JP6306679B2 - Radiation curable adhesive, radiation curable adhesive layer, radiation curable adhesive sheet and laminate - Google Patents

Description

  The present invention relates to a radiation curable pressure sensitive adhesive capable of realizing a low dielectric constant, a radiation curable pressure sensitive adhesive layer obtained from the pressure sensitive adhesive, and a radiation curable pressure sensitive adhesive sheet having the pressure sensitive adhesive layer on at least one side of a support. About. Furthermore, this invention relates to the laminated body by which the 1st member and the 2nd member were bonded together through the said adhesive layer. In particular, it is useful when at least one of the first member and the second member is a member having a step on the surface, and the pressure-sensitive adhesive layer of the present invention performs bonding without following a gap. be able to.

  The radiation curable pressure-sensitive adhesive layer or radiation curable pressure-sensitive adhesive sheet of the present invention is suitable for optical applications. For example, the radiation curable pressure-sensitive adhesive layer or radiation curable pressure-sensitive adhesive sheet of the present invention can be used for manufacturing image display devices such as liquid crystal display devices, organic EL (electroluminescence) display devices, PDP (plasma display panels), and electronic paper. In addition, it can be suitably used for manufacturing an input device such as a touch panel such as an optical method, an ultrasonic method, a capacitance method, or a resistance film method. In particular, it is suitably used for a capacitive touch panel.

  The radiation curable pressure-sensitive adhesive sheet of the present invention is useful as a pressure-sensitive adhesive optical member using an optical member as a support. For example, when a transparent conductive film is used as the optical member, the adhesive optical member is used as a transparent conductive film with an adhesive layer. The said transparent conductive film with an adhesive layer is used for the transparent electrode in the said image display apparatus, a touchscreen, etc., after processing is made suitably. In particular, the transparent conductive film with an adhesive layer is suitably used for an electrode substrate of an input device of a capacitive touch panel by patterning a transparent conductive thin film. In addition, the transparent conductive film with the pressure-sensitive adhesive layer is used for antistatic and electromagnetic wave shielding of transparent articles, liquid crystal light control glass, and transparent heaters.

  Moreover, when using an optical film as an optical member, an adhesive optical member is used as an optical film with an adhesive layer. The said optical film with an adhesive layer is used for image display apparatuses, such as a liquid crystal display device and an organic electroluminescence display. As the optical film, a polarizing plate, a phase difference plate, an optical compensation film, a brightness enhancement film, and a film in which these are laminated can be used.

  In recent years, an input device using a combination of an image display device such as a mobile phone or a portable music player and a touch panel has become widespread. In particular, capacitive touch panels are rapidly spreading due to their functionality.

  Currently, many transparent conductive films used for touch panels are known in which a transparent conductive thin film (ITO film) is laminated on a transparent plastic film substrate or glass. A transparent conductive film is laminated | stacked on another member through an adhesive layer. Various types of pressure-sensitive adhesive layers have been proposed (see Patent Documents 1 to 5).

  When the transparent conductive film is used for an electrode substrate of a capacitive touch panel, a film obtained by patterning the transparent conductive thin film is used. A transparent conductive film having such a patterned transparent conductive thin film is used by being laminated with an adhesive layer together with other transparent conductive films and the like. These transparent conductive films are suitably used for multi-touch type input devices that can be operated simultaneously with two or more fingers. In other words, the capacitive touch panel has a mechanism for sensing when the output signal of the position changes when the touch panel is touched with a finger or the like, and the amount of change of the signal exceeds a certain threshold.

JP 2003-238915 A JP 2003-342542 A JP 2004-231723 A JP 2002-363530 A JP 2011-184582 A

  As a member constituting the touch panel, for example, a cover glass or the like that is printed is used, and the surface of the cover glass has a step due to the printing. Therefore, when the member having the step surface and another member are bonded together with the adhesive layer, the adhesive layer absorbs the step and the adhesive layer follows the step so that there is no gap between the members. Is required. As an index of the pressure-sensitive adhesive layer related to the step, the step absorbency (%) represented by the step (μm) and the thickness (μm) of the pressure-sensitive adhesive layer: (step / thickness of the pressure-sensitive adhesive layer) × 100 And satisfying the following ability. About 30% was required as the step absorbability. In general, in order to absorb the step, it is conceivable to lower the elastic modulus. However, a pressure-sensitive adhesive having a low elastic modulus has insufficient reliability such as durability. In order to satisfy the above step absorbability as well as reliability, it has been proposed to use an ultraviolet crosslinkable pressure-sensitive adhesive sheet as described in Patent Document 5. However, in recent years, the pressure-sensitive adhesive layer has been demanded to be thin, and the level difference absorbability requirement has become as high as 60 to 90%. In the pressure-sensitive adhesive sheet described in Patent Document 5, high level difference absorption is achieved. It was hard to satisfy sex.

  Moreover, as mentioned above, the dielectric constant of the member and film which comprise a touch panel is related with the responsiveness of a touch panel, and is an important numerical value. On the other hand, with the spread of touch panels in recent years, higher performance is required for touch panels, and high performance is also required for transparent conductive films and pressure-sensitive adhesive layers that are constituent members, and thinning is one of them. is there. However, there is a problem that the designed capacitance value changes if the pressure-sensitive adhesive layer is simply thinned. In order to reduce the thickness of the pressure-sensitive adhesive layer without changing the value of the capacitance value, it is required to lower the dielectric constant of the pressure-sensitive adhesive layer. In addition, in order to improve visibility, an air layer of glass with printing or a film and an optical film or an air layer above the LCD may be filled with an adhesive layer, but on the other hand, If the dielectric constant is high, malfunction may occur. Also from the viewpoint of preventing such malfunction, the adhesive layer is required to have a low dielectric constant. Furthermore, the response speed and sensitivity of the touch panel are expected to be improved by reducing the dielectric constant of the adhesive layer.

  Then, an object of this invention is to provide the adhesive which can implement | achieve the adhesive layer which satisfies adhesive performance and has high level | step difference absorbency. Furthermore, it aims at providing the said adhesive which can implement | achieve the adhesive layer of satisfying adhesive performance, having a high level | step difference absorptivity, and a low dielectric constant.

  Moreover, an object of this invention is to provide the adhesive layer formed with the said adhesive, and also to provide the adhesive sheet which has the said adhesive layer. Furthermore, it aims at providing the laminated body with which the 1st member and the 2nd member were bonded together with sufficient followable | trackability via the said adhesive layer.

  As a result of intensive studies to solve the above problems, the present inventors have found the following pressure-sensitive adhesive and have completed the present invention.

  That is, the present invention contains a (meth) acrylic polymer obtained by polymerizing a monomer component containing 30 to 90% by weight of an alkyl (meth) acrylate having an alkyl group having 10 to 22 carbon atoms at the ester end, And a radiation-curable pressure-sensitive adhesive having a radically polymerizable functional group having a carbon-carbon double bond. The alkyl (meth) acrylate having an alkyl group having 10 to 22 carbon atoms at the ester terminal is preferably an alkyl group having a branched alkyl group.

  In the radiation curable pressure-sensitive adhesive, the monomer component may further contain 5 to 25% by weight of a cyclic nitrogen-containing monomer.

  In the radiation curable pressure-sensitive adhesive, the monomer component further includes 1 to 20% by weight of at least one functional group-containing monomer selected from a carboxyl group-containing monomer, a hydroxyl group-containing monomer, and a monomer having a cyclic ether group. be able to.

  In the radiation-curable pressure-sensitive adhesive, the monomer component is further selected from alkyl (meth) acrylate having an alkyl group having 1 to 9 carbon atoms at the ester end and alkyl (meth) acrylate having a cyclic alkyl group at the ester end. Any at least one of them can be contained in an amount of 0.5% by weight or more.

  As one aspect, the radiation-curable pressure-sensitive adhesive contains, in addition to the (meth) acrylic polymer, a compound having at least one radical polymerizable functional group having a carbon-carbon double bond in the molecule. Things can be used. In addition, as the radiation curable pressure-sensitive adhesive, as one embodiment, the (meth) acrylic polymer is a (meth) acrylic polymer having a radical polymerizable functional group having a carbon-carbon double bond. Can be used.

  Furthermore, the radiation curable pressure-sensitive adhesive preferably contains 0.005 to 5 parts by weight of a crosslinking agent with respect to 100 parts by weight of the (meth) acrylic polymer.

  The present invention also relates to a radiation curable pressure-sensitive adhesive layer obtained from any of the radiation curable pressure-sensitive adhesives described above.

The radiation curable pressure-sensitive adhesive layer is
Before radiation curing, the shear storage modulus at 70 ° C. is 2.0 × 10 ^{3 to} 4.0 × 10 ⁴ Pa, the gel fraction is 0 to 60% by weight,
After radiation curing, the shear storage modulus at 70 ° C. is preferably 1.5 × 10 ⁴ to 1.5 × 10 ⁵ Pa, and the gel fraction is preferably 40 to 95% by weight.

  The radiation curable pressure-sensitive adhesive layer preferably has a relative dielectric constant of 3.7 or less at a frequency of 100 kHz.

  The present invention also relates to a radiation curable pressure-sensitive adhesive sheet, wherein the radiation curable pressure-sensitive adhesive layer described above is formed on at least one side of a support.

  The radiation curable adhesive sheet can be used as an adhesive optical member using an optical member as a support.

  Moreover, this invention relates to the laminated body characterized by the 1st member and the 2nd member being bonded together through the radiation-curable adhesive layer in any one of the said.

The laminate is a member in which at least one of the first member and the second member has a step on the surface,
It is also suitable when the step (μm) and the thickness (μm) of the pressure-sensitive adhesive layer satisfy (step / thickness of the pressure-sensitive adhesive layer) ≦ 0.9.

  The laminate can be suitably applied when at least one of the first member and the second member is an optical member.

  The (meth) acrylic polymer in the radiation curable pressure-sensitive adhesive of the present invention was obtained by polymerizing a monomer component containing a predetermined amount of an alkyl (meth) acrylate having a long-chain alkyl group having 10 to 22 carbon atoms. Is. Since the radiation-curable pressure-sensitive adhesive layer formed from the radiation-curable pressure-sensitive adhesive of the present invention has the long-chain alkyl group before radiation curing, it can follow even a surface having a step. The step can be absorbed by the pressure-sensitive adhesive layer without any gap, and high step absorbability can be satisfied. In addition, since the radiation curable pressure-sensitive adhesive layer of the present invention has a high level of absorbency, it is not necessary to increase the thickness of the pressure-sensitive adhesive layer even when the level difference is large, and the pressure-sensitive adhesive layer is also suitable from the viewpoint of reducing the thickness. On the other hand, after radiation curing, the adhesive properties can be satisfied by the cured pressure-sensitive adhesive layer. Thus, according to the radiation curable pressure-sensitive adhesive of the present invention, it is possible to obtain a radiation curable pressure-sensitive adhesive layer that satisfies the adhesive performance and has high step absorbability.

  Further, according to the radiation curable pressure-sensitive adhesive of the present invention, a low dielectric constant pressure-sensitive adhesive layer can be realized by the action of the long-chain alkyl group. Further, as described above, even when the air layer is filled with an adhesive layer, the radiation curable adhesive layer has a low dielectric constant, so that malfunction can be prevented.

  In order to lower the dielectric constant, it is considered that the molecular dipole moment is reduced and the molar volume is increased from the Clausius-Mossotti equation. Since the alkyl (meth) acrylate related to the main monomer unit constituting the (meth) acrylic polymer that is the main component in the radiation curable pressure-sensitive adhesive of the present invention has a long-chain alkyl group, the dielectric constant decreases. Conceivable. In this way, the radiation curable pressure-sensitive adhesive layer having a balance between the two so that the molar volume is increased and the dipole moment is decreased is an alkyl group having 10 to 22 carbon atoms at the end of the ester group. This is considered to be achieved when the alkyl (meth) acrylate is used.

  For example, the radiation curable pressure-sensitive adhesive layer of the present invention satisfies the low dielectric constant of a dielectric constant at 100 kHz of 3.7 or less, thereby reducing the thickness of the radiation curable pressure-sensitive adhesive layer of the present invention and increasing the capacitance. Even when it is used for an adhesive layer applied to a transparent conductive film used for a touch panel of the type, it can be applied without changing the numerical value of the capacitance value designed by the touch panel of the capacitive type.

  Furthermore, in the case where a cyclic nitrogen-containing monomer is used as the monomer unit constituting the (meth) acrylic polymer that is the main component in the radiation-curable pressure-sensitive adhesive of the present invention, the cohesiveness in the cyclic structure having a nitrogen atom is Humidity resistance can be satisfied by the hydrophilic action. By satisfying the humidification reliability, white turbidity of the pressure-sensitive adhesive layer can be suppressed even when a laminate obtained by laminating a transparent conductive film or glass via the pressure-sensitive adhesive layer is exposed to humidification conditions. .

It is a figure which shows an example of the capacitive touch panel in which the radiation-curable adhesive layer or radiation-curable adhesive sheet of this invention is used. (A) It is the schematic which shows the measuring method of a workability test. (B) It is a figure which shows the distance-time curve in a workability test.

  The radiation curable pressure-sensitive adhesive of the present invention is obtained by polymerizing a monomer component containing 30 to 90% by weight of an alkyl (meth) acrylate having an alkyl group having 10 to 22 carbon atoms at an ester terminal. What has a radically polymerizable functional group which contains a polymer and has a carbon-carbon double bond is used.

  The radical polymerizable functional group having a carbon-carbon double bond contained in the radiation curable pressure-sensitive adhesive is a functional group having radiation curable properties, such as an unsaturated group such as a (meth) acryloyl group or a vinyl group. Examples thereof include a functional group having a double bond. The radically polymerizable functional group having a carbon-carbon double bond has at least one radically polymerizable functional group having a carbon-carbon double bond in the molecule in the (meth) acrylic polymer that is a base polymer. By compounding the compound, the radiation curable pressure-sensitive adhesive may have a radical polymerizable functional group having a carbon-carbon double bond, and the carbon-carbon as the (meth) acrylic polymer as the base polymer. By using a (meth) acrylic polymer having a radical polymerizable functional group having a double bond, the radiation curable pressure-sensitive adhesive may have a radical polymerizable functional group having a carbon-carbon double bond. Moreover, the radiation-curable pressure-sensitive adhesive may contain a radical polymerizable functional group having a carbon-carbon double bond by both means.

  First, the radiation-curable pressure-sensitive adhesive (1) in which the (meth) acrylic polymer is blended with a compound having at least one radical polymerizable functional group having a carbon-carbon double bond in the molecule will be described.

  The (meth) acrylic polymer is obtained by polymerizing a monomer component containing 30 to 90% by weight of an alkyl (meth) acrylate having an alkyl group having 10 to 22 carbon atoms at the ester terminal. Alkyl (meth) acrylate refers to alkyl acrylate and / or alkyl methacrylate, and (meth) in the present invention has the same meaning.

  The glass transition temperature (Tg) at the time of forming a homopolymer according to the alkyl (meth) acrylate having an alkyl group having 10 to 22 carbon atoms at the ester end is preferably -80 to 0 ° C. It is preferably −70 to −10 ° C., more preferably −60 to −10 ° C. If the Tg at the time of forming the homopolymer is less than -80 ° C, the elastic modulus of the pressure-sensitive adhesive at room temperature may be excessively decreased, and if it exceeds 0 ° C, the adhesive force may be decreased. . The Tg of the homopolymer is a value measured by temperature modulation DSC. In addition, the alkyl group preferably has 13 or more carbon atoms from the viewpoint of satisfying step absorbency, low dielectric constant, and appropriate elastic modulus. The alkyl group preferably has 14 to 22 carbon atoms, and more preferably 16 to 22 carbon atoms. In addition, even if the Tg of the homopolymer related to the alkyl (meth) acrylate is -80 to 0 ° C., if the carbon number is 9 or less, the step absorbability of the pressure-sensitive adhesive layer and the effect of reducing the dielectric constant are not large. .

The Tg of the homopolymer is a value measured by the following method. About 1 to 2 mg of a test sample is weighed in an aluminum open cell, and a temperature-modulated DSC (trade name “Q-2000”, manufactured by TA Instruments Inc.) is used in a nitrogen atmosphere of 50 ml / min. Homopolymer reversing heat flow at a heating rate of 5 ° C./min
(Specific heat component) Get behavior. Referring to JIS-K-7121, the low temperature side baseline of the obtained Reversing Heat Flow and the straight line that is equidistant from the straight line extending the high temperature side base line, and the stepwise change of the glass transition The temperature at the point where the partial curve intersects is the glass transition temperature (Tg) when the homopolymer is used.

  The alkyl group having 10 to 22 carbon atoms in the alkyl (meth) acrylate can be either linear or branched, but from the viewpoint of the step absorbability of the pressure-sensitive adhesive layer and the effect of reducing the dielectric constant. Is preferably a branched alkyl group rather than a linear alkyl group. It is considered that the long-chain alkyl group of the alkyl (meth) acrylate has a molar volume that is increased due to the branching of the alkyl group, the dipole moment is decreased, and a pressure-sensitive adhesive layer having a balance between the two is obtained. Moreover, since the alkyl group has a branch, the molecular weight between the entanglement points of the polymer is increased, and the storage elastic modulus at high temperature is decreased.

  Examples of the alkyl (meth) acrylate having a linear alkyl group having 10 to 22 carbon atoms at the ester terminal include decyl acrylate (carbon number 10), undecyl acrylate (carbon number 11), dodecyl acrylate (lauryl acrylate) (carbon). 12), tridecyl acrylate (13 carbon atoms), tetradecyl acrylate (14 carbon atoms), pentadecyl acrylate (15 carbon atoms), hexadecyl acrylate (16 carbon atoms), heptadecyl acrylate (17 carbon atoms), octadecyl Acrylate (18 carbon atoms), nonadecyl acrylate (19 carbon atoms), eicosyl acrylate (20 carbon atoms), henecosyl acrylate (21 carbon atoms), docosyl acrylate (22 carbon atoms), and the above exemplified methacrylate series Example of monomer It can be. These can be used alone or in combination of two or more. Among these, dodecyl acrylate and dodecyl methacrylate (lauryl methacrylate) (12 carbon atoms) are preferable.

  Examples of the alkyl (meth) acrylate having an alkyl group having a branched chain having 10 to 22 carbon atoms at the ester terminal include, for example, isodecyl acrylate (carbon number, homopolymer Tg (hereinafter simply referred to as Tg) = − 60. ° C), isodecyl methacrylate (carbon number 10, Tg = −41 ° C.), isomistyryl acrylate (carbon number 14, Tg = −56 ° C.), isostearyl acrylate (carbon number 18, Tg = −18 ° C.), 2- Examples include propyl heptyl acrylate, isoundecyl acrylate, isododecyl acrylate, isotridecyl acrylate, isopentadecyl acrylate, isohexadecyl acrylate, isoheptadecyl acrylate, and methacrylate monomers of the above-mentioned acrylate monomers. These can be used alone or in combination of two or more.

In addition, among the alkyl groups having 10 to 22 carbon atoms, those having a t-butyl group, in particular, have a pressure-sensitive adhesive layer having a balance between the two because the molar volume increases and the dipole moment decreases. It is preferable at the point considered to be obtained. Examples of the alkyl (meth) acrylate having a t-butyl group and having a branched alkyl group having 10 to 22 carbon atoms include isostearyl acrylate represented by the following formula.

  Moreover, as an alkyl (meth) acrylate having an alkyl group having 10 to 22 carbon atoms at the ester terminal, alkyl methacrylate is more preferable than alkyl acrylate because of an increase in molar volume and a decrease in dipole moment. This is preferable from the viewpoint of the step absorbability and the effect of reducing the dielectric constant. In the case of the alkyl methacrylate, even when the long-chain alkyl group is a linear alkyl group, the molar volume is increased, the dipole moment is decreased, and an adhesive layer having a balance between the two is obtained.

  The alkyl (meth) acrylate having an alkyl group having 10 to 22 carbon atoms at the ester terminal is 30 to 90% by weight, preferably 30 to 80%, based on all monomer components forming the (meth) acrylic polymer. % By weight, more preferably 30 to 70% by weight, still more preferably 35 to 60% by weight, particularly preferably 40 to 60% by weight. The use of 30% by weight or more is preferable in terms of step absorbency and low dielectric constant, and the use of 90% by weight or less is preferable in terms of maintaining adhesive strength.

  A cyclic nitrogen-containing monomer can be used as the monomer component. As the cyclic nitrogen-containing monomer, those having a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group and having a cyclic nitrogen structure can be used without particular limitation. The cyclic nitrogen structure preferably has a nitrogen atom in the cyclic structure. Examples of cyclic nitrogen-containing monomers include lactam vinyl monomers such as N-vinylpyrrolidone, N-vinyl-ε-caprolactam, and methylvinylpyrrolidone; vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinyl Examples thereof include vinyl monomers having a nitrogen-containing heterocyclic ring such as imidazole, vinyl oxazole and vinyl morpholine. Moreover, the (meth) acryl monomer containing heterocyclic rings, such as a morpholine ring, a piperidine ring, a pyrrolidine ring, a piperazine ring, is mentioned. Specific examples include N-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, N-acryloylpyrrolidine and the like. Among the cyclic nitrogen-containing monomers, lactam vinyl monomers are preferable from the viewpoint of dielectric constant and cohesiveness.

  The cyclic nitrogen-containing monomer is preferably 5 to 25% by weight based on all monomer components forming the (meth) acrylic polymer. More preferably, it is 5-20 weight%, More preferably, it is 5-15 weight%. When it is 5% by weight or more, it is preferable from the viewpoint of humidification reliability, and when it is 25% by weight or less, it is preferable from the viewpoint of improvement in adhesion and step absorbability.

  The monomer component forming the (meth) acrylic polymer of the present invention further includes at least one functional group-containing monomer selected from a carboxyl group-containing monomer, a hydroxyl group-containing monomer, and a monomer having a cyclic ether group. Can do.

  As the carboxyl group-containing monomer, a monomer having a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group and having a carboxyl group can be used without particular limitation. Examples of the carboxyl group-containing monomer include (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid. Can be used alone or in combination. These anhydrides can be used for itaconic acid and maleic acid. Among these, acrylic acid and methacrylic acid are preferable, and acrylic acid is particularly preferable. In addition, a carboxyl group-containing monomer can be arbitrarily used for the monomer component used for manufacture of the (meth) acrylic-type polymer of this invention, On the other hand, it is not necessary to use a carboxyl group-containing monomer. A pressure-sensitive adhesive containing a (meth) acrylic polymer obtained from a monomer component not containing a carboxyl group-containing monomer can form a pressure-sensitive adhesive layer in which metal corrosion caused by a carboxyl group is reduced.

  As the hydroxyl group-containing monomer, a monomer having a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group and having a hydroxyl group can be used without particular limitation. Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl ( Hydroxyalkyl (meth) acrylates such as (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate and the like; And hydroxyalkylcycloalkane (meth) acrylates such as 4-hydroxymethylcyclohexyl) methyl (meth) acrylate. Other examples include hydroxyethyl (meth) acrylamide, allyl alcohol, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether, and the like. These can be used alone or in combination. Of these, hydroxyalkyl (meth) acrylate is preferred.

  As the monomer having a cyclic ether group, a monomer having a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group and a cyclic ether group such as an epoxy group or an oxetane group. It can be used without particular limitation. Examples of the epoxy group-containing monomer include glycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate glycidyl ether, and the like. Examples of the oxetane group-containing monomer include 3-oxetanylmethyl (meth) acrylate, 3-methyl-oxetanylmethyl (meth) acrylate, 3-ethyl-oxetanylmethyl (meth) acrylate, and 3-butyl-oxetanylmethyl (meth) acrylate. , 3-hexyl-oxetanylmethyl (meth) acrylate, and the like. These can be used alone or in combination.

  It is preferable that the said functional group containing monomer is 1 to 20 weight% with respect to all the monomer components which form a (meth) acrylic-type polymer. It is preferably 1% by weight or more, more preferably 4% by weight or more from the viewpoint of enhancing the adhesive force and cohesive force. On the other hand, if the amount of the functional group-containing monomer is too large, the pressure-sensitive adhesive layer becomes hard and the adhesive strength may decrease, and the viscosity of the pressure-sensitive adhesive may become too high or gel. The functional group-containing monomer is preferably 20% by weight or less, more preferably 15% by weight or less, and further 12% by weight or less based on the total monomer components forming the (meth) acrylic polymer. preferable.

The monomer component forming the (meth) acrylic polymer of the present invention can contain a copolymerization monomer other than the cyclic nitrogen-containing monomer and the functional group-containing monomer. Examples of other copolymerizable monomers include CH ₂ ═C (R ¹ ) COOR ² (wherein R ¹ is hydrogen or a methyl group, R ² is an unsubstituted alkyl group having 1 to 9 carbon atoms or a substituted alkyl group). An alkyl (meth) acrylate represented by the following formula:

Here, the unsubstituted alkyl group having 1 to 9 carbon atoms or the substituted alkyl group as R ² represents a linear or branched alkyl group or a cyclic cycloalkyl group. Specific examples of R ² include a branched alkyl group having 3 to 9 carbon atoms and a cyclic alkyl group. In the case of a substituted alkyl group, the substituent is preferably an aryl group having 3 to 8 carbon atoms or an aryloxy group having 3 to 8 carbon atoms. The aryl group is not limited, but is preferably a phenyl group. As the alkyl (meth) acrylate, alkyl methacrylate is preferable to alkyl acrylate in terms of lowering the dielectric constant due to an increase in molar volume and a decrease in dipole moment.

Examples of such a monomer represented by CH ₂ ═C (R ¹ ) COOR ² include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, and s-butyl (meth) acrylate. , T-butyl (meth) acrylate, isobutyl (meth) acrylate, n-pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, isoamyl (meth) acrylate, 2- Ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, cyclohex Sil (meth) acrylate, 3,3,5-trimethylcyclohexyl (meth) acrylate, isobornyl (meth) acrylate. These can be used alone or in combination.

In the present invention, the (meth) acrylate represented by CH ₂ ═C (R ¹ ) COOR ² can be used at 70% by weight or less based on the total monomer components forming the (meth) acrylic polymer. 65% by weight or less is preferable. The (meth) acrylate represented by CH ₂ ═C (R ¹ ) COOR ² is preferably used in an amount of 5% by weight or more, and more preferably 10% by weight or more from the viewpoint of maintaining adhesive strength.

  Other copolymer monomers include vinyl acetate, vinyl propionate, styrene, α-methylstyrene; (meth) acrylic acid polyethylene glycol, (meth) acrylic acid polypropylene glycol, (meth) acrylic acid methoxyethylene glycol, (meth) Glycol acrylic ester monomers such as methoxypolypropylene glycol acrylate; Acrylic ester monomers such as tetrahydrofurfuryl (meth) acrylate, fluorine (meth) acrylate, silicone (meth) acrylate and 2-methoxyethyl acrylate; Monomers, amino group-containing monomers, imide group-containing monomers, N-acryloylmorpholine, vinyl ether monomers and the like can also be used. Moreover, as a copolymerization monomer, the monomer which has cyclic structures, such as terpene (meth) acrylate and dicyclopentanyl (meth) acrylate, can be used.

  Furthermore, the silane type monomer containing a silicon atom, etc. are mentioned. Examples of the silane monomer include 3-acryloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 4-vinylbutyltrimethoxysilane, 4-vinylbutyltriethoxysilane, and 8-vinyloctyltrimethoxysilane. , 8-vinyloctyltriethoxysilane, 10-methacryloyloxydecyltrimethoxysilane, 10-acryloyloxydecyltrimethoxysilane, 10-methacryloyloxydecyltriethoxysilane, 10-acryloyloxydecyltriethoxysilane, and the like.

  The monomer component that forms the (meth) acrylic polymer of the present invention contains a polyfunctional monomer as necessary in order to adjust the cohesive strength of the pressure-sensitive adhesive, in addition to the monofunctional monomer exemplified above. be able to.

  The polyfunctional monomer is a monomer having at least two polymerizable functional groups having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group, such as (poly) ethylene glycol di (meth) acrylate, (Poly) propylene glycol di (meth) acrylate, (poly) tetramethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol Stall tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,2-ethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,12-dodecanediol di (meth) Polyhydric alcohols such as acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethane tri (meth) acrylate, ethoxylated bisphenol A di (meth) acrylate, ethoxylated pentaerythritol tetra (meth) acrylate, and (meth) acrylic An ester compound with an acid; allyl (meth) acrylate, vinyl (meth) acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate, butyl di (meth) acrylate, hexyl di (meth) acrylate, and the like. Among these, trimethylolpropane tri (meth) acrylate, hexanediol di (meth) acrylate, and dipentaerythritol hexa (meth) acrylate can be preferably used. A polyfunctional monomer can be used individually by 1 type or in combination of 2 or more types.

  The amount of the polyfunctional monomer used varies depending on the molecular weight, the number of functional groups, and the like, but it can be used at 3% by weight or less with respect to all monomer components forming the (meth) acrylic polymer, and 2% by weight or less. More preferably, 1% by weight or less is preferable. When the usage-amount of a polyfunctional monomer exceeds 3 weight%, the cohesion force of an adhesive will become high too much, for example, and adhesive force may fall.

  In addition, the monomer component used in the present invention may include components other than those described above. In this case, the monomer component is 10% by weight or less based on the total monomer components forming the (meth) acrylic polymer. Is preferred.

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

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

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

  Examples of the thermal polymerization initiator used for solution polymerization include 2,2′-azobisisobutyronitrile, 2,2′-azobis-2-methylbutyronitrile, 2,2′-azobis (2 -Methylpropionic acid) dimethyl, 4,4'-azobis-4-cyanovaleric acid, azobisisovaleronitrile, 2,2'-azobis (2-amidinopropane) dihydrochloride, 2,2'-azobis [2- (5-Methyl-2-imidazolin-2-yl) propane] dihydrochloride, 2,2′-azobis (2-methylpropionamidine) disulfate, 2,2′-azobis (N, N′-dimethyleneisobutyl) Amidine), 2,2′-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] hydrate (manufactured by Wako Pure Chemical Industries, Ltd., VA-) 57) and the like; persulfates such as potassium persulfate and ammonium persulfate, di (2-ethylhexyl) peroxydicarbonate, di (4-t-butylcyclohexyl) peroxydicarbonate, di-sec- Butyl peroxydicarbonate, t-butyl peroxyneodecanoate, t-hexyl peroxypivalate, t-butyl peroxypivalate, dilauroyl peroxide, di-n-octanoyl peroxide, 1,1, 3,3-tetramethylbutylperoxy-2-ethylhexanoate, di (4-methylbenzoyl) peroxide, dibenzoyl peroxide, t-butylperoxyisobutyrate, 1,1-di (t-hexylper Oxy) cyclohexane, t-butyl hydroperoxide, hydrogen peroxide Peroxide initiators, combinations of persulfates and sodium bisulfite, redox initiators combining peroxides and reducing agents such as combinations of peroxides and sodium ascorbate, etc. However, it is not limited to these.

  The polymerization initiator may be used alone, or may be used in combination of two or more, but the total content is 0.005 to 100 parts by weight of the total amount of monomer components. The amount is preferably about 1 part by weight, and more preferably about 0.02 to 0.5 part by weight.

  In order to produce the (meth) acrylic polymer having the weight average molecular weight using, for example, 2,2′-azobisisobutyronitrile as the polymerization initiator, the amount of the polymerization initiator used is a monomer. The amount is preferably about 0.06 to 0.2 part by weight, more preferably about 0.08 to 0.175 part by weight with respect to 100 parts by weight of the total amount of the components.

  Examples of the chain transfer agent include lauryl mercaptan, glycidyl mercaptan, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid, methyl thioglycolate, ethyl thioglycolate, 2-ethylhexyl thioglycolate, α-thioglycerol, 2, 3 -Dimercapto-1-propanol etc. are mentioned. The chain transfer agent may be used alone or in combination of two or more, but the total content is 0.1 parts by weight with respect to 100 parts by weight of the total amount of monomer components. Less than or equal to

  Examples of the emulsifier used for emulsion polymerization include anionic emulsifiers such as sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzenesulfonate, ammonium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkyl phenyl ether sulfate, and polyoxy Nonionic emulsifiers such as ethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, and polyoxyethylene-polyoxypropylene block polymer are exemplified. These emulsifiers may be used alone or in combination of two or more.

  Furthermore, as a reactive emulsifier, as an emulsifier into which a radical polymerizable functional group having a carbon-carbon double bond such as a propenyl group or an allyl ether group is introduced, specifically, for example, Aqualon HS-10, HS-20, etc. , KH-10, BC-05, BC-10, BC-20 (all of which are manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Adeka Soap SE10N (manufactured by ADEKA), and the like. Reactive emulsifiers are preferable because they are incorporated into the polymer chain after polymerization and thus have improved water resistance. The amount of the emulsifier used is preferably 5 parts by weight or less, more preferably 0.3 to 5 parts by weight with respect to 100 parts by weight of the total amount of the monomer components, and 0.5 to 1 in view of polymerization stability and mechanical stability. Part by weight is particularly preferred.

  The weight average molecular weight of the (meth) acrylic polymer of the present invention is preferably 400,000 to 2,500,000, more preferably 500,000 to 2,200,000. By making the weight average molecular weight larger than 400,000, it is possible to satisfy the durability of the pressure-sensitive adhesive layer, or to suppress the occurrence of adhesive residue due to the reduced cohesive force of the pressure-sensitive adhesive layer. On the other hand, when the weight average molecular weight is larger than 2.5 million, the bonding property and the adhesive strength tend to be lowered. Furthermore, in the solution system, the viscosity becomes too high, and coating may be difficult. The weight average molecular weight is a value measured by GPC (gel permeation chromatography) and calculated in terms of polystyrene.

<Measurement of weight average molecular weight>
The weight average molecular weight of the obtained (meth) acrylic polymer was measured by GPC (gel permeation chromatography). The sample used was a filtrate obtained by dissolving the sample in tetrahydrofuran to make a 0.1 wt% solution, which was allowed to stand overnight, and then filtered through a 0.45 μm membrane filter. Analytical apparatus: manufactured by Tosoh Corporation, HLC-8120GPC Column: TSK gel GMH-H (S) Column size: 7.8 mmφ × 30 cm Eluent: tetrahydrofuran (concentration 0.1% by weight) Flow rate: 0 .5ml / min Detector: Differential refractometer (RI) Column temperature: 40 ° C
・ Injection volume: 100 μl
・ Eluent: Tetrahydrofuran ・ Detector: Differential refractometer ・ Standard sample: Polystyrene

  In the radiation curable pressure-sensitive adhesive (1), the compound having at least one radical polymerizable functional group having a carbon-carbon double bond, which is blended in the (meth) acrylic polymer, is a radiation curable compound. Examples thereof include monomer components and oligomer components having a radically polymerizable functional group having a carbon-carbon double bond.

  Examples of the compound having one radical polymerizable functional group in the molecule include the various monofunctional monomers exemplified above for the (meth) acrylic polymer. Examples of the compound having at least two radical polymerizable functional groups in the molecule include the compounds exemplified as the polyfunctional monomer. Examples of the radiation curable oligomer component include various oligomers such as urethane, polyether, polyester, polycarbonate, and polybutadiene. As the monomer component or oligomer component having a radical polymerizable functional group having a radiation curable carbon-carbon double bond, those having a molecular weight in the range of about 100 to 30000 are suitable. As the radiation-curable monomer component or oligomer component, a compound having at least two radical polymerizable functional groups having a carbon-carbon double bond in the molecule is preferable from the viewpoint of step absorbability.

  The compounding amount of the compound having at least one radical polymerizable functional group having a carbon-carbon double bond in the molecule is generally 1 to 50 with respect to 100 parts by weight of the (meth) acrylic polymer. The amount is preferably about parts by weight, more preferably 5 to 40 parts by weight, and further preferably 7 to 30 parts by weight.

  Next, a radiation curable pressure-sensitive adhesive (2) using a (meth) acrylic polymer having a radical polymerizable functional group having a carbon-carbon double bond as the (meth) acrylic polymer will be described. The radically polymerizable functional group having a carbon-carbon double bond can be contained in the side chain, main chain, or main chain terminal of the (meth) acrylic polymer. The radiation curable pressure-sensitive adhesive (2) does not need to contain a radiation curable monomer component or oligomer component, which is a low molecular component, in addition to the (meth) acrylic polymer, or does not contain many, so In particular, it is possible to form a pressure-sensitive adhesive layer having a stable layer structure without moving low molecular components or the like through the pressure-sensitive adhesive layer.

  The (meth) acrylic polymer having a radically polymerizable functional group having a carbon-carbon double bond is obtained by using the (meth) acrylic polymer described in the radiation curable pressure-sensitive adhesive (1) as a basic skeleton. ) A polymer obtained by introducing a radical polymerizable functional group having a carbon-carbon double bond into an acrylic polymer. The method for introducing the radically polymerizable functional group having a carbon-carbon double bond is not particularly limited, and various methods can be adopted. However, the radically polymerizable functional group having a carbon-carbon double bond is changed to a (meth) acrylic polymer. The molecular design is easy to introduce into the side chain. For example, a radical having a functional group (b) and a carbon-carbon double bond capable of reacting with the functional group (a) after previously copolymerizing a monomer having the functional group (a) with a (meth) acrylic polymer. Examples thereof include a method of subjecting a compound having a polymerizable functional group to a condensation or addition reaction while maintaining the radiation curability of the radically polymerizable functional group having a carbon-carbon double bond.

  Examples of combinations of the functional groups (a) and (b) include a carboxyl group and an epoxy group, a carboxyl group and an aziridyl group, and a hydroxyl group and an isocyanate group. Among these combinations of functional groups, a combination of a hydroxyl group and an isocyanate group is preferable. If the combination of these functional groups (a) and (b) is a combination that produces a (meth) acrylic polymer having a radical polymerizable functional group having the carbon-carbon double bond, the functional group ( a) and (b) may be on either side of the (meth) acrylic polymer and the compound. For example, when a hydroxyl group and an isocyanate group are combined, the (meth) acrylic polymer has a hydroxyl group. It is preferable that the compound has an isocyanate group. In this case, examples of the isocyanate compound having a radically polymerizable functional group having a carbon-carbon double bond include methacryloyl isocyanate, 2-methacryloyloxyethyl isocyanate, 2-acryloyloxyethyl isocyanate, m-isopropenyl-α, α. -Dimethylbenzyl isocyanate and the like. Moreover, as an acrylic polymer, what copolymerized the hydroxyl group containing monomer etc. of the said illustration is used. In the (meth) acrylic polymer having a radical polymerizable functional group having a carbon-carbon double bond, the ratio (introduction amount) of the radical polymerizable functional group is, for example, before introducing the radical polymerizable functional group ( The ratio of the compound having a radical polymerizable functional group to 100 parts by weight of the (meth) acrylic polymer is preferably in the range of 0.1 to 10 parts by weight.

  As the radiation curable pressure-sensitive adhesive (2), a (meth) acrylic polymer having a radical polymerizable functional group having a carbon-carbon double bond can be used alone. A compound having at least one radically polymerizable functional group having a carbon-carbon double bond in the molecule may be blended. The compound having at least one radical polymerizable functional group having a carbon-carbon double bond in the molecule is usually added to 100 parts by weight of a (meth) acrylic polymer having a radical polymerizable functional group having a carbon-carbon double bond. It is preferable to use in the range of 0 to 30 parts by weight, preferably 0 to 20 parts by weight, more preferably 0 to 10 parts by weight.

  A pressure-sensitive adhesive layer is formed from the radiation-curable pressure-sensitive adhesive of the present invention, and the pressure-sensitive adhesive layer can be cured by irradiation with an electron beam, UV, or the like after being bonded to an adherend. When the radiation polymerization is performed with an electron beam, it is not particularly necessary that the radiation curable pressure-sensitive adhesive contains a photopolymerization initiator, but when the radiation polymerization is performed with UV polymerization, the photopolymerization is started. An agent can be included. A photoinitiator can be used individually by 1 type or in combination of 2 or more types.

  The photopolymerization initiator is not particularly limited, but is not particularly limited as long as it initiates photopolymerization, and a commonly used photopolymerization initiator can be used. For example, benzoin ether photopolymerization initiator, acetophenone photopolymerization initiator, α-ketol photopolymerization initiator, aromatic sulfonyl chloride photopolymerization initiator, photoactive oxime photopolymerization initiator, benzoin photopolymerization initiator Agents, benzyl photopolymerization initiators, benzophenone photopolymerization initiators, ketal photopolymerization initiators, thioxanthone photopolymerization initiators, acylphosphine oxide photopolymerization initiators, and the like can be used.

  Specifically, examples of the benzoin ether photopolymerization initiator include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethane- 1-one [trade name: Irgacure 651, manufactured by BASF Corporation], anisole methyl ether and the like can be mentioned. Examples of the acetophenone photopolymerization initiator include 1-hydroxycyclohexyl phenyl ketone [trade name: Irgacure 184, manufactured by BASF], 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, 1- [4- ( 2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one [trade name: Irgacure 2959, manufactured by BASF Corp.], 2-hydroxy-2-methyl-1-phenyl-propane- 1-one [trade name: Darocur 1173, manufactured by BASF Corporation], methoxyacetophenone, and the like can be given. Examples of the α-ketol photopolymerization initiator include 2-methyl-2-hydroxypropiophenone, 1- [4- (2-hydroxyethyl) -phenyl] -2-hydroxy-2-methylpropane-1- ON etc. are mentioned. Examples of the aromatic sulfonyl chloride photopolymerization initiator include 2-naphthalene sulfonyl chloride. Examples of the photoactive oxime photopolymerization initiator include 1-phenyl-1,1-propanedione-2- (o-ethoxycarbonyl) -oxime.

  The benzoin photopolymerization initiator includes, for example, benzoin. Examples of the benzyl photopolymerization initiator include benzyl. Examples of the benzophenone photopolymerization initiator include benzophenone, benzoylbenzoic acid, 3,3′-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, α-hydroxycyclohexyl phenyl ketone, and the like. Examples of the ketal photopolymerization initiator include benzyl dimethyl ketal. Examples of the thioxanthone photopolymerization initiator include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, dodecylthioxanthone and the like are included.

Examples of the acylphosphine photopolymerization initiator include bis (2,6-dimethoxybenzoyl) phenylphosphine oxide, bis (2,6-dimethoxybenzoyl) (2,4,4-trimethylpentyl) phosphine oxide, bis ( 2,6-dimethoxybenzoyl) -n-butylphosphine oxide, bis (2,6-dimethoxybenzoyl)-(2-methylpropan-1-yl) phosphine oxide, bis (2,6-dimethoxybenzoyl)-(1- Methylpropan-1-yl) phosphine oxide, bis (2,6-dimethoxybenzoyl) -t-butylphosphine oxide, bis (2,6-dimethoxybenzoyl) cyclohexylphosphine oxide, bis (2,6-dimethoxybenzoyl) octylphosphine Oxides, bis (2-mes Xylbenzoyl) (2-methylpropan-1-yl) phosphine oxide, bis (2-methoxybenzoyl) (1-methylpropan-1-yl) phosphine oxide, bis (2,6-diethoxybenzoyl) (2-methyl Propan-1-yl) phosphine oxide, bis (2,6-diethoxybenzoyl) (1-methylpropan-1-yl) phosphine oxide, bis (2,6-dibutoxybenzoyl) (2-methylpropane-1- Yl) phosphine oxide, bis (2,4-dimethoxybenzoyl)
(2-methylpropan-1-yl) phosphine oxide, bis (2,4,6-trimethylbenzoyl) (2,4-dipentoxyphenyl) phosphine oxide, bis (2,6-dimethoxybenzoyl) benzylphosphine oxide, Bis (2,6-dimethoxybenzoyl) -2-phenylpropylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2-phenylethylphosphine oxide, bis (2,6-dimethoxybenzoyl) benzylphosphine oxide, bis (2 , 6-Dimethoxybenzoyl) -2-phenylpropylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2-phenylethylphosphine oxide, 2,6-dimethoxybenzoylbenzylbutylphosphine oxide, 2,6-dimethoxybenzo Rubenzyloctylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2,5-diisopropylphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2-methylphenylphosphine oxide, bis (2, 4,6-trimethylbenzoyl) -4-methylphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2,5-diethylphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2, 3,5,6-tetramethylphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2,4-di-n-butoxyphenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4- Limethylpentylphosphine oxide, bis (2,4,6-trimethylbenzoyl) isobutylphosphine oxide, 2,6-dimethyloxybenzoyl-2,4,6-trimethylbenzoyl-n-butylphosphine oxide, bis (2,4,4) 6-trimethylbenzoyl) phenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2,4-dibutoxyphenylphosphine oxide, 1,10-bis [bis (2,4,6-trimethylbenzoyl) phosphine oxide Decane, tri (2-methylbenzoyl) phosphine oxide, and the like.

  Although the usage-amount of a photoinitiator is not restrict | limited in particular, In any case of a radiation-curable adhesive (1) and (2), it is 0.01 ~ with respect to 100 weight part of the said (meth) acrylic-type polymers. 5 parts by weight, preferably 0.05 to 3 parts by weight, more preferably 0.05 to 1.5 parts by weight, and still more preferably 0.1 to 1 part by weight.

  If the amount of the photopolymerization initiator used is less than 0.01 parts by weight, the curing reaction may be insufficient. When the usage-amount of a photoinitiator exceeds 5 weight part, a photoinitiator may absorb an ultraviolet-ray and an ultraviolet-ray may not reach the inside of an adhesive layer. In this case, the curing reaction is reduced, and the cohesive force of the formed pressure-sensitive adhesive layer becomes low. When the pressure-sensitive adhesive layer is peeled from the film, a part of the pressure-sensitive adhesive layer remains on the film, and the film is reused. May not be possible.

  The radiation curable pressure-sensitive adhesive of the present invention can contain a crosslinking agent. Examples of crosslinking agents include isocyanate crosslinking agents, epoxy crosslinking agents, silicone crosslinking agents, oxazoline crosslinking agents, aziridine crosslinking agents, silane crosslinking agents, alkyl etherified melamine crosslinking agents, metal chelate crosslinking agents, and the like. A crosslinking agent is included. A crosslinking agent can be used alone or in combination of two or more. As said crosslinking agent, an isocyanate type crosslinking agent and an epoxy-type crosslinking agent are used preferably.

  The crosslinking agent may be used alone or in combination of two or more, but the total content is based on 100 parts by weight of the (meth) acrylic polymer. It is preferable to contain the said crosslinking agent in 0.005-5 weight part. The content of the crosslinking agent is preferably 0.005 to 4 parts by weight, and more preferably 0.01 to 3 parts by weight.

  The isocyanate-based crosslinking agent refers to a compound having two or more isocyanate groups in a molecule (including isocyanate-regenerating functional groups in which isocyanate groups are temporarily protected by a blocking agent or quantification).

  Examples of the isocyanate-based crosslinking agent include aromatic isocyanates such as tolylene diisocyanate and xylene diisocyanate, alicyclic isocyanates such as isophorone diisocyanate, and aliphatic isocyanates such as hexamethylene diisocyanate.

More specifically, for example, lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate, alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate and isophorone diisocyanate, 2,4-tolylene diisocyanate, Aromatic diisocyanates such as 4,4′-diphenylmethane diisocyanate, xylylene diisocyanate, polymethylene polyphenyl isocyanate, trimethylolpropane / tolylene diisocyanate trimer adduct (trade name Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.) , Trimethylolpropane / hexamethylene diisocyanate trimer adduct (trade name Coronate HL, manufactured by Nippon Polyurethane Industry Co., Ltd.), hexamethylene Isocyanurate of diisocyanate (trade name: Coronate HX, manufactured by Nippon Polyurethane Industry Co., Ltd.), xylylene diisocyanate trimethylolpropane adduct (trade name: D110N, manufactured by Mitsui Chemicals, Inc.), hexamethylene diisocyanate Trimethylolpropane adduct (trade name D160N, manufactured by Mitsui Chemicals, Inc.); polyether polyisocyanate, polyester polyisocyanate, and adducts of these with various polyols, isocyanurate bond, burette bond, allophanate bond, etc. And polyisocyanate polyfunctionalized with the above. Of these, it is preferable to use an aliphatic isocyanate because of its high reaction rate.

  The isocyanate-based crosslinking agent may be used alone or in combination of two or more, but the total content is 100 parts by weight of the (meth) acrylic polymer. On the other hand, it is preferable to contain 0.005-5 weight part of the said isocyanate type crosslinking agent, Furthermore, it is preferable to contain 0.005-4 weight part, Furthermore, it is preferable to contain 0.01-3 weight part. . It can be appropriately contained in consideration of cohesive force and prevention of peeling in a durability test.

  In addition, in the aqueous dispersion of the modified (meth) acrylic polymer prepared by emulsion polymerization, it is not necessary to use an isocyanate-based crosslinking agent. However, if necessary, it is blocked because it easily reacts with water. Isocyanate-based crosslinking agents can also be used.

  The said epoxy type crosslinking agent says the polyfunctional epoxy compound which has 2 or more of epoxy groups in 1 molecule. Examples of the epoxy crosslinking agent include bisphenol A, epichlorohydrin type epoxy resin, ethylene glycidyl ether, N, N, N ′, N′-tetraglycidyl-m-xylenediamine, diglycidylaniline, diamine glycidylamine, 1 , 3-bis (N, N-diglycidylaminomethyl) cyclohexane, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether , Polypropylene glycol diglycidyl ether, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, pentaerythritol polyglycidyl ether Glycerin diglycidyl ether, glycerin triglycidyl ether, polyglycerol polyglycidyl ether, sorbitan polyglycidyl ether, trimethylolpropane polyglycidyl ether, adipic acid diglycidyl ester, o-phthalic acid diglycidyl ester, triglycidyl-tris (2-hydroxy Ethyl) isocyanurate, resorcin diglycidyl ether, bisphenol-S-diglycidyl ether, and epoxy resins having two or more epoxy groups in the molecule. Examples of the epoxy-based crosslinking agent include commercially available products such as “Tetrad C” and “Tetrad X” manufactured by Mitsubishi Gas Chemical Co., Ltd.

  The epoxy crosslinking agent may be used alone or in combination of two or more. However, the total content is 100 parts by weight of the (meth) acrylic polymer. On the other hand, it is preferable to contain 0.005-5 weight part of said epoxy type crosslinking agents, Furthermore, it is preferable to contain 0.01-4 weight part, Furthermore, it is preferable to contain 0.01-3 weight part. . It can be appropriately contained in consideration of cohesive force and prevention of peeling in a durability test.

  Moreover, you may use together an organic type crosslinking agent and a polyfunctional metal chelate as a crosslinking agent. A polyfunctional metal chelate is one in which a polyvalent metal is covalently or coordinately bonded to an organic compound. Examples of polyvalent metal atoms include Al, Cr, Zr, Co, Cu, Fe, Ni, V, Zn, In, Ca, Mg, Mn, Y, Ce, Sr, Ba, Mo, La, Sn, Ti, and the like. Can be mentioned. Examples of the atom in the organic compound that is covalently bonded or coordinated include an oxygen atom, and examples of the organic compound include an alkyl ester, an alcohol compound, a carboxylic acid compound, an ether compound, and a ketone compound.

  The radiation curable pressure-sensitive adhesive of the present invention can contain a (meth) acrylic oligomer in order to improve the adhesive force. The (meth) acrylic oligomer is preferably a polymer having a Tg higher than that of the (meth) acrylic polymer of the present invention and a small weight average molecular weight. Such a (meth) acrylic oligomer functions as a tackifying resin and has the advantage of increasing the adhesive force without increasing the dielectric constant.

  The (meth) acrylic oligomer preferably has a Tg of about 0 ° C. or higher and 300 ° C. or lower, preferably about 20 ° C. or higher and 300 ° C. or lower, more preferably about 40 ° C. or higher and 300 ° C. or lower. When the Tg is less than about 0 ° C., the cohesive force of the pressure-sensitive adhesive layer at room temperature or higher is lowered, and the holding characteristics and the adhesiveness at high temperature may be lowered. The Tg of the (meth) acrylic oligomer is a theoretical value calculated based on the Fox equation, similar to the Tg of the (meth) acrylic polymer.

  The weight average molecular weight of the (meth) acrylic oligomer is 1000 or more and less than 30000, preferably 1500 or more and less than 20000, and more preferably 2000 or more and less than 10,000. If the weight average molecular weight is 30000 or more, the effect of improving the adhesive strength may not be sufficiently obtained. On the other hand, if the molecular weight is less than 1000, the molecular weight may be low, which may cause a decrease in adhesive strength and retention characteristics. In this invention, the measurement of the weight average molecular weight of a (meth) acrylic-type oligomer can be calculated | required in polystyrene conversion by GPC method. Specifically, TSKgelGMH-H (20) × 2 columns are used in HPLC 8020 manufactured by Tosoh Corporation, and measurement is performed with a tetrahydrofuran solvent at a flow rate of about 0.5 ml / min.

Examples of the monomer constituting the (meth) acrylic oligomer include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, and isobutyl (meth) acrylate. , S-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, heptyl (meth) acrylate, octyl (Meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undeci Alkyl (meth) acrylates such as (meth) acrylate and dodecyl (meth) acrylate; (meth) acrylic acid and alicyclic such as cyclohexyl (meth) acrylate, isobornyl (meth) acrylate and dicyclopentanyl (meth) acrylate An ester with a group alcohol; an aryl (meth) acrylate such as phenyl (meth) acrylate and benzyl (meth) acrylate; a (meth) acrylate obtained from a terpene compound derivative alcohol; and the like. Such (meth) acrylates can be used alone or in combination of two or more.

  Examples of (meth) acrylic oligomers include alkyl (meth) acrylates in which alkyl groups such as isobutyl (meth) acrylate and t-butyl (meth) acrylate have a branched structure; cyclohexyl (meth) acrylate and isobornyl (meth) Esters of (meth) acrylic acid and alicyclic alcohols such as acrylate and dicyclopentanyl (meth) acrylate; cyclic structures such as aryl (meth) acrylate such as phenyl (meth) acrylate and benzyl (meth) acrylate It is preferable that an acrylic monomer having a relatively bulky structure typified by (meth) acrylate having a monomer content is included as a monomer unit. By giving such a bulky structure to the (meth) acrylic oligomer, the adhesiveness of the pressure-sensitive adhesive layer can be further improved. In particular, those having a ring structure in terms of bulkiness are highly effective, and those having a plurality of rings are more effective. In addition, when ultraviolet rays (ultraviolet rays) are employed in the synthesis of the (meth) acrylic oligomer or in the production of the pressure-sensitive adhesive layer, those having a saturated bond are preferred in that they are less likely to cause polymerization inhibition. An alkyl (meth) acrylate having an alkyl group having a branched structure or an ester with an alicyclic alcohol can be suitably used as a monomer constituting the (meth) acrylic oligomer.

From this point, suitable (meth) acrylic oligomers include, for example, a copolymer of cyclohexyl methacrylate (CHMA) and isobutyl methacrylate (IBMA), and a copolymer of cyclohexyl methacrylate (CHMA) and isobornyl methacrylate (IBXMA). Polymer, copolymer of cyclohexyl methacrylate (CHMA) and acryloylmorpholine (ACMO), copolymer of cyclohexyl methacrylate (CHMA) and diethylacrylamide (DEAA), copolymer of 1-adamantyl acrylate (ADA) and methyl methacrylate (MMA) Polymer, copolymer of dicyclopentanyl methacrylate (DCPMA) and isobornyl methacrylate (IBXMA), cyclopentanyl methacrylate (DCPMA) and methyl Copolymer of acrylate (MMA), dicyclopentanyl methacrylate (DCPMA), cyclohexyl methacrylate (CHMA), isobornyl methacrylate (IBXMA), isobornyl acrylate (IBXA), dicyclopentanyl acrylate (DCPA), 1 -Adamantyl methacrylate (ADMA), 1-adamantyl acrylate (ADA) homopolymers, and the like. In particular, an oligomer containing CHMA as a main component is preferable.

  In the radiation curable pressure-sensitive adhesive of the present invention, when the (meth) acrylic oligomer is used, its content is not particularly limited, but it is 70 parts by weight or less with respect to 100 parts by weight of the (meth) acrylic polymer. Preferably, it is 1-70 weight part, More preferably, it is 2-50 weight part, More preferably, it is 3-40 weight part. When the added amount of the (meth) acrylic oligomer exceeds 70 parts by weight, there is a problem that the elastic modulus is increased and the adhesiveness at low temperature is deteriorated. In addition, it is effective from the point of the improvement effect of adhesive force, when mix | blending 1 weight part or more of (meth) acrylic oligomer.

  Furthermore, the radiation-curable pressure-sensitive adhesive of the present invention can contain a silane coupling agent in order to increase water resistance at the interface when applied to a hydrophilic adherend such as glass of the pressure-sensitive adhesive layer. The amount of the silane coupling agent is preferably 1 part by weight or less, more preferably 0.01 to 1 part by weight, still more preferably 0.02 to 0 parts per 100 parts by weight of the (meth) acrylic polymer. .6 parts by weight. If the amount of the silane coupling agent is too large, the adhesion to the glass increases and the removability is poor, and if it is too small, the durability decreases, which is not preferable.

  Examples of the silane coupling agent that can be preferably used include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 2- (3,4 epoxy cyclohexyl). ) Epoxy group-containing silane coupling agent such as ethyltrimethoxysilane, 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N- (1 , 3-dimethylbutylidene) propylamine, amino group-containing silane coupling agents such as N-phenyl-γ-aminopropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, etc. (Meta) Acry Group-containing silane coupling agents, such as isocyanate group-containing silane coupling agents such as 3-isocyanate propyl triethoxysilane and the like.

  Furthermore, the radiation-curable pressure-sensitive adhesive of the present invention may contain other known additives, such as powders such as colorants and pigments, dyes, surfactants, plasticizers, and tackifiers. , Surface lubricants, leveling agents, softeners, antioxidants, anti-aging agents, light stabilizers, UV absorbers, polymerization inhibitors, inorganic or organic fillers, metal powders, particles, foils, etc. Depending on the intended use, it can be added as appropriate. These addition amounts can be appropriately determined as long as the effects of the present invention are not impaired. For example, the addition amount is preferably 10 parts by weight or less with respect to 100 parts by weight of the (meth) acrylic polymer.

  Examples of the tackifier include petroleum resins, terpene resins, and hydrogenated products thereof. As the tackifier used in the radiation-curable pressure-sensitive adhesive of the present invention, a hydrogenated tackifier that does not inhibit curing by radiation such as ultraviolet rays is preferable. The pre-tackiness imparting agent can improve the adhesive force of the radiation-curable pressure-sensitive adhesive of the present invention, similarly to the (meth) acrylic oligomer. The tackifier is preferably used in the same proportion as the (meth) acrylic oligomer.

  The radiation curable pressure-sensitive adhesive layer of the present invention is formed from the radiation curable pressure-sensitive adhesive. The thickness in particular of an adhesive layer is not restrict | limited, For example, it is about 1-400 micrometers. Moreover, 50-400 micrometers is preferable, as for the thickness of the said adhesive layer, More preferably, it is 75-300 micrometers, More preferably, it is 100-200 micrometers.

The radiation-curable pressure-sensitive adhesive layer of the present invention can be cured after being bonded to an adherend. When radiation irradiation is performed by ultraviolet irradiation, a high pressure mercury lamp, a low pressure mercury lamp, a metal halide lamp, or the like can be used. The amount of ultraviolet irradiation is usually about 1000 to 10000 mJ / cm ² .

The radiation curable pressure-sensitive adhesive layer of the present invention has a shear storage elastic modulus at 23 ° C. of 1.5 × 10 ^{4 to} 1.2 × 10 ⁵ Pa and a shear storage elastic modulus of 2.degree. It is preferable that 0 × 10 ^{3 to} 4.0 × 10 ⁴ Pa and the gel fraction be 0 to 60% by weight because the step absorbability and handling properties are good. The shear storage modulus at 23 ° C. before radiation curing is further 2.0 × 10 ^{4 to} 1.0 × 10 ⁵ Pa, further 2.0 × 10 ^{4 to} 9.0 × 10 ⁴ Pa, and further 3 0.0 × 10 ^{4 to} 7.0 × 10 ⁴ Pa is preferable, and the shear storage modulus at 70 ° C. is further 5.0 × 10 ^{3 to} 4.0 × 10 ⁴ Pa, and further 1.0 ×. It is preferably 10 ^{4 to} 3.0 × 10 ⁴ Pa, more preferably 1.0 × 10 ^{4 to} 2.5 × 10 ⁴ Pa, and the gel fraction is further 0 to 55% by weight, and further 5 to 55%. It is preferably 5% by weight, further 5 to 50% by weight, further 5 to 45% by weight, further 5 to 35% by weight, and further 10 to 35% by weight.

  Further, the gel fraction before radiation curing is better as it is higher in view of workability (ease of handling), and is preferably in the range of 20 to 60% by weight, for example, 30 to 60% by weight. A range is more preferable. Moreover, from the viewpoint of step absorbability, for example, the range is preferably 0 to 45% by weight, and more preferably 0 to 40% by weight. Therefore, from the viewpoint of compatibility between step absorbability and workability, 0 to 60% by weight is preferable, further 0 to 55% by weight, further 10 to 50% by weight, further 20 to 45% by weight, and further 30 to 45% by weight. Is preferred.

The radiation curable pressure-sensitive adhesive layer of the present invention has a shear storage elastic modulus at 23 ° C. of 5.0 × 10 ^{4 to} 2.5 × 10 ⁶ Pa and a shear storage elastic modulus at 70 ° C. of 1. after radiation curing. 5 × 10 ^{4 to} 1.5 × 10 ⁵ Pa and a gel fraction of 40 to 95% by weight are preferable from the viewpoint of suppressing peeling from the adherend. The shear storage modulus at 23 ° C. after radiation curing is further 5.0 × 10 ^{4 to} 1.0 × 10 ⁶ Pa, further 8.0 × 10 ^{4 to} 4.5 × 10 ⁵ Pa, and further 9 0.0 × 10 ^{4 to} 3.0 × 10 ⁵ Pa, more preferably 1.0 × 10 ^{5 to} 2.0 × 10 ⁵ Pa, and the shear storage modulus at 70 ° C. is further 2.0. ^{× 10 4 ~1.0 × 10 5 Pa} , further ^{3.0 × 10 4 ~1.0 × 10 5} Pa, and even preferably more ^{3.0 × 10 4 ~8.0 × 10 4} Pa, a gel The fraction is preferably 45 to 85% by weight, more preferably 50 to 75% by weight. In addition, the hardening conditions of the radiation irradiation which concern on the said storage elastic modulus and gel fraction are based on description of an Example.

  The shear storage modulus at 23 ° C. and 70 ° C. is preferably such that the value after radiation curing is equal to or greater than the value before radiation curing. The shear storage modulus at 23 ° C. is preferably such that the value after radiation curing is 1.0 to 30 times the value before radiation curing, more preferably 1.0 to 27 times, and even more preferably 1.5 to 20 times, more preferably 2.0 to 10 times. Further, the shear storage modulus at 70 ° C. is preferably 1.0 to 15 times the value after radiation curing, more preferably 1.5 to 8 times, more preferably 2 after radiation curing. 0.0 to 5 times.

  As for the said gel fraction, it is preferable that the value after radiation curing is more than the value before radiation curing. The value after radiation curing is preferably 1.2 to 10 times the value before radiation curing, more preferably 1.2 to 8 times, and still more preferably 1.2 to 5 times.

  The shear storage elastic modulus and gel fraction of the radiation-curable pressure-sensitive adhesive layer are adjusted by adjusting the ratio of the radical polymerizable functional group having a carbon-carbon double bond contained in the radiation-curable pressure-sensitive adhesive and curing treatment. It can be controlled in consideration of the influence of temperature and processing time. Moreover, when an adhesive contains a crosslinking agent, it can control by adjusting the addition amount of the whole crosslinking agent and fully considering the influence of crosslinking treatment temperature and processing time. In addition, when the gel fraction of the adhesive layer after hardening is small, it is inferior to cohesion force, and when too large, it may be inferior to adhesive force.

  The radiation curable pressure-sensitive adhesive layer of the present invention preferably has a relative dielectric constant of 3.7 or less at a frequency of 100 kHz, more preferably 3.5 or less, still more preferably 3.3 or less, and still more preferably. 3.2 or less.

  The radiation curable pressure-sensitive adhesive layer of the present invention preferably has a haze value of 2% or less when the thickness of the pressure-sensitive adhesive layer is 100 μm. If the haze is 2% or less, the transparency required when the pressure-sensitive adhesive layer is used in an optical member can be satisfied. The haze value is preferably 0 to 1.5%, and more preferably 0 to 1%. In addition, if a haze value is 2% or less, it can be satisfied as an optical use. If the haze value exceeds 2%, white turbidity occurs, which is not preferable for optical film applications.

  The radiation curable pressure-sensitive adhesive layer can be formed as a pressure-sensitive adhesive sheet by, for example, applying the pressure-sensitive adhesive to a support and drying and removing a polymerization solvent and the like. In applying the adhesive, one or more solvents other than the polymerization solvent may be added as appropriate.

  Various methods are used as a method of applying the adhesive. Specifically, for example, roll coat, kiss roll coat, gravure coat, reverse coat, roll brush, spray coat, dip roll coat, bar coat, knife coat, air knife coat, curtain coat, lip coat, die coater, etc. Examples thereof include an extrusion coating method.

  The heating and drying temperature is preferably 40 ° C to 200 ° C, more preferably 50 ° C to 180 ° C, and particularly preferably 70 ° C to 170 ° C. By setting the heating temperature in the above range, an adhesive layer having excellent adhesive properties can be obtained. As the drying time, an appropriate time can be adopted as appropriate. The drying time is preferably 5 seconds to 20 minutes, more preferably 5 seconds to 10 minutes, and particularly preferably 10 seconds to 5 minutes.

  As the support, for example, a release-treated sheet can be used. A silicone release liner is preferably used as the release-treated sheet.

  When the pressure-sensitive adhesive layer is exposed on the release-treated sheet, the pressure-sensitive adhesive layer may be protected with a release-treated sheet (separator) until practical use. . In practical use, the peeled sheet is peeled off.

  Examples of the constituent material of the separator include, for example, plastic films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films, porous materials such as paper, cloth, and nonwoven fabric, nets, foam sheets, metal foils, and laminates thereof. Although a thin leaf body etc. can be mentioned, a plastic film is used suitably from the point which is excellent in surface smoothness.

  The plastic film is not particularly limited as long as it can protect the pressure-sensitive adhesive layer. For example, polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, and vinyl chloride co Examples thereof include a polymer film, a polyethylene terephthalate film, a polybutylene terephthalate film, a polyurethane film, and an ethylene-vinyl acetate copolymer film.

  The thickness of the separator is usually about 5 to 200 μm, preferably about 5 to 100 μm. For the separator, if necessary, mold release and antifouling treatment with a silicone type, fluorine type, long chain alkyl type or fatty acid amide type release agent, silica powder, etc., coating type, kneading type, vapor deposition type It is also possible to carry out antistatic treatment such as. In particular, when the surface of the separator is appropriately subjected to a release treatment such as silicone treatment, long-chain alkyl treatment, or fluorine treatment, the peelability from the pressure-sensitive adhesive layer can be further improved.

  The radiation-curable pressure-sensitive adhesive layer and pressure-sensitive adhesive sheet of the present invention can be applied to various members that become adherends. Moreover, it can use suitably for formation of the laminated body which bonded the 1st member and the 2nd member. In particular, in the laminated body, it is suitable when at least one of the first member and the second member is a member having a step on the surface, and the bonding can be performed following the step without gap. . The level difference is unevenness on the plane of each member, and is the maximum height from the plane in the thickness direction of each member. The radiation curable pressure-sensitive adhesive layer of the present invention has good followability to the step, and the thickness of the step (μm) and the pressure-sensitive adhesive layer (μm) is (step / thickness of the pressure-sensitive adhesive layer) ≦ 0 It can be suitably used in the range of .9, and even when the ratio of the step to the thickness of the pressure-sensitive adhesive layer is large as in the range of 0.5 to 0.9, the step absorbability is exhibited.

The radiation-curable pressure-sensitive adhesive layer and pressure-sensitive adhesive sheet of the present invention are preferably applied to optical members, and are preferably used for applications that are applied to metal thin films and metal electrodes, particularly in optical applications. Examples of the metal thin film include a thin film made of a metal, a metal oxide, or a mixture thereof, and are not particularly limited. For example, ITO (indium tin oxide), ZnO, SnO, CTO
And a thin film of (cadmium tin oxide). The thickness of the metal thin film is not particularly limited, but is about 10 to 200 nm. Usually, metal thin films, such as ITO, are provided on transparent plastic film base materials, such as a polyethylene terephthalate film (especially PET film), and are used as a transparent conductive film, for example. When the above-mentioned pressure-sensitive adhesive sheet of the present invention is attached to a metal thin film, it is preferably used so that the surface on the pressure-sensitive adhesive layer side becomes the pressure-sensitive adhesive surface on the side attached to the metal thin film.

  Further, the metal electrode is not particularly limited as long as it is an electrode made of a metal, a metal oxide, or a mixture thereof, and examples thereof include ITO, silver, copper, and CNT (carbon nanotube) electrodes.

  As an example of the specific use of the adhesive sheet of this invention, the adhesive sheet for touchscreens used for the manufacture use of a touchscreen can be mentioned. For example, in the production of a capacitive touch panel, the pressure-sensitive adhesive sheet for a touch panel includes a transparent conductive film provided with a metal thin film such as ITO, a polymethyl methacrylate resin (PMMA) plate, a hard coat film, a glass lens, and the like. Is used for pasting together. Although the said touch panel is not specifically limited, For example, it is used for a mobile telephone, a tablet computer, a portable information terminal, etc.

  As a more specific example, FIG. 1 shows an example of a capacitive touch panel in which the pressure-sensitive adhesive layer or pressure-sensitive adhesive sheet of the present invention is used. In FIG. 1, 1 is a capacitive touch panel, 11 is a decorative panel, 12 is an adhesive layer or an adhesive sheet, 13 is an ITO film, and 14 is a hard coat film. The decorative panel 11 is preferably a glass plate or a transparent acrylic plate (PMMA plate). The decorative panel 11 is printed on a cover glass or the like and has a printing step, and the pressure-sensitive adhesive layer or the pressure-sensitive adhesive sheet of the present invention is suitable for the step surface. The ITO film 13 is preferably a glass plate or a transparent plastic film (particularly a PET film) provided with an ITO film. The hard coat film 14 is preferably a transparent plastic film such as a PET film subjected to a hard coat treatment. The capacitive touch panel 1 uses the pressure-sensitive adhesive layer or pressure-sensitive adhesive sheet of the present invention, so that the thickness can be reduced and the operation stability is excellent. Also, the appearance and visibility are good.

  Moreover, an optical member can be used as a support body of the adhesive sheet of this invention. The pressure-sensitive adhesive layer can be applied directly to the optical member, and the pressure-sensitive adhesive layer can be formed on the optical member by drying and removing the polymerization solvent and the like. In addition, the pressure-sensitive adhesive layer formed on the release-treated separator can be appropriately transferred to an optical member to form a pressure-sensitive adhesive optical member.

  In addition, the sheet | seat which carried out the peeling process used in preparation of said adhesive type optical member can be used as a separator of an adhesive type optical member as it is, and can simplify in the surface of a process.

  Further, in the pressure-sensitive adhesive optical member, when forming the pressure-sensitive adhesive layer, the anchor layer is formed on the surface of the optical member or the pressure-sensitive adhesive layer is formed after various easy-adhesion treatments such as corona treatment and plasma treatment are performed. can do. Moreover, you may perform an easily bonding process on the surface of an adhesive layer.

  The pressure-sensitive adhesive optical member of the present invention can be used as a transparent conductive film with a pressure-sensitive adhesive layer using a transparent conductive film as an optical member. A transparent conductive film has the transparent conductive thin film used as metal thin films, such as said ITO, on one surface of a transparent plastic film base material. The other side of the transparent plastic film substrate has the pressure-sensitive adhesive layer of the present invention. A transparent conductive thin film can be provided on the transparent plastic film substrate via an undercoat layer. A plurality of undercoat layers can be provided. An oligomer migration preventing layer can be provided between the transparent plastic film substrate and the pressure-sensitive adhesive layer.

  Although it does not restrict | limit especially as said transparent plastic film base material, The various plastic film which has transparency is used. The plastic film is formed of a single layer film. For example, the materials include polyester resins such as polyethylene terephthalate and polyethylene naphthalate, acetate resins, polyethersulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth) acrylic resins. , Polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl alcohol resin, polyarylate resin, polyphenylene sulfide resin, and the like. Of these, polyester resins, polyimide resins and polyethersulfone resins are particularly preferable. The thickness of the film substrate is preferably 15 to 200 μm.

  The film base material is subjected to etching treatment or undercoating treatment such as sputtering, corona discharge, flame, ultraviolet irradiation, electron beam irradiation, chemical conversion, oxidation, etc. on the surface in advance, and a transparent conductive thin film or undercoat provided thereon You may make it improve the adhesiveness with respect to the said film base material of a layer. In addition, before providing the transparent conductive thin film or the undercoat layer, dust may be removed and cleaned by solvent cleaning or ultrasonic cleaning as necessary.

The constituent material and thickness of the transparent conductive thin film are not particularly limited, and are as exemplified in the metal thin film. The undercoat layer can be formed of an inorganic material, an organic material, or a mixture of an inorganic material and an organic material. For example, NaF (1.3), Na ₃ AlF ₆ (1.35), LiF (1.36), MgF ₂ (1.38), CaF ₂ (1.4), BaF ₂ (1. 3), inorganic substances such as SiO ₂ (1.46), LaF ₃ (1.55), CeF ₃ (1.63), Al ₂ O ₃ (1.63) Is the refractive index of light. Of these, SiO ₂ , MgF ₂ , A1 ₂ O _{3 and the} like are preferably used. In particular, SiO ₂ is suitable. In addition to the above, a composite oxide containing about 10 to 40 parts by weight of cerium oxide and about 0 to 20 parts by weight of tin oxide with respect to indium oxide can be used.

  Examples of organic substances include acrylic resins, urethane resins, melamine resins, alkyd resins, siloxane polymers, and organic silane condensates. At least one of these organic substances is used. In particular, as the organic substance, it is desirable to use a thermosetting resin made of a mixture of a melamine resin, an alkyd resin, and an organosilane condensate.

  The thickness of the undercoat layer is not particularly limited, but is usually about 1 to 300 nm, preferably 5 to 300 nm, from the viewpoint of optical design and the effect of preventing oligomer generation from the film substrate. .

  The said transparent conductive film with an adhesive layer is used in formation of various apparatuses, such as a touch panel and a liquid crystal display. In particular, it can be preferably used as an electrode plate for a touch panel. The touch panel is suitably used for various detection methods (for example, a resistance film method, a capacitance method, etc.).

  In a capacitive touch panel, a transparent conductive film provided with a transparent conductive thin film having a predetermined pattern shape is usually formed on the entire surface of the display unit. The said transparent conductive film with an adhesive layer is laminated | stacked suitably so that an adhesive layer and the patterned transparent conductive thin film may face.

  Moreover, the adhesive optical member of the present invention can be used as an optical film with an adhesive layer using an optical film for an image display device as an optical member.

  As an optical film, what is used for formation of image display apparatuses, such as a liquid crystal display device and an organic electroluminescence display, is used, and the kind in particular is not restrict | limited. For example, a polarizing plate is mentioned as an optical film. A polarizing plate having a transparent protective film on one or both sides of a polarizer is generally used.

  The polarizer is not particularly limited, and various types can be used. Examples of polarizers include dichroic iodine and dichroic dyes on hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films. Examples thereof include polyene-based oriented films such as those obtained by adsorbing substances and uniaxially stretched, polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products. Among these, a polarizer composed of a polyvinyl alcohol film and a dichroic material such as iodine is preferable. The thickness of these polarizers is not particularly limited, but is generally about 5 to 80 μm.

  A polarizer obtained by dyeing a polyvinyl alcohol film with iodine and uniaxially stretching it can be produced, for example, by dyeing polyvinyl alcohol in an aqueous solution of iodine and stretching it 3 to 7 times the original length. If necessary, it can be immersed in an aqueous solution such as potassium iodide which may contain boric acid, zinc sulfate, zinc chloride or the like. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed before dyeing. In addition to washing the polyvinyl alcohol film surface with dirt and anti-blocking agents by washing the polyvinyl alcohol film with water, it also has the effect of preventing unevenness such as uneven coloring by swelling the polyvinyl alcohol film. is there. Stretching may be performed after dyeing with iodine, may be performed while dyeing, or may be dyed with iodine after stretching. The film can be stretched even in an aqueous solution such as boric acid or potassium iodide or in a water bath.

  As a material constituting the transparent protective film, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy and the like is used. Specific examples of such thermoplastic resins include cellulose resins such as triacetyl cellulose, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth) acrylic resins, cyclic Examples thereof include polyolefin resins (norbornene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. A transparent protective film is bonded to one side of the polarizer by an adhesive layer. On the other side, as a transparent protective film, (meth) acrylic, urethane-based, acrylurethane-based, epoxy-based, silicone A thermosetting resin such as a system or an ultraviolet curable resin can be used. One or more kinds of arbitrary appropriate additives may be contained in the transparent protective film. Examples of the additive include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a mold release agent, an anti-coloring agent, a flame retardant, a nucleating agent, an antistatic agent, a pigment, and a coloring agent. The content of the thermoplastic resin in the transparent protective film is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, still more preferably 60 to 98% by weight, and particularly preferably 70 to 97% by weight. . When content of the said thermoplastic resin in a transparent protective film is 50 weight% or less, there exists a possibility that the high transparency etc. which a thermoplastic resin originally has cannot fully be expressed.

  Examples of the optical film include liquid crystal display devices such as a reflection plate, an anti-transmission plate, a retardation plate (including wavelength plates such as 1/2 and 1/4), an optical compensation film, a visual compensation film, and a brightness enhancement film. What becomes an optical layer which may be used for formation of is mentioned. These can be used alone as an optical film, or can be laminated on the polarizing plate for practical use and used as one layer or two or more layers.

  An optical film in which the optical layer is laminated on a polarizing plate can be formed by a method of sequentially laminating separately in the manufacturing process of a liquid crystal display device or the like. There is an advantage that the manufacturing process of a liquid crystal display device or the like can be improved because of excellent stability and assembly work. For the lamination, an appropriate adhesive means such as an adhesive layer can be used. When adhering the polarizing plate and the other optical layer, their optical axes can be set at an appropriate arrangement angle in accordance with the target phase difference characteristic.

  The optical film with an adhesive layer of the present invention can be preferably used for forming various image display devices such as a liquid crystal display device. The liquid crystal display device can be formed according to the conventional method. That is, a liquid crystal display device is generally formed by appropriately assembling components such as a liquid crystal cell, an optical film with an adhesive layer, and an illumination system as required, and incorporating a drive circuit. There is no limitation in particular except the point which uses the optical film with an adhesive layer by this invention, and it can apply according to the former. As the liquid crystal cell, any type such as a TN type, STN type, π type, VA type, IPS type, or the like can be used.

  An appropriate liquid crystal display device such as a liquid crystal display device in which an optical film with an adhesive layer is disposed on one side or both sides of a liquid crystal cell, or a backlight system or a reflector used in an illumination system can be formed. In that case, the optical film according to the present invention can be placed on one or both sides of the liquid crystal cell. When optical films are provided on both sides, they may be the same or different. Further, when forming a liquid crystal display device, for example, a single layer or a suitable part such as a diffusing plate, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusing plate, a backlight, etc. Two or more layers can be arranged.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In addition, all the parts and% in each example are based on weight. Evaluation items in Examples and the like were measured as follows.

Example 1
<Preparation of (meth) acrylic polymer>
In a four-necked flask equipped with a stirring blade, thermometer, nitrogen gas inlet tube, and condenser, 43 parts by weight of 2-ethylhexyl acrylate (2EHA), isostearyl acrylate (ISTA)
(Product name: ISTA, manufactured by Osaka Organic Chemical Industry Co., Ltd.) 43 parts by weight, 10 parts by weight of N-vinylpyrrolidone (NVP), 4 parts by weight of 4-hydroxybutyl acrylate (4HBA), 2,2 as a thermal polymerization initiator 0.1 parts by weight of '-azobisisobutyronitrile (AIBN) was added together with 150 parts by weight of ethyl acetate. And after stirring at 23 degreeC under nitrogen atmosphere for 1 hour, it was made to react at 58 degreeC for 4 hours, and was then made to react at 70 degreeC for 2 hours, and the (meth) acrylic-type polymer solution was prepared.

<Preparation of radiation curable pressure-sensitive adhesive (1)>
Next, in the (meth) acrylic polymer solution obtained above, polypropylene glycol (# 700) diacrylate (trade name: APG-700 as a radiation-curable monomer component with respect to 100 parts by weight of the solid content of the polymer. Shin-Nakamura Chemical Co., Ltd.) 10 parts by weight, photopolymerization initiator (trade name: Irgacure 184, manufactured by BASF) 0.1 part by weight, silane coupling agent, 3-glycidoxypropyltri 0.3 parts by weight of methoxysilane (trade name: KBM403, manufactured by Shin-Etsu Chemical Co., Ltd.) and a trimethylolpropane adduct of xylylene diisocyanate (trade name: D110N, manufactured by Mitsui Chemicals) as a crosslinking agent After adding 0.04 parts by weight, these were uniformly mixed to prepare a solution of the radiation curable pressure-sensitive adhesive (1).

<Formation of radiation curable pressure-sensitive adhesive layer: production of pressure-sensitive adhesive layer sheet>
The above-described solution of the radiation curable pressure-sensitive adhesive (1) obtained above is applied to the release-treated surface of a 50 μm-thick polyester film having one surface peeled off with silicone, heated at 100 ° C. for 3 minutes, and a thickness of 100 μm. A radiation curable pressure-sensitive adhesive layer was formed. Next, a 75 μm thick polyester film having one surface peeled with silicone is bonded to the surface of the applied radiation-curable pressure-sensitive adhesive layer so that the peel-treated surface of the film is on the coating layer side. Produced.

Examples 2-14, Comparative Examples 1-2
In Example 1, the types and composition ratios of the monomers used in <Preparation of (meth) acrylic polymer>, the radiation-curable monomer component used in <Preparation of radiation-curable adhesive (1)>, and photopolymerization Except having changed the compounding quantity of an initiator and a crosslinking agent as shown in Table 1, operation similar to Example 1 was performed and the adhesive sheet was produced.

Example 15
<Preparation of radiation curable adhesive (2)>
2 parts by weight of 2-methacryloyloxyethyl isocyanate (MOI) was added to the (meth) acrylic polymer solution prepared in Example 1 with respect to 100 parts by weight of the solid content of the polymer, and methacryloyl was added to the polymer molecule inner chain. A group was introduced. Furthermore, 0.1 parts by weight of a photopolymerization initiator (trade name: Irgacure 184, manufactured by BASF) and 3-glycidoxypropyltrimethoxysilane (trade name: KBM403, Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent )) And 0.34 parts by weight of xylylene diisocyanate trimethylolpropane adduct (trade name: D110N, manufactured by Mitsui Chemicals Co., Ltd.) And a solution of the radiation curable pressure-sensitive adhesive (2) was prepared.

<Formation of radiation curable pressure-sensitive adhesive layer: production of pressure-sensitive adhesive layer sheet>
In Example 1, instead of the solution of the radiation curable pressure-sensitive adhesive (1), the same operation as in Example 1 was performed except that the solution of the radiation curable pressure-sensitive adhesive (2) prepared above was used. An adhesive sheet was prepared.

Comparative Example 3
<Preparation of (meth) acrylic polymer>
In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser, 90 parts by weight of 2-ethylhexyl acrylate (2EHA), 10 parts by weight of acrylic acid (AA), 4-methacryloyloxybenzophenone (MBP) ) 0.35 parts by weight and 0.4 part by weight of 2,2′-azobis (2,4-valeronitrile) (V-65) as a thermal polymerization initiator were added together with 150 parts by weight of methyl ethyl ketone (MEK). And after stirring at 23 degreeC under nitrogen atmosphere for 1 hour, it was made to react at 50 degreeC for 4 hours, and was then made to react at 60 degreeC for 2 hours, and the (meth) acrylic-type polymer solution was prepared.

<Preparation of radiation curable pressure-sensitive adhesive (3)>
Subsequently, 3-glycidoxypropyltrimethoxysilane (trade name: KBM403, Shin-Etsu) is used as a silane coupling agent with respect to 100 parts by weight of the solid content of the polymer to the (meth) acrylic polymer solution obtained above. After 0.3 parts by weight of Chemical Industries, Ltd.) was added, they were uniformly mixed to prepare a solution of the radiation curable pressure-sensitive adhesive (3).

<Formation of radiation curable pressure-sensitive adhesive layer: production of pressure-sensitive adhesive layer sheet>
The above-mentioned solution of the radiation curable pressure-sensitive adhesive (3) obtained above is applied to the release surface of a 50 μm-thick polyester film whose one side is release-treated with silicone, heated at 100 ° C. for 3 minutes, and a thickness of 100 μm. A radiation curable pressure-sensitive adhesive layer was formed. Next, a 75 μm thick polyester film having one surface peeled with silicone is bonded to the surface of the applied radiation-curable pressure-sensitive adhesive layer so that the peel-treated surface of the film is on the coating layer side. Produced.

  The following evaluation was performed about the adhesive sheet (sample) obtained by the said Example and comparative example. The evaluation results are shown in Table 2.

<Measurement of gel fraction>
A predetermined amount (initial weight W1) is taken out from the pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet, immersed in an ethyl acetate solution and allowed to stand at room temperature for one week. It was calculated as follows.
Gel fraction = (W2 / W1) × 100
The gel fraction was measured for the measurement sample before irradiation and after irradiation. Irradiation was performed using a high-pressure mercury lamp under the condition of an ultraviolet irradiation amount of 2500 mJ / cm ² .

<Measurement of shear storage modulus>
The shear storage modulus at 23 ° C. and 70 ° C. was determined by dynamic viscoelasticity measurement. The pressure-sensitive adhesive sheets were laminated to obtain a laminate (laminated pressure-sensitive adhesive layer) having a thickness of about 1.5 mm. The laminate was used as a measurement sample. Using the dynamic viscoelasticity measuring device (device name “ARES” (manufactured by TA Instruments Inc.), the measurement sample was heated at a temperature range of −20 to 100 ° C. under the condition of a frequency of 1 Hz. The shear storage modulus was calculated at a rate of 5 ° C./min and calculated at 23 ° C. and 70 ° C. The shear storage modulus was measured for the measurement sample before and after irradiation, respectively. Irradiation was performed using a high-pressure mercury lamp under the condition of an ultraviolet irradiation amount of 2500 mJ / cm ² .

<Evaluation method of step absorbency>
A sheet piece having a width of 50 mm and a length of 100 mm was cut out from the adhesive sheet. One release film was peeled from the sheet piece, and the pressure-sensitive adhesive layer side of the sheet piece was bonded to a COP (cyclic polyolefin) film (thickness 100 μm) using a hand roller.
Next, the other release film was peeled from the sheet piece bonded to the COP film. The glass plate with printing steps was bonded under the following bonding conditions so that the surface of the glass plate on which the printing steps were applied and the pressure-sensitive adhesive layer on the glass plate were in contact. And the sample for evaluation which has a structure of a COP film / adhesive layer / glass plate with a printing level | step difference was obtained.
(Bonding conditions)
Surface pressure: 0.3 MPa
Pasting speed: 25mm / s
Roll rubber hardness: 70 °
The above-described glass plate with a printed step is formed on one surface of a glass plate (manufactured by Matsunami Glass Industry Co., Ltd., length 100 mm, width 50 mm, thickness 0.7 mm). The glass plate on which printing of 50 μm or 80 μm was applied was used.
(Step / thickness of the pressure-sensitive adhesive layer) × 100 (%), which is an index indicating the step absorbability, is 50% and 80%, respectively.
Next, the sample for evaluation was put into an autoclave, and autoclaved for 15 minutes under conditions of a pressure of 5 atm and a temperature of 50 ° C. After the autoclave treatment, a sample for evaluation was taken out, the state of sticking between the pressure-sensitive adhesive layer and the printed stepped glass plate was visually observed, and the step absorbability was evaluated according to the following evaluation criteria.
○: No bubbles remained and no float occurred between the pressure-sensitive adhesive layer and the printed stepped glass plate.
X: Air bubbles remain, and floating is generated between the pressure-sensitive adhesive layer and the printed stepped glass plate.

<Adhesion reliability evaluation method>
The evaluation sample (laminated body) after the autoclave treatment in the above <Method for evaluating step absorbability> was irradiated with ultraviolet rays (ultraviolet ray irradiation amount: 2500 mJ / cm ² ) to cure the pressure-sensitive adhesive layer. Next, the sample for evaluation was put in under conditions of heating (85 ° C.) and humidification (60 ° C./95% RH) for 24 hours, and the adhesion reliability was evaluated according to the following evaluation criteria.
◯: No bubbles are generated, and no float is generated between the pressure-sensitive adhesive layer and the glass plate with a printed step.
X: Air bubbles are generated, and floating is generated between the pressure-sensitive adhesive layer and the glass plate with a printed step.

<Dielectric constant>
A pressure-sensitive adhesive layer having a thickness of 100 μm (ultraviolet ray irradiation amount: 2500 mJ / cm ² , and a silicone-treated PET film peeled from the pressure-sensitive adhesive sheet) is sandwiched between a copper foil and an electrode, and the frequency of 100 kHz is obtained by the following apparatus. The relative dielectric constant was measured. Three samples were prepared for measurement, and the average of the measured values of these three samples was taken as the dielectric constant.
The relative dielectric constant of the pressure-sensitive adhesive layer at a frequency of 100 kHz was measured according to JIS K 6911 under the following conditions.
Measurement method: Capacity method (apparatus: using Agilent Technologies 4294A Precision Impedance Analyzer)
Electrode configuration: 12.1 mmφ, 0.5 mm thick aluminum plate Counter electrode: 3 oz copper plate Measurement environment: 23 ± 1 ° C., 52 ± 1% RH

<Workability test>
What peeled off one release liner (polyester film) of the pressure-sensitive adhesive layer sheet according to each example and each comparative example, bonded a polyethylene terephthalate film with a thickness of 25 μm, and cut it into 10 mm width × 40 mm length. A test piece was obtained. As shown in FIG. 2 (a), the adhesive surface of the test piece 3 was bonded to a bakelite plate 2 cleaned with toluene in an area of 10 mm in width and 20 mm in length, and left in an environment of 27 ° C. for 30 minutes. . Thereafter, the weight 4 was suspended at one end of the test piece so that a load of 500 g was applied in the shear direction. After hanging the weight 4, the amount of deformation (the distance (unit: mm) the specimen moved in the shear direction in the plastic deformation region) from 30 minutes to 60 minutes was measured with a displacement meter (not shown). From the amount of displacement, the ease of movement (inclination) of the test piece was calculated by the following equation. When this value is 4.0 (mm / hour) or less, the workability is good (◯), exceeds 4.0 (mm / hour), and less than 7.0 (mm / hour) is (Δ), 7.0. (Mm / hour) or more was defined as poor workability (x).
Ease of movement of test piece (mm / hour) = (movement distance of plastic deformation region (mm)) / (0.5 hours)

  Here, FIG. 2B is a distance-time curve in the workability test. The vertical axis is the distance that the specimen moved in the shear direction, and the horizontal axis is the time since the weight was suspended. The plastic deformation region is 30 minutes to 60 minutes after suspending the weight (6 in FIG. 2B), and immediately after the weight is suspended (5 in FIG. 2B) is the elastic deformation region. .

In Table 1, 2EHA is 2-ethylhexyl acrylate (manufactured by Toagosei Co., Ltd., homopolymer Tg = −70 ° C.);
ISTA is isostearyl acrylate (manufactured by Osaka Organic Chemical Co., Ltd., homopolymer Tg = −18 ° C.);
LMA is lauryl methacrylate;
LA is lauryl acrylate;
iDMA is isodecyl methacrylate;
AA is acrylic acid;
MMA is methyl methacrylate;
NVP is N-vinyl-2-pyrrolidone (manufactured by Nippon Shokubai Co., Ltd.);
NVC is N-vinyl-ε-caprolactam;
4HBA is 4-hydroxybutyl acrylate;
HEA is 2-hydroxyethyl acrylate;
MBP represents 4-methacryloyloxybenzophenone.

  D110N indicates a trimethylolpropane adduct of xylylene diisocyanate (manufactured by Mitsui Chemicals, Inc.).

APG-400 is polypropylene glycol (# 400) diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.);
APG-700 is polypropylene glycol (# 700) diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.);
MOI is 2-methacryloyloxyethyl isocyanate;
HX-620 is a di (meth) acrylate of ε-caprolactone adduct of neopentyl glycol hydroxybivalate (KAYARAD HX-620 (manufactured by Nippon Kayaku Co., Ltd.));
A-PTMG65 is polytetramethylene glycol (# 650) diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.);
M-1200 represents urethane acrylate (manufactured by Toagosei Co., Ltd.).

DESCRIPTION OF SYMBOLS 1 Capacitance type touch panel 11 Decorative panel 12 Adhesive layer or adhesive sheet 13 ITO film 14 Hard coat film 2 Bakelite board 3 Test piece 4 Weight 5 Elastic deformation area 6 Plastic deformation area

Claims (13)

(Meth) obtained by polymerizing a monomer component containing 30 to 90% by weight of an alkyl (meth) acrylate having an alkyl group having 10 to 22 carbon atoms at the ester end and 5 to 25% by weight of a cyclic nitrogen-containing monomer In addition to the acrylic polymer and the (meth) acrylic polymer, a compound having at least one radical polymerizable functional group having a carbon-carbon double bond in the molecule ,
The radiation curable pressure-sensitive adhesive, wherein the alkyl group of the alkyl (meth) acrylate having an alkyl group having 10 to 22 carbon atoms at an ester terminal is a branched alkyl group. (Meth) obtained by polymerizing a monomer component containing 30 to 90% by weight of an alkyl (meth) acrylate having an alkyl group having 10 to 22 carbon atoms at the ester terminal and 5 to 25% by weight of a cyclic nitrogen-containing monomer Contains acrylic polymers,
The (meth) acrylic polymer is a (meth) acrylic polymer having a radical polymerizable functional group having a carbon-carbon double bond,
The radiation curable pressure-sensitive adhesive, wherein the alkyl group of the alkyl (meth) acrylate having an alkyl group having 10 to 22 carbon atoms at an ester terminal is a branched alkyl group. The radiation-curable pressure-sensitive adhesive according to claim 1, wherein the (meth) acrylic polymer is a (meth) acrylic polymer having a radical polymerizable functional group having a carbon-carbon double bond. The monomer component is a monomer component further comprising 1 to 20% by weight of at least one functional group-containing monomer selected from a carboxyl group-containing monomer, a hydroxyl group-containing monomer, and a monomer having a cyclic ether group. The radiation curable pressure-sensitive adhesive according to any one of claims 1 to 3 . The monomer component further contains at least one selected from an alkyl (meth) acrylate having an alkyl group having 1 to 9 carbon atoms at the ester terminal and an alkyl (meth) acrylate having a cyclic alkyl group at the ester terminal. The radiation-curable pressure-sensitive adhesive according to claim 1 , which is a monomer component containing 5% by weight or more. Furthermore, 0.005-5 weight part of crosslinking agents are contained with respect to 100 weight part of said (meth) acrylic-type polymers, The radiation hardening type of any one of Claims 1-5 characterized by the above-mentioned. Adhesive. A radiation curable pressure-sensitive adhesive layer obtained from the radiation curable pressure-sensitive adhesive according to any one of claims 1 to 6 . The radiation curable pressure-sensitive adhesive layer according to claim 7 , wherein the dielectric constant at a frequency of 100 kHz is 3.7 or less. A radiation curable pressure-sensitive adhesive sheet, wherein the radiation curable pressure-sensitive adhesive layer according to claim 7 or 8 is formed on at least one side of the support. The radiation-curable pressure-sensitive adhesive sheet according to claim 9 , wherein the support is an optical member, and the pressure-sensitive adhesive sheet is a pressure-sensitive adhesive optical member having a pressure-sensitive adhesive layer on at least one side of the optical member. The laminated body characterized by the 1st member and the 2nd member being bonded together through the radiation-curing-type adhesive layer of Claim 7 or 8 . At least one of the first member and the second member is a member having a step on the surface,
The laminate according to claim 11, wherein the step (μm) and the thickness (μm) of the pressure-sensitive adhesive layer satisfy (step / thickness of the pressure-sensitive adhesive layer) ≦ 0.9. The laminate according to claim 11 or 12, wherein at least one of the first member and the second member is an optical member.