WO2019216096A1

WO2019216096A1 - Adhesive layer, method for producing same, adhesive sheet, adhesive layer-attached optical film, and image display device

Info

Publication number: WO2019216096A1
Application number: PCT/JP2019/015629
Authority: WO
Inventors: 普史形見; 崇弘野中
Original assignee: 日東電工株式会社
Priority date: 2018-05-11
Filing date: 2019-04-10
Publication date: 2019-11-14
Also published as: JP2019196468A; TW201946995A; CN112074580A; CN116515457A; KR20210009322A; SG11202011147XA; JP2023059986A

Abstract

Provided is an adhesive layer having a first face and a second face which is on the reverse side from the first face, wherein an adhesive composition containing a base polymer forms the base of the entire adhesive layer, the first face has a first refractive index based on the adhesive composition, and the second face has a second refractive index lower than the first refractive index of the first face. This adhesive layer is capable of effectively suppressing internal reflection and has good adhesion even when applied to an optical member having a low refractive index, such as an antireflection film, a light diffusion film, a prism film, a light guide film, a lens film, or a Fresnel lens, lenticular lens, or microlens film.

Description

Adhesive layer, production method thereof, adhesive sheet, optical film with adhesive layer, and image display device

The present invention relates to an adhesive layer and a method for producing the same. Moreover, this invention relates to the adhesive sheet which has the said adhesive layer, and an optical film with an adhesive layer. Furthermore, the present invention relates to an image display device using them.

For example, a display device such as a liquid crystal display device or an organic EL display device has a pressure-sensitive adhesive composition for bonding a polarizing film, a retardation film, a transparent cover member such as a cover glass, and other various optical films to other optical films. Use things. Thus, an optical film laminate having the two optical films is formed by disposing the pressure-sensitive adhesive layer between the two optical films. In the display device, the optical film laminate having such a configuration is disposed, for example, such that the optical film side is the viewing side. In this configuration, when external light is incident from the viewing-side optical film, there is a problem that the incident light is reflected at the interface between the adhesive layer and the non-viewing-side optical film and returns to the viewing side. This problem is particularly noticeable when the incident angle of external light is shallow.

On the other hand, for a backlight unit of an image display device, for example, it has been proposed to use a light diffusion pressure-sensitive adhesive composition containing a (meth) acrylic polymer as a base polymer and containing light diffusing fine particles (Patent Literature). 1).

JP 2014-224964 A

The problem as described above is considered to be caused by the difference in refractive index between the pressure-sensitive adhesive layer and the adherend. For example, an optical member (for example, an antireflection film, a light diffusion film, a light guide film) using a low refractive index material such as an adhesive layer and a fluorine-based resin, polysiloxane, low refractive inorganic particles, porous material, hollow material, etc. And a prism film, a lens film, a Fresnel lens, a lenticular lens, or a micro lens film), a problem arises in visibility due to the internal reflection of incident light at the interface. Since this problem is considered to be caused by the fact that the refractive index of the optical film is lower than that of the pressure-sensitive adhesive layer, it is considered that the above problem can be solved by using a pressure-sensitive adhesive layer having a low refractive index. For example, as a method of forming a pressure-sensitive adhesive layer having a low refractive index with an acrylic pressure-sensitive adhesive, a general acrylic polymer (refractive index is usually 1.47 to 1.52) which is a base polymer and a fluorocarbon monomer unit are used. It is conceivable to use alkyl acrylate (refractive index of around 1.38). However, an adhesive layer having a low refractive index using a base polymer containing the fluoroalkyl acrylate as a monomer unit has a high surface tension and it is difficult to ensure adhesion. Thus, it was extremely difficult to create a pressure-sensitive adhesive layer having a low refractive index (for example, a refractive index of 1.40 or less) while ensuring the adhesiveness of the pressure-sensitive adhesive layer.

On the other hand, the pressure-sensitive adhesive layer formed from the light diffusing pressure-sensitive adhesive composition of Patent Document 1 has a light diffusing function, but the light diffusing fine particles are dispersed in the entire range of the pressure-sensitive adhesive layer. It is difficult to ensure sufficient adhesion with the like.

The present invention can effectively suppress internal reflection even when applied to an optical member having a low refractive index such as an antireflection film, a light diffusion film, a lens film, a Fresnel lens, a lenticular lens, or a microlens film. And it aims at providing the adhesive layer with favorable adhesiveness, and its manufacturing method.

Moreover, this invention provides the adhesive sheet which has the said adhesive layer, Furthermore, it provides the optical film with an adhesive layer which has the said adhesive layer, Furthermore, this invention is with the said adhesive layer or an adhesive layer. An object of the present invention is to provide an image display device having an optical film.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found the following pressure-sensitive adhesive layer and completed the present invention.

That is, the present invention is a pressure-sensitive adhesive layer having a first surface and a second surface opposite to the first surface,
The pressure-sensitive adhesive layer forms the base of the entire pressure-sensitive adhesive layer by a pressure-sensitive adhesive composition containing a base polymer,
The first surface has a first refractive index based on the pressure-sensitive adhesive composition, while the second refractive index of the second surface is lower than the first refractive index of the first surface. Agent layer.

In the pressure-sensitive adhesive layer, the difference between the first refractive index of the first surface and the second refractive index of the second surface is preferably 0.02 to 0.45.

In the pressure-sensitive adhesive layer, the second refractive index of the second surface is preferably 1.45 or less.

As the pressure-sensitive adhesive layer, it is possible to adopt a mode in which a low refractive index material having a refractive index lower than the refractive index of the base polymer is dispersed on the second surface side.

In the pressure-sensitive adhesive layer, the thickness of the region in which the low refractive index material is dispersed is preferably 600 nm or less in the thickness direction from the second surface side in the pressure-sensitive adhesive layer.

In the pressure-sensitive adhesive layer, the base polymer preferably has a refractive index of 1.40 to 1.55, and the low refractive material has a refractive index of 1.10 to 1.45. The difference between the refractive index of the base polymer and the refractive index of the low refractive index material is preferably 0.07 to 0.45.

Examples of the low refractive index material include particles having an average particle diameter of 10 nm to 150 nm.

The low refractive index material is selected from the group consisting of at least one inorganic particle selected from the group consisting of MgF ₂ , CaF ₂ and Na ₃ AlF ₆ , porous silica particles, hollow nanosilica particles, and hollow polymer particles. At least one particle.

The pressure-sensitive adhesive layer preferably has a total light transmittance of 85% or more.

The adhesive layer preferably has a reflectance of 0.5 to 3.5% on the second surface.

In the pressure-sensitive adhesive layer, the difference in reflectance between the first surface and the second surface is preferably 0.1 to 3.5%.

The pressure-sensitive adhesive layer preferably has a gel fraction of 30 to 95% by weight.

The pressure-sensitive adhesive layer preferably has a storage elastic modulus G ′ at 25 ° C. of 0.05 to 0.50 MPa.

The pressure-sensitive adhesive layer preferably has a tan δ peak value of −5 to −50 ° C. when measuring dynamic viscoelasticity at 1 Hz.

The present invention is also a method for producing the pressure-sensitive adhesive layer,
Forming a base pressure-sensitive adhesive layer on the support with a pressure-sensitive adhesive composition containing the base polymer (1),
Preparing a dispersion in which a low refractive index material having a lower refractive index than that of the base polymer is dispersed (2);
In the base adhesive layer, the dispersion or solution is applied to the second surface opposite to the first surface on the support side, and the low refractive index material contained in the dispersion or solution is applied to the base adhesive. A step (3) of infiltrating in the thickness direction from the second surface of the agent layer, and a step (4) of drying the adhesive layer infiltrated with the low refractive index material,
It is related with the manufacturing method of the adhesive layer characterized by including.

The present invention also relates to the pressure-sensitive adhesive layer and the pressure-sensitive adhesive sheet having a support on one side or both sides of the pressure-sensitive adhesive layer.

Further, the present invention is an optical film with an adhesive layer having an optical film and an adhesive layer provided on one side or both sides of the optical film,
The single-sided or double-sided pressure-sensitive adhesive layer is the pressure-sensitive adhesive layer, and the first surface side of the pressure-sensitive adhesive layer is provided on the optical film.

In the optical film with an adhesive layer, a polarizing film is preferably used as the optical film.

The present invention also relates to an optical laminate comprising the optical film with the pressure-sensitive adhesive layer and a low refractive index optical member bonded to the pressure-sensitive adhesive layer of the optical film with the pressure-sensitive adhesive layer.

The present invention also relates to an image display device comprising the pressure-sensitive adhesive layer, the optical film with the pressure-sensitive adhesive layer, or the optical laminate.

The pressure-sensitive adhesive layer of the present invention is different from the diffusion pressure-sensitive adhesive layer in which fine particles are uniformly diffused in the pressure-sensitive adhesive layer, and has different refractive indexes on both sides of a single pressure-sensitive adhesive layer having a first surface and a second surface. The first surface side has a first refractive index based on the pressure-sensitive adhesive composition that forms the base of the entire pressure-sensitive adhesive layer, and the other second surface side has the first refractive index. The second refractive index is lower than the first refractive index of the surface. Thus, since the pressure-sensitive adhesive layer of the present invention has a pressure-sensitive adhesive surface controlled to have a lower refractive index than the refractive index based on the pressure-sensitive adhesive layer, an optical member formed of a low refractive index material (for example, The refractive index difference between the antireflection film, light diffusion film, light guide film, prism film, lens film, Fresnel lens, lenticular lens, microlens film, etc.) can be adjusted. Reflection at the interface with the optical member can be suppressed, and the light extraction efficiency can be improved. When the second surface of the pressure-sensitive adhesive layer of the present invention is applied to a surface uneven shape portion such as a microlens, the surface uneven shape is protected by filling the surface uneven shape portion with the pressure-sensitive adhesive layer. Compared to the case where a void layer is provided on the surface uneven shape portion, the void can be filled without impairing the light extraction efficiency, and scratches and shape damage due to vibration during handling and transportation can be achieved. Can be suppressed. Further, the second surface of the pressure-sensitive adhesive layer of the present invention has a refractive index adjustment region adjusted to a low refractive index, but has a high total light transmittance and a low refractive index region without increasing the haze value. Can be formed. Moreover, in the 1st surface of the adhesive layer of this invention, since the adhesive force which the adhesive layer originally has is maintained, adhesiveness with a general optical film (for example, polarizing film etc.) is also favorable, On the other hand, since the pressure-sensitive adhesive composition forms a base also on the second surface of the pressure-sensitive adhesive layer controlled to have a low refractive index, it ensures adhesion with an optical film formed of a low-refractive index material. Can do.

It is sectional drawing which shows one Embodiment of the adhesive layer of this invention. It is a top view which shows the state of the 2nd surface of the adhesive layer of this invention. It is the schematic which shows the process for producing the adhesive layer of this invention. It is sectional drawing which shows one Embodiment of the adhesive sheet of this invention. It is sectional drawing which shows one Embodiment of the optical film with an adhesive layer of this invention. It is sectional drawing which shows one Embodiment of the optical laminated body of this invention.

Hereinafter, the pressure-sensitive adhesive layer and the like of the present invention will be described with reference to the drawings.

<Adhesive layer>
As shown in FIG. 1, the pressure-sensitive adhesive layer 1 of the present invention has a first surface f1 and a second surface f2 on the opposite side of the first surface f1. Moreover, in the said adhesive layer 1, the base | substrate (matrix) 1a of the adhesive layer 1 whole is formed with the adhesive composition containing a base polymer. The first surface f1 has a first refractive index n1, and the second refractive index n2 of the second surface f2 is designed to be lower than the first refractive index n1. FIG. 1 illustrates a case where a low refractive index material 2 having a refractive index lower than the refractive index of the base polymer is dispersed (distributed) on the base 1a on the second surface f2 side. ing.

The first refractive index n1 of the first surface f1 corresponds to the refractive index of the pressure-sensitive adhesive layer obtained from the pressure-sensitive adhesive composition forming the base 1a in the pressure-sensitive adhesive layer 1 of the present invention. Accordingly, the first refractive index n1 is determined by the pressure-sensitive adhesive composition forming the base 1a. In addition, since the refractive index of the base polymer is substantially the same as the refractive index of the base 1a adhesive layer 1 of the entire adhesive layer 1, the first refractive index n1 of the first surface f1 is approximately the base. Determined by the refractive index of the polymer. The pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer will be described later. For example, the refractive index of a pressure-sensitive adhesive layer formed of a typical acrylic pressure-sensitive adhesive is generally about 1.47 to 1.52. The refractive index of the pressure-sensitive adhesive layer formed of the silicone-based pressure-sensitive adhesive is generally about 1.40.

On the other hand, the second refractive index n2 of the second surface f2 is not particularly limited as long as n1> n2 is satisfied in relation to the first refractive index n1 on the first surface f1 side. It is appropriately determined in consideration of the refractive index of the low refractive index optical film. However, if the difference (n1−n2) between the first refractive index n1 and the second refractive index n2 becomes too large, internal reflection in the pressure-sensitive adhesive layer 1 may occur. ) Is preferably adjusted to 0.02 to 0.45. The difference (n1-n2) is more preferably 0.03 to 0.35, and further preferably 0.03 to 0.25.

The second refractive index n2 of the second surface f2 is preferably, for example, 1.45 or less from the viewpoint of effectively suppressing internal reflection, more preferably 1.4 or less, and further 1 Is preferably 35 or less, and more preferably 1.3 or less. If the second refractive index n2 is 1.4 or less, the second surface side of the pressure-sensitive adhesive layer 1 of the present invention can be used as an alternative to the air layer. On the other hand, the second refractive index n2 is preferably 1.25 or more, and more preferably 1.28 or more, from the viewpoint of maintaining adhesive force. The range of the second refractive index n2 is a range lower than the lower limit value of the refractive index (generally about 1.47 to 1.52) of the pressure-sensitive adhesive layer formed of a typical acrylic pressure-sensitive adhesive.

In the pressure-sensitive adhesive layer 1, as shown in FIG. 1, when the low refractive index material 2 is dispersed on the second surface f2 side, the base polymer in the pressure-sensitive adhesive composition forming the base 1a is dispersed. The refractive index is 1.40 to 1.55, and the refractive index of the low refractive index material 2 dispersed on the second surface a2 side in the substrate 1a is 1.10 to 1.45. preferable. The difference between the refractive index of the base polymer and the refractive index of the low refractive index material 2 is preferably 0.07 to 0.45. The refractive index of the base polymer is more preferably 1.40 to 1.52, and further preferably 1.40 to 1.50. The refractive index of the low refractive index material 2 is preferably 1.14 to 1.42, and more preferably 1.18 to 1.40. The difference between the refractive index of the base polymer and the refractive index of the low refractive index material 2 is preferably 0.07 to 0.35, and more preferably 0.10 to 0.30. The low refractive index material 2 has a lower refractive index, and the refractive index can be lowered with a small addition amount. On the other hand, the difference between the refractive index of the base polymer (adhesive layer 1a) and the refractive index of the low refractive index material 2 is low. Since it tends to increase and scattering (haze) tends to occur, the refractive index difference is preferably adjusted so as not to become too large. The refractive index can be shown as a refractive index value of D line measured in a 23 ° C. environment by spectroscopic ellipsometry when the material is a single layer film.

As the low refractive index material 2, particles having an average particle diameter of 10 nm to 150 nm can be used. Particles having an average particle diameter in the above range are preferable for keeping the haze of the pressure-sensitive adhesive layer 1 low and maintaining a high total light transmittance even when dispersed on the second surface f2 side of the pressure-sensitive adhesive layer 1. . The average particle diameter is preferably 20 nm to 100 nm, more preferably 20 nm to 90 nm. The average particle diameter of the particles is a value measured by a particle size distribution diameter measuring apparatus using a dynamic light scattering method.

Examples of the low refractive index material 2 include MgF ₂ (refractive index 1.38), CaF ₂ (refractive index 1.43: fluorite), Na ₃ AlF (refractive index 1.34: sodium hexafluoroaluminate ( Cryolite)) and the like. These materials (for example, particles) can be used alone or in combination of two or more.

Moreover, as the low refractive index material 2, for example, hollow particles can be used. The hollow particles may be inorganic particles or polymer particles. Since the hollow particles have a void space having a low refractive index in the particles, the refractive index of the hollow particles is lower than the refractive index of the component forming the hollow particles. For example, silica has a refractive index of 1.46, but hollow nanosilica particles (refractive index: 1.24, trade name: thruria 5320, particle size 75 nm, manufactured by JGC Catalysts & Chemicals Co., Ltd.), porous silica particles have low refractive index. It can be used as a material. Other examples include fine hollow polymer particles (refractive index: 1.32, trade name: Techpolymer NH, product number XX-255AA, particle size 80 nm, hollow rate 39%, manufactured by Sekisui Plastics Co., Ltd.). In addition, when the hollow particles are provided on the surface treatment layer having a low refraction, the hollow particles (low refractive index material 2) in the present invention have a problem in strength and scratch resistance because they are hollow materials. Since it is a form added (impregnated) in the agent layer 1, it can be applied without considering the problems of strength and scratch resistance.

As the low refractive index material 2, an oligomer containing a fluoroalkyl group, an oligomer of a polysiloxane resin, or the like can be used.

The thickness of the pressure-sensitive adhesive layer 1 is not particularly limited, but is usually 5 μm to 500 μm, preferably 10 μm to 400 μm, and more preferably 10 μm to 350 μm. Moreover, in FIG. 1, the area | region where the said low refractive index material 2 is disperse | distributing in the said adhesive layer 1 is represented by thickness T from the said 2nd surface f2 side. The thickness T is appropriately designed according to the thickness of the pressure-sensitive adhesive layer, but is usually preferably 600 nm or less, more preferably 300 nm or less, and further preferably 200 nm or less. The thickness T is preferably 10 nm or more, more preferably 15 nm or more, and more preferably 20 nm or more in order to effectively suppress internal reflection when applied to an optical film having a low refractive index. Is preferred.

The region where the low refractive index material 2 relating to the thickness T is dispersed in the pressure-sensitive adhesive layer 1 has an irregular concavo-convex shape in relation to the base (matrix) 1a. Is determined by averaging the measured values of the depth of the concavo-convex shape.

The low refractive index material 2 is distributed on the second surface f2 side in a dispersed state or in a partially aggregated state. The boundary between the region where the low-refractive index material 2 is dispersed and the base 1a where the low-refractive index material 2 is not dispersed has an irregular uneven shape as described with reference to FIG. However, in measuring the thickness T, the range of the depth where 90% of the low refractive index material 2 exists at each measurement position is taken as the measurement value of the thickness T at the measurement position, and the measurement values at a plurality of measurement positions are used. Average.

FIG. 2 is a plan view showing a state of the second surface f2 of the pressure-sensitive adhesive layer 1. FIG. As shown in FIG. 2, the base 1a has a sea-island structure in which the low refractive index material 2 is dispersed in an island shape. The base 1a portion and the low refractive index material 2 portion exist. The area ratio of the low refractive index material 2 on the second surface f2 is preferably in the range of 30 to 99%. The area ratio is the ratio of the area occupied by the low refractive index material 2 to the total area of the square area in a square area having a side of 10 μm to 200 μm, and measurement is performed for a plurality of square areas, and the measured values are averaged. An area ratio is required.

The ratio of the low refractive index material 3 in the pressure-sensitive adhesive layer 1 is such that the first refractive index n1 on the first surface f1 side and the second refractive index n2 on the second surface f2 satisfy the relationship n1> n2. If it does, it will not be restricted in particular.

The total light transmittance of the entire pressure-sensitive adhesive layer 1 of the present invention is preferably 85% or more, more preferably 88% or more, and further preferably 90% or more. The total light transmittance of the pressure-sensitive adhesive layer 1 is preferably as high as possible. Further, the haze value is preferably 1.5% or less, more preferably 1% or less, and still more preferably 0.8% or less. The haze value of the pressure-sensitive adhesive layer 1 is preferably as low as possible. The total light transmittance and haze value of the entire pressure-sensitive adhesive layer 1 are values measured in accordance with JIS K7361.

Further, the reflectance of the second surface of the pressure-sensitive adhesive layer 1 of the present invention is preferably 0.5 to 3.5%. The reflectance of the second surface of the pressure-sensitive adhesive layer 1 of the present invention is lower than the reflectance of the first surface, and the internal reflection can be controlled to be small even in relation to the low refractive index material. The reflectance of the two surfaces is preferably 0.5 to 3.0%, more preferably 0.5 to 2.5%. Further, the difference in reflectance between the first surface and the second surface of the pressure-sensitive adhesive layer 1 of the present invention is preferably 0.1 to 3.5%.

The pressure-sensitive adhesive layer 1 of the present invention is described above on the assumption that the second refractive index n2 of the second surface f2 is designed to be lower than the first refractive index n1. However, the pressure-sensitive adhesive layer 1 of the present invention can be specified by the relationship between the refractive indexes of both surfaces, and the reflectance of the second surface f2 is lower than the reflectance of the first surface f1. It can be understood as a featured invention.

The pressure-sensitive adhesive layer 1 of the present invention preferably has a gel fraction of 30 to 95% by weight. The gel fraction is preferably 30 to 90% by weight, more preferably 35 to 90% by weight, and still more preferably 40 to 90% by weight. When the gel fraction of the pressure-sensitive adhesive layer 1 is within the above range, it has stress relaxation properties and is a preferable aspect in securing followability to unevenness. The gel fraction relates to the base 1a in the pressure-sensitive adhesive layer 1 and does not include the low refractive index material 2.

<Measurement of gel fraction of adhesive layer>
Sample 1 was scraped about 0.2 g from the pressure-sensitive adhesive layer (before penetration of the low refractive index material). The sample 1 was wrapped in a Teflon (registered trademark) film (trade name “NTF1122”, manufactured by Nitto Denko Corporation) having a diameter of 0.2 μm, and then tied with a kite string to obtain a sample 2. The weight of sample 2 before being subjected to the following test was measured, and this was designated as weight A. The weight A is the total weight of the sample 1 (adhesive layer), the Teflon (registered trademark) film, and the kite string. The total weight of the Teflon (registered trademark) film and the kite string was defined as weight B. Next, the sample 2 was put in a 50 ml container filled with ethyl acetate and allowed to stand at 23 ° C. for 1 week. Thereafter, the sample 2 was taken out from the container, dried in a dryer at 130 ° C. for 2 hours to remove ethyl acetate, and the weight of the sample 2 was measured. The weight of Sample 2 after being subjected to the test was measured, and this was designated as weight C. And the gel fraction (weight%) was computed from the following formula.
Gel fraction (% by weight) = (CB) / (AB) × 100

The pressure-sensitive adhesive layer 1 of the present invention preferably has a storage elastic modulus G ′ at 25 ° C. of 0.05 to 0.50 MPa. The storage elastic modulus G ′ is preferably 0.06 to 0.45 MPa, more preferably 0.07 to 0.40 MPa, and still more preferably 0.08 to 0.35 MPa. When the storage elastic modulus G ′ of the pressure-sensitive adhesive layer 1 is within the above range, it is preferable to protect image display devices (LCD, OLED terminals, etc.) that are becoming thinner and to ensure dimensional stability during cutting. It becomes.

The pressure-sensitive adhesive layer 1 of the present invention preferably has a tan δ peak value (glass transition temperature) of −5 to −50 ° C. when measuring dynamic viscoelasticity at 1 Hz. The tan δ peak value is preferably −7 to −50 ° C., more preferably −9 to −45 ° C., and further preferably −10 to −40 ° C. When the tan δ peak value of the pressure-sensitive adhesive layer 1 is within the above range, it becomes a preferable aspect in securing the resistance against a drop impact of the image display device (mobile terminal or the like).

<Measurement of storage elastic modulus G ′ and tan δ peak value of pressure-sensitive adhesive layer>
A plurality of pressure-sensitive adhesive layers were laminated to prepare a test sample having a thickness of about 2 mm. This test sample was punched into a disk shape having a diameter of 7.9 mm, sandwiched between parallel plates, and subjected to dynamic viscoelasticity measurement under the following conditions using “Advanced Rheometric Expansion System (ARES)” manufactured by Rheometric Scientific. From the results, the storage elastic modulus G ′ and tan δ peak value of the pressure-sensitive adhesive layer at 25 ° C. were read.
(Measurement condition)
Frequency: 1Hz
Deformation mode: Torsion Measurement temperature: -70 ° C to 150 ° C
Temperature increase rate: 5 ° C / min

Next, the method for producing the pressure-sensitive adhesive layer of the present invention will be described with reference to FIG.

First, as a step (1), a base pressure-sensitive adhesive layer 1 ′ is formed on a support S with a pressure-sensitive adhesive composition containing a base polymer. Base adhesive layer 1 'forms the base | substrate 1a in the adhesive layer 1 obtained. In the base pressure-sensitive adhesive layer 1 ′, the support 1 side is the first surface f1 ′, and the opposite side is the second surface f2 ′. The method for forming the base pressure-sensitive adhesive layer 1 ′ is not particularly limited, and can be formed by a method usually used in this field. Specifically, the pressure-sensitive adhesive composition is applied to one side of the support S and a coating film formed from the pressure-sensitive adhesive composition is formed by drying, or irradiated with active energy rays such as ultraviolet rays. Can be formed.

The support S is not particularly limited, and various substrates such as a release film and a transparent resin film substrate can be used.

Examples of the constituent material of the release film include resin films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films, porous materials such as paper, cloth, and nonwoven fabric, nets, foam sheets, metal foils, and laminates thereof. Suitable thin leaf bodies and the like can be mentioned, but a resin film is suitably used from the viewpoint of excellent surface smoothness. The release film may be subjected to release and antifouling treatment or antistatic treatment as necessary.

On the other hand, as a step (2), a dispersion 10 in which a low refractive index material 2 having a refractive index lower than the refractive index of the base polymer used in the pressure-sensitive adhesive composition is prepared (not shown). As a dispersion medium used in the dispersion, a material capable of dispersing the low refractive index material 2 and penetrating into the base pressure-sensitive adhesive layer 1 ′ is used. It is selected in a timely manner according to the type of pressure-sensitive adhesive composition forming the layer. The concentration of the low refractive index material in the dispersion medium is preferably adjusted to 0.1 to 10% by weight, for example.

Examples of the dispersion medium include methanol, ethanol, isopropyl alcohol, 1-propanol, n-butanol, 2-butanol, cyclohexanol, t-butyl alcohol, glycerin, ethylene glycol, 2-methyl-2,4-pentadiol. Alcohols such as phenol and parachlorophenol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, cyclopentanone, 2-pentanone, 2-hexanone, 2-heptanone; diethyl ether, tetrahydrofuran, dioxane, anisole, etc. Ethers such as ethyl acetate, butyl acetate and methyl lactate; aromatic hydrocarbons such as benzene, toluene and xylene; aliphatic hydrocarbons such as n-hexane and cyclohexane; Chill formamide, amides such as dimethylacetamide; methyl cellosolve, ethyl cellosolve, cellosolve such as methyl cellosolve acetate and the like. These dispersion media can be used alone or in admixture of two or more. In addition, said solvent is a mere illustration and the solvent used for this invention is not limited to these.

Next, as a step (3), the dispersion 10 is applied to the second surface f2 ′ of the base adhesive layer 1 ′, and the low refractive index material 2 contained in the dispersion 10 is applied to the base adhesive. It penetrates in the thickness direction from the second surface f2 ′ of the agent layer 1 ′. (3) -1 in FIG. 3 shows a state immediately after the dispersion 10 is coated with the base pressure-sensitive adhesive layer 1 ′, and (3) -2 shows a state in which the low refractive index material 2 has penetrated the base pressure-sensitive adhesive layer 1 ′. The second surface f2 ′ side of the base pressure-sensitive adhesive layer 1 ′ is swollen by the dispersion medium of the dispersion liquid 10, and in the process, the low refractive index material 2 in the dispersion liquid 10 enters the base pressure-sensitive adhesive layer 1 ′. To penetrate.

Next, as a step (4), the base pressure-sensitive adhesive layer 1 ′ into which the low refractive index material 2 has penetrated is dried. The pressure-sensitive adhesive layer 1 shown in FIG. 1 can be obtained by evaporating the dispersion medium of the dispersion 10 that has penetrated into the base pressure-sensitive adhesive layer 1 ′ by the drying step. This state is shown in (4) of FIG. The conditions for the drying step are determined according to the type of the dispersion medium.

The region (thickness T) in which the low refractive index material 2 is dispersed in the pressure-sensitive adhesive layer 1 is determined by the relationship between the pressure-sensitive adhesive composition forming the base pressure-sensitive adhesive layer 1 ′ and the dispersion medium of the dispersion liquid 10. . The dispersion medium can be appropriately selected so that the penetration depth becomes the value described above. Further, the coating amount of the dispersion liquid is appropriately set so as to have a desired thickness T.

The dispersion can be applied by, for example, roll coating, kiss roll coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, lip coating, or die coating. An appropriate method such as a filter can be used. The thickness T can be controlled by the dispersion coating method, the concentration of the dispersion, the coating amount, and the like.

<Adhesive composition>
The pressure-sensitive adhesive composition containing the base polymer that forms the base (matrix) 1a of the pressure-sensitive adhesive layer 1 of the present invention will be described.

The adhesive composition is preferably a transparent material having adhesiveness that can be used for optical applications. The pressure-sensitive adhesive composition is appropriately selected from, for example, acrylic pressure-sensitive adhesives, rubber-based pressure-sensitive adhesives, silicone-based pressure-sensitive adhesives, polyester-based pressure-sensitive adhesives, urethane-based pressure-sensitive adhesives, epoxy-based pressure-sensitive adhesives, and polyether-based pressure-sensitive adhesives. Can be used. From the viewpoint of transparency, workability, durability, etc., it is preferable to use an acrylic pressure-sensitive adhesive. A base polymer corresponding to the type of the pressure-sensitive adhesive composition is used. In the present invention, an acrylic pressure-sensitive adhesive containing a (meth) acrylic polymer as a base polymer is preferable.

The acrylic pressure-sensitive adhesive can include, for example, a partial polymer of a monomer component containing alkyl (meth) acrylate and / or a (meth) acrylic polymer obtained from the monomer component. The base polymer of the acrylic pressure-sensitive adhesive includes a partial polymer of a monomer component containing an alkyl (meth) acrylate and / or a (meth) acrylic polymer obtained from the monomer component.

Examples of the alkyl (meth) acrylate include the aforementioned linear or branched alkyl (meth) acrylates having 1 to 24 carbon atoms, and among these, alkyl (meth) having 1 to 9 carbon atoms. Acrylates are preferred, and alkyl (meth) acrylates having 4 to 9 carbon atoms are preferred. The alkyl (meth) acrylate is preferable in terms of easily balancing the adhesive properties. Specific examples of the alkyl (meth) acrylate having 4 to 9 carbon atoms include n-butyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, and isobutyl (meth). Acrylate, n-pentyl (meth) acrylate, isopentyl (meth) acrylate, isohexyl (meth) acrylate, isoheptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, etc. These can be used alone or in combination of two or more.

In the present invention, the alkyl (meth) acrylate having an alkyl group having 1 to 24 carbon atoms at the ester terminal is 40% by weight or more based on the total amount of the monofunctional monomer component forming the (meth) acrylic polymer. It is preferably 50% by weight or more, more preferably 60% by weight or more.

The monomer component may contain a copolymerization monomer other than the alkyl (meth) acrylate as a monofunctional monomer component. A copolymerization monomer can be used as the remainder of the said alkyl (meth) acrylate in a monomer component.

As the copolymerization monomer, for example, a cyclic nitrogen-containing monomer can be included. As said cyclic nitrogen containing monomer, what has a polymerizable functional group which has unsaturated double bonds, such as a (meth) acryloyl group or a vinyl group, and has a cyclic nitrogen structure can be especially used without a restriction | limiting. The cyclic nitrogen structure preferably has a nitrogen atom in the cyclic structure. Examples of cyclic nitrogen-containing monomers include lactam vinyl monomers such as N-vinylpyrrolidone, N-vinyl-ε-caprolactam, and methylvinylpyrrolidone; vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinyl Examples thereof include vinyl monomers having a nitrogen-containing heterocyclic ring such as imidazole, vinyl oxazole and vinyl morpholine. Moreover, the (meth) acryl monomer containing heterocyclic rings, such as a morpholine ring, a piperidine ring, a pyrrolidine ring, a piperazine ring, is mentioned. Specific examples include N-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, N-acryloylpyrrolidine and the like. Among the cyclic nitrogen-containing monomers, lactam vinyl monomers are preferable.

In the present invention, the cyclic nitrogen-containing monomer is preferably 0.5 to 50% by weight, and preferably 0.5 to 40% by weight, based on the total amount of the monofunctional monomer component forming the (meth) acrylic polymer. Is more preferable, and 0.5 to 30% by weight is even more preferable.

The monomer component used in the present invention can contain a hydroxyl group-containing monomer as a monofunctional monomer component. As the hydroxyl group-containing monomer, a monomer having a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group and having a hydroxyl group can be used without particular limitation. Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl ( Hydroxyalkyl (meth) acrylates such as (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate; -Hydroxyalkylcycloalkane (meth) acrylates such as -hydroxymethylcyclohexyl) methyl (meth) acrylate. Other examples include hydroxyethyl (meth) acrylamide, allyl alcohol, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether, and the like. These can be used alone or in combination. Of these, hydroxyalkyl (meth) acrylate is preferred.

In the present invention, the hydroxyl group-containing monomer is preferably 1% by weight or more from the viewpoint of enhancing adhesive force and cohesive force with respect to the total amount of the monofunctional monomer component forming the (meth) acrylic polymer, It is more preferably 2% by weight or more, and further preferably 3% by weight or more. On the other hand, if the amount of the hydroxyl group-containing monomer is too large, the pressure-sensitive adhesive layer may become hard and the adhesive strength may decrease, and the viscosity of the pressure-sensitive adhesive composition may become too high or may be gelled. Therefore, the hydroxyl group-containing monomer is preferably 30% by weight or less, more preferably 27% by weight or less, and more preferably 25% by weight based on the total amount of the monofunctional monomer component forming the (meth) acrylic polymer. % Or less is more preferable.

In addition, the monomer component that forms the (meth) acrylic polymer can contain other functional group-containing monomers as monofunctional monomers, such as carboxyl group-containing monomers and monomers having a cyclic ether group. It is done.

As the carboxyl group-containing monomer, a monomer having a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group and having a carboxyl group can be used without particular limitation. Examples of the carboxyl group-containing monomer include (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid. Can be used alone or in combination. These anhydrides can be used for itaconic acid and maleic acid. Among these, acrylic acid and methacrylic acid are preferable, and acrylic acid is particularly preferable. In addition, a carboxyl group-containing monomer can be arbitrarily used for the monomer component used for manufacture of the (meth) acrylic-type polymer of this invention, On the other hand, it is not necessary to use a carboxyl group-containing monomer.

As a monomer having a cyclic ether group, a monomer having a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group and a cyclic ether group such as an epoxy group or an oxetane group. It can be used without particular limitation. Examples of the epoxy group-containing monomer include glycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate glycidyl ether, and the like. Examples of the oxetane group-containing monomer include 3-oxetanylmethyl (meth) acrylate, 3-methyl-oxetanylmethyl (meth) acrylate, 3-ethyl-oxetanylmethyl (meth) acrylate, and 3-butyl-oxetanylmethyl (meth) acrylate. , 3-hexyl-oxetanylmethyl (meth) acrylate and the like. These can be used alone or in combination.

In the present invention, the carboxyl group-containing monomer and the monomer having a cyclic ether group are preferably 30% by weight or less based on the total amount of the monofunctional monomer component forming the (meth) acrylic polymer, and 27% by weight. % Or less is more preferable, and 25% by weight or less is more preferable.

The monomer component forming the (meth) acrylic polymer of the present invention includes, for example, CH ₂ ═C (R ¹ ) COOR ² (wherein R ¹ is hydrogen or a methyl group, and R ² is the number of carbon atoms). And an alkyl (meth) acrylate represented by 1 to 3 substituted alkyl groups and cyclic cycloalkyl groups.

Here, the substituent of the substituted alkyl group having 1 to 3 carbon atoms as R ² is preferably an aryl group having 3 to 8 carbon atoms or an aryloxy group having 3 to 8 carbon atoms. . The aryl group is not limited, but is preferably a phenyl group.

Examples of such a monomer represented by CH ₂ ═C (R ¹ ) COOR ² include phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, cyclohexyl (meth) acrylate, 3,3,5-trimethylcyclohexyl. (Meth) acrylate, isobornyl (meth) acrylate, etc. are mentioned. These can be used alone or in combination.

In the present invention, the (meth) acrylate represented by CH ₂ ═C (R ¹ ) COOR ² is 50% by weight or less based on the total amount of the monofunctional monomer component forming the (meth) acrylic polymer. 45% by weight or less is preferable, 40% by weight or less is more preferable, and 35% by weight or less is more preferable.

Other copolymerization monomers include vinyl acetate, vinyl propionate, styrene, α-methylstyrene; (meth) acrylic acid polyethylene glycol, (meth) acrylic acid polypropylene glycol, (meth) acrylic acid methoxyethylene glycol, (meth) Glycol acrylic ester monomers such as methoxypolypropylene glycol acrylate; Acrylic ester monomers such as tetrahydrofurfuryl (meth) acrylate, fluorine (meth) acrylate, silicone (meth) acrylate and 2-methoxyethyl acrylate; Monomers, amino group-containing monomers, imide group-containing monomers, N-acryloylmorpholine, vinyl ether monomers and the like can also be used. Moreover, as a copolymerization monomer, the monomer which has cyclic structures, such as terpene (meth) acrylate and dicyclopentanyl (meth) acrylate, can be used.

Further examples include silane monomers containing silicon atoms. Examples of the silane monomer include 3-acryloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 4-vinylbutyltrimethoxysilane, 4-vinylbutyltriethoxysilane, and 8-vinyloctyltrimethoxysilane. , 8-vinyloctyltriethoxysilane, 10-methacryloyloxydecyltrimethoxysilane, 10-acryloyloxydecyltrimethoxysilane, 10-methacryloyloxydecyltriethoxysilane, 10-acryloyloxydecyltriethoxysilane, and the like.

In order to adjust the cohesive strength of the pressure-sensitive adhesive composition, the monomer component that forms the (meth) acrylic polymer of the present invention includes, in addition to the above-described monofunctional monomer, a polyfunctional monomer as necessary. Can be contained.

The polyfunctional monomer is a monomer having at least two polymerizable functional groups having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group, such as (poly) ethylene glycol di (meth) acrylate, (Poly) propylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,2-ethylene Glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,12-dodecanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylol methanetri (meth) acrylate Ester compounds of polyhydric alcohols such as carbonate and (meth) acrylic acid; allyl (meth) acrylate, vinyl (meth) acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate, butyl di (meth) acrylate, hexyl di ( And (meth) acrylate. Among these, trimethylolpropane tri (meth) acrylate, hexanediol di (meth) acrylate, and dipentaerythritol hexa (meth) acrylate can be preferably used. A polyfunctional monomer can be used individually by 1 type or in combination of 2 or more types.

The amount of the polyfunctional monomer used varies depending on the molecular weight, the number of functional groups, etc., but it is preferably used at 3 parts by weight or less, more preferably 2 parts by weight or less, with respect to a total of 100 parts by weight of the monofunctional monomer. 1 part by weight or less is more preferable. Moreover, it does not specifically limit as a lower limit, However It is preferable that it is 0 weight part or more, and it is more preferable that it is 0.001 weight part or more. Adhesive force can be improved when the usage-amount of a polyfunctional monomer exists in the said range.

The production of the (meth) acrylic polymer can be appropriately selected from known production methods such as radiation polymerization such as solution polymerization and ultraviolet (UV) polymerization, various radical polymerizations such as bulk polymerization and emulsion polymerization. Further, the (meth) acrylic polymer obtained may be any of a random copolymer, a block copolymer, a graft copolymer, and the like.

In the present invention, a partial polymer of the monomer component can also be suitably used.

When the (meth) acrylic polymer is produced by radical polymerization, polymerization can be carried out by appropriately adding a polymerization initiator, a chain transfer agent, an emulsifier and the like used for radical polymerization to the monomer component. The polymerization initiator, chain transfer agent, emulsifier and the like used for the radical polymerization are not particularly limited and can be appropriately selected and used. In addition, the weight average molecular weight of a (meth) acrylic-type polymer can be controlled by the usage-amount of a polymerization initiator and a chain transfer agent, and reaction conditions, and the usage-amount is suitably adjusted according to these kinds.

For example, in solution polymerization or the like, for example, ethyl acetate, toluene or the like is used as a polymerization solvent. As a specific example of solution polymerization, the reaction is carried out in an inert gas stream such as nitrogen and a polymerization initiator is added, and the reaction is usually performed at about 50 to 70 ° C. under reaction conditions for about 5 to 30 hours.

Further, when the (meth) acrylic polymer is produced by radiation polymerization, it can be produced by polymerizing the monomer component by irradiating the monomer component with radiation such as an electron beam or ultraviolet (UV). When performing the ultraviolet polymerization, it is preferable to contain a photopolymerization initiator in the monomer component because of the advantage that the polymerization time can be shortened.

(Silane coupling agent)
Furthermore, the pressure-sensitive adhesive composition of the present invention can contain a silane coupling agent. The amount of the silane coupling agent is preferably 1 part by weight or less, more preferably 0.01 to 1 part by weight, based on 100 parts by weight of the base polymer (for example, the (meth) acrylic polymer). More preferred is 0.02 to 0.6 parts by weight.

(Crosslinking agent)
The pressure-sensitive adhesive composition of the present invention can contain a crosslinking agent. Examples of crosslinking agents include isocyanate crosslinking agents, epoxy crosslinking agents, silicone crosslinking agents, oxazoline crosslinking agents, aziridine crosslinking agents, silane crosslinking agents, alkyletherified melamine crosslinking agents, metal chelate crosslinking agents, Crosslinkers such as oxides are included. A crosslinking agent can be used alone or in combination of two or more. Among these, an isocyanate type crosslinking agent is preferably used.

The crosslinking agent may be used alone or in combination of two or more, but the total content is a monofunctional monomer that forms a (meth) acrylic polymer. The amount is preferably 5 parts by weight or less, more preferably 0.01 to 5 parts by weight, further preferably 0.01 to 4 parts by weight, and 0.02 to 3 parts by weight with respect to 100 parts by weight of the component. Particularly preferred.

(Other additives)
The pressure-sensitive adhesive composition of the present invention may contain appropriate additives in addition to the above components depending on the application. For example, viscosity modifiers, release modifiers, tackifiers (for example, rosin derivative resins, polyterpene resins, petroleum resins, oil-soluble phenol resins, etc., solid, semi-solid, or liquid at room temperature), plasticizers, softening Agents, pigments, colorants (pigments, dyes, etc.), pH adjusters (acids or bases), rust inhibitors, anti-aging agents, antioxidants, light stabilizers, ultraviolet absorbers, and the like.

The pressure-sensitive adhesive sheet of the present invention has a support on one side or both sides of the pressure-sensitive adhesive layer 1 and the pressure-sensitive adhesive layer 1. FIG. 4 shows a case where the pressure-sensitive adhesive layer 1 has a support 3a on the first surface f1 and a support 3b on the second surface f2. As the supports 3a and 3b, the same support as the support S used in the pressure-sensitive adhesive layer 1 shown in FIG. 3 can be used. Moreover, the support body S used in the manufacturing method of the adhesive layer 1 shown in FIG. The support 3b can be appropriately provided on the second surface f2 of the pressure-sensitive adhesive layer 1 after the pressure-sensitive adhesive layer 1 is manufactured by the manufacturing method shown in FIG.

The optical film A with an adhesive layer of the present invention has an optical film 4 and an adhesive layer 1 provided on one side or both sides of the optical film 4. The pressure-sensitive adhesive layer 1 is provided on either one side or both sides of the optical film 4. As for the adhesive layer 1, the 1st surface f1 side of the said adhesive layer 1 is provided in the said optical film 4. FIG. When the pressure-sensitive adhesive layer 1 is provided on one side of the optical film 4, a normal pressure-sensitive adhesive layer can be provided on the other side. In FIG. 5, the pressure-sensitive adhesive layer 1 is provided only on one side of the optical film 4. FIG. 5 shows a case where the support 3 b is provided on the second surface f <b> 2 of the pressure-sensitive adhesive layer 1.

<Optical film>
As an optical film, what is used for formation of image display apparatuses, such as a liquid crystal display device, is used, for example, The kind in particular is not restrict | limited. For example, a polarizing film is mentioned as an optical film. A polarizing film having a transparent protective film on one or both sides of a polarizer is generally used.

<Polarizing film>
Examples of the polarizing film include those having a transparent protective film on at least one surface of a polarizer.

The polarizer is not particularly limited, and various types can be used. Examples of polarizers include dichroic iodine and dichroic dyes on hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films. Examples thereof include polyene-based oriented films such as those obtained by adsorbing substances and uniaxially stretched, polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products. Among these, a polarizer composed of a polyvinyl alcohol film and a dichroic substance such as iodine is preferable. The thickness of these polarizers is not particularly limited, but is generally about 5 to 80 μm.

A polarizer obtained by dyeing a polyvinyl alcohol film with iodine and uniaxially stretching can be prepared, for example, by dyeing a polyvinyl alcohol film in an iodine aqueous solution and stretching it 3 to 7 times the original length. it can. If necessary, it can be immersed in an aqueous solution of potassium iodide or the like which may contain boric acid, zinc sulfate, zinc chloride or the like. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed before dyeing. In addition to washing the polyvinyl alcohol film surface with stains and antiblocking agents by washing the polyvinyl alcohol film with water, it also has the effect of preventing unevenness such as uneven dyeing by swelling the polyvinyl alcohol film. is there. Stretching may be performed after dyeing with iodine, may be performed while dyeing, or may be dyed with iodine after stretching. The film can be stretched even in an aqueous solution of boric acid or potassium iodide or in a water bath.

In the present invention, a thin polarizer having a thickness of 10 μm or less can also be used. From the viewpoint of thinning, the thickness is preferably 1 to 7 μm. Such a thin polarizer is preferable in that the thickness unevenness is small, the visibility is excellent, the dimensional change is small, the durability is excellent, and the thickness of the polarizing film can be reduced.

As a thin polarizer, representatively, Japanese Patent Application Laid-Open No. 51-069644, Japanese Patent Application Laid-Open No. 2000-338329, International Publication No. 2010/100917 pamphlet, Japanese Patent No. 4751481, and Japanese Patent Application Laid-Open No. 2012-2012. A thin polarizing film described in Japanese Patent No. 073563 can be given. These thin polarizing films can be obtained by a production method including a step of stretching and dyeing a polyvinyl alcohol-based resin (hereinafter also referred to as PVA-based resin) layer and a stretching resin substrate in the state of a laminate. With this production method, even if the PVA-based resin layer is thin, it can be stretched without problems such as breakage due to stretching by being supported by the stretching resin substrate.

As the thin polarizing film, International Publication No. 2010/100917 pamphlet in that it can be stretched at a high magnification and the polarization performance can be improved among the production methods including the step of stretching in the state of a laminate and the step of dyeing. Or obtained by a production method including a step of stretching in a boric acid aqueous solution as described in Japanese Patent No. 4751481 and Japanese Patent Application Laid-Open No. 2012-0753563, and particularly, Japanese Patent No. 4751481 and Japanese Patent Application Laid-Open No. 2012-2012. What is obtained by the manufacturing method including the process of extending | stretching in the air auxiliary before extending | stretching in the boric-acid aqueous solution which is described in 073563 gazette is preferable.

As a material constituting the transparent protective film, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy and the like is used. Specific examples of such thermoplastic resins include cellulose resins such as triacetyl cellulose, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth) acrylic resins, cyclic Examples thereof include polyolefin resins (norbornene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. A transparent protective film is bonded to one side of the polarizer by an adhesive layer. On the other side, as a transparent protective film, (meth) acrylic, urethane-based, acrylurethane-based, epoxy-based, silicone A thermosetting resin such as a system or an ultraviolet curable resin can be used. One or more kinds of arbitrary appropriate additives may be contained in the transparent protective film. Examples of the additive include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a mold release agent, a coloring inhibitor, a flame retardant, a nucleating agent, an antistatic agent, a pigment, and a coloring agent. The content of the thermoplastic resin in the transparent protective film is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, still more preferably 60 to 98% by weight, and particularly preferably 70 to 97% by weight. . When content of the said thermoplastic resin in a transparent protective film is 50 weight% or less, there exists a possibility that the high transparency etc. which a thermoplastic resin originally has cannot fully be expressed.

The thickness of the transparent protective film can be appropriately determined, but is generally about 1 to 500 μm from the viewpoints of workability such as strength and handleability, and thin film properties.

A functional layer such as a hard coat layer, an antireflection layer, or an antisticking layer can be formed on the surface of the transparent protective film to which the polarizer is not adhered, and a treatment for diffusion or antiglare is performed. It may be.

The adhesive used for laminating the polarizer and the transparent protective film is not particularly limited as long as it is optically transparent, and water-based, solvent-based, hot-melt-based, radical curable, and cationic curable types are used. However, water-based adhesives or radical curable adhesives are suitable.

In addition, as an optical film, it is used for forming a liquid crystal display device such as a reflection plate, an anti-transmission plate, a retardation film (including wavelength plates such as 1/2 and 1/4), a visual compensation film, and a brightness enhancement film. And an optical layer that may be formed. These can be used alone as an optical film, or can be laminated on the polarizing film for practical use to use one layer or two or more layers. A retardation film can also be used as the transparent protective film. As the retardation film, a film obtained by stretching / shrinking a polymer film or a film obtained by aligning and fixing a liquid crystal material can be appropriately used depending on the purpose.

An optical film obtained by laminating the optical layer on a polarizing film can be formed by a method of laminating separately sequentially in the manufacturing process of a liquid crystal display device or the like. There is an advantage that the manufacturing process of a liquid crystal display device or the like can be improved because of excellent stability and assembly work. For the lamination, an appropriate adhesive means such as an adhesive layer can be used. When bonding the polarizing film and the other optical layer, their optical axes can be set at an appropriate arrangement angle in accordance with a target retardation characteristic or the like.

The optical laminate B of the present invention includes an optical film A with an adhesive layer and an optical member 5 having a low refractive index bonded to the adhesive layer 1 of the optical film A with an adhesive layer. The optical member 5 is provided on the second surface f2 side of the pressure-sensitive adhesive layer 1. The optical layered body B shown in FIG. 6 has the optical member 5 attached to the pressure-sensitive adhesive layer 1 after peeling the support 3b (for example, a release film) from the optical film A with the pressure-sensitive adhesive layer shown in FIG. The case of being combined is illustrated. Examples of the optical member 5 include an antireflection film, a light diffusion film, a prism film, a light guide film, a lens film, a Fresnel lens, a lenticular lens, and a microlens film.

The optical film or optical laminate with an adhesive layer of the present invention can be preferably used for forming various image display devices such as liquid crystal display devices. The liquid crystal display device can be formed according to the conventional method. That is, a liquid crystal display device is generally formed by assembling a drive circuit by appropriately assembling components such as a display panel such as a liquid crystal cell and an optical film with an adhesive layer, or an optical laminate and an illumination system as required. However, in the present invention, there is no particular limitation except that the optical film with the pressure-sensitive adhesive layer or the optical laminate according to the present invention is used, and it can conform to the conventional one. As the liquid crystal cell, an arbitrary type such as an arbitrary type such as a TN type, STN type, π type, VA type, or IPS type can be used.

Appropriate liquid crystal display devices such as a liquid crystal display device in which an optical film with an adhesive layer or an optical laminate is disposed on one or both sides of a display panel such as a liquid crystal cell, or a backlight or reflector used in an illumination system are formed. can do. In that case, the optical film or optical laminated body with an adhesive layer by this invention can be installed in the one side or both sides of display panels, such as a liquid crystal cell. When optical films are provided on both sides, they may be the same or different. Furthermore, when forming a liquid crystal display device, for example, a single layer or a suitable layer of suitable components such as a diffusion layer, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusion sheet, and a backlight, Two or more layers can be arranged.

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. In addition, all the parts and% in each example are based on weight. The room temperature standing conditions not specifically defined below are all 23 ° C. and 65% RH.

(Release film)
A 38 μm thick polyester film (trade name: Diafoil MRF, manufactured by Mitsubishi Resin Co., Ltd.) having one surface peeled with silicone was used.

Comparative Example 1
(Preparation of pressure-sensitive adhesive composition (A))
2-ethylhexyl acrylate (2EHA) 41 parts by weight, isostearyl acrylate (ISTA) 41 parts by weight, N-vinyl-2-pyrrolidone (NVP) 14 parts by weight, N-2-hydroxybutyl acrylate (4HBA) 4 parts by weight, 2 A seed photopolymerization initiator (trade name: Irgacure 184, manufactured by BASF) 0.035 parts by weight and a photopolymerization initiator (trade name: Irgacure 651, manufactured by BASF) 0.035 parts by weight are charged into a four-necked flask. A monomer mixture was prepared. Next, this monomer mixture was partially photopolymerized by exposing it to ultraviolet rays under a nitrogen atmosphere to obtain a partially polymerized product (acrylic polymer syrup) having a polymerization rate of about 10% by weight. To 100 parts by weight of the acrylic polymer syrup thus obtained, 0.025 part by weight of trimethylolpropane triacrylate (TMPTA), a silane coupling agent (trade name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) After adding 0.3 part), these were uniformly mixed to prepare an adhesive composition (A).

(Manufacture of adhesive layer (A))
The pressure-sensitive adhesive composition (A) was applied on the release-treated surface of the release film so that the thickness after forming the pressure-sensitive adhesive layer was 100 μm to form a coating layer. Next, another release film was coated on the surface of the coating layer so that the release treatment surface was on the coating layer side. Thereafter, UV irradiation is performed under the conditions of illuminance: 6.5 mW / cm ² , light quantity: 2000 mJ / cm ² , peak wavelength: 350 nm, and the coating layer is photocured to form the pressure-sensitive adhesive layer (A). A pressure-sensitive adhesive sheet (base-less type, pressure-sensitive adhesive layer thickness: 100 μm) in which release films were provided on both surfaces of the layer (A) was produced. The refractive index (n _D ) of D line measured by an Abbe refractometer of the pressure-sensitive adhesive layer (A) in an environment of 23 ° C. was 1.48, and the gel fraction was 67%.

Comparative Example 2
(Preparation of pressure-sensitive adhesive composition (B))
Photopolymerization started on a monomer mixture composed of 76 parts by weight of 2-ethylhexyl acrylate (2EHA), 18 parts by weight of N-vinyl-2-pyrrolidone (NVP), and 16 parts by weight of 2-hydroxyethyl acrylate (HEA). As an agent, 1-hydroxycyclohexyl phenyl ketone (trade name: Irgacure 184, having an absorption band at a wavelength of 200 to 370 nm, manufactured by BASF) 0.050 part by weight, 2,2-dimethoxy-1,2-diphenylethane-1 -ON (trade name: Irgacure 651, having an absorption band at a wavelength of 200 to 380 nm, manufactured by BASF) 0.050 parts by weight, and then viscosity (measurement conditions: BH viscometer No. 5 rotor, 10 rpm, measurement temperature) (30 ° C) is irradiated with ultraviolet rays until it reaches about 20 Pa · s, and a part of the monomer component is polymerized. A repolymer composition (polymerization rate: 9%) was obtained. Next, 0.060 parts by weight of hexanediol diacrylate (HDDA) and 0.3 parts by weight of a silane coupling agent (trade name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) are added to the prepolymer composition. And mixed to obtain an adhesive composition (b).

(Preparation of pressure-sensitive adhesive composition (B))
2,4-, which was dissolved in butyl acrylate to a solid content of 15% with respect to the pressure-sensitive adhesive composition (b) obtained above (the monomer component forming the acrylic polymer was 100 parts by weight). Bis-[{4- (4-ethylhexyloxy) -4-hydroxy} -phenyl] -6- (4-methoxyphenyl) -1,3,5-triazine (trade name: Tinosorb S, absorption maximum wavelength of absorption spectrum) : 346 nm, manufactured by BASF Japan Ltd.) 0.8 part by weight (solid content weight) and bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide (trade name: Irgacure 819, absorption band at a wavelength of 200 to 450 nm) The pressure-sensitive adhesive composition (B) was obtained by adding and stirring 0.3 parts by weight of BASF Japan).

(Manufacture of adhesive layer (B))
The pressure-sensitive adhesive composition (B) was applied onto the release-treated surface of the release film so that the thickness after forming the pressure-sensitive adhesive layer was 150 μm to form a coating layer. Next, another release film was coated on the surface of the coating layer so that the release treatment surface was on the coating layer side. Thereafter, UV irradiation was performed under the conditions of illuminance: 6.5 mW / cm ² , light quantity: 2000 mJ / cm ² , peak wavelength: 350 nm, and the coating layer was photocured to form the pressure-sensitive adhesive layer (B). A pressure-sensitive adhesive sheet (baseless type, pressure-sensitive adhesive layer thickness: 150 μm) having release films provided on both sides of the agent layer (B) was produced. The refractive index (n _D ) of D line measured by an Abbe refractometer of the pressure-sensitive adhesive layer (B) in an environment of 23 ° C. was 1.49, and the gel fraction was 88%.

Comparative Example 3
(Preparation of pressure-sensitive adhesive composition (C))
In a separable flask equipped with a thermometer, stirrer, reflux condenser and nitrogen gas inlet tube, 95 parts by weight of butyl acrylate (BA), 5 parts by weight of acrylic acid (AA), azobisisobutyronitrile 0 as a polymerization initiator Then, 2 parts by weight and 233 parts by weight of ethyl acetate were added, and then nitrogen substitution was performed for about 1 hour while flowing nitrogen gas and stirring. Thereafter, the flask was heated to 60 ° C. and reacted for 7 hours to obtain an acrylic polymer having a weight average molecular weight (Mw) of 1.1 million. To the acrylic polymer solution (with a solid content of 100 parts by weight), 0.8 parts by weight of trimethylolpropane tolylene diisocyanate (trade name: Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.) as an isocyanate crosslinking agent, A pressure-sensitive adhesive composition (C: solution) was prepared by adding 0.1 part by weight of a silane coupling agent (trade name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.).

(Manufacture of adhesive layer (C))
The pressure-sensitive adhesive composition (C: solution) was applied on the release-treated surface of the release film so that the thickness after drying was 23 μm, and then dried at 100 ° C. for 3 minutes to form a solvent. Was removed to obtain a pressure-sensitive adhesive layer (C). Then, the crosslinking process was performed by heating at 50 degreeC for 48 hours. The exposed surface of the obtained pressure-sensitive adhesive layer (C) is covered with another release film so that the release-treated surface is on the exposed surface side, and the release film is formed on both surfaces of the pressure-sensitive adhesive layer (C). A pressure-sensitive adhesive sheet (baseless type, pressure-sensitive adhesive layer thickness: 23 μm) was prepared. The refractive index (n _D ) of D line measured by an Abbe refractometer of the pressure-sensitive adhesive layer (C) in an environment of 23 ° C. was 1.47, and the gel fraction was 82%.

Comparative Example 4
(Preparation of pressure-sensitive adhesive composition (D))
In a separable flask equipped with a thermometer, a stirrer, a reflux condenser, and a nitrogen gas introduction tube, 99 parts by weight of butyl acrylate (BA) as a monomer component, 1 part by weight of 4 hydroxybutyl acrylate (4HBA), and azo as a polymerization initiator After 0.2 parts by weight of bisisobutyronitrile and ethyl acetate as a polymerization solvent were added so as to have a solid content of 30% by weight, nitrogen substitution was performed for about 1 hour while flowing nitrogen gas and stirring. Thereafter, the flask was heated to 60 ° C. and reacted for 7 hours to obtain an acrylic polymer having a weight average molecular weight (Mw) of 1.1 million. To this acrylic polymer solution (solid content 100 parts), 0.11 part of trimethylolpropane xylylene diisocyanate (“Takenate D110N” manufactured by Mitsui Chemicals, Inc.) as an isocyanate crosslinking agent, a silane coupling agent (Shin-Etsu Chemical ( 0.1 parts of “KBM-403” manufactured by the same company) was added to prepare a pressure-sensitive adhesive composition (D: solution).

(Manufacture of adhesive layer (D))
The pressure-sensitive adhesive composition (D: solution) was applied onto the release-treated surface of the release film so that the thickness after drying was 20 μm, and then dried at 120 ° C. for 3 minutes to remove the solvent. Thus, an adhesive layer (D) was obtained. Then, the crosslinking process was performed by heating at 50 degreeC for 48 hours. The exposed surface of the obtained pressure-sensitive adhesive layer (D) is coated with another release film so that the release-treated surface is on the exposed surface side, and the release film is formed on both surfaces of the pressure-sensitive adhesive layer (D). A pressure-sensitive adhesive sheet (baseless type, pressure-sensitive adhesive layer thickness: 23 μm) was prepared. The refractive index (n _D ) of D line measured by an Abbe refractometer of the pressure-sensitive adhesive layer (D) in an environment of 23 ° C. was 1.47, and the gel fraction was 75%.

Example 1
(Preparation of dispersion containing low refractive index particles)
As a dispersion containing low refractive index particles, hollow nanosilica particles (hollow particles, refractive index: 1.24, average primary particle size: 75 nm, trade name: Thruria 5320, manufactured by JGC Catalysts & Chemicals Co., Ltd.) are used as a dispersion medium ( (Methyl ethyl ketone / methyl isobutyl ketone = 9/1: volume ratio) to prepare a dispersion having a particle concentration of 1.5% by weight.

(Manufacture of pressure-sensitive adhesive layer with adjusted refractive index)
One release film of the pressure-sensitive adhesive sheet obtained in Comparative Example 1 was peeled off. On the surface of the exposed pressure-sensitive adhesive layer (A), the above dispersion is applied to a bar coater RDS No. 1 so that the refractive index adjustment region has a thickness of about 20 nm to 150 nm. After coating at 3, it was dried in a drying oven at 110 ° C. for 180 seconds. Next, a second release film was newly bonded to the surface of the pressure-sensitive adhesive layer (A) in which the hollow nanosilica particles were dispersed to obtain a pressure-sensitive adhesive sheet. In addition, let the release film on the opposite side be a 1st release film with respect to a 2nd release film.

Examples 2-8
Example 1 except that the type of the pressure-sensitive adhesive layer and the type of dispersion (the type of low refractive index particles, the average particle diameter thereof, the type of dispersion medium, and the particle concentration) were changed as shown in Table 1. In the same manner as in No. 1, a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer with an adjusted refractive index was produced.
When the target thickness of the refractive index adjustment region after drying is about 150 to 300 nm or more, bar coater RDS No. 5 is used, and the target thickness of the refractive index adjustment region after drying is 20 to 150 nm. In the case of grade, bar coater RDS No. 3 was used.

(Evaluation)
Table 1 shows the results of the following evaluations performed on the pressure-sensitive adhesive layers (pressure-sensitive adhesive sheets) obtained in Examples and Comparative Examples.

<Measurement of average surface refractive index>
The average surface refractive index of the pressure-sensitive adhesive layer (refractive index adjusting region side: second surface) obtained in the examples was measured using a spectroscopic ellipsometer (EC-400, manufactured by JA Woolam) at sodium D line (589 nm). The refractive index was measured. From the pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples, the release films on both sides were peeled off, and the dispersion liquid was applied in a state where the blackboard was bonded to the surface where the dispersion liquid was not applied (first surface). The average refractive index of the surface (second surface) was measured. In the pressure-sensitive adhesive sheet of the comparative example, the average refractive index of the pressure-sensitive adhesive layer surface was measured in a state where both release sheets were peeled off and a blackboard was bonded to one surface. The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of the comparative example has the same refractive index on both sides.

<Measurement of thickness of refractive index adjustment region>
The cross section in the depth direction of the pressure-sensitive adhesive layer was adjusted, and TEM observation was performed. The thickness of the refractive index adjustment region was measured from the obtained TEM image (direct magnification: 3000 to 30000 times). The thickness of the refractive index adjustment region is an average value of the unevenness of the interface between the region where the particles are dispersed and the region where the particle is not dispersed in the pressure-sensitive adhesive layer. The binarized image processing was performed with image processing software (ImageJ), and the thickness of the region where 90% (area) of the particles existed was determined.

<Total light transmittance, haze>
The second release film (the second surface side of the pressure-sensitive adhesive layer) was peeled off from the pressure-sensitive adhesive sheet obtained in the examples, and a slide glass (trade name: white polishing No. 1, thickness: 0.8 to 1) 0.0 mm, total light transmittance: 92%, haze: 0.2%, manufactured by Matsunami Glass Industry Co., Ltd.). Furthermore, the other 1st release film was peeled and the test piece which has a layer structure of an adhesive layer (refractive index adjustment area | region is a slide glass side) / slide glass was produced. On the other hand, in the pressure-sensitive adhesive layer of the comparative example, one release film is peeled off and bonded to the same slide glass as described above, and the other release film is peeled off to form a pressure-sensitive adhesive layer / slide glass layer structure. A test piece was prepared. The total light transmittance and haze value in the visible light region of the test piece were measured using a haze meter (device name: HM-150, manufactured by Murakami Color Research Laboratory).

<Adhesiveness>
A sheet piece having a length of 100 mm and a width of 20 mm was cut out from the pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples. Next, from the sheet piece obtained from the pressure-sensitive adhesive sheet of the example, the first release film (side on which the dispersion liquid was not applied in the pressure-sensitive adhesive layer) was peeled off, and then the PET film (product) Name: Lumirror S-10, thickness: 25 μm, manufactured by Toray Industries, Inc.) was attached (backed). Next, the second release film is peeled off, and is bonded to a glass plate as a test plate (trade name: soda lime glass # 0050, manufactured by Matsunami Glass Industry Co., Ltd.) under a 2 kg roller, one reciprocating pressure condition. A sample composed of a test plate / adhesive layer (first side is PET side) / PET film was prepared. On the other hand, the sheet piece obtained from the pressure-sensitive adhesive sheet of the comparative example was peeled off one release film, and then, on the pressure-sensitive adhesive layer surface, the same PET film was peeled off, and then the other release film was peeled off. A sample was prepared using the same test plate. The obtained sample was autoclaved (50 ° C., 0.5 MPa, 15 minutes), and then 23 ° C., 50% R.D. H. And allowed to cool for 30 minutes. After allowing to cool, a tensile tester (device name: Autograph AG-IS, manufactured by Shimadzu Corporation) was used, and the temperature was 23 ° C. and 50% R.D. according to JIS Z0237. H. Under the above conditions, the pressure-sensitive adhesive sheet (pressure-sensitive adhesive layer / PET film) was peeled off from the test plate under the conditions of a tensile speed of 300 mm / min and a peeling angle of 180 °, and the 180 ° peel-off adhesive strength (N / 20 mm) was measured.

<Measurement of surface reflectance>
The surface (second surface) on which the dispersion liquid of the pressure-sensitive adhesive layer obtained in the examples was applied was used as a reflectance measurement surface. The first release film (the side where the dispersion liquid was not applied in the pressure-sensitive adhesive layer) was peeled off from the pressure-sensitive adhesive sheet obtained in the example, and a black acrylic plate (trade name “CLAREX”, manufactured by Nitto Resin Co., Ltd.) was attached. Then, the second release film (the side on which the dispersion liquid was applied in the pressure-sensitive adhesive layer) was peeled off, and the peeled surface was used as a sample for measuring surface reflectance. On the other hand, for the pressure-sensitive adhesive layer obtained in the comparative example, after peeling off one release film from the pressure-sensitive adhesive sheet, after laying on the same black acrylic plate, peeling off the other release film, The peeled surface was used as a sample for surface reflectance measurement. The surface reflectance (Y value) was measured with a reflection type spectrophotometer (U4100, manufactured by Hitachi High-Technologies Corporation).

<Measurement of internal reflection suppression rate (transmission improvement effect)>
After peeling the second release film (the side on which the dispersion liquid was applied in the pressure-sensitive adhesive layer) from the pressure-sensitive adhesive sheet obtained in the examples, the surface of the pressure-sensitive adhesive layer had a refractive index of 1.36 on the triacetyl cellulose film. The laminated film on which the low refractive index layer was formed was bonded to the low refractive layer side so that the low refractive index adjustment region of the pressure-sensitive adhesive layer was in contact with the low refractive index layer on the laminated film. Next, the first release film was peeled off, and a slide glass (trade name: white polishing No. 1, thickness: 0.8 to 1.0 mm, total light transmittance: 92%, Haze: 0.2%, manufactured by Matsunami Glass Industry Co., Ltd.). Thus, a test piece having a layer configuration of triacetyl cellulose film / low refractive index layer / adhesive layer (second surface is the low refractive index layer side) / slide glass was produced. On the other hand, for the pressure-sensitive adhesive layer obtained in the comparative example, one release film was peeled off from the pressure-sensitive adhesive sheet, and then the same as above, triacetyl cellulose film / low refractive index layer / pressure-sensitive adhesive layer / slide glass A test piece having the following layer structure was prepared.

The internal reflection suppression rate (transmission improvement effect) was calculated based on the following equation by measuring the transmittance of the test piece prepared above. In the following formula, “transmittance without particles (%)” is the reflectance of the test piece of the comparative example. That is, the internal reflection suppressing effect (transmittance improving effect) is an index indicating how much the internal reflectance can be reduced by having the refractive index adjustment layer.
Internal reflection suppression rate (%) = "Transmittance (%)"-"Transmittance without particles (%)"

In Table 1,
(X1) Hollow nanosilica particles: Refractive index 1.24 (trade name: Thruria 5320, particle size 75 nm, manufactured by JGC Catalysts and Chemicals)
(X2) Hollow polymer fine particles: Refractive index 1.32 (trade name: Techpolymer NH product number XX-255AA, particle size 80 nm, manufactured by Sekisui Plastics Co., Ltd.)
(X3) Hollow polymer fine particles: Refractive index 1.33 (trade name: Techpolymer NH product number XX-260AA, particle size 60 nm, manufactured by Sekisui Plastics Co., Ltd.)
(Y1) MgF ₂ : 1.38, average primary particle size: 40 nm, manufactured by CIK Nanotech Co., Ltd. (Y2) Na ₃ AlF ₆ : 1.34, average primary particle size: 50 nm, manufactured by CIK Nanotech Co., Ltd.
MEK / MIBK methyl ethyl ketone / methyl isobutyl ketone = 9/1 (volume ratio),
Ethanol / MIBK ethanol / methyl isobutyl ketone = 9/1 (volume ratio),
IPA isopropyl alcohol,
Indicates.

1... Adhesive layer 1a ... Base of the entire adhesive layer (matrix)
2 .... Low refractive index material f1 ... first surface f2 of adhesive layer ... second surface T of adhesive layer ...... thickness S of refractive index adjustment region ... support 3a ... support 3b ... support 4 ... optical film 5 ... low refractive optical member 10 ... dispersion

Claims

A pressure-sensitive adhesive layer having a first surface and a second surface opposite to the first surface,
The pressure-sensitive adhesive layer forms the base of the entire pressure-sensitive adhesive layer by a pressure-sensitive adhesive composition containing a base polymer,
The first surface has a first refractive index based on the pressure-sensitive adhesive composition, while the second refractive index of the second surface is lower than the first refractive index of the first surface. Agent layer.
3. The pressure-sensitive adhesive layer according to claim 1, wherein a difference between the first refractive index of the first surface and the second refractive index of the second surface is 0.02 to 0.45.
The pressure-sensitive adhesive layer according to any one of claims 1 to 3, wherein the second refractive index of the second surface is 1.45 or less.
4. The low-refractive index material having a refractive index lower than the refractive index of the base polymer is dispersed on the second surface side in the pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer described.
The pressure-sensitive adhesive layer according to claim 4, wherein the thickness of the region where the low refractive index material is dispersed is 600 nm or less in the thickness direction from the second surface side of the pressure-sensitive adhesive layer.
6. The pressure-sensitive adhesive layer according to claim 4, wherein the refractive index of the base polymer is 1.40 to 1.55, and the refractive index of the low refractive material is 1.10 to 1.45.
The pressure-sensitive adhesive layer according to any one of claims 4 to 6, wherein the difference between the refractive index of the base polymer and the refractive index of the low refractive index material is 0.07 to 0.45.
The pressure-sensitive adhesive layer according to any one of claims 4 to 7, wherein the low refractive index material is particles having an average particle diameter of 10 nm to 150 nm.
The low refractive index material is selected from the group consisting of at least one inorganic particle selected from the group consisting of MgF 2 , CaF 2 and Na 3 AlF 6 , porous silica particles, hollow nanosilica particles, and hollow polymer particles. The pressure-sensitive adhesive layer according to any one of claims 4 to 8, wherein the pressure-sensitive adhesive layer is at least one particle.
The pressure-sensitive adhesive layer according to any one of claims 1 to 9, wherein the total light transmittance is 85% or more.
11. The pressure-sensitive adhesive layer according to claim 1, wherein the reflectance of the second surface is 0.5 to 3.5%.
The pressure-sensitive adhesive layer according to any one of claims 1 to 11, wherein a difference in reflectance between the first surface and the second surface is 0.1 to 3.5%.
The pressure-sensitive adhesive layer according to any one of claims 1 to 12, wherein the gel fraction is 30 to 95% by weight.
The pressure-sensitive adhesive layer according to any one of claims 1 to 13, wherein a storage elastic modulus G 'at 25 ° C is 0.05 to 0.50 MPa.
The pressure-sensitive adhesive layer according to any one of claims 1 to 14, wherein a tan δ peak value at the time of dynamic viscoelasticity measurement at 1 Hz is -5 to -50 ° C.
A method for producing the pressure-sensitive adhesive layer according to any one of claims 1 to 15,
Forming a base pressure-sensitive adhesive layer on the support with a pressure-sensitive adhesive composition containing the base polymer (1),
Preparing a dispersion in which a low refractive index material having a lower refractive index than that of the base polymer is dispersed (2);
In the base pressure-sensitive adhesive layer, the dispersion liquid is applied to the second surface opposite to the first surface on the support side, and the low refractive index material contained in the dispersion liquid is applied to the base pressure-sensitive adhesive layer. A step (3) of infiltrating in the thickness direction from the second surface, and a step of drying the pressure-sensitive adhesive layer infiltrated with the low refractive index material (4),
The manufacturing method of the adhesive layer characterized by including.
16. A pressure-sensitive adhesive sheet comprising the pressure-sensitive adhesive layer according to claim 1 and a support on one side or both sides of the pressure-sensitive adhesive layer.
An optical film with an adhesive layer having an optical film and an adhesive layer provided on one side or both sides of the optical film,
The single-sided or double-sided adhesive layer is the adhesive layer according to any one of claims 1 to 15, wherein a first surface side of the adhesive layer is provided on the optical film. Optical film with adhesive layer.
The optical film with an adhesive layer according to claim 18, wherein the optical film is a polarizing film.
20. An optical laminate comprising an optical film with an adhesive layer according to claim 18 or 19 and an optical member having a low refractive index bonded to the adhesive layer of the optical film with an adhesive layer.
An image display device comprising the pressure-sensitive adhesive layer according to any one of claims 1 to 15, the optical film with the pressure-sensitive adhesive layer according to claim 18 or 19, or the optical laminate according to claim 19.