Circular polarizing plate with adhesive layer

Abstract

To provide a circularly polarizing plate with adhesive layers that is easily transferred, by suppressing formation of air bubbles of a separator film (base material film) and adhesive layers.SOLUTION: A circularly polarizing plate with adhesive layers comprises in the following order: a first base material film; a first adhesive layer; a polarizing plate; an adhesive layer; a phase difference layer; a second adhesive layer; and a second base material film. In the circularly polarizing plate with adhesive layers, a total thickness (T1) of a laminate (laminate a) consisting of layers from the first base material film to the first adhesive layer, and a total thickness (T2) of a laminate (laminate b) consisting of layers positioned between the first adhesive layer and the second adhesive layer, satisfy the formula (1): T1≥T2 (1). The total thickness (T2) of the laminate b and a thickness (T3) of the second base material film satisfy the formula (2): T3≥T2 (2). Further, a peeling force (F1) when peeling off the laminate a, and a peeling force (F2) when peeling off the second base material film, from the circularly polarizing plate with adhesive layers, satisfy the formula (3): F1<F2 (3).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a circularly polarizing plate with a pressure-sensitive adhesive layer. [Background technology]

[0002] Circular polarizing plates comprising a polarizing film and a retardation film are widely used in flat panel displays (FPDs) such as organic electroluminescence (EL) display devices. Circular polarizing plates are sometimes configured as optical laminates with a pressure-sensitive adhesive layer, with a pressure-sensitive adhesive layer provided on one surface thereof, and are often used by being attached to a display element such as a liquid crystal cell or an organic electroluminescence (EL) display element via the pressure-sensitive adhesive layer. Such optical laminates with a pressure-sensitive adhesive layer are usually laminated with a separate film that is peeled off and removed when the pressure-sensitive adhesive layer is used to protect the pressure-sensitive adhesive layer before being attached to the display element, and a surface protection film for protecting the optical laminate may also be laminated on the side of the optical laminate opposite to the side protected by the separate film (e.g., Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-18354 Summary of the Invention [Problem to be solved by the invention]

[0004] The optical laminate disclosed in the above-mentioned patent document can be incorporated into a display device or the like by transferring the laminate portion having the circular polarizer function to a substrate, i.e., by peeling off the surface protective film and the separate film in order and attaching the laminate to the substrate via an adhesive layer or the like.

[0005] In recent years, display devices have become increasingly thinner, and it is widely known that a coating layer obtained by polymerizing a polymerizable liquid crystal compound is used as each layer constituting a circular polarizing plate, such as a polarizer or a retardation layer. However, the present inventors have found that in the optical laminate disclosed in the above-mentioned patent document, when the layer structure of the optical laminate including the polarizer, the retardation layer, etc. is very thin, when the surface protection film is peeled off first, bubbles are likely to be generated between the separate film and the pressure-sensitive adhesive layer adjacent to the separate film.

[0006] The present invention aims to provide a circular polarizing plate with a pressure-sensitive adhesive layer, which has a peelable substrate film and a pressure-sensitive adhesive layer on both sides and has a very thin optical laminate structure, but which, when peeling one substrate film and transferring it to a transfer target, suppresses the generation of air bubbles between the other substrate film that is peeled later and the pressure-sensitive adhesive layer adjacent to it, and can be easily transferred to any transfer target. [Means for solving the problem]

[0007] The present inventors have conducted extensive research to solve the above problems and have completed the present invention. That is, the present invention includes the following aspects. [1] A circularly polarizing plate with a pressure-sensitive adhesive layer, comprising a first substrate film, a first pressure-sensitive adhesive layer, a polarizing plate, a tacky adhesive layer, a retardation layer, a second pressure-sensitive adhesive layer, and a second substrate film in this order, a laminate (laminate a) consisting of layers from the first base film to the first PSA layer is peelable from the layer adjacent to the surface of the first PSA layer opposite to the first base film, and the second base film is peelable from the second PSA layer; The total thickness (T1) of the laminate a and the total thickness (T2) of the laminate (laminate b) consisting of a layer located between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer are expressed by the following formula (1): T1≧T2 (1) and The total thickness (T2) of the laminate b and the thickness (T3) of the second base film are expressed by the following formula (2): T3≧T2 (2) Fulfilling The peel force (F1) when peeling the laminate a from the pressure-sensitive adhesive layer-attached circularly polarizing plate and the peel force (F2) when peeling the second base film from the pressure-sensitive adhesive layer-attached circularly polarizing plate are expressed by the following formula (3): F1 <F2 (3) A circular polarizing plate with an adhesive layer that satisfies the above requirements. [2] The circularly polarizing plate with a pressure-sensitive adhesive layer according to [1] above, wherein the peel force (F1) when peeling the laminate a from the circularly polarizing plate with a pressure-sensitive adhesive layer is 4 gf / inch or more. [3] The peel force (F1) when peeling the laminate a from the pressure-sensitive adhesive layer-attached circular polarizing plate and the peel force (F2) when peeling the second base film are expressed by the following formula (4): F2-F1≧1gf / inch (4) The pressure-sensitive adhesive layer-attached circular polarizing plate according to [1] or [2] above, which satisfies the above condition. [4] The circularly polarizing plate with a pressure-sensitive adhesive layer according to any one of [1] to [3] above, wherein the polarizing plate comprises a polarizer and a diffusion prevention layer located on the first pressure-sensitive adhesive layer side of the polarizer. [5] The pressure-sensitive adhesive layer-attached circularly polarizing plate according to any one of [1] to [4] above, wherein the laminate b has a total thickness of 20 μm or less. [6] The pressure-sensitive adhesive layer-attached circularly polarizing plate according to any one of the above [1] to [5], wherein the laminate a has a total thickness of 30 to 120 μm. [7] The pressure-sensitive adhesive layer-attached circular polarizing plate according to [4] above, wherein the thickness of the diffusion prevention layer is 5 μm or less. [8] The circular polarizing plate with an adhesive layer according to any one of [1] to [7], wherein the polarizing plate comprises a polarizer which is a liquid crystal cured film of a polymerizable liquid crystal composition containing a polymerizable liquid crystal compound exhibiting a smectic liquid crystal phase and a dichroic dye. [9] The circularly polarizing plate with an adhesive layer according to any one of [1] to [8], wherein the retardation layer is a horizontally aligned liquid crystal cured film in which a polymerizable liquid crystal compound is cured in a state where the polymerizable liquid crystal compound is aligned horizontally relative to the plane of the substrate.

[10] A step of peeling off the laminate a from the pressure-sensitive adhesive layer-attached circular polarizing plate according to any one of [1] to [9] above; and a step of laminating an adherend via a pressure-sensitive adhesive layer to the surface adjacent to the laminate a peeled off in the peeling step A method for producing an optical laminate, comprising:

[11] The method for producing an optical laminate according to

[10] above, further comprising a step of peeling off the second base film as a step downstream of the step of peeling off the laminate a. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a circular polarizing plate with an adhesive layer that has a peelable substrate film and an adhesive layer on both sides and has a very thin optical laminate structure, but when one substrate film is peeled off and transferred to a transfer target, the generation of air bubbles between the other substrate film that is peeled off later and the adhesive layer adjacent to it is suppressed, and the plate can be easily transferred to any transfer target. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic cross-sectional view showing an example of a layer structure of a pressure-sensitive adhesive layer-attached circularly polarizing plate of the present invention. [Figure 2] 1 is a schematic cross-sectional view showing an example of a layer structure of a pressure-sensitive adhesive layer-attached circularly polarizing plate of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described in detail. Note that the scope of the present invention is not limited to the embodiments described here, and various modifications can be made without departing from the spirit of the present invention.

[0011] The pressure-sensitive adhesive layer-attached circular polarizing plate of the present invention includes, in this order, a first base film, a first pressure-sensitive adhesive layer, a polarizing plate, a tacky adhesive layer, a retardation layer, a second pressure-sensitive adhesive layer, and a second base film. Hereinafter, an example of the layer structure of the pressure-sensitive adhesive layer-attached circular polarizing plate of the present invention will be described with reference to the drawings, but the pressure-sensitive adhesive layer-attached circular polarizing plate of the present invention is not limited to these embodiments.

[0012] The pressure-sensitive adhesive layer-attached circular polarizer 11 shown in FIG. 1 is formed by laminating, in this order, a first base film 1, a first pressure-sensitive adhesive layer 2, a polarizer 3, a tacky adhesive layer 4, a retardation layer 5, a second pressure-sensitive adhesive layer 6, and a second base film 7. In the pressure-sensitive adhesive layer-attached circular polarizer 11 shown in FIG. 1, the first base film 1 and the first pressure-sensitive adhesive layer 2 are peelable from each other at the layer adjacent to the surface of the first pressure-sensitive adhesive layer 2 opposite to the first base film 1 (between the first pressure-sensitive adhesive layer 2 and the polarizer 3 in FIG. 1), and the second base film 7 is peelable from the second pressure-sensitive adhesive layer 6. By peeling the first base film 1 together with the first pressure-sensitive adhesive layer 2 from the pressure-sensitive adhesive layer-attached circular polarizer 11, a surface of the polarizer 3 exposed by peeling the first base film 1 and the first pressure-sensitive adhesive layer 2 of the laminate structure 12 consisting of the polarizer 3, the tacky adhesive layer 4, the retardation layer 5, the second pressure-sensitive adhesive layer 6, and the second base film 7 can be attached to, for example, a pressure-sensitive adhesive front panel. Next, the releasable second substrate film 7 is peeled off and transferred to a transfer recipient (substrate) such as an OLED substrate via the second pressure-sensitive adhesive layer 6, thereby obtaining a display device including a circular polarizer 13 consisting of the polarizer 3, the tacky adhesive layer 4, and the retardation layer 5. In order to achieve the object of the present invention of suppressing the generation of bubbles between the second substrate film and the second pressure-sensitive adhesive layer when peeling the first substrate film together with the first pressure-sensitive adhesive layer, it is assumed that the order of peeling the first substrate film and the second substrate film from the pressure-sensitive adhesive layer-attached circular polarizer of the present invention is such that the first substrate film is peeled off together with the first pressure-sensitive adhesive layer first, and then the second substrate film is peeled off.

[0013] In a preferred embodiment of the present invention, the pressure-sensitive adhesive layer-attached circular polarizer of the present invention includes a polarizer and a diffusion prevention layer located on the first pressure-sensitive adhesive layer side of the polarizer. The pressure-sensitive adhesive layer-attached circular polarizer 11 shown in FIG. 2 has a diffusion prevention layer 32 between the first pressure-sensitive adhesive layer 2 and the polarizer 31. To improve the effect of suppressing the diffusion of dichroic dye from the polarizer, a diffusion prevention layer 33 may also be provided on the surface of the polarizer 31 opposite the first pressure-sensitive adhesive layer 2. In this specification, when a diffusion prevention layer is laminated on one or both surfaces of the polarizer, the polarizer and the diffusion prevention layer laminated on one or both surfaces thereof are collectively referred to as a polarizing plate. The polarizer and the diffusion prevention layer may be adjacent to each other or may be laminated via, for example, an alignment film for forming the polarizer. In this case, the alignment film for forming the polarizer is also considered to be one of the layers constituting the polarizing plate.

[0014] The pressure-sensitive adhesive layer-attached circular polarizing plate of the present invention may further include other layers in addition to the first substrate film, the first pressure-sensitive adhesive layer, the polarizing plate, the adhesive layer, the retardation layer, the second pressure-sensitive adhesive layer, and the second substrate film, as long as the effects of the present invention are not affected. Examples of the other layers include an alignment film for forming the retardation layer, a second retardation layer, an adhesive layer other than the adhesive layer between the polarizing plate and the retardation layer, and a resin layer having UV absorption ability.

[0015] Hereinafter, in this specification, a laminate consisting of layers from the first base film to the first pressure-sensitive adhesive layer will also be referred to as "laminate a." Furthermore, a laminate consisting of layers located between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer will also be referred to as "laminate b." In the present invention, laminate b is a laminate that essentially functions as a circularly polarizing plate.

[0016] In the pressure-sensitive adhesive layer-attached circularly polarizing plate of the present invention, the total thickness of the laminate a (hereinafter, the total thickness of the laminate a is referred to as "T1") and the total thickness of the laminate b (hereinafter, the total thickness of the laminate a is referred to as "T2") satisfy the following formula (1): T1≧T2 (1) and the total thickness T2 of the laminate b and the thickness of the second base film (hereinafter, the thickness of the second base film will be referred to as "T3") satisfy the formula (2): T3≧T2 (2) Meet the following. When the total thickness T1 of the laminate a and the total thickness T2 of the laminate b satisfy the relationship represented by formula (1), and the total thickness T2 of the laminate b and the thickness T3 of the second base film satisfy the relationship represented by formula (2), lifting is unlikely to occur between the second base film and the second pressure-sensitive adhesive layer when the laminate a is peeled off from the pressure-sensitive adhesive layer-attached circular polarizing plate of the present invention, and the effect of suppressing the generation of bubbles between the two layers due to lifting is excellent.

[0017] In the present invention, the difference between the total thickness T1 of the laminate a and the total thickness T2 of the laminate b is not particularly limited, as long as it is the same as or thicker than T2. ​​Since this tends to improve the effect of suppressing the generation of bubbles between the second base film and the second pressure-sensitive adhesive layer when the laminate a is peeled off, the difference between T1 and T2, expressed as T1 / T2, is preferably 1.2 or more, more preferably 1.5 or more, even more preferably 2.0 or more, and may even be 2.5 or more. The upper limit of the T1 / T2 value is not particularly limited, but is usually 10 or less, preferably 8 or less.

[0018] The value of T1 can be controlled by adjusting the thickness of each layer constituting the laminate a, such as the first base film and the first pressure-sensitive adhesive layer. The thickness of each layer in the laminate a can be determined appropriately depending on the base film, pressure-sensitive adhesive layer, etc. used. However, from the viewpoint of ensuring easy peelability of the laminate a, when the laminate a is composed of a first base film and a first pressure-sensitive adhesive layer, it is preferable that the thickness of the first pressure-sensitive adhesive layer is smaller than the thickness of the first base film. In one embodiment of the present invention, the laminate a consists only of the first base film and the first pressure-sensitive adhesive layer.

[0019] Furthermore, the difference in total thickness T2 of laminate b is not particularly limited as long as it is the same as or thinner than the thickness T3 of the second base film. Since this tends to improve the effect of suppressing the generation of bubbles between the second base film and the second pressure-sensitive adhesive layer when peeling laminate a, the difference between T2 and T3, expressed as T3 / T2, is preferably 1.2 or more, more preferably 1.5 or more, and may even be 2.0 or more. The upper limit of the T3 / T2 value is not particularly limited, but is usually 10 or less, and preferably 8 or less.

[0020] The value of T2 can be controlled by adjusting the thickness of each layer constituting the laminate b, such as the polarizing plate and the retardation layer. The pressure-sensitive adhesive layer-attached circular polarizing plate of the present invention can achieve particularly significant effects, such as suppressing the generation of bubbles during transfer, particularly when the thickness of the circular polarizing plate to be transferred later is extremely thin (for example, 20 μm or less, as described below). For example, when the polarizer, alignment film, and diffusion prevention layer constituting the polarizing plate, as well as the retardation layer, are composed of coating layers, it is possible to make the value of T2 very small.

[0021] The relationship between the total thickness T1 of the laminate a and the thickness T3 of the second base film is not particularly limited, but usually, the total thickness T1 of the laminate a comprising the first base film and the first PSA layer is the same as or thicker than T3, that is, the relationship is expressed by the formula (5): T1≧T3 (5) The difference between T1 and T3, expressed as the value of T1 / T3, is preferably 1.0 or more, more preferably 1.2 or more. The upper limit of the value of T1 / T3 is not particularly limited, but is usually 10 or less, preferably 8 or less.

[0022] In the present invention, the peel force (F1) when peeling the laminate a from the pressure-sensitive adhesive layer-attached circularly polarizing plate and the peel force (F2) when peeling the second base film from the pressure-sensitive adhesive layer-attached circularly polarizing plate are expressed by the following formula (3): F1 <F2 (3) Meet the following. When the peel strength F1 and the peel strength F2 satisfy the relationship expressed by the above formula (3), an appropriate strength relationship is created between the adhesion strength of the first pressure-sensitive adhesive layer in the pressure-sensitive adhesive layer-attached circular polarizer and the adhesion strength of the second base film in the pressure-sensitive adhesive layer-attached circular polarizer. Therefore, when the above relationship is satisfied, the laminate a is easily peeled when it is first peeled from the pressure-sensitive adhesive layer-attached circular polarizer, and lifting is unlikely to occur between the second base film and the second pressure-sensitive adhesive layer when the laminate a is peeled, which is excellent in suppressing the generation of bubbles due to such lifting. This is expected to be effective in suppressing deterioration of the optical performance of the circular polarizer that may occur during transfer. The difference in peel strength also occurs when F2 is smaller than F1 (i.e., F1 > F2). In this case, it is difficult to first peel the laminate a from the pressure-sensitive adhesive layer-attached circular polarizer, which is likely to lead to the generation of wrinkles during transfer.

[0023] The above effect can be expected when the peel force F1 on the side that is peeled first is smaller than the peel force F2 on the side that is peeled last. In order to improve the effect more easily, it is preferable that F1 and F2 satisfy the formula (4): F2-F1≧1gf / inch (4) It is preferable that the following is satisfied. The value of F2-F1 is more preferably 1.5 gf / inch or more, even more preferably 2.0 gf / inch or more, and particularly preferably 5 gf / inch or more. When the value of F2 is larger and the difference between the value of F2 and the value of F1 is large, the effect of suppressing the generation of bubbles between the second base film and the second pressure-sensitive adhesive layer when peeling the laminate a is more likely to be significant, and therefore in one embodiment of the present invention, the value of F2-F1 may be, for example, 5.0 gf / inch or more, or 8.0 gf / inch or more.

[0024] In the present invention, the peel force F1 is preferably 4.0 gf / inch or more, more preferably 4.2 gf / inch or more, and even more preferably 4.4 gf / inch or more. When the peel force F1 is equal to or greater than the lower limit, it is easy to control the peel force F1 in relation to the peel force F2 within a range that is effective in suppressing the generation of bubbles between the second base film and the second pressure-sensitive adhesive layer when peeling the laminate a. It is also possible to suppress unintended peeling of the laminate a before transfer and incorporation into a display device or the like. The upper limit of the peel force F1 is not particularly limited as long as it is smaller than the peel force F2, but is usually less than 25 gf / inch.

[0025] In the present invention, the peel force F2 is preferably 4.5 gf / inch or more, more preferably 5.0 gf / inch or more, even more preferably 5.5 gf / inch or more, and may be, for example, 10.0 gf / inch or more. When the peel force F2 is equal to or greater than the lower limit, the effect of suppressing the generation of bubbles between the second substrate film and the second pressure-sensitive adhesive layer when the laminate a is first peeled from the pressure-sensitive adhesive layer-attached circular polarizer is likely to be improved. Furthermore, the peel force F2 is preferably 25 gf / inch or less, more preferably 20 gf / inch or less, and even more preferably 18 gf / inch or less. When the peel force F2 is equal to or less than the upper limit, easy peelability can be ensured when the second substrate film is peeled from the pressure-sensitive adhesive layer-attached circular polarizer, while a high effect of suppressing the generation of bubbles between the second substrate film and the second pressure-sensitive adhesive layer when the laminate a is peeled can be expected.

[0026] The peel strengths F1 and F2 are measured as the peel strength required to peel the laminate a or the second substrate film for which the peel strength is to be measured from the circular polarizer with a pressure-sensitive adhesive layer of the test specimen, which is prepared by, for example, attaching the surface of the pressure-sensitive adhesive circular polarizer to a glass plate with a pressure-sensitive adhesive, from which the substrate film or laminate (e.g., the second substrate film when measuring F1, or the laminate a when measuring F2) has been peeled, opposite the substrate film for which the peel strength is to be measured. The peel strengths F1 and F2 are measured as the peel strength required to peel the laminate a or the second substrate film for which the peel strength is to be measured from the circular polarizer with a pressure-sensitive adhesive layer of the test specimen. The peel strength can be measured in accordance with the 180° peel test method specified in JIS K 6854. The detailed method for measuring the peel strengths F1 and F2 is described in the Examples below.

[0027] The peel strengths F1 and F2 can be adjusted by, for example, the configuration and thickness of the layers adjacent to the laminate a and the second base film, respectively, the type and thickness of the first pressure-sensitive adhesive layer and the second base film, surface treatment of the first pressure-sensitive adhesive layer, the second base film, and / or these layers or layers adjacent to the base films, etc. For example, the peel strength of the laminate a or the second base film from the PSA-layered circular polarizer can be controlled by subjecting the outermost layer of the circular polarizer (laminate b) adjacent to the laminate a and / or the surface of the second base film to a modification treatment, or by providing a layer for adjusting the peel strength as a layer adjacent to the first pressure-sensitive adhesive layer and / or the second base film.

[0028] Hereinafter, each component of the pressure-sensitive adhesive layer-attached circularly polarizing plate of the present invention will be described in detail.

[0029] [First base film and second base film]

[0030] In the pressure-sensitive adhesive layer-attached circular polarizer of the present invention, the first substrate film is a layer laminated on the circular polarizer so as to be peelable together with the first pressure-sensitive adhesive layer from the layer adjacent to the surface of the first pressure-sensitive adhesive layer on the opposite side of the first substrate film of the pressure-sensitive adhesive layer-attached circular polarizer. The layers from the first substrate film to the first pressure-sensitive adhesive layer are preferably laminated with a certain degree of adhesion so that they can be peeled off together during peeling. On the other hand, the second substrate film is a layer peelably laminated between the first substrate film and the second pressure-sensitive adhesive layer provided on the outermost layer of the circular polarizer.

[0031] The thickness of the first base film is not particularly limited and may be appropriately determined depending on the material of the base film, the configuration of the layer adjacent to the base film, etc. From the viewpoint of being able to expect a high effect of suppressing the occurrence of wrinkles when peeling the laminate a from the circularly polarizing plate with the pressure-sensitive adhesive layer, particularly when continuous transfer is performed by a roll-to-roll manufacturing method, the thickness may be preferably 20 μm or more, more preferably 30 μm or more, and even more preferably 50 μm or more, and is also preferably 110 μm or less, more preferably 100 μm or less, and even more preferably 90 μm or less.

[0032] The thickness of the second base film is not particularly limited and may be appropriately determined depending on the material of the base film, the configuration of the layer adjacent to the base film, etc. It may be preferably 10 μm or more, more preferably 20 μm or more, and even more preferably 30 μm or more, and is preferably 100 μm or less, more preferably 80 μm or less, and even more preferably 50 μm or less. When the thickness of the second base film is within the above range, the laminate structure of the circular polarizer is easily and effectively reinforced when peeling the laminate a from the pressure-sensitive adhesive layer-attached circular polarizer, and the effect of suppressing the generation of bubbles between the second base film and the second pressure-sensitive adhesive layer is easily improved.

[0033] In the pressure-sensitive adhesive layer-attached circular polarizing plate of the present invention, the thicknesses of the first substrate film and the second substrate film may be the same or different. When the thicknesses of the first substrate film and the second substrate film are different, and when the first substrate film is thicker than the second substrate film, the effects of the present invention are more likely to be achieved stably. The thickness of the substrate film can be measured using a laser microscope, a film thickness meter, or the like, and the same applies to the measurement of the thicknesses of each layer or film, such as a polarizer or a retardation layer, constituting the pressure-sensitive adhesive layer-attached circular polarizing plate hereinafter.

[0034] The first and second substrate films can be, for example, resin films conventionally known in the field of optical films. Examples of resins constituting the first and second substrate films include polyolefins such as polyethylene, polypropylene, and norbornene-based polymers; cyclic olefin-based resins; polyvinyl alcohol; polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polymethacrylates; polyacrylic esters; cellulose-based resins such as triacetyl cellulose, diacetyl cellulose, and cellulose acetate propionate; polycarbonates; polysulfones; polyethersulfones; polyetherketones; and plastics such as polyphenylene sulfide and polyphenylene oxide. Among these, from the viewpoint of smoothness and quality as a coating substrate, at least one resin selected from cellulose-based resins, cyclic olefin-based resins, and polyester-based resins (particularly polyethylene terephthalate resins) is preferred. These resins may be used alone or in combination of two or more. Such resins can be formed into a resin film by known methods such as solvent casting and melt extrusion. The first base film and the second base film may be the same or different. In this specification, when simply referring to a "base film," the "base film" includes the first base film and the second base film.

[0035] In order to easily impart the desired releasability and adhesion to the surface of the substrate film, the surface of the substrate film may be subjected to a modification treatment such as corona treatment, plasma treatment, or flame treatment, depending on the configuration of the adjacent layer, etc. In the pressure-sensitive adhesive layer-attached circularly polarizing plate of the present invention, when the first substrate film and / or the second substrate film are subjected to a surface modification treatment, the treatment methods may be the same or different.

[0036] [First Pressure-Sensitive Adhesive Layer and Second Pressure-Sensitive Adhesive Layer] The pressure-sensitive adhesive layer-equipped circular polarizer of the present invention has a first pressure-sensitive adhesive layer on the polarizer-side surface of the first substrate film and a second pressure-sensitive adhesive layer on the retardation layer-side surface of the second substrate film. In the present invention, the first substrate film and the second substrate film each form a laminate having a circular polarization function via a pressure-sensitive adhesive layer, and the second pressure-sensitive adhesive layer is present on one outer layer of the laminate b incorporated (transferred) into a display device. In the pressure-sensitive adhesive layer-equipped circular polarizer of the present invention having such a structure, the first substrate film and the first pressure-sensitive adhesive layer are preferably disposed adjacent to each other in order to fully suppress the generation of bubbles between the second substrate film and the second pressure-sensitive adhesive layer, which may occur when peeling off the laminate a including the first substrate film and the first pressure-sensitive adhesive layer. Furthermore, the second substrate film and the second pressure-sensitive adhesive layer are preferably disposed adjacent to each other. In this specification, when the term "pressure-sensitive adhesive layer" is simply used, the "pressure-sensitive adhesive layer" is intended to encompass both the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer.

[0037] The first pressure-sensitive adhesive layer is a layer that has sufficient adhesion to allow the first base film to be bonded to laminate b before transfer, and can be peeled off together with the first base film to form laminate a. On the other hand, the second pressure-sensitive adhesive layer preferably has sufficient adhesion to allow the second base film to be bonded to laminate b before transfer, similar to the first pressure-sensitive adhesive layer, and functions as a pressure-sensitive adhesive layer for bonding to a transfer-receiving object such as a substrate after the second base film is peeled off. The adhesion of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer to the base film and / or to the transfer-receiving object can be controlled by the types, content ratios, thicknesses, etc. of the components constituting each pressure-sensitive adhesive layer. Pressure-sensitive adhesive layers having such functions can be prepared using materials conventionally known in the art. Examples include compositions (hereinafter also referred to as "pressure-sensitive adhesive layer-forming compositions") whose main components are (meth)acrylic, rubber, urethane, ester, silicone, or polyvinyl ether resins. In particular, from the viewpoint of excellent transparency, adhesiveness, weather resistance, heat resistance, etc., it is preferable that the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer are each formed from a composition having a (meth)acrylic resin as a base polymer. In particular, it is preferable that the second pressure-sensitive adhesive layer incorporated into a display device together with the circularly polarizing plate (laminate b) is formed from a composition having a (meth)acrylic resin as a base polymer.

[0038] The (meth)acrylic resin (base polymer) used in the pressure-sensitive adhesive layer-forming composition is preferably a polymer or copolymer containing one or more (meth)acrylic acid esters as monomers, such as butyl (meth)acrylate, ethyl (meth)acrylate, isooctyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. A polar monomer is preferably copolymerized into the base polymer. Examples of polar monomers include monomers having a carboxyl group, a hydroxyl group, an amide group, an amino group, or an epoxy group, such as (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, (meth)acrylamide, N,N-dimethylaminoethyl (meth)acrylate, and glycidyl (meth)acrylate.

[0039] In one embodiment of the present invention, the structural units derived from (meth)acrylic acid esters in the (meth)acrylic resin constituting the pressure-sensitive adhesive layer preferably account for 80 to 99.9 mass%, more preferably 85 mass% or more, and even more preferably 90 mass% or more of the total mass of all structural units constituting the (meth)acrylic resin. Furthermore, when the (meth)acrylic resin contains structural units derived from polar monomers, the structural units derived from the polar monomers preferably account for 0.1 to 10 mass%, more preferably 0.5 mass% or more, even more preferably 1 mass% or more, and even more preferably 8 mass% or less of the total mass of all structural units constituting the (meth)acrylic resin.

[0040] The (meth)acrylic resin constituting the pressure-sensitive adhesive layer can be produced by various known methods, such as solution polymerization, emulsion polymerization, bulk polymerization, and suspension polymerization. A polymerization initiator is usually used in the production of this acrylic resin. The content of the polymerization initiator is preferably 0.001 to 5 parts by mass relative to 100 parts by mass of the total of all monomers used in the production of the (meth)acrylic resin.

[0041] The polymerization initiator may be a thermal polymerization initiator or a photopolymerization initiator. Examples of the thermal polymerization initiator include azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile), dimethyl-2,2'-azobis(2-methylpropionate), and 2,2'-azobis(2-hydroxymethylpropionitrile); lauryl peroxide; Examples of suitable peroxides include organic peroxides such as tert-butyl hydroperoxide, benzoyl peroxide, tert-butyl peroxybenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, dipropyl peroxydicarbonate, tert-butyl peroxyneodecanoate, tert-butyl peroxypivalate, and (3,5,5-trimethylhexanoyl) peroxide; and inorganic peroxides such as potassium persulfate, ammonium persulfate, and hydrogen peroxide. Examples of suitable photopolymerization initiators include 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone.

[0042] When preparing a (meth)acrylic resin by solution polymerization, a method can be used in which the desired monomer and organic solvent are mixed, a thermal polymerization initiator is added under a nitrogen atmosphere, and the mixture is stirred at 40 to 90°C, preferably 50 to 80°C. To control the reaction, the monomer and polymerization initiator may be added continuously or intermittently during polymerization, or may be added in a dissolved state in an organic solvent. Examples of organic solvents that can be used include aromatic hydrocarbon solvents such as toluene and xylene; ester solvents such as ethyl acetate and butyl acetate; aliphatic alcohol solvents such as propyl alcohol and isopropyl alcohol; and ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone.

[0043] The weight average molecular weight of the (meth)acrylic resin is preferably 1×10 in terms of standard polystyrene as determined by gel permeation chromatography. 5 ~2.5×10 5 and more preferably 1.4 × 10 5 ~2×10 5 is.

[0044] The pressure-sensitive adhesive layer may contain only the acrylic resin, or may be formed in combination with a crosslinking agent. Examples of crosslinking agents include divalent or higher metal ions that form metal carboxylates with carboxyl groups, polyamine compounds that form amide bonds with carboxyl groups, polyepoxy compounds or polyols that form ester bonds with carboxyl groups, and polyisocyanate compounds that form amide bonds with carboxyl groups.

[0045] In addition to the acrylic resin component, the pressure-sensitive adhesive layer may contain, as necessary, components useful for controlling the peelability and adhesion between the pressure-sensitive adhesive layer and an adjacent layer. Examples of such components include isocyanate compounds, silane compounds (particularly silane coupling agents), antistatic components, etc. When the pressure-sensitive adhesive layer-forming composition contains these components, the content thereof may be appropriately determined depending on the components to be blended, the desired effect, etc.

[0046] In one embodiment of the present invention, the first PSA layer preferably contains the above-mentioned useful components so that the first PSA layer can be peeled from the adjacent layer on the surface opposite to the first base film. Alternatively, the first base film may be subjected to a surface treatment, for example, as appropriate, to increase the adhesion between the first base film and the first PSA layer. On the other hand, the second pressure-sensitive adhesive layer is a layer that is incorporated into the display device after the second base film is peeled off, and is preferably a layer that is laminated with an adjacent layer on the side of the layer opposite the second base film with appropriate adhesion.

[0047] The pressure-sensitive adhesive layer can be provided, for example, by applying a pressure-sensitive adhesive layer-forming composition, in which the acrylic resin described above as the main component is dissolved in a solvent, to a substrate film or the like on which the pressure-sensitive adhesive layer is to be laminated by a bar coating method or the like, and then drying the composition. Examples of the solvent include the same ones as those exemplified in the method for preparing the acrylic resin.

[0048] Furthermore, as the laminate a comprising the first base film and the first pressure-sensitive adhesive layer, a commercially available protective sheet having a peelable property and in which a pressure-sensitive adhesive layer is formed on a base film may be used.

[0049] The thickness of the pressure-sensitive adhesive layer may be appropriately determined depending on the configuration of the pressure-sensitive adhesive layer, the configuration and size of the display device, etc. The thickness of the first pressure-sensitive adhesive layer and the thickness of the second pressure-sensitive adhesive layer may be the same as or different from each other.

[0050] In one embodiment of the present invention, the thickness of the first pressure-sensitive adhesive layer is preferably 5 to 80 μm, more preferably 10 μm or more, even more preferably 15 μm or more, and more preferably 50 μm or less, even more preferably 30 μm or less. The thickness of the second pressure-sensitive adhesive layer is preferably 10 to 100 μm, more preferably 15 μm or more, even more preferably 20 μm or more, and more preferably 80 μm or less, even more preferably 50 μm or less.

[0051] [Polarizing plate] In the present invention, the polarizing plate is a layer having a polarizing function and is configured to include at least a polarizer. The polarizer includes a dichroic dye, which is a dye having absorption anisotropy. From the viewpoint of being advantageous for making the transferred circular polarizer ultra-thin, the polarizer included in the polarizing plate in the pressure-sensitive adhesive layer-attached circular polarizing plate of the present invention is preferably a coating layer, and is a cured layer formed from a polymerizable liquid crystal composition (hereinafter also referred to as a "polarizer-forming composition") containing at least one liquid crystal compound, preferably a polymerizable liquid crystal compound and a dichroic dye.

[0052] The polymerizable liquid crystal compound (hereinafter also referred to as "polymerizable liquid crystal compound (A)") contained in the polarizer-forming composition for forming the polarizer of the present invention is a compound having at least one polymerizable group. Here, the polymerizable group refers to a group that can be involved in a polymerization reaction by an active radical or an acid generated from a polymerization initiator. Examples of the polymerizable group contained in the polymerizable liquid crystal compound (A) include a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, a (meth)acryloyl group, an oxiranyl group, and an oxetanyl group. Among these, a radically polymerizable group is preferred, a (meth)acryloyl group, a vinyl group, or a vinyloxy group is more preferred, and a (meth)acryloyl group is even more preferred. When the polymerizable liquid crystal compound for forming the polarizer has the same functional group (polymerizable group), such as a (meth)acryloyl group, as the functional group contained in the compound for forming the alignment film for forming the polarizer described below, the alignment film and the polarizer have high compatibility and excellent adhesion between the layers.

[0053] In the present invention, the polymerizable liquid crystal compound (A) is preferably a compound exhibiting smectic liquid crystallinity. By using a polymerizable liquid crystal compound exhibiting smectic liquid crystallinity, a polarizer with a high degree of orientational order can be formed. From the viewpoint of achieving a higher degree of orientational order, the liquid crystal state exhibited by the polymerizable liquid crystal compound (A) is more preferably a high-order smectic phase (high-order smectic liquid crystal state). Here, the high-order smectic phase refers to a smectic B phase, a smectic D phase, a smectic E phase, a smectic F phase, a smectic G phase, a smectic H phase, a smectic I phase, a smectic J phase, a smectic K phase, and a smectic L phase. Among these, a smectic B phase, a smectic F phase, and a smectic I phase are more preferred. The liquid crystallinity may be either thermotropic or lyotropic, but a thermotropic liquid crystal is preferred because it allows precise control of the film thickness. The polymerizable liquid crystal compound (A) may be a monomer, or may be an oligomer or polymer in which a polymerizable group is polymerized.

[0054] The polymerizable liquid crystal compound (A) is not particularly limited as long as it is a liquid crystal compound having at least one polymerizable group, and any known polymerizable liquid crystal compound can be used, but a compound exhibiting smectic liquid crystallinity is preferred. Examples of such polymerizable liquid crystal compounds include a compound represented by the following formula (A1) (hereinafter sometimes referred to as "polymerizable liquid crystal compound (A1)"). U 1 -V 1 -W 1 -(X 1 -Y 1 ) n -X 2 -W 2 -V 2 -U 2 (A1) [In formula (A1), X 1 and X 2 are each independently a divalent aromatic group or a divalent alicyclic hydrocarbon group, wherein a hydrogen atom contained in the divalent aromatic group or divalent alicyclic hydrocarbon group may be substituted with a halogen atom, an alkyl group having 1 to 4 carbon atoms, a fluoroalkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group, or a nitro group, and a carbon atom constituting the divalent aromatic group or divalent alicyclic hydrocarbon group may be substituted with an oxygen atom, a sulfur atom, or a nitrogen atom, provided that X 1 and X 2 At least one of the groups is an optionally substituted 1,4-phenylene group or an optionally substituted cyclohexane-1,4-diyl group. Y 1 is a single bond or a divalent linking group. n is 1 to 3, and when n is 2 or more, multiple X 1 may be the same or different. 2 Multiple X 1 In addition, when n is 2 or more, a plurality of Y 1 may be the same or different. From the viewpoint of liquid crystal properties, n is preferably 2 or more. U 1represents a hydrogen atom or a polymerizable group. U 2 represents a polymerizable group. W 1 and W 2 are each independently a single bond or a divalent linking group. V 1 and V 2 represent each independently an alkanediyl group having 1 to 20 carbon atoms which may have a substituent, and -CH2- constituting the alkanediyl group may be replaced by -O-, -CO-, -S- or -NH-.

[0055] In the polymerizable liquid crystal compound (A1), X 1 and X 2 are each independently preferably an optionally substituted 1,4-phenylene group or an optionally substituted cyclohexane-1,4-diyl group, and X 1 and X 2 At least one of these is an optionally substituted 1,4-phenylene group or an optionally substituted cyclohexane-1,4-diyl group, preferably a trans-cyclohexane-1,4-diyl group. The optionally substituted 1,4-phenylene group or the optionally substituted cyclohexane-1,4-diyl group may optionally have a substituent, such as an alkyl group having 1 to 4 carbon atoms, a cyano group, or a halogen atom, such as a chlorine atom or a fluorine atom. Preferably, the group is unsubstituted.

[0056] The polymerizable liquid crystal compound (A1) is a compound represented by the formula (A1) having the formula (A1-1): -(X 1 -Y 1 ) n -X 2 - (A1-1) [In the formula, X 1 , Y 1 , X 2 and n have the same meanings as above.] [hereinafter, also referred to as partial structure (A1-1)] preferably has an asymmetric structure, since this facilitates the development of smectic liquid crystal properties. The polymerizable liquid crystal compound (A1) in which the partial structure (A1-1) is an asymmetric structure is, for example, a compound in which n is 1 and one X 1 and X 2 and Y are different from each other. 1 are compounds having the same structure as each other, and two X 1 have the same structure as each other, and one X 2 These two X 1 The polymerizable liquid crystal compound (A1) has a structure different from that of the two X 1 Of the W 1 X binds to 1 But the other X 1 and X 2 The other X 1 and X 2 Furthermore, the polymerizable liquid crystal compound (A1) may be a compound having the same structure as the compound (A1). 1 are compounds having the same structure as each other, and three X 1 and one X 2 The polymerizable liquid crystal compound (A1) may be any one of the following three compounds:

[0057] Y 1 are -CH2CH2-, -CH2O-, -CH2CH2O-, -COO-, -OCOO-, single bond, -N=N-, -CR a =CR b -, -C≡C-, -CR a =N- or -CO-NR a - is preferred. a and R b are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. 1 is more preferably -CH2CH2-, -COO- or a single bond, and 1 If there is an X 2 Y bonded with 1is more preferably -CH2CH2- or CH2O-. 1 and X 2 When all of Y are the same structure, two or more Y 1 It is preferable that there are plural Y 1 When the compound has an asymmetric structure, the compound tends to exhibit smectic liquid crystallinity.

[0058] U 2 is a polymerizable group. 1 is a hydrogen atom or a polymerizable group, preferably a polymerizable group. 1 and U 2 Preferably, both of U are polymerizable groups, and preferably both are radically polymerizable groups. Examples of the polymerizable group include the same groups as those exemplified above as the polymerizable group contained in the polymerizable liquid crystal compound (A). 1 and a polymerizable group represented by U 2 may be different from each other, but are preferably the same type of group, and U 1 and U 2 Preferably, at least one of the groups is a (meth)acryloyl group, and more preferably, both of the groups are (meth)acryloyl groups. The polymerizable group may be in a polymerized state or an unpolymerized state, but is preferably in an unpolymerized state.

[0059] V 1 and V 2 Examples of the alkanediyl group represented by the formula (V) include a methylene group, an ethylene group, a propane-1,3-diyl group, a butane-1,3-diyl group, a butane-1,4-diyl group, a pentane-1,5-diyl group, a hexane-1,6-diyl group, a heptane-1,7-diyl group, an octane-1,8-diyl group, a decane-1,10-diyl group, a tetradecane-1,14-diyl group, and an icosane-1,20-diyl group. 1 and V 2 is preferably an alkanediyl group having 2 to 12 carbon atoms, and more preferably an alkanediyl group having 6 to 12 carbon atoms.

[0060] Examples of the substituent that the alkanediyl group may optionally have include a cyano group and a halogen atom, but the alkanediyl group is preferably unsubstituted, and more preferably an unsubstituted linear alkanediyl group.

[0061] W 1 and W 2 are each independently preferably a single bond, -O-, -S-, -COO- or -OCOO-, more preferably a single bond or -O-.

[0062] The polymerizable liquid crystal compound (A) is not particularly limited as long as it is a polymerizable liquid crystal compound having at least one polymerizable group, and known polymerizable liquid crystal compounds can be used, but it is preferable that it exhibits smectic liquid crystal properties. A structure that is likely to exhibit smectic liquid crystal properties preferably has an asymmetric molecular structure within the molecular structure. Specifically, it is more preferable that it is a polymerizable liquid crystal compound that exhibits smectic liquid crystal properties and has the partial structures (Aa) to (Ai) below. From the perspective of being likely to exhibit higher-order smectic liquid crystal properties, it is more preferable that it has the partial structure (Aa), (Ab), or (Ac). In the following (Aa) to (Ai), * represents a bond (single bond).

[0063] [ka]

[0064] Specific examples of the polymerizable liquid crystal compound (A) include compounds represented by formulae (A-1) to (A-25). When the polymerizable liquid crystal compound (A) has a cyclohexane-1,4-diyl group, the cyclohexane-1,4-diyl group is preferably a trans isomer.

[0065] [ka]

[0066] [ka]

[0067] [ka]

[0068] Among these, at least one selected from the group consisting of compounds represented by formula (A-2), formula (A-3), formula (A-4), formula (A-5), formula (A-6), formula (A-7), formula (A-8), formula (A-13), formula (A-14), formula (A-15), formula (A-16) and formula (A-17) is preferred. As the polymerizable liquid crystal compound (A), one type may be used alone, or two or more types may be used in combination.

[0069] The polymerizable liquid crystal compound (A) can be produced by a known method, for example, as described in Lub et al., Recl. Trav. Chim. Pays-Bas, 115, 321-328 (1996), or Japanese Patent No. 4719156.

[0070] In the present invention, the polarizer-forming composition may contain other polymerizable liquid crystal compounds besides the polymerizable liquid crystal compound (A). However, from the viewpoint of obtaining a polarizer with a high degree of orientational order, the proportion of the polymerizable liquid crystal compound (A) relative to the total mass of all polymerizable liquid crystal compounds contained in the polarizer-forming composition is preferably 51 mass% or more, more preferably 70 mass% or more, and even more preferably 90 mass% or more.

[0071] When the polarizer-forming composition contains two or more polymerizable liquid crystal compounds (A), at least one of them may be the polymerizable liquid crystal compound (A1), or all of them may be the polymerizable liquid crystal compound (A1). By combining multiple polymerizable liquid crystal compounds, it may be possible to temporarily maintain liquid crystallinity even at a temperature below the liquid crystal-crystalline phase transition temperature.

[0072] The content of the polymerizable liquid crystal compound in the polarizer-forming composition is preferably 40 to 99.9% by mass, more preferably 60 to 99% by mass, and even more preferably 70 to 99% by mass, based on the solid content of the polarizer-forming composition. When the content of the polymerizable liquid crystal compound is within the above range, the orientation of the polymerizable liquid crystal compound tends to be high. Note that the "solid content" referred to here refers to the components remaining after excluding volatile components such as solvents from the polarizer-forming composition. Similarly, when the term "solid content" is used hereinafter in this specification, it refers to the components remaining after excluding volatile components such as solvents from the target composition.

[0073] In the present invention, the polarizer-forming composition used to form the polarizer typically contains a dichroic dye. Here, the dichroic dye refers to a dye having different absorbance in the long axis direction of the molecule and absorbance in the short axis direction. The dichroic dye that can be used in the present invention is not particularly limited as long as it has the above-mentioned properties, and may be a dye or a pigment. Furthermore, two or more dyes or pigments may be used in combination, or a dye and a pigment may be used in combination. Furthermore, the dichroic dye may be polymerizable or liquid crystalline.

[0074] As a dichroic dye, the maximum absorption wavelength (λ MAX ) is preferred. Examples of such dichroic dyes include acridine dyes, oxazine dyes, cyanine dyes, naphthalene dyes, azo dyes, and anthraquinone dyes.

[0075] Examples of azo dyes include monoazo dyes, bisazo dyes, trisazo dyes, tetrakisazo dyes, and stilbene azo dyes, and bisazo dyes and trisazo dyes are preferred, such as a compound represented by formula (I) (hereinafter also referred to as "compound (I)"). K 1 (-N=NK 2 ) p -N=NK 3 (I) [In formula (I), K 1 and K. 3represent, independently of each other, an optionally substituted phenyl group, an optionally substituted naphthyl group, an optionally substituted benzoic acid phenyl ester group, or an optionally substituted monovalent heterocyclic group. 2 represents a p-phenylene group which may have a substituent, a naphthalene-1,4-diyl group which may have a substituent, a 4,4'-stilbenylene group which may have a substituent, or a divalent heterocyclic group which may have a substituent. p represents an integer of 0 to 4. When p is an integer of 2 or more, a plurality of K 2 may be the same or different. The -N=N- bond may be replaced with a -C=C-, -COO-, -NHCO-, or -N=CH- bond as long as the compound exhibits absorption in the visible region.

[0076] Examples of monovalent heterocyclic groups include groups in which one hydrogen atom has been removed from a heterocyclic compound such as quinoline, thiazole, benzothiazole, thienothiazole, imidazole, benzimidazole, oxazole, benzoxazole, etc. Examples of divalent heterocyclic groups include groups in which two hydrogen atoms have been removed from the above heterocyclic compounds.

[0077] K 1 and K. 3 Phenyl group, naphthyl group, benzoic acid phenyl ester group and monovalent heterocyclic group in 2In the formula (I), the p-phenylene group, the naphthalene-1,4-diyl group, the 4,4'-stilbenylene group, and the divalent heterocyclic group may optionally have a substituent, such as an alkyl group having 1 to 20 carbon atoms, an alkyl group having 1 to 20 carbon atoms and having a polymerizable group, or an alkenyl group having 1 to 4 carbon atoms; an alkoxy group having 1 to 20 carbon atoms, such as a methoxy group, an ethoxy group, or a butoxy group; an alkoxy group having 1 to 20 carbon atoms and having a polymerizable group; a fluorinated alkyl group having 1 to 4 carbon atoms, such as a trifluoromethyl group; Examples of the polymerizable group include an ano group, a nitro group, a halogen atom, and substituted or unsubstituted amino groups such as an amino group, a diethylamino group, and a pyrrolidino group (a substituted amino group refers to an amino group having one or two alkyl groups of 1 to 6 carbon atoms, an amino group having one or two alkyl groups of 1 to 6 carbon atoms and a polymerizable group, or an amino group in which two substituted alkyl groups are bonded to form an alkanediyl group of 2 to 8 carbon atoms. An unsubstituted amino group is -NH2). Examples of the polymerizable group include a (meth)acryloyl group and a (meth)acryloyloxy group.

[0078] Among the compounds (I), compounds represented by any one of the following formulae (I-1) to (I-8) are preferred. [ka] [In formulas (I-1) to (I-8), B 1 ~B 30 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group, a nitro group, a substituted or unsubstituted amino group (the definitions of a substituted amino group and an unsubstituted amino group are as defined above), a chlorine atom, or a trifluoromethyl group. n1 to n4 each independently represent an integer of 0 to 3. If n1 is 2 or more, multiple B 2 may be the same or different from each other, If n2 is 2 or more, multiple B 6 may be the same or different from each other, If n3 is 2 or more, multiple B 9may be the same or different from each other, If n4 is 2 or more, multiple B 14 may be the same or different from each other.

[0079] The anthraquinone dye is preferably a compound represented by formula (I-9). [ka] [In formula (I-9), R 1 ~R 8 are, independently of each other, a hydrogen atom, -R x , -NH2, -NHR x , -NR x 2, -SR x or a halogen atom. R x represents an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms.

[0080] The oxazone dye is preferably a compound represented by formula (I-10). [ka] [In formula (I-10), R 9 ~R 15 are, independently of each other, a hydrogen atom, -R x , -NH2, -NHR x , -NR x 2, -SR x or a halogen atom. R x represents an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms.

[0081] The acridine dye is preferably a compound represented by formula (I-11). [ka] [In formula (I-11), R 16 ~R 23are, independently of each other, a hydrogen atom, -R x , -NH2, -NHR x , -NR x 2, -SR x or a halogen atom. R x represents an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms. In formula (I-9), formula (I-10) and formula (I-11), R x Examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group, and examples of the aryl group having 6 to 12 carbon atoms include a phenyl group, a toluyl group, a xylyl group, and a naphthyl group.

[0082] As the cyanine dye, compounds represented by formula (I-12) and compounds represented by formula (I-13) are preferred. [ka] [In formula (I-12), D 1 and D 2 represent, independently of each other, a group represented by any one of formulae (I-12a) to (I-12d). [ka] n5 represents an integer from 1 to 3. [ka] [In formula (I-13), D 3 and D 4 represent, independently of each other, a group represented by any one of formulas (I-13a) to (I-13h). [ka] n6 represents an integer from 1 to 3.

[0083] Among these dichroic dyes, azo dyes are suitable for producing polarizers with excellent polarization performance due to their high linearity. Therefore, in one embodiment of the present invention, the dichroic dye contained in the polarizer-forming composition for forming the polarizer is preferably an azo dye.

[0084] In the present invention, the weight average molecular weight of the dichroic dye is usually 300 to 2,000, and preferably 400 to 1,000.

[0085] In one embodiment of the present invention, the dichroic dye contained in the polarizer-forming composition for forming the polarizer is preferably hydrophobic. When the dichroic dye is hydrophobic, the compatibility between the dichroic dye and the polymerizable liquid crystal compound is improved, and the dichroic dye and the polymerizable liquid crystal compound form a uniform phase state, thereby obtaining a polarizer with a high degree of orientational order. In the present invention, a hydrophobic dichroic dye refers to a dye whose solubility in 100 g of water at 25°C is 1 g or less.

[0086] The content of the dichroic dye in the polarizer-forming composition can be appropriately determined depending on the type of dichroic dye used, but is preferably 0.1 to 50 parts by mass, more preferably 0.1 to 20 parts by mass, and even more preferably 0.1 to 12 parts by mass, relative to 100 parts by mass of the polymerizable liquid crystal compound. When the content of the dichroic dye is within the above range, the orientation of the polymerizable liquid crystal compound is unlikely to be disturbed, and a polarizer having a high degree of orientational order can be obtained.

[0087] In the present invention, the polarizer-forming composition for forming a polarizer may contain a polymerization initiator. The polymerization initiator is a compound capable of initiating the polymerization reaction of a polymerizable liquid crystal compound, and a photopolymerization initiator is preferred because it can initiate the polymerization reaction under lower temperature conditions. Specific examples include photopolymerization initiators that can generate active radicals or acids under the action of light, and among these, photopolymerization initiators that generate radicals under the action of light are preferred. The polymerization initiators can be used alone or in combination of two or more.

[0088] As the photopolymerization initiator, known photopolymerization initiators can be used. For example, photopolymerization initiators that generate active radicals include self-cleavage type photopolymerization initiators and hydrogen abstraction type photopolymerization initiators. Examples of the self-cleaving photopolymerization initiator that can be used include self-cleaving benzoin compounds, acetophenone compounds, hydroxyacetophenone compounds, α-aminoacetophenone compounds, oxime ester compounds, acylphosphine oxide compounds, and azo compounds. Examples of the hydrogen abstraction photopolymerization initiator that can be used include hydrogen abstraction benzophenone compounds, benzoin ether compounds, benzil ketal compounds, dibenzosuberone compounds, anthraquinone compounds, xanthone compounds, thioxanthone compounds, halogenoacetophenone compounds, dialkoxyacetophenone compounds, halogenobisimidazole compounds, halogenotriazine compounds, and triazine compounds.

[0089] As the photopolymerization initiator that generates an acid, an iodonium salt, a sulfonium salt, or the like can be used.

[0090] Among these, a reaction at low temperature is preferred from the viewpoint of preventing dissolution of the dye, and a self-cleaving photopolymerization initiator is preferred from the viewpoint of reaction efficiency at low temperature, and an acetophenone-based compound, a hydroxyacetophenone-based compound, an α-aminoacetophenone-based compound, or an oxime ester-based compound is particularly preferred.

[0091] Specific examples of the photopolymerization initiator include the following: benzoin compounds such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether and benzoin isobutyl ether; hydroxyacetophenone compounds such as 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1,2-diphenyl-2,2-dimethoxyethan-1-one, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]propan-1-one, 1-hydroxycyclohexyl phenyl ketone, and oligomers of 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propan-1-one; α-aminoacetophenone compounds such as 2-methyl-2-morpholino-1-(4-methylthiophenyl)propan-1-one and 2-dimethylamino-2-benzyl-1-(4-morpholinophenyl)butan-1-one; Oxime ester compounds such as 1,2-octanedione, 1-[4-(phenylthio)-, 2-(O-benzoyloxime)], ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(O-acetyloxime); acylphosphine oxide compounds such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide; benzophenone compounds such as benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, 3,3',4,4'-tetra(tert-butylperoxycarbonyl)benzophenone, and 2,4,6-trimethylbenzophenone; Dialkoxyacetophenone compounds such as diethoxyacetophenone; 2,4-bis(trichloromethyl)-6-(4-methoxyphenyl)-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-(4-methoxynaphthyl)-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-(4-methoxystyryl)-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-[2-(5-methylfuran-2-yl)ethenyl]-1,3,5-triazine triazine-based compounds such as 2,4-bis(trichloromethyl)-6-[2-(furan-2-yl)ethenyl]-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-[2-(4-diethylamino-2-methylphenyl)ethenyl]-1,3,5-triazine, and 2,4-bis(trichloromethyl)-6-[2-(3,4-dimethoxyphenyl)ethenyl]-1,3,5-triazine. The photopolymerization initiator may be appropriately selected from the above-mentioned photopolymerization initiators, for example, in consideration of the relationship with the polymerizable liquid crystal compound contained in the polarizer-forming composition.

[0092] Alternatively, commercially available photopolymerization initiators may be used. Examples of commercially available polymerization initiators include Irgacure (registered trademark) 907, 184, 651, 819, 250, and 369, 379, 127, 754, OXE01, OXE02, and OXE03 (manufactured by BASF); Omnirad BCIM, Esacure 1001M, and Esacure KIP160 (manufactured by IDM Resins); BV); Seikuol (registered trademark) BZ, Z, and BEE (Seiko Chemical Co., Ltd.); Kayacure (registered trademark) BP100 and UVI-6992 (Dow Chemical Co., Ltd.); Adeka Optomer SP-152, N-1717, N-1919, SP-170, Adeka Arcles NCI-831, Adeka Arcles NCI-930 (ADEKA Corporation); TAZ-A and TAZ-PP (Nihon Siber Hegner Co., Ltd.); and TAZ-104 (Sanwa Chemical Co., Ltd.).

[0093] The content of the polymerization initiator in the polarizer-forming composition for forming a polarizer is preferably 1 to 10 parts by mass, more preferably 1 to 8 parts by mass, still more preferably 2 to 8 parts by mass, and particularly preferably 4 to 8 parts by mass, relative to 100 parts by mass of the polymerizable liquid crystal compound. When the content of the polymerization initiator is within the above range, the polymerization reaction of the polymerizable liquid crystal compound can be carried out without significantly disturbing the alignment of the polymerizable liquid crystal compound.

[0094] In the present invention, the polymerization rate of the polymerizable liquid crystal compound is preferably 60% or more, more preferably 65% ​​or more, and even more preferably 70% or more, from the viewpoints of line contamination during production and handling.

[0095] The polarizer-forming composition may further contain a photosensitizer. The use of a photosensitizer can further promote the polymerization reaction of the polymerizable liquid crystal compound. Examples of photosensitizers include xanthone compounds such as xanthone and thioxanthone (e.g., 2,4-diethylthioxanthone, 2-isopropylthioxanthone, etc.); anthracene compounds such as anthracene and alkoxy group-containing anthracene (e.g., dibutoxyanthracene, etc.); phenothiazine, rubrene, etc. The photosensitizers can be used alone or in combination of two or more.

[0096] When the polarizer-forming composition contains a photosensitizer, the content thereof may be determined appropriately depending on the type and amount of the polymerization initiator and polymerizable liquid crystal compound, but is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 10 parts by mass, and even more preferably 0.5 to 8 parts by mass, relative to 100 parts by mass of the polymerizable liquid crystal compound.

[0097] The polarizer-forming composition may also contain a leveling agent. The leveling agent adjusts the fluidity of the polarizer-forming composition and functions to make the coating film obtained by applying the polarizer-forming composition flatter. Specific examples of the leveling agent include surfactants. The leveling agent is preferably at least one selected from the group consisting of leveling agents containing a polyacrylate compound as a main component and leveling agents containing a fluorine atom-containing compound as a main component. The leveling agents can be used alone or in combination of two or more.

[0098] Examples of leveling agents containing polyacrylate compounds as their main components include "BYK-350", "BYK-352", "BYK-353", "BYK-354", "BYK-355", "BYK-358N", "BYK-361N", "BYK-380", "BYK-381" and "BYK-392" (BYK Chemie).

[0099] Examples of leveling agents containing a fluorine atom-containing compound as a main component include "Megafac (registered trademark) R-08", "R-30", "R-90", "F-410", "F-411", "F-443", "F-445", "F-470", "F-471", "F-477", "F-479", "F-482" and "F-483" (DIC Corporation); "Surflon (registered trademark) S-381" and "S-483" (DIC Corporation); Examples of such grease include "S-382", "S-383", "S-393", "SC-101", "SC-105", "KH-40" and "SA-100" (AGC Seimi Chemical Co., Ltd.); "E1830", "E5844" (Daikin Fine Chemicals Research Institute, Ltd.); "F-TOP EF301", "F-TOP EF303", "F-TOP EF351" and "F-TOP EF352" (Mitsubishi Materials Electronic Chemicals Co., Ltd.).

[0100] When the polarizer-forming composition contains a leveling agent, the content thereof is preferably 0.05 to 5 parts by mass, more preferably 0.05 to 3 parts by mass, relative to 100 parts by mass of the polymerizable liquid crystal compound. When the content of the leveling agent is within the above range, the polymerizable liquid crystal compound is easily aligned, unevenness is less likely to occur, and a smoother polarizer tends to be obtained.

[0101] The polarizer-forming composition may contain additives other than the photosensitizer and the leveling agent. Examples of the additives include antioxidants, release agents, stabilizers, colorants such as bluing agents, flame retardants, and lubricants. When the polarizer-forming composition contains other additives, the content of the additives is preferably more than 0% and not more than 20% by mass, more preferably more than 0% and not more than 10% by mass, based on the solid content of the polarizer-forming composition.

[0102] The polarizer-forming composition can be produced by a conventionally known method for preparing a polarizer-forming composition, and can usually be prepared by mixing and stirring a polymerizable liquid crystal compound and a dichroic dye, and, if necessary, a polymerization initiator and the above-mentioned additives, etc. Furthermore, since compounds exhibiting smectic liquid crystal properties generally have high viscosity, the viscosity may be adjusted by adding a solvent to the polarizer-forming composition from the viewpoint of improving the coatability of the polarizer-forming composition and facilitating the formation of a polarizer.

[0103] The solvent used in the polarizer-forming composition can be appropriately selected depending on the solubility of the polymerizable liquid crystal compound and dichroic dye used. Specific examples include alcohol solvents such as water, methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, methyl cellosolve, butyl cellosolve, and propylene glycol monomethyl ether; ester solvents such as ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone, propylene glycol methyl ether acetate, and ethyl lactate; ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, methyl amyl ketone, and methyl isobutyl ketone; aliphatic hydrocarbon solvents such as pentane, hexane, and heptane; aromatic hydrocarbon solvents such as toluene and xylene; nitrile solvents such as acetonitrile; ether solvents such as tetrahydrofuran and dimethoxyethane; and chlorinated hydrocarbon solvents such as chloroform and chlorobenzene. These solvents can be used alone or in combination. The content of the solvent is preferably 100 to 1900 parts by mass, more preferably 150 to 900 parts by mass, and even more preferably 180 to 600 parts by mass, relative to 100 parts by mass of the solid content of the polarizer-forming composition.

[0104] In the present invention, the polarizer preferably has a high degree of orientational order. A polarizer with a high degree of orientational order exhibits a Bragg peak derived from a higher-order structure, such as a hexatic phase or a crystalline phase, in X-ray diffraction measurement. A Bragg peak refers to a peak derived from the planar periodic structure of molecular orientation. Therefore, the polarizer constituting the pressure-sensitive adhesive layer-attached circular polarizer of the present invention preferably exhibits a Bragg peak in X-ray diffraction measurement. That is, in the polarizer constituting the pressure-sensitive adhesive layer-attached circular polarizer of the present invention, the polymerizable liquid crystal compound or its polymer is preferably oriented so that the polarizer exhibits a Bragg peak in X-ray diffraction measurement, and more preferably exhibits "horizontal orientation" in which the molecules of the polymerizable liquid crystal compound are oriented in the direction of light absorption. In the present invention, a polarizer having a planar periodic spacing of 3.0 to 6.0 Å in molecular orientation is preferred. A high degree of orientational order that exhibits a Bragg peak can be achieved by controlling the type of polymerizable liquid crystal compound used, the type and amount of dichroic dye, and the type and amount of polymerization initiator.

[0105] In the present invention, the polarizer can be obtained, for example, by a method including forming a coating film of a polarizer-forming composition on a substrate or an alignment film described later, removing the solvent from the coating film, raising the temperature to a temperature at which the polymerizable liquid crystal compound undergoes a phase transition to a liquid phase or higher and then lowering the temperature to cause the polymerizable liquid crystal compound to undergo a phase transition to a liquid crystal phase (smectic phase), and polymerizing the polymerizable liquid crystal compound while maintaining the liquid crystal phase.

[0106] Examples of a method for applying the polarizer-forming composition to a substrate or an alignment film include known methods such as coating methods, such as spin coating, extrusion, gravure coating, die coating, bar coating, and applicator methods, and printing methods, such as flexography.

[0107] Next, the solvent is removed by drying or the like under conditions that do not polymerize the polymerizable liquid crystal compound contained in the coating film obtained from the polarizer-forming composition, thereby forming a dried coating film. Examples of the drying method include natural drying, ventilation drying, heat drying, and reduced-pressure drying.

[0108] Furthermore, in order to cause the polymerizable liquid crystal compound to undergo a phase transition to a liquid phase, the temperature is raised to a temperature at which the polymerizable liquid crystal compound undergoes a phase transition to a liquid phase or higher, and then the temperature is lowered to cause the polymerizable liquid crystal compound to undergo a phase transition to a liquid crystal phase (smectic phase). Such a phase transition may be carried out after or simultaneously with the removal of the solvent from the coating film.

[0109] A polarizer is formed as a cured product of the polarizer-forming composition by polymerizing the polymerizable liquid crystal compound while maintaining its liquid crystal state. Photopolymerization is a preferred polymerization method. In photopolymerization, the light irradiated onto the dried coating film is appropriately selected depending on the type of polymerizable liquid crystal compound contained in the dried coating film (particularly the type of polymerizable group possessed by the polymerizable liquid crystal compound), the type and amount of polymerization initiator, and other factors. Specific examples include one or more types of light selected from the group consisting of visible light, ultraviolet light, infrared light, X-rays, α-rays, β-rays, and γ-rays, and actinic electron beams. Among these, ultraviolet light is preferred because it is easy to control the progress of the polymerization reaction and allows the use of photopolymerization equipment widely used in the field. It is also preferable to select the types of polymerizable liquid crystal compound and polymerization initiator contained in the polarizer-forming composition so that they can be photopolymerized by ultraviolet light. Furthermore, the polymerization temperature can be controlled by irradiating the dried coating film with light while cooling it with an appropriate cooling means. During photopolymerization, a patterned polarizer can be obtained by performing masking and development.

[0110] Examples of the light source of the active energy rays include a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a xenon lamp, a halogen lamp, a carbon arc lamp, a tungsten lamp, a gallium lamp, an excimer laser, an LED light source emitting light in a wavelength range of 380 to 440 nm, a chemical lamp, a black light lamp, a microwave-excited mercury lamp, and a metal halide lamp.

[0111] The UV irradiation intensity is usually 10 to 3,000 mW / cm 2The ultraviolet irradiation intensity is preferably an intensity in a wavelength region effective for activating a photopolymerization initiator. The light irradiation time is usually 0.1 seconds to 10 minutes, preferably 1 second to 5 minutes, more preferably 5 seconds to 3 minutes, and even more preferably 10 seconds to 1 minute. When irradiating once or multiple times with such ultraviolet irradiation intensity, the cumulative light amount is 10 to 3,000 mJ / cm. 2 , preferably 50 to 2,000 mJ / cm 2 , more preferably 100 to 1,000 mJ / cm 2 is.

[0112] By photopolymerization, the polymerizable liquid crystal compound is polymerized while maintaining a liquid crystal phase, particularly a smectic phase, and preferably a high-order smectic phase, to form a polarizer. The polarizer obtained by polymerizing the polymerizable liquid crystal compound while maintaining a smectic phase has the advantage of higher polarization performance, due in part to the action of the dichroic dye, compared to conventional host-guest polarizing films, i.e., polarizers formed in a nematic liquid crystal phase. Furthermore, the polarizer has the advantage of being superior in strength compared to films coated with only a dichroic dye or lyotropic liquid crystal.

[0113] The thickness of the polarizer can be appropriately selected depending on the display device to which it is applied, but in the present invention, which aims to prevent defects (such as the generation of bubbles or wrinkles) during transfer of a very thin circular polarizer, it is preferable that the polarizer be as thin as possible. For example, it is preferably 0.1 to 5 μm, more preferably 0.3 to 4 μm, and even more preferably 0.5 to 3 μm. If the film thickness of the polarizer is equal to or greater than the above lower limit, it is easy to prevent the necessary light absorption from being lost, and if it is equal to or less than the above upper limit, it is easy to prevent the occurrence of alignment defects due to a decrease in the alignment regularity of the alignment film.

[0114] The polarizer may be formed on an alignment film. The alignment film has an alignment regulating force that aligns the polymerizable liquid crystal compound in a desired direction, and a precisely aligned polarizer can be easily obtained by applying a polarizer-forming composition onto the alignment film. The alignment film preferably has solvent resistance that prevents the polarizer-forming composition from dissolving when applied, and also has heat resistance during heat treatment for removing the solvent or orienting the polymerizable liquid crystal compound. In the present invention, the alignment film is preferably a photo-alignment film from the viewpoints of the precision and quality of the alignment angle, as well as the water resistance and bending resistance of a circular polarizer including the alignment film. The photo-alignment film is also advantageous in that the direction of the alignment regulating force can be freely controlled by selecting the polarization direction of the polarized light to be irradiated.

[0115] A photo-alignment film is typically obtained by applying a composition (hereinafter also referred to as a "photo-alignment film-forming composition") containing a polymer, oligomer, or monomer (hereinafter also referred to as a "polymer, etc. having a photo-reactive group") and a solvent to a substrate or, if necessary, to a diffusion prevention layer provided on the substrate, and irradiating it with polarized light (preferably polarized UV). Examples of substrates on which a photo-alignment film is formed include those similar to the substrate film of the pressure-sensitive adhesive layer-attached circular polarizer of the present invention. When the polymer, etc. contained in the photo-alignment film-forming composition has the same reactive group (e.g., a (meth)acryloyl group) as the functional group of the polymerizable group of the polymerizable liquid crystal compound that forms the polarizer, adhesion to the polarizer tends to be improved.

[0116] The photoreactive group refers to a group that exhibits liquid crystal alignment ability upon irradiation with light. Specific examples include groups involved in photoreactions that induce molecular alignment upon irradiation with light or that are the origin of liquid crystal alignment ability, such as isomerization, dimerization, photocrosslinking, or photodecomposition. Among these, groups involved in dimerization or photocrosslinking are preferred because of their excellent alignment properties. As the photoreactive group, groups having an unsaturated bond, particularly a double bond, are preferred, and groups having at least one bond selected from the group consisting of a carbon-carbon double bond (C=C bond), a carbon-nitrogen double bond (C=N bond), a nitrogen-nitrogen double bond (N=N bond), and a carbon-oxygen double bond (C=O bond) are particularly preferred.

[0117] Examples of photoreactive groups having a C=C bond include vinyl groups, polyene groups, stilbene groups, stilbazole groups, stilbazolium groups, chalcone groups, and cinnamoyl groups. Examples of photoreactive groups having a C=N bond include groups having structures such as aromatic Schiff bases and aromatic hydrazones. Examples of photoreactive groups having an N=N bond include azobenzene groups, azonaphthalene groups, aromatic heterocyclic azo groups, bisazo groups, formazan groups, and groups having an azoxybenzene structure. Examples of photoreactive groups having a C=O bond include benzophenone groups, coumarin groups, anthraquinone groups, and maleimide groups. These groups may have substituents such as alkyl groups, alkoxy groups, aryl groups, allyloxy groups, cyano groups, alkoxycarbonyl groups, hydroxyl groups, sulfonic acid groups, and halogenated alkyl groups.

[0118] Among these, photoreactive groups involved in photodimerization reactions are preferred, and cinnamoyl and chalcone groups are preferred because they require a relatively small amount of polarized light irradiation for photoalignment and are likely to produce a photoalignment film with excellent thermal stability and stability over time. As the polymer having a photoreactive group, those having a cinnamoyl group such that the terminal of the polymer side chain has a cinnamic acid structure are particularly preferred.

[0119] The photoalignment-inducing layer can be formed by applying the composition for forming a photoalignment film, for example, to a substrate or a diffusion prevention layer provided on the substrate (described later). Examples of the solvent contained in the composition include the same solvents as those exemplified above as solvents that can be used in forming a polarizer, and the solvent can be appropriately selected depending on the solubility of the polymer having a photoreactive group, etc.

[0120] The content of the polymer having a photoreactive group in the composition for forming a photo-alignment film can be adjusted appropriately depending on the type of polymer and the desired thickness of the photo-alignment film, but is preferably at least 0.2% by mass, more preferably in the range of 0.3 to 10% by mass, relative to the mass of the composition for forming a photo-alignment film. The composition for forming a photo-alignment film may contain a polymer material such as polyvinyl alcohol or polyimide, or a photosensitizer, as long as the properties of the photo-alignment film are not significantly impaired.

[0121] Methods for applying the composition for forming a photo-alignment film onto a substrate or onto a diffusion prevention layer described later, and methods for removing the solvent from the applied composition for forming a photo-alignment film, include methods similar to those for applying the composition for forming a polarizer onto a substrate or the like and removing the solvent.

[0122] The polarized light irradiation may be performed by directly irradiating the coating film of the photo-alignment film-forming composition with polarized UV light after removing the solvent, or by irradiating the substrate with polarized light and then transmitting the polarized light. It is particularly preferable that the polarized light be substantially parallel. The wavelength of the polarized light to be irradiated should be in a wavelength range in which the photoreactive group in the polymer having a photoreactive group can absorb the light energy. Specifically, UV (ultraviolet light) with a wavelength of 250 to 400 nm is particularly preferable. Examples of light sources used for the polarized light irradiation include xenon lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, and ultraviolet lasers such as KrF and ArF. High-pressure mercury lamps, ultra-high-pressure mercury lamps, and metal halide lamps are more preferable. Among these, high-pressure mercury lamps, ultra-high-pressure mercury lamps, and metal halide lamps are preferred due to their high emission intensity of ultraviolet light with a wavelength of 313 nm. Polarized UV light can be irradiated by passing light from the light source through an appropriate polarizer. As such a polarizer, a polarizing filter, a polarizing prism such as a Glan-Thompson or Glan-Taylor, or a wire grid type polarizer can be used.

[0123] If masking is performed during polarized light irradiation, a plurality of regions (patterns) with different liquid crystal alignment directions can be formed.

[0124] The number-average molecular weight of the photo-alignment film is preferably 20,000 to 100,000, more preferably 25,000 or more, and more preferably 90,000 or less, and even more preferably 80,000 or less. When the number-average molecular weight of the photo-alignment film is within the above range, adhesion between the photo-alignment film and adjacent layers is likely to be improved. The number-average molecular weight of the photo-alignment film can be controlled by the amount of monomers used in the composition for forming a photo-alignment film, the type and amount of polymerization initiator, etc. The "number average molecular weight of the photo-alignment film" referred to here essentially corresponds to the number average molecular weight of the polymer constituting the cured photo-alignment film, and is a molecular weight calculated by measuring the cured photo-alignment film itself using a measuring instrument such as gel permeation chromatography.

[0125] The thickness of the photo-alignment film is preferably 10 to 5000 nm, more preferably 10 to 1000 nm, and even more preferably 30 to 300 nm. When the thickness of the photo-alignment film is within the above range, the film can exhibit good adhesion at the interface with the polarizer and can exert alignment regularity, allowing the formation of a polarizer with high alignment order.

[0126] [Diffusion prevention layer] In the present invention, the polarizing plate preferably includes a polarizer and a diffusion prevention layer located on the first pressure-sensitive adhesive layer side of the polarizer. Furthermore, a diffusion prevention layer may be further included between the polarizer and the adhesive layer. The presence of a diffusion prevention layer between the first pressure-sensitive adhesive layer and the polarizer or between the polarizer and the adhesive layer can effectively suppress diffusion of the dichroic dye in the polarizer into other layers. When the pressure-sensitive adhesive layer-attached circular polarizing plate of the present invention is incorporated into a display device or the like, deterioration of the optical properties over time due to diffusion of the dichroic dye can be suppressed. To fully achieve this effect, the diffusion prevention layer is preferably provided adjacent to the polarizer on the first pressure-sensitive adhesive layer side of the polarizer. It is more preferable that the diffusion prevention layer is provided adjacent to the polarizer on both the first pressure-sensitive adhesive layer side and the retardation layer side of the polarizer, respectively, or via only the alignment film that forms the polarizer. When the diffusion prevention layer is provided on both the first pressure-sensitive adhesive layer side and the retardation layer side of the polarizer, the layers may be the same or different.

[0127] The diffusion prevention layer is not particularly limited as long as it has a function of preventing the diffusion of the dichroic dye, but in the present invention, which aims to suppress defects (such as the generation of bubbles and wrinkles) during transfer of a very thin circular polarizing plate, it is preferable that the diffusion prevention layer is as thin as possible. The diffusion prevention layer that can achieve such a thin thickness is preferably a coating layer, and examples thereof include a layer formed from a resin composition containing a water-soluble polymer and a layer formed from a curable composition containing an active energy ray-curable resin.

[0128] The water-soluble polymer has a polarity significantly different from that of the dichroic dye, and therefore can prevent the diffusion of the dichroic dye. Examples of water-soluble polymers that can form the diffusion prevention layer include polyacrylamide polymers; polyvinyl alcohol, and vinyl alcohol polymers such as ethylene-vinyl alcohol copolymers and (meth)acrylic acid or its anhydride-vinyl alcohol copolymers; carboxyvinyl polymers; polyvinylpyrrolidone; starches; sodium alginate; and polyethylene oxide polymers. These polymers may be used alone or in combination of two or more.

[0129] When the diffusion prevention layer is a layer formed from a resin composition containing a water-soluble polymer (hereinafter also referred to as a "water-soluble polymer-containing resin composition"), the content of the water-soluble polymer in the layer is preferably 75% by mass or more, more preferably 80% by mass or more, and even more preferably 85% by mass or more.

[0130] When the diffusion-preventing layer is a layer formed from a water-soluble polymer-containing resin composition, a crosslinking structure may be introduced by using a crosslinking agent to increase the density of the layer and improve the dichroic dye diffusion-preventing function. Examples of such crosslinking agents include water-soluble additives and crosslinking agents such as ionic crosslinking agents such as glyoxylate salts and epoxy crosslinking agents such as polyamide epoxy resins. For the purpose of imparting water resistance, hydrophobic crosslinking agents may also be used, such as isocyanate crosslinking agents, polyaldehyde crosslinking agents such as glyoxal and glyoxal derivatives, and metal compound crosslinking agents such as zirconium chloride or titanium lactate crosslinking agents.

[0131] When a crosslinking agent is used to introduce a crosslinked structure into the diffusion prevention layer, the amount of the crosslinking agent added may be determined appropriately depending on the type of crosslinking agent used, etc. For example, the amount may be 0.1 to 100 parts by mass, preferably 1 to 70 parts by mass, and more preferably 10 to 50 parts by mass, per 100 parts by mass of the water-soluble polymer. When the content of the crosslinking agent is within the above range, the diffusion prevention layer becomes dense, and the shielding effect against the dichroic dye in the light-absorption anisotropic film is likely to be improved.

[0132] The water-soluble polymer-containing resin composition capable of forming the diffusion barrier layer is usually prepared as a solution in which the water-soluble polymer is dissolved in a solvent. The solvent may be selected depending on the water-soluble polymer to be used, but typical examples include water, alcohol, and a mixture of water and alcohol, with water being preferred.

[0133] The solids concentration of the water-soluble polymer-containing resin composition obtained by adding a solvent to the components constituting the diffusion prevention layer, such as the water-soluble polymer and crosslinking agent, is preferably 1 to 50 mass %, more preferably 2 to 30 mass %. When the solids concentration of the water-soluble polymer-containing resin composition is within the above range, the viscosity of the composition is low, resulting in good coatability and handleability.

[0134] The water-soluble polymer-containing resin composition may contain other components such as additives in addition to the water-soluble polymer, crosslinker, and solvent such as water. Examples of such other components include preservatives and leveling agents. When the water-soluble polymer-containing resin composition contains other components such as additives, the amount of such components is preferably 10% by mass or less, more preferably 5% by mass or less, based on the solid content of the resin composition.

[0135] For example, the diffusion prevention layer can be obtained by applying a water-soluble polymer-containing resin composition to the surface on which the diffusion prevention layer is to be formed, and then drying and curing the coating.

[0136] The method for applying the water-soluble polymer-containing resin composition is not particularly limited, and examples thereof include known methods similar to the method for applying a polarizer-forming composition to a substrate or the like.

[0137] The drying temperature and time for forming a diffusion-preventing layer from a coating film of the water-soluble polymer-containing resin composition are not particularly limited and may be appropriately determined depending on the composition of the water-soluble polymer-containing resin composition used. The drying treatment can be carried out, for example, by blowing hot air, and the temperature is usually within a range of 40 to 100° C., preferably 60 to 100° C. The drying time is usually 10 to 600 seconds.

[0138] Active energy ray-curable resins tend to have excellent dichroic dye diffusion prevention properties due to their high polymerizability. Examples of curable compositions containing active energy ray-curable resins capable of forming a diffusion barrier layer (hereinafter also referred to as "diffusion barrier layer-forming curable compositions") include cationically polymerizable curable compositions containing cationically polymerizable compounds as curable compounds, radically polymerizable curable compositions containing radically polymerizable compounds as curable compounds, and hybrid curable compositions containing both cationically polymerizable and radically polymerizable compounds. Specific examples of cationically polymerizable compounds include epoxy compounds having one or more epoxy groups in the molecule, oxetane compounds having one or more oxetane rings in the molecule, and vinyl compounds. Specific examples of radically polymerizable compounds include (meth)acrylic compounds having one or more (meth)acryloyl groups in the molecule, vinyl compounds, and the like. The diffusion barrier layer-forming curable composition may contain one or more cationically polymerizable compounds and / or one or more radically polymerizable compounds.

[0139] The cationically polymerizable compound, which is the main component of the cationically polymerizable curable composition, refers to a compound or oligomer that undergoes a cationic polymerization reaction and hardens when exposed to active energy rays such as ultraviolet light, visible light, electron beams, or X-rays or when heated, and examples of such compounds include epoxy compounds, oxetane compounds, and vinyl compounds. Of these, the preferred cationically polymerizable compound is an epoxy compound.

[0140] An epoxy compound is a compound having one or more, preferably two or more, epoxy groups in the molecule. One type of epoxy compound may be used alone, or two or more types may be used in combination. Examples of epoxy compounds include alicyclic epoxy compounds, aromatic epoxy compounds, hydrogenated epoxy compounds, and aliphatic epoxy compounds. From the viewpoints of weather resistance, curing speed, and adhesiveness, it is preferable that the epoxy compound contains an alicyclic epoxy compound or an aliphatic epoxy compound.

[0141] In the present invention, when the curable composition for forming a diffusion prevention layer contains an epoxy compound as a cationically polymerizable compound, the content of the epoxy compound is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and even more preferably 20 parts by mass or more, and is preferably 70 parts by mass or less, more preferably 60 parts by mass or less, and even more preferably 50 parts by mass or less, relative to 100 parts by mass of the solid content of the curable composition.

[0142] When the total amount of curable compounds contained in the curable composition for forming a diffusion barrier layer (including hybrid types) containing a cationically polymerizable compound is taken as 100 mass %, the content of the cationically polymerizable compound (when two or more types of cationically polymerizable compounds are contained, the total content of these compounds) is preferably 50 mass % or more, more preferably 60 mass % or more, and even more preferably 70 mass % or more. In addition, the cationically polymerizable curable composition may further contain a polymer component (such as a thermoplastic resin).

[0143] When the curable composition for forming a diffusion barrier layer contains a cationic polymerizable compound, it preferably contains a cationic photopolymerization initiator. The cationic photopolymerization initiator generates cationic species or Lewis acids upon irradiation with active energy rays such as visible light, ultraviolet light, X-rays, or electron beams, thereby initiating the polymerization reaction of the cationic curable compound. Because the cationic photopolymerization initiator acts catalytically under light, it exhibits excellent storage stability and workability even when mixed with the cationic photocurable compound. Examples of compounds that generate cationic species or Lewis acids upon irradiation with active energy rays include onium salts such as aromatic iodonium salts and aromatic sulfonium salts, aromatic diazonium salts, and iron-arene complexes.

[0144] The cationic photopolymerization initiator may be used alone or in combination of two or more. Among them, aromatic sulfonium salts are preferably used because they have ultraviolet absorption properties even in the wavelength region around 300 nm, and therefore can provide a cured product with excellent curability, good mechanical strength, and adhesive strength.

[0145] The content of the cationic photopolymerization initiator in the curable composition for forming a diffusion prevention layer is preferably 1 to 10 parts by mass, more preferably 2 to 8 parts by mass, per 100 parts by mass of the solid content of the curable compound. When the content of the cationic photopolymerization initiator is within the above range, the cationic polymerizable compound can be sufficiently cured, and the resulting diffusion prevention layer can be imparted with high mechanical strength and adhesive strength.

[0146] A hybrid curable composition can also be obtained by incorporating a radically polymerizable compound in addition to a cationic polymerizable compound into a cationic polymerization curable composition. The combined use of a radically polymerizable compound is expected to have the effect of increasing the hardness and mechanical strength of the diffusion prevention layer, and further makes it easier to adjust the viscosity, curing speed, etc. of the curable composition.

[0147] The radical polymerizable compound, which is the main component of the radical polymerization type curable composition, refers to a compound or oligomer that undergoes a radical polymerization reaction and hardens when exposed to active energy rays such as ultraviolet light, visible light, electron beams, or X-rays or when heated, and specifically includes a compound having an ethylenically unsaturated bond. Examples of the compound having an ethylenically unsaturated bond include (meth)acrylic compounds having one or more (meth)acryloyl groups in the molecule, as well as vinyl compounds such as styrene, styrene sulfonic acid, vinyl acetate, vinyl propionate, and N-vinyl-2-pyrrolidone. Among these, the preferred radical polymerizable compound is a (meth)acrylic compound.

[0148] The (meth)acrylic compound is a compound having at least one (meth)acryloyloxy group in the molecule, and may be a monomer, oligomer, or polymer. Examples of the (meth)acrylic compound include (meth)acrylate compounds such as monofunctional (meth)acrylate compounds and polyfunctional (meth)acrylate compounds; urethane (meth)acrylate compounds such as polyfunctional urethane (meth)acrylate compounds; epoxy (meth)acrylate compounds such as polyfunctional epoxy (meth)acrylate compounds; carboxyl group-modified epoxy (meth)acrylate compounds, polyester (meth)acrylate compounds, etc. The (meth)acrylic compounds may be used alone or in combination of two or more.

[0149] Examples of the (meth)acrylate compound include a monofunctional (meth)acrylate compound having one (meth)acryloyloxy group in the molecule, and a polyfunctional (meth)acrylate compound having two or more (meth)acryloyloxy groups in the molecule.

[0150] When a polyfunctional (meth)acrylate compound is used, the crosslink density of the diffusion prevention layer can be adjusted by controlling the molecular weight between crosslinks and the number of crosslinks of the compound. More specifically, the smaller the molecular weight between crosslinks, the higher the crosslink density. Also, the larger the number of crosslinks, the denser the crosslink density, and the more effectively the light-absorbing anisotropic film can be shielded from the dichroic dye.

[0151] The urethane (meth)acrylate compound generally refers to a reaction product of an isocyanate compound, a polyol compound, and a (meth)acrylate compound, and is preferably a polyfunctional urethane (meth)acrylate compound having two or more (meth)acryloyloxy groups in the molecule. Because polyfunctional urethane (meth)acrylate compounds can form a crosslinked structure, they are advantageous in terms of improving the dichroic dye diffusion prevention function of the diffusion prevention layer, and can also impart appropriate toughness. The number of functional groups in the polyfunctional urethane (meth)acrylate compound is preferably 2 to 5.

[0152] Examples of epoxy (meth)acrylate compounds include polyfunctional epoxy (meth)acrylates that can be obtained by an addition reaction between polyglycidyl ether and (meth)acrylic acid and have at least two (meth)acryloyloxy groups in the molecule. Examples of polyester (meth)acrylate compounds include compounds that have an ester bond and at least two (meth)acryloyl groups (typically (meth)acryloyloxy groups) in the molecule.

[0153] In the present invention, when the curable composition for forming a diffusion prevention layer contains a radical polymerizable compound, it is preferable that the radical polymerizable compound contains a polyfunctional (meth)acrylate compound. In this case, the content of the polyfunctional (meth)acrylate compound is preferably 50 parts by mass or more, more preferably 60 parts by mass or more, and even more preferably 70 parts by mass or more, and is preferably 100 parts by mass or less, more preferably 95 parts by mass or less, and even more preferably 90 parts by mass or less, relative to 100 parts by mass of the solid content of the curable composition.

[0154] In the present invention, when the curable composition for forming a diffusion barrier layer contains a radically polymerizable compound, the radically polymerizable compound preferably contains a polyfunctional (meth)acrylate compound and a polyfunctional urethane (meth)acrylate compound. In this case, the polyfunctional (meth)acrylate compound and the urethane (meth)acrylate compound are preferably contained in a ratio (mass ratio of polyfunctional (meth)acrylate compound:urethane (meth)acrylate compound) of 95:5 to 50:50, more preferably 90:10 to 70:30.

[0155] When the curable composition for forming the diffusion prevention layer contains a radical polymerizable compound, it preferably contains a photoradical polymerization initiator. The photoradical polymerization initiator initiates the polymerization reaction of the radical curable compound by irradiation with active energy rays such as visible light, ultraviolet light, X-rays, or electron beams. The photoradical polymerization initiator may be used alone or in combination of two or more.

[0156] Specific examples of the photoradical polymerization initiator include acetophenone-based initiators such as acetophenone, 3-methylacetophenone, benzyl dimethyl ketal, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, and 2-hydroxy-2-methyl-1-phenylpropan-1-one; benzophenone-based initiators such as benzophenone, 4-chlorobenzophenone, and 4,4'-diaminobenzophenone; and 2,2-dimethylbenzophenone. Alkylphenone initiators such as 1,2-diphenylethan-1-one and 1-hydroxycyclohexylphenyl ketone; benzoin ether initiators such as benzoin propyl ether and benzoin ethyl ether; thioxanthone initiators such as 4-isopropylthioxanthone; acylphosphine oxide initiators such as bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide; and others such as xanthone, fluorenone, camphorquinone, benzaldehyde, and anthraquinone.

[0157] The content of the photoradical polymerization initiator in the curable composition for forming a diffusion prevention layer is preferably 1 to 10 parts by mass, more preferably 2 to 8 parts by mass, per 100 parts by mass of the solid content of the curable compound. When the content of the photoradical polymerization initiator is within the above range, the polymerization initiation ability is sufficiently exhibited, and the curability is improved, while the photoradical polymerization initiator is less likely to remain, making it easier to suppress a decrease in visible light transmittance, etc.

[0158] In the present invention, the curable composition for forming a diffusion-preventing layer may contain an organic solvent, for example, to adjust the viscosity to a level suitable for the coating method to be adopted, or may be substantially solvent-free (solvent-free). Note that "substantially solvent-free" does not exclude cases where a solvent is inevitably mixed in.

[0159] The solvent may be any solvent capable of dissolving the components constituting the diffusion prevention layer, and examples thereof include the same solvents as those usable in the polarizer-forming composition. These solvents may be used alone or in combination of two or more.

[0160] The type and content of the solvent are appropriately selected depending on the type and content of the components constituting the diffusion prevention layer, the shape, the application method, the thickness of the diffusion prevention layer, etc. When a solvent is contained, the amount thereof is, for example, preferably 3 to 1000 parts by mass, more preferably 5 to 100 parts by mass, and even more preferably 7 to 50 parts by mass per 100 parts by mass of the solid content of the curable composition.

[0161] The curable composition for forming a diffusion prevention layer may contain additives such as a cationic polymerization accelerator, a photosensitizer, an ion trapping agent, an antioxidant, a chain transfer agent, a tackifier, a thermoplastic resin, a filler, a flow adjuster, a plasticizer, an antifoaming agent, an antistatic agent, and a leveling agent, as needed.

[0162] For example, a diffusion-preventing layer can be obtained by applying a curable composition for forming a diffusion-preventing layer to the surface on which the diffusion-preventing layer is to be formed, and then irradiating the coating with active energy rays to cure the composition. The method of applying the curable composition for forming a diffusion-preventing layer, the type of active energy rays used for curing, the light source, the irradiation conditions, and the like can be similar to those used in the method of applying and curing the composition for forming a polarizer.

[0163] The thickness of the diffusion prevention layer is preferably 0.1 μm or more and 5 μm or less, more preferably 0.3 μm or more and 4 μm or less, and even more preferably 0.5 μm or more and 3 μm or less. Within the above range, an ultrathin polarizing plate can be provided while effectively suppressing the diffusion of the dichroic dye in the polarizer into other layers. When the diffusion prevention layer is included on both the first adhesive layer side and the retardation layer side of the polarizer, the thicknesses may be the same or different, but it is preferable that the thickness of both diffusion prevention layers be within the above range.

[0164] [Retardation layer] The retardation layer included in the pressure-sensitive adhesive layer-attached circular polarizer of the present invention is a layer that exhibits retardation. From the viewpoint of thinning the circular polarizer, the retardation layer is preferably a coating layer, and more preferably comprises a cured layer of a polymerizable liquid crystal composition containing at least one polymerizable liquid crystal compound. The pressure-sensitive adhesive layer-attached circular polarizer of the present invention is excellent in suppressing the occurrence of bubbles, wrinkles, etc. when the two outer layer surfaces revealed by peeling off the laminate a and the second substrate film are transferred and incorporated into a display device, and therefore high circular polarization function can be expected even after being incorporated into a display device or the like by double-sided transfer. The pressure-sensitive adhesive layer-attached circular polarizer of the present invention may include one retardation layer or two or more retardation layers.

[0165] The pressure-sensitive adhesive layer-attached circularly polarizing plate of the present invention preferably includes a retardation layer that satisfies the following formula (6). 120nm≦Re(550)≦170nm (6) (wherein Re(λ) represents the in-plane retardation value of the retardation layer at a wavelength of λ nm.) When the in-plane retardation Re(550) of the retardation layer is within the range of formula (6), the retardation layer functions as a quarter-wave plate, and the effect of improving the front reflection hue (the effect of suppressing coloration) is easily enhanced when a circular polarizer including the retardation layer is applied to an organic EL display device, etc. A more preferable range of the in-plane retardation value is 130 nm≦Re(550)≦150 nm.

[0166] Furthermore, it is preferable that the retardation layer satisfying the above formula (6) also satisfies the following formulas (7) and (8). Re(450) / Re(550)≦1.00 (7) 1.00≦Re(650) / Re(550) (8) (wherein Re(λ) represents the in-plane retardation value of the retardation layer at a wavelength of λ nm.) When the retardation layer satisfies the formulas (7) and (8), the retardation layer exhibits so-called reverse wavelength dispersion, in which the in-plane retardation value at short wavelengths is smaller than the in-plane retardation value at long wavelengths. A circularly polarizing plate having such a retardation layer tends to have excellent front hue when incorporated into an organic EL display device or the like. To improve the reverse wavelength dispersion and further enhance the effect of improving the reflected hue in the front direction, Re(450) / Re(550) is preferably 0.70 or more, more preferably 0.78 or more, and is preferably 0.92 or less, more preferably 0.90 or less, even more preferably 0.87 or less, particularly preferably 0.86 or less, and even more particularly preferably 0.85 or less. Furthermore, Re(650) / Re(550) is preferably 1.01 or more, more preferably 1.02 or more.

[0167] The in-plane retardation value can be adjusted by adjusting the film thickness d of the retardation layer. The in-plane retardation value is determined by the above formula Re(λ)=(nx(λ)-ny(λ))×d. Therefore, to obtain a desired in-plane retardation value (Re(λ): in-plane retardation value of the retardation layer at wavelength λ (nm)), it is sufficient to adjust the three-dimensional refractive index and film thickness d. In the formula, d represents the thickness of the target retardation layer, nx represents the principal refractive index at a wavelength λ nm in a direction parallel to the plane of the retardation layer in the index ellipsoid formed by the retardation layer, and ny represents the refractive index at a wavelength λ nm in a direction parallel to the plane of the retardation layer and perpendicular to the direction of nx in the index ellipsoid formed by the retardation layer.

[0168] The pressure-sensitive adhesive layer-attached circular polarizer of the present invention preferably comprises a retardation layer made of a "horizontally aligned liquid crystal cured layer" in which a polymerizable liquid crystal compound is cured while being aligned horizontally relative to the surface of the substrate, and more preferably comprises a horizontally aligned liquid crystal cured layer that satisfies the above formulas (6) to (8). When the pressure-sensitive adhesive layer-attached circular polarizer of the present invention comprises one retardation layer, the retardation layer that constitutes the retardation layer is usually a "horizontally aligned liquid crystal cured layer".

[0169] The pressure-sensitive adhesive layer-attached circular polarizer of the present invention may further include a retardation layer that is a cured liquid crystal layer (retardation layer) that is a positive C plate, in addition to the retardation layer that is a horizontally aligned cured liquid crystal layer. The cured liquid crystal layer that is a positive C plate is a "vertically aligned cured liquid crystal layer" in which a polymerizable liquid crystal compound is cured in a state where it is aligned vertically relative to the substrate surface. By including a retardation layer that is a horizontally aligned cured liquid crystal layer in combination with a retardation layer that is a vertically aligned cured liquid crystal layer, when the circular polarizer is applied to an organic EL display device or the like, an improvement in not only the front reflection hue but also the oblique reflection hue can be expected. When the pressure-sensitive adhesive layer-attached circular polarizer of the present invention includes a vertically aligned cured liquid crystal layer, the retardation layer that is a vertically aligned cured liquid crystal layer is preferably disposed between the polarizer and the second pressure-sensitive adhesive layer.

[0170] When the pressure-sensitive adhesive layer-attached circularly polarizing plate of the present invention contains a vertically aligned liquid crystal cured layer, the liquid crystal cured layer preferably satisfies formula (9). -100nm≦Rth(550)≦-40nm (9) (wherein Rth(550) represents a retardation value in the thickness direction of the cured liquid crystal layer at a wavelength of 550 nm, and Rth=((nx(λ)+ny(λ)) / 2-nz)×d (wherein d represents the thickness of the cured liquid crystal layer, nx represents the principal refractive index at a wavelength of λ nm in a direction parallel to the plane of the cured liquid crystal layer in the index ellipsoid formed by the cured liquid crystal layer, ny represents the refractive index at a wavelength of λ nm in a direction parallel to the plane of the cured liquid crystal layer and perpendicular to the direction of nx in the index ellipsoid formed by the cured liquid crystal layer, and nz represents the refractive index at a wavelength of λ nm in a direction perpendicular to the plane of the cured liquid crystal layer in the index ellipsoid formed by the cured liquid crystal layer).)

[0171] When the vertically aligned liquid crystal cured layer satisfies formula (9), the oblique reflection hue can be improved when a circular polarizer including the liquid crystal cured layer is applied to an organic EL display device. The retardation value Rth(550) in the thickness direction of the liquid crystal cured layer is more preferably −90 nm or more, even more preferably −80 nm or more, and more preferably −50 nm or less.

[0172] In the present invention, the retardation layer (horizontally aligned liquid crystal cured layer and vertically aligned liquid crystal cured layer) is composed of a cured layer of a polymerizable liquid crystal composition (hereinafter also referred to as "composition for forming retardation layer") containing at least one polymerizable liquid crystal compound. The polymerizable liquid crystal compound can be appropriately selected from polymerizable liquid crystal compounds conventionally known in the field of retardation films according to the desired optical properties.

[0173] The polymerizable liquid crystal compound is a liquid crystal compound having a polymerizable group. Generally, the polymer (cured product) obtained by polymerizing the polymerizable liquid crystal compound alone while oriented in a specific direction includes a polymerizable liquid crystal compound exhibiting positive wavelength dispersion and a polymerizable liquid crystal compound exhibiting reverse wavelength dispersion. In the present invention, only one type of polymerizable liquid crystal compound may be used, or both types of polymerizable liquid crystal compounds may be used in combination. Furthermore, when the circular polarizer includes a horizontally aligned liquid crystal cured layer and a vertically aligned liquid crystal cured layer, the polymerizable liquid crystal compounds constituting these layers may be the same or different. From the viewpoint of easily improving the optical properties of the circular polarizer, in one embodiment of the present invention, the horizontally aligned liquid crystal cured layer is preferably a cured layer of a polymerizable liquid crystal composition containing a polymerizable liquid crystal compound exhibiting so-called reverse wavelength dispersion.

[0174] In the present invention, the polymerizable group possessed by the polymerizable liquid crystal compound forming the retardation layer is preferably a photopolymerizable group. The photopolymerizable group refers to a polymerizable group that can be involved in a polymerization reaction by a reactive species generated from a photopolymerization initiator, such as an active radical or an acid. Examples of the photopolymerizable group include a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, a (meth)acryloyl group, an oxiranyl group, and an oxetanyl group. Among these, a (meth)acryloyl group, a vinyloxy group, an oxiranyl group, and an oxetanyl group are preferred, and an acryloyl group is more preferred.

[0175] The liquid crystallinity exhibited by the polymerizable liquid crystal compound may be thermotropic or lyotropic, but thermotropic liquid crystal is preferred because it allows precise control of film thickness. The phase-ordered structure of the thermotropic liquid crystal may be nematic, smectic, or discotic. The polymerizable liquid crystal compounds may be used alone or in combination.

[0176] Polymerizable liquid crystal compounds having a so-called T-shaped or H-shaped molecular structure tend to exhibit reverse wavelength dispersion when polymerized and cured, and polymerizable liquid crystal compounds having a T-shaped molecular structure tend to exhibit even stronger reverse wavelength dispersion.

[0177] The polymerizable liquid crystal compound exhibiting reverse wavelength dispersion is preferably a compound having the following characteristics (A) to (D). (A) A compound capable of forming a nematic or smectic phase. (B) The polymerizable liquid crystal compound has π electrons in the long axis direction (a). (C) It has π electrons in a direction intersecting the long axis direction (a) [intersecting direction (b)]. (D) The π electron density in the long axis direction (a) of a polymerizable liquid crystal compound defined by the following formula (i), where N(πa) is the total number of π electrons present in the long axis direction (a) and N(Aa) is the total number of molecular weights present in the long axis direction: D(πa)=N(πa) / N(Aa) (i) The π electron density in the cross direction (b) of the polymerizable liquid crystal compound is defined by the following formula (ii), where N(πb) is the total number of π electrons present in the cross direction (b) and N(Ab) is the total molecular weight present in the cross direction (b): D(πb)=N(πb) / N(Ab) (ii) and the formula (iii) 0≦[D(πa) / D(πb)]<1 (iii) [i.e., the π electron density in the cross direction (b) is greater than the π electron density in the long axis direction (a)]. As described above, polymerizable liquid crystal compounds having π electrons on the long axis and in the direction crossing the long axis generally tend to form a T-shaped structure.

[0178] In the above features (A) to (D), the long axis direction (a) and the number of π electrons N are defined as follows. The long axis direction (a) is, for example, in the case of a compound having a rod-like structure, the long axis direction of the rod. The number of π electrons present in the long axis direction (a), N(πa), does not include the π electrons lost during the polymerization reaction. The number of π electrons present along the long axis (a), N(πa), is the total number of π electrons on the long axis and those conjugated to it, and includes, for example, the number of π electrons present in rings present along the long axis (a) that satisfy Hückel's rule. The number of π electrons present in the cross direction (b), N(πb), does not include the π electrons lost due to the polymerization reaction. A polymerizable liquid crystal compound that satisfies the above conditions has a mesogenic structure in the long axis direction, and this mesogenic structure allows the compound to exhibit a liquid crystal phase (nematic phase, smectic phase, etc.).

[0179] A polymerizable liquid crystal compound satisfying the above (A) to (D) can be heated above its phase transition temperature to form a nematic or smectic phase. In the nematic or smectic phase formed by orienting the polymerizable liquid crystal compound, the long axes of the polymerizable liquid crystal compounds are typically aligned parallel to each other, with the long axes being the orientation direction of the nematic or smectic phase. When such a polymerizable liquid crystal compound is formed into a film and polymerized in the nematic or smectic phase, a polymer film can be formed, consisting of polymers oriented along the long axis (a). This polymer film absorbs ultraviolet light through π electrons in the long axis direction (a) and π electrons in the cross direction (b). Here, the maximum absorption wavelength of ultraviolet light absorbed by π electrons in the cross direction (b) is defined as λbmax. λbmax is typically 300 nm to 400 nm. The π electron density satisfies the above formula (iii), and the π electron density in the cross direction (b) is greater than the π electron density in the long axis direction (a), resulting in a polymer film in which the absorption of linearly polarized UV light (wavelength λbmax) having a vibration plane in the cross direction (b) is greater than the absorption of linearly polarized UV light (wavelength λbmax) having a vibration plane in the long axis direction (a). The ratio (the ratio of the absorbance of linearly polarized UV light in the cross direction (b) to the absorbance in the long axis direction (a)) is, for example, greater than 1.0, preferably 1.2 or more, and usually 30 or less, for example 10 or less.

[0180] Polymerizable liquid crystal compounds having the above characteristics generally exhibit reverse wavelength dispersion in the birefringence of the polymer when polymerized in a unidirectionally aligned state. Specific examples thereof include compounds represented by the following formula (X) (hereinafter also referred to as "polymerizable liquid crystal compound (X)"). [ka]

[0181] In formula (X), Ar represents a divalent group having an aromatic group which may have a substituent. Examples of the aromatic group include the groups exemplified by (Ar-1) to (Ar-23) described below. Ar may also have two or more aromatic groups. The aromatic group may contain at least one of a nitrogen atom, an oxygen atom, and a sulfur atom. When Ar contains two or more aromatic groups, the two or more aromatic groups may be bonded to each other via a divalent bonding group such as a single bond, -CO-O-, or -O-.

[0182] In formula (X), G 1 and G 2 each independently represents a divalent aromatic group or a divalent alicyclic hydrocarbon group, wherein a hydrogen atom contained in the divalent aromatic group or divalent alicyclic hydrocarbon group may be substituted with a halogen atom, an alkyl group having 1 to 4 carbon atoms, a fluoroalkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group, or a nitro group, and a carbon atom constituting the divalent aromatic group or divalent alicyclic hydrocarbon group may be substituted with an oxygen atom, a sulfur atom, or a nitrogen atom.

[0183] In formula (X), L 1 , L 2 , B 1 and B 2 are each independently a single bond or a divalent linking group.

[0184] In formula (X), k and l each independently represent an integer of 0 to 3, and satisfy the relationship 1≦k+l. When 2≦k+l, B 1 and B 2 , G 1 and G 2 may be the same as or different from each other.

[0185] In formula (X), E 1 and E 2are each independently an alkanediyl group having 1 to 17 carbon atoms, and more preferably an alkanediyl group having 4 to 12 carbon atoms. Furthermore, a hydrogen atom contained in the alkanediyl group may be substituted with a halogen atom, and -CH2- contained in the alkanediyl group may be substituted with -O-, -S-, or -C(=O)-.

[0186] In formula (X), P 1 and P 2 each independently represents a polymerizable group or a hydrogen atom, and at least one of them is a polymerizable group.

[0187] G 1 and G 2 are each independently preferably a 1,4-phenylenediyl group optionally substituted with at least one substituent selected from the group consisting of halogen atoms and alkyl groups having 1 to 4 carbon atoms, or a 1,4-cyclohexanediyl group optionally substituted with at least one substituent selected from the group consisting of halogen atoms and alkyl groups having 1 to 4 carbon atoms, more preferably a 1,4-phenylenediyl group substituted with a methyl group, an unsubstituted 1,4-phenylenediyl group, or an unsubstituted 1,4-trans-cyclohexanediyl group, and particularly preferably an unsubstituted 1,4-phenylenediyl group or an unsubstituted 1,4-trans-cyclohexanediyl group. Also, there are multiple G 1 and G 2 At least one of L is preferably a divalent alicyclic hydrocarbon group. 1 or L 2 G binds to 1 and G 2 It is more preferable that at least one of the groups is a divalent alicyclic hydrocarbon group.

[0188] L 1 and L 2 are each independently preferably a single bond, an alkylene group having 1 to 4 carbon atoms, -O-, -S-, -R a1 OR a2 -, -R a3 COOR a4 -, -Ra5 OCOR a6 -, -R a7 OC=OOR a8 -, -N=N-, -CR c =CR d -, or -C≡C-, where R a1 ~R a8 each independently represents a single bond or an alkylene group having 1 to 4 carbon atoms, and R c and R d represents an alkyl group having 1 to 4 carbon atoms or a hydrogen atom. 1 and L 2 are each independently preferably a single bond, -OR a2-1 -, -CH2-, -CH2CH2-, -COOR a4-1 -, or -OCOR a6-1 -, where R a2-1 , R a4-1 , R a6-1 Each independently represents a single bond, -CH2-, or -CH2CH2-. 1 and L 2 are each independently more preferably a single bond, -O-, -CH2CH2-, -COO-, -COOCH2CH2-, or -OCO-.

[0189] B 1 and B 2 are each independently preferably a single bond, an alkylene group having 1 to 4 carbon atoms, -O-, -S-, -R a9 OR a10 -, -R a11 COOR a12 -, -R a13 OCOR a14 -, or -R a15 OC=OOR a16 -, where R a9 ~R a16 each independently represents a single bond or an alkylene group having 1 to 4 carbon atoms. 1 and B 2 are each independently preferably a single bond, -OR a10-1 -, -CH2-, -CH2CH2-, -COOR a12-1 -, or -OCOR a14-1 -, where Ra10-1 , R a12-1 , R a14-1 Each independently represents a single bond, -CH2-, or -CH2CH2-. B 1 and B 2 are each independently more preferably a single bond, -O-, -CH2CH2-, -COO-, -COOCH2CH2-, -OCO-, or -OCOCH2CH2-.

[0190] From the viewpoint of exhibiting reverse wavelength dispersion, k and l are preferably in the range of 2≦k+l≦6, preferably k+l=4, and more preferably k=2 and l=2. When k=2 and l=2, a symmetric structure is obtained, which is preferable.

[0191] P 1 or P 2 Examples of the polymerizable group represented by the formula (I) include an epoxy group, a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, a (meth)acryloyl group, an oxiranyl group, and an oxetanyl group. Among these, a (meth)acryloyl group, a vinyl group, and a vinyloxy group are preferred, and a (meth)acryloyl group is more preferred.

[0192] Ar preferably has at least one selected from an aromatic hydrocarbon ring which may have a substituent, an aromatic heterocyclic ring which may have a substituent, and an electron-withdrawing group. Examples of the aromatic hydrocarbon ring include a benzene ring, a naphthalene ring, and an anthracene ring, with a benzene ring and a naphthalene ring being preferred. Examples of the aromatic heterocyclic ring include a furan ring, a benzofuran ring, a pyrrole ring, an indole ring, a thiophene ring, a benzothiophene ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, a triazole ring, a triazine ring, a pyrroline ring, an imidazole ring, a pyrazole ring, a thiazole ring, a benzothiazole ring, a thienothiazole ring, an oxazole ring, a benzoxazole ring, and a phenanthroline ring. Among these, a thiazole ring, a benzothiazole ring, or a benzofuran ring is preferred, and a benzothiazole ring is even more preferred. Furthermore, when Ar contains a nitrogen atom, it is preferred that the nitrogen atom has π electrons.

[0193] In formula (X), the total number of π electrons possessed by the group represented by Ar is N π is usually 6 or more, preferably 8 or more, more preferably 10 or more, even more preferably 14 or more, and particularly preferably 16 or more. It is also preferably 36 or less, more preferably 32 or less, even more preferably 26 or less, and particularly preferably 24 or less.

[0194] Examples of the aromatic group contained in Ar include the following groups.

[0195] [ka]

[0196] In formulas (Ar-1) to (Ar-23), * represents a linking portion, and Z 0 , Z 1 and Z 2each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, a cyano group, a nitro group, an alkylsulfinyl group having 1 to 12 carbon atoms, an alkylsulfonyl group having 1 to 12 carbon atoms, a carboxyl group, a fluoroalkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an alkylthio group having 1 to 12 carbon atoms, an N-alkylamino group having 1 to 12 carbon atoms, an N,N-dialkylamino group having 2 to 12 carbon atoms, an N-alkylsulfamoyl group having 1 to 12 carbon atoms, or an N,N-dialkylsulfamoyl group having 2 to 12 carbon atoms. 0 , Z 1 and Z 2 may contain a polymerizable group.

[0197] In formula (Ar-1) ~ formula (Ar-23), Q 1 and Q 2 are each independently -CR 2’ R 3’ -, -S-, -NH-, -NR 2’ represents -, -CO- or -O-, and R 2’ and R 3’ each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

[0198] In formula (Ar-1) ~ formula (Ar-23), J 1 and J. 2 each independently represents a carbon atom or a nitrogen atom.

[0199] In formula (Ar-1) ~ formula (Ar-23), Y 1 , Y 2 and Y 3 each independently represents an optionally substituted aromatic hydrocarbon group or an optionally substituted aromatic heterocyclic group.

[0200] In formulas (Ar-1) to (Ar-23), W 1 and W 2 each independently represents a hydrogen atom, a cyano group, a methyl group or a halogen atom; and m represents an integer of 0 to 6.

[0201] Y 1 , Y 2and Y 3 Examples of the aromatic hydrocarbon group in the formula (I) include aromatic hydrocarbon groups having 6 to 20 carbon atoms, such as a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, and a biphenyl group, with a phenyl group and a naphthyl group being preferred, and a phenyl group being more preferred. Examples of the aromatic heterocyclic group include aromatic heterocyclic groups having 4 to 20 carbon atoms and containing at least one heteroatom, such as a nitrogen atom, an oxygen atom, or a sulfur atom, such as a furyl group, a pyrrolyl group, a thienyl group, a pyridinyl group, a thiazolyl group, and a benzothiazolyl group being preferred.

[0202] Y 1 , Y 2 and Y 3 may each independently be an optionally substituted polycyclic aromatic hydrocarbon group or polycyclic aromatic heterocyclic group. The polycyclic aromatic hydrocarbon group refers to a fused polycyclic aromatic hydrocarbon group or a group derived from an aromatic ring assembly. The polycyclic aromatic heterocyclic group refers to a fused polycyclic aromatic heterocyclic group or a group derived from an aromatic ring assembly.

[0203] Z 0 , Z 1 and Z 2 are each independently preferably a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, a cyano group, a nitro group, or an alkoxy group having 1 to 12 carbon atoms; Z 0 is more preferably a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or a cyano group, and Z 1 and Z 2 is more preferably a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group, or a cyano group. 0 , Z 1 and Z 2 may contain a polymerizable group.

[0204] Q 1 and Q 2 -NH-, -S-, -NR 2’ -, -O- are preferred, and R 2’ is preferably a hydrogen atom, and among these, -S-, -O-, and -NH- are particularly preferred.

[0205] Among the formulae (Ar-1) to (Ar-23), the formulae (Ar-6) and (Ar-7) are preferred from the viewpoint of molecular stability.

[0206] In formulas (Ar-16) to (Ar-23), Y 1 is the nitrogen atom to which it is bonded and Z 0 and Y may form an aromatic heterocyclic group together. Examples of the aromatic heterocyclic group include those mentioned above as aromatic heterocycles that Ar may have, such as a pyrrole ring, an imidazole ring, a pyrroline ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, an indole ring, a quinoline ring, an isoquinoline ring, a purine ring, and a pyrrolidine ring. This aromatic heterocyclic group may have a substituent. In addition, Y 1 is the nitrogen atom to which it is bonded and Z 0 and may be the above-mentioned optionally substituted polycyclic aromatic hydrocarbon group or polycyclic aromatic heterocyclic group, such as a benzofuran ring, a benzothiazole ring, or a benzoxazole ring.

[0207] Examples of the compound represented by formula (X) include polymerizable liquid crystal compounds described in JP-A-2010-31223 and JP-A-2021-47245, and can be produced according to the methods described in these documents.

[0208] In the present invention, as the polymerizable liquid crystal compound forming the retardation layer, for example, a compound containing a group represented by the following formula (Y) (hereinafter also referred to as "polymerizable liquid crystal compound (Y)") may be used. The polymerizable liquid crystal compound (Y) generally tends to exhibit positive wavelength dispersion. These polymerizable liquid crystal compounds may be used alone or in combination of two or more.

[0209] P11-B11-E11-B12-A11-B13- (Y) In formula (Y), P11 represents a polymerizable group. A11 represents a divalent alicyclic hydrocarbon group or a divalent aromatic hydrocarbon group. B11 is -O-, -S-, -CO-O-, -O-CO-, -O-CO-O-, -CO-NR 16 -, -NR 16 R represents -CO-, -CO-, -CS- or a single bond. 16 represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. B12 and B13 each independently represent -C≡C-, -CH=CH-, -CH2-CH2-, -O-, -S-, -C(=O)-, -C(=O)-O-, -OC(=O)-, -OC(=O)-O-, -CH=N-, -N=CH-, -N=N-, or -C(=O)-NR 16 -, -NR 16 represents -C(=O)-, -OCH2-, -OCF2-, -CH2O-, -CF2O-, -CH=CH-C(=O)-O-, -OC(=O)-CH=CH-, -H, -C≡N or a single bond. E11 represents an alkanediyl group having 1 to 12 carbon atoms, and a hydrogen atom contained in the alkanediyl group may be substituted with an alkoxy group having 1 to 5 carbon atoms, and a hydrogen atom contained in the alkoxy group may be substituted with a halogen atom. In addition, -CH2- constituting the alkanediyl group may be substituted with -O- or -CO-.

[0210] The number of carbon atoms in the aromatic hydrocarbon group and alicyclic hydrocarbon group of A11 is preferably in the range of 3 to 18, more preferably in the range of 5 to 12, and particularly preferably 5 or 6. The hydrogen atoms contained in the divalent alicyclic hydrocarbon group and divalent aromatic hydrocarbon group represented by A11 may be substituted with a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a cyano group, or a nitro group, and the hydrogen atoms contained in the alkyl group having 1 to 6 carbon atoms and the alkoxy group having 1 to 6 carbon atoms may be substituted with a fluorine atom. A11 is preferably a cyclohexane-1,4-diyl group or a 1,4-phenylene group.

[0211] E11 is preferably a linear alkanediyl group having 1 to 12 carbon atoms. -CH2- constituting the alkanediyl group may be replaced with -O-. Specific examples include linear alkanediyl groups having 1 to 12 carbon atoms, such as methylene, ethylene, propane-1,3-diyl, butane-1,4-diyl, pentane-1,5-diyl, hexane-1,6-diyl, heptane-1,7-diyl, octane-1,8-diyl, nonane-1,9-diyl, decane-1,10-diyl, undecane-1,11-diyl, and dodecane-1,12-diyl; -CH-CH-O-CH-CH-, -CH-CH-O-CH-CH-O-CH-CH-, and -CH-CH-O-CH-CH-O-CH-CH-O-CH-CH-. As B11, -O-, -S-, -CO-O-, and -O-CO- are preferred, and among these, -CO-O- is more preferred. B12 and B13 are each independently preferably -O-, -S-, -C(=O)-, -C(=O)-O-, -OC(=O)- or -OC(=O)-O-, and among these, -O- or -OC(=O)-O- is more preferred.

[0212] The polymerizable group represented by P11 is preferably a radically polymerizable group or a cationically polymerizable group in terms of high polymerization reactivity, particularly high photopolymerization reactivity. In addition, the polymerizable group is preferably a group represented by the following formulas (P-11) to (P-15), because they are easy to handle and the liquid crystal compound itself is easy to produce. [ka] [In formulas (P-11) to (P-15), R 17 ~R 21 each independently represents an alkyl group having 1 to 6 carbon atoms or a hydrogen atom.

[0213] Specific examples of the groups represented by formulae (P-11) to (P-15) include groups represented by the following formulae (P-16) to (P-20). [ka]

[0214] P11 is preferably a group represented by formula (P-14) to formula (P-20), and more preferably a vinyl group, a p-stilbene group, an epoxy group or an oxetanyl group. The group represented by P11-B11- is more preferably an acryloyloxy group or a methacryloyloxy group.

[0215] Examples of the polymerizable liquid crystal compound (Y) include compounds represented by formula (I), formula (II), formula (III), formula (IV), formula (V) or formula (VI). P11-B11-E11-B12-A11-B13-A12-B14-A13-B15-A14-B16-E12-B17-P12 (I) P11-B11-E11-B12-A11-B13-A12-B14-A13-B15-A14-F11 (II) P11-B11-E11-B12-A11-B13-A12-B14-A13-B15-E12-B17-P12 (III) P11-B11-E11-B12-A11-B13-A12-B14-A13-F11 (IV) P11-B11-E11-B12-A11-B13-A12-B14-E12-B17-P12 (V) P11-B11-E11-B12-A11-B13-A12-F11 (VI) [In the formula, A11, B11 to B13, and P11 are as defined above. A12 to A14 each independently have the same meaning as A11, B14 to B16 each independently have the same meaning as B12, B17 has the same meaning as B11, E12 has the same meaning as E11, and P12 has the same meaning as P11. F11 represents a hydrogen atom, an alkyl group having 1 to 13 carbon atoms, an alkoxy group having 1 to 13 carbon atoms, a cyano group, a nitro group, a trifluoromethyl group, a dimethylamino group, a hydroxyl group, a methylol group, a formyl group, a sulfo group (—SO3H), a carboxyl group, an alkoxycarbonyl group having 1 to 10 carbon atoms, or a halogen atom, and —CH2— constituting the alkyl group and alkoxy group may be replaced with —O—.]

[0216] Specific examples of the polymerizable liquid crystal compound (Y) include compounds having a polymerizable group among the compounds described in "3.8.6 Network (completely crosslinked type)" and "6.5.1 Liquid crystal materials b. Polymerizable nematic liquid crystal materials" in Liquid Crystal Handbook (edited by Liquid Crystal Handbook Editorial Committee, published by Maruzen Co., Ltd. on October 30, 2000), and the polymerizable liquid crystals described in JP-A Nos. 2010-31223, 2010-270108, 2011-6360, and 2011-207765.

[0217] The polymerizable liquid crystal compound (X) and the polymerizable liquid crystal compound (Y) can be used either horizontally or vertically aligned. The polymerizable liquid crystal compound (X) and the polymerizable liquid crystal compound (Y) can be used alone, in combination of two or more kinds, or in combination of both.

[0218] The content of the polymerizable liquid crystal compound in the composition for forming a retardation layer is, for example, 70 to 99.5 parts by mass, preferably 80 to 99 parts by mass, more preferably 85 to 98 parts by mass, and even more preferably 90 to 95 parts by mass, relative to 100 parts by mass of the solid content of the composition for forming a retardation layer. If the content of the polymerizable liquid crystal compound is within the above range, it is advantageous from the viewpoint of the alignment of the obtained retardation layer. Note that, when the composition for forming a retardation layer contains two or more polymerizable liquid crystal compounds, it is preferable that the total amount of all liquid crystal compounds contained in the composition for forming a retardation layer is within the above content range.

[0219] The retardation layer forming composition may contain a polymerization initiator for initiating the polymerization reaction of polymerizable liquid crystal compound.The polymerization initiator can be appropriately selected from those conventionally used in this field, and may be a thermal polymerization initiator or a photopolymerization initiator, but photopolymerization initiator is preferred because it can initiate the polymerization reaction under lower temperature conditions.Preferably, the same as those exemplified above can be used as the photopolymerization initiator that can be used in the polarizer forming composition.

[0220] The retardation layer-forming composition is preferably dissolved in a solvent and applied to a substrate film or the like, and therefore preferably contains a solvent. The solvent is preferably a solvent capable of dissolving a polymerizable liquid crystal compound, and is preferably a solvent inactive to the polymerization reaction of the polymerizable liquid crystal compound. Examples of the solvent include the same solvents as those exemplified above as those usable in the polarizer-forming composition.

[0221] Furthermore, the retardation layer-forming composition may contain, as necessary, a photosensitizer, a leveling agent, a reactive additive, and the additives exemplified as additives contained in the polarizer-forming composition. Examples of the photosensitizer and the leveling agent include those exemplified above as additives that can be used in the polarizer-forming composition.

[0222] The retardation layer-forming composition can be prepared, for example, by mixing and stirring a polymerizable liquid crystal compound and, if necessary, a polymerization initiator, a solvent, an additive, and the like.

[0223] The retardation layer can be obtained, for example, by applying a retardation layer-forming composition to a substrate or an alignment film, drying the resulting coating film, and aligning the polymerizable liquid crystal compound in the retardation layer-forming composition, and then polymerizing the polymerizable liquid crystal compound by light irradiation or the like while maintaining the alignment state. Examples of the substrate include the same substrate film constituting the pressure-sensitive adhesive layer-attached circular polarizer of the present invention. Examples of the alignment film include, in addition to the photo-alignment film exemplified above as a film that can be used when producing the polarizer of the present invention, an alignment film containing an oriented polymer, and a groove alignment film having a concavo-convex pattern or a plurality of grooves on the surface. The film may be appropriately selected depending on the desired alignment control force, etc.

[0224] Examples of orienting polymers include polyamides and gelatins having an amide bond in the molecule, polyimides having an imide bond in the molecule, and their hydrolyzed products such as polyamic acid, polyvinyl alcohol, alkyl-modified polyvinyl alcohol, polyacrylamide, polyoxazole, polyethyleneimine, polystyrene, polyvinylpyrrolidone, polyacrylic acid, and polyacrylic acid esters. Among these, polyvinyl alcohol is preferred. Orienting polymers can be used alone or in combination of two or more.

[0225] An alignment film containing an alignment polymer is usually obtained by applying a composition in which the alignment polymer is dissolved in a solvent (hereinafter also referred to as an "alignment polymer composition") to a surface on which the alignment film is to be formed, such as a substrate film, and then removing the solvent, or by applying the alignment polymer composition to a substrate, removing the solvent, and then rubbing (rubbing method). Examples of the solvent include the same solvents as those exemplified above as solvents that can be used in the polarizer-forming composition.

[0226] The concentration of the orienting polymer in the orienting polymer composition may be within a range in which the orienting polymer material can be completely dissolved in the solvent, and is preferably 0.1 to 20% in terms of solid content relative to the solution, more preferably about 0.1 to 10%.

[0227] As the oriented polymer composition, commercially available alignment film materials may be used as they are. Examples of commercially available alignment film materials include SUNEVER (registered trademark, manufactured by Nissan Chemical Industries, Ltd.) and OPTOMER (registered trademark, manufactured by JSR Corporation).

[0228] As a method for applying the oriented polymer composition to a surface of a substrate or the like on which an oriented film is to be formed and a method for removing the solvent in the coating film, the same methods as those for applying the polarizer-forming composition to a substrate film or the like and removing the solvent in the coating film can be used.

[0229] The resulting dried coating film of the oriented polymer composition is subjected to a rubbing treatment to obtain a rubbed alignment film. Examples of the rubbing treatment method include contacting the dried coating film of the oriented polymer composition with a rotating rubbing roll around which a rubbing cloth is wound. If masking is performed during the rubbing treatment, multiple regions (patterns) with different orientation directions can be formed on the alignment film.

[0230] A groove alignment film is a film with a concave-convex pattern or multiple grooves on its surface. When a polymerizable liquid crystal compound is applied to a film with multiple equally spaced linear grooves, the liquid crystal molecules are oriented in the direction along the grooves.

[0231] Methods for obtaining a grooved alignment film include a method in which the surface of a photosensitive polyimide film is exposed to light through an exposure mask having pattern-shaped slits, followed by development and rinsing to form a concave-convex pattern; a method in which a layer of uncured UV-curable resin is formed on a plate-shaped master having grooves on its surface, and the formed resin layer is transferred to a substrate or the like and then cured; and a method in which a roll-shaped master having multiple grooves is pressed against an uncured UV-curable resin film formed on the surface on which the alignment film is to be formed to form concave-convex patterns, and then the resin is cured.

[0232] The thickness of the alignment film (alignment film containing an alignment polymer or photoalignment film) for forming the retardation layer is usually in the range of 10 to 10,000 nm, preferably in the range of 10 to 2,500 nm, more preferably 10 to 1,000 nm or less, even more preferably 10 to 500 nm, and particularly preferably 50 to 250 nm.

[0233] In the pressure-sensitive adhesive layer-attached circular polarizer of the present invention, the thickness of the retardation layer can be appropriately selected depending on the display device to which it is applied, but from the viewpoint of thinning, it is preferably 0.1 to 10 μm, more preferably 0.5 to 5 μm, and even more preferably 1 to 3 μm. When the pressure-sensitive adhesive layer-attached circular polarizer of the present invention includes multiple retardation layers, the thicknesses of the respective retardation layers included in the retardation layer may be the same or different, but are preferably within the above ranges.

[0234] When the pressure-sensitive adhesive layer-attached circular polarizer of the present invention includes a retardation layer made of a horizontally aligned cured liquid crystal layer and a retardation layer made of a vertically aligned cured liquid crystal layer, the vertically aligned cured liquid crystal layer is preferably disposed between the polarizer and the second pressure-sensitive adhesive layer. When the pressure-sensitive adhesive layer includes a retardation layer made of a horizontally aligned cured liquid crystal layer and a retardation layer made of a vertically aligned cured liquid crystal layer, the polarizer, the adhesive layer, the first retardation layer, the second retardation layer, and the second adhesive layer are preferably laminated in this order. In this case, either the horizontally aligned cured liquid crystal layer or the vertically aligned cured liquid crystal layer may be disposed on the polarizer side (i.e., the first retardation layer). The horizontally aligned cured liquid crystal layer and the vertically aligned cured liquid crystal layer may be bonded together via an adhesive layer. Alternatively, the vertically aligned cured liquid crystal layer may be laminated on the horizontally aligned cured liquid crystal layer with or without an alignment film having a horizontal alignment force. Alternatively, the horizontally aligned cured liquid crystal layer may be laminated on the vertically aligned cured liquid crystal layer with or without an alignment film having a horizontal alignment force.

[0235] [Adhesive layer] In the present invention, the adhesive layer disposed between the polarizing plate and the retardation layer is a layer formed from an adhesive. The adhesive layer can be formed from a known adhesive as long as it functions as a layer for bonding the polarizing plate and the retardation layer. The adhesive or adhesive is not particularly limited, and conventionally known adhesives and adhesives can be used without particular limitation. Examples of adhesives include adhesives having a base polymer such as acrylic, rubber, urethane, silicone, or polyvinyl ether. Energy ray-curable adhesives and heat-curable adhesives may also be used. Examples of adhesives include active energy ray-curable adhesives, water-based adhesives, organic solvent-based adhesives, and solventless adhesives. In one embodiment of the present invention, the adhesive layer is formed from an adhesive.

[0236] The thickness of the adhesive layer is usually 1 to 40 μm, and preferably 3 to 25 μm.

[0237] When laminating a polarizing plate and a retardation layer, it is preferable to laminate them so that the slow axis (optical axis) of the retardation layer and the absorption axis of the polarizer are substantially at 45°. By laminating them so that the slow axis (optical axis) of the retardation layer and the absorption axis of the polarizer are substantially at 45°, it is possible to obtain the function of a circular polarizing plate. Note that substantially 45° is usually in the range of 45±5°.

[0238] [Circularly polarizing plate with adhesive layer] The pressure-sensitive adhesive layer-attached circular polarizing plate of the present invention can be produced by forming and laminating a first base film, a first pressure-sensitive adhesive layer, a polarizing plate, a tacky adhesive layer, a retardation layer, a second pressure-sensitive adhesive layer, and a second base film, as well as an alignment film, a diffusion prevention layer, and the like, as needed, in an appropriate order according to the production method, etc. described above for each layer, so as to have a desired configuration depending on the application, etc. The pressure-sensitive adhesive layer-attached circular polarizing plate of the present invention can be produced, for example, in the case where the polarizing plate includes a diffusion prevention layer on both sides of the polarizer, by the following procedure: forming an alignment film on a diffusion prevention layer formed on a substrate film, forming a polarizer on the alignment film, and then forming a diffusion prevention layer on the polarizer to produce a polarizing plate having a polarizer between two diffusion prevention layers; separately from this, forming a retardation layer on a substrate film via an alignment film to produce a laminate having a retardation layer, and bonding the laminate having the retardation layer and the polarizing plate with a pressure-sensitive adhesive to produce a laminate (A) comprising substrate film / diffusion prevention layer / alignment film / polarizer / diffusion prevention layer / adhesive layer / retardation layer / alignment film / substrate film in this order; further forming a first pressure-sensitive adhesive layer on a first substrate film, A laminate (B) consisting of one substrate film / first pressure-sensitive adhesive layer / substrate film is produced, and a second pressure-sensitive adhesive layer is formed on the second substrate film to produce a laminate (C) consisting of a second substrate film / second pressure-sensitive adhesive layer / substrate film. The substrate film of laminate (A) is peeled from the substrate film of laminate (B), and the diffusion prevention layer and the first pressure-sensitive adhesive layer are bonded together. The substrate films of both outer layers of laminate (A), the substrate film of laminate (B), and the substrate film of laminate (C) are each peeled off, and the diffusion prevention layer and the first pressure-sensitive adhesive layer, and the retardation layer and the second pressure-sensitive adhesive layer are each bonded together, thereby producing a circularly polarizing plate with a pressure-sensitive adhesive layer, which consists of the first substrate film / first pressure-sensitive adhesive layer / diffusion prevention layer / alignment film / polarizer / diffusion prevention layer / adhesive layer / retardation layer / alignment film / second pressure-sensitive adhesive layer / second substrate film in this order.

[0239] In the pressure-sensitive adhesive layer-attached circular polarizing plate of the present invention, the total thickness of the laminate b consisting of layers located between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer is preferably 20 μm or less. The present invention is configured to suppress the generation of bubbles and wrinkles that tend to occur during transfer in ultra-thin circular polarizing plates, and the effects of the present invention are more pronounced in laminates in which the structure (laminate b) for providing circular polarization function, consisting of a polarizing plate and a retardation layer, etc., located between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer, is thin. In the present invention, the total thickness of the laminate b varies depending on the desired layer structure, but is more preferably 18 μm or less. The lower limit of the total thickness of the laminate b is not particularly limited, but is usually 5 μm or more.

[0240] In the pressure-sensitive adhesive layer-attached circular polarizer of the present invention, in which the circular polarizer (laminate b) is ultrathin, the total thickness of the laminate a is preferably 30 to 120 μm, as this structure makes it easier to prevent lifting between the second base film and the second pressure-sensitive adhesive layer when the laminate a is first peeled off and to further enhance the effect of suppressing the formation of bubbles due to this. From the viewpoint of easily ensuring the easy peelability of the laminate a while achieving a high effect of suppressing the formation of bubbles between the second base film and the second pressure-sensitive adhesive layer, the total thickness of the laminate a is more preferably 40 μm or more, even more preferably 50 μm or more, and more preferably 110 μm or less, even more preferably 100 μm or less.

[0241] In the circular polarizer with a pressure-sensitive adhesive layer of the present invention, the peelable laminate a and the peelable second base film constituting the circular polarizer are both peeled off, and the laminate structure (laminate b) having the function of a circular polarizer is transferred to a transferee via the second pressure-sensitive adhesive layer for use. The circular polarizer with a pressure-sensitive adhesive layer of the present invention, which controls the thicknesses of the laminate a including the first base film to be peeled off first, the laminate b which is the second base film and the circular polarizer, and the peel strengths of the laminate a and the second base film, is excellent in the effect of suppressing the generation of bubbles and wrinkles when the base film is peeled off and the circular polarizer is transferred to a substrate or the like.

[0242] The present invention provides A step of peeling off the laminate a from the above-mentioned pressure-sensitive adhesive layer-attached circular polarizing plate of the present invention; and a step of laminating an adherend via a pressure-sensitive adhesive layer to the surface adjacent to the laminate a peeled off in the peeling step A method for producing an optical laminate, comprising: Includes.

[0243] The method for producing the optical laminate further comprises: The step of peeling off the second base film may be included as a step downstream of the step of peeling off the laminate a.

[0244] For example, even when a long optical laminate is produced using the pressure-sensitive adhesive layer-attached circular polarizer of the present invention, the desired peel strength of the laminate a and the second base film is easily maintained throughout the entire length. Therefore, even when the laminate a and the second base film are continuously peeled off in sequence by a roll-to-roll method using equipment commonly used in the field, the effect of suppressing the generation of bubbles between the second base film and the second pressure-sensitive adhesive layer is excellent without setting special conditions. As a result, the pressure-sensitive adhesive layer-attached circular polarizer of the present invention is suitable for producing a long optical laminate using a roll-to-roll method, because the laminate a and the second base film can be continuously peeled off in this order from the circular polarizer without any problems using common equipment conventionally widely used in the field for producing optical films, optical laminates, etc.

[0245] The pressure-sensitive adhesive layer-attached circular polarizer of the present invention is thin, yet is less likely to develop bubbles or wrinkles due to peeling of the substrate film, and high optical performance can be expected for the circular polarizer after transfer. Therefore, the pressure-sensitive adhesive layer-attached circular polarizer of the present invention can be suitably used in the manufacture of various display devices. A display device is a device having a display element, and includes a light-emitting element or a light-emitting device as a light source. Examples of display devices include liquid crystal display devices, organic electroluminescence (EL) display devices, inorganic electroluminescence (EL) display devices, touch panel display devices, electron emission display devices (e.g., field emission displays (FEDs) and surface field emission displays (SEDs)), electronic paper (display devices using electronic ink or electrophoretic elements), plasma display devices, projection display devices (e.g., grating light valve (GLV) displays and displays having digital micromirror devices (DMDs)), and piezoelectric ceramic displays. Liquid crystal display devices include transmissive liquid crystal display devices, semi-transmissive liquid crystal display devices, reflective liquid crystal display devices, direct-view liquid crystal display devices, and projection liquid crystal display devices. These display devices may be display devices that display two-dimensional images or stereoscopic display devices that display three-dimensional images. [Example]

[0246] The present invention will be described in more detail below with reference to Examples and Comparative Examples. In the Examples and Comparative Examples, "%" and "parts" are "% by mass" and "parts by mass" unless otherwise specified.

[0247] The thickness of each layer in the examples and comparative examples was measured using a contact film thickness measuring device (Nikon Corporation's "MS-5C"), except for the retardation layer (horizontal alignment liquid crystal cured film, vertical alignment liquid crystal cured film) and the alignment film, which was measured using a field emission scanning electron microscope (FE-SEM) (SU-8010, Hitachi High-Tech Corporation).

[0248] 1. Preparation of laminate A1 including polarizing plate (1) Preparation of the composition for forming the diffusion prevention layer The mixture was prepared by mixing 100 parts by mass of water, 3 parts by mass of polyvinyl alcohol resin powder (manufactured by Kuraray Co., Ltd., average degree of polymerization 18,000, product name: KL-318), and 1.5 parts by mass of polyamide epoxy resin (manufactured by Sumika Chemtex Co., Ltd., product name: SR650(30)) as a crosslinking agent.

[0249] (2) Preparation of composition for forming photo-alignment film The following photoalignment polymer was dissolved in cyclopentanone (solvent) at a concentration of 5% by mass to obtain a composition for forming a photoalignment film. Photoalignment polymer: Polymer described in JP 2013-033249 A (number average molecular weight: approximately 28,200, Mw / Mn: 1.82) [ka]

[0250] (3) Preparation of polarizer-forming composition (Polymerizable liquid crystal compound) Compounds (1-1) and (1-2) represented by the following structures were used as polymerizable liquid crystal compounds. Compounds (1-1) and (1-2) were synthesized by the method described in Lub et al., Recl. Trav. Chim. Pays-Bas, 115, 321-328 (1996). ·Compound (1-1) [ka] ·Compound (1-2) [ka]

[0251] (dichroic dye) As the dichroic dyes, the following dichroic dye (1), dichroic dye (2), and dichroic dye (3) described in the examples of JP-A-2013-101328 were used. Dichroic dyes (1) [ka] The dichroic dye shown below (2) [ka] The dichroic dye shown below (3) [ka]

[0252] A polarizer-forming composition was prepared by mixing 75 parts by mass of the compound (1-1), 25 parts by mass of the compound (1-2), 2.5 parts by mass each of the azo dyes represented by the formulas (1), (2), and (3) as dichroic dyes, 6 parts by mass of 2-dimethylamino-2-benzyl-1-(4-morpholinophenyl)butan-1-one (Irgacure 369, manufactured by BASF Japan) as a polymerization initiator, and 1.2 parts by mass of a polyacrylate compound (BYK-361N, manufactured by BYK-Chemie) as a leveling agent with 400 parts by mass of toluene, and stirring the resulting mixture at 80°C for 1 hour.

[0253] (4) Preparation of polarizing plates The above-prepared diffusion prevention layer-forming composition (3% by mass) was applied to the release-treated surface of a release polyethylene terephthalate (PET) film ("FF-50" manufactured by Unitika Ltd., one-side release-treated PET film, substrate thickness: 50 μm) using a bar coater. The resulting solution was dried at 100°C for 2 minutes to form a 2 μm thick diffusion prevention layer made of a water-soluble polymer film. The surface of the resulting diffusion prevention layer was subjected to plasma treatment, and then the above-prepared photoalignment film-forming composition was applied using a bar coater to form a coating film. The coating film was dried at 100°C for 2 minutes to remove the solvent and form a dry coating. Polarized UV light was applied to the dried coating at 20 mJ / cm. 2 The light was irradiated at an intensity of 313 nm to impart an alignment control force, thereby forming a 50 nm photo-alignment film (the resulting laminate structure: substrate / anti-diffusion layer / photo-alignment film).

[0254] Next, the polarizer-forming composition was applied to the obtained photo-alignment film using a bar coater to form a coating film. This was then dried at 110°C for 2 minutes to remove the solvent and cause the polymerizable liquid crystal compound to undergo a phase transition to a liquid phase, followed by cooling to room temperature to cause the polymerizable liquid crystal compound to undergo a phase transition to a smectic liquid crystal state. Then, the obtained dried coating film was irradiated with ultraviolet light at 1000mJ / cm using a high-pressure mercury lamp. 2(365 nm standard) to polymerize the polymerizable liquid crystal compound contained in the dried film while maintaining the smectic liquid crystal state, thereby forming a 3 μm polarizer (the resulting laminate structure: substrate / anti-diffusion layer / photo-alignment film / polarizer).

[0255] Next, the formed polarizer was subjected to a plasma treatment, and then the composition for forming the diffusion prevention layer was applied by a bar coater using a bar coater so as to give a dried thickness of 1.0 μm, and dried for 3 minutes at 80° C. In this way, a laminate A1 including a polarizing plate composed of a substrate / diffusion prevention layer / photoalignment film / polarizer / diffusion prevention layer was obtained.

[0256] 2. Preparation of laminate B1 including retardation layer (1) Preparation of a composition for forming a horizontally aligned liquid crystal cured film To a mixture of polymerizable liquid crystal compound X1 and polymerizable liquid crystal compound Y1 shown below in a mass ratio of 90:10, 1 part by mass of a leveling agent (F-556; manufactured by DIC Corporation) and 6 parts by mass of a polymerization initiator, 2-dimethylamino-2-benzyl-1-(4-morpholinophenyl)butan-1-one ("Irgacure 369 (Irg369)" manufactured by BASF Japan Ltd.) were added.

[0257] Furthermore, N-methyl-2-pyrrolidone (NMP) was added so that the solid content concentration became 13%, and the mixture was stirred at 80° C. for 1 hour, thereby obtaining a composition 1 for forming a horizontally aligned liquid crystal cured film.

[0258] Polymerizable liquid crystal compound X1 was produced according to the method described in JP-A No. 2010-31223. Polymerizable liquid crystal compound Y1 was produced according to the method described in JP-A No. 2009-173893. The molecular structures of each compound are shown below.

[0259] Polymerizable liquid crystal compound X1 [ka]

[0260] Polymerizable liquid crystal compound Y1 [ka]

[0261] (2) Preparation of a composition for forming a vertically aligned liquid crystal cured film The components were mixed according to the composition shown in Table 1, and the resulting solution was stirred at 80° C. for 1 hour and then cooled to room temperature to prepare a composition for forming a vertically aligned liquid crystal cured film. The components in Table 2 are shown below, and the blending amounts indicate the blending ratio of each component to the total amount of the prepared composition.

[0262] [Table 1]

[0263] Irg907: Cationic polymerization initiator [Irgacure 907 (BASF Japan)] BYK-361N: Leveling agent (manufactured by BYK Japan) LR-9000: Reactive additive [Laromer (registered trademark) LR-9000 (manufactured by BASF Japan)] PGMEA: Solvent (propylene glycol 1-monomethyl ether 2-acetate) LC242: Polymerizable liquid crystal compound [polymerizable liquid crystal compound represented by the following formula (manufactured by BASF)] [ka]

[0264] (3) Preparation of composition for forming vertical alignment film A composition for forming a vertical alignment film was obtained by adding 99 parts by mass of 2-butoxyethanol to 1 part by mass (solid content equivalent) of Sunever SE-610 (manufactured by Nissan Chemical Industries, Ltd.). The solid content of SE-610 was calculated from the concentration listed in the delivery specifications.

[0265] (4) Preparation of a laminate containing a horizontally aligned liquid crystal cured film Corona treatment was performed on the release-treated surface of a release polyethylene terephthalate (PET) film (FF-50, one-side release-treated PET film, thickness: 50 μm) manufactured by Zeon Corporation, and then the composition for forming a horizontal alignment film used in the preparation of the polarizer was applied to the corona-treated surface using a bar coater and dried at 80°C for 1 minute. Next, a polarized UV irradiation device ("SPOT CURE SP-9" manufactured by Ushio Inc.) was used to apply the composition to the surface, with an integrated light intensity of 100 mJ / cm at a wavelength of 313 nm. 2 The film was exposed to polarized UV light at an axial angle of 45° at 100° C. to obtain a horizontal alignment film. The thickness of the obtained horizontal alignment film was measured and found to be 100 nm.

[0266] Next, the composition for forming a horizontally aligned liquid crystal cured film was applied to the horizontal alignment film using a bar coater, dried at 120°C for 1 minute, and then irradiated with ultraviolet light (under a nitrogen atmosphere, cumulative light intensity at a wavelength of 365 nm: 500 mJ / cm) using a high-pressure mercury lamp (Uniqure VB-15201BY-A, manufactured by Ushio Inc.). 2 ) to form a horizontally aligned liquid crystal cured film, thereby obtaining a laminate B1-1 consisting of a substrate / horizontal alignment film / horizontally aligned liquid crystal cured film. The thickness of the horizontally aligned liquid crystal cured film in the obtained laminate B1-1 was measured and found to be 2.3 μm.

[0267] (5) Measurement of retardation of horizontally aligned liquid crystal cured film The in-plane retardation value Re(λ) of the horizontally aligned liquid crystal cured film 1 produced by the above method was measured using a measuring device ("KOBRA-WPR", manufactured by Oji Scientific Instruments Co., Ltd.) after laminating the laminate to glass via an adhesive and peeling off the COP substrate. The measured retardation values ​​Re(λ) at each wavelength were Re(450) = 121 nm, Re(550) = 142 nm, Re(650) = 146 nm, and Re(450) / Re(550) = 0.85.

[0268] (6) Preparation of a laminate containing a vertically aligned liquid crystal cured film Corona treatment was performed on the release-treated surface of a release polyethylene terephthalate (PET) film (FF-50, one-sided release-treated PET film, thickness: 50 μm) manufactured by Zeon Corporation. The composition for forming a vertical alignment film was then applied to the corona-treated surface using a bar coater and dried at 90°C for 1 minute to form a vertical alignment film. The thickness of the resulting vertical alignment film was measured using an ellipsometer to find a value of 70 nm. Furthermore, the retardation value of the resulting vertical alignment film at a wavelength of 550 nm was measured (measuring instrument: Oji Scientific Instruments, KOBRA-WR) to find a value of R0(550) = 0.7 nm. Since the retardation value of the COP at a wavelength of 550 nm is approximately 0, it does not affect the retardation value. Subsequently, a composition for forming a vertically aligned liquid crystal cured film was applied onto the obtained vertical alignment film using a bar coater, dried at 90°C for 1 minute, and irradiated with ultraviolet light using a high-pressure mercury lamp (manufactured by Ushio Inc., Uniqure VB-15201BY-A) (under a nitrogen atmosphere, cumulative light intensity at a wavelength of 365 nm: 1000 mJ / cm 2 ) to form a vertically aligned liquid crystal cured film, thereby obtaining a laminate B1-2 consisting of a substrate / vertical alignment film / vertical alignment liquid crystal cured film. The thickness of the vertically aligned liquid crystal cured film in the obtained laminate B1-2 was measured and found to be 534 nm.

[0269] (7) Measurement of retardation of vertically aligned liquid crystal cured film To measure the retardation value of the vertically aligned liquid crystal cured film, a vertically aligned film and a vertically aligned liquid crystal cured film were prepared on a COP film (ZF-14) manufactured by Zeon Corporation using the same procedure as above. The vertically aligned liquid crystal cured film was then attached to glass via an adhesive (15 μm pressure-sensitive adhesive manufactured by Lintec Corporation). After confirming that the COP had no retardation, the retardation value was measured by changing the incident angle of light onto the sample using an ellipsometer. The retardation value calculated from the obtained film thickness, average refractive index, and ellipsometer measurement results was R0(550) = 1.3 nm, R 40 (550) = 21.9 nm, Rth(450) = -91 nm, Rth(550) = -84 nm, Rth(450) / Rth(550) = 1.09.

[0270] (8) Preparation of laminate B1 including retardation layers (cured horizontally aligned liquid crystal film and cured vertically aligned liquid crystal film) An active energy ray-curable adhesive having the following composition was applied to the cured film side of the horizontally aligned liquid crystal of the laminate B1-1 obtained above so that the thickness after curing would be 2 μm, and the laminate was laminated to the cured film side of the vertically aligned liquid crystal of the laminate B1-2 obtained above. From the cured film side of the vertically aligned liquid crystal, an ultraviolet irradiation device (manufactured by Fusion UV Systems Co., Ltd.) was used to irradiate the adhesive with an integrated light dose of 400 mJ / cm. 2 The adhesive was cured by irradiating it with ultraviolet light (UV-B), to obtain a laminate B1 consisting of substrate / horizontal alignment film / cured horizontal alignment liquid crystal film / adhesive layer / cured vertical alignment liquid crystal film / vertical alignment film / substrate.

[0271] Active energy ray curing adhesive composition 30 parts by mass of 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (trade name: CEL2021P, manufactured by Daicel Corporation) 1,6-Hexanediol diglycidyl ether (product name: EX-212L, manufactured by Nagase ChemteX Corporation) 45 parts by mass 25 parts by mass of 4-hydroxybutyl vinyl ether (product name: HBVE, manufactured by Maruzen Petrochemical Co., Ltd.) Cationic polymerization initiator (product name: CPI-100P, manufactured by San-Apro Co., Ltd., 50% by weight solution) 3 parts by weight (solid content)

[0272] 3. Preparation of Circular Polarizer A pressure-sensitive adhesive sheet with a release film (5 μm thick sheet-like adhesive layer (Sumitomo Chemical: optical pressure-sensitive adhesive L2)) was laminated to the diffusion prevention layer side of the laminate A1 containing the polarizing plate prepared above. The release film of the adhesive sheet was then peeled off, and the exposed surface of the substrate on the horizontally aligned liquid crystal cured film side of the laminate B1 prepared above, which was peeled off together with the horizontal alignment film, was then laminated to the exposed surface. The substrate on the vertically aligned liquid crystal cured film side was then peeled off together with the vertical alignment film to obtain a circular polarizing plate 1 consisting of substrate / diffusion prevention layer / photo-alignment film / polarizer / diffusion prevention layer / adhesive layer / horizontally aligned liquid crystal cured film (λ / 4 plate) / adhesive layer / vertically aligned liquid crystal cured film (positive C layer).

[0273] 4. Preparation of a circular polarizer with an adhesive layer (1) The following substrate films with adhesive layers were used as materials for laminate a consisting of a first adhesive layer / first base film. Note that the adhesive layer of substrate film 1 with adhesive layer, substrate film 2 with adhesive layer, and substrate film 3 with adhesive layer differs from one another in adhesive strength. Adhesive-coated base film 1: Base film consisting of polyester release film (19 μm) / adhesive layer (15 μm) / antistatic polyester film (75 μm) Adhesive-coated base film 2: Base film consisting of polyester release film (19 μm) / adhesive layer (15 μm) / antistatic polyester film (38 μm) Adhesive backing film 3: Base film consisting of polyester release film (19 μm) / adhesive layer (15 μm) / antistatic polyester film (38 μm)

[0274] (2) Preparation of a circularly polarizing plate with an adhesive layer (i) Example 1 A substrate film 1 with a pressure-sensitive adhesive layer was used as laminate a. The substrate of circularly polarizing plate 1 was peeled off, and the pressure-sensitive adhesive layer exposed by peeling off the polyester release film of substrate film 1 with a pressure-sensitive adhesive layer was attached to the diffusion prevention layer side. Next, pressure-sensitive adhesive layer 1 with a release film described below was attached to the vertically aligned liquid crystal cured film side, with the pressure-sensitive adhesive layer side exposed by peeling off the light separate film of pressure-sensitive adhesive layer 1 with release film. In this way, a circularly polarizing plate with a pressure-sensitive adhesive layer was produced, consisting of first substrate film (antistatic polyester film) / first pressure-sensitive adhesive layer / diffusion prevention layer / photo-alignment film / polarizer / diffusion prevention layer / tacky adhesive layer / horizontally aligned liquid crystal cured film / adhesive layer / vertically aligned liquid crystal cured film / second pressure-sensitive adhesive layer / second substrate film (release film).

[0275] Adhesive layer with release film 1: A laminated film consisting of a light separation film (38 μm) / adhesive layer (25 μm) / heavy separation film (50 μm) was used. During lamination, the light separation film was peeled off and the heavy separation film was used as the second base film.

[0276] (ii) Example 2 A circularly polarizing plate with a pressure-sensitive adhesive layer was produced in the same manner as in Example 1, except that the following pressure-sensitive adhesive sheet with a release film was used as a laminate consisting of a second pressure-sensitive adhesive layer / second base film.

[0277] ·Adhesive sheet with release film Preparation of the second adhesive layer <Preparation of (Meth)acrylic Polymer A1> 54 parts by mass of n-butyl acrylate, 45 parts by mass of 2-ethylhexyl acrylate, and 1 part by mass of 4-hydroxybutyl acrylate were copolymerized to prepare (meth)acrylic polymer A1. The molecular weight of this (meth)acrylic polymer A1 was measured by the method described below, and the weight average molecular weight (Mw) was 1.2 million.

[0278] Method for measuring weight-average molecular weight of (meth)acrylic polymer The measurement sample was eluted at approximately 100 times the concentration, and after 2 hours, it was analyzed using a 0.45 μm PTFE syringe filter (solvent: tetrahydrofuran). Evaluation equipment: Agilent LC 1100 measurement Evaluation criteria: - Injection volume: 100uL - Flow rate: 1.0mL / min - Column: KF-805 / 804 / 803 - Detector: RID

[0279] <Preparation of composition for forming second pressure-sensitive adhesive layer> 100 parts by mass (solid content equivalent; same below) of the (meth)acrylic polymer A1 obtained in the above process was mixed with 0.15 parts by mass of trimethylolpropane-modified xylylene diisocyanate (manufactured by Soken Chemical Industries, Ltd., product name "TD-75") as a thermal crosslinking agent, and 0.2 parts by mass of 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KBM403") as a silane coupling agent, stirred thoroughly, and diluted with methyl ethyl ketone to obtain a composition for forming a second adhesive layer.

[0280] The obtained composition for forming a second pressure-sensitive adhesive layer was applied to the release-treated surface of a light-weight separator (manufactured by Lintec Corporation, product name "SP-PET752150") using a knife coater. This coating layer was heat-treated at 90°C for 1 minute. Next, the coating layer on the obtained light-weight separator and a heavy-weight separator (manufactured by Lintec Corporation, product name "SP-PET382120", thickness: 38µm) having a release-treated surface were attached so that the release-treated surface of the heavy separator was in contact with the coating layer, and the resulting mixture was aged under conditions of 23°C and 50% RH for 7 days to obtain a pressure-sensitive adhesive sheet having a 25µm-thick pressure-sensitive adhesive layer, i.e., a pressure-sensitive adhesive sheet with a release film having a configuration of light-weight separator / pressure-sensitive adhesive layer (thickness: 25µm) / heavy-weight separator (38µm).

[0281] (iii) Example 3 A circularly polarizing plate with a pressure-sensitive adhesive layer was produced in the same manner as in Example 1, except that the substrate film with a pressure-sensitive adhesive layer 2 was used instead of the substrate film with a pressure-sensitive adhesive layer 1 as the laminate a.

[0282] (iv) Comparative example 1 A circularly polarizing plate with a pressure-sensitive adhesive layer was produced in the same manner as in Example 1, except that, as laminate a, substrate film 2 with a pressure-sensitive adhesive layer was used instead of substrate film 1 with a pressure-sensitive adhesive layer, and as a laminate consisting of a second pressure-sensitive adhesive layer / second substrate film, pressure-sensitive adhesive layer 2 with a release film was used instead of pressure-sensitive adhesive layer 1 with a release film.

[0283] Adhesive layer with release film 2: The structure used was a light separation film (38 μm) / adhesive layer (25 μm) / heavy separation film (38 μm). During lamination, the light separation film was peeled off and the heavy separation film was used as the second base film.

[0284] (v) Comparative example 2 A circularly polarizing plate with a pressure-sensitive adhesive layer was produced in the same manner as in Example 1, except that, as laminate a, substrate film 3 with a pressure-sensitive adhesive layer was used instead of substrate film 1 with a pressure-sensitive adhesive layer, and as a laminate consisting of a second pressure-sensitive adhesive layer / second substrate film, pressure-sensitive adhesive layer 2 with a release film was used instead of pressure-sensitive adhesive layer 1 with a release film. Adhesive layer with release film 3: The structure used was a light separation film (38 μm) / adhesive layer (25 μm) / heavy separation film (70 μm). During lamination, the light separation film was peeled off and the heavy separation film was used as the second base film.

[0285] 5. Physical properties / characteristics evaluation (1) Peel force measurement method The peel strength was measured according to the following method. Each of the pressure-sensitive adhesive layer-attached circular polarizing plates prepared in the Examples and Comparative Examples was cut to a width of 25 mm and a length of approximately 180 mm to obtain a measurement sample. The surface of the substrate film or pressure-sensitive adhesive layer-attached substrate film opposite the substrate film for which the peel strength was to be measured (for example, the release film of pressure-sensitive adhesive layer 1 with release film when measuring peel strength F1 in Example 1, or the pressure-sensitive adhesive layer-attached substrate film 1 when measuring peel strength F2) was peeled was attached to a glass plate via a pressure-sensitive adhesive film. Using a precision universal testing machine "Autograph AGS-50NX" manufactured by Shimadzu Corporation, one end of the measurement sample (a laminate excluding the pressure-sensitive adhesive film to be attached to the glass plate and the glass plate) in the longitudinal direction was grasped and the force required to peel it off in a 180° direction was measured. The measurement was performed at a peel speed of 300 mm / min under conditions of 23±2°C and 50±5% relative humidity. The results are shown in Table 2.

[0286] (2) Air bubble generation Each of the circularly polarizing plates with adhesive layers prepared in the Examples and Comparative Examples was cut to 180 × 120 mm to prepare a measurement sample. The substrate film with adhesive layers (first substrate film and first adhesive layer) of the measurement sample was peeled off by hand, and the generation of bubbles between the second substrate film and the second adhesive layer was visually confirmed. For each of the Examples and Comparative Examples, the test was performed five times, and the number of bubbles was calculated as the average.

[0287] <Evaluation criteria> ◎: No bubbles 〇: 1 bubble ×: Two or more bubbles

[0288] (2) Wrinkles Each of the circularly polarizing plates with adhesive layer prepared in Examples and Comparative Examples was cut to 180 × 120 mm to prepare a measurement sample. The release film (second base film) of the adhesive layer with release film of the measurement sample was peeled off by hand, and the occurrence of wrinkles in the circularly polarizing plate after peeling was visually confirmed. For each of Examples and Comparative Examples, the test was performed five times, and if wrinkles occurred even once, it was evaluated as ×.

[0289] <Evaluation criteria> 〇: No wrinkles ×: Wrinkles occurred

[0290] [Table 2] [Explanation of symbols]

[0291] 1: First base film 2: First adhesive layer 3: Polarizing plate 4:Adhesive layer 5: Retardation layer 6:Second adhesive layer 7: Second base film 11: Circular polarizing plate with adhesive layer 12: Laminated structure 13: Circular polarizer 31: Polarizer 32, 33: Diffusion prevention layer

Claims

1. A pressure-sensitive adhesive layer-attached circular polarizing plate comprising a first substrate film, a first pressure-sensitive adhesive layer, a polarizing plate, a tacky adhesive layer, a retardation layer, a second pressure-sensitive adhesive layer, and a second substrate film in this order, a laminate (laminate a) comprising layers from the first base film to the first PSA layer is peelable from the layer adjacent to the surface of the first PSA layer opposite to the first base film, and the second base film is peelable from the second PSA layer; The total thickness (T1) of the laminate a and the total thickness (T2) of a laminate (laminate b) composed of a layer located between the first PSA layer and the second PSA layer are expressed by the following formula (1): T1 ≧ T2 (1) and The total thickness (T2) of the laminate b and the thickness (T3) of the second base film are expressed by the following formula (2): T3≧T2 (2) Fulfilling The peel force (F1) when peeling the laminate a from the pressure-sensitive adhesive layer-attached circularly polarizing plate and the peel force (F2) when peeling the second base film from the pressure-sensitive adhesive layer-attached circularly polarizing plate are expressed by the following formula (3): F1 < F2 (3) and 1gf / inch≦F2-F1≦10.6gf / inch Fulfilling A circularly polarizing plate with an adhesive layer, having F2 of 4.5 gf / inch or more and 25 gf / inch or less.

2. The pressure-sensitive adhesive layer-attached circular polarizing plate according to claim 1, wherein a peel force (F1) when peeling the laminate a from the pressure-sensitive adhesive layer-attached circular polarizing plate is 4 gf / inch or more.

3. The pressure-sensitive adhesive layer-attached circular polarizing plate according to claim 1 , wherein the polarizing plate comprises a polarizer and a diffusion prevention layer located on the first pressure-sensitive adhesive layer side of the polarizer.

4. 4. The pressure-sensitive adhesive layer-attached circularly polarizing plate according to claim 1, wherein the laminate b has a total thickness of 20 μm or less.

5. 5. The pressure-sensitive adhesive layer-attached circularly polarizing plate according to claim 1, wherein the laminate a has a total thickness of 30 to 120 μm.

6. The pressure-sensitive adhesive layer-attached circular polarizing plate according to claim 3 , wherein the diffusion prevention layer has a thickness of 5 μm or less.

7. The pressure-sensitive adhesive layer-attached circular polarizer according to any one of claims 1 to 6, wherein the polarizing plate comprises a polarizer that is a liquid crystal cured film of a polymerizable liquid crystal composition containing a polymerizable liquid crystal compound exhibiting a smectic liquid crystal phase and a dichroic dye.

8. 8. The pressure-sensitive adhesive layer-attached circular polarizer according to claim 1, wherein the retardation layer is a horizontally aligned liquid crystal cured film obtained by curing a polymerizable liquid crystal compound in a state where the polymerizable liquid crystal compound is aligned horizontally relative to the surface of the substrate.

9. A step of peeling off the laminate a from the pressure-sensitive adhesive layer-attached circular polarizing plate according to any one of claims 1 to 8; and a step of laminating an adherend via a pressure-sensitive adhesive layer to the surface adjacent to the laminate a peeled off in the peeling step A method for producing an optical laminate, comprising:

10. The method for producing an optical laminate according to claim 9 , further comprising a step of peeling off the second base film as a step downstream of the step of peeling off the laminate a.

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