阅读说明：本技术 用于层合片的粘合剂 (Adhesive for laminated sheet ) 是由 山田泰史 伊藤祥子 釜井教义 池田仁志 于 2013-08-22 设计创作，主要内容包括：本发明公开了一种用于层合片的粘合剂,其包含：氨基甲酸酯树脂,所述氨基甲酸酯树脂可通过将丙烯酸酯多元醇与异氰酸酯化合物混合来获得；和硅烷化合物；其中所述硅烷化合物包含基于缩水甘油基的硅烷化合物,其中所述丙烯酸酯多元醇可通过将可聚合单体聚合来获得,所述可聚合单体包含具有羟基的单体和其它单体,所述其它单体包含丙烯腈,并且所述异氰酸酯化合物包含选自苯二甲基二异氰酸酯和六亚甲基二异氰酸酯中的至少一种。所述用于层合片的粘合剂具有适中的固化速率,并且具有优异的对膜的初始粘合性和优异的在高温下的长期耐水解性；并且还具有优异的耐气候性。(Disclosed is an adhesive for laminated sheets, comprising: a urethane resin obtainable by mixing an acrylate polyol with an isocyanate compound; and a silane compound; wherein the silane compound comprises a glycidyl-based silane compound, wherein the acrylate polyol is obtainable by polymerizing a polymerizable monomer comprising a monomer having a hydroxyl group and another monomer comprising acrylonitrile, and the isocyanate compound comprises at least one selected from the group consisting of xylylene diisocyanate and hexamethylene diisocyanate. The adhesive for laminated sheets has a moderate curing rate, and has excellent initial adhesion to a film and excellent long-term hydrolysis resistance at high temperatures; and also has excellent weatherability.)

1. Raw material comprising acrylate polyol for preparing adhesive for laminated sheet, wherein

The acrylate polyol can be obtained by polymerizing a polymerizable monomer,

the polymerizable monomer comprises a monomer having a hydroxyl group and other monomers, and

the other monomer comprises acrylonitrile.

Technical Field

The present invention relates to an adhesive for laminated sheets.

Background

Outdoor materials such as wall protection materials, roofing materials, solar cell panel materials, window materials, outdoor flooring materials, illumination protection materials, automobile parts, and signboards include a laminate (or a laminate sheet) obtained by laminating multilayer films to each other using an adhesive as a constituent material. Examples of the film constituting the laminate include metal foils made of metals (e.g., aluminum, copper, and steel); a metal plate and a deposited metal film; and films made of plastics such as polypropylene, polyvinyl chloride, polyester, fluororesin and acrylic resin.

As shown in fig. 1, the laminated sheet 10 is a laminate of a plurality of films 11 and 12, and the films 11 and 12 are laminated with an adhesive 13 interposed therebetween.

Since the laminate is exposed outdoors for a long period of time, an adhesive for a laminate sheet is required to have excellent durability. Adhesives for laminate sheets, particularly for solar cell applications that convert sunlight to electrical energy, preferably have a higher level of durability than conventional laminate adhesives.

As shown in fig. 3, in the case of a solar cell application, the laminate sheet 10 is referred to as a back sheet (back sheet), and is arranged within the solar cell module 1 together with the sealing material 20, the solar cell unit 30, and the glass plate 40.

Since the solar cell module 1 is exposed to the outside for a long period of time, it is required to have sufficient durability against sunlight under conditions of high temperature and high humidity. In particular, when the adhesive 13 has poor properties, the film 11 may be peeled off from the film 12, whereby the appearance of the laminate sheet 10 may be impaired. Therefore, it is required that the adhesive used in the laminate sheet for manufacturing a solar cell module does not undergo peeling of the film even when exposed to high temperatures for a long period of time.

Patent documents 1 to 3 disclose urethane-based adhesives for manufacturing solar cell protective sheets as examples of adhesives for laminated sheets.

Patent document 1 discloses that a urethane adhesive synthesized from an acrylate polyol is suitable as an adhesive for a solar cell back sheet (see claim 1 and paragraph [0048] of patent document 1).

Patent document 2 discloses a protective sheet for a solar cell module in which an acrylic urethane resin is formed on a base sheet (see claim 1 and fig. 1 to 3 of patent document 2).

Patent document 3 discloses that an isocyanate curing agent is mixed with an acrylic polyol to prepare an adhesive (see tables 1 and 2 of patent document 3); then, a solar cell back sheet can be manufactured by using these adhesives (see paragraph [0107] of patent document 3).

Patent documents 1 to 3 disclose that inferior appearance of a solar cell module can be prevented by manufacturing a solar cell back sheet using an adhesive having excellent hydrolysis resistance and excellent lamination strength. However, the demand for durability of the adhesive for solar cell back sheets has increased year by year, and it is hard to say that the adhesives of these documents satisfy these high demands of consumers.

Solar cell back sheets are generally manufactured by: an adhesive with moderate viscosity is applied to the film, the adhesive is dried, the film is laminated (dry lamination process), and the laminate is aged for several days. Therefore, an adhesive for such sheets is also required to have excellent initial adhesion to a film in lamination.

Since the solar cell module is used outdoors under high temperature and high humidity conditions, a plurality of films constituting the back sheet (laminate sheet) may be peeled off. In particular, it is difficult to bond the fluororesin-based film to other various substrates using an adhesive. When exposed to the outside for a long period of time, the adhesive strength between the adhesive and the fluororesin-based film may be drastically reduced. Recently, progress has been made to improve organic solar cells at low manufacturing costs compared to solar cells using silicon or inorganic compound materials. Since the organic solar cell may have colorability or flexibility, a transparent film is often used as a film constituting a back sheet of the solar cell. Therefore, an adhesive for solar cell back sheets is required not only to maintain peel strength over a long period of time but also to undergo very limited color difference change and to have excellent weatherability.

Therefore, there is a need for adhesives for solar cell back sheets that have higher levels of hydrolysis resistance, initial adhesion, and weatherability. When an adhesive is used to bond a fluororesin-based film, it is urgently required to suppress deterioration of the adhesiveness of the adhesive.

Patent document 1: JP 2011-105819A

Patent document 2: JP 2010-238815A

Patent document 3: JP 2010-263193A

Disclosure of Invention

Problems to be solved by the invention

The present invention has been made to solve such problems, and an object of the present invention is to provide an adhesive for a laminate sheet, which has a moderate curing rate, has excellent initial adhesion to a film when a laminate (laminate sheet) is produced using a plastic film (particularly a fluororesin-based film), and also has excellent weather resistance and excellent long-term hydrolysis resistance at high temperatures.

Means for solving the problems

The inventors of the present invention have conducted intensive studies and surprisingly found that, when a specific polyol and a specific isocyanate compound are used as raw materials of a urethane resin and a specific silane compound is added as a coupling agent, an adhesive for a laminate sheet having a moderate curing rate and excellent initial adhesion to a film, long-term hydrolysis resistance at high temperature and weather resistance can be obtained, thereby completing the present invention.

That is, in one aspect, the present invention provides an adhesive for a laminate sheet, comprising: a urethane resin obtainable by mixing an acrylate polyol with an isocyanate compound; and a silane compound; wherein

The silane compound includes a glycidyl-based silane compound, the acrylate polyol is obtainable by polymerizing a polymerizable monomer including a monomer having a hydroxyl group and another monomer including acrylonitrile, and the isocyanate compound includes at least one selected from xylylene diisocyanate (hexamethylene diisocyanate).

The present invention provides, as an embodiment, an adhesive for laminated sheets, wherein the equivalent ratio (NCO/OH) of an isocyanate group derived from xylylene diisocyanate and/or hexamethylene diisocyanate to a hydroxyl group derived from an acrylate polyol is 1.0 to 3.0.

The present invention provides, as a preferred embodiment, an adhesive for laminated sheets, wherein xylylene diisocyanate is a monomer and hexamethylene diisocyanate is in the form of isocyanurate.

In another aspect, the present invention provides a raw material comprising an acrylate polyol for use in preparing any one of the above-described adhesives for laminated sheets, wherein the acrylate polyol is obtainable by polymerizing polymerizable monomers comprising a monomer having a hydroxyl group and other monomers, and the other monomers comprise acrylonitrile.

Effects of the invention

The adhesive for laminated sheets of the present invention comprises: a urethane resin obtainable by mixing an acrylate polyol with at least one isocyanate compound selected from xylylene diisocyanate and hexamethylene diisocyanate; and a silane compound including a glycidyl-based silane compound, wherein the acrylate polyol is obtainable by polymerizing a monomer having a hydroxyl group with at least one other monomer, wherein the at least one other monomer includes acrylonitrile. Thus, the adhesive has a moderate curing rate, has excellent initial adhesion to a film and excellent long-term hydrolysis resistance at high temperature, and also has excellent weatherability.

In the adhesive for laminate sheets of the present invention, more preferably, the equivalent ratio (NCO/OH) of the isocyanate groups derived from the isocyanate compound (which may contain or consist of, for example, xylylene diisocyanate and/or hexamethylene diisocyanate) to the hydroxyl groups derived from the acrylate polyol is 1.0 to 3.0, because a moderate curing rate is maintained and initial adhesion to a film, hydrolysis resistance and weather resistance are improved.

In the adhesive of the present invention, it is particularly preferable that xylylene diisocyanate is a monomer and hexamethylene diisocyanate is in the form of isocyanurate, since a moderate curing rate is maintained, initial adhesion to a film, hydrolysis resistance and weather resistance are remarkably improved, and overall properties are excellent.

In the raw material containing an acrylate polyol, which is used for preparing the adhesive for laminated sheets of the present invention, (a) the acrylate polyol is obtainable by polymerizing a polymerizable monomer; the polymerizable monomer comprises a monomer having a hydroxyl group and at least one other monomer; the at least one other monomer comprises acrylonitrile. Therefore, a urethane resin having a moderate curing rate, having excellent initial adhesion and hydrolysis resistance, and also having excellent weatherability is prepared by reacting the raw materials with an isocyanate compound, and thus, an adhesive suitable for outdoor material applications, particularly for a laminate sheet, which can be used as an adhesive for a back sheet of a solar cell, can be provided.

Drawings

Figure 1 is a cross-sectional view of one embodiment of a laminate sheet.

Fig. 2 is a cross-sectional view of another embodiment laminate sheet.

Fig. 3 is a cross-sectional view of an embodiment of an outdoor material (e.g., a solar cell module).

Detailed Description

The adhesive for laminated sheets of the present invention comprises a urethane resin obtainable by mixing an acrylate polyol with an isocyanate compound, and a silane compound.

The urethane resin is a polymer obtainable by mixing an acrylate polyol with an isocyanate compound and reacting them, and has a urethane bond. The hydroxyl groups of the acrylate polyol react with the isocyanate groups.

The acrylate polyol can be obtained by addition polymerization of polymerizable monomers including "a monomer having a hydroxyl group" and "other monomers".

The "monomer having a hydroxyl group" is a radically polymerizable monomer having a hydroxyl group and an ethylenic double bond, and is not particularly limited as long as the objective adhesive of the present invention can be obtained. The monomer having a hydroxyl group includes, for example, hydroxyalkyl (meth) acrylate, and hydroxyalkyl (meth) acrylate may be used alone, or two or more hydroxyalkyl (meth) acrylates may be used in combination. The hydroxyalkyl (meth) acrylate may also be used in combination with a monomer having a hydroxyl group other than the hydroxyalkyl (meth) acrylate.

Examples of "hydroxyalkyl (meth) acrylate" include, but are not limited to, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl acrylate, and the like.

Examples of "polymerizable monomer having a hydroxyl group other than hydroxyalkyl (meth) acrylate" include polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, and the like.

The "other monomer" is a "radical polymerizable monomer having an ethylenic double bond" other than the monomer having a hydroxyl group and contains acrylonitrile, and is not particularly limited as long as the objective adhesive for a laminate sheet of the present invention can be obtained. The other monomer may further include a (meth) acrylate. The other monomers may further include radical polymerizable monomers having an ethylenic double bond other than acrylonitrile and (meth) acrylate.

"(meth) acrylate" can be obtained, for example, by a condensation reaction of (meth) acrylic acid with a monohydric alcohol, and has an ester bond. The monomer having a hydroxyl group is not included in the (meth) acrylate ester in spite of having an ester bond. Specific examples thereof include alkyl (meth) acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, dicyclopentyl (meth) acrylate, and isobornyl (meth) acrylate; glycidyl (meth) acrylate, and the like. Both linear and cyclic alkyl groups are included within the "alkyl group".

In the present invention, at least one monomer selected from the group consisting of methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate and cyclohexyl (meth) acrylate is preferably included; more preferably, at least one monomer selected from the group consisting of methyl (meth) acrylate, ethyl (meth) acrylate and butyl (meth) acrylate is included.

Examples of the "radical polymerizable monomer having an ethylenic double bond other than acrylonitrile and (meth) acrylate" include, but are not limited to, (meth) acrylic acid, styrene, vinyl toluene, and the like.

"Acrylonitrile" is of the formula CH₂＝CH-CN, and also known as acrylonitrile (acrylic nitrile), acrylic nitrile, or vinyl cyanide.

The content of acrylonitrile is preferably 1 to 40 parts by weight, more preferably 5 to 35 parts by weight, particularly preferably 5 to 25 parts by weight, based on 100 parts by weight of the polymerizable monomer. When the content of acrylonitrile is within the above range, an adhesive for solar cell back sheets providing an excellent balance among coatability, initial adhesion to a film, and adhesion at high temperature (hydrolysis resistance) can be obtained.

In the present specification, acrylic acid and methacrylic acid are collectively referred to as "(meth) acrylic acid", and "acrylate and methacrylate" are collectively referred to as "(meth) acrylate" or "(meth) acrylate".

The method of polymerizing the polymerizable monomer is not particularly limited as long as the objective adhesive of the present invention can be obtained. For example, the above-mentioned polymerizable monomers can be radical polymerized in an organic solvent by a conventional solution polymerization method using an appropriate catalyst. Here, the "organic solvent" may be used to polymerize the polymerizable monomer, and the organic solvent is not particularly limited as long as it does not substantially adversely affect the characteristics of the adhesive after polymerization. Examples of such solvents include: aromatic solvents such as toluene and xylene; ester-based solvents such as ethyl acetate and butyl acetate; and combinations thereof.

The polymerization reaction conditions in the polymerization of the polymerizable monomer, such as the reaction temperature, the reaction time, the type of organic solvent, the type and concentration of the monomer, the stirring rate, and the type and concentration of the polymerization initiator, may be appropriately selected according to the objective characteristics of the adhesive.

The "polymerization initiator" is preferably a compound which can accelerate the polymerization of the polymerizable monomer by its addition in a small amount and can be used in an organic solvent. Examples of the polymerization initiator include ammonium persulfate, tert-butyl peroxybenzoate, 2-Azobisisobutyronitrile (AIBN), and 2, 2-azobis (2, 4-dimethylvaleronitrile).

The polymerization in the present invention may suitably use a chain transfer agent to adjust the molecular weight. As "chain transfer agents" it is possible to use compounds which are well known to the person skilled in the art. Examples thereof include mercaptans such as n-dodecyl mercaptan (nDM), lauryl methyl mercaptan and mercaptoethanol.

As mentioned above, the acrylate polyol can be obtained by polymerizing a polymerizable monomer. Weight average molecular weight (M) of acrylic ester polyol from the viewpoint of coatability of adhesive_W) Preferably 200,000 or less, more preferably 5,000-100,000. Weight average molecular weight (M)_W) Is a value measured by Gel Permeation Chromatography (GPC) and converted to a polystyrene standard. Specifically, the value can be measured by using the following GPC apparatus and measurement method. As a GPC apparatus, HCL-8220GPC manufactured by TOSOH corporation was used, and RI was used as a detector. Two TSKgelSuperMultipore HZ-M manufactured by TOSOH corporation were used as GPC columns. The sample was dissolved in tetrahydrofuran, and the obtained solution was allowed to flow at a column temperature of 40 ℃ at a flow rate of 0.35 ml/min, and the measured Mw was obtained. The objective Mw is determined by converting the measured molecular weight based on a calibration curve obtained by using polystyrene having a monodisperse molecular weight as a standard reference material.

Glass transition temperature (T) of acrylate polyol_g) Can be set by adjusting the kind and mass fraction of the monomer to be used. Glass transition temperature (T) of acrylate polyol_g) Can be determined based on the glass transition temperature of the homopolymer obtainable from each monomer and the mass fraction of the homopolymer used in the acrylate polyol, using the following calculation formula (i). The composition of the monomers is preferably determined using the glass transition temperature determined by calculation:

(i)：1/T_g＝W1/T_g1+W2/T_g2+···+Wn/T_gn

wherein T in the above formula (i)_gDenotes the glass transition temperature of the acrylate polyol, each of W1, W2,. cndot., Wn denotes the mass fraction of the respective monomer, and T_g1,T_g2,. and T_gEach of n represents a glass of a homopolymer of the respective monomerGlass transition temperature.

The values disclosed in the references can be used as T for homopolymers_g. For example, it may be useful to refer to the following references: catalog of acrylates from Mitsubishi Rayon corporation (1997 edition), edited by Kyozo Kitaoka; "ShinKobunshi Bunko 7, Guide to Synthetic Resin for Coating Material", Kobunshi Kankokai, published 1997, page 168-169; and "POLYMER HANDBOOK", 3 rd edition, page 209 and 277, John Wiley&Sons corporation, published in 1989.

In the present specification, the glass transition temperatures of the homopolymers of the following monomers are as follows.

Methyl methacrylate: 105 ℃ C

N-butyl acrylate: -54 deg.C

Ethyl acrylate: -20 ℃ C

2-hydroxyethyl methacrylate: 55 deg.C

2-hydroxyethyl acrylate: -15 deg.C

Glycidyl methacrylate: 41 deg.C

Acrylonitrile: 130 deg.C

Styrene: 105 ℃ C

In the present invention, the glass transition temperature of the acrylic polyol is preferably from-20 ℃ to 20 ℃, more preferably from-15 ℃ to 20 ℃, particularly preferably from-10 ℃ to 15 ℃ from the viewpoint of initial adhesion to a film. When the glass transition temperature of the acrylate polyol is within the above range, the cohesive force of the adhesive of the present invention is less likely to be reduced, and the adhesive of the present invention has more excellent initial adhesion and can also better maintain hydrolysis resistance.

The hydroxyl value of the acrylic ester polyol is preferably from 0.5 to 45mgKOH/g, more preferably from 1 to 40mgKOH/g, and particularly preferably from 3 to 30 mgKOH/g. When the hydroxyl value of the acrylate polyol is within the above range, an adhesive having excellent initial adhesion, adhesion at high temperature and hydrolysis resistance can be obtained. In particular, when a solar cell back sheet is manufactured by laminating a plurality of films using the adhesive of the present invention, the films become less likely to peel off from the adhesive.

In the present specification, the hydroxyl value is the number of milligrams of potassium hydroxide required to neutralize acetic acid, which is acetic acid reacted with hydroxyl groups upon acetylation of 1g of the resin.

In the present invention, the hydroxyl value is specifically calculated by the following formula (ii).

(ii) The method comprises the following steps Hydroxyl value ═ [ (weight of (meth) acrylate having hydroxyl group)/(molecular weight of (meth) acrylate having hydroxyl group) ] × (number of moles of hydroxyl group contained in 1mol of (meth) acrylate monomer having hydroxyl group) × [ (formula weight of KOH) × 1,000)/(weight of acrylate polyol) ]

The isocyanate compound of the present invention is not particularly limited as long as the objective adhesive of the present invention can be obtained, and the isocyanate compound contains at least one selected from xylylene diisocyanate and hexamethylene diisocyanate. The isocyanate compound may comprise other isocyanate compounds. The isocyanate compound is preferably at least one selected from the group consisting of trimethylolpropane adduct, isocyanurate form, biuret form, allophanate form and isocyanate monomer.

When the isocyanate compound contains these compounds, the adhesive for laminate sheets can be more preferably used at high temperature and high humidity for a long period of time because hydrolysis resistance is significantly improved.

The isocyanate compounds are mainly classified into "isocyanates having no aromatic ring" and "isocyanates having aromatic ring".

Examples of the isocyanate having no aromatic ring include "aliphatic isocyanate" and "alicyclic isocyanate".

The aliphatic isocyanate refers to a compound having a chain-like hydrocarbon chain and having no cyclic hydrocarbon chain, wherein an isocyanate group is directly bonded to the hydrocarbon chain.

The alicyclic isocyanate is a compound having a cyclic hydrocarbon chain and may have a chain hydrocarbon chain. The isocyanate group may be directly bonded to a cyclic hydrocarbon chain, or may be directly bonded to a chain-like hydrocarbon chain that may be present.

Examples of aliphatic isocyanates include 1, 4-diisocyanatobutane, 1, 5-diisocyanatopentane, Hexamethylene Diisocyanate (HDI), 1, 6-diisocyanato-2, 2, 4-trimethylhexane, methyl 2, 6-diisocyanatohexanoate (lysine diisocyanate), and the like.

Examples of alicyclic isocyanates include 5-isocyanato-1-isocyanatomethyl-1, 3, 3-trimethylcyclohexane (isophorone diisocyanate), 1, 3-bis (isocyanatomethyl) cyclohexane (hydrogenated xylylene diisocyanate), bis (4-isocyanatocyclohexyl) methane (hydrogenated diphenylmethane diisocyanate), 1, 4-diisocyanatocyclohexane, and the like.

It is sufficient for the isocyanate having an aromatic ring (hereinafter referred to as aromatic isocyanate) to have an aromatic ring, and it is not necessary that the isocyanate group is directly bonded to the aromatic ring. The aromatic ring may be an aromatic ring in which two or more benzene rings are fused.

Examples of the aromatic isocyanate include 4, 4' -diphenylmethane diisocyanate (MDI), p-phenylene diisocyanate, m-phenylene diisocyanate, Toluene Diisocyanate (TDI), Xylylene Diisocyanate (XDI), and the like. These isocyanate compounds may be used alone or in combination.

Due to xylylene diisocyanate (OCN-CH)₂-C₆H₄-CH₂-NCO) has an aromatic ring, and thus, although an isocyanate group is not directly bonded to an aromatic ring, it corresponds to an aromatic isocyanate.

In the present invention, the isocyanate compound contains at least one selected from Hexamethylene Diisocyanate (HDI) as an aliphatic isocyanate and Xylylene Diisocyanate (XDI) as an aromatic isocyanate from the viewpoint of improving initial adhesion to a film after aging, curing time and hydrolysis resistance. More preferably, both XDI and HDI are contained.

HDI is more preferably in the form of isocyanurate, and XDI is more preferably a monomer.

In the present invention, the isocyanate compound may further comprise at least one selected from isophorone diisocyanate, which is an alicyclic isocyanate, and 4, 4' -diphenylmethane diisocyanate (MDI) and Toluene Diisocyanate (TDI), which are aromatic isocyanates, from the viewpoint of improving initial adhesion to a film, curing time, and hydrolysis resistance after aging.

The urethane resin of the present invention can be obtained by reacting an acrylate polyol with an isocyanate compound. In the reaction, a known method may be used, and the reaction may be generally performed by mixing an acrylate polyol with an isocyanate compound. The mixing method is not particularly limited as long as the urethane resin of the present invention can be obtained.

In the present invention, the equivalent ratio (NCO/OH) of the isocyanate groups derived from xylylene diisocyanate and/or hexamethylene diisocyanate to the hydroxyl groups derived from the acrylate polyol is preferably 1.0 to 3.0, more preferably 1.0 to 2.5, particularly preferably 1.5 to 2.5. At an equivalent ratio (NCO/OH) of 1.0 to 3.0, a moderate curing rate is preferably maintained, and initial adhesion to a film, hydrolysis resistance and weather resistance are improved.

The adhesive for laminated sheets of the present invention contains a silane compound. The silane compound includes a glycidyl-based silane compound, which is an epoxy-based silane compound.

The glycidyl group-based silane compound is a silane compound having a glycidyloxy group represented by the following formula (1):

chemical formula (1):

"glycidyl-based silane compound" means a compound having a glycidyloxy group, and specific examples thereof include 3-glycidoxypropylmethyldiisopropyloxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyldiethoxysilane and the like.

These glycidyl group-based silane compounds may be used alone or in combination.

In the adhesive for laminated sheets of the present invention, the glycidyl group-based silane compound is particularly preferably 3-glycidoxypropyltrialkoxysilane. Examples of the 3-glycidoxypropyltrialkoxysilane compound include 3-glycidoxypropyltrimethoxysilane and 3-glycidoxypropyltriethoxysilane.

As the 3-glycidoxypropyltrialkoxysilane compound, 3-glycidoxypropyltriethoxysilane is most suitable as an embodiment of the present invention.

Glycidyl group-based silane compounds are preferable as the silane coupling agent. The silane coupling agent refers to a compound composed of an organic substance and silicon, and also having an organic functional group "Y" such as an amino group, an epoxy group, a methacrylate group, a vinyl group or a mercapto group in one molecule at the same time; and a hydrolyzable group "OR" such as methoxy, ethoxy, OR methylcarbonyloxy, which is intended to react OR interact with organic species, and which can combine organic and inorganic materials that are generally unlikely to combine with each other.

Thus, the compound is a glycidyl-based silane compound and as a silane coupling agent, the compound means a silane coupling agent containing a functional group having a glycidyloxy group as an organic functional group "Y". When the adhesive for a laminate sheet of the present invention contains a glycidyloxy group-based silane compound, initial adhesion and hydrolysis resistance are improved, and initial adhesion between polyvinylidene fluoride (PVDF) and polyethylene terephthalate (PET) is excellent.

The method of mixing the glycidyl-based silane compound is not limited as long as the target adhesive can be obtained. For example, the glycidyl group-based silane compound may be previously mixed with the acrylate polyol, or may be post-added to the urethane resin obtainable by mixing the acrylate polyol with the isocyanate compound. The glycidyloxy group-based silane compound may be contained in the adhesive for a laminate sheet in a state of being combined with a urethane resin after being reacted with an isocyanate compound, or the silane compound may be contained in the adhesive for a laminate sheet in an unreacted state.

The glycidyl group-based silane compound may be used in combination with other silane compounds.

As the "other silane compound", for example, epoxy cyclohexyl based silane compounds, (meth) acryloyloxyalkyltrialkoxysilane compounds, (meth) acryloyloxyalkylalkylalkoxysilane compounds, vinyltrialkoxysilane compounds, vinylalkylalkoxysilane compounds, mercaptosilane compounds and isocyanurate silane compounds can be used. However, the other silane compounds are not limited to these silane compounds.

The "epoxycyclohexyl-based silane compound" is an epoxy-based silane compound, and is a compound having a 3, 4-epoxycyclohexyl group represented by the following formula (2):

chemical formula (2):

specific examples of the "epoxycyclohexyl-based silane compound" include 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, 2- (3, 4-epoxycyclohexyl) ethyltriethoxysilane, and the like.

Examples of "(meth) acryloyloxyalkyltrialkoxysilane compounds" include 3- (meth) acryloyloxypropyltrimethoxysilane, 3- (meth) acryloyloxypropyltriethoxysilane, 2- (meth) acryloyloxyethyltrimethoxysilane and the like.

Examples of "(meth) acryloyloxyalkylalkoxysilane compound" include 3- (meth) acryloyloxypropylmethyldimethoxysilane, 3- (meth) acryloyloxypropylmethyldiethoxysilane, 3- (meth) acryloyloxypropylethyldiethoxysilane, 2- (meth) acryloyloxyethylmethyldimethoxysilane, and the like.

Examples of "vinyltrialkoxysilane compounds" include vinyltrimethoxysilane, vinyltriethoxysilane, vinyldimethoxyethoxysilane, vinyltris (methoxyethoxy) silane, vinyltris (ethoxymethoxy) silane, and the like.

Examples of "vinylalkylalkoxysilane compounds" include vinylmethyldimethoxysilane, vinylethylbis (methoxyethoxy) silane, vinyldimethylmethoxysilane, vinyldiethyl (methoxyethoxy) silane, and the like.

Examples of the "mercaptosilane compound" include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, and the like.

Examples of the "isocyanurate silane compound" include tris (3- (trimethoxysilyl) propyl) isocyanurate and the like.

The adhesive for a laminate sheet of the present invention may contain an ultraviolet absorber for improving long-term weatherability. As the ultraviolet absorber, a hydroxyphenyl triazine-based compound and other commercially available ultraviolet absorbers can be used. The "hydroxyphenyl triazine-based compound" is a triazine derivative in which a hydroxyphenyl derivative is combined with a carbon atom of the triazine derivative, and examples thereof include TINUVIN 400, TINUVIN 405, TINUVIN 479, TINUVIN 477 and TINUVIN 460 (all of which are trade names) commercially available from BASF corporation.

The adhesive for laminated sheets may further contain a hindered phenol-based compound, which is not particularly limited as long as the objective adhesive of the present invention can be obtained.

As the hindered phenol-based compound, commercially available products such as those available from BASF corporation can be used. Examples include IRGANOX1010, IRGANOX1035, IRGANOX1076, IRGANOX1135, IRGANOX1330, and IRGANOX1520 (all of which are trade names). Hindered phenol-based compounds are added to adhesives as antioxidants and may be used, for example, in combination with phosphite-based antioxidants, thioether-based antioxidants, amine-based antioxidants, and the like.

The adhesive of the present invention may further comprise a hindered amine-based compound, which is not particularly limited as long as the objective adhesive of the present invention can be obtained.

As the hindered amine-based compound, a commercially available product can be used. Examples of hindered amine-based compounds include TINUVIN 765, TINUVIN 111FDL, TINUVIN 123, TINUVIN 144, TINUVIN152, TINUVIN 292, and TINUVIN 5100 (all of which are trade names) available from BASF corporation. The hindered amine-based compound is added to the adhesive as a light stabilizer, and may be used, for example, in combination with a benzotriazole-based compound, a benzoate-based compound, and the like.

The adhesive for laminated sheets of the present invention may further contain one or more other components as long as the objective adhesive can be obtained.

The addition time of the "other components" to the adhesive is not particularly limited as long as the objective adhesive can be obtained. For example, the other components may be added together with the acrylate polyol and the isocyanate compound in the synthesis of the urethane resin, or may be added after the urethane resin is synthesized by reacting the acrylate polyol with the isocyanate compound.

Examples of "other components" include tackifier resins, pigments, plasticizers, flame retardants, waxes, and the like.

Examples of the "tackifier resin" include styrene-based resins, terpene-based resins, aliphatic petroleum resins, aromatic petroleum resins, rosin esters, acrylic resins, polyester resins (excluding polyester polyols), and the like.

Examples of "pigments" include titanium oxide, carbon black, and the like.

Examples of "plasticizers" include dioctyl phthalate, dibutyl phthalate, diisononyl adipate, dioctyl adipate, mineral spirits, and the like.

Examples of the "flame retardant" include halogen-based flame retardants, phosphorus-based flame retardants, antimony-based flame retardants, metal hydroxide-based flame retardants, and the like.

The "wax" is preferably a wax, such as paraffin wax and microcrystalline wax.

The viscosity of the adhesive for laminate sheets of the present invention was measured by using a rotational viscometer (model BM, manufactured by TOKIMEC corporation). When the solution viscosity of 40% solid content is 4,000mPa · s or more, the coatability of the adhesive may deteriorate. If a solvent is further added to reduce the viscosity, coating is performed at a low solid component concentration, and thus, the productivity of the adhesive may be reduced.

The adhesive for laminated sheets of the present invention may be prepared by mixing the above-described urethane resin and silane compound, as well as a plasticizer, a light stabilizer and/or other components that may be optionally added. There is no particular limitation on the mixing method or the mixing order of the components; the adhesive can be prepared without the need for a special mixing process and a special mixing sequence. The obtained adhesive can maintain excellent hydrolysis resistance at high temperature for a long period of time and also has excellent initial adhesion to a film.

Therefore, a laminated sheet is produced by laminating a plurality of adherends using the adhesive for laminated sheets of the present invention, and the obtained laminated sheet is used for producing various outdoor materials.

Examples of such outdoor materials include wall protection materials, roofing materials, solar cell modules, window materials, outdoor flooring materials, lighting protection materials, automobile parts, and signboards. These outdoor materials include a laminated sheet obtained by laminating a plurality of films to each other as an adherend. Examples of the film include a film obtained by depositing a metal on a plastic film (metal-deposited film) and a film on which no metal is deposited (plastic film).

Among the adhesives used for laminated sheets, the adhesives used for manufacturing solar cell modules are required to have particularly high curing rate and adhesion level to a film after aging, and further to have long-term hydrolysis resistance at high temperature. The adhesive for laminated sheets of the present invention has excellent long-term hydrolysis resistance at high temperatures, and is therefore suitable as an adhesive for solar cell back sheets.

In the case of manufacturing a solar cell back sheet, the adhesive of the present invention is applied to a film. Application may be performed by various methods, such as gravure coating, wire bar coating, air knife coating, die coating, lip coating (lip coating), and comma coating (comma coating) methods. The adhesive-coated films were laminated to each other to complete a solar cell back sheet.

Embodiments of the solar cell back sheet of the present invention are shown in each of fig. 1 to 3, but the present invention is not limited to these embodiments.

Fig. 1 is a sectional view of a solar cell back sheet as an embodiment of the laminate sheet of the present invention. The solar cell back sheet 10 is formed of two films and an adhesive 13 for a laminate sheet interposed therebetween, and the two films 11 and 12 are laminated to each other using the adhesive 13 for a laminate sheet. The membranes 11 and 12 may be made of the same or different materials. In fig. 1, two films 11 and 12 are laminated to each other, or three or more films may be laminated to each other.

Another embodiment of the laminate of the present invention (solar cell back sheet) is shown in fig. 2. In fig. 2, a thin film (or foil film) 11a is formed between the film 11 and the outdoor urethane adhesive 13. For example, fig. 2 shows an embodiment in which a metal thin film 11a is formed on the surface of the film 11 when the film 11 is a plastic film. The metal thin film 11a may be formed on the surface of the plastic film 11 by vapor deposition, and the solar cell back sheet of fig. 2 may be obtained by: the metal thin film 11 having the metal thin film 11a formed on the surface thereof is laminated with the film 12 by interposing an adhesive 13 for a lamination sheet between the metal thin film 11 and the film 12.

Examples of metals to be deposited on the plastic film include aluminum, steel, copper, and the like. The barrier properties may be imparted to the plastic film by subjecting the film to vapor deposition. Silicon oxide or aluminum oxide is used as the vapor deposition material. The plastic film 11 used as the substrate may be transparent, or white or black.

As the film 12, a plastic film made of polyvinyl chloride, polyester, fluororesin, or acrylic resin is used. In order to impart heat resistance, weather resistance, rigidity, insulation properties, and the like, a polyethylene terephthalate film or a polybutylene terephthalate film is preferably used. The films 11 and 12 may be transparent and/or may be colored.

The deposited thin film 11a of the film 11 and the film 12 were laminated to each other using the adhesive 13 of the present invention; the films 11 and 12 are generally laminated to each other by a dry lamination method.

Fig. 3 shows a sectional view of an example of a solar cell module as an embodiment of the outdoor material of the present invention. In fig. 3, the solar cell module 1 can be obtained by stacking the following on each other: a glass plate 40; a sealing material 20 such as Ethylene Vinyl Acetate (EVA); a plurality of solar cells 30, which are generally connected to each other to generate a desired voltage; and a back sheet 10; these components 10, 20, 30 and 40 are then secured using spacers 50.

As described above, since the back sheet 10 is a laminate of the plurality of films 11 and 12, the urethane adhesive 13 is required not to peel off the films 11 and 12 even if the back sheet 10 is exposed outdoors for a long period of time.

The solar cell 30 is generally manufactured using silicon, and sometimes organic resin containing a dye. In this case, the solar cell module 1 becomes an organic (dye-sensitized) solar cell module. Since an organic (dye-sensitized) solar cell requires coloring property, transparent films are generally used as the film 11 and the film 12 constituting the solar cell back sheet 10. Therefore, the adhesive 13 for the solar cell back sheet is required to cause only a very small color difference change and to have excellent weatherability even after long-term exposure to the outside.

The main embodiments of the present invention will be given below.

1. An adhesive for a laminate sheet comprising:

a urethane resin obtainable by mixing an acrylate polyol with an isocyanate compound; and

a silane compound; wherein

The silane compound includes a glycidyl-based silane compound, the acrylate polyol is obtainable by polymerizing a polymerizable monomer including a monomer having a hydroxyl group and another monomer including acrylonitrile, and the isocyanate compound includes at least one selected from xylylene diisocyanate and hexamethylene diisocyanate.

2. The adhesive for laminated sheets according to item 1 above, wherein the equivalent ratio (NCO/OH) of isocyanate groups from the one or more isocyanate compounds to hydroxyl groups derived from the acrylate polyol (A) is from 1.0 to 3.0.

3. The adhesive for laminated sheets according to item 1 or 2 above, wherein the xylylene diisocyanate is a monomer and the hexamethylene diisocyanate is in the form of isocyanurate.

4. A raw material comprising an acrylate polyol for producing the adhesive for laminated sheets according to any one of items 1 to 3 above, wherein

The acrylate polyol is obtainable by polymerizing a polymerizable monomer comprising a monomer having a hydroxyl group and at least one other monomer, wherein the at least one other monomer comprises acrylonitrile.