KR20160137473A - Adhesive composition and adhesive film - Google Patents

Abstract

The present invention provides a manufacturing method of an adhesive film which has a low dielectric permittivity, excellent insulation performance, conformability to a printing gap, and excellent shape maintaining characteristic, an adhesive composite, and an adhesive film. The method includes: a process (1) of obtaining acrylic polymers by copolymerizing (meth)acrylate on top of polyalkylene glycol(meth)acrylate; a process (2) of making an adhesive composite including an acrylic polymer, a vinyl monomer with a polyalkylene oxide chain, a photo-polymerization initiator, and a cross linking agent for a total 100g of an acrylic polymer with a total 0.1 to 20 moles of a vinyl monomer with a polyalkylene oxide chain selected from the polyalkylene glycol(meth)acrylate; and a process (3) of forming an adhesive layer of which the specific inductive capacity at the frequency of 1MHz is equal to or less than 3.5 by applying the adhesive composite and heating.

Description

[0001] ADHESIVE COMPOSITION AND ADHESIVE FILM [0002]

The present invention relates to a method for producing an adhesive film, a pressure-sensitive adhesive composition and a pressure-sensitive adhesive film used for interlaminar bonding of an optical member and the like. More particularly, the present invention relates to a pressure-sensitive adhesive composition containing only an acryl-based monomer having a general structure as a main component, a process for producing an adhesive film having a low dielectric constant, excellent insulation performance, To an adhesive film.

In addition, the pressure-sensitive adhesive composition according to the present invention can be used as an electrical insulating material in which an electric member and an electronic circuit member are joined together in addition to an optical member. Further, the adhesive film according to the present invention can be used as a film for a touch panel having an electrical insulation, an electronic paper film, and a display film.

Recently, the amount of information to be handled is rapidly increasing, as represented by the transmission of moving images via optical fiber communication lines and wireless communication lines. As a result, there is a demand for miniaturization, high frequency and high speed of electronic and electric devices, and improvement of safety and reliability is required. For this reason, it is required to use an electrically insulating material having a low dielectric constant in response to the high frequency of electronic and electric devices.

BACKGROUND ART [0002] Conventionally, in order to obtain an electrical insulating material having a low dielectric constant, it has been proposed to form a hollow structure in an electrical insulating material (see, for example, Patent Documents 1 to 3).

Patent Document 1 discloses an electrical insulating member in which a foamed pressure-sensitive adhesive layer is laminated on one side of an electrical insulating material containing a microcavity in a synthetic resin film such as polyethylene terephthalate.

Patent Document 2 discloses an adhesive film using a pressure-sensitive adhesive containing a minute tool body (microballoons) such as glass or silica so that the dielectric constant of the insulating material is 2.5 or less.

Patent Document 3 discloses a wire insulating film made of an inorganic porous microporous film containing silica in a polyolefin resin.

It has also been proposed to use a liquid crystal polymer having a low dielectric constant as a substrate for an insulating adhesive film having a low dielectric constant (see, for example, Patent Document 4).

Patent Document 5 discloses a pressure-sensitive adhesive layer having a relative dielectric constant of 3.5 or less at a frequency of 100 kHz, comprising 30 to 99.5% by weight of an alkyl (meth) acrylate having an alkyl group of 10 to 18 carbon atoms at the ester terminal and a cyclic nitrogen- (Meth) acryl-based polymer obtained by polymerizing a monomer component containing 0.5 to 50 wt% of a (meth) acrylic polymer.

In recent years, for the purpose of improving the operability of electronic devices, a smart phone equipped with a capacitive touch panel (a multifunctional mobile phone combining functions of a mobile phone and a portable information terminal), a tablet, a notebook equipped with a touch panel Is rapidly spreading.

However, since the capacitive touch panel is a sensor that senses a change in an electromagnetic field, it is susceptible to the influence of noise, and in order to prevent the erroneous recognition of the contact position, a low dielectric constant film is laminated in the laminated structure, (See, for example, Patent Documents 6 and 7).

Patent Document 8 will be described later.

Japanese Laid-Open Patent Publication No. 11-025757 Japanese Patent Application Laid-Open No. 11-288621 Japanese Laid-Open Patent Publication No. 2006-024473 Japanese Laid-Open Patent Publication No. 2003-321659 Japanese Laid-Open Patent Publication No. 2013-082880 Japanese Laid-Open Patent Publication No. 2012-094017 Japanese Laid-Open Patent Publication No. 2013-003758 Japanese Laid-Open Patent Publication No. 2011-162659

However, in an optical film used for various image display displays such as a PDP, a liquid crystal panel, and an organic EL panel, or an optical adhesive film, high transparency is required for improving visibility. However, in the method of mixing silica fine particles to form a hollow structure in the synthetic resin or pressure sensitive adhesive layer disclosed in Patent Document 3, the particle diameter of the silica fine particles is set to be 400 nm (0.4 탆 or less), which is the wavelength of the red light of the visible light , The total light transmittance due to light scattering is lowered. However, since the silica fine powder having a particle diameter of 0.4 탆 or less is expensive due to its difficulty in production, there is a problem that it can not be used for manufacturing a general-purpose insulator which is inexpensive.

The invention described in Patent Document 4 is intended to provide a more economical adhesive film for electrical and electronic insulation that maintains excellent heat resistance, moisture resistance, and dielectric properties. Therefore, although the adhesive film according to the invention of Patent Document 4 uses a liquid crystal polymer having a low dielectric constant as a base material, since a general silicone adhesive is used for the adhesive layer, the dielectric constant of the adhesive film can be further reduced, none.

In addition, the pressure sensitive adhesive according to Patent Document 5 has a good dielectric property with a relative dielectric constant of 3.5 or less at a frequency of 100 kHz, but does not describe the dielectric constant at around 1 MHz, which is the mainstream driving frequency of the touch panel at present.

Patent Documents 6 and 7 disclose that a low dielectric constant film is laminated in the laminated structure or a low dielectric constant member is formed in the wiring line of the capacitance sensor in order to prevent the mistaken recognition of the capacitive touch panel. The method of manufacturing the dielectric constant member is not specifically disclosed.

Thus, in the prior art, there has been no known method for producing an adhesive film, a pressure-sensitive adhesive composition and a pressure-sensitive adhesive film which can be used for bonding an optical member and have excellent insulating performance due to a low dielectric constant.

A black frame of a light shielding layer formed by screen printing or the like is disposed on the surface of a front glass plate of a general display, and a step of about several micrometers to 50 m in thickness is formed between the front glass plate and the black frame of the light shielding layer. For example, in many cases, a protective frame of a cellular phone or the like is provided with a print frame having a thickness of about 10 mu m to several tens of mu m for improving the design. The ITO layer of the touch panel device is also provided with an electrode for transmitting a current in the touch panel, and a printed stepped portion having a thickness of several micrometers to several tens of micrometers is formed on the wiring portion by the printing. As described above, there are many configurations in which a step is present on the surface of an adherend when the adhesive film is used to adhere various optical films or protective plates to a display or when the ITO layer is to be adhered to another film or the like using a pressure-sensitive adhesive layer.

If there is a step difference due to a printed layer or the like on the surface of the adherend, there is a problem that the adhesive film fails to follow the step and bubbles are generated by lifting generated and a gap is generated between the adhesive film and the adherend. In order to solve this problem, various attempts have conventionally been made. There is a need for a method for producing an adhesive film, a pressure-sensitive adhesive composition, and an adhesive film overcoming the above-mentioned requirements and problems.

As a method of improving the followability with respect to the printing step, a method of lowering the storage elastic modulus of the pressure-sensitive adhesive layer as in the case of the pressure-sensitive adhesive film according to Patent Document 8 is known. However, if the storage elastic modulus of the pressure-sensitive adhesive layer is lowered, the pressure-sensitive adhesive layer tends to be deformed, and the adherend may be fixed for a long period of time and the shape of the pressure-sensitive adhesive layer may not be maintained.

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a pressure-sensitive adhesive composition having a low dielectric constant, excellent insulation performance, followability to a printing step, and good shape retention even though it is an adhesive composition containing only an acrylic monomer having a general structure as a main component A production method thereof, a pressure-sensitive adhesive composition and a pressure-sensitive adhesive film.

DISCLOSURE OF THE INVENTION In order to solve the above problems, the present invention provides a pressure-sensitive adhesive composition containing only an acryl-based monomer having a general structure as a main component, but also includes a pressure- , A pressure-sensitive adhesive layer having excellent insulation performance due to a low dielectric constant, ability to follow print steps, and excellent shape retention.

For this reason, the pressure-sensitive adhesive film according to the present invention is used after being thermally cured, in the form of an adhesive film before cross-linking by ultraviolet irradiation, and after cementing onto an adherend having a printing step, Layer.

An adherend having no printing step can be used in the form of an adhesive film having a pressure-sensitive adhesive layer formed by copolymerization and crosslinking by heating and light irradiation.

Further, in order to solve the above problems, the present invention provides a method for producing an adhesive film for use in bonding an optical member, comprising the steps of (1) to (3)

Step (1): a step of copolymerizing monomers of two or more kinds of (meth) acrylates other than polyalkylene glycol (meth) acrylate to obtain an acrylic polymer,

Step (2): The total amount of vinyl monomers having one or more kinds of polyalkylene oxide chains selected from the group of compounds of polyalkylene glycol (meth) acrylate relative to 100 g in total of the acrylic polymer is 0.1 to 20 moles A step of preparing a pressure-sensitive adhesive composition comprising the acrylic polymer, the vinyl monomer having the polyalkylene oxide chain, a photopolymerization initiator and a crosslinking agent,

Step (3): The pressure-sensitive adhesive composition was coated on one side of a previously prepared release film and then heated to copolymerize to form a pressure-sensitive adhesive layer having a relative dielectric constant of 3.5 or less at a frequency of 1 MHz, Process for producing an adhesive film having a film structure

In order from the side of the adhesive film.

Further, the present invention is a method for producing an adhesive film used for bonding an optical member, comprising the steps of: (1)

Step (1): a step of copolymerizing monomers of two or more kinds of (meth) acrylates other than polyalkylene glycol (meth) acrylate to obtain an acrylic polymer,

Step (2): The total amount of vinyl monomers having one or more kinds of polyalkylene oxide chains selected from the group of compounds of polyalkylene glycol (meth) acrylate relative to 100 g in total of the acrylic polymer is 0.1 to 20 moles A step of preparing a pressure-sensitive adhesive composition comprising the acrylic polymer, the vinyl monomer having the polyalkylene oxide chain, a photopolymerization initiator and a crosslinking agent,

Step (3): A step of applying a pressure-sensitive adhesive composition on one side of a previously prepared base film and then heating and copolymerizing to form a pressure-sensitive adhesive layer having a relative dielectric constant of 3.5 or less at a frequency of 1 MHz to produce an adhesive film

In the order from the base material to the base material.

Further, it is preferable that the pressure-sensitive adhesive film is irradiated with light to crosslink the pressure-sensitive adhesive composition.

The polyalkylene glycol (meth) acrylate is represented by the following formula (1)

CH ₂ = C (R ¹ ) -COO- (R ² -O) _n -R ³ (1)

(Wherein R ¹ represents a hydrogen atom or a methyl group, R ² represents an alkylene group having 2 to 4 carbon atoms, R ³ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and n represents an integer of 1 to 23 ).

Further, it is preferable that the monomer of the two or more kinds of (meth) acrylates is selected from the group of compounds of a copolymerizable vinyl monomer having any one of an alkyl group, a hydroxyl group, a carboxyl group, an amide group, an imide group and an aromatic group.

The present invention also provides a pressure-sensitive adhesive composition comprising a copolymerizable and crosslinked pressure-sensitive adhesive composition constituting a pressure-sensitive adhesive layer for a pressure-sensitive adhesive film to be used for bonding an optical member, wherein at least two (meth) acrylate monomers other than polyalkylene glycol To 100 g of a total of 100 g of the acryl-based polymer obtained by copolymerizing a polyalkylene glycol (meth) acrylate with a vinyl monomer having one or more kinds of polyalkylene oxide chains selected from the group of polyalkylene glycol (meth) And a pressure-sensitive adhesive composition comprising the acryl-based polymer, the vinyl monomer having the polyalkylene oxide chain, the photopolymerization initiator, and the cross-linking agent are copolymerized and crosslinked.

The polyalkylene glycol (meth) acrylate is represented by the following formula (1)

CH ₂ = C (R ¹ ) -COO- (R ² -O) _n -R ³ (1)

(Wherein R ¹ represents a hydrogen atom or a methyl group, R ² represents an alkylene group having 2 to 4 carbon atoms, R ³ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and n represents an integer of 1 to 23 ).

Further, it is preferable that the monomer of the two or more kinds of (meth) acrylates is selected from the group of compounds of a copolymerizable vinyl monomer having any one of an alkyl group, a hydroxyl group, a carboxyl group, an amide group, an imide group and an aromatic group.

The total amount of the alkyl (meth) acrylate compound groups in the total amount of all the monomers in 100 parts by weight is preferably 50 parts by weight or more.

The present invention also provides a pressure-sensitive adhesive film comprising a pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive composition formed on one side of a release film and having the structure of a release film / the pressure-sensitive adhesive layer / release film.

The present invention also provides an adhesive film comprising a substrate film and a pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive composition formed on one side thereof.

The relative dielectric constant of the pressure-sensitive adhesive layer at a frequency of 1 MHz is preferably 3.5 or less.

According to the present invention, it is possible to overcome the conventional requirements and problems, and it is an object of the present invention to provide a pressure-sensitive adhesive composition containing only an acrylic monomer having a general structure and having excellent insulation performance by a low dielectric constant, A method for producing an adhesive film, a pressure-sensitive adhesive composition and a pressure-sensitive adhesive film.

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

The method for producing an adhesive film of the present invention comprises the following steps (1) to (3)

Step (1): a step of copolymerizing monomers of two or more kinds of (meth) acrylates other than polyalkylene glycol (meth) acrylate to obtain an acrylic polymer,

Step (2): The total amount of vinyl monomers having one or more kinds of polyalkylene oxide chains selected from the group of compounds of polyalkylene glycol (meth) acrylate relative to 100 g in total of the acrylic polymer is 0.1 to 20 moles A step of preparing a pressure-sensitive adhesive composition comprising the acrylic polymer, the vinyl monomer having the polyalkylene oxide chain, a photopolymerization initiator and a crosslinking agent,

Step (3): A step of applying a pressure-sensitive adhesive composition to one side of a film prepared in advance and then copolymerizing by heating to form a pressure-sensitive adhesive layer having a relative dielectric constant of 3.5 or less at a frequency of 1 MHz to produce an adhesive film

In order. Here, the film used in the step (3) may be a base film or a release film.

The pressure-sensitive adhesive layer of the present invention is a pressure-sensitive adhesive layer obtained by copolymerizing 100 g of the acrylic polymer obtained by copolymerizing monomers of two or more (meth) acrylates other than the polyalkylene glycol (meth) acrylate with the polyalkylene glycol (meth) A vinyl monomer having the polyalkylene oxide chain, a photopolymerization initiator, and a photopolymerization initiator, in an amount of 0.1 to 20 moles of the total of the vinyl monomer having one or more polyalkylene oxide chains selected from the group consisting of And a pressure-sensitive adhesive composition comprising a crosslinking agent is copolymerized and crosslinked.

The polyalkylene glycol (meth) acrylate having a polyalkylene oxide chain, which is used as a raw material for the pressure-sensitive adhesive layer according to the present invention, has a function of remarkably reducing the relative dielectric constant. The reason why the polyalkyleneglycol (meth) acrylate is contained in the acrylic polymer and the copolymerization and cross-linking are carried out and the relative dielectric constant is remarkably reduced is not clear, but the following reason is considered to be one of the reasons.

(1) The pressure-sensitive adhesive layer according to the present invention is obtained by copolymerizing and crosslinking a pressure-sensitive adhesive composition containing an acryl-based polymer and a polyalkylene glycol (meth) acrylate. The acrylic copolymer after copolymerization and cross-linking has a plurality of polyalkylene oxide chains (here abbreviated as " whiskers ") elongated as long side chains. For this reason, the acrylic copolymer (polymer) is not elongated only in the longitudinal direction but has a thick shape due to the effect of "whiskers" elongated in the transverse width direction orthogonal to the longitudinal direction. That is to say, a structure having a dendritic shape which is difficult to be polarized even when a high frequency electric charge is applied reduces the dielectric constant.

(2) In addition, a plurality of "beard" stretched as side chains of the acrylic copolymer (polymer) interfere with each other to prevent the skeleton portions of the acrylic copolymer (polymer) from approaching each other, Fine pores composed of a plurality of air layers are generated, and the relative dielectric constant is reduced.

Examples of the polyalkylene glycol (meth) acrylate selected as the vinyl monomer (monomer B) having a polyalkylene oxide chain include a repeating structure of a polyalkylene oxide chain such as an ethylene oxide chain, a propylene oxide chain and a butylene oxide chain Or one or more compounds having two or more kinds of them.

The polyalkylene glycol (meth) acrylate represented by the formula (1) is a monofunctional (meth) acrylate having one (meth) acryloyl group per molecule represented by CH ₂ C (R ¹ ) -CO- . A compound having a (meth) acryloyl group at one end of an alkylene oxide chain or a compound having a (meth) acryloyl group at one end of an alkylene oxide chain randomly or block-bonded with an ethylene oxide chain, a propylene oxide chain or a butylene oxide chain (Meth) acryloyl group may be used.

Wherein the polyalkylene glycol (meth) acrylate is represented by the following formula (1)

CH ₂ = C (R ¹ ) -COO- (R ² -O) _n -R ³ (1)

(Wherein R ¹ represents a hydrogen atom or a methyl group, R ² represents an alkylene group having 2 to 4 carbon atoms, R ³ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and n represents an integer of 1 to 23 ).

It is preferable that the polyalkylene glycol (meth) acrylate is a monomer of (meth) acrylate having an ethylene oxide chain, a propylene oxide chain, or a butylene oxide chain and the number of repetition of which is 2 to 23.

More preferably, it is a polyalkylene glycol (meth) acrylate having a repeating number of 5 to 23 in the polyalkylene oxide chain. In polyalkylene glycol (meth) acrylates wherein the number of repeating polyalkylene oxide chains is less than 2, it is difficult to set the relative dielectric constant at a frequency of 1 MHz to 3.5 or less. This is because, in the polyalkylene glycol (meth) acrylate having a repeating number of polyalkylene oxide chains of more than 23, the relative dielectric constant at a frequency of 1 MHz hardly decreases as compared with a compound having a repetition number of 23 or less.

Examples of the monomer of the polyalkylene glycol (meth) acrylate having a polyethylene oxide chain include methoxypolyethylene glycol (meth) acrylate, ethoxypolyethylene glycol (meth) acrylate, and polyethylene glycol (meth) have.

Examples of the monomer of the polyalkylene glycol (meth) acrylate having a polypropylene oxide chain include methoxypolypropylene glycol (meth) acrylate, ethoxypolypropylene glycol (meth) acrylate, polypropylene glycol (meth) And the like.

Examples of the monomer of the polyalkylene glycol (meth) acrylate having a polybutylene oxide chain include methoxypolybutylene glycol (meth) acrylate, ethoxypolybutylene glycol (meth) acrylate, polybutylene glycol Methacrylate, and the like.

Examples of the monomer of the polyalkylene glycol (meth) acrylate having both the polyethylene oxide chain and the polypropylene oxide chain include polyethylene glycol · polypropylene glycol (meth) acrylate and the like.

Specific examples of the polyalkylene glycol (meth) acrylate having a commercially available polyalkylene oxide chain, which are generally available, include the following.

For example, NK ester AM30G (methoxypolyethylene glycol acrylate, repeating number of polyalkylene oxide chain: n = 3), NK ester M40G (methoxypolyethylene glycol methacrylate , n = 4), NK ester AM90G (methoxypolyethylene glycol acrylate, n = 9), NK ester M90G (methoxypolyethylene glycol methacrylate, n = 9), NK ester AM130G (methoxypolyethylene glycol acrylate, n = 13) and NK ester AM230G (methoxypolyethylene glycol acrylate, n = 23).

(Methoxy triethylene glycol acrylate, n = 3), light acrylate 130A (methoxypolyethylene glycol acrylate, n = 9) and the like were used as the trade name of Kyoeisha Chemical Co., Ltd. .

(Trade name) manufactured by Nichiyu K.K., a blender AE-200 (polyethylene glycol acrylate, n = 4.5), a blender AE-350 (polyethylene glycol acrylate, n = 8), a blemmer AE- (Polyethylene glycol methacrylate, n = 8), blemmer AP400 (polypropylene glycol acrylate, n = 10), Blemmer PE-200 (polyethylene glycol methacrylate, (Polypropylene glycol acrylate, n = 9), blemmer PP-500 (polypropylene glycol methacrylate, n = 9), blemmer PP-800 (polypropylene glycol methacrylate (Methacryloxypropyleneglycol acrylate, n = 9), Blemmer PME-200 (n = 16), Blemmer PP-1000 (polypropylene glycol methacrylate, Methoxypolyethylene glycol methacrylate, n = 4), Blemmer PME-400 (methoxypolyethylene glycol methacrylate A relay agent, n = 9), block remmeo PME-1000 (methoxypolyethylene glycol methacrylate, n = 23), etc. may be mentioned.

MPE400A (methoxypolyethylene glycol acrylate, n = about 7), MPE550A (methoxypolyethylene glycol acrylate, n = about 9), and the like can be given as trade names of Osaka Organic Chemical Industry Co.,

In the pressure-sensitive adhesive layer according to the present invention, the content of the polyalkylene glycol (meth) acrylate in the total of the acrylic monomers of the pressure-sensitive adhesive composition (100 g thereof) is preferably in the range of 0.1 to 20 moles. More preferably from 0.1 to 15 mol. When the content of the polyalkylene glycol (meth) acrylate is less than 0.1 mol, the effect of reducing the relative dielectric constant of the pressure-sensitive adhesive layer is small, and it is difficult to set the relative dielectric constant of the pressure-sensitive adhesive layer to 3.5 or less. When the content of the polyalkylene glycol (meth) acrylate is more than 20 mol, the viscosity of the pressure-sensitive adhesive composition becomes excessively high and the copolymerization reaction becomes difficult, which is not preferable.

The content of the polyalkylene glycol (meth) acrylate in the whole of the acrylic monomer (assuming 100 g thereof) of the pressure-sensitive adhesive composition is in the range of 0.1 to 20 mols, and after crosslinking by irradiation with ultraviolet rays when the title to the storage elastic modulus (unit ㎩) in 30 ℃ of the adhesive layer prior to the K1, K1 is a pressure-sensitive adhesive layer is 2 × 10 ⁴ ~1 × 10 ⁵ ㎩ range is obtained.

As a result, a pressure-sensitive adhesive layer and a pressure-sensitive adhesive film having excellent followability to a printing step and excellent shape retention are obtained. When the pressure-sensitive adhesive layer is excellent in shape retention, the adhered state (original positional relationship) of the adherend can be maintained between the adherends on both sides of the pressure-sensitive adhesive layer (or between the base film and the adherend). It is also possible to maintain the shape of the device manufactured by bonding the pressure-sensitive adhesive layer. If K1 exceeds 1 x 10 < ⁵ > Pa, the pressure-sensitive adhesive layer is hardly deformed at the time of curing, so there is no traceability to the printing step difference and a gap is generated in the printing step part.

Further, when the storage elastic modulus (unit Pa) at 30 캜 of the pressure-sensitive adhesive layer after crosslinking by ultraviolet irradiation is represented by K2, if K2 is less than 3 10 ⁵ Pa, the pressure-sensitive adhesive layer is easily deformed, Can not be fixed over a long period of time or the shape of the pressure-sensitive adhesive layer can not be maintained.

The acrylic polymer (polymer A) according to the present invention is obtained by copolymerizing a monomer (monomer A) of two or more kinds of (meth) acrylates other than the polyalkylene glycol (meth) acrylate. The monomer A is preferably selected from a group of compounds of a copolymerizable vinyl monomer having any one of an alkyl group, a hydroxyl group, a carboxyl group, an amide group, an imide group and an aromatic group. The polymer (A) is preferably a polymer having no polyalkylene oxide chain in the side chain.

Examples of the alkyl (meth) acrylate monomer having an alkyl group of C1 to C14 include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) (Meth) acrylate, isobutyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, (Meth) acrylate, nonyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (Meth) acrylate, tetradecyl (meth) acrylate, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate and the like. The alkyl group of the alkyl (meth) acrylate monomer may be any of linear, branched and cyclic.

In the pressure-sensitive adhesive layer according to the present invention, it is preferable that the alkyl (meth) acrylate monomer having an alkyl group of C1 to C14 contained in the pressure-sensitive adhesive composition is 95.5 to 25 parts by weight based on 100 parts by weight of the total amount of the acrylic monomers .

Other copolymerizable monomers include vinyl monomers such as vinyl acetate, vinyl propionate, styrene,? -Methyl styrene, N-vinyl caprolactam and N-vinyl pyrrolidone; Glycol-based acrylic ester monomers such as (meth) acrylic acid polyethylene glycol, (meth) acrylic acid polypropylene glycol, (meth) acrylic acid methoxyethylene glycol and (meth) acrylic acid methoxypolypropylene glycol; Acrylate monomers such as (meth) acrylic acid tetrahydrofurfuryl, fluorine (meth) acrylate, silicone (meth) acrylate and 2-methoxyethyl acrylate; Amide group-containing monomers, amino group-containing monomers, imide group-containing monomers, and nitrogen-containing monomers such as N-acryloylmorpholine; Vinyl ether monomers and the like can also be used.

Among them, a nitrogen-containing monomer such as a vinyl monomer having an amide group having no active hydrogen, or a vinyl monomer having an amino group having no active hydrogen may be contained, if necessary, in order to adjust the cohesive force of the pressure-sensitive adhesive. Here, " active hydrogen " means a hydrogen atom other than carbon, for example, bonded to an atom such as oxygen or nitrogen.

Examples of the nitrogen-containing monomer having no active hydrogen include cyclic nitrogen vinyl compounds such as N-vinylpyrrolidone, N-vinylcaprolactam and (meth) acryloylmorpholine, N-ethyl- (Meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-di (Meth) acrylates such as ethyl (meth) acrylamide, N, N-dipropyl (meth) acrylamide, N, N-diisopropyl (meth) acrylamide and N, Acrylamide, N-methyl-N-isopropylaminoethyl (meth) acrylate, N-methyl- N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N, N-dimethylamino (Meth) acrylates such as N, N-dimethylaminoethyl (meth) acrylate, N, N-dipropylaminoethyl (meth) acrylate and N, N-dibutylaminoethyl (Meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N, N-dimethylaminopropyl ) Acrylamide, N, N-diethylaminopropyl (meth) acrylamide, N, N-dipropylaminopropyl (meth) acrylamide, N, Dialkyl-substituted aminoalkyl (meth) acrylamides such as ethylaminoethyl (meth) acrylamide, and the like.

The nitrogen-containing monomer is preferably free of active hydrogen and more preferably free of a hydroxyl group and a carboxyl group in order to be distinguishable from a vinyl monomer having a hydroxyl group described later. Examples of such monomers include acrylic monomers containing the above-exemplified monomers, for example, N, N-dialkyl substituted amino groups and N, N-dialkyl substituted amide groups; N-vinyl substituted lactams such as N-vinyl pyrrolidone and N-vinyl caprolactam; And N- (meth) acryloyl-substituted cyclic amines such as N- (meth) acryloylmorpholine.

In the pressure-sensitive adhesive layer according to the present invention, examples of the vinyl monomer having an amide group contained in the pressure-sensitive adhesive composition include N-vinylpyrrolidone, N, N-dimethyl (meth) acrylamide, N, (Meth) acrylamide, N, N-dipropyl (meth) acrylamide, N, N-diisopropyl Acrylamide, N, N-diethylaminopropyl (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylamide and N-vinylcaprolactam are particularly preferably used.

Further, in the pressure-sensitive adhesive layer according to the present invention, the nitrogen-containing monomer having no active hydrogen contained in the pressure-sensitive adhesive composition can impart necessary adhesive strength and durability to the pressure-sensitive adhesive layer. Therefore, in applications where a large adhesive force with an adherend is required for the pressure-sensitive adhesive layer, the adhesive strength can be adjusted by adding or subtracting the content ratio of nitrogen monomers having no active hydrogen in the same manner as the carboxyl group-containing monomer. In addition, in applications where it is not preferable to contain a carboxyl group-containing monomer, for example, in the case where the adherend is an ITO transparent conductive film, a nitrogen-containing monomer having no active hydrogen may be used instead of a carboxyl group- .

Examples of the hydroxyl group-containing copolymerizable vinyl monomers (hydroxyl group-containing monomers) include 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4-hydroxybutyl (Meth) acrylates such as N-hydroxy (meth) acrylate, 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) (Meth) acrylamides having a hydroxyl group such as hydroxymethyl (meth) acrylamide and N-hydroxyethyl (meth) acrylamide. In the present invention, 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate are preferable.

In the pressure-sensitive adhesive layer according to the present invention, the hydroxyl group-containing monomer to be contained in the pressure-sensitive adhesive composition is preferably such that the pressure-sensitive adhesive layer to be obtained is a carboxyl group-containing monomer which is considered to have an influence on corrosiveness to an adherend, As a copolymerizable monomer for reducing the content of the monomer. For this reason, the monomer containing a hydroxyl group can help to improve the adhesion of the pressure-sensitive adhesive layer and also to reduce the corrosiveness.

Examples of the carboxyl group-containing copolymerizable vinyl monomers (carboxyl group-containing monomers) include (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, 2- (meth) acryloyloxyethyl (Meth) acryloyloxyethylphthalic acid, 2- (meth) acryloyloxyethylsuccinic acid, 2- (meth) acryloyloxyphthalic acid, 2- (Meth) acrylate, carboxypolycaprolactone mono (meth) acrylate, 2- (meth) acryloyloxyethyltetrahydrophthalic acid, and the like. In the present invention, (meth) acrylic acid is preferable.

Further, in the pressure-sensitive adhesive layer according to the present invention, the carboxyl group-containing monomer contained in the pressure-sensitive adhesive composition can impart necessary cohesive force to the pressure-sensitive adhesive layer. For this reason, in applications where the pressure-sensitive adhesive layer is required to have a large adhesive force with an adherend, the content of the carboxyl group-containing monomer can be increased or decreased to adjust the adhesive strength.

In the pressure-sensitive adhesive layer according to the present invention, one or more copolymerizable vinyl monomers (functional group-containing copolymerizable monomers) selected from the group of copolymerizable vinyl monomers having any one or more functional groups out of a hydroxyl group and a carboxyl group, Is preferably 0.5 to 15 parts by weight based on 100 parts by weight of the total amount of the acrylic monomers.

The functional group-containing copolymerizable monomer is preferably 0.5% by weight or more based on 100 parts by weight of the total of the acrylic monomer components in view of maintaining the adhesive force and the cohesive force. On the other hand, if the amount of the above-mentioned functional group-containing copolymerizable monomer is too large, the pressure-sensitive adhesive may be hardened and the adhesive force may be lowered. In addition, since the viscosity of the pressure-sensitive adhesive composition may become excessively high or gelation may occur, Is preferably 15% by weight or less based on 100 parts by weight of the total of the acrylic monomer components.

Examples of the copolymerizable vinyl monomer having an amide group include (meth) acrylamides other than (meth) acrylate having an amide group such as N- [2- (acryloyloxy) ethyl] acetamide.

Examples of the copolymerizable vinyl monomer having an imide group include (meth) acrylates having an imide group such as N- [2- (acryloyloxy) ethyl] phthalimide.

Examples of the copolymerizable vinyl monomer having an aromatic group include (meth) acrylates having an aromatic group such as phenyl (meth) acrylate, benzyl (meth) acrylate and phenoxyethyl (meth) acrylate, styrene, Of non-acrylic vinyl monomers having an aromatic group.

The polymerization method of the polymer (A) is not particularly limited, and a well-known polymerization method such as a solution polymerization method and an emulsion polymerization method can be used. The polymer (A) preferably has a weight average molecular weight of 200,000 to 200,000.

The monomer composition of the polymer (A) includes 50 to 100 parts by weight of an acrylic monomer such as a (meth) acrylic acid ester monomer, (meth) acrylic acid or (meth) acrylamides relative to 100 parts by weight of the polymer desirable.

In the pressure-sensitive adhesive composition, properties such as required physical properties can be adjusted by adding a crosslinking agent or an optional additive to the polymer (A) and the monomer (B). A pressure-sensitive adhesive composition comprising a polymer (A), a monomer (B), a photopolymerization initiator and a crosslinking agent is prepared at a ratio of the total amount of the monomers (B) to 100 g of the polymer (A) . According to the present invention, the monomer (B) is added to the polymer (A), which is a general acrylic pressure-sensitive adhesive, and the monomer (B) is copolymerized with the polymer (A) by heating and further crosslinked by ultraviolet irradiation have. That is, the monomer (B) can be added only when a general adhesive product is produced (using a general-purpose adhesive) and only when a pressure-sensitive adhesive product requiring low-permittivity performance is produced. Therefore, it is advantageous in terms of cost and management because it can produce an adhesive product having a low dielectric constant without making an inventory of "adhesive for a low dielectric constant adhesive product". Further, the pressure-sensitive adhesive having a low dielectric constant can be obtained only by adding the monomer (B) and the photoinitiator to a pressure-sensitive adhesive which has been used in the past. Further, by changing the kind and amount of the monomer (B) added to the solid content of the pressure-sensitive adhesive, the relative dielectric constant can be controlled. There is a possibility that it is possible not only to lower the relative permittivity but also to produce a product matching the desired relative dielectric constant.

Examples of the crosslinking agent include biuret-modified or isocyanurate-modified products of diisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, tolylene diisocyanate and xylylene diisocyanate, trimethylol Polyisocyanate compounds such as propane and adducts of tri- or higher-valent polyols such as glycerin, metal-based chelate compounds, and epoxy compounds. Further, the pressure-sensitive adhesive may be crosslinked by photo-crosslinking such as ultraviolet rays.

When the acrylic copolymer is crosslinked using a crosslinking agent, it is preferable that the acrylic copolymer has a functional group capable of performing a crosslinking reaction with the crosslinking agent (depending on the type of crosslinking agent, but having a hydroxyl group or a carboxyl group) Containing monomer is preferably contained. It is also preferable that the pressure-sensitive adhesive composition contains 0.01 to 5 parts by weight of a crosslinking agent based on 100 parts by weight of the total of the acrylic monomers.

Known additives such as a silane coupling agent, 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 antioxidant may be appropriately added have. These may be used alone or in combination of two or more. In the application of electric insulation, it is preferable that the pressure-sensitive adhesive does not contain ionic compounds such as alkali metal salts, alkaline earth metal salts and quaternary onium salts, conductors such as metals, carbon, antistatic agents and the like.

The pressure-sensitive adhesive layer of the present invention can be obtained by applying the pressure-sensitive adhesive composition to a base film or a release film, and then crosslinking the pressure-sensitive adhesive composition.

When the pressure-sensitive adhesive layer according to the present invention is used as an electric insulating material having a low dielectric constant corresponding to the high frequency of electronic and electric devices, the relative dielectric constant of the pressure-sensitive adhesive layer at a frequency of 1 MHz is preferably 3.5 or less, desirable.

It is preferable that the total amount of the alkyl (meth) acrylate compound groups in the total amount of 100 parts by weight of all the monomers in the pressure-sensitive adhesive composition comprising the copolymerization and crosslinking constituting the pressure-sensitive adhesive layer for a pressure-sensitive adhesive film is 50 parts by weight or more. By increasing the proportion of the alkyl (meth) acrylate having a low polarity, the relative dielectric constant can be lowered.

The thickness of the pressure-sensitive adhesive layer of the present invention is not particularly limited and is about 5 to 400 mu m. For example, when the pressure-sensitive adhesive layer for electronic insulation of the present invention is used in a capacitive touch panel, the relative dielectric constant? _R of the pressure-sensitive adhesive layer and the thickness (pressure-sensitive adhesive layer) Since the responsiveness of the capacitive touch panel varies depending on the sensor, it is necessary to control the relative dielectric constant and the adhesion thickness according to the design of the mounted electronic device. In recent years, it is required to reduce the thickness of electronic devices and touch panels, and the pressure-sensitive adhesive layer as a constituent member also needs to be thinned. By using the pressure-sensitive adhesive layer of the present invention, the sensitivity equivalent to that in the case of using the conventional pressure-sensitive adhesive layer can be realized with a thin thickness of adhesion.

In the case where the prevention of malfunction is emphasized, the response speed and sensitivity of the touch panel can be expected to be improved by replacing the conventional pressure-sensitive adhesive layer with the pressure-sensitive adhesive layer of the present invention.

Formula: C =? _R ?? ₀ ? A / d

C is the capacitance,? _{R is the} relative dielectric constant of the pressure-sensitive adhesive layer,? ₀ is the permittivity of the space (vacuum), A is the area, and d is the thickness of the pressure-

When the pressure-sensitive adhesive layer according to the present invention is used for layer-to-layer bonding of optical members, it is preferable that the refractive index difference is as small as possible in order to reduce light reflection at the interface between the pressure-sensitive adhesive layer and the optical member. Therefore, the refractive index of the pressure-sensitive adhesive layer is preferably 1.47 to 1.50.

The adhesive force of the pressure-sensitive adhesive layer according to the present invention can be adjusted by adjusting the composition of the pressure-sensitive adhesive in accordance with the object to be adhered to the adherend, but is generally about 0.1 to 20 N / 25 mm.

The pressure-sensitive adhesive film of the present invention can be produced by forming the pressure-sensitive adhesive layer of the present invention on one side of a substrate or a release film.

As the base film used for forming the pressure-sensitive adhesive layer and the release film (separator) for protecting the adhesive surface, a resin film such as a polyester film or the like can be used.

Antistatic treatment with an antifouling treatment with a silicone type, fluorine type releasing agent, a coating agent, fine silica particles, antistatic treatment by application or incorporation of an antistatic agent, etc. can be performed on the surface of the base film opposite to the side where the pressure-

The release film is subjected to releasing treatment by a silicone-based, fluorine-based releasing agent or the like on the side of the pressure-sensitive adhesive layer which is to be brought into contact with the adhesive surface.

The release film, the pressure-sensitive adhesive layer, and the release film may be formed on both surfaces of one pressure-sensitive adhesive layer by aligning the surfaces subjected to the release treatment of the release film. In this case, the release films on both sides are sequentially or simultaneously peeled off to expose the adhesive surface, so that the release film can be bonded to an optical member such as an optical film. Examples of the optical film include a cover glass, an ITO glass, an ITO film, a transparent conductive film by a conductive polymer, a transparent conductive film by a nano silver wire, a transparent conductive film by a carbon nanotube, a polarizing film, a retardation film, And a compensation film.

The adhesive film of the present invention can be used for bonding the touch panel and the display panel. Examples of the display panel include a liquid crystal display, an organic EL, and the like, but are not limited thereto. In addition, it can be used as an electrical insulating material for joining an electric member and an electronic circuit member.

The adhesive film of the present invention can be used for bonding various optical films for a touch panel, various optical films for peripheral members of a liquid crystal display device mainly including a polarizing plate, various optical films using electronic species, and various optical films for organic EL .

Further, the optical film may be an optical film having a pressure-sensitive adhesive layer formed by laminating the pressure-sensitive adhesive layer on at least one surface of these optical films. Specifically, the optical film / pressure-sensitive adhesive layer / optical film, the optical film / pressure-sensitive adhesive layer / release film, the optical film / pressure-sensitive adhesive layer, , "Optical film / pressure-sensitive adhesive layer / optical film / pressure-sensitive adhesive layer / release film", "release film / pressure-sensitive adhesive layer / optical film / pressure-sensitive adhesive layer / release film".

For example, in the case of having a pressure-sensitive adhesive layer protected by a release film such as "optical film / pressure-sensitive adhesive layer / release film", the release film is peeled off to expose the pressure-sensitive adhesive layer like "optical film / pressure- , A configuration similar to that of the "optical film / pressure-sensitive adhesive layer / optical film" in which the pressure-sensitive adhesive layer is used for interlayer bonding can be obtained.

The pressure-sensitive adhesive film of the present invention is a pressure-sensitive adhesive film obtained by thermosetting a pressure-sensitive adhesive layer, and a pressure-sensitive adhesive layer formed by peeling off a release film on one side or both sides of the pressure- And then irradiated with ultraviolet rays, the pressure-sensitive adhesive layer can be crosslinked and used. As a result, an optical member having a pressure-sensitive adhesive layer can be produced.

Example

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

[Example 1]

Nitrogen gas was introduced into a reactor equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen introduction tube to replace the air in the reactor with nitrogen gas. Subsequently, a solvent (ethyl acetate) was added to the reaction apparatus together with 63 g of butyl acrylate, 32 g of methyl acrylate and 5 g of 2-hydroxyethyl acrylate. Thereafter, azobisisobutyronitrile as a polymerization initiator was added dropwise over 2 hours and reacted by heating to obtain an acrylic polymer solution used in Example 1 having a weight average molecular weight of 230,000.

The acrylic polymer solution of Example 1 thus prepared was mixed with 0.026 mole of ethylene glycol dimethacrylate (1G), 0.84 g of a crosslinking agent (A) as an isocyanate crosslinking agent, 0.15 g of an additive (D) as an alkylphenon- Were added and stirred to obtain a pressure-sensitive adhesive composition of Example 1. The pressure-sensitive adhesive composition was coated on a release film made of a polyethylene terephthalate (PET) film coated with a silicone resin so that the thickness after drying became 50 占 퐉, and the solvent was then removed by drying at 90 占 폚. Then, the pressure-sensitive adhesive composition was thermally cured by aging for 7 days under an atmosphere of 40 ° C and 50% RH and then heating and copolymerizing to obtain the pressure-sensitive adhesive film of Example 1 having the structure of release film / pressure-sensitive adhesive layer / release film .

[Examples 2 to 9 and Comparative Examples 1 to 4]

The pressure-sensitive adhesive films of Examples 2 to 9 and Comparative Examples 1 to 4 were obtained in the same manner as the pressure-sensitive adhesive films of Example 1 except that the compositions of monomers and additives were changed as shown in Tables 1, 3 and 4, respectively. The " monomer composition " in Tables 1, 3 and 4 is a breakdown of monomers constituting 100 g of " acrylic adhesive ". The measurement results and test results described in Tables 1 to 4 will be described later.

The contents and names of the components used in Tables 1, 3 and 4 are shown in Table 5.

The blending ratio of the acrylic polymer (polymer A) and the vinyl monomer (monomer B) having a polyalkylene oxide chain in the pressure-sensitive adhesive composition of Examples 1 to 9 was such that a vinyl monomer having a polyalkylene oxide chain To 14.6 moles.

The amount of the monomer used in the production of 100 g of the acrylic pressure-sensitive adhesive (1) is 63 g (0.4915 mol) of BA, 32 g (0.3717 mol) of MA and 5 g (0.0430 mol) of HEA and the total of these monomers is 0.906 mol.

The amount of the monomer used in the production of 100 g of the acrylic pressure-sensitive adhesive (2) was 97 g (0.5264 mol) of 2EHA and 3 g (0.0258 mol) of HEA, and the total amount of these monomers was 0.552 mol.

The amount of the monomer used in the production of 100 g of the acrylic pressure-sensitive adhesive (3) was 95 g (0.5155 mol) of 2 EHA and 5 g (0.0438 mol) of 4HBA, and the total amount of these monomers was 0.559 mol.

≪ Measurement method of relative dielectric constant and measurement result >

In the pressure-sensitive adhesive films of Examples 1 to 9 and Comparative Examples 1 to 4, a release film (PET film coated with silicone resin) was peeled off to expose the pressure-sensitive adhesive layer, and a pressure-sensitive adhesive layer was transferred to one side of the PET film. The relative dielectric constant of the pressure-sensitive adhesive layer was measured using this sample using an LCR meter (manufactured by Hewlett Packard, model: 4284A).

Tables 1, 3 and 4 show measurement results of the relative dielectric constant.

The adhesive films of Examples 1 to 9 had excellent insulation performance due to low dielectric constant. That is, the requirements and problems were overcome in the adhesive films of Examples 1 to 9.

The pressure-sensitive adhesive films of Comparative Examples 1, 2 and 4 did not have excellent insulation performance due to low dielectric constant.

The adhesive film of Comparative Example 3 had excellent insulation performance due to low dielectric constant.

≪ Test method and test result of followability to printing step difference >

(A PET resin film coated with a silicone resin) on the side of the light leaping side was peeled from the pressure-sensitive adhesive film of Example 2, Example 5, and Comparative Example 1 before the irradiation with ultraviolet rays, (Thickness: 100 mu m). For the conjugation, a conjugation apparatus (product name: SE320) manufactured by Climate Products Co., Ltd. was used.

From this sample, a releasing film (silicone resin coated PET film) on the side of the middle bare surface was peeled off and the pressure-sensitive adhesive layer on which the obtained PET film was formed was peeled off from the adherend (screen printing, Formed PET film which had been hard-coated on the opposite side to the printing side) under an atmospheric pressure environment. After the bonding, the appearance of the portion where the pressure-sensitive adhesive layer of each sample was adhered to the printing step of the adherend was visually confirmed, and the bubble was identified (x).

Table 2 shows the test results of the followability to the printing step of the pressure-sensitive adhesive layer before ultraviolet ray irradiation.

In Example 2 and Example 5, the pressure-sensitive adhesive layer could be bonded without introducing air bubbles into the printed steps. In Comparative Example 1, air bubbles entered the printing step portion at the time of coalescence. This is because Comparative Example 1 shows that the crosslinking of the pressure-sensitive adhesive layer progresses at the time before irradiation of ultraviolet rays, and thus the resin is hardened and the followability of the pressure-sensitive adhesive layer before the ultraviolet ray irradiation to the printing step of the adherend is deteriorated.

≪ Test method and test result of shape retention property >

(A PET resin film coated with a silicone resin) on the light-raking side was peeled from the pressure-sensitive adhesive films of Examples 2 and 5 and Comparative Example 1 before the irradiation with ultraviolet rays, (Thickness: 100 mu m) to prepare a sample of the shape retention property (measurement of the displacement amount). A 2 kg hand roller was used for the bonding. A releasing film (silicone resin coated PET film) on the side of the middle bare face was peeled from the sample of the shape retention property test, and the pressure-sensitive adhesive layer on which the obtained PET film was formed was bonded to a glass plate under atmospheric pressure. After the conjugation, each sample was irradiated with ultraviolet rays at 1500 mJ / cm 2 to crosslink the pressure-sensitive adhesive layer. Thereafter, a weight of 1,500 g was attached to one end of the PET film, and a shape-retaining test was conducted at 30 캜. After 12 hours, the amount of displacement of the pressure-sensitive adhesive layer between adherends (PET film and glass plate) was measured with a microscope.

Table 2 shows the results of shape-maintaining test.

In the tests of Example 2 and Example 5, a large " displacement amount " of the pressure-sensitive adhesive layer was hardly observed. On the other hand, in the test of Comparative Example 1, a "displacement amount" of about 6 mm occurred in the pressure-sensitive adhesive layer. For this reason, the pressure-sensitive adhesive film of Comparative Example 1 can not fix the shape of the pressure-sensitive adhesive layer (the positional relationship between adherends) by fixing adherends sufficiently.

≪ Measurement method of storage elastic modulus and measurement result >

Means a storage elastic modulus of a pressure-sensitive adhesive layer at 30 DEG C when a temperature rise rate of 2 DEG C / min and a viscoelasticity measurement in a solid shear mode of 1 Hz are performed.

In the present specification, in order to distinguish the storage modulus at 30 占 폚 of the pressure-sensitive adhesive layer before crosslinking by ultraviolet irradiation and crosslinking by ultraviolet irradiation, it is preferable to use a pressure-sensitive adhesive layer after crosslinking by ultraviolet irradiation , And storage elastic moduli at 30 DEG C are denoted by K1 and K2, respectively.

A dynamic viscoelasticity measuring device (product name: Rheogel-E4000) manufactured by UBM Co., Ltd. was used to measure the storage elastic modulus.

Table 2 shows the measurement results of the storage elastic modulus. The measured value of the storage elastic modulus is represented by a method (m is an arbitrary real number value and n is a positive integer) in which "m x 10 ⁿ " is set to "mE + 0 ⁿ ".

As a result of the measurement of the storage elastic modulus, the storage elastic modulus (K1) of the pressure-sensitive adhesive layer before crosslinking by ultraviolet irradiation at 30 deg. C after thermal curing in Examples 2 and 5 and Comparative Example 1 was K1 = 6.8 × 10 ⁴ Pa, K 1 = 8.2 × 10 ⁴ Pa, and K 1 = 1.9 × 10 ⁵ Pa. Further, according to the results of the followability test for the print step, the visual evaluation results of the followability for the adherend having the stepped print of 15 占 퐉 in step height of Example 2, Example 5, and Comparative Example 1 were (?) And ○) and (×).

From this, it is preferable that K1 is in the range of 1.0 x 10 < ⁴ > to 1.0 x 10 < ⁵ > Pa in the case of the pressure-sensitive adhesive film having the followability to the printing step and excellent shape- More preferably, K1 is in the range of 2.0 × 10 ^{4 to} 1.0 × 10 ⁵ Pa.

If K1 is more than 1.0 x 10 < ⁵ > Pa, the pressure-sensitive adhesive layer is hardly deformed at the time of curing, so there is no traceability to the printing step, and bubbles enter the part of the printing step.

Further, in the results of measurement of the storage elastic modulus in Example 2, Example 5 and Comparative Examples, the storage elastic modulus (K2) in 30 ℃ of the pressure-sensitive adhesive layer after crosslinked by ultraviolet irradiation of 1, K2 = 5.4 × 10 ^5, respectively ^{㎩, K2 = 4.3 × 10 5} ㎩, K2 = it was 2.0 × 10 ⁵ ㎩.

Generally, the higher the K2, the less likely the deformation of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive film, and the adherend can be held for a long period of time at the time of use of the pressure-sensitive adhesive film. When K2 is less than 3.0 x 10 < ⁵ > Pa, the pressure-sensitive adhesive layer tends to be deformed to fix the adherend for a long period of time or to maintain the shape of the pressure-sensitive adhesive layer.

Examples 2 and 5 K2 is 3.0 × 10 or more ⁵ ㎩ (also K2 is 4 × 10 ⁵ ㎩ above), and then cross-linked by irradiation with UV light (the actual use of), the pressure-sensitive adhesive as compared to Comparative Example 1 The layer is in a state of excellent shape retention, in which strain hardly occurs.

Therefore, K2 is preferably 3.0 x 10 < ⁵ > Pa or more, and K2 is more preferably 4 x 10 < ⁵ > Pa or more.

Although the pressure-sensitive adhesive layer according to the present invention uses a pressure-sensitive adhesive composition containing only an acrylic monomer having a general structure, the pressure-sensitive adhesive layer has excellent insulation performance due to low dielectric constant, . Further, since the adhesive film according to the present invention can be used as a film for a touch panel or a film for an electronic paper using a film for electronic use, it has a great industrial value.

Further, since the pressure-sensitive adhesive layer of the pressure-sensitive adhesive film according to the present invention has a low storage elastic modulus before crosslinking by irradiation of ultraviolet rays, adherence of a stepped portion can be achieved without introducing air.

Further, since the pressure-sensitive adhesive layer of the pressure-sensitive adhesive film according to the present invention has a storage modulus equivalent to that of a general pressure-sensitive adhesive film after crosslinking by irradiation of ultraviolet rays, the pressure-sensitive adhesive layer is excellent in shape retention and is unlikely to cause deformation of the pressure-sensitive adhesive layer.

Claims (4)

A pressure-sensitive adhesive composition for constituting a pressure-sensitive adhesive layer for a pressure-sensitive adhesive film used for bonding an optical member,
(Meth) acrylate selected from the group of compounds of copolymerized vinyl monomers having any of the alkyl group, hydroxyl group, carboxyl group, amide group, imide group and aromatic group other than the polyalkylene glycol (meth) (1), based on 100 g of the total of the acrylic polymer obtained by copolymerizing the monomers,
CH ₂ = C (R ¹ ) -COO- (R ² -O) _n -R ³ (1)
(Wherein R ¹ represents a hydrogen atom or a methyl group, R ² represents an alkylene group having 2 to 4 carbon atoms, R ³ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and n represents an integer of 1 to 23 (Meth) acrylate represented by the following general formula (1): ???????? 1 - (CH 2) 2 - (CH 2) A pressure-sensitive adhesive composition comprising a vinyl monomer having an alkylene oxide chain, a photopolymerization initiator, and an isocyanate-based crosslinking agent. The method according to claim 1,
Wherein the total amount of the alkyl (meth) acrylate compound groups in 100 parts by weight of the total amount of all the monomers is 50 parts by weight or more. A pressure-sensitive adhesive film having a pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive composition according to claim 1 or 2 formed on one side of a release film and having the structure of a release film / the pressure-sensitive adhesive layer / release film. A pressure-sensitive adhesive film comprising a pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive composition of claim 1 or 2 formed on one side of a base film.