TW202308843A - Multilayer optical film - Google Patents

Abstract

A multilayer optical film (X) according to the present invention is sequentially provided with an optical film (10), an adhesive layer (20) and an optical film (30) in the thickness direction (H). The adhesive layer (20) is bonded to the optical film (10), while also being bonded to the optical film (30). The optical film (30) has a boundary region (31) on the adhesive layer (20) side, the boundary region (31) containing an adhesive material component that is derived from the adhesive layer (20). The ratio of the thickness T2 of an adhesive material component-containing part (40), which consists of the adhesive layer (20) and the boundary region (31), to the thickness T1 of the adhesive layer (20) is 1.01 or more.

Description

Laminated Optical Film

The invention relates to a laminated optical film.

The display panel has, for example, a laminated structure including a pixel panel, a touch panel, a surface protection cover, and the like. The laminated structure of the display panel also includes various functional optical films with predetermined optical functions. Examples of functional optical films include polarizer films and retardation films. A functional optical film is, for example, incorporated into a laminated structure in a state where it is bonded to another optical film such as a protective film through an adhesive, that is, in the form of a laminated optical film. Such a laminated optical film is described, for example, in Patent Document 1 below. prior art literature patent documents

Patent Document 1: Japanese Patent Laid-Open No. 2019-147865

The problem to be solved by the invention With the thinning of display panels, the thinning of functional optical films continues to progress. The adhesive layer between the optical films in the laminated optical film is also required to be thin. However, the thinner the adhesive layer between the optical films, the easier it is to reduce the bonding force between the optical films. From the viewpoint of bonding reliability between optical films, the low bonding force is not preferable. For laminated optical films for display panels that can be repeatedly bent (folded), it is strongly required to ensure the bonding force between optical films. For laminated optical films used in foldable display panels used in high-temperature and high-humidity environments such as automobiles, excessive stress will be generated on the optical film due to high temperature and high humidity, resulting in stress concentration on the bonding interface, so optical film is prone to occur. Therefore, it is especially required to use the adhesive layer to ensure the bonding force between the optical films.

The present invention provides a laminated optical film which is suitable for securing bonding force between optical films even with a thin adhesive layer.

means to solve problems The present invention [1] includes a laminated optical film comprising a first optical film, an adhesive layer, and a second optical film sequentially in the thickness direction; the adhesive layer is joined to the first optical film, and is bonded to the aforementioned Bonding of the second optical film; the second optical film has a border area on the side of the adhesive layer, and the border area contains the adhesive raw material component derived from the adhesive layer; and the thickness T2 of the adhesive raw material component containing part is relative to the aforementioned The thickness T1 ratio of the adhesive layer is 1.01 or more, and the adhesive raw material component containing portion is a portion formed by combining the adhesive layer and the boundary region.

The present invention [2] includes the laminated optical film according to the above [1], wherein the aforementioned thickness T1 is 5 µm or less.

The present invention [3] includes the laminated optical film according to the above [1] or [2], wherein the 90° peel strength of the second optical film against the first optical film at 25°C is 0.8 N/15mm or more.

The present invention [4] includes the laminated optical film according to any one of the above-mentioned [1] to [3], wherein the first optical film is a polarizer film.

Invention effect In the laminated optical film of the present invention, as described above, the second optical film has a boundary region on the side of the adhesive layer joining the first and second optical films, and the boundary region contains adhesive raw material components derived from the adhesive layer. That is, the second optical film has a region (the aforementioned boundary region) in which the adhesive raw material component from the adhesive layer permeates on the adhesive layer side. In the boundary region, the constituent components of the second optical film and the adhesive raw material components are mixed. Furthermore, in this laminated optical film, as described above, the ratio of the thickness T2 of the adhesive material component containing portion to the thickness T1 of the adhesive layer is 1.01 or more. That is to say, in this laminated optical film, the thickness T2 of the portion (adhesive layer and boundary region) that contains the raw material components of the adhesive and participates in the adhesive function is greater than the thickness T1 of the adhesive layer. Such configurations of the boundary between the second optical film and the adhesive layer and the vicinity thereof are suitable for achieving a strong interaction between the second optical film and the adhesive layer and ensuring high bonding force. Furthermore, securing the bonding force between the second optical film and the adhesive layer contributes to securing the bonding force between the first and second optical films by the adhesive layer. Therefore, this laminated optical film is suitable for ensuring bonding force between optical films even if a thin adhesive layer is used. Ensuring that the bonding force between the optical films is suitable for suppressing peeling of the optical films. In addition, the above-mentioned laminated optical film is suitable for suppressing peeling of the optical films because the thin adhesive layer between the optical films can secure bonding force even under high-temperature and high-humidity environments.

The laminated optical film X which is one embodiment of the laminated optical film of the present invention, as shown in FIG. 2 optical films). The adhesive layer 20 is used to bond between the optical films 10 and 30 . The laminated optical film X has a sheet shape with a predetermined thickness, and expands in a direction (surface direction) perpendicular to the thickness direction H. Laminated optical film X is a composite film incorporated into the laminated structure of the display panel.

The optical film 10 is a functional optical film in this embodiment. Examples of functional optical films include polarizer films and retardation films.

The polarizer film can be, for example, a hydrophilic polymer film that has been dyed with a dichroic substance and then stretched. Examples of dichroic substances include iodine and dichroic dyes. Examples of the hydrophilic polymer film include polyvinyl alcohol (PVA) film, partially formalized PVA film, and partially saponified film of ethylene-vinyl acetate copolymer. The polarizer film may also be a polyene oriented film. The material of the polyene oriented film can be, for example, dehydrated PVA and dehydrochloridized polyvinyl chloride. In view of excellent optical properties such as polarizing properties, the polarizer film is preferably a PVA film that has been dyed with iodine and then uniaxially stretched.

From the viewpoint of thinning, the thickness of the optical film 10 as a polarizer film is preferably not more than 15 µm, more preferably not more than 12 µm, more preferably not more than 10 µm, and especially preferably not more than 8 µm. Thin polarizer film has excellent visibility due to less variation in thickness, and has excellent durability against thermal shock due to small dimensional changes due to temperature changes. From the viewpoint of strength, the thickness of the optical film 10 as a polarizer film is preferably 3 µm or more, more preferably 5 µm or more.

As a retardation film, a λ/2 wavelength film, a λ/4 wavelength film, and a viewing angle compensation film are mentioned, for example. The material of the retardation film can be, for example, a polymer film that is birefringent by stretching. Examples of polymer films include cellulose films and polyester films. The cellulose film may, for example, be a cellulose triacetate film. Examples of polyester films include polyethylene terephthalate films and polyethylene naphthalate films. The thickness of the optical film 10 as a retardation film is, for example, 20 µm or more and, for example, 150 µm or less. In addition, as the retardation film, a film including a substrate such as a cellulose film and an alignment layer of a liquid crystal compound such as a liquid crystal polymer on the substrate can also be suitably used.

The adhesive layer 20 is a cured product of the adhesive composition. The adhesive layer 20 is directly bonded to the optical film 10 and directly bonded to the optical film 30 . The adhesive composition contains a curable resin. The components of the adhesive composition are specifically described below.

From the viewpoint of bonding force between the optical films 10 and 30, the thickness T1 of the adhesive layer 20 is preferably not less than 0.1 µm, more preferably not less than 0.4 µm, more preferably not less than 0.7 µm, particularly preferably not less than 0.8 µm. From the viewpoint of thinning the laminated optical film X, the thickness T1 of the adhesive layer 20 is preferably not more than 5 µm, more preferably not more than 3 µm, more preferably not more than 1.5 µm, and most preferably not more than 1 µm. The thickness T1 of the adhesive layer 20 is the length in the thickness direction H of the region having the hardened structure of the adhesive composition (formed by hardened components). This length can be measured in an image obtained by observation such as SEM observation. The thickness T1 of the adhesive layer 20 can be specifically measured by the method described later in the embodiments.

The first indentation elastic modulus of the adhesive layer 20 measured by the nanoindentation method at 25°C is preferably not less than 0.01GPa, more preferably not less than 0.03GPa, more preferably not less than 0.05GPa, especially preferably not less than 0.07GPa ( The first indentation elastic modulus is set as the indentation elastic modulus under the first measurement condition; the first measurement condition is as described later for the examples, in the first measurement condition, the indenter is The maximum indentation depth of the test sample is 200nm). Such a configuration is preferable from the viewpoint of ensuring bonding force between the optical films 10 and 30 . Also, the first indentation elastic modulus is preferably 5 GPa or less, more preferably 3 GPa or less, more preferably 1 GPa or less. Such a configuration is suitable for securing the flexibility of the adhesive layer 20, and thus is suitable for securing the flexibility of the laminated optical film X. The method of adjusting the indentation elastic modulus of the adhesive layer 20 may, for example, adjust the composition of the adhesive composition. Specifically, the effective method for adjusting the indentation elastic modulus of the adhesive layer 20 is to adjust the number of functional groups of the polymerizable compound described later in the adhesive composition forming the adhesive layer 20, that is, to adjust the acryl group equivalent of the polymerizable compound or epoxy equivalent.

The nanoindentation method refers to the method of measuring various physical properties of the sample at the nanometer scale. In this embodiment, the nanoindentation method is carried out in accordance with ISO14577. The nanoindentation method is to implement the process of pressing the indenter into the sample installed on the stage (load application process), and then pull the indenter out of the sample (unloading process), and measure a series of processes The load acting between the indenter and the sample and the relative displacement of the indenter to the sample (load-displacement measurement). From this, a load-displacement curve can be obtained. From this load-displacement curve, various physical properties of the measurement sample can be determined based on nanoscale measurement. The load-displacement measurement of the cross section of the adhesive layer by the nanoindentation method can use, for example, a nanoindenter (trade name "Triboindenter", manufactured by Hysitron Corporation). Specifically, it is as described in the examples below.

The second indentation elastic modulus of the adhesive layer 20 measured by nanoindentation method at 25°C is preferably 0.5 GPa or more, more preferably 1 GPa or more, more preferably 1.5 GPa or more, especially 2 GPa or more (the second The indentation elastic modulus is set as the indentation elastic modulus under the second measurement condition; the second measurement condition is as described later for the examples. In the second measurement condition, the indenter measures the The maximum indentation depth of the sample is 50nm). Such a configuration is preferable from the viewpoint of ensuring bonding force between the optical films 10 and 30 . Also, the second indentation elastic modulus is preferably 7 GPa or less, more preferably 5 GPa or less, more preferably 3 GPa or less. Such a configuration is suitable for securing the flexibility of the adhesive layer 20, and thus is suitable for securing the flexibility of the laminated optical film X.

The optical film 30 is a transparent protective film in this embodiment. The transparent protective film is, for example, a flexible transparent resin film. The material of the transparent protective film includes, for example, polyolefin, polyester, polyamide, polyimide, polyvinyl chloride, polyvinyl chloride, cellulose, modified cellulose, polystyrene and polycarbonate. Examples of polyolefins include cycloolefin polymers (COP), polyethylene, polypropylene, ethylene-propylene copolymers, ethylene-vinyl acetate copolymers, and ethylene-vinyl alcohol copolymers. Examples of polyester include polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate. The polyamide can be, for example, polyamide 6, polyamide 6,6 and partially aromatic polyamide. Modified cellulose may, for example, be cellulose triacetate. These materials may be used alone or in combination of two or more. From the viewpoint of cleanliness, it is preferable to use polyolefin as the material of the transparent protective film, and it is more preferable to use COP.

From the viewpoint of the strength of the laminated optical film X, the thickness of the optical film 30 is preferably at least 5 µm, more preferably at least 10 µm, and more preferably at least 20 µm. From the viewpoint of thinning the laminated optical film X, the thickness of the optical film 30 is preferably 100 µm or less, more preferably 70 µm or less, more preferably 50 µm or less.

As shown in FIG. 2 , the optical film 30 has a border region 31 on the side of the adhesive layer 20 and a non-border region 32 on the side opposite to the adhesive layer 20 . The boundary region 31 contains adhesive raw material components derived from the adhesive layer 20 . In the boundary region 31, the constituent components of the optical film 30 and the adhesive raw material components are mixed. The detection method of the raw material components of the adhesive can be, for example, Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS: Time-of-Flight Secondary Ion Mass Spectrometry). On the other hand, the non-boundary region 32 does not contain adhesive raw material components derived from the adhesive layer 20 . The non-border region 32 is composed of components of the optical film 30 . In the optical film 30, the area where the adhesive raw material components above the detection limit value (positive and negative secondary ion intensity 0.1 counts/second) is detected in the above-mentioned detection method is the boundary area 31, and the above-mentioned detection limit value is not detected The area of the above adhesive raw material components is the non-boundary area 32 . The ratio of the thickness of the boundary region 31 to the thickness of the non-border region 32 is, for example, 0.01% or more, preferably 0.05% or more, and for example, 50% or less, preferably 20% or less.

The thickness of the boundary region 31 is, for example, not less than 0.01 µm, preferably not less than 0.05 µm. The thickness of the boundary region 31 is, for example, 10 µm or less, preferably 5 µm or less. The method of adjusting the thickness of the boundary region 31 may be, for example, adjusting the composition of the adhesive composition. The method of adjusting the thickness of the boundary region 31 also includes adjusting the time from the coating step described later to the hardening step in the production process of the laminated optical film X. The longer this time is, the thicker the boundary region 31 tends to be.

In the laminated optical film X, the boundary region 31 and the above-mentioned adhesive layer 20 form an adhesive raw material component containing portion 40 . In order to prevent insufficient adhesion when the boundary region 31 is too small (too thin), the ratio (T2/T1) of the thickness T2 of the adhesive material component containing portion 40 to the thickness T1 of the adhesive layer 20 is 1.01 or more, preferably 1.05. More preferably, it is more than 1.1, and more preferably it is more than 1.2. From the point of view of both the adhesiveness between the adhesive layer 20 and the optical film 30 and the production stability of the laminated optical film X, the ratio (T2/T1) is preferably 1.3 or less, more preferably 1.25 or less, and more preferably 1.25 or less. Below 1.2. The aforementioned adhesion between the adhesive layer 20 and the optical film 30 can be ensured, for example, by the following method: after ensuring the thickness of the adhesive layer 20, when the laminated optical film X is bent, the The peeling occurs due to the load on the interface of the film 30. The thickness T2 of the adhesive raw material component containing portion 40 is larger than the thickness of the adhesive layer 20 and smaller than the total thickness of the adhesive layer 20 and the optical film 30 . The thickness T2 of the adhesive raw material component containing portion 40 depends on the thickness and composition of the adhesive layer 20 and the material of the optical film 30, and is, for example, not less than 0.101 µm and not more than 6.5 µm. The thickness T2 of the adhesive raw material component containing portion 40 and the thickness of the above-mentioned boundary region 31 can be measured by the method described later for the examples.

The laminated optical film X is as described above, and the optical film 30 has the boundary region 31 on the adhesive layer 20 side of the film. In the boundary region 31, the constituent components of the optical film 30 and the adhesive raw material components are mixed. Furthermore, in the laminated optical film X, the ratio of the thickness T2 of the adhesive raw material component containing portion 40 (adhesive layer 20, boundary region 31) to the thickness T1 of the adhesive layer 20 is 1.01 or more, preferably 1.05 or more, which is relatively low. It is preferably 1.1 or more, more preferably 1.2 or more. That is, in the laminated optical film X, the thickness T2 of the portion (the adhesive layer 20 and the boundary region 31 ) that contains the adhesive raw material components and participates in the adhesive function is greater than the thickness T1 of the adhesive layer 20 . The configurations of the boundary between the optical film 30 and the adhesive layer 20 and the vicinity thereof are suitable for achieving a strong interaction between the optical film 30 and the adhesive layer 20 and ensuring high bonding force. Furthermore, ensuring the bonding force between the optical film 30 and the adhesive layer 20 helps to ensure the bonding force between the first optical films 10 and 30 by using the adhesive layer 20 . Therefore, the laminated optical film X is suitable for securing bonding force between the optical films 10 and 30 even with a thin adhesive layer 20 . The bonding force between the optical films 10 and 30 is ensured to be suitable for suppressing peeling of the optical films 10 and 30 . Furthermore, the laminated optical film X is suitable for suppressing peeling of the optical films 10 and 30 because the thin adhesive layer 20 between the optical films 10 and 30 can secure bonding force even under high temperature and high humidity environment. Specifically, it is as shown in the Examples and Comparative Examples described later.

In the laminated optical film X, the 90° peel strength of the optical film 30 against the optical film 10 at 25°C is preferably 0.8N/15mm or more, more preferably 1N/15mm or more, more preferably 1.2N/15mm or more, and especially preferably Above 1.5N/15mm. The above configuration is suitable for achieving good bonding force between the optical films 10 and 30 , and is particularly suitable for securing the bonding force between the optical films 10 and 30 for foldable display panels. The 90° peel strength is, for example, 10 N/15 mm or less. The 90° peel strength can be measured by the method described later in the examples. In addition, the method of adjusting the 90° peel strength may, for example, adjust the ratio (T2/T1) and adjust the composition of the adhesive composition.

The ratio of the aforementioned 90° peel strength (N/15mm) to the first indentation elastic modulus (GPa) is preferably 5 or more, more preferably 10 or more, more preferably 15 or more, and preferably 30 or less, more preferably 25 or less. Such a configuration is advantageous in that peeling between the optical films 10 and 30 can be suppressed when the laminated optical film X (in particular, a thin laminated optical film X) is repeatedly bent.

The ratio of the aforementioned 90° peel strength (N/15mm) to the second indentation elastic modulus (GPa) is preferably at least 0.2, more preferably at least 0.3, more preferably at least 0.4, and preferably at most 5, more preferably at least 0.2. 3 or less, more preferably 2 or less. Such a configuration is advantageous in that peeling between the optical films 10 and 30 can be suppressed when the laminated optical film X (in particular, a thin laminated optical film X) is repeatedly bent.

The adhesive layer 20 is, for example, a cured product of an adhesive composition (active energy ray-curable composition) containing an active energy ray-curable curable resin. The active energy ray curable composition includes, for example, an electron beam curable composition, an ultraviolet ray curable composition, and a visible ray curable composition. The active energy ray-curable composition is either or both of a radical polymerizable composition and a cationic polymerizable composition in this embodiment.

The radically polymerizable composition contains a radically polymerizable compound as a monomer. The radically polymerizable compound is a compound having a radically polymerizable functional group. As a radical polymerizable functional group, the group containing an ethylenic unsaturated bond is mentioned, for example. The ethylenically unsaturated bond-containing group includes, for example, a (meth)acryl group, a vinyl group, and an allyl group. (Meth)acryl means acryl and/or methacryl. From the viewpoint of the curability of the active energy ray-curable composition, the active energy ray-curable composition preferably contains a radically polymerizable compound having a (meth)acryl group as a main component. The principal component means the most numerous component in terms of mass ratio. The ratio of the (meth)acryl group-containing radically polymerizable compound in the active energy ray-curable composition is, for example, 50% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more. Moreover, examples of the radical polymerizable compound include monofunctional radical polymerizable compounds and polyfunctional radical polymerizable compounds having more than two functions.

As a monofunctional radically polymerizable compound, the (meth)acrylamide derivative which has a (meth)acrylamide group is mentioned, for example. Examples of (meth)acrylamide derivatives include N-alkyl-containing (meth)acrylamide derivatives, N-hydroxyalkyl-containing (meth)acrylamide derivatives, N-aminoalkyl-containing (meth)acrylamide derivatives containing N-alkoxy groups, (meth)acrylamide derivatives containing N-alkoxy groups, and (meth)acrylamide derivatives containing N-mercaptoalkyl groups. N-alkyl-containing (meth)acrylamide derivatives include, for example: N-methyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N- Diethyl (meth)acrylamide, N-isopropyl (meth)acrylamide, N-butyl (meth)acrylamide and N-hexyl (meth)acrylamide, preferably N , N-Diethylacrylamide. Examples of (meth)acrylamide derivatives containing N-hydroxyalkyl include: N-methylol (meth)acrylamide, N-hydroxyethyl (meth)acrylamide and N-methylol (meth)acrylamide N-propane (meth)acrylamide, preferably N-hydroxyethylacrylamide. The (meth)acrylamide derivatives may be used alone or in combination of two or more.

As a monofunctional radically polymerizable compound, the (meth)acrylic acid derivative which has a (meth)acryloxy group is mentioned, for example. Examples of the (meth)acrylic acid derivative include (meth)acrylic acid derivatives other than alkyl (meth)acrylate and alkyl (meth)acrylate. The (meth)acrylic acid derivatives may be used alone or in combination of two or more.

Alkyl (meth)acrylates include, for example: methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, (meth)acrylate ) n-butyl acrylate, isobutyl (meth) acrylate, n-pentyl (meth) acrylate, 2,2-dimethyl butyl (meth) acrylate, n-hexyl (meth) acrylate, (meth) ) n-octyl acrylate, 2-ethylhexyl (meth)acrylate, 4-methyl-2-propylpentyl (meth)acrylate and n-octadecyl (meth)acrylate.

Examples of (meth)acrylic acid derivatives other than alkyl (meth)acrylates include cycloalkyl (meth)acrylates, aralkyl (meth)acrylates, and hydroxyl-containing (meth)acrylic acid derivatives. , Alkoxy-containing (meth)acrylic acid derivatives and phenoxy-containing (meth)acrylic acid derivatives. As cycloalkyl (meth)acrylate, cyclohexyl (meth)acrylate and cyclopentyl (meth)acrylate are mentioned, for example. Examples of aralkyl (meth)acrylate include benzyl (meth)acrylate and 3-phenoxybenzyl (meth)acrylate. Examples of hydroxyl-containing (meth)acrylic acid derivatives include: 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, (meth)acrylate ) 2-hydroxybutyl acrylate, 4-hydroxybutyl (meth)acrylate, [4-(hydroxymethyl)cyclohexyl]methacrylate and 2-hydroxy-3-phenoxypropyl (methyl) Acrylate. Alkoxy-containing (meth)acrylic acid derivatives include, for example, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate and 3-methoxybutyl (meth)acrylates. Examples of phenoxy-containing (meth)acrylic acid derivatives include phenoxyethyl (meth)acrylate and phenoxydiethylene glycol (meth)acrylate. (Meth)acrylic acid derivatives other than alkyl (meth)acrylates are preferably selected from 3-phenoxybenzyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate and phenoxy At least one of the group consisting of diethylene glycol acrylate.

Carboxyl group-containing monomers are also mentioned as a monofunctional radically polymerizable compound. Examples of carboxyl group-containing monomers include (meth)acrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid.

Examples of the monofunctional radically polymerizable compound include lactamide-based vinyl monomers. Examples of lactam-based vinyl monomers include N-vinyl-2-pyrrolidone, N-vinyl-ε-caprolactam, and methylvinylpyrrolidone.

As the monofunctional radically polymerizable compound, a vinyl-based monomer having a nitrogen-containing heterocycle can also be mentioned. Examples of such monomers include vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperidone, vinylpyridine, vinylpyrrole, vinylimidazole, vinyloxazole, and vinylmorphine.

As the polyfunctional radically polymerizable compound, for example, tripropylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1, 9-nonanediol di(meth)acrylate, 1,10-decanediol diacrylate, 2-Eth-2-butylpropanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate Acrylates, tricyclodecane dimethanol di(meth)acrylate, cyclic trimethylolpropane formal (meth)acrylate, dioxanediol di(meth)acrylate, trimethylolpropane trimethylolpropane (Meth)acrylate, neopentylthritol tri(meth)acrylate, neopentylthritol tetra(meth)acrylate, diperythritol penta(meth)acrylate and diperythritol hexa(meth)acrylate As (meth)acrylate, tripropylene glycol diacrylate is preferably used. The polyfunctional radically polymerizable compound may be used alone or in combination of two or more. A polyfunctional radically polymerizable compound can function as a crosslinking agent.

化合物。二苯基酮化合物可舉例如苄基、二苯基酮、苯甲醯苯甲酸及3,3'-二甲基-4-甲氧基二苯基酮。苯偶姻醚化合物可舉例如苯偶姻甲醚、苯偶姻乙醚、苯偶姻異丙醚及苯偶姻異丁醚。9-氧硫𠮿

化合物可列舉例如：9-氧硫𠮿

、2-氯9-氧硫𠮿

、2-甲基9-氧硫𠮿

、2,4-二甲基9-氧硫𠮿

、異丙基9-氧硫𠮿

、2,4-二氯9-氧硫𠮿

、2,4-二乙基9-氧硫𠮿

、2,4-二異丙基9-氧硫𠮿

及十二基9-氧硫𠮿

。When the active energy ray-curable composition is an ultraviolet ray-curable composition or a visible ray-curable composition, the active energy ray-curable composition contains a photopolymerization initiator. Photopolymerization initiators can be, for example, benzophenone compounds, benzoin ether compounds and 9-oxothiophene

compound. Examples of the diphenyl ketone compound include benzyl, diphenyl ketone, benzoylbenzoic acid and 3,3'-dimethyl-4-methoxy diphenyl ketone. Examples of benzoin ether compounds include benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether and benzoin isobutyl ether. 9-oxosulfur

Compounds can be listed for example: 9-oxosulfur

, 2-Chloro9-oxosulfur 𠮿

, 2-methyl 9-oxosulfur 𠮿

, 2,4-Dimethyl 9-oxosulfur 𠮿

, Isopropyl 9-oxosulfur

, 2,4-dichloro-9-oxosulfur 𠮿

, 2,4-Diethyl 9-oxosulfur 𠮿

, 2,4-Diisopropyl 9-oxosulfur 𠮿

and dodecyl 9-oxosulfur

.

When the active energy ray curable composition is a visible ray curable composition, it is preferable to use a photopolymerization initiator having high sensitivity to light of 380 nm or more. The photopolymerization initiator can be exemplified, for example: 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1 -(4-morpholinylphenyl)-butan-1-one, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4- Morpholinyl)phenyl]-1-butanone, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis(2,4,6-trimethylbenzoyl base)-phenylphosphine oxide and bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)-phenyl )titanium.

、及/或2-甲基-1-(4-甲硫基苯基)-2-嗎福林基丙-1-酮。The photopolymerization initiator should use 2,4-diethyl 9-oxosulfur

, and/or 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one.

The content of the photopolymerization initiator in the active energy ray-curable composition is preferably at least 0.1 parts by mass, more preferably at least 0.05 parts by mass, more preferably 0.1 parts by mass relative to 100 parts by mass of the curable component (radical polymerizable compound). More than 20 parts by mass, preferably less than 10 parts by mass, more preferably less than 5 parts by mass.

When the active energy ray-curable composition is a cationic polymer composition, the composition contains a cationic polymerizable compound as a monomer. The cationic polymerizable compound is a compound having a cationic polymerizable functional group, which includes a monofunctional cationic polymerizable compound with one cationic polymerizable functional group and a multifunctional cationic polymerizable compound with two or more cationic polymerizable functional groups. The liquid viscosity of the monofunctional cationic polymerizable compound is relatively low. By blending the monofunctional cationic polymerizable compound into the resin composition, the viscosity of the resin composition can be reduced. Moreover, many monofunctional cationically polymerizable compounds have functional groups capable of exhibiting various functions. By blending the monofunctional cationic polymerizable compound into the resin composition, the resin composition and/or the cured product of the resin composition can exhibit various functions. On the other hand, a cured product having a three-dimensional crosslinked portion can be obtained by curing a resin composition blended with a polyfunctional cationic polymerizable compound (the polyfunctional cationic polymerizable compound functions as a crosslinking agent). From such a viewpoint, it is preferable to use a polyfunctional cation polymerizable compound. When a monofunctional cation polymerizable compound and a polyfunctional cation polymerizable compound are used together, the amount of the polyfunctional cation polymerizable compound is, for example, 10 parts by mass or more and, for example, 1000 parts by mass or less with respect to 100 parts by mass of the monofunctional cation polymerizable compound . The cationic polymerizable functional group may, for example, be an epoxy group, an oxetanyl group or a vinyl ether group. The compound having an epoxy group includes, for example, aliphatic epoxy compounds, alicyclic epoxy compounds, and aromatic epoxy compounds. From the viewpoint of hardening and adhesiveness of the cationic polymer composition, it is preferable to use an alicyclic epoxy compound as the compound having an epoxy group. Alicyclic epoxy compounds can be, for example: 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, or 3,4-epoxycyclohexylmethyl-3,4- Caprolactone-modified, trimethylcaprolactone-modified, and valerolactone-modified substances of epoxycyclohexane carboxylate. Commercially available alicyclic epoxy compounds include, for example, CELLOXIDE 2021, CELLOXIDE 2021A, CELLOXIDE 2021P, CELLOXIDE 2081, CELLOXIDE 2083, and CELLOXIDE 2085 (manufactured by DAICEL Chemical Industry Co., Ltd.), and Cyracure UVR-6105, Cyracure UVR -6107, Cyracure 30 and R-6110 (the above are manufactured by DOW CHEMICAL Japan Co., Ltd.). From the standpoint of improving the curability and reducing the viscosity of the cationic polymer composition, it is preferable to use a compound having an oxetanyl group and/or a compound having a vinyl ether group. Compounds with an oxetane group include, for example: 3-E-3-hydroxymethyl oxetane, 1,4-bis[(3-E-3-oxetane)methoxy Methyl]benzene, 3-Eth-3-(phenoxymethyl)oxetane, bis[(3-Eth-3-oxetanyl)methyl]ether, 3-Eth- 3-(2-Ethylhexyloxymethyl)oxetane, phenol novolac oxetane, etc. Commercially available compounds having an oxetane group include, for example: ARON OXETANE OXT-101, ARON OXETANE OXT-121, ARON OXETANE OXT-211, ARON OXETANE OXT-221, ARON OXETANE OXT-212 (above, East Asia synthetic company). Compounds having a vinyl ether group include, for example: 2-hydroxyethyl vinyl ether, diethylene glycol monovinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether, triethylene glycol Alcohol divinyl ether, cyclohexanedimethanol divinyl ether, cyclohexanedimethanol monovinyl ether, tricyclodecane vinyl ether, cyclohexyl vinyl ether, methoxyethyl vinyl ether, ethyl Oxyethyl vinyl ether and neopentylthritol tetravinyl ether.

When the active energy ray-curable composition is an ultraviolet ray-curable composition or a visible ray-curable composition, the active energy ray-curable composition contains a photocationic polymerization initiator. When the photocationic polymerization initiator is irradiated by active energy rays (visible light, ultraviolet rays, X-rays, electron beams, etc.), it will generate cationic species or Lewis acid, and initiate the polymerization reaction of cationic polymerizable functional groups. Examples of photocationic polymerization initiators include photoacid generators and photobase generators, preferably photoacid generators. Active energy ray curable composition When a visible ray curable composition is used, it is particularly preferable to use a photocationic polymerization initiator that is highly sensitive to light above 380 nm. Moreover, when using a photocationic polymerization initiator, it is preferable to use together the photosensitizer which shows the maximum absorption with respect to the light of wavelength longer than 380 nm. A photocationic polymerization initiator is generally a compound that exhibits maximum absorption in a wavelength region near 300nm or shorter, so by using a photosensitizer that exhibits maximum absorption at a wavelength longer than 380nm, the wavelength can be effectively used Light longer than 380nm is used to promote the generation of cationic species or Lewis acids from photocationic polymerization initiators. Examples of photosensitizers include anthracene compounds, pyrene compounds, carbonyl compounds, organosulfur compounds, persulfide compounds, redox compounds, azo compounds, disazo compounds, halogen compounds, and photoreducible dyes. These may be used alone or in combination of two or more. In particular, an anthracene compound is preferable because of its excellent photosensitization effect. Commercially available products of an anthracene compound as a photosensitizer include, for example, ANTHRACURE UVS-1331 and ANTHRACURE UVS-1221 (manufactured by Kawasaki Chemical Co., Ltd.). The content of the photosensitizer in the composition is, for example, 0.1 to 5% by weight.

The active energy ray curable composition may also contain an oligomer. Examples of oligomers include acrylic oligomers, fluorine oligomers, and polysiloxane oligomers, preferably acrylic oligomers. The blending of the oligomer into the active energy ray-curable composition helps to adjust the viscosity of the composition, and helps to suppress the shrinkage of the composition when it is cured. Suppression of curing shrinkage of the active energy ray-curable composition is suitable for reducing the interface stress between the formed adhesive layer 20 and the optical films 10 and 30 . Suppression of interfacial stress helps to secure the bonding force between the optical films 10 and 30 .

Examples of (meth)acrylic monomers that form acrylic acid oligomers include alkyl (meth)acrylates with 1 to 20 carbon atoms, cycloalkyl (meth)acrylates, and aralkyl (meth)acrylates. esters, polycyclic (meth)acrylates, hydroxyl-containing (meth)acrylates and halogen-containing (meth)acrylates. Alkyl (meth)acrylates include, for example: methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, 2-methyl- 2-Nitropropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, S-butyl (meth)acrylate, tertiary butyl (meth)acrylate, n-pentyl (meth)acrylate, tertiary pentyl (meth)acrylate, 3-pentyl (meth)acrylate, 2,2-dimethylbutyl (meth)acrylate, (meth)acrylic acid n-hexyl ester, cetyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 4-methyl-2-propylpentyl (meth)acrylate and N-octadecyl(meth)acrylate. As cycloalkyl (meth)acrylate, cyclohexyl (meth)acrylate and cyclopentyl (meth)acrylate are mentioned, for example. As for aralkyl (meth)acrylate, benzyl (meth)acrylate is mentioned, for example. Polycyclic (meth)acrylates can be exemplified by 2-isobornyl (meth)acrylate, 2-norbornyl methyl (meth)acrylate, 5-norbornen-2-yl-methyl (meth)acrylate base) acrylate and 3-methyl-2-norbornyl methyl (meth)acrylate. Hydroxyl-containing (meth)acrylates include, for example, hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2,3-dihydroxypropylmethyl-butyl (meth)methacrylate base acrylate. Halogen-containing (meth)acrylates include, for example: 2,2,2-trifluoroethyl (meth)acrylate, 2,2,2-trifluoroethylethyl (meth)acrylate, tetrafluoroethyl (meth)acrylate, Fluoropropyl (meth)acrylate, hexafluoropropyl (meth)acrylate, octafluoropentyl (meth)acrylate, heptadecylfluorodecyl (meth)acrylate. These (meth)acrylates may be used alone or in combination of two or more.

The weight average molecular weight (Mw) of the acrylic acid oligomer is preferably 15,000 or less, more preferably 10,000 or less, more preferably 5,000 or less. The Mw of the acrylic acid oligomer is preferably not less than 500, more preferably not less than 1000, more preferably not less than 1500.

The content of the acrylic acid oligomer in the active energy ray curable composition is preferably at least 2% by mass, more preferably at least 4% by mass, and is preferably at most 20% by mass, more preferably at most 15% by mass.

The active energy ray curing composition may contain other components. Other components include silane coupling agent, leveling agent, surfactant, plasticizer and ultraviolet absorber. The blending amount of the other components is preferably not more than 10 parts by mass, more preferably not more than 5 parts by mass, more preferably not more than 3 parts by mass, and for example, not less than 0.01 parts by mass relative to 100 parts by mass of the hardening component.

From the viewpoint of coatability in the coating step described later, the viscosity of the active energy ray-curable composition at 25°C is preferably 3 mPa·s or higher, more preferably 5 mPa·s or higher, more preferably 10 mPa·s Above, and preferably below 100mPa·s, more preferably below 50mPa·s, more preferably below 30mPa·s. The viscosity of the composition is the measured value measured with an E-type viscometer (cone-plate viscometer).

The laminated optical film X can be produced, for example, as follows.

First, an active energy ray-curable composition is coated on one side (surface to be joined) of one of the optical films (optical film 10 or optical film 30 ) to form a coating film of the composition (coating step). Before this coating step, the surface to be joined of the optical film may also be subjected to surface modification treatment. Surface modifying treatments include corona treatment, plasma treatment, excimer treatment and flame treatment. The coating method in this step may be, for example, a reverse coater, a gravure coater, a rod reverse coater, a roll coater, a die coater, a rod coater, and a rod coater.

Next, the other optical film (the optical film 30 or the optical film 10 ) is bonded to one of the optical films via the composition coating film. For bonding, a roll laminator can be used, for example.

From the viewpoint of forming the boundary region 31 with a sufficient thickness, the active energy ray-curable composition preferably contains a monomer having an SP value close to that of the resin in the optical film 30 . When the active energy ray-curable composition contains the above-mentioned monomer, the above-mentioned monomer in contact with the surface of the optical film 30 is compatible with the surface during the coating and curing process of the active energy ray-curable composition, and The boundary area 31 is easily formed.

In the manufacturing process of the laminated optical film X, active energy rays are then irradiated to the composition coating film between the optical films 10 and 30 to harden the coating film (active energy ray-curable composition) (curing step). Thereby, the adhesive layer 20 is formed between the optical films 10 and 30, and the optical films 10 and 30 are bonded through the adhesive layer 20 (the adhesive layer 20 is not a pressure-sensitive adhesive layer). From the viewpoint of suppressing deterioration of the optical film 10 which is a functional optical film, it is preferable to irradiate active energy rays from the optical film 30 side in this step. Active energy rays can use electron beams, ultraviolet rays, and visible rays. The electron beam irradiation mechanism may, for example, be an electron beam accelerator. Examples of light sources for ultraviolet and visible light include: LED LIGHT, gallium-filled metal halide lamps, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high pressure mercury lamps, xenon lamps, halogen lamps, and gallium lamps. In this step, a wavelength cutoff filter may also be used as required to cut off the wavelength region of a part of the ultraviolet and/or visible light emitted from the light source.

As shown in FIG. 3 , the laminated optical film X can also be bonded with the optical film 30 on both sides of the optical film 10 in the thickness direction H through the adhesive layer 20 . The laminated optical film X (laminated optical film X′) shown in FIG. 3 includes an optical film 30 , an adhesive layer 20 , an optical film 10 , an adhesive layer 20 , and an optical film 30 sequentially in the thickness direction H. The composition of the active energy ray-curable composition forming the two adhesive layers 20 may be the same or different. The materials of the two optical films 30 can be the same or different from each other. The laminated optical film X' can be manufactured, for example, by further bonding the optical film 30 to the laminated optical film X in FIG. 1 through the adhesive layer 20 .

In the laminated optical film X′, at least one optical film 30 has the aforementioned boundary region 31 , preferably two optical films 30 have the boundary region 31 . In the laminated optical film X', each adhesive material component containing portion 40 formed by the boundary region 31 of each adhesive layer 20 and the optical film 30 in contact with the adhesive layer 20 is an adhesive material component containing portion. The ratio (T2/T1) of the thickness T2 of 40 to the thickness T1 of the adhesive layer 20 is at least 1.01, preferably at least 1.05, more preferably at least 1.1, and more preferably at least 1.2.

Example Examples are shown below to specifically illustrate the present invention. The present invention is not limited by the Examples. In addition, specific values such as the blending amount (content), physical property values, and parameters described below can be replaced by the corresponding blending amount (content), physical property values, and parameters described in the above "Forms for Implementing the Invention" The upper limit (the value defined as "below" or "less than") or the lower limit (the value defined as "above" or "greater than").

[Example 1] The following components were mixed at 25° C. for 1 hour at the blending amounts shown in Table 1 (blending amounts in terms of solid content) to prepare an adhesive composition (preparation step). The unit of the blending amount shown in Table 1 is relative "parts by mass".

，日本化藥公司製 ARUFON 1190(丙烯酸寡聚物)：黏度6000mPa・s(25℃)，Mw1700，Tg-50℃，東亞合成公司製 BYK-UV3505(調平劑)：具有丙烯醯基之改質聚二甲基矽氧烷，BYK公司製 LIGHT ACRYLATE POB-A (monomer): 3-phenoxybenzyl acrylate, manufactured by Kyoeisha Chemical Co., Ltd. LIGHT ACRYLATE P2H-A (monomer): phenoxydiethylene glycol acrylate, manufactured by Kyoeisha Chemical ARONIX M-5700 (monomer) manufactured by the company: 2-hydroxy-3-phenoxypropyl acrylate, ARONIX M-220 (monomer) manufactured by Toagosei Co., Ltd.: tripropylene glycol diacrylate, HEAA (monomer) manufactured by Toagosei Corporation Body): hydroxyethylacrylamide, DEAA manufactured by KJ Chemicals Corporation (monomer): diethylacrylamide, OMINIRAD907 manufactured by KJ Chemicals Corporation (photopolymerization initiator): 2-methyl-1-(4-methylthio phenyl)-2-morpholinopropan-1-one, KAYACURE DETX-S (photopolymerization initiator) manufactured by IGM Resins Co., Ltd.: 2,4-diethyl 9-oxosulfur

, ARUFON 1190 (acrylic acid oligomer) manufactured by Nippon Kayaku Corporation: viscosity 6000mPa·s (25°C), Mw1700, Tg-50°C, BYK-UV3505 (leveling agent) manufactured by Toagosei Corporation: modified with acrylyl group Quality polydimethylsiloxane, manufactured by BYK

Then, in the roll-to-roll system, a coating step, a bonding step, and a curing step are sequentially performed while running the elongated transparent protective film at a predetermined line speed. In the coating step, the adhesive composition was applied on a long COP film (product name "ZeonorFilm ZF14", manufactured by ZEON Corporation, Japan) with a thickness of 23 µm as a transparent protective film to form an adhesive coating film with a thickness of 0.9 µm. The MCD coating machine manufactured by Fuji Machinery Co., Ltd. (groove shape: honeycomb shape, gravure roll line number 1000/inch, rotation speed 140%/line speed) was used for coating. In the subsequent bonding step, the polarizer film (thickness 5 µm) is bonded to the transparent protective film through the adhesive coating film on the film. In the subsequent hardening step, the adhesive coating film between the films is hardened by irradiating ultraviolet rays through the transparent protective film to the adhesive coating film. Gallium lamps were used for ultraviolet irradiation. Thereby, a laminated optical film is obtained by joining the transparent protective film and the polarizer film.

In the above manner, the laminated optical film of Example 1 was produced. The laminated optical film of Example 1 is sequentially provided with a polarizer film (5 µm in thickness), an adhesive layer, and a transparent protective film (23 µm in thickness) in the thickness direction.

[Example 2] The laminated optical film of Example 2 was produced in the same manner as the laminated optical film of Example 1 except for the following matters. The above-mentioned production line speed is increased by a predetermined level, and the time from the coating step to the hardening step is shortened. The thickness of the coating film to be formed on the transparent protective film (COP film) in the coating step was set to a thickness of 2.6 µm.

The laminated optical film of Example 2 is sequentially provided with a polarizer film (5 µm in thickness), an adhesive layer, and a transparent protective film (23 µm in thickness) in the thickness direction.

[Example 3] The laminated optical film of Example 3 was produced in the same manner as the laminated optical film of Example 1 except for the following matters. The above-mentioned line speed is reduced by a predetermined degree, and the time from the coating step to the hardening step is increased. The thickness of the coating film to be formed on the transparent protective film (COP film) in the coating step was set to 1.2 µm.

The laminated optical film of Example 3 is sequentially provided with a polarizer film (5 µm in thickness), an adhesive layer, and a transparent protective film (23 µm in thickness) in the thickness direction.

[Comparative example 1] Except for the following matters, the laminated optical film of Comparative Example 1 was produced in the same manner as the laminated optical film of Example 1 (the production line speed between the coating step and the hardening step was the same as that of Example 1).

In the preparation step, an adhesive composition having the composition (ingredients, compounding amount) shown in Table 1 was prepared. As the monomer, 36 parts by mass of "LIGHT ACRYLATE 1.9ND-A" (1,9-nonanediol diacrylate) manufactured by Kyoeisha Chemical Co., Ltd. and "LIGHT ACRYLATE HPP-A" manufactured by Kyoeisha Chemical Co., Ltd. were used (Hydroxytrimethylacetic acid neopentyl glycol acrylate adduct) 12.5 parts by mass to replace "LIGHT ACRYLATE POB-A" and "LIGHT ACRYLATE P2H-A".

The thickness of the coating film to be formed on the transparent protective film (COP film) in the coating step was set to 0.93 µm.

The laminated optical film of Comparative Example 1 has a polarizer film (thickness 5 µm), an adhesive layer, and a transparent protective film (thickness 23 µm) sequentially in the thickness direction.

<Thickness of Adhesive Layer> The thickness T1 of the adhesive layer in each laminated optical film of Examples 1-3 and Comparative Example 1 was measured in the following manner. First, a 5 mm x 10 mm film sheet (laminated optical film) is cut out from the laminated optical film. Next, the laminated optical film was cut by the frozen section method. Specifically, after cooling the laminated optical film to -30°C, use a hard cutter to cut upward along the thickness direction of the film, and then return to room temperature. In this way, a laminated optical film with a cut surface is obtained, and then the cut surface is subjected to a conductive treatment with a thickness of less than 5nm. Thereby, a sample for observation was obtained. Next, the thickness of the adhesive layer was measured by SEM observation of the sample for observation. Specifically, a scanning electron microscope (product name "REGULUS8220", manufactured by HITACHI Corporation) was used to observe and photograph the secondary electron image of the cut surface of the sample for observation, and measure the thickness of the adhesive layer. In this observation, the acceleration voltage was set to 3.0 kV, the current amount was set to 10 µA, the working distance was set to 8 mm, the magnification was set to 100,000 times, and the detection mode was set to Upper+Lower mode. Table 1 shows the thickness T1 (µm) of the adhesive layer.

<Thickness of Adhesive Raw Material Component Containing Portion> The thickness T2 of the adhesive raw material component containing portion in each of the laminated optical films of Examples 1 to 3 and Comparative Example 1 was measured in the following manner. First, the transparent protective film of the film sheet cut out from the laminated optical film is cut to a predetermined depth from the surface side of the transparent protective film by a microtome to make it thinner. Thereby, a measurement sample is obtained. Next, the measurement sample was analyzed from the side of the transparent protective film by time-of-flight secondary ion mass spectrometry (TOF-SIMS). The analysis system used a time-of-flight secondary ion mass spectrometer (product name "TRIFT-V nanoTOF, manufactured by ULVAC-PHI Co., Ltd.). In this analysis, the ion beam for etching and the ion beam for measurement (primary ion beam) were irradiated alternately and repeatedly. ). For the irradiation of ion beams for etching, Ar gas cluster ions were used (cluster size (median value) was 2500), the acceleration voltage was set to 20kV, the ion beam current value was set to 10nA, and the irradiation range was set to 1000µm×1000µm. The irradiation time was set to 5 seconds. In the irradiation of the ion beam for measurement, double-charged ions (Bi ₃ ⁺⁺ ) of bismuth clusters were used as primary irradiation ions, the accelerating voltage was set to 30 kV, and the irradiation range was set to the ion beam for etching The central portion of the irradiation area is 200µm×200µm, and a neutralization gun used to correct the charge of the sample in the analysis is used. In addition, this analysis is carried out at room temperature. Through this analysis, secondary ions (positive ions, negative ions ) intensity of the mass spectrum of the depth profile (depth profile). Regarding the secondary ion intensity, it is converted to the value when the value of C ₃ H ₅ ⁺ is the reference value 1 for positive ions, and for negative ions It is said to be converted into the value when the value of C ₂ H ^- is the reference value of 1. Then, according to the obtained depth direction profile, the detection limit value of the transparent protective film (positive and negative secondary ion strength 0.1counts) is specified The region (boundary region) of the adhesive raw material component) above the adhesive material component. Then, the thickness T2 of the adhesive raw material component containing part is obtained from the thickness of the boundary region and the above-mentioned thickness T1 of the adhesive layer. The thickness T2 (µm ) are shown in Table 1. In addition, the ratio of thickness T2 to thickness T1 is also shown in Table 1.

<Peel Strength> The peel strength between the transparent protective film and the polarizer film in each of the laminated optical films of Examples 1 to 3 and Comparative Example 1 was investigated. First, a sample film having a size of 200 mm on the first side x 15 mm on the second side was cut out from the laminated optical film. The first side is a side extending along the extending direction of the polarizer film. The second side is a side extending in a direction perpendicular to the aforementioned extending direction. Next, the polarizer film side of the sample film was bonded to a glass plate through a strong adhesive. Next, the 90° peel strength (N/15mm) of the transparent protective film peeled from the polarizer film was measured with a TENSILON universal testing machine (product name "RTC", manufactured by A&D Company, Limited). In this measurement, the measurement temperature was 25° C., the peeling angle was 90°, and the peeling speed was 1000 mm/min. The measured 90° peel strength is shown in Table 1 as peel strength F ₁ .

<Indentation Elastic Modulus> The elastic modulus of the adhesive layer in each laminated optical film of Examples 1 to 3 and Comparative Example 1 was investigated by the nanoindentation method. Specifically, first, a film sheet (laminated optical film) with a size of 5 mm×10 mm is cut out from the laminated optical film. Next, the laminated optical film was cut by the frozen section method. Specifically, after cooling the laminated optical film to -30°C, use a hard cutter to cut upward along the thickness direction of the film, and then return to room temperature. Thereby, a sample for measurement is obtained. Next, use a nanoindentation tester (product name "TI950 Triboindenter", manufactured by Hysitron Corporation) to perform a load-displacement measurement on the exposed surface of the adhesive layer in the test sample in accordance with JIS Z 2255:2003, and obtain a load-displacement curve . In this measurement, the measurement mode is set to single indentation measurement, the measurement temperature is set to 25°C, the indenter used is a Berkovich (triangular pyramid) diamond indenter, and the maximum indentation depth of the indenter on the test sample during the load application process ( The maximum displacement (hmax) was set to 200 nm, the indenter's indentation speed was set to 10 nm/sec, and the indenter's pull-out speed from the measurement sample during unloading was set to 10 nm/sec (first measurement condition). Then, use the dedicated analysis software (Ver. 9.4.0.1) of "TI950 Triboindenter" to process the obtained measurement data. Specifically, according to the load (f)-displacement (h) curve obtained: the maximum load fmax (the load acting on the indenter with the maximum displacement hmax), the contact projected area S (the distance between the indenter and the sample at the maximum load) The projected area of the contact area between them), and the slope D of the tangent to the load-displacement curve at the beginning of unloading. Then, the indentation elastic modulus (=(π ^1/2 D)/(2S ^1/2 )) of the adhesive layer was calculated from the slope D and the contact projected area S. This value is shown in Table 1 as the indentation modulus M ₁ (GPa) (the indentation modulus M ₁ is the above-mentioned first indentation modulus). Also, Table 1 shows the ratio (F ₁ /M ₁ ) of the peel strength F ₁ to the indentation elastic modulus M ₁ .

On the other hand, the load-displacement measurement was performed with a nanoindenter under the same measurement conditions (second measurement conditions) as the first measurement conditions except that the maximum indentation depth was changed from 200 nm to 50 nm. Then, use the special analysis software (Ver. 9.4.0.1) of "TI950 Triboindenter" to process the measured data to calculate the indentation elastic modulus of the adhesive layer. This value is shown in Table 1 as the indentation modulus M ₂ (GPa) (the indentation modulus M ₂ is the above-mentioned second indentation modulus). Also, Table 1 shows the ratio (F ₁ /M ₂ ) of the peel strength F ₁ to the indentation elastic modulus M ₂ .

＜High temperature and high humidity flexural test＞ For each laminated optical film of Examples 1-3 and Comparative Example 1, a high-temperature and high-humidity flexural test was implemented in the following manner.

First, samples for evaluation were produced. Specifically, first, the exposed surface of the polarizer film of the laminated optical film and the adhesive surface of the adhesive layer with a release liner attached to one side are bonded together. The lamination was carried out under the environment of 23°C by making a 2kg roller reciprocate once to crimp the surface of the polarizer film and the surface of the adhesive layer of the laminated optical film (the lamination described later was also carried out under the same conditions). Next, after the release liner is peeled off from the adhesive layer, the exposed surface of the adhesive sheet is obtained, and a polyethylene terephthalate (PET) film (product name "DIAFOIL", thickness 125 µm, Mitsubishi Chemical Co., Ltd. Co. Manufactured). Thereby, a multilayer film is obtained. The adhesive layer of the above-mentioned single-sided release liner is produced in the following manner.

First, 100 parts by mass of n-butyl acrylate, 3 parts by mass of acrylic acid, and 0.1 parts by mass of 2-hydroxyethyl acrylate were used as thermal polymerization initiators in a reaction vessel equipped with a reflux cooling pipe, a nitrogen introduction pipe, a thermometer, and a stirrer. A mixture of 0.3 parts by mass of 2,2'-azobisisobutyronitrile and ethyl acetate as a solvent was stirred at 55° C. for 8 hours under a nitrogen atmosphere (polymerization reaction). Thereby, a polymer solution containing an acrylic base polymer was obtained. In the polymer solution, the weight average molecular weight of the acrylic base polymer was about 2.2 million. Next, for the polymer solution, 0.5 parts by mass of a crosslinking agent (product name "CORONATE L", manufactured by Japan Polyurethane) and a silane coupling agent (product name "KMB-403", γ-ring 0.075 parts by mass of oxypropoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) were mixed to prepare an adhesive solution. Next, the adhesive solution was coated on the release-treated surface of the release liner to form a coating film (thickness: 20 µm). The release liner is a polyethylene terephthalate film (thickness 38 µm) with a predetermined release treatment. Next, the coating film on the release liner is dried to form an adhesive layer.

When producing a sample for evaluation, the sample for evaluation is then cut out from the multilayer film prepared in the above-mentioned manner. Specifically, a rectangular sample of 25 mm×100 mm was cut out from the laminated film so that the absorption axis direction of the polarizer film in the sample to be cut out was parallel to the longitudinal direction.

Next, about this sample, the flexure test was implemented with the planar object no-load U-shaped stretching tester (manufactured by YUASA SYSTEM). In this test, the two ends of the long side direction of the sample are respectively installed with flexure fixtures within 20 mm from the end edge of the sample, and then the sample is fixed on the testing machine (the center of the long side direction of the sample is The 60mm area is not fixed). Also, in this test, in a constant temperature and humidity chamber under the conditions of a temperature of 60°C and a relative humidity of 90%, at a deflection speed of 60 rpm, the surface of the sample on the polarizer film side becomes the inside of the deflected form and the non-flexed form. Between the curved forms, the deformation (deflection) is repeated 200,000 times. The deflection form in this test specifically refers to the form in which the axial direction of the bending moment acting on the sample is perpendicular to the absorption axis direction of the polarizer film. In this flexure form, the bending radius of the sample was set to 3 mm, and the bending angle was set to 180°. Then, with regard to the peeling inhibition between the films (transparent protective film, polarizer film) in the flexure test, the case where the number of flexures reached 200,000 without peeling between the films was evaluated as "excellent", and the flexure was evaluated as "excellent". When the number of flexures was more than 80,000 and less than 200,000, peeling was evaluated as "good", and when the number of flexures was less than 80,000, peeling was evaluated as "poor". Table 1 shows the evaluation results.

[Table 1]

X,X': laminated optical film 10: Optical film (1st optical film) 20: Adhesive layer 30: Optical film (2nd optical film) 31: Boundary area 32: Non-boundary area 40: Adhesive raw material ingredients containing part H: Thickness direction T1: The thickness of the adhesive layer T2: The thickness of the part containing the raw material components of the adhesive

Fig. 1 is a schematic cross-sectional view of an embodiment of the laminated optical film of the present invention. Fig. 2 is a partially enlarged cross-sectional view of the laminated optical film shown in Fig. 1 . Fig. 3 is a schematic cross-sectional view of another embodiment of the laminated optical film of the present invention. The laminated optical film of this embodiment includes a second optical film, an adhesive layer, a first optical film, an adhesive layer, and a second optical film in order in the thickness direction.

X:Laminated optical film

10: Optical film (1st optical film)

20: Adhesive layer

30: Optical film (2nd optical film)

H: Thickness direction

Claims (4)

A laminated optical film comprising a first optical film, an adhesive layer and a second optical film sequentially in the thickness direction; The aforementioned adhesive layer is bonded to the aforementioned first optical film and bonded to the aforementioned second optical film; The second optical film has a boundary region on the side of the adhesive layer, and the boundary region contains an adhesive raw material component derived from the adhesive layer; and The ratio of the thickness T2 of the adhesive raw material component containing portion to the thickness T1 of the adhesive layer is 1.01 or more. The adhesive raw material component containing portion is a portion formed by combining the adhesive layer and the boundary region. The laminated optical film according to claim 1, wherein the aforementioned thickness T1 is 5 µm or less. The laminated optical film according to claim 1, wherein the 90° peel strength of the second optical film against the first optical film at 25°C is 0.8 N/15mm or more. The laminated optical film according to any one of claims 1 to 3, wherein the first optical film is a polarizer film.

Images