JP2019200423A - Liquid crystal panel with touch sensing function and liquid crystal display - Google Patents

Abstract

To provide a liquid crystal panel with a touch sensing function that can satisfy a stable antistatic function even in a humidified environment.SOLUTION: In a liquid crystal panel having a touch sensing function built therein comprising: a first polarization film that is arranged on a visible side of the liquid crystal cell having a touch sensing function built therein and a second polarization film that is arranged on the opposite side of the visible side and a first adhesive layer that is arranged between the first polarization film and the liquid crystal cell, the first adhesive layer is formed of a (meth)acrylic polymer (A) that contains alkyl (meth)acrylate (a1) and an amide group-containing monomer (a2) as a monomer unit and an adhesive composition that contains an ionic compound (B), and has a small change in surface resistance value in a humidified environment.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a liquid crystal panel with a touch sensing function and a liquid crystal display device. The liquid crystal display device with a touch sensing function of the present invention can be used as various input display devices such as mobile devices.

  In a liquid crystal display device, generally, a polarizing film is bonded to both sides of a liquid crystal cell via an adhesive layer from the image forming method. In addition, a liquid crystal display device in which a touch panel is mounted on a display screen has been put into practical use. There are various types of touch panels such as a capacitance type, a resistance film type, an optical method, an ultrasonic method, and an electromagnetic induction type, but the capacitance type is increasingly adopted. In recent years, a liquid crystal display device with a touch sensing function that incorporates a capacitance sensor as a touch sensor unit has been used.

  On the other hand, at the time of manufacturing the liquid crystal display device, when the polarizing film with the pressure-sensitive adhesive layer is attached to the liquid crystal cell, the release film is peeled off from the pressure-sensitive adhesive layer of the polarizing film with the pressure-sensitive adhesive layer. Static electricity is generated by peeling. The static electricity generated in this way affects the alignment of the liquid crystal layer inside the liquid crystal display device, leading to defects. Generation of static electricity can be suppressed, for example, by forming an antistatic layer on the outer surface of the polarizing film.

On the other hand, the capacitance sensor in the liquid crystal display device with a touch sensing function detects a weak capacitance formed by the transparent electrode pattern and the finger when the finger of the user approaches the surface. When a conductive layer such as an antistatic layer is provided between the transparent electrode pattern and the user's finger, the electric field between the drive electrode and the sensor electrode is disturbed, the sensor electrode capacitance becomes unstable, and the touch panel sensitivity Lowers, causing malfunction. In the liquid crystal display device with a touch sensing function, it is required to suppress the generation of static electricity and to suppress malfunction of the capacitance sensor. For example, in the liquid crystal display device with a touch sensing function, the surface resistance value is 1.0 × 10 ^{9 to} 1.0 × 10 ¹¹ Ω / □ in order to reduce the occurrence of display defects and malfunctions. It has been proposed to dispose a polarizing film having an antistatic layer on the viewing side of the liquid crystal layer (Patent Document 1).

  In addition, pressure-sensitive adhesives for optical films having an antistatic function have been proposed for the purpose of preventing unevenness of a liquid crystal panel due to static electricity and preventing adhesion of foreign substances.

JP2013-105154A

  According to the polarizing film having the antistatic layer described in Patent Document 1, it is possible to suppress the generation of static electricity to some extent. However, in Patent Document 1, since the place where the antistatic layer is disposed is farther from the fundamental position where static electricity is generated, it is not as effective as when an antistatic function is imparted to the adhesive layer.

  Moreover, the pressure-sensitive adhesive layer containing an ionic compound is more effective in preventing static electricity unevenness by suppressing the generation of static electricity than the antistatic layer provided on the polarizing film. However, it was found that the antistatic function of the pressure-sensitive adhesive layer containing an ionic compound deteriorates with time. In particular, in a humidified environment (after a humidification reliability test), ionic compounds in the pressure-sensitive adhesive layer segregate at the interface with the optical film (polarizing film) or migrate into the optical film (polarizing film). It was found that the surface resistance value of the pressure-sensitive adhesive layer was increased, and the antistatic function was significantly reduced. It has been found that such a decrease in the antistatic function of the pressure-sensitive adhesive layer causes static electricity unevenness and malfunction of the liquid crystal display device with a touch sensing function.

  The present invention is a liquid crystal panel with a touch sensing function in which an optical film is bonded to the viewing side of a liquid crystal cell with a built-in touch sensing function with an adhesive layer containing an ionic compound, which is stable even in a humidified environment. An object of the present invention is to provide a liquid crystal panel with a touch sensing function that can satisfy the antistatic function. Furthermore, it aims at providing the liquid crystal display device using the said liquid crystal panel.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by the following liquid crystal panel with a touch sensing function, and have completed the present invention.

That is, the present invention
A liquid crystal cell with a touch sensing function having a liquid crystal layer and a touch sensor,
A first polarizing film disposed on the viewing side of the liquid crystal cell and a second polarizing film disposed on the opposite side of the viewing side; and
In the liquid crystal panel with a built-in touch sensing function, having a first adhesive layer disposed between the first polarizing film and the liquid crystal cell,
The first pressure-sensitive adhesive layer contains, as monomer units, a (meth) acrylic polymer (A) containing an alkyl (meth) acrylate (a1) and an amide group-containing monomer (a2), and an ionic compound (B). Formed from an adhesive composition, and
The first pressure-sensitive adhesive layer has a surface resistance value variation ratio (b / a) ≦ 5, where the a is provided with the first pressure-sensitive adhesive layer on the first polarizing film, and The surface resistance value of the first pressure-sensitive adhesive layer when the separator is peeled off immediately after producing the first polarizing film with the pressure-sensitive adhesive layer in a state where the separator is provided on the pressure-sensitive adhesive layer, and b is the pressure-sensitive adhesive layer. The first polarizing film is put in a humidified environment of 60 ° C./95% RH for 250 hours, further dried at 40 ° C. for 1 hour, and then the surface resistance value of the first pressure-sensitive adhesive layer when the separator is peeled off The liquid crystal panel with a built-in touch sensing function is characterized by satisfying the following.

  In the touch sensing function built-in liquid crystal panel, the amide group-containing monomer (a2) is preferably an N-vinyl group-containing lactam monomer.

  In the touch sensing function built-in liquid crystal panel, the amide group-containing monomer (a2) is preferably contained in the (meth) acrylic polymer (A) in an amount of 0.1% by weight or more as a monomer unit.

  In the touch sensing function built-in liquid crystal panel, the ionic compound (B) is preferably an alkali metal salt. The ionic compound (B) is preferably contained in an amount of 0.01 parts by weight or more with respect to 100 parts by weight of the (meth) acrylic polymer (A).

  The liquid crystal panel with a built-in touch sensing function is suitably applied when the touch sensor unit and the first adhesive layer are in direct contact.

  The present invention also relates to a liquid crystal display device having the touch sensing function built-in liquid crystal panel.

  In the panel with a built-in touch sensing function of the present invention, the first pressure-sensitive adhesive layer provided between the liquid crystal cell containing the touch sensor portion and the first polarizing film disposed on the viewing side of the liquid crystal cell has an amide as a monomer unit. It is formed from a pressure-sensitive adhesive composition containing a (meth) acrylic polymer (A) containing a group-containing monomer (a2) and an ionic compound (B). The first pressure-sensitive adhesive layer contains the ionic compound (B), and the surface resistance value of the first pressure-sensitive adhesive layer can be reduced to suppress the generation of static electricity.

  Moreover, in the 1st adhesive layer, the amide group introduce | transduced into the side chain in the (meth) acrylic-type polymer (A) which is a base polymer exists. Due to the presence of the amide group, the surface resistance value of the first pressure-sensitive adhesive layer adjusted by blending the ionic compound (B) is suppressed from fluctuating and increasing even in a humidified environment. Can be maintained within the range. Compatibility of (meth) acrylic polymer (A) and ionic compound (B) due to the presence of an amide group introduced as a functional group of a copolymerization monomer in the side chain in (meth) acrylic polymer (A) Is thought to rise. As a result, even in a humidified environment, the ionic compound (B) in the first pressure-sensitive adhesive layer is prevented from being segregated and transferred to the interface of the polarizing film or the like, and the first pressure-sensitive adhesive layer has a desired surface resistance value. It is considered that the value could be maintained within the range. According to such a liquid crystal panel with a touch sensing function having the first pressure-sensitive adhesive layer of the present invention, unevenness due to generation of static electricity can be suppressed, and malfunction can be prevented from occurring. It is considered that the decrease could be suppressed. The liquid crystal panel with a touch sensing function of the present invention is particularly suitable when an in-cell type liquid crystal cell or an on-cell type liquid crystal cell is used as the touch sensing function built-in liquid crystal cell.

  Moreover, since the amide group introduced into the side chain in the (meth) acrylic polymer (A) which is the base polymer is present in the pressure-sensitive adhesive layer, the glass and the transparent conductive layer (ITO layer or the like) In any case, the durability is good, and it is possible to suppress the occurrence of peeling or floating in a state of being attached to the liquid crystal panel. In addition, durability can be satisfied even in a humidified environment (after a humidification reliability test).

It is sectional drawing which shows an example of the liquid crystal panel with a touch sensing function of this invention. It is sectional drawing which shows an example of the liquid crystal panel with a touch sensing function of this invention. It is sectional drawing which shows an example of the liquid crystal panel with a touch sensing function of this invention.

  The liquid crystal panel with a built-in touch sensing function of the present invention will be described with reference to the drawings. The liquid crystal panel with a built-in touch sensing function of the present invention is disposed on the opposite side of the viewing side from the liquid crystal cell C having the liquid crystal layer 3 and the touch sensor unit 5, the first polarizing film 11 disposed on the viewing side of the liquid crystal cell C. The second polarizing film 12 and the first pressure-sensitive adhesive layer 21 disposed between the first polarizing film 11 and the liquid crystal cell C are included. The respective configurations of the liquid crystal panel with a built-in touch sensing function of the present invention can be simply shown as the first polarizing film 11 / the first adhesive layer 21 / the liquid crystal cell C / the second polarizing film 12 from the viewing side. it can. In the touch sensing function built-in liquid crystal panel, the order of the components is simply shown, but other components can be appropriately provided between the components.

  Specific examples of the liquid crystal panel with a built-in touch sensing function of the present invention are shown in FIGS. 1 to 3, for example.

  FIG. 1 shows a so-called in-cell type liquid crystal panel with a built-in touch sensing function. From the viewing side, the first polarizing film 11 / first adhesive layer 21 / first transparent substrate 41 / touch sensor unit 5 / liquid crystal layer 3 / It has the structure of drive electrode and sensor part 6 / second transparent substrate 42 / second adhesive layer 22 / second polarizing film 12. In the in-cell type liquid crystal panel with a touch sensing function of FIG. 1, for example, the liquid crystal cell C is in the first and second glass substrates 41 and 42 (in the liquid crystal cell) sandwiching the liquid crystal layer 3. Part 6.

  FIG. 2 is a modified example of the so-called in-cell type (semi-in-cell type) liquid crystal panel with a built-in touch sensing function. From the viewing side, the first polarizing film 11 / the first adhesive layer 21 / the touch sensor unit 5 / the first 1 transparent substrate 41 / liquid crystal layer 3 / drive electrode and sensor unit 6 / second transparent substrate 42 / second pressure-sensitive adhesive layer 22 / second polarizing film 12. In the in-cell type liquid crystal panel with a touch sensing function of FIG. 2, for example, the liquid crystal cell C is outside the first transparent substrate 41, the touch sensor unit 5 is in direct contact with the first adhesive layer 21, and sandwiches the liquid crystal layer 3. The drive electrode and sensor unit 6 is provided on the second transparent substrate 42 side in the first and second glass substrates 41 and 42 (in the liquid crystal cell).

  FIG. 3 shows a so-called on-cell type liquid crystal panel with a built-in touch sensing function. From the viewing side, the first polarizing film 11 / the first adhesive layer 21 / the touch sensor unit 5 / the driving electrode / sensor unit 6 / the first 1 transparent substrate 41 / liquid crystal layer 3 / drive electrode 7 / second transparent substrate 42 // second pressure-sensitive adhesive layer 22 / second polarizing film 12. 3, for example, the liquid crystal cell C has the touch sensor unit 5 and the drive electrode / sensor unit 6 outside the first transparent substrate 41, and the touch sensor unit 5 is the first sensor unit. Directly in contact with the pressure-sensitive adhesive layer 21, the drive electrode 7 is provided on the second transparent substrate 42 side in the first and second glass substrates 41 and 42 (in the liquid crystal cell) sandwiching the liquid crystal layer 3.

  In the liquid crystal panel with a built-in touch sensing function, when the touch sensor portion 5 of the liquid crystal cell C and the first adhesive layer 21 are in direct contact with each other, the first adhesive layer 21 (containing an ionic compound) is prevented from being charged. The function is likely to deteriorate, particularly in a humidified and humid environment. Therefore, the liquid crystal panel with a built-in touch sensing function of the present invention is preferably applied to the in-cell type (modified example) shown in FIG. 2 or the on-cell type liquid crystal panel with a built-in touch sensing function shown in FIG.

  As for the 1st polarizing film 11 and the 2nd polarizing film 12, what has a transparent protective film in the single side | surface or both surfaces of a polarizer is generally used. The 1st polarizing film 11 and the 2nd polarizing film 12 are arrange | positioned so that a transmission axis (or absorption axis) may orthogonally cross on both sides of the liquid crystal layer 3. FIG.

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

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

  As a material constituting the transparent protective film, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy and the like is used. Specific examples of such thermoplastic resins include cellulose resins such as triacetyl cellulose, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth) acrylic resins, cyclic Examples include polyolefin resins (norbornene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. A transparent protective film is bonded to one side of the polarizer by an adhesive layer. On the other side, as a transparent protective film, (meth) acrylic, urethane-based, acrylurethane-based, epoxy-based, silicone A thermosetting resin such as a system or an ultraviolet curable resin can be used.

  As a material for the transparent protective film, cellulose resin, (meth) acrylic resin can be used because the variation ratio (b / a) of the surface resistance value of the first pressure-sensitive adhesive layer provided on the transparent protective film can be controlled to be small. Is preferred. In particular, a (meth) acrylic resin is preferable in that the variation ratio (b / a) of the surface resistance value of the first pressure-sensitive adhesive layer can be controlled to be smaller than that of the cellulose resin. As the (meth) acrylic resin, it is preferable to use a (meth) acrylic resin having a lactone ring structure. Examples of the (meth) acrylic resin having a lactone ring structure include JP 2000-230016, JP 2001-151814, JP 2002-120326, JP 2002-254544, and JP 2005. Examples thereof include (meth) acrylic resins having a lactone ring structure described in Japanese Patent No. 146084.

  A functional layer such as a hard coat layer, an antireflection layer, an antisticking layer, a diffusion layer or an antiglare layer can be provided on the surface of the transparent protective film to which the polarizer is not adhered.

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

  In addition, the 1st polarizing film 11 arrange | positioned at the visual recognition side of the liquid crystal cell C, and the 2nd polarizing film 12 arrange | positioned at the opposite side of the said visual recognition side are other optical films according to the suitability of each arrangement | positioning location. It can be used by laminating. Examples of the other optical films include liquid crystal display devices such as a reflection plate, an anti-transmission plate, a retardation film (including wavelength plates such as 1/2 and 1/4), a visual compensation film, and a brightness enhancement film. And an optical layer that may be used in the above. These can be used as one layer or two or more layers. Even when these other optical films are used, the pressure-sensitive adhesive layer closest to the liquid crystal layer 3 is preferably the first pressure-sensitive adhesive layer 21.

  The first pressure-sensitive adhesive layer 21 contains, as monomer units, a (meth) acrylic polymer (A) containing an alkyl (meth) acrylate (a1) and an amide group-containing monomer (a2), and an ionic compound (B). It is formed from an adhesive composition. Details of the pressure-sensitive adhesive composition will be described later.

  The 2nd adhesive layer 22 is formed from an adhesive. As the pressure-sensitive adhesive, various pressure-sensitive adhesives can be used, for example, rubber-based pressure-sensitive adhesives, acrylic pressure-sensitive adhesives, silicone-based pressure-sensitive adhesives, urethane-based pressure-sensitive adhesives, vinyl alkyl ether-based pressure-sensitive adhesives, polyvinylpyrrolidone-based pressure-sensitive adhesives, A polyacrylamide type adhesive, a cellulose adhesive, etc. are mentioned. An adhesive base polymer is selected according to the type of the adhesive. Among the pressure-sensitive adhesives, acrylic pressure-sensitive adhesives are preferably used because they are excellent in optical transparency, exhibit appropriate wettability, cohesiveness, and adhesive pressure-sensitive adhesive properties, and are excellent in weather resistance and heat resistance. The The thickness in particular of the 2nd adhesive layer 22 is not restrict | limited, For example, it is about 1-100 micrometers. Preferably, it is 2-50 micrometers, More preferably, it is 2-40 micrometers, More preferably, it is 5-35 micrometers.

  The liquid crystal layer 3 included in the liquid crystal cell C is a liquid crystal layer including liquid crystal molecules that are homogeneously aligned in the absence of an electric field, which is applied to a liquid crystal panel with a built-in touch sensing function. For example, an IPS liquid crystal layer is preferably used as the liquid crystal layer 3. In addition, as the liquid crystal layer 3, for example, any type of liquid crystal layer of TN type, STN type, π type, VA type or the like can be used. The thickness of the liquid crystal layer is, for example, about 1.5 μm to 4 μm.

  In the liquid crystal cell C, the first transparent substrate 41 and the second transparent substrate 42 can form a liquid crystal cell with the liquid crystal layer 3 interposed therebetween. Inside or outside the liquid crystal cell, a touch sensor unit 5, a drive electrode / sensor unit 6, a drive electrode 7 and the like are formed according to the form of the liquid crystal panel with a built-in touch sensing function. A color filter substrate can be provided on the liquid crystal cell (first transparent substrate 41).

  Examples of the material forming the transparent substrate include glass and polymer films. Examples of the polymer film include polyethylene terephthalate, polycycloolefin, and polycarbonate. When the transparent substrate is made of glass, the thickness is, for example, about 0.3 mm to 1 mm. When the transparent substrate is formed of a polymer film, the thickness is, for example, about 10 μm to 200 μm. The said transparent substrate can have an easily bonding layer and a hard-coat layer on the surface.

  The touch sensor unit 5 (capacitance sensor), the drive electrode / sensor unit 6, and the drive electrode 7 are formed as a transparent conductive layer. The constituent material of the transparent conductive layer is not particularly limited. For example, gold, silver, copper, platinum, palladium, aluminum, nickel, chromium, titanium, iron, cobalt, tin, magnesium, tungsten, and the like An alloy etc. are mentioned. Examples of the constituent material of the transparent conductive layer include metal oxides of indium, tin, zinc, gallium, antimony, zirconium, and cadmium. Specifically, indium oxide, tin oxide, titanium oxide, cadmium oxide, and these And metal oxides made of a mixture of these. In addition, other metal compounds such as copper iodide are used. The metal oxide may further include an oxide of a metal atom shown in the above group, if necessary. For example, indium oxide (ITO) containing tin oxide and tin oxide containing antimony are preferably used, and ITO is particularly preferably used. As ITO, it is preferable to contain 80 to 99 weight% of indium oxide and 1 to 20 weight% of tin oxide.

  There is no restriction | limiting in the location in which the touch sensor layer 5 is formed in the liquid crystal cell C, The touch sensor layer 5 is formed according to the form of a liquid crystal panel with a built-in touch sensing function. For example, in FIGS. 1 to 3, the touch sensor layer 5 is illustrated as being disposed between the first polarizing film 11 and the liquid crystal layer 3. The touch sensor layer 5 can be formed as a transparent electrode pattern on the first transparent substrate 41, for example. Also for the drive electrode / sensor unit 6 and the drive electrode 7, a transparent electrode pattern can be formed according to a conventional method according to the form of the liquid crystal panel with a built-in touch sensing function. The transparent electrode pattern is usually electrically connected to a lead line (not shown) formed at the end of the transparent substrate, and the lead line is connected to a controller IC (not shown). As the shape of the transparent electrode pattern, an arbitrary shape such as a stripe shape or a rhombus shape can be adopted in addition to the comb shape. The height of the transparent electrode pattern is, for example, 10 nm to 100 nm, and the width is 0.1 mm to 5 mm.

  In addition, the liquid crystal panel with a built-in touch sensing function can appropriately use a member that forms a liquid crystal display device such as a backlight using a backlight or a reflector in the lighting system.

  Below, the adhesive composition which forms the 1st adhesive layer 21 is demonstrated. The pressure-sensitive adhesive composition contains an alkyl (meth) acrylate (a1) and a (meth) acrylic polymer (A) containing an amide group-containing monomer (a2), and an ionic compound (B). (Meth) acrylate refers to acrylate and / or methacrylate, and (meth) of the present invention has the same meaning.

  The (meth) acrylic polymer (A) contains alkyl (meth) acrylate (a1) as a main component as a monomer unit. Examples of the alkyl (meth) acrylate constituting the main skeleton of the (meth) acrylic polymer (A) include linear or branched alkyl groups having 1 to 18 carbon atoms. For example, the alkyl group includes methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, amyl group, hexyl group, cyclohexyl group, heptyl group, 2-ethylhexyl group, isooctyl group, nonyl group, decyl group. Group, isodecyl group, dodecyl group, isomyristyl group, lauryl group, tridecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, and the like. These can be used alone or in combination. The average carbon number of these alkyl groups is preferably 3-9.

  The weight ratio of the alkyl (meth) acrylate (a1) is 70% by weight or more in the weight ratio of all the constituent monomers (100% by weight) constituting the (meth) acrylic polymer (A) as the monomer unit. preferable. The weight ratio of the alkyl (meth) acrylate (a1) can be considered as the balance of the amide group-containing monomer (a2) and other copolymerization monomers. Setting the weight ratio of the alkyl (meth) acrylate (a1) within the above range is preferable for securing the adhesiveness.

  The amide group-containing monomer (a2) is a compound containing an amide group in its structure and a polymerizable unsaturated double bond such as a (meth) acryloyl group or a vinyl group. Specific examples of the amide group-containing monomer (a2) include (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N-isopropylacrylamide, and N-methyl (meth) acrylamide. , N-butyl (meth) acrylamide, N-hexyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methylol-N-propane (meth) acrylamide, aminomethyl (meth) acrylamide, aminoethyl (meth) acrylamide , Acrylamide monomers such as mercaptomethyl (meth) acrylamide, mercaptoethyl (meth) acrylamide; N- (meth) acryloylmorpholine, N- (meth) acryloylpiperidine, N- (meth) acryloylpyrrolidine, etc. - acryloyl heterocyclic monomers; N- vinylpyrrolidone, N- vinyl-containing lactam monomers such as N- vinyl -ε- caprolactam. The amide group-containing monomer (a2) is preferable for suppressing an increase in surface resistance value with time (particularly in a humidified environment) and satisfying durability. In particular, among the amide group-containing monomers (a2), particularly N-vinyl group-containing lactam monomers can suppress an increase in surface resistance over time (especially in a humidified environment) It is preferable to satisfy the durability against the sensor layer. Although not exemplified above, the amide group-containing monomer having a hydroxyl group tends to improve conductivity in combination with the ionic compound (B), and when the use ratio increases, the polarizing film ( It is preferable not to use it because there is a problem with the throwing force with the optical film) and the reworkability with the transparent conductive layer (touch sensor layer).

  The weight ratio of the amide group-containing monomer (a2) is preferably 0.1% by weight or more from the viewpoint of suppressing an increase in surface resistance value over time (particularly in a humidified environment). The weight ratio is preferably 0.3% by weight or more, and more preferably 0.5% by weight or more. On the other hand, if the weight ratio is too large, the anchoring property to a base film such as a polarizing film tends to be lowered. Therefore, the weight ratio is preferably 35% by weight or less, and more preferably 30% by weight or less. More preferably, it is preferably 25% by weight or less.

  In the (meth) acrylic polymer (A), in addition to the monomer unit, a polymer having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group for the purpose of improving adhesiveness and heat resistance. One or more kinds of copolymerization monomers having a functional group can be introduced by copolymerization.

  As the copolymerization monomer, for example, an aromatic ring-containing (meth) acrylate can be used. An aromatic ring-containing (meth) acrylate is a compound containing an aromatic ring structure in its structure and a (meth) acryloyl group. Examples of the aromatic ring include a benzene ring, a naphthalene ring, and a biphenyl ring.

  Specific examples of the aromatic ring-containing (meth) acrylate include, for example, benzyl (meth) acrylate, phenyl (meth) acrylate, o-phenylphenol (meth) acrylate phenoxy (meth) acrylate, phenoxyethyl (meth) acrylate, and phenoxypropyl. (Meth) acrylate, phenoxydiethylene glycol (meth) acrylate, ethylene oxide modified nonylphenol (meth) acrylate, ethylene oxide modified cresol (meth) acrylate, phenol ethylene oxide modified (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) Acrylate, methoxybenzyl (meth) acrylate, chlorobenzyl (meth) acrylate, cresyl (meth) acrylate, polystyryl ( A) Having a benzene ring such as acrylate; hydroxyethylated β-naphthol acrylate, 2-naphthoethyl (meth) acrylate, 2-naphthoxyethyl acrylate, 2- (4-methoxy-1-naphthoxy) ethyl (meth) acrylate And those having a naphthalene ring such as biphenyl (meth) acrylate.

  As the aromatic ring-containing (meth) acrylate, benzyl (meth) acrylate and phenoxyethyl (meth) acrylate are preferable, and phenoxyethyl (meth) acrylate is particularly preferable from the viewpoint of adhesive properties and durability.

  The weight ratio of the aromatic ring-containing (meth) acrylate is preferably 25% by weight or less, more preferably 3 to 25% by weight, further preferably 8 to 22% by weight, and further 12 to 18% by weight. Is preferred. When the weight ratio of the aromatic ring-containing (meth) acrylate is 3% by weight or more, it is preferable for suppressing display unevenness. On the other hand, if it exceeds 25% by weight, the suppression of display unevenness is not sufficient, and the durability tends to decrease.

  Examples of the copolymerization monomer include a carboxyl group-containing monomer and a hydroxyl group-containing monomer.

  The carboxyl group-containing monomer is a compound containing a carboxyl group in its structure and a polymerizable unsaturated double bond such as a (meth) acryloyl group or a vinyl group. Specific examples of the carboxyl group-containing monomer include (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid and the like. Among the carboxyl group-containing monomers, acrylic acid is preferable from the viewpoints of copolymerizability, cost, and adhesive properties.

  The hydroxyl group-containing monomer is a compound containing a hydroxyl group in its structure and a polymerizable unsaturated double bond such as a (meth) acryloyl group or a vinyl group. Specific examples of the hydroxyl group-containing monomer include, for example, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8- Examples include hydroxyalkyl (meth) acrylate and (4-hydroxymethylcyclohexyl) -methyl acrylate, such as hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, and 12-hydroxylauryl (meth) acrylate. Among the hydroxyl group-containing monomers, 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate are preferable, and 4-hydroxybutyl (meth) acrylate is particularly preferable from the viewpoint of durability.

  When the pressure-sensitive adhesive composition contains a crosslinking agent, the carboxyl group-containing monomer and the hydroxyl group-containing monomer serve as reaction points with the crosslinking agent. Since the carboxyl group-containing monomer and the hydroxyl group-containing monomer are rich in reactivity with the intermolecular crosslinking agent, they are preferably used for improving the cohesiveness and heat resistance of the resulting pressure-sensitive adhesive layer. Moreover, a carboxyl group-containing monomer is preferable in terms of achieving both durability and reworkability, and a hydroxyl group-containing monomer is preferable in terms of reworkability.

  The weight ratio of the carboxyl group-containing monomer is preferably 2% by weight or less, more preferably 0.01 to 2% by weight, further preferably 0.05 to 1.5% by weight, and further preferably 0. 1-1 weight% is preferable, Most preferably, it is 0.1-0.5 weight%. The weight ratio of the carboxyl group-containing monomer is preferably 0.01% by weight or more from the viewpoint of durability. On the other hand, when it exceeds 2 weight%, it is unpreferable from the point of rework property.

  The weight ratio of the hydroxyl group-containing monomer is preferably 3% by weight or less, more preferably 0.01 to 3% by weight, further preferably 0.1 to 2% by weight, further 0.2 to 2% by weight is preferred. It is preferable that the weight ratio of the hydroxyl group-containing monomer is 0.01% by weight or more from the viewpoint of crosslinking the pressure-sensitive adhesive layer, durability and pressure-sensitive adhesive properties. On the other hand, if it exceeds 3% by weight, it is not preferable from the viewpoint of durability.

  Specific examples of other copolymerization monomers other than those described above include: acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride; caprolactone adducts of acrylic acid; allylsulfonic acid, 2- (meth) acrylamide-2 -Sulphonic acid group-containing monomers such as methyl propane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate; and phosphoric acid group-containing monomers such as 2-hydroxyethyl acryloyl phosphate.

  Further, alkylaminoalkyl (meth) acrylates such as aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, t-butylaminoethyl (meth) acrylate; methoxyethyl (meth) acrylate, ethoxyethyl ( Alkoxyalkyl (meth) acrylates such as meth) acrylate; N- (meth) acryloyloxymethylene succinimide, N- (meth) acryloyl-6-oxyhexamethylene succinimide, N- (meth) acryloyl-8-oxyoctamethylene succinimide, etc. Succinimide monomers; N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide and other maleimide monomers; N-methylitaconimide, N Itaconimide monomers such as ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, N-laurylitaconimide, etc. are also examples of monomers for modification purposes. Can be mentioned.

  Furthermore, as modification monomers, vinyl monomers such as vinyl acetate and vinyl propionate; cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; epoxy group-containing (meth) acrylates such as glycidyl (meth) acrylate; polyethylene glycol (meth) Glycol-based (meth) acrylates such as acrylate, polypropylene glycol (meth) acrylate, methoxyethylene glycol (meth) acrylate, methoxypolypropylene glycol (meth) acrylate; tetrahydrofurfuryl (meth) acrylate, fluorine (meth) acrylate, silicone (meta (Meth) acrylate monomers such as acrylate and 2-methoxyethyl acrylate can also be used. Furthermore, isoprene, butadiene, isobutylene, vinyl ether and the like can be mentioned.

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

  Moreover, as a copolymerization monomer, tripropylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, bisphenol A diglycidyl ether di (meth) acrylate, neodymium Pentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate (Meth) acryloyl such as esterified product of (meth) acrylic acid and polyhydric alcohol such as caprolactone-modified dipentaerythritol hexa (meth) acrylate , Polyfunctional monomers having two or more unsaturated double bonds such as vinyl groups, and unsaturated groups such as (meth) acryloyl groups and vinyl groups as functional groups similar to the monomer components in the backbone of polyester, epoxy, urethane, etc. Polyester (meth) acrylate, epoxy (meth) acrylate, urethane (meth) acrylate and the like to which two or more double bonds are added can also be used.

  The ratio of the other copolymerization monomer in the (meth) acrylic polymer (A) is about 0 to 10% in the weight ratio of all the constituent monomers (100 wt%) of the (meth) acrylic polymer (A). Further, it is preferably about 0 to 7%, more preferably about 0 to 5%.

  In general, the (meth) acrylic polymer (A) of the present invention preferably has a weight average molecular weight of 1,000,000 to 2,500,000. Considering durability, particularly heat resistance, the weight average molecular weight is preferably 1.2 million to 2 million. A weight average molecular weight of 1 million or more is preferable from the viewpoint of heat resistance. On the other hand, when the weight average molecular weight is larger than 2.5 million, the pressure-sensitive adhesive tends to be hard and peeling is likely to occur. Moreover, it is preferable that weight average molecular weight (Mw) / number average molecular weight (Mn) which shows molecular weight distribution is 1.8 or more and 10 or less, Furthermore, it is 1.8-7, Furthermore, 1.8- 5 is preferred. When the molecular weight distribution (Mw / Mn) exceeds 10, it is not preferable in terms of durability. The weight average molecular weight and molecular weight distribution (Mw / Mn) are determined by GPC (gel permeation chromatography) and calculated from polystyrene.

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

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

  The polymerization initiator, chain transfer agent, emulsifier and the like used for radical polymerization are not particularly limited and can be appropriately selected and used. In addition, the weight average molecular weight of the (meth) acrylic polymer (A) can be controlled by the amount of polymerization initiator, the amount of chain transfer agent used, and the reaction conditions, and the amount used is appropriately adjusted according to these types. The

  The pressure-sensitive adhesive composition of the present invention contains an ionic compound (B). As the ionic compound (B), an alkali metal salt and / or an organic cation-anion salt can be preferably used. As the alkali metal salt, an organic salt or inorganic salt of an alkali metal can be used. The “organic cation-anion salt” in the present invention refers to an organic salt whose cation part is composed of an organic substance, and the anion part may be an organic substance or an inorganic substance. There may be. “Organic cation-anion salt” is also called an ionic liquid or ionic solid.

<Alkali metal salt>
Examples of the alkali metal ions constituting the cation part of the alkali metal salt include lithium, sodium, and potassium ions. Of these alkali metal ions, lithium ions are preferred.

The anion part of the alkali metal salt may be composed of an organic material or an inorganic material. Examples of the anion part constituting the organic salt include CH ₃ COO ⁻ , CF ₃ COO ⁻ , CH ₃ SO ₃ ⁻ , CF ₃ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₃ C ⁻ , and C ₄ F ₉ SO _{3. ^{-, 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-, or the following general formula ( 1) to (4), (1): (C _n F _{2n + 1} SO ₂ ) ₂ N ⁻ (where n is an integer of 1 to 10),
_{(2): CF 2 (C} m F 2m SO 2) 2 N - ( where, m is an integer of from 1 to 10),
^{_{(3): - O 3 S}} (CF 2) l SO 3 - ( where, l is an integer of from 1 to 10),
^{_{(4) :( C p F 2p}} + 1 SO 2) N - (C q F 2q + 1 SO 2), ( where, p, q is an integer of from 1 to 10), in represented by those such as are used. In particular, an anion moiety containing a fluorine atom is preferably used because an ionic compound having good ion dissociation properties can be obtained. The anion part constituting the inorganic salt includes Cl ⁻ , 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 the like are used. As the anion moiety, (perfluoroalkylsulfonyl) imide represented by the general formula (1) such as (CF ₃ SO ₂ ) ₂ N ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , and the like is preferable. (Trifluoromethanesulfonyl) imide represented by CF ₃ SO ₂ ) ₂ N ⁻ is preferable.

Specific examples of the alkali metal organic salt include sodium acetate, sodium alginate, sodium lignin sulfonate, sodium toluenesulfonate, 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 , and the like, among these _{LiCF 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 and the like are preferable, and Li (CF ₃ SO ₂ ) ₂ N, Li (C ₂ F ₅ SO ₂ ) ₂ N, Li (C ₄ F ₉ SO _{2) 2} Bis (fluorosulfonyl) fluorine-containing lithium imide salt is more preferably imide lithium salt etc., especially (perfluoroalkyl sulfonyl) imide lithium salts are preferred. Other examples include 4,4,5,5-tetrafluoro-1,3,2-dithiazolidine-1,1,3,3-tetraoxide lithium salt.

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

<Organic cation-anion salt>
The organic cation-anion salt used in the present invention is composed of a cation component and an anion component, and the cation component is composed of an organic substance. As the cation component, specifically, pyridinium cation, piperidinium cation, pyrrolidinium cation, cation having a pyrroline skeleton, cation having a pyrrole skeleton, imidazolium cation, tetrahydropyrimidinium cation, dihydropyrimidinium cation, Examples include pyrazolium cation, pyrazolinium cation, tetraalkylammonium cation, trialkylsulfonium cation, and tetraalkylphosphonium cation.

Examples of the anion component include Cl ⁻ , Br ⁻ , I ⁻ , AlCl ₄ ⁻ , Al ₂ Cl ₇ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , ClO ₄ ⁻ , NO ₃ ⁻ , CH ₃ COO ⁻ , and CF ₃ COO. ⁻ , CH ₃ SO ₃ ⁻ , CF ₃ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₃ C ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , NbF ₆ ⁻ , TaF ₆ ⁻ , (CN) ₂ N ⁻ , C ₄ F _{^{9 SO 3 -, C 3 F}} 7 COO -, ((CF 3 SO 2) (CF 3 CO) N -, - O 3 S (CF 2) 3 SO 3 -, or the following general formula (1) to (4 ),
(1): (C _n F _{2n + 1} SO ₂ ) ₂ N ⁻ (where n is an integer of 1 to 10),
_{(2): CF 2 (C} m F 2m SO 2) 2 N - ( where, m is an integer of from 1 to 10),
_{^{(3): - O 3 S}} (CF 2) l SO 3 - ( where, l is an integer of from 1 to 10),
^{_{(4) :( C p F 2p}} + 1 SO 2) N - (C q F 2q + 1 SO 2), ( where, p, q is an integer of from 1 to 10), in represented by those such as are used. Among these, an anion component containing a fluorine atom is particularly preferably used because an ionic compound having good ion dissociation properties can be obtained.

  As the organic cation-anion salt, a compound comprising a combination of the cation component and the anion component is appropriately selected and used. Preferable specific examples of the organic cation-anion salt include, for example, methyltrioctylammonium bis (trifluoromethanesulfonyl) imide, 1-methyl-1-propylpyrrolidinium bis (trifluoromethanesulfonyl) imide, ethylmethylimidazolium bis ( Fluorosulfonylimide). Of these, 1-methyl-1-propylpyrrolidinium bis (trifluoromethanesulfonyl) imide and ethylmethylimidazolium bis (fluorosulfonylimide) are more preferable.

  Examples of the ionic compound (B) include inorganic salts such as ammonium chloride, aluminum chloride, copper chloride, ferrous chloride, ferric chloride, and ammonium sulfate in addition to the alkali metal salt and organic cation-anion salt. Is mentioned.

The ionic compound (B) can be used alone or in combination in order to obtain a desired resistance value. In particular, when the purpose is to control the surface resistance value of the pressure-sensitive adhesive layer in the range of 1 × 10 ¹⁰ to 1 × 10 ¹² Ω / □, an alkali metal salt is used as the ionic compound (B) to prevent antistatic. It is preferable in terms of enhancing the performance. By using an alkali metal salt, a pressure-sensitive adhesive having high antistatic performance can be obtained even with a small number of blending parts. On the other hand, when it is intended to control the surface resistance value of the pressure-sensitive adhesive layer in the range of 1 × 10 ⁸ to 1 × 10 ¹⁰ Ω / □, the ionic compound (B) is an organic cation-anion salt. It is preferable in terms of enhancing the antistatic performance, and by using an organic cation-anion salt, a pressure-sensitive adhesive having high antistatic performance can be obtained even with a smaller number of blended parts.

The ratio of the ionic compound (B) in the pressure-sensitive adhesive composition of the present invention can be appropriately adjusted so as to satisfy the antistatic properties of the pressure-sensitive adhesive layer and the sensitivity of the touch panel. For example, containing an amide group introduced into the (meth) acrylic polymer (A) such that the surface resistance value of the pressure-sensitive adhesive layer is in the range of 1.0 × 10 ^{8 to} 1.0 × 10 ¹² Ω / □. It is preferable to adjust the ratio of the ionic compound (B) according to the type of the liquid crystal panel with a built-in touch sensing function, taking into consideration the weight ratio of the monomer (a2), the type of the transparent protective film of the polarizing film, and the like. For example, in the in-cell type liquid crystal panel with a built-in touch sensing function shown in FIG. 1, the first pressure-sensitive adhesive layer preferably has a surface resistance value controlled in a range of 1 × 10 ⁸ to 1 × 10 ¹⁰ Ω / □. Moreover, in the semi-in-cell type liquid crystal panel with a touch sensing function shown in FIG. 2 or the on-cell type shown in FIG. 3, the first adhesive layer has a surface resistance value of 1 × 10 ¹⁰ to 1 × 10 ¹² Ω / □. It is preferable to control the range.

  The first pressure-sensitive adhesive layer is controlled so as to satisfy a variation ratio (b / a) ≦ 5 of the surface resistance value. The a is immediately after producing the first polarizing film with the pressure-sensitive adhesive layer in which the first pressure-sensitive adhesive layer is provided on the first polarizing film and the separator is provided on the first pressure-sensitive adhesive layer. It is the surface resistance value of the first pressure-sensitive adhesive layer when the separator is peeled off, and b represents the first polarizing film with the pressure-sensitive adhesive layer put in a humidified environment of 60 ° C./95% RH for 250 hours, and further 40 It is the surface resistance value of the first pressure-sensitive adhesive layer when the separator is peeled after drying at 0 ° C. for 1 hour. When the variation ratio (b / a) exceeds 5, the antistatic function of the pressure-sensitive adhesive layer in a humidified environment is lowered. The variation ratio (b / a) is preferably 5 or less, more preferably 3.5 or less, further preferably 2.5 or less, and further preferably 2 or less, Most preferably, it is 1.5 or less.

  The proportion of the ionic compound (B) is preferably 0.01 parts by weight or more with respect to 100 parts by weight of the (meth) acrylic polymer (A), for example. Use of 0.01 part by weight or more of the ionic compound (B) is preferable in improving the antistatic performance. From this viewpoint, the ionic compound (B) is preferably 0.1 parts by weight or more, more preferably 0.5 parts by weight or more. On the other hand, when the ionic compound (B) increases, the surface resistance value becomes too low, and the sensitivity of the touch panel may decrease due to the baseline fluctuation (malfunction at the time of touch caused by the surface resistance value being too low). There is. Moreover, when the said ionic compound (B) increases, an ionic compound (B) may precipitate, and also it will become easy to produce humid peeling. From this viewpoint, the ionic compound (B) is usually preferably 40 parts by weight or less, more preferably 30 parts by weight or less, further preferably 20 parts by weight or less, and preferably 10 parts by weight or less. Most preferably it is.

  The pressure-sensitive adhesive composition of the present invention can contain a crosslinking agent (C). As the crosslinking agent (C), an organic crosslinking agent or a polyfunctional metal chelate can be used. Examples of the organic crosslinking agent include an isocyanate crosslinking agent, a peroxide crosslinking agent, an epoxy crosslinking agent, and an imine crosslinking agent. A polyfunctional metal chelate is one in which a polyvalent metal is covalently or coordinately bonded to an organic compound. Examples of polyvalent metal atoms include Al, Cr, Zr, Co, Cu, Fe, Ni, V, Zn, In, Ca, Mg, Mn, Y, Ce, Sr, Ba, Mo, La, Sn, Ti, and the like. Can be mentioned. Examples of the atom in the organic compound that is covalently bonded or coordinated include an oxygen atom, and examples of the organic compound include an alkyl ester, an alcohol compound, a carboxylic acid compound, an ether compound, and a ketone compound.

  As the crosslinking agent (C), an isocyanate crosslinking agent and / or a peroxide crosslinking agent are preferable.

  As the isocyanate crosslinking agent (C), a compound having at least two isocyanate groups can be used. For example, known aliphatic polyisocyanate, alicyclic polyisocyanate, aromatic polyisocyanate and the like generally used for urethanization reaction are used.

  As the peroxide, any radical active species can be used as long as it generates radical active species by heating or light irradiation to advance the crosslinking of the base polymer of the pressure-sensitive adhesive composition. However, in consideration of workability and stability. It is preferable to use a peroxide having a one-minute half-life temperature of 80 ° C. to 160 ° C., and more preferable to use a peroxide having a 90 ° C. to 140 ° C.

  Examples of peroxides that can be used include di (2-ethylhexyl) peroxydicarbonate (1 minute half-life temperature: 90.6 ° C.), di (4-t-butylcyclohexyl) peroxydicarbonate (1 Minute half-life temperature: 92.1 ° C.), di-sec-butyl peroxydicarbonate (1 minute half-life temperature: 92.4 ° C.), t-butyl peroxyneodecanoate (1 minute half-life temperature: 103 0.5 ° C), t-hexyl peroxypivalate (1 minute half-life temperature: 109.1 ° C), t-butyl peroxypivalate (1 minute half-life temperature: 110.3 ° C), dilauroyl peroxide ( 1 minute half-life temperature: 116.4 ° C.), di-n-octanoyl peroxide (1 minute half-life temperature: 117.4 ° C.), 1,1,3,3-tetramethylbutyl Oxy-2-ethylhexanoate (1 minute half-life temperature: 124.3 ° C), di (4-methylbenzoyl) peroxide (1 minute half-life temperature: 128.2 ° C), dibenzoyl peroxide (half-minute for 1 minute) Period temperature: 130.0 ° C.), t-butyl peroxyisobutyrate (1 minute half-life temperature: 136.1 ° C.), 1,1-di (t-hexylperoxy) cyclohexane (1 minute half-life temperature: 149.2 ° C.) and the like. Especially, since the crosslinking reaction efficiency is excellent, di (4-t-butylcyclohexyl) peroxydicarbonate (1 minute half-life temperature: 92.1 ° C.), dilauroyl peroxide (1 minute half-life temperature: 116. 4 ° C.), dibenzoyl peroxide (1 minute half-life temperature: 130.0 ° C.) and the like are preferably used.

  The amount of the crosslinking agent (C) used is preferably 3 parts by weight or less, more preferably 0.01 to 3 parts by weight, and further 0.02 with respect to 100 parts by weight of the (meth) acrylic polymer (A). ˜2 parts by weight is preferable, and 0.03 to 1 part by weight is more preferable. If the cross-linking agent (C) is less than 0.01 parts by weight, the pressure-sensitive adhesive layer may be insufficiently cross-linked and the durability and pressure-sensitive adhesive properties may not be satisfied. There is a tendency for durability to decrease due to excessive hardness.

  The pressure-sensitive adhesive composition of the present invention can contain a silane coupling agent (D). The durability can be improved by using the silane coupling agent (D). Specific examples of the silane coupling agent include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2- (3, Epoxy group-containing silane coupling agent such as 4-epoxycyclohexyl) ethyltrimethoxysilane, 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl- Amino group-containing silane coupling agents such as N- (1,3-dimethylbutylidene) propylamine, N-phenyl-γ-aminopropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltri (Meth) acrylic such as ethoxysilane Containing silane coupling agent, such as an isocyanate group-containing silane coupling agents such as 3-isocyanate propyl triethoxysilane and the like. As the exemplified silane coupling agent, an epoxy group-containing silane coupling agent is preferable.

  Moreover, what has a some alkoxy silyl group in a molecule | numerator can also be used as a silane coupling agent (D). Specifically, for example, X-41-1053, X-41-1059A, X-41-1056, X-41-1805, X-41-1818, X-41-1810, X-40 manufactured by Shin-Etsu Chemical Co., Ltd. -2651 etc. are mentioned. Silane coupling agents having a plurality of alkoxysilyl groups in these molecules are preferred because they are less volatile and effective in improving durability because they have a plurality of alkoxysilyl groups. In particular, the durability is also suitable when the adherend of the optical film with the pressure-sensitive adhesive layer is a transparent conductive layer (for example, ITO) in which alkoxysilyl groups are less likely to react than glass. The silane coupling agent having a plurality of alkoxysilyl groups in the molecule preferably has an epoxy group in the molecule, and more preferably has a plurality of epoxy groups in the molecule. A silane coupling agent having a plurality of alkoxysilyl groups in the molecule and having an epoxy group tends to have good durability even when the adherend is a transparent conductive layer (for example, ITO). Specific examples of the silane coupling agent having a plurality of alkoxysilyl groups in the molecule and having an epoxy group include X-41-1053, X-41-1059A, and X-41-1056 manufactured by Shin-Etsu Chemical Co., Ltd. In particular, X-41-1056 manufactured by Shin-Etsu Chemical Co., Ltd. having a high epoxy group content is preferred.

  The silane coupling agent (D) may be used alone or as a mixture of two or more, but the total content thereof is the (meth) acrylic polymer (A) 100. 5 parts by weight or less is preferable with respect to parts by weight, more preferably 0.001 to 5 parts by weight, still more preferably 0.01 to 1 part by weight, still more preferably 0.02 to 1 part by weight, Is preferably 0.05 to 0.6 parts by weight. It is an amount that improves durability.

  In the pressure-sensitive adhesive composition of the present invention, a polyether compound (E) having a reactive silyl group can be blended. The polyether compound (E) is preferable in that the reworkability can be improved. As the polyether compound (E), for example, those disclosed in JP 2010-275522 A can be used.

  The proportion of the polyether compound (E) in the pressure-sensitive adhesive composition of the present invention is preferably 10 parts by weight or less, and preferably 0.001 to 10 parts by weight with respect to 100 parts by weight of the (meth) acrylic polymer (A). . If the said polyether compound (E) is less than 0.001 weight part, the improvement effect of rework property may not be enough. The polyether compound (E) 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 amount of the polyether compound (E) is more than 10 parts by weight, it is not preferable from the viewpoint of durability. The polyether compound (E) is preferably 5 parts by weight or less, and more preferably 2 parts by weight or less. The ratio of the said polyether compound (E) can set the preferable range by employ | adopting the said upper limit or lower limit.

  Furthermore, the pressure-sensitive adhesive composition of the present invention may contain other known additives such as a polyether compound of polyalkylene glycol such as polypropylene glycol, a colorant, a powder such as a pigment, a dye, Surfactant, plasticizer, tackifier, surface lubricant, leveling agent, softener, antioxidant, anti-aging agent, light stabilizer, UV absorber, polymerization inhibitor, inorganic or organic filler, metal It can be added as appropriate according to the intended use of powder, particles, foils and the like. Moreover, you may employ | adopt the redox system which added a reducing agent within the controllable range. These additives are preferably used in an amount of 5 parts by weight or less, further 3 parts by weight or less, and further 1 part by weight or less based on 100 parts by weight of the (meth) acrylic polymer (A).

  The 1st adhesive layer 21 of this invention can be used as an optical film with an adhesive layer bonded together to the optical film (polarizing film). The optical film with the pressure-sensitive adhesive layer can be obtained by forming a pressure-sensitive adhesive layer on at least one surface of the optical film with the pressure-sensitive adhesive composition.

  As a method for forming the pressure-sensitive adhesive layer, for example, the pressure-sensitive adhesive composition is applied to a release-treated separator, and the polymerization solvent is dried and removed to form a pressure-sensitive adhesive layer, which is then transferred to an optical film (polarizing film). Or a method of applying the pressure-sensitive adhesive composition to an optical film (polarizing film) and drying and removing the polymerization solvent to form a pressure-sensitive adhesive layer on the optical film. In applying the pressure-sensitive adhesive, one or more solvents other than the polymerization solvent may be added as appropriate.

  The thickness of the 1st adhesive layer 21 is not restrict | limited in particular, For example, it is about 1-100 micrometers. Preferably, it is 2-50 micrometers, More preferably, it is 2-40 micrometers, More preferably, it is 5-35 micrometers.

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

<Measurement of weight average molecular weight of (meth) acrylic polymer (A)>
The weight average molecular weight (Mw) of the (meth) acrylic polymer (A) was measured by GPC (gel permeation chromatography). It measured similarly about Mw / Mn.
・ Analyzer: HLC-8120GPC manufactured by Tosoh Corporation
Column: manufactured by Tosoh Corporation, G7000H _XL + GMH _XL + GMH _XL
・ Column size: 7.8mmφ × 30cm each 90cm in total
-Column temperature: 40 ° C
・ Flow rate: 0.8mL / min
・ Injection volume: 100 μL
・ Eluent: Tetrahydrofuran ・ Detector: Differential refractometer (RI)
Standard sample: polystyrene

<Creation of polarizing film P1>
A polyvinyl alcohol film having a thickness of 80 μm was stretched up to 3 times while being dyed for 1 minute in an iodine solution of 0.3% concentration at 30 ° C. between rolls having different speed ratios. Thereafter, the total draw ratio was stretched to 6 times while being immersed in an aqueous solution containing 60% at 4% concentration of boric acid and 10% concentration of potassium iodide for 0.5 minutes. Next, after washing by immersing in an aqueous solution containing potassium iodide at 30 ° C. and 1.5% concentration for 10 seconds, drying was performed at 50 ° C. for 4 minutes to obtain a polarizer having a thickness of 30 μm. A polarizing film P1 was prepared by bonding a corona-treated (meth) acrylic resin film having a lactone ring structure having a thickness of 20 μm as a transparent protective film with a polyvinyl alcohol adhesive on both surfaces of the polarizer.

<Creation of polarizing film P2>
In the production of the polarizing film P1, a polarizing film P2 was obtained by the same method except that a saponified 80 μm thick triacetylcellulose film was used as the transparent protective film.

Example 1
(Preparation of acrylic polymer (A))
In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube and a condenser, 75.8 parts of butyl acrylate, 23 parts of phenoxyethyl acrylate, 0.5 part of N-vinyl-2-pyrrolidone (NVP), A monomer mixture containing 0.3 part of acrylic acid and 0.4 part of 4-hydroxybutyl acrylate was charged. Furthermore, with respect to 100 parts of the monomer mixture (solid content), 0.1 part of 2,2′-azobisisobutyronitrile as a polymerization initiator was charged with 100 parts of ethyl acetate, and nitrogen gas was added while gently stirring. After introducing and purging with nitrogen, the polymerization temperature was kept at around 55 ° C. for 8 hours to carry out a polymerization reaction, and an acrylic polymer having a weight average molecular weight (Mw) of 1.6 million and Mw / Mn = 3.7 (A ) Was prepared.

(Preparation of adhesive composition)
Bis (trifluoromethanesulfonyl) imide lithium (Li-TFSI) 0.1 manufactured by Mitsubishi Materials Corporation as an ionic compound with respect to 100 parts of the solid content of the solution of the acrylic polymer (A1) obtained in Production Example 1 Parts, 0.1 parts of isocyanate crosslinking agent (Takenate D160N, manufactured by Mitsui Chemicals, trimethylolpropane hexamethylene diisocyanate), 0.3 part of benzoyl peroxide (Nyper BMT manufactured by NOF Corporation) and epoxy group-containing silane coupling agent (Shin-Etsu Chemical Co., Ltd. product: X-41-1056) 0.3 part was mix | blended and the solution of the acrylic adhesive composition was prepared.

(Preparation of polarizing film with adhesive layer)
Next, the solution of the acrylic pressure-sensitive adhesive composition was applied to one side of a polyethylene terephthalate film (separator film: manufactured by Mitsubishi Chemical Polyester Film Co., Ltd., MRF38) treated with a silicone-based release agent. It was applied to a thickness of 20 μm and dried at 155 ° C. for 1 minute to form an adhesive layer on the surface of the separator film. Next, the pressure-sensitive adhesive layer formed on the separator film was transferred to the polarizing film P1 prepared above to produce a pressure-sensitive adhesive layer-attached polarizing film.

Examples 2-14, Comparative Examples 1-6
In Example 1, as shown in Table 1, the amount of N-vinyl-2-pyrrolidone (NVP) used in the preparation of the acrylic polymer (A) in the monomer mixture and the pressure-sensitive adhesive composition were used. Except for changing the type of ionic compound (Li-TFSI or MPP-TFSI) or its blending ratio and the type of polarizing film, a solution of an acrylic polymer and an acrylic pressure-sensitive adhesive composition were the same as in Example 1. A solution of was prepared. Moreover, the polarizing film with an adhesive layer was produced like Example 1 using the solution of the said acrylic adhesive composition.

  The following evaluation was performed about the polarizing film with an adhesive layer obtained by the said Example and comparative example. The evaluation results are shown in Table 1. In each evaluation, “Initial” is immediately after producing the polarizing film with the pressure-sensitive adhesive layer, “After humidification” is “After humidification”, and the obtained polarizing film with the pressure-sensitive adhesive layer is 250 hours in a humidified environment of 60 ° C./95% RH It is the value measured after each was added and further dried at 40 ° C. for 1 hour.

<Surface resistance (Ω / □): conductivity>
After peeling the separator film from the polarizing film with the pressure-sensitive adhesive layer, the surface resistance value of the pressure-sensitive adhesive layer surface was measured. The measurement was performed using MCP-HT450 manufactured by Mitsubishi Chemical Analytech.
The fluctuation ratio (b / a) in Table 1 is a value calculated from the “initial” surface resistance value (a) and the “after humidification” surface resistance value (b) (rounded off to the second decimal place). Value).
Moreover, the following criteria evaluated that a value with a small fluctuation ratio was preferable as an index with a low possibility of causing “malfunction”.
A: Variation ratio is 2 or less.
A: The fluctuation ratio exceeds 2 and is less than 5.
X: Fluctuation ratio is 5 or more.

<ESD test>
After peeling the separator film from the polarizing film with the pressure-sensitive adhesive layer, as shown in Table 1, it was bonded to the viewing side of the on-cell type liquid crystal cell or in-cell type liquid crystal cell to prepare a liquid crystal panel with a built-in touch sensing function. That is, the polarizing film with an adhesive layer obtained in Examples 1 to 3, 6 to 10, and Comparative Examples 1 to 6 was bonded to the sensor layer (touch sensor portion) of the on-cell liquid crystal cell shown in FIG. Thus, the first pressure-sensitive adhesive layer and the first polarizing film were formed. The polarizing film with the pressure-sensitive adhesive layer obtained in Examples 4, 5, 11 to 13 was bonded to the first transparent substrate of the in-cell type liquid crystal cell shown in FIG. 1, and the first pressure-sensitive adhesive layer and the first polarizing film were bonded. Formed. In the liquid crystal panel, an ESD (electrostatic discharge) gun (10 kV) was fired on the polarizing film surface, and the time until the white spots disappeared due to electricity was measured and judged according to the following criteria.
(Evaluation criteria)
A: Within 3 seconds.
○: Over 3 seconds and within 10 seconds.
X: Over 10 seconds.

  In Table 1, Li-TFSI indicates bis (trifluoromethanesulfonyl) imide lithium, and MPP-TFSI indicates 1-methyl-1-propylpyrrolidinium bis (trifluoromethanesulfonyl) imide manufactured by Toyo Gosei Co., Ltd.

  As shown in Table 1, from the description of Examples and Comparative Examples, even when the initial surface resistance value of the pressure-sensitive adhesive layer was set low by blending an ionic compound into the acrylic polymer, It can be seen that when the acrylic polymer has an amide group-containing monomer as a monomer unit, the fluctuation ratio of the surface resistance value after humidification of the pressure-sensitive adhesive layer is 5 or less, and an increase in the surface resistance value can be suppressed. That is, in the examples, since the fluctuation ratio of the surface resistance value of the pressure-sensitive adhesive layer is small, the surface resistance value can be maintained within a desired range even after humidification, and the touch panel sensitivity can be maintained well. Furthermore, the ESD test is good and static electricity unevenness can be suppressed.

DESCRIPTION OF SYMBOLS 11, 12 1st, 2nd polarizing film 21, 22 1st, 2nd adhesive layer 3 Liquid crystal layer 41, 42 1st, 2nd transparent substrate 5 Touch sensor part 6 Drive electrode and sensor part 7 Drive electrode C Liquid crystal cell

Claims (4)

A polarizing film having an adhesive layer,
The pressure-sensitive adhesive layer contains, as monomer units, a (meth) acrylic polymer (A) containing an alkyl (meth) acrylate (a1) and an amide group-containing monomer (a2), and an ionic compound (B). Formed from an agent composition, and
The ionic compound (B) is an organic cation-anion salt,
The ionic compound (B) is contained in an amount of 0.01 to 13 parts by weight with respect to 100 parts by weight of the (meth) acrylic polymer (A),
The surface resistance value of the pressure-sensitive adhesive layer is 1.0 × 10 ⁸ Ω / □ or more and 1.0 × 10 ¹⁰ Ω / □ or less,
The pressure-sensitive adhesive layer has a surface resistance value fluctuation ratio (b / a) ≦ 5, where the a is provided with the pressure-sensitive adhesive layer on the polarizing film, and the pressure-sensitive adhesive layer is provided with a separator. The surface resistance value of the pressure-sensitive adhesive layer when the separator was peeled off immediately after the production of the polarizing film with the pressure-sensitive adhesive layer in the wet state, With pressure-sensitive adhesive layer characterized by satisfying the respective surface resistance values of the pressure-sensitive adhesive layer when the separator is peeled off after being put in an environment for 250 hours and further dried at 40 ° C. for 1 hour. Polarized film.   The pressure-sensitive adhesive layer according to claim 1, wherein the amide group-containing monomer (a2) is contained in the (meth) acrylic polymer (A) as a monomer unit in an amount of 0.1% by weight or more. Attached polarizing film.   The polarizing film with an adhesive layer according to claim 1 or 2, wherein the amide group-containing monomer (a2) does not contain an N- (alkoxyalkyl) (meth) acrylamide monomer. The pressure-sensitive adhesive layer-attached polarizing film according to claim 1, wherein a fluctuation ratio (b / a) of the surface resistance value is 2 or less.

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