JP2019077781A - Optically clear adhesive sheet, laminate, method for producing optically clear adhesive sheet, and laminated sheet - Google Patents

Abstract

The object of the present invention is to provide an optically transparent pressure-sensitive adhesive sheet which is excellent in flexibility and can be made thick and which is easy to be re-sticked immediately after lamination and which exhibits excellent adhesion.
An optical transparent adhesive sheet composed of a thermosetting polyurethane, wherein the thermosetting polyurethane is a cured product of a thermosetting polyurethane composition containing a polyol component, a polyisocyanate component and a silane coupling agent. The optical transparent adhesive sheet, wherein the silane coupling agent is a silane coupling monomer having a first organic functional group blocked by a protective group or a silane coupling oligomer having a second organic functional group.
[Selected figure] Figure 3

Description

The present invention relates to an optically transparent pressure-sensitive adhesive sheet, a laminate, a method for producing an optically transparent pressure-sensitive adhesive sheet, and a laminated sheet.

An optically clear adhesive (OCA) sheet is a transparent adhesive sheet used for laminating optical members. In recent years, the demand for touch panels has been rapidly growing in the fields of smartphones, tablet PCs, portable game machines, car navigation devices, etc. With this, the demand for OCA sheets used to bond touch panels to other optical members Is also increasing. A display device provided with a touch panel generally includes a display panel such as a liquid crystal panel, a transparent member (touch panel main body) having a transparent conductive film made of ITO (indium tin oxide) or the like on the surface, and a cover for protecting the transparent conductive film. It has a structure where optical members, such as a panel, were laminated, and an OCA sheet is used for pasting between optical members. However, between the display panel and the touch panel main body, the end of the bezel, which is the housing of the display panel, is wider than the distance between the other optical members, and bonding with the OCA sheet is not performed. It was common to provide an air layer called.

However, if an air gap which is an air layer exists between the optical members, interface reflection occurs due to the difference in refractive index between the air layer and the optical members, and the visibility of the display panel is reduced. Therefore, a thick film OCA sheet suitable for bonding the display panel and the touch panel main body has been required. Moreover, covering the level difference formed by the thickness of a bezel is also calculated | required by the OCA sheet used for bonding of a display panel and a touch-panel main body. Therefore, an OCA sheet excellent in flexibility (step followability) and capable of being thickened is required.

Examples of documents disclosing prior art in the OCA sheet-related field include Patent Documents 1 and 2. The adhesive type optical film in which an adhesive layer is provided on an optical film is disclosed in Patent Document 1, wherein the adhesive layer comprises a polyol compound (a-1) having a weight average molecular weight of 500 to 4000, and an isocyanate compound (a-). 2), and a polyol compound (a-4) having two or more C = C bonds having radical polymerization property in one molecule, which are obtained by reaction, and the polyol (a-1) and the polyol compound (a-4) A polyurethane polymer (A) in which the compounding amount of the polyol compound (a-4) is 0.1 to 10% by weight with respect to the total amount of (A) as a base polymer, and the urethane polymer (A) 100 The adhesive type optical film characterized by containing 0.01-0.5 weight part of silane coupling agents (B) with respect to a weight part is disclosed.

Patent Document 2 describes 100 parts by weight of a pressure-sensitive adhesive resin (A) and silicone alkoxy oligomers (B) 0.1 to 20 having an epoxy equivalent of 100 to 2000 g / mol and an alkoxyl group content of 5 to 60% by weight. Acrylic pressure-sensitive adhesive resin (A1), urethane-based pressure-sensitive adhesive resin (A2), and polyester-based pressure-sensitive adhesive, which are obtained by polymerizing a monomer containing no carboxyl group, wherein the pressure-sensitive adhesive resin (A) contains parts by weight A pressure-sensitive adhesive composition is disclosed, which is one or more selected from the group consisting of an agent resin (A3). In addition, it is described that the pressure-sensitive adhesive composition may further contain 0.001 to 5 parts by weight of a silane coupling agent (D) with respect to 100 parts by weight of the pressure-sensitive adhesive resin (A). (See claim 7).

Patent No. 5016994 Specification JP, 2016-44291, A

As the OCA sheet, one formed of an ultraviolet curing adhesive is known. However, since an ultraviolet curing adhesive can not be irradiated with ultraviolet light at a portion to be a shadow of decorative printing or a portion to be a shadow of a material that absorbs ultraviolet light, it can not be cured sufficiently.

Therefore, the present inventors pay attention to using a thermosetting polyurethane composition which is film-formed without using a solvent and is cured by heating as a material of the OCA sheet which is excellent in flexibility and can be thickened. did. Furthermore, in the case of improving the adhesion of an optical transparent adhesive sheet using a thermosetting polyurethane, the addition of a silane coupling agent to the thermosetting polyurethane composition causes aging of the interface or by heating. I thought about improving adhesion. However, the effect of sufficient adhesion improvement was not obtained.

The present invention has been made in view of the above-mentioned present situation, and it is possible to use a thermosetting polyurethane which is excellent in flexibility and capable of forming a thick film, so that it is easy to reattach immediately after bonding, and excellent adhesion. It aims at providing the optical transparent adhesive sheet to express.

As a result of examining the reason why the sufficient effect of adhesive strength improvement can not be obtained even if the silane coupling agent is added to the thermosetting polyurethane composition, the present inventors hydrolyze the silane coupling agent inside the sheet, It was thought that it was because it did not precipitate at the interface with the adherend. Therefore, various investigations were made on a silane coupling agent suitable for segregating at the interface with the adherend, and it was found that a sufficient effect of improving the adhesive strength can be obtained if a specific type of silane coupling agent is added. , Completed the present invention.

The optical transparent adhesive sheet of the present invention is an optical transparent adhesive sheet composed of thermosetting polyurethane, and the thermosetting polyurethane is a thermosetting polyurethane composition containing a polyol component, a polyisocyanate component and a silane coupling agent. And the silane coupling agent includes a silane coupling monomer having a first organic functional group blocked by a protecting group or a silane coupling oligomer having a second organic functional group. It features.

The first organic functional group is preferably an amino group or a mercapto group.

The silane coupling oligomer may have a structure in which the second organic functional group is bonded to a siloxane chain. In this case, the second organic functional group is preferably an acryloyl group, a methacryloyl group, an epoxy group, a mercapto group or a vinyl group.

The second organic functional group may be an isocyanurate ring.

The polyol component preferably contains an olefin-based polyol.

The laminate of the present invention comprises the first adherend, the second adherend, and the optically transparent pressure-sensitive adhesive sheet of the present invention for bonding the first adherend and the second adherend. It is characterized by having.

The first adherend may be a glass substrate. The second adherend may be a resin base material. The resin substrate may contain a polycarbonate.

The method for producing an optical transparent pressure-sensitive adhesive sheet of the present invention is a method for producing the optical transparent pressure-sensitive adhesive sheet of the present invention, wherein the above-mentioned polyol component, the above-mentioned polyisocyanate component and the above-mentioned silane coupling agent are stirred and mixed The method comprises the steps of preparing a polyurethane composition and curing the thermosetting polyurethane composition.

The laminated sheet of the present invention comprises the optical transparent adhesive sheet of the present invention, a first release film covering one surface of the optical transparent adhesive sheet, and a second release film covering the other surface of the optical transparent adhesive sheet. It is characterized in that a mold film is laminated.

According to the optical transparent pressure-sensitive adhesive sheet of the present invention, while obtaining the superiority of a thermosetting polyurethane which is excellent in flexibility and capable of being thickened, it is easy to reattach immediately after bonding, and expresses excellent adhesive strength can do. Moreover, according to the laminated body of this invention, the outstanding adhesive force can be obtained. According to the method for producing an optical transparent pressure-sensitive adhesive sheet of the present invention, the optical transparent pressure-sensitive adhesive sheet of the present invention can be suitably produced. According to the laminated sheet of the present invention, the handleability of the optical transparent pressure-sensitive adhesive sheet of the present invention can be improved.

It is a figure explaining the effect | action mechanism of a silane coupling agent. It is a schematic diagram for demonstrating the measuring method of the adhesive force of an optical transparent adhesive sheet. It is sectional drawing which showed typically an example of the display apparatus with a touch panel using the optical transparent adhesive sheet of this invention. It is a schematic diagram for demonstrating an example of the shaping | molding apparatus used for preparation of the optical transparent adhesive sheet of this invention. (A) is the graph which showed the confocal Raman spectrum obtained about the optical transparent adhesive sheet of Example 1, (b) is the low wavelength area | region (the Raman shift is 800 cm < ^-1 > vicinity of the spectrum of (a) It is the graph which expanded and showed.

The optical transparent adhesive sheet of the present invention is an optical transparent adhesive sheet composed of thermosetting polyurethane, and the thermosetting polyurethane is a thermosetting polyurethane composition containing a polyol component, a polyisocyanate component and a silane coupling agent. And the silane coupling agent includes a silane coupling monomer having a first organic functional group blocked by a protecting group or a silane coupling oligomer having a second organic functional group. It features. In addition, in this specification, an "optical transparent adhesive sheet" is synonymous with an "optical transparent adhesive film."

The optically transparent pressure-sensitive adhesive sheet of the present invention is composed of a thermosetting polyurethane. The optical transparent adhesive sheet made of polyurethane is flexible, stretches well and is very hard to break when a tensile stress is applied. For this reason, it is possible to peel off without adhesive residue. Moreover, since the optical transparent adhesive sheet of the present invention is flexible and can be thickened, it can be made excellent in impact resistance. Furthermore, since an optical transparent adhesive sheet made of polyurethane has a high dielectric constant and higher electrostatic capacitance than an optical transparent adhesive sheet made of a conventional acrylic resin composition, it is possible to use an electrostatic capacitive touch panel. It is suitably used for bonding.

The thermosetting polyurethane is preferably not acrylic-modified, and it is preferable that the main chain does not contain a site derived from an acrylic ester, a methacrylic ester or the like. When the thermosetting polyurethane is acrylic-modified, it becomes hydrophobic, and therefore, aggregation of water tends to occur under high temperature and high humidity. The aggregation of the water may cause whitening, foaming and the like, which may impair the optical properties. Therefore, by setting the thermosetting polyurethane not to be acrylic-modified, it is possible to prevent the deterioration of the optical characteristics due to whitening, foaming and the like under high temperature and high humidity. In the thermosetting polyurethane, the total amount of the monomer units derived from the polyol component and the monomer units derived from the polyisocyanate component is 80 mol% or more of the monomer units constituting the entire polyurethane. The monomer unit is preferably composed of only a monomer unit derived from a polyol component and a monomer unit derived from a polyisocyanate component.

[Polyol component]
The polyol component is not particularly limited, and examples thereof include polyether polyol, polycaprolactone polyol, polycarbonate polyol, polyester polyol and the like. These may be used alone or in combination of two or more.

Examples of the polyether polyols include polyethylene glycol, polypropylene glycol, polypropylene triol, polypropylene tetraol, polytetramethylene glycol, polytetramethylene triol, polyalkylene glycols such as copolymers thereof, and side chains introduced into these. And derivatives having a branched structure introduced, modified products, and mixtures of these.

Examples of the polycaprolactone polyol include polycaproate glycol, polycaprolactone triol, polycaprolactone tetraol, derivatives into which side chains are introduced or branched structures introduced into them, modified products, and mixtures of these, etc. It can be mentioned.

As said polycarbonate polyol, the reaction material of dialkyl carbonate and diol is mentioned, for example.

Examples of the dialkyl carbonate include dialkyl carbonates such as dimethyl carbonate and diethyl carbonate; diaryl carbonates such as diphenyl carbonate; and alkylene carbonates such as ethylene carbonate. These may be used alone or in combination of two or more.

Examples of the diol include 1,4-butanediol, diethylene glycol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 2-methyl-1, 8-octanediol, 1,9-nonanediol, 1,10-dodecanediol, 2-ethyl-1,6-hexanediol, 3-methyl-1,5-pentanediol, 2,4-dimethyl-1,5 -Pentanediol, neopentyl glycol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 2,2'-bis (4-hydroxycyclohexyl) -propane and the like. These may be used alone or in combination of two or more. As the diol, an alicyclic or alicyclic diol having 4 to 9 carbon atoms is preferable, and, for example, 1,4-butanediol, diethylene glycol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl 1,5-pentanediol, 2,4-dimethyl-1,5-pentanediol, 1,4-cyclohexanedimethanol, 1,7-heptanediol, 1,8-octanediol, 2-methyl-1,1,5-heptanediol It is preferable to use 8-octanediol and 1,9-nonanediol singly or in combination of two or more. As the diol, a copolycarbonate diol consisting of 1,6-hexanediol and 3-methyl-1,5-pentanediol, and a copolycarbonate diol consisting of 1,6-hexanediol and 1,5-pentanediol are also available. preferable.

In addition, as the polycarbonate polyol, for example, polycarbonate glycol, polycarbonate triol, polycarbonate tetraol, derivatives in which a side chain is introduced or a branched structure is introduced thereto, modified products, and a mixture thereof can also be used. it can.

As said polyester polyol, what carried out dehydration condensation of the dicarboxylic acid and the glycol component is mentioned, for example.

Examples of dicarboxylic acids include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid and 2,6-naphthalenedicarboxylic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid and the like. Be

As the glycol component, for example, ethylene glycol, 1,4-butanediol, diethylene glycol, neopentyl glycol, 3-methyl-1,5-pentanediol, 1,5-pentanediol, 1,9-nonanediol, triethylene Aliphatic glycols such as glycols; alicyclic glycols such as 1,4-cyclohexanedimethanol; aromatic diols such as p-xylene diol; polyoxyalkylene glycols such as polyethylene glycol, polypropylene glycol and polytetramethylene glycol Be

The polyester polyol is a polyester having a linear molecular structure when formed by the dicarboxylic acid and glycol components exemplified above, but having a branched molecular structure using a trivalent or higher ester forming component. It may be. The dicarboxylic acid and the glycol component may be reacted at 150 to 300 ° C. at a molar ratio of 1.1 to 1.3.

The number average molecular weight of the polyol component is preferably 300 or more and 5,000 or less. When the number average molecular weight of the polyol component is less than 300, the reaction between the polyol component and the polyisocyanate component is too fast, which makes it difficult to form the thermosetting polyurethane into a uniform sheet, or the flexibility of the thermosetting polyurethane becomes It may become brittle due to a decrease in the sex. When the number average molecular weight of the polyol component exceeds 5000, the viscosity of the polyol component becomes too high, which makes it difficult to form the thermosetting polyurethane into a uniform sheet, or the thermosetting polyurethane crystallizes and becomes cloudy. And other problems may occur. The number average molecular weight of the polyol component is more preferably 500 or more and 2000 or less.

The polyol component is preferably one having an olefin skeleton, that is, one whose main chain is constituted by a polyolefin or a derivative thereof. By using an olefin-based polyol as the polyol component, good heat resistance can be obtained, and since it is hydrophobic, the generation of outgassing due to moisture can be suppressed. Examples of the polyol component having an olefin skeleton include polybutadiene-based polyols such as 1,2-polybutadiene polyol, 1,4-polybutadiene polyol, 1,2-polychloroprene polyol and 1,4-polychloroprene polyol, and polyisoprene Polyols and those having their double bonds saturated with hydrogen or halogen etc. may be mentioned. Further, the polyol component may be a polyol obtained by copolymerizing an olefin compound such as styrene, ethylene, vinyl acetate or acrylic ester with a polybutadiene type polyol or the like or a hydrogenated product thereof. The polyol component may have a linear structure or may have a branched structure. Only one type of polyol component having an olefin skeleton may be used, or two or more types may be used. The polyol component used for the polyurethane preferably contains 80 mol% or more of a polyol component having an olefin skeleton, and more preferably consists only of the polyol component having an olefin skeleton.

Among the known polyol components having an olefin skeleton, for example, a polyolefin polyol (“EPOL (registered trademark)”) obtained by hydrogenating hydroxyl-terminated polyisoprene manufactured by Idemitsu Kosan Co., Ltd., number average molecular weight: 2500), both-end hydroxyl group hydrogenated polybutadiene (“GI-1000”, number average molecular weight: 1500) manufactured by Nippon Soda Co., Ltd., polyhydroxy polyolefin oligomer (“Polytail (registered trademark)”) manufactured by Mitsubishi Chemical Corporation, etc. may be mentioned. .

[Polyisocyanate component]
The polyisocyanate component is not particularly limited, and conventionally known polyisocyanates can be used, and hydrophilic polyisocyanate having a hydrophilic unit (hydrophilic group) and hydrophobic polyisocyanate having no hydrophilic unit Either one or both may be used. The above-mentioned hydrophilic polyisocyanate is not a compound whose hydrophilicity is improved only by a structure derived from an isocyanate group like an isocyanurate structure or a biuret structure, but a functional group (hydrophilic group) for enhancing the hydrophilicity is added. It is preferable that it is a polyisocyanate.

An ethylene oxide unit is suitable as the hydrophilic unit. The action of suppressing whitening due to moisture absorption can be obtained by including the hydrophilic unit. It is preferable that content of the said ethylene oxide unit is 0.1 weight% or more and 20 weight% or less with respect to the whole thermosetting polyurethane composition. If the content is less than 0.1% by weight, whitening may not be sufficiently suppressed. When the content is more than 20% by weight, the compatibility with the low polar olefin-based polyol component, tackifier, plasticizer and the like is reduced, whereby the optical properties such as haze may be reduced. The content of the ethylene oxide unit is more preferably 0.1 to 5% by weight. When the content exceeds 5% by weight, the amount of moisture absorption in the high temperature and high humidity environment may be too large.

Examples of hydrophilic units other than ethylene oxide units include units containing a carboxylic acid group, an alkali metal base of carboxylic acid, a sulfonic acid group, an alkali metal base of sulfonic acid, a hydroxyl group, an amide group, an amino group and the like. More specifically, polyacrylic acid, alkali metal salt of polyacrylic acid, sulfonic acid group-containing copolymer, alkali metal salt of sulfonic acid group-containing copolymer, polyvinyl alcohol, polyacrylamide, carboxymethylcellulose, alkali metal of carboxymethylcellulose Salt, polyvinyl pyrrolidone and the like can be mentioned.

As a hydrophilic polyisocyanate which has the said hydrophilic unit, the modified polyisocyanate obtained by making aliphatic polyisocyanate and the ether compound which has an ethylene oxide unit react is used suitably, for example. By using the aliphatic polyisocyanate, it is possible to prevent the occurrence of coloration or discoloration of the optically transparent pressure-sensitive adhesive sheet, and to ensure the transparency of the optically transparent pressure-sensitive adhesive sheet for a long time more reliably. In addition, the polyisocyanate component can suppress whitening by the action of the hydrophilic portion (ethylene oxide unit) by forming a modified product in which an ether compound having an ethylene oxide unit is reacted, and the hydrophobic portion (other unit) The compatibility with low polarity tackifiers, plasticizers, etc. can be exhibited by the action of

Examples of the aliphatic polyisocyanate include hexamethylene diisocyanate, tetramethylene diisocyanate, 2-methyl-pentane-1,5-diisocyanate, 3-methyl-pentane-1,5-diisocyanate, lysine diisocyanate, trioxyethylene diisocyanate And isophorone diisocyanate, cyclohexyl diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, norbornane diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate, hydrogenated tetramethyl xylene diisocyanate, and modified products thereof. These may be used alone or in combination of two or more. In addition, as a modified body of hexamethylene diisocyanate, what carried out isocyanurate modification, allophanate modification, and / or urethane modification etc. of hexamethylene diisocyanate, etc. are mentioned, for example.

Examples of the ether compounds having ethylene oxide units include ethylene oxide adducts of alcohols, phenols and / or amines, and from the viewpoint of enhancing hydrophilicity, those having three or more ethylene oxide units per molecule It is preferably used.

Examples of the alcohol include monohydric alcohols, dihydric alcohols (ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,3-butylenediol And peopentyl glycol etc., trihydric alcohols (glycerin, trimethylolpropane etc.). These may be used alone or in combination of two or more.

Examples of the above-mentioned phenols include hydroquinone, bisphenols (bisphenol A, bisphenol F, etc.), and formalin low condensates of phenol compounds (novolak resin, intermediate of resole). These may be used alone or in combination of two or more.

The number of isocyanate groups per molecule of the modified polyisocyanate is preferably 2.0 or more on average. If the number of isocyanate groups is less than 2.0 on average, the decrease in the crosslink density may result in the thermosetting polyurethane composition not sufficiently curing.

The above-mentioned hydrophobic polyisocyanate is not particularly limited, but aliphatic isocyanates are suitably used. For example, hexamethylene diisocyanate (HDI), tetramethylene diisocyanate, 2-methyl-pentane-1,5-diisocyanate, 3-methyl -Pentane-1,5-diisocyanate, lysine diisocyanate, trioxyethylene diisocyanate, isophorone diisocyanate (IPDI), cyclohexyl diisocyanate, 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI), norbornane diisocyanate (NBDI), hydrogenated tolylene And isocyanates, hydrogenated xylene diisocyanate, hydrogenated tetramethyl xylene diisocyanate, and modified products thereof. These may be used alone or in combination of two or more.

The compounding ratio of the hydrophilic polyisocyanate having the hydrophilic unit and the hydrophobic polyisocyanate not having the hydrophilic unit is preferably 9: 1 to 1: 1, from the viewpoint of achieving both the prevention of whitening and the reduction of the moisture absorption rate. 9, and more preferably 7: 3 to 3: 7.

The thermosetting polyurethane composition preferably has an α ratio of 1 or more (mole number of OH group derived from polyol component / mole number of NCO group derived from polyisocyanate component). When the α ratio is less than 1, the amount of the polyisocyanate component is excessive with respect to the amount of the polyol component, so the thermosetting polyurethane becomes hard, and the flexibility required for the optical transparent adhesive sheet is It becomes difficult to secure. If the flexibility of the optical transparent pressure-sensitive adhesive sheet is low, in particular, when bonding an optical member such as a touch panel, it is not possible to cover the unevenness and the level difference present on the bonding surface. Moreover, there is a possibility that the adhesive force required for the optical transparent adhesive sheet can not be secured. The α ratio more preferably satisfies 1.3 <α <2.0. When the α ratio is 2.0 or more, the thermosetting polyurethane composition may not be cured sufficiently.

[Silane coupling agent]
The thermosetting polyurethane composition is a silane coupling agent, a silane coupling monomer (A) having a first organic functional group blocked by a protective group, or a silane coupling having a second organic functional group It contains an oligomer (B).

As the silane coupling monomer (A), at least one inorganic functional group (first inorganic functional group) chemically bonded to the inorganic material and at least one organic functional group chemically bonded to the organic material (in the molecule) A silane compound having a first organic functional group), wherein at least one of the first organic functional groups is bonded to a protective group can be used. The above-mentioned silane coupling monomer (A) preferably has three inorganic functional groups and one organic functional group in the molecule.

As said 1st inorganic functional group, a methoxy group and an ethoxy group are mentioned, for example. When at least one of the first inorganic functional groups is an ethoxy group, the hydrolysis reaction can be delayed and outgassing causing foaming can be reduced.

Examples of the first organic functional group include acryloyl group, methacryloyl group, epoxy group, amino group, ureido group, mercapto group, isocyanate group and vinyl group. Among these, amino group and mercapto group are preferable. Since an amino group and a mercapto group easily hydrogen bond with a hydroxyl group of urethane, when an amino group or a mercapto group is used as the first organic functional group, it is heated after bonding to an inorganic adherend such as glass. The adhesion can be greatly improved.

The protective group is not particularly limited as long as it binds to the first organic functional group to reduce the reactivity of the first organic functional group, and is released from the first organic functional group by hydrolysis. Is preferred. By blocking the organic functional group with the protective group, the silane coupling monomer (A) can be stably present in the optically transparent pressure-sensitive adhesive sheet without reaction, and easily migrate to the sheet surface. Therefore, the silane coupling agent is likely to be segregated on the sheet surface. When the first organic functional group is an amino group, by using a ketone compound as a protecting group, a ketimine structure is formed as an organic functional group blocked by the protecting group. The ketimine structure is easily hydrolyzed to give primary amines.

FIG. 1 is a view for explaining the action mechanism of the silane coupling agent. As shown in FIG. 1, the silane coupling agent is hydrolyzed by water to be silanol and then partially condensed to form an oligomer. Subsequently, the surface of the adherend 100 is adsorbed by an interaction such as hydrogen bonding. Thereafter, when a dehydration condensation reaction occurs due to heating or the like, it chemically strongly bonds to the surface of the adherend 100. As described above, the optical transparent pressure-sensitive adhesive sheet of the present invention does not exhibit high adhesive strength immediately after bonding, and by heating, the adhesive strength is significantly improved and can be firmly bonded to the adherend. Therefore, the optical transparent adhesive sheet of the present invention is excellent in reworkability.

It is preferable that content of the said silane coupling monomer (A) is 0.1 weight% or more and 4.0 weight% or less with respect to a thermosetting polyurethane composition. When content of a silane coupling monomer (A) is less than 0.1 weight%, the adhesive force of an optical transparent adhesive sheet may not fully be improved. When the content of the silane coupling monomer (A) exceeds 4.0% by weight, the surface segregation of the silane coupling monomer (A) becomes excessive, and the adhesion at normal temperature may be significantly reduced.

As the silane coupling oligomer (B) having the second organic functional group, those having a structure in which at least one organic functional group (second organic functional group) chemically bonded to the organic material is bonded to a siloxane chain Specific examples include alkoxy oligomers in which at least one alkoxy group and at least one second organic functional group are bonded to a siloxane chain in the molecule. Such alkoxy oligomers can be produced by hydrolytic condensation of alkoxysilanes.

As said alkoxy group, a methoxy group and an ethoxy group are mentioned, for example. When at least one of the alkoxy groups is an ethoxy group, the hydrolysis reaction can be delayed to reduce outgassing causing foaming.

Examples of the second organic functional group include acryloyl group, methacryloyl group, epoxy group, amino group, ureido group, mercapto group, isocyanate group and vinyl group, and among them, acryloyl group, methacryloyl group, epoxy group, Mercapto and vinyl are preferred. When an acryloyl group, a methacryloyl group, an epoxy group, a mercapto group or a vinyl group is used as the second organic functional group, the adhesion can be significantly improved when heated after bonding to the adherend.

As the silane coupling oligomer (B) having the second organic functional group, one having an isocyanurate ring (trimer of isocyanate group) may be used as the second organic functional group. The isocyanurate ring can be stably present without reacting in the optically transparent pressure-sensitive adhesive sheet, and thus easily migrate to the sheet surface. Therefore, the silane coupling agent is likely to be segregated on the sheet surface.

By using the silane coupling oligomer (B) having a second organic functional group as the silane coupling agent, the compatibility of the silane coupling agent with the polyol component and the polyisocyanate component can be reduced, and the silane coupling Since the functional group of the agent tends to segregate at the interface with the adherend, it can be strongly bonded to the adherend. Moreover, when it contains a siloxane chain, it also has the advantage of low volatility and good heat resistance and light resistance.

It is preferable that content of the said silane coupling oligomer (B) is 0.1 weight% or more and 4.0 weight% or less with respect to a thermosetting polyurethane composition. When content of a silane coupling oligomer (B) is less than 0.1 weight%, the adhesive force of an optical transparent adhesive sheet may not fully be improved. When the content of the silane coupling oligomer (B) exceeds 4.0% by weight, the surface segregation of the silane coupling oligomer (B) is excessive, and the adhesion at normal temperature may be significantly reduced.

[Tackfire]
The thermosetting polyurethane composition may further contain a tackifier (tackifier). A tackifier is an additive that is added to improve adhesion, and is usually an amorphous oligomer with a molecular weight of several hundred to several thousand, and is a thermoplastic resin that is liquid or solid at normal temperature. When the thermosetting polyurethane composition contains a tackifier, the adhesion of the optically transparent pressure-sensitive adhesive sheet formed of the cured product of the thermosetting polyurethane composition can be improved.

The above-mentioned tackifier is not particularly limited, and examples thereof include petroleum resin-based tackifiers, hydrocarbon resin-based tackifiers, rosin-based tackifiers, terpene-based tackifiers and the like. Only one type of these may be contained, or two or more types may be contained.

As the above-mentioned tackifier, a petroleum resin-based tackifier is suitably used since it is excellent in compatibility with the polyol component having the above-mentioned olefin skeleton. Among the above-mentioned petroleum resin-based tackifiers, a hydrogenated petroleum resin obtained by hydrogenating a copolymer of dicyclopentadiene and an aromatic compound is preferably used. Dicyclopentadiene is obtained from the C5 fraction. As said aromatic compound, vinyl aromatic compounds, such as styrene, (alpha)-methylstyrene, vinyl toluene, are mentioned, for example. The ratio of dicyclopentadiene to the vinyl aromatic compound is not particularly limited, but on a weight basis, it is preferable that dicyclopentadiene: vinyl aromatic compound = 70: 30 to 20:80, 60:40 to 40:60. It is more preferable that The preferable softening point of the above-mentioned hydrogenated petroleum resin is 90 to 160 ° C., the preferable vinyl aromatic compound unit content is 35 mass% or less, the preferable bromine number is 0 to 30 g / 100 g, and the preferable number average molecular weight is 500 to 1100. As a well-known thing among said hydrogenated petroleum resins, "Imarb P-100" by Idemitsu Kosan Co., Ltd. is mentioned, for example.

As said tackifier, since it is excellent in compatibility with the polyol component etc. which have the said olefin frame, a hydrocarbon resin type tackifier is used suitably. Among the above-mentioned hydrocarbon resin tackifiers, alicyclic saturated hydrocarbon resins are preferably used. Among the above-mentioned alicyclic saturated hydrocarbon resins, known ones include, for example, "Arcon P-100" manufactured by Arakawa Chemical Industries, Ltd.

It is preferable that content of the said tackifier is 1 weight% or more and 20 weight% or less with respect to a thermosetting polyurethane composition. When the content of the tackifier is less than 1% by weight, the adhesion of the optical transparent adhesive sheet may not be sufficiently improved, and in particular, the adhesion under high temperature and high humidity may be insufficient. . When the content of the tackifier exceeds 20% by weight, the reaction between the polyol component and the polyisocyanate component may be inhibited, and urethane crosslinking may not be sufficiently formed in the thermosetting polyurethane. As a result, the optical transparent pressure-sensitive adhesive sheet may be dissolved and the shape may change or the tackifier may be precipitated (bleed) under high temperature and high humidity. In addition, if the reaction time between the polyol component and the polyisocyanate component is increased to sufficiently form urethane crosslinking, the productivity is lowered.

[Plasticizer]
The thermosetting polyurethane composition may further contain a plasticizer. By the addition of the plasticizer, the hardness can be reduced, whereby the handling property and the level difference followability of the optical transparent pressure-sensitive adhesive sheet of the present invention can be improved.

The plasticizer is not particularly limited as long as it is a compound used to impart flexibility to a thermoplastic resin, but from the viewpoint of compatibility and weather resistance, it is preferable to include a carboxylic plasticizer. Examples of the carboxylic acid plasticizer include phthalic acid esters such as diundecyl phthalate, dioctyl phthalate, diisononyl phthalate, diisodecyl phthalate, and dibutyl phthalate (phthalic acid plasticizers), and 1,2-cyclohexanedicarboxylic acid. Acid diisononyl ester, adipic acid ester, trimellitic acid ester, maleic acid ester, benzoic acid ester, poly-α-olefin and the like can be mentioned. Only one type of these may be contained, or two or more types may be contained. Among the above-mentioned carboxylic acid plasticizers, for example, “DINCH” manufactured by BASF, “San-sizer DUP” manufactured by Shin Nippon Rika, “Durasyn (registered trademark) 148” manufactured by Iones Oligomers, etc. Can be mentioned.

[catalyst]
The thermosetting polyurethane composition may further contain a catalyst. The catalyst is not particularly limited as long as it is a catalyst used for the urethanation reaction, for example, organic tin compounds such as di-n-butyl tin dilaurate, dimethyl tin dilaurate, dibutyl tin oxide, octane tin, etc .; organic titanium compounds Organic zirconium compounds; carboxylic acid tin salts; carboxylic acid bismuth salts; amine-based catalysts such as triethylenediamine.

In the above-mentioned thermosetting polyurethane composition, various additives such as a coloring agent, a stabilizer, an antioxidant, a mildew, a flame retardant and the like are optionally added within the range not to impair the required characteristics of the optical transparent pressure sensitive adhesive sheet. It may be added.

It is preferable that the thickness of the optical transparent adhesive sheet of this invention is 50-3000 micrometers. In the case where the thickness is less than 50 μm, when one surface of the optically transparent pressure-sensitive adhesive sheet is attached to the surface of the optical member, the optically transparent pressure-sensitive adhesive sheet may cover asperities or steps existing on the surface of the optical member In some cases, the other surface of the optical transparent pressure-sensitive adhesive sheet can not be attached to the surface of another optical member with sufficient adhesion. Further, the thicker the optical transparent adhesive sheet, the larger the amount of moisture absorption, and therefore delayed bubbles due to moisture absorption tend to occur, but if the thickness is 3000 μm or less, delayed bubbles due to moisture absorption can be sufficiently suppressed. The more preferable lower limit of the thickness of the optical transparent pressure-sensitive adhesive sheet is 300 μm, and the more preferable upper limit is 2000 μm. Moreover, it is preferable that an optical transparent adhesive sheet has thickness 3 times or more with respect to the height of the unevenness | corrugation or level | step difference which exists in the sticking surface of a to-be-adhered body.

It is preferable that the optical transparent adhesive sheet of this invention is 5 N / 25 mm or less in initial stage adhesive force in 23 degreeC with respect to a glass surface. Moreover, it is preferable that the optical transparent adhesive sheet of this invention is 5 N / 25 mm or less in initial stage adhesive force in 23 degreeC with respect to the surface of a polycarbonate. If the initial adhesive strength is 5 N / 25 mm or less, when the optically transparent pressure-sensitive adhesive sheet is used for laminating optical members such as a touch panel, it can be peeled off without adhesive residue, so it is excellent in reworkability. Moreover, when the adhesive force of an optical transparent adhesive sheet becomes large too much, it may become difficult to pull out the bubble which entered between the optical transparent adhesive sheet and a to-be-adhered body at the time of bonding. In addition, when bonding optical members, such as a touch panel, with the optical transparent adhesive sheet of this invention, the autoclave process which removes a bubble and a vacuum void after bonding may be implemented at the temperature of about 50 degreeC. In order to be able to be reworked up to the autoclave treatment, it is preferable that the initial tackiness is low and the tackiness increase after the autoclave treatment. The optical transparent pressure-sensitive adhesive sheet of the present invention preferably has an adhesive strength of 10 N / 25 mm or more with respect to the glass surface after holding at 50 ° C. for 2 hours. Moreover, it is preferable that the adhesive force of the optical transparent adhesive sheet of this invention after holding for 2 hours at 50 degreeC with respect to the surface of a polycarbonate is 10 N / 25 mm or more. If the adhesive strength after holding at 50 ° C. for 2 hours is less than 10 N / 25 mm, the generation of delayed bubbles may not be suppressed.

The said adhesive force points out the value measured by the 180 degree peeling test which makes a base material made of glass or a polycarbonate a to-be-adhered body. The 180 ° peel test can be conducted by the following method to measure the adhesion (N / 25 mm). FIG. 2: is a schematic diagram for demonstrating the measuring method of the adhesive force of an optical transparent adhesive sheet. First, the optically transparent adhesive sheet 12 is attached to the base 31. Next, as shown to Fig.2 (a), the PET sheet 32 is affixed on the surface on the opposite side to the base material 31 of the optical transparent adhesive sheet 12. As shown in FIG. Thereafter, as shown in FIG. 2 (b), the PET sheet 32 is pulled in the direction of 180 ° to peel off the optically transparent adhesive sheet 12 at the interface with the substrate 31, and the adhesion of the optically transparent adhesive sheet 12 to the substrate 31 Measure

The optical transparent adhesive sheet of the present invention preferably has a haze of 0.5% or less and a total light transmittance of 90% or more in order to ensure the performance as an optical transparent adhesive sheet. . The haze and the total light transmittance can be measured, for example, using a turbidity meter “HazeMeter NDH 2000” manufactured by Nippon Denshoku Industries Co., Ltd. The haze is measured by the method according to JIS K 7136, and the total light transmittance is measured by the method according to JIS K 7361-1.

A release film may be attached to both sides of the optical transparent adhesive sheet of the present invention. The optical transparent adhesive sheet of the present invention, a first release film covering one side of the optical transparent adhesive sheet, and a second release film covering the other side of the optical transparent adhesive sheet are laminated The laminated sheet (hereinafter, also referred to as "the laminated sheet of the present invention") which is one of them is also an aspect of the present invention. By attaching the first and second release films, the surface of the optical transparent pressure-sensitive adhesive sheet of the present invention can be protected until just before being attached to the adherend. As a result, it is possible to prevent the decrease in adhesiveness and the adhesion of foreign matter. Moreover, since it can prevent sticking other than a to-be-adhered body, the handleability of the optical transparent adhesive sheet of this invention can be improved.

For example, a polyethylene terephthalate (PET) film can be used as the first and second release films. The material and thickness of the first release film and the second release film may be the same or different.

The bonding strength (peel strength) of the optical transparent adhesive sheet of the present invention to the first release film and the bonding strength of the optical transparent adhesive sheet of the present invention to the second release film may be different from each other preferable. The optical transparent adhesion which peeled and exposed only one of the first and second release films (the release film with the weaker bonding strength) from the laminated sheet of the present invention due to the difference in the bonding strength. The first surface of the sheet and the first adherend were laminated, and then the other of the first and second release films (the release film with higher adhesion strength) was peeled off and exposed It becomes easy to bond together the 2nd surface and the 2nd adherend of an optical transparent adhesive sheet. The surface of the first release film in contact with the optical transparent adhesive sheet of the present invention, and the surface of the second release film in contact with the optical transparent adhesive sheet of the present invention, or both An easy peeling process (mold releasing process) may be performed. As an easy peeling process, a silicon process is mentioned, for example.

The application of the optical transparent pressure-sensitive adhesive sheet of the present invention is not particularly limited, and a first adherend, a second adherend, and the first adherend and the second adherend are joined. A laminate comprising the optical transparent pressure-sensitive adhesive sheet of the present invention is also an aspect of the present invention. As a 1st and 2nd to-be-adhered body, a glass base material and a resin base material are used suitably, for example. The materials of the first and second adherends may be the same or different. For example, the first adherend is a glass substrate and the second adherend is It may be a resin base material.

The said glass base material will not be specifically limited if the surface which contact | connects an optical transparent adhesive sheet was comprised with glass, For example, Display apparatuses, such as a display panel, a touch panel (glass substrate with an ITO transparent conductive film), a cover glass The various members made of glass which comprise are mentioned. The type of display panel is not particularly limited, and examples thereof include a liquid crystal panel and an organic electroluminescence panel (organic EL panel). By bonding various members in the display using the optically transparent adhesive sheet, the air layer (air gap) in the display can be eliminated, and the visibility of the display screen can be improved. Moreover, if an optical transparent adhesive sheet is stuck on a glass base material, the effect which prevents scattering of glass will be acquired.

The said resin base material will not be specifically limited if the surface which contact | connects an optical transparent adhesive sheet was comprised with resin (plastic), For example, Display apparatuses, such as a cover panel, a touch sensor film, a polarizing plate, retardation film The various resin-made members which comprise these are mentioned. The resin substrate may include a portion made of a material other than resin, but from the viewpoint of obtaining the effect of the present invention to suppress the generation of delayed bubbles, the thickness of the portion made of resin is 1 mm It is preferable that it is more than. If the thickness of the portion made of resin is less than 1 mm, the amount of water contained in the inside of the resin base material is small, so there is a possibility that the need to suppress the generation of delayed bubbles is small.

It does not specifically limit as resin which comprises the said resin base material, For example, a polycarbonate, polymethyl methacrylate resin (PMMA), triacetyl cellulose (TAC) etc. are mentioned. Among them, polycarbonate is preferable from the viewpoint of obtaining the effect of the present invention for suppressing the generation of delayed bubbles. In the case where the resin substrate contains a polycarbonate, delayed bubbles are likely to be generated remarkably, and the generation of delayed bubbles can be effectively suppressed by the present invention. Moreover, when the resin base material is a polarizing plate, the surface which contact | connects an optical transparent adhesive sheet may be comprised with a triacetyl cellulose.

As a laminated body of this invention, the display apparatus with a touch panel provided with the optical transparent adhesive sheet of this invention, a display panel, and a touch panel is mentioned, for example. FIG. 3: is sectional drawing which showed typically an example of the display apparatus with a touch panel using the optical transparent adhesive sheet of this invention. In the display device 10 shown in FIG. 3, the display panel 11, the optically transparent adhesive sheet 12, the touch panel (glass substrate with ITO transparent conductive film) 13, the optically transparent adhesive sheet 12, and the transparent cover panel 14 are sequentially stacked. The three optical members of the display panel 11, the touch panel 13 and the transparent cover panel 14 are integrated by two optically transparent adhesive sheets 12 of the present invention. The type of the display panel 11 is not particularly limited, and, for example, a liquid crystal panel, an organic electroluminescence panel (organic EL panel), or the like can be used. As the touch panel 13, for example, a detection method such as a resistance film method or a capacitance method is used.

The display panel 11 is housed in a bezel (a housing of the display panel 11) 11A having an opening on the display surface side, and a step corresponding to the thickness of the bezel 11A is present at the outer edge of the opening of the bezel 11A. Do. The optically transparent adhesive sheet 12 is attached to cover the display surface side of the display panel 11 and the bezel 11A, and covers a step corresponding to the thickness of the bezel 11A. According to the structure in which the optically transparent adhesive sheet 12 is disposed on the bezel so as to cover the step formed by the bezel 11A (hereinafter, also referred to as "bezel-on bonding structure"), the optically transparent adhesive sheet 12 is a step of the bezel 11A. Since the formation portion is covered, not only can the end portion of the optical transparent adhesive sheet 12 be prevented from being visually recognized, but the optical transparent adhesive sheet 12 is sandwiched between the step forming portion of the bezel 11A and the upper substrate (touch panel 13) Thus, peeling from the end of the optically transparent adhesive sheet 12 can be prevented. In order to cover the step formed by the thickness of the bezel 11A, the optical transparent adhesive sheet 12 is required to have flexibility to follow the step and a thickness greater than the thickness of the bezel 11A. Thus, it is preferable that the thickness of the optically transparent adhesive sheet 12 used for bonding with the display panel 11 accommodated in the bezel 11A is, for example, 700 μm or more. The optical transparent pressure-sensitive adhesive sheet of the present invention has sufficient optical properties and flexibility even if it has a thickness of 700 μm or more, and is preferably used for bonding with the display panel 11 housed in the bezel 11A. it can.

In such a display device, since the optical transparent adhesive sheet of the present invention is used, the adhesive power of the optical transparent adhesive sheet is unlikely to decrease even when used under various environments, and the optical member is used for a long period of time It can be stuck to each other. As a result, since a space | gap does not generate | occur | produce between each optical member and an optical transparent adhesive sheet, the fall of the visibility by the increase of interface reflection etc. can be prevented. The optical transparent adhesive sheet of the present invention can be used, for example, in an on-vehicle display device such as a display device incorporated in a car navigation device or a display device for a portable device such as a smartphone.

The process for producing the transparent optical pressure-sensitive adhesive sheet of the present invention is not particularly limited. For example, after preparing a thermosetting polyurethane composition, a method may be mentioned in which the composition is thermally cured by a conventionally known method. And (ii) preparing a thermosetting polyurethane composition by stirring and mixing a polyol component, a polyisocyanate component and a silane coupling agent, and curing the thermosetting polyurethane composition.

As the polyol component, the polyisocyanate component and the silane coupling agent, those which are liquid at normal temperature (23 ° C.) can be used, and a thermosetting polyurethane can be obtained without using a solvent. Other components such as tackifiers can be added to either the polyol component and the polyisocyanate component, and are preferably added to the polyol component. Thus, when producing an optical transparent adhesive sheet using a thermosetting polyurethane composition, since removal of a solvent is unnecessary, a uniform sheet | seat can be thickly formed. For this reason, when using the optical transparent adhesive sheet of this invention for bonding of a display panel and the transparent member (touch panel) which has a transparent conductive film in surface layer, the level | step difference of a bezel can be covered.

As an example of the manufacturing method, first, a master batch is prepared by adding a predetermined amount of tackifier to the polyol component and dissolving it by heating and stirring. Subsequently, the obtained masterbatch, polyol component, polyisocyanate component, silane coupling agent, and, if necessary, other components such as a catalyst and the like are mixed and stirred by a mixer or the like to form a liquid or gel. A thermosetting polyurethane composition is obtained. Thereafter, the thermosetting polyurethane composition is immediately charged into a molding apparatus, and the thermosetting polyurethane composition is moved while being moved between the first and second release films, thereby causing crosslinking and curing. The polyurethane composition is semi-cured to obtain a sheet integrated with the first and second release films. Thereafter, a cross-linking reaction is carried out in a furnace for a fixed time to obtain an optically transparent pressure-sensitive adhesive sheet comprising a cured product of a thermosetting polyurethane composition, and the laminate sheet of the present invention is completed.

FIG. 4: is a schematic diagram for demonstrating an example of the shaping | molding apparatus used for preparation of the optical transparent adhesive sheet of this invention. In the forming apparatus 20 shown in FIG. 4, first, a pair of release films in which the liquid or gel thermosetting polyurethane composition 23 before curing is continuously fed from a pair of forming rolls 22 arranged at a distance from each other. (PET film) 21 is poured into the gap. Then, while the thermosetting polyurethane composition 23 is held in the gap between the pair of release films 21, it is carried into the heating device 24 while advancing the curing reaction (crosslinking reaction). In the heating device 24, the thermosetting polyurethane composition 23 is thermally cured in a state of being held between a pair of release films (PET film) 21, and an optically transparent adhesive sheet comprising a cured product of the thermoplastic polyurethane composition The molding of 12 is completed.

As a process for producing the optically transparent adhesive sheet of the present invention, after preparing a thermosetting polyurethane composition before curing, a general-purpose film forming apparatus such as various coating apparatus, bar coat, doctor blade or the like and a film forming method are used. It may be. In addition, the optical transparent pressure-sensitive adhesive sheet of the present invention may be produced using a centrifugal molding method.

EXAMPLES Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

Example 1
100 parts by weight of a polyolefin polyol ("EPOL (registered trademark)" manufactured by Idemitsu Kosan Co., Ltd., number average molecular weight: 2500), 10 parts by weight of a modified polyisocyanate ("Coronato 4022" manufactured by Tosoh Corp.) having a hydrophilic unit, 1.3 parts by weight of a silane coupling agent (3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine), hydrogenated petroleum resin based tackifier (Iimab P-100, manufactured by Idemitsu Kosan Co., Ltd.) 20 parts by weight and 0.05 parts by weight of dimethyltin dilaurate ("Fomrez catalyst UL-28" manufactured by Momentive, Inc.) are stirred and mixed using a reciprocating rotary agitator, and the α ratio is 1.85 A thermosetting polyurethane composition was prepared.

Thereafter, the obtained thermosetting polyurethane composition was injected into the molding apparatus 20 shown in FIG. Then, while conveying the thermosetting polyurethane composition in a state of being sandwiched by a pair of release films (PET film whose surface has been subjected to release treatment) 21, conditions of an oven temperature of 70 ° C. and an oven time of 10 minutes It was cross-linked and hardened. Then, the crosslinking reaction was performed for 12 hours by the heating device 24 adjusted to 70 ° C., and an optically transparent adhesive sheet 12 made of a cured product of the thermosetting polyurethane composition was produced. The thickness of the optical transparent adhesive sheet 12 was 300 μm.

Optically bonded to a transparent glass substrate (soda glass manufactured by Matsunami Glass Co., Ltd.) by vacuum bonding one surface of the optical transparent adhesive sheet from which the mold release film was peeled off at a pressure of 0.15 MPa and peeling the mold release film A 2 mm-thick resin substrate was vacuum bonded to the other surface of the transparent adhesive sheet at a pressure of 0.15 MPa, and a laminate was obtained by bonding a glass substrate and a resin substrate by an optically transparent adhesive sheet. . As a resin base material, hard coating is applied to both sides of "UW2-070" manufactured by Kuraray Co., Ltd., which is a resin board obtained by acrylic primer treatment of one side of a polycarbonate board ("MT2LX" manufactured by Kuraray Co., Ltd.) An optically clear pressure-sensitive adhesive sheet was attached to the side not subjected to the acrylic primer treatment using the one to which "PMR" was applied.

Finally, the resulting laminate was heated at 50 ° C. Before heating, bonding of the glass substrate and the optical transparent adhesive sheet, and bonding of the resin substrate and the optical transparent adhesive sheet can be easily peeled off, and the optical transparent adhesive sheet may be used if necessary. It was possible to paste again. On the other hand, after heating, the optically transparent pressure-sensitive adhesive sheet was chemically bonded to the surfaces of the glass substrate and the resin substrate, and the glass substrate and the resin substrate were firmly adhered by the optically transparent pressure-sensitive adhesive sheet. In addition, although it heated in order to shorten the time which adhesion | attachment requires, sufficient adhesive strength is obtained only by leaving it to stand at normal temperature for about 1 day.

(Examples 2-4, comparative examples 1-4)
As shown in Table 1 below, in the same manner as in Example 1 except that the type of silane coupling agent was changed, an optical transparent adhesive with a release film according to Examples 2 to 4 and Comparative Examples 1 to 4 Each sheet was produced.

(Measurement of adhesion to glass plate)
The 180 ° peel test was conducted by the method shown in FIG. 2 to measure the adhesive strength (N / 25 mm). Specifically, the optical transparent adhesive sheet with a release film was cut into a length of 75 mm × width 25 mm as a test piece. After peeling the release film on one side of this test piece, the optical transparent adhesive sheet 12 side is attached to the base material 31 of length 75 mm × width 25 mm, and held for 30 minutes at a pressure of 0.4 MPa. 12 and the base material 31 were bonded together. Next, the release film on the side opposite to the substrate 31 is peeled off, and as shown in FIG. 2 (a), a PET sheet with a thickness of 125 μm on the side opposite to the substrate 31 of the optical transparent adhesive sheet 12 ("Melinex (registered trademark) S" manufactured by Teijin DuPont Films, Inc.) 32 was laminated. Then, after standing for 12 hours under normal temperature and normal humidity (temperature 23 ° C., humidity 50%), as shown in FIG. 2 (b), the PET sheet 32 is pulled in the direction of 180 ° to make the optically transparent adhesive sheet 12 It was made to peel at the interface with the material 31, and the adhesion of the optical transparent adhesive sheet 12 to the substrate 31 was measured.

The measurement was performed using a glass plate as the substrate 31. In addition, the adhesive strength immediately after bonding (initial adhesive strength) and the adhesive power after being put in an environment of 50 ° C for 2 hours after bonding, and the adhesive after being put in an environment of 50 ° C for 12 hours after bonding The force was measured. Each measurement was performed by preparing two test pieces for each example and comparative example, and the average value of the two measured values obtained was taken as the measurement result in each example and comparative example.

In addition, silane coupling agents A to H in Table 1 represent the following compounds or commercially available products.
A: 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine (amino-protected type (ketimine type))
B: Siloxane "KR-519" manufactured by Shin-Etsu Chemical Co., Ltd. (organic functional group: mercapto, alkoxy group: methoxy)
C: Organosilane "X-12-1056 ES" (mercapto protected type) manufactured by Shin-Etsu Chemical Co., Ltd.
D: Tris- (trimethoxysilylpropyl) isocyanurate E: 3-glycidoxypropylmethyldiethoxysilane F: 3-glycidoxypropyltriethoxysilane G: N-2- (aminoethyl) -3-aminopropyl Methyldimethoxysilane H: N-2- (aminoethyl) -3-aminopropyltrimethoxysilane

As can be seen from Table 1, the optically transparent adhesive sheet of Examples 1 and 3 to which a silane coupling monomer having a first organic functional group blocked by a protective group is added, and a silane cup having a second organic functional group The optical transparent pressure-sensitive adhesive sheets of Examples 2 and 4 to which a ring oligomer was added, the adhesive strength was improved by heating to 50 ° C., and sufficient adhesive strength to the adherend was obtained. On the other hand, in the optically transparent pressure-sensitive adhesive sheets of Comparative Examples 1, 2 and 4, the adhesion did not improve even when heated to 50 ° C. Moreover, although the adhesive force improved by heating at 50 degreeC, the optically transparent adhesive sheet of the comparative example 3 did not acquire sufficient adhesive strength with respect to a to-be-adhered body even if it heated for 12 hours.

(Measurement of adhesion to polycarbonate plate)
About the optically transparent adhesive sheet of Example 1 and 4, the 180 degree peeling test was done by the method shown in FIG. 2, and the adhesive force with respect to a polycarbonate board was measured.
The optical transparent adhesive sheet of Example 1 has an initial adhesive strength of 1.0 (N / 25 mm), and an adhesive strength of 2.3 (N / 25 mm) after being put in an environment of 50 ° C. for 30 minutes. )Met. The optical transparent adhesive sheet of Example 4 has an initial adhesive strength of 5.1 (N / 25 mm) and an adhesive strength of 16.5 (N / 25 mm) after being put in an environment of 50 ° C. for 30 minutes. )Met.

(Measurement of confocal Raman spectrum)
The confocal Raman spectrum of the optically transparent pressure-sensitive adhesive sheet of Example 1 was measured with a Raman microscope ("XPoloRa Plus" manufactured by Horiba, Ltd.). An objective lens with a magnification of 20 × was used, and measurement was made at points of 0 μm (sheet surface), 40 μm, 80 μm, 160 μm, and 200 μm from the sheet surface. Moreover, it measured similarly about the undiluted | stock solution of the silane coupling agent used in Example 1 for comparison.

Fig.5 (a) is the graph which showed the confocal Raman spectrum obtained about the optical transparent adhesive sheet of Example 1, FIG.5 (b) is a low wavelength area | region (Raman of the spectrum of Fig.5 (a). Shift is an enlarged graph of 800 cm.sup.- ¹ ). The “single substance” in FIG. 5 (b) corresponds to the measurement result of the stock solution of the silane coupling agent A used in Example 1.

As can be seen from FIG. 5B, the Raman spectrum of the stock solution (single substance) of the silane coupling agent A shows a peak of the Raman intensity of Si derived from the silane coupling agent A in the vicinity of 830 cm ⁻¹ . Therefore, comparing the Raman intensities at around 830 cm ^-1 , the Raman intensity at the depth of 0 μm (sheet surface) is the largest, and as the depth increases from the sheet surface, the Raman intensity in the low wavelength region tends to decrease. The From this, it was confirmed that the silane coupling agent A was segregated in the vicinity of the sheet surface.

(Example 5)
In the same manner as in Example 1 except that the compounding amount of the silane coupling agent was changed to 3 times, an optical transparent pressure-sensitive adhesive sheet with a release film according to Example 5 was produced. The 180 ° peel test was carried out by the method shown in FIG. 2 and the adhesion to the glass plate was measured. The adhesion immediately after bonding (initial adhesion) was 9.8 (N / 25 mm), and bonding was performed. The adhesive strength after being placed in an environment at 50 ° C. for 30 minutes was 24.8 (N / 25 mm).

DESCRIPTION OF SYMBOLS 10 Display device 11 Display panel 11A Bezel 12 Optical transparent adhesive sheet 13 Touch panel 14 Transparent cover panel 20 Molding device 21 Releasing film 22 Molding roll 23 Thermosetting polyurethane composition 24 Heating device 31 Base material 32 PET sheet 100 Adherend

Claims (12)

It is an optical transparent adhesive sheet made of thermosetting polyurethane,
The thermosetting polyurethane is a cured product of a thermosetting polyurethane composition containing a polyol component, a polyisocyanate component and a silane coupling agent,
The above-mentioned silane coupling agent comprises a silane coupling monomer having a first organic functional group blocked by a protective group, or a silane coupling oligomer having a second organic functional group. Sheet. The said 1st organic functional group is an amino group or a mercapto group, The optical transparent adhesive sheet of Claim 1 characterized by the above-mentioned. The optically transparent adhesive sheet according to claim 1, wherein the silane coupling oligomer has a structure in which the second organic functional group is bonded to a siloxane chain. The optically transparent adhesive sheet according to claim 3, wherein the second organic functional group is an acryloyl group, a methacryloyl group, an epoxy group, a mercapto group or a vinyl group. The optically transparent adhesive sheet according to claim 1, wherein the second organic functional group is an isocyanurate ring. The optically transparent pressure-sensitive adhesive sheet according to any one of claims 1 to 5, wherein the polyol component contains an olefin-based polyol. The optically transparent pressure-sensitive adhesive sheet according to any one of claims 1 to 6, wherein a first adherend, a second adherend, the first adherend and the second adherend are joined. A laminate comprising: The laminate according to claim 7, wherein the first adherend is a glass substrate. The laminate according to claim 7, wherein the second adherend is a resin base material. The laminate according to claim 9, wherein the resin substrate contains a polycarbonate. It is a manufacturing method of the optical transparent adhesive sheet in any one of Claims 1-6, Comprising:
Preparing the thermosetting polyurethane composition by stirring and mixing the polyol component, the polyisocyanate component, and the silane coupling agent;
Curing the thermosetting polyurethane composition. The optical transparent adhesive sheet according to any one of claims 1 to 6, a first release film covering one surface of the optical transparent adhesive sheet, and a second covering the other surface of the optical transparent adhesive sheet A laminated sheet characterized in that a release film and a laminated film are laminated.

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