JP2018095693A - Adhesive film and information display device including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical adhesive film having excellent moist heat resistance.SOLUTION: This invention relates to an adhesive film, which is an adhesive tape having a triacetyl cellulose base material and an adhesive layer. The adhesive layer contains an acrylic copolymer, with an acrylic acid content in a monomer component constituting the acrylic copolymer being less than 1 mass%.SELECTED DRAWING: None

Description

  The present invention relates to an optical pressure-sensitive adhesive film such as an antireflection film or an antiglare film.

As an information display device such as a liquid crystal display, a plasma display, an organic EL display, and a display to which a touch panel function is added, it is difficult to see an image caused by reflection of light such as sunlight in an image display unit. In order to solve this problem, an antireflection material is used.

  As a method for imparting antireflection properties, for example, a method of attaching an antireflection film or an antiglare film to an image display surface is known (Patent Document 1).

  As these anti-reflection films and anti-glare films are suitable for polarized sunglasses, a TAC (triacetyl cellulose) film with a small retardation is often used as a base film, but in the adhesive layer, any commercially available OCA (optical Most products have a double-sided tape), and may not be used for TAC film base materials.

  Specific problems include wet heat resistance. In general, TAC film has the property of shrinking and hydrolyzing under wet heat conditions, and TAC film manufacturers and TAC film additive manufacturers are struggling to improve. In addition, as the use expands from mobile to in-vehicle, the required wet heat conditions are becoming more severe.

  On the other hand, the pressure-sensitive adhesive layer plays an important role in bonding the TAC film and the adherend, and it is necessary to suppress not only the shrinkage of the TAC film but also blistering and whitening under the severe wet heat conditions described above, The reality is that adhesive manufacturers are also struggling.

Japanese Patent Laid-Open No. 2003-177209

  The problem to be solved by the present invention is to provide an optical pressure-sensitive adhesive film excellent in moisture and heat resistance.

  When the present inventors examined in order to solve the said subject, in the adhesive tape which has a triacetylcellulose base material and an adhesive layer, by using the adhesive composition containing a specific adhesive for an adhesive layer. It has been found that the above problems can be solved.

  That is, the present invention is a pressure-sensitive adhesive tape having a triacetyl cellulose base material and a pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive layer contains an acrylic copolymer, and the acrylic in the monomer component constituting the acrylic copolymer. An adhesive film having an acid content of less than 1% by mass is provided.

  The pressure-sensitive adhesive film of the present invention has antireflection properties and antiglare properties, and has excellent moisture and heat resistance, and therefore suppresses yellowing and TAC film embrittlement even in a moisture and heat test (85 ° C., 85% RH). can do.

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 base material]
Triacetylcellulose (TAC) is excellent in incombustibility, transparency, surface appearance, optical isotropy, electrical insulation, and the like, and is suitably used as a substrate for optical films.

The thickness of the TAC substrate is not particularly limited and can be appropriately selected depending on the application. Usually, it is 20 μm or more and 150 μm or less, but preferably 30 μm or more and 100 μm or less. If the thickness is less than the above range, the mechanical strength is insufficient, and there is a possibility that a problem may occur in workability. Further, if it is thicker than the above range, it becomes expensive and may not be preferable.

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

  In addition, a plasticizer is added for the purpose of imparting flexibility, and a heat stabilizer, an ultraviolet absorber, an antioxidant, a filler, etc. are used for the purpose of adjusting mechanical strength, coatability, stability, etc. Additives can also be added as long as the transparency is not impaired.

  The TAC substrate may be subjected to known easy adhesion treatment such as corona discharge treatment, plasma treatment, ozone treatment, flame treatment, primer treatment, pre-heat treatment, dust removal treatment, vapor deposition treatment, alkali treatment, etc. Can be used without particular limitation.

[Adhesive layer]
The pressure-sensitive adhesive layer used in the present invention contains an acrylic copolymer, and as the monomer component constituting the acrylic copolymer, those generally used for pressure-sensitive adhesives can be used. For example, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, sec-butyl acrylate, t-butyl acrylate, n-hexyl acrylate, cyclohexyl acrylate, n-octyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, Acrylic acid alkyl esters such as isononyl acrylate, isodecyl acrylate, lauryl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, sec-butyl methacrylate, t-butyl methacrylate, n-hexyl methacrylate , Cyclohexyl methacrylate, n-octyl methacrylate, iso Chi methacrylate, 2-ethylhexyl methacrylate, isononyl methacrylate, isodecyl methacrylate, include alkyl methacrylate and lauryl methacrylate may be used in combination of them either singly or in combination.

  In the present specification, acrylic acid and methacrylic acid are collectively referred to as (meth) acrylic acid, and these derivatives are also represented in the same manner.

  In addition, a vinyl monomer having a functional group such as a hydroxyl group, a carboxyl group, or an amino group in the side chain can also be used, which is preferable. Specifically, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, dimethylaminoethylacrylamide, N-vinylpyrrolidone, acrylonitrile, N-vinylcaprolactam, acrylamide, Examples thereof include dimethyl acrylamide, diacetone acrylamide, N-methylol acrylamide, glycidyl (meth) acrylate, and the like. These can be used alone or in combination of two or more. Of these, 2-hydroxyethyl acrylate, dimethylacrylamide, and diacetone acrylamide can be preferably used.

  On the other hand, for the purpose of increasing the cohesive strength of the pressure-sensitive adhesive layer, a large number of acidic functional groups may be introduced or a tackifier having an acidic functional group may be used. It is preferable not to use an acrylic copolymer. Examples of the monomer component having a carboxylic acid group include unsaturated carboxylic acids such as (meth) acrylic acid, maleic acid, itaconic acid, crotonic acid, fumaric acid, and cinnamic acid. It is essential that the content of acrylic acid in the monomer component constituting the copolymer is less than 1% by mass. Conventionally, when an acrylic pressure-sensitive adhesive having an acidic functional group is used, the adherend is corroded or outgas is generated. Therefore, it is preferably used for fixing electronic members such as display materials. In some cases, especially when a pressure-sensitive adhesive containing acrylic acid is used, not only the deterioration of the pressure-sensitive adhesive layer but also the yellowing and embrittlement of the TAC base material are promoted in a high-temperature and high-humidity environment. . Specifically, it is presumed that acidic functional groups having high polarity promote water absorption and act as a catalyst, thereby causing hydrolysis of the TAC substrate. If acrylic acid is not included, hydrolysis of the TAC substrate is not accelerated. The content of acrylic acid in the monomer component constituting the acrylic copolymer is preferably less than 0.5% by mass, more preferably less than 0.1% by mass, still more preferably less than 0.05% by mass, and completely contained. Most preferably not.

  The weight average molecular weight of the acrylic copolymer in the pressure-sensitive adhesive layer of the present invention is preferably 50,000 to 3,000,000, more preferably 100,000 to 2,000,000. When the weight average molecular weight is too small, the adhesive force and cohesive force of the adhesive are inferior, and when the molecular weight is too large, the adhesive becomes hard and the adhesiveness becomes insufficient, so that the workability of sticking is deteriorated. In addition, the weight average molecular weight of an adhesive component can be measured using a polystyrene conversion value with a gel permeation chromatograph (GPC).

  The glass transition temperature of the acrylic copolymer in the pressure-sensitive adhesive layer of the present invention is preferably -30 to 20 ° C, more preferably -25 to 10 ° C. By being the glass transition temperature within the above range, a high elastic modulus can be imparted to the pressure-sensitive adhesive layer, and a high scratch resistance can be imparted to the hard coat film. The glass transition temperature of the pressure-sensitive adhesive component is determined by, for example, using a viscoelasticity tester such as a product name: Ares 2KSTD manufactured by Rheometrix Co., and sandwiching a test piece between parallel disks that are measuring units of the tester. The loss tangent (Tanδ) that can be calculated by measuring the storage elastic modulus (G ′) and the loss elastic modulus (G ″) at a frequency of 1 Hz can be calculated as the maximum temperature.

  The pressure-sensitive adhesive layer preferably contains a crosslinking agent as a component other than the acrylic copolymer in order to improve the cohesive force of the pressure-sensitive adhesive layer.

  Examples of the crosslinking agent used include isocyanate crosslinking agents, epoxy crosslinking agents, chelating crosslinking agents, azirine crosslinking agents, and polyfunctional acrylates. Among these, an isocyanate type crosslinking agent rich in reactivity with an acrylic copolymer is preferable. As an isocyanate type crosslinking 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, 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.

  0.01-5 mass parts is preferable with respect to 100 mass parts of solid content of an acrylic adhesive, and, as for the compounding quantity of the crosslinking agent added to the said adhesive layer, 0.03-3 mass parts is more preferable. By setting it as content of the said range, it is easy to adjust the gel fraction and adhesive force of an adhesive layer to a suitable range.

  In addition, the pressure-sensitive adhesive layer includes a tackifier, a dispersant, an antifoaming agent, a light stabilizer, a UV absorber, a plasticizer, a filler, a silane coupling agent, an antioxidant, and the like as necessary. It may contain other additives. As long as they do not contain an acidic functional group, especially acrylic acid, known ones can be used without particular limitation, and can be appropriately selected according to the performance required for the coating liquid and the adhesive layer. .

  The thickness of the pressure-sensitive adhesive layer of the present invention may be appropriately selected depending on the mode of use, but is preferably 5 to 100 μm, and more preferably 10 to 50 μm. By having the thickness within the above range, the adhesive strength, the sticking workability, the pencil hardness of the optical film, and the followability to the printed part applied to the hard coat film as necessary can be made a suitable range. .

  Moreover, in this invention, it is preferable that the total light transmittance in the visible light wavelength range as an adhesive layer is 90% or more, and a haze is less than 1.0% so that the transparency of a TAC base material may not be inhibited. If it is within the above range, the high-definition of the display equipped with the touch panel device using the adhesive film is easily maintained. In order to bring the total light transmittance and haze within the above ranges, it is necessary to appropriately select the compatibility of the pressure-sensitive adhesive component, the crosslinking agent, and other additives, the production method of the pressure-sensitive adhesive film, and the like.

[Adhesive film]
The pressure-sensitive adhesive film of the present invention can be prepared by a generally used method. For example, it can be produced by forming an adhesive layer on a TAC substrate or a release sheet. Specifically, the pressure-sensitive adhesive composition is directly applied to a TAC substrate film and dried or cured / polymerized, or once applied on a release sheet and dried to form a pressure-sensitive adhesive layer. It can be produced by a method of bonding to a material film and curing / polymerization. Or after apply | coating on a release sheet, drying, hardening and superposition | polymerization, you may bond together with a TAC base film. Among them, in order to improve the adhesion between the TAC base material and the pressure-sensitive adhesive layer and the TAC base material film may be bent, the pressure-sensitive adhesive layer is once coated on the release sheet and dried to be a pressure-sensitive adhesive layer. After forming the film, a method of curing and polymerizing after bonding to the TAC substrate film is preferable.

  There is no particular limitation on the method of providing the pressure-sensitive adhesive layer on the TAC substrate or the method of providing the pressure-sensitive adhesive layer on an arbitrary release sheet, and the viscosity of the pressure-sensitive adhesive can be appropriately selected according to the thickness. it can. For example, gravure coating method, micro gravure coating method, roll coating method, rod coating method, kiss coating method, knife coating method, air knife coating method, comma coating method, die coating method, lip coating method, flow coating method, dip coating method, spray Various known coating methods such as a coating method can be appropriately used. Generally, an adhesive often has a high viscosity, and a comma coating method, a die coating method, and a lip coating method are preferably used.

  The release sheet can be provided with an adhesive layer, and does not cause thermal alteration or the like due to bonding. On the other hand, it is a sheet that can be satisfactorily peeled off from the adhesive layer before being attached to an adherend. If there is no particular limitation. Specific examples include polyolefin resins such as polyethylene and polypropylene, ethylene-vinyl acetate copolymers, ethylene-vinyl alcohol copolymers, ethylene- (meth) acrylic acid (ester) copolymers, and ethylene-unsaturated carboxylic acids. Olefin copolymer resin such as copolymer metal neutralized product (so-called ionomer resin), acrylic resin such as polyacrylonitrile, polymethyl methacrylate, polyethyl methacrylate, styrene resin such as polystyrene, AS resin, ABS resin, Polyvinyl resins such as polyvinyl acetal, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyarylate, polycar A film made of a thermoplastic resin such as a polyester resin such as bonate, polyvinyl fluoride, polyvinylidene fluoride, polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, or the like, or plasma irradiation of the film, Examples thereof include those that have been surface-treated with a release agent such as a fluorine compound or a silicone compound. Among these, those obtained by treating the surface of polyethylene terephthalate with a release agent are particularly preferred from the viewpoint of being inexpensive, excellent in surface smoothness, and easy to adjust the peeling force.

  In the pressure-sensitive adhesive film of the present invention, an aging treatment is performed after the pressure-sensitive adhesive layer is formed on the TAC base material in order to increase the affinity between the pressure-sensitive adhesive layer and the TAC base material or to promote the curing and polymerization of the pressure-sensitive adhesive layer. It is effective to cure. Specifically, it is preferable to cure at 20 to 80 ° C. for 12 hours or more. However, depending on the composition and thickness of the pressure-sensitive adhesive layer, the fluidity may be excessively increased and may be oozed out to the end face. Therefore, curing at 25 to 60 ° C. for 12 to 240 hours is more preferable.

In the pressure-sensitive adhesive layer of the present invention, the gel fraction represented by the following formula when immersed in toluene for 24 hours is not particularly limited as long as the 180 ° peel adhesive force is achieved, but is 0 to 90%. Preferably, it is 20 to 80%. If the gel fraction of the pressure-sensitive adhesive layer is too low, the cohesive force is not expressed, and there is a risk that the adherend will float in a high temperature environment. On the other hand, if the gel fraction is too high, the pressure-sensitive adhesive layer becomes hard and the adhesive strength may be reduced.
Gel fraction (% by weight) = 100 × (W2-W0) / (W1-W0)
(W0: weight of TAC substrate, W1: weight of test piece before immersion, W2: weight of test piece after immersion and drying)

  The thickness of the pressure-sensitive adhesive film of the present invention is preferably 20 to 300 μm, more preferably 30 to 200 μm, and more preferably 40 to 150 μm. When the thickness is within the above range, workability such as punching and sticking is not lowered, and workability is improved.

  The pressure-sensitive adhesive film of the present invention is a pressure-bonded one-time reciprocation using a 2 kg roller on a glass panel in an environment of a temperature of 23 ° C. and a relative humidity of 50% RH, and is left in the same environment for 60 minutes. The 180 ° peel adhesive strength (peeling speed 300 mm / min) is preferably 4 N / 25 mm or more. If the adhesive strength is low and the 180 ° peel adhesive strength is too small, the heat resistance and moist heat resistance are inferior, and there is a fear that the adherend will float. Further, if the adhesive strength is high and the 180 ° peel adhesive strength is too large, peeling may be difficult. From such a viewpoint, the 180 ° peel adhesive strength is preferably 5 N / 25 mm or more and 30 N / 25 mm or less, and more preferably 6 N / 25 mm or more and 25 N / 25 mm or less. If it is in the said range, it will be easy to suppress the float from a to-be-adhered body in fixation of a TAC base material, and it will become easy to peel a double-sided adhesive tape in the poorly bonded product in a manufacturing process, and will be excellent in rework property. The 180 ° peel adhesive strength can be appropriately adjusted depending on the pressure-sensitive adhesive composition, the amount of the crosslinking agent, other additives, the gel fraction, and the pressure-sensitive adhesive film production method.

  Various types of liquid crystal display, plasma display, CRT display, EL display, field emission display, etc. are formed by further forming a hard coat layer, an antireflection layer, etc. on the surface of the adhesive film opposite to the adhesive layer of the TAC substrate. In an image display device, 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. Although the thickness of the said hard-coat layer is not specifically limited, 3-50 micrometers is preferable and 5-20 micrometers is more preferable. When the thickness is within the above range, it is possible to impart high scratch resistance, a thin image display device, and high punchability.

  The antireflection layer can be formed by a combination of a lamination of a low refractive index layer by adding fine particles such as hollow silica and a lamination of a high refractive index layer by adding fine particles such as zirconia. These can be obtained by known techniques.

  As an example of the information display device using the adhesive film of the present invention, the optical adhesive film in which the antireflection layer, the hard coat layer, the TAC substrate, and the adhesive layer are formed in this order is so that the adhesive layer and the glass panel are in contact with each other. By fixing to a glass panel, it can be suitably used as an antireflection film. The glass panel may be a glass panel for a touch panel having a conductive layer on at least one side, and the material, thickness and the like are not particularly limited and can be suitably used.

In recent years, a plastic molding material has been increasingly used as a cover material for a display surface, and can be used without particular limitation even when a polycarbonate substrate, an acrylic substrate or the like is used as an adherend.

  The method for attaching to the adherend is not particularly limited, but usually a pressure bonding method is generally used, and the adhesive film of the present invention can be suitably attached.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.
The glass transition temperature of the acrylic copolymer is made by using a viscoelasticity tester such as a product name: Ares 2KSTD manufactured by Rheometrix, and a test piece is sandwiched between parallel disks which are measuring units of the tester, The temperature was calculated as the temperature at which the loss tangent (Tan δ) that can be calculated by measuring the storage elastic modulus (G ′) and loss elastic modulus (G ″) at a frequency of 1 Hz was the maximum value.

<Acrylic copolymer (1)>
Preparation of acrylic copolymer In a reaction vessel equipped with a stirrer, cold flow cooler, thermometer, dropping funnel and nitrogen gas inlet, 20 parts by mass of n-butyl acrylate, 80 parts by mass of 2-methoxyethyl acrylate and a polymerization initiator An acrylic copolymer (1) having a weight average molecular weight of 750,000 is obtained by dissolving 0.2 part of 2,2′-azobisisobutylnitrile in 100 parts by mass of ethyl acetate, and substituting with nitrogen, followed by polymerization at 80 ° C. for 8 hours. Obtained.

<Acrylic copolymer (2)>
Preparation of acrylic copolymer In a reaction vessel equipped with a stirrer, cold flow cooler, thermometer, dropping funnel and nitrogen gas inlet, 10 parts by mass of methyl acrylate, 14 parts by mass of diacetone acrylamide, 56 parts by mass of n-butyl acrylate, 20 parts by mass of cyclohexyl acrylate and 0.2 part of 2,2′-azobisisobutylnitrile as a polymerization initiator are dissolved in 100 parts by mass of ethyl acetate, and after nitrogen substitution, polymerized at 80 ° C. for 8 hours to obtain a weight average molecular weight of 75. Ten thousand acrylic copolymers (2) were obtained.

<Acrylic copolymer (3)>
Preparation of acrylic copolymer Polymerized with 18 parts by mass of dimethylacrylamide, 40 parts by mass of 2-ethylhexyl acrylate, and 42 parts by mass of ethyl acrylate in a reaction vessel equipped with a stirrer, cold flow cooler, thermometer, dropping funnel and nitrogen gas inlet. As an initiator, 0.2 part of 2,2′-azobisisobutylnitrile is dissolved in 100 parts by mass of ethyl acetate, and after substitution with nitrogen, polymerization is carried out at 80 ° C. for 8 hours to obtain an acrylic copolymer having a weight average molecular weight of 750,000 ( 3) was obtained.

<Acrylic copolymer (4)>
Preparation of acrylic copolymer In a reaction vessel equipped with a stirrer, a cold flow cooler, a thermometer, a dropping funnel and a nitrogen gas inlet, 13 parts by mass of methyl acrylate, 87 parts by mass of n-butyl acrylate and 2,2 as a polymerization initiator '-Azobisisobutylnitrile (0.2 part) was dissolved in ethyl acetate (100 parts by mass), purged with nitrogen, and polymerized at 80 ° C. for 8 hours to obtain an acrylic copolymer (4) having a weight average molecular weight of 750,000.

<Acrylic copolymer (5)>
Preparation of acrylic copolymer Polymerized with 16 parts by mass of methyl methacrylate, 80 parts by mass of n-butyl acrylate, and 4 parts by mass of acrylic acid in a reaction vessel equipped with a stirrer, cold flow cooler, thermometer, dropping funnel and nitrogen gas inlet. As an initiator, 0.2 part of 2,2′-azobisisobutylnitrile is dissolved in 100 parts by mass of ethyl acetate, and after substitution with nitrogen, polymerization is carried out at 80 ° C. for 8 hours to obtain an acrylic copolymer having a weight average molecular weight of 750,000 ( 5) was obtained.

<Acrylic copolymer (6)>
Preparation of acrylic copolymer In a reaction vessel equipped with a stirrer, cold flow cooler, thermometer, dropping funnel and nitrogen gas inlet, 94 parts by mass of n-butyl acrylate, 6 parts by mass of acrylic acid and 2,2 as a polymerization initiator '-Azobisisobutylnitrile (0.2 parts) was dissolved in 100 parts by mass of ethyl acetate, purged with nitrogen, and then polymerized at 80 ° C for 8 hours to obtain an acrylic copolymer (6) having a weight average molecular weight of 750,000.

<Acrylic copolymer (7)>
Preparation of acrylic copolymer In a reaction vessel equipped with a stirrer, cold flow cooler, thermometer, dropping funnel and nitrogen gas inlet, 25 parts by mass of methyl acrylate, 65 parts by mass of n-butyl acrylate, 2 parts by mass of 2-hydroxyethyl acrylate Part, 8 parts by mass of acrylic acid and 0.2 part of 2,2′-azobisisobutylnitrile as a polymerization initiator are dissolved in 100 parts by mass of ethyl acetate, and after substitution with nitrogen, polymerization is carried out at 80 ° C. for 8 hours to obtain a weight average. An acrylic copolymer (7) having a molecular weight of 750,000 was obtained.

<Clear hard coat layer forming composition (1)>
Unidic 17-813 (DIC Corporation, polyfunctional urethane acrylate, nonvolatile content 80 mass%) 39 parts by mass, dipentaerythritol hexaacrylate (Toagosei Co., Ltd., Aronix M402) 31 parts by mass, as a photopolymerization initiator A clear hard coat layer forming composition (1) was obtained by mixing 4 parts by mass of Irgacure 184 (manufactured by BASF, hydroxycyclohexyl phenyl ketone) and 26 parts by mass of ethyl acetate as an organic solvent.

<Low refractive index layer forming composition (1)>
As the composition (1) for forming a low refractive index layer, “P-5062” (manufactured by JGC Catalysts & Chemicals, Inc., hollow silica fine particle dispersion, nonvolatile content 3 mass%) was used. The viscosity of the low refractive index layer-forming composition (1) was 2.0 mPa · s when measured at a rotational speed of 60 rpm using a B-type viscometer (BL type, manufactured by Tokyo Keiki Co., Ltd.).

<Antireflection film (I)>
A bar coater is attached to one side of a substrate made of TD80ULM (Fuji Film, thickness 80 μm, triacetyl cellulose film) so that the thickness after drying the clear hard coat layer forming composition (1) becomes 5 μm. A coating film was formed by drying for 2 minutes in an environment at a temperature of 80 ° C. Next, a clear hard coat layer was formed on the surface of the coating film by irradiating with ultraviolet rays so that the irradiation amount was 100 mJ / cm ² under an oxygen atmosphere using an H bulb manufactured by Fusion. Next, the low refractive index layer-forming composition (1) is applied onto the clear hard coat layer using a bar coater so that the thickness after drying becomes 0.1 μm, and the temperature is 80 ° C. Was dried for 2 minutes to form a coating film (low refractive index layer). Next, on the surface of the coating film (low refractive index layer), an H bulb manufactured by Fusion is used, and irradiation with ultraviolet rays is performed so that the irradiation amount is 400 mJ / cm ² in a nitrogen atmosphere, thereby preventing reflection. Film (I) was obtained.

Example 1
0.7 parts by mass of an isocyanate-based cross-linking agent (Lion Specialty Chemicals cross-linking agent N, solid content 75%) was added to 100 parts by mass of the acrylic copolymer (1), and the mixture was stirred for 15 minutes. The film was coated on a 75 μm thick polyester film (hereinafter referred to as # 75 peeled film) having been subjected to a release treatment so that the thickness after drying was 25 μm, and dried at 85 ° C. for 4 minutes. Thereafter, the pressure-sensitive adhesive layer was bonded to the surface opposite to the clear hard coat layer side of the antireflection film (I), and then aged at 40 ° C. for 72 hours to obtain a pressure-sensitive adhesive film having a gel fraction of 60%.

(Example 2)
An adhesive film having a gel fraction of 60% was obtained in the same manner as in Example 1 except that the thickness of the adhesive layer was 10 μm.

(Example 3)
An adhesive film having a gel fraction of 60% was obtained in the same manner as in Example 1 except that the thickness of the adhesive layer was 50 μm.

Example 4
An adhesive film having a gel fraction of 60% was obtained in the same manner as in Example 1 except that the acrylic copolymer (1) was changed to the acrylic copolymer (2).

(Example 5)
An adhesive film having a gel fraction of 60% was obtained in the same manner as in Example 1 except that the acrylic copolymer (1) was changed to the acrylic copolymer (3).

(Example 6)
An adhesive film having a gel fraction of 60% was obtained in the same manner as in Example 1 except that the acrylic copolymer (1) was changed to the acrylic copolymer (4).

(Comparative Example 1)
A pressure-sensitive adhesive film having a gel fraction of 60% was obtained in the same manner as in Example 1 except that the acrylic copolymer (1) was changed to the acrylic copolymer (5).

(Comparative Example 2)
An adhesive film having a gel fraction of 60% was obtained in the same manner as in Example 1 except that the acrylic copolymer (1) was changed to the acrylic copolymer (6).

(Comparative Example 3)
An adhesive film having a gel fraction of 60% was obtained in the same manner as in Example 1, except that the acrylic copolymer (1) was changed to the acrylic copolymer (7).

  The following evaluation was performed about the adhesive film obtained by the said Example and comparative example. The obtained results are shown in Tables 1 and 2 below.

(180 ° peel adhesion)
The obtained adhesive film was cut to a width of 25 mm, and then the # 75 release film was peeled off, and stuck in such a manner that the adhesive layer was in contact with the glass substrate in an environment of a temperature of 23 ° C. and a relative humidity of 50% RH. Was used for one-way reciprocation, and left in the same environment for 60 minutes. Thereafter, the adhesive strength when peeled in the 180 ° direction at a peeling speed of 300 mm / min was measured.

(Moisture and heat resistance)
The # 75 release film is peeled off from the adhesive film cut to 40 mm x 50 mm, and is attached so that the adhesive layer is in contact with the same size glass. After leaving still for 30 minutes in an environment of 5 atm, it was left at 23 ° C. for 1 hour to prepare a glass sticking test piece. Then, the glass sticking test piece was allowed to stand for 1000 hours in an environment having a temperature of 85 ° C. and a relative humidity of 85%, and the state of the glass sticking test piece was visually evaluated.

(1) Yellowing ○: The pressure-sensitive adhesive layer and the TAC base material layer of the pressure-sensitive adhesive film maintain a colorless and transparent state.
X: Either or both of the pressure-sensitive adhesive layer and the TAC base material layer of the pressure-sensitive adhesive film are yellow or brown.

(2) Embrittlement ○: The pressure-sensitive adhesive layer and the TAC base material layer of the pressure-sensitive adhesive film maintain the film state, and no cracks are observed.
X: Either or both of the pressure-sensitive adhesive layer and the TAC base material layer of the pressure-sensitive adhesive film are embrittled, and cracks and the like are generated.

    The compounds abbreviated in Table 1 and Table 2 are as follows.

2-MEA: 2-methoxyethyl acrylate BA: n-butyl acrylate 2-EHA: 2-ethylhexyl acrylate MA: methyl acrylate DAAM: diacetone acrylamide CHA: cyclohexyl acrylate DMAA: dimethyl acrylamide EA: ethyl acrylate MMA: methyl methacrylate 2- HEA: 2-hydroxyethyl acrylate

  As shown in Tables 1 and 2, the adhesive films of Examples 1 to 6 do not contain acrylic acid as the monomer composition of the acrylic copolymer of the adhesive layer, and are long in an environment at a temperature of 85 ° C. and a relative humidity of 85%. Even when exposed to time, it was possible to maintain a good state, and it was confirmed that the optical film had high moisture and heat resistance. In contrast, in Comparative Examples 1 to 3 containing 1% by mass or more of acrylic acid, yellowing and embrittlement of the TAC substrate occurred when exposed to an environment of 85 ° C. and 85% relative humidity for a long time. It was confirmed that deterioration of the pressure-sensitive adhesive layer and hydrolysis of the TAC substrate were promoted.

Claims (7)

A pressure-sensitive adhesive tape having a triacetyl cellulose base material and a pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive layer contains an acrylic copolymer, and the content of acrylic acid in the monomer component constituting the acrylic copolymer is 1 An adhesive film that is less than mass%. The pressure-sensitive adhesive film according to claim 1, wherein the pressure-sensitive adhesive layer has a thickness of 5 to 100 μm. The pressure-sensitive adhesive film according to claim 1 or 2, wherein the triacetylcellulose base material has a thickness of 20 µm or more and 150 µm or less. The pressure-sensitive adhesive film according to any one of claims 1 to 3, wherein the acrylic copolymer has a weight average molecular weight of 50,000 to 3,000,000. 180 ° peel adhesive strength (peeling) after pressing with a 2kg roller on a glass panel in an environment of temperature 23 ° C and relative humidity 50% RH using a 2kg roller and reciprocating for 60 minutes. The pressure-sensitive adhesive film according to any one of claims 1 to 4, wherein a speed of 300 mm / min is 4 N / 25 mm or more. The pressure-sensitive adhesive film according to any one of claims 1 to 5, wherein a hard coat layer and / or an antireflection layer is formed on a surface of the triacetylcellulose substrate opposite to the pressure-sensitive adhesive layer. The information display apparatus by which the adhesive film in any one of Claims 1-6 was laminated | stacked on the information display part.