JP2023059986A - Adhesive layer, method for producing same, adhesive sheet, adhesive layer-attached optical film, and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive layer that 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.

SOLUTION: 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.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2023,JPO&INPIT

Description

TECHNICAL FIELD The present invention relates to an adhesive layer and a method for producing the same. The present invention also relates to a pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer and an optical film with a pressure-sensitive adhesive layer. Furthermore, the present invention relates to an image display device using these.

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

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

JP 2014-224964 A

The above problems are thought 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, antireflection film, light diffusion film, light guide film , prism film, lens film, Fresnel lens, lenticular lens, or microlens film), visibility problems arise due to the influence of internal reflection of incident light at the interface. Since it is considered that the problem is caused by the refractive index of the optical film being lower than that of the pressure-sensitive adhesive layer, the 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 with a low refractive index using an acrylic pressure-sensitive adhesive, a general acrylic polymer (having a refractive index of usually 1.47 to 1.52), which is a base polymer, is added with fluoro as a monomer unit. It is conceivable to use an alkyl acrylate (refractive index around 1.38). However, the pressure-sensitive adhesive layer having a low refractive index and using a base polymer containing the fluoroalkyl acrylate as a monomer unit has a high surface tension, making it difficult to ensure adhesion. Thus, it has been extremely difficult to form a pressure-sensitive adhesive layer with 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. However, it is difficult to ensure sufficient adhesion with, etc.

The present invention can effectively suppress internal reflection even when applied to optical members having a low refractive index such as antireflection films, light diffusion films, lens films, Fresnel lenses, lenticular lenses, and microlens films. The object of the present invention is to provide a pressure-sensitive adhesive layer having good adhesion and a method for producing the same.

Further, the present invention provides a pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer, further provides a pressure-sensitive adhesive layer-attached optical film having the pressure-sensitive adhesive layer, and further provides the pressure-sensitive adhesive layer or the pressure-sensitive adhesive layer-attached optical film. An object of the present invention is to provide an image display device having an optical film.

The inventors of the present invention have made intensive studies to solve the above problems, and as a result, have found the pressure-sensitive adhesive layer and the like shown below, and completed the present invention.

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

In the 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 surface preferably has a second refractive index of 1.45 or less.

As the pressure-sensitive adhesive layer, a mode in which a low refractive index material having a lower refractive index than that of the base polymer is dispersed on the second surface side can be adopted.

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

In the adhesive layer, it is preferable that the base polymer has a refractive index of 1.40 to 1.55 and the low refractive index material has a refractive index of 1.10 to 1.45. Further, it is preferable that 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.

Examples of the low refractive index material include particles having an average particle size 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 adhesive layer preferably has a total light transmittance of 85% or more.

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

The pressure-sensitive adhesive layer preferably has a reflectance difference of 0.1 to 3.5% between the first surface and the second surface.

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

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

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

The present invention also provides a method for producing the pressure-sensitive adhesive layer,
Step (1) of forming a base pressure-sensitive adhesive layer on a support from a pressure-sensitive adhesive composition containing a base polymer;
step (2) of preparing a dispersion in which a low refractive index material having a refractive index lower than that of the base polymer is dispersed;
The dispersion or solution is applied to the second surface of the base adhesive layer 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 layer. The step (3) of permeating the adhesive layer from the second surface in the thickness direction, and the step (4) of drying the pressure-sensitive adhesive layer in which the low refractive index material has permeated,
A method for producing a pressure-sensitive adhesive layer, comprising:

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

The present invention also provides an optical film with an adhesive layer having an optical film and an adhesive layer provided on one or both sides of the optical film,
The present invention relates to an optical film with a pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive layer on one side or both sides 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 pressure-sensitive adhesive layer-attached optical film, a polarizing film is preferably used as the optical film.

The present invention also relates to an optical laminate comprising the optical film with an adhesive layer and an optical member having a low refractive index attached to the adhesive layer of the optical film with an adhesive layer.

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

The pressure-sensitive adhesive layer of the present invention differs from the diffused pressure-sensitive adhesive layer in which fine particles are uniformly dispersed in the pressure-sensitive adhesive layer, and has different refractive indices on both sides of a single pressure-sensitive adhesive layer having a first surface and a second surface. The first surface has a first refractive index based on the adhesive composition that forms the base of the entire adhesive layer, and the other second surface has the first It has a second refractive index 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 (for example, Antireflection film, light diffusion film, light guide film, prism film, lens film, Fresnel lens, lenticular lens, microlens film, etc.) can be adjusted, whereby the pressure-sensitive adhesive layer and the 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 an uneven surface portion such as a microlens, the surface uneven shape is protected by filling the uneven surface portion with the pressure-sensitive adhesive layer. Compared to the case where a void layer is provided in the uneven surface portion, the voids can be filled without impairing the light extraction efficiency, and scratches and shape damage due to vibrations during handling and transportation can be achieved. can be deterred. In addition, the second surface of the pressure-sensitive adhesive layer of the present invention has a refractive index-adjusted region adjusted to a low refractive index. can be formed. In addition, since the first surface of the pressure-sensitive adhesive layer of the present invention maintains the original adhesive strength of the pressure-sensitive adhesive layer, the adhesiveness to a general optical film (for example, a polarizing film, etc.) is also good, On the other hand, since the pressure-sensitive adhesive composition forms a base on the second surface of the pressure-sensitive adhesive layer controlled to have a low refractive index, it is possible to ensure adhesion with the optical film formed of a material with a low refractive index. can be done.

It is a sectional view showing one embodiment of the adhesive layer of the present invention. FIG. 4 is a plan view showing the state of the second surface of the pressure-sensitive adhesive layer of the present invention; It is the schematic which shows the process for producing the adhesive layer of this invention. 1 is a cross-sectional view showing an embodiment of the pressure-sensitive adhesive sheet of the present invention; FIG. BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows one Embodiment of the optical film with an adhesive layer of this invention. 1 is a cross-sectional view showing an embodiment of an optical layered body of the present invention; FIG.

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 opposite to the first surface f1. Further, in the pressure-sensitive adhesive layer 1, the base (matrix) 1a of the entire pressure-sensitive adhesive layer 1 is formed by the pressure-sensitive adhesive composition containing the 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 lower refractive index than that of the base polymer is dispersed (unevenly distributed) on the second surface f2 side of the substrate 1a. ing.

The first refractive index n1 of the first surface f1 corresponds to the refractive index of the adhesive layer obtained from the adhesive composition forming the base 1a in the adhesive layer 1 of the present invention. Therefore, the first refractive index n1 is determined by the adhesive composition forming the substrate 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 same as that of the base polymer. Determined by the refractive index of the polymer. The pressure-sensitive adhesive composition that forms the pressure-sensitive adhesive layer will be described later. For example, the refractive index of the pressure-sensitive adhesive layer formed from a typical acrylic pressure-sensitive adhesive is generally about 1.47 to 1.52. The refractive index of a pressure-sensitive adhesive layer formed from a 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 it satisfies n1>n2 in relation to the first refractive index n1 of the first surface f1 side. It is appropriately determined in consideration of the refractive index of the optical film having a low refractive index. However, if the difference (n1-n2) between the first refractive index n1 and the second refractive index n2 becomes too large, internal reflection may occur within the pressure-sensitive adhesive layer 1, so the front difference (n1-n2 ) is preferably adjusted to 0.02 to 0.45. The difference (n1-n2) is preferably 0.03 to 0.35, more preferably 0.03 to 0.25.

The second refractive index n2 of the second surface f2 is, for example, preferably 1.45 or less from the viewpoint of effectively suppressing internal reflection, more preferably 1.4 or less, and further preferably 1.45 or less. It is preferably 0.35 or less, 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 a substitute for the air layer. On the other hand, the second refractive index n2 is preferably 1.25 or more, more preferably 1.28 or more, from the viewpoint of maintaining adhesive strength. The range of the second refractive index n2 is lower than the lower limit of the refractive index (generally about 1.47 to 1.52) of a pressure-sensitive adhesive layer formed from a typical acrylic pressure-sensitive adhesive.

Further, 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 substrate 1a 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 f2 side of 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 preferably 1.40 to 1.52, more preferably 1.40 to 1.50. The refractive index of the low refractive index material 2 is preferably 1.14 to 1.42, more preferably 1.18 to 1.40. The difference between the refractive index of the base polymer and the low refractive index material 2 is preferably 0.07 to 0.35, more preferably 0.10 to 0.30. The lower the refractive index of the low-refractive-index material 2, the lower the refractive index with a low additive amount. As the refractive index difference increases, scattering (haze) tends to occur easily, so it is preferable to adjust the refractive index difference so as not to increase too much. The refractive index can be expressed as a D-line refractive index value measured under an environment of 23° C. by spectroscopic ellipsometry when the material is a single layer film.

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

Hollow particles, for example, can be used as the low refractive index material 2 . The hollow particles may be inorganic particles or polymer particles. Since the hollow particles have void spaces with a low refractive index within the particles, the refractive index of the hollow particles is lower than the refractive index of the components forming the hollow particles. For example, the refractive index of silica is 1.46, but hollow nanosilica particles (refractive index 1.24, trade name: Sururia 5320, particle size 75 nm, manufactured by Nikki Shokubai Kasei Co., Ltd.) and porous silica particles have a low refractive index. It can be used as a material. In addition, hollow polymer microparticles (refractive index 1.32, trade name: Techpolymer NH product number XX-255AA, particle size 80 nm, hollowness 39%, manufactured by Sekisui Plastics Co., Ltd.) can be exemplified. In addition, when hollow particles are provided in a low refractive surface treatment layer, there are problems in strength and scratch resistance because they are hollow materials, but the hollow particles (low refractive index material 2) in the present invention are adhesive Since it is in the form of being added (impregnated) into the agent layer 1, it can be applied without considering the problems of strength and scratch resistance.

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

Although the thickness of the adhesive layer 1 is not particularly limited, it is usually 5 μm to 500 μm, preferably 10 μm to 400 μm, more preferably 10 μm to 350 μm. Further, in FIG. 1, the region in which the low refractive index material 2 is dispersed in the pressure-sensitive adhesive layer 1 is represented by a thickness T from the second surface f2 side. The thickness T is appropriately designed according to the thickness of the pressure-sensitive adhesive layer, and is usually preferably 600 nm or less, more preferably 300 nm or less, further preferably 200 nm or less. The thickness T is preferably 10 nm or more, more preferably 15 nm or more, further 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.

In the pressure-sensitive adhesive layer 1, the region in which the low refractive index material 2 related to the thickness T is dispersed has an irregular uneven shape in relation to the substrate (matrix) 1a, but in the present invention, the thickness T is determined by averaging the depth measurements of the topography.

The low refractive index material 2 is distributed on the second surface f2 side in an individually dispersed state or in a partially aggregated state. The boundary between the region where the low refractive index material 2 is dispersed and the substrate 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 depth range where 90% of the low refractive index material 2 exists at each measurement position is the measured value of the thickness T at that measurement position, and the measured values at a plurality of measurement positions are Average.

FIG. 2 is a plan view showing the state of the second surface f2 of the pressure-sensitive adhesive layer 1. FIG. As shown in FIG. 2, the substrate 1a has a sea-island structure in which the low-refractive index material 2 is dispersed like islands, and the substrate 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 defined as the ratio of the area occupied by the low refractive index material 2 to the total area of a rectangular region with a side of 10 μm to 200 μm, and the measured values are averaged for a plurality of rectangular regions. An area ratio is obtained.

The ratio of the low refractive index material 2 in the pressure-sensitive adhesive layer 1 satisfies the relationship of n1>n2 between the first refractive index n1 on the first surface f1 side and the second refractive index n2 on the second surface f2. There are no particular restrictions if

The total light transmittance of the pressure-sensitive adhesive layer 1 of the present invention is preferably 85% or more, more preferably 88% or more, and still more preferably 90% or more. The higher the total light transmittance of the pressure-sensitive adhesive layer 1, the better. Also, 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 adhesive layer 1 is preferably as low as possible. The total light transmittance and haze value of the adhesive layer 1 as a whole are values measured according to JIS K7361.

The second surface of the pressure-sensitive adhesive layer 1 of the present invention preferably has a reflectance of 0.5 to 3.5%. The reflectance of the second surface of the 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%. Moreover, 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%.

In the description above, the pressure-sensitive adhesive layer 1 of the present invention is described on the premise 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 indices of both surfaces, and the reflectance of the second surface f2 is lower than the reflectance of the first surface f1. It can be regarded as a characteristic invention.

Further, the 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, even more preferably 40 to 90% by weight. When the gel fraction of the pressure-sensitive adhesive layer 1 is within the above range, the pressure-sensitive adhesive layer 1 has stress relaxation properties and is a preferable mode for ensuring conformability to irregularities. The gel fraction relates to the base 1a of 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 obtained by scraping about 0.2 g from the pressure-sensitive adhesive layer (before permeation of the low refractive index material). Sample 1 was wrapped in a Teflon (registered trademark) film having a diameter of 0.2 μm (trade name “NTF1122”, manufactured by Nitto Denko Corporation) and tied with a kite string. The weight of sample 2 was measured before being subjected to the following test, and this was defined 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 weight B is the total weight of the Teflon (registered trademark) film and the kite string. Next, the sample 2 was placed in a 50 ml container filled with ethyl acetate and allowed to stand at 23° C. for 1 week. After that, sample 2 was taken out from the container and dried in a dryer at 130° C. for 2 hours to remove ethyl acetate, and the weight of sample 2 was measured. After being subjected to the test, the weight of Sample 2 was measured and designated as Weight C. Then, the gel fraction (% by weight) was calculated from the following formula.
Gel fraction (% by weight) = (C - B) / (A - B) x 100

The pressure-sensitive adhesive layer 1 of the present invention preferably has a storage modulus G' at 25°C of 0.05 to 0.50 MPa. The storage modulus G' is preferably 0.06 to 0.45 MPa, more preferably 0.07 to 0.40 MPa, even 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 a preferred embodiment for protecting image display devices (LCD, OLED terminals, etc.), which are becoming thinner, and ensuring dimensional stability during cutting. becomes.

Further, 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 in dynamic viscoelasticity measurement at 1 Hz. The tan δ peak value is preferably -7 to -50°C, more preferably -9 to -45°C, and still more preferably -10 to -40°C. When the tan δ peak value of the pressure-sensitive adhesive layer 1 is within the above range, it is a preferred mode for ensuring the resistance to drop impact of an image display device (mobile terminal, etc.).

<Measurement of storage elastic modulus G′ and tan δ peak value of pressure-sensitive adhesive layer>
A test sample having a thickness of about 2 mm was prepared by laminating a plurality of adhesive layers. This test sample was punched into a disk shape with a diameter of 7.9 mm, sandwiched between parallel plates, and subjected to dynamic viscoelasticity measurement under the following conditions using Rheometric Scientific's "Advanced Rheometric Expansion System (ARES)". 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
Heating 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 step (1), a base adhesive layer 1' is formed on a support S with an adhesive composition containing a base polymer. The base pressure-sensitive adhesive layer 1' forms the substrate 1a in the pressure-sensitive 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 it can be formed by a method commonly 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 dried to form it, or irradiated with active energy rays such as ultraviolet rays. can be formed by

The support S is not particularly limited, and various substrates such as release films and transparent resin film substrates 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; A suitable thin leaf material such as a resin film is preferably used because of its excellent surface smoothness. If necessary, the release film may be subjected to a release and antifouling treatment or an antistatic treatment.

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

Examples of the dispersion medium include methanol, ethanol, isopropyl alcohol, 1-propanol, n-butanol, 2-butanol, cyclohexanol, t-butyl alcohol, glycerin, ethylene glycol, and 2-methyl-2,4-pentadiol. , phenol, parachlorophenol and other alcohols; acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, cyclopentanone, 2-pentanone, 2-hexanone, 2-heptanone and other ketones; diethyl ether, tetrahydrofuran, dioxane, anisole, etc. Ethers; Esters 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; amides; cellosolves such as methyl cellosolve, ethyl cellosolve, and methyl cellosolve acetate; These dispersion media can be used alone or in combination of two or more. The above solvents are merely examples, and the solvents used in the present invention are not limited to these.

Next, in 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 layer 1'. It is permeated in the thickness direction from the second surface f2' of the agent layer 1'. FIG. 3(3)-1 shows the state immediately after the dispersion liquid 10 is applied to the base pressure-sensitive adhesive layer 1', and (3)-2 shows the state in which the low refractive index material 2 has permeated the base pressure-sensitive adhesive layer 1'. The second surface f2' side of the base 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 is absorbed into the base adhesive layer 1'. permeate.

Next, in step (4), the base pressure-sensitive adhesive layer 1' permeated with the low refractive index material 2 is dried. By evaporating the dispersion medium of the dispersion liquid 10 that permeates the base pressure-sensitive adhesive layer 1' in the drying process, the pressure-sensitive adhesive layer 1 shown in FIG. 1 can be obtained. This state is shown in (4) of FIG. Conditions for the drying process are determined according to the type of 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 is the value described above. Also, the amount of the dispersion liquid to be applied is appropriately set so that the desired thickness T is achieved.

Examples of the method of applying the dispersion include 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, and die coating. An appropriate method such as a filter can be used. The thickness T can be controlled by the method of applying the dispersion, the concentration of the dispersion, the amount of application, and the like.

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

For the adhesive composition, a transparent material having adhesiveness that can be used for optical purposes is preferably used. The adhesive composition is appropriately selected from, for example, acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, epoxy adhesives, and polyether 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 is used according to the type of the pressure-sensitive adhesive composition. In the present invention, an acrylic pressure-sensitive adhesive containing a (meth)acrylic polymer as a base polymer is preferred.

The acrylic pressure-sensitive adhesive may contain, for example, a partial polymer of a monomer component containing an alkyl (meth)acrylate and/or a (meth)acrylic polymer obtained from the monomer component. Base polymers of acrylic pressure-sensitive adhesives include partial polymers of monomer components containing alkyl (meth)acrylates and/or (meth)acrylic polymers obtained from the monomer components.

Examples of the alkyl (meth)acrylate include the above-mentioned linear or branched alkyl (meth)acrylate having 1 to 24 carbon atoms. Acrylates are preferred, and branched alkyl (meth)acrylates having 4 to 9 carbon atoms are preferred. The alkyl (meth)acrylate is preferable in that the adhesive properties are easily balanced. Specific examples of branched alkyl (meth)acrylates having 4 to 9 carbon atoms include n-butyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, and isobutyl (meth)acrylate. Acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, isohexyl (meth)acrylate, isoheptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate and the like. These can be used singly 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 end is 40% by weight or more with respect to the total amount of the monofunctional monomer component forming the (meth)acrylic polymer. is preferred, 50% by weight or more is more preferred, and 60% by weight or more is even more preferred.

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

Comonomers can include, for example, cyclic nitrogen-containing monomers. As the cyclic nitrogen-containing monomer, those having a polymerizable functional group having an unsaturated double bond such as a (meth)acryloyl group or a vinyl group and having a cyclic nitrogen structure can be used without particular limitation. The cyclic nitrogen structure preferably has a nitrogen atom within the cyclic structure. Examples of cyclic nitrogen-containing monomers include lactam-based vinyl monomers such as N-vinylpyrrolidone, N-vinyl-ε-caprolactam, and methylvinylpyrrolidone; vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinyl Vinyl-based monomers having a nitrogen-containing heterocyclic ring such as imidazole, vinyloxazole, and vinylmorpholine are included. Also included are (meth)acrylic monomers containing a heterocyclic ring such as a morpholine ring, piperidine ring, pyrrolidine ring and piperazine ring. Specific examples include N-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, N-acryloylpyrrolidine and the like. Among the cyclic nitrogen-containing monomers, lactam vinyl monomers are preferred.

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

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, those 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 hydroxyl group-containing monomers 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; (4 - 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. Among these, hydroxyalkyl (meth)acrylates are preferred.

In the present invention, the hydroxyl group-containing monomer is preferably 1% by weight or more with respect to the total amount of monofunctional monomer components forming the (meth)acrylic polymer from the viewpoint of increasing adhesive strength and cohesive strength. Although it is 2% by weight or more, it is more 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 gel may occur. Therefore, the hydroxyl group-containing monomer is preferably 30% by weight or less, more preferably 27% by weight or less, relative to the total amount of the monofunctional monomer component forming the (meth)acrylic polymer, and 25% by weight. % or less is more preferable.

In addition, the monomer component forming the (meth)acrylic polymer may contain other functional group-containing monomers as monofunctional monomers, such as carboxyl group-containing monomers and monomers having a cyclic ether group. be done.

As the carboxyl group-containing monomer, those 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 carboxyl group-containing monomers 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. Anhydrides of itaconic acid and maleic acid can be used. Among these, acrylic acid and methacrylic acid are preferred, and acrylic acid is particularly preferred. Any carboxyl group-containing monomer can be used as the monomer component used for producing the (meth)acrylic polymer of the present invention, while the carboxyl group-containing monomer may not be used.

As the monomer having a cyclic ether group, those having a polymerizable functional group having an unsaturated double bond such as a (meth)acryloyl group or a vinyl group and having a cyclic ether group such as an epoxy group or an oxetane group are used. It can be used without any particular limitation. Examples of epoxy group-containing monomers include glycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether, and the like. Examples of oxetane group-containing monomers 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, and 27% by weight, based on the total amount of the monofunctional monomer component forming the (meth)acrylic polymer. % or less is more preferable, and 25% by weight or less is even more preferable.

Examples of monomer components for forming the (meth)acrylic polymer of the present invention include, as copolymerization monomers, CH ₂ ═C(R ¹ )COOR ² (R ¹ is hydrogen or a methyl group, R ² is the number of carbon atoms 1 to 3 substituted alkyl groups and cyclic cycloalkyl groups.) include alkyl (meth)acrylates.

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 preferably, but not limited to, a phenyl group.

Examples of such monomers 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 and the like. 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 with respect to the total amount of monofunctional monomer components 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 even more preferable.

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

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

The monomer components forming the (meth)acrylic polymer of the present invention include, in addition to the monofunctional monomers exemplified above, polyfunctional monomers as necessary in order to adjust the cohesion of the pressure-sensitive adhesive composition. can contain.

Polyfunctional monomers are monomers having at least two polymerizable functional groups having unsaturated double bonds such as (meth)acryloyl groups or vinyl groups, for example, (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, tetramethylolmethane tri(meth)acrylate, etc. Ester compounds of polyhydric alcohol and (meth)acrylic acid; allyl (meth)acrylate, vinyl (meth)acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate, butyl di(meth)acrylate, hexyl di(meth)acrylate, etc. is mentioned. 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 its molecular weight, the number of functional groups, etc., but it is preferably used in an amount of 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 monomers. 1 part by weight or less is more preferable. Although the lower limit is not particularly limited, it is preferably 0 parts by weight or more, more preferably 0.001 parts by weight or more. Adhesive strength can be improved by setting the amount of the polyfunctional monomer to be used within the above range.

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

In addition, in the present invention, a partially polymerized product of the above monomer component can also be suitably used.

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

When the (meth)acrylic polymer is produced by radical polymerization, polymerization can be carried out by appropriately adding polymerization initiators, chain transfer agents, emulsifiers, etc. used for radical polymerization to the monomer components. The polymerization initiator, chain transfer agent, emulsifier and the like used in the radical polymerization are not particularly limited and can be appropriately selected and used. The weight-average molecular weight of the (meth)acrylic polymer can be controlled by adjusting the amount of the polymerization initiator and the chain transfer agent used and the reaction conditions, and the amount used is appropriately adjusted according to these types.

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

When the (meth)acrylic polymer is produced by radiation polymerization, it can be produced by irradiating the monomer component with radiation such as electron beams and ultraviolet rays (UV) for polymerization. When performing ultraviolet polymerization, it is preferable to allow the monomer component to contain a photopolymerization initiator because of the advantage that the polymerization time can be shortened.

(Silane coupling agent)
Furthermore, the 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). 0.02 to 0.6 parts by weight is more preferred.

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

The cross-linking agent may be used alone or in combination of two or more, but the total content is the monofunctional monomer that forms the (meth)acrylic polymer. Based on 100 parts by weight of the component, it is preferably 5 parts by weight or less, more preferably 0.01 to 5 parts by weight, still more preferably 0.01 to 4 parts by weight, and 0.02 to 3 parts by weight. Especially preferred.

(Other additives)
The pressure-sensitive adhesive composition of the present invention may contain appropriate additives in addition to the components described above, depending on the application. For example, viscosity modifiers, release modifiers, tackifiers (for example, rosin derivative resins, polyterpene resins, petroleum resins, oil-soluble phenolic resins that are solid, semi-solid, or liquid at room temperature), plasticizers, softeners agents, pigments, coloring agents (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 the pressure-sensitive adhesive layer 1 and a support on one side or both sides of the pressure-sensitive adhesive layer 1 . FIG. 4 shows the case where the adhesive layer 1 has the support 3a on the first surface f1 and the support 3b on the second surface f2. As the supports 3a and 3b, the same support as the support S used in the adhesive layer 1 shown in FIG. 3 can be used. As the support 3a, the support S used in the method for producing the pressure-sensitive adhesive layer 1 shown in FIG. 3 can be used as it is. 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 pressure-sensitive adhesive layer-carrying optical film A of the present invention has an optical film 4 and a pressure-sensitive adhesive layer 1 provided on one side or both sides of the optical film 4 . The adhesive layer 1 is provided on either one side or both sides of the optical film 4 . The pressure-sensitive adhesive layer 1 is provided on the optical film 4 on the first surface f1 side of the pressure-sensitive adhesive layer 1 . When the pressure-sensitive adhesive layer 1 is provided on one side of the optical film 4, the other side may be provided with a normal pressure-sensitive adhesive layer. FIG. 5 shows the case where the adhesive layer 1 is provided only on one side of the optical film 4 . FIG. 5 shows the case where the pressure-sensitive adhesive layer 1 has the support 3b on the second surface f2.

<Optical film>
As the optical film, for example, one used for forming an image display device such as a liquid crystal display device is used, and the type thereof is not particularly limited. For example, the optical film includes a polarizing 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 polarizers can be used. As a polarizer, for example, hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and partially saponified ethylene-vinyl acetate copolymer films are coated with dichroic dyes such as iodine and dichroic dyes. Polyene-based oriented films such as those obtained by adsorbing a substance and uniaxially stretched, polyvinyl alcohol dehydrated products, polyvinyl chloride dehydrochlorinated products, and the like can be mentioned. Among these, a polarizer composed of a polyvinyl alcohol film and a dichroic substance such as iodine is suitable. Although the thickness of these polarizers is not particularly limited, it is generally about 5 to 80 μm.

A polarizer obtained by dyeing a polyvinyl alcohol-based film with iodine and uniaxially stretching it can be produced, for example, by dyeing a polyvinyl alcohol-based film by immersing it in an aqueous solution of iodine and stretching it to 3 to 7 times its original length. can. It can also be immersed in an aqueous solution of potassium iodide or the like, which may contain boric acid, zinc sulfate, zinc chloride or the like, if necessary. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed with water before dyeing. By washing the polyvinyl alcohol film with water, dirt and anti-blocking agents on the surface of the polyvinyl alcohol film can be washed away, and by swelling the polyvinyl alcohol film, uneven dyeing can be prevented. be. Stretching may be performed after dyeing with iodine, stretching may be performed while dyeing, or dyeing with iodine may be performed after stretching. It can also be stretched in an aqueous solution of boric acid or potassium iodide or in a water bath.

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

As a thin polarizer, typically, JP-A-51-069644, JP-A-2000-338329, WO 2010/100917 pamphlet, or JP-A-4751481 and JP-A-2012- A thin polarizing film described in JP-A No. 073563 can be mentioned. These thin polarizing films can be obtained by a manufacturing method including a step of stretching a laminate of a polyvinyl alcohol-based resin (hereinafter also referred to as a PVA-based resin) layer and a stretching resin substrate, and a step of dyeing. According to this manufacturing method, even if the PVA-based resin layer is thin, it can be stretched without problems such as breakage due to stretching because it is supported by the stretching resin substrate.

As for the thin polarizing film, among the manufacturing methods including the step of stretching and the step of dyeing in the state of a laminate, it can be stretched at a high magnification and can improve the polarizing performance. , or preferably those obtained by a manufacturing method including a step of stretching in an aqueous boric acid solution as described in JP 4751481 and JP 2012-073563, especially JP 4751481 and JP 2012- Preferably, it is obtained by the process described in JP-A-073563, which includes a step of auxiliary stretching in the air before stretching in an aqueous boric acid solution.

As a material for forming the transparent protective film, a thermoplastic resin having excellent transparency, mechanical strength, thermal stability, water barrier properties, 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 Polyolefin resins (norbornene-based resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. A transparent protective film is attached to one side of the polarizer with an adhesive layer, and a transparent protective film such as (meth)acrylic, urethane, acrylic urethane, epoxy, or silicone film is attached to the other side of the polarizer. A thermosetting resin such as a system or a UV curable resin can be used. One or more of any suitable additives may be contained in the transparent protective film. Examples of additives include ultraviolet absorbers, antioxidants, lubricants, plasticizers, release agents, anti-coloring agents, flame retardants, nucleating agents, antistatic agents, pigments, colorants and the like. 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. . If the content of the thermoplastic resin in the transparent protective film is 50% by weight or less, the high transparency inherent in the thermoplastic resin may not be sufficiently exhibited.

Although the thickness of the transparent protective film can be determined as appropriate, it is generally about 1 to 500 μm from the viewpoints of strength, workability such as handleability, and thinness.

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 on which the polarizer is not adhered, and the surface is treated for the purpose of diffusion or antiglare. can be

The adhesive used for bonding the polarizer and the transparent protective film is not particularly limited as long as it is optically transparent. water-based adhesives or radical curing adhesives are preferred.

As optical films, for example, it is used to form liquid crystal displays such as reflectors, anti-transmissive plates, retardation films (including 1/2 and 1/4 wavelength plates), visual compensation films, and brightness enhancement films. optical layers that may be used. These can be used alone as an optical film, and can also be laminated to the polarizing film for practical use in one or more layers. A retardation film can also be used as the transparent protective film. As the retardation film, a film obtained by stretching and shrinking a polymer film or a film obtained by aligning and fixing a liquid crystal material can be appropriately used depending on the purpose.

The optical film obtained by laminating the optical layer on the polarizing film can be formed by a method of sequentially and separately laminating in the manufacturing process of a liquid crystal display device or the like. It has the advantage of improving the manufacturing process of liquid crystal display devices, etc., because it is excellent in stability and assembly work. Appropriate adhesive means such as an adhesive layer can be used for lamination. When the polarizing film and other optical layers are adhered, their optical axes can be arranged at an appropriate angle according to the desired retardation properties and the like.

The optical laminate B of the present invention has an optical film A with an adhesive layer and an optical member 5 with 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 adhesive layer 1 . The optical laminate B shown in FIG. 6 is obtained by peeling off the support 3b (for example, release film) from the adhesive layer-attached optical film A shown in FIG. A combined case is illustrated. Examples of the optical member 5 include an antireflection film, a light diffusion film, a prism film, a light guiding film, a lens film, a Fresnel lens, a lenticular lens, a microlens film, and the like.

The pressure-sensitive adhesive layer-carrying optical film or optical laminate of the present invention can be preferably used for forming various image display devices such as liquid crystal display devices. Formation of the liquid crystal display device can be carried out according to the conventional method. That is, a liquid crystal display device is generally formed by appropriately assembling components such as a display panel such as a liquid crystal cell, an optical film with an adhesive layer, or an optical laminate and, if necessary, an illumination system, and incorporating a driving circuit. However, in the present invention, there is no particular limitation except that the pressure-sensitive adhesive layer-attached optical film or optical laminate according to the present invention is used, and conventional methods can be applied. As for the liquid crystal cell, any type such as TN type, STN type, π type, VA type, IPS type, etc. can be used.

Appropriate liquid crystal display devices such as liquid crystal display devices in which an optical film with an adhesive layer or an optical laminate is placed on one or both sides of a display panel such as a liquid crystal cell, or devices using a backlight or a reflector in the lighting system are formed. can do. In that case, the pressure-sensitive adhesive layer-attached optical film or optical laminate according to the present invention can be placed on one side or both sides of a display panel 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, appropriate parts such as a diffusion layer, an anti-glare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusion sheet, a backlight, etc. Two or more layers can be arranged.

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these Examples. All parts and percentages in each example are based on weight. All room temperature storage conditions not specified below are 23° C. and 65% RH.

(release film)
A polyester film (trade name: Diafoil MRF, manufactured by Mitsubishi Plastics Co., Ltd.) having a thickness of 38 μm and having one surface subjected to release treatment with silicone was used.

Comparative example 1
(Preparation of 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 0.035 parts by weight of a seed photopolymerization initiator (trade name: Irgacure 184, manufactured by BASF) and 0.035 parts by weight of a photopolymerization initiator (trade name: Irgacure 651, manufactured by BASF) are added to a four-necked flask. to prepare a monomer mixture. Then, this monomer mixture was partially photopolymerized by exposing it to ultraviolet rays in 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 parts by weight of trimethylolpropane triacrylate (TMPTA), a silane coupling agent (trade name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) ) was added, and these were uniformly mixed to prepare a pressure-sensitive adhesive composition (A).

(Production of adhesive layer (A))
The pressure-sensitive adhesive composition (A) was applied onto the release-treated surface of the release film so that the thickness after formation of 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-treated surface was on the coating layer side. Thereafter, ultraviolet irradiation is performed under the conditions of illuminance: 6.5 mW/cm ² , light amount: 2000 mJ/cm ² , peak wavelength: 350 nm, and the coating layer is photocured to form an adhesive layer (A). A pressure-sensitive adhesive sheet (substrate-less type, thickness of pressure-sensitive adhesive layer: 100 μm) having release films provided on both sides of the layer (A) was prepared. The pressure-sensitive adhesive layer (A) had a D-line refractive index (n _D ) of 1.48 and a gel fraction of 67% as measured under an environment of 23° C. with an Abbe refractometer.

Comparative example 2
(Preparation of adhesive composition (B))
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) was photopolymerized. As agents, 0.050 parts by weight of 1-hydroxycyclohexylphenyl ketone (trade name: Irgacure 184, having an absorption band at a wavelength of 200 to 370 nm, manufactured by BASF), 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) after blending 0.050 parts by weight, viscosity (measurement conditions: BH viscometer No. 5 rotor, 10 rpm, measurement temperature 30° C.) reached about 20 Pa·s to obtain a prepolymer composition (polymerization rate: 9%) in which a part of the above monomer component was polymerized. 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 adhesive composition (B))
2,4- 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) 0.8 parts by weight (solid content weight) and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (trade name: Irgacure 819, wavelength 200 to 450 nm absorption band A pressure-sensitive adhesive composition (B) was obtained by adding 0.3 parts by weight of BASF Japan Co., Ltd.) and stirring.

(Production 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 formation of 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-treated surface was on the coating layer side. After that, ultraviolet irradiation is performed under the conditions of illuminance: 6.5 mW/cm ² , light amount: 2000 mJ/cm ² , peak wavelength: 350 nm, and the coating layer is photocured to form an adhesive layer (B) to form an adhesive layer. A pressure-sensitive adhesive sheet (substrate-less type, thickness of pressure-sensitive adhesive layer: 150 μm) having release films on both sides of the agent layer (B) was prepared. The pressure-sensitive adhesive layer (B) had a D-line refractive index (n _D ) of 1.49 and a gel fraction of 88% as measured under an environment of 23° C. with an Abbe refractometer.

Comparative example 3
(Preparation of adhesive composition (C))
In a separable flask equipped with a thermometer, a stirrer, a reflux condenser and a nitrogen gas introduction tube, 95 parts by weight of butyl acrylate (BA), 5 parts by weight of acrylic acid (AA), and 0 part of azobisisobutyronitrile as a polymerization initiator. After adding 2 parts by weight and 233 parts by weight of ethyl acetate, nitrogen gas was flowed and the contents were replaced with nitrogen for about 1 hour while stirring. After that, 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 1,100,000. 0.8 parts by weight of trimethylolpropane tolylene diisocyanate (trade name: Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.) as an isocyanate cross-linking agent to the above acrylic polymer solution (with a solid content of 100 parts by weight); 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.).

(Production of adhesive layer (C))
The pressure-sensitive adhesive composition (C: solution) is applied on the release-treated surface of the release film so that the thickness after drying is 23 μm, and then dried at 100 ° C. for 3 minutes to remove the solvent. It was removed to obtain an adhesive layer (C). After that, a cross-linking treatment was performed by heating at 50° C. for 48 hours. The exposed surface of the obtained pressure-sensitive adhesive layer (C) is coated with another release film so that the release-treated surface is on the exposed surface side, and a release film is formed on both surfaces of the pressure-sensitive adhesive layer (C). was provided (substrate-less type, adhesive layer thickness: 23 μm). The pressure-sensitive adhesive layer (C) had a D-line refractive index (n _D ) of 1.47 and a gel fraction of 82% as measured under an environment of 23° C. with an Abbe refractometer.

Comparative example 4
(Preparation of adhesive composition (D))
A separable flask equipped with a thermometer, a stirrer, a reflux condenser and a nitrogen gas inlet tube was charged with 99 parts by weight of butyl acrylate (BA) and 1 part by weight of 4-hydroxybutyl acrylate (4HBA) as monomer components, and an azo polymer as a polymerization initiator. After 0.2 parts by weight of bisisobutyronitrile and ethyl acetate as a polymerization solvent were added so that the solid content was 30% by weight, nitrogen gas was flowed and nitrogen substitution was performed for about 1 hour while stirring. After that, 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 1,100,000. Trimethylo-propane xylylene diisocyanate (Mitsui Chemicals Co., Ltd. "Takenate D110N") 0.11 parts as an isocyanate cross-linking agent in the acrylic polymer solution (solid content 100 parts), a silane coupling agent (Shin-Etsu Chemical "KBM-403" manufactured by Co., Ltd.) was added to prepare an adhesive composition (D: solution).

(Production of adhesive layer (D))
The pressure-sensitive adhesive composition (D: solution) is applied onto the release-treated surface of the release film so that the thickness after drying is 20 μm, and then dried at 120° C. for 3 minutes to remove the solvent. , to obtain an adhesive layer (D). After that, a cross-linking treatment was performed by heating at 50° C. 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 a release film is formed on both sides of the pressure-sensitive adhesive layer (D). was provided (substrate-less type, adhesive layer thickness: 23 μm). The pressure-sensitive adhesive layer (D) had a D-line refractive index (n _D ) of 1.47 and a gel fraction of 75% as measured under an environment of 23° C. with an Abbe refractometer.

Example 1
(Preparation of dispersion liquid 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: Surulia 5320, manufactured by Nikki Shokubai Kasei Co., Ltd.), 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.

(Production 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. The dispersion liquid was applied to the exposed surface of the pressure-sensitive adhesive layer (A) using a bar coater RDS No. 1 so that the thickness of the refractive index adjustment region was about 20 nm to 150 nm. 3, and then dried in a drying oven at 110° C. for 180 seconds. Next, a second release film was newly attached 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 of 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 adhesive layer and the type of dispersion liquid (type of low refractive index particles, average particle size thereof, type of dispersion medium, particle concentration) were changed as shown in Table 1. A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer with an adjusted refractive index was prepared in the same manner as in 1.
When the target thickness of the refractive index adjustment region after drying is about 150 to 300 nm, bar coater RDS No. 5 is used, and the target thickness of the refractive index adjustment region after drying is 20 to 150 nm. Bar coater RDS No. 3 was used in the case of grade.

(evaluation)
Table 1 shows the results of the following evaluations of the adhesive layers (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 adjustment region side: second surface) obtained in Examples was measured at the sodium D line (589 nm) using a spectroscopic ellipsometer (EC-400, manufactured by JA Woolam). 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 was applied in a state in which a blackboard was attached to the surface (first surface) that was not coated with the dispersion. The average refractive index of the surface (second surface) was measured. For the pressure-sensitive adhesive sheet of Comparative Example, the average refractive index of the pressure-sensitive adhesive layer surface was measured in a state in which both release films were peeled off and a blackboard was adhered 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>
A 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 of 3000 to 30000 times). The thickness of the refractive index adjustment region is the average value of the unevenness of the interface between the region in which the particles are dispersed and the region in which the particles are not dispersed in the adhesive layer. Binary image processing was performed using image processing software (ImageJ), and the depth and thickness of the region in which 90% (area) of the particles existed was taken as the thickness.

<Total light transmittance, haze>
From the pressure-sensitive adhesive sheet obtained in the example, the second release film (second surface side of the pressure-sensitive adhesive layer) was peeled off, and a slide glass (trade name: white polishing No. 1, thickness: 0.8 to 1) was applied. 0 mm, total light transmittance: 92%, haze: 0.2%, manufactured by Matsunami Glass Industry Co., Ltd.). Further, the other first release film was peeled off to prepare a test piece having a layer structure of pressure-sensitive adhesive layer (refractive index adjustment region on slide glass side)/slide glass. On the other hand, in the pressure-sensitive adhesive layer of the comparative example, one of the release films was peeled off and attached to the same slide glass as described above, and the other release film was peeled off to obtain a layer structure of the pressure-sensitive adhesive layer/slide glass. A test piece having The total light transmittance and haze value of the test piece in the visible light region were measured using a haze meter (device name: HM-150, manufactured by Murakami Color Laboratory Co., Ltd.).

<Adhesion>
Sheet pieces having a length of 100 mm and a width of 20 mm were cut out from the adhesive sheets obtained in Examples and Comparative Examples. Next, from the sheet piece obtained from the pressure-sensitive adhesive sheet of the example, after peeling off the first release film (the side of the pressure-sensitive adhesive layer on which the dispersion liquid was not applied), a PET film (product Name: Lumirror S-10, thickness: 25 μm, manufactured by Toray Industries, Inc.) was attached (backed). Next, the second release film was peeled off, and a glass plate (trade name: soda lime glass #0050, manufactured by Matsunami Glass Industry Co., Ltd.) as a test plate was crimped under crimping conditions of one reciprocation with a 2 kg roller, A sample composed of a test plate/adhesive layer (the first surface is on the PET side)/PET film was prepared. On the other hand, in the sheet piece obtained from the pressure-sensitive adhesive sheet of the comparative example, after peeling off one release film, the same PET film as described above was attached to the surface of the pressure-sensitive adhesive layer, and then the other release film was peeled off. , samples were prepared using test plates similar to those described above. The resulting sample was autoclaved (50°C, 0.5 MPa, 15 minutes) and then 23°C, 50% RH. H. It was allowed to cool for 30 minutes in an atmosphere of After standing to cool, using a tensile tester (equipment name: Autograph AG-IS, manufactured by Shimadzu Corporation), in accordance with JIS Z0237, 23 ° C., 50% R.E. H. The pressure-sensitive adhesive sheet (adhesive layer/PET film) was peeled off from the test plate under conditions of a peeling speed of 300 mm/min and a peeling angle of 180° in an atmosphere of , and the 180° peeling adhesive strength (N/20 mm) was measured.

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

<Measurement of internal reflection suppression rate (transmittance improvement effect)>
After peeling off the second release film (the side of the pressure-sensitive adhesive layer on which the dispersion is applied) from the pressure-sensitive adhesive sheet obtained in Example, a triacetyl cellulose film having a refractive index of 1.36 was applied to the surface of the pressure-sensitive adhesive layer. The low refractive index layer side of the laminated film on which the low refractive index layer was formed was attached, and laminated 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 is 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.) was laminated. In this way, a test piece having a layer structure of triacetyl cellulose film/low refractive index layer/adhesive layer (the second surface is on the low refractive index layer side)/slide glass was produced. On the other hand, for the pressure-sensitive adhesive layer obtained in Comparative Example, after peeling off one of the release films from the pressure-sensitive adhesive sheet, in the same manner as above, triacetyl cellulose film/low refractive index layer/adhesive layer/slide glass A test piece having a layer structure of

The internal reflection suppression rate (transmittance improvement effect) was calculated based on the following formula after measuring the transmittance of the test piece prepared above. The "transmittance (%) in the absence of particles" in the following formula is the reflectance of the test piece of the comparative example. That is, the internal reflection suppression effect (transmittance improvement effect) is an index showing 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: Sururia 5320, particle size 75 nm, manufactured by Nikki Shokubai Kasei Co., Ltd.),
(X2) Hollow polymer microparticles: 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 microparticles: 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 (matrix) for the entire adhesive layer
2 Low refractive index material f1 First surface of adhesive layer f2 Second surface of adhesive layer T Thickness of refractive index adjustment region S Support 3a... Support 3b... Support 4... Optical film 5... Low refractive optical member 10... Dispersion

Claims (18)

A one-layer pressure-sensitive adhesive layer having a first side and a second side opposite to the first side,
The pressure-sensitive adhesive layer forms a base of the entire pressure-sensitive adhesive layer with a pressure-sensitive adhesive composition containing a base polymer,
the first surface has a first refractive index based on the adhesive composition, while the second refractive index of the second surface is lower than the first refractive index of the first surface;
In the pressure-sensitive adhesive layer, a low refractive index material having a lower refractive index than that of the base polymer is dispersed on the second surface side,
The pressure-sensitive adhesive layer, wherein the region in which the low refractive index material is dispersed has a thickness of 600 nm or less in the thickness direction from the second surface side of the pressure-sensitive adhesive layer. 2. The pressure-sensitive adhesive layer according to claim 1, wherein the difference between the first refractive index of said first surface and the second refractive index of said second surface is 0.02 to 0.45. 3. The pressure-sensitive adhesive layer according to claim 1, wherein the second surface has a second refractive index of 1.45 or less. 4. The method according to any one of claims 1 to 3, wherein the base polymer has a refractive index of 1.40 to 1.55, and the low refractive index material has a refractive index of 1.10 to 1.45. adhesive layer. The pressure-sensitive adhesive layer according to any one of claims 1 to 4, wherein the low refractive index material is particles having an average particle size 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 _MgF2 , _CaF2 and _Na3AlF6 , porous silica particles, hollow nanosilica particles, and hollow polymer particles. The pressure-sensitive adhesive layer according to any one of claims 1 to 5, comprising at least one particle. 7. The pressure-sensitive adhesive layer according to any one of claims 1 to 6, which has a total light transmittance of 85% or more. The pressure-sensitive adhesive layer according to any one of claims 1 to 7, wherein the second surface has a reflectance of 0.5 to 3.5%. The pressure-sensitive adhesive layer according to any one of claims 1 to 8, wherein the difference in reflectance between the first surface and the second surface is 0.1 to 3.5%. 10. The pressure-sensitive adhesive layer according to any one of claims 1 to 9, which has a gel fraction of 30 to 95% by weight. The pressure-sensitive adhesive layer according to any one of claims 1 to 10, wherein the 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 11, which has a tan δ peak value of -5 to -50°C in dynamic viscoelasticity measurement at 1 Hz. A method for producing an adhesive layer according to any one of claims 1 to 12,
Step (1) of forming a base pressure-sensitive adhesive layer on a support from a pressure-sensitive adhesive composition containing a base polymer;
step (2) of preparing a dispersion in which a low refractive index material having a refractive index lower than that of the base polymer is dispersed;
The dispersion is applied to the second surface of the base pressure-sensitive adhesive layer opposite to the first surface on the support side, and the low refractive index material contained in the dispersion is applied to the base pressure-sensitive adhesive layer. The step (3) of permeating from the second surface in the thickness direction, and the step (4) of drying the adhesive layer in which the low refractive index material has permeated,
A method for producing a pressure-sensitive adhesive layer, comprising: A pressure-sensitive adhesive sheet comprising the pressure-sensitive adhesive layer according to any one of claims 1 to 12 and a support on one 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 or both sides of the optical film,
The pressure-sensitive adhesive layer on one side or both sides is the pressure-sensitive adhesive layer according to any one of claims 1 to 12, and the first surface side of the pressure-sensitive adhesive layer is provided on the optical film. Optical film with adhesive layer. 16. The pressure-sensitive adhesive layer-carrying optical film according to claim 15, wherein the optical film is a polarizing film. 17. An optical laminate comprising the optical film with an adhesive layer according to claim 15 or 16 and an optical member with a low refractive index attached 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 12, the pressure-sensitive adhesive layer-attached optical film according to claim 15 or 16, or the optical laminate according to claim 17.

Images