JP2013212657A - Triacetylcellulose laminate, optical film using the same, and optical member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate capable of reducing the shrinkage stress of a triacetylcellulose base material without using any peroxide even under high temperature and high humidity environments when the triacetylcellulose base material and a polarizing plate are layered together through an adhesive layer and a glass base material is further layered on the surface of the polarizing plate for preventing an adhesive film of a TAC (triacetylcellulose) base material from separating from an adherend.SOLUTION: In a laminate, an adhesive layer 12 is formed on a triacetylcellulose base material 11. The adhesive layer 12 includes an acrylic adhesive and an isocyanate curing agent or an epoxy curing agent. A difference E'(20°C)-E'(60°C) between a storage elastic modulus E' at 60°C and that at 20°C of the adhesive layer 12 is not lower than 2.0×10and not higher than 6.0×10.

Description

  The present invention relates to an optical member used in an image display device such as a liquid crystal display, and more specifically, when a triacetyl cellulose (hereinafter also referred to as “TAC”) substrate and an adherend are laminated via an adhesive layer. Furthermore, it is related with the laminated body which can prevent the adhesion film of a TAC base material from floating to a to-be-adhered body even under high temperature and humidity.

  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 the polarizing plate. If necessary, the hard coat layer for imparting scratch resistance to the surface and the anti-reflection function while maintaining the scratch resistance make it easy to view the liquid crystal screen. There is also a type in which an antireflection layer or the like that contributes to the improvement of the thickness is formed.

  The TAC film is laminated with a polarizing plate or a glass substrate via an adhesive layer and used as an optical member. However, since TAC generally has a property of shrinking under wet heat conditions, there is a problem that the adhesive film of the TAC base material floats from the adherend under high temperature and high humidity.

  In order to solve this problem, for example, Patent Document 1 includes a peroxide in addition to an acrylic pressure-sensitive adhesive and an isocyanate-based curing agent, so that a crosslinking reaction by the peroxide is used in combination, and sufficient stress is obtained. It is disclosed to maintain relaxation.

In Patent Document 2, 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 3.2 × 10 ^{4 to} 7.0 × 10 ⁴ Pa. And a step of heat-treating the layer made of the pressure-sensitive adhesive composition so that the storage elastic modulus (G ′) at 80 ° C. is 2.0 × 10 ^{4 to} 4.5 × 10 ⁴ Pa. A method for manufacturing the layer 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 maintaining a sufficient stress relaxation property by using a crosslinking reaction with the peroxide. is there.

  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, and its object is to laminate a TAC substrate and an adherend via an adhesive layer, even under high temperature and high humidity, It is providing the laminated body which can prevent the adhesion film of a TAC base material from floating to a to-be-adhered body.

  The present inventor has made extensive studies to solve the above problems, and found that the above problems can be solved by combining an acrylic pressure-sensitive adhesive with an isocyanate curing agent or an epoxy curing agent. It came to complete. Specifically, the present invention provides the following.

(1) The present invention is a laminate in which an adhesive layer is formed on a triacetyl cellulose base material, and the adhesive layer contains an acrylic adhesive and an isocyanate curing agent or an epoxy curing agent, E ′ (20 ° C.) − E ′ (60 ° C.), which is the difference between the storage elastic modulus E ′ at 60 ° C. and the storage elastic modulus E ′ at 20 ° C. of the adhesive layer, is 2.0 × 10 ⁵ or more. 0 × 10 ⁵ or less.

  (2) Moreover, this invention is an optical film by which the hard-coat layer and the antireflection layer were formed in the surface on the opposite side to the said adhesion layer of the said triacetylcellulose base material in the laminated body as described in (1). .

  (3) Moreover, this invention is an optical member by which the said triacetyl cellulose base material and a polarizing plate are laminated | stacked through the said adhesion layer in the optical film as described in (2).

  According to the laminate of the present invention, when the TAC substrate and the adherend are laminated through the adhesive layer, the shrinkage of the TAC substrate is achieved without using peroxide even under high temperature and high humidity. The stress can be suppressed, and the TAC-based adhesive film can be prevented from floating from the adherend.

It is sectional drawing of the optical member which shows typically the structure of the optical member 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.

<Triacetyl cellulose laminate>
In the triacetylcellulose laminate of the present invention, an adhesive layer is formed on a triacetylcellulose substrate, and this adhesive layer comprises an acrylic adhesive as a main ingredient and an isocyanate curing agent or an epoxy curing agent as essential components. To do. Hereinafter, these components will be described.

[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 humid heat environment, but when the adhesive layer has a certain thickness and elasticity, it suppresses the shrinkage stress of the TAC substrate, and the adhesive film of the TAC substrate floats from the adherend. 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.

[Acrylic adhesive]
Then, an acrylic adhesive is demonstrated. A preferable acrylic pressure-sensitive adhesive includes, for example, an acrylate copolymer obtained by copolymerizing an acrylate ester with another monomer. Examples of the acrylate ester include ethyl acrylate, acrylate-n-butyl, acrylate-2-ethylhexyl, isooctyl acrylate, isononyl acrylate, hydroxylethyl acrylate, propylene glycol acrylate, acrylamide, glycidyl acrylate, and the like. Is mentioned. These can be used alone or in combination of two or more. In the present invention, among the acrylate esters, acrylate-n-butyl and acrylate-2-ethylhexyl are preferable in terms of excellent heat resistance, moist heat resistance, durability, and transparency. In the present invention, among the other monomers, (meth) acrylic acid-n-butyl is preferable.

  The weight average molecular weight (Mw) of the acrylate copolymer used as the acrylic pressure-sensitive adhesive is preferably in the range of 400,000 to 1,000,000. 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 1,000,000, the adhesive layer becomes hard, the adherend interface becomes unstable, and in any case, the shrinkage of the TAC base material cannot be suppressed. The weight average molecular weight is a value in terms of polystyrene when measured by gel permeation chromatography (GPC).

  Furthermore, the crosslinking group in the acrylate copolymer is preferably a carboxyl group. Examples of the monomer containing a carboxyl group include acrylic acid, methacrylic acid, β-carboxyethyl acrylate, itaconic acid, crotonic acid, maleic acid, maleic anhydride, butyl maleate and the like. These can be used alone or in combination of two or more. When a monomer containing a carboxyl group is used, the cohesiveness of the pressure-sensitive adhesive is improved, so that the shrinkage of the TAC base material can be suppressed, and as a result, the adhesive film of the TAC base material is prevented from floating or peeling off from the polarizing plate. it can.

  In addition, as a commercial item of the said acrylic adhesive, SK dyne 2950 (made by Soken Chemical Co., Ltd.) etc. can be used suitably, for example. Here, SK Dyne 2950 is an acrylic pressure-sensitive adhesive having acrylic acid-n-butyl as a main monomer.

[Curing agent]
In the said adhesion layer, it is preferable to use an isocyanate hardening agent or an epoxy-type hardening | curing agent as a hardening | curing agent from the reason that the adhesiveness to a TAC base material is favorable.

  As an isocyanate curing agent, for example, 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 amounts of the urethane prepolymer Examples include the body. 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.

  Examples of the epoxy curing agent include sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, glycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, neopentyl glycol diglycidyl ether, Examples thereof include polyfunctional epoxy compounds such as 1,6-hexanediol diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and polybutadiene diglycidyl ether.

  The content of the isocyanate curing agent or epoxy curing agent in the adhesive layer is preferably 0.1 parts by mass or more and 3.0 parts by mass or less in terms of solid content with respect to 100 parts by mass of the acrylic adhesive. More preferably, it is 0.2 parts by mass or more and 1.0 part by mass or less. If the blending amount is less than 0.1 parts by mass, the elastic modulus at high temperature decreases, which is not preferable in that durability may not be obtained. On the other hand, when the blending amount is more than 3.0 parts by mass, the elastic modulus is increased and the adherend interface becomes unstable, which is not preferable in that the floatation or peeling may easily occur. If it is the said range, the adhesion layer which has moderate elasticity modulus can be formed, the shrinkage | contraction of a TAC base material is suppressed, and the adhesive film of a TAC base material floats from a to-be-adhered body even under high temperature and humidity. Can be prevented.

  In addition, as a commercial item of the said epoxy-type crosslinking agent, E-5C (made by Soken Chemical Co., Ltd.) can be used suitably, for example, as a commercial item of the said isocyanate type hardening | curing agent, it is L-45 (Soken). Chemical Co., Ltd.) and K-130 (Syden Chemical Co., Ltd.) can be preferably used.

[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 adhesive layer. 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, a plasticizer, a silane coupling agent, a dispersant, an antifoaming agent, a light stabilizer, an ultraviolet absorber, a heat stabilizer, an antioxidant and the like may be added. 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 adhesion layer, it selects suitably.

[Adhesive layer]
The thickness of the adhesive layer is usually 5 μm or more and 100 μm or less, preferably 15 μm or more and 40 μm or less. If the thickness is less than 5 μm, most of the adhesive layer follows the shrinkage of the TAC, and the shrinkage stress of the TAC base material cannot be suppressed. If the thickness exceeds 100 μm, there is no problem with the stress suppression property, but it may adversely affect optical properties such as light transmittance, which is not preferable.

Regarding the elasticity of the adhesive layer, E ′ (20 ° C.) − E ′ (60 ° C.), which is the difference between the storage elastic modulus E ′ at 60 ° C. and the storage elastic modulus E ′ at 20 ° C. of the adhesive layer, is 2. It is preferably 0 × 10 ⁵ or more and 6.0 × 10 ⁵ or less, more preferably 2.1 × 10 ⁵ or more and 3.5 × 10 ⁵ or less. The storage elastic modulus E ′ is one of the dynamic mechanical properties, and applies a strain or stress that changes (vibrates) over time to the sample, and detects the stress or strain generated thereby, thereby determining the mechanical properties of the sample. Of the values obtained by the method of measuring the value, the value stored inside the sample. The present invention prevents the adhesive film of the TAC base material from floating from the adherend even under high temperature and high humidity, and further prevents the end portion of the film from peeling off from the adherend even slightly. Therefore, the difference between the storage elastic modulus E ′ at high temperature (60 ° C.) and the storage elastic modulus E ′ at room temperature (20 ° C.) was used as an index. If the difference in storage elastic modulus E ′ is less than 2.0 × 10 ⁵ , the change in the hardness of the adhesive layer due to temperature rise is small, and the adhesive film of the TAC substrate may float from the adherend under high temperature and high humidity. This is not preferable. If the difference in storage elastic modulus E ′ is larger than 6.0 × 10 ⁵ , the change in the hardness of the adhesive layer due to temperature rise is too large. In this case as well, the adhesive film of the TAC substrate is adhered under high temperature and high humidity. It is not preferable in that it may float from the body.

Further, E ′ (20 ° C.) is preferably 4.5 × 10 ⁵ Pa or more and 8.0 × 10 ⁵ Pa or less. When E ′ (20 ° C.) is less than 4.5 × 10 ⁵ Pa, the pressure-sensitive adhesive layer is soft, and TAC shrinkage is not suppressed, so that it is not preferable in terms of easy floating and peeling. On the other hand, when E ′ (20 ° C.) is larger than 8.0 × 10 ⁵ Pa, the adhesive layer becomes hard and the adherend interface becomes unstable, which is not preferable in terms of easy floating and peeling. .

[Method for producing TAC laminate]
The method for producing the TAC laminate of the present invention is not particularly limited except for the preparation of the pressure-sensitive adhesive composition, and a conventionally 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>
By further forming a hard coat layer, an antireflection layer, etc. on the surface of the TAC laminate opposite to the adhesive layer of the TAC substrate, such as a liquid crystal display, plasma display, CRT display, EL display, field emission display, etc. In various image display devices, 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>
FIG. 1 shows an example of the configuration of the optical member 1 of the present invention. In the optical member 1 of the present invention, the TAC base material 11 and the polarizing plate 13 are bonded to each other on the one surface of the TAC base material 11 via the adhesive layer 12 and the polarizing plate is provided via the second adhesive layer 14. 13 and the glass base material 15 are stuck. Further, on the other surface of the TAC substrate 11, a hard coat layer 16 and an antireflection layer 17 are sequentially laminated. The pressure-sensitive adhesive layer made of the pressure-sensitive adhesive composition for TAC of the present invention corresponds to the pressure-sensitive adhesive layer 12 in FIG. A method for adhering the TAC substrate 11 and the polarizing plate 13 through the adhesive layer 12 is not particularly limited, but a pressure bonding method is usually used. In addition, the glass base material 15 tends to be thinned to about 0.5 mm in recent years, and the adhesive layer 12 of the present invention is suitably used when the thickness of the glass base material 15 is 0.1 mm to 0.7 mm. .

  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 an acrylic pressure-sensitive adhesive (trade name “SK2950”, acrylic acid-n-butyl pressure-sensitive adhesive, weight average molecular weight: 500,000, solid content: 36.5%, manufactured by Soken Chemical Co., Ltd.) and an epoxy curing agent (Trade name “E-5C”, epoxy curing agent, solid content: 5%, manufactured by Soken Chemical Co., Ltd.) 2.94 parts by mass with a mixed solvent of toluene and methyl ethyl ketone (trade name: KT-11, mass ratio 1: 1, manufactured by DIC Graphics Co., Ltd.) was dissolved in 25 parts by mass to obtain an adhesive composition.

A laminate of Example 1 was prepared using this pressure-sensitive adhesive composition. The laminate was produced using AR5.5 (Sony Chemical & Information Device), which is a commercially available optical film based on TAC. The configuration of AR5.5 is obtained by sequentially laminating a hard coat layer 16 and an antireflection layer 17 on one surface of the TAC substrate 11 as in the optical member 1 shown in FIG. Using the applicator, the pressure-sensitive adhesive composition has a pressure-sensitive adhesive layer thickness of 25 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 of the release film on which the pressure-sensitive adhesive layer is formed is laminated on the surface opposite to the surface on which the antireflection layer 17 of AR5.5 is formed. The body was made. 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 laminated body of Example 1. In the production of the optical member, a polarizing plate (product name “F1205DU”, manufactured by Nitto Denko Corporation) on which a second adhesive layer different from the above adhesive layer is formed, and a glass substrate (product name “Gorilla Glass # 1737”). , Thickness: 0.7 mm, manufactured by Corning). Among the surfaces of the laminate of Example 1, the surface on which the adhesive layer is formed is the surface opposite to the surface on which the second adhesive layer is formed among the surfaces of the polarizing plate. Laminated. Subsequently, the surface of the polarizing plate on which the second adhesive layer was formed was laminated on a glass substrate. Thus, the optical member of Example 1 was produced.

<Example 2>
100 parts by mass of the acrylic pressure-sensitive adhesive and 1.95 parts by mass of the epoxy curing agent are dissolved in toluene, and the plasticizer A (trade name “BXX5463”, a plasticizer containing an aliphatic polybasic acid ester, 1.83 parts by mass of solid content: 100%, manufactured by Toyochem Co., Ltd. was dissolved in 25 parts by mass of a mixed solvent of toluene and methyl ethyl ketone (trade name: KT-11, mass ratio 1: 1, manufactured by DIC Graphics). A laminate and an optical member of Example 2 were obtained in the same manner as in Example 1 except that the pressure-sensitive adhesive composition was obtained.

<Example 3>
100 parts by mass of the acrylic pressure-sensitive adhesive, and isocyanate curing agent (trade name “L-45”, tolylene diisocyanate curing agent, solid content: 45%, manufactured by Soken Chemical Co., Ltd.) instead of the epoxy curing agent 0 , Except that 324 parts by mass was dissolved in 25 parts by mass of a mixed solvent of toluene and methyl ethyl ketone (trade name: KT-11, mass ratio 1: 1, manufactured by DIC Graphics), to obtain a pressure-sensitive adhesive composition. In the same manner as in Example 1, the laminate and optical member of Example 3 were obtained.

<Example 4>
100 parts by mass of the acrylic pressure-sensitive adhesive and 0.18 parts by mass of an isocyanate curing agent (trade name “K-130”, hexamethylene diisocyanate curing agent, solid content: 80%, made by Seiden Chemical Co., Ltd.) And a mixed solvent of methyl ethyl ketone (trade name: KT-11, mass ratio 1: 1, manufactured by DIC Graphics) and dissolved in 25 parts by mass to obtain a pressure-sensitive adhesive composition. Thus, a laminate and an optical member of Example 4 were obtained.

<Comparative Example 1>
Instead of the acrylic pressure-sensitive adhesive “SK2950”, an acrylic pressure-sensitive adhesive (trade name “OC3949”, acrylic acid-n-butyl pressure-sensitive adhesive, weight average molecular weight: 1,200,000, solid content: 19.5%, Syden Chemical Co., Ltd. 100 parts by mass), and 1.60 parts by mass of the above epoxy curing agent, and a new silane coupling agent (trade name “S-1”, solid content: 6.3%, Syden The laminated body and optical member of the comparative example 1 were obtained by the method similar to Example 1 except having added 1 mass part).

<Comparative example 2>
Using 100 parts by mass of the above-mentioned acrylic pressure-sensitive adhesive (trade name “OC3949”, acrylic acid-n-butyl-based pressure-sensitive adhesive, weight average molecular weight: 1,200,000, solid content: 19.5%, manufactured by Seiden Chemical Co., Ltd.) In addition to using 0.1 parts by mass of an isocyanate curing agent (trade name “K-130”, hexamethylene diisocyanate curing agent, solid content: 80%, manufactured by Seiden Chemical Co., Ltd.) instead of an epoxy curing agent, A comparative example was carried out in the same manner as in Example 1 except that 1 part by mass of a silane coupling agent (trade name “S-1”, solid content: 6.3%, manufactured by Seiden Chemical Co., Ltd.) was newly added. 2 laminates and an optical member were obtained.

<Comparative Example 3>
Instead of the acrylic adhesive “SK2950”, an acrylic adhesive (trade name “EG-655”, acrylic acid-n-butyl adhesive, weight average molecular weight: 1 million, solid content: 23.5%, 100 parts by mass of Toyochem Co.) is used, and an isocyanate curing agent (trade name “BXX5627”, xylylene diisocyanate curing agent, solid content: 50%, manufactured by Toyochem Co., Ltd.) 0.02 mass instead of the epoxy curing agent. The laminated body and optical member of the comparative example 3 were obtained by the method similar to Example 1 except having used the part.

<Comparative example 4>
Acrylic adhesive (trade name “SK1811L”, acrylic acid-n-butyl adhesive, weight average molecular weight: 600,000, solid content: 23%, manufactured by Soken Chemical Co., Ltd.) instead of the acrylic adhesive “SK2950” Using 100 parts by mass, instead of the epoxy curing agent, an isocyanate curing agent (trade name “TD-75”, xylylene diisocyanate curing agent, solid content: 75%, manufactured by Soken Chemical Co., Ltd.) 0.4 parts by mass In addition to the addition of 0.09 parts by mass of a silane coupling agent (trade name “A-50”, solid content: 50%, manufactured by Soken Chemical Co., Ltd.) By the method, the laminate and the optical member of Comparative Example 4 were obtained.

<Comparative Example 5>
Acrylic adhesive (trade name “SK2403”, acrylic acid-n-butyl adhesive, weight average molecular weight: 500,000, solid content: 29.3%, instead of acrylic adhesive “SK2950”, Soken Chemical Co., Ltd. 100 parts by mass, instead of the epoxy curing agent, an isocyanate curing agent (trade name “L-45”, tolylene diisocyanate curing agent, solid content: 45%, manufactured by Soken Chemical Co., Ltd.) 7.7 A laminate and an optical member of Comparative Example 5 were obtained in the same manner as in Example 1 except that the parts by mass were used.

<Comparative Example 6>
In addition to using 100 parts by mass of the acrylic adhesive “SK2403” and 7.7 parts by mass of the isocyanate curing agent “L-45”, a new plasticizer B (trade name “DINP”, phthalic acid) Except that 2.93 parts by mass of bis (2-ethylhexyl), solid content: 100%, manufactured by J-Plus Co., Ltd.) was dissolved in 25 parts by mass of the above mixed solvent “KT-11” to obtain an adhesive composition. The laminated body and optical member of Comparative Example 6 were obtained in the same manner as in Example 1.

<Examination of stress suppression characteristics>
By performing the following tests, the stress suppression characteristics of the TAC laminate of the present invention were verified from the elastic aspect of the adhesive layer.

Using the laminated body of each Example / Comparative Example, the storage elastic modulus E ′ at room temperature (20 ° C.) and the storage elasticity at high temperature (60 ° C.) for the adhesive layer of each Example / Comparative Example The rate E ′ was measured. And the difference (E '(20 degreeC) -E' (60 degreeC)) with respect to the storage elastic modulus E 'in the room temperature state of the storage elastic modulus E' in a high temperature state (60 degreeC) was computed. The storage elastic modulus E ′ is measured by using a solid viscoelasticity analyzer RSA-III manufactured by TA Instruments Inc., and a dynamic viscoelasticity measurement method (attachment mode: compression mode, frequency: compliant with JIS K7244-1). 1 Hz, temperature: −50 to 150 degrees, temperature increase rate: 5 degrees / minute). Table 3 shows the measurement results. In Table 3, the case where the value of E ′ (20 ° C.) is 4.5 × 10 ⁵ or more and 8.0 × 10 ⁵ or less is “good”, and the case where it is not is “bad”. Further, the case where the difference of E ′ (E ′ (20 ° C.) − E ′ (60 ° C.)) is 2.0 × 10 ⁵ or more and 6.0 × 10 ⁵ or less is defined as “good”, and the case where the difference is not “ “Bad”.

<Evaluation of durability test>
Each optical member of each example and comparative example was stored for 500 hours under conditions of high temperature and high humidity (60 ° C., 90% RH), and then visually measured whether the adhesive film of the TAC substrate was lifted from the polarizing plate. did. The evaluation criteria are as follows.
Good: No lifting or peeling.
Defect: A float or peeling occurred.
Table 3 shows the measurement results.

In Table 3, it appears that wrinkles occur between the values of E ′ (20 ° C.) and E ′ (60 ° C.) and the difference between E ′ (E ′ (20 ° C.) − E ′ (60 ° C.)). There are places, but these are not errors. For example, in Example 1, the difference in E ′ seems to be 3.0 × 10 ⁵ Pa at first glance, but the more detailed value of E ′ (20 ° C.) is 4.74 × 10 ⁵ Pa. The more detailed value of E ′ (60 ° C.) is 1.67 × 10 ⁵ Pa, and the difference of E ′ is 3.07 × 10 ⁵ Pa. Table 3 is based on the fact that the mantissa part of these exponents is rounded off to the second decimal place, so there is no error in the description of Table 3.

In Comparative Example 1, at first glance, the difference in E ′ seems to be 0, but the more detailed value of E ′ (20 ° C.) is 3.69 × 10 ⁵ Pa, and more detailed E ′ ( 60 ° C) is 3.66 × 10 ⁵ Pa, and Table 3 is based on rounding off the second decimal place in the mantissa part of these exponents. There is no.

In Comparative Example 3, at first glance, the difference in E ′ seems to be 1.8 × 10 ⁵ Pa, but the more accurate value of E ′ (20 ° C.) is 3.13 × 10 ⁵ Pa, The actual value of E ′ (60 ° C.) is 1.25 × 10 ⁵ Pa, and the difference of E ′ is 1.85 × 10 ⁵ Pa. Table 3 is based on the fact that the mantissa part of these exponents is rounded off to the second decimal place, so there is no error in the description of Table 3.

In Comparative Example 4, at first glance, the difference in E ′ seems to be 1.4 × 10 ⁵ Pa, but the more accurate value of E ′ (20 ° C.) is 3.47 × 10 ⁵ Pa. The actual value of E ′ (60 ° C.) is 2.14 × 10 ⁵ Pa, and the difference of E ′ is 1.31 × 10 ⁵ Pa. Table 3 is based on the fact that the mantissa part of these exponents is rounded off to the second decimal place, so there is no error in the description of Table 3.

The adhesive layer contains an acrylic adhesive and an isocyanate curing agent or an epoxy curing agent, and is the difference between the storage elastic modulus E ′ at 20 ° C. and the storage elastic modulus E ′ at 60 ° C., E ′ (20 ° C.) The optical member using the TAC laminate having −E ′ (60 ° C.) of 2.0 × 10 ⁵ or more and 6.0 × 10 ⁵ can suppress the shrinkage of the TAC substrate, and as a result, the adhesion of the TAC substrate. It was confirmed that the film can be prevented from floating from the polarizing plate (Examples 1 to 4).

On the other hand, when the weight average molecular weight of the acrylic pressure-sensitive adhesive is 1 million or more (for example, when the average molecular weight of the acrylic pressure-sensitive adhesive is 1,200,000), E ′ (20 ° C.) − E ′ (60 ° C.) is 2.0. × 10 ⁵ lower than, for changes in the hardness of the adhesive layer due to temperature rise is small, that the adhesive film of TAC substrate is not preferable in that there is a possibility that the float from the adherend was observed under high temperature and high humidity (Comparative Examples 1 and 2).

  In addition, when the crosslinking group of the acrylic pressure-sensitive adhesive is not a carboxyl group but a hydroxyl group, sufficient cohesiveness cannot be obtained, so that the shrinkage of the TAC substrate cannot be suppressed. As a result, the TAC under high temperature and high humidity It was confirmed that the adhesive film of the substrate may float from the polarizing plate (Comparative Examples 3 and 4).

Further, when the pressure-sensitive adhesive layer contains an isocyanate-based curing agent, the content of the isocyanate-based curing agent (in terms of solid content) is small (for example, the content of the isocyanate-based curing agent is a solid content with respect to 100 parts by mass of the acrylic pressure-sensitive adhesive). In the case of 0.1 parts by mass or less in terms of conversion), since the size of E ′ (20 ° C.) does not reach 4.5 × 10 ⁵ Pa, the shrinkage stress of the TAC substrate cannot be suppressed, resulting in high temperature. It was confirmed that the TAC-based adhesive film might float from the polarizing plate under high humidity (Comparative Example 3).

Moreover, when there is much content (in solid content conversion) of an isocyanate hardening agent (For example, when the content of an isocyanate hardening agent exceeds 3 mass parts in conversion of solid content with respect to 100 mass parts of acrylic adhesives), E '(20 ° C) greatly exceeds 8.0 × 10 ⁵ Pa, and as a result, it was confirmed that the adhesive film of the TAC substrate may float from the polarizing plate under high temperature and high humidity (comparison) Examples 5, 6).

DESCRIPTION OF SYMBOLS 1 Optical member 11 TAC base material 12 Adhesive layer 13 Polarizing plate 14 2nd adhesive layer 15 Glass base material 16 Hard-coat layer 17 Antireflection layer

Claims (3)

A laminate in which an adhesive layer is formed on a triacetyl cellulose substrate,
The adhesive layer contains an acrylic adhesive and an isocyanate curing agent or an epoxy curing agent,
5. E ′ (20 ° C.) − E ′ (60 ° C.), which is the difference between the storage elastic modulus E ′ at 20 ° C. and the storage elastic modulus E ′ at 60 ° C. of the adhesive layer, is 2.0 × 10 ⁵ or more. Laminate which is 0 × 10 ⁵ or less.   The optical film by which the hard-coat layer and the antireflection layer were formed in the surface on the opposite side to the said adhesion layer of the said triacetyl cellulose base material in the laminated body of Claim 1.   The optical member by which the said triacetyl cellulose base material and a polarizing plate are laminated | stacked through the said adhesion layer in the optical film of Claim 2.

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