JP2015166451A - Black curable adhesive resin composition, and solar battery rear face protective sheet made using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a black curable adhesive resin composition that allows a black pigment to be suitably dispersed without using a pigment dispersant and makes it possible to form a black curing adhesion layer having excellent long-term durability.SOLUTION: A black curable adhesive resin composition comprises, based on 100 pts.mass of an acrylic copolymer (A) with a specific hydroxyl value, a specific amine value, and a specific weight average molecular weight, 2-40 pts.mass of a black pigment (B), and 1-20 pts.mass of a polyisocyanate compound (C) comprising a blocked polyisocyanate compound (c1) as essential components.

Description

  The present invention relates to a black curable adhesive resin composition capable of forming a black cured adhesive layer having excellent long-term durability. Moreover, this invention relates to the solar cell back surface protection sheet which comprises the said black curable adhesive resin layer in the outermost surface, and its manufacturing method. Further, the present invention provides the black curable adhesive resin, wherein the black curable adhesive resin layer in the solar cell back surface protective sheet is disposed at a position in contact with a sealing agent located on the non-light-receiving surface side of the solar cell. The present invention relates to a solar cell module obtained by curing a layer.

As generally shown in FIG. 1, the solar cell module includes: (I): surface protection member (II): light-receiving surface side sealant (III): solar cell (IV): non-light-receiving surface side sealant; V): A back surface protection member is provided.
The surface protection member (I) is located on the outermost surface (light receiving surface side) of the solar cell module. In many cases, glass is used.
The sealing agent layers (II) and (IV) are also called filler layers, and are for embedding solar cells. Generally, ethylene-vinyl acetate copolymer resin (EVA) is used. A plurality of solar cells are arranged between two sheet-like EVAs, and are sandwiched between the front surface protection member (I) and the back surface protection member (V), and are thermocompression bonded to form a solar cell module.

  In the conventional solar cell module, the light receiving surface side of the solar cells exhibits a deep blue color, and the light receiving surface side gap between the solar cells exhibits a hue close to white. This is because a polytetrafluoroethylene (hereinafter referred to as PTFE) film or a polyethylene terephthalate (hereinafter referred to as PET) film is used for the outermost layer (layer farthest from the light receiving surface) in the back surface protection member (V). . That is, these films often exhibit white or slightly beigey white, and when the solar cell module is viewed from the light-receiving surface side, the gap between the solar cells exhibits the color of these films.

In recent years, from the viewpoint of design properties, modules that make the gap between solar cells black and make the solar cells less noticeable have come to be preferred.
As one method for blackening the gap between the solar cells on the light receiving surface side, a method of blackening the innermost layer (layer closest to the light receiving surface) in the back surface protection member (V) is conceivable.

  Patent Document 1 includes an acrylic polymer obtained by polymerizing a monomer mixture containing an ultraviolet-stable monomer and a (meth) acrylate monomer having a hydrocarbon group having 4 to 25 carbon atoms, The black coating composition containing a black pigment is described, and it is described that the said black coating composition can be used conveniently for a solar cell backsheet.

  Patent Documents 2 to 4 disclose the use of a pigment dispersant having a specific amine value, an amino group, or a nitrogen-containing group.

JP 2010-138300 A JP 2012-149197 A JP 2001-172528 A JP-A-10-339949

As a method of making the innermost layer in the back surface protection member (V) for the solar cell module black, use of a black pigment is conceivable. Many of the black pigments have poor affinity with the binder resin, and use of a pigment dispersant is effective from the viewpoint of dispersibility and storage stability.
However, the pigment dispersant has a considerably high polarity for improving the dispersibility of the pigment, and has a relatively low molecular weight as compared with the binder resin for forming the innermost layer in the back surface protective member (V). Is common.
Therefore, when a black pigment is dispersed using a pigment dispersant as disclosed in Patent Documents 2 to 4, the long-term durability of the solar cell module may be impaired.

  Moreover, since the black coating composition described in patent document 1 does not use the pigment dispersant as described in patent documents 2-4, the durability improvement as a solar cell module can be expected. However, it was unable to meet the increasingly demanding requirements.

  The present invention has been made in view of the prior art, and without using a so-called pigment dispersant, a black pigment can be suitably dispersed, and a black curable adhesive capable of forming a black cured adhesive layer having excellent long-term durability. It is an object to provide a conductive resin composition.

This invention solves the said subject by using the resin component which is excellent in pigment dispersibility, although it is high molecular weight instead of what is called a pigment dispersant.
That is, the present invention is a black curable adhesive resin composition containing an acrylic copolymer (A), a black pigment (B) and a polyisocyanate compound (C), wherein the acrylic copolymer ( A) has a hydroxyl value of 2 to 20 (mg KOH / g), an amine value of 0.5 (mg KOH / g) or more, a weight average molecular weight (Mw) of 40,000 to 600,000, and the acrylic copolymer Combined (A): 2 to 40 parts by mass of black pigment (B) and 1 to 20 parts by mass of polyisocyanate compound (C) with respect to 100 parts by mass, and further in the polyisocyanate compound (C) Black curing in which the ratio of the blocked polyisocyanate compound (c1) to the unblocked polyisocyanate compound (c2) is (c1) :( c2) = 50 or more to 100: 50 or less to 0 (mass ratio) Adhesion resin composition.
The acrylic copolymer (A) is preferably a copolymer having a (meth) acryloyl monomer having a tertiary amino group as a copolymerization component, and a glass transition temperature of 20 ° C. or higher. preferable.

  The present invention is also a solar cell back surface protective sheet having a black curable adhesive resin layer (4 ′) as an outermost surface layer on one surface of the plastic film (2), the black curable adhesive resin A layer (4 ') is formed from said black curable adhesive resin composition, It is related with the solar cell back surface protection sheet whose insoluble content with respect to methyl ethyl ketone is 0-50 mass%.

Furthermore, the present invention provides a plastic film (2) on one surface,
The above black curable adhesive resin composition is applied to form a black curable adhesive resin layer (4 ') having an insoluble content with respect to methyl ethyl ketone of 0 to 50% by mass. The present invention relates to a sheet manufacturing method.

Furthermore, the present invention also provides a solar cell surface protection member (I) positioned on the light receiving surface side of the solar cell, a sealant layer (II) positioned on the light receiving surface side of the solar cell, solar cells (III), solar A solar cell module comprising the sealing agent layer (IV) positioned on the non-light-receiving surface side of the battery, and the above-described solar cell back surface protective sheet in contact with the non-light-receiving surface side sealing agent layer (IV). There,
The present invention relates to a solar cell module, wherein the black cured adhesive layer (4) formed from the black curable adhesive resin layer (4 ′) is in contact with the non-light-receiving surface side sealing agent layer (IV).

  The black curable adhesive resin composition of the present invention can disperse a black pigment suitably, without using a so-called pigment dispersant, and has low viscosity and excellent storage stability. A black curable adhesive resin layer (4 ′) obtained by coating and drying the black curable adhesive resin composition of the present invention on a plastic film is in contact with the non-light-receiving surface side sealing agent layer (IV). The solar cell module is formed by curing in the state. The black cured adhesive layer (4) positioned between the plastic film and the non-light-receiving surface side sealant layer (IV) allows the plastic film and the non-light-receiving surface side sealant layer (IV) to pass through a long-term wet heat test. Adhesiveness is not impaired.

The typical sectional drawing of the conventional or solar cell module of this invention is represented. The typical sectional view of an example of the solar cell back surface protection sheet of the present invention is expressed. The schematic sectional drawing of the other aspect of the solar cell back surface protection sheet of this invention is represented. The typical sectional view of other modes of the solar cell back surface protection sheet of the present invention is expressed.

The acrylic copolymer (A) used for the black curable adhesive resin composition of the present invention will be described. The hydroxyl value of the acrylic copolymer (A) is 2 to 20 (mgKOH / g).
By using the acrylic copolymer (A) having a hydroxyl value of 2 to 20 (mgKOH / g), the reaction with the polyisocyanate compound (C) essentially comprising the blocked polyisocyanate compound (c1) is sufficient and appropriate. A black cured adhesive layer (4) having a sufficient crosslinking density can be formed, and the plastic film and the non-light-receiving surface side sealing agent layer (IV) can be bonded together with sufficient adhesive strength.

The hydroxyl value of the acrylic copolymer (A) depends on the ratio of the hydroxyl group-containing monomer component in the monomer component used for the formation of the acrylic copolymer (A).
Examples of the hydroxyl group-containing monomer include hydroxyalkyl (meth) acrylate and a product obtained by adding ε-caprolactone to the hydroxyalkyl (meth) acrylate, and hydroxyalkyl (meth) acrylate is preferable.
In order to obtain an acrylic copolymer (A) having a hydroxyl value of 2 to 20 (mgKOH / g), 0.5 to 5% by mass of hydroxyalkyl (meth) acrylate in a total of 100% by mass of monomers. % Copolymerization is preferred.

  Specific examples of hydroxyalkyl (meth) acrylate and its ε-caprolactone adduct include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 2-hydroxybutyl. (Meth) acrylate, hydroxyalkyl (meth) acrylate having 1 to 4 carbon atoms of alkyl group such as 4-hydroxybutyl (meth) acrylate; 1-mol ε-caprolactone adduct of 2-hydroxyethyl (meth) acrylate, 2 -Ε- of hydroxyalkyl (meth) acrylate having 1 to 4 carbon atoms, such as ε-caprolactone 2 mol adduct of hydroxyethyl (meth) acrylate, ε-caprolactone 3 mol adduct of 2-hydroxyethyl (meth) acrylate, etc. Capro Although such lactone adducts, the present invention is not limited only to those exemplified. These hydroxyl group-containing monomers may be used alone or in combination.

The amine value of the acrylic copolymer (A) used in the present invention is 0.5 (mg KOH / g) or more. By using the acrylic copolymer (A) having an amine value of 0.5 (mg KOH / g) or more, the black pigment can be favorably dispersed.
For example, when an acrylic copolymer having no amine value: 100 parts by mass and black pigment: 40 parts by mass with a solid content (non-volatile content) of about 35% by mass using glass beads to disperse There is no fluidity of the body, and it becomes a cream state with the dispersion and glass beads mixed. If the amount of the black pigment relative to the acrylic copolymer having no amine value is reduced, fluidity is exhibited immediately after dispersion, but fluidity is lost after 1 day.
When the solar cell module is viewed from the light-receiving surface side, the black pigment is used with respect to 100 parts by mass of the acrylic copolymer in order to exhibit a dark color to black so that the gap between the solar cell cells cannot be distinguished from the solar cell. In order to disperse the black pigment, the amine value of the acrylic copolymer (A) must be at least 0.5 (mg KOH / g).

The upper limit of the amine value is not particularly limited, but the amine value is preferably 100 (mgKOH / g) or less, considering that it functions as a binder resin in the film on which the acrylic copolymer (A) is formed. (MgKOH / g) is more preferable, and 30 (mgKOH / g) or less is more preferable.
By using an acrylic copolymer (A) having an amine value of 100 (mgKOH / g) or less, water and water vapor hardly penetrate through the formed black cured adhesive layer (4), and the solar battery cell is deteriorated. Risk is reduced.

As a method for imparting an amine value to the acrylic copolymer (A), a monomer having a nitrogen atom-containing group and an ethylenically unsaturated double bond is used as a single monomer having another ethylenically unsaturated double bond. It can be obtained by copolymerization with a polymer (hereinafter referred to as “other monomer”). “Other monomer” means neither the above-mentioned hydroxyl group-containing monomer nor a monomer having a nitrogen atom-containing group and an ethylenically unsaturated double bond.
Monomers having a nitrogen atom-containing group and an ethylenically unsaturated double bond include alkylamino (meth) acrylates that are (meth) acrylates, alkyl (meth) acrylamides that are (meth) acrylamides, aminoalkyl ( (Meth) acrylamides can be raised.

  Examples of alkylamino (meth) acrylate monomers include N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, and 1- (N, N-dimethylamino) -1,1-dimethyl. Methyl (meth) acrylate, N, N-dimethylaminohexyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-diisopropylaminoethyl (meth) acrylate, N, N-di-i-butyl Aminoethyl (meth) acrylate, morpholinoethyl (meth) acrylate, piperidinoethyl (meth) acrylate, 1-pyrrolidinoethyl (meth) acrylate, N, N-methyl-2-pyrrolidylaminoethyl (meth) acrylate, N, N -Methylphenylaminoethyl (meta Acrylate and the like.

  Alkyl (meth) acrylamide monomers include dimethyl (meth) acrylamide, diethyl (meth) acrylamide, diisopropyl (meth) acrylamide, di-n-butyl (meth) acrylamide, di-i-butyl (meth) acrylamide, morpholino (meth) ) Acrylamide, piperidino (meth) acrylamide, N-methyl-2-pyrrolidyl (meth) acrylamide, N, N-methylphenyl (meth) acrylamide and the like.

  Examples of aminoalkyl (meth) acrylamide monomers include 2- (N, N-dimethylamino) ethyl (meth) acrylamide, 2- (N, N-diethylamino) ethyl (meth) acrylamide, 3- (N, N- Diethylamino) propyl (meth) acrylamide, 3- (N, N-dimethylamino) propyl (meth) acrylamide, 1- (N, N-dimethylamino) -1,1-dimethylmethyl (meth) acrylamide, 6- (N , N-diethylamino) hexyl (meth) acrylamide and the like.

As the monomer having a nitrogen atom-containing group and an ethylenically unsaturated double bond, a monomer having a UV-stable group called so-called HALS and an ethylenically unsaturated double bond is also preferably used. Examples of monomers having UV-stable groups and ethylenically unsaturated double bonds include:
4- (meth) acryloyloxy-1,2,2,6,6-pentamethylpiperidine, 4- (meth) acryloyloxy-2,2,6,6-tetramethylpiperidine, 4- (meth) acryloylamino- 2,2,6,6-tetramethylpiperidine, 4- (meth) acryloylamino-1,2,2,6,6-pentamethylpiperidine, 4-cyano-4- (meth) acryloylamino-2,2, Examples include 6,6-tetramethylpiperidine, 4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, 4-crotonoylamino-2,2,6,6-tetramethylpiperidine and the like.
Further, 3- (2H-1,2,3-benzotriazol-2-yl) -4-hydroxyphenethyl methacrylate, which is known as an ultraviolet absorber monomer, can also be used.

In the present invention, a (meth) acryloyl monomer having a tertiary amino group is preferred as the monomer having a nitrogen atom-containing group and an ethylenically unsaturated double bond. The tertiary amino group is a group in which the hydrogen atom of ammonia is substituted with a hydrocarbon residue, and all three hydrogen atoms are substituted with hydrocarbon residues. For example, among alkylamino (meth) acrylate monomers, dialkylamino (meth) acrylate monomers, the aforementioned HALS having a piperidinyl group, and the like can be mentioned.
The black curable adhesive resin composition of the present invention contains a polyisocyanate compound (C) essentially comprising an acrylic copolymer (A) and a blocked polyisocyanate compound (c1).
Primary amino groups and secondary amino groups are more reactive with isocyanate groups than hydroxyl groups. Therefore, when the acrylic copolymer (A) having a primary amino group or a secondary amino group is used, when a solar cell module is formed, that is, when the cured adhesive layer (4) is formed, it has priority over the hydroxyl group. In addition, the primary amino group or the secondary amino group may react with the polyisocyanate compound (C) to leave a hydroxyl group. If a large amount of hydroxyl groups remain in the cured adhesive layer (4), the heat and moisture resistance may be reduced. Moreover, when the amount of the polyisocyanate compound (C) is increased so that no hydroxyl group remains, the crosslink density of the cured adhesive layer (4) becomes excessively large, which may reduce the adhesion. Therefore, in the present invention, it is preferable to use a (meth) acryloyl monomer having a tertiary amino group as a monomer having a nitrogen atom-containing group and an ethylenically unsaturated double bond.

  Examples of the “other monomers” used for forming the acrylic copolymer (A) in the present invention include (meth) acrylates, vinyl ester monomers, silicon atom-containing monomers, halogen atom-containing monomers. Examples include a monomer, a polyfunctional monomer, a vinyl ether monomer, an epoxy group-containing monomer, and an acidic group-containing monomer, but the present invention is not limited to such examples.

  Examples of (meth) acrylates include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, and sec-butyl (meth) acrylate. , Tert-butyl (meth) acrylate, isoamyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isononyl (meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, tert -Alkyl (meth) acrylates such as butylhexyl (meth) acrylate, 2-acetoacetoxyethyl (meth) acrylate, phenoxyethyl (meth) acrylate and the like.

  As a monomer having an alicyclic hydrocarbon group, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, cyclododecyl (meth) acrylate, bornyl (meth) acrylate, isobornyl (meth) acrylate, Examples thereof include dicyclopentenyl (meth) acrylate and dicyclopentanyl (meth) acrylate.

  Examples of the monomer having an epoxy group include glycidyl (meth) acrylate, α-methylglycidyl acrylate, α-methylglycidyl methacrylate, 3,4-epoxycyclohexylmethyl acrylate, 3,4-epoxycyclohexylmethyl methacrylate, and the like.

  Examples of the acidic group-containing monomer include (meth) acrylic acid, maleic anhydride, 2- (meth) acryloyloxyethyl-succinic acid, 2- (meth) acryloyloxyethyl-hexahydrophthalic acid, 2- ( And (meth) acryloyloxyethyl-phthalic acid, 2- (meth) acryloyloxyethyl acid phosphate, and the like.

  The acrylic copolymer (A) can be easily prepared by copolymerizing the monomers.

  Examples of the method for polymerizing the monomer include a solution polymerization method, a bulk polymerization method, a suspension polymerization method, and an emulsion polymerization method, but the present invention is not limited to such a polymerization method. Among these polymerization methods, the solution polymerization method is preferable because the obtained reaction mixture can be used as it is.

  Hereinafter, one embodiment in the case of preparing an acrylic copolymer by solution polymerization of monomers will be described, but the present invention is not limited only to that embodiment.

  Examples of the solvent used for solution polymerization of the monomer include aromatic solvents such as toluene and xylene; alcohol solvents such as n-butyl alcohol, propylene glycol monomethyl ether, diacetone alcohol, and ethyl cellosolve; Examples include ester solvents such as ethyl, butyl acetate, and cellosolve acetate; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; dimethylformamide and the like, but the present invention is not limited to such examples. The amount of the solvent is preferably determined as appropriate according to the concentration of the single mixture, the molecular weight of the target acrylic polymer, and the like.

  Examples of the polymerization initiator include 2,2′-azobis- (2-methylbutyronitrile), tert-butylperoxy-2-ethylhexanoate, 2,2′-azobisisobutyronitrile, benzoyl Although a peroxide, di-tert-butyl peroxide, etc. are mentioned, this invention is not limited only to this illustration. The amount of the polymerization initiator is usually preferably 0.01 to 30 parts by mass, more preferably 0.05 to 10 parts by mass, per 100 parts by mass of the monomer mixture.

  In the polymerization, a chain transfer agent such as n-dodecyl mercaptan may be used to adjust the molecular weight of the resulting acrylic copolymer.

  The polymerization temperature at the time of polymerizing the monomer is usually preferably 40 to 200 ° C, more preferably 40 to 140 ° C.

  Since the polymerization time of the monomer varies depending on the polymerization temperature, the composition of the monomer mixture, the type and amount of the polymerization initiator, and cannot be determined unconditionally, it is preferable to determine appropriately according to them. .

In the present invention, a functional group capable of reacting with the hydroxyl group and a compound having a (meth) acryloyl group are reacted with a part of the hydroxyl group in the (meth) acrylic copolymer obtained as described above, A (meth) acrylic copolymer introduced with a (meth) acryloyl group can also be used as the (meth) acrylic copolymer (A).
Alternatively, in the case where the (meth) acrylic copolymer obtained as described above has a carboxyl group, a compound having a functional group capable of reacting with the carboxyl group and a (meth) acryloyl group is reacted, ) A (meth) acrylic copolymer into which an acryloyl group has been introduced can also be used as the (meth) acrylic copolymer (A).
Alternatively, in the case where the (meth) acrylic copolymer obtained as described above has a glycidyl group, a compound having a functional group capable of reacting with the glycidyl group and a (meth) acryloyl group is reacted, ) A (meth) acrylic copolymer into which an acryloyl group has been introduced can also be used as the (meth) acrylic copolymer (A).
When a (meth) acrylic copolymer having a (meth) acryloyl group introduced therein is used as the (meth) acrylic copolymer (A), when a solar cell module is obtained, the non-light-receiving surface side sealing agent layer (IV ) And the adhesive strength can be increased.

Examples of the compound having a functional group capable of reacting with a hydroxyl group and a (meth) acryloyl group include 2-methacryloyloxyethyl isocyanate, 2-acryloyloxyethyl isocyanate, 1,1-bis (acryloyloxymethyl) ethyl isocyanate, etc. Is mentioned.
Examples of the compound having a functional group capable of reacting with a carboxyl group and a (meth) acryloyl group include glycidyl methacrylate.
Examples of the compound having a functional group capable of reacting with a glycidyl group and a (meth) acryloyl group include acrylic acid and methacrylic acid.

The weight average molecular weight of the (meth) acrylic copolymer (A) in the present invention is preferably 40,000 to 600,000, more preferably 50,000 to 400,000. 000 to 200,000 is particularly preferable.
In addition, said weight average molecular weight is the value of polystyrene conversion by the gel permeation chromatography (GPC) of a (meth) acrylic-type copolymer (A). For example, the temperature of a column (KF-805LKF-803L and KF-802 manufactured by Showa Denko KK) is 40 ° C., THF is used as an eluent, the flow rate is 0.2 ml / min, detection is RI, sample concentration 0.02% and polystyrene was used as a standard sample. The weight average molecular weight of the present invention describes the value measured by the above method.

When the weight average molecular weight of the acrylic copolymer (A) in the present invention is 40,000 or more, a black curable adhesive resin layer (4 ′) having high film strength can be obtained. As a result, when the solar cell module was formed, the black cured adhesive layer (4) and the sealant layer (IV)
The adhesion between the black cured adhesive layer (4) and the plastic film (2) does not become weaker, and the power output of the solar cell can be increased during long-term use. It does n’t drop.
The weight average molecular weight (Mw) of the acrylic copolymer (A) is preferably 600,000 or less from the viewpoint of preventing the formation and mixing of gel-like materials. If the gel-like material is mixed into the black curable adhesive resin layer (4 ′), it may cause defective products when the solar cell module is formed. In addition, when the weight average molecular weight (Mw) of the acrylic copolymer (A) is 600,000 or less, a black curable adhesive resin composition having an appropriate viscosity and an appropriate solid content can be obtained, When applied to the plastic film (2), problems are unlikely to occur.

The glass transition temperature of the acrylic copolymer (A) in the present invention is preferably 20 ° C. or higher. More preferably, it is 30 ° C. or higher and more preferably 70 ° C. or lower. By making the glass transition temperature 20 ° C. or higher, it becomes difficult for tack to occur on the surface of the black curable adhesive resin layer (4 ′) to be formed. It becomes difficult to cause blocking.
By setting the glass transition temperature of the acrylic copolymer (A) to 70 ° C. or lower, the black cured adhesive layer (4) having an appropriate flexibility without being too hard can be formed. Adhesiveness between the plastic film (2) and the sealant layer (IV) is improved.

  The glass transition temperature referred to here is the glass transition temperature measured by differential scanning calorimetry (DSC) for a resin obtained by drying a solution of the acrylic copolymer (A) to a solid content of 100%. Indicates. For example, for the glass transition temperature, an aluminum pan containing a sample obtained by weighing about 10 mg of a sample and an aluminum pan containing no sample are set in a DSC apparatus, and this is set to −50 using liquid nitrogen in a nitrogen stream. A rapid cooling treatment is performed until the temperature is increased to 150 ° C. at 10 ° C./min, and a DSC curve is plotted. The slope of the DSC curve on the low temperature side (the DSC curve portion in the temperature region where no transition or reaction occurs in the test piece) is extended to the high temperature side, and the slope of the step change portion of the glass transition is maximized. From the intersection with the tangent drawn at such a point, the extrapolated glass transition start temperature (Tig) can be determined, and this can be determined as the glass transition temperature. The glass transition temperature of this invention has described the value measured by said method.

  The black curable adhesive resin composition of the present invention contains 2 to 40 parts by mass of the black pigment (B) with respect to 100 parts by mass of the acrylic copolymer (A). Examples of the black pigment include carbon black, black iron oxide (triiron tetroxide), black titanium oxide, copper manganese black, copper chrome black, cobalt black, cyanine black, and aniline black. It is not limited to illustration only. These black pigments may be used alone or in combination of two or more. Among these, carbon black is preferable from the viewpoint of light shielding properties. Examples of the carbon black include channel black, oil furnace black, gas furnace black, thermal black, acetylene black, bone black, and the like. The black pigment may be used in combination with other colorants such as pigments and dyes as long as the object of the present invention is not impaired.

  By setting the amount of the black pigment to 2 parts by mass or more with respect to 100 parts by mass of the acrylic copolymer (A), it is possible to form a solar cell back surface protective sheet excellent in blackness, and the solar cell module from the light receiving side When viewed, the gap between the solar cells also appears dark. Moreover, by setting the amount of the black pigment to 40 parts by mass or less, it is possible to obtain a black curable adhesive resin composition excellent in dispersion stability that does not rapidly increase in viscosity during storage and does not gel. .

Next, the polyisocyanate compound (C) will be described.
The polyisocyanate compound (C) contains the blocked polyisocyanate compound (c1) as an essential component. The blocked polyisocyanate compound (c1) and the unblocked polyisocyanate compound ( The ratio to c2) is (c1) :( c2) = 50 or more to 100: 50 or less to 0 (mass ratio).

In the solar cell back surface protective sheet obtained by applying the black curable adhesive resin composition of the present invention to the plastic film (2), the black curable adhesive resin layer (4 ′) is an encapsulant layer (IV). It is important to be uncured or semi-cured until the solar cell module is manufactured by bonding together. Accordingly, it is important to use a polyisocyanate compound (C) that contains the blocked polyisocyanate compound (c1) as an essential component.
That is, when the blocked polyisocyanate compound (c1) is formed by stacking the solar cell back surface protective sheet and the sealing layer (IV) to form a solar cell module, the acrylic copolymer (A
) Reacts with a hydroxyl group in the copolymer to crosslink the copolymers, form a black cured adhesive layer (4), and bear the function of bonding the solar cell back surface protective sheet and the sealing layer (IV) together.
On the other hand, the non-blocked polyisocyanate compound (c2) reacts with a part of the hydroxyl groups in the acrylic copolymer (A) when mainly forming the solar cell back surface protective sheet, to crosslink the copolymers, A semi-cured black curable adhesive resin layer (4 ′) is formed. By using the unblocked polyisocyanate compound (c2), the blocking resistance of the semi-cured black curable adhesive resin layer (4 ′) can be improved.

The black curable adhesive resin composition of the present invention contains 1 to 20 parts by mass of the polyisocyanate compound (C) with respect to 100 parts by mass of the acrylic copolymer (A).
By setting the polyisocyanate compound (C) to 1 part by mass or more with respect to 100 parts by mass of the acrylic copolymer (A), a strong black cured adhesive layer (4) can be formed.
On the other hand, by setting the polyisocyanate compound (C) to 20 parts by mass or less with respect to 100 parts by mass of the acrylic copolymer (A), a black cured adhesive layer (4) having an appropriate crosslinking density can be formed. Sufficient adhesive strength can be expressed.

It is important that the blocked polyisocyanate compound (c1) used in the present invention is a blocked product of a polyisocyanate compound having two or more isocyanate groups in one molecule, for example, two or more in one molecule. Examples of the polyisocyanate compound having an isocyanate group include aromatic polyisocyanate, aliphatic polyisocyanate, and alicyclic polyisocyanate.
One type of blocked polyisocyanate compound (c1) may be used, or two or more types of compounds may be used in combination.

  Aromatic polyisocyanates include 1,3-phenylene diisocyanate, 4,4′-diphenyl diisocyanate, 1,4-phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-triisocyanate. Range isocyanate, 4,4'-toluidine diisocyanate, 2,4,6-triisocyanate toluene, 1,3,5-triisocyanate benzene, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4 ', 4 " -Can increase triphenylmethane triisocyanate, etc.

  Aliphatic polyisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate. 2,4,4-trimethylhexamethylene diisocyanate and the like.

  Examples of alicyclic polyisocyanates include 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate (IPDI), 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl- 2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4′-methylene bis (cyclohexyl isocyanate), 1,4-bis (isocyanate methyl) cyclohexane and the like can be raised.

  In addition to the polyisocyanate, an adduct of the polyisocyanate and a polyol compound such as trimethylolpropane, a burette or isocyanurate of the polyisocyanate, and further, the polyisocyanate and a known polyether polyol or polyester polyol, Examples include adducts such as acrylic polyol, polybutadiene polyol, polyisoprene polyol, and the like.

  Among these polyisocyanate compounds (C), a low-yellowing type aliphatic or alicyclic polyisocyanate is preferable from the viewpoint of design, and an isocyanurate is preferable from the viewpoint of heat-and-moisture resistance. More specifically, an isocyanurate form of hexamethylene diisocyanate (HDI) and an isocyanurate form of 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate (IPDI) are preferred. Moreover, these mixtures are also used suitably.

  The blocked polyisocyanate compound (c1) can be obtained by reacting almost all of the isocyanate groups of the unblocked polyisocyanate compound (c2) with the blocking agent.

  Examples of the blocking agent include phenols such as phenol, thiophenol, methylthiophenol, xylenol, cresol, resorcinol, nitrophenol, chlorophenol, oximes such as acetone oxime, methyl ethyl ketone oxime, cyclohexanone oxime, methanol, ethanol, n- Alcohols such as propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, t-butyl alcohol, t-pentanol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, benzyl alcohol , Pyrazol such as 3,5-dimethylpyrazole, 1,2-pyrazole, etc. , Triazoles such as 1,2,4-triazole, halogen-substituted alcohols such as ethylene chlorohydrin and 1,3-dichloro-2-propanol, ε-caprolactam, δ-valerolactam, γ-butyrolactam, β- Examples include lactams such as propyl lactam, and active methylene compounds such as methyl acetoacetate, ethyl acetoacetate, acetylacetone, methyl malonate, and ethyl malonate. In addition, amines, imides, mercaptans, imines, ureas, diaryls, and the like are also included. One blocking agent may be used, or two or more blocking agents may be used in combination.

Among these blocking agents, those having a dissociation temperature of 80 to 150 ° C. are preferable. When the dissociation temperature is less than 80 ° C., when the black curable adhesive resin composition is applied and the solvent is volatilized, the curing reaction proceeds and the adhesiveness to the sealant layer may be reduced. is there. When the dissociation temperature exceeds 150 ° C., the curing reaction does not proceed sufficiently in the vacuum laminating step when the solar cell module is constructed, and the adhesiveness with the sealant layer may be lowered.
Examples of the blocking agent having a dissociation temperature of 80 ° C. to 150 ° C. include methyl ethyl ketone oxime (dissociation temperature: 140 ° C., hereinafter the same), 3,5-dimethylpyrazole (120 ° C.), diisopropylamine (120 ° C.) and the like.

Furthermore, in the black curable adhesive resin composition of the present invention, a resin for a binder other than the acrylic copolymer (A), an organic or inorganic resin can be used within a range that does not impair the object of the present invention. Fine particles, organic solvents, and the like may be included.
Examples of resins other than the acrylic copolymer (A) include polyester resins, urethane resins, epoxy resins, vinyl resins, fluororesins, and silicone resins.

By containing organic or inorganic fine particles in the black curable adhesive resin composition of the present invention, the surface of the black curable adhesive resin layer (4 ′) is made uneven to give an antiblocking effect, It can be expected to produce a matte feeling due to surface irregularities, or to give the film strength, thereby making it less likely to be scratched or improving adhesion.
These fine particles are preferably contained in an amount of 0.01 to 30 parts by mass, more preferably 0.1 to 20 parts by mass with respect to 100 parts by mass of the acrylic copolymer (A). When the content is 0.01 parts by mass or more, the above effect can be expected, and when the content is 30 parts by mass or less, a strong black cured adhesive layer (4) having excellent adhesiveness can be formed.

  Specific examples of the organic fine particles include polymethyl methacrylate resin, polystyrene resin, nylon (registered trademark) resin, melamine resin, guanamine resin, phenol resin, urea resin, silicone resin, methacrylate resin, acrylate resin, or polymer fine particles, or , Cellulose powder, nitrocellulose powder, wood powder, waste paper powder, rice husk powder, starch and the like. One type of organic particles may be used, or two or more types may be used in combination.

  Specific examples of the inorganic fine particles include inorganic oxides such as magnesium, calcium, barium, zinc, zirconium, molybdenum, silicon, antimony, titanium, and other metal oxides, hydroxides, sulfates, carbonates, silicates, and the like. System fine particles are raised. Further specific examples include silica gel, aluminum oxide, calcium hydroxide, calcium carbonate, magnesium oxide, magnesium hydroxide, magnesium carbonate, zinc oxide, lead oxide, diatomaceous earth, zeolite, aluminosilicate, talc, white carbon, mica Glass fiber, glass powder, glass beads, clay, wollastonite, iron oxide, antimony oxide, titanium oxide, lithopone, pumice powder, aluminum sulfate, zirconium silicate, barium carbonate, dolomite, molybdenum disulfide, iron sand, carbon black, etc. Examples thereof include inorganic particles. One kind of inorganic particles may be used, or two or more kinds may be used in combination.

  Moreover, you may add a hardening accelerator to the black curable adhesive resin composition of this invention in the range which does not prevent the effect by this invention as needed. The curing accelerator plays a role as a catalyst for promoting the urethane bond reaction between the hydroxyl group of the acrylic copolymer (A) and the polyisocyanate compound (C). Examples of the curing accelerator include tin compounds, metal salts, bases, etc. Specific examples include tin octylate, dibutyltin diacetate, dibutyltin dilaurate, dioctyltin dilaurate, tin chloride, iron octylate, cobalt octylate, naphthene. Examples include zinc acid, triethylamine, and triethylenediamine. These can be used alone or in combination.

The black curable adhesive resin composition of the present invention may contain an organic solvent. Examples of the organic solvent include aromatic solvents such as toluene and xylene; alcohol solvents such as iso-propyl alcohol, n-butyl alcohol and propylene glycol monomethyl ether; ester systems such as ethyl acetate, butyl acetate and cellosolve acetate. Solvent; ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone are listed.
It is preferable to use an organic solvent having a boiling point of 50 ° C to 200 ° C. When the boiling point is lower than 50 ° C., the solvent tends to volatilize when the black curable adhesive resin composition is applied to the substrate, and the solid content becomes high and it becomes difficult to apply the uniform film thickness. When the boiling point is higher than 200 ° C., it is difficult to dry the solvent. Two or more solvents may be used.

The black curable adhesive resin composition of the present invention is used to form the innermost layer on the light receiving surface side of the solar cell back surface protective sheet. And a solar cell back surface protection sheet is provided for formation of a solar cell module. Since the solar cell module is exposed to the external environment for a long period of time, the solar cell module is required to have high moisture and weather resistance.
Since the black cured adhesive layer (4) formed from the black curable adhesive resin composition of the present invention is also exposed to the external environment for a long period of time, a high degree of moist heat resistance and weather resistance are required.
For the purpose of imparting weather resistance to the black curable adhesive resin composition of the present invention, an ultraviolet absorber, an ultraviolet stabilizer, or the like can be added.
Examples of UV absorbers include organic UV absorbers such as benzotriazole UV absorbers, benzophenone UV absorbers, triazine UV absorbers, and indole UV absorbers, and inorganic systems such as zinc oxide and titanium oxide. UV absorbers such as UV absorbers are raised.
As the ultraviolet stabilizer, an ultraviolet stabilizer such as a hindered amine compound is preferably used. An ultraviolet absorber or an ultraviolet stabilizer may be added to the black curable adhesive resin composition as an additive, or an ultraviolet absorber or an ultraviolet stabilizer having a functional group is reacted with an acrylic copolymer. You may use it, making it react with other resin and using it.
These ultraviolet absorbers and ultraviolet stabilizers are used in an amount of 0.1 to 30 parts by weight, preferably 1 to 20 parts by weight, based on 100 parts by weight of the solid content of the black curable adhesive resin composition.

  In the black curable adhesive resin composition in the present invention, a filler, a thixotropy imparting agent, an anti-aging agent, an antioxidant, an antistatic agent, a flame retardant, as long as the effects according to the present invention are not hindered. , Thermal conductivity improvers, plasticizers, anti-sagging agents, antifouling agents, antiseptics, bactericides, antifoaming agents, leveling agents, curing agents, thickeners, pigment dispersants, silane coupling agents, etc. Additives may be added.

  In the present invention, since the affinity between the acrylic copolymer (A) and the black pigment (B) is excellent, the black pigment (B) can be dispersed in a short time. The black curable adhesive resin composition after dispersion exhibits low viscosity and Newtonian fluidity, and the viscosity does not increase even when stored for a long period of time, and the pigment does not separate or settle.

Next, the solar cell back surface protection sheet of this invention is demonstrated based on a figure.
The solar cell back surface protection sheet (V) of this invention is located in a non-light-receiving surface in the solar cell module shown in FIG.
In the solar cell back surface protective sheet (V) of the present invention, as shown in FIGS. 2, 3, and 4, the weather resistant protective layer (1) constitutes one surface, and the black curable adhesive resin layer (4 ′). It can be set as the aspect which comprises the other surface.
When forming the solar cell module, the black curable adhesive resin layer (4 ′) is disposed so as to be in contact with the non-light-receiving surface side sealing agent (IV) shown in FIG. Therefore, in the formed solar cell module, the black cured adhesive layer (4) is the innermost layer on the non-light-receiving surface side.

Such a solar cell back surface protective sheet can be obtained by the following method.
For example, the composition for forming a weather-resistant protective layer is applied to one surface of the plastic film (2), cured by heating, provided with a weather-resistant protective layer (1), and on the other surface of the plastic film (2), The black curable adhesive resin composition of the present invention was applied, and the solvent was volatilized by heating and drying at 50 to 150 ° C. for 30 seconds to 2 minutes, and the insoluble content in methyl ethyl ketone was 0 to 0. A black curable adhesive resin layer (4 ′) that is 50% can be formed, and the solar cell back surface protective sheet of the embodiment of FIG. 2 can be obtained.

  Alternatively, a plurality of plastic films (2) are laminated in advance via an adhesive layer (3), and a weather-resistant protective layer-forming composition is applied to one surface of the laminate, thereby providing a weather-resistant protective layer. The solar cell back surface protection sheet of the aspect of FIG. 3 can also be obtained by providing (1) or providing a weather-resistant protective film (1) via an adhesive layer (3).

Alternatively, an adhesive layer is applied to one surface of the plastic film (2), and the solvent is volatilized by heating and drying at 50 to 150 ° C. for 30 seconds to 2 minutes, thereby uncured adhesive layer (3 ′). Form. After forming the adhesive layer (3 ′), the weather-resistant protective film (1) is stacked, and the adhesive layer is cured by aging.
The aging temperature is preferably 30 to 80 ° C, more preferably 40 to 60 ° C. The aging time is usually 2 to 8 days. If the aging temperature is low, the time until the curing is completed is long, and if the aging temperature is high, the time is short.
A method of accelerating curing by evaporating the solvent and heating it at a temperature of 80 to 150 ° C. for 30 seconds to 10 minutes before aging is also suitable.
Next, the black curable adhesive resin composition of the present invention is applied to the other surface of the plastic film (2), and the solvent is volatilized by heating and drying at 50 to 150 ° C. for 30 seconds to 2 minutes. A partially cured black curable adhesive resin layer (4 ′) having an insoluble content with respect to methyl ethyl ketone of 0 to 50% can be formed to obtain the solar cell back surface protective sheet of the embodiment of FIG.

  Alternatively, the black curable adhesive resin composition of the present invention is applied to one surface of the plastic film (2), dried by heating, the solvent is volatilized, and the black cured resin has an insoluble content in methyl ethyl ketone of 0 to 50%. The adhesive resin layer (4 ′) is formed. And the solar cell back surface protection sheet of the aspect of FIG. 4 can be obtained also by laminating | stacking a weather-resistant protective film (1) on the other surface of a plastic film (2) through an adhesive bond layer (3). it can.

Various things can be used as a plastic film (2) which is the object which apply | coats the black curable adhesive resin composition of this invention.
For example, polyester, polyethylene, polypropylene, triacetyl cellulose, polystyrene, polycarbonate, polyethersulfone, cellophane, polyamide, polyvinyl alcohol, polyacetal, polyphenylene ether, polyphenylene sulfide, polyimide, polyamideimide, polyetherimide, polyetheretherketone, poly Examples thereof include films made of various resins such as fluorine resins such as tetrafluoroethylene and polyvinylidene fluoride, ABS resins, nonyl resins, acrylic resins, and epoxy resins.
Moreover, the vapor deposition film etc. which vapor-deposited the metal oxide and the nonmetallic inorganic oxide etc. can also be used for these resin films.
Furthermore, what laminated | stacked metal foil, such as copper and aluminum, can also be used for these resin-made films using an adhesive agent.
In addition, it does not ask | require whether the surface which apply | coats the black curable adhesive resin composition of this invention is a resin film, a vapor deposition layer, or a metal foil.

Examples of the metal oxide or non-metal inorganic oxide to be deposited include oxides such as silicon, aluminum, magnesium, calcium, potassium, tin, sodium, boron, titanium, lead, zirconium, and yttrium. Alkali metal and alkaline earth metal fluorides can also be used, and these can be used alone or in combination.
These metal oxides or non-metallic inorganic oxides can be deposited using PVD methods such as conventionally known vacuum deposition, ion plating, and sputtering, and CVD methods such as plasma CVD and microwave CVD.

  A conventionally well-known method can be used as a method of apply | coating the black curable adhesive resin composition of this invention to a plastic film (2). Specifically, comma coating, gravure coating, reverse coating, roll coating, lip coating, spray coating, etc. can be raised.

  The thickness of the black cured adhesive layer (4) in the solar cell back surface protective sheet (V) of the present invention is preferably 0.1 to 30 μm, and more preferably 1 to 20 μm.

As the adhesive used for forming the solar cell back surface protective sheet (V) of the present invention, various types such as a hot-melt type, a UV-curable type, etc. can be used in addition to the thermosetting type.
Examples of the thermosetting adhesive include adhesives formed by blending various polyol components and curing agent components represented by isocyanate components. For example, Toyo Morton Co., Ltd. trade name: Dyna Grand, Shin-Etsu Polymer Co., Ltd. trade name: Polymer Ace. Examples of hot melt adhesives include products manufactured by Toray Dow Corning Co., Ltd.
The adhesive used for the formation of the solar cell back surface protective sheet (V) of the present invention is not limited to such examples.

Next, the solar cell module will be described with reference to FIGS.
The solar cell module is formed by laminating a surface protection member (I) positioned on the light receiving surface side of the solar cell module, a sealant layer (II) positioned on the light receiving surface side, and a solar cell (III). The sealing agent layer (IV) located on the non-light-receiving surface side of the battery module and the solar cell back surface protection sheet (V) are sequentially stacked. The black curable adhesive resin layer (4 ′) in the solar cell back surface protective sheet (V) is arranged in contact with the sealant layer (IV). That is, the solar cell so that the black curable adhesive resin layer (4 ′) constituting the solar cell back surface protective sheet (V) shown in FIGS. 2, 3 and 4 is in contact with the sealant layer (IV). Stack the back protection sheet (V).
Next, the sealing agent layers (II) and (IV) located on the light receiving surface side and the non-light receiving surface side are melted and softened by thermocompression using a vacuum laminator, and the layers are joined to form a solar cell module.
As shown in FIG. 1, solar cells that are sensitive to water and humidity are sealed in the sealant layers (II) and (IV), and the sealant layers (II) and (IV) are further used as a surface protective material. The solar battery cell is protected from water and humidity by being sandwiched between the back surface protection sheets.

Solar cell modules need to withstand long-term use of 10 or 20 years.
In the solar cell module shown in FIG. 1, when the black cured adhesive layer (4) (not shown) deteriorates, the sealing state between the encapsulant layer (IV) and the solar cell back surface protective sheet (V) is impaired, Water and water vapor penetrate and cause deterioration of the solar battery cell. When the solar cell is deteriorated, the power generation efficiency is lowered or a failure is caused.
Even if the black cured adhesive layer (4) itself does not deteriorate, the plastic film (2), the black cured adhesive layer (4), the black cured adhesive layer (4), and the sealant layer (IV) against heat and humidity. When the shrinkage rate and expansion rate are greatly different from each other, when heat and humidity are repeatedly applied, the interface between the plastic film (2) and the black cured adhesive layer (4), the black cured adhesive layer (4) and the sealant There is a risk of distortion occurring at the interface with the layer (IV), partial floating, and eventually peeling.
The black curable adhesive resin composition of the present invention can form a black cured adhesive layer (4) that does not deteriorate or peel even under severe conditions over a long period of time.

  The temperature of the vacuum laminator is usually about 130 to 160 ° C, and 150 ° C is common. The above-mentioned module material is placed on a heater in a vacuum laminator in a superposed state, and the inside is vacuumed and laminated for about 10 to 30 minutes. After vacuum laminating for about 15 minutes, it may be further heated for about 15 minutes in an oven at about 130 to 160 ° C. at normal pressure.

As the sealant layer (II) and the sealant layer (IV), an ethylene-vinyl acetate copolymer (EV
A) is often used.
When peroxide is added to EVA in advance, sealant layer (II) and sealant layer (IV) are improved in heat resistance by thermally melting and crosslinking EVA by heating during vacuum lamination. Solar cell (III) can be fixed inside.

  Although it does not specifically limit as solar cell surface protection member (I), As a general example, plastic plates, such as a glass plate, a polycarbonate plate, a polyacrylate plate, can be raised. In view of transparency, weather resistance, toughness and the like, a glass plate is preferable. Furthermore, white glass with high transparency is preferable among the glass plates.

  As the solar cell (III), an electrode is provided on a photoelectric conversion layer such as crystalline silicon, amorphous silicon, and a compound semiconductor represented by copper indium selenide, and further, these are laminated on a substrate such as glass. Etc. can be illustrated.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited by a following example. In the examples, “parts” represents “parts by mass” and “%” represents “% by mass”.

Synthesis Example 1 “Acrylic Copolymer A-1 Solution”
A four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen introducing tube was charged with 150 parts of ethyl acetate, and the temperature was raised to 77 ° C. while stirring in a nitrogen atmosphere. When the temperature in the flask reached 77 ° C., 10.00 parts of methyl methacrylate, 88.74 parts of n-butyl methacrylate, 0.70 parts of 2-hydroxyethyl methacrylate, 0.56 parts of dimethylaminoethyl methacrylate Then, a monomer solution mixed with 0.30 part of azobisisobutyronitrile was added dropwise over 2 hours.
The reaction was continued by adding 0.03 parts of azobisisobutyronitrile every hour from 1 hour after the completion of the monomer addition, and the reaction was continued until the unreacted monomer in the solution was 1% or less. When the unreacted monomer was 1% or less, the reaction was terminated by cooling to obtain an acrylic copolymer A-1 solution having a solid content of about 40%.
Acrylic copolymer A-1 has an amine value of 2.0 (mg KOH / g), an acid value of 0 (mg KOH / g), a hydroxyl value of 3.1 (mg KOH / g), a weight average molecular weight of 123, 000.

Synthesis Examples 2 to 10 and 12 to 17 “acrylic copolymers A-2 to A-10, A-12 to A-17 solutions”
Reaction was performed according to the composition of Tables 1 and 2, and acrylic copolymers A-2 to A-10 and A-12 to A-17 solutions were obtained. Tables 1 and 2 show the solid content, amine value, acid value, hydroxyl value, and weight average molecular weight.
The solid content, amine value, acid value, hydroxyl value, and weight average molecular weight (Mw) were measured by the methods described below.

Synthesis Example 11 “Acrylic Copolymer A-11 Solution”
The reaction was carried out according to the composition shown in Table 1, and methyl methacrylate, n-butyl methacrylate, 2-hydroxyethyl methacrylate, dimethylaminoethyl methacrylate were copolymerized in the same manner as in Example 1. Thereafter, 2.39 parts of methacrylic acid = 2-isocyanatoethyl was added and reacted with 50% of the hydroxyl group derived from 2-hydroxyethyl methacrylate. The reaction was terminated by confirming that the isocyanate group had disappeared using an infrared spectroscopic analyzer, and an acrylic copolymer A-11 solution into which a methacryloyl group had been introduced was obtained.
Acrylic copolymer A-11 has an amine value of 5.2 (mg KOH / g), an acid value of 0 (mg KOH / g), a hydroxyl value of 8.7 (mg KOH / g), and a weight average molecular weight of 147. 000.

<Measurement of solid content>
The weight of an aluminum pan with a lid having a diameter of 55 mm and a depth of 15 mm is measured to 4 digits after the decimal point. About 1.5 g of the resin solution is collected in an aluminum dish, and the lid is immediately covered, and the weight is quickly and accurately measured. With the lid removed, place in an oven at 150 ° C. for 10 minutes to dry. After cooling to room temperature, the weight of the aluminum pan and the lid is measured, and the solid content is calculated by the following formula.
Solid content (%) = (weight after drying−weight of aluminum dish) ÷ (weight before drying−weight of aluminum dish) × 100

<Measurement of amine value>
About 1.5 g of the resin solution is accurately weighed into a stoppered Erlenmeyer flask, and 50 ml of methyl ethyl ketone is further added and dissolved. Automatic titration is performed using a potentiometric titrator manufactured by Kyoto Electronics Co., Ltd. using 0.02 mol / L perchloric acid (dioxane solution) as a titration reagent. The maximum inflection point on the titration curve is taken as the equivalent point, and the titration amount of 0.02 mol / L perchloric acid (dioxane solution) at this time is determined.
The amine value is determined by the following formula. The amine value was a numerical value of the dry state of the resin.
Amine value (mgKOH / g) = (a × F × 56.1 × 0.02) / S
S: Amount of sample collected x (solid content of sample / 100) (g)
a: Titration amount (ml) of 0.02 mol / L perchloric acid (dioxane solution)
F: 0.02 mol / L perchloric acid (dioxane solution) titer

<Measurement of acid value (AV)>
About 1 g of the resin solution is accurately weighed in a stoppered Erlenmeyer flask, and dissolved by adding 50 ml of a toluene / ethanol (volume ratio: toluene / ethanol = 2/1) mixed solution. To this is added phenolphthalein reagent as an indicator and held for 30 seconds. Thereafter, the solution is titrated with a 0.1 mol / L alcoholic potassium hydroxide solution until the solution becomes light red.
The acid value was determined by the following formula. The acid value is a numerical value of the dry state of the resin.
Acid value (mgKOH / g) = (a × F × 56.1 × 0.1) / S
S: Amount of sample collected x (solid content of sample / 100) (g)
a: Titration of 0.1 mol / L alcoholic potassium hydroxide solution (ml)
F: Potency of 0.1 mol / L alcoholic potassium hydroxide solution

<< Measurement of hydroxyl value (OHV) >>
About 1 g of the resin solution is accurately weighed in a stoppered Erlenmeyer flask, and dissolved by adding 50 ml of a toluene / ethanol (volume ratio: toluene / ethanol = 2/1) mixed solution. Further, 5 ml of an acetylating agent (a solution in which 25 g of acetic anhydride is dissolved in pyridine to make a volume of 100 ml) is added accurately, heated to 100 ° C. and stirred for about 1 hour. To this, phenolphthalein reagent is added as an indicator and lasts for 30 seconds. Thereafter, the solution is titrated with a 0.5 mol / L alcoholic potassium hydroxide solution until the solution becomes light red. Separately, as a blank test, a solution obtained by adding an acetylating agent only to a toluene / ethanol mixed solution and heating at 100 ° C. for 1 hour is titrated with a 0.5 mol / L alcoholic potassium hydroxide solution.
The hydroxyl value was determined by the following formula. The hydroxyl value was a numerical value of the dry state of the resin.
Hydroxyl value (mgKOH / g) = {(ba) × F × 56.1 × 0.5} / S + D
S: Amount of sample collected x (solid content of sample / 100) (g)
a: Titration volume of 0.5 mol / L alcoholic potassium hydroxide solution (ml)
b: Titration volume of 0.5 mol / L alcoholic potassium hydroxide solution in the blank experiment (ml)
F: Potency of 0.5 mol / L alcoholic potassium hydroxide solution D: Acid value (mgKOH / g)

<< Weight average molecular weight (Mw) >>
The measurement was performed using a Shodex GPC-104 / 101 system manufactured by Showa Denko.
Column Shodex KF-805L + KF-803L + KF-802
Detector Differential refractometer (RI)
Column temperature 40 ° C
Eluent Tetrahydrofuran (THF)
Flow rate 1.0ml / min
Sample concentration 0.02%
Standard sample for calibration curve TSK standard polystyrene

"Production of blocked polyisocyanate compound (c1-1)"
A trimethylolpropane (TMP) adduct of isophorone diisocyanate (IPDI) blocked with methylethylketoxime is diluted with ethyl acetate to obtain a solution of blocked polyisocyanate compound (c1-1) as a resin solution having a solid content of 50%. It was.

"Production of blocked polyisocyanate compound (c1-2)"
The isocyanurate form of hexamethylene diisocyanate (HDI) blocked with 3,5-dimethylpyrazole was diluted with ethyl acetate to obtain a solution of a polyisocyanate compound (c1-2) having a solid content of 50%.

"Production of blocked polyisocyanate compound (c1-3)"
A mixed uretate of IPDI and HDI blocked with methyl ethyl ketoxime was diluted with ethyl acetate to obtain a solution of a polyisocyanate compound (c1-3) having a solid content of 50%.

“Production of Unblocked Polyisocyanate Compound (c2)”
The isocyanurate form of hexamethylene diisocyanate (HDI) was diluted with ethyl acetate to obtain a solution of a polyisocyanate compound (c2) having a solid content of 50%.

"Example 1"
To 100 parts (solid weight) of the acrylic copolymer (A-1) obtained in Synthesis Example 1, 4 parts of carbon black MA-100 manufactured by Mitsubishi Chemical Corporation was added as a black pigment (B), and the solid content was 35. % Toluene was added. Glass beads were added to this pigment mixed solution, and dispersed for 3 hours with Scandic to obtain a dispersion. 5 parts (solid weight) of the blocked polyisocyanate compound (c1-1) is added to the obtained dispersion, and toluene is further added and stirred so that the solid content is 35%, followed by black curable adhesive resin composition. I got a thing.
Table 3 shows the pigment dispersibility and storage stability of the black curable adhesive resin composition at this time.

The obtained black curable adhesive resin composition is applied to a base film using a bar coater, dried in an oven at 100 ° C. for 1 minute to volatilize the solvents, and then black cured on the base film. The laminated body 1 in which the adhesive resin layer was formed was obtained. A polyester film (Tetron S (registered trademark), thickness 188 μm, double-sided corona treatment) manufactured by Teijin DuPont Films was used as the base film. The bar coater was selected so that the film thickness after drying was 5 μm.
The laminate 1 was evaluated for the insoluble content (%) with respect to methyl ethyl ketone, the initial adhesiveness to EVA, and the wet adhesive heat aging over EVA.

"Examples 2, 4, 5, 7, 8, 9, 11, 12, 14, 15, 16", "Comparative examples 4, 6-11"
According to the composition of Table-3, a black curable adhesive resin composition was obtained in the same manner as in Example 1, and further applied to a base film to obtain a laminate 1. Evaluation was performed in the same manner as in Example 1.

"Examples 3, 6, 10, 13", comparative examples "1, 2, 3, 5, 12"
According to the composition of Table-3, a black curable adhesive resin composition was obtained in the same manner as in Example 1.
Next, the obtained black curable adhesive resin composition was applied to a base film using a bar coater and dried in an oven at 100 ° C. for 1 minute to volatilize the solvents. Next, the laminate 2 is obtained by allowing the acrylic copolymer and the polyisocyanate compound to age for 4 days in a thermostatic chamber at 50 ° C. to form a black curable adhesive resin layer on the base film. It was. Then, it evaluated by the method similar to Example 1. FIG.

<Pigment dispersibility>
The state of the dispersion immediately after being dispersed for 3 hours with Scandex was visually evaluated.
A: The dispersion liquid has fluidity, and when the container is tilted, the dispersion liquid immediately flows.
○: Although the dispersion has fluidity, it takes time for the dispersion to flow by tilting the container.
(Triangle | delta): Although a dispersion liquid does not have fluidity | liquidity, it will flow, if it stirs lightly with a spatula.
X: The dispersion liquid has no fluidity, and even if the container is tilted, the dispersion liquid remains as it is.

<Storage stability>
After being dispersed with Scandyx, the glass beads were separated and left in a constant temperature room at 40 ° C. for 2 weeks, and the state of the dispersion was visually evaluated after 2 weeks.
A: The dispersion liquid has a low viscosity and is not different from that immediately after the dispersion of the scan dicks.
○: Although the fluidity of the dispersion is lost, it will flow when stirred gently with a spatula.
Δ: There was fluidity immediately after dispersion, but there was no fluidity after 2 weeks.
X: The dispersion is separated into a resin layer and a pigment layer.

<< Insoluble matter in MEK (methyl ethyl ketone) (%) >>
The base film is cut into a size of 10 cm × 10 cm in advance, and the weight (X) is obtained. Next, the black curable adhesive resin composition obtained in each Example and Comparative Example was applied to the film with a bar coater so that the film thickness after drying was 15 μm. Dry and cure under the conditions described above to obtain a sample. The weight (Y) of the sample is measured. Thereafter, the sample is put in a container containing 500 ml of methyl ethyl ketone and shaken and stirred at 25 ° C. for 1 hour. After 1 hour, remove the sample from the methyl ethyl ketone, flush the surface with fresh methyl ethyl ketone, and then dry the sample at room temperature. The weight (Z) of the sample is measured after drying. The solvent insoluble content (%) is calculated from the following formula.
Solvent insoluble content (%) = {(Z) − (X)} ÷ {(Y) − (X)} × 100

<Preparation of adhesive strength evaluation sample>
A laminated body 1 and a laminated body 2 in which a black curable adhesive resin layer is formed on a white plate glass, a vinyl acetate-ethylene copolymer film (manufactured by Sanvic Co., Ltd., standard cure type, hereinafter referred to as EVA film), a polyester film, In a state where the black curable adhesive resin layers are sequentially stacked so as to contact the EVA film, they are put in a vacuum laminator, evacuated to about 1 Torr, heated at 150 ° C. for 30 minutes at a press pressure of 0.1 MPa, and then at normal pressure. The sample was further heated at 150 ° C. for 30 minutes to produce a 10 cm × 10 cm square adhesive strength evaluation sample.

<Adhesiveness to EVA-after initial and wet heat test>
From the polyester film side of the sample for adhesive strength evaluation, it was cut into a width of 15 mm with a cutter until it reached the surface of the EVA film, and the adhesive strength between the EVA film and the black cured adhesive layer was measured. For the measurement, a tensile tester was used, and a 180 degree peel test was performed at a pulling speed of 100 mm / min. The obtained measurement values were evaluated as follows.
The sample for evaluating the adhesive strength is stored for 2000 hours under environmental conditions of a temperature of 85 ° C. and a relative humidity of 85% RH, and a moisture-resistant heat treatment is performed. It was taken out after 2000 hours, and the adhesive force to EVA was measured in the same manner as described above.
A: 50 N / 15 mm or more.
A: 30 N / 15 mm or more to less than 50 N / 15 mm.
(Triangle | delta): 10N / 15mm or more-less than 30N / 15mm.
X: Less than 10N / 15mm.
The results are shown in Table-3.

From the result of Table-3, the black curable adhesive resin composition of the present invention using the acrylic copolymer (A) having an amine value of 0.5 (mgKOH / g) or more of the present invention is carbon. The dispersibility of the black pigment is excellent, and the storage stability is also good.
On the other hand, the acrylic copolymer used in Comparative Example 1 and Comparative Example 3 has an amine value of 0, and the black curable adhesive resin composition using the acrylic copolymer has a carbon black pigment dispersibility and storage. Stability is very bad.
In Comparative Examples 6 and 7, an acrylic copolymer having no amine value was used, and a monomer having an amine value, dimethylaminoethyl methacrylate (DM), or methacrylic acid = 1, 2, 2 , 6,6-pentamethyl-4-piperidinyl (HALS (1)). The addition of a monomer having a simple amine value does not have the dispersibility of the carbon black pigment.
In Comparative Example 8, as disclosed in Patent Documents 2, 3, and 4, a pigment dispersant is used. Solspers 24000SC (trade name, manufactured by Nippon Lubrizol Co., Ltd., active ingredient 100 mass%, weight average molecular weight: 5300, hydroxyl value: 106 mgKOH / g, amine value 42 mgKOH / g) as a commercially available dispersant having an amine value It is what was added. Since it has an amine value, the dispersibility of the carbon black pigment is excellent, but the storage stability is poor because the weight average molecular weight is small. Further, since the hydroxyl value is too large, the resistance to EVA wet heat aging is poor.

  From the results of Examples 1 to 16, the acrylic copolymer (A) having an amine value of 0.5 (mg KOH / g) or more and having a specific hydroxyl value and a weight average molecular weight is used. The black cured adhesive layer has excellent initial adhesiveness to EVA and adhesiveness to EVA wet heat over time.

  Since the acrylic copolymers used in Comparative Example 1 and Comparative Example 2 have no hydroxyl group, no crosslinking reaction occurs even when a polyisocyanate compound is blended. Therefore, the initial adhesiveness to EVA and the adhesiveness to EVA wet heat over time are inferior.

  Since the acrylic copolymer used in Comparative Example 5 has a high hydroxyl value of 41.2 (mgKOH / g), the crosslinking reaction with the isocyanate compound proceeds too much, and the adhesiveness to EVA wet heat is poor.

  Even if the hydroxyl value of the acrylic copolymer used as in Comparative Example 10 and Comparative Example 11 is appropriate, the black curable adhesive resin composition containing no polyisocyanate compound or the black curable resin containing excessive polyisocyanate compound The balance of the adhesive property to EVA wet heat of the black cured adhesive layer formed from the adhesive resin composition is lost. Comparative Example 9 is a case where the amount of carbon black pigment added is large, but results in inferior EVA wet heat adhesiveness as well as pigment dispersibility and storage stability.

  Comparative Example 4 uses an acrylic copolymer having a weight average molecular weight of 26,000. When the weight average molecular weight of the acrylic copolymer is small, the storage stability of the pigment dispersion is poor and the pigment is easily separated. Moreover, since the black cured adhesive layer laminated with the EVA film has a low molecular weight, the adhesive property to EVA wet heat is inferior.

From the above, the black curable adhesive resin composition of the present invention can be used without using a so-called pigment dispersant or the like by using a polyisocyanate compound in a specific ratio with respect to a specific acrylic copolymer. In addition, the carbon black pigment is well dispersed, and no phenomenon such as thickening, separation or sedimentation occurs during storage. In addition, a black cured adhesive layer obtained by applying these black curable adhesive resin compositions to a substrate film and drying and curing gives a film having excellent initial adhesiveness to EVA and adhesiveness to EVA over time with wet heat. .

  The black curable adhesive resin composition of the present invention is a laminate obtained by applying and curing a plastic film, a plastic molding, an aluminum foil, an aluminum plate, a copper foil, a tin plate, a galvanized steel plate, a glass plate, a glass bottle, etc. Can be used for solar cell back surface protection sheet, outdoor display, marking film, glass scattering prevention film, antireflection film, heat ray prevention film, etc.

Furthermore, the black curable adhesive resin composition of the present invention is excellent in adhesiveness with an adhesive such as a silicone-based adhesive, and has an excellent property that the adhesiveness hardly deteriorates even after a wet heat test. .
Accordingly, the black curable adhesive resin composition of the present invention includes, for example, various recording materials, IC cards, IC tags, etc., packaging materials such as chemicals and foods, back surface protection sheets for solar cells, marking films, and photosensitive properties. Resin plates, adhesive sheets, dye-sensitized solar cells, polarizing plate protecting resin films, antireflection resin films, optical diffusion films such as light diffusion films, glass scattering prevention resin films, decorative sheets, window resin films, etc. It can be used for resin films for building materials, display materials, resin films for indoor and outdoor overlays such as electric signs, and shrink films.

(I): Surface protective member (II): Light-receiving surface side sealing agent (III): Solar cell (IV): Non-light-receiving surface side sealing agent (V): Back surface protection member or solar cell back surface protection sheet ( 1): Weather-resistant protective film, weather-resistant protective layer (2): Plastic film (3): Adhesive layer (4 ′): Black curable adhesive resin layer

Claims (6)

A black curable adhesive resin composition containing an acrylic copolymer (A), a black pigment (B) and a polyisocyanate compound (C),
The acrylic copolymer (A) has a hydroxyl group of 2 to 20 (mgKOH / g), an amine value of 0.5 (mgKOH / g) or more, and a weight average molecular weight (Mw) of 40,000 to 600,000. ,
The acrylic copolymer (A): 2 to 40 parts by mass of the black pigment (B) and 1 to 20 parts by mass of the polyisocyanate compound (C) with respect to 100 parts by mass,
The ratio of the blocked polyisocyanate compound (c1) to the unblocked polyisocyanate compound (c2) in the polyisocyanate compound (C) is (c1) :( c2) = 50 or more to 100: 50 or less to 0 ( Mass ratio),
Black curable adhesive resin composition.   The black curable adhesive resin composition according to claim 1, wherein the acrylic copolymer (A) is a copolymer having a (meth) acryloyl monomer having a tertiary amino group as a copolymerization component.   The black curable adhesive resin composition of Claim 1 or 2 whose glass transition temperature of an acryl-type copolymer (A) is 20 degreeC or more. A solar cell back surface protective sheet having a black curable adhesive resin layer (4 ′) as an outermost surface layer on one surface of the plastic film (2),
The said black curable adhesive resin layer (4 ') is formed from the black curable adhesive resin composition of any one of Claims 1-3, and the insoluble matter with respect to methyl ethyl ketone is 0- The solar cell back surface protection sheet which is 50 mass%. On one side of the plastic film (2)
The black curable adhesive resin composition according to any one of claims 1 to 3 is applied to form a black curable adhesive resin layer (4 ') having an insoluble content in methyl ethyl ketone of 0 to 50% by mass. The manufacturing method of the solar cell back surface protection sheet characterized by the above-mentioned. Solar cell surface protection member (I) positioned on the light receiving surface side of the solar cell, sealant layer (II) positioned on the light receiving surface side of the solar cell, solar cell (III), on the non-light receiving surface side of the solar cell A solar cell module comprising a sealing agent layer (IV) positioned and a solar cell back surface protective sheet in contact with the non-light-receiving surface side sealing agent layer (IV),
The said solar cell back surface protection sheet is formed from the solar cell back surface protection sheet of Claim 4, and the black cured adhesive layer (4) formed from the said black curable adhesive resin layer (4 ') is provided. The solar cell module is in contact with the non-light-receiving surface side sealing agent layer (IV).

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