CN112119332B

CN112119332B - Adhesive layer-attached single-sided protective polarizing film, image display device, and continuous production method therefor

Info

Publication number: CN112119332B
Application number: CN201980032036.9A
Authority: CN
Inventors: 藤田雅人; 森本有; 江原卓; 外山雄祐
Original assignee: Nitto Denko Corp
Current assignee: Nitto Denko Corp
Priority date: 2018-06-26
Filing date: 2019-05-28
Publication date: 2022-11-08
Anticipated expiration: 2039-05-28
Also published as: WO2020003857A1; KR20210023976A; CN112119332A; JP7142497B2; TW202000823A; TWI812726B; JP2020003576A

Abstract

The purpose of the present invention is to provide a single-sided protective polarizing film with an adhesive layer, which has excellent initial reworkability, durability and conductive stability in a high-temperature and/or high-humidity environment, and is less likely to peel off from a glass substrate or the like even when exposed to an environment in which dew condensation occurs. The one-sided protective polarizing film with an adhesive layer of the present invention comprises a one-sided protective polarizing film having a protective film only on one side of a polarizer, and an adhesive layer on the polarizer side of the one-sided protective polarizing film directly or via a coating layer, wherein the adhesive layer comprises a (meth) acrylic polymer as a base polymer, has a weight change rate of 1.1% or more, and has an adhesive force P before immersion in water ₀ 10N/25mm or less, and an adhesive force P after immersion in water for 2 hours ₁ Is 1.6N/25mm or more.

Description

Single-sided protective polarizing film with adhesive layer, image display device and continuous manufacturing method thereof

Technical Field

The present invention relates to a one-sided protective polarizing film having a one-sided protective polarizing film in which a protective film is provided only on one side of a polarizer and an adhesive layer-attached one-sided protective polarizing film. The pressure-sensitive adhesive layer-attached one-side protective polarizing film may be used alone to form an image display device such as a Liquid Crystal Display (LCD) or an organic EL display, or may be used as an optical film in which the pressure-sensitive adhesive layer-attached one-side protective polarizing film is laminated to form an image display device such as a Liquid Crystal Display (LCD) or an organic EL display.

Background

In a liquid crystal display device, it is essential to dispose polarizing films on both sides of a glass substrate forming a surface of a liquid crystal panel in view of an image forming method. As the polarizing film, a polarizing film obtained by laminating a protective film on one surface or both surfaces of a polarizer made of a dichroic material such as a polyvinyl alcohol film and iodine with a polyvinyl alcohol adhesive or the like is generally used.

When the polarizing film is bonded to a liquid crystal cell or the like, an adhesive is generally used. In addition, since there are advantages in that the polarizing film can be fixed instantaneously, a drying process for fixing the polarizing film is not required, and the like, the adhesive may be previously provided on one surface of the polarizing film in the form of an adhesive layer. That is, the polarizing film with the adhesive layer may be used for lamination of the polarizing film.

In addition, there is a problem that cracks (through cracks) are likely to occur in the entire absorption axis direction of the polarizer due to a change in shrinkage stress of the polarizer in a severe environment of thermal shock (for example, a thermal shock test in which temperature conditions of-30 ℃ and 80 ℃ are repeated, a test at a high temperature of 100 ℃) in a polarizing film and an adhesive layer-attached polarizing film. That is, the polarizing films and the adhesive layer-equipped polarizing films have insufficient durability against thermal shock in the above severe environments. In particular, the above-described durability against thermal shock is insufficient for a single-sided protective polarizing film with an adhesive layer using a single-sided protective polarizing film provided with a protective film only on one side of a polarizer from the viewpoint of thinning. In addition, the through-crack induced by the thermal shock described above is more easily generated in the case where the size of the polarizing film becomes large.

For example, in order to impart high durability in a high-temperature environment, it has been proposed to use, as the pressure-sensitive adhesive layer of the pressure-sensitive adhesive layer-attached one-sided protective polarizing film, a pressure-sensitive adhesive layer having a storage modulus at 23 ℃ of 0.2 to 10MPa and a thickness of 2 μm or more and less than 25 μm (patent document 1). In order to provide excellent durability even in a high-temperature environment, it has been proposed to use, as the pressure-sensitive adhesive layer, an adhesive layer exhibiting a storage modulus of 0.15 to 1MPa in a temperature range of 23 to 80 ℃ in a polarizing plate in which a pressure-sensitive adhesive layer is provided on one surface of a polarizer and a protective layer made of a transparent resin film is provided on the other surface of the polarizer (patent document 2). In order to suppress the occurrence of the through crack, it has been proposed to use, as the pressure-sensitive adhesive layer of the one-side protective polarizing film with a pressure-sensitive adhesive layer, a pressure-sensitive adhesive layer in which the shrinkage force in the direction perpendicular to the absorption axis of the polarizer is controlled to be small and the storage modulus of the pressure-sensitive adhesive layer at 23 ℃ is 0.20MPa or more (patent document 3). Further, a thin polarizer is also used, and for example, a thin polarizer which exhibits high orientation by controlling optical characteristics such as a monomer transmittance and a polarization degree has been proposed (patent document 4).

However, in patent document 1, even if the durability is satisfied, the thickness of the polarizer is as high as 25 μm, and thus the occurrence of through cracks due to the shrinkage stress of the polarizer cannot be prevented. Further, patent documents 1 to 3 have a problem of improving the durability of the one-side protective polarizing film with an adhesive layer, and thus boric acid is used in a polarizer in a relatively large amount. It is also known that: when the amount of boric acid contained in the polarizer is more than a specific value, crosslinking is promoted by boric acid during heating, and the shrinkage stress of the polarizer increases, which is not preferable from the viewpoint of suppressing the occurrence of through cracks. That is, in patent documents 1 to 3, although the occurrence of through cracks can be prevented to some extent by controlling the storage modulus of the pressure-sensitive adhesive layer, it cannot be said that the occurrence of through cracks can be sufficiently suppressed.

On the other hand, the polarizer is also thinned. In the case of a polarizer used in a one-side protective polarizing film with a thin adhesive layer, the change in the shrinkage stress of the polarizer is small. It is thus understood that if a polarizer having a reduced thickness is produced, the occurrence of the through crack can be suppressed.

However, it is known that, in the pressure-sensitive adhesive layer-attached one-side protective polarizing film in which the occurrence of the through crack is suppressed, when the polarizer is thinned while controlling the optical characteristics as in patent document 4 (for example, when the thickness is set to 12 μm or less), when a mechanical impact is applied to the pressure-sensitive adhesive layer-attached one-side protective polarizing film (including when a load by a convex fold is applied to the polarizer side), an extremely fine slit (hereinafter, also referred to as a nano slit) is locally generated in the absorption axis direction of the polarizer. It is also known that the generation of the nano-slit is not related to the size of the polarizing film. It is also known that the above-described nano-slit does not occur when a double-sided protective polarizing film having protective films on both sides of a polarizer is used. In addition, in the case where the through crack is generated in the polarizer, the stress around the through crack is released, and therefore the through crack is not generated adjacently, but it is known that the nano slit is generated not only singly but also adjacently. It is also known that through cracks have progressiveness that extends in the absorption axis direction of the polarizer in which the cracks have occurred, but the nano slits do not have the progressiveness. It is thus understood that the nano-slit is a new problem that occurs when the polarizer is thinned and the optical characteristics are controlled to a predetermined range in a single-sided protective polarizing film in which the occurrence of through-cracks is suppressed, and is a problem caused by a phenomenon different from the conventionally known through-cracks.

In addition, the nano-slit is extremely fine and thus cannot be detected in a normal environment. Therefore, even if a nano-slit is generated in the polarizer, it is difficult to confirm a defect of the one-side protective polarizing film with an adhesive layer from light leakage only by simple observation. That is, in general, a single-sided protective polarizing film is formed into a long film shape, and defect inspection is performed by automatic optical inspection, but it is difficult to detect a nano-slit as a defect by the defect inspection. It is also known that the aforementioned defects caused by the nano-slits can be detected by the expansion of the nano-slits in the width direction (for example, the presence or absence of the aforementioned light leakage) when the one-side protective polarizing film with an adhesive layer is bonded to a glass substrate or the like of an image display panel and placed in a heated environment.

Therefore, it is expected that not only through-crack but also defects due to the nano-slits are suppressed in the single-sided protective polarizing film with an adhesive layer using a thin polarizer. Further, since the one-side protective polarizing film with an adhesive layer is thinner than a polarizing film having a two-side protective structure with protective films on both sides, the polarizing film is likely to be bent or broken during handling.

In order to suppress the defects caused by the nano-slits, a technique has been proposed in which a transparent layer (coating layer) is provided between a polarizer of a single-sided protective polarizing film with an adhesive layer and the adhesive layer (patent document 5). By providing a transparent layer, the polarizing film is less likely to be deflected when external stress is applied to the polarizing film, and therefore, the formation of nano-slits can be suppressed.

In addition, when the one-side protective polarizing film with a pressure-sensitive adhesive layer is attached to a liquid crystal cell in the production of a liquid crystal display device, a release film is peeled from the pressure-sensitive adhesive layer of the one-side protective polarizing film with a pressure-sensitive adhesive layer, but static electricity is generated by the peeling of the release film. The static electricity thus generated affects the alignment of liquid crystals in the liquid crystal display device, and causes a problem. In addition, when a liquid crystal display device is used, display unevenness due to static electricity may occur. The generation of static electricity can be carried out, for example, by using a polarizing filmThe antistatic layer is formed on the outer surface to inhibit the static electricity, but the effect is small, and the static electricity cannot be prevented fundamentally. Therefore, in order to suppress the generation of static electricity at the fundamental site thereof, it is required to impart an antistatic function to the adhesive layer. As a method for imparting an antistatic function to the pressure-sensitive adhesive layer, for example, a method of blending an ionic compound into the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer has been proposed (patent documents 6 to 8). In detail, patent document 6 proposes an adhesive composition for an optical film containing an alkali metal salt and/or an organic cation-anion salt. Patent document 7 proposes a polarizing film with an adhesive layer containing an adhesive layer as a raw material for the adhesive layer

-anionic salts and alkali metal salts. Patent document 8 proposes an adhesive composition containing an alkali metal salt as a material for an adhesive layer of an adhesive-type polarizing plate.

Further, the pressure-sensitive adhesive layer of the one-side protective polarizing film with a pressure-sensitive adhesive layer is required to have high durability, and for example, in a durability test using heating, humidification, or the like, which is generally performed as an environmental promotion test, it is required that defects such as peeling or lifting of the pressure-sensitive adhesive layer do not occur.

Various studies have been made on such an adhesive composition for optical use, and an adhesive composition that does not peel or foam even when placed under high humidity and heat conditions after an optical film is bonded has been proposed (patent document 9).

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2010-44211

Patent document 2: japanese patent laid-open No. 2008-197309

Patent document 3: japanese patent laid-open publication No. 2013-72951

Patent document 4: japanese patent No. 4751481 specification

Patent document 5: japanese patent No. 6077618

Patent document 6: japanese patent laid-open publication No. 2015-199942

Patent document 7: japanese laid-open patent publication No. 2014-48497

Patent document 8: japanese laid-open patent publication No. 2012-247574

Patent document 9: japanese laid-open patent publication No. 2009-242767

Disclosure of Invention

Problems to be solved by the invention

However, if a glass substrate with a polarizing film, such as a glass substrate on which a liquid crystal panel is formed, to which a conventional one-side protective polarizing film with an adhesive layer is bonded is placed in an environment where dew condensation occurs, there is a problem that peeling easily occurs at the interface between the glass substrate and the adhesive layer.

In addition, when a single-sided protective polarizing film with an adhesive layer is bonded to a glass substrate or the like forming the surface of a liquid crystal panel, if a bonding error occurs due to the inclusion of foreign matter or air bubbles, the polarizing film needs to be peeled off from the glass substrate or the like. The one-sided protective polarizing film with an adhesive layer using a thin polarizer has a very small thickness as a whole because the polarizer is thin and the protective film is provided only on one surface of the polarizer. Therefore, the pressure-sensitive adhesive layer-attached one-side protective polarizing film using a conventional thin polarizer has a problem that it is easily broken when it is peeled off from a glass substrate or the like. Therefore, the pressure-sensitive adhesive layer is also required to have reworkability that does not cause a problem when the polarizing film is peeled from a glass substrate or the like.

The purpose of the present invention is to provide a pressure-sensitive adhesive layer-attached single-sided protective polarizing film that has excellent initial reworkability, durability in high-temperature and/or high-humidity environments, and electrical conductivity stability, and that is less likely to peel off from a glass substrate or the like even when exposed to an environment in which condensation has occurred. In addition to the above-described effects, an object of the present invention is to provide a single-sided protective polarizing film with an adhesive layer, which can suppress defects caused by a nano-slit even when a coating layer is not provided between a polarizer and the adhesive layer.

Another object of the present invention is to provide an image display device having the pressure-sensitive adhesive layer-attached single-sided protective polarizing film, and a continuous production method thereof.

Means for solving the problems

As a result of intensive studies, the present inventors have found that the above-mentioned problems can be solved by the following pressure-sensitive adhesive layer-attached one-side protective polarizing film and the like, and have completed the present invention.

That is, the present invention relates to a one-sided protective polarizing film with an adhesive layer, which has a one-sided protective polarizing film having a protective film only on one side of a polarizer and has an adhesive layer directly or via a coating layer on the polarizer side of the one-sided protective polarizing film,

the adhesive layer contains a (meth) acrylic polymer as a base polymer,

the weight change rate of the pressure-sensitive adhesive layer calculated by the following formula (1) is 1.1% or more,

adhesive force P of the adhesive layer under the following conditions ₀ Is 10N/25mm or less and has an adhesive force P under the following conditions ₁ Is more than 1.6N/25mm,

weight change rate (%) = { (W) ₁ －W ₀ )/W ₀ }×100 (1)

W ₀ = weight of adhesive layer after drying the above adhesive layer at 23 ℃ for 2 hours,

W ₁ (ii) the weight of the pressure-sensitive adhesive layer after leaving the pressure-sensitive adhesive layer after drying at 23 ℃, 55% RH for 5 hours, further at 60 ℃, 95% RH for 5 hours,

adhesive force P ₀ : the pressure-sensitive adhesive layer of the one-sided protective polarizing film with a pressure-sensitive adhesive layer was adhered to the surface of an alkali-free glass, autoclave treatment was carried out for 15 minutes under conditions of 50 ℃ and 0.5atm, and then the pressure-sensitive adhesive layer was peeled from the surface of the alkali-free glass at a peeling temperature of 23 ℃, a peeling speed of 300mm/min and a peeling angle of 90 degrees,

adhesive force P ₁ : the pressure-sensitive adhesive layer of the above-mentioned one-side protective polarizing film with a pressure-sensitive adhesive layer was adhered to the surface of an alkali-free glass, and then autoclave treatment was carried out at 50 ℃ and 0.5atm for 15 minutes to obtain a laminateAnd (3) the adhesive strength when the pressure-sensitive adhesive layer is peeled from the surface of the alkali-free glass under the conditions of a peeling temperature of 23 ℃, a peeling speed of 300mm/min and a peeling angle of 90 degrees after the laminate is taken out from the water after the laminate is immersed in water at 23 ℃ for 2 hours.

In order to impart durability and conductive stability to the pressure-sensitive adhesive layer provided on the polarizer side of the single-sided protective polarizing film, it is preferable to introduce a polar monomer into the pressure-sensitive adhesive layer through a (meth) acrylic polymer which is a base polymer of the pressure-sensitive adhesive layer. However, the hydrophilicity of the (meth) acrylic polymer into which the polar monomer is introduced by copolymerization becomes high. Therefore, it is considered that the pressure-sensitive adhesive layer containing the (meth) acrylic polymer is likely to absorb water when exposed to an environment where dew condensation occurs, and the adhesive strength is likely to be lowered, and thus the pressure-sensitive adhesive layer is likely to be peeled from a glass substrate or the like. The present inventors have conducted extensive studies on the relationship between the physical properties of the pressure-sensitive adhesive layer provided on the polarizer side of the one-side protective polarizing film, the initial removability, and the peeling from the glass substrate, etc., and as a result, have found that by adjusting the weight change rate of the pressure-sensitive adhesive layer before and after humidification, and the adhesive strength under specific conditions to specific ranges, it is possible to obtain a one-side protective polarizing film with a pressure-sensitive adhesive layer which can maintain the initial removability, the durability in a high-temperature and/or high-humidity environment, and the conductive stability at high levels, and which is less likely to peel from the glass substrate, etc., even when exposed to an environment in which dew condensation occurs.

The (meth) acrylic polymer preferably contains, as monomer units:

(meth) acrylic acid alkyl ester (A) having a homopolymer glass transition temperature of less than 0 ℃ in an amount of 50% by weight or more, and

0.1 to 20 wt% of at least one high Tg monomer (B) selected from an alkyl (meth) acrylate (B1) having a homopolymer glass transition temperature of 0 ℃ or higher and a (meth) acryloyl group-containing monomer (B2) having a homopolymer glass transition temperature of 0 ℃ or higher and a heterocycle.

Further, it is preferable that the (meth) acrylic polymer contains a polar monomer other than the (meth) acryloyl group-containing monomer (b 2), and the polar monomer is at least one selected from the group consisting of a nitrogen-containing monomer, a carboxyl group-containing monomer, a hydroxyl group-containing monomer, and an aromatic group-containing monomer.

Preferably, the nitrogen-containing monomer is a vinyl monomer having a lactam ring. Preferably, the vinyl monomer having a lactam ring is a vinylpyrrolidone monomer. Further, it is preferable that the vinylpyrrolidone monomer is N-vinylpyrrolidone.

In the (meth) acrylic polymer, the nitrogen-containing monomer is preferably contained in an amount of 0.1 to 5% by weight, the carboxyl group-containing monomer is preferably contained in an amount of 0.01 to 3% by weight, the hydroxyl group-containing monomer is preferably contained in an amount of 0.01 to 1% by weight, and the aromatic group-containing monomer is preferably contained in an amount of 1 to 20% by weight, as a monomer unit.

The weight average molecular weight of the (meth) acrylic polymer is preferably 150 ten thousand or less.

Preferably, the pressure-sensitive adhesive layer contains a silane coupling agent having at least 1 functional group selected from the group consisting of an epoxy group, an isocyanate group, a mercapto group, an acid anhydride group and an amino group. The silane coupling agent is preferably contained in an amount of 0.01 to 3 parts by weight based on 100 parts by weight of the (meth) acrylic polymer.

The thickness of the polarizer is preferably 12 μm or less,

Further, it is preferable that the polarizer contains a polyvinyl alcohol resin, and is configured such that optical characteristics represented by a monomer transmittance T and a degree of polarization P satisfy the following conditions:

P＞－(10 ^0.929T-42.4 -1) x 100 (wherein T < 42.3), or

P is more than or equal to 99.9 (wherein, T is more than or equal to 42.3).

Further, the polarizer preferably contains boric acid in an amount of 25 wt% or less based on the total amount of the polarizer.

A separator may be provided on the adhesive layer of the above-described one-side protective polarizing film with an adhesive layer. The single-sided protective polarizing film with an adhesive layer provided with a separator may be used as a roll.

In addition, the present invention relates to an image display device having the above-described one-side protective polarizing film with an adhesive layer.

Further, the present invention relates to a method for continuously manufacturing an image display device, the method including the steps of: the pressure-sensitive adhesive layer-attached one-side protective polarizing film continuously fed from the roll of pressure-sensitive adhesive layer-attached one-side protective polarizing film and conveyed by the separator is continuously bonded to the surface of the image display panel via the pressure-sensitive adhesive layer.

ADVANTAGEOUS EFFECTS OF INVENTION

The pressure-sensitive adhesive layer-equipped one-side protective polarizing film of the present invention has excellent initial reworkability, and therefore, even when a thin polarizer is used, the polarizing film can be peeled from a glass substrate or the like without breaking. Further, the pressure-sensitive adhesive layer-attached single-sided protective polarizing film of the present invention is excellent in durability in a high-temperature and/or high-humidity environment, and therefore, is less likely to cause troubles such as peeling and lifting of the pressure-sensitive adhesive layer. In addition, the one-side protective polarizing film with an adhesive layer of the present invention is excellent in conductive stability in a humidified environment, and therefore, the polarizer is less likely to be deteriorated and the polarizer is less likely to be discolored. In addition, the pressure-sensitive adhesive layer-equipped one-side protective polarizing film of the present invention is less likely to have a reduced adhesive force and is less likely to be peeled off from a glass substrate or the like even when exposed to an environment where dew condensation occurs. Further, since the pressure-sensitive adhesive layer-equipped single-sided protective polarizing film of the present invention has the pressure-sensitive adhesive layer, the occurrence of the nano-slit can be effectively suppressed even without providing a coating layer.

Drawings

FIG. 1 is an example of a schematic cross-sectional view of a single-sided protective polarizing film with an adhesive layer according to the present invention.

Fig. 2 is an example of a schematic diagram for comparing a nanoslit and a through crack generated by a polarizer.

Fig. 3 is a schematic diagram illustrating evaluation items relating to the nanoslit of the examples and comparative examples.

Fig. 4 is an example of a photograph showing cracks initiated by the nano slits in the evaluation of the examples and comparative examples.

Fig. 5 is an example of a schematic cross-sectional view of a continuous manufacturing system for an image display device.

Description of the symbols

1. Polarizer

2. Protective film

3. Adhesive layer and the like

4. Adhesive layer

5.5 a, 5b diaphragm

6. 6a, 6b surface protective film

10. Single-sided protective polarizing films

11. Single-sided protective polarizing film with adhesive layer

20a, 20b Single-sided protective polarizing film roll with adhesive layer

21a, 21b Single-sided protective polarizing film with adhesive layer (with surface protective film)

100. Continuous manufacturing system for image display device

101a, 101b polarizing film supply unit

151a, 151b continuous discharge portion

152a, 152b cutting part

153a, 153b peeling part

154a, 154b winding part

201a, 201b bonding portion

300. Arrangement replacement part

P image display panel

Conveying part of X image display panel

Detailed Description

Hereinafter, the pressure-sensitive adhesive layer-equipped single-sided protective polarizing film of the present invention will be described with reference to fig. 1. The pressure-sensitive adhesive layer-equipped single-sided protective polarizing film 11 of the present invention includes, for example, a single-sided protective polarizing film 10 and a pressure-sensitive adhesive layer 4. The adhesive layer 4 is an adhesive layer of the present invention. As shown in fig. 1, the one-side protective polarizing film 10 has a protective film 2 only on one side of a polarizer 1. The polarizer 1 and the protective film 2 are laminated via an adhesive layer 3 (and an interlayer such as an adhesive layer and an undercoat layer). Although not shown, the one-side protective polarizing film 10 may be formed by providing an easy-adhesion layer on the protective film 2, or by performing activation treatment on the protective film 2 and then laminating the easy-adhesion layer and the adhesive layer. Further, although not shown, a plurality of protective films 2 may be provided. The plurality of protective films 2 may be laminated via an adhesive layer 3 (and an interlayer such as an adhesive layer or an undercoat layer).

As shown in fig. 1, the pressure-sensitive adhesive layer 4 of the pressure-sensitive adhesive layer-attached one-side protective polarizing film 11 of the present invention is provided on the polarizer 1 side of the one-side protective polarizing film 10. Further, although not shown, an application layer may be provided between the polarizer 1 and the adhesive layer 4. The coating layer is not particularly limited, and a known transparent layer described in, for example, japanese patent No. 6077618 can be used. The pressure-sensitive adhesive layer-equipped one-side protective polarizing film 11 of the present invention may be provided with a separator 5 on the pressure-sensitive adhesive layer 4 and a surface protective film 6 on the opposite side. In the adhesive layer-attached one-side protective polarizing film 11 of fig. 1, a case where both the separator 5 and the surface protective film 6 are provided is shown. The one-side protective polarizing film with an adhesive layer 11 having at least the separator 5 (further, the polarizing film with the surface protective film 6) may be used in the form of a roll, and as described later, for example, a mode (hereinafter, also referred to as a "roll-to-panel mode") in which the one-side protective polarizing film with an adhesive layer 11 continuously fed out from the roll and conveyed by the separator 5 is applied to the surface of the image display panel via the adhesive layer 4 is advantageous in the typical case of referring to japanese patent No. 4406043. From the viewpoints of suppressing the warping of the display panel after bonding, suppressing the generation of nano slits, and the like, the pressure-sensitive adhesive layer-attached single-side protective polarizing film described in fig. 1 is preferably used.

Fig. 2 is a schematic diagram comparing a nanoslit a and a through crack b generated at a polarizer. Fig. 2 (a) shows a nanoslit a produced on the polarizer 1, and fig. 2 (B) shows a through crack B produced on the polarizer 1. The nano-slits a are generated by mechanical impact, and the nano-slits a locally generated in the absorption axis direction of the polarizer 1 cannot be confirmed at the time of initial generation, but can be confirmed based on the expansion in the width direction in a thermal environment (for example, 80 ℃ or 60 ℃,90% rh). On the other hand, the nanoslit a is not considered to have a progressivity extending in the absorption axis direction of the polarizer. The generation of the nano-slit a is not related to the size of the polarizing film. The nano-slits a are not only individually generated but also adjacently generated in some cases. On the other hand, the through crack b is generated by thermal shock (e.g., thermal shock test). The through crack has a progressivity extending in the absorption axis direction of the polarizer in which the crack has occurred. When the through crack b is generated, the stress around the through crack b is released, and thus the through crack is not generated adjacently.

< polarizer >

In the present invention, the thickness of the polarizer is preferably 12 μm or less, more preferably 10 μm or less, further preferably 8 μm or less, further preferably 7 μm or less, and particularly preferably 6 μm or less, from the viewpoint of reduction in thickness and suppression of occurrence of through cracks. On the other hand, the thickness of the polarizer is preferably 1 μm or more. Such a thin polarizer has excellent durability against thermal shock because of small thickness unevenness, excellent visibility, and small dimensional change.

As the polarizer, a polarizer using a polyvinyl alcohol resin can be used. Examples of the polarizer include films obtained by uniaxially stretching hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene-vinyl acetate copolymer partially saponified films, and polyene oriented films such as polyvinyl alcohol dehydrated products and polyvinyl chloride desalted products, and the like. Among these, a polarizer made of a dichroic material such as a polyvinyl alcohol film and iodine is preferable.

The polarizer obtained by uniaxially stretching a polyvinyl alcohol film dyed with iodine can be produced by, for example, dyeing polyvinyl alcohol by immersing it in an aqueous iodine solution and stretching it to 3 to 7 times the original length. If necessary, boric acid, zinc sulfate, zinc chloride, or the like may be contained, and the film may be immersed in an aqueous solution of potassium iodide or the like. Further, the polyvinyl alcohol film may be immersed in water and washed with water before dyeing, if necessary. By washing the polyvinyl alcohol film with water, dirt and an anti-blocking agent on the surface of the polyvinyl alcohol film can be washed off, and the polyvinyl alcohol film can be swollen to prevent unevenness such as uneven dyeing. The stretching may be performed after the dyeing with iodine, or may be performed while dyeing, or may be performed after the stretching with iodine. Stretching may also be carried out in an aqueous solution or water bath of boric acid, potassium iodide, or the like.

The polarizer preferably contains boric acid from the viewpoint of tensile stability and optical durability. In addition, from the viewpoint of suppressing the occurrence of through cracks and nano slits and suppressing the expansion, the content of boric acid contained in the polarizer is preferably 25 wt% or less, more preferably 20 wt% or less, further preferably 18 wt% or less, and further preferably 16 wt% or less with respect to the total amount of the polarizer. When the boric acid content in the polarizer exceeds 25 wt%, even when the thickness of the polarizer is reduced (for example, 12 μm or less), the shrinkage stress of the polarizer is likely to increase and through cracks are likely to occur, which is not preferable. On the other hand, the boric acid content relative to the total amount of the polarizers is preferably 10% by weight or more, more preferably 12% by weight or more, from the viewpoint of the tensile stability and optical durability of the polarizers.

Typical examples of the thin polarizers include thin polarizers described in japanese patent No. 4751486, japanese patent No. 4751481, japanese patent No. 4815544, japanese patent No. 5048120, japanese patent No. 5587517, international publication No. 2014/077599, and international publication No. 2014/077636, and thin polarizers obtained by the production methods described in these documents.

Preferably, the polarizer is configured such that optical characteristics represented by a single transmittance T and a polarization degree P satisfy the following conditions:

P＞－(10 ^0.929T-42.4 -1) x 100 (wherein T < 42.3), or

P is more than or equal to 99.9 (wherein, T is more than or equal to 42.3).

Mainly, a polarizer configured to satisfy the above conditions is usedThe performance required for a display for a liquid crystal television, which is a large-sized display element, is being improved. Specifically, the contrast is 1000 or more and the maximum luminance is 500cd/m ² As described above. For another use, for example, the adhesive sheet can be bonded to the visible side of an organic EL display device.

On the other hand, since the polarizer configured to satisfy the above conditions exhibits high orientation of a polymer (e.g., polyvinyl alcohol-based polymer) constituting the polarizer, the polarizer is bonded to a thin polarizer (e.g., 12 μm or less in thickness), and the tensile breaking stress in a direction perpendicular to the absorption axis direction of the polarizer is significantly reduced. As a result, for example, when the polarizing film is exposed to a mechanical impact exceeding the tensile breaking stress in the production process thereof, the nano-slit is highly likely to be generated in the absorption axis direction of the polarizer. Therefore, the present invention is particularly suitable for use in a single-sided protective polarizing film using the polarizer (or a single-sided protective polarizing film with an adhesive layer using the polarizer).

As the thin polarizer, in a production method including a step of stretching in a state of a laminate and a step of dyeing, from the viewpoint of being capable of stretching to a high magnification to improve polarization performance, a thin polarizer obtained by a production method including a step of stretching in an aqueous boric acid solution as described in japanese patent No. 4751486, japanese patent No. 4751481, and japanese patent No. 4815544 is preferably used, and particularly a thin polarizer obtained by a production method including a step of auxiliarily stretching in a gas atmosphere before stretching in an aqueous boric acid solution as described in japanese patent No. 4751481, and japanese patent No. 4815544 is preferable. These thin polarizers can be obtained by a production method including a step of stretching a polyvinyl alcohol resin (hereinafter, also referred to as PVA-based resin) layer and a resin base material for stretching in a laminated state, and a step of dyeing. With this production method, even if the PVA-based resin layer is thin, it can be stretched without causing problems such as breakage due to stretching by being supported by the stretching resin base material.

< protective film >

The material constituting the protective film is preferably excellent in transparency, mechanical strength, thermal stability, moisture barrier properties, isotropy, and the like. Examples thereof include: polyester polymers such AS polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such AS cellulose diacetate and cellulose triacetate, acrylic polymers such AS polymethyl methacrylate, styrene polymers such AS polystyrene and acrylonitrile-styrene copolymers (AS resins), and polycarbonate polymers. Examples of the polymer forming the protective film include: examples of the polymer include polyolefin polymers such as polyethylene, polypropylene, cyclic polyolefins having a norbornene structure, and ethylene-propylene copolymers, amide polymers such as vinyl chloride polymers, nylon and aromatic polyamides, imide polymers, sulfone polymers, polyethersulfone polymers, polyetheretherketone polymers, polyphenylene sulfide polymers, vinyl alcohol polymers, vinylidene chloride polymers, vinyl butyral polymers, aromatic ester polymers, polyoxymethylene polymers, epoxy polymers, and blends of the above polymers.

The protective film may contain 1 or more kinds of any appropriate additives. Examples of additives include: ultraviolet absorbers, antioxidants, lubricants, plasticizers, mold release agents, anti-coloring agents, flame retardants, nucleating agents, antistatic agents, pigments, colorants, and the like. The content of the thermoplastic resin in the protective film is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, even more preferably 60 to 98% by weight, and particularly preferably 70 to 97% by weight. When the content of the thermoplastic resin in the protective film is 50 wt% or less, there is a possibility that high transparency inherent in the thermoplastic resin cannot be sufficiently exhibited.

As the protective film, a retardation film, a brightness enhancement film, a diffusion film, or the like can be used. Examples of the retardation film include a retardation film having a front retardation of 40nm or more and/or a thickness direction retardation of 80nm or more. The front retardation is usually controlled to be in the range of 40 to 200nm, and the thickness direction retardation is usually controlled to be in the range of 80 to 300 nm. When the retardation film is used as the protective film, the retardation film also functions as a polarizer protective film, and therefore, the thickness can be reduced.

Examples of the retardation film include a birefringent film obtained by subjecting a thermoplastic resin film to a uniaxial stretching treatment or a biaxial stretching treatment. The temperature, stretch ratio, and the like of the above stretching may be appropriately set depending on the retardation value, the material, and the thickness of the film.

The thickness of the protective film may be appropriately determined, but is usually about 1 to 500 μm in view of strength, workability such as handling, and thin layer property. Preferably 1 to 300 μm, more preferably 5 to 200 μm, further preferably 5 to 150 μm, and particularly preferably 5 to 80 μm.

A functional layer such as a hard coat layer, an antireflection layer, an adhesion prevention layer, a diffusion layer, or an antiglare layer may be provided on the surface of the protective film that is not bonded to the polarizer. The functional layers such as the hard coat layer, the antireflection layer, the adhesion prevention layer, the diffusion layer, and the antiglare layer may be provided as the protective film itself, or may be provided separately from the protective film.

< interlayer >

The protective film and the polarizer may be laminated with an adhesive layer, an undercoat layer (primer layer), or the like interposed therebetween. In this case, it is preferable to stack both layers without an air gap by using an interlayer. The protective film and the polarizer are preferably laminated with an adhesive layer interposed therebetween.

The adhesive layer may be formed using an adhesive. The type of the adhesive is not particularly limited, and various adhesives can be used. The adhesive layer is not particularly limited as long as it is an optically transparent layer, and various types of adhesives such as water-based adhesives, solvent-based adhesives, hot-melt adhesives, and active energy ray-curable adhesives can be used as the adhesive, but water-based adhesives or active energy ray-curable adhesives are preferable.

Examples of the aqueous adhesive include isocyanate adhesives, polyvinyl alcohol adhesives, gelatin adhesives, vinyl latexes, and aqueous polyesters. The aqueous adhesive is generally used in the form of an adhesive formed from an aqueous solution, and usually contains 0.5 to 60% by weight of a solid content.

The active energy ray-curable adhesive is an adhesive that is cured by an active energy ray such as an electron beam or ultraviolet ray (radical-curable type or cation-curable type), and can be used in the form of, for example, an electron beam-curable type or an ultraviolet-curable type. As the active energy ray-curable adhesive, for example, a radical photo-curable adhesive can be used. When a radical photo-curable active energy ray-curable adhesive is used as the ultraviolet-curable adhesive, the adhesive contains a radical polymerizable compound and a photopolymerization initiator.

The application method of the adhesive can be appropriately selected depending on the viscosity of the adhesive and the target thickness. Examples of the coating method include: reverse coaters, gravure coaters (direct, reverse, or offset), bar reverse coaters, roll coaters, die coaters, wire wound bar coaters, and the like. The coating may be performed by a dipping method or the like.

When an aqueous adhesive or the like is used for the application of the adhesive, the adhesive layer to be finally formed is preferably made to have a thickness of 30 to 300 nm. The thickness of the adhesive layer is more preferably 60 to 250nm. On the other hand, when an active energy ray-curable adhesive is used, the thickness of the adhesive layer is preferably 0.1 to 200 μm. More preferably 0.5 to 50 μm, and still more preferably 0.5 to 10 μm.

In the case of laminating the polarizer and the protective film, an easy adhesion layer may be provided between the protective film and the adhesive layer. The easy-adhesion layer can be formed using various resins having, for example, a polyester skeleton, a polyether skeleton, a polycarbonate skeleton, a polyurethane skeleton, silicones, a polyamide skeleton, a polyimide skeleton, a polyvinyl alcohol skeleton, or the like. These polymer resins may be used alone in 1 kind, or 2 or more kinds may be used in combination. In addition, other additives may be added to the formation of the easy adhesion layer. Specifically, a thickener, an ultraviolet absorber, an antioxidant, a stabilizer such as a heat stabilizer, and the like can be further used.

Generally, an easy-adhesion layer is provided on a protective film in advance, and the easy-adhesion layer side of the protective film is laminated with a polarizer via an adhesive layer. The easy adhesion layer can be formed by applying a material for forming the easy adhesion layer to the protective film by a known technique and drying the applied material. The material for forming the easy-adhesion layer may be prepared as a solution diluted to an appropriate concentration in consideration of the thickness after drying, the smoothness of application, and the like. The thickness of the easy adhesion layer after drying is preferably 0.01 to 5 μm, more preferably 0.02 to 2 μm, and still more preferably 0.05 to 1 μm. In this case, the easy adhesion layer is preferably formed to have a total thickness within the above range.

The adhesive layer is formed of an adhesive. As the binder, various binders can be used, and examples thereof include: rubber-based adhesives, acrylic-based adhesives, silicone-based adhesives, urethane-based adhesives, vinyl alkyl ether-based adhesives, polyvinyl pyrrolidone-based adhesives, polyacrylamide-based adhesives, cellulose-based adhesives, and the like. The base polymer for adhesion may be selected corresponding to the kind of the above-mentioned adhesive. Among the above-mentioned pressure-sensitive adhesives, acrylic pressure-sensitive adhesives are preferably used because they are excellent in optical transparency, exhibit adhesive properties such as suitable wettability, cohesiveness and adhesiveness, and are excellent in weather resistance, heat resistance and the like.

The undercoat layer (undercoat layer) is formed to improve the adhesion between the polarizer and the protective film. The material constituting the undercoat layer is not particularly limited as long as it exerts a certain degree of strong adhesion to both the base film and the polyvinyl alcohol resin layer. For example, a thermoplastic resin or the like excellent in transparency, thermal stability, stretchability, and the like can be used. Examples of the thermoplastic resin include: acrylic resin, polyolefin resin, polyester resin, polyvinyl alcohol resin, or a mixture thereof.

< adhesive layer >

The adhesive layer of the one-side protective polarizing film with an adhesive layer of the present invention is formed of an acrylic adhesive containing a (meth) acrylic polymer as a base polymer. Acrylic pressure-sensitive adhesives are excellent in optical transparency, exhibit adhesive properties such as favorable wettability, cohesiveness and adhesiveness, and are excellent in weather resistance, heat resistance and the like, and therefore are suitable as a material for forming a pressure-sensitive adhesive layer.

The weight change rate of the pressure-sensitive adhesive layer calculated by the following formula (1) is 1.1% or more, preferably 1.2% or more, and more preferably 1.3% or more. If the weight change rate is less than 1.1%, the durability and the conductive stability of the pressure-sensitive adhesive layer tend to be deteriorated in a high-temperature and/or high-humidity environment. In addition, the adhesive force P described below is adjusted ₁ And P ₂ From the viewpoint of adjustment to the target range, the weight change rate is preferably 2.0% or less, and more preferably 1.8% or less.

Weight change rate (%) = { (W) ₁ －W ₀ )/W ₀ }×100 (1)

W ₀ = weight of adhesive layer after drying the adhesive layer at 23 ℃ for 2 hours

W ₁ = weight of pressure-sensitive adhesive layer after leaving the pressure-sensitive adhesive layer after drying at 23 ℃ and 55% RH for 5 hours, and further after leaving the pressure-sensitive adhesive layer at 60 ℃ and 95% RH for 5 hours

Further, the adhesive force P of the adhesive layer under the following conditions ₀ Is 10N/25mm or less and has an adhesive force P under the following conditions ₁ Is 1.6N/25mm or more. The above adhesive force P ₀ When the amount exceeds 10N/25mm, the initial reworkability is deteriorated. From the above viewpoint, the adhesive force P ₀ Preferably 8N/25mm or less, more preferably 6N/25mm or less. In addition, the adhesive force P is ₁ When the thickness is less than 1.6N/25mm, the adhesive strength is liable to be lowered when exposed to an environment where dew condensation occurs, and the adhesive layer is liable to be peeled from a glass substrate or the like. From the above viewpoint, the adhesive force P ₁ Preferably 2N/25mm or more, more preferably 3N/25mm or more.

Adhesive force P ₀ : the pressure-sensitive adhesive layer of the single-side protective polarizing film with pressure-sensitive adhesive layer is adhered to the surface of alkali-free glass at 50 deg.C and 0.5atmAn adhesive strength when the pressure-sensitive adhesive layer is peeled from the surface of the alkali-free glass under conditions of a peeling temperature of 23 ℃, a peeling speed of 300mm/min and a peeling angle of 90 degrees after autoclave treatment for 15 minutes under the conditions,

adhesive force P ₁ : and (2) an adhesive strength when the pressure-sensitive adhesive layer of the one-side protective polarizing film with the pressure-sensitive adhesive layer is stuck to the surface of an alkali-free glass, followed by autoclave treatment for 15 minutes under conditions of 50 ℃ and 0.5atm, immersing the resulting laminate in water at 23 ℃ for 2 hours, taking out the laminate from the water, and then peeling the pressure-sensitive adhesive layer from the surface of the alkali-free glass under conditions of a peeling temperature of 23 ℃, a peeling speed of 300mm/min, and a peeling angle of 90 degrees.

From the above viewpoint, the adhesive force P of the adhesive layer under the following conditions ₂ Preferably 0.8N/25mm or more, more preferably 1.0N/25mm or more.

Adhesive force P ₂ : and (2) an adhesive strength when the pressure-sensitive adhesive layer of the one-side protective polarizing film with the pressure-sensitive adhesive layer is stuck to the surface of an alkali-free glass, and then autoclave treatment is performed for 15 minutes under conditions of 50 ℃ and 0.5atm, the obtained laminate is immersed in water at 23 ℃ for 5 hours, the laminate is taken out of the water, and then the pressure-sensitive adhesive layer is peeled from the surface of the alkali-free glass under conditions of a peeling temperature of 23 ℃, a peeling speed of 300mm/min, and a peeling angle of 90 degrees.

As the (meth) acrylic polymer, a (meth) acrylic polymer having a main skeleton of a monomer unit of an alkyl (meth) acrylate can be used. The term (meth) acrylate refers to acrylate and/or methacrylate, and has the same meaning as (meth) acrylate in the present invention.

The alkyl group of the alkyl (meth) acrylate constituting the main skeleton of the (meth) acrylic polymer has about 1 to 18 carbon atoms, and specific examples of the alkyl (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, and stearyl (meth) acrylate, and they may be used alone or in combination.

In order to obtain a composition having the above weight change ratio and the above adhesive force P ₀ ～P ₂ And further suppressing the generation of nano slits, the (meth) acrylic polymer preferably contains, as a monomer unit:

50% by weight or more (more preferably 60% by weight or more, further preferably 70% by weight or more, further preferably 80% by weight or more) of an alkyl (meth) acrylate (a) having a glass transition temperature of a homopolymer of less than 0 ℃ (more preferably-20 ℃ or less, further preferably-40 ℃ or less); and

0.1 to 20 wt% (more preferably 1 to 15 wt%, further preferably 2.5 to 10 wt%, further preferably 4 wt% or more and less than 10 wt%) of at least one high Tg monomer (B) selected from the group consisting of an alkyl (meth) acrylate (B1) having a homopolymer glass transition temperature of 0 ℃ or more (more preferably 20 ℃ or more, further preferably 40 ℃ or more) and a (meth) acryloyl group-containing monomer (B2) having a heterocycle and a homopolymer glass transition temperature of 0 ℃ or more (more preferably 20 ℃ or more, further preferably 40 ℃ or more). When the alkyl (meth) acrylate (b 1) and the (meth) acryloyl group-containing monomer (b 2) are used in combination, the total weight% is defined as the total weight%.

Examples of the alkyl (meth) acrylate (a) include: ethyl acrylate (Tg: -24 ℃ C.), n-butyl acrylate (Tg: -50 ℃ C.), n-pentyl methacrylate (Tg: -5 ℃ C.), n-hexyl acrylate (Tg: -57 ℃ C.), n-hexyl methacrylate (Tg: -5 ℃ C.), n-octyl acrylate (Tg: -65 ℃ C.), n-octyl methacrylate (Tg: -20 ℃ C.), n-nonyl acrylate (Tg: -58 ℃ C.), n-lauryl acrylate (Tg: -3 ℃ C.), n-lauryl methacrylate (Tg: -65 ℃ C.), n-tetradecyl methacrylate (Tg: -72 ℃ C.), isopropyl acrylate (Tg: -3 ℃ C.), isobutyl acrylate (Tg: -40 ℃ C.), isooctyl acrylate (Tg: -58 ℃ C.), isooctyl methacrylate (Tg: -45 ℃ C.), 2-ethylhexyl acrylate (Tg: -70 ℃ C.), 2-ethylhexyl methacrylate (Tg: -10 ℃ C.), and the like. They may be used alone or in combination. Of these, at least one selected from the group consisting of ethyl acrylate, n-butyl acrylate, n-pentyl methacrylate, n-hexyl acrylate, and 2-ethylhexyl acrylate is preferably used, and n-butyl acrylate is more preferably used. The Tg (glass transition temperature) in each bracket is the Tg of a homopolymer obtained by polymerizing each monomer. The same applies to the following description.

Examples of the alkyl (meth) acrylate (b 1) include: linear alkyl (meth) acrylates such as methyl acrylate (Tg: 8 ℃ C.), methyl methacrylate (Tg: 105 ℃ C.), ethyl methacrylate (Tg: 65 ℃ C.), n-propyl acrylate (Tg: 3 ℃ C.), n-propyl methacrylate (Tg: 35 ℃ C.), n-pentyl acrylate (Tg: 22 ℃ C.), n-tetradecyl acrylate (Tg: 24 ℃ C.), n-hexadecyl acrylate (Tg: 35 ℃ C.), n-hexadecyl methacrylate (Tg: 15 ℃ C.), n-stearyl acrylate (Tg: 30 ℃ C.), and n-stearyl methacrylate (Tg: 38 ℃ C.); branched alkyl (meth) acrylates such as t-butyl acrylate (Tg: 43 ℃ C.), t-butyl methacrylate (Tg: 48 ℃ C.), isopropyl methacrylate (Tg: 81 ℃ C.), and isobutyl methacrylate (Tg: 48 ℃ C.); and cyclic alkyl (meth) acrylates such as cyclohexyl acrylate (Tg: 19 ℃ C.), cyclohexyl methacrylate (Tg: 65 ℃ C.), isobornyl acrylate (Tg: 94 ℃ C.), and isobornyl methacrylate (Tg: 180 ℃ C.). They may be used alone or in combination. Among these, at least one selected from the group consisting of methyl acrylate, methyl methacrylate, ethyl methacrylate, isobornyl acrylate, and isobornyl methacrylate is preferably used, and at least one selected from the group consisting of methyl acrylate, methyl methacrylate, and isobornyl acrylate is more preferably used.

The (meth) acryloyl group-containing monomer (b 2) has a heterocycle. The heterocyclic ring is not particularly limited, and examples thereof include: aliphatic ring such as aziridine ring, azetidine ring, pyrrolidine ring, piperidine ring, piperazine ring and morpholine ringHeterocyclic ring, pyrrole ring, imidazole ring, pyrazole ring,

Azolyl ring, iso

Heteroaromatic rings such as an azole ring, a thiazole ring, an isothiazole ring, a pyridine ring, a pyrimidine ring, a pyridazine ring and a pyrazine ring. The heterocyclic ring may be directly bonded to the (meth) acryloyl group or may be bonded to the (meth) acryloyl group via a linking group. Among these, aliphatic heterocyclic rings are preferable, and morpholine rings are more preferable. Examples of the (meth) acryloyl group-containing monomer (b 2) include N-acryloylmorpholine (Tg: 145 ℃ C.), and the like. They may be used alone or in combination. Of these, N-acryloylmorpholine is particularly preferably used.

For the purpose of improving adhesiveness, heat resistance, and the like, one or more of various monomers may be introduced into the (meth) acrylic polymer by copolymerization. Specific examples of such comonomers (except the (meth) acryloyl group-containing monomer (b 2)) include carboxyl group-containing monomers, hydroxyl group-containing monomers, nitrogen-containing monomers, and aromatic group-containing monomers.

Examples of the carboxyl group-containing monomer include: acrylic acid, methacrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and the like. They may be used alone or in combination.

As the hydroxyl group-containing monomer, there may be mentioned: 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxydodecyl (meth) acrylate, and (4-hydroxymethylcyclohexyl) methyl acrylate. They may be used alone or in combination.

Examples of the nitrogen-containing monomer include: vinyl monomers having a lactam ring (e.g., vinyl pyrrolidone monomers such as N-vinyl pyrrolidone and methyl vinyl pyrrolidone)And vinyl lactam monomers having a lactam ring such as a β -lactam ring, a δ -lactam ring, and an e-lactam ring); maleimide monomers such as maleimide, N-cyclohexylmaleimide and N-phenylmaleimide; (N-substituted) amide monomers such as (meth) acrylamide, N-dimethyl (meth) acrylamide, N-diethyl (meth) acrylamide, N-hexyl (meth) acrylamide, N-methyl (meth) acrylamide, N-butyl (meth) acrylamide, N-methylol (meth) acrylamide, and N-methylol propane (meth) acrylamide; aminoalkyl (meth) acrylate monomers such as aminoethyl (meth) acrylate, aminopropyl (meth) acrylate, N-dimethylaminoethyl (meth) acrylate, t-butylaminoethyl (meth) acrylate, and 3- (3-pyridyl) propyl (meth) acrylate; succinimide monomers such as N- (meth) acryloyloxymethylene succinimide, N- (meth) acryloyl-6-oxyhexamethylene succinimide, and N- (meth) acryloyl-8-oxyoctamethylene succinimide; cyano (meth) acrylate monomers such as acrylonitrile and methacrylonitrile; vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinylpyridine

Oxazole, vinyl morpholine, N-vinyl carboxylic acid amides, and the like. They may be used alone or in combination.

Examples of the aromatic group-containing monomer include: benzyl (meth) acrylate, phenyl (meth) acrylate, phenoxyethyl (meth) acrylate, and the like. They may be used alone or in combination.

In addition to the above monomers, acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride; caprolactone adducts of acrylic acid; sulfonic acid group-containing monomers such as styrenesulfonic acid, allylsulfonic acid, 2- (meth) acrylamide-2-methylpropanesulfonic acid, (meth) acrylamidopropanesulfonic acid, (meth) sulfopropyl acrylate, and (meth) acryloyloxynaphthalenesulfonic acid; phosphoric acid group-containing monomers such as 2-hydroxyethyl acryloyl phosphate, and the like. They may be used alone or in combination.

It is also possible to use: vinyl monomers such as vinyl acetate, vinyl propionate, styrene, alpha-methylstyrene and N-vinylcaprolactam; epoxy group-containing acrylic monomers such as glycidyl (meth) acrylate; polyethylene glycol acrylate monomers such as polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, methoxyethylene glycol (meth) acrylate, and methoxypolypropylene glycol (meth) acrylate; acrylic ester monomers such as tetrahydrofurfuryl (meth) acrylate, fluorine-containing (meth) acrylate, silicone (meth) acrylate, and 2-methoxyethyl acrylate. They may be used alone or in combination.

From the viewpoint of improving the cohesive force of the (meth) acrylic polymer and more effectively suppressing the generation of the nano-slits, it is preferable to introduce at least one polar monomer selected from the group consisting of the carboxyl group-containing monomer, the hydroxyl group-containing monomer, the nitrogen-containing monomer, and the aromatic group-containing monomer (except the (meth) acryloyl group-containing monomer (b 2)) into the (meth) acrylic polymer by copolymerization, and it is more preferable to introduce the carboxyl group-containing monomer, the hydroxyl group-containing monomer, and the nitrogen-containing monomer into the (meth) acrylic polymer by copolymerization. As the carboxyl group-containing monomer, (meth) acrylic acid is preferable. The hydroxyl group-containing monomer is preferably at least 1 selected from the group consisting of 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate. The nitrogen-containing monomer is preferably a vinyl-based monomer having a lactam ring, more preferably the vinylpyrrolidone-based monomer, and still more preferably N-vinylpyrrolidone. By introducing the nitrogen-containing monomer into the (meth) acrylic polymer by copolymerization, the occurrence of nano-slits can be more effectively suppressed, and the durability (peeling resistance) of the pressure-sensitive adhesive layer at high temperature and/or high humidity can be improved. The aromatic group-containing monomer is preferably phenoxyethyl (meth) acrylate.

The (meth) acrylic polymer preferably contains the carboxyl group-containing monomer in an amount of 0.01 to 3 wt%, more preferably 0.05 to 1 wt%, and still more preferably 0.1 to 0.5 wt% as a monomer unit.

The (meth) acrylic polymer preferably contains the hydroxyl group-containing monomer in an amount of 0.01 to 1% by weight, more preferably 0.05 to 1% by weight, and still more preferably 0.1 to 0.5% by weight as a monomer unit.

The (meth) acrylic polymer preferably contains, as a monomer unit, 0.1 to 5% by weight, more preferably 0.5 to 3% by weight, and still more preferably 1.5 to 3% by weight of the nitrogen-containing monomer.

The (meth) acrylic polymer preferably contains 1 to 20% by weight, more preferably 1 to 18% by weight, and still more preferably 1 to 15% by weight of the aromatic group-containing monomer as a monomer unit.

The weight average molecular weight of the (meth) acrylic polymer is not particularly limited, but is preferably 150 ten thousand or less, more preferably 140 ten thousand or less, and further preferably 130 ten thousand or less, from the viewpoint of coatability of the adhesive. In addition, the weight average molecular weight is usually 80 ten thousand or more, preferably 100 ten thousand or more, from the viewpoint of adhesive properties, weather resistance, heat resistance and the like.

The (meth) acrylic polymer can be produced by a known method, and for example, radical polymerization such as bulk polymerization, solution polymerization, suspension polymerization and the like can be appropriately selected. As the radical polymerization initiator, various known initiators such as azo type and peroxide type initiators can be used. The reaction temperature is usually about 50 to 80 ℃ and the reaction time is usually 1 to 8 hours. Among the above production methods, the solution polymerization method is preferred, and ethyl acetate, toluene and the like are generally used as a solvent for the (meth) acrylic polymer.

The binder may contain a crosslinking agent. The crosslinking agent improves adhesion and durability, and can achieve reliability at high temperatures and shape retention of the adhesive itself. As the crosslinking agent, isocyanates, epoxies, peroxides, metal chelates, peroxides, etc., can be suitably used,

Oxazolines, and the like. These crosslinking agents can be used in 1 or a combination of 2 or more.

Isocyanate-based crosslinking agents isocyanate compounds can be used. Examples of the isocyanate compound include isocyanate monomers such as tolylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, and hydrogenated diphenylmethane diisocyanate, and adduct-type isocyanate compounds obtained by adding these isocyanate monomers to trimethylolpropane or the like; examples of the isocyanurate and biuret compounds include urethane prepolymer type isocyanates obtained by addition reaction of known polyether polyols, polyester polyols, acrylic polyols, polybutadiene polyols, polyisoprene polyols, and the like.

The isocyanate-based crosslinking agent may be used alone or in combination of two or more, and the total content of the isocyanate-based crosslinking agent is preferably 0.01 to 2 parts by weight, more preferably 0.02 to 2 parts by weight, and still more preferably 0.05 to 1.5 parts by weight, based on 100 parts by weight of the base polymer. It may be suitably contained in consideration of cohesive force, resistance to peeling in a durability test, and the like.

Various peroxides are used as the peroxide crosslinking agent. Examples of the peroxide include di (2-ethylhexyl) peroxydicarbonate, di (4-tert-butylcyclohexyl) peroxydicarbonate, di-sec-butyl peroxydicarbonate, tert-butyl peroxyneodecanoate, tert-hexyl peroxypivalate, tert-butyl peroxypivalate, dilauroyl peroxide, di-n-octanoyl peroxide, 1, 3-tetramethylbutyl peroxyisobutyrate, 1, 3-tetramethylbutyl peroxy2-ethylhexanoate, bis (4-methylbenzoyl) peroxide, dibenzoyl peroxide, and tert-butyl peroxyisobutyrate. Among them, bis (4-t-butylcyclohexyl) peroxydicarbonate, dilauroyl peroxide, and dibenzoyl peroxide, which are excellent in crosslinking reaction efficiency, are particularly preferably used.

The above-mentioned peroxides may be used singly or in combination of two or more, and the total content of the above-mentioned peroxides is preferably 0.01 to 2 parts by weight, more preferably 0.04 to 1.5 parts by weight, and still more preferably 0.05 to 1 part by weight, based on 100 parts by weight of the base polymer. Within this range, the processability, reworkability, crosslinking stability, peelability and the like can be suitably selected.

In order to obtain a composition having the above adhesion force P ₀ ～P ₂ The pressure-sensitive adhesive layer of (3), preferably, the pressure-sensitive adhesive contains a silane coupling agent. As the silane coupling agent, a silane coupling agent having any suitable functional group can be used. Examples of the functional group include: vinyl groups, epoxy groups, amino groups, acid anhydride groups, mercapto groups, (meth) acryloyloxy groups, acetoacetyl groups, isocyanate groups, styryl groups, polysulfide groups, and the like. Specific examples thereof include: vinyl silane-containing coupling agents such as vinyltriethoxysilane, vinyltripropoxysilane, vinyltriisopropoxysilane and vinyltributoxysilane; epoxy group-containing silane coupling agents such as gamma-glycidoxypropyltrimethoxysilane, gamma-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane and 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane; amino-containing silane coupling agents such as γ -aminopropyltrimethoxysilane, N- β - (aminoethyl) - γ -aminopropylmethyldimethoxysilane, N- (2-aminoethyl) 3-aminopropylmethyldimethoxysilane, γ -triethoxysilyl-N- (1, 3-dimethylbutylidene) propylamine, and N-phenyl- γ -aminopropyltrimethoxysilane; anhydride group-containing silane coupling agents such as 3-trimethoxysilylpropyl succinic anhydride; mercapto silane-containing coupling agents such as γ -mercaptopropylmethyldimethoxysilane; styrene-containing silane coupling agents such as p-styryltrimethoxysilane; (meth) acrylic acid-containing silane coupling agents such as gamma-acryloyloxypropyltrimethoxysilane and gamma-methacryloyloxypropyltriethoxysilane; isocyanate-containing silane coupling agents such as 3-isocyanatopropyltriethoxysilane; polysulfide-containing silane coupling agents such as bis (triethoxysilylpropyl) tetrasulfide, and the like. These silane coupling agents may be used alone or in combination. Among these, from the viewpoint of obtaining an adhesive layer which is not easily peeled from a glass substrate or the like even when exposed to an environment where dew condensation occurs,the silane coupling agent having at least 1 functional group selected from the group consisting of an epoxy group, an isocyanate group, a mercapto group, an acid anhydride group and an amino group is preferably used, and the silane coupling agent having an epoxy group, an isocyanate group, a mercapto group or an acid anhydride group is more preferably used.

In addition, an oligomer type silane coupling agent may be used from the viewpoint of obtaining an adhesive layer that is not easily peeled off from a glass substrate or the like even when exposed to an environment where dew condensation occurs. The oligomer type is a polymer of about 2-mer or more and less than 100-mer of a monomer, and the weight average molecular weight of the oligomer type silane coupling agent is preferably about 300 to 30000.

Examples of the oligomer-type silane coupling agent include: epoxy-containing silane coupling agents, mercapto-containing silane coupling agents, and isocyanate-containing silane coupling agents, etc., and mercapto-containing silane coupling agents and isocyanate-containing silane coupling agents are preferred. They may be used alone or in combination.

The epoxy equivalent of the epoxy group-containing silane coupling agent is preferably 250 to 600g/mol, more preferably 250 to 500g/mol, and even more preferably 280 to 400g/mol, from the viewpoint of durability of the pressure-sensitive adhesive layer in a high-temperature and/or high-humidity environment.

The epoxy group-containing silane coupling agent preferably has 2 or more alkoxysilyl groups in the molecule. In the silane coupling agent, the amount of the alkoxy group in the epoxy group-containing silane coupling agent is preferably 10 to 60% by weight, more preferably 20 to 50% by weight, and still more preferably 20 to 40% by weight. The epoxy group-containing silane coupling agent has 1 or 2 or more epoxy groups in the molecule, but preferably has 1 epoxy group in the molecule from the viewpoint of obtaining an adhesive layer that is not easily peeled off from a glass substrate or the like even when exposed to an environment where condensation occurs. From the above viewpoint, the epoxy group-containing silane coupling agent preferably has an aromatic ring in the molecule.

Examples of the oligomer-type epoxy group-containing silane coupling agent having 2 or more alkoxysilyl groups in the molecule include: X-12-981S, X-12-1231, X-41-1059A, X-41-1056, and the like, manufactured by shin-Etsu chemical Co., ltd.

From the viewpoint of durability of the pressure-sensitive adhesive layer in a high-temperature and/or high-humidity environment, the mercapto equivalent weight of the mercapto group-containing silane coupling agent is preferably 1000g/mol or less, more preferably 800g/mol or less, even more preferably 700g/mol or less, and even more preferably 500g/mol or less. The lower limit of the mercapto equivalent is not particularly limited, but is preferably 200g/mol or more.

The mercapto group-containing silane coupling agent preferably has 2 or more alkoxysilyl groups in the molecule. In the silane coupling agent, the alkoxy group content of the mercapto group-containing silane coupling agent is preferably 10 to 60% by weight, more preferably 20 to 50% by weight, and still more preferably 20 to 40% by weight.

Examples of the oligomer-type mercapto silane-containing coupling agent having 2 or more alkoxysilyl groups in the molecule include: x-41-1805, X-41-1810, X-41-1818, X-12-1156 and the like, all manufactured by shin Etsu chemical Co., ltd.

The isocyanate equivalent weight of the isocyanatosilane-containing coupling agent is preferably 250 to 600g/mol, more preferably 250 to 500g/mol, and even more preferably 280 to 400g/mol, from the viewpoint of durability of the pressure-sensitive adhesive layer in a high-temperature and/or high-humidity environment.

The isocyanate-containing silane coupling agent preferably has 2 or more alkoxysilyl groups in the molecule. In the silane coupling agent, the amount of the alkoxy group in the isocyanate-containing silane coupling agent is preferably 10 to 60% by weight, more preferably 20 to 50% by weight, and still more preferably 20 to 40% by weight.

Examples of the oligomeric isocyanate-containing silane coupling agent having 2 or more alkoxysilyl groups in the molecule include: x-40-9318, X-12-1159L manufactured by shin-Etsu chemical Co., ltd.

To obtain a composition having the above adhesive force P ₀ ～P ₂ From the viewpoint of the pressure-sensitive adhesive layer (b), the content of the entire silane coupling agent is preferably 0.05 to 5 parts by weight, more preferably 0.1 to 3 parts by weight, and still more preferably 0.2 to 2 parts by weight, based on 100 parts by weight of the base polymer。

Further, the adhesive force P is obtained ₀ ～P ₂ In view of the pressure-sensitive adhesive layer(s), the content of the silane coupling agent (including the oligomer type silane coupling agent) having at least 1 functional group selected from the group consisting of an epoxy group, an isocyanate group, a mercapto group, an acid anhydride group and an amino group is preferably 0.01 to 3 parts by weight, more preferably 0.1 to 2 parts by weight, and still more preferably 0.1 to 1 part by weight, based on 100 parts by weight of the base polymer.

Further, from the viewpoint of improving the reworkability, the binder preferably contains a reworking improver. The above-mentioned reworking improver is a chemical substance which has a polar group, is likely to interact with a glass interface, and is likely to segregate at the glass interface. Examples of the above-mentioned rework improving agent include: diols having an oxyalkylene group such as EO and PO, oligomers having a perfluoroalkyl group, and polyether compounds having a reactive silyl group. The polyether compound may be, for example, a polyether compound disclosed in Japanese patent application laid-open No. 2010-275522.

Examples of the polyether compound having a reactive silyl group include: MS polymers S203, S303, and S810 manufactured by KANEKA corporation; SILYL EST250, EST280; SAT10, SAT200, SAT220, SAT350, SAT400, EXCESTAR S2410, S2420 or S3430 manufactured by Asahi glass company.

The content of the rework improving agent is preferably 0.001 parts by weight or more, more preferably 0.01 parts by weight or more, further preferably 0.1 parts by weight or more, and further preferably 10 parts by weight or less, more preferably 5 parts by weight or less, further preferably 2 parts by weight or less, and further preferably 1 part by weight or less, relative to 100 parts by weight of the base polymer. When the content of the reworking improver is less than 0.001 parts by weight, the reworkability of the pressure-sensitive adhesive layer is difficult to improve, and when the content is more than 10 parts by weight, the adhesive properties of the pressure-sensitive adhesive layer tend to be lowered.

Further, it is preferable that the adhesive contains an antistatic agent. In the case of attaching the pressure-sensitive adhesive layer-attached one-side protective polarizing film to a liquid crystal panel in the production of a liquid crystal display device, a release film is peeled from the pressure-sensitive adhesive layer of the pressure-sensitive adhesive layer-attached one-side protective polarizing film, but static electricity is generated by the peeling of the release film. In addition, when a lamination error occurs when a one-side protective polarizing film with an adhesive layer is attached to a liquid crystal panel, the polarizing film needs to be peeled off, but static electricity is generated by the peeling of the polarizing film. The generated static electricity affects the alignment of liquid crystals in the liquid crystal display device, and causes a problem. In addition, when a liquid crystal display device is used, display unevenness due to static electricity may occur. By adding an antistatic agent to the adhesive, an antistatic function can be imparted to the adhesive layer of the one-side protective polarizing film with the adhesive layer, thereby preventing such inconveniences.

The antistatic agent is not particularly limited, and examples thereof include:

anionic salts, and alkali metal salts of plasma compounds. It is considered that when an ionic compound is added, the ionic compound bleeds out to the surface of the pressure-sensitive adhesive layer, and the antistatic function is effectively exhibited. On the other hand, the ionic compound may come into contact with the polarizer to deteriorate optical characteristics such as a degree of polarization. From the viewpoint of suppressing the deterioration of the optical properties, it is particularly preferable to use an alkali metal salt.

The alkali metal salt may be an organic or inorganic salt of an alkali metal. The alkali metal salt may be used alone in 1 kind, or in combination of plural kinds.

Examples of the alkali metal ion constituting the cation portion of the alkali metal salt include various ions such as lithium, sodium, and potassium. Among these alkali metal ions, lithium ions are preferable.

The anion portion of the alkali metal salt may be composed of an organic substance or an inorganic substance. As the anion moiety constituting the organic salt, for example, CH can be used ₃ COO ^- 、CF ₃ COO ^- 、CH ₃ SO ₃ ^- 、CF ₃ SO ₃ ^- 、 (CF ₃ SO ₂ ) ₂ N ^- 、(CF ₃ SO ₂ ) ₃ C ^- 、C ₄ F ₉ SO ₃ ^- 、(C ₂ F ₅ SO ₂ ) ₂ N ^- 、C ₃ F ₇ COO ^- 、 (CF ₃ SO ₂ )(CF ₃ CO)N ^- 、 ^- O ₃ S(CF ₂ ) ₃ SO ₃ ^- 、PF ₆ ^- 、CO ₃ ^2- And so on. In particular, an ionic compound having good ion dissociation properties can be obtained in an anion portion containing a fluorine atom, and thus the compound is preferably used. As the anion portion constituting the inorganic salt, cl may be used ^- 、Br ^- 、I ^- 、AlCl ₄ ^- 、Al ₂ Cl ₇ ^- 、BF ₄ ^- 、PF ₆ ^- 、 ClO ₄ ^- 、NO ₃ ^- 、AsF ₆ ^- 、SbF ₆ ^- 、NbF ₆ ^- 、TaF ₆ ^- 、(CN) ₂ N ^- And so on. As the anion portion, (CF) is preferable ₃ SO ₂ ) ₂ N ^- 、(C ₂ F ₅ SO ₂ ) ₂ N ^- Etc. (perfluoroalkylsulfonyl) imide, particularly preferably (CF) ₃ SO ₂ ) ₂ N ^- (trifluoromethanesulfonyl) imide.

Specific examples of the organic salt of an alkali metal include: sodium acetate, sodium alginate, sodium lignosulfonate, sodium tosylate, liCF ₃ SO ₃ 、Li(CF ₃ SO ₂ ) ₂ N、Li(CF ₃ SO ₂ ) ₂ N、Li(C ₂ F ₅ SO ₂ ) ₂ N、 Li(C ₄ F ₉ SO ₂ ) ₂ N、Li(CF ₃ SO ₂ ) ₃ C、KO ₃ S(CF ₂ ) ₃ SO ₃ K、LiO ₃ S(CF ₂ ) ₃ SO ₃ K, etc., among these, liCF is preferred ₃ SO ₃ 、Li(CF ₃ SO ₂ ) ₂ N、Li(C ₂ F ₅ SO ₂ ) ₂ N、Li(C ₄ F ₉ SO ₂ ) ₂ N、 Li(CF ₃ SO ₂ ) ₃ C, etc., more preferably Li (CF) ₃ SO ₂ ) ₂ N、Li(C ₂ F ₅ SO ₂ ) ₂ N、Li(C ₄ F ₉ SO ₂ ) ₂ A fluorine-containing imide lithium salt such as N, and a (perfluoroalkyl sulfonyl) imide lithium salt is particularly preferable.

Examples of the inorganic salt of an alkali metal include lithium perchlorate and lithium iodide.

The content of the alkali metal salt in the binder is preferably 0.001 to 5 parts by weight with respect to 100 parts by weight of the base polymer. When the alkali metal salt is less than 0.001 part by weight, the effect of improving antistatic performance may be insufficient. The content of the alkali metal salt is preferably 0.01 parts by weight or more, and more preferably 0.1 parts by weight or more. On the other hand, when the content of the alkali metal salt is more than 5 parts by weight, durability may be insufficient. The content of the alkali metal salt is preferably 3 parts by weight or less.

As a method for forming the pressure-sensitive adhesive layer, the following method can be used: for example, a method in which the pressure-sensitive adhesive is applied to a separator or the like subjected to a peeling treatment, and after a pressure-sensitive adhesive layer is formed by drying and removing a polymerization solvent or the like, the pressure-sensitive adhesive layer is transferred onto the polarizer side (polarizer in the embodiment of fig. 1) of the one-side protective polarizing film; or a method of applying the above adhesive, drying the adhesive to remove the polymerization solvent and the like, and forming an adhesive layer on the polarizer; and so on. In the case of applying the adhesive, one or more solvents other than the polymerization solvent may be added newly as appropriate.

The thickness of the pressure-sensitive adhesive layer is not particularly limited, but is preferably 25 μm or less, more preferably 23 μm or less, further preferably 20 μm or less, and further preferably 10 μm or more, more preferably 12 μm or more, and further preferably 15 μm or more, from the viewpoint of effectively suppressing defects due to nano slits and satisfying excellent pressure-sensitive adhesive characteristics and reworkability.

As the separator subjected to the peeling treatment, a silicone release liner can be preferably used. In the step of forming the pressure-sensitive adhesive layer by applying the pressure-sensitive adhesive of the present invention to such a liner and drying the applied pressure-sensitive adhesive, a suitable method can be appropriately employed as a method for drying the pressure-sensitive adhesive according to the purpose. The method of drying the coating film by heating is preferably used. The heating and drying temperature is preferably 40 to 200 ℃, more preferably 50 to 180 ℃, and particularly preferably 70 to 170 ℃. By setting the heating temperature in the above range, an adhesive having excellent adhesive characteristics can be obtained.

The drying time may be suitably employed as appropriate. The drying time is preferably 5 seconds to 20 minutes, more preferably 5 seconds to 10 minutes, and particularly preferably 10 seconds to 5 minutes.

As a method for forming the adhesive layer, various methods can be employed. Specific examples thereof include: roll coating, roll-and-lick coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, blade coating, air knife coating, curtain coating, lip coating, extrusion coating using a die coater, and the like.

When the pressure-sensitive adhesive layer is exposed, the pressure-sensitive adhesive layer can be protected with a sheet (separator) subjected to a peeling treatment until it is actually used.

Examples of the constituent material of the separator include: plastic films such as polyethylene, polypropylene, polyethylene terephthalate and polyester films, porous materials such as paper, cloth and nonwoven fabrics, and suitable sheets such as nets, foamed sheets, metal foils and laminates thereof, and the like.

The plastic film is not particularly limited as long as it can protect the pressure-sensitive adhesive layer, and examples thereof include: polyethylene films, polypropylene films, polybutylene films, polybutadiene films, polymethylpentene films, polyvinyl chloride films, vinyl chloride copolymer films, polyethylene terephthalate films, polybutylene terephthalate films, polyurethane films, ethylene-vinyl acetate copolymer films, and the like.

The thickness of the separator is usually about 5 to 200. Mu.m, preferably about 5 to 100. Mu.m. The separator may be subjected to release and antifouling treatment using a release agent of silicone type, fluorine type, long chain alkyl type or fatty acid amide type, silica powder or the like, or antistatic treatment of coating type, mixing type, vapor deposition type or the like, as necessary. In particular, the surface of the separator may be appropriately subjected to a release treatment such as a silicone treatment, a long-chain alkyl treatment, or a fluorine treatment, whereby the releasability from the pressure-sensitive adhesive layer can be further improved.

< surface protective film >

A surface protective film may be disposed on the one-side protective polarizing film with the adhesive layer. The surface protective film generally has a base film and an adhesive layer, and protects the polarizer via the adhesive layer.

The base film of the surface protective film may be selected from materials having isotropy or near isotropy from the viewpoint of inspection properties, manageability, and the like. Examples of the film material include: transparent polymers such as polyester resins such as polyethylene terephthalate films, cellulose resins, acetate resins, polyethersulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, and acrylic resins. Among these materials, polyester-based resins are preferred. The substrate film may be a laminate of 1 or 2 or more kinds of film materials, or a stretched product of the above film. The thickness of the base film is usually 500 μm or less, preferably 10 to 200. Mu.m.

As the pressure-sensitive adhesive for forming the pressure-sensitive adhesive layer of the surface protective film, a pressure-sensitive adhesive using a polymer such as a (meth) acrylic polymer, a silicone polymer, a polyester, a polyurethane, a polyamide, a polyether, a fluorine polymer, or a rubber as a base polymer can be appropriately selected and used. From the viewpoint of transparency, weather resistance, heat resistance and the like, an acrylic adhesive comprising an acrylic polymer as a base polymer is preferred. The thickness of the adhesive layer (dry film thickness) may be determined according to the desired adhesive force. Usually about 1 to 100. Mu.m, preferably 5 to 50 μm.

In the surface protective film, a release treated layer may be provided on the surface of the base film opposite to the surface on which the pressure-sensitive adhesive layer is provided, using a low-adhesion material subjected to a silicone treatment, a long-chain alkyl treatment, a fluorine treatment, or the like.

< other optical layers >

The pressure-sensitive adhesive layer-equipped single-sided protective polarizing film of the present invention can be used in practice as an optical film laminated with other optical layers. The optical layer is not particularly limited, and 1 or 2 or more layers of optical layers, such as a reflective plate, a semi-transmissive plate, a retardation plate (including 1/2 wave plate, 1/4 wave plate, and the like), a viewing angle compensation film, and the like, which are used in the formation of a liquid crystal display device and the like, may be used. In particular, a reflective polarizing film or a semi-transmissive polarizing film in which a reflective plate or a semi-transmissive reflective plate is further laminated on the pressure-sensitive adhesive layer-attached one-side protective polarizing film of the present invention, an elliptical polarizing film or a circular polarizing film in which a phase difference plate is further laminated on the pressure-sensitive adhesive layer-attached one-side protective polarizing film, a wide-angle polarizing film in which a viewing angle compensation film is further laminated on the pressure-sensitive adhesive layer-attached one-side protective polarizing film, or a polarizing film in which a brightness enhancement film is further laminated on the pressure-sensitive adhesive layer-attached one-side protective polarizing film is preferable.

The optical film in which the optical layers are laminated on the pressure-sensitive adhesive layer-attached single-side protective polarizing film may be formed by sequentially laminating the optical layers in the production process of a liquid crystal display device or the like, but when the optical film is laminated in advance to form the optical film, there are advantages in that stability of quality, assembly work, and the like are excellent, and the production process of the liquid crystal display device or the like can be improved. The lamination may be carried out by a suitable bonding means such as an adhesive layer. When the above-mentioned one-side protective polarizing film with an adhesive layer and other optical films are bonded, their optical axes may be set at an appropriate arrangement angle depending on the desired retardation characteristics and the like.

The pressure-sensitive adhesive layer-equipped single-sided protective polarizing film or optical film of the present invention can be preferably used for formation of various image display devices such as liquid crystal display devices and organic EL display devices. The liquid crystal display device can be formed in a conventional manner. That is, the liquid crystal display device can be generally formed by appropriately assembling a liquid crystal cell, a one-side protective polarizing film or an optical film with an adhesive layer, and components such as an illumination system used as needed, and introducing them into a driver circuit or the like. As the liquid crystal cell, any type of liquid crystal cell such as IPS type, VA type, etc. can be used, and IPS type is particularly preferable.

A liquid crystal display device in which a single-sided protective polarizing film or an optical film with an adhesive layer is disposed on one side or both sides of a liquid crystal cell, a liquid crystal display device using a backlight or a reflector in an illumination system, or the like can be formed. At this time, the adhesive layer-equipped one-sided protective polarizing film or optical film of the present invention may be disposed on one side or both sides of the liquid crystal cell. In the case where a single-sided protective polarizing film or optical film with an adhesive layer is provided on both sides, they may be the same material or different materials. Further, in forming a liquid crystal display device, appropriate members such as a diffusion plate, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusion plate, and a backlight may be disposed in appropriate positions in 1 layer or 2 layers or more.

< method for continuously producing image display device >

The above-described image display device is preferably manufactured by a continuous manufacturing method (roll-to-plate) method including: the pressure-sensitive adhesive layer-equipped one-side protective polarizing film of the present invention fed continuously from a roll (roll) of the pressure-sensitive adhesive layer-equipped one-side protective polarizing film and conveyed by the separator is continuously bonded to the surface of the image display panel via the pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer-attached one-side protective polarizing film of the present invention is a very thin film, and therefore, in a case of a method of cutting (sheet-by-sheet cutting) the film into a sheet shape and attaching the film to an image display panel one by one (also referred to as a "sheet-to-panel (sheet) method"), handling at the time of sheet conveyance and attachment to the display panel is difficult, and in these processes, the risk of the pressure-sensitive adhesive layer-attached one-side protective polarizing film (sheet) being subjected to a large mechanical impact (for example, deflection due to adsorption or the like) increases. In order to reduce such a risk, it is necessary to take another measure such as using a surface protection film having a substrate film thickness of 50 μm or more. On the other hand, if a roll-to-roll system is used, the pressure-sensitive adhesive layer-attached single-sided protective polarizing film is stably transported from a roll to an image display panel through a continuous separator without being cut (cut into individual sheets) into a sheet shape, and is adhered to the image display panel while maintaining this state. As a result, high-speed continuous production of image display panels in which the occurrence of nano-slits is effectively suppressed can be realized in addition to the relaxation of mechanical impact by the pressure-sensitive adhesive layer controlled such that the film thickness and the storage modulus satisfy the predetermined relational expression.

Fig. 5 is a schematic diagram showing an example of a continuous manufacturing system of a liquid crystal display device using a roll-to-plate (roll-to-plate) method. As shown in fig. 5, a continuous manufacturing system 100 for liquid crystal display devices includes: a series of conveying units X, a 1 st polarizing film supply unit 101a, a 1 st laminating unit 201a, a 2 nd polarizing film supply unit 101b, and a 2 nd laminating unit 201b for conveying the liquid crystal display panel P. As the roll 20a of the 1 st pressure-sensitive adhesive layer-attached one-side protective polarizing film (1 st roll) and the roll 20b of the 2 nd pressure-sensitive adhesive layer-attached one-side protective polarizing film (2 nd roll), rolls of polarizing films having an absorption axis in the longitudinal direction and having the form shown in fig. 1 were used.

(conveying section)

The conveying section X conveys the liquid crystal display panel P. The conveying section X includes a plurality of conveying rollers, an adsorption plate, and the like. The conveying portion X includes an arrangement replacing portion (for example, by horizontally rotating the liquid crystal display panel P by 90 °) 300 for replacing the arrangement relationship between the long side and the short side of the liquid crystal display panel P with respect to the conveying direction of the liquid crystal display panel P between the 1 st bonding portion 201a and the 2 nd bonding portion 201b. Thus, the 1 st pressure-sensitive adhesive layer-attached one-side protective polarizing film 21a and the 2 nd pressure-sensitive adhesive layer-attached one-side protective polarizing film 21b can be bonded to the liquid crystal display panel P in a crossed nicol relationship.

(No. 1 polarizing film supply section)

The 1 st polarizing film supply unit 101a continuously supplies the 1 st pressure-sensitive adhesive layer-attached single-sided protective polarizing film (adhesive surface protective film-attached sheet) 21a continuously fed from the 1 st roll 20a and conveyed by the separator 5a to the 1 st laminating unit 201a. The 1 st polarizing film supply section 101a has: a 1 st continuous feeding unit 151a, a 1 st cutting unit 152a, a 1 st peeling unit 153a, a 1 st winding unit 154a, a plurality of conveyance roller units, a power storage unit such as a dancer roller (dancer roller), and the like.

The 1 st continuous feeding unit 151a has a continuous feeding shaft on which the 1 st roll 20a is provided, and continuously feeds the single-side protective polarizing film 21a with the pressure-sensitive adhesive layer in a belt shape on which the separator 5a is provided from the 1 st roll 20 a.

The 1 st cutting unit 152a includes a cutting mechanism such as a cutter or a laser device, and an adsorption mechanism. The 1 st cutting section 152a cuts the 1 st adhesive layer-attached one-side protective polarizing film 21a in a tape shape in the width direction by a given length and leaves the separator 5a. Note that, when a roll of the single-side protective polarizing film 21a (a roll of an optical film with cuts) in which a tape-like pressure-sensitive adhesive layer having a plurality of cuts formed in the width direction at a predetermined length is laminated on the separator 5a is used as the 1 st roll 20a, the 1 st cut unit 152a is not necessary (the same applies to the 2 nd cut unit 152b described later).

The 1 st peeling unit 153a peels the 1 st pressure-sensitive adhesive layer-attached one-side protective polarizing film 21a from the separator 5a by folding back with the separator 5a as the inside. The 1 st peeling section 153a may be a wedge member, a roller, or the like.

The 1 st winding unit 154a winds the separator 5a after peeling the 1 st pressure-sensitive adhesive layer-attached one-side protective polarizing film 21a. The 1 st winding part 154a has a winding shaft provided for winding the roll of the separator 5a.

(1 st attaching part)

The 1 st laminating unit 201a continuously laminates the 1 st pressure-sensitive adhesive layer-attached one-side protective polarizing film 21a peeled by the 1 st peeling unit 153a to the liquid crystal display panel P conveyed by the conveying unit X with the pressure-sensitive adhesive layer of the 1 st pressure-sensitive adhesive layer-attached one-side protective polarizing film 21a interposed therebetween (1 st laminating step). The 1 st bonding section 81 includes a pair of bonding rollers, and at least one of the bonding rollers is a driving roller.

(No. 2 polarizing film supply section)

The 2 nd polarizing film supply unit 101b continuously attaches the 2 nd pressure-sensitive adhesive layer-attached single-sided protective polarizing film (surface-attached protective film) 21b continuously fed from the 2 nd roll 20b and conveyed by the separator 5b to the 2 nd attaching unit 201b. The 2 nd polarizing film supply section 101b has: a 2 nd continuous feeding section 151b, a 2 nd cutting section 152b, a 2 nd peeling section 153b, a 2 nd winding section 154b, a plurality of conveyance roller sections, an energy storage section such as a dancer roller, and the like. The 2 nd continuous feeding unit 151b, the 2 nd cutting unit 152b, the 2 nd peeling unit 153b, and the 2 nd winding unit 154b have the same configurations and functions as the 1 st continuous feeding unit 151a, the 1 st cutting unit 152a, the 1 st peeling unit 153a, and the 1 st winding unit 154a, respectively.

(No. 2 bonding part)

The 2 nd laminating unit 201b continuously laminates the 2 nd pressure-sensitive adhesive layer-attached single-side protective polarizing film 21b peeled by the 2 nd peeling unit 153b to the liquid crystal display panel P conveyed by the conveying unit X with the pressure-sensitive adhesive layer of the 2 nd pressure-sensitive adhesive layer-attached single-side protective polarizing film 21b interposed therebetween (2 nd laminating step). The 2 nd bonding portion 201b is configured to have a pair of bonding rollers, and at least one of the bonding rollers is configured by a driving roller.

Examples

The present invention will be described with reference to examples, but the present invention is not limited to the examples shown below. In each example, parts and% are on a weight basis. Hereinafter, the room temperature conditions not particularly specified were all 23 ℃ and 55% RH.

< preparation of Single-sided protective polarizing film >

(production of polarizing mirror)

One surface of a substrate of an amorphous polyethylene terephthalate isophthalate copolymer (IPA-copolymerized PET) film (thickness: 100 μm) having a water absorption rate of 0.75% and a Tg of 75 ℃ was subjected to corona treatment, and an aqueous solution containing polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (polymerization degree 1200, acetoacetyl-modified rate 4.6%, saponification degree 99.0 mol% or more, manufactured by Nippon synthetic chemical industries, ltd., trade name "GOHSEFIMER Z200") at a ratio of 9.

The resultant laminate was subjected to free-end uniaxial stretching (auxiliary stretching treatment in a gas atmosphere) of 2.0 times in the longitudinal direction (longitudinal direction) in an oven at 120 ℃ between rolls having different peripheral speeds.

Next, the laminate was immersed in an insolubilization bath (an aqueous boric acid solution prepared by mixing 4 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 30 ℃ for 30 seconds (insolubilization treatment).

Next, the polarizing plate was immersed in a dyeing solution at a liquid temperature of 30 ℃ while adjusting the iodine concentration and the immersion time so as to achieve a predetermined transmittance. In this example, an aqueous iodine solution prepared by adding 0.2 part by weight of iodine and 1.0 part by weight of potassium iodide to 100 parts by weight of water was immersed for 60 seconds (dyeing treatment).

Next, the substrate was immersed in a crosslinking bath (an aqueous boric acid solution prepared by mixing 3 parts by weight of potassium iodide and 3 parts by weight of boric acid with respect to 100 parts by weight of water) at a liquid temperature of 30 ℃ for 30 seconds (crosslinking treatment).

Then, the laminate was immersed in an aqueous boric acid solution (an aqueous solution prepared by mixing 4 parts by weight of boric acid and 5 parts by weight of potassium iodide with respect to 100 parts by weight of water) at a liquid temperature of 70 ℃, and uniaxially stretched (stretched in an aqueous solution) between rolls having different peripheral speeds so that the total stretching ratio was 5.5 times in the longitudinal direction.

Then, the laminate was immersed in a cleaning bath (aqueous solution prepared by mixing 4 parts by weight of potassium iodide with 100 parts by weight of water) at a liquid temperature of 30 ℃ (cleaning treatment).

By the above operation, an optical film laminate including a polarizer having a thickness of 5 μm and a boric acid content of 16% was obtained. The boric acid content in the polarizer was measured by the following method.

The obtained polarizer was measured for a boric acid peak (665 cm) by attenuated total reflection spectroscopy (ATR) measurement using polarized light as measurement light, using a fourier transform infrared spectrophotometer (FTIR) (product name "spectra 2000" manufactured by Perkin Elmer corporation) ^-1 ) Strength of andcontrol Peak (2941 cm) ^-1 ) The strength of (2). From the obtained boric acid peak intensity and the control peak intensity, the boric acid amount index was calculated by the following formula, and further the boric acid content (% by weight) was determined from the calculated boric acid amount index by the following formula.

(boric acid amount index) = (boric acid peak 665 cm) ^-1 Intensity of (2)/(control Peak 2941 cm) ^-1 Strength of (2)

(boric acid content (% by weight)) = (boric acid amount index) × 5.54+4.1

(preparation of transparent protective film)

Transparent protective film: the easy-adhesion-treated surface of a (meth) acrylic resin film having a lactone ring structure and having a thickness of 40 μm was subjected to corona treatment and used.

(preparation of adhesive for transparent protective film)

An ultraviolet-curable adhesive was prepared by mixing 40 parts by weight of N-hydroxyethyl acrylamide (HEAA), 60 parts by weight of acryloyl morpholine (ACMO), and 3 parts by weight of a photoinitiator IRGACURE 819 (BASF corporation).

(preparation of Single-sided protective polarizing film)

The ultraviolet-curable adhesive is applied to the surface of the polarizer of the optical film laminate so that the thickness of the cured adhesive layer becomes 0.5 μm, the transparent protective film is bonded thereto, and then ultraviolet rays are irradiated as active energy rays to cure the adhesive. The ultraviolet irradiation uses a gallium-sealed metal halide lamp and an irradiation device: light HAMMER10 manufactured by Fusion UV Systems, valve: v valve, maximum illumination 1600mW/cm ² Cumulative dose of radiation 1000/mJ/cm ² (wavelength 380 to 440 nm) and the illuminance of ultraviolet light were measured by using Sola-Check system manufactured by Solatell corporation. Next, the amorphous PET substrate was peeled off, and a single-sided protective polarizing film using a thin polarizer was produced. When the monomer transmittance T and the degree of polarization P of the polarizer were measured by the following methods using the obtained one-side protective polarizing film, the monomer transmittance T of the polarizer was 42.8%, and the degree of polarization P of the polarizer was 99.99%.

The single transmittance T and the degree of polarization P of the polarizer of the obtained single-sided protective polarizing film were measured using a spectral transmittance measuring instrument with an integrating sphere (Dot-3 c, institute of color technology, village).

The degree of polarization P is determined by applying the transmittance (parallel transmittance: tp) when 2 identical single-side protective polarizing films are stacked so that the transmission axes thereof are parallel to each other and the transmittance (orthogonal transmittance: tc) when the two transmission axes are orthogonal to each other to the following equation. Polarization degree P (%) = { (Tp-Tc)/(Tp + Tc) } ^1/2 ×100

Each transmittance is a transmittance represented by a Y value measured in a 2-degree field of view (C light source) according to JIS Z8701 and corrected for visibility, assuming that the fully polarized light obtained after passing through the glan-taylor prism polarizer is 100%.

< preparation of double-sided protective polarizing film >

A polyvinyl alcohol film having a thickness of 80 μm was dyed in a 0.3% by weight iodine solution at 30 ℃ for 1 minute between rolls having different speed ratios while being stretched 3-fold. Then, the resultant was immersed in an aqueous solution containing boric acid at a concentration of 4% by weight and potassium iodide at a concentration of 10% by weight at 60 ℃ for 0.5 minute while performing stretching until the total stretching magnification became 6 times. Subsequently, the plate was immersed in an aqueous solution containing potassium iodide at a concentration of 1.5 wt% at 30 ℃ for 10 seconds to wash the plate, and then dried at 50 ℃ for 4 minutes to obtain a polarizer having a thickness of 30 μm. A cellulose triacetate film having a thickness of 80 μm and subjected to saponification treatment was bonded to both surfaces of the polarizer with a polyvinyl alcohol adhesive to prepare a two-sided protective polarizing film.

< formation of adhesive layer >

(preparation of acrylic adhesive 1)

A four-necked flask equipped with a stirrer, a thermometer, a nitrogen inlet, and a condenser was charged with a monomer mixture containing 89.78 parts of N-butyl acrylate, 8 parts of methyl methacrylate, 1.5 parts of N-vinylpyrrolidone, 0.2 part of acrylic acid, and 0.48 part of 4-hydroxybutyl acrylate. Further, 0.15 part of 2,2' -azobisisobutyronitrile as a polymerization initiator was added together with ethyl acetate to 100 parts of the monomer mixture (solid content), nitrogen gas was introduced while slowly stirring to replace nitrogen gas, and then the polymerization reaction was carried out for 7 hours while maintaining the liquid temperature in the flask at about 60 ℃. Then, ethyl acetate was added to the obtained reaction solution to prepare a solution of an acrylic polymer having a weight-average molecular weight of 130 ten thousand and a solid content concentration of 20%.

The weight average molecular weight (Mw) of the acrylic polymer was measured using a GPC apparatus (HLC-8220 GPC) manufactured by Tosoh corporation, and the measurement conditions were as follows.

Sample concentration: 0.2% by mass (THF solution)

Sample injection amount: 10 μ l

Eluent: THF (tetrahydrofuran)

Flow rate: 0.6ml/min

Measuring temperature: 40 deg.C

A chromatographic column: a sample column; TSKguardcolumn SuperHZ-H (1 root) + TSKgel SuperHZM-H (2 roots)

A reference column; TSKgel SuperH-RC (1 root)

A detector: differential Refractometer (RI)

The weight average molecular weight is determined by polystyrene conversion.

1.5 parts of lithium bis (trifluoromethanesulfonyl) imide (Mitsubishi Material Seiki Kabushiki Kaisha) and ethylmethylpyrrolidine were added to 100 parts of the solid content of the prepared acrylic polymer solution

1 part of bis (trifluoromethanesulfonyl) imide (manufactured by Tokyo chemical industry Co., ltd.), 0.25 part of an isocyanate-based crosslinking agent (manufactured by Mitsui chemical Co., ltd., trade name "Takenate D160N"), 0.25 part of a peroxide-based crosslinking agent (manufactured by Nippon fat and oil Co., ltd., trade name "NYPER BMT40 SV"), 0.1 part of a rework improver (manufactured by KANEKA, trade name "SAT 10"), 0.3 part of an antioxidant (manufactured by BASF Japan, trade name "Irganox 1010"), 0.2 part of an acetoacetylsilane-containing coupling agent (manufactured by Kagaku Co., ltd., trade name "A-100"), and an oligomer-type mercaptosilane-containing coupling agent (manufactured by shin-Etsu chemical industry Co., ltd.) (product ofTrade name "X-41-1810" manufactured by Kabushiki Kaisha) 0.2 parts by weight, an acrylic adhesive 1 was prepared.

(preparation of acrylic Adhesives 2 to 27)

In the preparation of the acrylic adhesive 1, acrylic polymer solutions were prepared in the same manner, and acrylic adhesives 2 to 27 were prepared, except that the monomer composition was changed as shown in table 1, the polymerization conditions were adjusted, and the kinds and amounts of additives were changed as shown in table 1.

(formation of adhesive layer)

Next, the prepared acrylic adhesives 1 to 27 were uniformly applied to the surfaces of polyethylene terephthalate films (diaphragms) treated with silicone-based release agents by a jet coater, and dried in an air-circulating oven at 155 ℃ for 1 minute to form adhesive layers on the surfaces of the diaphragms, respectively.

The compounds in table 1 are as follows.

BA: acrylic acid n-butyl ester

4HBA: acrylic acid 4-hydroxybutyl ester

AA: acrylic acid

NVP: n-vinyl pyrrolidone

MMA: methacrylic acid methyl ester

PEA: 2-Phenoxyethyl acrylate

NYPER BMT40SV: dibenzoyl peroxide

D160N: isocyanate crosslinking agent (manufactured by Sanjing chemical Co., ltd.)

D110N: isocyanate crosslinking agent (manufactured by Sanjing chemical Co., ltd.)

C/L: trimethylolpropane/tolylene diisocyanate adduct (product of Tosoh corporation, trade name "CORONATE L")

SAT10: re-operation improving agent (KANEKA corporation, product of Kaneka corporation)

And (3) LiTFSi: lithium bis (trifluoromethanesulfonyl) imide (manufactured by Mitsubishi Material electronics chemical Co., ltd.)

EMPTFSi: ethyl methyl pyrrolidine

Bis (trifluoromethanesulfonyl) imide (manufactured by Tokyo chemical industry)

Irganox 1010: antioxidant (BASF Japan K.K.)

A-100: coupling agent containing acetoacetylsilane (manufactured by Suzuki Kagaku Co., ltd.)

X-41-1810: oligomer-type mercapto-containing silane coupling agent (manufactured by shin-Etsu chemical Co., ltd.)

KBM-573: n-phenyl-3-aminopropyltrimethoxysilane (manufactured by shin-Etsu chemical Co., ltd.)

X-12-1156: oligomer type mercapto silane coupling agent (product of shin-Etsu chemical Co., ltd.)

X-40-9318: oligomer-type isocyanate-containing silane coupling agent (manufactured by shin-Etsu chemical Co., ltd.)

X-88-398: amino-containing silane coupling agent (manufactured by shin-Etsu chemical Co., ltd.)

KBM-6803: n-2- (aminoethyl) -8-Aminooctyltrimethoxysilane (manufactured by shin-Etsu chemical Co., ltd.)

X-12-5263H: multifunctional silane coupling agent containing amino alkoxy group (product of shin-Etsu chemical Co., ltd.)

X-12-981S: organosilane (manufactured by Xinyue chemical industry Co., ltd.)

X-12-1159L: oligomer type isocyanate-containing silane coupling agent (product of shin-Etsu chemical Co., ltd.)

X-12-1231: epoxy silane-containing coupling agent (product of shin-Etsu chemical Co., ltd.)

X-41-1056: oligomer-type epoxy-containing silane coupling agent (manufactured by shin-Etsu chemical Co., ltd.)

X-24-9591F: oligomer type silane coupling agent containing acid anhydride group (manufactured by shin-Etsu chemical Co., ltd.)

TMPS-E: amino-containing silane coupling agent (manufactured by shin-Etsu chemical Co., ltd.)

X-12-967C: 3-trimethoxysilylpropyl succinic anhydride (manufactured by shin-Etsu chemical Co., ltd.)

KBM-3086: alkoxy-containing polyfunctional silane coupling agent (product of shin-Etsu chemical Co., ltd.)

KBE-9007N: isocyanate-containing silane coupling agent (product of shin-Etsu chemical Co., ltd.)

KBM-803: 3-mercaptopropyltrimethoxysilane (manufactured by shin-Etsu chemical Co., ltd.)

X-12-1056ES: mercapto-containing silane coupling agent (manufactured by shin-Etsu chemical Co., ltd.)

KBM-403: 3-glycidoxypropyltrimethoxysilane (manufactured by shin-Etsu chemical Co., ltd.)

Examples 1 to 19 and comparative examples 1 to 11

< production of one-sided protective polarizing film with adhesive layer >

The adhesive layers thus prepared were bonded to the polarizer sides of the single-sided protective polarizing films thus prepared, respectively, to prepare single-sided protective polarizing films each having an adhesive layer.

< preparation of two-sided protective polarizing film with adhesive layer >

The adhesive layers were attached to one side of each of the two-sided protective polarizing films, and a two-sided protective polarizing film with an adhesive layer was produced.

The pressure-sensitive adhesive layer, the one-side protective polarizing film with a pressure-sensitive adhesive layer, and the both-side protective polarizing film with a pressure-sensitive adhesive layer obtained above were subjected to the following measurement and evaluation, and the results are shown in table 2.

< production inhibition of nanoslit: guitar pick test >

The pressure-sensitive adhesive layer-attached single-sided protective polarizing film and the pressure-sensitive adhesive layer-attached double-sided protective polarizing film thus produced were cut into a size of 50mm × 150mm (50 mm in the absorption axis direction), and this was designated as sample 11. Sample 11 was used after a surface protection film 6 produced by the following method was bonded to one side of the protection film 2.

(surface protective film for test)

Into a four-necked flask equipped with a stirrer, a thermometer, a nitrogen introduction tube, and a condenser, 94 parts by mass of 2-ethylhexyl acrylate (2 EHA), 1 part by mass of N, N-Diethylacrylamide (DEAA), 1 part by mass of ethoxydiglycol acrylate (EDE), 4 parts by mass of 4-hydroxybutyl acrylate (HBA), 0.2 part by mass of 2,2' -azobisisobutyronitrile as a polymerization initiator, and 150 parts by mass of ethyl acetate were charged, and nitrogen was introduced while slowly stirring, and the liquid temperature in the flask was maintained at about 60 ℃ to conduct a polymerization reaction for 5 hours, thereby preparing an acrylic polymer solution (40 mass%). The weight average molecular weight of the acrylic polymer was 57 ten thousand, and the glass transition temperature (Tg) was-68 ℃.

The acrylic polymer solution (40 mass%) was diluted with ethyl acetate to 20 mass%, and to 500 mass parts (100 mass parts of solid content) of the solution, 2 mass parts (2 mass parts of solid content) of an isocyanurate of hexamethylene diisocyanate (CORONATE HX: C/HX, manufactured by Nippon urethane industries Co., ltd.) and 2 mass parts (0.02 mass part of solid content) of dibutyltin dilaurate (1 mass% ethyl acetate solution) as a crosslinking catalyst were added and mixed with stirring to prepare an acrylic adhesive solution.

The acrylic pressure-sensitive adhesive solution was applied to a transparent polyethylene terephthalate (PET) film (polyester film) having a thickness of 38 μm, and heated at 130 ℃ for 1 minute to form a pressure-sensitive adhesive layer having a thickness of 15 μm, thereby producing a surface protective film.

Next, as shown in the schematic view of fig. 3 (a) and the cross-sectional view of fig. 3 (B), the release sheet (separator) was peeled from sample 11, and was adhered to glass plate 20 with adhesive layer 4 exposed. Next, a load of 200g was applied to the central portion of sample 11 (surface protective film 6 side) by a guitar pick (model "HP2H (HARD)" manufactured by hitory corporation), and a load of 50 round trips was repeated in a distance of 100mm in the direction perpendicular to the absorption axis of polarizer 1 of sample 11. The load was applied to 1 part. Further, the load was carried out at a high speed (7.5 m/min).

Next, after sample 11 was left to stand in an environment of 80 ℃ for 1 hour, the presence or absence of cracks due to light leakage in sample 11 was confirmed by the following criteria.

Excellent: 0 to 10

O: 11 to 30

X: more than 31

Fig. 4 is an example of a microscopic photograph showing the surface of a polarizing film, showing the following index of a crack (nano slit a) in a guitar pick test in which the pressure-sensitive adhesive layer-attached single-sided protective polarizing film 11 is confirmed. In fig. 4 (a), no crack of light leakage due to the nanoslit a was observed. On the other hand, fig. 4 (B) shows a case where 3 cracks of light leakage due to the nanoslits a are generated in the absorption axis direction of the polarizer by heating. In fig. 4, the sample in which the nano-slit is generated is observed by using a differential interference microscope. When a sample was photographed, a sample in which no nano-slit was generated was placed under a sample in which a nano-slit was generated (on the side of a transmission light source) so as to have an orthogonal nicol relationship, and observation was performed using transmission light.

< measurement of weight Change ratio >

The prepared adhesive layer (50 mg) was placed in a sample cage, the sample was set on a device balance, and then moisture adsorption/desorption measurement was performed using a moisture adsorption/desorption measurement device (IGA-Sorp, manufactured by Hiden). The measurement conditions are as follows. W obtained by measurement ₀ And W ₁ The weight change rate was calculated by substituting the following formula (1).

Drying (pretreatment for removing moisture in the adhesive layer): (100 ℃, dry, 1 hour)

The procedure is as follows: (23 ℃, dry, 2 hours) (W) ₀ ) → (23 ℃, 55% RH, 5 hours) → (60 ℃, 95% RH, 5 hours) (W ₁ ) → (23 ℃, 55% RH, 5 hours)

Measurement mode: sequence of

Weight change rate (%) = { (W) ₁ －W ₀ )/W ₀ }×100 (1)

W ₀ = weight of adhesive layer after drying the above adhesive layer at 23 ℃ for 2 hours

W ₁ = leaving the dried adhesive layer at 23 ℃ and 55 RH for 5 hours, and further 60 DEG C95% weight of the adhesive layer after standing at RH for 5 hours

< measurement of adhesive force and evaluation of peeling >

The prepared single-sided protective polarizing film with an adhesive layer and the prepared double-sided protective polarizing film with an adhesive layer were used as samples.

The sample was attached to the surface of an alkali-free glass plate using a laminator, and then, autoclave treatment was performed at 50 ℃ and 5atm for 15 minutes to completely adhere the sample. Then, the polarizing film was peeled from the surface of the alkali-free glass plate at a peeling temperature of 23 ℃, a peeling speed of 300mm/min and a peeling angle of 90 degrees using a re-handling apparatus, and the adhesive force P at this time was measured ₀ (N/25mm)。

The sample was attached to the surface of an alkali-free glass plate using a laminator, and then, autoclave treatment was performed at 50 ℃ and 5atm for 15 minutes to completely adhere the sample to the surface of the alkali-free glass plate, thereby obtaining a laminate. Then, the obtained laminate was immersed in water at 23 ℃ for 2 hours, and the laminate was taken out of the water. Then, the polarizing film was peeled from the surface of the alkali-free glass plate at a peeling temperature of 23 ℃, a peeling speed of 300mm/min and a peeling angle of 90 degrees by using a re-handling apparatus, and the adhesive force P at this time was measured ₁ (N/25mm)。

The obtained laminate was immersed in water at 23 ℃ for 5 hours, and the laminate was taken out of the water. Then, the polarizing film was peeled from the surface of the alkali-free glass plate at a peeling temperature of 23 ℃, a peeling speed of 300mm/min and a peeling angle of 90 degrees by using a re-handling apparatus, and the adhesive force P at this time was measured ₂ (N/25mm)。

The obtained laminate was immersed in water at 23 ℃ for 500 hours, and the laminate was taken out of the water. Then, the presence or absence of the peeling of the polarizing film was visually observed, and evaluated based on the following criteria.

Very good: no peeling was observed at all.

O: wrinkles were observed at the ends of the polarizing film.

X: significant peeling was observed.

< evaluation of durability >

The pressure-sensitive adhesive layer-attached single-side protective polarizing film and the pressure-sensitive adhesive layer-attached double-side protective polarizing film (15 inch) were peeled off, and then bonded to alkali-free glass (EG-XG, manufactured by corning) having a thickness of 0.7mm using a laminator. Then, the polarizing film was completely adhered to the alkali-free glass by autoclave treatment at 50 ℃ and 0.5MPa for 15 minutes. Then, the polarizing plates were put into a heating oven (heating) at 80 ℃ and a constant temperature and humidity machine (humidifying) at 60 ℃/90% RH, and the presence or absence of peeling of the polarizing plates after 500 hours was evaluated according to the following criteria.

Very good: peeling was not observed at all.

O: peeling was observed to an extent not visually confirmed.

And (delta): a small peel was observed, which was identifiable to the naked eye.

X: significant peeling was observed.

< evaluation of conductive stability >

After the one-side protective polarizing film with an adhesive layer and the separators of the both-side protective polarizing films with adhesive layers were peeled, the surface resistance value of the adhesive surface was measured using MCP-HT450 manufactured by Mitsubishi chemical analysis corporation (omega/\9633;). After the polarizing film was stored in a humidified environment at 60 ℃/90% rh for 500 hours, the surface resistance value of the adhesive surface was also measured in the same manner as described above. The change rate (%) of the surface resistance value was calculated by the following formula and evaluated based on the following criteria.

Change rate Δ R (%) = (surface resistance value after storage) × 100/(surface resistance value before storage)

(evaluation criteria)

○：0≤ΔR＜500

△：500≤ΔR＜700

×：700≤ΔR

Industrial applicability

The pressure-sensitive adhesive layer-attached single-sided protective polarizing film of the present invention can be used alone or as an optical film laminated to an image display device such as a Liquid Crystal Display (LCD) or an organic EL display.

Claims

1. A single-sided protective polarizing film with an adhesive layer, which has a single-sided protective polarizing film having a protective film only on one side of a polarizer and has an adhesive layer directly or via a coating layer on the polarizer side of the single-sided protective polarizing film,

the adhesive layer contains a (meth) acrylic polymer as a base polymer,

the (meth) acrylic polymer contains, as monomer units:

60% by weight or more of (meth) acrylic acid alkyl ester (A) having a glass transition temperature of a homopolymer of less than 0 ℃, and

0.1 to 20 wt% of at least one high Tg monomer (B) selected from an alkyl (meth) acrylate (B1) having a homopolymer glass transition temperature of 0 ℃ or higher and a (meth) acryloyl group-containing monomer (B2) having a homopolymer glass transition temperature of 0 ℃ or higher and a heterocycle,

the weight change rate of the adhesive layer calculated by the following formula (1) is 1.1% or more,

the adhesive force P of the adhesive layer under the following conditions ₀ Is 10N/25mm or less and has an adhesive force P under the following conditions ₁ Is more than 1.6N/25mm,

weight change rate (%) = { (W) ₁ －W ₀ )/W ₀ }×100 (1)

W ₀ = weight of adhesive layer after drying the adhesive layer at 23 ℃ for 2 hours,

W ₁ (ii) = the weight of the pressure-sensitive adhesive layer after leaving the dried pressure-sensitive adhesive layer at 23 ℃, 55% RH for 5 hours, further at 60 ℃, 95% RH for 5 hours,

adhesive force P ₀ : the adhesive layer of the single-sided protective polarizing film with the adhesive layer is adhered toAn alkali-free glass surface, an autoclave treatment for 15 minutes at 50 ℃ and 0.5atm, and a pressure-sensitive adhesive layer peeled from the alkali-free glass surface at a peeling temperature of 23 ℃, a peeling speed of 300mm/min and a peeling angle of 90 degrees,

adhesive force P ₁ : the pressure-sensitive adhesive layer of the one-side protective polarizing film with a pressure-sensitive adhesive layer was adhered to the surface of an alkali-free glass, and then autoclave treatment was performed for 15 minutes under conditions of 50 ℃ and 0.5atm, the obtained laminate was immersed in water at 23 ℃ for 2 hours, the laminate was taken out of the water, and then the pressure-sensitive adhesive layer was peeled from the surface of the alkali-free glass under conditions of a peeling temperature of 23 ℃, a peeling speed of 300mm/min, and a peeling angle of 90 degrees.

2. The adhesive layer-bearing single-sided protective polarizing film according to claim 1,

the (meth) acrylic polymer contains, as a monomer unit, a polar monomer other than the (meth) acryloyl group-containing monomer (b 2), and the polar monomer is at least one selected from a nitrogen-containing monomer, a carboxyl group-containing monomer, a hydroxyl group-containing monomer, and an aromatic group-containing monomer.

3. The adhesive layer-bearing single-sided protective polarizing film according to claim 2,

the nitrogen-containing monomer is a vinyl monomer with a lactam ring.

4. The adhesive layer-bearing single-sided protective polarizing film according to claim 3,

the vinyl monomer with a lactam ring is a vinyl pyrrolidone monomer.

5. The adhesive layer-bearing single-sided protective polarizing film according to claim 4,

the vinyl pyrrolidone monomer is N-vinyl pyrrolidone.

6. The adhesive layer-bearing single-sided protective polarizing film according to claim 2,

the (meth) acrylic polymer contains 0.1 to 5% by weight of the nitrogen-containing monomer as a monomer unit.

7. The adhesive layer-bearing single-sided protective polarizing film according to claim 2,

the (meth) acrylic polymer contains 0.01 to 3% by weight of the carboxyl group-containing monomer as a monomer unit.

8. The adhesive layer-bearing single-sided protective polarizing film according to claim 2,

the (meth) acrylic polymer contains 0.01 to 1% by weight of the hydroxyl group-containing monomer as a monomer unit.

9. The adhesive layer-bearing single-sided protective polarizing film according to claim 2,

the (meth) acrylic polymer contains 1 to 20% by weight of the aromatic group-containing monomer as a monomer unit.

10. The adhesive layer-bearing single-sided protective polarizing film according to claim 1,

the weight average molecular weight of the (meth) acrylic polymer is 150 ten thousand or less.

11. The adhesive layer-bearing single-sided protective polarizing film according to claim 1,

the adhesive layer contains a silane coupling agent having at least 1 functional group selected from an epoxy group, an isocyanate group, a mercapto group, an acid anhydride group, and an amino group.

12. The adhesive layer-bearing single-sided protective polarizing film according to claim 11,

the silane coupling agent is contained in an amount of 0.01 to 3 parts by weight based on 100 parts by weight of the (meth) acrylic polymer.

13. The adhesive layer-bearing single-sided protective polarizing film according to claim 1,

the thickness of the polarizer is less than 12 μm.

14. The adhesive layer-bearing single-sided protective polarizing film according to claim 1,

the polarizer contains a polyvinyl alcohol resin, and is configured such that optical characteristics represented by a monomer transmittance T and a polarization degree P satisfy the following conditions:

P＞－(10 ^0.929T-42.4 -1) x 100, wherein T < 42.3, or

P is more than or equal to 99.9, wherein T is more than or equal to 42.3.

15. The adhesive layer-equipped one-side protective polarizing film according to claim 1, wherein the polarizer contains 25 wt% or less of boric acid with respect to the total amount of polarizers.

16. The adhesive layer-equipped single-sided protective polarizing film according to any one of claims 1 to 15,

a separator is disposed on the adhesive layer.

17. The adhesive layer-bearing single-sided protective polarizing film according to claim 16, which is a roll.

18. An image display device having the adhesive layer-equipped single-sided protective polarizing film of any one of claims 1 to 15.

19. A method for continuously manufacturing an image display device, comprising the steps of:

the pressure-sensitive adhesive layer-equipped one-side protective polarizing film continuously fed from the roll of pressure-sensitive adhesive layer-equipped one-side protective polarizing film described in claim 17 and conveyed by the separator is continuously bonded to the surface of an image display panel via the pressure-sensitive adhesive layer.