TW201841948A - Curable composition, sheet and laminate produced using same, and image display device - Google Patents

Abstract

Provided is a sheet which can exhibit good adhesiveness and retentivity, high transparency and water vapor barrier properties, and contains an isobutylene polymer (A) and an acrylate-based polymer (B), wherein the acrylate-based polymer (B) contains a monofunctional acrylate unit and a polyfunctional acrylate unit as structural units, at least one of maximum points of loss tangent (tan[delta]) in a shear measurement of the sheet at a frequency of 1 Hz falls within the range from -30 DEG C to 30 DEG C, and the haze of the sheet is 2.0% or less.

Description

Curable composition, sheet, laminated body using the same, image display device

The present invention relates to a sheet having an adhesive force, a holding power, a transparency, and a water vapor barrier property, and further a curable composition for producing the sheet.

In recent years, a curved surface or a bendable display device using an organic light-emitting diode (OLED) or a quantum dot (QD) has been developed and is being widely commercialized. Such a display device has a structure in which a plurality of film-like constituent members are bonded together by a transparent optical adhesive (OCA) sheet. However, the acrylic OCA sheet which has been used in the past has problems such as various failures due to insufficient moisture resistance, corrosion or migration of metal electrodes, and the like, and has sought a new material system OCA sheet. A polymer material containing an isobutylene as a polymerization component and a copolymerization component (referred to as "isobutylene polymer") is exemplified as a polymer material that can solve the above problems. The isobutylene polymer has a particularly high water vapor barrier property as a general-purpose soft resin. However, when it is applied to a resin composition, the cohesive force is too small, so that there are problems such as paste residue, low-temperature flow, and insufficient holding power. As one of the methods for flexibly applying such an isobutylene polymer having a low cohesive force, a method is known in which a monomer such as an acrylate is mixed with an isobutylene polymer to polymerize an acrylate to thereby increase the cohesive force. For example, Non-Patent Document 1 discloses a composition having a semi-IPN structure comprising a network of an isobutylene polymer and a polycyclohexyl methacrylate (PCHMA) as a monofunctional acrylate, and reveals a low temperature flow of the composition. It is inhibited and also has the original water vapor barrier property of the isobutylene polymer. Patent Document 1 discloses an adhesive composition comprising a sealing resin such as an isobutylene polymer, a polyfunctional acrylate, and a specific decane compound, and describes that the adhesive film obtained from the adhesive composition has excellent water vapor. Barrier and transparency. PRIOR ART DOCUMENT Patent Document Patent Document 1: Japanese Patent Publication No. 2016-527377 Non-Patent Document Non-Patent Document 1: B. Davion et al./Polymer, 51, (2010), 5323-5331

[Problems to be Solved by the Invention] The adhesive sheet comprising an isobutylene polymer and a polyfunctional acrylate disclosed in Patent Document 1 can have excellent water vapor barrier properties, but if this is the case, the glass transition temperature is too low. I can't get the full adhesion problem. As a method of raising the glass transition temperature, a large amount of a method of formulating an adhesion-imparting agent such as a petroleum resin is known, and in Example 1 of Patent Document 1, about 25% by mass of a hydrogenated DCPD (Dicyclopentadiene) system is added. Adhesive imparting agent. However, if a large amount of the adhesion-imparting agent is blended as described above, on the other hand, the glass transition temperature can be raised, and there is a problem that the retention force which is a property of maintaining the adhesive state for a long period of time is lowered. Further, the isobutylene polymer/DCPA-based composition comprising tricyclodecane dimethanol diacrylate (DCPA) exemplified in the above-mentioned Patent Document 1 has a refractive index of the cured product extremely close to that of the isobutylene polymer. Thus, the transparency of the composition can be maintained to some extent. However, when the isobutylene polymer/DCPA-based composition was observed by a transmission electron microscope (TEM), it was found that the DCPA cured product having a size of 1 μm or more dispersed due to poor compatibility of the isobutylene polymer with DCPA. The state may cause problems in terms of retention and transparency. In the system shown in the above Non-Patent Document 1, when the content ratio of the isobutylene polymer is large, the properties of the isobutylene polymer are remarkably prominent, and it is difficult to obtain an adhesive sheet having sufficient adhesion or holding force. The present invention provides a sheet having excellent adhesion, good retention, and excellent transparency and having excellent water vapor barrier properties, and further a curable composition for producing the sheet. [Technical means for solving the problem] The present invention provides a sheet comprising an isobutylene polymer (A) and an acrylate-based polymer (B), and the above acrylate-based polymer (B) has the following formula (1) a monofunctional acrylate unit having a unit structure and a polyfunctional acrylate unit as a structural unit, wherein at least one maximum point of loss tangent (tan δ) of the sheet at a frequency of 1 Hz is in the range of -30 ° C to 30 In the range of °C, the haze is 2.0% or less. [Chemical 1] (wherein R represents a hydrocarbon group, and R' represents hydrogen (H) or methyl (CH ₃ )). Further, the present invention provides a curable composition characterized in that it is 100 parts by mass based on 100 parts by mass of the isobutylene polymer (A). 5 parts by mass or more and less than 100 parts by mass of the acrylate monomer, and each having a monofunctional acrylate monomer and a polyfunctional acrylate monomer as the above acrylate monomer, and the above polyfunctional compound is contained in the above curable composition The acrylate is 0.5% by mass or more and less than 10% by mass. [Effect of the Invention] The above-mentioned sheet proposed by the present invention can be produced by curing the curable composition of the present invention by hardening. Further, the sheet proposed by the present invention contains a monofunctional acrylate unit having a unit structure represented by the above formula (1) and an acrylate polymer (B) having a polyfunctional acrylate unit as a structural unit, respectively. A semi-IPN (interpenetrating polymer network) structure is formed between the isobutylene polymer (A) and the acrylate polymer (B), and both water vapor barrier properties and transparency can be achieved. Further, at least one maximum point of the loss tangent (tan δ) in the shear measurement at a frequency of 1 Hz is in the range of -30 ° C to 30 ° C, so that a sheet having excellent adhesion and holding force can be obtained, so that the sheet can be improved. Subsequent, retention, transparency, and water vapor barrier properties. Therefore, by using the sheet as a constituent member of an image display device or the like, it is possible to contribute to thinning of an image display device or the like.

The invention is described in detail below. However, the content of the present invention is not limited to the embodiments described below. [This sheet] A sheet (referred to as "this sheet") according to an embodiment of the present invention is a sheet containing an isobutylene polymer (A) and an acrylate-based polymer (B). <Isobutylene Polymer (A)> The isobutylene polymer (A) constituting the sheet is a polymer having an isobutylene skeleton in a main chain or a side chain and having a structural unit of the following formula (2). [Chemical 2] The isobutylene polymer (A) has an effect of improving the water vapor barrier property of the sheet. Examples of the isobutylene polymer (A) include an isobutylene polymer as a homopolymer of isobutylene, a copolymer of isobutylene and isoprene, a copolymer of isobutylene and n-butene, and a copolymer of isobutylene and butadiene. And a halogenated butyl rubber obtained by subjecting the copolymer to bromination or chlorination. These polymers may be used alone or in combination of two or more. Among these, from the viewpoint of improving the durability and weather resistance of the sheet and lowering the water vapor transmission rate, the isobutylene polymer (A) is preferably an isobutylene polymer or isobutylene-isoprene. An olefin copolymer or a combination of these. The above isobutylene-isoprene copolymer has a repeating unit derived from isobutylene in the molecule [-CH ₂ -C(CH ₃ ) ₂ -] with repeat units from isoprene [-CH ₂ -C(CH ₃ )=CH-CH ₂ -] Synthetic rubber. The content of the repeating unit derived from isoprene in the isobutylene-isoprene copolymer is usually 0.1 to 99 mol%, preferably 0.5 to 50 mol%, more preferably 1 based on the total repeating unit. ~10 mol%. When the repeating unit derived from isoprene in the isobutylene-isoprene copolymer is in the above range, the sheet excellent in moisture resistance can be obtained, which is preferable. The type of the isobutylene-isoprene copolymer is not particularly limited. For example, a regenerated isobutylene-isoprene copolymer, a synthetic isobutylene-isoprene copolymer, etc. are mentioned. Among these, a synthetic isobutylene-isoprene copolymer is preferred. The method for synthesizing the isobutylene polymer includes a method of polymerizing a monomer component such as isobutylene in the presence of a Lewis acid catalyst such as aluminum chloride or boron trifluoride. Further, as the isobutylene polymer (A), a commercially available product can also be used. Examples of commercially available products include Vistanex (manufactured by Exxon Chemical Co.), Hycar (manufactured by Goodrich Co., Ltd.), Oppanol (manufactured by BASF Corporation), Tetrax (manufactured by JXTG Co., Ltd.), and Polybutene (manufactured by JXTG Co., Ltd.). The weight average molecular weight (Mw) of the isobutylene polymer (A) is preferably from 1,000 to 2,000,000 g/mol, more preferably 1,500 g/mol or more or 1,500,000 g/mol or less, and further preferably 2,000 g/mol or more. Further, it is 1,000,000 g/mol or less, and further preferably 50,000 g/mol or more, more preferably 100,000 g/mol or more, and still more preferably 120,000 g/mol or more. By making the isobutylene polymer an isobutylene polymer (A) having a weight average molecular weight (Mw) of 1,000 g/mol or more, the fluidity of the present curable composition forming the sheet becomes moderate, and it is easy to form into a sheet. Keep the shape. Further, by using the isobutylene polymer (A) having a weight average molecular weight (Mw) of 2,000,000 g/mol or less, a uniform structure can be easily obtained. Here, the weight average molecular weight (Mw) is a value measured by gel permeation chromatography (GPC analysis) using tetrahydrofuran as a solvent, and converted by standard polystyrene. The isobutylene polymer (A) may be used by combining two or more kinds of isobutylene polymers (A) having different average molecular weights. For example, an isobutylene polymer having a weight average molecular weight of less than 100,000 g/mol and an isobutylene polymer having a weight average molecular weight of 100,000 g/mol or more can be used as the bimodal molecular weight distribution of the isobutylene polymer. Thus, even if the raw materials are different from each other, the weight average molecular weight of the entire isobutylene polymer (A) is 1,000 to 2,000,000 g/mol, more preferably 1,500 to 1,500,000 g/mol, and still more preferably 2,000 to 1,000,000 g/mol. Just fine. Commercial products having a weight average molecular weight of less than 100,000 g/mol include, for example, Tetrax (JXTG), trade name: Polybutene (JXTG), and trade name: Himol (JXTG), as a weight average. A commercially available product having a molecular weight of 100,000 g/mol or more is exemplified by Oppanol (BASF Corporation). <Acrylate Polymer (B)> The acrylate polymer (B) constituting the sheet is preferably a monofunctional acrylate unit having a unit structure represented by the following formula (1) (also referred to simply as "monofunctional acrylate". The ester ") and the multifunctional acrylate unit (also referred to simply as "polyfunctional acrylate") are structural units. [Chemical 3] (wherein R represents a hydrocarbon group and R' represents hydrogen (H) or methyl (CH) ₃ )) (monofunctional acrylate) In the use of a folding display or the like, there is a case where it is required to lower the Tg of the sheet. In this case, the acrylate-based polymer (B) preferably has at least two monofunctional acrylates. By using two or more kinds of monofunctional acrylates, the carbon number of the side chain becomes inconsistent, and the Tg of the sheet can be lowered. Further, by adjusting the blending ratio of two or more kinds of monofunctional acrylates, the Tg of the sheet can be adjusted to a desired temperature region. For example, in a certain formulation, when isobutyl acrylate (iso-C18) ester is used alone as a monofunctional acrylate, the Tg of the sheet is about -2 ° C, and on the other hand, the mass is 1:1. When the ratio of isostearyl acrylate (iso-C18) ester to cetyl acrylate (n-C16) ester is blended, the Tg of the sheet can be lowered to around -20 °C. The monofunctional acrylate is preferably a monofunctional acrylate having a long-chain alkyl chain having 10 or more carbon atoms from the viewpoint of compatibility with the isobutylene polymer (A). The monofunctional acrylate having a long-chain alkyl chain having 10 or more carbon atoms is exemplified by an acrylate having one (meth) acryloxy group and having a long-chain alkyl chain having 10 or more carbon atoms. The aliphatic acrylate has a structure shown in the following formula (3). [Chemical 4] In the above formula (3), R represents a long-chain alkyl group having 10 or more carbon atoms. In the above formula, R' represents hydrogen (H) or methyl (CH) ₃ ). The long-chain alkyl group (R) having 10 or more carbon atoms is an alkyl group having a carbon number of 10 or more in the main chain. For example, 癸 ( (C ₁₀ ), undecyl (C ₁₁ ), dodecyl (C ₁₂ ), tridecyl (C ₁₃ ), tetradecyl (C ₁₄ ), pentadecyl (C ₁₅ ), cetyl (C ₁₆ ), heptadecyl (C ₁₇ ), octadecyl (C ₁₈ ), nonadecyl (C ₁₉ )Wait. The number of carbon atoms in the main chain in the long-chain alkyl group (R) is preferably 20 or less, particularly preferably 18 or less. When the number of carbon atoms is 18 or less, it is difficult to cause crystallization of the monofunctional aliphatic acrylates, and thus it is easy to exhibit transparency based on low haze and high total light transmittance. On the other hand, when the carbon number of the main chain is 10 or more, the long-chain alkyl group (R) may have a branched alkyl group. Generally, a branched alkyl group is difficult to crystallize at a normal temperature region, and it is easy to exhibit transparency compared to a linear alkyl group. In addition, when the long-chain alkyl group (R) is a combination of two or more kinds different from each other, crystallization can be suppressed and transparency can be improved. The acrylate-based polymer (B) preferably contains a monofunctional acrylate in a range of 60 to 90% by mass, and more preferably contains a monofunctional acrylate in a range of 70% by mass or more and 90% by mass or less. By setting it as such a range, the transparency of this sheet can be maintained, and creep resistance is also improved. The content of the monofunctional acrylate relative to the entire sheet is preferably 3% by mass or more. When it is set to 3% by mass or more, the creep resistance of the sheet can be improved. In this regard, the content of the monofunctional acrylate relative to the entire sheet is more preferably 5% by mass or more, and further preferably 10% by mass or more. On the other hand, as for the upper limit, the content of the monofunctional acrylate is preferably 50% by mass or less. When it is 50% by mass or less, the water vapor barrier property or the impact energy absorbability of the sheet can be improved. In this regard, the content of the monofunctional acrylate is more preferably 40% by mass or less, further preferably 35% by mass or less, more preferably 30% by mass or less, and still more preferably 25% by mass or less. . The acrylate-based polymer (B) is preferably a monofunctional acrylate containing at least one of the above formula (1) wherein R is a branched alkyl group, from the viewpoint of improving the crystallinity of the side chain and improving the transparency. (HSP distance) The Hansen solubility parameter (HSP) distance of the monofunctional acrylate of the above isobutylene polymer (A) and the acrylate polymer (B) is preferably 5.0 or less, more preferably 4.5 or less, and further preferably 3.8 or less. If the Hansen solubility parameter (HSP) distance of the monofunctional acrylate of the isobutylene polymer (A) and the acrylate polymer (B) is 5.0 or less, the isobutylene polymer (A) and the acrylate polymer (B) The compatibility is good, and it is possible to suppress the bleeding or the deterioration of the transparency due to the increase in the dispersion diameter. The HSP of the monofunctional acrylate is preferably at a position where the HSP distance from the isobutylene polymer (A) is 5.0 or less, more preferably 4.5 or less. Examples of the monofunctional acrylate having an HSP distance to the isobutylene polymer (A) of 5.0 or less include, for example, isostearyl acrylate, isohexadecyl acrylate, stearyl acrylate, and cetyl acrylate. Ester, isotetradecyl acrylate, tetradecyl acrylate, isododecyl acrylate, dodecyl acrylate, isodecyl acrylate, and the like. Here, "Hansen's solubility parameter (HSP)" is an index indicating how much a substance can be dissolved in another substance. The HSP system divides the solubility parameter introduced by Hildebrand into three components of a dispersion term δD, a polarity term δP, and a hydrogen bond term δH, and is expressed in a three-dimensional space. The dispersion term δD represents the effect based on the dispersion force, the polarity term δP represents the effect based on the inter-dipole force, the hydrogen bond term δH represents the effect based on the hydrogen bond force, and is expressed as δD: the energy δP from the dispersive force between the molecules: from The energy of the polar force between molecules δH: the energy from the hydrogen bonding force between molecules (here, the unit of each is MPa ^0.5 ). The definition and calculation of HSP are described in the following documents. Charles M. Hansen, Hansen Solubility Parameters: A Users Handbook (CRC Press, 2007). The dispersion term reflects the van der Waals force, the polarity term reflects the dipole moment, and the hydrogen bond term reflects the action of water, alcohol, and the like. Moreover, it can be judged that the vector similarity of the HSP is highly soluble, and the similarity of the vector can be judged by the distance (HSP distance) of the Hansen solubility parameter. Further, the solubility parameter of Hansen can be used not only as a judgment index of solubility, but also as a judgment index of how much a substance is likely to exist in other substances, that is, to what extent the dispersibility is good. In the present invention, HSP [δD, δP, δH] can be simply calculated from the chemical structure by using the computer software Hansen Solubility Parameters in Practice (HSPiP). Specifically, it is determined from the chemical structure by the Y-MB method attached to HSPiP. Further, when the chemical structure is unknown, it is determined by the result of the dissolution test using a plurality of solvents by the Sphere method attached to HSPiP. Regarding the HSP distance (Ra), for example, the HSP of the solute (the acrylate-based polymer (B) in the present invention) is set to (δD). ₁ δP ₁ δH ₁ ), the HSP of the solvent (the isobutylene polymer (A) in the present invention) is set to (δD) ₂ δP ₂ δH ₂ When it is, it can be calculated by the following formula. HSP distance (Ra) = {4 × (δD ₁ -δD ₂ ) ² +(δP ₁ -δP ₂ ) ² +(δH ₁ -δH ₂ ) ² } ^0.5 (Polyfunctional acrylate) By allowing the acrylate-based polymer (B) to contain a polyfunctional acrylate, the network of the acrylate-based polymer (B) can be adjusted, and as a result, the elastic modulus of the flat region of the sheet can be adjusted. (plateau elastic modulus). By adjusting the elastic modulus of the flat zone, it is possible to adjust the ease of wetting or the ease of entrainment of air bubbles when the sheet is attached. The more the amount of the polyfunctional acrylate added, the more the elastic modulus of the flat region can be increased, and the larger the molecular weight of the polyfunctional acrylate, the lower the elastic modulus of the flat region. The polyfunctional acrylate is an acrylate having two or more (meth) acryloxy groups and at least (meth) propylene hydroxy groups bonded to each other via a hydrocarbon group. As an example of the polyfunctional acrylate, the structure of the difunctional aliphatic acrylate is shown in the following formula (4). [Chemical 5] In the above formula (4), R is hydrogen (H) or methyl (CH) ₃ ). X is an aliphatic hydrocarbon group or an alicyclic hydrocarbon group. The HSP of the polyfunctional acrylate is preferably at a position where the HSP distance from the isobutylene polymer (A) is 9.0 or less, more preferably 8.0 or less. By setting the HSP distance to the above range, it is possible to suppress a failure related to transparency or adhesion such as bleeding. Among the polyfunctional acrylates, the aliphatic hydrocarbon group or the alicyclic hydrocarbon group (X) is preferably a hydrocarbon group containing no multiple bonds from the viewpoint of long-term stability of the sheet. Examples of the polyfunctional acrylate include a dialkyl acrylate having a linear alkyl group such as 1,9-nonanediol diacrylate, 1,10-nonanediol diacrylate, and hydrogenated polybutadiene acrylate; A diacrylate having an alicyclic skeleton such as tricyclononanediol diacrylate or tricyclodecane dimethanol diacrylate. However, it is not limited to these. As the polyfunctional acrylate, a polyfunctional urethane urethane can also be used. From the viewpoint of compatibility with the isobutylene polymer (A), an urethane urethane having an aliphatic polymer such as polybutadiene in the skeleton is preferred. As a commercial item of the urethane acrylate, the brand name: CN9014 NS (Sartomer company), brand name: BAC-45 (made by Osaka Organic Chemical Co., Ltd., polybutadiene-terminated diacrylate), etc. are mentioned. . The polyfunctional acrylate of such a polymer matrix has an effect of lowering the modulus of elasticity of the flat region of the sheet, and therefore, the acrylate-based polymer (B) constituting the sheet contains a polyfunctional acrylate. The sheet is preferably used, for example, for folding displays or impact resistant applications. The polyfunctional acrylate is not limited to the difunctional acrylate, and may be a polyfunctional acrylate having a (meth) acrylonitrile group in an amount of 3, 4, or more than 4. However, from the viewpoint of long-term stability of the sheet and ease of obtaining acrylate, a difunctional acrylate is preferred. Further, the polyfunctional acrylate may be used alone or in combination of two or more. The polyfunctional acrylate is preferably contained in the sheet in a ratio of 0.5% by mass or more and less than 10% by mass, and more preferably 0.7% by mass or more or less than 9% by mass, particularly 1.0% by mass or more. Or a ratio of less than 8.0% by mass is contained in the sheet. By setting the content of the polyfunctional acrylate to less than 10% by mass, bleeding can be reduced. On the other hand, transparency can be expressed by setting the content of the polyfunctional acrylate to 0.5% by mass or more. (content ratio) The acrylate-based polymer (B) is preferably contained in a ratio of 5 parts by mass or more and less than 100 parts by mass based on 100 parts by mass of the above-mentioned isobutylene polymer (A). When the content of the acrylate-based polymer (B) is 5 parts by mass or more, the cohesive force of the present curable composition can be effectively improved. In addition, when the content of the acrylate-based polymer (B) is 100 parts by mass or less, the dispersion diameter of the component (B) in the sheet can be made small, and good transparency can be exhibited, and the transparency can be improved. In this regard, the content ratio of the acrylate-based polymer (B) is preferably 5 parts by mass or more and less than 100 parts by mass, and more preferably 8 parts by mass, per 100 parts by mass of the isobutylene polymer (A). It is more than 10 parts by mass or less, and further preferably 10 parts by mass or more or 80 parts by mass or less. <Physical Properties of the Sheet> (Thickness) The thickness of the sheet is not particularly limited. For example, it is 0.01 mm or more, more preferably 0.03 mm or more, and still more preferably 0.05 mm or more. On the other hand, the upper limit is preferably 1 mm or less, more preferably 0.7 mm or less, still more preferably 0.5 mm or less. When the thickness is 0.01 mm or more, the workability is good, and if the thickness is 1 mm or less, the thickness of the laminate can be reduced. (Dispersibility) The sheet is preferably observed by a transmission electron microscope to observe a longitudinal section or a cross section of the sheet (magnification: 1000 to 5000 times), and no maximum diameter of 1 μm or more is observed. Piece. As described above, the block having a maximum diameter of 1 μm or more means that the isobutylene polymer (A) and the acrylate polymer (B) are highly compatible, and the water vapor barrier property and transparency can be achieved as the sheet. In addition, "the block having a maximum diameter of 1 μm or more is not observed" means that the sheet is dyed with ruthenium tetroxide or the like, and the sheet is placed on the sheet with a frozen sheet slicer or the like under freezing. Cut vertically or in parallel with the sheet surface to make a slice having a thickness of about 80 nm. When the cross section is observed by a transmission electron microscope (TEM) at a magnification of 1000 to 5000 times, the three slices are randomly selected. Ten sections were observed, and no block with a maximum diameter of 1 μm or more was observed in any of the fields of view. As described above, when the content of the acrylate-based polymer (B) is less than that of the isobutylene polymer (A), the above-mentioned "block having a maximum diameter of 1 μm or more" is a block containing the acrylate-based polymer (B). As described above, the block having a maximum diameter of 1 μm or more is not observed, meaning that the isobutylene polymer (A) and the acrylate polymer (B) are highly compatible, and as the sheet, as shown in Figs. 2 to 5 It is a co-continuous structure in which the isobutylene polymer (A) and the acrylate polymer (B) are uniformly dispersed. The acrylate monomer as the precursor of the acrylate-based polymer (B) is uniformly mixed in the isobutylene polymer (A), and the acrylate monomer in the mixture is polymerized, whereby the sheet can be as above The total continuous construction. (tan δ) The sheet is preferably at least one maximum point of loss tangent (tan δ) in shear at a frequency of 1 Hz in the range of -30 to 30 °C. By setting the maximum value of the tangent (tan δ) in the range of -30 to 30 ° C, a sheet having good adhesion and holding power can be obtained. By selecting an acrylate having a long-chain alkyl chain having 10 or more carbon atoms as a main component of the acrylate-based polymer (B), and selecting the kind of the isobutylene polymer and the ratio of the amounts, the loss tangent (tan δ) can be obtained. The maximum point is adjusted to within the range of -30 to 30 °C. Further, the maximum value of the loss tangent can be adjusted to be in the range of -30 to 30 ° C by adding the following tackifier. However, it is not limited to this method. Further, regarding the maximum value of the loss tangent (tan δ) in the shear of the sheet at a frequency of 1 Hz, it is more preferably in the range of -30 to 30 ° C at a frequency of 1 Hz in terms of ensuring adhesion. The maximum value of the loss tangent in the shearing is 0.5 or more, and more preferably 0.55 or more, and still more preferably 0.6 or more. The loss tangent (tan δ) of the sheet at 100 ° C is preferably 0.6 or less, and more preferably 0.5 or less. When the loss tangent (tan δ) is 0.6 or less, a sufficient high-temperature holding force can be expressed. In order to set the tan δ at 100 ° C of the sheet to 0.6 or less as described above, the polyfunctional acrylate may be blended in the acrylate-based polymer and sufficiently polymerized. However, it is not limited to this method. (Glass Transfer Temperature) The sheet preferably has a glass transition temperature (Tg) of a single unit. The multicomponent component containing at least the component (A) and the component (B) rarely becomes a single glass transition temperature (Tg) as a single material. However, since this sheet has good compatibility with the component (A) and the component (B), the glass transition temperature (Tg) can be made uniform. The transparency of the sheet can be improved by making the glass transition temperature single. Here, the "glass transition temperature" refers to the temperature of the peak of the main dispersion in which loss tangent (tan δ) occurs. Therefore, when only one point is observed at the maximum point of the tangent (tan δ) in the shear at a frequency of 1 Hz, the glass transition temperature (Tg) can be regarded as a single. (Total Light Transmittance and Haze) The sheet preferably has a total light transmittance of 85% or more, more preferably 88% or more, still more preferably 90% or more. Further, the sheet preferably has a haze of 2.0% or less, more preferably less than 1.0%, and particularly preferably less than 0.9%. By setting the haze to 2.0% or less, it can be used as a sheet for display devices depending on the application. (Water vapor transmission rate) In order to suppress deterioration of the light-emitting element by water and to improve the life of the display device, it is required that the water vapor transmission rate of the sheet is as low as possible. From this point of view, when the thickness of the sheet is 100 μm (when the thickness is set to 100 μm), the water vapor transmission rate in an environment of a temperature of 40 ° C and a relative humidity of 90% RH is preferably 20 g. /m ² ・24 h or less, and further preferably 15 g/m ² ・Under 24 hours, especially 10 g/m ² ・24 hours or less. Further, the lower limit is not particularly limited and is generally 0.5 g/m. ² ・24h or more. By making the water vapor transmission rate 20 g/m ² ・24 hours or less, it is possible to prevent and suppress the water vapor from the outside from reaching the object to be sealed, and the water vapor barrier property is good. In order to set the water vapor transmission rate to the above range, it is preferred that the sheet contains the isobutylene polymer (A) in an appropriate amount. Here, the water vapor transmission rate can be measured in accordance with JIS K7129B. Regarding the water vapor transmission rate when converted to 100 μm, for example, the thickness is A μm, and the water vapor transmission rate is B g / (m) ² In the case of "day", the water vapor transmission rate when the thickness is converted to 100 μm can be obtained by substituting into the formula of B × A / 100. <Method for Producing the Sheet> Next, a method for producing the sheet will be described. However, the following description is an example of a method of producing the sheet, and the sheet is not limited to those manufactured by the production method. This sheet can be obtained by hardening an uncured sheet containing the present curable composition described below. As a method of forming the curable composition into an uncured sheet, a known method such as dry lamination, extrusion casting using a T-die, extrusion lamination, calendering or Inflating method, etc. Among them, in terms of workability, productivity, and the like, a method of melt molding, such as an extrusion casting method and an extrusion lamination method, is preferred. In the case of selecting a melt molding without using a solvent, as the present curable composition for melt molding, a storage elastic modulus (G') in a shear at a frequency of 1 Hz in an unhardened state is preferred. It is 1,000 Pa or more, especially 50,000 Pa or more at 20 ° C, and 10,000 Pa or less at 160 ° C. When G' at 20 ° C is in the above range, the shape can be maintained at normal temperature after molding. Further, when G' at 160 ° C is in the above range, it can be molded without entraining air bubbles. The elastic modulus (storage elastic modulus) G' and the viscosity ratio (loss elastic modulus) G'' and tan δ = G''/G' at various temperatures can be measured using a strain rheometer. The molding temperature at the time of melt molding is preferably appropriately adjusted depending on flow characteristics, film forming properties, and the like. It is preferably 0 to 230 ° C, more preferably 80 ° C or higher, and further preferably 90 ° C or higher or 160 ° C or lower. In the case of melt forming, the thickness of the sheet can be appropriately adjusted by the lip gap of the T-die, the drawing speed of the sheet, and the like. The hardened composition can be produced by irradiating the curable composition with heat and/or active energy rays to harden it. In particular, the sheet can be produced by irradiating heat and/or active energy rays to a sheet obtained by molding the curable composition. Here, examples of the active energy rays to be irradiated include free radiation such as α rays, β rays, γ rays, neutron rays, and electron beams, ultraviolet rays, visible rays, and the like, and the damage to the constituent members of the optical device is suppressed. From the viewpoint of reaction control, ultraviolet rays are preferred. In addition, the irradiation energy of the active energy ray, the irradiation time, the irradiation method, and the like are not particularly limited as long as the polymerization initiator can be activated to polymerize the acrylate component. Further, as another embodiment of the method for producing the sheet, the following curable composition may be dissolved in a suitable solvent and applied by various coating methods. However, in this embodiment, it is necessary to consider the manufacturing cost such as solvent recovery. In the case of using a coating method, in addition to the above-described active energy ray irradiation hardening, the sheet may be obtained by thermal hardening. In the case of selecting a forming method by a coating method, in addition to active energy ray hardening, a hardening composition is easily obtained by thermal hardening, and in the case of being a thermosetting composition, it is selected to have a drying temperature higher than a solvent. A polymerization initiator which decomposes at a temperature. In the case of coating, the thickness of the sheet can be adjusted by the coating thickness and the solid content concentration of the coating liquid. Further, from the viewpoint of preventing adhesion or preventing adhesion of foreign matter, a laminate obtained by forming at least one single-layer release film of the sheet is preferable. As described below, by laminating the laminate with heat and/or active energy rays, a laminate having a structure in which at least a single-layer release film of the sheet is obtained can be obtained. If necessary, embossing or various irregularities (cone or pyramid shape, or hemispherical shape, etc.) can be processed. Further, it is also possible to improve various surface treatments such as corona treatment, plasma treatment, and primer treatment for the purpose of adhering to various members to be joined. <The present curable composition> The curable composition (referred to as "the present curable composition") which is an example of the embodiment of the present invention includes a hardenable combination of an isobutylene polymer (A) and an acrylate monomer. Things. In addition, the "curable composition" means a composition having a hardenable property. As described above, the present curable composition can be formed into a sheet shape and cured, whereby the sheet can be produced. However, the method of producing the sheet is not limited to this method. The isobutylene polymer (A) constituting the curable composition may be any of the isobutylene polymers (A) described in the sheet. From the viewpoint of the sheet, the acrylate monomer constituting the curable composition preferably has a monofunctional acrylate monomer (also referred to as "monofunctional acrylate") and a polyfunctional acrylate, respectively. Monomer (also known as "polyfunctional acrylate"). The monofunctional acrylate monomer and the polyfunctional acrylate monomer in the above acrylate monomer may be the monofunctional acrylate and the polyfunctional acrylate described in the sheet, respectively. The acrylate monomer preferably contains two or more kinds of the above-mentioned monofunctional acrylate from the viewpoint of controlling the Tg after curing or suppressing crystallization. The above acrylate monomer is preferably a monofunctional acrylate comprising a long-chain alkyl chain having 10 or more carbon atoms. By selecting the above-mentioned acrylate monomer to contain a monofunctional acrylate having a long-chain alkyl chain having 10 or more carbon atoms, the intertwining between the isobutylene polymer (A) and the acrylate-based polymer (B) becomes Further, as a result, a curable composition and a sheet having excellent adhesion and retention can be obtained. In addition, the present curable composition selectively contains a long-chain alkyl acrylate having a carbon number of 10 or more, and has a large influence on the high-order structure of the curable composition, and is a two-component curable composition. Shows excellent transparency. The polyfunctional acrylate is preferably contained in the curable composition in an amount of 0.5% by mass or more and less than 10% by mass, more preferably 0.7% by mass or more or less than 9% by mass, particularly preferably 1.0% by mass or more. The above polyfunctional acrylate is contained in the range of less than 8.0% by mass. By setting the content of the polyfunctional acrylate to less than 10% by mass, bleeding can be reduced. On the other hand, transparency can be expressed by setting the content of the polyfunctional acrylate to 0.5% by mass or more. It is preferably contained in an amount of 5 parts by mass or more and less than 100 parts by mass based on 100 parts by mass of the isobutylene polymer (A). When the content of the acrylate monomer is 5 parts by mass or more, the cohesive force of the present curable composition can be effectively improved. In addition, when the content of the acrylate monomer is 100 parts by mass or less, the dispersion diameter of the acrylate-based polymer (B) in the curable composition can be reduced, and good transparency can be exhibited, and the performance is good. Transparency. In this regard, the content ratio of the acrylate monomer is preferably 5 parts by mass or more and less than 100 parts by mass based on 100 parts by mass of the isobutylene polymer (A), and more preferably 8 parts by mass or more or 90%. The amount by mass or less is further preferably 10 parts by mass or more or 80 parts by mass or less. In the above-mentioned, the curable composition is preferably a curable composition containing 5 parts by mass or more of the acrylate monomer per 100 parts by mass of the isobutylene polymer (A). It is less than 100 parts by mass, and each has a monofunctional acrylate monomer and a polyfunctional acrylate monomer as the acrylate monomer, and the above-mentioned curable composition contains 0.5% by mass or more and less than 10% of the above polyfunctional acrylate. quality%. (Polymerization Initiator) The curable composition preferably contains a polymerization initiator to obtain hardenability. The polymerization initiator is not particularly limited as long as it is a polymerization initiator which can be used for polymerization of an acrylate. For example, any one activated by heat or activated by an active energy ray can be used. Further, any one which causes a radical reaction to generate a radical reaction, a cation or an anion, and an addition reaction can be used. The preferred polymerization initiator is a photopolymerization initiator, and the choice of photopolymerization initiator is generally dependent at least in part on the particular ingredients used in the curable composition, and the desired rate of hardening. Examples of the photopolymerization initiator include phenyl ethyl ketone such as phenyl or diphenylphosphine oxide, ketone, and acridine, benzoin, benzophenone, benzamidine compound, hydrazine, and 9-oxygen. Thiopurine , phosphine oxide, etc. Specific examples include DAROCUR (Ciba Specialty Chemicals), IRGACURE (Ciba Specialty Chemicals), and 2,4,6-trimethylbenzimidyldiphenylphosphinic acid ethyl ester available as LUCIRIN TPO. Etc. can be used as a photopolymerization initiator for LUCIRIN (BASF). As a photopolymerization initiator, it is also possible to use it in an excitation wavelength region of 400 nm or more. Specific examples of the photopolymerization initiator include α-diketones such as camphorquinone and 1-phenyl-1,2-propanedione; and 2,4,6-trimethylbenzhydryldiphenyl. Ruthenium phosphine oxides such as phosphine oxide, bis(2,4,6-trimethylbenzylidene)-phenylphosphine oxide; 2-benzyl-2-dimethylamino-1-(4-oxime) Α-aminoalkylphenones such as phenylphenyl)-butanone-1, 2-methyl-1-(4-methylthiophenyl)-2-indolyl propan-1-one; A ferrocene compound such as bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl)titanium Titanium and the like. Among these, from the viewpoints of good polymerization activity and less harmfulness to living organisms, α-diketones or fluorenylphosphine oxides are preferred, and camphorquinone, 2, 4, 6- is more preferred. Trimethylbenzimidyldiphenylphosphine oxide. On the other hand, in order to form a crosslinked structure, a thermal polymerization initiator may be used in addition to the photopolymerization initiator. Examples of the thermal polymerization initiator include an azo compound, quinine, a nitro compound, a mercapto halide, an anthracene, a mercapto compound, a pyrylium compound, an imidazole, a chlorotriazine, a benzoin, and a benzoin alkyl ether. , diketone, benzophenone, and barium laurate and organic 1,1,2-di(perylene peroxide)-3,3,5-trimethylcyclohexane obtained by NOF Co. as PERHEXA TMH peroxide. The polymerization initiator is usually used in a concentration of from about 0.01 to about 10% by mass, particularly from about 0.01 to about 5% by mass, based on the total mass of the present curable composition. Mixtures of polymerization initiators can also be used. (Adhesive Additive) The curable composition may further contain an adhesion-imparting agent to improve adhesion. Usually, the isobutylene resin composition contains a large amount of an adhesion-imparting agent. However, in order to prevent a problem of a decrease in high-temperature cohesive force or a yellowing caused by the addition of an adhesion-imparting agent, the content of the adhesion-imparting agent is preferably less than 10% by mass. By setting it as this range, the hardening composition which is excellent in high-temperature cohesive force can be prepared. The adhesion-imparting agent may also be any compound or a mixture of compounds which enhances the adhesion of the present curable composition. Examples of the adhesion-imparting agent include an aliphatic hydrocarbon-based adhesion-imparting agent represented by a terpene-based adhesion-imparting agent, an aromatic hydrocarbon-based adhesion-imparting agent represented by a phenol-based adhesion-imparting agent, and a rosin-based adhesion-imparting agent. An alicyclic hydrocarbon-based adhesion-imparting agent, an adhesion-imparting agent containing the hydrocarbon-based copolymer, an epoxy-based adhesion-imparting agent, a polyamine-based adhesion-imparting agent, a ketone-based adhesion-imparting agent, and the like. Among these, from the viewpoint of compatibility, an aliphatic hydrocarbon-based adhesion-imparting agent, an aromatic hydrocarbon-based adhesion-imparting agent, an alicyclic hydrocarbon-based adhesion-imparting agent, and an adhesion of the hydrocarbon-based copolymer are preferable. The agent is given. It is especially preferred to be an aliphatic hydrocarbon-based adhesion-imparting agent. Further, these adhesion-imparting agents may be used alone or in combination of two or more. (Others) The curable composition may also contain a softening agent. The softener can, for example, adjust the viscosity of the composition to improve processability. Examples of the usable softening agent include petroleum-based hydrocarbons such as an aromatic type, a paraffin type, and a cycloalkane type, petroleum jelly, and petroleum-based pitch. However, it is not limited to these. In the embodiment in which the softening agent is used, a softening agent or a combination of a plurality of softening agents can be used. Further, in the present curable composition, the liquid isobutylene polymer is treated as an isobutylene polymer (A). Further, the curable composition may also be a filler, a rust inhibitor, a acrylamide, a hardening accelerator, a filler, a decane coupling agent, an ultraviolet absorber, a UV stabilizer, an antioxidant, a stabilizer, or the like. Several combinations are added to the curable composition. Typically, the amount of the additives is preferably selected so as not to adversely affect the hardening of the curable composition, or in such a manner as not to adversely affect the physical properties of the curable composition. (State and Form) The state and form of the curable composition are arbitrary. For example, it may be in the form of a liquid, a gel, or a solid, or may be in other states. The curable composition may be in various forms such as a sheet shape, a rod shape, a hollow shape, or another shape. Among them, for example, an unstretched sheet used as an adhesive sheet or the like can be cited. In the case where the present curable composition is in the form of a sheet, the thickness thereof is not particularly limited. For example, it is 0.01 mm or more, more preferably 0.03 mm or more, and still more preferably 0.05 mm or more. On the other hand, the upper limit is preferably 1 mm or less, more preferably 0.7 mm or less, still more preferably 0.5 mm or less. When the thickness of the curable composition in the form of a sheet is 0.01 mm or more, the workability is good, and when the thickness is 1 mm or less, the thickness of the laminate can be reduced. (Method for Producing the Curable Composition) Hereinafter, a method for producing the curable composition will be described. However, the following description is an example of a method of producing the curable composition, and the curable composition is not limited to those manufactured by the production method. The curable composition can be prepared, for example, by preparing an isobutylene polymer (A) (also referred to as "(A) component") and an acrylate monomer containing a monofunctional acrylate (also referred to as "(B) In the curable composition of the component "), the above-mentioned monofunctional acrylate is used to polymerize the component (B) to cure the curable composition, and if necessary, it is suitably processed. However, it is not limited to such a manufacturing method. For example, the above component (A) can be used by using a temperature-adjustable kneader (for example, a single-shaft extruder, a twin-screw extruder, a planetary mixer, a twin-shaft mixer, a pressure kneader, etc.). The acrylate monomer containing a monofunctional acrylate, a polymerization initiator, and an optional component are kneaded to prepare a curable composition as a precursor of the present curable composition. When various raw material resins are mixed to obtain a curable composition, various additives such as a decane coupling agent and an antioxidant may be blended with the resin in advance and supplied to the extruder, or all of the materials may be melted and mixed in advance and supplied. The masterbatch is prepared by pre-concentrating the additive only in the resin. (Sheet Forming Method) As a method of forming the above-mentioned curable composition into a sheet shape, a known method such as an extrusion casting method using a T-die, an extrusion lamination method, and a calender method can be employed. Or inflation method, etc. Among them, in terms of workability, productivity, and the like, a method of melt molding, such as an extrusion casting method and an extrusion lamination method, is preferred. In the case of selecting a melt molding without using a solvent, as the present curable composition for melt molding, a storage elastic modulus (G') in a shear at a frequency of 1 Hz in an unhardened state is preferred. It is 50,000 Pa or more at 20 ° C and 10,000 Pa or less at 160 ° C. When G' at 20 ° C is in the above range, the shape can be maintained at normal temperature after molding. Further, when G' at 160 ° C is in the above range, it can be molded without entraining air bubbles. The elastic modulus (storage elastic modulus) G' and the viscosity ratio (loss elastic modulus) G'' and tan δ = G''/G' at various temperatures can be measured using a strain rheometer. The molding temperature at the time of melt molding is appropriately adjusted depending on the flow characteristics, film forming properties, etc., and is preferably 80 to 230 ° C, more preferably 90 to 160 ° C. In the case of melt forming, the thickness of the sheet can be appropriately adjusted by the lip gap of the T-die, the drawing speed of the sheet, and the like. From the viewpoint of preventing adhesion or preventing adhesion of foreign matter, it is preferable that the present curable composition produced as described above is formed into a laminate of at least a single-layer release film of a sheet formed into a sheet. . If necessary, at least one side of the sheet may be subjected to embossing or various irregularities (cone or pyramid shape, or hemispherical shape, etc.). Further, it is also possible to improve various surface treatments such as corona treatment, plasma treatment, and primer treatment for the purpose of adhering to various members to be joined. The sheet can be produced by irradiating a sheet of the present curable composition produced as described above into a sheet by irradiating heat and/or an active energy ray. Here, examples of the active energy rays to be irradiated include free radiation such as α rays, β rays, γ rays, neutron rays, and electron beams, ultraviolet rays, visible rays, and the like, and the damage to the constituent members of the optical device is suppressed. From the viewpoint of reaction control, ultraviolet rays are preferred. In addition, the irradiation energy of the active energy ray, the irradiation time, the irradiation method, and the like are not particularly limited as long as the polymerization initiator can be activated to polymerize the acrylate. Further, when paraffin or isoparaffin is added as a softening agent, when the viscosity of the curable composition is sufficiently low, it can be used in a solvent-free state by using a die coater or a notch coater. It is coated on a film to obtain a curable composition. (Coating) Further, as another embodiment of the method for producing the curable composition, the curable composition may be dissolved in a suitable solvent and applied by various coating methods. However, in this embodiment, it is necessary to consider the manufacturing cost such as solvent recovery. In the case of using a coating method, in addition to the above-described active energy ray irradiation hardening, the present curable composition can be obtained by thermal curing. In the case where the molding by the coating method is selected, as the curing composition, in addition to the active energy ray hardening, the hardening composition which is hard-cured is easily obtained, and in the case of the thermosetting composition, it is selected to be higher than the solvent. A polymerization initiator for the decomposition temperature of the drying temperature. In the case of coating, the thickness of the sheet can be adjusted depending on the coating thickness and the solid content concentration of the coating liquid. <This Foldable Sheet> Next, a sheet which is particularly foldable in the sheet (referred to as "the present foldable sheet") will be described. In recent years, the demand for optical adhesives (OCAs) for foldable displays is increasing. When the user of the display folds, if the glass transition temperature (Tg) is in the vicinity of 0 ° C, the previous acrylic adhesive will cause a failure in the subsequent buckling of the interface. The dynamic viscoelasticity of the adhesive in the frequency region where the person can bend affects it. Therefore, it is preferred to further lower the glass transition temperature (Tg) of the adhesive while lowering the elastic modulus of the low temperature region. From this point of view, the glass transition temperature (Tg) of the present foldable sheet is preferably -15 ° C or lower, and more preferably -20 ° C or lower. Further, the glass transition temperature (Tg) of the present foldable sheet is preferably -30 ° C or more from the viewpoint of the adhesion force near the normal temperature. Preferably, the foldable sheet has a loss tangent (tan δ) at a frequency of 1 Hz at least one maximum point in the range of -30 ° C to -15 ° C. By thus maximizing the loss tangent (tan δ) in the range of -30 to -15 ° C, a sheet having good adhesion and holding power can be obtained. As described below, by making the acrylate-based polymer (B) have at least two kinds of monofunctional acrylate components different in R in the above formula (1), it is easy to set the maximum value of the tangent (tan δ) to -30 ° C. ～-15 °C range. Further, by selecting the type of the isobutylene polymer (A) and the acrylate constituting the acrylate polymer (B) and the composition ratio thereof, the maximum value of the loss tangent (tan δ) can be appropriately adjusted. Further, the maximum value of the loss tangent may be set in the range of -30 to -15 ° C by adding the following tackifier. However, it is not limited to this method. In the present foldable sheet, the acrylate-based polymer (B) preferably contains an ester portion having a large carbon number (for example, a carbon number of 12 or more) from the viewpoint of compatibility with the isobutylene polymer (A). An acrylate-based polymer having an acrylate unit structure. Therefore, a monofunctional acrylate having a hydrocarbon group having 12 or more carbon atoms is preferably used as the present curable composition of the acrylate monomer of the present curable composition and the present foldable sheet. The monofunctional acrylate has a glass transition temperature (Tg) which is relatively higher than that of a usual monofunctional acrylate, and can improve the Tg of the present curable composition and the present foldable sheet. Here, specifically, the Tg of a homopolymer of a commercially available monofunctional acrylate having a hydrocarbon group having 12 or more carbon atoms is specifically represented. It can be seen that the larger the carbon number, the higher the Tg and the Tg exceeds -15 °C. Thus, the Tg of the homopolymer containing the component is shown below in the form of "polymer Tg".・Lauryl acrylate (C12 linear, polymer Tg: -3 °C) ・Cetyl acrylate (C16 linear, polymer Tg: 35 °C) ・Stearet acrylate (C18 linear, polymer Tg: 30 ° C) ・Acetyl acrylate (C22 linear, polymer Tg: 50 ° C) In addition, when a hydrocarbon group is introduced into a chain, the Tg of the homopolymer is lower than that of a linear one having the same carbon number, but even so, The Tg of commercially available branched alkyl acrylates shown below still exceeds -15 °C. - Isostearyl acrylate (C18 branch, polymer Tg: 15 ° C (DMA)) In addition to the monofunctional acrylate having a hydrocarbon group having 12 or more carbon atoms, the present curable composition or the present foldable A polyfunctional acrylate or the like is added to the sheet to carry out crosslinking. Regarding the polyfunctional acrylate, from the viewpoint of compatibility with the isobutylene polymer (A), the acrylate having a hydrocarbon group as described below is selected, and the Tg of the curable composition obtained is further increased.・1,9-nonanediol diacrylate (C9 linear difunctional, polymer Tg: 68 ° C) ・ 1,10-decanediol diacrylate (C10 linear difunctional, polymer Tg: 91 ° C) - Tricyclodecane dimethanol diacrylate (C12 alicyclic difunctional, polymer Tg: 190 ° C) It is known that the Tg of the acrylate copolymer (B) can be obtained by the following FOX formula. FOX type: 1/Tg=W1/T1+W2/T2+・・・Wn/Tn where Tg is the theoretical glass transition temperature (K), and W1, W2, and Wn are the mass fractions of the respective monomers, T1. T2・・・Tn is the measured glass transition temperature (K) of each monomer. That is, even an acrylate-based polymer containing isostearyl acrylate having a relatively low polymer Tg as a main structural unit may be subjected to a Tg of a secondary component such as a polyfunctional acrylate or a mutual polymer with an isobutylene polymer. As a result of the action, there is a problem that the Tg of the actual curable composition does not fall below -15 °C. Thus, when it is desired to obtain a hardenable composition containing an isobutylene polymer and an acrylate polymer which is excellent in compatibility, the actual situation is that the hardening composition has a maximum tangent tangent in shear at a frequency of 1 Hz. Above -15 ° C, it is difficult to adjust it to below -15 ° C. In the present foldable sheet, the Tg of the curable composition can be drastically reduced by including at least two kinds of monofunctional acrylates in the acrylate-based polymer (B). It is considered to be caused by a change in the interaction between the side chains of the long-chain hydrocarbon group of the acrylate-based polymer (B). As a result, it can be regarded as a special phenomenon showing a Tg which is significantly lower than the Tg predicted by the above FOX formula. By this means, at least one of the loss tangent (tan δ) at a frequency of 1 Hz can be produced in at least one of the maximum hardening points in the range of -30 ° C to -15 ° C, which can be prevented from being bent. The buckling can be followed by the present foldable sheet, and a curable composition excellent in adhesion, holding power, and water vapor barrier property can be obtained. (Acrylate-based polymer (B)) The acrylate-based polymer (B) in the present foldable sheet is preferably contained in a ratio of 60 parts by mass or more based on 100 parts by mass of the acrylate-based polymer (B). The monofunctional acrylate is further preferably contained in a ratio of 70 parts by mass or more, particularly 80 parts by mass or more. When the monofunctional acrylate is 60 parts by mass or more, the cohesive force of the sheet can be effectively improved, and the favorable adhesion and retention of the curable composition can be exhibited. In the present foldable sheet, in the above formula (1) of the acrylate-based polymer (B), R is not particularly limited. However, in terms of adhesion and retention, the R is preferably a hydrocarbon group having a carbon number of 12 to 30. Further, the R may contain a double bond, a triple bond or an aromatic ring, and from the viewpoint of long-term stability, a hydrocarbon group which does not contain a double bond, a triple bond or an aromatic ring is preferable. Specific examples of the R include, for example, a mercapto group (C). ₁₀ ), undecyl (C ₁₁ ), dodecyl (C ₁₂ ), tridecyl (C ₁₃ ), tetradecyl (C ₁₄ ), pentadecyl (C ₁₅ ), cetyl (C ₁₆ ), heptadecyl (C ₁₇ ), octadecyl (C ₁₈ ), nonadecyl (C ₁₉ )Wait. Here, the acrylate-based polymer (B) is preferably a monofunctional acrylate component containing at least two kinds of R having a different carbon number in the above formula (1). By including at least two of the above-mentioned monofunctional acrylate components having different carbon numbers, it is easy to set the maximum value of the tangent (tan δ) to a range of -30 ° C to -15 ° C, which can be used as described below. An optical adhesive for a foldable display. The acrylate-based polymer (B) is preferably an acrylate having two different R groups in the above formula (1), and may be contained in three or more kinds. The acrylate-based polymer (B) constituting the sheet is preferably a monofunctional acrylate component containing at least one of the above formula (1) wherein R is a branched alkyl group. By including at least one monofunctional acrylate component in which R of the above formula (1) is a branched alkyl group, the maximum loss tangent (tan δ) of the present foldable sheet is easily set to -30 ° C to -15 ° C. The range, as described below, can be made into an optical adhesive for a foldable display. Further, it also has an advantage that it is difficult to crystallize in a normal temperature region and it is easy to express transparency. There is no particular limitation as long as it is a branched alkyl group. For example, it can be preferably exemplified: isodecyl (C ₁₀ ), iso-decyl (C ₁₁ ), isododecyl (C ₁₂ ), isotridecyl (C ₁₃ ), isotetradecyl (C ₁₄ ), isopentadecyl (C ₁₅ ), isohexadecyl (C ₁₆ ), isoheptadecyl (C ₁₇ ), iso-octadecyl (isostearyl) (C ₁₈ ), iso-heptadecyl (C ₁₉ ) a branched alkyl group. Further, the branched alkyl group may be either a second alkyl group or a third alkyl group, and the position of the branch and the number of branches are also not particularly limited insofar as they are chemically stable. The content of the monofunctional acrylate component in which R in the above formula (1) is a branched alkyl group is preferably a monofunctional acrylate in which R is a branched alkyl group with respect to 100 parts by mass of the acrylate-based polymer (B). The component is 30 parts by mass to 80 parts by mass, and more preferably 35 parts by mass or more or 75 parts by mass or less. When the content is 30 parts by mass or more, the transparency of the present foldable sheet is easily expressed. On the other hand, when it is 80 mass parts or less, it is easy to set the maximum value of the loss tangent (tan δ) of the present foldable sheet in the range of -30 ° C to -15 ° C. Hereinafter, the acrylate monomer constituting the monomer of the acrylate-based polymer (B) will be described. The monofunctional acrylate which becomes an acrylate type polymer (B) by a hardening reaction is shown by following formula (3). [Chemical 6] (wherein R represents a hydrocarbon group and R' represents hydrogen (H) or methyl (CH) ₃ As described above, the HSP of the monofunctional acrylate is preferably at a position where the HSP distance from the isobutylene polymer (A) is 5.0 or less, more preferably 4.5 or less. Examples of the monofunctional acrylate having an HSP distance of 5.0 or less from the isobutylene polymer (A) include isostearyl acrylate, isohexadecyl acrylate, stearyl acrylate, and cetyl acrylate. Isodecyl acrylate, tetradecyl acrylate, isododecyl acrylate, dodecyl acrylate, isodecyl acrylate, and the like. Further, R in the formula (3) is preferably at least one of branched alkyl groups. By including at least one monofunctional acrylate component in which R is a branched alkyl group, the maximum point of loss tangent (tan δ) of the present foldable sheet is easily set in the range of -30 ° C to -15 ° C, as described below. An optical adhesive for a foldable display can be made. Further, it also has an advantage that it is difficult to crystallize in a normal temperature region and it is easy to express transparency. The branched alkyl group may be either the second or the third, and the position of the branch and the number of the branches are also not particularly limited insofar as they are chemically stable. The present foldable sheet preferably contains a unit structure of the above formula (3) with respect to 100 parts by weight of the acrylate before the curing composition composition (hereinafter referred to as "curable composition"). The monofunctional acrylate is 60 parts by mass or more, and more preferably 70 parts by mass or more, particularly 80 parts by mass or more. The polyfunctional acrylate is an acrylate having two or more acryloxy groups and at least an acryloxy group bonded to each other via a hydrocarbon group. As an example of the polyfunctional acrylate monomer, the structure of the difunctional aliphatic acrylate monomer is shown in the following formula (4). [Chemistry 7] In the above formula (4), R represents hydrogen (H) or methyl (CH) ₃ ). The content of the polyfunctional acrylate is preferably 0.5% by mass or more and less than 10% by mass based on the present foldable sheet, and more preferably 1% by mass or more or less than 9% by mass, particularly 2% by mass or more. Or less than 8 mass%. By setting the content of the polyfunctional acrylate to 0.5% by mass or more, the transparency or cohesive force of the present foldable sheet can be improved, and on the other hand, the adhesion and retention can be expressed by less than 10% by mass. . The HSP for the polyfunctional acrylate of the present foldable sheet is preferably at a position where the HSP distance from the isobutylene polymer (A) is 9.0 or less, more preferably 8.0 or less. By setting the HSP distance to the above range, it is possible to suppress a failure related to transparency or adhesion such as bleeding. In the above formula (4), X is preferably an aliphatic hydrocarbon group or an alicyclic hydrocarbon group. Further, examples of the polyfunctional acrylate used in the present foldable sheet include 1,9-nonanediol diacrylate, 1,10-nonanediol diacrylate, and hydrogenated polybutadiene acrylate. a dialkyl acrylate having a alicyclic skeleton such as a linear alkyl diacrylate; a tricyclodecandiol diacrylate or a tricyclodecane dimethanol diacrylate; but is not limited thereto. On the other hand, in the above formula (4), X may also be a hydrocarbon group containing a multiple bond. Examples of such a polyfunctional acrylate include a product name: BAC-45 (manufactured by Osaka Organic Chemical Co., Ltd., polybutadiene-terminated diacrylate). Further, as the polyfunctional acrylate, a polyfunctional urethane urethane can also be used. From the viewpoint of compatibility with the component (A), an urethane urethane having an aliphatic polymer such as polybutadiene in the skeleton is preferred. As a commercial item, the brand name: CN9014 NS (Sartomer company) etc. are mentioned. Thus, in the above formula (4), X is not particularly limited. From the viewpoint of transparency and the like, X is preferably a hydrocarbon group containing a single bond. The polyfunctional acrylate is not limited to the difunctional acrylate, and a polyfunctional acrylate having a (meth) acrylonitrile group in an amount of 3, 4, or more than 4 may also be used. Among them, a difunctional acrylate is preferred from the viewpoint of long-term stability of the sheet and ease of low Tg of the curable composition. Further, the polyfunctional acrylate may be used alone or in combination of several kinds. <Layered body for image display device configuration and image display device> By forming a member of at least one-layer image display device of the sheet material, a laminate for image display device configuration can be formed, and the image display device can be used. The laminated body for constituting can constitute an image display device. A laminate for an image display device having a configuration in which at least a single layer of the sheet is composed of a touch panel, an image display panel, a surface protection panel, a retardation film, a polarizing film, and a color filter can be obtained. Any one or more of the group consisting of a light sheet and a flexible substrate. The image display device can be configured by using the laminate for the above-described image display device including any one or a combination of two or more of these. Further, an image display device in which the sheet is provided as the image display device constituent member on the display surface side and/or the non-display surface side may be used. For example, in a flexible OLED display of a top emission type, a light-emitting layer is formed on a resin substrate such as polyimide, and the light-emitting layer side serves as a display surface, and the sealing material can be prevented by disposing the sealing material on the non-display surface side of the resin substrate. The infiltration of water from the non-display side or the moisture absorption of the polyimine can contribute to the long life of the OLED. Moreover, the influence of the deformation of the display surface or the external force can be suppressed. The present foldable sheet can be preferably used as a constituent member of a bendable image display device. <Description of Statements> In the case of "X to Y" (where X and Y are arbitrary numbers), the meaning of "X or more and Y or less" is included unless otherwise specified. It is preferably greater than X" or "preferably less than Y". In the case of "X or above" (X is an arbitrary number) or "Y below" (Y is an arbitrary number), it also means "better than X" or "preferably not up to Y". Intention. In the case of the present invention, in the case of "acrylate", unless otherwise specified, the same meaning as the acrylate is included, and methacrylate is contained. [Examples] The present invention will be further illustrated by the following examples. However, the examples are not intended to limit the invention, regardless of the method. <Example 1> First, the compounds or materials used in Examples 1-1 to 1-2 and Comparative Examples 1-1 to 1-4 are shown below, and then, in each of Examples and Comparative Examples, The manufacturing method, and then, the evaluation method will be described. [Isobutylene polymer (A)] ・Oppanol N50 (manufactured by BASF, isobutylene polymer, Mw: 565,000 g/mol, (HSP δD: 15.1, δP: 0, δH: 0)) ・Tetrax 3T (JX Energy shares) Manufactured by the company, isobutylene polymer, Mw: 49,000 g/mol, (HSP δD: 15.1, δP: 0, δH: 0)) • Polybutene (96% by mass of isobutylene, 4% by mass of n-butene, Mw: 3,720, Mn: 1,660, (HSP δD: 15.1, δP: 0, δH: 0)) [Acrylate (B)] (i) Monofunctional aliphatic acrylate (b-1) ・S-1800ACL (Xinzhongcun) Manufactured by Chemical Industry Co., Ltd., isostearyl acrylate, a branched alkyl group having a carbon number of 18, having an acryloxy group, HSP distance from the component (A): 3.74) ・Blemmer CA Made by the company, cetyl acrylate, (HSP δD: 16.1, δP: 2.2, δH: 2.8, HSP distance from component A: 4.08)) (ii) Polyfunctional aliphatic acrylate (b-2) ・A- DCP (manufactured by Shin-Nakamura Chemical Industry Co., Ltd., tricyclodecane dimethanol diacrylate, HSP distance from (A) component: 7.77) ・A-NOD-N (manufactured by Shin-Nakamura Chemical Industry Co., Ltd., 1, 9-decanediol dipropyl Ethyl ester, HSP distance from (A) component: 7.00) ・NK Ester A-DOD-N (manufactured by Shin-Nakamura Chemical Co., Ltd., 1,10-decanediol diacrylate, (HSP δD: 16.3, δP: 3.8 δH: 4.9, HSP distance from component A: 6.64)) ・CN9014NS (manufactured by Sartomer, difunctional urethane amide of hydrogenated polybutadiene) [adhesive imparting agent] ・Quintone CX495: manufactured by ZEON Corporation Petroleum resin [antioxidant] ・Irganox 1076: Manufactured by BASF, hindered phenolic antioxidant [polymerization initiator] ・Omnirad TPO-G: manufactured by BASF, sulfhydryl phosphine oxide photopolymerization initiator, Irgacure 184 (BASF Manufactured by the company, 1-hydroxycyclohexyl phenyl ketone) <Method for producing uncured sheet> The isobutylene polymer (A), monofunctional aliphatic acrylate (b-1), polyfunctional with the composition described in Table 2 The aliphatic acrylate (b-2) and the polymerization initiator were kneaded by a Laboplastomill (manufactured by Toyo Seiki Seisakusho Co., Ltd.) at 110 ° C and 60 rpm to obtain a curable composition. Then, the melt-hardened composition was supplied to and passed through two release-treated polyethylene terephthalate films (manufactured by Mitsubishi Plastics Co., Ltd., DIAFOIL MRF38, thickness: 38 μm). The two heat rolls were laminated by laminating, and an uncured sheet having a release film on both sides and having a thickness of the curable composition layer of about 100 μm was obtained. At this time, the temperature of the heating roller was 160 ° C and the speed was 100 mm / min. <Evaluation Test of Curable Composition and Unhardened Sheet> (HSP, HSP Distance (Ra)) HSP is obtained from the chemical structure by the Y-MB method attached to HSPiP (trade name) as HSP integrated software. . The HSP distance (Ra) is set to (δD) the HSP of the acrylate (B) ₁ δP ₁ δH ₁ ), setting the HSP of the isobutylene polymer (A) to (δD) ₂ δP ₂ δH ₂ When it is calculated, it is calculated by the following formula. HSP distance (Ra) = {4 × (δD ₁ -δD ₂ ) ² +(δP ₁ -δP ₂ ) ² +(δH ₁ -δH ₂ ) ² } ^0.5 Table 1 shows the distance between HSP obtained by the Y-MB method and the representative isobutylene polymer (A) of several (b-1) components and (b-2) components. [Table 1] (Total Light Transmittance, Haze) In addition, the total light transmittance and the haze are attached to the measurement hole by peeling off the release film of one side, and the other release film is peeled off, and a haze meter is used. Manufactured by Sewing Industrial Co., Ltd., NDH5000), the total light transmittance was measured in accordance with JIS K7361-1, and the haze was measured in accordance with JIS K7136. (Dynamic viscoelasticity) The release film on both sides of the sheet obtained from the composition was peeled off and a plurality of sheets were laminated, thereby producing a sheet having a thickness of about 2 mm, and a circular shape having a diameter of 20 mm was used. Variant (manufactured by Yinghong Seiki Co., Ltd., MARS), in the bonding fixture: Φ20 mm parallel plate, strain: 0.1%, frequency: 1 Hz, temperature: -70 to 200 °C, heating rate: 3 °C/min The measurement was carried out to obtain a storage elastic modulus (G'), a loss elastic modulus (G''), and a loss tangent (tan δ) in an uncured state. <Method for Producing Hardened Sheet> Using a high-pressure mercury lamp, the cumulative light amount at 365 nm becomes 2000 mJ/cm. ² In this manner, the obtained uncured sheet was irradiated with ultraviolet rays in a state in which a release film was laminated, and the unhardened sheet was cured, and cured at 23 ° C and 50% RH for 15 hours or more, whereby a cured sheet was obtained. <Evaluation Test of Hardened Sheet> (Total Light Transmittance, Haze) The obtained cured sheet was measured in the same manner as the unhardened sheet. The results are shown in Table 2. (Dynamic viscoelasticity) The obtained cured sheet was measured in the same manner as the unhardened sheet, thereby obtaining a storage elastic modulus (G'), a loss elastic modulus (G''), and a loss tangent in a hardened state ( Tan δ). (Water vapor barrier property) After the thickness of the obtained cured sheet was measured, the double-sided release PET (polyethylene terephthalate) was peeled off, and the PET nonwoven fabric was attached thereto, and the measurement was performed by the JIS K7129B method. The water vapor transmission rate of °C and 90% Rh was evaluated by the following evaluation criteria. Good: The water vapor transmission rate is less than 20 g when converted to 100 μm. The water vapor transmission rate in the case of conversion to 100 μm is more than 20 g. In addition, in order to compare the thicknesses slightly, the hardened sheets are used. The thickness is A μm and the water vapor transmission rate is B (g/m ² ・In the case of a hardened sheet of 24 h), substitute it into the formula of A×B/100 and obtain the value when converted to 100 μm. [Table 2] The uncured sheets obtained in Examples 1-1 and 1-2 were low in haze, high in total light transmittance, and excellent in transparency. Further, the cured sheet obtained by curing the uncured sheets is also low in haze and high in total light transmittance, and has excellent transparency. Further, the cured sheet obtained in Example 1-3 was also low in haze, high in total light transmittance, and excellent in transparency. The hardened sheet of Example 1-1 had a peak value of loss tangent (tan δ) of 0.3 at a frequency of 1 Hz, and the peak of 0.3 was present at -35 ° C, so that the impact energy absorbability at the time of high-speed deformation was also excellent. Moreover, the water vapor transmission rate at 100 μm is also good, and is 20 g/m. ² ・24 hours or less. The hardened sheet of Example 1-2 has a peak value of 0.4 tantalum (tan δ) at a frequency of 1 Hz. The peak of 0.4 is present at -38 ° C, so that the impact energy absorbability at the time of high-speed deformation is also excellent. Moreover, the water vapor transmission rate at 100 μm is also good, and is 20 g/m. ² ・24 hours or less. The cured sheets of Comparative Examples 1-1 to 1-3 using only the monofunctional aliphatic acrylate (b-1) as the acrylate were high in haze and poor in transparency. The reason is considered to be that the polymerization of the monofunctional acrylate causes the phase separation of the produced polymer and the isobutylene polymer at a micron order. The cured sheet of Comparative Example 1-4 using only the polyfunctional alicyclic acrylate (b-2) as the acrylate was confirmed to be bleed out in an uncured state, and the haze of the uncured sheet was unsatisfactory. Further, the cured sheet obtained by curing the uncured sheet is also inferior in transparency. <Example 2> The compounds or materials used in Examples 2-1 to 2-3 and Comparative Examples 2-1 to 2-3 are shown below, and then the production methods in the respective examples and comparative examples are shown. Then, the evaluation method will be described. [Isobutylene polymer (A)] ・(A)-1: Oppanol N50SF (manufactured by BASF Corporation, isobutylene polymer, Mw: 565,000 g/mol, (HSP δD: 15.1, δP: 0, δH: 0)) (A)-2: Tetrax 3T (manufactured by JXTG, isobutylene polymer, Mw: 49,000 g/mol, (HSP δD: 15.1, δP: 0, δH: 0)) ・(A)-3: IP Solvent 2835 (Isobutylene polymer manufactured by Idemitsu Co., Ltd.) [Monomer of acrylate polymer (B)] (i) Monofunctional aliphatic acrylate (B)-1: S-1800 ACL (Xinzhongcun Chemical Industry Co., Ltd.) Manufactured, isostearyl acrylate, acrylate having 1 propylene decyloxy group at a branched alkyl group of carbon number 18. HSP distance from (A) component: 3.74) ・(B)-2: Blemmer CA (Manufactured by Nippon Oil Co., Ltd., cetyl acrylate, a linear alkyl group having a carbon number of 16 and having an acryloxy group acrylate. HSP distance from the component (A): 4.08) (ii) Functional acrylate, (B)-3: A-DCP (manufactured by Shin-Nakamura Chemical Co., Ltd., tricyclodecane dimethanol diacrylate, HSP distance from component (A): 7.77) ・(B)-4 :A-NOD-N (Xinzhongcun Chemical Industry Co., Ltd. Manufacture, 1,9-nonanediol diacrylate, HSP distance from (A) component: 7.00) ・(B)-5: CD595 (manufactured by Sartomer, 1,10-decanediol diacrylate, distance ( A) HSP distance of component: 6.65) [Adhesive imparting agent] ・(C)-1: YS Resin PX800 (manufactured by Yasuhara Chemical Co., Ltd., terpene resin) [Polymerization initiator] ・(D)-1: Darocure TPO ( Manufactured by BASF, 2,4,6-trimethylbenzylidene-diphenyl-phosphine oxide) <Production methods: Examples 2-1 to 2-3 and Comparative Examples 2-1 to 2-2 > The isobutylene polymer, the monofunctional aliphatic acrylate, the polyfunctional acrylate, the adhesion-imparting agent, and the polymerization initiator were prepared by using Laboplastomill (manufactured by Toyo Seiki Seisakusho Co., Ltd.) at 110 ° C and 60 rpm in the composition described in Table 3. The mixture was kneaded to obtain a curable composition as a precursor. Then, the melt-hardened composition was supplied to and passed through two release-treated polyethylene terephthalate films (manufactured by Mitsubishi Chemical Corporation, DIAFOIL MRF38, thickness: 38 μm). The two heat rolls were laminated by laminating, and a sheet-like curable composition having a release film on both sides and having a thickness of the curable composition layer of about 100 μm was obtained. At this time, the temperature of the heating roller was 160 ° C and the speed was 100 mm / min. Then, using a high-pressure mercury lamp, the cumulative light amount at 365 nm becomes 2000 mJ/cm. ² When the obtained sheet-like curable composition is irradiated with ultraviolet rays in a state in which a release film is laminated, and cured at 23° C. and 50% RH for 15 hours or more, a sheet containing a curable composition is obtained in the intermediate layer. A laminate of materials (samples). <Evaluation Test of Curable Composition and Unhardened Sheet> (HSP, HSP Distance (Ra)) HSP is obtained from the chemical structure by the Y-MB method attached to HSPiP (trade name) as HSP integrated software. . HSP distance (Ra) is set to HSD of acrylate monomer (δD ₁ δP ₁ δH ₁ ), setting the HSP of the isobutylene polymer (A) to (δD) ₂ δP ₂ δH ₂ When it is calculated, it is calculated by the following formula. HSP distance (Ra) = {4 × (δD ₁ -δD ₂ ) ² +(δP ₁ -δP ₂ ) ² +(δH ₁ -δH ₂ ) ² } ^0.5 (Dynamic viscoelasticity) The release film on both sides of the obtained laminated body was peeled off, and a plurality of sheets (samples) were stacked to prepare a sheet having a thickness of about 2 mm, which was punched into a circle having a diameter of 20 mm. The founder uses a rheometer (manufactured by Yinghong Seiki Co., Ltd., MARS), in the adhesion fixture: Φ20 mm parallel plate, strain: 0.1%, frequency: 1 Hz, temperature: -50 to 150 ° C, heating rate: 3 The measurement was carried out under the conditions of ° C/min, whereby the storage elastic modulus (G'), the loss elastic modulus (G''), and the loss tangent (tan δ) of the sheet (sample) were obtained. In particular, the result of tan δ is shown in Fig. 1. (TEM observation) The obtained sheet (sample) was dyed with ruthenium tetroxide, and a slicer EM UC7 manufactured by Leica was used to perform freeze cutting in a manner perpendicular to the sheet surface to prepare a plurality of slices having a thickness of about 80 nm. Three slices were randomly extracted from the obtained plurality of slices, and a cross section of each slice was randomly obtained at a magnification of 100 kV at an acceleration voltage of 100 kV using a transmission electron microscope "H-7650" manufactured by Hitachi. Ten sites were observed to confirm the dispersion state. At this time, the observed three slices were randomly observed with a field of view of 10 parts, and the case where "the block having a maximum diameter of 1 μm or more" was not observed in any of the fields of view was judged as "none", and any When the "block with a maximum diameter of 1 μm or more" was observed under the visual field, it was judged as "Yes". An electron micrograph of the sheet (sample) obtained in Example 2-1 is shown in Figs. 2 and 3, and an electron micrograph of the sheet (sample) obtained in Example 2-3 is shown in Figs. 4 and 5, Electron micrographs of the sheets (samples) obtained in Comparative Examples 2-1 and 2-2 are shown in Figs. 6 and 7, respectively. (Continuous force test) One of the obtained release sheets (samples) was peeled off, and the 50 μm polyethylene terephthalate film of the substrate film was bonded (Mitsubishi Resin Co., Ltd., DIAFOIL T100, thickness) 50 μm), made into a laminate. After the laminated product was cut into a length of 150 mm and a width of 10 mm, the remaining release film was peeled off, and the exposed back surface roll was pressure-bonded to soda lime glass. The laminate was subjected to autoclave treatment (60 ° C, gauge pressure: 0.2 MPa, 20 minutes) to carry out final bonding, and a sample for adhesion measurement was prepared. The adhesion to the glass (N/cm) when the peeling force measurement sample was peeled off at a peeling angle of 180° and a peeling speed of 60 mm/min was measured and evaluated by the following criteria. ○: If the force is 1 N/cm or more ×: The results of the curable composition obtained in the case where the force is less than 1 N/cm are shown in Table 3. (Retention test) The sheet (sample) having a thickness of 100 μm produced in the examples and the comparative examples was cut into 40 mm × 50 mm, and the release film of one side was peeled off, and the backing of the substrate was carried out by a hand roller. After a polyethylene terephthalate film (manufactured by Mitsubishi Plastics Co., Ltd., DIAFOIL S-100, thickness: 38 μm), it was cut into strips having a width of 25 mm × a length of 100 mm to prepare test pieces. Then, the remaining release film was peeled off and attached to a SUS plate (120 mm × 50 mm × thickness 1.2 mm) by a hand roller so that the bonding area became 25 mm × 25 mm. Thereafter, the test piece was cured in an atmosphere of 40 ° C for 15 minutes, and then the hammer of 1 kgf was attached to the test piece in a vertical direction and left to stand, and then the drop time (minutes) of the hammer was measured, and the following criteria were used. Evaluation. ○: Those who have not fallen within 30 minutes×: The results of the curable composition obtained by falling within 30 minutes are shown in Table 3. (Haze) The haze is measured by using a haze meter (NDH5000, manufactured by Nippon Denshoku Industries Co., Ltd.) on the both sides of the sheet (sample), and the total light transmittance is measured in accordance with JIS K7361-1. The haze was measured in accordance with JIS K7136. The results of the respective curable compositions obtained are shown in Table 3. (moisture resistance) After measuring the thickness of the obtained sheet (sample), the release PET on both sides was peeled off, and the PET nonwoven fabric was attached thereto, and the water vapor transmission rate at 40 ° C and 90% Rh was measured by the JIS K7129B method. The evaluation criteria were evaluated as follows. ○: Water vapor transmission rate at 20 μm is 20 g/m ² ・Under 24 h ×: Water vapor transmission rate exceeding 20 g/m when converted to 100 μm ² ・In the case of 24 h, in order to compare the thicknesses slightly differently, the thickness of the cured sheet is A μm, and the water vapor transmission rate is B (g/m). ² ・In the case of a hardened sheet of 24 h), substitute it into the formula of A×B/100 and obtain the value when converted to 100 μm. The results of the respective curable compositions obtained are shown in Table 3. [table 3] As for the sheet (sample) of the curable composition obtained in Examples 2-1 and 2-3, as shown in Figs. 2 to 5, the isobutylene polymer (A) was highly compatible with the acrylate-based polymer, and was not confirmed. In the case of a block having a maximum diameter of 1 μm or more, in other words, a dispersed phase containing a maximum diameter of 1 μm or more of the acrylate-based polymer (B) was not confirmed. In the sheet (sample) which is a curable composition obtained in Example 2-2, a bulk of a bulk having a maximum diameter of 1 μm or more was not confirmed. As is clear from the results of Table 3 and Fig. 1, the sheets (samples) which are the curable compositions obtained in Examples 2-1 to 2-3 have good adhesion, good retention, high transparency, and water. Excellent vapor barrier properties. The tangential maximum of the sheet (sample) of the sclerosing composition obtained in Comparative Examples 2-1 and 2-2 at a frequency of 1 Hz was not in the range of -20 to 20 °C. Therefore, the adhesion force when forming a sheet is poor. Further, as shown in Figs. 6 and 7, the sheet (sample) of the curable composition obtained in Comparative Examples 2-1 and 2-2 was confirmed to have a maximum diameter of 1 μm or more, i.e., an acrylate-based polymer ( B) A dispersed phase with a maximum diameter of 1 μm or more. Therefore, the transparency is poor. In Examples 2-1 to 2-3, even if the content of the isobutylene polymer (A) is large relative to the acrylate polymer (B), a large tan δ peak derived from the isobutylene polymer is not observed, and Non-Patent Literature The system using PCHMA described in 1 is different. It is a phenomenon seen when an acrylate-based polymer (B) having a monofunctional acrylate having a long-chain alkyl chain having 10 or more carbon atoms as a main component is used, and the former isobutylene polymer-based IPN (interpenetrating network) Not seen in the structure). It is presumed that the long-chain alkyl side chain of the component (B) is entangled with the molecule of the isobutylene polymer (A), and as a result, the viscoelastic behavior as a single material is exhibited. <Example 3> The compounds or materials used in Examples 3-1 to 3-6 and Comparative Examples 3-1 to 3-5 are shown below, and then the production methods in the respective examples and comparative examples are shown. Then, the evaluation method will be described. [Isobutylene polymer (A)] ・(A)-1: Oppanol N50SF (manufactured by BASF Corporation, isobutylene polymer, Mw: 565,000 g/mol, (HSP δD: 15.1, δP: 0, δH: 0)) (A)-2: Tetrax 3T (manufactured by JXTG, isobutylene polymer, Mw: 49,000 g/mol, (HSP δD: 15.1, δP: 0, δH: 0)) ・(A)-3: IP Solvent 2835 (Isobutylene polymer manufactured by Idemitsu Co., Ltd.) [Monomer of acrylate polymer (B)] (i) Monofunctional acrylate (B)-1: S-1800ALC (manufactured by Shin-Nakamura Chemical Co., Ltd., acrylic acid Isostearyl ester, an alkyl acrylate having an acryloxy group at a carbon number of 18, and an HSP distance from the component (A): 3.74) • (B)-2: Blemmer CA Made by the company, cetyl acrylate, a linear alkyl group having a carbon number of 16 and having an acryloxy group acrylate. HSP distance from the component (A): 4.08) ・(B)-3: Blemmer VA (manufactured by Nippon Oil Co., Ltd., behenyl acrylate, a linear alkyl group having a carbon number of 22, having an acryloxy group of acrylate. The HSP distance from the component (A): 3.61) (ii) Functional acrylate · (B)-4: CD595 (manufactured by Sartomer 1,10-nonanediol diacrylate, HSP distance from (A) component: 6.65) ・(B)-5: A-DCP (manufactured by Shin-Nakamura Chemical Co., Ltd., tricyclodecane dimethanol II Acrylate, HSP distance from (A) component: 7.77) ・(B)-6: CN9014NS (manufactured by Sartomer, polybutadiene-based difunctional urethane amide) [Adhesive-imparting agent (C)]・(C)-1: YS Resin PX800 (manufactured by Yasuhara Chemical Co., Ltd., terpene resin) [Polymerization initiator] ・(D)-1: Darocure TPO (manufactured by BASF, 2,4,6-trimethylbenzene) Mercapto-diphenyl-phosphine oxide) <Method for producing sheet-like curable composition> Examples of the compositions described in Tables 4 and 5 include an isobutylene polymer, a monofunctional acrylate, a polyfunctional acrylate, and an adhesion-imparting agent. And the polymerization initiator is mixed until uniform, and a curable composition which is a precursor of the curable composition of the present invention is obtained. Then, a two-layer release-treated polyethylene terephthalate film (manufactured by Mitsubishi Chemical Corporation, DIAFOIL MRF38, thickness: 38 μm) was used to develop a curable composition, and a release film was obtained on both sides. Further, the thickness of the curable composition layer is a sheet-like curable composition of about 100 μm. Then, using a high-pressure mercury lamp, the cumulative light amount at 365 nm becomes 2000 mJ/cm. ² When the obtained sheet-like curable composition is irradiated with ultraviolet rays in a state in which a release film is laminated, and cured at 23° C. and 50% RH for 15 hours or more, a sheet containing a curable composition is obtained in the intermediate layer. A laminate of materials (samples). <Evaluation Test of Curable Composition and Unhardened Sheet> (HSP, HSP Distance (Ra)) HSP is obtained from the chemical structure by the Y-MB method attached to HSPiP (trade name) as HSP integrated software. . HSP distance (Ra) is set to HSD of acrylate monomer (δD ₁ δP ₁ δH ₁ ), setting the HSP of the isobutylene polymer (A) to (δD) ₂ δP ₂ δH ₂ When it is calculated, it is calculated by the following formula. HSP distance (Ra) = {4 × (δD ₁ -δD ₂ ) ² +(δP ₁ -δP ₂ ) ² +(δH ₁ -δH ₂ ) ² } ^0.5 (Dynamic viscoelasticity) The release film on both sides of the obtained laminated body was peeled off and a plurality of sheets (samples) were stacked, thereby producing a sheet having a thickness of about 2 mm, which was punched into a circular shape having a diameter of 20 mm. The person using the rheometer (manufactured by Yinghong Seiki Co., Ltd., MARS), the bonding fixture: Φ20 mm parallel plate, strain: 0.1%, frequency: 1 Hz, temperature: -70 to 150 °C, heating rate: 3 °C The measurement was carried out under the condition of /min, whereby the storage elastic modulus (G'), the loss elastic modulus (G''), and the loss tangent (tan δ) of the sheet (sample) were obtained. (Breakability evaluation) The release film on both sides of the obtained laminate was peeled off, and a PET film having a thickness of 100 μm and a PET film having a thickness of 50 μm were bonded to both surfaces, and the laminate was subjected to autoclave treatment (60 ° C, table). The final adhesion was carried out at a pressure of 0.2 MPa for 20 minutes to prepare a sample for evaluation. For the sample for evaluation, DLDMLH-FS manufactured by YUASA SYSTEM Co., Ltd. was used, and U-shaped bending was repeated on the PET side having a thickness of 50 μm as an inner side in accordance with IEC 63715. The test conditions were 20 ° C, a frequency of 1 Hz, R = 3 mm, and 100,000 times, and the bending property was evaluated by the following criteria. ○: After bending 100,000 times, no buckling or flow marks were observed. ×: Any one of buckling and flow marks was seen after bending 100,000 times. (Continuous force test) One of the obtained release sheets (samples) was peeled off, and the 50 μm polyethylene terephthalate film of the substrate film was bonded (Mitsubishi Resin Co., Ltd., DIAFOIL T100, thickness) 50 μm), made into a laminate. After the laminated product was cut into a length of 150 mm and a width of 10 mm, the remaining release film was peeled off, and the exposed back surface roll was pressure-bonded to soda lime glass. The laminate was subjected to autoclave treatment (60 ° C, gauge pressure: 0.2 MPa, 20 minutes) to carry out final bonding, and a sample for adhesion measurement was prepared. The adhesion to the glass (N/cm) when the peeling force measurement sample was peeled off at a peeling angle of 180° and a peeling speed of 60 mm/min was measured and evaluated by the following criteria. ○: If the force is 1 N/cm or more ×: If the force is less than 1 N/cm, the results obtained for the curable composition are shown in Tables 6 and 7. (Retention test) The sheet (sample) having a thickness of 100 μm produced in the examples and the comparative examples was cut into 40 mm × 50 mm, and the release film of one side was peeled off, and the backing of the substrate was carried out by a hand roller. After a polyethylene terephthalate film (manufactured by Mitsubishi Plastics Co., Ltd., DIAFOIL S-100, thickness: 38 μm), it was cut into strips having a width of 25 mm × a length of 100 mm to prepare test pieces. Then, the remaining release film was peeled off and attached to a SUS plate (120 mm × 50 mm × thickness 1.2 mm) by a hand roller so that the bonding area became 25 mm × 25 mm. Thereafter, the test piece was cured in an atmosphere of 40 ° C for 15 minutes, and then the hammer of 1 kgf was attached to the test piece in a vertical direction and left to stand, and then the drop time (minutes) of the hammer was measured, and the following criteria were used. Evaluation. ○: Those who have not fallen within 30 minutes △: Those who have fallen within 10 minutes and have fallen within 30 minutes (within practical range) ×: Those who have fallen within 10 minutes are shown in Table 6 for the results of the curable composition. Table 7. (Haze) The haze is measured by using a haze meter (NDH5000, manufactured by Nippon Denshoku Industries Co., Ltd.) on the both sides of the sheet (sample), and the total light transmittance is measured in accordance with JIS K7361-1. The haze was measured in accordance with JIS K7136. The results of the respective curable compositions obtained are shown in Tables 6 and 7. (moisture resistance) After measuring the thickness of the obtained sheet (sample), the release PET on both sides was peeled off, and the PET nonwoven fabric was attached thereto, and the water vapor transmission rate at 40 ° C and 90% Rh was measured by the JIS K7129B method. The evaluation criteria were evaluated as follows. ○: Water vapor transmission rate at 20 μm is 20 g/m ² ・Under 24 h ×: Water vapor transmission rate exceeding 20 g/m when converted to 100 μm ² ・In the case of 24 h, in order to compare the thicknesses slightly differently, the thickness of the cured sheet is A μm, and the water vapor transmission rate is B (g/m). ² ・In the case of a hardened sheet of 24 h), substitute it into the formula of A×B/100 and obtain the value when converted to 100 μm. The results of the respective curable compositions obtained are shown in Tables 6 and 7. [Table 4] [table 5] [Table 6] [Table 7] <Production Example of Using Solvent> The isobutylene polymer, the monofunctional acrylate, the polyfunctional acrylate, the adhesion-imparting agent, and the polymerization initiator were uniformly mixed in the composition of Example 3-1 described in Table 4 to obtain A curable composition of a precursor. 100 parts by mass of the obtained curable composition was transferred to a light-shielding container, and 200 parts by mass of heptane was added thereto to be dissolved, whereby a uniform coating liquid was obtained. Then, the coating liquid was spread using an applicator on the release side of the release-treated polyethylene terephthalate film (manufactured by Mitsubishi Chemical Corporation, DIAFOIL MRF38, thickness: 38 μm), and the coating liquid was used at 120 ° C. After the dryer was dried for 15 minutes, another release-treated PET film was laminated using a hand roll to obtain a sheet-like curable composition having a release film on both sides and a thickness of the curable composition layer of about 100 μm. Then, using a high-pressure mercury lamp, the cumulative light amount at 365 nm becomes 2000 mJ/cm. ² When the obtained sheet-like curable composition is irradiated with ultraviolet rays in a state in which a release film is laminated, and cured at 23° C. and 50% RH for 15 hours or more, a sheet containing a curable composition is obtained in the intermediate layer. A laminate of materials (samples). There is no difference in various physical properties and evaluation items even when compared with a manufacturing method that does not use a solvent. The sheets obtained in Examples 3-1 to 3-6 each had a maximum point of loss tangent (tan δ) in shear at a frequency of 1 Hz in the range of -30 ° C to -15 ° C, and had excellent adhesion, Retention, bending and water vapor barrier. Further, Examples 3-1 to 3-5 were more remarkable in terms of holding power than Examples 3-6. Further, Examples 3-1 to 3-4 were more remarkable in terms of haze (transparency) than Example 3-5. However, even the haze of Examples 3-5 is practical. The sheets obtained in Comparative Examples 3-1 to 3-3 and Comparative Examples 3-5 had a maximum loss tangent (tan δ) in shear at a frequency of 1 Hz in the range of -30 ° C to -15 ° C. Buckling was observed in the evaluation of the bending property. Comparative Example 3-4 using an acrylate-based polymer composed only of a polyfunctional acrylate was inferior in terms of adhesion and retention, and a flow trace was observed at the evaluation of the bending property.

Fig. 1 is a graph showing loss tangent (tan δ) of sheets (samples) obtained in Examples 2-1 to 2-3 and Comparative Examples 2-1 to 2-2, that is, sheets (samples) after hardening treatment. . Fig. 2 is a photograph of a sheet (sample) obtained in Example 2-1, that is, a sheet (sample) after hardening treatment, by a transmission electron microscope (1000 times). Fig. 3 is a photograph of a sheet (sample) obtained in Example 2-1, that is, a sheet (sample) after hardening treatment, using a transmission electron microscope (5000 times). Fig. 4 is a photograph of a sheet (sample) obtained in Example 2-3, that is, a sheet (sample) after hardening treatment, by a transmission electron microscope (2000 times). Fig. 5 is a photograph of a sheet (sample) obtained in Example 2-3, that is, a sheet (sample) after hardening treatment, by a transmission electron microscope (5000 times). Fig. 6 is a photograph of a sheet (sample) obtained in Comparative Example 2-1, that is, a sheet (sample) after hardening treatment, by a transmission electron microscope (1000 times). Fig. 7 is a photograph of a sheet (sample) obtained in Comparative Example 2-2, that is, a sheet (sample) after hardening treatment, by a transmission electron microscope (1000 times).

Claims (17)

A sheet comprising an isobutylene polymer (A) and an acrylate polymer (B), and the above acrylate polymer (B) has a monofunctional acrylate unit having a unit structure represented by the following formula (1) And a polyfunctional acrylate unit as a structural unit, wherein the sheet has a loss tangent (tan δ) at a frequency of 1 Hz at least one maximum point in the range of -30 ° C to 30 ° C and a haze of 2.0% or less ; [Chemical 1] (wherein R represents a hydrocarbon group, and R' represents hydrogen (H) or methyl (CH ₃ )). The sheet of claim 1 has a haze of less than 1.0%. The sheet of claim 1 or 2, wherein the acrylate-based polymer (B) comprises from 60% by mass to 90% by mass of the monofunctional acrylate unit. The sheet according to any one of claims 1 to 3, wherein when the longitudinal section or the cross section of the sheet is observed by a transmission electron microscope (magnification: 1000 to 5000 times), no maximum diameter of 1 μm or more is observed. Block. The sheet of any one of Claims 1 to 4, wherein the acrylate-based polymer (B) is contained in an amount of 5 parts by mass or more and less than 100 parts by mass based on 100 parts by mass of the above-mentioned isobutylene polymer (A). The sheet according to any one of claims 1 to 5, wherein the acrylate-based polymer (B) contains a polyfunctional acrylate, and the content of the polyfunctional acrylate in the sheet is 0.5% by mass or more and is not Up to 10% by mass. A sheet according to any one of claims 1 to 6, wherein at least one of the maximum points of the tangent (tan δ) in the shear at a frequency of 1 Hz is in the range of -30 ° C to -15 ° C. The sheet according to claim 7, wherein the acrylate-based polymer (B) has at least two monofunctional acrylate components. The sheet according to claim 7 or 8, wherein the acrylate-based polymer (B) comprises at least one monofunctional acrylate component in which R of the above formula (1) is a branched alkyl group. A curable composition comprising, in an amount of 5 parts by mass or more and less than 100 parts by mass based on 100 parts by mass of the isobutylene polymer (A), and having a monofunctional acrylate monomer and a polyfunctional group, respectively. The acrylate monomer is the acrylate monomer, and the polyfunctional acrylate is contained in the curable composition in an amount of 0.5% by mass or more and less than 10% by mass. A sclerosing composition according to claim 10 which comprises at least 2 of the above monofunctional acrylates. An uncured sheet comprising the curable composition of claim 10 or 11. A sheet which is obtained by hardening an unhardened sheet of claim 12. A laminate comprising at least one single-layer release film of the sheet of any one of claims 1 to 9, or the sheet of claim 13. A laminated body for an image display device comprising the sheet according to any one of claims 1 to 9, or at least a single-layer layer of the sheet of claim 13 by a touch panel, an image display panel, a surface Any one or more of a group consisting of a protective panel, a retardation film, a polarizing film, a color filter, and a flexible substrate. An image display apparatus provided with a sheet as claimed in any one of claims 1 to 9 or as claimed in item 13. A bendable image display device provided with a sheet according to any one of claims 7 to 9 or as claimed in claim 13.