TW201621015A - Adhesive layer and adhesive film - Google Patents

Abstract

The present invention provides an adhesive layer and an adhesive film having flexibility and rigidity together with durability and reworkability. More specifically, the present invention is an adhesive layer in which an adhesive composition including: an acrylic-based polymer; and a cross-linking agent is cross-linked, the acrylic-based polymer being a copolymer obtained by copolymerizing at least one or more from the group of monomers consisting of alkyl (meth)acrylate monomers having a C1 to C14 alkyl group, alicyclic group-containing monomers, and branched structure alkyl group-containing monomers, and a hydroxyl group-containing copolymerizable vinyl monomer, the alkyl-based polymer containing, with respect to a total of 100 parts by weight of the monomers excluding the hydroxyl group-containing copolymerizable vinyl monomer, 30 to 100 parts by weight of butyl (meth)acrylate and 0.1 to 3.5 parts by weight of the hydroxyl group-containing copolymerizable vinyl monomer, the gel fraction being 40 to 75%, the relative dielectric constant at a frequency of 100 kHz measured after laminating to a thickness of 1,000 [mu]m being 1.50 to 5.50, and the dielectric loss being 0.01 to 0.09.

Description

Adhesive layer and adhesive film

The present invention relates to an adhesive layer and an adhesive film for bonding optical members such as polarizing plates. More specifically, the present invention provides an adhesive layer and an adhesive film which are used for optics in the manufacture of a liquid crystal panel or the like having an ITO film called an On-cell panel. The adhesion of the components, the dielectric constant of the adhesive layer and the value of the dielectric loss are low, and both softness and stiffness, durability and reworkability are combined.

In recent years, various display devices that externally connect an electrostatic capacitance type touch panel to a liquid crystal panel have been widely used, such as a smart phone, a tablet terminal, a tablet PC, and the like. In such a display device, there is a physical space between the liquid crystal panel and the touch panel. Therefore, there is a problem that external light or the like is reflected on the upper surface of the liquid crystal panel or the lower surface of the touch panel, and the visibility is lowered, particularly in a bright environment such as an outdoor room.

As a method for solving the problem of such a decrease in visibility, an In-cell type display device in which a function of a touch panel is embedded in a liquid crystal cell has been proposed (for example, refer to Patent Document 1). However, since this requires a complicated manufacturing process, the yield of the product is lowered, and it is technically difficult to improve the display performance of the image. For these reasons, it has not been put into practical use.

On the other hand, a display device of the On-cell type has recently been proposed (for example, refer to Patent Document 2). The On-cell type display device is a display device in which a touch sensor including a transparent electrode pattern is formed between a color filter and a polarizing plate, and a touch panel function is embedded between the color filter substrate and the polarizing plate. The On-cell method has the advantage that the yield of the product is reduced less. Therefore, the On-cell method is expected to be developed in the future as a promising manufacturing technology for a liquid crystal panel in which a touch panel is assembled.

However, the capacitive touch panel is a sensor that senses changes in electromagnetic fields and is therefore susceptible to noise. Therefore, in order to prevent erroneous recognition of the contact position, a low dielectric constant film is laminated in the laminated structure or a low dielectric constant member is provided in the wiring of the electrostatic capacitance sensor (for example, reference patent) Literature 3~5).

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2009-258182

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2014-044501

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2013-082880

[Patent Document 4] Japanese Patent Laid-Open Publication No. 2012-094017

[Patent Document 5] Japanese Patent Laid-Open Publication No. 2013-003758

Further, the adhesive of Patent Document 3 has a specific dielectric constant of 3.5 or less and has excellent insulating properties, but whether or not the adhesive layer has flexibility and rigidity Sex is not clear.

Further, in Patent Documents 4 and 5, in order to prevent erroneous recognition of a capacitive touch panel, a low dielectric constant film is laminated in the laminated structure or a low wiring is provided in the wiring of the capacitance sensor. A component of dielectric constant. However, the method of manufacturing the low dielectric constant member used is not specifically shown.

Thus, it can be used for bonding of optical members, and an adhesive layer and an adhesive film which have excellent insulating properties, flexibility, stiffness, durability, and reworkability due to a low dielectric constant, in the prior art. It is unknown.

There is a need for an adhesive layer and an adhesive film that overcomes these requirements and problems in the prior art and can be used for the bonding of optical components.

An object of the present invention is to provide an adhesive layer and an adhesive film which are lower in dielectric constant and dielectric loss than a conventional adhesive layer, and which have both flexibility and stiffness and durability. And reworkability.

In order to solve the above problems, the technical idea of the adhesive layer of the present invention is as follows: an acrylic polymer has butyl (meth) acrylate as an essential monomer; no aromatic-containing monomer is used; and a functional group-containing monomer does not. For the carbonyl group-containing monomer, only the hydroxyl group-containing monomer is used; for the copolymer, the crosslinking agent uses only the adduct of toluene diisocyanate; further, a decane coupling agent is used in combination.

In order to solve the above problems, the present invention provides an adhesive layer which is an adhesive layer obtained by crosslinking an adhesive composition containing an acrylic polymer and a crosslinking agent, wherein the acrylic polymer is an alkane The carbon number of the base is C1 to C14 alkyl (meth) acrylate monomer, alicyclic monomer, and branched chain a copolymer obtained by copolymerizing at least one monomer of a monomer group composed of a monomer having a structural alkyl group and a hydroxyl group-containing copolymerizable vinyl monomer, with respect to a copolymerizable vinyl group other than the hydroxyl group-containing copolymer 100 parts by weight of the total amount of monomers other than the body, the acrylic polymer contains 30 to 100 parts by weight of butyl (meth)acrylate, and 0.1 to 3.5 parts by weight of the hydroxyl group-containing copolymerized vinyl monomer The adhesive layer has a gel fraction of 40 to 75%, and the adhesive layer is laminated to a thickness of 1000 μm. The specific dielectric constant measured at a frequency of 100 kHz is 1.50 to 5.50, and the dielectric loss is It is 0.01~0.09.

The acrylic polymer preferably contains no (meth) acrylate monomer having an aromatic group and a carboxyl group-containing copolymerizable vinyl monomer, and the acrylic polymer has an acid value of 0.1 or less, with respect to 100 parts by weight of the total of the monomers of the hydroxyl group-containing copolymerizable vinyl monomer, containing 0.01 to 1.5 parts by weight of an isocyanate compound as the crosslinking agent, and an adhesive after crosslinking the adhesive composition The layer has a weight average molecular weight of 300,000 to 2,000,000. After laminating the adhesive layer on one side of the substrate to a thickness of 25 μm, the adhesion after 23 ° C × 10 days is 1.5 to 10 N / 25 mm.

It is preferable that the adhesive composition further contains 0.01 to 2.0 parts by weight of a decane coupling agent with respect to 100 parts by weight of the total amount of the monomer other than the hydroxyl group-containing copolymerizable vinyl monomer.

The crosslinking agent is an isocyanate compound, preferably a trimethylolpropane adduct of toluene diisocyanate.

The hydroxyl group-containing copolymerizable vinyl monomer is preferably selected from the group consisting of 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. At least one of the compound groups consisting of 2-hydroxyethyl (meth)acrylate the above.

Further, the present invention provides an adhesive film in which the adhesive layer is laminated on one side of a substrate.

The adhesive film is preferably used for bonding a polarizing plate to a liquid crystal panel or to an organic EL panel.

Further, the present invention provides an adhesive film comprising a pressure-sensitive adhesive layer formed on one surface of a release film having a thickness of from 1 μm to 25 μm, which is a release film/adhesive layer/release film.

Further, the present invention provides an optical film with an adhesive, wherein the adhesive film is used on at least one side of the optical film.

Further, the present invention provides a polarizing plate with an adhesive layer, wherein the adhesive film according to item 8 of the patent application is used on one side of the polarizing plate.

The polarizing plate with an adhesive layer is preferably used for the adhesion of a retardation film having a phase difference of λ/4 or λ/2 and the polarizing plate.

Further, the present invention provides a liquid crystal panel in which the polarizing plate with an adhesive layer is used.

Further, the present invention provides an On-cell panel in which the polarizing plate with an adhesive layer is used.

According to the present invention, it is possible to provide an adhesive layer and an adhesive film which have softness, stiffness and durability as compared with the conventional adhesive layer, and have a low dielectric constant and dielectric loss value. Reworkability.

1‧‧‧ touch panel

2‧‧‧LCD panel

3‧‧‧Backlight unit

4‧‧‧ Space

5‧‧‧LCD panel with touch panel

10‧‧‧Touch sensor

11,12‧‧‧ glass substrate

13‧‧‧ color filter

14,15‧‧‧Polarizer

16‧‧‧Transparent electrode

17‧‧‧TFT electrode

18‧‧‧Liquid layer

20‧‧‧LCD panel

30‧‧‧Backlight unit

40‧‧‧LCD panel with On-cell touch panel

FIG. 1 is a schematic structural view showing an example of a liquid crystal panel on which a conventional touch panel is mounted.

FIG. 2 is a schematic structural view showing an example of a liquid crystal panel on which an On-cell touch panel is mounted.

Hereinafter, the present invention will be described based on preferred embodiments.

The present invention provides an adhesive layer and an adhesive film for use in the manufacture of a liquid crystal panel or the like having an ITO film called an On-cell panel, which is used for bonding optical components. Softness and stiffness, durability and reworkability.

FIG. 1 is a schematic view showing an example of a liquid crystal panel 5 on which a conventional touch panel is mounted. In the display device using the liquid crystal panel on which the conventional touch panel is mounted, the physical space 4 exists between the liquid crystal panel 2 and the touch panel 1. Therefore, there is a problem in that external light or the like is reflected on the upper surface of the liquid crystal panel 2 or the lower surface of the touch panel 1, and the visibility is lowered, particularly in a bright environment such as a house.

In addition, FIG. 2 shows a schematic structural view of an example of a liquid crystal panel 40 on which an On-cell type touch panel is mounted. The On-cell type display device is a display in which a touch sensor 10 including a transparent electrode pattern is formed between the color filter 13 and the polarizing plate 14, and a touch panel is provided between the color filter 13 and the polarizing plate 14. Device. The On-cell method has the advantage that the yield of the product is reduced less. Therefore, the On-cell method is expected to be developed in the future as a promising manufacturing technology for a liquid crystal panel in which a touch panel is assembled.

Compared with the conventional adhesive layer, in Fig. 2, the use of the present invention The adhesive layer adhered to the optical member is an adhesive layer having a low dielectric constant and dielectric loss value, thereby reducing the influence of noise on the electrostatic capacitance type touch panel, and thus can be used for the polarizing plate 14 and the backlight unit. The fit of the optical components between 30.

The adhesive layer of the present invention is particularly preferably used to bond the upper and lower polarizing plates 14, 15 to the liquid crystal panel 20. Specifically, the adhesive layer of the present invention can be particularly preferably used for the bonding of the polarizing plate 14 and the glass substrate 11 with the touch sensor 10 (also referred to as ITO glass) as well as the polarizing plate 15 and the TFT electrode. The bonding of the glass substrate 12 (also referred to as TFT glass) of 17.

The adhesive layer of the present invention is an adhesive layer obtained by crosslinking an adhesive composition containing an acrylic polymer and a crosslinking agent, wherein the acrylic polymer is composed of an alkyl group having a carbon number of C1 to C14. At least one or more monomers and a hydroxyl group-containing copolymerized vinyl group in a monomer group composed of an alkyl (meth)acrylate monomer, an alicyclic monomer, and a branched alkyl group-containing monomer The copolymer obtained by copolymerization of the monomer contains 30 to 100 parts by weight of (meth) with respect to 100 parts by weight of the total amount of the monomer other than the hydroxyl group-containing copolymerizable vinyl monomer. Butyl acrylate, 0.1 to 3.5 parts by weight of the hydroxyl group-containing copolymerizable vinyl monomer, the adhesive layer has a gel fraction of 40 to 75%, and the adhesive layer is laminated to a thickness of 1000 μm. The specific dielectric constant measured at a frequency of 100 kHz is 1.50 to 5.50, and the dielectric loss is 0.01 to 0.09.

The acrylic polymer of the present invention is a copolymer obtained by copolymerizing one or more monomers belonging to the first monomer group and a monomer belonging to the second monomer group, and is used as a monomer belonging to the first monomer group. The alkyl group has a C1 to C14 alkyl (meth) acrylate monomer, an alicyclic monomer, and a branched alkyl group-containing monomer. At least one or more monomers in the monomer group to be formed include a hydroxyl group-containing copolymerizable vinyl monomer as a monomer belonging to the second monomer group. In the present specification, (meth) acrylate is a generic term for acrylate and methacrylate.

In the adhesive composition of the present invention, as the alkyl (meth) acrylate monomer having a C1 to C14 carbon number as an alkyl group, methyl (meth) acrylate or ethyl (meth) acrylate may be mentioned. , (meth) propyl acrylate, butyl (meth) acrylate, amyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, ( Ethyl methacrylate, decyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, (a) At least one or more of tetradecyl acrylate and the like. The alkyl group of the alkyl (meth) acrylate monomer may be linear, branched or cyclic, and the alkyl group is linear. The (meth) acrylate monomer having a branched alkyl group belongs to a monomer having a branched alkyl group. Further, the (meth) acrylate monomer having a cyclic alkyl group belongs to an alicyclic group-containing monomer. The acrylic polymer of the present invention contains butyl (meth)acrylate as an essential monomer. The acrylic polymer preferably contains 30 to 100 parts by weight of (meth)acrylic acid based on 100 parts by weight of the total amount of the monomer other than the hydroxyl group-containing copolymerizable vinyl monomer (monomer belonging to the first monomer group). Butyl ester.

In the adhesive composition of the present invention, examples of the alicyclic group-containing monomer include cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, and isobornyl (meth)acrylate. At least one selected from the group consisting of bicycloheptyl methyl acrylate, bicyclooctyl (meth) acrylate, dimethyl bicycloheptyl (meth) acrylate, and dicyclopentanyl (meth) acrylate. The alicyclic monomer may be an alicyclic (meth) acrylate monomer having an alkyl group having a C1 to C18 carbon number.

In the adhesive composition of the present invention, examples of the monomer having a branched alkyl group include isopropyl (meth)acrylate, isobutyl (meth)acrylate, and tert-butyl (meth)acrylate. Ester, isoamyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isodecyl (meth)acrylate, isodecyl (meth)acrylate, Isodecyl (meth)acrylate, isododecyl (meth)acrylate, isotridecyl (meth)acrylate, isotetradecyl (meth)acrylate, (A) Isopentadecyl acrylate, isohexadecyl (meth)acrylate, isoheptadecyl (meth)acrylate, isostearyl (meth)acrylate, (methyl) At least one or more of isomyristyl acrylate and isostearyl (meth)acrylate. The monomer having a branched alkyl group may be a branched (meth)acrylic acid alkyl ester monomer having an alkyl group having a C1 to C18 carbon number. The monomer having a branched alkyl group may have a branched structure of two or more alkyl groups such as a t-butyl group (for example, two or more side chains with respect to the main chain).

In the adhesive composition of the present invention, examples of the hydroxyl group-containing copolymerizable vinyl monomer include 8-hydroxyoctyl (meth)acrylate and 6-hydroxyhexyl (meth)acrylate. a hydroxyl group-containing (meth)acrylic acid alkyl ester such as 4-hydroxybutyl acrylate or 2-hydroxyethyl (meth)acrylate; N-hydroxy(meth) acrylamide, N-hydroxyl At least one or more of hydroxyl group-containing (meth) acrylamides such as (meth) acrylamide and N-hydroxyethyl (meth) acrylamide. Wherein the hydroxyl group-containing copolymerizable vinyl monomer is preferably selected from the group consisting of 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. At least one or more of the compound groups consisting of 2-hydroxyethyl (meth)acrylate. The acrylic polymer of the present invention contains 0.1 to 3.5 parts by weight of a hydroxyl group-containing portion with respect to 100 parts by weight of the total amount of the monomer other than the hydroxyl group-containing copolymerizable vinyl monomer (monomer belonging to the first monomer group). Copolymerizable vinyl monomer.

In the adhesive composition of the present invention, the acrylic polymer preferably does not contain a (meth) acrylate monomer having an aromatic group from the viewpoint of lowering the dielectric constant of the pressure-sensitive adhesive layer. Similarly, the (meth) acrylate having an aromatic group is not limited, and a copolymerizable vinyl monomer (styrene or the like) having an aromatic group may not be contained. Moreover, it is preferable that the acrylic polymer does not contain a carboxyl group-containing copolymerizable vinyl monomer from the viewpoint of avoiding the corrosiveness of the adherend which is corrosive to the ITO surface of the transparent conductive film. The acid value of the acrylic polymer is preferably 0.1 or less.

The polymerization method of the copolymer used as the acrylic polymer is not particularly limited, and a suitable known polymerization method such as a solution polymerization method or an emulsion polymerization method can be used. The acrylic polymer preferably contains 50 to 100% by weight of an acrylic monomer such as a (meth) acrylate monomer.

By mixing a crosslinking agent and a suitable arbitrary additive with the above-mentioned acrylic polymer, characteristics, such as the physical property value required for the said adhesive composition, can be adjusted.

Examples of the crosslinking agent include a biuret modification of a diisocyanate such as hexamethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, toluene diisocyanate or benzene dimethylene diisocyanate. At least one or more kinds of polyisocyanate compounds such as a compound, an isocyanurate-modified product, and an adduct of a trihydric or higher polyhydric alcohol such as trimethylolpropane or glycerin. The acrylic polymer preferably has a hydroxyl group as a functional group capable of undergoing crosslinking reaction with an isocyanate compound of a crosslinking agent, and a monomer having such a functional group in a side chain is preferable.

The content of the isocyanate compound used as the crosslinking agent is preferably 0.01 to 1.5 parts by weight based on 100 parts by weight of the total amount of the monomer other than the hydroxyl group-containing copolymerizable vinyl monomer (monomer belonging to the first monomer group). . As the crosslinking agent, only an isocyanate compound can be used. As the isocyanate compound, an adduct of toluene diisocyanate is preferred, and a trimethylolpropane adduct of toluene diisocyanate is particularly preferred.

The adhesive composition preferably further contains a decane coupling agent. The decane coupling agent may, for example, be a compound having at least one organic functional group and at least one hydrolyzable group in one molecule and the hydrolyzable group being an alkoxy group bonded to a ruthenium atom. The decane coupling agent preferably has at least one organic functional group selected from the group consisting of an epoxy group, a (meth) propylene fluorenyl group, a fluorenyl group, and an amino group. Here, the (meth) propylene fluorenyloxy group means an acryloxy group (CH ₂ =CHCOO-) or a methacryloxy group (CH ₂ =C(CH ₃ )COO-).

Examples of the decane coupling agent having an epoxy group include 3-glycidoxypropyltrimethoxydecane, 3-glycidoxypropylmethyldiethoxydecane, and 3-epoxy. Propoxypropylmethyldimethoxydecane, 3-glycidoxypropyltriethoxydecane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxydecane, 2-( 3,4-Epoxycyclohexyl)ethylmethyldimethoxydecane, 2-(3,4-epoxycyclohexyl)ethylmethyldiethoxydecane, 2-(3,4- Epoxycyclohexyl)ethyltriethoxydecane, 5,6-epoxyhexyltrimethoxydecane, 5,6-epoxyhexylmethyldimethoxydecane, 5,6-epoxy Hexylmethyldiethoxydecane, 5,6-epoxyhexyltriethoxydecane, and the like.

Examples of the decane coupling agent having a (meth) propylene fluorenyloxy group include 3-(meth)acryloxypropyltrimethoxydecane and 3-(meth)acryloxypropane propylene. Methyl dimethoxy decane, 3-(methyl) propylene methoxy propyl triethoxy decane, 3-(methyl) propylene methoxy propyl methyl diethoxy decane, 3- ( Methyl) propylene methoxy propyl dimethyl ethoxy decane, 3-(methyl) propylene methoxy propyl dimethyl methoxy decane, and the like.

Examples of the decane coupling agent having a mercapto group include 3-mercaptopropylmethyldimethoxydecane, 3-mercaptopropyltrimethoxydecane, 3-mercaptopropylmethyldiethoxydecane, and 3 - Mercaptopropyltriethoxydecane, and the like.

The decane coupling agent having an amino group may, for example, be 3-aminopropyltrimethoxydecane, 3-aminopropyltriethoxydecane, N-phenyl-3-aminopropyltrimethoxydecane, or N. -2-(aminoethyl)-3-aminopropylmethyldimethoxydecane, N-2-(aminoethyl)-3-aminopropylmethyldiethoxydecane, N-2-( Aminoethyl)-3-aminopropyltrimethoxydecane, N-2-(aminoethyl)-3-aminopropyltriethoxydecane, 3-(methylamino)propyltrimethoxynonane, 3-(methylamino)propyltriethoxydecane, and the like.

Further, as the decane coupling agent, an oligomeric alkoxy oligomer (oxyalkylene alkoxy oligomer) containing the above-mentioned organofunctional group or the like can also be used.

The content of the decane coupling agent is preferably 0.01 to 2.0 parts by weight based on 100 parts by weight of the total amount of the monomer other than the hydroxyl group-containing copolymerizable vinyl monomer (monomer belonging to the first monomer group).

As other optional components, known additives such as an antioxidant, a surfactant, a curing accelerator, a plasticizer, a filler, a crosslinking catalyst, a crosslinking retarder, a curing retarder, a processing aid, and an anti-aging agent may be suitably blended. . These may be used alone or in combination of two or more.

For the adhesive layer of the present invention, the adhesive composition is coated After being applied to the substrate and the release film, the adhesive layer of the present invention can be obtained by crosslinking the adhesive composition. The gel fraction of the adhesive layer after crosslinking is preferably 40 to 75%. Further, the weight average molecular weight of the adhesive layer after crosslinking the adhesive composition is preferably from 300,000 to 2,000,000. The weight average molecular weight of the adhesive layer means the average value of all the components contained in the adhesive layer, the acrylic polymer (crosslinked polymer) crosslinked by the crosslinking agent, and the uncrosslinked acrylic polymer (not yet The copolymer) accounts for the majority of the weight of the adhesive layer. Thus, the weight average molecular weight of the adhesive layer substantially corresponds to the weight average molecular weight of the average crosslinked polymer and the uncrosslinked polymer.

When it is used for bonding between layers of an optical member, etc., it is desirable to be a thin adhesive layer. The thickness of the adhesive layer is preferably from 1 μm to 25 μm, more preferably from 5 μm to 25 μm. Further, in general, the adhesive force of the adhesive layer is approximately proportional to the thickness of the adhesive layer, and the adhesive force of the adhesive layer having a thickness of 25 μm is preferably 1.5 to 10 N/25 mm after the adhesion at 23 ° C for 10 days. Examples of the adherend for the adhesion test include a glass plate such as an alkali-free glass, a resin film, and the like.

When the adhesive layer of the present invention is used for bonding between layers of an optical member, etc., in order to reduce reflection of light at the interface between the adhesive layer and the optical member, it is desirable that the difference in refractive index is as small as possible. Therefore, the refractive index of the adhesive layer is preferably 1.47 to 1.50.

When the adhesive layer of the present invention is used for an electronic device such as a touch panel, from the viewpoint of reducing the noise of the electromagnetic field, it is preferable to laminate the adhesive layer to a thickness of 1000 μm and the specific dielectric constant measured at a frequency of 100 kHz is 1.50. ~5.50, and the dielectric loss is 0.01~0.09.

The adhesive film of the present invention can be formed by laminating the adhesive of the present invention It is produced on one side of a substrate or a release film.

As the base film used for the formation of the adhesive layer and the release film (spacer) for protecting the adhesive surface, a resin film such as a polyester film or the like can be used.

The base film may be subjected to an antifouling treatment based on an organic lanthanoid, a fluorine-based release agent or a coating agent, cerium oxide fine particles or the like on the opposite side of the resin film from the side on which the adhesive layer is formed, based on the antistatic agent. Antistatic treatment is carried out by coating, mixing, and the like.

The release film is subjected to a release treatment using an organic hydrazine-based or fluorine-based release agent on the surface on the side where the adhesive surface of the pressure-sensitive adhesive layer is bonded.

A structure in which a release film is applied by bonding a release film to both surfaces of one adhesive layer may form a "release film/adhesive layer/release film". In this case, the release films on both sides are peeled off sequentially or simultaneously, and after exposing the adhesive surface, it can be bonded to an optical member such as an optical film. Examples of the optical film include a polarizing film, a retardation film, an antireflection film, an antiglare (antiglare) film, an ultraviolet absorbing film, an infrared absorbing film, an optical compensation film, and a brightness enhancement film.

The adhesive film of the present invention can be used for various optical films for peripheral members of liquid crystal display devices including polarizing plates, various optical films for touch panels, various optical films for electronic paper, various optical films for organic EL, and the like. Fit.

Further, the adhesive layer may be laminated on at least one surface of these optical films to form an optical film with an adhesive layer. Specifically, "optical film / adhesive layer / optical film", "optical film / adhesive layer / release film", "optical film / adhesive layer", "optical film / adhesive layer / optical film / Adhesive layer / optical film", "optical film / adhesive layer / optical film / adhesive layer / release film", "release film / adhesive layer / optical film / adhesive layer / release film" .

For example, "optical film / adhesive layer / release film", which has protection with a release film Adhesive layer. In this case, the release film is peeled off, such as an "optical film/adhesive layer", and the adhesive layer is exposed, and the film is bonded to other optical films to obtain an adhesion between the layers using an adhesive layer. A structure such as "optical film/adhesive layer/optical film".

The adhesive film of the present invention is suitable for use in bonding a polarizing plate to a display panel. As the display panel, for example, a liquid crystal panel or an organic EL panel can be cited. The adhesive film of the present invention can be suitably used as an adhesive layer of a polarizing plate with an adhesive layer. As a constituent material of the polarizing plate, a retardation film having a phase difference of λ/4 or λ/2 can be used. The adhesive layer of the present invention can be used for the bonding of a retardation film and a polarizing plate. According to the adhesive film of the present invention, the adhesive layer has a low dielectric constant, and therefore, it can be suitably used for a polarizing plate in an On-cell type display device in which a touch sensor is disposed between a color filter and a polarizing plate. The bonding of the optical components with the backlight unit.

[Examples]

Hereinafter, the present invention will be specifically described by way of examples.

<Manufacture of acrylic polymer>

[Example 1]

Nitrogen gas was introduced into a reaction apparatus equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen introduction tube, and the air in the reaction apparatus was replaced with nitrogen. Thereafter, 100 parts by weight of butyl acrylate and 0.2 parts by weight of 8-hydroxyoctyl acrylate were added to the reaction apparatus while 60 parts by weight of a solvent (ethyl acetate) was added thereto. Thereafter, 0.1 part by weight of azobisisobutyronitrile as a polymerization initiator was added dropwise thereto over 2 hours, and the mixture was reacted at 65 ° C for 6 hours to obtain an acrylic polymer solution 1 used in Example 1. A part of the acrylic polymer was used as a measurement sample of an acid value to be described later.

[Examples 2 to 4 and Comparative Examples 1 to 3]

The composition of the monomer was similar to that of the acrylic polymer solution 1 used in the above Example 1 except that the composition of the monomer was as described in the group (1) and the group (2) of Table 1, and Examples 2 to 4 were obtained. And the acrylic polymer solution used in Comparative Examples 1 to 3.

<Manufacture of Adhesive Composition, Adhesive Layer and Adhesive Film>

[Example 1]

To the acrylic polymer solution 1 of Example 1 produced as described above, 0.2 parts by weight of Coronate L (75% ethyl acetate solution of trimethylolpropane (TMP) adduct of toluene diisocyanate (TDI) compound) was added, 0.05 parts by weight of KBM-403 (3-glycidoxypropyltrimethoxydecane) was stirred and mixed to obtain an adhesive composition of Example 1. The adhesive composition was applied onto a release film (poly terephthalic acid (PET) film coated with an organic resin), and then dried at 90 ° C to remove the solvent, and then passed at 23 ° C, 50%. The adhesive composition was cross-linked in an atmosphere of RH for 7 days to form an adhesive layer having a thickness of 25 μm to obtain an adhesive film of Example 1 having an adhesive layer on one side of the release film.

[Examples 2 to 4 and Comparative Examples 1 to 3]

The composition of the additive was carried out in the same manner as in the adhesive film of the above-described Example 1, except that the composition of the additive was as described in the group (3) and the group (4) of Table 1, and the examples 2 to 4 and the comparative examples 1 to 3 were obtained. Adhesive film.

In Table 1, the (meth)acrylic acid alkyl ester monomer having an alkyl group having a C1 to C14 carbon number in the group (1), an alicyclic group-containing monomer, and a branched chain alkyl group-containing single group The total amount of the monomer group constituted by the body was calculated by 100 parts by weight. Further, the numerical values as the parts by weight of the addition ratios from the group (2) to the group (4) are indicated by parentheses. Here, in Example 2, the total amount of the group (1) was 90 parts by weight. Further, in the case of Comparative Examples 1 and 2, the group (1) further contained a (meth) acrylate monomer having an aromatic group.

In addition, the group (2) is a hydroxyl group-containing copolymerizable vinyl monomer, but in Comparative Examples 1 and 3, it is composed of a hydroxyl group-containing copolymerizable vinyl monomer and a carboxyl group-containing copolymerizable vinyl monomer. Monomer group. (3) The group is a crosslinking agent. The group (4) is a decane coupling agent.

Further, the compound names of the abbreviations of the respective components used in Table 1 are listed in Table 2. In addition, Coronate (registered trademark) L is a trade name of Japan Polyurethane Industry Co., Ltd., D-110N is a trade name of Mitsui Chemicals Co., Ltd., and KBM-403 and KBM-803 are trade names of Shin-Etsu Chemical Co., Ltd. TDI stands for toluene diisocyanate, TMP stands for trimethylolpropane, XDI stands for Benzomethylene diisocyanate.

<Test method and evaluation>

The release film (the PET film coated with the organic resin) was peeled off from the adhesive films of Examples 1 to 4 and Comparative Examples 1 to 3 to expose the adhesive layer, and the adhesive layer was transferred to one side of the polarizing plate (film). on.

<Method for measuring adhesion>

An adhesive layer having a thickness of 25 μm was transferred onto one surface of a polarizing plate (film) having a thickness of 180 μm to obtain an adhesive film (an optical film with an adhesive layer) as a sample.

The obtained adhesive film was bonded to a non-tin surface washed with acetone of an alkali-free glass by a pressure roller, and autoclaved at 50 ° C for 0.5 MPa × 20 minutes. Thereafter, it returned to an atmosphere of 23 ° C × 50% RH and passed for 1 hour. For the adhesive film thereafter, the peeling strength was measured by a tensile tester using JIS Z0237 "adhesive tape. Adhesive test method", and the peel strength at the time of peeling at a speed of 300 mm/min in the direction of 180° was adhesion of the adhesive film. Adhesion of the agent layer (N/25mm).

<Method for measuring acid value>

The acid value of the acrylic polymer was measured using a potentiometric automatic titrator (manufactured by Kyoto Electronics Manufacturing Co., Ltd., AT-610). The sample was dissolved in a solvent (diethyl ether and ethanol were mixed at a volume ratio of 2:1), and the potentiometric titration apparatus was used to carry out potentiometric titration with a potassium hydroxide ethanol solution having a concentration of about 0.1 mol/l. And the amount of potassium hydroxide ethanol solution required for the sample. Further, the acid value was determined by the following formula.

Acid value = (B × f × 5.611) / S

B = amount of 0.1 mol/l potassium hydroxide ethanol solution used for titration (ml)

f=0.1mol/l factor of potassium hydroxide ethanol solution

S = quality of solids of the sample (g)

<Method for measuring gel fraction>

After the completion of the etching, the quality of the measurement sample before bonding to the polarizing plate was accurately measured, and after immersing in toluene for 24 hours, it was filtered using a metal mesh of 200 mesh. Thereafter, after the filtrate was dried at 100 ° C for 1 hour, the quality of the residue was accurately measured, and the gel fraction of the adhesive layer (adhesive after crosslinking) was calculated from the following formula.

Gel fraction (%) = insoluble portion quality (g) / adhesive quality (g) × 100

<Test method for durability>

A 10 cm angle adhesive film prepared by the same method as the adhesion measurement The sample prepared by laminating the non-tin surface of the alkali-free glass in the same manner was placed in a predetermined atmosphere (80 ° C dry atmosphere or 60 ° C × 90% RH atmosphere) for 250 hours, and then taken out to 23 ° C × In a 50% RH atmosphere, the state of the adhesive film was visually observed after 1 hour to judge the durability.

○. . The adhesive film is completely free of peeling and foaming.

△. . A part of the adhesive film is peeled and foamed.

×. . The adhesive film as a whole is peeled and foamed.

<Method for Measuring Specific Dielectric Constant and Dielectric Loss>

An adhesive layer having a thickness of 1000 μm was used as a measurement sample. Using a LCR meter, the measurement sample was clamped on a jig of an LCR meter, and the specific dielectric constant and dielectric loss were measured at a frequency of 100 to 200 kHz.

<On-cell panel responsiveness>

After bonding a polarizing plate having an adhesive layer having a thickness of 20 μm on one side to an On-cell panel (TOD, Touch On Display), a touch operation is performed from the surface of the polarizing plate to detect a change in the position of the touch operation. The reactivity was evaluated and evaluated based on the following criteria.

○. . The response is good.

×. . The response is poor.

<Test method for reworkability>

A 10 cm-angle adhesive film prepared by the same method as the measurement of the adhesion force was attached to a non-tin surface of an alkali-free glass in the same manner, and placed in an atmosphere of 70 ° C for 10 days, and then taken out to 23 The adhesiveness of the adhesive film after standing for 1 hour was measured in an atmosphere of ° C to judge the reworkability.

○. . The adhesion after 70 ° C × 10 days is 1.5 to 10 N / 25 mm.

△. . The adhesion after 70 ° C × 10 days is greater than 10 N / 25 mm, but below 20 N / 25 mm.

×. . The adhesion after 70 ° C × 10 days is greater than 20 N / 25 mm (can not be peeled off).

The evaluation results are listed in Tables 3 and 4.

The adhesive films of Examples 1 to 4 are the adhesive films of the present invention, wherein the adhesive layer having a thickness of 25 μm has an adhesive force after 23 ° C × 10 days in the range of 1.5 to 10 N / 25 mm, and the adhesive layer of the crosslinked adhesive layer is coagulated. The gel fraction is 40~75%, and the weight average molecular weight of the adhesive layer after cross-linking is 300,000~2 million, C The acid value of the olefinic polymer is 0.1 or less, and is excellent in adhesion and durability. Further, after the adhesive films of Examples 1 to 4 were bonded to the adherend, the adhesive strength after 70 ° C × 10 days was in the range of 1.5 to 10 N / 25 mm, whereby the reworkability was also excellent. That is, according to the adhesive films of Examples 1 to 4, it is possible to overcome the problems and problems in the prior art.

In the adhesive film of Comparative Example 1, the constituent monomer of the acrylic polymer does not contain butyl acrylate, and contains a (meth) acrylate monomer having an aromatic group and a carboxyl group-containing copolymerizable vinyl monomer, and an adhesive. The gel fraction of the layer is low, the weight average molecular weight of the adhesive layer after crosslinking is small, and the acid value of the acrylic polymer is high. Due to these effects, the adhesive layer of the adhesive layer having a thickness of 25 μm is strong, the durability at 80° C. is slightly poor, the durability at 60° C.×90% RH is poor, and the reworkability is slightly inferior. In addition, the specific dielectric constant and dielectric loss are high, and the On-cell panel responsiveness is poor.

In the adhesive film of Comparative Example 2, the constituent monomer of the acrylic polymer contains a (meth) acrylate monomer having an aromatic group, and the content of the hydroxyl group-containing copolymerizable vinyl monomer is large, and the crosslinking agent is added. The amount is large and the gel fraction is high. Due to these effects, the adhesive layer of the adhesive layer having a thickness of 25 μm is strong, the durability at 60 ° C × 90% RH is poor, and the reworkability is slightly inferior. In addition, the dielectric loss is high and the On-cell panel has poor response.

Since the adhesive film of Comparative Example 3 did not contain a crosslinking agent, the acrylic polymer did not crosslink, and the gel fraction was 0, and the weight average molecular weight of the adhesive layer after crosslinking was small. Further, the acrylic polymer contains a carboxyl group-containing copolymerizable vinyl monomer and has a high acid value. Due to these effects, the adhesive layer having a thickness of the adhesive layer of 25 μm has a very strong adhesive force, and has poor durability and reworkability. In addition, the specific dielectric constant is high, and the On-cell panel is inferior in responsiveness.

Thus, the adhesive films of Comparative Examples 1 to 3 could not overcome the problems and problems in the prior art.

Claims (13)

An adhesive layer which is an adhesive layer obtained by crosslinking an adhesive composition containing an acrylic polymer and a crosslinking agent, wherein the acrylic polymer has a carbon number of C1 to C14 At least one or more monomers in the monomer group composed of the alkyl (meth) acrylate monomer, the alicyclic monomer, and the branched alkyl group-containing monomer, and the hydroxyl group-containing copolymerization property The copolymer obtained by copolymerizing a vinyl monomer contains 30 to 100 parts by weight based on 100 parts by weight of the total of the monomers other than the hydroxyl group-containing copolymerizable vinyl monomer. Methyl)butyl acrylate and 0.1 to 3.5 parts by weight of the hydroxyl group-containing copolymerizable vinyl monomer, the adhesive layer having a gel fraction of 40 to 75%, and the adhesive layer is laminated to 1000 μm The thickness of the specific dielectric constant measured at a frequency of 100 kHz is 1.50 to 5.50, and the dielectric loss is 0.01 to 0.09. The adhesive layer according to claim 1, wherein the acrylic polymer does not contain a (meth) acrylate monomer having an aromatic group and a carboxyl group-containing copolymerizable vinyl monomer. The acrylic polymer has an acid value of 0.1 or less, and contains 0.01 to 1.5 parts by weight of an isocyanate compound as described above with respect to 100 parts by weight of the total of the monomers other than the hydroxyl group-containing copolymerizable vinyl monomer. a cross-linking agent, wherein the adhesive composition has a weight average molecular weight of 300,000 to 2,000,000 after cross-linking, and after laminating the adhesive layer having a thickness of 25 μm on one side of the substrate, passing through 23 ° C × The adhesion after 10 days is 1.5~10N/25mm. The adhesive layer according to claim 1 or 2, wherein the adhesive composition is 100 parts by weight relative to the total amount of the monomers other than the hydroxyl group-containing copolymerizable vinyl monomer. Further, 0.01 to 2.0 parts by weight of a decane coupling agent is contained. The adhesive layer according to any one of claims 1 to 3, wherein the crosslinking agent is an isocyanate compound which is a trimethylolpropane adduct of toluene diisocyanate. The adhesive layer according to any one of claims 1 to 4, wherein the hydroxyl group-containing copolymerizable vinyl monomer is selected from the group consisting of 8-hydroxyoctyl (meth)acrylate, (methyl) At least one or more of the compound group consisting of 6-hydroxyhexyl acrylate, 4-hydroxybutyl (meth) acrylate, and 2-hydroxyethyl (meth) acrylate. An adhesive film in which an adhesive layer according to any one of claims 1 to 5 is laminated on one side of a substrate. The adhesive film according to claim 6, wherein the adhesive film is used for bonding a polarizing plate to a liquid crystal panel or to an organic EL panel. An adhesive film in which the adhesive layer according to any one of claims 1 to 5 is formed on one side of the release film at a thickness of 1 μm to 25 μm, which is a release film/adhesive layer/dissociation layer. The composition of the film. An optical film with an adhesive, wherein an adhesive film according to claim 8 is used on at least one side of the optical film. A polarizing plate with an adhesive layer, wherein an adhesive film according to claim 8 is used on one side of the polarizing plate. The polarizing plate with an adhesive layer according to claim 10, wherein the adhesive layer is used for lamination of a retardation film having a phase difference of λ/4 or λ/2 and the polarizing plate. . A liquid crystal panel in which a polarizing plate with an adhesive layer as described in claim 10 of the patent application is used. An On-cell panel in which a polarizing plate with an adhesive layer as described in claim 10 is used.