JP5664170B2 - Urethane / urea resin having (meth) acryloyl group, active energy ray-curable adhesive containing the urethane / urea resin, and back surface protection sheet for solar cell - Google Patents

Description

The present invention relates to an active energy ray-curable urethane / urea resin suitably used for, for example, adhesives, inks, paints and the like. Specifically, the present invention relates to an active energy ray-curable urethane / urea resin suitable for an active energy ray-curable adhesive for forming a back surface protection sheet for solar cells.
Furthermore, the present invention provides a solar cell back surface protection sheet that is excellent in adhesion between sheet-like members and heat-and-moisture resistance, and that does not cause appearance defects or delamination due to the generation of bubbles in the adhesive layer at a high yield and low cost. The present invention relates to an active energy ray-curable adhesive that can be manufactured with good productivity.

  In recent years, solar cells have been attracting attention as a clean energy source free from environmental pollution due to an increase in awareness of environmental problems, and earnestly researched and put into practical use from the viewpoint of using solar energy as a useful energy resource. These solar cells are provided with a back surface protective sheet on the surface opposite to the surface on which sunlight is incident for the purpose of protecting the solar cell elements. Performances such as weather resistance, water vapor permeability, electrical insulation, mechanical properties, mounting workability, and the like are required for the back surface protection sheet for solar cells, and a laminate of several kinds of sheet-like members is generally used.

For the lamination of the sheet-like member, it is common to use a polyurethane adhesive that cures by reacting a hydroxyl group-containing resin as a main agent and an isocyanate compound as a curing agent (Patent Documents 1 and 2). .
By the way, when laminating | stacking a some sheet-like member and industrially producing the back surface protection sheet for solar cells, the thing of a long state is wound up in roll shape. However, since the polyurethane-based adhesive has a slow curing reaction, the adhesive layer in the laminated body wound up in a roll shape is likely to be insufficiently cured, and after winding up, the sheet-like member is likely to be displaced, resulting in a defective product occurrence rate. There was a problem that the yield was high and the yield was poor.
In addition, it is necessary to age for several days in a warehouse maintained at a high temperature in order to be fully cured. In this respect, the productivity is poor and the cost of electricity for maintaining the temperature of the warehouse is increased, resulting in an increase in production cost. There was also a problem.
Furthermore, the isocyanate compound as the curing agent not only reacts with the hydroxyl group-containing resin as the main agent, but also reacts with water in the air. Since the decarboxylation reaction occurs after reacting with water, bubbles were generated in the adhesive layer after laminating the sheet-like members, and there was a problem that appearance defects and delamination occurred.

  Patent Document 3 discloses a urethane acrylate obtained by reacting a polycarbonate diol, a bifunctional epoxy (meth) acrylate containing two hydroxyl groups and two ethylenically unsaturated groups in the molecule, and a polyisocyanate. An active energy ray-curable resin adhesive containing a photopolymerization initiator is disclosed, but when this is used as an adhesive for a solar cell back surface protection sheet, the adhesive strength between sheets and heat and humidity resistance are sufficient. It wasn't.

JP 2007-320218 A JP 2007-253463 A Japanese Laid-Open Patent Publication No. 2008-127475

  An object of the present invention is to provide a back surface protection sheet for solar cells that is excellent in adhesive strength and heat-and-moisture resistance between sheet-like members and that does not cause appearance defects or delamination due to the generation of bubbles in the adhesive layer, with high yield and low cost. The object is to provide an active energy ray-curable composition that can be produced with good productivity (no aging is required).

In the first invention , (meth) acrylic acid is added to the diol component (A) which does not have a (meth) acryloyl group, which has a diol component having a carbonate structure, and the epoxy group of a compound having two or more epoxy groups. To the urethane prepolymer (G) having an isocyanate group, which is formed by reacting a polyol component (B1) having a (meth) acryloyl group and having two or more hydroxyl groups and a polyisocyanate component (C). And a urethane-urea resin (E) having a (meth) acryloyl group obtained by further reacting the diamine component (D).

  The second invention relates to the urethane-urea resin (E) having a (meth) acryloyl group according to the invention, wherein the glass transition temperature is -60 to -10 ° C.

  A third invention relates to a urethane-urea resin (E) having a (meth) acryloyl group according to any one of the inventions, wherein the number average molecular weight is 5,000 to 150,000.

  According to a fourth invention, the urethane / urea resin (E) having a (meth) acryloyl group according to any one of the inventions, wherein the polyol component (B) has two or more (meth) acryloyl groups. About.

  A sixth invention relates to the urethane-urea resin (E) having a (meth) acryloyl group according to any one of the inventions, wherein the (meth) acryloyl group equivalent is 500 to 40,000.

  7th invention contains the urethane-urea resin (E) and epoxy resin (F) which have the (meth) acryloyl group in any one of the 2nd-6th invention, The active energy ray hardening property characterized by the above-mentioned. It relates to adhesives.

  The eighth invention relates to the active energy ray-curable adhesive according to the invention, wherein the epoxy resin (F) has a number average molecular weight of 500 to 5,000.

  9th invention is characterized by having urethane-urea resin (E) 50 to 85 weight% and epoxy resin (F) 5 to 40 weight% on the basis of solid content of an active energy ray hardening adhesive. The active energy ray-curable adhesive according to any one of the eighth to ninth inventions.

  In the tenth invention, at least two or more sheet-like members are laminated via the active energy ray-curable adhesive layer formed from the active energy ray-curable adhesive according to any one of the seventh to ninth inventions. It is related with the back surface protection sheet for solar cells formed.

  An eleventh aspect of the invention is a plastic film with a vapor deposition layer in which one of the sheet-like members is a metal foil or a metal oxide or a non-metal inorganic oxide is vapor-deposited on at least one surface of the plastic film. It is related with the back surface protection sheet for solar cells as described in the said invention characterized by the above-mentioned.

  12th invention is related with the back surface protection sheet for solar cells in any one of 10th-11th invention characterized by the glass transition temperature of an active energy ray hardening adhesive bond layer being -20-30 degreeC. .

  By the active energy ray-curable adhesive containing the urethane / urea resin (E) having a (meth) acryloyl group of the present invention, the adhesive strength between the sheet-like members and the heat-and-moisture resistance are excellent, and bubbles are generated in the adhesive layer. It is possible to provide a solar cell back surface protection sheet free from defects in appearance and delamination with high yield and low cost with high productivity (no aging is required).

Hereinafter, embodiments of the present invention will be described in detail.
The urethane / urea resin (E) having a (meth) acryloyl group of the present invention comprises a diol component (A) having no (meth) acryloyl group and a (meth) acryloyl group having a diol component having a carbonate structure as an essential component. The urethane prepolymer (G) having an isocyanate group obtained by reacting the polyol component (B) having two or more hydroxyl groups with the polyisocyanate component (C) is further reacted with the diamine component (D). Can be obtained.
The urethane prepolymer (G) can be obtained by reacting the polyisocyanate component (C) with a hydroxyl group derived from (A) and (B) under conditions where the isocyanate group becomes excessive.
In addition, if the diamine component (D) is less than the isocyanate group in the urethane prepolymer (G), the isocyanate group remains. In that case, use a monool component or a monoamine component to stop the terminal. Can do.

  In this specification and claims, when the notation “(meth) acrylo” is used for a certain compound, the compound is obtained by replacing “(meth) acrylo” with “acrylo”, and “ This means that any compound obtained by replacing “(meth) acrylo” with “methacrylo” may be used. Further, in this specification, when the expression “(meth) acryl” is used for a certain functional group, the functional group is a functional group obtained by replacing “(meth) acryl” with “acryl”, and “( It means that any of the functional groups obtained by replacing “meth) acryl” with “methacryl” may be used. Furthermore, in this specification, when the expression “(meth) acrylate” is used for a certain compound, the compound is a compound in which “(meth) acrylate” is replaced with “acrylate”, and “(meth) acrylate” "Is replaced with" methacrylate "which means any compound.

The glass transition temperature of the urethane / urea resin (E) is preferably −60 to −10 ° C., more preferably −50 to −20 ° C. When the glass transition temperature is lower than −60 ° C., the adhesive force between the sheet-like members tends to be lowered during the moisture and heat resistance test. When the glass transition temperature is higher than −10 ° C., when the sheet-like member is stacked on the curable adhesive layer or the cured adhesive layer, the wettability of the adhesive layer with respect to the sheet-like member becomes poor, As a result, the adhesive force between the sheet-like members tends to be insufficient.
The glass transition temperature of the urethane / urea resin (E) was measured using DSC “RDC220” manufactured by Seiko Instruments Inc. A sample obtained by drying a urethane resin solution, about 10 mg is weighed on an aluminum pan, set in a DSC apparatus, cooled to −100 ° C. with liquid nitrogen, and then heated at 10 ° C./min to obtain a glass from a DSC chart. The transition temperature was calculated.

The number average molecular weight (Mn) of the urethane / urea resin (E) is preferably 5000 to 150,000, and more preferably 10,000 to 100,000. If the number average molecular weight is less than 5000,
The cohesive force of the adhesive layer after curing becomes low, and the adhesive force between the sheet-like members tends to be lowered during the moisture and heat resistance test. If the number average molecular weight is larger than 150,000, the active energy ray-curable adhesive tends to be highly viscous, the solubility with other components constituting the active energy ray-curable adhesive tends to be poor, and curing occurs. When the sheet-like member is stacked on the adhesive adhesive layer or the cured adhesive layer, the wettability of the adhesive layer to the sheet-like member becomes poor, and as a result, the adhesive force between the sheet-like members tends to be insufficient, Problems occur.
The number average molecular weight of the urethane / urea resin (E) was measured by using GPC (gel permeation chromatography) “HPC-8020” manufactured by Tosoh Corporation and tetrahydrofuran as the solvent. The number average molecular weight was calculated in terms of standard polystyrene.

The urethane / urea resin (E) preferably has a (meth) acryloyl group equivalent of 500 to 40000, more preferably 1000 to 30000, from the viewpoint of compatibility between the adhesive force between the sheet-like members and heat and moisture resistance. The (meth) acryloyl group equivalent referred to here is the number average molecular weight per (meth) acryloyl group in the urethane resin molecule. In other words, the (meth) acryloyl group equivalent is the number average molecular weight of the urethane / urea resin (E) divided by the average number of (meth) acryloyl groups contained in one molecule of the urethane / urea resin (E). It is a value obtained by doing.
If the (meth) acryloyl group equivalent is less than 500, the adhesive force between the sheet-like members tends to be insufficient due to curing shrinkage during active energy ray curing. On the other hand, when the (meth) acryloyl group equivalent is larger than 40000, the adhesive layer is not sufficiently cross-linked, and the adhesive force between the sheet-like members tends to be reduced during the wet heat resistance test.

The urethane / urea resin (E) preferably has a urethane bond equivalent of 200 to 3000, more preferably 250 to 2000, from the viewpoints of adhesive strength between sheet-like members and heat and humidity resistance. The urethane bond equivalent referred to here is the number average molecular weight per urethane bond in one molecule of the urethane / urea resin (E). In other words, the urethane bond equivalent is a value obtained by dividing the number average molecular weight of the urethane-urea resin (E) by the average value of the number of urethane bonds contained in one molecule of the urethane-urea resin (E). It is.
When the urethane bond equivalent is less than 200, the cohesive force of the curable adhesive layer or the cured adhesive layer increases, and when the sheet-like member is overlaid on the curable adhesive layer or the cured adhesive layer, the sheet shape The wettability of the adhesive layer to the member becomes poor, and the adhesive force tends to be reduced. On the other hand, when the urethane bond equivalent is larger than 3000, the number of urethane bonds having good moisture and heat resistance decreases, and the adhesive force between the sheet-like members tends to decrease after the moisture and heat resistance test.

In addition, the urethane / urea resin (E) preferably has a urea bond equivalent of 1000 to 20000, more preferably 2000 to 15000, from the viewpoints of adhesive strength between sheet-like members and resistance to moist heat. The urethane bond equivalent referred to here is the number average molecular weight per urea bond in one molecule of the urethane / urea resin (E). In other words, the urethane bond equivalent is a value obtained by dividing the number average molecular weight of the urethane / urea resin (E) by the average value of the number of urea bonds contained in one molecule of the urethane / urea resin (E). It is.
When the urea bond equivalent is less than 1000, the cohesive force of the curable adhesive layer or the cured adhesive layer increases, and when the sheet-like member is overlaid on the curable adhesive layer or the cured adhesive layer, the sheet shape The wettability of the adhesive layer to the member becomes poor, and the adhesive force tends to be reduced. On the other hand, when the urea bond equivalent is larger than 20000, the urea bond having good wet heat resistance is reduced, and the adhesive force between the sheet-like members tends to decrease after the wet heat resistance test.

As the diol component (A) having no (meth) acryloyl group, which is used for the formation of the urethane / urea resin (E) and having a diol component having a carbonate structure as an essential component, a (meth) acryloyl group having a carbonate structure is used. The diol (A1) not having an essential component can be used in combination with the diol component (A2) having no carbonate structure.
The carbonate structure is a structure containing a carbonate group (—O—CO—O— group). The urethane / urea resin (E) contains a carbonate group derived from the diol component (A).
In urethane / urea resin (E), diol component (A), polyol component (B), polyisocyanate component (C), diamine component (D), and monool component or monoamine component that can be used as necessary The concentration of the carbonate group with respect to the total solid content is preferably in the range of 2 mmol / g to 8 mmol / g, and more preferably in the range of 3 mmol / g to 7 mmol / g. The density | concentration of carbonate group said here is the diol component (A), the polyol component (B), the polyisocyanate component (C), the diamine component (D), and the monool component or monoamine which can be used as needed. It is the amount of carbonate groups contained in 1 g of the total solid content of the components. If this concentration is less than 2 mmol / g, the solubility of the urethane / urea resin in the solvent tends to be poor, or sufficient heat-and-moisture resistance tends not to be obtained, and if it is greater than 8 mmol / g, sufficient adhesion is obtained. It tends to be impossible.

As the diol component (A1) having a carbonate structure used for the formation of the urethane / urea resin (E), for example, at least one kind of diol and a carbonate ester are used as raw materials to cause a transesterification reaction. can get.
Examples of the diol used as the raw material include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8 -Octanediol, 1,9-nonanediol, 1,10-decanediol, 1,5-hexanediol, 2-methyl-1,8-octanediol, neopentyl glycol, 2-isopropyl-1,4-butanediol 2-ethyl-1,6-hexanediol, 3-methyl-1,5-pentanediol, 2,4-dimethyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, , 3-butanediol, 2-ethyl-1,3-hexanediol, 2-butyl-2-ethyl-1,3-propanedio 1,3-cyclohexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 2-bis (4-hydroxycyclohexyl) -propane, hydrogenated bisphenol A, hydrogenated bisphenol F, and the like. These can be used alone or in combination of two or more. Examples of such a diol component (A1) include ETERNACOLL UC-100, ETERNACOLL UM-90 (3/1), ETERNACOLL UM-90 (1/1), and ETERNACOLL UM-90 (1/3) manufactured by Ube Industries, Ltd. , ETERNACOLL UC-100, Kuraray Co., Ltd. C-1090, C-2050, C-2090, C-3090, Ube Industries, Ltd. ETERNACOLLUH-50, ETERNACOLLUH-100, ETERNACOLLUH-200, ETERNACOLL UH-300 ETERNACOLL UH-50-200, ETERNACOLL UH-50-100, Asahi Kasei Chemicals T6002, T6001, T5652. Examples include T4672, Plaxel CD CD205, Plaxel CD CD205PL, Plaxel CD CD210, Plaxel CD CD210PL, Plaxel CD CD220, Plaxel CD CD220PL, etc. manufactured by Daicel Chemical Industries, Ltd. These may be used alone or in combination of two or more.
In addition, it is preferable that the number average molecular weight of the diol component (A1) which has a carbonate structure is about 500 or more, and it is preferable that it is 500-5000. When the diol component (A1) having a carbonate structure having a number average molecular weight of less than 500 is used, the urethane bond group equivalent tends to be small. If the urethane bond group equivalent becomes too small, the cohesive force of the curable adhesive layer or the cured adhesive layer becomes too large. When a sheet-like member is stacked on or on a curable adhesive layer having too much cohesive force, the wettability of the adhesive layer to the sheet-like member becomes poor, and as a result, the adhesive force between the sheet-like members decreases. Tend to. On the other hand, when the number average molecular weight of the diol component (A1) having a carbonate structure exceeds 5000, there is a concern that the adhesive strength between the sheet-like members may be reduced due to insufficient cohesive force.

Examples of the diol component (A2) having no carbonate structure include so-called prepolymers such as polyester diol, polyethylene glycol, and polypropylene glycol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, and 1,6-hexane. Diol, neopentyl glycol, 1,4-butylene glycol, 1,9-nanonediol, aliphatic diol such as 3-methyl-1,5-pentanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, Examples include diols having an alicyclic structure such as 1,4-cyclohexanedimethanol, 2-bis (4-hydroxycyclohexyl) -propane, hydrogenated bisphenol A, and hydrogenated bisphenol F. Luo alone or in combination of two or more. When the diol component having an alicyclic structure is used, the wet strength and heat resistance of the adhesive strength is excellent, but the initial bond strength (adhesive strength before the wet heat resistance test) tends to decrease. Therefore, an alicyclic structure can be appropriately introduced as required.
When the diol components (A1) to (A2) are used in combination, the proportion of the diol component (A2) in the total amount thereof is preferably 20% by weight or less, and more preferably 10% by weight or less. When this ratio is large, the effects of the polycarbonate skeleton and the alicyclic skeleton on the heat and moisture resistance and the adhesive strength tend to be small, and it is difficult to achieve both excellent heat and heat resistance and excellent adhesive strength.

The polyol component (B) having a (meth) acryloyl group used as a raw material for the urethane / urea resin (E) has two or more hydroxyl groups. By using the polyol component (B), a (meth) acryloyl group can be introduced not only into the terminal of the main chain of the urethane / urea resin (E) but also into the side chain. The amount of (meth) acryloyl group introduced can be controlled by controlling the composition of the diol components (A1) and (A2) and the polyol component (B).
If a polyol component (B) having at least two (meth) acryloyl groups is used, even if it is a high molecular weight urethane / urea resin (E), the (meth) acryloyl group can be efficiently introduced. Therefore, the active energy ray curability is improved, and as a result, the heat and moisture resistance can be improved.

As the polyol component (B) having a (meth) acryloyl group and two or more hydroxyl groups in one molecule, a compound in which (meth) acrylic acid is added to the epoxy group of a compound having two or more epoxy groups ( B1), glycerin mono (meth) acrylate, trimethylolethane mono (meth) acrylate, trimethylolpropane mono (meth) acrylate, pentaerythritol mono (meth) acrylate, pentaerythritol di (meth) acrylate, dipentaerythritol tetra (meta) ) Acrylate, dipentaerythritol tri (meth) acrylate, and the like. These may be used alone or in combination of two or more.
Compound (B1) in which (meth) acrylic acid is added to an epoxy group of a compound having two or more epoxy groups has a high purity as a polyol, and a urethane / urea resin (E) synthesized having a (meth) acryloyl group Since reaction control at the time is easy, it is more preferable as the polyol component (B).

  As the compound (B1) in which (meth) acrylic acid is added to the epoxy group of a compound having two or more epoxy groups, for example, a (meth) acrylic acid adduct of propylene glycol diglycidyl ether, 1,6-hexane (Meth) acrylic acid adduct of diol diglycidyl ether, (meth) acrylic acid adduct of ethylene glycol diglycidyl ether, (meth) acrylic acid adduct of 1,4-butanediol diglycidyl ether, 1,5-pentane (Meth) acrylic acid adduct of diol diglycidyl ether, (meth) acrylic acid adduct of 1,6-hexanediol diglycidyl ether, (meth) acrylic acid adduct of 1,9-nonanediol diglycidyl ether, Neo (Meth) acrylic acid adduct of pentyl glycol diglycidyl ether (Meth) acrylic acid adduct of bisphenol A diglycidyl ether, (meth) acrylic acid adduct of hydrogenated bisphenol A diglycidyl ether, and (meth) acrylic acid adduct of glycerin diglycidyl ether.

  Examples of the polyisocyanate component (C) used in the present invention include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, 1,5-naphthalene diisocyanate, Examples include an adduct, a burette, and an isocyanurate formed of a single isocyanate compound selected from hexamethylene diisocyanate, hydrogenated diphenylmethane diisocyanate, and the like, or at least one selected from the above isocyanate compounds. More than one type may be used in combination. From the viewpoint of weather resistance, the diisocyanate component is preferably an alicyclic diisocyanate.

  In the urethane prepolymer (G) having an isocyanate group used in the present invention, the diol component (A1), (A2), the polyol component (B) and the polyisocyanate component (C) described above are subjected to an isocyanate group excess condition. It is made to react with. For example, the urethane prepolymer (G) can be obtained by reacting the isocyanate group in the range of 1 to 10 moles with respect to 1 mole of the hydroxyl group. The isocyanate group is 1.01 with respect to 1 mole of the hydroxyl group. More preferably, it is -6 mol.

The diamine component (D) used in the present invention is a compound having two primary or secondary amino groups, and is used for the purpose of chain extension of the NCO group-terminated urethane prepolymer (G).
As the diamine (D), a known diamine can be used. Specifically,
Aliphatic polyamines such as ethylenediamine, propylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, 2,2,4-trimethylhexamethylenediamine, decanediamine, tolylenediamine, hydrazine, piperazine;
Cycloaliphatic polyamines such as isophoronediamine and dicyclohexylmethane-4,4′-diamine;
Aromatic polyamines such as phenylenediamine and xylylenediamine;
Furthermore, the dimer diamine etc. which converted the carboxyl group of dimer acid into the amino group etc. are mentioned, These may be individual or may use 2 or more types together.
By performing a chain extension reaction with the diamine component, a urea bond having a higher cohesive force than that of the urethane bond is formed, and the moisture and heat resistance of the formed adhesive layer is improved.
If the diamine component (D) is less than the isocyanate group in the urethane prepolymer (G), the isocyanate group remains. In that case, use a monool component or a monoamine component to stop the terminal. Can do.

The urethane / urea resin (E) having a (meth) acryloyl group of the present invention may be produced by reacting raw materials in the absence of a solvent or may be produced by reacting in an organic solvent.
Organic solvents include ketone compounds such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, ester compounds such as methyl acetate, ethyl acetate, butyl acetate, ethyl lactate and methoxyethyl acetate, ethers such as diethyl ether and ethylene glycol dimethyl ether. Various solvents such as aromatic compounds such as a series compound, aromatic compounds such as toluene and xylene, aliphatic compounds such as pentane and hexane, and halogenated hydrocarbon compounds such as methylene chloride, chlorobenzene, and chloroform can be used.

  In the synthesis of the urethane / urea resin (E), a catalyst can be added as necessary. For example, metal catalysts such as dibutyltin diacetate, dibutyltin dilaurate, dioctyltin dilaurate, and dibutyltin dimaleate; -Diaza-bicyclo (5,4,0) undecene-7,1,5-diazabicyclo (4,3,0) nonene-5,6-dibutylamino-1,8-diazabicyclo (5,4,0) undecene- Tertiary amines such as 7; reactive tertiary amines such as triethanolamine, and the like. These may be used alone or in combination of two or more.

Next, the active energy ray-curable adhesive of the present invention will be described.
The active energy ray-curable adhesive of the present invention includes a urethane / urea resin having an (meth) acryloyl group (E) having a glass transition temperature of −60 to −10 ° C., and an epoxy resin. (F).

  Examples of the epoxy resin (F) used in the present invention include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, brominated bisphenol A type epoxy resin, hydrogenated bisphenol A type epoxy resin, and biphenol type. Epoxy resin, bixylenol type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, brominated phenol novolac type epoxy resin, bisphenol A novolac type epoxy resin, trihydroxyphenylmethane type epoxy resin, tetraphenylolethane type Glycidyl ether compounds such as epoxy resins, phenol novolac epoxy resins containing naphthalene skeleton, and phenol novolac epoxy resins containing dicyclopentadiene skeleton; Glycidyl ester compounds such as diglycidyl phthalate; Alicyclic epoxy resins such as EHPE-3150 manufactured by Daicel Chemical Industries; heterocyclic epoxy resins such as triglycidyl isocyanurate; N, N, N ′, N Examples include glycidylamines such as' -tetraglycidylmetaxylenediamine, and epoxy compounds such as a copolymer of glycidyl (meth) acrylate and a compound having an ethylenically unsaturated double bond. These may be used alone or in combination of two or more.

  By including the epoxy resin (F) in the active energy ray-curable adhesive, the functional group generated by the decomposition of the urethane / urea resin (E) during the wet heat resistance test can be reacted with the epoxy group, and the adhesive layer It is possible to suppress a decrease in the molecular weight of the resin and to suppress a decrease in adhesive strength.

  From the viewpoint of wet heat resistance of the adhesive layer and compatibility with the urethane / urea resin (E), the epoxy resin (F) is preferably a bisphenol type epoxy resin having a number average molecular weight of 500 to 5,000. When the number average molecular weight of the epoxy resin is smaller than 500, the adhesive layer tends to be soft and sufficient moisture and heat resistance tends not to be obtained. When the number average molecular weight of the epoxy resin is larger than 5000, the compatibility with other components of the active energy ray-curable adhesive deteriorates, and the adhesive tends to become cloudy.

The active energy ray-curable adhesive of the present invention can contain a compound having a (meth) acryloyl group other than the urethane / urea resin (E). Examples of the compound having a (meth) acryloyl group other than the urethane / urea resin (E) contained in the active energy ray-curable adhesive of the present invention include, for example, a relatively low molecular weight (meth) acrylate monomer, and to some extent Examples include so-called prepolymers and polymers having a large molecular weight.
Examples of relatively low molecular weight (meth) acrylate monomers include monofunctional (meth) acrylate monomers such as 4-hydroxybutyl (meth) acrylate, isobornyl (meth) acrylate, lauryl (meth) acrylate, and acryloylmorpholine; 1,9-nonanediol di (meth) acrylate, bisphenol A di (meth) acrylate, pentaerythritol tri (meth) acrylate, tris ((meth) acryloxyethyl) isocyanurate, and dipentaerythritol hexa (meth) A polyfunctional (meth) acrylate monomer such as acrylate can be exemplified.
Examples of the prepolymer and polymer include radically polymerizable prepolymers having (meth) acryloyl groups such as polyester (meth) acrylate, polyurethane (meth) acrylate, epoxy (meth) acrylate, and (meth) acrylated maleic acid-modified polybutadiene. Mention may be made of polymers or polymers.
These may be used alone or in combination of two or more.

  The active energy ray-curable adhesive of the present invention can contain a photopolymerization initiator, a compound having no active energy ray curability, and the like.

A known photopolymerization initiator can be used as the photopolymerization initiator. For example, benzophenone, 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2-benzyl-2-dimethylamino- 1- (4-morpholinophenyl) butanone-1,2-hydroxy-2-methyl-1-phenylpropan-1-one, 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropane-1 -One, benzoin methyl ether, benzoin ethyl ether, benzoin isobutyl ether, benzoin isopropyl ether, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, 2-hydroxy-2-methyl- (4- (1- Methylvinyl) phenyl) propa Oligomers, isopropylthioxanthone, (4- (methylphenylthio) phenyl) phenylmethane, 2,4-diethylthioxanthone, 2-chlorothioxanthone, ethyl anthraquinone, etc., and these may be used alone or in combination of two or more. .
In addition to the photopolymerization initiator, aliphatic amines such as n-butylamine, triethylamine, ethyl p-dimethylaminobenzoate, and aromatic amines may be used in combination as a sensitizer.

  The active energy ray-curable adhesive of the present invention can further contain other compounds having no active energy ray curability. Compounds that do not have active energy ray curability include acrylic resins, polyester resins, amino resins, xylene resins, petroleum resins and other curing agents, isocyanate compounds, aziridine compounds and other curing agents, aluminum chelate compounds, silane coupling agents, and ultraviolet rays. Absorbers, antioxidants, leveling agents, antifoaming agents, adhesion aids, dispersants, drying regulators, antifriction agents, and the like can be blended.

The active energy ray-curable adhesive of the present invention has a urethane / urea resin (E) of 50 to 85% by weight and an epoxy resin (F) of 5 to 40% by weight based on the solid content of the active energy ray curable adhesive. %, A compound having a (meth) acryloyl group other than the urethane / urea resin (E) is preferably contained in an amount of 0 to 30% by weight, the urethane / urea resin (E) in an amount of 60 to 85% by weight, and an epoxy resin (F). It is more preferable to contain 10 to 34% by weight of the compound having a (meth) acryloyl group other than the urethane / urea resin (E).
When the amount of the urethane / urea resin (E) is less than 50% by weight, the cohesive force of the adhesive layer is lowered, and the adhesive force and heat-and-moisture resistance tend to be insufficient. If it exceeds 85% by weight, the heat and humidity resistance tends to be lowered.
When the amount of the epoxy resin (F) is less than 5% by weight, sufficient moisture and heat resistance tends to be not obtained. When the amount is more than 40% by weight, the active energy ray-curable component decreases, and the urethane having a (meth) acryloyl group. -Urea resin (E) does not fully harden | cure and there exists a tendency for moisture-heat resistance and adhesive force not to be fully obtained.
If the amount of the compound having a (meth) acryloyl group other than the urethane / urea resin (E) is more than 30% by weight, the adhesive force tends to be insufficient due to shrinkage during curing.

The active energy ray-curable adhesive layer constituting the solar cell back surface protective sheet of the present invention preferably has a glass transition temperature of -20 ° C to 30 ° C. In other words, the active energy ray-curable adhesive is preferably one that can form an adhesive layer having a glass transition temperature of −20 ° C. to 30 ° C. when cured by irradiation with active energy rays. More preferably, it is −10 ° C. to 20 ° C.
When the glass transition temperature exceeds 30 ° C., when the sheet-like member is stacked on the curable adhesive layer or on the cured adhesive layer, the wettability of the adhesive layer with respect to the sheet-like member becomes poor, and as a result, the sheet shape There exists a tendency for the adhesive force between members to fall. On the other hand, when the glass transition temperature is less than −20 ° C., the cohesive force of the adhesive layer is lowered, and the adhesive force and the heat and humidity resistance tend to be insufficient.

The back surface protection sheet for solar cells of the present invention is formed by laminating at least two or more sheet-like members via an active energy ray-curable adhesive layer formed by the active energy ray-curable adhesive of the present invention. It is.
The sheet-like member constituting the back surface protection sheet for solar cell of the present invention is not particularly limited, and a plastic film, a metal foil, a material obtained by depositing a metal oxide or a non-metal oxide on the plastic film, etc. Can be mentioned.

As the plastic film, for example, a polyester resin film such as polyethylene terephthalate, polynaphthalene terephthalate,
Polyethylene resin film, polypropylene resin film, polyvinyl chloride resin film, polycarbonate resin film, polysulfone resin film, poly (meth) acrylic resin film,
Fluorine resins such as polyvinyl fluoride, polyvinylidene fluoride, polychlorotrifluoroethylene, polyethylene tetrafluoroethylene, polytetrafluoroethylene, tetrafluoroethylene perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene copolymer A film etc. are mentioned.
A film in which these plastic films are used as a support and are coated with an acrylic or fluorine-based paint, a multilayer film in which polyvinylidene fluoride, an acrylic resin, or the like is laminated 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.

An example of the metal foil is aluminum 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.

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 resin film, polycarbonate resin film,
Metal foil such as plastic film or aluminum foil with vapor-deposited metal oxide or non-metallic inorganic oxide with water vapor barrier property to prevent output drop due to the influence of water in solar cells, and appearance defects due to light deterioration In order to prevent this, a back protective sheet for solar cells is preferred in which a fluorine resin film with good weather resistance is laminated.

The solar cell back surface protection sheet of the present invention can be obtained, for example, by the following production method.
[1] After an active energy ray-curable adhesive is applied to one (meaning “any”) sheet-like member and another sheet-like member is stacked on the formed active energy ray-curable adhesive layer The active energy ray is irradiated from one sheet-like member side or from both sheet-like member sides, and an active energy ray-curing adhesive layer is formed between both sheet-like members, or

  [2] An active energy ray-curable adhesive layer is formed by coating an active energy ray-curable adhesive layer on one (meaning “any”) sheet-like member, and the active energy ray-curable adhesive layer is formed. After irradiating active energy rays from the side and / or from the sheet-like member side to form an active energy ray-curing adhesive layer, another sheet-like member is laminated on the active energy ray-curing adhesive layer, or

[3] An active energy ray-curable adhesive layer is formed by coating an active energy ray-curable adhesive layer on one (meaning “any”) sheet-like member, and the active energy ray-curable adhesive layer is formed. After irradiating active energy rays from the side and / or from the sheet-like member side to form an active energy ray-curable adhesive layer, another sheet-like member-forming coating solution is applied to the active energy ray-curable adhesive layer. The back surface protection sheet for solar cells of this invention can be manufactured by crafting and forming another sheet-like member with a heat | fever or an active energy ray.
Other sheet-form member forming coating solutions used in the method of [3] include polyester resin solutions, polyethylene resin solutions, polypropylene resin solutions, and polyvinyl chloride resin solutions that can be used to form plastic films. Polycarbonate resin solution, polysulfone resin solution, poly (meth) acrylic resin solution, fluorine resin solution and the like.

In the method of [1], the active energy ray-curable adhesive layer is irradiated with the active energy ray-curable adhesive layer sandwiched between two sheet-like members. It has the advantage of being less susceptible to oxygen inhibition. However, on the other hand, since the active energy ray-curable adhesive layer is irradiated with the active energy ray through the sheet-like member, regardless of whether the active energy ray-curable adhesive is radically polymerizable, It is important to use a sheet-like member that can transmit active energy rays without being attenuated as much as possible.
The method [2] has completely opposite characteristics to the method [1]. That is, the active energy ray is irradiated in a situation where oxygen inhibition is likely to occur, but it has the advantage that the options of sheet-like members that can be used are widened.
In the method of [3], the active energy ray is irradiated in a situation where it is susceptible to oxygen inhibition in the first step, but on the other hand, another sheet-like member forming coating liquid is applied to the formed adhesive layer, Since another sheet-like member is formed, there is an advantage that it is easy to ensure the adhesive force between the adhesive layer and the other sheet-like member.
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.
In addition, in the case of [1] and [2], when another sheet-like member is stacked on the curable adhesive layer or on the cured adhesive layer, they can be stacked under heating and / or pressure conditions.

When the active energy ray-curable adhesive is applied to the sheet-like member, a solvent may be included within a range that does not affect the sheet-like member in the drying step in order to adjust the coating liquid to an appropriate viscosity. . When the active energy ray-curable adhesive contains a solvent, after the solvent is volatilized, the active energy ray-curable adhesive can be cured by irradiation with active energy rays.
Solvents include ketone compounds such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, ester compounds such as methyl acetate, ethyl acetate, butyl acetate, ethyl lactate and methoxyethyl acetate, ethers such as diethyl ether and ethylene glycol dimethyl ether. Compounds, aromatic compounds such as toluene and xylene, aliphatic compounds such as pentane and hexane, halogenated hydrocarbon compounds such as methylene chloride, chlorobenzene and chloroform, alcohols such as ethanol, isopropyl alcohol and normal butanol, and water It is done. These solvents may be used alone or in combination of two or more.

  In the present invention, the active energy ray-curable adhesive is applied to the sheet-like member as a comma coater, dry laminator, roll knife coater, die coater, roll coater, bar coater, gravure roll coater, reverse roll coater, blade. Examples include coaters, gravure coaters, and micro gravure coaters.

The amount of adhesive applied to the sheet-like member is preferably about 0.1 to 50 g / m ² in terms of dry film thickness.

  Examples of the active energy ray irradiated to cure the active energy ray-curable adhesive include ultraviolet rays, electron beams, γ rays, infrared rays, and visible rays.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the examples. In the examples, all parts and% indicate parts by weight and% by weight.
Below, it shows about the synthesis | combination of the urethane urea resin (E) which has a (meth) acryloyl group, an active energy ray hardening adhesive, and the preparation method of the back surface protection sheet for solar cells.

Example 1 (Synthesis of NCO-terminated urethane prepolymer)
1700.0 parts of toluene, 2240.5 parts of Kuraray polyol C-3090, epoxy ester 70PA in a polymerization reactor of a polymerization reactor equipped with a polymerization tank, a stirrer, a thermometer, a reflux condenser, a nitrogen introduction pipe, and a dropping tank 24.5 parts and isophorone diisocyanate 284.9 parts were added, and the temperature in the polymerization tank was raised to 80 ° C. while stirring under a nitrogen stream. When the temperature reached 80 ° C., 0.3 part of dibutyltin dilaurate was added and the reaction was continued for 4 hours. Thereafter, 2125 parts of toluene and 0.4 part of acetylacetone were added and cooled to obtain an NCO group-terminated urethane prepolymer (G-1) solution having a solid content of 40%.

Examples 2-13
According to the composition of Table-1, the reaction was performed in the same manner as in Example 1 to obtain urethane prepolymer (G-2) to (G-13) solutions.

Example 14 (Synthesis of urethane / urea resin having (meth) acryloyl group)
In a polymerization tank of a polymerization reactor equipped with a polymerization tank, a stirrer, a thermometer, a reflux condenser, a nitrogen introduction pipe, and a dropping tank, the NCO group-terminated urethane prepolymer (G-1) solution obtained in Example 1 was 2000 The temperature in the polymerization tank was raised to 40 ° C. while stirring under a nitrogen stream. When the temperature reached 40 ° C., 8.2 parts of isophoronediamine was charged into the dropping tank and dropped over 2 hours. Thereafter, 4.2 parts of 2-amino-2-methyl-1-propanol was added to obtain a urethane / urea resin (E-1) solution having a (meth) acryloyl group. The properties are shown in Table-2.

Examples 15-32
Using the NCO group-terminated urethane prepolymers (G-1) to (G-11) obtained in Examples 1 to 13, (meth) acryloyl groups in the same manner as in Example 14 according to the composition of Table-2 Urethane / urea resins having a (meth) acryloyl group were obtained, and urethane / urea resin solutions (E-2) to (E-19) were obtained. The properties are shown in Tables 2 and -3.

Comparative Example 1 (Synthesis of urethane acrylate)
In a polymerization tank of a polymerization reactor equipped with a polymerization tank, a stirrer, a thermometer, a reflux condenser, a nitrogen introduction pipe, and a dropping tank, 869.4 parts of methyl ethyl ketone (MEK) and Kuraray polyol C-3090 (manufactured by Kuraray Co., Ltd.) 834.1 parts and 41.7 parts of cyclohexanedimethanol (CHDM) were charged, and the temperature in the polymerization tank was raised to 80 ° C. while stirring under a nitrogen stream. When the temperature reached 80 ° C, 0.5 parts of dibutyltin dilaurate (DBTDL) was added. Next, 124.2 parts of isophorone diisocyanate (IPDI) and 124.2 parts of MEK were mixed, put into a dropping tank, and dropped into the polymerization tank over 2 hours. One hour after the completion of dropping, 0.05 part of DBTDL was added, and then the reaction was continued until the infrared absorption peak of the isocyanate group disappeared with an infrared spectrophotometer, and it was confirmed that the absorption peak of the isocyanate group had completely disappeared. A urethane resin having a number average molecular weight of 44000, a weight average molecular weight of 76000, and a hydroxyl value of 2.55 mgKOH / g was obtained.
Next, the temperature of the polymerization tank was lowered to 60 ° C., and 6.4 parts of 2-acryloyloxyethyl isocyanate having one isocyanate group and one acryloyl group (Karenz AOI, Showa Denko) and MEK were added. A mixture with 6.4 parts was added to the polymerization tank, the reaction was performed at 60 ° C., and the reaction was continued until the infrared absorption peak of the isocyanate group completely disappeared with an infrared spectrophotometer. The temperature of the polymerization tank was lowered to 40 ° C., 500.0 parts of MEK was added, and a urethane acrylate (H-1) solution having a solid content of 40% was obtained. The properties of (H-1) are shown in Table-4.

Comparative Example 2 (Synthesis of urethane acrylate)
862.5 parts of methyl ethyl ketone (MEK) and Kuraray polyol C-3090 (manufactured by Kuraray Co., Ltd.) were added to the polymerization tank of a polymerization reactor equipped with a polymerization tank, a stirrer, a thermometer, a reflux condenser, a nitrogen inlet tube, and a dropping tank. 826.7 parts and 41.3 parts of cyclohexanedimethanol (CHDM) were charged, and the temperature in the polymerization tank was raised to 80 ° C. while stirring under a nitrogen stream. When the temperature reached 80 ° C, 0.5 parts of dibutyltin dilaurate (DBTDL) was added. Next, 132.0 parts of isophorone diisocyanate (IPDI) and 132.0 parts of MEK were mixed, put into a dropping tank, and dropped into the polymerization tank over 2 hours. One hour after the completion of dropping, 0.05 part of DBTDL was added and the reaction was continued for 3 hours to obtain a urethane resin having a number average molecular weight of 42000, a weight average molecular weight of 72000, and an NCO value of 2.67 mgKOH / g.
Next, the temperature of the polymerization tank is lowered to 60 ° C., and a mixture of 5.5 parts of hydroxyethyl acrylate (HEA) and 5.5 parts of MEK is added to the polymerization tank and reacted at 60 ° C. The reaction was continued until the infrared absorption peak of the isocyanate group completely disappeared with an infrared spectrophotometer. The temperature of the polymerization tank was lowered to 40 ° C., 500.0 parts of MEK was added, and a urethane acrylate (H-2) solution having a solid content of 40% was obtained. The properties of (H-2) are shown in Table-4.

Comparative Example 3 (Synthesis of urethane acrylate)
In a polymerization tank of a polymerization reactor equipped with a polymerization tank, a stirrer, a thermometer, a reflux condenser, a nitrogen introduction pipe, and a dropping tank, 716.6 parts of methyl ethyl ketone (MEK) and Kuraray polyol P-3010 (manufactured by Kuraray Co., Ltd.) 827.2 parts, 39.8 parts of cyclohexanedimethanol (CHDM), and 8.7 parts of epoxy ester 70PA (manufactured by Kyoeisha Chemical Co., Ltd.), which is a compound obtained by adding 2 mol of acrylic acid to propylene glycol diglycidyl ether, While stirring in a nitrogen stream, the temperature in the polymerization tank was raised to 80 ° C. When the temperature reached 80 ° C, 0.5 parts of dibutyltin dilaurate (DBTDL) was added.
Next, a mixture of 124.3 parts of isophorone diisocyanate (IPDI) and 124.3 parts of MEK was dropped from the dropping tank into the polymerization tank over 2 hours. One hour after the completion of dropping, 0.05 part of DBTDL was added, and then the reaction was continued until the infrared absorption peak of the isocyanate group disappeared with an infrared spectrophotometer, and it was confirmed that the absorption peak of the isocyanate group had completely disappeared. Finished the reaction. The temperature of the polymerization tank was lowered to 40 ° C., 500.0 parts of MEK was added, and a urethane acrylate (H-3) solution having a solid content of 40% was obtained. The properties of (H-3) are shown in Table-4.

Comparative Examples 4 to 5 (Synthesis of urethane acrylate)
According to the composition of Table-4, the urethane acrylate (H-4) to (H-5) solutions were obtained in the same manner as in Comparative Example 3. Properties of each urethane acrylate are shown in Table-4.

Comparative Example 6
In a polymerization tank of a polymerization reactor equipped with a polymerization tank, a stirrer, a thermometer, a reflux condenser, a nitrogen inlet pipe, and a dropping tank, 1000.0 parts of toluene and 780.5 of Kuraray polyol C-3090 (manufactured by Kuraray Co., Ltd.) Part, 39.0 parts of cyclohexanedimethanol (CHDM) and 180.5 parts of isophorone diisocyanate were charged, and the temperature in the polymerization tank was raised to 80 ° C. with stirring under a nitrogen stream. When the temperature reached 80 ° C., 0.5 part of dibutyltin dilaurate was added and the reaction was continued for 4 hours. Thereafter, 500.0 parts of methyl ethyl ketone (MEK) and 0.4 part of acetylacetone were added and cooled to obtain an NCO group-terminated urethane prepolymer (G-14) solution having a solid content of 40%.

Comparative Example 7
According to the composition of Table-5, an NCO group-terminated urethane prepolymer (G-15) solution was obtained in the same manner as in Comparative Example 6. The properties are shown in Table 5.

Comparative Example 8
The NCO group-terminated urethane prepolymer (G-14) solution obtained in Example 6 was added to a polymerization tank of a polymerization reactor equipped with a polymerization tank, a stirrer, a thermometer, a reflux condenser, a nitrogen introduction pipe, and a dropping tank. The temperature in the polymerization tank was raised to 40 ° C. while stirring under a nitrogen stream. When the temperature reached 40 ° C., 11.8 parts of isophoronediamine was charged into the dropping tank and dropped over 2 hours to obtain a urethane / urea resin having an amino group.
Thereafter, 5.5 parts of 2-acryloyloxyethyl isocyanate (Karenz AOI, Showa Denko KK) and 26.0 parts of toluene are added to react the amino group with the isocyanate group, and the urethane having a (meth) acryloyl group. -A urea resin (H-6) solution was obtained. The properties are shown in Table-6.

Comparative Example 9
In a polymerization tank of a polymerization reactor equipped with a polymerization tank, a stirrer, a thermometer, a reflux condenser, a nitrogen introduction pipe, and a dropping tank, the NCO group-terminated urethane prepolymer (G-15) solution obtained in Example 1 was 2000 The temperature in the polymerization tank was raised to 40 ° C. while stirring under a nitrogen stream. When the temperature reached 40 ° C., 11.8 parts of isophoronediamine was charged into the dropping tank and dropped over 2 hours to obtain a urethane / urea resin having an isocyanate group.
Thereafter, 4.2 parts of 2-amino-2-methyl-1-propanol and 27.3 parts of toluene are added to react the amino group with the isocyanate group, thereby to obtain a urethane / urea resin having a (meth) acryloyl group ( H-7) A solution was obtained. The properties are shown in Table-6.

The detail of each component in Tables 1-6 is as follows.
C-1090: Kuraray Co., Ltd., polycarbonate diol Number average molecular weight = 1000
C-2050: manufactured by Kuraray Co., Ltd., polycarbonate diol number average molecular weight = 2000
C-2090: Kuraray Co., Ltd., polycarbonate diol Number average molecular weight = 2000
C-3090: Kuraray Co., Ltd., polycarbonate diol Number average molecular weight = 3000
P-3010: manufactured by Kuraray Co., Ltd., polyester diol number average molecular weight = 3000
CHDM: cyclohexanedimethanol MPD: 3-methyl-1,5-pentanediol 1,9-ND: 1,9-nonanediol Epoxy ester 70PA: manufactured by Kyoei Chemical Co., Ltd., 2 mol of acrylic acid in propylene glycol diglycidyl ether An acid-added compound.
IPDI: isophorone diisocyanate DBTDL: dibutyltin dilaurate AOI: 2-acryloyloxyethyl isocyanate (Karenz AOI, Showa Denko)
HEA: hydroxyethyl acrylate MEK: methyl ethyl ketone IPDA: isophoronediamine TMHMDA: trimethylhexamethylenediamine 1,10-DDA: 1,10-decanediamine AMP: 2-amino-2-methyl-1-propanol

<Mn, Mw>
For the measurement of Mn and Mw, GPC (gel permeation chromatography) “HPC-8020” manufactured by Tosoh Corporation was used, and tetrahydrofuran was used as the solvent. Mn and Mw were calculated in terms of polystyrene.

<Glass transition temperature (Tg)>
The glass transition temperature was measured using DSC “RDC220” manufactured by Seiko Instruments Inc. A urethane / urea resin solution having a (meth) acryloyl group was dried. About 10 mg of a sample was weighed into 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 calculated from the obtained DSC chart.

Examples 33-53, Comparative Examples 10-16 (Preparation of active energy ray-curable adhesive)
Resin solution of urethane / urea resin (E) having (meth) acryloyl group obtained by the above synthesis, resin solution of urethane acrylate, epoxy resin (F), urethane / urea resin (E) having (meth) acryloyl group Other active energy ray-curable compounds, photopolymerization initiators and other components were blended according to parts by weight shown in Tables 7 and -8 to obtain active energy ray-curable adhesives.

The detail of each component in Tables 7-8 is as follows.
Epicoat 1001: Epoxy resin (Japan Epoxy Resin Co., Ltd.) Number average molecular weight 900
Epicoat 1002: Epoxy resin (Japan Epoxy Resin Co., Ltd.) Number average molecular weight 1200
Epicoat 1009: Epoxy resin (Japan Epoxy Resin Co., Ltd.) Number average molecular weight 3800
IBXA: Isobornyl acrylate (manufactured by Osaka Organic Chemical Co., Ltd.)
M-210: EO-modified bisphenol A diacrylate (manufactured by Toagosei Co., Ltd.)
M305: Pentaerythritol triacrylate (manufactured by Toagosei Co., Ltd.)
M315: isocyanuric acid EO-modified triacrylate (manufactured by Toagosei Co., Ltd.)
Beam set 700: Dipentaerythritol hexaacrylate (Arakawa Chemical Co., Ltd.)
Viscoat # 230: 1,6-hexanediol diacrylate (Osaka Organic Chemical Co., Ltd.)
Irgacure 184: 1-hydroxy-cyclohexyl ruphenyl ketone (Ciba Specialty Chemicals)
Irgacure 369: 2-Benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1 (Ciba Specialty Chemicals)
Irgacure 819: Bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide (Ciba Specialty Chemicals)
S-510: 3-glycidoxypropyl) trimethoxysilane (manufactured by Chisso Corporation)

The glass transition temperature (Tg) of the cured product of each adhesive shown in Tables 7 to 8 was determined as follows.
A cured adhesive sheet having a thickness of about 200 μm was prepared and measured using a dynamic viscoelasticity measuring apparatus DVA-200 (manufactured by IT Measurement Control Co., Ltd.), and the temperature of the peak value of tan δ was defined as the glass transition temperature.

  The cured adhesive sheet was prepared by applying an adhesive to a polyester film having a silicone release layer with a blade coater, drying the solvent, and then ultraviolet rays (120 W metal halide lamp, integrated light quantity of UV-A region 500 mJ / cm2), an active energy ray-curable adhesive layer was formed, and the polyester film was peeled off.

(Methods 1 to 3 for creating a back surface protection sheet for solar cells)
Creation method 1
After applying the active energy ray-curable adhesive to the sheet-like member (S1) and volatilizing the solvent, the other sheet-like member (S2) is stacked and passed between two rolls set at 60 ° C. After lamination, the back surface protective sheet for solar cells is formed by irradiating ultraviolet rays (120W metal halide lamp, accumulated light quantity of 500-mJ / cm ^{2 in the} UV-A region) from the other sheet-like member (S2) side to form an active energy ray-cured adhesive layer. It was created. The amount of the adhesive layer was 8 to 10 g / square meter.

Creation method 2
The active energy ray-curable adhesive is applied to the sheet-like member (S1), and the solvent is volatilized, and then irradiated with ultraviolet rays (120 W high-pressure mercury lamp, integrated light quantity of 200 mJ / cm ^{2 in the} UV-A region) from the coated surface side. After curing the active energy ray-curing adhesive layer, the other sheet-like member (S2) is stacked and passed between two rolls set at 60 ° C., and after lamination, a solar cell back surface protection sheet is created. did. The amount of the adhesive layer was 8 to 10 g / square meter.

Creation method 3
The active energy ray-curable adhesive is applied to the sheet-like member (S1), and the solvent is volatilized, and then irradiated with ultraviolet rays (120 W high-pressure mercury lamp, integrated light quantity of 200 mJ / cm ^{2 in the} UV-A region) from the coated surface side. Then, after the active energy ray-curing adhesive layer was cured, another sheet-like member (S2) was stacked and passed between two rolls set at 60 ° C., and a laminate was created after lamination.
Next, an active energy ray-curable adhesive was applied to the laminate, and the solvent was volatilized. Then, ultraviolet rays (120 W high-pressure mercury lamp, integrated light amount of UV-A region 200 mJ / cm ² ) were applied from the coated surface side. After the active energy ray-curing adhesive layer is cured, another sheet-like member (S3) is stacked and passed between two rolls set at 60 ° C., and after lamination, a solar cell back surface protection sheet is created. did. The amount of the two adhesive layers was 8-10 g / square meter.

(Examples 54 to 81, Comparative Examples 17 to 30)
The back surface protection sheet for solar cells was obtained with the combination of the active energy ray-curable adhesive shown in Tables 9 to 13, the method for producing the back surface protection sheet for solar cells, and the sheet member. According to the method described later, the adhesiveness, heat and humidity resistance, productivity, and presence of bubbles were evaluated. The results are shown in Tables 9-13.

The meanings of the abbreviations of the sheet members (S1 to S3) in Tables 9 to 13 are as follows.
PET (1): colorless and transparent polyethylene terephthalate film (thickness: 188 μm)
PET (2): colorless and transparent polyethylene terephthalate film (thickness 50 μm)
Vapor deposition PET: A film obtained by vapor-depositing a mixture having a ratio of 90/10 of silicon oxide and magnesium fluoride (mol%) to a thickness of 500 mm on one side of a polyethylene terephthalate film (thickness: 12 μm).
AL (1): A 10 μm weather resistant resin layer * provided on one side of an aluminum foil (thickness 30 μm).
Weather resistant resin layer *: Obligato PS2012 (white) Main agent: Curing agent (13: 1) (manufactured by AGC Co-Tech)
AL (2): Aluminum foil (thickness 30 μm).
White PET: White polyethylene terephthalate film (thickness 50 μm)
Black PET: Black polyethylene terephthalate film (thickness 50 μm)
PVF: DuPont polyvinyl fluoride film “Tedlar” (thickness 38 μm)
-KFC: Kureha Extec multilayer film “FT-50Y” (50 μm thickness)
EVA: Ethylene / vinyl acetate copolymer resin film (thickness 100 μm)

Each evaluation method and evaluation criteria in Tables 9 to 13 are as follows.
(1) Adhesive The back protective sheet for solar cells is cut into a size of 200 mm × 15 mm, and a T-type peel test is performed at a load speed of 300 mm / min using a tensile tester according to the test method of ASTM D1876-61. It was. The peel strength (N / 15 mm width) between each sheet-like member was shown by the average value of five test pieces.
◎ ・ ・ ・ 4N or more ○ ・ ・ ・ 2N or more to less than 4N Δ ・ ・ ・ 1N or more to less than 2N × ・ ・ ・ less than 1N

(2) Moist heat resistance The back surface protection sheet for solar cells was preserve | saved for 1000 and 2000 hours in 85 degreeC and 85% RH atmosphere. The stored back surface protection sheet for solar cells was cut into a size of 200 mm × 15 mm, and a T-type peel test was performed at a load speed of 300 mm / min using a tensile tester in accordance with the test method of ASTM D1876-61. The peel strength (N / 15 mm width) between each sheet-like member was shown by the average value of five test pieces.
◎ ・ ・ ・ 4N or more ○ ・ ・ ・ 2N or more to less than 4N Δ ・ ・ ・ 1N or more to less than 2N × ・ ・ ・ less than 1N

(3) Productivity A roll-like product of a back protection sheet for a solar cell having a width of 50 cm and a length of 500 m was prepared, the core was placed in a vertical direction, and the outer periphery was grasped and lifted.
○: No deviation occurred in the bonded sheet, and the shape of the roll could be maintained.
X: Deviation occurred in the adhered sheet, and the shape of the roll could not be maintained.

(4) Presence / absence of bubbles and floats A 50 cm wide, 500 m long back surface protection sheet for solar cells was prepared, and the core was placed in a vertical orientation and stored in an environment at 60 ° C. for 1 week.
The state of the adhesive layer was observed through the transparent sheet-like member, and the presence or absence of lifting of the sheet-like member was observed.
○ ・ ・ ・ No abnormality △ ・ ・ ・ Small bubbles or small floats occurred.
X: Large bubbles or large bubbles are generated.

  The cured product obtained by curing the composition containing the urethane / urea resin (E) having the (meth) acryloyl group of the present invention is excellent in adhesiveness to various substrates such as a plastic film and a metal film. Deterioration does not occur under hot and humid conditions. Therefore, the composition is suitably used for the production of a back protective sheet for solar cells, as well as other fields, for example, optical members such as plastic lenses, prisms, optical fibers, solder resists for flexible printed wiring boards, multilayers, etc. It can also be used widely as electrical / electronic members such as interlayer insulating films for printed wiring boards, coating agents such as paper and plastic films, and adhesives for food packages.

Claims (11)

A diol component (A) that does not have a (meth) acryloyl group, which essentially includes a diol component having a carbonate structure, and (meth) acrylic acid added to the epoxy group of a compound having two or more epoxy groups. A urethane prepolymer (G) having an isocyanate group obtained by reacting a polyol component (B1) having a ( meth) acryloyl group and having two or more hydroxyl groups with a polyisocyanate component (C), and a diamine component (D) A urethane-urea resin (E) having a (meth) acryloyl group obtained by further reaction.   The urethane-urea resin (E) having a (meth) acryloyl group according to claim 1, wherein the glass transition temperature is -60 to -10 ° C.   The urethane-urea resin (E) having a (meth) acryloyl group according to claim 1 or 2, wherein the number average molecular weight is 5,000 to 150,000.   The urethane-urea resin (E) having a (meth) acryloyl group according to any one of claims 1 to 3, wherein the polyol component (B) has two or more (meth) acryloyl groups. The urethane / urea resin (E) having a (meth) acryloyl group according to any one of claims 1 to 4 , wherein the (meth) acryloyl group equivalent is 500 to 40,000. An active energy ray-curable adhesive comprising the urethane / urea resin (E) and the epoxy resin (F) each having a (meth) acryloyl group according to any one of claims 2 to 5 . The number average molecular weight of an epoxy resin (F) is 500-5000, The active energy ray hardening adhesive of Claim 6 characterized by the above-mentioned. Based on the solid content of the active energy ray-curable adhesive, 50 to 85 wt% of the urethane-urea resin (E), according to claim 6 or, characterized in that it contains an epoxy resin (F) 5 to 40 wt% 8. The active energy ray-curable adhesive according to 7 . The back surface protection sheet for solar cells in which at least 2 or more sheet-like members are laminated | stacked through the active energy ray hardening adhesive bond layer formed from the active energy ray hardening adhesive agent in any one of Claims 6-8. . One of the sheet-like members is a metal foil or a plastic film with a vapor deposition layer formed by vapor-depositing a metal oxide or a non-metal inorganic oxide on at least one surface of the plastic film. Item 10. A solar cell back surface protective sheet according to Item 9 . The glass transition temperature of an active energy ray hardening adhesive bond layer is -20-30 degreeC, The back surface protection sheet for solar cells of Claim 9 or 10 characterized by the above-mentioned.