JP2013142131A - Pressure-sensitive adhesive composition for triacetyl cellulose, as well as laminate using the same, optical film and optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure-sensitive adhesive composition with which shrinkage stress of a triacetyl cellulose (TAC) substrate is relaxed and floating from a glass substrate is prevented without using a peroxide even in high temperature and high humidity environment when a TAC substrate 11 and a glass substrate 13 are laminated via a pressure-sensitive adhesive layer 12.SOLUTION: The pressure-sensitive adhesive composition for TAC contains: an acrylic pressure-sensitive adhesive with weight average molecular weight of 400,000 to 900,000; an isocyanate-based curing agent of 0.01 to 0.5 pt.mass in terms of the solid content with respect to the solid content of the acrylic pressure-sensitive adhesive of 100 pts.mass; and an acrylic copolymer composed of a methacrylate polymer block (M) and an acrylate polymer block (A), while the composition does not substantially contain any acid component. The copolymer is suitably an M-A-M type three-block copolymer with weight average molecular weight of 10,000-300,000, and the curing agent is suitably a hexamethylene diisocyanate-based agent.

Description

  The present invention relates to an optical member used for an image display device such as a liquid crystal display or a mobile display equipped with a touch panel, and more specifically, a triacetyl cellulose (hereinafter also referred to as “TAC”) base material and a glass base material. It is related with the adhesive composition which can prevent the adhesive film of a TAC base material from floating from a glass base material, even if it laminates | stacks through.

  A TAC film is used as an optical film constituting an image display device such as a liquid crystal display. TAC has the role of protecting glass and polarizing plates, and if necessary, the hard coat layer for imparting scratch resistance to the surface and the anti-reflection function while maintaining the scratch resistance of the liquid crystal screen. There is also a type in which an antireflection layer or the like that contributes to improvement in visibility is formed.

  A TAC film is laminated | stacked with a glass base material through the adhesion layer, and is used as an optical member. However, since TAC generally has a property of shrinking under wet heat conditions, a problem arises that the adhesive film of the TAC base material floats from the glass base material under high temperature and high humidity.

  In order to solve this problem, for example, Patent Document 1 discloses that, in addition to an acrylic pressure-sensitive adhesive and an isocyanate-based curing agent, a peroxide is contained in combination with a thermal decomposition reaction using a peroxide. Maintaining stress relaxation properties is disclosed.

  Patent Document 2 discloses that the storage elastic modulus (G ′) at 23 ° C. of the pressure-sensitive adhesive layer obtained by crosslinking the layer made of the pressure-sensitive adhesive composition is 32000 in order to prevent warping of the glass substrate. The manufacturing method of the adhesion layer for optical members including the process of heat-processing the layer which consists of an adhesive composition so that the storage elastic modulus (G ') in 70000 Pa and 80 degreeC may be 20000-45000Pa is disclosed.

JP 2006-183022 A JP 2006-316181 A

  As is clear from the examples, the pressure-sensitive adhesives of Patent Documents 1 and 2 both contain a peroxide, thereby using a thermal decomposition reaction with the peroxide and maintaining sufficient stress relaxation properties. It is.

  However, when a peroxide is contained as a third component other than the curing agent, the remaining peroxide causes a problem that the cross-linking reaction proceeds with time and the adhesive physical properties are changed. A problem arises in that the pressure-sensitive adhesive deteriorates with time because it decomposes with light or heat and generates radicals. For this reason, a method of suppressing floating and peeling without containing a peroxide has been desired.

  The present invention has been made in view of the above circumstances. The object of the present invention is to provide a TAC substrate under high temperature and high humidity when a TAC substrate and a glass substrate are laminated via an adhesive layer. It is providing the adhesive composition which can prevent the adhesive film of this from floating from a glass base material.

  The present inventor has conducted extensive research to solve the above problems, and found that the above problems can be solved by combining an acrylic pressure-sensitive adhesive, an isocyanate curing agent, and an acrylic copolymer, The present invention has been completed. Specifically, the present invention provides the following.

  (1) This invention is a composition which comprises the adhesion layer formed on a triacetyl cellulose base material, Comprising: The weight average molecular weight is 400,000-900,000 or less, and the said acrylic adhesive An acrylic curing agent comprising an isocyanate-based curing agent in a solid content conversion of 0.01 to 1.0 parts by mass, a methacrylic acid ester polymer block, and an acrylic acid ester polymer block with respect to 100 parts by mass of the solid content of the agent. A triacetylcellulose pressure-sensitive adhesive composition containing a copolymer and substantially free of an acid component.

  (2) Moreover, this invention is M- of the weight average molecular weights 10,000-300,000 in which the said acrylic copolymer consists of a methyl methacrylate polymer block (M) and a butyl acrylate polymer block (A). The pressure-sensitive adhesive composition for triacetyl cellulose according to (1), which is an AM type triblock copolymer.

  (3) Moreover, this invention is a pressure-sensitive adhesive composition for triacetyl cellulose according to (1) or (2), wherein the isocyanate curing agent is a hexamethylene diisocyanate curing agent.

  (4) Further, in the present invention, the pressure-sensitive adhesive composition for triacetyl cellulose according to any one of claims 1 to 3 is formed on a triacetyl cellulose base material as an adhesive layer, and the pressure-sensitive adhesive layer of the triacetyl cellulose base material An optical film having a hard coat layer and an antireflection layer formed on the opposite surface.

  (5) Moreover, this invention is an optical member by which the said triacetyl cellulose base material and the glass base material are laminated | stacked through the said adhesion layer in the optical film as described in (4).

  According to the pressure-sensitive adhesive composition for triacetyl cellulose of the present invention, when the TAC substrate and the glass substrate are laminated through the pressure-sensitive adhesive layer made of a cured product of the pressure-sensitive adhesive composition, However, the shrinkage stress of the TAC base material can be relieved without using a peroxide, and the adhesive film of the TAC base material can be prevented from floating from the glass base material.

It is a schematic sectional drawing of the optical member which concerns on embodiment of this invention. It is a schematic sectional drawing of the image display apparatus which concerns on embodiment of this invention.

  Hereinafter, specific embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and may be implemented with appropriate modifications within the scope of the object of the present invention. can do.

<Adhesive composition for triacetyl cellulose>
The pressure-sensitive adhesive composition for triacetyl cellulose of the present invention comprises an acrylic pressure-sensitive adhesive as a main agent, an isocyanate-based curing agent, and an acrylic copolymer as essential components. Hereinafter, these components will be described.

[Acrylic adhesive]
First, the acrylic adhesive will be described. It is preferable that the acrylic pressure-sensitive adhesive contains substantially no acid component. When an acid component is contained, deterioration of the conductive thin film in contact with the adhesive layer can be promoted, which is not preferable. Examples of such an acid component include carboxylic acid. On the other hand, the composition containing substantially no acid component includes, for example, an acrylate ester and a hydroxyl group-containing monomer copolymerizable with the acrylate ester, and is obtained by copolymerization of the acrylate ester and the hydroxyl group-containing monomer. An adhesive is used.

  Here, “not containing substantially” means that the content of carboxyl groups in the acrylic polymer is less than 25 ppm. In the present invention, corrosion of the conductive thin film can be effectively prevented by not containing 25 ppm or more of carboxyl groups in the acrylic polymer. In addition, content of the carboxyl group in an acrylic polymer can be measured with a nuclear magnetic resonance apparatus (NMR). Specifically, a carboxyl group and a silylating agent are reacted, and a peak derived from the silylated product is measured by 1H-NMR (600 MHz) (lower limit of quantification: 25 ppm).

  The acrylic polymer has an acrylic ester as a main component. Here, the main component means that the copolymerization ratio is 51% by mass or more, and preferably 65% by mass or more. Examples of the acrylate ester include ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, isononyl acrylate, hydroxylethyl acrylate, propylene glycol acrylate, acrylamide, and glycidyl acrylate. It is done. These can be used alone or in combination of two or more. Among the acrylic acid esters, 2-ethylhexyl acrylate, n-butyl acrylate, and 2-hydroxyethyl acrylate are preferable in terms of excellent durability, transparency, coating suitability, and the like and low cost.

  The copolymerizable hydroxyl group-containing monomer is not particularly limited as long as it has a copolymerizable polymerizable group and a hydroxyl group in its structure. For example, 2-hydroxyethyl acrylate, 2-hydroxyacrylate Examples thereof include hydroxypropyl, 2-hydroxybutyl acrylate, 3-chloro-2-hydroxypropyl acrylate, polyethylene glycol acrylate, and the like.

    The content of the hydroxyl group-containing monomer in the pressure-sensitive adhesive composition is not particularly limited as long as an acrylic ester is a main component, and can be appropriately set so as to exhibit a desired pressure-sensitive adhesive strength. From the viewpoints of adhesiveness, optical properties, etc., the content is preferably 0.1 parts by mass or more and 20 parts by mass or less with respect to the total amount of the acrylate ester contained in the composition. The copolymerization ratio can be measured with a nuclear magnetic resonance apparatus (NMR).

  Moreover, the mass average molecular weight (Mw) of the acrylic polymer is not particularly limited, but is preferably in the range of 400,000 to 900,000 from the viewpoint of durability. When the weight average molecular weight is less than 400,000, the adhesive layer becomes soft and sufficiently follows the shrinkage of the TAC substrate, but cannot withstand internal stress repeated under high-temperature and high-humidity long-term conditions. When the molecular weight exceeds 900,000, the adhesive layer becomes hard, and the difference between the shrinkage amount of the TAC base material and the change amount of the adhesive layer increases, resulting in contraction stress. In each case, the contraction stress of the TAC base material is moderately relaxed. It is not preferable because it cannot be performed. The weight average molecular weight is a value in terms of polystyrene when measured by gel permeation chromatography (GPC).

  Examples of commercially available acrylic polymers include SK Dyne 2971 (manufactured by Soken Chemical), SK Dyne 2975 (manufactured by Soken Chemical), SK Dyne 1811L (manufactured by Soken Chemical), and SK Dyne 2147 (Soken Chemical). SK Dyne 1435 (manufactured by Soken Chemical Co., Ltd.), SK Dyne 1415 (manufactured by Soken Chemical Co., Ltd.), Olivevine EG-655 (manufactured by Toyochem Co., Ltd.) and the like can be suitably used.

[Curing agent]
As the curing agent, an isocyanate curing agent is preferably used because it has good adhesion to the TAC substrate. Examples of the isocyanate curing agent include a polyisocyanate compound, a trimer of a polyisocyanate compound, a urethane prepolymer having a terminal isocyanate group obtained by reacting a polyisocyanate compound and a polyol compound, and 3 of the urethane prepolymer. Examples include a polymer. Examples of the polyisocyanate compound include 2,4-tolylene diisocyanate, 2,5-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, diphenylmethane-4,4′-diisocyanate, 3 -Methyldiphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, dicyclohexylmethane-2,4'-diisocyanate, lysine isocyanate and the like. These can be used alone or in combination of two or more. In the present invention, it is preferable to use a hexamethylene diisocyanate curing agent in terms of excellent stress relaxation property because flexibility can be imparted to the adhesive layer.

  The content of the isocyanate curing agent is preferably 0.01 parts by mass or more and 1.0 parts by mass or less in terms of solid content with respect to 100 parts by mass of solid content of the acrylic pressure-sensitive adhesive, and 0.05 parts by mass The amount is more preferably 0.3 parts by mass or less, and further preferably 0.05 parts by mass or more and 0.2 parts by mass or less. When the blending amount is less than 0.01 parts by mass, the elastic modulus at high temperature is lowered, so that sufficient stress relaxation properties are hardly exhibited and durability may not be obtained. On the other hand, if the content is more than 1.0 parts by mass, the modulus of elasticity increases and it becomes difficult to follow the shrinkage of the TAC substrate at a high temperature, and the adhesive force decreases, so that floating and peeling occur. It is not preferable in that it may be easy to do. If it is 0.01 part by mass or more and 1.0 part by mass or less, an adhesive layer having an appropriate elastic modulus can be formed, and the TAC base material can be relaxed to reduce the shrinkage stress. It can prevent that the adhesive film of a base material floats from a glass base material.

[Acrylic copolymer]
Acrylic copolymer is a triblock copolymer curing system because it improves adhesion to a TAC substrate at high temperatures and improves cohesiveness of the adhesive layer, making it difficult to reduce the elastic modulus at high temperatures. It is preferable to use an agent. The triblock copolymer consists of a methyl methacrylate polymer block (M) and a butyl acrylate polymer block (A), and the proportion of the butyl acrylate polymer block (A) is 70% by mass or more, The weight average molecular weight of the triblock copolymer is 10,000 to 300,000.

  Although it does not specifically limit as a triblock copolymer which satisfy | fills the said weight average molecular weight and the ratio for which a butyl acrylate polymer block (A) accounts, Specifically, for example, LA2330, LA2140, LA4285 (made by Kuraray) , M51, M52, M53, M52N, and M22N (manufactured by Arkema Co., Ltd.) can be suitably used.

  The blending amount of the acrylic copolymer is preferably 0.1 to 10 parts by mass, more preferably 1 to 5 parts by mass in terms of solid content with respect to 100 parts by mass of the solid content of the acrylic pressure-sensitive adhesive. . When the blending amount is less than 0.1 parts by mass, it is not preferable in that the elastic modulus at a high temperature is lowered and sufficient stress relaxation properties are hardly exhibited, and durability may not be obtained. On the other hand, when the content is more than 10 parts by mass, the compatibility with the acrylic pressure-sensitive adhesive is deteriorated, which is not preferable in that the transparency may be lowered. If it is the said range, even if it is a hot and humid condition, it can prevent that the adhesive film of a TAC base material floats from a glass base material.

[Other additives]
Other additives are added as necessary to impart weather resistance, light resistance, heat resistance, moisture resistance, flame resistance, and the like to the pressure-sensitive adhesive composition. In addition, the additive is added as necessary to improve the stability, coating property, drying property, anti-blocking property and the like of the coating solution. As other additives, in particular, in addition to the above-mentioned pressure-sensitive adhesive, curing agent, acrylic copolymer, plasticizer and metal chelating agent, a silane coupling agent is used in combination and added, so that the TAC substrate and the adherend It is possible to further improve the adhesion to the object.

  Examples of the silane coupling agent include amino-based silane coupling agents such as γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, and γ-phenylaminofuropyltrimethoxysilane; ureido-based ureidopropyltriethoxysilane and the like. Silane coupling agents; vinyl silane coupling agents such as vinylethoxysilane, vinylmethoxysilane, vinyltris (β-methoxyethoxy) silane; methacrylates such as γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane Silane coupling agent; epoxy-based silane coupling agent such as γ-glycidoxypropyltrimethoxysilane; isocyanate-based silane coupling such as γ-isocyanatopropyltriethoxysilane Agent; Polymer type silane coupling agent such as polyethoxydimethylsiloxane and polyethoxydimethylsiloxane; Cationic silane coupling agent such as N- (N-benzyl-β-aminoethyl) -γ-aminopropyltrimethoxysilane hydrochloride Etc.

  Moreover, you may add a dispersing agent, an antifoamer, a light stabilizer, a ultraviolet absorber, a heat stabilizer, antioxidant. These can use a well-known thing without a restriction | limiting in particular, According to the performance calculated | required by a coating liquid or an adhesive composition, it selects suitably.

<Triacetyl cellulose laminate>
The triacetyl cellulose laminate of the present invention is formed by forming the above-mentioned pressure-sensitive adhesive composition for triacetyl cellulose on a triacetyl cellulose substrate as an adhesive layer.

[Triacetyl cellulose base material]
Triacetyl cellulose (TAC) is preferable as a base material of an optical film in terms of excellent incombustibility, transparency, surface appearance, and electrical insulation. TAC has the property of shrinking in a moist heat environment, but when the adhesive layer has a certain thickness and elasticity, it reduces the shrinkage stress of the TAC substrate, and the adhesive film of the TAC substrate floats from the glass substrate. Can be prevented.

  The thickness of the TAC substrate is not particularly limited and can be appropriately selected depending on the application. Usually, it is 50 μm or more and 150 μm or less, preferably 50 μm or more and 100 μm or less. If the thickness is less than the above range, the mechanical strength may be insufficient, and breakage may occur due to warpage under wet heat conditions. If the thickness is more than the above range, excessive performance may increase the cost.

  The method for forming the TAC substrate is not particularly limited, and for example, a conventionally known film forming method such as a solution casting method, a melt extrusion method, or a calendar method can be used. Moreover, you may use the commercially available base material previously formed into a film form by the said method.

  In addition, you may perform well-known easy-adhesion processes, such as a corona discharge process, a plasma process, an ozone process, a flame process, a primer process, a preheating process, a dust removal process, a vapor deposition process, an alkali process, to a base material.

[Adhesive layer]
The thickness of the pressure-sensitive adhesive layer is usually 5 μm or more and 100 μm or less, preferably 10 μm or more and 50 μm or less. If the thickness is less than 5 μm, most of the adhesive layer follows the shrinkage of TAC, and the shrinkage stress of the TAC substrate cannot be relaxed. If it exceeds 100 μm, there is no problem with the stress relaxation property, but it may adversely affect optical properties such as light transmittance, which is not preferable.

  Regarding the viscosity of the adhesive layer, the loss tangent at 60 ° C. of the adhesive layer (hereinafter also referred to as “tan δ (60 ° C.)”) is 0.35 or more and less than 1.0, and the loss of the adhesive layer at 80 ° C. The tangent (hereinafter also referred to as “tan δ (80 ° C.)”) is preferably 0.40 or more and less than 1.0. tan δ is one of the parameters that reflect the viscosity of the adhesive layer and show the stress relaxation behavior (deformation delay when force is applied). For example, tan δ is a dynamic viscoelasticity measurement method (attachment mode: compression mode, frequency) based on JIS K7244-1 using a solid viscoelasticity analyzer RSA-III manufactured by TA Instruments as a measuring device. 1 Hz, temperature: −50 to 150 ° C., temperature rise temperature: 5 ° C./min). The present invention prevents the adhesive film of the TAC base material from floating from the glass base material even under high temperature and high humidity, and further prevents the end portion of the film from being slightly peeled off from the glass base material. Therefore, the loss tangent tan δ at high temperatures (60 ° C. and 80 ° C.) was used as an index. If the value of tan δ is lower than the above range, it is preferable in that the fluidity of the pressure-sensitive adhesive is low and it becomes difficult to follow the shrinkage of the TAC substrate at a high temperature, so that the float or peeling may easily occur. Absent. If the value of tan δ is higher than the above range, it is not preferable in that the fluidity of the pressure-sensitive adhesive is high, the cohesiveness of the pressure-sensitive adhesive layer is lowered, and durability may not be obtained.

[Method for producing TAC laminate]
The manufacturing method of the TAC laminated body of this invention is not specifically limited, A conventionally well-known method can be used. As an example, it can be manufactured by laminating a TAC substrate on the surface on which the pressure-sensitive adhesive layer is formed on the release film after the entire surface of the pressure-sensitive adhesive composition is applied and dried by an applicator.

<Optical film>
In addition to window glass, liquid crystal display, plasma display, CRT display, organic EL display by further forming a hard coat layer, antireflection layer, etc. on the surface of the TAC laminate that is opposite to the adhesive layer of the TAC substrate In various image display devices such as field emission displays, it can be suitably used as an optical film used for the purpose of antireflection, surface protection, antiglare and the like. The hard coat layer can be formed by a method of adding a cured film made of an acrylic UV curable resin to the surface of the TAC substrate. The antireflection layer can be formed by attaching fine particles such as silica.

<Optical member>
The optical film of this invention can be conveniently used as an optical member used in various image display apparatuses, such as a liquid crystal display, by sticking a glass base material through the said adhesion layer. In FIG. 1, an example of a structure of the optical member of this invention is shown. In the optical member 1, a hard coat layer 14 and an antireflection layer 15 are sequentially laminated on one surface of the TAC substrate 11, and an adhesive layer 12 is formed on the other surface. The glass base material 13 is stuck through. Although it does not specifically limit as a method of sticking the glass base material 13, Usually, a crimping | compression-bonding system is used. The glass substrate 13 tends to be thinned to about 0.5 mm in recent years, and the adhesive layer of the present invention is suitably used when the thickness of the glass substrate 13 is 0.1 mm to 0.7 mm.

  Moreover, the thickness of the adhesion layer 12 may be as thin as about 10 micrometers. Even if the optical member of the present invention is used for a long time under wet heat conditions, the optical member of the present invention is less likely to float from the glass substrate and maintains stable optical characteristics. It is characterized by. Therefore, the optical member of the present invention can be suitably used as a thin optical member. Moreover, since the pressure-sensitive adhesive composition does not contain a peroxide, the residual peroxide may cause a cross-linking reaction to progress over time, and the physical properties of the pressure-sensitive adhesive may change. There is no possibility that the pressure-sensitive adhesive is deteriorated by the influence of radicals generated by the decomposition.

<Image display device>
FIG. 2 shows an example when the optical member 1 is used in an image display device 2 equipped with a touch panel. The optical member 1 of the present invention is an image display device such as a liquid crystal display or a mobile display equipped with a touch panel, as long as the TAC base material 11 and the glass base material 13 are attached, such as a window display or a car meter. Although it can be used in a wide variety of applications, it uses a pressure-sensitive adhesive composition for triacetyl cellulose that does not substantially contain an acid component, and can effectively prevent corrosion of a conductive thin film. It is more preferable to use it for a display device.

<Image display device>
The optical member 1 can be used in various image display devices such as a mobile display equipped with a touch panel. FIG. 2 shows an example of the configuration of the image display device 2 in this case. A transparent substrate 21 made of a thin film substrate 21a such as glass is provided on the outermost surface of the image display device, and printing for decorating the periphery of the transparent substrate 21 is provided on the periphery of the back surface of the transparent substrate 21. An ink layer 21b is formed. A second adhesive layer 22 is formed on the back surface of the transparent substrate 21, and a transparent conductive substrate 23 having a conductive thin film such as ITO formed on the surface is formed through the second adhesive layer 22. ing. The composition of the adhesive layer 22 may be different from or the same as the composition of the adhesive layer 12. The transparent conductive substrate 23 corresponds to a sensor in the X-axis direction.

  On the surface of the transparent conductive base material 23 opposite to the adhesive layer 22, the optical film 1 is laminated in the order of the glass base material 13, the adhesive layer 12, the TAC base material 11, the hard coat layer 14 and the antireflection layer 15. ing. In FIG. 2, a second transparent conductive substrate 24 is formed on the glass substrate 13 on the adhesive layer 12 side. The second transparent conductive substrate 24 corresponds to a sensor in the Y-axis direction.

  An air gap layer 25 and a liquid crystal display layer 26 are sequentially laminated on the surface of the antireflection layer 15 opposite to the hard coat layer 14. The air gap layer 25 is an air layer and is provided to protect the liquid crystal display layer 26 from external impacts.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to a following example.

<Example 1>
100 parts by mass of acrylic pressure-sensitive adhesive A (trade name “SK2975”, weight average molecular weight: 400,000, solid content: 42%, manufactured by Soken Chemical Co., Ltd.) and isocyanate-based curing agent A (trade name “Y-75”, hexa Methylene diisocyanate-based curing agent, solid content: 75%, manufactured by Soken Chemical Co., Ltd. 0.1 parts by mass, acrylic copolymer (trade name “LA2330”, solid content: 100%, methyl methacrylate polymer block (M) And a butyl acrylate polymer block (A) having a weight average molecular weight of 160,000 MAM type triblock copolymer (manufactured by Kuraray Co., Ltd.) is dissolved in toluene to give a solid content of 40%. 2.625 parts by mass of the acrylic copolymer solution prepared as described above and 0.25 parts by mass of a silane coupling agent (trade name “A50”, solid content: 50%, manufactured by Soken Chemical Co., Ltd.) A mixed solvent of ethyl ketone was (trade name:: KT-11, weight ratio 1 1, DIC Graphics Co., Ltd.) was dissolved in 25 parts by weight to obtain an adhesive composition.

  The optical film of Example 1 was produced using this adhesive composition. The optical film was prepared using AR5.5 (manufactured by Sony Chemical & Information Device) based on TAC. In the configuration of AR5.5, similarly to the optical member 1 shown in FIG. 1, a hard coat layer 14 and an antireflection layer 15 are sequentially laminated on one surface of the TAC substrate 11. Using the applicator, the pressure-sensitive adhesive composition has a pressure-sensitive adhesive layer thickness of 12 μm after being dried on a PET film (Toray Film Processing Co., Ltd. Therapy BX9A (RX) PET 38 μm) under a drying condition of 92 ° C. for 2 minutes. The surface opposite to the surface on which the antireflection layer 15 of AR5.5 is formed is laminated on the surface of the release film on which the adhesive layer is formed, and the optical surface of Example 1 is laminated. A film was prepared. The thickness of the antireflection layer is 0.1 μm, the thickness of the hard coat layer is 10 μm, and the thickness of the TAC substrate is 80 μm.

  Moreover, the optical member of Example 1 was produced using the optical film of Example 1. In the production of the optical member, a glass substrate (product name “Gorilla Glass # 1737”, thickness: 0.7 mm, manufactured by Corning) was used. Of the surfaces of the optical film of Example 1, the surface on which the adhesive layer was formed was laminated to the glass substrate. Thus, the optical member of Example 1 was produced.

<Example 2>
Instead of the acrylic adhesive A, 100 parts by mass of the acrylic adhesive B (trade name “N7520”, weight average molecular weight: 700,000, solid content: 35%, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) is used. In place of the curing agent A, 0.025 parts by mass of an isocyanate curing agent B (trade name “Coronate HX”, hexamethylene diisocyanate curing agent, solid content: 100%, manufactured by Nippon Polyurethane Industry Co., Ltd.) was used. The optical film and optical member of Example 2 were the same as Example 1 except that the amount of the combined solution was 2.19 parts by mass and the amount of the silane coupling agent was 0.2 parts by mass. Got.

<Comparative Example 1>
100 parts by mass of the acrylic adhesive B is used in place of the acrylic adhesive A, and an isocyanate curing agent C (trade name “Coronate L-55E”, tolylene diisocyanate curing is used in place of the isocyanate curing agent A. Agent, solid content: 55%, manufactured by Nippon Polyurethane Industry Co., Ltd.), and the same method as in Example 1 except that the acrylic copolymer solution and the silane coupling agent were not used. Thus, an optical film and an optical member of Comparative Example 1 were obtained.

<Comparative example 2>
Instead of the acrylic pressure-sensitive adhesive A, 100 parts by weight of the acrylic pressure-sensitive adhesive C (trade name “EG-655”, weight average molecular weight: 1 million, solid content: 23.5%, manufactured by Toyochem Co., Ltd.) is used. In place of the acrylic curing agent A, 0.02 parts by mass of the isocyanate curing agent D (trade name “BXX5627”, m-xylylene diisocyanate curing agent, solid content: 50%, manufactured by Toyochem Co., Ltd.) was used. The optical film and optical member of Comparative Example 2 were obtained in the same manner as in Example 1 except that the combined solution and the silane coupling agent were not used.

<Comparative Example 3>
In place of the acrylic pressure-sensitive adhesive A, 100 parts by weight of the acrylic pressure-sensitive adhesive D (trade name “SK1811L”, weight average molecular weight: 600,000, solid content: 23%, manufactured by Soken Chemical Co., Ltd.) is used. In place of A, 0.4 parts by mass of isocyanate-based curing agent E (trade name “TD-75”, m-xylylene diisocyanate-based curing agent, solid content: 75%, manufactured by Soken Chemical Co., Ltd.) is used, and the above silane coupling is used. An optical film and an optical member of Comparative Example 3 were obtained in the same manner as in Example 1 except that 0.09 parts by mass of the agent was used and the above acrylic copolymer solution was not used.

<Examination of stress relaxation characteristics>
By performing the following tests, the stress relaxation characteristics of the TAC laminate of the present invention were verified from the viscoelasticity side of the adhesive layer.

  Using the optical film of each Example / Comparative Example, the loss tangent tan δ at the first high temperature state (60 ° C.) and the second high temperature state (80 ° C.) for the adhesive layer of each Example / Comparative Example The loss tangent tan δ was measured. The loss tangent tan δ is measured using a dynamic viscoelasticity measurement method (attachment mode: compression mode, frequency: 1 Hz) according to JIS K7244-1 using a solid viscoelasticity analyzer RSA-III manufactured by TA Instruments. (Temperature: -50 to 150 degrees, temperature increase rate: 5 degrees / minute). Table 2 shows the measurement results. As for tan δ (60 ° C.), the case where it is 0.35 or more and less than 1.0 is “◯”, and the case where it is not so is “×”. As for tan δ (80 ° C.), the case where it is 0.40 or more and less than 1.0 is “◯”, and the case where it is not so is “×”.

<Evaluation of durability test>
The optical member of each Example / Comparative Example was stored for 500 hours under conditions of high temperature and high humidity (60 ° C., 90% RH), and then whether or not the adhesive film of the TAC base material floated from the glass base material was visually observed. It was measured. The evaluation criteria are as follows.
○: Lifting or peeling occurred.
X: No lifting or peeling occurred.
Table 2 shows the measurement results.

  The pressure-sensitive adhesive layer contains an acrylic pressure-sensitive adhesive, an isocyanate-based curing agent, and an acrylic copolymer, tan δ (60 ° C.) is 0.35 or more and less than 1.0, and tan δ (80 ° C.) is 0.40. The optical member using the TAC laminate of less than 1.0 can appropriately relieve the shrinkage stress of the TAC base material even though the thickness of the adhesive layer is as extremely small as 12 μm. It was confirmed that the adhesive film can be prevented from floating from the glass substrate (Examples 1 and 2). In addition, since the adhesive layer does not substantially contain an acid component, deterioration of the conductive thin film can be prevented even when the conductive thin film is in contact with the adhesive layer.

  On the other hand, when the adhesive layer does not contain an acrylic copolymer, the value of tan δ is lower than the above range, and as a result, it becomes difficult to follow the shrinkage of the TAC substrate at a high temperature, so that floating and peeling are likely to occur. It was confirmed (Comparative Examples 1-3).

  Further, when the weight average molecular weight of the acrylic pressure-sensitive adhesive exceeds 900,000, the pressure-sensitive adhesive layer becomes hard, and the difference between the amount of shrinkage of the TAC base material and the amount of change of the pressure-sensitive adhesive layer increases, resulting in shrinkage stress. It was confirmed that the shrinkage stress could not be moderately relaxed (Comparative Example 2).

  Moreover, when the addition amount of the isocyanate-based curing agent exceeds 0.5 parts by mass in terms of solid content with respect to 100 parts by mass of the solid content of the acrylic pressure-sensitive adhesive, the elastic modulus at high temperature becomes high, and the glass group at high temperature It became difficult to follow the shrinkage of the material, and the adhesive strength was reduced, and it was confirmed that floating and peeling could occur (Comparative Example 3).

DESCRIPTION OF SYMBOLS 1 Optical member 11 TAC base material 12 Adhesive layer 13 Glass base material 14 Hard-coat layer 15 Antireflection layer

Claims (5)

A composition constituting an adhesive layer formed on a triacetylcellulose substrate,
An acrylic pressure-sensitive adhesive having a weight average molecular weight of 400,000 or more and 900,000 or less,
0.01 mass part or more and 1.0 mass part or less isocyanate curing agent in terms of solid content with respect to 100 mass parts of solid content of the acrylic pressure-sensitive adhesive,
An acrylic copolymer comprising a methacrylate polymer block and an acrylic ester polymer block;
Containing
A pressure-sensitive adhesive composition for triacetyl cellulose which does not substantially contain an acid component.   The acrylic copolymer is a MAM type triblock copolymer having a weight average molecular weight of 10,000 to 300,000 consisting of a methyl methacrylate polymer block (M) and a butyl acrylate polymer block (A). The pressure-sensitive adhesive composition for triacetyl cellulose according to claim 1, which is a coalescence.   The pressure-sensitive adhesive composition for triacetyl cellulose according to claim 1 or 2, wherein the isocyanate curing agent is a hexamethylene diisocyanate curing agent.   The pressure-sensitive adhesive composition for triacetyl cellulose according to any one of claims 1 to 3 is formed on a triacetyl cellulose substrate as an adhesive layer, and a hard coat is formed on the surface of the triacetyl cellulose substrate opposite to the adhesive layer. An optical film having a layer and an antireflection layer formed thereon.   The optical member by which the said triacetyl cellulose base material and the glass base material are laminated | stacked through the said adhesion layer in the optical film of Claim 4.

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