WO2018221109A1 - 光学部材用活性エネルギー線硬化型粘着シート - Google Patents
光学部材用活性エネルギー線硬化型粘着シート Download PDFInfo
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- WO2018221109A1 WO2018221109A1 PCT/JP2018/017303 JP2018017303W WO2018221109A1 WO 2018221109 A1 WO2018221109 A1 WO 2018221109A1 JP 2018017303 W JP2018017303 W JP 2018017303W WO 2018221109 A1 WO2018221109 A1 WO 2018221109A1
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- sensitive adhesive
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
- C09J133/04—Homopolymers or copolymers of esters
- C09J133/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, the oxygen atom being present only as part of the carboxyl radical
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J7/00—Adhesives in the form of films or foils
- C09J7/10—Adhesives in the form of films or foils without carriers
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J7/00—Adhesives in the form of films or foils
- C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
- C09J7/38—Pressure-sensitive adhesives [PSA]
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J2301/00—Additional features of adhesives in the form of films or foils
- C09J2301/30—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier
- C09J2301/312—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier parameters being the characterizing feature
Definitions
- the present invention relates to a pressure-sensitive adhesive sheet having a low dielectric constant and excellent step absorbability and handleability (for example, cut property, rework property, and storage property). Among them, preferably, for example, it can be suitably used when forming an image display device such as a personal computer, a mobile terminal (PDA), a game machine, a television (TV), a car navigation system, a touch panel, a pen tablet,
- PDA mobile terminal
- TV television
- TV television
- touch panel a touch panel
- pen tablet a pen tablet
- the present invention relates to an active energy ray-curable pressure-sensitive adhesive sheet for optical members.
- image display devices equipped with a touch sensor function particularly image display devices equipped with a capacitive touch sensor function, have become widespread mainly in mobile phones and portable terminals.
- the capacitance of a capacitor formed between two electrodes facing each other through an insulating film changes when a conductor such as a finger approaches from the surface protection panel side.
- This is a touch sensor that detects the position and detects the position.
- the adhesive sheet used for filling between the electrode and the surface protection panel is required to have a low dielectric constant in order to absorb the change in the touch detection sensitivity and suppress the generation of noise in the detection signal. .
- the electrode substrate is being replaced from glass to a resin film.
- the electrode substrate is being replaced from glass to a resin film.
- Patent Document 1 discloses an acrylic compound (A) having a relative dielectric constant of 3.0 or less at a frequency of 100 kHz and a linear or branched alkyl group having 1 to 9 carbon atoms.
- a double-sided pressure-sensitive adhesive sheet comprising an acrylic acid ester copolymer (B) obtained by copolymerizing a (meth) acrylic acid ester monomer and / or a vinyl ether monomer having a side chain is disclosed.
- the entire sheet can have a cross-linked structure, handling properties (ease of handling) can be enhanced, for example, the sheet shape can be maintained even when heated.
- it contains an acrylic acid ester copolymer (B) obtained by copolymerizing a (meth) acrylic acid ester monomer and / or a vinyl ether monomer having a linear or branched alkyl group having 1 to 9 carbon atoms in the side chain. Therefore, suitable adhesive properties can be obtained. For example, due to environmental changes such as temperature and humidity, the bonded members do not cause foaming or peeling, and have appropriate elasticity and dent recoverability. be able to.
- Patent Document 2 discloses an alkyl (meth) acrylate (a1) having a branched alkyl group having 8 to 24 carbon atoms at the ester end and an alkyl (meth) having a linear alkyl group having 8 to 24 carbon atoms at the ester end.
- a pressure-sensitive adhesive comprising a (meth) acrylic polymer obtained by polymerizing a monomer component containing an acrylate (a2) is disclosed.
- a low dielectric constant pressure-sensitive adhesive layer can be realized by the action of the long-chain branched alkyl group and the long-chain linear alkyl group, and the adhesive performance can be satisfied.
- a touch panel type image display device is usually configured by combining a surface protection panel, a touch panel, and an image display panel (collectively, also referred to as “component for image display device”).
- surface protection panels for touch panel image display devices such as smartphones and tablet terminals have been made of tempered glass and plastic materials such as acrylic resin plates and polycarbonate plates. The part is printed in black.
- a plastic film sensor is used together with a glass sensor, a member in which the touch panel function is integrated with the surface protection panel (for example, a touch-on lens (TOL)) is used, or the touch panel function is applied to the image display panel.
- the touch panel function is integrated with the surface protection panel (for example, a touch-on lens (TOL)) is used, or the touch panel function is applied to the image display panel.
- An integrated member for example, in-cell or on-cell is used.
- Patent Document 3 discloses an ultraviolet-crosslinkable pressure-sensitive adhesive sheet comprising a (meth) acrylic copolymer of a monomer containing a (meth) acrylic acid ester having an ultraviolet-crosslinkable site, and a pressure-sensitive adhesive before UV-crosslinking. storage modulus of the sheet, 30 ° C., at 1Hz, 5.0 ⁇ 10 4 Pa or more, 1.0 ⁇ 10 6 Pa or less, and 80 ° C., at 1 Hz, or less 5.0 ⁇ 10 4 Pa, further An ultraviolet-crosslinkable pressure-sensitive adhesive sheet in which the storage elastic modulus of the pressure-sensitive adhesive sheet after ultraviolet crosslinking is 1.0 ⁇ 10 3 Pa or more at 130 ° C. and 1 Hz is disclosed.
- the step or the bulge even if the thickness is about the same as the height of the step or the bulge (for example, 20 to 30 ⁇ m) by heating and / or pressurization in the stage before UV crosslinking, the step or As a result, it is possible to follow the bulge, and as a result, no gap or the like is generated in the step or in the vicinity of the bulge, and the internal residual stress of the adhesive sheet in the vicinity of the step or in the bulge is not unnecessarily high. Moreover, highly reliable adhesion
- attachment is realizable by performing an ultraviolet-ray bridge
- the pressure-sensitive adhesive sheet disclosed in Patent Document 1 or Patent Document 2 described above is intended to reduce the dielectric constant of the pressure-sensitive adhesive sheet while maintaining the original function of the pressure-sensitive adhesive sheet. .
- the printing step absorbability when considering the printing step absorbability, it is excellent even though it is a thin object (for example, 30 to 50 ⁇ m) by imparting flexibility to the pressure-sensitive adhesive sheet like the pressure-sensitive adhesive sheet disclosed in Patent Document 3 above.
- the handling property for example, the cut property, the rework property, and the storage property
- the pressure-sensitive adhesive sheet of Patent Document 3 does not consider reduction of the dielectric constant.
- the object of the present invention is not only to realize both low dielectric constant and excellent printing level difference absorbability, but also excellent handling property as an adhesive sheet (for example, cut property, rework property, storage property). It is to provide a new adhesive sheet.
- the present invention is an active energy ray-curable pressure-sensitive adhesive sheet containing an acrylic resin (A), wherein the acrylic resin (A) has an active energy ray crosslinkable structure site and has 10 to 10 carbon atoms.
- the main feature is that it is a (co) polymer of a monomer component containing a (meth) acrylic acid ester monomer (a) having 24 linear alkyl groups, and the following is a summary.
- the present invention is an active energy ray-curable pressure-sensitive adhesive sheet containing an acrylic resin (A), wherein the acrylic resin (A) has an active energy ray crosslinkable structure site and has 10 to 10 carbon atoms.
- An optical member which is a (co) polymer of a monomer component containing a (meth) acrylic acid ester monomer (a) having 24 linear alkyl groups and has at least all the following characteristics (1) to (3)
- An active energy ray-curable pressure-sensitive adhesive sheet is proposed.
- Tensile modulus at a temperature of 23 ° C. is 0.03 MPa or more.
- this invention is an active energy ray hardening-type adhesive sheet containing acrylic resin (A), Comprising:
- the said acrylic resin (A) has an active energy ray crosslinkable structure site
- Proposing an active energy ray-curable pressure-sensitive adhesive sheet for optical members having a region containing the acrylic resin (A) having a different storage elastic modulus G ′ and having a relative dielectric constant of 3.7 or less at a frequency of 100 kHz. It is.
- the active energy ray-curable pressure-sensitive adhesive sheet for optical members of the present invention can realize both low dielectric constant characteristics and excellent printing step absorbability. Moreover, since it is excellent in handling properties (for example, cutability / reworkability / storage properties) as an adhesive sheet, for example, a personal computer, a mobile terminal (PDA), a game machine, a television (TV), a car navigation system, a touch panel. It can be suitably used when forming an image display device such as a pen tablet.
- PDA mobile terminal
- TV television
- TV television
- touch panel a touch panel
- FIG. 1 is a sample schematic diagram of a tensile modulus measurement test in Examples and Comparative Examples.
- (Meth) acryl means acryl and methacryl
- (meth) acryloyl means acryloyl and methacryloyl
- (meth) acrylate means acrylate and methacrylate
- (co) polymer is intended to encompass polymers and copolymers.
- the “sheet” conceptually includes a sheet, a film, and a tape.
- the active energy ray-curable pressure-sensitive adhesive sheet for optical members of the present invention contains an acrylic resin (A), and the acrylic resin (A) has an active energy ray crosslinkable structure.
- this pressure-sensitive adhesive sheet has at least all the following properties (1) to (3).
- Tensile modulus at a temperature of 23 ° C. is 0.03 MPa or more.
- the displacement length by the holding force test is 1 mm or more.
- (3) The relative dielectric constant at a frequency of 100 kHz is 3.7 or less.
- the pressure-sensitive adhesive sheet has the above-mentioned characteristics, and ensures handling properties (for example, cutability / reworkability / storage) as a pressure-sensitive adhesive sheet while achieving both low dielectric constant characteristics and excellent print level difference absorbability. be able to.
- This pressure-sensitive adhesive sheet contains, as an acrylic resin (A), a (meth) acrylic acid ester monomer (a) having an active energy ray-crosslinkable structural site and a linear alkyl group having 10 to 24 carbon atoms.
- the (co) polymer of the monomer component is used, and this makes it possible to obtain a pressure-sensitive adhesive sheet in which the tensile modulus and holding force are adjusted to be within a predetermined range while reducing the dielectric constant.
- This adhesive sheet has a tensile elastic modulus at a temperature of 23 ° C. of 0.03 MPa or more. By setting the tensile elastic modulus within such a range, excellent handleability can be ensured. From this viewpoint, the tensile elastic modulus of the pressure-sensitive adhesive sheet is preferably 0.03 MPa to 1.0 MPa, and more preferably 0.03 MPa to 0.5 MPa.
- This adhesive sheet has a displacement length of 1 mm or more according to the holding force test.
- the deviation length is 1 mm or more, the printing step absorbability can be obtained.
- the deviation length of the pressure-sensitive adhesive sheet is 1.0 mm or more and 20 mm or less.
- required from a holding power test is a value calculated
- This pressure-sensitive adhesive sheet uses a specific acrylic resin (A) to have a flexible property that the displacement length is 1 mm or more and at the same time has a hard property that the tensile elastic modulus is 0.03 MPa or more. Have. In this way, this pressure-sensitive adhesive sheet uses a specific acrylic resin (A) to achieve a low dielectric constant, while being flexible and excellent in handling properties such as cut properties, and printing step absorption and handling. It is possible to have a contradictory property called a property. More specifically, by having a pressure-sensitive adhesive sheet design having a laminated structure as described later while having the above characteristics (1) to (3), it is possible to have higher printing step absorbability and handleability.
- the tensile elastic modulus means a value obtained by the method described in Examples described later
- the storage elastic modulus G ′ means a storage elastic modulus when dynamic viscoelasticity measurement is performed in a shear mode.
- the region having different storage elastic modulus G ′ is, for example, a case where two or more layers having different storage elastic modulus G ′ are laminated, or there is no interface clearly indicating the interlayer, but the storage elastic modulus G ′ This includes cases where different parts exist.
- region containing the said acrylic resin (A) from which the said storage elastic modulus G 'differs for example, it has at least n layer containing the said acrylic resin (A), and the 1st layer and the 1st layer
- the i-th layer may have different storage elastic moduli G ′ at a frequency of 1 Hz and a temperature of 20 ° C. (hereinafter also referred to as “lamination structure”).
- lamination structure n and i are each independently an integer of 2 or more.
- the i-th layer preferably has a storage elastic modulus G 'of 40 kPa to 1 MPa at a frequency of 1 Hz and a temperature of 20 ° C.
- G ′ storage elastic modulus
- the pressure-sensitive adhesive sheet itself has a firmness
- the pressure-sensitive adhesive resin adheres to the punching die and the slit blade
- the pressure-sensitive adhesive material rotates around the cut end. It is possible to prevent the peeling film from being peeled off, and to prevent problems such as sticking out of the edge.
- the first layer preferably has a storage elastic modulus G ′ of 30 kPa or more and 70 kPa or less at a frequency of 1 Hz and a temperature of 20 ° C.
- G ′ storage elastic modulus
- the storage elastic modulus G ′ adjusts the irradiation amount of active energy rays and the amount of active energy ray crosslinkable structural sites. Or by adjusting the amount of cross-linking agent to adjust the degree of cross-linking, it can be within the above range.
- an acrylic resin (A) described later it is preferable to contain an acrylic resin (A) described later.
- the pressure-sensitive adhesive sheet having the above-described laminated structure has a structure in which n layers or more are laminated, specifically, the first layer / second layer, the first layer / second layer. There may be mentioned a laminated structure having / third layer, first layer / second layer /... / I-th layer. Although not all layers need to be pressure-sensitive adhesive layers, it is preferable that at least the first (surface layer) and / or the n-th layer (back layer) is a pressure-sensitive adhesive layer.
- the present pressure-sensitive adhesive sheet having the above-described laminated structure has a mode in which the intermediate layer contains the acrylic resin (A) with respect to the front and back layers, and the storage elastic modulus G ′ of the front and back layers is different from that of the intermediate layer. It is most preferable in that the adhesive sheet itself has a firmness with a thick intermediate layer, and the step following ability can be secured with a flexible front and back layer.
- n and i are each independently an integer of 2 or more.
- n is 2, n is the same as i.
- n is 3 or more, n> i is satisfied. Is preferred.
- the storage elastic modulus G ′ at the frequency of 1 Hz and the temperature of 20 ° C. of the third layer may be the same as or different from that of the first layer, but is preferably the same.
- the thickness of the pressure-sensitive adhesive sheet is preferably in the range of 20 ⁇ m to 500 ⁇ m (excluding the thickness when a substrate sheet is provided). For example, if the thickness is 20 ⁇ m or more, the adhesion to the adherend and the impact absorbability are not hindered, and if it is 500 ⁇ m or less, the demand for thinning can be met. Accordingly, the thickness of the present pressure-sensitive adhesive sheet is preferably 20 ⁇ m to 500 ⁇ m, more preferably 30 ⁇ m or more and 300 ⁇ m or less, and particularly preferably 50 ⁇ m or more or 200 ⁇ m or less.
- the first and n-th total thickness that is, the ratio of the thickness (S2) of the i-th layer to the total thickness (S1) of the front and back layers ((S1) / (S2)) Is preferably 0.05 ⁇ (S1) / (S2) ⁇ 2.
- the contribution of the thickness of the front and back layers in the laminate does not become too large, and it is preferable that the workability such as cutting and handling becomes inferior due to being too flexible.
- the ratio of the thickness (S2) of the i-th layer to the total thickness (S1) of the front and back layers is more preferably 0.1 ⁇ (S1) / (S2) ⁇ 2, and 0.1 ⁇ More preferably, (S1) / (S2) ⁇ 1.
- the adhesive sheet preferably has a relative dielectric constant of 3.7 or less at a frequency of 100 kHz.
- the relative dielectric constant of the pressure-sensitive adhesive sheet is more preferably 3.5 or less, and more preferably 3.2 or less.
- the relative dielectric constant is a value obtained by the method described in Examples described later.
- This adhesive sheet contains acrylic resin (A).
- the acrylic resin (A) is a monomer component comprising a (meth) acrylic acid ester monomer (a) having an active energy ray crosslinkable structural site and having a linear alkyl group having 10 to 24 carbon atoms. A co) polymer is preferred.
- the active energy ray crosslinkable structure site reacts with a part of the acrylic resin (A) or a curing component other than the acrylic resin (A) by irradiation with active energy rays to form a crosslinked structure. It is a structural site to obtain.
- Examples of the active energy ray crosslinkable structure site include a structure having a radical polymerizable functional group having a carbon-carbon double bond such as a functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group.
- a benzophenone structure which can be excited by irradiation with ultraviolet light and can extract a hydrogen radical in the excited state.
- electromagnetic waves such as far ultraviolet rays, ultraviolet rays, near ultraviolet rays, infrared rays
- electromagnetic waves such as X rays and ⁇ rays, electron beams, proton rays, neutron rays, etc.
- Curing by ultraviolet irradiation is advantageous from the viewpoint of speed, availability of the irradiation device, price, and the like.
- a structure having a radical polymerizable functional group having a carbon-carbon double bond such as a functional group having an unsaturated double bond
- an acrylic resin such as 2-isocyanatoethyl (meth) acrylate
- a monomer having an unsaturated double bond and a functional group that reacts with the functional group may be reacted with the functional group in the acrylic resin.
- the active energy ray crosslinkable structure site containing (meth) acrylic acid ester monomer ( ⁇ ) is used as a copolymerization component. What is necessary is just to copolymerize.
- the (meth) acrylic acid ester monomer ( ⁇ ) containing an active energy ray crosslinkable structure site it is more efficient to contain a (meth) acrylic acid ester monomer having a benzophenone structure by active energy rays such as ultraviolet rays and electron beams.
- active energy rays such as ultraviolet rays and electron beams.
- specific examples include 4- (meth) acryloyloxybenzophenone.
- the content of the active energy ray-crosslinkable structure site-containing (meth) acrylic acid ester monomer ( ⁇ ) is preferably 0.01 to 5% by mass with respect to the entire copolymer component, and in particular, the benzophenone structure
- the content of the (meth) acrylic acid ester monomer having is preferably 0.01 to 5% by mass, particularly preferably 0.1 to 2% by mass, and still more preferably based on the entire copolymer component. 0.2 to 1% by mass.
- the acrylic resin (A) has an active energy ray crosslinkable structure site, the acrylic resin (A) can be efficiently cured (crosslinked), and cohesive force can be obtained without containing an acid component. And has excellent anti-foaming reliability (in particular, excellent anti-ultraviolet (UV) anti-foaming reliability).
- the benzophenone structure is most preferable as the active energy ray crosslinkable structure site.
- Examples of the (meth) acrylic acid ester monomer (a) having a linear alkyl group having 10 to 24 carbon atoms include decyl (meth) acrylate (alkyl group having 10 carbon atoms), lauryl (meth) acrylate (carbon number). 12), tridecyl (meth) acrylate (carbon number 13), hexadecyl (meth) acrylate (carbon number 16), stearyl (meth) acrylate (carbon number 18), behenyl (meth) acrylate (carbon number 22), and the like. . These may be used alone or in combination of two or more.
- a (meth) acrylic acid ester monomer having a linear alkyl group having 10 to 24 carbon atoms and having a hydroxyl group is treated as (b) below.
- alkyl methacrylate is preferable because it can lower the dielectric constant and lower the glass transition temperature of the acrylic resin.
- alkyl methacrylate is particularly preferable, and stearyl methacrylate, lauryl methacrylate, and tridecyl methacrylate are most preferable.
- the content of the (meth) acrylic acid alkyl ester monomer (a) having a linear alkyl group having 10 to 24 carbon atoms is from 50 to 94% by mass, preferably from 60 to 94% by mass based on the entire (co) polymerization component. 83 mass%, particularly preferably 70 to 80 mass%.
- the acrylic resin (A) is a co-polymer of monomer components including a hydroxyl group-containing (meth) acrylic acid ester monomer (b) as a monomer component other than the above (a) from the viewpoint of improving the resistance to moist heat whitening. It is preferably a coalescence.
- hydroxyl group-containing (meth) acrylic acid ester monomer (b) examples include 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 5-hydroxypentyl (meth) acrylate, 6-hydroxyhexyl (meta) ) Acrylate, acrylic acid hydroxyalkyl esters such as 8-hydroxyoctyl (meth) acrylate, caprolactone modified monomers such as caprolactone modified 2-hydroxyethyl (meth) acrylate, oxy such as diethylene glycol (meth) acrylate, polyethylene glycol (meth) acrylate, etc.
- Alkylene-modified monomers other 2-acryloyloxyethyl-2-hydroxyethylphthalic acid, N-methylol (meth) acrylamide, hydroxyethylacrylamide
- a primary hydroxyl group-containing monomer such as 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate and the like; 2,2-dimethyl-2 -Tertiary hydroxyl group-containing monomers such as hydroxyethyl (meth) acrylate. These may be used alone or in combination of two or more.
- a primary hydroxyl group-containing monomer is preferable in terms of excellent reactivity with a crosslinking agent and improvement in moisture and heat whitening resistance, and further, there are few impurities such as di (meth) acrylate, and it is easy to manufacture.
- 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate are preferable, and 4-hydroxybutyl acrylate is particularly preferable.
- the content of the hydroxyl group-containing (meth) acrylic acid ester monomer (b) in the copolymer component is preferably 5 to 15% by mass, particularly preferably 8 to 14% by mass, based on the total copolymer component. More preferably, it is 10 to 13% by mass.
- the content ratio of the monomer components (a) and (b) in the copolymer component is preferably 50 to 94% by mass for (a) and 5 to 15% by mass for (b).
- the free acid contained in the acrylic resin (A) is preferably 1.0% or less, particularly preferably 0.5% or less, and further preferably 0.1% or less. By setting it within the above range, there is no possibility that the thermal stability is deteriorated and the corrosion of the metal adherend when the pressure-sensitive adhesive sheet is formed proceeds. Thus, in order to reduce the content of free acid in the acrylic resin (A), the free acid contained in the hydroxyl group-containing (meth) acrylic acid ester monomer (b) may be reduced. Is preferably 1.0% or less, particularly preferably 0.5% or less, and still more preferably 0.1% or less.
- the acrylic resin (A) is a (meth) acrylic acid alkyl ester having a branched chain-containing alkyl group as a monomer component other than the above (b) from the viewpoint of efficiently increasing the cohesive force while keeping the dielectric constant low.
- a copolymer of monomer components including the monomer (c) is preferable.
- the (meth) acrylic-acid alkylester monomer which has a branched chain containing alkyl group has a hydroxyl group
- Examples of the (meth) acrylic acid alkyl ester monomer (c) having a branched chain-containing alkyl group include, for example, a branched chain-containing monomer having a tertiary carbon in the alkyl group and a branched chain-containing monomer having a t-Bu group. Can be mentioned.
- a branched chain-containing monomer having a tertiary carbon in the alkyl group can efficiently extract hydrogen during photocrosslinking to increase cohesion, and has a t-Bu group such as tert-butyl (meth) acrylate.
- the branched chain-containing monomer has an ability to improve cohesion by increasing the glass transition temperature.
- the (meth) acrylic acid alkyl ester monomer having a branched chain-containing alkyl group it is preferable to use iso-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, or tert-butyl (meth) acrylate, particularly preferably. Is 2-ethylhexyl (meth) acrylate or tert-butyl (meth) acrylate.
- the content (weight ratio) of the copolymer components (a) and (c) in the copolymer component is preferably 100/0 to 70/30, and particularly preferably 100/0 to 80/20. More preferably, it is 90/10 to 85/15. By setting it within the above range, there is no possibility that the thermal stability is lowered or the adhesive properties are lowered.
- the acrylic resin (A) may be a copolymer that contains another copolymerizable ethylenically unsaturated monomer as a monomer component, if necessary, as a copolymer component.
- copolymerizable ethylenically unsaturated monomers include, for example, phenyl (meth) acrylate, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenyldiethylene glycol (meth) acrylate, 2-hydroxy-3-phenoxypropyl
- Aromatic ring-containing monomers such as (meth) acrylate, phenoxypolyethylene glycol (meth) acrylate, phenoxypolyethylene glycol-polypropylene glycol- (meth) acrylate, orthophenylphenoxyethyl (meth) acrylate, nonylphenol ethylene oxide adduct (meth) acrylate; Cyclohexyl (meth) acrylate, cyclohexyloxyalkyl (meth) acrylate, t-butylcyclohexyloxyethyl ( ) Acrylate, isobornyl (meth) acryl
- the acrylic resin (A) can be produced by appropriately selecting and polymerizing the above polymerization components.
- a polymerization method of the acrylic resin (A) for example, a conventionally known polymerization method such as solution polymerization, suspension polymerization, bulk polymerization, emulsion polymerization or the like can be used, but in the present invention, it is produced by solution polymerization. It is preferable that the acrylic resin (A) can be produced safely and stably with an arbitrary monomer composition.
- Organic solvent examples include aromatic hydrocarbons such as toluene and xylene, aliphatic hydrocarbons such as hexane, esters such as ethyl acetate and butyl acetate, N-propyl alcohol, and isopropyl alcohol.
- Aliphatic alcohols such as acetone, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone.
- a solvent having a boiling point of 70 ° C. or less is used in that a solvent-free acrylic resin can be efficiently produced by distilling off the solvent from the acrylic resin solution obtained by solution polymerization. preferable.
- organic solvents having a boiling point of 70 ° C. or lower include hydrocarbon solvents such as n-hexane (67 ° C.), alcohol solvents such as methanol (65 ° C.), and methyl acetate (54 ° C.).
- hydrocarbon solvents such as n-hexane (67 ° C.)
- alcohol solvents such as methanol (65 ° C.)
- methyl acetate 54 ° C.
- ester solvents such as acetone (56 ° C.), diethyl ether (35 ° C.), methylene chloride (40 ° C.), tetrahydrofuran (66 ° C.), among others, versatility and safety.
- acetone and methyl acetate are preferably used, and acetone is particularly preferable.
- the numerical value in () described following each said organic solvent name is a boiling point.
- an azo polymerization initiator or a peroxide polymerization initiator which is a normal radical polymerization initiator can be used, and as the azo polymerization initiator, for example, 2,2'-azobis (2-methylbutyronitrile), 2,2'-azobisisobutyronitrile, (1-phenylethyl) azodiphenylmethane, 2,2'-azobis (2,4-dimethylvaleronitrile) ), 2,2′-azobis (2-cyclopropylpropionitrile), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile) and the like.
- benzoyl peroxide di-t-butyl peroxide, cumene hydroperoxide, lauroyl peroxide, t-butyl peroxypivalate, - hexyl peroxypivalate, t-hexyl peroxyneodecanoate, diisopropyl peroxycarbonate, include diisobutyryl peroxide and the like. These may be used alone or in combination of two or more.
- the acrylic resin (A) it is preferable to perform polymerization at a relatively low temperature using a solution polymerization reaction solvent having a boiling point of 70 ° C. or lower. At this time, if a polymerization initiator having a high 10-hour half-life temperature is used, the polymerization initiator tends to remain, and when the polymerization initiator remains, a step of distilling off the solvent from the acrylic resin (A) solution described later. Tends to cause gelation of acrylic resin.
- the numerical value in () described following each compound name is the 10-hour half
- the amount of the polymerization initiator used is usually 0.001 to 10 parts by weight, preferably 0.1 to 8 parts by weight, particularly preferably 0.5 to 6 parts by weight with respect to 100 parts by weight of the polymerization component. Further, it is preferably 1 to 4 parts by mass, particularly preferably 1.5 to 3 parts by mass, and most preferably 2 to 2.5 parts by mass. By setting the amount within the above range, there is no possibility that the polymerization rate of the acrylic resin decreases, the residual monomer increases, or the weight average molecular weight of the acrylic resin increases.
- polymerization conditions for solution polymerization
- polymerization conditions may be carried out in accordance with conventionally known polymerization conditions.
- a polymerization component containing a (meth) acrylic monomer and a polymerization initiator are mixed or dropped in a solvent to a predetermined polymerization condition. Can be polymerized.
- the polymerization temperature in the above polymerization reaction is usually 40 to 120 ° C., but is preferably 50 to 90 ° C., more preferably 55 to 75 ° C., and particularly preferably 60 to 70 ° C. from the viewpoint of stable reaction.
- the acrylic resin (A) is easily gelled, the activity of the polymerization initiator is lowered, the polymerization rate is lowered, and the residual monomer is increased.
- the polymerization time in the polymerization reaction is not particularly limited, but it is 0.5 hours or more, preferably 1 hour or more after the last addition of the polymerization initiator. More preferably, it is 2 hours or more, particularly preferably 5 hours or more.
- the polymerization reaction is preferably performed while refluxing the solvent from the viewpoint of easy heat removal.
- the acrylic resin (A) in order to reduce the amount of the residual polymerization initiator, it is preferable to perform additional heating in order to thermally decompose the polymerization initiator.
- the driving-in heating temperature is preferably higher than the 10-hour half-life temperature of the polymerization initiator, specifically 40 to 150 ° C., and preferably 55 to 130 ° C. from the viewpoint of suppressing gelation.
- the temperature is preferably 75 to 95 ° C.
- an acrylic resin (A) solution can be obtained.
- the solvent is distilled off from the obtained acrylic resin (A) solution.
- the step of distilling off the solvent from the acrylic resin (A) solution can be carried out by a known general method.
- a method of distilling off the solvent a method of distilling off the solvent by heating or depressurization is conducted.
- There is a method of distilling off the solvent but from the viewpoint of efficiently distilling off the solvent, a method of distilling off by heating under reduced pressure is preferred.
- the temperature at which the solvent is distilled off by heating is preferably 60 to 150 ° C., and in particular, the reaction solution after polymerization of the acrylic resin (A) is maintained at 60 to 80 ° C. And then distilling the solvent at 80 to 150 ° C. is preferable in that the amount of the remaining solvent is extremely reduced. In addition, it is preferable not to perform the temperature in the case of solvent distillation at 150 degreeC or more from the point which suppresses gelatinization of an acrylic resin (A).
- the pressure when the solvent is distilled off under reduced pressure is preferably 20 to 101.3 kPa, and in particular, after the solvent in the reaction solution is distilled by maintaining the pressure in the range of 50 to 101.3 kPa. From the viewpoint of extremely reducing the amount of residual solvent, it is preferable to distill the residual solvent at 0 to 50 kPa. Thus, the acrylic resin (A) can be produced.
- the acrylic resin (A) preferably has a weight average molecular weight of 100,000 or more, more preferably 150,000 to 1,500,000, particularly preferably 200,000 to 1,000,000, particularly preferably 250,000 to 800,000, Particularly preferred is 300,000 to 600,000.
- the weight average molecular weight of the said acrylic resin (A) is a weight average molecular weight at the time of completion of manufacture, and is a weight average molecular weight of the acrylic resin (A) which is not heated after manufacture.
- the dispersity (weight average molecular weight / number average molecular weight) of the acrylic resin (A) is preferably 15 or less, more preferably 10 or less, particularly 7 or less, and particularly preferably 5 or less. By setting it within such a range, the durability performance of each layer is lowered, and there is no possibility that foaming or the like occurs or handleability is lowered.
- the lower limit of the degree of dispersion is usually 1.1 from the viewpoint of production limit.
- said weight average molecular weight is a weight average molecular weight by standard polystyrene molecular weight conversion, and it is a column in a high performance liquid chromatography (The Japan Waters company, "Waters 2695 (main body)” and “Waters 2414 (detector)”).
- Shodex GPC KF-806L exclusion limit molecular weight: 2 ⁇ 10 7 , separation range: 100 to 2 ⁇ 10 7 , theoretical plate number: 10,000 plates / piece
- filler material styrene-divinylbenzene copolymer
- the number average molecular weight can be measured using the same method. The degree of dispersion is determined from the weight average molecular weight and the number average molecular weight.
- the acrylic resin (A) preferably has a glass transition temperature (Tg) of ⁇ 100 to 50 ° C., particularly ⁇ 80 to 0 ° C., more preferably ⁇ 70 to ⁇ 10 ° C.
- Tg glass transition temperature
- the glass transition temperature is calculated from the following formula 1 of the following Fox.
- Tg Glass transition temperature of copolymer (K)
- Tga Glass transition temperature (K) of homopolymer of monomer A
- Wa Weight fraction of monomer A
- Tgb Glass transition temperature of homopolymer of monomer B
- Wb Weight fraction of monomer B
- Tgn Homogeneous of monomer N
- the acrylic resin (A) has a melt viscosity (mPa ⁇ s) at 100 ° C. of preferably 1,000 to 10,000,000 mPa ⁇ s, particularly preferably 50,000 to 1,000,000 mPa ⁇ s, Preferably, it is 200,000 to 600,000 mPa ⁇ s.
- said viscosity is the value which measured the load 30kg, orifice diameter 1.0mm, die
- the acrylic resin (A) is preferably a solventless acrylic resin that does not substantially contain a solvent, and the solvent content of the acrylic resin (A) is preferably 2% by mass or less. Is preferably 0.00001 to 2% by mass, more preferably 0.0001 to 1% by mass, and particularly preferably 0.001 to 0.1% by mass. By setting it within the above range, there is no possibility that bubbles are generated or durability is lowered.
- the residual monomer amount in the acrylic resin (A) is preferably 2% by mass or less, particularly preferably 0.00001 to 1.5% by mass, and more preferably 0.0001 to 1.0% by mass. is there.
- the solvent content and the amount of residual monomer in the acrylic resin (A) were obtained by diluting the acrylic resin (A) 20-fold with toluene, and using a gas chromatography / mass fragment detector (GC: 7890A GCsystem manufactured by Agilent Technologies). , MSD: a value measured using Agilent Technologies 5975inert).
- GC gas chromatography / mass fragment detector
- the volatile content in the acrylic resin (A) (usually the solvent and the residual monomer are the main components) is preferably 2% by mass or less, particularly preferably 0.00001 to 1.5% by mass. More preferably, the content is 0.0001 to 1.0% by mass.
- the volatile content in the acrylic resin (A) was calculated from the weight change before and after heating the acrylic resin (A) in a hot air dryer at 130 ° C. for 1 hour. Value.
- This pressure-sensitive adhesive sheet has a cross-linking agent (B) in addition to the acrylic resin (A) in terms of high cohesion for improving the handleability (for example, cutability / reworkability / storage properties) as a pressure-sensitive adhesive sheet. You may form from the composition to contain.
- crosslinking agent (B) examples include (meth) acryloyl group, epoxy group, isocyanate group, carboxyl group, hydroxyl group, carbodiimide group, oxazoline group, aziridine group, vinyl group, amino group, imino group, and amide group.
- the crosslinking agent which has at least 1 sort (s) of crosslinkable functional group chosen can be mentioned, You may use 1 type or in combination of 2 or more types.
- the crosslinkable functional group may be protected with a deprotectable protecting group.
- a polyfunctional organic function having two or more organic functional groups such as a polyfunctional (meth) acrylate having two or more (meth) acryloyl groups, an isocyanate group, an epoxy group, a melamine group, a glycol group, a siloxane group or an amino group.
- An organometallic compound having a metal complex such as a base resin, zinc, aluminum, sodium, zirconium, or calcium can be preferably used.
- polyfunctional (meth) acrylate examples include 1,4-butanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, glycerin di (meth) acrylate, glycerin glycidyl ether di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, tricyclodecane dimethanol di (meth) acrylate, bisphenol A polyethoxydi (meth) acrylate, bisphenol A polyalkoxydi (meth) ) Acrylate, bisphenol F polyalkoxy di (meth) acrylate, polyalkylene glycol di (meth) acrylate, trimethylolpropane trioxyethyl (meth) acrylate, ⁇ -caprolactone modified (2-hydroxyethyl) isocyanurate tri (me
- polyfunctional (meth) acrylate monomers polar functional groups such as a hydroxyl group, a carboxyl group, and an amide group from the viewpoint of improving the adhesion to the adherend and the effect of suppressing wet heat whitening.
- Polyfunctional monomers or oligomers containing are preferred.
- a monofunctional or polyfunctional (meth) acrylic acid ester that reacts with a crosslinking agent may be further added.
- the content of the crosslinking agent is 0.1 to 20 parts by mass with respect to 100 parts by mass of the acrylic resin (A) from the viewpoint of balancing the flexibility and cohesive force of the pressure-sensitive adhesive composition.
- 0.5 to 15 parts by mass, particularly 1 to 13 parts by mass is particularly preferable.
- the present pressure-sensitive adhesive sheet having the above-mentioned laminated structure preferably contains a cross-linking agent (B) in the i-th layer in terms of imparting better handling properties (for example, cutability, reworkability, and storage property) Especially, it is most preferable to include in layers other than the 1st and nth layers, ie, layers other than the front and back layers.
- B cross-linking agent
- This pressure-sensitive adhesive sheet contains an acrylic resin (A), but contains a photopolymerization initiator (C) in addition to the acrylic resin (A) in that it can stabilize the reaction during irradiation with active energy rays. You may form from the composition to do.
- the photopolymerization initiator (C) is not particularly limited as long as it generates radicals by the action of light, and examples thereof include acetophenone-based, benzoin-based, benzophenone-based, thioxanthone-based, and acylphosphine oxide-based light.
- Examples of the polymerization initiator include hydrogen abstraction-type benzophenone-based photopolymerization initiators from the viewpoint of efficient crosslinking between molecules or within a molecule.
- benzophenone-based photopolymerization initiator examples include benzophenone, benzoylbenzoic acid, 3,3′-dimethyl-4-methoxybenzophenone, and polyvinylbenzophenone. These may be used alone or in combination of two or more.
- auxiliary agents for these photopolymerization initiators include triethanolamine, triisopropanolamine, 4,4′-dimethylaminobenzophenone (Michler ketone), 4,4′-diethylaminobenzophenone, 2-dimethylaminoethylbenzoic acid, Ethyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate (n-butoxy), isoamyl 4-dimethylaminobenzoate, 2-ethylhexyl 4-dimethylaminobenzoate, 2,4-diethylthioxanthone, 2, 4-diisopropylthioxanthone or the like can be used in combination. These auxiliaries may be used alone or in combination of two or more.
- the blending amount of the photopolymerization initiator (C) is preferably 0.01 to 10 parts by mass, particularly preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of the acrylic resin (A). Part, more preferably 0.5 to 2 parts by weight. If the blending amount is too small, there is no possibility that the curing rate is lowered or the curing is insufficient.
- the pressure-sensitive adhesive sheet may be formed from a composition containing known components blended in a normal pressure-sensitive adhesive composition.
- tackifying resins processing aids (such as oil components), silane coupling agents, antioxidants, light stabilizers, metal deactivators, UV absorbers (UVA), light stabilizers (HALS),
- UV absorbers UVA
- HALS light stabilizers
- Various additives such as a rust inhibitor, an anti-aging agent, a hygroscopic agent, a hydrolysis inhibitor, and a nucleating agent can be appropriately contained.
- This pressure-sensitive adhesive sheet is a base sheet or a release sheet in which the resin composition containing the acrylic resin (A) and, if necessary, a crosslinking agent (B) and a photopolymerization initiator (C) is melted by heat. It can be manufactured by coating (coating) on a mold sheet and then cooling.
- the present pressure-sensitive adhesive sheet having a laminated structure is formed by applying (coating) the resin composition onto a base sheet or a release sheet in a melted state by heat, and then cooling the first layer.
- the coating (coating) method is not particularly limited as long as it is a general coating method, and examples thereof include roll coating, die coating, gravure coating, comma coating, and screen printing.
- the pressure-sensitive adhesive sheet may be a pressure-sensitive adhesive sheet with a base material sheet provided with a pressure-sensitive adhesive layer on the base material sheet, or a base-less pressure-sensitive adhesive sheet provided with a pressure-sensitive adhesive layer on a release sheet.
- the base sheet examples include polyester resins such as polyethylene naphthalate, polyethylene terephthalate, polybutylene terephthalate, and polyethylene terephthalate / isophthalate copolymer; polyolefin resins such as polyethylene, polypropylene, and polymethylpentene; polyvinyl fluoride, Polyfluorinated ethylene resins such as polyvinylidene fluoride and polyfluorinated ethylene; polyamides such as nylon 6 and nylon 6,6; polyvinyl chloride, polyvinyl chloride / vinyl acetate copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl Vinyl polymers such as alcohol copolymers, polyvinyl alcohol and vinylon; cellulose resins such as cellulose triacetate and cellophane; polymethyl methacrylate, polyethyl methacrylate, polyacrylate Acrylic resin such as polybutyl acrylate, polystyrene, polycarbonate, polyary
- release sheet for example, various synthetic resin sheets exemplified in the base sheet, paper, cloth, non-woven fabric and the like can be used.
- release sheet it is preferable to use a silicon-based release sheet.
- the adhesive sheet is preferably used by irradiating an active energy line after being bonded to the adherend. Therefore, when this active adhesive sheet is irradiated with active energy rays so that the integrated light quantity at 365 nm is 2000 mJ or more, the first layer has a storage elastic modulus G ′ at a frequency of 1 Hz and a temperature of 80 ° C. before and after irradiation.
- the difference (storage elastic modulus G ′ after irradiation ⁇ storage elastic modulus G ′ before irradiation) is 5 kPa or more, and the i-th layer has a difference (irradiation) of storage elastic modulus G ′ at a frequency of 1 Hz and a temperature of 80 ° C. It is preferable that the storage elastic modulus G ′ after storage—the storage elastic modulus G ′ before irradiation) is 2 kPa or more.
- the first layer has a difference in storage elastic modulus G ′ at a frequency of 1 Hz and a temperature of 80 ° C. (storage elastic modulus G ′ after irradiation) from the viewpoint of providing step absorption and foaming reliability.
- the storage elastic modulus G ′ before irradiation is preferably 5 kPa or more
- the i-th layer has a difference in storage elastic modulus G ′ at a frequency of 1 Hz and a temperature of 80 ° C. (storage elastic modulus G ′ after irradiation) It is preferable that the storage elastic modulus G ′) before irradiation is 4 kPa or more.
- this pressure-sensitive adhesive sheet leaves room for curing with active energy rays, but among them, when the degree of curing is adjusted so as to have the storage elastic modulus difference in the above range, While realizing a dielectric constant, it is possible to have extremely high printing step absorbability.
- the storage elastic modulus G ′ can be adjusted by the method described above.
- This pressure-sensitive adhesive sheet can be used for bonding an optical display member, for example, an image display device constituent member.
- the image display device constituent member include a constituent member of an image display device such as a personal computer, a mobile terminal (PDA), a game machine, a television (TV), a car navigation system, a touch panel, a pen tablet, LCD, PDP, or EL. Can do.
- a polarizing film or the like is laminated on a liquid crystal panel display (LCD), and a plastic protective panel is laminated thereon via an adhesive or a sheet.
- LCD liquid crystal panel display
- PVA polyvinyl alcohol
- triacetyl cellulose resin may be used as a constituent material of the polarizing film, and it has been found that these easily release outgas.
- a laminate composed of a protective panel / this adhesive sheet / polarizing film is prepared, and active energy rays are irradiated through these image display device constituent members (protecting panel or polarizing film) to thereby produce this adhesive sheet.
- active energy rays are irradiated through these image display device constituent members (protecting panel or polarizing film) to thereby produce this adhesive sheet.
- An intermediate resin layer composition (A-1) was prepared by melt-kneading 50 g of an ultraviolet curable resin propoxylated pentaerythritol triacrylate (“ATM-4PL” manufactured by Shin-Nakamura Chemical Co., Ltd.) as a crosslinking agent to 1 kg of this acrylic resin A. ) was prepared.
- ATM-4PL an ultraviolet curable resin propoxylated pentaerythritol triacrylate
- the composition (A-1) was mixed with two release films, ie two peeled polyethylene terephthalate films (“Diafoil MRV-V06” manufactured by Mitsubishi Chemical Corporation, thickness 100 ⁇ m / manufactured by Mitsubishi Chemical Corporation “ Diafoil MRQ ”(thickness 75 ⁇ m), and using a laminator, the sheet is shaped to a thickness of 90 ⁇ m at a temperature of 80 ° C., and the intermediate layer forming laminated sheet 1 (intermediate resin layer (A-1)) A thickness of 90 ⁇ m) was produced.
- two release films ie two peeled polyethylene terephthalate films
- Diafoil MRV-V06 manufactured by Mitsubishi Chemical Corporation, thickness 100 ⁇ m / manufactured by Mitsubishi Chemical Corporation “ Diafoil MRQ ”(thickness 75 ⁇ m)
- (Laminated sheet 2 for forming an intermediate layer) 44.5 parts by mass of a mixture of lauryl methacrylate and tridecyl methacrylate (SLMA), 10 parts by mass of 2-ethylhexyl methacrylate (2EHMA), 35 parts by mass of n-stearyl methacrylate (SMA), and 4-hydroxybutyl acrylate (4HBA)
- SMA 2-ethylhexyl methacrylate
- 4HBA 4-hydroxybutyl acrylate
- An acrylic resin B prepared by random copolymerization of 10 parts by mass and 0.5 parts by mass of 4-methacryloyloxybenzophenone (MBP) was prepared.
- An intermediate resin layer composition (B-1) was prepared by melting and kneading 50 g of UV curable resin propoxylated pentaerythritol triacrylate (“ATM-4PL” manufactured by Shin-Nakamura Chemical Co., Ltd.) as a crosslinking agent to 1 kg of this acrylic resin B. ) was prepared.
- ATM-4PL UV curable resin propoxylated pentaerythritol triacrylate
- the composition (B-1) was mixed with two release films, ie two peeled polyethylene terephthalate films (“Diafoil MRV-V06” manufactured by Mitsubishi Chemical Corporation, thickness 100 ⁇ m / manufactured by Mitsubishi Chemical Corporation “ Diafoil MRQ ”(thickness 75 ⁇ m), and using a laminator, the sheet is shaped into a thickness of 90 ⁇ m at a temperature of 80 ° C., and the intermediate layer forming laminated sheet 2 (intermediate resin layer (B-1) A thickness of 90 ⁇ m) was produced.
- two release films ie two peeled polyethylene terephthalate films
- Diafoil MRV-V06 manufactured by Mitsubishi Chemical Corporation, thickness 100 ⁇ m / manufactured by Mitsubishi Chemical Corporation “ Diafoil MRQ ”(thickness 75 ⁇ m)
- (Laminated sheet 3 for forming an intermediate layer) 52.5 parts by mass of a mixture of lauryl methacrylate and tridecyl methacrylate (SLMA), 20 parts by mass of 2-ethylhexyl methacrylate (2EHMA), 15 parts by mass of n-stearyl methacrylate (SMA), and 2-hydroxyethyl acrylate (2HEA)
- SMA lauryl methacrylate and tridecyl methacrylate
- EHMA 2-ethylhexyl methacrylate
- SMA n-stearyl methacrylate
- 2-HEA 2-hydroxyethyl acrylate
- An acrylic resin C prepared by random copolymerization of 12 parts by mass and 0.5 parts by mass of 4-methacryloyloxybenzophenone (MBP) was prepared.
- An intermediate resin layer composition (C-1) was prepared by melt-kneading 50 g of UV-cured resin propoxylated pentaerythritol triacrylate (“ATM-4PL” manufactured by Shin-Nakamura Chemical Co., Ltd.) as a crosslinking agent into 1 kg of this acrylic resin C. ) was prepared.
- ATM-4PL UV-cured resin propoxylated pentaerythritol triacrylate
- the composition (C-1) was mixed with two release films, ie two peeled polyethylene terephthalate films (“Diafoil MRV-V06” manufactured by Mitsubishi Chemical Corporation, thickness 100 ⁇ m / manufactured by Mitsubishi Chemical Corporation “ Diafoil MRQ ”(thickness 75 ⁇ m), and using a laminator, the sheet is shaped to a thickness of 90 ⁇ m at a temperature of 80 ° C., and the intermediate layer forming laminated sheet 3 (intermediate resin layer (C-1) A thickness of 90 ⁇ m) was produced.
- two release films ie two peeled polyethylene terephthalate films
- Diafoil MRV-V06 manufactured by Mitsubishi Chemical Corporation, thickness 100 ⁇ m / manufactured by Mitsubishi Chemical Corporation “ Diafoil MRQ ”(thickness 75 ⁇ m)
- (Laminated sheet 4 for intermediate layer formation) 82.6 parts by mass of a mixture of lauryl methacrylate and tridecyl methacrylate (SLMA), 5 parts by mass of t-butyl methacrylate (tBMA), 12 parts by mass of 4-hydroxybutyl acrylate (4HBA), 4-methacryloyloxybenzophenone (MBP)
- SLMA lauryl methacrylate and tridecyl methacrylate
- tBMA t-butyl methacrylate
- 4HBA 4-hydroxybutyl acrylate
- MBP 4-methacryloyloxybenzophenone
- An intermediate resin layer composition (D-1) was prepared by melting and kneading 50 g of UV curable resin propoxylated pentaerythritol triacrylate (“ATM-4PL” manufactured by Shin-Nakamura Chemical Co., Ltd.) as a crosslinking agent to 1 kg of this acrylic resin D. ) was prepared.
- ATM-4PL UV curable resin propoxylated pentaerythritol triacrylate
- the composition (D-1) was mixed with two release films, ie two peeled polyethylene terephthalate films (“Diafoil MRV-V06” manufactured by Mitsubishi Chemical Corporation, thickness 100 ⁇ m / manufactured by Mitsubishi Chemical Corporation “ Diafoil MRQ ”(thickness 75 ⁇ m), and using a laminator, the sheet is shaped to a thickness of 90 ⁇ m at a temperature of 80 ° C., and the intermediate layer forming laminated sheet 4 (intermediate resin layer (D-1) A thickness of 90 ⁇ m) was produced.
- two release films ie two peeled polyethylene terephthalate films
- Diafoil MRV-V06 manufactured by Mitsubishi Chemical Corporation, thickness 100 ⁇ m / manufactured by Mitsubishi Chemical Corporation “ Diafoil MRQ ”(thickness 75 ⁇ m)
- the composition (E-1) was mixed with two release films, ie two peeled polyethylene terephthalate films (“Diafoil MRV-V06” manufactured by Mitsubishi Chemical Corporation, thickness 100 ⁇ m / manufactured by Mitsubishi Chemical Corporation “ Diafoil MRQ ”(thickness 75 ⁇ m), and using a laminator, the sheet is shaped to a thickness of 90 ⁇ m at a temperature of 80 ° C., and the intermediate layer forming laminated sheet 5 (intermediate resin layer (E-1) A thickness of 90 ⁇ m) was produced.
- two release films ie two peeled polyethylene terephthalate films
- Diafoil MRV-V06 manufactured by Mitsubishi Chemical Corporation, thickness 100 ⁇ m / manufactured by Mitsubishi Chemical Corporation “ Diafoil MRQ ”(thickness 75 ⁇ m)
- Two release films of the acrylic resin A that is, two peeled polyethylene terephthalate films (“Diafoil MRV-V06” manufactured by Mitsubishi Chemical Corporation, thickness 100 ⁇ m / “Diafoil MRQ” manufactured by Mitsubishi Chemical Corporation) , 75 ⁇ m thick) and shaped into a sheet shape using a laminator to a thickness of 30 ⁇ m to produce an outermost layer forming laminated sheet 1 (thickness of the pressure-sensitive adhesive layer A of 30 ⁇ m).
- Two release films of the acrylic resin B that is, two polyethylene terephthalate films subjected to release treatment (“Diafoil MRV-V06” manufactured by Mitsubishi Chemical Corporation, thickness 100 ⁇ m / “Diafoil MRQ” manufactured by Mitsubishi Chemical Corporation) , 75 ⁇ m thick), and using a laminator, it was formed into a sheet shape at a temperature of 80 ° C. so as to have a thickness of 30 ⁇ m, and the outermost layer forming laminated sheet 2 (thickness of the pressure-sensitive adhesive layer B was 30 ⁇ m) was produced.
- Two release films of the acrylic resin D that is, two peeled polyethylene terephthalate films (“Diafoil MRV-V06” manufactured by Mitsubishi Chemical Corporation, thickness 100 ⁇ m / “Diafoil MRQ” manufactured by Mitsubishi Chemical Corporation) , 75 ⁇ m thick) and using a laminator, it was shaped into a sheet shape at a temperature of 80 ° C. to a thickness of 30 ⁇ m, and the outermost layer forming laminated sheet 4 (thickness of the pressure-sensitive adhesive layer D was 30 ⁇ m) was produced.
- (Laminated sheet 5 for outermost layer formation) Composition for outermost resin layer obtained by melt-kneading 15 g of a mixture of 2,4,6-trimethylbenzophenone and 4-methylbenzophenone as photoinitiators (“Ezacure TZT” manufactured by Lanberti) in 1 kg of acrylic resin E E ′ is two release films, ie two peeled polyethylene terephthalate films (“Diafoil Mrv-V06” manufactured by Mitsubishi Chemical Corporation, thickness 100 ⁇ m / “Diafoil MRQ” manufactured by Mitsubishi Chemical Corporation, thickness
- the laminate sheet 5 for forming the outermost layer was prepared using a laminator and shaped into a sheet shape having a thickness of 30 ⁇ m at a temperature of 80 ° C.
- UV light is irradiated with a high-pressure mercury lamp through a polyethylene terephthalate film remaining on the surface so that the integrated light quantity at 365 nm is 500 mJ, and A and (A-1) are UV-crosslinked, and pressure-sensitive adhesive sheet 1 (total A thickness of 150 ⁇ m) was produced.
- the pressure-sensitive adhesive sheet 1 is in a semi-cured state, that is, in a state where there is room for further curing, by adjusting the irradiation amount of ultraviolet rays.
- a pressure-sensitive adhesive sheet 2 was produced in the same manner as in Example 1 except that (B-1) was used for the intermediate resin layer and B was used for the outermost layer.
- a pressure-sensitive adhesive sheet 3 was produced in the same manner as in Example 1 except that (C-1) was used for the intermediate resin layer and C was used for the outermost layer.
- a pressure-sensitive adhesive sheet 4 was produced in the same manner as in Example 1 except that (D-1) was used for the intermediate resin layer and D was used for the outermost layer.
- a pressure-sensitive adhesive sheet 5 was produced in the same manner as in Example 1 except that (A-1) was used for the intermediate resin layer and B was used for the outermost layer.
- a pressure-sensitive adhesive sheet 6 was produced in the same manner as in Example 1 except that (B-1) was used for the intermediate resin layer and A was used for the outermost layer.
- a pressure-sensitive adhesive sheet 7 was produced in the same manner as in Example 1 except that (C-1) was used for the intermediate resin layer and A was used for the outermost layer.
- a pressure-sensitive adhesive sheet 8 was produced in the same manner as in Example 1 except that (A-1) was used for the intermediate resin layer and C was used for the outermost layer.
- a pressure-sensitive adhesive sheet 9 was produced in the same manner as in Example 1 except that (B-1) was used for the intermediate resin layer and C was used for the outermost layer.
- a pressure-sensitive adhesive sheet 10 was produced in the same manner as in Example 1 except that (C-1) was used for the intermediate resin layer and B was used for the outermost layer.
- composition (A-1) was mixed with two release films, ie, two peeled polyethylene terephthalate films (“Diafoil MRV-V06” manufactured by Mitsubishi Chemical Corporation, thickness 100 ⁇ m / “Diameter” manufactured by Mitsubishi Chemical Corporation).
- Foil MRQ (thickness 75 ⁇ m) and shaped into a sheet shape with a laminator to a thickness of 150 ⁇ m, thereby producing an adhesive sheet 11.
- a pressure-sensitive adhesive sheet 12 was produced in the same manner as in Comparative Example 1 except that the composition (B-1) was used instead of the composition (A-1).
- a pressure-sensitive adhesive sheet 13 was produced in the same manner as in Comparative Example 1 except that the composition (C-1) was used instead of the composition (A-1).
- a pressure-sensitive adhesive sheet 14 was produced in the same manner as in Comparative Example 1 except that the composition (D-1) was used instead of the composition (A-1).
- a pressure-sensitive adhesive sheet 15 was produced in the same manner as in Comparative Example 1 except that the acrylic resin A was used instead of the composition (A-1).
- a pressure-sensitive adhesive sheet 16 was produced in the same manner as in Comparative Example 1 except that the acrylic resin B was used in place of the composition (A-1).
- a pressure-sensitive adhesive sheet 17 was produced in the same manner as in Comparative Example 1 except that the acrylic resin C was used instead of the composition (A-1).
- a pressure-sensitive adhesive sheet 18 was produced in the same manner as in Comparative Example 1 except that the acrylic resin D was used instead of the composition (A-1).
- a pressure-sensitive adhesive sheet 19 was produced in the same manner as in Comparative Example 1 except that the composition E ′ was used instead of the composition (A-1).
- a pressure-sensitive adhesive sheet 20 was produced in the same manner as in Comparative Example 1 except that the composition (E-1) was used instead of the composition (A-1).
- a pressure-sensitive adhesive sheet 21 was produced in the same manner as in Example 1 except that (E-1) was used for the intermediate resin layer and E ′ was used for the outermost layer.
- ⁇ Tensile modulus> The pressure-sensitive adhesive sheets 1 to 21 produced in the examples and comparative examples were cut into a width of 20 mm and a length of 80 mm, and this was pasted on a paper pattern (60 mm ⁇ 80 mm, the central part being a window part) as shown in FIG. After the upper and lower sides of the pattern paper are chucked by a tensile tester ("205 type tester” manufactured by Intesco), as shown in FIGS. 1 (B) and 1 (C), diagonal cuts are made on both sides of the pattern paper. The upper and lower sides of the pattern paper were divided, and a tensile test was performed at a distance between chucks of 40 mm and a tensile speed of 300 mm / min.
- reference numeral 1 denotes a paper pattern
- reference numeral 2 denotes an adhesive sheet.
- MPa tensile elasticity modulus
- the sticking area of the transparent double-sided PSA sheet and the SUS (stainless steel) plate is 25 mm ⁇ 20 mm.
- the test piece was cured for 15 minutes in an atmosphere of 40 ° C., then a 4.9 N weight was vertically attached to the test piece and allowed to stand for 30 minutes, and then the SUS (stainless steel) plate, the test piece, The misalignment length (mm) at which the sticking position was shifted downward was measured. The measurement results are shown in Table 3.
- ⁇ Printing step tracking test> An evaluation glass having a printing step of 40 ⁇ m on the peripheral edge of a 60 mm ⁇ 90 mm ⁇ 0.5 mm thick soda lime glass with a black printing (total light transmittance of 0%) having a width of 10 mm and a thickness of 40 ⁇ m. A substrate was produced.
- This glass substrate for evaluation is a substitute for an image display device constituent member having a stepped portion having a height of 30 ⁇ m to 50 ⁇ m and a flat surface portion on the bonding surface.
- a polarizing plate (“NWF-KDSEGHC-ST22” manufactured by Nitto Denko Corporation) as an image display device constituent member is previously placed on a glass plate (60 ⁇ 90 mm ⁇ What was bonded to the whole surface on one side (t0.5 mm) was produced.
- One release film of the pressure-sensitive adhesive sheets 1 to 21 cut by the processability evaluation was peeled off, and the exposed pressure-sensitive adhesive surface was stuck with a hand roller so as to cover the printing step portion of the glass substrate.
- the dynamic storage elastic modulus (G ′) at 20 ° C. is determined based on the active energy ray-curable pressure-sensitive adhesive sheets 1 to 10 and intermediate layers thereof (semi-cured intermediate layer forming sheets) and A plurality of outer layers (semi-cured outermost layer forming sheets) were used, laminated to a thickness of 1 mm to 2 mm, and punched into a circle with a diameter of 20 mm as a measurement sample. Seiki Co., Ltd.
- the dynamic storage modulus G ′ at 0 ° C. was measured. The measurement results are shown in Table 1.
- the dynamic storage elastic modulus (G ′) at 20 ° C. was measured in the same manner as described above. The measurement results are shown in Table 3.
- the dynamic storage elastic modulus (G ′) at 80 ° C. is determined by the intermediate layer (semi-cured intermediate layer forming sheet 4) and outermost layer of the active energy ray-curable pressure-sensitive adhesive sheet 4 obtained in Example 4.
- the semi-cured outermost layer forming sheet 4 is irradiated with ultraviolet rays so that the integrated light quantity at 365 nm is 2000 mJ or more, and the intermediate layer forming sheet 4 and the outermost layer forming sheet 4 after the ultraviolet irradiation. Were measured under the same conditions as above. The measurement results are shown in Table 2.
- ⁇ UV foam test> Preparation of UV irradiation test sample
- One release film of the pressure-sensitive adhesive sheets 1 to 21 prepared in Examples and Comparative Examples was peeled off and roll-bonded to soda lime glass having a size of 150 mm ⁇ 200 mm and a thickness of 1 mm.
- the remaining release film was peeled off, roll-bonded to a glass plate of 238 mm ⁇ 182 mm ⁇ thickness 0.8 mm, and subjected to autoclaving (80 ° C., gauge pressure 0.2 MPa, 20 minutes) and finished and bonded.
- ultraviolet rays were irradiated with a high-pressure mercury lamp so that ultraviolet rays having a wavelength of 365 nm reached the adhesive sheet at 2000 mJ / cm 2 , and the adhesive sheet was cured to produce a laminate.
- the active energy ray-curable pressure-sensitive adhesive sheet for optical members of the present invention is formed using a specific acrylic resin (A) so as to have a specific property, thereby reducing the dielectric constant and excellent printing step absorbability.
- A acrylic resin
- it is preferably used when forming an image display device such as a personal computer, a mobile terminal (PDA), a game machine, a television (TV), a car navigation system, a touch panel, a pen tablet, etc. Can do.
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Abstract
Description
また、粘着シートを被着体に貼り合わせた後に紫外線架橋を行うことにより、信頼性の高い接着が実現可能となる。これにより、被着体を含む積層体の厚みを薄く抑えることができると共に、空隙や液晶の色ムラなどの欠陥がない貼り合わせが可能となる。
加えて、上記特許文献3の粘着シートは、誘電率の低減化については考慮されていない。
(1)温度23℃における引張弾性率が0.03MPa以上
(2)25mm×20mmの貼着面積でステンレス板に貼り付け、500gf(4.9N)の荷重を鉛直方向に30分間加える保持力試験によるズレ長さが1mm以上
(3)周波数100kHzにおける比誘電率が3.7以下
また、それでいて粘着シートとしての取扱い性(例えば、カット性・リワーク性・保管性)にも優れるので、例えば、パーソナルコンピュータ、モバイル端末(PDA)、ゲーム機、テレビ(TV)、カーナビゲーションシステム、タッチパネル、ペンタブレットなどのような画像表示装置を形成する際に好適に用いることができる。
また、「シート」とは、シート、フィルム、テープを概念的に包含するものである。
本発明の光学部材用活性エネルギー線硬化型粘着シート(以下「本粘着シート」とも称する。)は、アクリル系樹脂(A)を含み、該アクリル系樹脂(A)は、活性エネルギー線架橋性構造部位を有し、かつ、炭素数10~24の直鎖アルキル基を有する(メタ)アクリル酸エステルモノマー(a)を含むモノマー成分の(共)重合体である。
(2)幅25mm×長さ20mmの貼着面積でステンレス板に貼り付け、500gf(4.9N)の荷重を鉛直方向に30分間加える保持力試験によるズレ長さが1mm以上
(3)周波数100kHzにおける比誘電率が3.7以下
本粘着シートは、温度23℃における引張弾性率が0.03MPa以上である。引張弾性率を、このような範囲内とすることで、優れた取扱い性を確保することができる。かかる観点から、本粘着シートの引張弾性率は0.03MPa以上1.0MPa以下であることが好ましく、0.03MPa以上0.5MPa以下であることがより好ましい。
本粘着シートは、上記保持力試験によるズレ長さが1mm以上である。ズレ長さが1mm以上であることにより、印刷段差吸収性を有することができる。かかる観点から、本粘着シートの前記ズレ長さは1.0mm以上20mm以下であることが好ましい。なお、保持力試験より求められるズレ長さは、後述する実施例に記載の方法で求められる値である。
このように、本粘着シートは、特定のアクリル系樹脂(A)を用いることで、低誘電率化を実現しつつ、柔軟でありながらカット性等の取扱い性に優れ、印刷段差吸収性と取扱い性という、相反する性質を有することができる。
より具体的には、上記特性(1)~(3)を有しつつ、後述するような積層構成の粘着シート設計とすることにより、より高い印刷段差吸収性と取扱い性を有することができる。
但し、n及びiは各々独立して2以上の整数である。
上記積層構成の本粘着シートは、n層以上の層が積層した構成を有し、具体的には、第1番目の層/第2番目の層、第1番目の層/第2番目の層/第3番目の層、第1番目の層/第2番目の層/・・・/第i番目の層を有する積層構成が挙げられる。なお、全ての層が粘着剤層である必要はないが、少なくとも第1番目(表層)及び/又は第n番目の層(裏層)は粘着剤層であることが好ましい。
本粘着シートの厚みは、20μm~500μmの範囲(基材シートを有する場合はその厚みを除く。)にあることが好ましい。例えば、厚さ20μm以上あれば、被着体との密着力や衝撃吸収性を妨げることが無く、500μm以下であれば、薄肉化の要求にこたえることができる。
したがって、本粘着シートの厚みは20μm~500μmであるのが好ましく、中でも30μm以上或いは300μm以下、その中でも50μm以上或いは200μm以下であるのがさらに好ましい。
また、凹凸や屈曲した面への追随性に劣ることがなく、被着体への接着力や濡れ性を維持することができ、好ましい。
かかる観点から、表裏層の総厚み(S1)に対する第i番目の層の厚み(S2)比率は、0.1≦(S1)/(S2)≦2であることがより好ましく、0.1≦(S1)/(S2)≦1であることがさらに好ましい。
本粘着シートは、周波数100kHzにおける比誘電率が3.7以下であることが好ましい。比誘電率が3.7以下であることにより、本粘着シートが絶縁層としての機能を果たし、タッチ信号のような高周波の電気信号の損失を低減することができる。このような点から、本粘着シートの比誘電率は3.5以下がより好ましく、3.2以下であることがより好ましい。なお、比誘電率は、後述する実施例に記載の方法で求められる値である。
本粘着シートは、アクリル系樹脂(A)を含有する。
なお、該活性エネルギー線架橋性構造部位とは、活性エネルギー線の照射により、アクリル系樹脂(A)の一部分、又は、アクリル系樹脂(A)以外の硬化成分と反応し、架橋構造を形成し得る構造部位である。
これらは単独で用いてもよいし2種以上を併用してもよい。
なお、炭素数10~24の直鎖アルキル基を有する(メタ)アクリル酸エステルモノマーであって、水酸基を含有するモノマーは、下記(b)として扱うものとする。
上記アクリル系樹脂(A)は、耐湿熱白化性が向上の点から、上記(a)以外のモノマー成分として、さらに、水酸基含有(メタ)アクリル酸エステルモノマー(b)を含むモノマー成分の共重合体であることが好ましい。
これらは単独で用いてもよいし2種以上を併用してもよい。
前記範囲内とすることにより、熱安定性の低下や、粘着シートとした際の金属系被着体の腐食が進行する虞がない。
このようにアクリル系樹脂(A)中の遊離酸の含有量を少なくするためには、水酸基含有(メタ)アクリル酸エステルモノマー(b)中に含有する遊離酸を少なくすればよく、その含有量は、1.0%以下が好ましく、特に好ましくは0.5%以下、更に好ましくは0.1%以下である。
なお、分岐鎖含有アルキル基を有する(メタ)アクリル酸アルキルエステルモノマーが水酸基を有するものである場合は、水酸基を含有する(メタ)アクリル酸エステルモノマー(b)として扱うものとする。
中でも、分岐鎖含有アルキル基を有する(メタ)アクリル酸アルキルエステルモノマーとして、iso-ブチル(メタ)アクリレート、2-エチルヘキシル(メタ)アクリレート、tert-ブチル(メタ)アクリレートを用いることが好ましく、特に好ましくは、2-エチルヘキシル(メタ)アクリレート又はtert-ブチル(メタ)アクリレートである。
これらは単独で用いてもよいし2種以上を併用してもよい。
なお、耐金属腐食性の観点から、上記アクリル系樹脂(A)は、カルボキシル基等の酸成分を含まないことが好ましい。
まず、有機溶媒中に、共重合成分、重合開始剤を混合あるいは滴下し、溶液重合してアクリル系樹脂(A)溶液を得る。
上記重合反応に用いられる有機溶媒としては、例えば、トルエン、キシレン等の芳香族炭化水素類、ヘキサン等の脂肪族炭化水素類、酢酸エチル、酢酸ブチル等のエステル類、N-プロピルアルコール、イソプロピルアルコール等の脂肪族アルコール類、アセトン、メチルエチルケトン、メチルイソブチルケトン、シクロヘキサノン等のケトン類等が挙げられる。これらの溶媒の中でも、溶液重合により得られるアクリル系樹脂溶液から溶媒を留去して、無溶媒型のアクリル系樹脂を効率よく製造できる点で、沸点が70℃以下である溶媒を用いることが好ましい。
なお、上記各有機溶媒名に続いて記載された( )内の数値は沸点である。
上記重合反応に用いられる重合開始剤としては、通常のラジカル重合開始剤であるアゾ系重合開始剤や過酸化物系重合開始剤等を用いることができ、アゾ系重合開始剤としては、例えば、2,2'-アゾビス(2-メチルブチロニトリル)、2,2'-アゾビスイソブチロニトリル、(1-フェニルエチル)アゾジフェニルメタン、2,2'-アゾビス(2,4-ジメチルバレロニトリル)、2,2'-アゾビス(2-シクロプロピルプロピオニトリル)、2,2'-アゾビス(4-メトキシ-2,4-ジメチルバレロニトリル)等が挙げられ、過酸化物系重合開始剤としては、例えば、ベンゾイルパーオキサイド、ジ-t-ブチルパーオキサイド、クメンハイドロパーオキサイド、ラウロイルパーオキサイド、t-ブチルペルオキシピバレート、t-ヘキシルペルオキシピバレート、t-ヘキシルペルオキシネオデカノエート、ジイソプロピルペルオキシカーボネート、ジイソブチリルペルオキシド等が挙げられる。
これらは単独で用いるか、又は2種以上を併用することができる。
この際に10時間半減期温度が高い重合開始剤を使用すると、重合開始剤が残存しやすくなり、重合開始剤が残存すると、後述の、アクリル系樹脂(A)溶液から溶媒を留去する工程においてアクリル系樹脂のゲル化が発生する傾向がある。
なお、上記各化合物名に続いて記載された( )内の数値は各化合物の10時間半減期温度である。
溶液重合の重合条件については、従来公知の重合条件に従って重合すればよく、例えば、溶媒中に、(メタ)アクリル系モノマーを含有する重合成分、重合開始剤を混合或いは滴下し所定の重合条件にて重合することができる。
なお、重合反応は、除熱がしやすい点で溶媒を還流しながら行うことが好ましい。
次いで得られたアクリル系樹脂(A)溶液から溶媒を留去する。
アクリル系樹脂(A)溶液から溶媒を留去する工程は、公知一般の方法で行うことができ、溶媒を留去する方法としては、加熱することにより溶媒を留去する方法や、減圧することにより溶媒を留去する方法等があるが、溶媒の留去を効率的に行う点から、減圧下で加熱することにより留去する方法が好ましい。
かくしてアクリル系樹脂(A)を製造することができる。
前記範囲内とすることにより、粘度が高くなりすぎて、塗工性やハンドリングが低下したり、凝集力が低下し、耐久性が低下したりする虞がない。
なお、上記アクリル系樹脂(A)の重量平均分子量は、製造完了時の重量平均分子量であり、製造後に加熱等がされていないアクリル系樹脂(A)の重量平均分子量である。
また、段差追従性や粘着力が低下したり、熱耐久性が低下したりする虞もない。
Tga:モノマーAのホモポリマーのガラス転移温度(K) Wa:モノマーAの重量分率 Tgb:モノマーBのホモポリマーのガラス転移温度(K) Wb:モノマーBの重量分率 Tgn:モノマーNのホモポリマーのガラス転移温度(K) Wn:モノマーNの重量分率(Wa+Wb+・・・+Wn=1)
本粘着シートは、粘着シートとしての取扱い性(例えば、カット性・リワーク性・保管性)向上のための高凝集力化という点で、上記アクリル系樹脂(A)以外に架橋剤(B)を含有する組成物から形成してもよい。
なお、前記架橋性官能基は、脱保護可能な保護基で保護されていてもよい。
本粘着シートは、アクリル系樹脂(A)を含有するが、活性エネルギー線照射時の反応を安定化させることができる点で、アクリル系樹脂(A)以外に光重合開始剤(C)を含有する組成物から形成してもよい。
これらは単独で用いてもよいし、2種以上併用してもよい。
本粘着シートは、上記以外にも、通常の粘着組成物に配合されている公知の成分を含有する組成物から形成してもよい。例えば、粘着付与樹脂や、加工助剤(オイル成分など)、シランカップリング剤、酸化防止剤、光安定化剤、金属不活性化剤、紫外線吸収剤(UVA)、光安定剤(HALS)、防錆剤、老化防止剤、吸湿剤、加水分解防止剤、造核剤などの各種の添加剤を適宜含有させることが可能である。無機系もしくは有機系のナノ微粒子などもこれに含まれる。
これらの中でも、防錆剤や粘着付与剤を含むことがより好ましい。
また、必要に応じて反応触媒(三級アミン系化合物、四級アンモニウム系化合物、ラウリル酸スズ化合物など)を、必要に応じて適宜含有してもよい。
本粘着シートは、上述したアクリル系樹脂(A)並びに必要に応じて架橋剤(B)及び光重合開始剤(C)を含有する樹脂組成物を、熱により溶融した状態で基材シート又は離型シート上に塗布(塗工)し、その後冷却することで製造することができる。
また、例えば、積層構成の本粘着シートは、前記樹脂組成物を、熱により溶融した状態で基材シート又は離型シート上に塗布(塗工)し、その後冷却して、第1番目の層を形成し、形成した第1番目の層上に該樹脂組成物を塗布(塗工)し、その後冷却して、第2番目の層を形成することを繰り返し、第i番目の層を形成する方法や、該樹脂組成物を加熱により溶融し、前記と同様にして、第1番目から第i番目までの層を形成しておき、その後、それぞれの塗布(塗工)面同士を貼り合せる方法や、該樹脂組成物を加熱により溶融し、共押出成型により第1番目の層から第i番目の層を同時に形成する方法により作製することができる。
本粘着シートは、被着部材への貼合後に、活性ネルギー線を照射して、使用することが好ましい。
したがって、本粘着シートは、365nmの積算光量が2000mJ以上となるように活性エネルギー線を照射した場合、照射前後において、第1番目の層は、周波数1Hz、温度80℃における貯蔵弾性率G’の差(照射後の貯蔵弾性率G’-照射前の貯蔵弾性率G’)が5kPa以上となり、かつ、第i番目の層は、周波数1Hz、温度80℃における貯蔵弾性率G’の差(照射後の貯蔵弾性率G’-照射前の貯蔵弾性率G’)が2kPa以上となることが好ましい。
なお、上記貯蔵弾性率G’は上述した方法により調節することができる。
本粘着シートは、光学部材用、例えば、画像表示装置構成部材の貼合に用いることができる。画像表示装置構成部材としては、例えば、パソコン、モバイル端末(PDA)、ゲーム機、テレビ(TV)、カーナビ、タッチパネル、ペンタブレット等、LCD、PDP又はEL等の画像表示装置の構成部材を挙げることができる。
ラウリルメタクリレートとトリデシルメタクリレートの混合物(SLMA)58.5質量部と、2-エチルヘキシルメタクリレート(2EHMA)15質量部と、n-ステアリルメタクリレート(SMA)15質量部と、4-ヒドロキシブチルアクリレート(4HBA)11質量部と、4-メタクリロイルオキシベンゾフェノン(MBP)0.5質量部をランダム共重合してなるアクリル系樹脂Aを用意した。
このアクリル系樹脂A 1kgに、架橋剤としての紫外線硬化樹脂プロポキシ化ペンタエリスリトールトリアクリレート(新中村化学社製「ATM-4PL」)50gを溶融混錬して中間樹脂層用組成物(A-1)を調製した。
前記組成物(A-1)を、2枚の離型フィルム、すなわち剥離処理された2枚のポリエチレンテレフタレートフィルム(三菱ケミカル社製「ダイアホイルMRV-V06」、厚さ100μm/三菱ケミカル社製「ダイアホイルMRQ」、厚さ75μm)で挟み、ラミネータを用い、温度80℃で厚さ90μmとなるようシート状に賦形し、中間層形成用積層シート1(中間樹脂層(A-1)の厚さ90μm)を作製した。
ラウリルメタクリレートとトリデシルメタクリレートの混合物(SLMA)44.5質量部と、2-エチルヘキシルメタクリレート(2EHMA)10質量部と、n-ステアリルメタクリレート(SMA)35質量部と、4-ヒドロキシブチルアクリレート(4HBA)10質量部と、4-メタクリロイルオキシベンゾフェノン(MBP)0.5質量部をランダム共重合してなるアクリル系樹脂Bを用意した。
このアクリル系樹脂B 1kgに、架橋剤としての紫外線硬化樹脂プロポキシ化ペンタエリスリトールトリアクリレート(新中村化学社製「ATM-4PL」)50gを溶融混錬して中間樹脂層用組成物(B-1)を調製した。
前記組成物(B-1)を、2枚の離型フィルム、すなわち剥離処理された2枚のポリエチレンテレフタレートフィルム(三菱ケミカル社製「ダイアホイルMRV-V06」、厚さ100μm/三菱ケミカル社製「ダイアホイルMRQ」、厚さ75μm)で挟み、ラミネータを用い、温度80℃で厚さ90μmとなるようシート状に賦形し、中間層形成用積層シート2(中間樹脂層(B-1)の厚さ90μm)を作製した。
ラウリルメタクリレートとトリデシルメタクリレートの混合物(SLMA)52.5質量部と、2-エチルヘキシルメタクリレート(2EHMA)20質量部と、n-ステアリルメタクリレート(SMA)15質量部と、2-ヒドロキシエチルアクリレート(2HEA)12質量部と、4-メタクリロイルオキシベンゾフェノン(MBP)0.5質量部をランダム共重合してなるアクリル系樹脂Cを用意した。
このアクリル系樹脂C 1kgに、架橋剤としての紫外線硬化樹脂プロポキシ化ペンタエリスリトールトリアクリレート(新中村化学社製「ATM-4PL」)50gを溶融混錬して中間樹脂層用組成物(C-1)を調製した。
前記組成物(C-1)を、2枚の離型フィルム、すなわち剥離処理された2枚のポリエチレンテレフタレートフィルム(三菱ケミカル社製「ダイアホイルMRV-V06」、厚さ100μm/三菱ケミカル社製「ダイアホイルMRQ」、厚さ75μm)で挟み、ラミネータを用い、温度80℃で厚さ90μmとなるようシート状に賦形し、中間層形成用積層シート3(中間樹脂層(C-1)の厚さ90μm)を作製した。
ラウリルメタクリレートとトリデシルメタクリレートの混合物(SLMA)82.6質量部と、t-ブチルメタクリレート(tBMA)5質量部と、4-ヒドロキシブチルアクリレート(4HBA)12質量部と、4-メタクリロイルオキシベンゾフェノン(MBP)0.5質量部をランダム共重合してなるアクリル系樹脂Dを用意した。
このアクリル系樹脂D 1kgに、架橋剤としての紫外線硬化樹脂プロポキシ化ペンタエリスリトールトリアクリレート(新中村化学社製「ATM-4PL」)50gを溶融混錬して中間樹脂層用組成物(D-1)を調製した。
前記組成物(D-1)を、2枚の離型フィルム、すなわち剥離処理された2枚のポリエチレンテレフタレートフィルム(三菱ケミカル社製「ダイアホイルMRV-V06」、厚さ100μm/三菱ケミカル社製「ダイアホイルMRQ」、厚さ75μm)で挟み、ラミネータを用い、温度80℃で厚さ90μmとなるようシート状に賦形し、中間層形成用積層シート4(中間樹脂層(D-1)の厚さ90μm)を作製した。
2-エチルヘキシルアクリレート(2EHA)77質量部と、酢酸ビニル(VA)19質量部と、アクリル酸(AA)4質量部をランダム共重合してなるアクリル系樹脂Eを用意した。
このアクリル系樹脂E 1kgに、架橋剤としての紫外線硬化樹脂プロポキシ化ペンタエリスリトールトリアクリレート(新中村化学社製「ATM-4PL」)50gと光開始剤としての2,4,6-トリメチルベンゾフェノン及び4-メチルベンゾフェノンの混合物(Lanberti社製「エザキュアTZT」)15gを溶融混錬して中間樹脂層用組成物(E-1)を調製した。
前記組成物(E-1)を、2枚の離型フィルム、すなわち剥離処理された2枚のポリエチレンテレフタレートフィルム(三菱ケミカル社製「ダイアホイルMRV-V06」、厚さ100μm/三菱ケミカル社製「ダイアホイルMRQ」、厚さ75μm)で挟み、ラミネータを用い、温度80℃で厚さ90μmとなるようシート状に賦形し、中間層形成用積層シート5(中間樹脂層(E-1)の厚さ90μm)を作製した。
前記アクリル系樹脂Aを2枚の離型フィルム、すなわち剥離処理された2枚のポリエチレンテレフタレートフィルム(三菱ケミカル社製「ダイアホイルMRV-V06」、厚さ100μm/三菱ケミカル社製「ダイアホイルMRQ」、厚さ75μm)で挟み、ラミネータを用いて厚さ30μmとなるようシート状に賦形し、最外層形成用積層シート1(粘着剤層Aの厚さ30μm)を作製した。
前記アクリル系樹脂Bを2枚の離型フィルム、すなわち剥離処理された2枚のポリエチレンテレフタレートフィルム(三菱ケミカル社製「ダイアホイルMRV-V06」、厚さ100μm/三菱ケミカル社製「ダイアホイルMRQ」、厚さ75μm)で挟み、ラミネータを用い、温度80℃で厚さ30μmとなるようシート状に賦形し、最外層形成用積層シート2(粘着剤層Bの厚さ30μm)を作製した。
前記アクリル系樹脂Cを2枚の離型フィルム、すなわち剥離処理された2枚のポリエチレンテレフタレートフィルム(三菱ケミカル社製「ダイアホイルMRV-V06」、厚さ100μm/三菱ケミカル社製「ダイアホイルMRQ」、厚さ75μm)で挟み、ラミネータを用い、温度80℃で厚さ30μmとなるようシート状に賦形し、最外層形成用積層シート3(粘着剤層Cの厚さ30μm)を作製した。
前記アクリル系樹脂Dを2枚の離型フィルム、すなわち剥離処理された2枚のポリエチレンテレフタレートフィルム(三菱ケミカル社製「ダイアホイルMRV-V06」、厚さ100μm/三菱ケミカル社製「ダイアホイルMRQ」、厚さ75μm)で挟み、ラミネータを用い、温度80℃で厚さ30μmとなるようシート状に賦形し、最外層形成用積層シート4(粘着剤層Dの厚さ30μm)を作製した。
前記アクリル系樹脂E 1kgに、光開始剤としての2,4,6-トリメチルベンゾフェノン及び4-メチルベンゾフェノンの混合物(Lanberti社製「エザキュアTZT」)15gを溶融混錬した最外樹脂層用組成物E′を2枚の離型フィルム、すなわち剥離処理された2枚のポリエチレンテレフタレートフィルム(三菱ケミカル社製「ダイアホイルMRV-V06」、厚さ100μm/三菱ケミカル社製「ダイアホイルMRQ」、厚さ75μm)で挟み、ラミネータを用い、温度80℃で厚さ30μmとなるようシート状に賦形し、最外層形成用積層シート5(粘着剤層Eの厚さ30μm)を作製した。
中間樹脂層形成用積層シート1における中間樹脂層(A-1)の両側のPETフィルムを順次剥離除去すると共に、最外層形成用積層シート1における粘着剤層Aの一側のPETフィルムを剥がして、露出した粘着面を(A-1)の両表面にラミネータにて順次貼合し、A/(A-1)/Aからなる多層粘着シートを作製した。
積層後、表面に残るポリエチレンテレフタレートフィルムを介して、365nmの積算光量が500mJとなるよう高圧水銀ランプにて紫外線を照射し、Aおよび(A-1)を紫外線架橋させて、粘着シート1(総厚み150μm)を作製した。
なお、粘着シート1は、紫外線の照射量を調節して、半硬化状態、すなわち、さらに硬化できる余地を残した状態のものである。
中間樹脂層に(B-1)、最外層にBを用いた以外は、実施例1と同様の方法により粘着シート2を作製した。
中間樹脂層に(C-1)、最外層にCを用いた以外は、実施例1と同様の方法により粘着シート3を作製した。
中間樹脂層に(D-1)、最外層にDを用いた以外は、実施例1と同様の方法により粘着シート4を作製した。
中間樹脂層に(A-1)、最外層にBを用いた以外は、実施例1と同様の方法により粘着シート5を作製した。
中間樹脂層に(B-1)、最外層にAを用いた以外は、実施例1と同様の方法により粘着シート6を作製した。
中間樹脂層に(C-1)、最外層にAを用いた以外は、実施例1と同様の方法により粘着シート7を作製した。
中間樹脂層に(A-1)、最外層にCを用いた以外は、実施例1と同様の方法により粘着シート8を作製した。
中間樹脂層に(B-1)、最外層にCを用いた以外は、実施例1と同様の方法により粘着シート9を作製した。
中間樹脂層に(C-1)、最外層にBを用いた以外は、実施例1と同様の方法により粘着シート10を作製した。
前記組成物(A-1)を、2枚の離型フィルムすなわち剥離処理された2枚のポリエチレンテレフタレートフィルム(三菱ケミカル社製「ダイアホイルMRV-V06」、厚さ100μm/三菱ケミカル社製「ダイアホイルMRQ」、厚さ75μm)で挟み、ラミネータを用いて厚さ150μmとなるようシート状に賦形し、粘着シート11を作製した。
組成物(A-1)のかわりに組成物(B-1)を用いた以外は、比較例1と同様の方法により粘着シート12を作製した。
組成物(A-1)のかわりに組成物(C-1)を用いた以外は、比較例1と同様の方法により粘着シート13を作製した。
組成物(A-1)のかわりに組成物(D-1)を用いた以外は、比較例1と同様の方法により粘着シート14を作製した。
組成物(A-1)のかわりにアクリル系樹脂Aを用いた以外は、比較例1と同様の方法により粘着シート15を作製した。
組成物(A-1)のかわりにアクリル系樹脂Bを用いた以外は、比較例1と同様の方法により粘着シート16を作製した。
組成物(A-1)のかわりにアクリル系樹脂Cを用いた以外は、比較例1と同様の方法により粘着シート17を作製した。
組成物(A-1)のかわりにアクリル系樹脂Dを用いた以外は、比較例1と同様の方法により粘着シート18を作製した。
組成物(A-1)のかわりに組成物E′を用いた以外は、比較例1と同様の方法により粘着シート19を作製した。
組成物(A-1)のかわりに組成物(E-1)を用いた以外は、比較例1と同様の方法により粘着シート20を作製した。
中間樹脂層に(E-1)、最外層にE′を用いた以外は、実施例1と同様の方法により粘着シート21を作製した。
実施例及び比較例で作製した粘着シート1~21を、幅20mm、長さ80mmに切り出し、これを図1(A)に示すような型紙(60mm×80mm、中央部は窓部)に貼り付け、引張試験機(インテスコ社製「205型試験機」)に型紙上下をチャックした後、図1(B)及び図1(C)に示すように、型紙の両横に斜めに切り込みを入れて型紙の上下を分断し、チャック間距離40mm、引張速度300mm/minで引張試験を行った。図1中の符号1は型紙、符号2は粘着シートである。そして、引張弾性率(MPa)を算出した。算出結果は表3に示した。
実施例及び比較例で作製した粘着シート1~21を、トムソン打抜機を用いて50mm×80mmのトムソン刃でカットし、裁断したシート端部の形状を目視で観察した。そして、シート端部に糊のはみだしがあるものを「×」、なきものを「○」と判定した。判定結果は表3に示した。
実施例及び比較例で作製した粘着シート1~21を、30mm×80mmに裁断した後、片面の剥離フィルムを剥がし、該粘着シートの片面が、裏打用のポリエチレンテレフタレートフィルム(厚さ38μm)に重なるようにハンドローラで貼着し、これを25mm×80mmの短冊状に裁断して試験片とした。
次に、残る剥離フィルムを剥がして、垂直に立設したSUS(ステンレス)板(120mm×50mm×厚さ1.2mm)に対して、試験片が20mmの長さだけ重なるようにしてハンドローラで貼着した。この時、透明両面粘着シートとSUS(ステンレス)板の貼着面積は25mm×20mmとなる。
その後、試験片を40℃の雰囲気下で15分養生させた後、試験片に4.9Nの錘を垂直方向に取り付けて掛けて30分間静置した後、SUS(ステンレス)板と試験片との貼着位置が下方にずれたズレ長さ(mm)を測定した。測定結果は表3に示した。
60mm×90mm×厚さ0.5mmのソーダライムガラスの周縁部に、幅10mm、厚み40μmの黒色の印刷(全光線透過率0%)を施し、周縁部に40μmの印刷段差をもつ評価用ガラス基板を作製した。この評価用ガラス基板は、高さ30μm~50μmの段差部、及び、平坦面部を貼合面に有する画像表示装置構成部材の代替品である。
この評価用ガラス基板に貼合する試験用被着体として、画像表示装置構成部材としての偏光板(日東電工株式会社製「NWF-KDSEGHC-ST22」)を、予めガラス板上(60×90mm×t0.5mm)の片面に全面貼合したものを作製した。
前記加工性評価にて裁断した粘着シート1~21の一方の剥離フィルムを剥がし、露出した粘着面を上記ガラス基板の印刷段差部を覆うようにハンドローラにて貼着した。次いで、残る剥離フィルムを剥がし、露出した粘着面に未処理のソーダライムガラスを減圧下(絶対圧5kPa)にてプレス貼合した後、オートクレーブ処理(60℃、0.2MPa、20分)を施して仕上貼着し、印刷段差追随性評価用積層体を作製した。
前記印刷段差追随性評価用積層体を、常態(温度23℃湿度50%)で一日静置した後、外観を目視観察し、印刷段差付近に粘着シートの浮きもしくは剥離が発生したものを「×」と評価し、浮きもしくは剥離が無かったものを「○」と評価した。評価結果は表3に示した。
実施例及び比較例で作製した粘着シート1~21を、直径25mmの円状に切り出し、LCRメータ(キーサイト・テクノロジー社製)の測定部に両面の剥離フィルムを剥がした状態で貼合し、23℃50%RHで、印加電圧1V、周波数100kHzにおける比誘電率を測定した。測定結果は表3に示した。
20℃における動的貯蔵弾性率(G’)は、実施例で得られた、活性エネルギー線硬化型の粘着シート1~10並びにこれらの中間層(半硬化状態の中間層形成用シート)及び最外層(半硬化状態の最外層形成用シート)を、それぞれ複数枚使用して、1mm~2mmの厚みになるように積層し、直径20mmの円状に打ち抜いたものを測定試料とし、レオメータ(英弘精機株式会社製「MARS」)を用いて、粘着治具:Φ20mmパラレルプレート、歪み:0.5%、周波数:1Hz、温度:-50~200℃、昇温速度:3℃/minで、20℃における動的貯蔵弾性率G’を測定した。測定結果は表1に示した。
また、粘着シート11~21についても、前記と同様にして、20℃の動的貯蔵弾性率(G‘)を測定した。測定結果は表3に示した。
また、80℃における動的貯蔵弾性率(G’)は、実施例4で得られた活性エネルギー線硬化型の粘着シート4の中間層(半硬化状態の中間層形成用シート4)及び最外層(半硬化状態の最外層形成用シート4)に対して、365nmの積算光量が2000mJ以上となるように紫外線を照射して、紫外線照射後の中間層形成用シート4及び最外層形成用シート4を作製し、それぞれについて上記と同様の条件で測定した。測定結果は表2に記載した。
(UV照射試験試料の作製)
実施例及び比較例で作製した粘着シート1~21の一方の離型フィルムを剥がし、150mm×200mm厚さ1mmのソーダライムガラスにロール貼合した。次いで、残る離型フィルムを剥がし、238mm×182mm×厚さ0.8mmのガラス板にロール貼合し、オートクレーブ処理(80℃、ゲージ圧0.2MPa、20分)を施して仕上げ貼着した。
0.8mm厚のガラス側から、波長365nmの紫外線が粘着シートに2000mJ/cm2到達するよう高圧水銀ランプにて紫外線を照射し、粘着シートを硬化させて、積層体を作製した。
上記積層体を、キセノンUV照射装置(サンテストCPS:東洋精機製)に入れ、照度765W/m2、温度60℃で24時間UV照射処理を施した後の外観を観察した。粘着シートに直径5mm以上の気泡が発生したものを「×(poor)」、直径5mm以下の気泡がみられたものを「△(usual)」、発泡なく、外観変化がなかったものを「○(good)」と判定した。
2 粘着シート
Claims (10)
- アクリル系樹脂(A)を含有する活性エネルギー線硬化型粘着シートであって、
前記アクリル系樹脂(A)は、活性エネルギー線架橋性構造部位を有し、かつ、炭素数10~24の直鎖アルキル基を有する(メタ)アクリル酸エステルモノマー(a)を含むモノマー成分の(共)重合体であり、
少なくとも次の(1)~(3)の全ての特性を有する、光学部材用活性エネルギー線硬化型粘着シート。
(1)温度23℃における引張弾性率が0.03MPa以上
(2)25mm×20mmの貼着面積でステンレス板に貼り付け、500gf(4.9N)の荷重を鉛直方向に30分間加える保持力試験によるズレ長さが1mm以上
(3)周波数100kHzにおける比誘電率が3.7以下 - アクリル系樹脂(A)を含有する活性エネルギー線硬化型粘着シートであって、
前記アクリル系樹脂(A)は、活性エネルギー線架橋性構造部位を有し、かつ、炭素数10~24の直鎖アルキル基を有する(メタ)アクリル酸エステルモノマー(a)を含むモノマー成分の(共)重合体であり、
少なくとも一方のシート表面から厚み方向に、周波数1Hz、温度20℃における貯蔵弾性率G’が異なる、前記アクリル系樹脂(A)を含む領域を有し、
周波数100kHzにおける比誘電率が3.7以下である、光学部材用活性エネルギー線硬化型粘着シート。 - 少なくとも一方のシート表面から厚み方向に、少なくともn個の層を有し、
第1番目の層及び第i番目の層の周波数1Hz、温度20℃における貯蔵弾性率G’は異なり、
前記第i番目の層は、周波数1Hz、温度20℃における貯蔵弾性率G’が、40kPa以上1MPa以下であることを特徴とする、請求項2記載の光学部材用活性エネルギー線硬化型粘着シート。
(但し、n及びiは各々独立して2以上の整数である。) - 前記第1番目の層は、周波数1Hz、温度20℃における貯蔵弾性率G’が、30kPa以上70kPa以下であることを特徴とする、請求項3記載の光学部材用活性エネルギー線硬化型粘着シート。
- 前記第i番目の層は、架橋剤(B)を含んでなる、請求項2~4の何れか一項記載の光学部材用活性エネルギー線硬化型粘着シート。
- 365nmの積算光量が2000mJ以上となるように活性エネルギー線を照射した場合、照射前後において、第1番目の層は、周波数1Hz、温度80℃における貯蔵弾性率G’の差(照射後の貯蔵弾性率G’-照射前の貯蔵弾性率G’)が5kPa以上となり、かつ、第i番目の層は、周波数1Hz、温度80℃における貯蔵弾性率G’の差(照射後の貯蔵弾性率G’-照射前の貯蔵弾性率G’)が2kPa以上となる、請求項3~5の何れか一項記載の光学部材用活性エネルギー線硬化型粘着シート。
- 前記活性エネルギー線架橋性構造部位が、ベンゾフェノン系架橋構造である、請求項1~6の何れか一項に記載の光学部材用活性エネルギー線硬化型粘着シート。
- 前記アクリル系樹脂(A)は、前記モノマー(a)以外に、さらに、水酸基含有(メタ)アクリル酸エステルモノマー(b)を含むモノマー成分の共重合体である、請求項1~7の何れか一項記載の光学部材用活性エネルギー線硬化型粘着シート。
- 前記アクリル系樹脂(A)は、前記モノマー(b)以外に、さらに、分岐鎖含有アルキル基を有する(メタ)アクリル酸アルキルエステルモノマー(c)を含むモノマー成分の共重合体である、請求項1~8の何れか一項記載の光学部材用活性エネルギー線硬化型粘着シート。
- 前記アクリル系樹脂(A)は、その共重合体中の前記モノマー(a)及び(c)の含有割合(重量比)が、100/0~70/30であることを特徴とする請求項9記載の光学部材用活性エネルギー線硬化型粘着シート。
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