Adhesive sheet with release film, laminate for image display device, and image display device

Abstract

To provide an adhesive sheet with a release film, a laminate for an image display device, and an image display device, that are free from generation of peeling traces, even when a release film with high surface resistivity (such as a release film lacking an antistatic layer) is employed.SOLUTION: An adhesive sheet with a release film has a structure in which a release film [F] whose surface resistivity is 1.0×1014 Ω / sq. or more and an adhesive sheet [I] are laminated, wherein the shear storage modulus (G') of the adhesive sheet [I] at 25°C is within a range of 6.0×104 Pa to 1.0×107 Pa.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a pressure-sensitive adhesive sheet with a release film, a laminate for an image display device, and an image display device. [Background technology]

[0002] In order to improve the visibility of image display devices, the gap between an image display panel such as a liquid crystal display (LCD), a plasma display (PDP), or an electroluminescence display (ELD) and a protective panel or touch panel member placed on the front side (viewing side) of the image display panel is filled with a resin such as an adhesive or glue to suppress reflection of incident light and outgoing light from the displayed image at the air layer interface.

[0003] For example, Patent Document 1 discloses a method for manufacturing a component laminate for an image display device, which has a configuration in which an image display device component is laminated on at least one side of a transparent double-sided adhesive sheet, in which an adhesive sheet that has been primarily crosslinked by ultraviolet light is attached to the image display device component, and then the adhesive sheet is irradiated with ultraviolet light through the image display device component to cause secondary curing.

[0004] Furthermore, Patent Document 2 discloses a pressure-sensitive adhesive sheet containing a (meth)acrylic copolymer having an ultraviolet-crosslinkable site, as an adhesive sheet useful for displays and touch panels.

[0005] Furthermore, a release film is usually laminated on the pressure-sensitive adhesive sheet. The release film laminated on the pressure-sensitive adhesive sheet used for bonding components of an image display device usually has an antistatic layer for the purpose of preventing adhesion of foreign matter due to static electricity. For example, Patent Documents 3 and 4 describe that the base film has an antistatic layer on at least one side, and it is common for an antistatic layer to be formed on the release film laminated to the pressure-sensitive adhesive sheet. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 4971529 [Patent Document 2] Patent No. 6062740 [Patent Document 3] Japanese Patent Application Laid-Open No. 2016-182767 [Patent Document 4] Japanese Patent Application Laid-Open No. 2016-188266 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in recent years, from the viewpoint of resource conservation and environmental friendliness, there has been an increasing demand for the use of release films that do not have an antistatic layer.

[0008] When a release film having a high surface resistance value, such as one that does not have an antistatic layer, is used, problems such as peeling marks due to peeling can occur on the surface of the adhesive sheet due to the influence of static electricity when the release film is peeled off from the adhesive sheet, and this tends to reduce productivity when manufacturing a laminate for an image display device by bonding components of the image display device. The term "peeling marks" as used herein refers to the phenomenon in which marks are left behind when the release film is peeled off from the adhesive sheet due to the surface of the adhesive sheet becoming rough.

[0009] Although Patent Documents 1 and 2 state that a release film is laminated on the adhesive sheet, they do not provide any details about the release film, and therefore do not take into consideration at all problems such as peeling marks that may occur when the release film is peeled off from the adhesive sheet.

[0010] Therefore, in this context, from the viewpoint of resource conservation and environmental friendliness, the present invention aims to provide an adhesive sheet with a release film, a laminate for an image display device, and an image display device that do not leave peeling marks even when a release film with a high surface resistance value (for example, a release film without an antistatic layer) is used. [Means for solving the problem]

[0011] In the present invention, as a result of extensive research conducted in light of these circumstances, it was discovered that even when a release film with a high surface resistance value (for example, a release film without an antistatic layer) is used, an adhesive sheet in which the shear storage modulus of the adhesive sheet has been adjusted to be relatively high, i.e., a relatively hard adhesive sheet, can be selected, and an adhesive sheet with a release film laminated with such a release film will become an adhesive sheet with a release film that does not leave any marks when the release film is peeled off, thereby completing the present invention. That is, the present invention has the following aspects. [1] Surface resistance is 1.0×10 14 A pressure-sensitive adhesive sheet with a release film having a configuration in which a release film [F] having a resistivity of Ω / □ or more and a pressure-sensitive adhesive sheet [I] are laminated together, The pressure-sensitive adhesive sheet [I] has a shear storage modulus (G') at 25°C of 6.0 × 10 4 ~1.0×10 7 Pa is an adhesive sheet with a release film. [2] The pressure-sensitive adhesive sheet with a release film according to [1], wherein the pressure-sensitive adhesive sheet [I] has an acrylic pressure-sensitive adhesive layer formed from a resin composition (i) containing an acrylic copolymer (A), a crosslinking agent (B), and a photopolymerization initiator (C). [3] The pressure-sensitive adhesive sheet with a release film according to [2], wherein the crosslinking agent (B) is a polyfunctional (meth)acrylate compound having two or more functional groups. [4] The pressure-sensitive adhesive sheet with a release film according to [2] or [3], wherein the photopolymerization initiator (C) comprises a hydrogen abstraction photopolymerization initiator (c1). [5] The pressure-sensitive adhesive sheet with a release film according to any one of [1] to [4], wherein the release film [F] is a release film that does not have an antistatic layer. [6] A laminate for an image display device, comprising two image display device components laminated together via the adhesive sheet [I] described in any one of [1] to [5], one of the two image display device components being a surface protection panel, and the other being a member consisting of one or a combination of two or more of the group consisting of a touch sensor, an image display panel, a color filter, a polarizing film, and a retardation film. [7] The laminate for an image display device according to [6], wherein the surface protection panel has a frame-shaped concealing portion on the periphery, and the frame has a portion with a width of 3 mm or less. [8] The laminate for an image display device according to [6], wherein the surface protection panel has a curved shape. [9] An image display device comprising the laminate for an image display device according to [6]. [Effects of the Invention]

[0012] From the viewpoint of resource conservation and environmental friendliness, the pressure-sensitive adhesive sheet with a release film of the present invention does not leave peel marks even when a release film with a high surface resistance value (for example, a release film without an antistatic layer) is used, and therefore is very useful as a pressure-sensitive adhesive sheet with a release film used in the manufacture of a laminate for an image display device and an image display device. DETAILED DESCRIPTION OF THE INVENTION

[0013] An example of an embodiment of the present invention will be described in detail below, but the present invention is not limited to the embodiment described below. In this specification, the term "film" conceptually encompasses sheets, films, and tapes. Furthermore, when the term "panel" is used, such as an image display panel or a protective panel, it encompasses a plate, a sheet, and a film.

[0014] In this specification, when it is written "x to y" (x and y are any numbers), unless otherwise specified, it means "greater than x and less than y", and also means "preferably greater than x" or "preferably smaller than y". Furthermore, when it is stated that the amount is "x or more" (x is any number), it also means that the amount is "preferably greater than x" unless otherwise specified, and when it is stated that the amount is "y or less" (y is any number), it also means that the amount is "preferably smaller than y" unless otherwise specified. Furthermore, "x and / or y (x and y are optional configurations)" means at least one of x and y, and can mean three possibilities: x only, y only, or x and y. In addition, with respect to the numerical ranges described in stages in this specification, the upper or lower limit of a numerical range in one stage can be arbitrarily combined with the upper or lower limit of a numerical range in another stage. Furthermore, in the numerical ranges described in this specification, the upper or lower limit of the numerical range can also be replaced with the values ​​shown in the examples.

[0015] In addition, in this specification, "(meth)acrylic" is a comprehensive term that includes acrylic and methacrylic, "(meth)acrylate" is a comprehensive term that includes acrylate and methacrylate, and "(meth)acryloyl" is a comprehensive term that includes acryloyl and methacryloyl. Furthermore, in this specification, the term "main component" refers to a component that has a significant effect on the properties of the material, and the content of the component is usually 50% by mass or more of the entire material, preferably 70% by mass or more, and particularly preferably 90% by mass or more.

[0016] An adhesive sheet with a release film according to one embodiment of the present invention (hereinafter sometimes referred to as "the adhesive sheet with a release film") is formed by laminating a release film [F] and an adhesive sheet [I], and the release film [F] may be laminated on one side or both sides of the adhesive sheet [I], and in particular, a double-sided adhesive sheet with a release film in which the adhesive sheet [I] is sandwiched between release films [F], forming a laminate of release film [F] / adhesive sheet [I] / release film [F] is preferred. In addition, the double-sided adhesive sheet with release film typically has different adhesive strengths to the adhesive sheet between one release film and the other release film, and is used by first peeling off the release film with the lower adhesive strength (light release side release film) and then peeling off the release film with the higher adhesive strength (heavy release side release film). Hereinafter, each of the components constituting the pressure-sensitive adhesive sheet with a release film will be described.

[0017] <Release film [F]> The release film [F] used in this embodiment has a surface resistance of 1.0 × 10 14 Ω / □ or more, preferably 1.0×10 14 Ω / □~5.0×10 15 Ω / □, more preferably 1.0×10 15 Ω / □~4.0×10 15 Ω / □, more preferably 2.0×10 15 Ω / □~3.0×10 15 It is Ω / □. The release film [F] having a surface resistance value in the above range is generally a release film having no antistatic layer. That is, the release film [F] is preferably a release film having no antistatic layer. The surface resistance value of a release film having an antistatic layer is usually 1.0 × 10 13 It is Ω / □ or less.

[0018] In this specification, the surface resistance value is measured by the following method. Using a high resistance measuring instrument (HP4339B manufactured by Hewlett-Packard Japan) and a measuring electrode (HP16008B manufactured by Hewlett-Packard Japan), the sample is conditioned for 30 minutes in a measuring atmosphere of 23°C and 50% RH, and then the surface resistivity is measured.

[0019] The peel strength of the release film [F] from the pressure-sensitive adhesive sheet [I] is usually 0.05 to 1.5 N / cm, preferably 0.06 to 1.2 N / cm, and more preferably 0.07 to 1.0 N / cm. The peel strength of the release film [F] is measured in a 180° peel test at a test speed of 300 m / min. In the case of a double-sided pressure-sensitive adhesive sheet with release films, it is preferable to provide a difference in peel strength between the light release side release film and the heavy release side release film, and the peel strength ratio of the heavy release side release film / light release side release film is usually in the range of more than 1.0 to 5.0, preferably 1.5 to 4.0, and more preferably 2.0 to 3.0. Within the above range, the release film [F] can be easily peeled from the pressure-sensitive adhesive sheet [I], and there is a tendency that peeling marks can be prevented during peeling.

[0020] The thickness of the release film [F] is usually 20 to 500 μm, preferably 30 to 250 μm, more preferably 40 to 125 μm, and even more preferably 60 to 100 μm. By setting the thickness of the release film [F] within the above range, the release film [F] tends to have excellent conformability to a curved pressure-sensitive adhesive sheet, to be less likely to lift off the pressure-sensitive adhesive sheet [I] during storage, and to have excellent storage stability.

[0021] Examples of materials for the release film [F] include films made of resin materials such as polyester resin, polyolefin resin, polycarbonate resin, polystyrene resin, acrylic resin, triacetyl cellulose resin, and fluororesin. Furthermore, films made of these materials that have been treated with a silicone resin or with release paper can also be used. Among these, polyester resin and polyolefin resin are preferred, with release-treated polyester resin and polyolefin resin being more preferred, and release-treated polyethylene terephthalate being particularly preferred. Furthermore, the resin materials for the release film [F] may be used alone or in combination of two or more.

[0022] In the release treatment of the release film [F], the release force can be adjusted by using a silicone composition containing a solvent-curable silicone and a solventless-curable silicone to perform the release treatment on the film made of the resin, or by incorporating a reactive release strength adjuster or the like. The reactive release strength modifier is a type of release strength modifier that reacts with the siloxane polymer of the release agent upon drying and is incorporated into it. The chemical structure of the reactive release strength modifier preferably has, for example, a vinyl group as the reactive group, and is generally known as an MQ resin or an MDQ resin.

[0023] <Adhesive sheet [I]> The pressure-sensitive adhesive sheet [I] used in this embodiment is preferably a pressure-sensitive adhesive sheet formed from a resin composition (i) containing an acrylic copolymer (A), preferably containing the acrylic copolymer (A) as a main component.

[0024] The layer structure of the pressure-sensitive adhesive sheet [I] may be a single layer or a multi-layer structure. When a pressure-sensitive adhesive sheet with a multi-layer structure is used, it is preferably a multi-layer structure of two or more layers from the viewpoint of lamination reliability, more preferably a multi-layer structure of two or more layers in which the surface layer and the back layer are acrylic pressure-sensitive adhesive layers, even more preferably a multi-layer structure of three or more layers in which the surface layer and the back layer are acrylic pressure-sensitive adhesive layers, and particularly preferably a multi-layer structure of three layers [surface layer (pressure-sensitive adhesive layer) / intermediate layer / back layer (pressure-sensitive adhesive layer)] in which the surface layer and the back layer are the acrylic pressure-sensitive adhesive layers and further an intermediate layer formed from a resin composition containing an acrylic copolymer.

[0025] Each layer of the pressure-sensitive adhesive sheet [I] may be a layer formed from the resin composition (i) described below, or may be a layer formed from a different resin composition. When the pressure-sensitive adhesive sheet [I] has a multi-layer structure of three or more layers, it is preferable that the front and back layers are layers formed from the same resin composition.

[0026] The thickness of the pressure-sensitive adhesive sheet [I] is usually 50 to 1000 μm, preferably 60 to 500 μm, and more preferably 75 to 300 μm. If the thickness is too thin, the level difference absorbability tends to decrease, while if the thickness is too thick, it tends to be difficult to obtain reliable lamination to curved members having curved portions.

[0027] Furthermore, when the pressure-sensitive adhesive sheet [I] has a multi-layer structure of three or more layers, the ratio of the total thickness of the surface layer and the back layer to the total thickness is usually 5 to 70%, preferably 10 to 60%, more preferably 20 to 45%. By keeping the thicknesses of the surface layer and the back layer within this range, when the pressure-sensitive adhesive sheet is attached to a curved surface member having a curved shape, it becomes less likely to be crushed even when pressure is applied, and it also tends to have excellent attachment reliability such as adhesiveness and level difference absorbency.

[0028] The shear storage modulus (G') of the pressure-sensitive adhesive sheet [I] at 25°C is 6.0 × 10 4 ~1.0×10 7 Pa, preferably 7.0×10 4 ~1.0×10 6 Pa, more preferably 8.0 × 104 ~1.0×10 6 Pa, more preferably 1.0 × 10 5 ~5.0×10 5 Pa. If the shear storage modulus (G') is too small, peeling marks tend to be easily formed on the pressure-sensitive adhesive sheet [I] when peeled. If it is too large, the level difference absorbency tends to decrease.

[0029] The shear storage modulus (G') can be measured as follows. The release film on one side of the adhesive sheet is removed, and the sheet is repeatedly laminated with a hand roller to a thickness of 0.7 to 1.0 mm (for example, approximately 0.8 mm), and a circle with a diameter of 8 mm is punched out to form a sample. The resulting sample is placed in a rheometer (TA Instruments "DHR-2") and subjected to dynamic viscoelasticity measurement under the following conditions: measurement jig: 8 mm diameter parallel plates, frequency: 1 Hz, measurement temperature: -50 to 150°C, heating rate: 5°C / min, and the shear storage modulus (G') at 25°C is read.

[0030] In order to accurately measure the storage shear modulus (G'), it is necessary to avoid fluctuations in the measurement results due to the influence of the measuring jig caused by an insufficient thickness of the pressure-sensitive adhesive sheet. For this reason, the thickness is adjusted to the range of 0.7 to 1.0 mm before measurement, which allows the storage shear modulus (G') to be accurately measured without being influenced by the measuring jig. The above-mentioned "thickness of 0.7 to 1.0 mm" means that if the thickness of the pressure-sensitive adhesive sheet used as the measurement sample is less than this range, the thickness of the measurement sample is adjusted to within this range by stacking several sheets, for example.

[0031] From the viewpoint of increasing the reliability of lamination, the pressure-sensitive adhesive sheet [I] preferably has photocurability, that is, it is cured by irradiation with active energy rays such as ultraviolet rays.

[0032] When the pressure-sensitive adhesive sheet [I] is active energy ray curable, the gel fraction before curing (after pre-curing, which will be described later) is preferably 10% by mass or more, more preferably 40% by mass or more, even more preferably 60% by mass or more, and particularly preferably 65% ​​by mass or more. When the gel fraction is 10% by mass or more, the pressure-sensitive adhesive sheet tends to not undergo cohesive failure over time when attached to a curved surface member, and to exhibit excellent curved surface attachment properties. On the other hand, from the viewpoint of conformability to unevenness, the gel fraction is preferably 90% by mass or less, and more preferably 80% by mass or less.

[0033] The pressure-sensitive adhesive sheet [I] is curable with active energy rays and is irradiated with active energy rays having a wavelength of 365 nm at an integrated light dose of 2000 to 4000 mJ / cm. 2 When the composition is cured by irradiation, the gel fraction preferably increases compared to before curing. The gel fraction after curing is preferably 70% by mass or more, more preferably 73% by mass or more, and particularly preferably 75% by mass or more. The upper limit is usually 100% by mass. When the gel fraction after curing is within the above range, the pressure-sensitive adhesive sheet [I] tends to have shape stability and durability when used in an image display device. Furthermore, the gel fraction after curing is preferably increased by 2% by mass or more compared to before curing, more preferably 3% by mass or more, even more preferably 5% by mass or more, and particularly preferably 10% by mass or more. When the difference in gel fraction before and after curing is within the above range, it tends to be possible to impart step-following ability and durability when used in an image display device.

[0034] The gel fraction is determined by the following method. The mass of the adhesive sheet [I] (mass before immersion) is measured, wrapped in a bag using SUS mesh (#200), immersed in ethyl acetate, and stored in a dark place at 23°C for 24 hours. The bag is then removed and heated at 70°C for 4.5 hours to evaporate the adhering ethyl acetate. The mass of the remaining adhesive sheet (mass after immersion) is measured, and the gel fraction is calculated using the following formula. Gel fraction (mass%) = [(mass after immersion) / (mass before immersion)] × 100

[0035] The adhesive strength of the pressure-sensitive adhesive sheet [I] is usually 3 N / cm or more, preferably 4 N / cm or more, more preferably 5 N / cm, and the upper limit of the 180° peel adhesive strength is usually 50 N / cm.

[0036] When the pressure-sensitive adhesive sheet [I] is active energy ray-curable, the adhesive strength after irradiation with active energy rays (after curing) is usually 3 N / cm or more, preferably 4 N / cm or more, and particularly preferably 5 N / cm or more. The upper limit of the 180° peel adhesive strength is usually 50 N / cm.

[0037] The adhesive strength is measured by the following method. A 100 μm thick polyethylene terephthalate film (Diafoil T100, manufactured by Mitsubishi Chemical Corporation) was bonded to one side of the adhesive sheet, and the other side was roll-pressed onto soda lime glass to form a bonded product. The bonded product was then cured at 40°C for 3 hours and then finished and bonded to form a sample. The sample was then peeled at a peel angle of 180° and a peel speed of 60 mm / min in an environment of 23°C and 50% RH, and the peel force (N / cm) to the glass was measured. The adhesive strength after curing was measured by irradiating the polyethylene terephthalate film surface with ultraviolet light at 365 nm with an integrated light intensity of 2000 mJ / cm. 2 After irradiation so as to obtain the above, the sample is cured for 12 hours in an environment of a temperature of 23°C and a humidity of 50% RH and then used as a sample.

[0038] The pressure-sensitive adhesive sheet [I] is preferably an optically transparent pressure-sensitive adhesive sheet. Here, "optically transparent" means that the total light transmittance is 80% or more, preferably 85% or more, and more preferably 90% or more. The haze value of the pressure-sensitive adhesive sheet [I] is preferably 10% or less, more preferably 5% or less, even more preferably 3% or less, and particularly preferably 1% or less.

[0039] The pressure-sensitive adhesive sheet [I] is usually preferably a pressure-sensitive adhesive sheet formed from a resin composition (i) containing an acrylic copolymer (A), preferably containing the acrylic copolymer (A) as a main component, and more preferably formed from a resin composition (i) containing the acrylic copolymer (A), a crosslinking agent (B), and a photopolymerization initiator (C). Each component contained in the resin composition (i) will be described below.

[0040] [Acrylic copolymer (A)] The acrylic copolymer (A) may be, for example, a copolymer of an alkyl acrylate monomer having an alkyl group with 4 to 18 carbon atoms and a monomer component copolymerizable therewith. The resin composition may contain only one type of acrylic copolymer (A), or two or more types of acrylic copolymer (A).

[0041] Examples of the alkyl (meth)acrylate monomer having 4 to 18 carbon atoms in the alkyl group include linear alkyl (meth)acrylates such as n-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, n-octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, cetyl (meth)acrylate, and stearyl (meth)acrylate; isobutyl (meth)acrylate, sec-butyl (meth)acrylate, t-butyl (meth)acrylate; and isobutyl (meth)acrylate. Examples of the alicyclic (meth)acrylates include branched alkyl (meth)acrylates such as isopentyl (meth)acrylate, neopentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, isodecyl (meth)acrylate, and isostearyl (meth)acrylate, and alicyclic (meth)acrylates such as cyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, 3,5,5-trimethylcyclohexane (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, and isobornyl (meth)acrylate. These may be used alone or in combination of two or more. Among these, branched alkyl (meth)acrylates and alicyclic (meth)acrylates in which the alkyl group has 6 to 14 carbon atoms are preferred, and 2-ethylhexyl (meth)acrylate and isobornyl (meth)acrylate are more preferred.

[0042] The content of the alkyl (meth)acrylate having 4 to 18 carbon atoms in the alkyl group is usually 30 to 90 mass %, preferably 35 to 88 mass %, more preferably 40 to 85 mass %, and particularly preferably 55 to 85 mass %, of the total monomer components of the copolymer.

[0043] Examples of the copolymerizable monomer component include copolymers with a monomer component containing one or more monomers selected from a carboxy group-containing monomer, a hydroxy group-containing monomer, a nitrogen atom-containing monomer, an epoxy group-containing monomer, a vinyl monomer, an alkyl (meth)acrylate monomer having an alkyl group with 1 to 3 carbon atoms, and other copolymerizable monomers.

[0044] Examples of the carboxy group-containing monomer include (meth)acrylic acid and (meth)acrylic acid dimer. These may be used alone or in combination of two or more. Of these, (meth)acrylic acid is preferred.

[0045] The content of the carboxyl group-containing monomer in the total monomer components of the copolymer is usually 10% by mass or less, preferably 8% by mass or less, and particularly preferably 6% by mass or less, with the lower limit usually being 0% by mass.

[0046] Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxy-1-methylethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, glycerin mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, polyethylene glycol polypropylene glycol mono(meth)acrylate, polyethylene glycol polybutylene glycol mono(meth)acrylate, and hydroxyphenyl (meth)acrylate. These may be used alone or in combination of two or more. Among these, 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferred.

[0047] The content of the hydroxyl group-containing monomer in the total monomer components of the copolymer is usually 30% by mass or less, preferably 25% by mass or less, and particularly preferably 20% by mass or less, with the lower limit usually being 0% by mass.

[0048] Examples of the nitrogen atom-containing monomer include aminoalkyl (meth)acrylates such as aminomethyl (meth)acrylate, aminoethyl (meth)acrylate, aminopropyl (meth)acrylate, and aminoisopropyl (meth)acrylate; amino group-containing monomers such as N-alkylaminoalkyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, and N,N-dimethylaminopropyl (meth)acrylate; amide group-containing monomers such as (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N-butyl (meth)acrylamide, N-methylol (meth)acrylamide, N-methylolpropane (meth)acrylamide, N-methoxymethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide, and diacetone (meth)acrylamide; and amide group-containing monomers such as maleic acid amide and maleimide. These may be used alone or in combination of two or more. Among these, amide group-containing monomers are preferred, and (meth)acrylamide is more preferred.

[0049] The content of the nitrogen atom-containing monomer in the total monomer components of the copolymer is usually 20% by mass or less, preferably 10% by mass or less, and particularly preferably 7% by mass or less, with the lower limit usually being 0% by mass.

[0050] Examples of the epoxy group-containing monomer include glycidyl (meth)acrylate, methyl glycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether, etc. These may be used alone or in combination of two or more.

[0051] The content of the epoxy group-containing monomer in the total monomer components of the copolymer is usually 20% by mass or less, and preferably 10% by mass or less, with the lower limit usually being 0% by mass.

[0052] Examples of the vinyl monomer include compounds having a vinyl group in the molecule. Examples of such compounds include vinyl ester monomers such as vinyl acetate, vinyl propionate, and vinyl laurate, aromatic vinyl monomers such as styrene, chlorostyrene, chloromethylstyrene, α-methylstyrene, and other substituted styrenes, and polyalkylene glycol di(meth)acrylates. These may be used alone or in combination of two or more. Among these, vinyl acetate is preferred.

[0053] The content of the vinyl monomer in the total monomer components of the copolymer is usually 40% by mass or less, preferably 35% by mass or less, and particularly preferably 30% by mass or less, with the lower limit usually being 0% by mass.

[0054] Examples of alkyl(meth)acrylate monomers having an alkyl group of 1 to 3 carbon atoms include methyl(meth)acrylate, ethyl(meth)acrylate, n-propyl(meth)acrylate, and i-propyl(meth)acrylate. These may be used alone or in combination of two or more. Of these, methyl(meth)acrylate is preferred.

[0055] The content of the alkyl (meth)acrylate monomer in which the alkyl group has 1 to 3 carbon atoms in the total monomer components of the copolymer is usually 40% by mass or less, preferably 35% by mass or less, and particularly preferably 25% by mass or less, with the lower limit usually being 0% by mass.

[0056] Examples of the other copolymerizable monomers include acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride, heterocyclic basic monomers such as vinylpyrrolidone, vinylpyridine and vinylcarbazole, macromonomers, etc. These may be used alone or in combination of two or more.

[0057] The content of the other copolymerizable monomers in the total monomer components of the copolymer is usually 30% by mass or less, and preferably 25% by mass or less, with the lower limit usually being 0% by mass.

[0058] In this embodiment, an acrylic copolymer (A) obtained by copolymerizing the various monomer components may be used, and the copolymerization method may be a conventionally known method, such as solution radical polymerization, suspension polymerization, bulk polymerization, emulsion polymerization, etc. Among these, solution polymerization is preferred because it allows the acrylic copolymer (A) to be produced safely and stably with any monomer composition. An example of a preferred method for producing the acrylic copolymer (A) used in this embodiment will be described below.

[0059] First, the copolymerization components and polymerization initiator are mixed or dropped into an organic solvent, followed by solution polymerization to obtain an acrylic polymer solution.

[0060] Examples of organic solvents used in the polymerization reaction include aromatic hydrocarbons such as toluene and xylene, aliphatic hydrocarbons such as hexane, esters such as ethyl acetate and butyl acetate, aliphatic alcohols such as n-propyl alcohol and isopropyl alcohol, and ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. These solvents can be used alone or in combination of two or more. Among these solvents, ethyl acetate is preferred.

[0061] As the polymerization initiator used in the polymerization reaction, azo-based polymerization initiators and peroxide-based polymerization initiators, which are common radical polymerization initiators, can be used. Examples of the azo polymerization initiator include 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobisisobutyronitrile, (1-phenylethyl)azodiphenylmethane, 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), and 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile). Examples of the peroxide polymerization initiator include benzoyl peroxide, di-t-butyl peroxide, cumene hydroperoxide, lauroyl peroxide, t-butyl peroxypivalate, t-hexyl peroxypivalate, t-hexyl peroxyneodecanoate, diisopropyl peroxycarbonate, and diisobutyryl peroxide. These polymerization initiators can be used alone or in combination of two or more. Among them, azo-based polymerization initiators are preferred, with 2,2'-azobis(2,4-dimethylvaleronitrile) being particularly preferred.

[0062] The amount of the polymerization initiator used is usually 0.001 to 10 parts by mass, preferably 0.1 to 8 parts by mass, more preferably 0.5 to 6 parts by mass, even more 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, per 100 parts by mass of the copolymerization components. If the amount of the polymerization initiator used is above the lower limit, a decrease in the polymerization rate of the acrylic copolymer (A) and an increase in residual monomers, as well as an increase in the weight-average molecular weight of the acrylic copolymer (A), tend to be suppressed. If the amount used is below the upper limit, gelation during polymerization tends to be suppressed.

[0063] The solution polymerization may be carried out under conventionally known polymerization conditions. For example, the polymerization components and a polymerization initiator may be mixed or dropped into a solvent, and polymerization may be carried out under predetermined polymerization conditions.

[0064] The polymerization temperature in the polymerization reaction is usually 40 to 120° C., but in this embodiment, from the viewpoint of ensuring a stable reaction, it is preferably 50 to 90° C., more preferably 55 to 75° C., and even more preferably 60 to 70° C. If the polymerization temperature is too high, the acrylic copolymer (A) tends to be easily gelled, and if it is too low, the activity of the polymerization initiator decreases, so that the polymerization rate decreases and the amount of residual monomer tends to increase.

[0065] The polymerization time in the polymerization reaction (the time until the start of the follow-up heating, if the follow-up heating described below is carried out) is not particularly limited, but is preferably 0.5 hours or more from the addition of the final polymerization initiator, more preferably 1 hour or more, even more preferably 2 hours or more, and particularly preferably 5 hours or more. The upper limit of the polymerization time is usually 72 hours. The polymerization reaction is preferably carried out while refluxing the solvent, since this facilitates heat removal.

[0066] In the production of the acrylic copolymer (A), in order to reduce the amount of residual polymerization initiator, it is preferable to thermally decompose the polymerization initiator by follow-up heating.

[0067] The drive-in heating temperature is preferably higher than the 10-hour half-life temperature of the polymerization initiator, and specifically is usually 40 to 150° C., and from the viewpoint of suppressing gelation, it is preferably 55 to 130° C., and more preferably 75 to 95° C. If the drive-in heating temperature is too high, the acrylic copolymer (A) tends to turn yellow, whereas if it is too low, the polymerization components and polymerization initiator remain, and the stability over time and thermal stability of the acrylic copolymer (A) tend to decrease. In this way, the acrylic copolymer (A) can be obtained.

[0068] The glass transition temperature (Tg) of the acrylic copolymer (A) is usually from -100 to 25°C, preferably from -80 to 20°C, and particularly preferably from -50 to 15°C, from the viewpoint of the balance between adhesiveness, conformability to unevenness, and peel marks.

[0069] In the present invention, the glass transition temperature (Tg) is determined by reading the temperature at which the loss tangent (tanδ) becomes maximum when dynamic viscoelasticity is measured in a shear mode at a frequency of 1 Hz using a dynamic viscoelasticity measuring device. For example, the acrylic copolymer (A) is molded into a cylindrical body with a diameter of 8 mm (height of 1.0 mm), and the loss tangent (tanδ) can be measured using a rheometer (manufactured by TA Instruments, "DHR-2") under the following measurement conditions. (Measurement conditions) Measurement jig: Φ8mm parallel plate Distortion: 0.1% Frequency: 1Hz ·Measurement temperature: -50~80℃ Heating rate: 5℃ / min

[0070] The weight average molecular weight (Mw) of the acrylic copolymer (A) is preferably 400,000 or more, more preferably 500,000 or more, and even more preferably 550,000 or more, from the viewpoint of obtaining a resin composition (i) with high cohesive strength. In addition, the upper limit of the weight average molecular weight (Mw) of the acrylic copolymer (A) is preferably 1.5 million or less, more preferably 1.2 million or less, even more preferably 1.1 million or less, particularly preferably 1 million or less, and especially preferably 900,000 or less, from the viewpoints of ease of handling and uniform stirring.

[0071] Furthermore, the number average molecular weight (Mn) of the acrylic copolymer (A) is preferably 5,000 or more, more preferably 10,000 or more, and even more preferably 50,000 or more, from the viewpoint of obtaining a resin composition (i) with high cohesive strength. The upper limit of the number average molecular weight (Mn) of the acrylic copolymer (A) is preferably 100,000 or less, more preferably 800,000,000 or less, from the viewpoints of ease of handling and uniform stirring.

[0072] Furthermore, the dispersity (weight average molecular weight / number average molecular weight) of the acrylic copolymer (A) is preferably 20 or less, more preferably 15 or less, and even more preferably 10 or less, from the viewpoint of adhesive properties. The lower limit of the dispersity is usually 1.1 from the viewpoint of production limitations.

[0073] In the present invention, the weight average molecular weight (Mw) can be determined, for example, as follows. (Method for measuring weight-average molecular weight) The weight average molecular weight (Mw) can be determined by dissolving 4 mg of acrylic polymer (A) in 12 mL of tetrahydrofuran (THF) to prepare a measurement sample, and measuring the molecular weight distribution curve using a gel permeation chromatography (GPC) analyzer ("HLC-8320GPC" manufactured by Tosoh Corporation) under the following conditions: Guard column: TSKguardcolumnHXL Separation column: TSKgel GMHXL (4 columns) ·Temperature: 40℃ ·Injection volume: 100μL Polystyrene equivalent Solvent: THF ·Flow rate: 1.0mL / min

[0074] The content of the acrylic copolymer (A) is usually 50 to 99% by mass, preferably 60 to 98% by mass, and more preferably 70 to 95% by mass of the resin composition (i).

[0075] [Crosslinking agent (B)] Examples of the crosslinking agent (B) include crosslinking agents having at least one crosslinkable functional group selected from (meth)acryloyl, epoxy, isocyanate, carboxy, hydroxy, carbodiimide, oxazoline, aziridine, vinyl, amino, imino, and amide groups. These may be used alone or in combination of two or more. The crosslinking agent (B) also includes an embodiment in which the crosslinking agent (B) is chemically bonded to the acrylic copolymer (A).

[0076] Among these, crosslinking agents having a (meth)acryloyl group are preferred, and polyfunctional (meth)acrylates having two or more functional groups are particularly preferred. Here, "polyfunctional" refers to those having two or more crosslinkable functional groups. If necessary, three or more, or four or more crosslinkable functional groups may be present. Furthermore, the crosslinkable functional groups may be protected with deprotectable protecting groups.

[0077] Examples of the polyfunctional (meth)acrylate include bifunctional (meth)acrylates such as 1,4-butanediol di(meth)acrylate, glycerin di(meth)acrylate, neopentyl glycol di(meth)acrylate, glycerin glycidyl ether di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, tricyclodecane dimethacrylate, tricyclodecane dimethanol di(meth)acrylate, bisphenol A polyethoxy di(meth)acrylate, bisphenol A polyethoxy di(meth)acrylate, bisphenol B polyethoxy di(meth)acrylate, bisphenol C ... Examples of the (meth)acrylate having three or more functional groups include phenol A polypropoxy di(meth)acrylate, bisphenol F polyethoxy di(meth)acrylate, ethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol hydroxypivalate di(meth)acrylate, and di(meth)acrylate of an ε-caprolactone adduct of neopentyl glycol hydroxypivalate. Trimethylolpropane trioxyethyl (meth)acrylate, ε-caprolactone-modified tris(2-hydroxyethyl) isocyanurate tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propoxylated pentaerythritol tri(meth)acrylate, ethoxylated pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, propoxylated pentaerythritol tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, dipentaerythritol

[0033] Examples of the acrylates include hexa(meth)acrylate, tris(acryloxyethyl)isocyanurate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, tripentaerythritol hexa(meth)acrylate, tripentaerythritol penta(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane polyethoxytri(meth)acrylate, and ditrimethylolpropane tetra(meth)acrylate.In addition to the above-mentioned polyfunctional (meth)acrylates, polyfunctional (meth)acrylic oligomers such as polyester (meth)acrylate, epoxy (meth)acrylate, urethane (meth)acrylate, and polyether (meth)acrylate can also be used. These may be used alone or in combination of two or more. Among these, ultraviolet-curable polyfunctional (meth)acrylates are preferred, and trifunctional or higher functional (meth)acrylates, especially propoxylated pentaerythritol tri(meth)acrylate, are particularly preferred.

[0078] The content of the crosslinking agent (B) is preferably 0.5 to 50 parts by mass, more preferably 1 to 40 parts by mass, and particularly preferably 5 to 30 parts by mass, relative to 100 parts by mass of the acrylic copolymer (A). When the content of the crosslinking agent (B) is within the above range, the curing reaction proceeds sufficiently in a short time, which is preferable because it is easy to balance the reliability after curing with the resistance to wet heat whitening, flexibility, processability when molding into a sheet, and the like.

[0079] [Photopolymerization initiator (C)] The photopolymerization initiator (C) is a compound that generates radicals when exposed to active energy rays, and is roughly classified into two types based on the radical generation mechanism: hydrogen abstraction photopolymerization initiators (c1), which are capable of forming an exciplex between an excited initiator and a hydrogen donor in the system and transferring hydrogen from the hydrogen donor; and cleavage photopolymerization initiators (c2), which are capable of generating radicals by cleaving and decomposing the single bond of the initiator itself.

[0080] The photopolymerization initiator (C) may be either a hydrogen abstraction photopolymerization initiator (c1) or a cleavage photopolymerization initiator (c2), and either one may be used alone or in combination with the other, or one or more types of each may be used in combination. However, in the pressure-sensitive adhesive sheet [I], it is preferable to use a hydrogen abstraction photopolymerization initiator (c1) because it is highly versatile and does not require functional groups such as polymerizable unsaturated groups in the acrylic copolymer (A) itself, and because it forms a uniform crosslinked network structure by crosslinking the entire polymer, thereby improving the shear storage modulus at high temperatures.

[0081] Examples of the hydrogen abstraction photopolymerization initiator (c1) include benzophenone, 4-methylbenzophenone, 2,4,6-trimethylbenzophenone, 4-phenylbenzophenone, 3,3'-dimethyl-4-methoxybenzophenone, 4-(meth)acryloyloxybenzophenone, methyl 2-benzoylbenzoate, methyl benzoylformate, bis(2-phenyl-2-oxoacetic acid)oxybisethylene, 4-(1,3-acryloyl-1,4,7,10,13-pentaoxotridecyl)benzophenone, thioxanthone, 2-chlorothioxanthone, 3-methylthioxanthone, 2,4-dimethylthioxanthone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-t-butylanthraquinone, 2-aminoanthraquinone, and derivatives thereof. Of these, benzophenone-based hydrogen abstraction photopolymerization initiators are preferred, and 4-methylbenzophenone and 2,4,6-trimethylbenzophenone are more preferred.

[0082] Examples of the cleavage-type photopolymerization initiator (c2) include 2,2-dimethoxy-1,2-diphenylethan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-(4-(2-hydroxyethoxy)phenyl)-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-[4-{4-(2-hydroxy-2-methyl-propionyl)benzyl}phenyl]-2-methyl-propan-1-one, oligo(2-hydroxy-2-methyl-1-(4-(1-methylvinyl)phenyl)propanone), methyl phenylglyoxylate, and 2-benzyl-2-dimethylamine. Examples of the methyl methyl phosphine oxide include bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, (2,4,6-trimethylbenzoyl)ethoxyphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)2,4,4-trimethylpentylphosphine oxide, and derivatives thereof.

[0083] The content of the photopolymerization initiator (C) is usually 0.1 to 10 parts by mass, preferably 0.5 to 5 parts by mass, and more preferably 1 to 4 parts by mass, relative to 100 parts by mass of the acrylic copolymer (A). When the content is equal to or greater than the lower limit, poor curing tends to be prevented, while when the content is equal to or less than the upper limit, deterioration in solution stability such as precipitation from the resin composition (i) tends to be suppressed, and problems such as embrittlement and coloration tend to be suppressed.

[0084] (Other ingredients) The resin composition (i) may contain, as "other components", various additives such as ultraviolet absorbers, rust inhibitors, silane coupling agents, tackifying resins, antioxidants, light stabilizers, metal deactivators, antioxidants, moisture absorbents, and inorganic particles, as needed, to the extent that the effects of the present invention are not impaired. If necessary, a reaction catalyst such as a tertiary amine compound, a quaternary ammonium compound, or a tin laurate compound may be appropriately contained. These can be used alone or in combination of two or more.

[0085] Examples of the ultraviolet absorber include benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, triazine-based ultraviolet absorbers, salicylic acid-based ultraviolet absorbers, cyanoacrylate-based ultraviolet absorbers, benzoxazine-based ultraviolet absorbers, etc. These ultraviolet absorbers can be used alone or in combination of two or more.

[0086] When the ultraviolet absorber is used, the content thereof is preferably 0.01 to 20 parts by mass, more preferably 0.1 to 15 parts by mass, and even more preferably 0.5 to 10 parts by mass, relative to 100 parts by mass of the acrylic copolymer (A). When the content is equal to or greater than the lower limit, lightfastness reliability tends to improve, and when the content is equal to or less than the upper limit, yellowing resistance tends to improve.

[0087] The anticorrosive agent is preferably, for example, a triazole or a benzotriazole, which can prevent corrosion of optical members. These may be used alone or in combination of two or more kinds. When the rust inhibitor is used, the content thereof is preferably 0.01 to 5 parts by mass, and more preferably 0.1 to 3 parts by mass, per 100 parts by mass of the acrylic copolymer (A).

[0088] The silane coupling agent is an organosilicon compound containing, in its structure, one or more reactive functional groups and one or more alkoxy groups bonded to silicon atoms. Examples of the reactive functional groups include epoxy groups, (meth)acryloyl groups, mercapto groups, hydroxyl groups, carboxy groups, amino groups, amide groups, and isocyanate groups. Among these, epoxy groups and mercapto groups are preferred in terms of balance of durability.

[0089] The alkoxy group bonded to the silicon atom preferably contains an alkoxy group having 1 to 8 carbon atoms from the viewpoint of durability and storage stability, and is particularly preferably a methoxy group or an ethoxy group. The silane coupling agent may have an organic substituent other than the reactive functional group and the alkoxy group bonded to the silicon atom, such as an alkyl group or a phenyl group.

[0090] Examples of the silane coupling agent include monomeric epoxy group-containing silane coupling agents, which are silane compounds such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; and silane coupling agents in which a part of the silane compound is hydrolyzed and condensed, or in which the silane compound is polymerized with methyltriethoxysilane, ethyltriethoxysilane, or methyltrimethoxysilane. oligomeric epoxy group-containing silane coupling agents which are silane compounds obtained by co-condensation of alkyl group-containing silane compounds such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, γ-mercaptopropyldimethoxymethylsilane, 3-mercaptopropylmethyldimethoxysilane, and monomeric mercapto group-containing silane compounds such as silane compounds obtained by hydrolysis and condensation polymerization of a part of the silane compounds or silane compounds obtained by hydrolysis and condensation polymerization of the silane compounds with methyltriethoxysilane, ethyltriethoxysilane, methyl ... Oligomeric mercapto group-containing silane coupling agents, which are silane compounds obtained by co-condensation of alkyl group-containing silane compounds such as ethyltrimethoxysilane and ethyltrimethoxysilane; (meth)acryloyl group-containing silane coupling agents such as 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, and 3-acryloxypropyltrimethoxysilane; N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane Examples of the silane coupling agents include amino group-containing silane coupling agents such as N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, and N-phenyl-3-aminopropyltrimethoxysilane; isocyanate group-containing silane coupling agents such as 3-isocyanatepropyltriethoxysilane; and vinyl group-containing silane coupling agents such as vinyltrimethoxysilane and vinyltriethoxysilane.These may be used alone or in combination of two or more.

[0091] Among these, epoxy group-containing silane coupling agents and mercapto group-containing silane coupling agents are preferably used because of their excellent durability, and epoxy group-containing silane coupling agents are particularly preferred.

[0092] The content of the silane coupling agent is preferably 0.005 to 10 parts by mass, particularly preferably 0.01 to 5 parts by mass, and even more preferably 0.05 to 1 part by mass, relative to 100 parts by mass of the acrylic copolymer (A). When the content is equal to or greater than the lower limit, durability tends to be improved, and when the content is equal to or less than the upper limit, durability tends to be improved.

[0093] The content of the other components is preferably 5 parts by mass or less, more preferably 1 part by mass or less, and even more preferably 0.5 parts by mass or less, relative to 100 parts by mass of the acrylic copolymer (A). If the content is too high, the compatibility with the acrylic polymer tends to decrease, and durability tends to decrease. The lower limit is 0 parts by mass.

[0094] The resin composition is obtained by mixing the acrylic copolymer (A), the crosslinking agent (B), the photopolymerization initiator (C), and other components as needed. There are no particular limitations on the mixing method, and there are no particular limitations on the order in which the components are mixed. A heat treatment step may be included in the production of the resin composition. In this case, it is desirable to mix the components of the resin composition in advance and then perform the heat treatment. In the above-mentioned mixing, a masterbatch made by concentrating the various mixed components may be used.

[0095] As mentioned above, the mixing method is not particularly limited, and for example, a universal kneader, a planetary mixer, a Banbury mixer, a kneader, a gate mixer, a pressure kneader, a three-roll mill, a two-roll mill, etc. can be used. When mixing the components of the resin composition, a solvent may be used as needed, or the components may be mixed as a solvent-free system that does not contain a solvent. By making the resin composition solvent-free, there is no residual solvent, which has the advantage of improving heat resistance and light resistance.

[0096] <Method of manufacturing the present pressure-sensitive adhesive sheet with release film> Next, a method for producing the present pressure-sensitive adhesive sheet with a release film will be described. However, the following explanation is an example of a method for producing the present pressure-sensitive adhesive sheet with a release film, and the present pressure-sensitive adhesive sheet with a release film is not limited to sheets produced by this production method.

[0097] The present pressure-sensitive adhesive sheet with release film is preferably produced as a pressure-sensitive adhesive sheet with release film by providing a release film [F] on the above-mentioned pressure-sensitive adhesive sheet [I], and is particularly preferably produced as a double-sided pressure-sensitive adhesive sheet with release film by providing the above-mentioned release film [F] on one side of the pressure-sensitive adhesive sheet [I] and an optional release film on the other side by the following steps. Also, the pre-curing described below may be omitted.

[0098] First, resin composition (i) is heated and melted (hot melt), coated onto a release film, sandwiched between other release films, and heated to produce a single-layer double-sided PSA sheet with a release film. When a double-sided PSA sheet with a release film having a multi-layer structure of two or more layers is desired, this single-layer double-sided PSA sheet with a release film can be obtained by preparing the number of layers required for the PSA sheet, peeling off the release films, and laminating the PSA sheets.

[0099] The obtained double-sided PSA sheet with a release film is preferably pre-cured by crosslinking with active energy rays so that it has latent active energy ray reactivity, in other words, so that it retains active energy ray reactivity. When pre-curing, each layer is crosslinked with active energy rays through the release film [F], and the gel fraction is set to the above-mentioned range. In this case, the degree of active energy ray crosslinking (gel fraction) can be adjusted by controlling the amount of active energy ray irradiation. However, as described above, it is also possible to adjust the degree of active energy ray crosslinking (gel fraction) by irradiating ultraviolet rays through the release film [F], thereby partially blocking the active energy rays.

[0100] Examples of the active energy rays include ionizing radiation such as α rays, β rays, neutron rays, and electron beams, ultraviolet rays, visible light, etc. Among these, ultraviolet rays are preferred from the viewpoint of suppressing damage to components of the image display device and controlling reactions.

[0101] Examples of the ultraviolet irradiation light source include a high-pressure mercury lamp, an ultra-high-pressure water lamp, a low-pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, a chemical lamp, an electrodeless discharge lamp, an LED, etc., which emit light in the wavelength range of 150 to 450 nm. Of these, it is preferable to use a high-pressure mercury lamp.

[0102] The amount of active energy ray irradiation (cumulative light amount) is usually 50 to 3000 mJ / cm from the viewpoint of curing. 2 , preferably 100 to 1000 mJ / cm 2 The irradiation time varies depending on the type of light source and other conditions, but is usually a few seconds, and in some cases may be a fraction of a second.

[0103] Furthermore, in addition to the above-mentioned method, a double-sided pressure-sensitive adhesive sheet with a release film having a multi-layer structure of two or more layers can also be produced by, for example, coating a resin composition on a release film to form an adhesive sheet, and then coating another resin composition on the formed adhesive sheet to form an adhesive sheet.

[0104] The pressure-sensitive adhesive sheet [I] is preferably used for bonding optical members. Specifically, it is preferably used for bonding members constituting a display, particularly members used for manufacturing a display, and is preferably used as a pressure-sensitive adhesive sheet for bonding an image display device component such as an image display panel and a protective panel or touch panel disposed on the front side (viewing side) of the image display device, or components constituting the image display device component. The image display device components can be the same as those described below.

[0105] <Laminate for image display device> A laminate for an image display device according to one embodiment of the present invention (hereinafter sometimes referred to as "the present laminate for an image display device") is a laminate for an image display device having a configuration in which two components of the image display device are laminated via a pressure-sensitive adhesive sheet [I]. The present laminate for an image display device is preferably a laminate for an image display device having a configuration in which two components of the image display device are laminated via the present pressure-sensitive adhesive sheet.

[0106] Among the components of the present laminate for an image display device, the pressure-sensitive adhesive sheet [I] is as described above, and the components other than the pressure-sensitive adhesive sheet will be described below.

[0107] [Image display device components] Examples of image display device components that constitute the present laminate for image display devices include flat panel image display device components, curved image display device components, and flexible image display device components. Examples of such image display device components include liquid crystal displays, organic electroluminescence (EL) displays, surface protection panels (surface protection films), polarizing plates, polarizers, retardation films, barrier films, viewing angle compensation films, brightness enhancement films, contrast enhancement films, diffusion films, semi-transparent reflective films, electrode films, transparent conductive films, metal mesh films, and touch sensor films. Any one of these may be used alone or in combination. Examples include a combination of a surface protection panel with other image display device components, or a combination with other image display device components.

[0108] It is preferable that one of the two image display device components is a surface protection panel and the other is a component consisting of one or a combination of two or more of the group consisting of a touch sensor, an image display panel, a color filter, a polarizing film, and a retardation film, and it is more preferable that the surface protection panel has a frame-shaped concealing portion on its periphery, and the frame has a portion with a width of 3 mm or less. With this configuration, the effects of the present invention can be particularly enjoyed.

[0109] [Method for manufacturing the present laminate for image display device] The method for producing the laminate for the image display device is not particularly limited, and as described above, for example, the resin composition (i) may be applied to a component of the image display device to form an adhesive sheet [I], or an adhesive sheet with a release film may be formed in advance and then laminated to the component of the image display device.

[0110] <Image display device> An image display device according to an embodiment of the present invention (hereinafter, sometimes referred to as "the image display device") is an image display device incorporating a laminate for an image display device having a configuration in which two components of the image display device are bonded together via the pressure-sensitive adhesive sheet. For example, there can be mentioned an image display device having a structure in which a laminate for an image display device having a configuration in which two components of the image display device are bonded together via the pressure-sensitive adhesive sheet is combined with other components of the image display device. In this case, examples of "other components of the image display device" include FPC cables, reflective sheets, light guide plates and light sources, diffusion films, prism sheets, liquid crystal panels, organic EL panels, anti-reflection films, color filters, polarizing plates, retardation plates, glass substrates, surface protection films, and integrated composites of these components. Specific examples of the image display device include liquid crystal displays, organic EL displays, inorganic EL displays, electronic paper, plasma displays, and microelectromechanical system (MEMS) displays used in personal computers, mobile terminals, game consoles, televisions (TVs), car navigation systems, touch panels, pen tablets, etc. [Example]

[0111] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention. In the examples, "parts" and "%" are by mass.

[0112] The surface resistance of the release film is measured by the following method. Using a high resistance measuring instrument (HP4339B manufactured by Hewlett-Packard Japan) and a measuring electrode (HP16008B manufactured by Hewlett-Packard Japan), the surface resistance value was measured after 30 minutes of humidity conditioning of the sample in a measurement atmosphere of 23°C and 50% RH.

[0113] First, the raw materials of the resin compositions prepared in the examples will be described in detail.

[0114] <Acrylic copolymer (A)> Acrylic copolymer (A-1): An acrylic copolymer (Mw=440,000, Mn=62,000, Mw / Mn=8, theoretical Tg=-50°C) obtained by randomly copolymerizing 75 parts of 2-ethylhexyl acrylate (homopolymer Tg (glass transition temperature (Tg) of a polymer obtained by polymerizing only 2-ethylhexyl acrylate): -70°C), 20 parts of vinyl acetate (homopolymer Tg: 32°C), and 5 parts of acrylic acid (homopolymer Tg: 106°C). Acrylic copolymer (A-2): An acrylic copolymer (Mw: 250,000) obtained by random copolymerization of 15 parts of a macromonomer (number average molecular weight: 3,000) having a terminal functional group of methacryloyl group, consisting of isobornyl methacrylate:methyl methacrylate = 1:1, 73 parts of 2-ethylhexyl acrylate, 9 parts of methyl acrylate, and 3 parts of acrylamide.

[0115] <Crosslinking agent (B)> Crosslinking agent (B-1): Propoxylated pentaerythritol polyacrylate

[0116] <Photopolymerization initiator (C)> Initiator (C-1): A mixture of 2,4,6-trimethylbenzophenone and 4-methylbenzophenone

[0117] [Example 1] Resin composition 1 was prepared by mixing 1 kg of acrylic copolymer (A-1), 100 g of crosslinking agent (B-1), and 15 g of initiator (C-1).

[0118] The resin composition 1 obtained above was applied to a heavy-release release film ("MRV100" manufactured by Mitsubishi Chemical Corporation: surface resistance value 5.0 × 10 5 Ω / □, with antistatic layer) and apply it with an applicator to a thickness of 100 μm. Then, apply a layer with a surface resistance of 2.1 × 10 15The sheet was sandwiched between Ω / □ light release films (MRQ38 manufactured by Mitsubishi Chemical Corporation, no antistatic layer) to obtain a laminate consisting of release film (heavy release) / sheet-like material / release film (light release). Then, using a high-pressure mercury lamp, the integrated light intensity of the wavelength of 365 nm was 3000 mJ / cm 2 Both surfaces of the sheet-like material were irradiated with ultraviolet light through the release film to obtain a pressure-sensitive adhesive sheet 1 with release film consisting of release film (heavy release) / adhesive sheet / release film (light release).

[0119] [Example 2] In Example 1, the resin composition 1 was used to prepare a release film having a heavy release property, such as "100D-GT2-SAS" manufactured by Fujimori Kogyo Co., Ltd. (having a surface resistance of 2.2 × 10 6 Ω / □, with antistatic layer), and Fujimori Kogyo's "38D-BD-NAS" (surface resistance value of 3.6 × 10 15 An adhesive sheet 2 with a release film was obtained in the same manner as in Example 1, except that a 1000 Ω / □ adhesive sheet (without an antistatic layer) was used.

[0120] [Example 3] Resin composition 2 was prepared by mixing 1 kg of acrylic copolymer (A-2), 100 g of crosslinking agent (B-1), and 15 g of initiator (C-1).

[0121] In Example 1, except that the resin composition 2 obtained above was used, an adhesive sheet 3 with a release film consisting of a release film (heavy release) / adhesive sheet / release film (light release) was obtained in the same manner as in Example 1.

[0122] [Example 4] Resin composition 3 was prepared by mixing 1 kg of acrylic copolymer (A-1), 200 g of crosslinking agent (B-1), and 15 g of initiator (C-1).

[0123] In Example 1, except that the resin composition 3 obtained above was used, an adhesive sheet 4 with a release film consisting of a release film (heavy release) / adhesive sheet / release film (light release) was obtained in the same manner as in Example 1.

[0124] [Comparative Example 1] Resin composition 4 was prepared by mixing 15 g of initiator (C-1) with 1 kg of acrylic copolymer (A-1) (no crosslinking agent was added).

[0125] In Example 1, the resin composition 4 obtained above was used to obtain an adhesive sheet 5 with a release film consisting of a release film (heavy release) / adhesive sheet / release film (light release) in the same manner as in Example 1.

[0126] Comparative Example 2 In Comparative Example 1, the cumulative amount of ultraviolet light was 6000 mJ / cm 2 A pressure-sensitive adhesive sheet 6 with a release film was obtained in the same manner as in Example 1, except for changing the above.

[0127] [Reference example 1] In Example 1, the resin composition 4 was used, and "MRQ75" manufactured by Mitsubishi Chemical Corporation (having a surface resistance of 3.0 × 10 5 A pressure-sensitive adhesive sheet 7 with a release film was obtained in the same manner as in Example 1, except that a pressure-sensitive adhesive sheet 8 with a release film (Ω / □, with antistatic layer) was used.

[0128] [Physical property measurement and evaluation] The pressure-sensitive adhesive sheets with release films prepared in the above Examples, Comparative Examples, and Reference Examples were subjected to the following various measurements and evaluations. The evaluation results are shown in Table 1 below.

[0129] <25°C shear storage modulus (G')> The release film on one side of each of the pressure-sensitive adhesive sheets with release film prepared in the Examples, Comparative Examples, and Reference Examples was removed, and the sheet was repeatedly laminated with a hand roller to a thickness of approximately 0.8 mm, and then punched out into a circle with a diameter of 8 mm to prepare a sample. The resulting sample was placed in a rheometer (TA Instruments "DHR-2") and subjected to dynamic viscoelasticity measurement under the following conditions: measurement jig: 8 mm diameter parallel plates, frequency: 1 Hz, measurement temperature: -50 to 150°C, heating rate: 5°C / min, and the shear storage modulus (G') at 25°C was read.

[0130] <Peeling marks> The adhesive sheets with release film prepared in the Examples, Comparative Examples, and Reference Examples were cut into strips 50 mm wide x 150 mm long, and the sheets were attached to a 5 mm thick piece of glass with double-sided tape using a hand roller with the light release film side facing outwards, and then the light release film was peeled off at an angle of 180° in the longitudinal direction at a peeling speed of 300 mm / min. The adhesive sheets after the release film had been peeled off were projected onto a projector and visually observed, with evaluation of "○" indicating no peeling marks and "×" indicating peeling marks.

[0131] <Printing step absorption> The adhesive sheets with release film prepared in the Examples, Comparative Examples, and Reference Examples were cut to a width of 50 mm x 80 mm, the light-release film was peeled off, and the sheets were attached to a 0.5 mm thick glass sheet with a 20 μm thick black print within a 5 mm area of ​​the outer periphery. After aging for 20 minutes at 60 ° C and 0.2 MPa, the obtained samples were checked and evaluated as follows: those with no bubbles remaining in the step with the black print were marked with "◎", those with bubbles remaining in one place were marked with "○", and those with bubbles remaining in two or more places were marked with "×".

[0132] [Table 1]

[0133] The adhesive sheet of the example has a surface resistance of 1.0 × 10 14 Even when a release film of Ω / □ or more (a release film without an antistatic layer) was used, the release film could be peeled off without leaving any peeling marks, and the sheets had good print step absorbency. In particular, the pressure-sensitive adhesive sheets of Examples 1 to 3 were more excellent in print step absorbency than the pressure-sensitive adhesive sheet of Example 4, which had a slightly higher shear storage modulus, and were therefore suitable pressure-sensitive adhesive sheets. On the other hand, the surface resistance is 1.0×10 14When using a release film of Ω / □ or more (a release film without an antistatic layer), the adhesive sheets of Comparative Examples 1 and 2 have good print step absorption, but peeling marks are left when the release film is peeled off, which is a factor that causes poor quality, and the object of the present invention could not be achieved. In Reference Example 1, the adhesive sheet is provided with a release film having a low surface resistance (a release film having an antistatic layer). In this case, the adhesive sheet is not affected by the shear storage modulus of the adhesive sheet, no peeling marks are produced, and the print step absorption is good, so there is no need to consider the selectivity of the adhesive sheet. That is, when a release film with a high surface resistivity is used, it is important that the pressure-sensitive adhesive sheet has a predetermined shear storage modulus as in the present invention. [Industrial Applicability]

[0134] From the viewpoint of resource saving and environmental friendliness, the pressure-sensitive adhesive sheet with a release film of the present invention does not leave peel marks even when a release film with a high surface resistance value (for example, a release film without an antistatic layer) is used. Therefore, it can be suitably used as a pressure-sensitive adhesive sheet with a release film used in the manufacture of a laminate for an image display device and an image display device.

Claims

1. Surface resistance is 1.0 x 10 14 A pressure-sensitive adhesive sheet with a release film, comprising a release film [F] having a resistivity of Ω / □ or more and a pressure-sensitive adhesive sheet [I] laminated together, The pressure-sensitive adhesive sheet [I] has a shear storage modulus (G') at 25°C of 6.0 × 10 4 ~1.0 x 10 7 Pa. An adhesive sheet with a release film.

2. The pressure-sensitive adhesive sheet [I] has an acrylic pressure-sensitive adhesive layer formed from a resin composition (i) containing an acrylic copolymer (A), a crosslinking agent (B), and a photopolymerization initiator (C).

2. The pressure-sensitive adhesive sheet with a release film according to claim 1.

3. The pressure-sensitive adhesive sheet with a release film according to claim 2 , wherein the crosslinking agent (B) is a polyfunctional (meth)acrylate compound having two or more functional groups.

4. The pressure-sensitive adhesive sheet with a release film according to claim 2 or 3, wherein the photopolymerization initiator (C) comprises a hydrogen abstraction photopolymerization initiator (c1).

5. 3. The pressure-sensitive adhesive sheet with a release film according to claim 1 or 2, wherein the release film [F] is a release film that does not have an antistatic layer.

6. A laminate for an image display device, comprising two image display device components laminated together via the adhesive sheet [I] according to claim 1 or 2, one of the two image display device components being a surface protection panel, and the other being a component consisting of any one or a combination of two or more of the group consisting of a touch sensor, an image display panel, a color filter, a polarizing film, and a retardation film.

7. 7. The laminate for an image display device according to claim 6, wherein the surface protection panel has a frame-shaped concealing portion on the periphery thereof, and the frame has a portion with a width of 3 mm or less.

8. The laminate for an image display device according to claim 6 , wherein the surface protection panel has a curved shape.

9. An image display device comprising the laminate for an image display device according to claim 6.

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