JP2015003950A - Novel polyester polyurethane polyol, polyol agent for two-liquid type laminate adhesive, resin composition, curable resin composition, adhesive for two-liquid type laminate and back sheet for solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a back sheet adhesive for solar cells which is notably improved in substrate adhesion under humid and hot conditions and causes less discoloration due to UV rays and less deterioration of the substrate adhesion during long-term service.SOLUTION: A two-liquid type laminate adhesive contains, as a main agent, a novel polyester polyurethane polyol having a resin structure which is formed by reacting together (i) an aliphatic polyester polyol obtained by reacting a branched alkylene polyol with an aliphatic dicarboxylic acid or an alkyl ester of the dicarboxylic acid, (ii) an aliphatic multifunctional isocyanate compound and (iii) a 2-13C aliphatic diol.

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 Products, a novel polyester polyurethane polyol constituting the main component, a polyol component for a two-component laminate adhesive, 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, it is still not at a sufficient level, and further, when used outdoors for a long period of time, discoloration due to ultraviolet rays and adhesive strength. The decrease was inevitable.

Japanese Patent No. 4416047

  Therefore, the problem to be solved by the present invention is a two-component type in which the substrate adhesiveness under wet heat conditions is drastically improved and the color change due to ultraviolet rays and the deterioration of the substrate adhesiveness are small when used for a long time. Laminating adhesive, curable resin composition constituting the adhesive, main component of the adhesive, novel polyester polyurethane polyol constituting the adhesive, and solar cell exhibiting excellent performance in moisture and heat resistance and discoloration resistance It is to provide a back sheet for use.

  As a result of intensive studies to solve the above problems, the inventors of the present invention obtained an aliphatic polyester polyol obtained by reacting a branched alkylene polyol with an aliphatic dicarboxylic acid component, an aliphatic polyvalent isocyanate and a carbon atom number of 2 to 2. When the polyester polyol having a resin structure obtained by reacting with an aliphatic diol of No. 13 is extremely excellent in moisture resistance and used as a main ingredient of an adhesive for an exterior film of a solar cell backsheet, The present inventors have found that the base adhesiveness under the conditions is remarkably excellent and that yellowing and adhesion deterioration due to ultraviolet rays can be effectively prevented during long-term outdoor use, and the present invention has been completed.

  That is, the present invention provides an aliphatic polyester polyol (i) obtained by reacting a branched alkylene polyol with an aliphatic dicarboxylic acid or an alkyl ester thereof, an aliphatic polyfunctional isocyanate compound (ii), The present invention relates to a novel polyester polyurethane polyol characterized by having a resin structure obtained by reacting 13 aliphatic diols (iii).

  The present invention further relates to a polyol agent for a two-component laminate adhesive comprising the novel polyester polyurethane polyol.

  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 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 the two-component laminating adhesive for bonding these films together. It is related with the solar cell backsheet shape | molded from the adhesive layer which becomes.

  According to the present invention, the adhesive property for a base material under wet heat conditions is drastically improved, and when used for a long period of time, the adhesive for two-component laminating is less susceptible to discoloration due to ultraviolet rays or deterioration of the adhesive property of the base material. A curable resin composition constituting an adhesive, a main component of the adhesive, a novel polyester polyurethane polyol constituting the adhesive, and a solar cell backsheet exhibiting excellent performance in moisture and heat resistance and discoloration resistance can be provided. .

1 is a GPC chart of the polyester polyurethane polyol (A1) obtained in Example 1. FIG. 2 is an infrared absorption spectrum diagram of the polyester polyurethane polyol (A1) obtained in Example 1. FIG.

  The novel polyester polyurethane polyol of the present invention is useful as a polyol agent for a two-component laminate adhesive, which is a main component of a solar cell backsheet adhesive, and a branched alkylene polyol as a raw material diol component constituting a polyester structure part. Since it uses, the hydrolysis resistance of this polyester structure site | part improves dramatically. In addition, since the aliphaticity is high, discoloration and adhesion deterioration due to ultraviolet rays are unlikely to occur, and in addition, the adhesive force is improved due to the cohesive force of urethane bonds.

  Here, the aliphatic polyester polyol (i), which is the main raw material component of the novel polyester polyurethane polyol, has a structure obtained by reacting a branched alkylene polyol and an aliphatic dicarboxylic acid or an alkyl ester thereof as described above. It is what you have. Such a branched alkylene polyol is specifically a polyol having an alkylene structure in which a tertiary carbon atom or a quaternary carbon atom is present in the molecular structure. For example, 1,2-propylene glycol, 1,3-butylene Glycol, 2-methyl-1,3-propanediol, neopentyl glycol, 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, 2,4-diethyl-1,5-pentanediol, 1,2-hexane glycol, 1,2-octyl glycol, etc. Alkanediol; a trifunctional or higher functional branched polyfunctional alcohol such as trimethylolpropane and pentaerythritol It is below. Among these, a branched alkylene diol having 4 to 13 carbon atoms is preferable, and neopentyl glycol is particularly preferable from the viewpoint that an adhesive having excellent coatability to a substrate and good heat and heat resistance can be obtained. In the present invention, the branched alkanediol is partially used in combination with a polyfunctional alcohol having a tri- or higher functional branched alkane structure, so that these branched alkylene polyols can improve the adhesion to a substrate and The molecular weight distribution of the novel polyester polyurethane polyol can be controlled. In this case, the use ratio between the branched alkanediol and the above-described trifunctional or higher functional branched polyalcohol is 99.5 mass ratio [branched alkanediol / trifunctional or higher branched alkane structure-containing polyfunctional alcohol]. A ratio of 0.5 / 95/5 is preferable.

  On the other hand, the aliphatic dicarboxylic acid or alkyl ester thereof to be reacted with this is, as the linear aliphatic dicarboxylic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, Undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, heptadecanedioic acid, octadecanedioic acid, nonadecanedioic acid, icosanedioic acid, or those having 1 to 4 carbon atoms Examples include alkyl esters.

  In the present invention, among these, particularly when used as an adhesive, the adhesion to the base material and the heat-and-moisture resistance are good, and therefore the number of carbon atoms such as adipic acid, azelaic acid, sebacic acid and the like is 6-10. The dicarboxylic acid is preferably used.

  Further, in the present invention, for the purpose of improving the flexibility and wettability as an adhesive, and within the range not impairing the effects of the present invention, ethylene glycol, 1,3-propylene is further added to each of the above raw material components. Linear alkanediols such as glycol, 1,4-butanediol, 1,6-hexanediol, 1,8-nonanediol, and diethylene glycol may be used in combination.

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

  Next, the conditions for reacting the branched alkylene polyol with the aliphatic dicarboxylic acid or the alkyl ester thereof are, for example, 160 to 270 in the presence of the esterification catalyst in the branched alkylene polyol and the aliphatic dicarboxylic acid or the alkyl ester thereof. The method of making it react in the temperature range of ° C is mentioned.

  The aliphatic polyester polyol (i) obtained in this manner has a hydroxyl value in the range of 100 to 130 mgKOH / g, but can reduce the amount of carbonyloxy groups in the finally obtained new polyester polyurethane polyol. When the polyester polyurethane polyol (A) finally obtained is improved as the main agent for the adhesive, the moisture resistance is improved, and the moisture and heat resistance is improved by preventing water from entering the adhesive layer.

  The novel polyester polyurethane polyol comprises the aliphatic polyester polyol (i) thus obtained, an aliphatic polyfunctional isocyanate compound (ii), and an aliphatic diol (iii) having 2 to 13 carbon atoms. It can be produced by reacting.

  Here, 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).

  The nurate type polyisocyanate compound having an isocyanurate ring structure in the molecule is, for example, a temperature of 40 to 100 ° C. of the aliphatic diisocyanate compound (ii-1) in the presence of an isocyanuration catalyst. It can be obtained by reacting in a range.

  Here, when using the polyisocyanate compound (ii-2) having three or more functional groups, the degree of branching of the above-described polyester polyurethane polyol (A) is improved and used as an adhesive for the above-described solar battery back sheet. The heat and humidity resistance in the case can be further improved.

  Among the aliphatic polyfunctional isocyanate compounds (ii) described in detail above, isophorone is particularly advantageous in that it provides an adhesive that is particularly excellent in coating properties on substrates and heat and moisture resistance, and also has an effect of preventing adhesion deterioration against ultraviolet rays. Diisocyanate is preferred.

  On the other hand, the aliphatic diol (iii) having 2 to 13 carbon atoms specifically includes ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,8- Examples thereof include linear alkanediols such as nonanediol and diethylene glycol, and the branched alkane polyol (i-1) described above. Among these, particularly when used as an adhesive, a linear alkanediol having 4 to 9 carbon atoms is preferable from the viewpoint of obtaining an adhesive excellent in adhesion to a substrate, and 1,6-hexanediol is particularly preferable. preferable.

  The reaction between the aliphatic polyester polyol (i), the aliphatic polyfunctional isocyanate compound (ii), and the aliphatic diol (iii) having 2 to 13 carbon atoms is, for example, an aliphatic polyester polyol (i ) And an aliphatic polyfunctional isocyanate compound (ii), and then a method of reacting an aliphatic diol (iii) having 2 to 13 carbon atoms (Method 1) and an aliphatic polyester polyol (i) ), An aliphatic polyfunctional isocyanate compound (ii), and an aliphatic diol (iii) having 2 to 13 carbon atoms (method 2).

  Specifically, in the method 1, first, an aliphatic polyester polyol (i) and an aliphatic polyfunctional isocyanate compound (ii) have an equivalent ratio [isocyanate group in (ii) / hydroxyl group in (i)]. Reaction is performed at a temperature of 60 to 100 ° C. at a ratio of 3/1 to 1.1 / 1, and the reaction end point is obtained when the viscosity of the reaction solution becomes constant, thereby obtaining an aliphatic polyester polyisocyanate. Furthermore, the equivalent ratio [isocyanate group in the aliphatic polyester polyisocyanate / hydroxyl group in (iii)] of the aliphatic polyester polyisocyanate and the aliphatic diol (iii) having 4 to 13 carbon atoms is 1.2. The method of making it react on the temperature conditions of 60-100 degreeC in the ratio used as /1-1.001/1.

  On the other hand, the method 2 specifically includes an aliphatic polyester polyol (i), an aliphatic polyfunctional isocyanate compound (ii), and an aliphatic diol (iii) having 4 to 13 carbon atoms in a mass ratio. [(I) / (iii)] is a ratio of 1/1 to 20/1, and an aliphatic polyfunctional isocyanate compound (to the total of the hydroxyl groups in (i) and (iii) ( The ratio of the equivalent ratio of isocyanate groups in ii) [(hydroxyl group in (i) + hydroxyl group in (iii)) / isocyanate group in (ii)] is from 1.2 / 1 to 1.001 / 1. The method of making it react on 60-100 degreeC temperature conditions is mentioned.

  In the urethanization reaction in Method 1 or Method 2, a urethanization catalyst may be used.

  Among the above-described methods 1 and 2, in particular, in the present invention, the method 2 is a fat resulting from the aliphatic diol (iii) having 2 to 13 carbon atoms in the finally obtained new polyester urethane polyol. Since the group and the polyester structure site resulting from the aliphatic polyester polyol (i) are present at random, it is preferable from the viewpoint that the moisture resistance of the novel polyester urethane polyol can be improved.

  The novel polyester polyurethane polyol 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 100,000 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 novel polyester polyurethane polyol 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.

  Further, the number average molecular weight (Mn) of the novel polyester polyurethane polyol is 5,000 to 50,000 in that it is excellent in substrate adhesion under wet heat conditions and becomes a resin composition having a viscosity suitable for coating. It is preferable that it is the range of 6,000, and it is especially preferable that it is the range of 6,000-30,000.

  In the present invention, the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the novel polyester polyurethane polyol 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 novel polyester polyurethane polyol 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 adhesion to the substrate under wet heat conditions. Is more preferable.

  The novel polyester polyurethane polyol of the present invention described in detail above is useful as a polyol agent which is a main component of a two-component laminate adhesive, and can be used together with a curing agent. It is preferable to use a resin composition containing “polyester polyurethane polyol (A)”) and a polyfunctional epoxy compound (B) as the main component of the two-component laminate adhesive. That is, by using the polyfunctional epoxy compound (B) in addition to the polyester polyurethane polyol (A), the carboxy group generated by hydrolysis of the polyester polyurethane polyol (A) when the adhesive layer absorbs moisture is added to the polyester polyurethane polyol (A). The epoxy group in the polyfunctional epoxy compound (B) is captured, and the heat-and-moisture 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. Here, the method for measuring the number average molecular weight (Mn) is a value measured under the same conditions as the GPC measurement conditions in the above-described novel polyester polyurethane polyol.

  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 method of polycondensation reaction between 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 the present invention, since the blending ratio of the aliphatic polyisocyanate (D) becomes a curable resin composition having more excellent curability, the polyester polyurethane polyol (A), the epoxy compound (B), and the hydroxyl group-containing The ratio [OH] / [NCO] between the total number of moles [OH] of hydroxyl groups contained in the polycarbonate resin (C) and the number of moles [NCO] of isocyanate groups contained in the aliphatic polyisocyanate (D) is 1 The range is preferably from 1/1 to 1/2, and more preferably from 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 fat The mixing ratio of the group polyisocyanate (D) is a ratio of the total number of moles [OH] of hydroxyl groups in the curable resin composition to the number of moles [NCO] of isocyanate groups contained in the polyisocyanate compound (D) [ OH] / [NCO] is preferably in the range of 1/1 to 1/2, and more preferably in the range of 1 / 1.05 to 1 / 1.5.

  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 useful as a two-component laminating adhesive for bonding various plastic films.

  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)

  The infrared absorption spectrum was measured by coating a solution of polyester polyurethane polyol (A1) on a KBr plate to prepare a sample in which the solvent was volatilized.

Example 1 [Synthesis of Polyester Polyurethane Polyol (A1)]
In a flask having a stir bar, temperature sensor, and rectifying tube, 471.6 parts by mass of neopentyl glycol, 510.5 parts by mass of adipic acid and titanium (di-i-propoxide) bis (acetylacetonate) (Matsumoto Fine Chemical Co., Ltd.) 0.6 parts by mass of “Orgachix TC-100” manufactured by the company was charged, and 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, and after cooling to 100 ° C., the mixture was diluted with ethyl acetate to a solid content of 80% by mass to obtain an ethyl acetate solution of polyester diol. The obtained polyester diol had a hydroxyl value of 117 mgKOH / g.

  Next, 90.2 parts by mass of 1,6-hexanediol and 343.1 parts by mass of isophorone diisocyanate were charged into the ethyl acetate solution of the polyester diol (solid content of polyester polyol 765.0 parts by mass), and dry nitrogen was introduced into the flask. The mixture was heated to 70 to 80 ° C. with stirring and subjected to 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 11,000, a weight average molecular weight of 29000, a molecular weight distribution (Mw / Mn) of 2.6, and a hydroxyl value of 8 was obtained. It was. A resin solution having a solid content of 60% by mass 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 stirring bar, a temperature sensor, and a rectifying tube, 428.7 parts by mass of neopentyl glycol, 5.0 parts by mass of trimethylolpropane, 464.1 parts by mass of adipic acid, and titanium (di-i-propoxide) Charge 0.6 parts by mass of bis (acetylacetonate) (Matsumoto Fine Chemical Co., Ltd. “Orgatechs TC-100”), flow dry nitrogen into the flask and heat to 230-250 ° C. with stirring to conduct the esterification reaction. went. The reaction was stopped when the acid value became 2.0 mgKOH / g or less, and after cooling to 100 ° C., the mixture was diluted with ethyl acetate to a solid content of 80% by mass to obtain an ethyl acetate solution of polyester diol. The obtained polyester diol had a hydroxyl value of 120 mgKOH / g.

  Next, 83.7 parts by mass of 1,6-hexanediol and 343.1 parts by mass of isophorone diisocyanate were charged into this ethyl acetate solution of polyester diol (polyester polyol solid content 760.3 parts by mass), and dry nitrogen was introduced into the flask. The mixture was heated to 70 to 80 ° C. with stirring and subjected to urethanization reaction. The reaction was stopped when the isocyanate content became 0.3% by mass or less, and a polyester polyurethane polyol having a number average molecular weight of 9000, a weight average molecular weight of 42000, a molecular weight distribution (Mw / Mn) of 4.7, and a hydroxyl value of 10 was obtained. Obtained. A resin solution having a solid content of 60% obtained by diluting this with ethyl acetate is designated as polyester polyurethane polyol (A2).

Comparative Example 1 [Synthesis of Polyester Polyol (a1)]
In a flask having a stirring bar, a temperature sensor, and a rectifying tube, 371.0 parts of neopentyl glycol, 556.5 parts by weight of ethylene glycol, 927.5 parts by weight of sebacic acid, 1298.6 parts by weight of isophthalic acid, and titanium (di- i-propoxide) bis (acetylacetonate) ("Orgachix TC-100" manufactured by Matsumoto Fine Chemical Co., Ltd.) 1.0 part by mass, heated to 230-250 ° C while stirring and flowing dry nitrogen into the flask Then, esterification reaction was performed. 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, a molecular weight distribution (Mw / Mn) of 3.3, and a hydroxyl value of 13 mgKOH / g was obtained. This resin solution is designated as polyester polyol (a1).

Comparative Example 2 [Synthesis of Polyester Polyurethane Polyol (a2)]
In a flask having a stir bar, temperature sensor, and rectifying tube, 382.1 parts neopentyl glycol, 573.1 parts by weight ethylene glycol, 859.7 parts by weight sebacic acid, 1337.3 parts by weight isophthalic acid, and titanium (di- i-propoxide) bis (acetylacetonate) ("Orgachix TC-100" manufactured by Matsumoto Fine Chemical Co., Ltd.) 1.0 part by mass, heated to 230-250 ° C while stirring and flowing dry nitrogen into the flask Then, esterification reaction was performed. 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. The reaction was stopped when the isocyanate content was 0.3% or less, and the polyester polyurethane polyol had a number average molecular weight of 12,000, a weight average molecular weight of 37,000, a molecular weight distribution (Mw / Mn) of 3.1, and a hydroxyl value of 14 mgKOH / g. Got. A resin solution having a solid content of 60% obtained by diluting this with ethyl acetate is designated as polyester polyurethane polyol (a2).

Comparative Example 3 [Synthesis of Polyester Polyol (a3)]
In a flask having a stirring bar, a temperature sensor, and a rectifying tube, 514.3 parts by mass of neopentyl glycol, 291.7 parts by mass of 1,6-hexanediol, 1053.0 parts by mass of adipic acid and titanium (di-i-propoxy E) 0.8 parts by weight of bis (acetylacetonate) (Matsumoto Fine Chemical Co., Ltd. “Orgatics TC-100”) was charged, and dry nitrogen was flowed into the flask and heated to 230 to 250 ° C. with stirring to perform esterification. Reaction was performed. 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 22000, a molecular weight distribution (Mw / Mn) of 2.4, and a hydroxyl value of 14 mgKOH / g was obtained. This resin solution is designated as polyester polyol (a3).

Comparative Example 4 [Synthesis of Polyester Polyol (a4)]
In a flask having a stirring bar, a temperature sensor, and a rectifying tube, 560.0 parts by mass of neopentyl glycol, 400.0 parts by mass of ethylene glycol, 100.0 parts by mass of 1,6-hexanediol, 136.0 parts by mass of isophthalic acid , 580.0 parts by mass of sebacic acid, 1290.0 parts by mass of phthalic anhydride, and titanium (di-i-propoxide) bis (acetylacetonate) ("Orgatics TC-100" manufactured by Matsumoto Fine Chemical Co., Ltd.) 1.0 A mass part 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 60% solid content with ethyl acetate. By this synthesis method, a polyester polyol having a number average molecular weight of 14,000, a weight average molecular weight of 38000, a molecular weight distribution (Mw / Mn) of 2.7, and a hydroxyl value of 12 mgKOH / g was obtained. This resin solution is designated as polyester polyol (a4).

Examples 3-9 and Comparative Examples 5-7
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) (discoloration resistance 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): Discoloration resistance)
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.

(Evaluation method of evaluation sample (B): heat and humidity resistance)
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.

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 (D): Nurate-modified product of hexamethylene diisocyanate (“Sumijour N3300” manufactured by Sumitomo Bayer Urethane Co., Ltd.)

  The hydroxyl value of the epoxy resin (B2) is determined by measuring the abundance ratio of epoxy resins having different degrees of polymerization present in the epoxy resin (B2) by GPC. This is a value calculated from the value of the theoretical hydroxyl value.

Claims (11)

An aliphatic polyester polyol (i) obtained by reacting a branched alkylene polyol with an aliphatic dicarboxylic acid or an alkyl ester thereof, an aliphatic polyfunctional isocyanate compound (ii), an aliphatic diol having 2 to 13 carbon atoms ( A novel polyester polyurethane polyol having a resin structure obtained by reacting with iii). The novel polyester polyurethane polyol according to claim 1, wherein the aliphatic polyester polyol (i) is obtained by reacting a branched alkylene diol having 4 to 13 carbon atoms with an aliphatic dicarboxylic acid or an alkyl ester thereof. The novel polyester polyurethane polyol according to claim 2, wherein the aliphatic polyester polyol (i) is in the range of 1,000 to 6,000 in weight average molecular weight (Mw). The novel polyester polyurethane polyol according to claim 3, wherein the hydroxyl value is in the range of 2 to 30 mgKOH / g. The novel polyester polyurethane polyol according to claim 4, wherein the weight average molecular weight (Mw) is in the range of 10,000 to 200,000. A polyol agent for a two-component laminate adhesive comprising the novel polyester polyurethane polyol according to any one of claims 1 to 5. A resin composition comprising the novel polyester polyurethane polyol (A) according to any one of claims 1 to 5 and a polyfunctional epoxy compound (B) as essential components. The resin composition according to claim 7, comprising the novel polyester polyurethane polyol (A) according to any one of claims 1 to 5, a polyfunctional epoxy compound (B), and a hydroxyl group-containing aliphatic polycarbonate (C) as essential components. object. Curability obtained by using the polyol component 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 blending an aliphatic polyisocyanate (D) as a curing agent. Resin composition. 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.

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