JP2014162824A - Polyol agent for two-liquid type laminate adhesive, resin composition, curable resin composition, adhesive for two-liquid type laminate and back sheet for solar battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a back sheet adhesive for a solar battery having a base adhesiveness under hot heat conditions and having reduced discoloration upon use over a long period.SOLUTION: The polyol agent for a two-liquid type laminate adhesion comprises polyester polyurethane polyol (A) with a resin structure obtained by reacting aliphatic polyester polyol (i) having a branched alkane structural site and a non-branched alkane structural site as the hydrocarbon structural sites of polyester in the molecule with an aliphatic multifunctional isocyanate compound (ii), and is used as the main agent of the two-liquid type laminate adhesive.

Description

  The present invention relates to a back sheet for solar cells that is excellent in substrate adhesion and UV resistance under wet heat conditions, a two-component laminating adhesive useful as the back sheet adhesive, and a curable resin composition constituting the same Product, a polyol component for a two-component laminate adhesive constituting the main component, and a resin composition.

  In recent years, the depletion of fossil fuels such as oil and coal has been threatened, and development to secure alternative energy obtained from these fossil fuels is urgently required. Among such fossil fuel alternative energy, solar power generation capable of directly converting solar energy into electric energy is being put into practical use as a new energy source that is semi-permanent and non-polluting, and is actually used. The improvement in price / performance ratio is remarkable, and it is highly expected as a clean energy source.

  Solar cells used for photovoltaic power generation constitute the heart of a photovoltaic power generation system that converts sunlight energy directly into electrical energy, and are composed of semiconductors such as silicon, In the structure, solar cell elements are wired in series and in parallel, and various packaging is applied to protect the elements so as to be unitized. A unit incorporated in such a package is called a solar cell module, and generally has a structure in which the surface exposed to sunlight is covered with glass, the gap is filled with a filler made of a thermoplastic resin, and the back surface is protected with a sealing sheet. It has become. As a filler made of a thermoplastic resin, an ethylene-vinyl acetate copolymer resin is often used because of its high transparency and excellent moisture resistance. On the other hand, the back protective sheet (back sheet) is required to have characteristics such as mechanical strength, weather resistance, heat resistance, moisture heat resistance, and light resistance. Since such a solar cell module is usually used outdoors for a long period of about 30 years, the adhesive constituting the back sheet is required to have a long-term reliable adhesive strength. In addition, high adhesion to various films having different characteristics such as polyester film and polyvinyl fluoride film, and high level of moisture and heat resistance for maintaining long-term adhesion even in an open-air environment are required.

  As such an adhesive for a back sheet, for example, a high molecular weight polyester polyol and a low molecular weight polyester polyurethane using an aromatic dibasic acid, a C9 or higher aliphatic carboxylic acid, and a C5 or higher aliphatic alcohol as raw material monomers. By using a polyisocyanate compound as a main agent in combination with a polyol and using a polyisocyanate compound as a curing agent, the cohesive strength of the resin resulting from the aromatic dibasic acid is increased, and the distance between ester bonds is increased by the long-chain aliphatic alcohol. A technique is known that improves moisture resistance and heat resistance by suppressing moisture intrusion, and improves coating properties and wettability by using a low molecular weight urethane together (see Patent Document 1 below).

  However, in recent years, solar cells with various structures and design properties have been developed for backsheet exterior films. In this case, the adhesive layer is required to have a function that does not cause deterioration due to ultraviolet rays. However, although the adhesive described in Patent Document 1 has good moisture resistance and weather resistance of the back sheet itself, discoloration due to ultraviolet rays is unavoidable during long-term outdoor use.

Japanese Patent No. 4416047

  Therefore, the problem to be solved by the present invention is to develop adhesives for two-component laminates that exhibit base adhesiveness under wet heat conditions and have less discoloration when used for a long time, and the curability that constitutes the adhesives. An object of the present invention is to provide a back sheet for a solar cell that exhibits excellent performance in a resin composition, a main component of the adhesive, and heat and moisture resistance and discoloration resistance.

  As a result of intensive studies to solve the above problems, the present inventors have reacted a polyester polyol having a branched alkane structure portion and an unbranched alkane structure portion in the molecule as a hydrocarbon structure portion of the polyester with a polyfunctional isocyanate. By using the polyester polyurethane polyol obtained as a main ingredient of the back sheet adhesive for solar cells, the base adhesiveness under wet heat conditions is remarkably excellent, and yellowing caused by ultraviolet rays can be prevented during long-term outdoor use. The inventors have found that it can be effectively prevented and have completed the present invention.

  That is, the present invention comprises reacting an aliphatic polyester polyol (i) having a branched alkane structure moiety and an unbranched alkane structure moiety in the molecule as a hydrocarbon structure moiety of a polyester with an aliphatic polyfunctional isocyanate compound (ii). It is related with the polyol agent for two-component laminate adhesives containing the polyester polyurethane polyol (A) which has the resin structure obtained in this way.

  The present invention further relates to a resin composition comprising the novel polyester polyurethane polyol (A) and the polyfunctional epoxy compound (B) as essential components.

  The present invention further relates to a curable resin composition using the novel polyester polyurethane diol or the resin composition as a main agent and blended with an aliphatic polyisocyanate (D) as a curing agent.

  The present invention further relates to a two-component laminating adhesive comprising a curable resin composition.

  The present invention further includes at least one film selected from the group consisting of a polyester film, a fluororesin film, a polyolefin film, and a metal foil, and the two-component laminate according to claim 10 for bonding these films together. It is related with the solar cell backsheet shape | molded from the contact bonding layer which consists of adhesives for water.

  ADVANTAGE OF THE INVENTION According to this invention, while exhibiting the base adhesiveness in wet-heat conditions, the adhesive for two-component laminates with little discoloration at the time of long-term use, the curable resin composition which comprises this adhesive, this adhesion It is possible to provide a back sheet for a solar cell that exhibits excellent performance in the main component of the agent, and heat and moisture resistance and discoloration resistance.

  The polyol component for a two-component laminate adhesive of the present invention is used as a main component of a solar cell backsheet adhesive, and includes a branched alkane structure portion and an unbranched alkane structure portion in the molecule as a hydrocarbon structure portion of polyester. The polyester polyurethane polyol (A) having a resin structure obtained by reacting the aliphatic polyester polyol (i) having an aliphatic polyfunctional isocyanate compound (ii) as an essential component.

  Here, the aliphatic polyester polyol (i), which is a main raw material component of the polyester polyurethane polyol (A), has a branched alkane structure moiety (i) as a hydrocarbon group knotted by a carbonyloxy group constituting the polyester. -A) and the unbranched alkane structure site (ib) coexist, thereby exhibiting excellent flexibility and wettability as an adhesive and exhibiting good substrate adhesion after aging. In addition, it is possible to effectively prevent water from entering the cured product, and to exhibit excellent adhesion to the base material over a long period of time in a moist heat environment. Such a branched alkane structure site means an alkane having a tertiary carbon atom or a quaternary carbon atom in the alkane structure site, and becomes a site that forms a bulky structure in the aliphatic polyester polyol (i). . On the other hand, the unbranched alkane structural site refers to a linear alkane having no tertiary carbon atom or quaternary carbon atom in the structural site.

  In addition, the proportion of the branched alkane structure site (ia) and the unbranched alkane structure site (ib) in the aliphatic polyester polyol (i) is determined by the molar ratio [(ia) / (i− b)] is preferably in a ratio of 1/3 to 3/1 from the viewpoint of better substrate adhesion in a moist heat environment.

The aliphatic polyester polyol (i) can be produced by reacting a branched alkane polyol (i-1), an unbranched alkanediol (i-2), and an aliphatic dicarboxylic acid (i-3). The proportion of the branched alkane structure moiety (ia) and the unbranched alkane structure moiety (ib) in the aliphatic polyester polyol (i) thus prepared can be adjusted by the reaction ratio of each of these raw material components. it can.
Here, the branched alkane structure site (ia) is a structure derived from the branched alkane polyol (i-1), but the aliphatic dicarboxylic acid (i-3) is a tertiary carbon atom or quaternary. When it contains a carbon atom, the branched alkane structure site (ia) can be introduced into the aliphatic polyester polyol (i) by the (i-3).

  Examples of the branched alkane polyol (i-1) that can be used here include 1,2-propylene glycol, 1,3-butylene glycol, 2-methyl-1,3-propanediol, neopentyl glycol, and 3-methyl. -1,5-pentanediol, 2-n-butyl-2-ethyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol Trifunctional or tetrafunctional polyhydric alcohols such as alkanediols such as 2,4-diethyl-1,5-pentanediol, 1,2-hexane glycol, 1,2-octyl glycol, trimethylolpropane, pentaerythritol, etc. Can be mentioned. In the present invention, among these, alkanediol is preferred, and neopentyl glycol is particularly preferred from the viewpoint that an adhesive having excellent wettability and heat resistance is obtained while being excellent in coating property to a substrate.

  On the other hand, as the unbranched alkanediol (i-2), specifically, ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,8-nonanediol, Examples include linear alkanediols such as diethylene glycol. Among these, 1,6-hexanediol is preferable from the viewpoint of obtaining an adhesive having excellent adhesion to a substrate.

  Examples of the aliphatic dicarboxylic acid (i-3) include a linear aliphatic dicarboxylic acid or a branched aliphatic dicarboxylic acid having a tertiary carbon atom or a quaternary carbon atom in the molecular structure.

  Examples of linear aliphatic dicarboxylic acids include malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, Examples include pentadecanedioic acid, hexadecanedioic acid, heptadecanedioic acid, octadecanedioic acid, nonadecanedioic acid, icosanedioic acid, and the like.

  Moreover, as the branched aliphatic having a tertiary carbon atom or a quaternary carbon atom having a branched structure in the molecular structure, a saturated aliphatic dibasic having a branched structure such as hexahydrophthalic acid or 1,4-cyclohexanedicarboxylic acid. Examples include acids and anhydrides thereof; aliphatic unsaturated dibasic acids having a branched structure such as tetrahydrophthalic acid, citraconic acid, and itaconic acid, and anhydrides thereof.

  In the present invention, it is preferable to use a linear aliphatic dicarboxylic acid as the aliphatic dicarboxylic acid (i-3) from the viewpoint of obtaining an adhesive having excellent adhesion to a substrate and heat and moisture resistance among these. In particular, dicarboxylic acids having 6 to 10 carbon atoms such as adipic acid, azelaic acid and sebacic acid are preferred.

  In the present invention, for the purpose of adjusting the molecular weight and viscosity of the aliphatic polyester polyol (i), as raw materials for the polyester polyurethane polyol (A), methanoic acid, ethanoic acid, propanoic acid, butanoic acid, pentanoic acid, Monocarboxylic acids such as hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, and benzoic acid may be used.

Next, the conditions for reacting the branched alkane polyol (i-1), unbranched alkanediol (i-2), and aliphatic dicarboxylic acid (i-3) described above are, for example, branched alkane polyol (i-1). , Unbranched alkanediol (i-2) and aliphatic dicarboxylic acid (i-3) in the presence of an esterification catalyst in a temperature range of 180 to 270 ° C.
The reaction ratio of each component is such that the molar ratio [(i-1) / (i-2)] with the branched alkane polyol (i-1) and the unbranched alkanediol (i-2) is 1/2 to 10. The molar ratio of the hydroxyl group of the branched alkane polyol (i-1) and unbranched alkanediol (i-2) to the carboxyl group of the aliphatic dicarboxylic acid (i-3) [ Hydroxyl / carboxyl group] is preferably in a ratio of 3/1 to 1/1 from the viewpoint of excellent substrate adhesion under wet heat conditions.

  The aliphatic polyester polyol (i) thus obtained has a number average molecular weight (Mn) in the range of 500 to 5,000, and the finally obtained polyester polyurethane polyol (A) is used for an adhesive. When used as a base agent, it has excellent wettability to the base and flexibility, moderately prevents water from entering the adhesive layer, improves moisture and heat resistance, and exhibits excellent performance in UV resistance To preferred.

  The polyester polyurethane polyol (A) can be produced by reacting the aliphatic polyester polyol (i) thus obtained with an aliphatic polyfunctional isocyanate compound (ii).

  Examples of the aliphatic polyfunctional isocyanate compound (ii) include an aliphatic diisocyanate compound (ii-1) and a trifunctional or higher functional aliphatic polyisocyanate compound (ii-2).

  Examples of the aliphatic diisocyanate compound (ii-1) include butane-1,4-diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, and xylylene diene. Aliphatic diisocyanates such as isocyanate and m-tetramethylxylylene diisocyanate;

  Cyclohexane-1,4-diisocyanate, isophorone diisocyanate, lysine diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, 1,3-bis (isocyanatemethyl) cyclohexane, methylcyclohexane diisocyanate, isopropylidene dicyclohexyl-4,4′-diisocyanate, And alicyclic diisocyanates such as norbornane diisocyanate.

  On the other hand, examples of the trifunctional or higher polyisocyanate compound (ii-2) include adduct type polyisocyanate compounds having a urethane bond site in the molecule and nurate type polyisocyanate compounds having an isocyanurate ring structure in the molecule. It is done.

  The adduct type polyisocyanate compound having a urethane bond site in the molecule can be obtained, for example, by reacting the diisocyanate compound (ii-1) with the aliphatic polyester polyol (i).

  In addition, the nurate type polyisocyanate compound having an isocyanurate ring structure in the molecule can be obtained, for example, by reacting a diisocyanate compound in the presence of an isocyanuration catalyst in a temperature range of 40 to 100 ° C. .

  Here, examples of the diisocyanate compound include the aliphatic diisocyanate compound (ii-1).

  Here, by using the tri- or higher functional polyisocyanate compound (ii-2), the degree of branching of the above-described polyester polyurethane polyol (A) is increased, and the moisture and heat resistance can be further improved.

  Among the above-mentioned various compounds, the aliphatic polyfunctional isocyanate compound (ii) is preferably isophorone diisocyanate from the viewpoint of obtaining an adhesive that is particularly excellent in coatability to a substrate and excellent in heat and moisture resistance.

  The conditions for reacting the aliphatic polyester polyol (i) with the aliphatic polyfunctional isocyanate compound (ii) are as follows. Specifically, the aliphatic polyester polyol (i) is reacted with the aliphatic polyfunctional isocyanate compound (ii). In the presence of a urethanization catalyst in a temperature range of 60 to 100 ° C.

  The polyester polyurethane polyol (A) thus obtained preferably has a weight average molecular weight (Mw) in the range of 10,000 to 200,000. When the weight average molecular weight (Mw) is in this range, the cured product exhibits high strength, and the resin composition has excellent initial adhesive strength, and the resin composition has a viscosity suitable for coating. . That is, when the weight average molecular weight (Mw) is less than 10,000, the initial adhesive strength is lowered, and the viscosity is low, so that the resin composition is difficult to apply uniformly. On the other hand, when it exceeds 200,000, it becomes a resin composition that is difficult to apply due to its high viscosity. Among them, the weight average molecular weight (Mw) is in the range of 10,000 to 150,000 in that a resin composition having high initial adhesive strength and excellent base material adhesion under wet heat conditions can be obtained. It is preferable.

  The polyester polyurethane polyol (A) preferably has a molecular weight distribution (Mw / Mn) in the range of 2.0 to 15. That is, when the molecular weight distribution (Mw / Mn) is within the above range, the effect of improving the adhesion to the substrate due to the low molecular weight component and the effect of increasing the strength of the cured product due to the high molecular weight component. Are exhibited simultaneously, so that the resin composition is excellent in base material adhesion under wet heat conditions and has high initial adhesive strength. Specifically, when the molecular weight distribution (Mw / Mn) is 2.0 or more, the initial adhesive strength is improved. Especially, it is especially preferable that molecular weight distribution (Mw / Mn) is the range of 2.0-10.0 at the point from which the resin composition which is excellent by the base-material adhesiveness in wet heat conditions is obtained.

  Furthermore, the number average molecular weight (Mn) of the said polyester polyurethane polyol (A) is excellent in the base-material adhesiveness on wet-heat conditions, and becomes a resin composition of the viscosity suitable for coating from 5,000-50. Is preferably in the range of 6,000, particularly preferably in the range of 6,000 to 30,000.

  In the present invention, the weight average molecular weight (Mw) and the number average molecular weight (Mn) are values measured by gel permeation chromatography (GPC) under the following conditions.

Measuring device: HLC-8220GPC manufactured by Tosoh Corporation
Column: TSK-GUARDCOLUMN SuperHZ-L manufactured by Tosoh Corporation
+ Tosoh Corporation TSK-GEL SuperHZM-M x 4
Detector: RI (differential refractometer)
Data processing: Multi-station GPC-8020 model II manufactured by Tosoh Corporation
Measurement conditions: Column temperature 40 ° C
Solvent tetrahydrofuran
Flow rate: 0.35 ml / min Standard: Monodispersed polystyrene Sample: Filtered 0.2% by mass tetrahydrofuran solution in terms of resin solids with a microfilter (100 μl)

  Further, the hydroxyl value of the polyester polyurethane polyol (A) is preferably in the range of 2 to 30 mgKOH / g, more preferably in the range of 5 to 20 mgKOH / g, in terms of excellent substrate adhesion under wet heat conditions. It is more preferable.

  The polyester polyurethane polyol (A) described in detail above can be used alone as a polyol agent for a two-component laminate adhesive with a curing agent. In the present invention, the polyester polyurethane polyol (A), It is preferable to use a resin composition containing a polyfunctional epoxy compound (B) as a main component of a two-component laminate adhesive. That is, by using the polyfunctional epoxy compound (B) in addition to the polyester polyurethane polyol (A), the adhesive layer absorbs moisture, and captures the carboxy group generated by hydrolysis of the polyester polyurethane polyol (A). The moisture and heat resistance of the adhesive layer can be further improved. The polyfunctional epoxy compound (B) is preferably a hydroxyl group-containing epoxy resin having a number average molecular weight (Mn) in the range of 300 to 5,000. That is, when the number average molecular weight (Mn) is 300 or more, in addition to the heat and moisture resistance, the adhesion strength to the substrate is further improved, and when the number average molecular weight (Mn) is 5,000 or less. The compatibility with the polyester polyurethane polyol (A) will be good. From the viewpoint of excellent balance, those having a number average molecular weight (Mn) in the range of 400 to 2,000 are more preferable.

  Moreover, since the polyfunctional epoxy compound (B) provides a resin composition with more excellent curability, the hydroxyl value is preferably in the range of 30 to 160 mgKOH, and in the range of 50 to 150 mgKOH / g. Is more preferable.

  The polyfunctional epoxy compound (B) is, for example, a bisphenol type epoxy resin such as a bisphenol A type epoxy resin or a bisphenol F type epoxy resin; a biphenyl type epoxy resin such as a biphenyl type epoxy resin or a tetramethylbiphenyl type epoxy resin; Examples include pentadiene-phenol addition reaction type epoxy resins. These may be used alone or in combination of two or more. Among these, a bisphenol type epoxy resin is preferable in that a resin composition excellent in base material adhesion under wet heat conditions and initial adhesive strength can be obtained.

  Furthermore, the resin composition can drastically increase the crosslinking density of the cured product by using the polyester polyurethane polyol (A) and the polyfunctional epoxy compound (B) together with a hydroxyl group-containing aliphatic polycarbonate (C). It is possible to improve the adhesion to the substrate.

  The hydroxyl group-containing aliphatic polycarbonate (C) used here has a number average molecular weight (Mn) in the range of 5 to 3,000. The hydroxyl group concentration is moderately high, and the crosslinking density during curing is significantly improved. The number average molecular weight (Mn) is particularly preferably in the range of 800 to 2,000.

  The hydroxyl group-containing aliphatic polycarbonate (C) has a hydroxyl value in the range of 20 to 300 mgKOH / g, particularly in the range of 40 to 250 mgKOH / g, in that it becomes a resin composition with more excellent curability. More preferred. Moreover, it is preferable that it is polycarbonate diol at the point which is excellent in the base-material adhesiveness on wet heat conditions.

  Here, the hydroxyl group-containing polycarbonate (C) can be produced, for example, by a polycondensation reaction of a polyhydric alcohol and a carbonylating agent.

  Examples of the polyhydric alcohol used in the production of the hydroxyl group-containing polycarbonate (C) include the compounds mentioned as the branched alkane polyol (i-1) or unbranched alkane diol (i-2) as the raw material of the above-described novel polyester polyurethane diol. Can be used.

  Examples of the carbonylating agent used in the production of the hydroxyl group-containing polycarbonate (C) include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, dibutyl carbonate, diphenyl carbonate and the like. These may be used alone or in combination of two or more.

  The resin composition of the present invention comprises the polyester polyurethane polyol (A), the polyfunctional epoxy compound (B), and the hydroxyl group-containing polycarbonate resin (C) with respect to 100 parts by mass of the polyester polyurethane polyol (A). When the polyfunctional epoxy compound (B) is contained in a proportion in the range of 5 to 20 parts by mass and the polycarbonate resin (C) is contained in a proportion in the range of 5 to 20 parts by mass, It is preferable from the viewpoint that the resin composition is excellent in adhesion to the substrate and can maintain high substrate adhesion even under wet heat conditions.

  The resin composition of the present invention may contain other hydroxyl group-containing compounds of the polyester polyurethane polyol (A), the polyfunctional epoxy compound (B), and the hydroxyl group-containing polycarbonate resin (C). Such a hydroxyl group-containing compound has, for example, a number average molecular weight (Mw) obtained by reacting a polyester polyol, polybasic acid, polyhydric alcohol and polyisocyanate obtained by reacting a polybasic acid with a polyhydric alcohol. Polyester polyurethane polyols less than 25,000, linear polyester polyurethane polyols obtained by reacting dibasic acids, diols and diisocyanates, ether glycols such as polyoxyethylene glycol and polyoxypropylene glycol, bisphenol A, bisphenol F, etc. Bisphenol, and alkylene oxide adducts of bisphenol obtained by adding ethylene oxide, propylene oxide and the like to the bisphenol. These may be used alone or in combination of two or more.

  When the resin composition of the present invention contains the polyester polyurethane polyol (A), the polyfunctional epoxy compound (B), and other hydroxyl group-containing compounds of the hydroxyl group-containing polycarbonate resin (C), various kinds of substrates are used. Since the resin composition which is excellent in adhesiveness and can maintain high base-material adhesiveness even under wet heat conditions is obtained, the content thereof is 5 to 20 with respect to 100 parts by mass of the polyester polyurethane polyol (A). It is preferable that it is the ratio used as the range of a mass part.

  The curable resin composition of the present invention is mainly composed of a polyol composition for a two-component laminate adhesive containing the polyester polyurethane polyol (A) or a resin composition containing the components (A) to (C). The aliphatic polyisocyanate (D) is used as the curing agent.

  Examples of the aliphatic polyisocyanate (D) include various polyisocyanates listed as the aliphatic polyfunctional isocyanate compound (ii). These polyisocyanate (D) may be used individually by 1 type, and may use 2 or more types together.

  Among these aliphatic polyisocyanates (D), the nurate type polyisocyanate compound is preferable in terms of excellent substrate adhesion under wet heat conditions.

  In this invention, since it becomes a curable resin composition which is more excellent in curability, the total number of moles of hydroxyl groups contained in the polyester polyurethane polyol (A), the epoxy compound (B) and the hydroxyl group-containing polycarbonate resin (C). The ratio [OH] / [NCO] of [OH] to the number of moles [NCO] of isocyanate groups contained in the aliphatic polyisocyanate (D) is preferably in the range of 1/1 to 1/2. More preferably, the range is 1 / 1.05 to 1 / 1.5.

  Moreover, when the above-mentioned resin composition used as a main ingredient contains the said polyester polyurethane polyol (A), the said polyfunctional epoxy compound (B), and the other hydroxyl-containing compound of the said hydroxyl-containing polycarbonate (C), the said hardening Ratio [OH] / [NCO] of the total number of moles [OH] of hydroxyl groups in the functional resin composition to the number of moles [NCO] of isocyanate groups contained in the polyisocyanate compound (D) is 1/1 to 1. / 2 is preferable, and a range of 1 / 1.05 to 1 / 1.5 is more preferable.

  The curable resin composition of the present invention may further contain various solvents. Examples of the solvent include ketone compounds such as acetone, methyl ethyl ketone (MEK) and methyl isobutyl ketone, cyclic ether compounds such as tetrahydrofuran (THF) and dioxolane, and ester compounds such as methyl acetate, ethyl acetate and butyl acetate. Aromatic compounds such as toluene and xylene, and alcohol compounds such as carbitol, cellosolve, methanol, isopropanol, butanol, and propylene glycol monomethyl ether. These may be used alone or in combination of two or more.

  The curable resin composition of the present invention further includes various additives such as an ultraviolet absorber, an antioxidant, a silicon-based additive, a fluorine-based additive, a rheology control agent, a defoaming agent, an antistatic agent, and an antifogging agent. May be contained.

  The curable resin composition of the present invention is suitably used as a two-component laminating adhesive for adhering various plastic films, particularly as an adhesive for bonding plastic films when manufacturing back sheets for solar cells. Can be used.

  The plastic film used for bonding here is, for example, polycarbonate, polyethylene terephthalate, polymethyl methacrylate, polystyrene, polyester, polyolefin, epoxy resin, melamine resin, triacetyl cellulose resin, polyvinyl alcohol, ABS resin, norbornene resin, cyclic Examples include films made of olefin-based resins, polyimide resins, polyvinyl fluoride resins, polyvinylidene fluoride resins, and the like. The two-pack type laminating adhesive of the present invention exhibits high adhesion to films made of polyvinyl fluoride resin or polyvinylidene fluoride resin, which are particularly difficult to bond among the various films.

When bonding the various films, the amount of the two-component laminating adhesive of the present invention is preferably in the range of ^{2 to} 50 g / m ² .

  A laminated film obtained by adhering a plurality of films using the two-component laminating adhesive of the present invention has a feature that it has high adhesiveness even under wet heat conditions, and the films are difficult to peel off. Therefore, the two-pack type laminating adhesive of the present invention can be suitably used for laminated film applications used in harsh environments such as outdoors, and as described above, the adhesive particularly used for producing a solar cell backsheet. Can be preferably used.

  A method for producing a solar battery backsheet using the two-component laminating adhesive of the present invention includes, for example, applying the two-component laminating adhesive of the present invention to a plastic film and then applying this curable resin composition. A method in which another plastic substrate is overlaid on the physical layer and then cured under a temperature condition of 25 to 80 ° C. to obtain a sheet molded body can be mentioned.

  Here, as an apparatus for applying the two-component laminating adhesive of the present invention to a plastic film, a comma coater, roll knife coater, die coater, roll coater, bar coater, gravure roll coater, reverse roll coater, blade coater , Gravure coater, micro gravure coater and the like. The amount of the two-component laminating adhesive applied to the plastic substrate is preferably about 1 to 50 μm in terms of dry film thickness.

There may be a plurality of the above-described plastic film and adhesive layer. Further, a structure may be employed in which a gas barrier layer such as a metal vapor deposition film is provided on the surface of the plastic film, the two-component laminating adhesive is applied thereon, and another plastic film is laminated. Furthermore, in order to improve adhesiveness with the sealing material which seals a solar cell element, the easily bonding layer may be provided in the sealing material side surface of this solar cell backsheet. This easy-adhesion layer can form irregularities on the surface of the easy-adhesion layer, and is composed of fine metal particles such as TiO ₂ , SiO ₂ , CaCO ₃ , SnO ₂ , ZrO ₂ and MgCO ₃ and a binder in order to improve adhesion. It is preferable that it is a thing.

  Further, the thickness of the adhesive layer in the solar cell backsheet of the present invention is preferably in the range of 1 to 50 μm, particularly preferably in the range of 5 to 15 μm.

In addition, a solar cell module using such a back sheet for a solar cell includes an ethylene vinyl acetate resin (EVA) sheet, a plurality of solar cells, an ethylene vinyl acetate resin (EVA) sheet on the cover glass plate, It can be manufactured by disposing a back sheet, heating while evacuating, and melting the EVA sheet to seal the solar cell element. At this time, the plurality of solar cell elements are joined in series by the interconnector.
Here, as the solar cell element, for example, a single-crystal silicon-based solar cell element, a polycrystalline silicon-based solar cell element, an amorphous silicon-based solar cell element composed of a single junction type or a tandem structure type, gallium arsenide ( III-V compound semiconductor solar cell elements such as GaAs) and indium phosphide (InP), II-VI compound semiconductor solar cell elements such as cadmium tellurium (CdTe), copper / indium / selenium (CIS), copper / Indium / gallium / selenium-based (CIGS-based), copper / indium / gallium / selenium / sulfur-based (CIGSS-based) I-III-VI group compound semiconductor solar cell elements, dye-sensitized solar cell elements, organic solar cells An element etc. are mentioned.

  Hereinafter, the present invention will be described in more detail with reference to specific synthesis examples and examples, but the present invention is not limited to these examples.

  In Examples of the present application, the number average molecular weight (Mn) and the weight average molecular weight (Mw) were measured by gel permeation chromatography (GPC) under the following conditions.

Measuring device: HLC-8220GPC manufactured by Tosoh Corporation
Column: TSK-GUARDCOLUMN SuperHZ-L manufactured by Tosoh Corporation
+ Tosoh Corporation TSK-GEL SuperHZM-M x 4
Detector: RI (differential refractometer)
Data processing: Multi-station GPC-8020 model II manufactured by Tosoh Corporation
Measurement conditions: Column temperature 40 ° C
Solvent tetrahydrofuran
Flow rate: 0.35 ml / min Standard: Monodispersed polystyrene Sample: Filtered 0.2% by mass tetrahydrofuran solution in terms of resin solids with a microfilter (100 μl)

Example 1 [Synthesis of Polyester Polyurethane Polyol (A1)]
A flask having a stirring bar, a temperature sensor, and a rectifying tube was charged with 413.7 parts of neopentyl glycol, 90.2 parts of 1,6-hexanediol, 464.1 parts of adipic acid, and 0.6 part of an organic titanium compound, Dry nitrogen was flowed into the flask and heated to 230 to 250 ° C. with stirring to conduct esterification. The reaction was stopped when the acid value became 2.0 mgKOH / g or less, cooled to 100 ° C., and diluted to 80% solid content with ethyl acetate. Next, 343.1 parts of isophorone diisocyanate was charged, and dry nitrogen was flowed into the flask and heated to 70 to 80 ° C. with stirring to conduct a urethanization reaction. When the isocyanate content became 0.3% or less, the reaction was stopped to obtain a polyester polyurethane polyol having a number average molecular weight of 10,000, a weight average molecular weight of 26000, and a hydroxyl value of 6. A resin solution having a solid content of 60% obtained by diluting this with ethyl acetate is designated as polyester polyurethane polyol (A1).

Example 2 [Synthesis of Polyester Polyurethane Polyol (A2)]
In a flask having a stir bar, temperature sensor, and rectifying tube, 345.2 parts of neopentyl glycol, 70.0 parts of 1,6-hexanediol, 5.0 parts of trimethylolpropane, 388.4 parts of adipic acid and organic titanium 0.5 parts of the compound was charged, dry nitrogen was flowed into the flask, and heated to 230 to 250 ° C. with stirring to conduct an esterification reaction. The reaction was stopped when the acid value became 2.0 mgKOH / g or less, cooled to 100 ° C., and diluted to 80% solid content with ethyl acetate. Next, 286.0 parts of isophorone diisocyanate was charged, and dry nitrogen was flowed into the flask and heated to 70 to 80 ° C. with stirring to conduct a urethanization reaction. When the isocyanate content became 0.3% or less, the reaction was stopped to obtain a polyester polyurethane polyol having a number average molecular weight of 13,000, a weight average molecular weight of 42,000, and a hydroxyl value of 7. A resin solution having a solid content of 50% obtained by diluting this with ethyl acetate is designated as polyester polyurethane polyol (A2).

Example 3 [Synthesis of Polyester Polyurethane Polyol (A3)]
A flask having a stirring bar, a temperature sensor, and a rectifying tube is charged with 401.4 parts of neopentyl glycol, 107.8 parts of dipropylene glycol, 449.6 parts of adipic acid, and 0.6 part of an organic titanium compound, and dried nitrogen is added. The mixture was flowed into the flask and heated to 230 to 250 ° C. with stirring to conduct an esterification reaction. The reaction was stopped when the acid value became 2.0 mgKOH / g or less, cooled to 100 ° C., and diluted to 80% solid content with ethyl acetate. Next, 349.8 parts of isophorone diisocyanate was charged, and dry nitrogen was allowed to flow into the flask and heated to 70 to 80 ° C. with stirring to conduct a urethanization reaction. The reaction was stopped when the isocyanate content became 0.3% or less, and a polyester polyurethane polyol having a number average molecular weight of 10,000, a weight average molecular weight of 30,000 and a hydroxyl value of 13 was obtained. A resin solution having a solid content of 60% obtained by diluting this with ethyl acetate is designated as polyester polyurethane polyol (A3).

Example 4 [Synthesis of Polyester Polyurethane Polyol (A4)]
A flask having a stirring bar, a temperature sensor, and a rectifying tube was charged with 349.8 parts of neopentyl glycol, 90.1 parts of 1,6-hexanediol, 392.9 parts of adipic acid and 0.5 parts of an organic titanium compound. Dry nitrogen was flowed into the flask and heated to 230 to 250 ° C. with stirring to conduct esterification. The reaction was stopped when the acid value became 2.0 mgKOH / g or less, cooled to 100 ° C., and diluted to 80% solid content with ethyl acetate. Then. Next, 22.0 parts of an isocyanurate modified form of hexamethylene diisocyanurate (Sumijour N-3300; manufactured by Sumika Bayer Urethane Co., Ltd.) and 240.6 parts of hexamethylene diisocyanate were charged, and dry nitrogen was allowed to flow into the flask. While stirring, the mixture was heated to 70 to 80 ° C. to carry out urethanization reaction. The reaction was stopped when the isocyanate content became 0.3% or less, and a polyester polyurethane polyol having a number average molecular weight of 14,000, a weight average molecular weight of 119000 and a hydroxyl value of 9 was obtained. A resin solution having a solid content of 50% obtained by diluting this with ethyl acetate is designated as polyester polyurethane polyol (A4).

Comparative Example 1 [Synthesis of Polyester Polyol (a1)]
A flask having a stirring bar, a temperature sensor, and a rectifying tube was charged with 514.3 parts of neopentyl glycol, 291.7 parts of 1,6-hexanediol, 1053.0 parts of adipic acid and 0.8 part of an organic titanium compound, Dry nitrogen was flowed into the flask and heated to 230 to 250 ° C. with stirring to conduct esterification. The reaction was stopped when the acid value became 2.0 mgKOH / g or less, cooled to 100 ° C., and diluted to 60% solid content with ethyl acetate. By this synthesis method, a polyester polyol having a number average molecular weight of 9000, a weight average molecular weight of 22,000, and a hydroxyl value of 14 was obtained. This resin solution is designated as polyester polyol (a1).

Comparative Example 2 [Synthesis of Polyester Polyol (a2)]
In a flask having a stir bar, temperature sensor, and rectifying tube, 396.6 parts neopentyl glycol, 224.9 parts 1,6-hexanediol, 411.9 parts adipic acid, 569.6 parts sebacic acid, and an organic titanium compound 0.7 parts were charged, dry nitrogen was flowed into the flask, and heated to 230 to 250 ° C. with stirring to conduct an esterification reaction. The reaction was stopped when the acid value became 2.0 mgKOH / g or less, cooled to 100 ° C., and diluted to 70% solid content with ethyl acetate. By this synthesis method, a polyester polyol having a number average molecular weight of 10,000, a weight average molecular weight of 22,000, and a hydroxyl value of 8 was obtained. This resin solution is designated as polyester polyol (a2).

Comparative Example 3 [Synthesis of Polyester Polyol (a3)]
In a flask having a stir bar, temperature sensor, and rectifying tube, 492.6 parts neopentyl glycol, 279.4 parts 1,6-hexanediol, 30.6 parts trimethylolpropane, 1057.4 parts adipic acid and organic titanium 0.8 parts of the compound was charged, and dry nitrogen was allowed to flow into the flask and heated to 230 to 250 ° C. while stirring to conduct an esterification reaction. The reaction was stopped when the acid value became 2.0 mgKOH / g or less, cooled to 100 ° C., and diluted to 60% solid content with ethyl acetate. By this synthesis method, a polyester polyol having a number average molecular weight of 13,000, a weight average molecular weight of 34,000, and a hydroxyl value of 11 was obtained. This resin solution is designated as polyester polyol (a3).

Comparative Example 4 [Synthesis of Polyester Polyol (a4)]
In a flask having a stir bar, a temperature sensor, and a rectifying tube, 902.0 parts of neopentyl glycol, 179.0 parts of ethylene glycol, 414.5 parts of adipic acid, 1259.0 parts of phthalic anhydride, and an organic titanium compound 1.0 The portion was charged and dried nitrogen was allowed to flow into the flask and heated to 230 to 250 ° C. with stirring to carry out the esterification reaction. The reaction was stopped when the acid value became 2.0 mgKOH / g or less, cooled to 100 ° C., and diluted to 60% solid content with ethyl acetate. By this synthesis method, a polyester polyol having a number average molecular weight of 10,000, a weight average molecular weight of 21,000, and a hydroxyl value of 9 was obtained. This resin solution is designated as polyester polyol (a4).

Comparative Example 5 [Synthesis of Polyester Polyol (a5)]
In a flask having a stir bar, temperature sensor, and rectifying tube, 371.0 parts of neopentyl glycol, 556.5 parts of ethylene glycol, 927.5 parts of sebacic acid, 1298.6 parts of isophthalic acid, and 1.0 part of an organic titanium compound Then, dry nitrogen was allowed to flow into the flask and heated to 230 to 250 ° C. while stirring to conduct an esterification reaction. The reaction was stopped when the acid value became 1.0 mgKOH / g or less, cooled to 100 ° C., and diluted to 60% solid content with ethyl acetate. By this synthesis method, a polyester polyol having a number average molecular weight of 23,000, a weight average molecular weight of 75,000, and a hydroxyl value of 13 was obtained. This resin solution is designated as polyester polyol (a5).

Comparative Example 6 [Synthesis of Polyester Polyurethane Polyol (a6)]
In a flask having a stir bar, temperature sensor, and rectifying tube, 382.1 parts neopentyl glycol, 573.1 parts ethylene glycol, 859.7 parts sebacic acid, 1337.3 parts isophthalic acid, and 1.0 part organic titanium compound Then, dry nitrogen was allowed to flow into the flask and heated to 230 to 250 ° C. while stirring to conduct an esterification reaction. The reaction was stopped when the acid value became 1.0 mgKOH / g or less, cooled to 100 ° C., and diluted to 80% solid content with ethyl acetate. Next, 129.0 parts of isophorone diisocyanate was charged, and dry nitrogen was allowed to flow into the flask and heated to 70 to 80 ° C. with stirring to conduct a urethanization reaction. When the isocyanate content became 0.3% or less, the reaction was stopped to obtain a polyester polyurethane polyol having a number average molecular weight of 12,000, a weight average molecular weight of 37,000 and a hydroxyl value of 14. A resin solution having a solid content of 60% obtained by diluting this with ethyl acetate is designated as polyester polyurethane polyol (a6).

Examples 5 to 13 and Comparative Examples 7 to 11
According to the composition of Table 1 or Table 2, the adhesive main agent is prepared, and then, according to the formulations shown in Table 1 and Table 2, the obtained adhesive main agent and the curing agent are mixed together to obtain a curable resin composition. It was adjusted. In addition, the main ingredient compounding quantity in a table | surface is a solid content mass part. The compounding quantity of a hardening | curing agent is solid content mass with respect to 100 mass parts of main ingredient solid content.

(Preparation of evaluation sample)
Evaluation sample (A) (UV evaluation sample)
Using a 30 μm thick aluminum foil (“A1N30H-O” manufactured by Toyo Aluminum Co., Ltd.) as a base material, the curable resin composition obtained in each Example and Comparative Example was applied to 5 to 6 g / m 2 (dry mass). As a bonding film, a 25 μm-thick fluorine film (“Aflex 25PW” manufactured by Asahi Glass Co., Ltd.) was bonded to obtain a laminated film. After aging this at 50 ° C. for 72 hours, an evaluation sample (A) was obtained.

Evaluation sample (B) (Moisture and heat resistance evaluation sample)
Using a 125 μm thick PET film (Toray Co., Ltd. “X10S”) as a base material, the curable resin compositions obtained in each Example and Comparative Example were applied to 5 to 6 g / m 2 (dry mass), A laminating film was obtained by laminating a 25 μm-thick fluorine film (“Aflex 25PW” manufactured by Asahi Glass Co., Ltd.) as a laminating film. After aging this at 50 ° C. for 72 hours, an evaluation sample (B) was obtained.

(Evaluation method of evaluation sample (A))
The evaluation sample (A) was subjected to a T-type peel test using a tensile tester (“AGS500NG” manufactured by SHIMADZU) under the conditions of a peel rate of 300 mm / min and N / 15 mm, and the strength was evaluated as adhesive strength. . The initial adhesive strength of the evaluation sample (A) and the adhesive strength of each sample after exposure for 25 hours, 50 hours, and 75 hours in an environment of 121 ° C. and 100% humidity were measured.

(Evaluation method of evaluation sample (B))
Using the tensile tester (“AGS500NG” manufactured by SHIMADZU), the evaluation sample (B) was subjected to a T-type peel test under conditions of a peel rate of 300 mm / min and N / 15 mm, and the initial adhesive strength was evaluated. . With respect to the initial adhesive strength, the adhesive strength retention after irradiation with 100 mW / cm ² ultraviolet rays from the fluorine film side for 100 hours and the yellowing of the coating film were evaluated.

The epoxy resin (B) used in Examples and Comparative Examples of the present invention is shown below.
Epoxy resin (B1): Hydrogenated bisphenol A epoxy resin (“YX8034” manufactured by Mitsubishi Chemical Corporation, molecular weight of about 470)
Epoxy resin (B2): bisphenol A type epoxy resin (“Epiclon 860” manufactured by DIC Corporation) having a number average molecular weight (Mn) of 470, an epoxy equivalent of 245 g / eq, and a hydroxyl value of 54 mgKOH / g
Polycarbonate resin (C) :: polycarbonate diol having a number average molecular weight (Mn) of 1,000 and a hydroxyl value of 110 mgKOH / g (“Placcel CD210” manufactured by Daicel Chemical Industries)
Curing agent (D1): Nurate modified product of hexamethylene diisocyanate (“Sumijour N3300” manufactured by Sumitomo Bayer Urethane Co., Ltd.)

  The hydroxyl value of the epoxy resin (B) is determined by measuring the abundance ratio of epoxy resins having different degrees of polymerization present in the epoxy resin (B) by GPC. It is a value calculated from the value with the theoretical hydroxyl value.

Claims (11)

A resin structure obtained by reacting an aliphatic polyester polyol (i) having a branched alkane structure part and an unbranched alkane structure part in the molecule as a hydrocarbon structure part of a polyester with an aliphatic polyfunctional isocyanate compound (ii) A polyol component for a two-component laminate adhesive containing the polyester polyurethane polyol (A). The polyol agent for a two-component laminate adhesive according to claim 1, wherein the polyester polyurethane polyol (A) has a number average molecular weight (Mn) in the range of 5,000 to 20,000. The polyester polyurethane polyol (A) has a branched alkane structure site (ia) and an unbranched alkane structure site (ib) in a molar ratio [(ia) / (ib)] of 1. The two-component type according to claim 2, which has a resin structure obtained by reacting the aliphatic polyester polyol (i) having a ratio of / 3 to 3/1 with an aliphatic polyfunctional isocyanate compound (ii). Polyol agent for laminating adhesive. The polyester polyurethane polyol (A) is a resin structure obtained by reacting the aliphatic polyester polyol (i) having a number average molecular weight (Mn) in the range of 500 to 5,000 with an aliphatic polyfunctional isocyanate compound (ii). The polyol agent for a two-component laminate adhesive according to claim 3, wherein The polyester polyol (i) is obtained by reacting a branched alkane polyol (i-1), an unbranched alkanediol (i-2), and an aliphatic dicarboxylic acid or its anhydride (i-3). The polyol agent for two-component laminate adhesives according to claim 4. The polyol agent for a two-component laminate adhesive according to claim 5, wherein the polyester polyurethane polyol (A) has a hydroxyl value in the range of 2 to 30. The resin composition which uses the novel polyester polyurethane polyol (A) as described in any one of Claims 1-6, and a polyfunctional epoxy compound (B) as an essential component. The resin composition according to claim 7, comprising the novel polyester polyurethane polyol (A) according to any one of claims 1 to 6, a polyfunctional epoxy compound (B), and a hydroxyl group-containing aliphatic polycarbonate (C) as essential components. object. A curable resin composition comprising the polyol agent for a two-component laminate adhesive according to claim 6 or the resin composition according to claim 7 or 8 as a main agent and an aliphatic polyisocyanate (D) as a curing agent. object. A two-component laminating adhesive comprising the curable resin composition according to claim 9. Adhesion comprising one or more kinds of films selected from the group consisting of a polyester film, a fluororesin film, a polyolefin film, and a metal foil, and an adhesive for two-component laminating according to claim 10 for bonding these films together. A solar cell backsheet formed from the layers.