JP2018159066A - Curable composition, curing sheet, and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a curable composition capable of cross-linking and curing, and a cured sheet having low haze, high light transmittance, excellent transparency, impact energy absorption, creep resistance and water vapor barrier property. To provide. A curable composition containing a polyisobutylene resin (A) as a main component, wherein the (meth) acrylate (B) is 5 parts by mass or more and 99 parts by mass with respect to 100 parts by mass of the polyisobutylene resin (A). It contains less than a portion and has monofunctional aliphatic (meth) acrylate (b-1) and polyfunctional aliphatic (meth) acrylate (b-2) as the (meth) acrylate (B), respectively, and is cured. A curable composition in which the polyfunctional aliphatic (meth) acrylate (b-2) is less than 10% by mass based on the sex composition, and a sheet obtained from the composition. [Selection diagram] None

Description

  The present invention relates to a curable composition, a cured sheet, and an image display device. More specifically, a curable composition capable of crosslinking and curing, and a cured sheet having low haze, high light transmittance, excellent transparency, impact energy absorption, creep resistance, and water vapor barrier properties. The cured sheet is used as a sealing material and a member of an image display device.

In recent years, curved or flexible (foldable) display devices using organic light emitting diodes (OLEDs) and quantum dots (QDs) have been developed and are being widely commercialized.
Such a display device has a structure in which a plurality of film-shaped constituent members are bonded with a transparent optical adhesive (OCA) sheet. However, OCA that can relieve stress between each layer accompanying bending has been demanded. Since the OCA at the bent portion is subjected to high-speed deformation, an OCA having impact energy absorption is required. Conventionally, acrylic resin is generally used as an OCA sheet for reasons such as high transparency.
However, the conventional acrylic OCA film often has a glass transition temperature (Tg) in the temperature range of -20 to 0 ° C, and sufficiently absorbs energy in a low temperature range (for example, less than -20 ° C) corresponding to high-speed deformation. There is a problem that is not.

In addition, OLED and QD are vulnerable to water vapor, and must have a water vapor barrier property so that water vapor does not reach the light emitting element. Specifically, in the case of ^{OLED 10 -6 g / m 2 /} 24h or so, in the case of QD is said to require water vapor barrier properties of about ^{10 -2 g / m 2 / 24h} , a commercially available display device In general, a plurality of inorganic layers are disposed on both the display surface side and the non-display surface side of the light-emitting element in order to impart water vapor barrier properties. In order to achieve a high water vapor barrier property, a structure in which defects of each inorganic layer are compensated by multilayering the inorganic layer is generally used. However, in recent years, a commercially available barrier film is formed using a water vapor barrier OCA. Display devices having a structure in which the number of laminated inorganic layers is reduced by being attached to a light-emitting element are also commercially available. As described above, the OLED and the QD require a configuration that prevents water from entering the entire display device, and the importance of the display increases with the flexibility. The need for a water vapor barrier is also increasing in OCA.

  Furthermore, with the thinning of the display panel, there is a problem that when the panel is bent, the unevenness of the constituent members installed on the non-display surface side deforms the panel. In particular, in a thin device such as a smartphone or a tablet, since a battery, a computer, and various electronic devices need to be housed together in a narrow housing, the problem becomes remarkable. From such a background, there is an increasing need for an adhesive film having creep resistance that eliminates unevenness on the non-display surface side and relieves stress when bent.

  Polyisobutylene is a polymer material that may satisfy the needs for impact energy absorption and water vapor barrier properties. Polyisobutylene is susceptible to internal friction due to the influence of bulky side chains, has excellent impact energy absorption, and possesses the highest level of water vapor barrier property as a soft polymer that can be processed into an adhesive.

  As an adhesive using polyisobutylene, Patent Document 1 discloses an adhesive sheet in which a polyisobutylene is mixed with a tackifier such as petroleum resin and an oil component such as liquid paraffin.

  Patent Document 2 discloses a polyisobutylene resin having a weight average molecular weight of more than 300,000 g / mol and contained in at least 50% by mass of the total mass of the composition, and a polyfunctional (meth) of 10 to 20% by mass. An adhesive encapsulating composition is disclosed that includes an acrylate monomer and no tackifier.

  Patent Document 3 discloses a pressure-sensitive adhesive composition containing a polyisobutylene resin, a bifunctional acrylate having an alicyclic hydrocarbon, and a tackifier. In the examples, polyisobutylene is the main component. A composition containing 10 to 35% by mass of tricyclodecane dimethanol di (meth) acrylate is disclosed, and examples using trifunctional acrylate and linear bifunctional acrylate are shown as comparative examples. . That is, among polyfunctional (meth) acrylates, alicyclic bifunctional (meth) acrylates are more suitable than other types of acrylate monomers in terms of haze and holding power.

JP, 2006-186042, A Special table 2011-526629 International Publication No. 2015/129625 Pamphlet

Since the adhesive sheet disclosed in Patent Document 1 is difficult to crosslink with polyisobutylene, the flexible image display device has a problem that bending marks are formed on the display surface due to creep deformation.
The haze of the composition disclosed in Patent Document 2 is not particularly described, and transparency may be a problem when application to an image display device is considered. Patent Document 2 has many descriptions as a polyfunctional (meth) acrylate monomer, but a monomer having a plurality of (meth) acryloyl groups which are polar groups in a nonpolar polyisobutylene resin is poorly compatible. It was found that when 10% by mass or more was added, the monomer component bleeded out, resulting in a problem of deterioration in transparency.

  The composition disclosed in Patent Document 3 has no verification nor mention regarding the bleeding out of the monomer when stored in an uncured state and the accompanying deterioration in transparency. Since the composition of Patent Document 3 uses 10% by mass or more of the same type of monomer as Patent Document 2, it was found that bleeding out and the accompanying deterioration in transparency become problems.

  Accordingly, the present invention has been made to solve the above-described problems, and an object of the present invention is a curable composition that can be crosslinked and cured, as well as low haze and high light transmittance. An object of the present invention is to provide a cured sheet that is excellent in transparency, impact energy absorption, creep resistance, and water vapor barrier properties.

  The gist of the present invention is as follows.

[1] A curable composition comprising a polyisobutylene resin (A) as a main component,
Containing 5 parts by weight or more and less than 99 parts by weight of (meth) acrylate (B) with respect to 100 parts by weight of the polyisobutylene resin (A),
As said (meth) acrylate (B), it has a monofunctional aliphatic (meth) acrylate (b-1) and a polyfunctional aliphatic (meth) acrylate (b-2),
The curable composition whose content rate of the said polyfunctional aliphatic (meth) acrylate (b-2) with respect to a curable composition is less than 10 mass%.
[2] The curable composition according to [1], wherein a Hansen solubility parameter distance between the polyisobutylene resin (A) and the monofunctional aliphatic (meth) acrylate (b-1) is 5.0 or less.
[3] An uncured sheet comprising the curable composition according to [1] or [2].
[4] A laminate in which a release film is laminated on at least one side of the uncured sheet according to [3].
[5] A cured sheet obtained by curing the uncured sheet according to [3].
[6] The cured sheet according to [5], wherein the haze when formed to a thickness of 100 μm is 10% or less.
[7] Any one of the group consisting of a touch panel, an image display panel, a surface protection panel, a retardation film, a polarizing film, a color filter, and a flexible substrate on at least one side of the cured sheet according to [5] or [6] A laminate for an image display device having a configuration in which one or more types are laminated.
[8] An image display device in which the cured sheet according to [5] or [6] is provided on the non-display surface side.

  The curable composition of the present invention can be crosslinked. Further, a cured sheet obtained by curing the curable composition into a sheet form has a low haze and a high light ray transmittance, excellent transparency, excellent impact energy absorption, creep resistance, and water vapor barrier properties. Further, by using this cured sheet as a bonding material or a sealing material for a display device or the like, it is possible to contribute to thinning and flexibility of the display device or the like.

  The present invention will be described in detail below. However, the contents of the present invention are not limited to the embodiments described below.

<Curable composition>
A curable composition according to an example of an embodiment of the present invention (hereinafter sometimes referred to as “the present composition”) is a curable composition containing a polyisobutylene resin (A) as a main component, 5 parts by mass or more and less than 99 parts by mass of (meth) acrylate (B) with respect to 100 parts by mass of isobutylene resin (A). As the (meth) acrylate (B), monofunctional aliphatic (meth) acrylate (b -1) and a polyfunctional aliphatic (meth) acrylate (b-2), and the content ratio of the polyfunctional aliphatic (meth) acrylate (b-2) to the curable composition is 10 masses. Preferably, the curable composition is less than%.

  The “main component” is a component that is contained in the largest amount, and is a component that is contained in an amount of 35% by mass or more, preferably 40% by mass or more, more preferably 45% by mass or more in the entire composition. .

  The composition comprises a polyisobutylene resin (A) as a main component, and contains 5 parts by weight or more and less than 99 parts by weight of (meth) acrylate (B) with respect to 100 parts by weight of the polyisobutylene resin (A), It is preferable to have a monofunctional aliphatic (meth) acrylate (b-1) and a polyfunctional aliphatic (meth) acrylate (b-2) as the acrylate (B).

  The composition preferably has a Hansen solubility parameter (HSP) distance of 5.0 or less between the polyisobutylene resin (A) and the monofunctional aliphatic (meth) acrylate (b-1). 5 or less is more preferable. If the HSP distance between the component (A) and the component (b-1) is 5.0 or less, the compatibility between the polyisobutylene resin (A) and the monofunctional aliphatic (meth) acrylate (b-1) is It becomes favorable and can suppress bleed-out in an uncured state and deterioration of transparency due to phase separation.

Here, Hansen's solubility parameter (HSP) is an index representing the solubility of how much a certain substance is dissolved in another certain substance. HSP is a three-dimensional space in which the solubility parameter introduced by Hildebrand is divided into three components: a dispersion term δD, a polar term δP, and a hydrogen bond term δH. The dispersion term δD indicates the effect due to the dispersion force, the polar term δP indicates the effect due to the dipole force, the hydrogen bond term δH indicates the effect due to the hydrogen bond force,
δD: Energy derived from intermolecular dispersion force δP: Energy derived from intermolecular polar force δH: Energy derived from intermolecular hydrogen bonding force (Here, each unit 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 polar term reflects the dipole moment, and the hydrogen bond term reflects the action of water, alcohol, etc. Those having similar vectors by HSP can be determined to have high solubility, and the similarity of vectors can be determined by the distance of the Hansen solubility parameter (HSP distance). In addition, Hansen's solubility parameter can be used not only as a judgment of solubility, but also as an index for judging how easily a certain substance is present in another certain substance, that is, how good the dispersibility is.

In the present invention, HSP [δD, δP, δH] can be easily estimated from its chemical structure by using, for example, computer software Hansen Solubility Parameters in Practice (HSPiP). Specifically, it is obtained from the chemical structure by the Y-MB method, which is implemented in HSPiP. When the chemical structure is unknown, the chemical structure is obtained by the sphere method implemented in HSPiP from the result of the dissolution test using a plurality of solvents.
HSP distance (Ra) is, for example HSP solute (in this invention (meth) acrylate (B)) to the HSP _{(δD 1, δP 1, δH} 1) and the solvent (polyisobutylene resin in the present invention (A)) the _{(δD 2, δP 2, δH} 2) when formed into a can be calculated by the following equation.
HSP distance (Ra) = {4 × ( δD 1 -δD 2) 2 + (δP 1 -δP 2) 2 + (δH 1 -δH 2) 2} 0.5

Previously, in the polyfunctional acrylate (tricyclodecane dimethanol diacrylate) described in Patent Document 3, when a certain amount or more is added as a curing component, bleeding out occurs in an uncured state. However, the HSP distance between polyisobutylene and the polyfunctional acrylate is 7.77, and the HSP distance of 1,9-nonanediol diacrylate of the same polyfunctional aliphatic acrylate is relatively large as 7.00. It can be seen that it is larger than the HSP distance of the functional aliphatic acrylate (b-1) (see Table 1). That is, it can be seen that the polyfunctional (meth) aliphatic acrylate (b-2) has a HSP distance larger than that of the component (b-1) due to a plurality of acryloyloxy groups in the molecule.
Moreover, it can be seen from Table 1 that the HSP distance is 5.0 or less, particularly in the case of monofunctional aliphatic acrylate (b-1) having a fatty chain of branched C8 or higher.

However, even if it is a monofunctional aliphatic acrylate (b-1) having relatively good compatibility, when it is used alone as a cross-linking component, the polymer grows linearly at the time of curing. A phase separation of micrometer order from the isobutylene resin (A) occurs, and as a result, the phenomenon that the transparency of the cured product is impaired is often observed.
Therefore, in the present invention, it contains a polyfunctional aliphatic (including alicyclic) (b-2) component that does not bleed out, and introduces branching into the polymer produced by curing, thereby allowing phase separation during curing. Inhibition or phase separation on the order of nanometers can be obtained, and as a result, a cured sheet having excellent transparency can be obtained.

The content of (meth) acrylate (B) with respect to 100 parts by mass of polyisobutylene resin (A) is preferably 5 parts by mass or more and less than 99 parts by mass. The upper limit is preferably less than 95 parts by mass. About a minimum, it is more preferable that it is 7 mass parts or more especially 10 mass parts or more.
Among them, it is preferably 5 parts by mass or more and less than 50 parts by mass, more preferably 7 parts by mass or more and less than 40 parts by mass, and further preferably 10 parts by mass or more and less than 35 parts by mass. By setting the content of the mono (meth) acrylate (B) to 5 parts by mass or more, the creep resistance characteristics in a state after curing can be enhanced. Moreover, it can be set as the cured sheet which has water vapor | steam barrier property and impact energy absorptivity by setting it as 99 mass parts or less.

The content of the polyfunctional aliphatic (meth) acrylate (b-2) in the curable composition is preferably less than 10% by mass, more preferably less than 9% by mass, and less than 8% by mass. Is more preferable. Bleed out can be reduced by setting the content of the polyfunctional aliphatic (meth) acrylate to less than 10% by mass.
On the other hand, the lower limit of the content of the polyfunctional aliphatic (meth) acrylate (b-2) with respect to the curable composition is not particularly limited. For example, it is preferably 0.1% by mass or more, and more preferably 0.3% by mass or more.

As a preferable condition for melt-molding the composition, the storage elastic modulus (G ′) at a shear rate of 1 Hz is 10,000 Pa or more at 20 ° C., particularly 30,000 Pa or more, and more preferably 50,000 Pa or more. It is preferably 30,000 Pa or less at 160 ° C., more preferably 10,000 Pa or less, and most preferably 5,000 Pa or less.
When G ′ at 20 ° C. is in the above range, the shape can be maintained at room temperature when formed into a sheet. If G ′ at 160 ° C. is within the above range, molding can be performed without entraining bubbles when melt molding is performed.

  The storage elastic modulus (G ′) can be adjusted by appropriately selecting the type and amount of the polyisobutylene resin (A) and (meth) acrylate to be used.

  The elastic modulus (storage elastic modulus) G ′ at various temperatures can be measured using a strain rheometer.

  Hereinafter, the raw material which comprises this composition is demonstrated.

[Polyisobutylene resin (A)]
The polyisobutylene resin (A) used in the present invention is a polymer having an isobutylene skeleton in the main chain or side chain, and has a structural unit of the following formula (1).

  The polyisobutylene resin has a function of improving the impact energy property and water vapor barrier property of the cured sheet.

  As polyisobutylene resin (A), polyisobutylene which is a homopolymer of isobutylene, a copolymer of isobutylene and isoprene, a copolymer of isobutylene and n-butene, a copolymer of isobutylene and butadiene, and these copolymers And halogenated butyl rubber obtained by bromination or chlorination. These polymers can be used alone or in combination of two or more.

  Among these, polyisobutylene and an isobutylene / isoprene copolymer are preferable from the viewpoint of improving the durability and weather resistance of the sheet made of the present composition and reducing the water vapor transmission rate.

The isobutylene / isoprene copolymer has a repeating unit derived from isobutylene [—CH ₂ —C (CH ₃ ) ₂ —] and a repeating unit derived from isoprene [—CH ₂ —C (CH ₃ ) ═CH— in the molecule. It is a synthetic rubber having CH ₂ —].
The content of repeating units derived from isoprene in the isobutylene / isoprene copolymer is usually from 0.1 to 99 mol%, preferably from 0.5 to 50 mol%, more preferably from all repeating units. 1 to 10 mol%.
If the repeating unit derived from isoprene in the isobutylene / isoprene copolymer is in the above range, it is preferable because a curable composition having excellent moisture barrier properties can be obtained.

  The type of the isobutylene / isoprene copolymer is not particularly limited, and examples thereof include a regenerated isobutylene / isoprene copolymer and a synthetic isobutylene / isoprene copolymer. Among these, a synthetic isobutylene / isoprene copolymer is preferable.

Examples of the method for synthesizing polyisobutylene include a method in which a monomer component such as isobutylene is polymerized in the presence of a Lewis acid catalyst such as aluminum chloride or boron trifluoride.
Moreover, a commercial item can also be used as polyisobutylene (A). Examples of commercially available products include Vistanex (manufactured by Exxon Chemical Co.), Hycar (manufactured by Goodrich), Opanol (manufactured by BASF), Tetrax (manufactured by JX), and the like.

The weight average molecular weight (Mw) of the polyisobutylene resin (A) is preferably 1,000 to 2,000,000 g / mol, and more preferably 1,500 g / mol or more or 1,500,000 g / mol or less. Among them, it is more preferably 2,000 g / mol or more and 1,000,000 g / mol or less, especially 50,000 g / mol or more, especially 100,000 g / mol or more, especially 120,000 g / mol or more.
By the polyisobutylene resin (A) having a weight average molecular weight (Mw) of 1,000 g / mol or more, the fluidity of the adhesive composition becomes appropriate, and the shape is easily retained after being formed into a sheet shape. . Moreover, when it is a polyisobutylene resin (A) having a weight average molecular weight (Mw) of 2,000,000 g / mol or less, it is uniform without being powdered when mixed with (meth) acrylate (B). It can be a fluid.
Here, the weight average molecular weight (Mw) is a value measured by gel permeation chromatography using tetrahydrofuran as a solvent (GPC analysis) and converted to standard polystyrene.

Moreover, the polyisobutylene resin (A) of this invention can also be used combining 2 or more types of polyisobutylene resin (A) from which average molecular weight differs. As a polyisobutylene (A) having a bimodal molecular weight distribution, a polyisobutylene polymer having a weight average molecular weight of less than 100,000 g / mol and a polyisobutylene polymer having a weight average molecular weight of 100,000 g / mol or more are used in combination. Also good.
Thus, even if the original is a separate raw material, the polyisobutylene resin component (A) as a whole has a weight average molecular weight of 100,000 to 2,000,000 g / mol, more preferably 100,000 to 1,500. 1,000 g / mol, more preferably 100,000 to 1,000,000.

  Examples of commercially available products having a weight average molecular weight of less than 100,000 g / mol include trade name: Tetrax (JX Energy), trade name: Hymor (JX Energy), and a weight average molecular weight of 100,000 g / mol. As the above-mentioned commercial item, brand name: Opanol (BASF) is mentioned.

[Mono (meth) acrylate (B)]
(Meth) acrylate (B) is a monomer having a (meth) acryl group, and has a function of imparting curability to the composition and improving the creep resistance of the cured sheet.
(Meth) acrylate means at least one of acrylate and methacrylate.
In the present invention, low haze is achieved by containing both a monofunctional aliphatic (meth) acrylate (b-1) having 10 to 30 carbon atoms and a polyfunctional aliphatic (meth) acrylate (b-2). A sheet having high light transmittance and excellent transparency can be obtained.

  The monofunctional aliphatic (meth) acrylate (b-1) used in the present invention is a (meth) acrylate having one (meth) acryloyloxy group and an aliphatic hydrocarbon group. The structure of the aliphatic acrylate is shown in the following formula (2).

In the above formula (2), R represents an aliphatic hydrocarbon group.
In the above formula, R ′ is hydrogen (H) or a methyl group (CH ₃ ).

  The content of the monofunctional aliphatic (meth) acrylate (b-1) component with respect to the entire curable composition is preferably 3% by mass or more, preferably 5% by mass or more, and more preferably 10% by mass. That's it. By being 3% by mass or more, the creep resistance of the cured sheet can be enhanced. On the other hand, the upper limit is preferably 35% by mass or less, preferably 30% by mass or less, and more preferably 25% by mass or less. By being 35 mass% or less, the water vapor | steam barrier property and impact energy absorptivity of a cured sheet can be improved.

  Moreover, as for the monofunctional aliphatic (meth) acrylate (b-1) of this invention, the content rate of the said (b-1) with respect to the said (meth) acrylate (B) whole is 60-90 mass%. Preferably, it is 70-90 mass%. By setting it as the said range, (b-1) component can be increased with respect to the (b-2) component mentioned later, and creep resistance can also be improved, maintaining transparency.

  The aliphatic hydrocarbon group (R) is preferably an aliphatic hydrocarbon group not containing multiple bonds from the viewpoint of long-term stability of the sheet.

Among aliphatic hydrocarbon groups, monofunctional aliphatic (meth) acrylates having branched alkyl groups are less likely to crystallize during curing than (meth) acrylates having linear alkyl groups, and have low haze and high total light. It is preferable because transparency due to transmittance is easily expressed.
When the aliphatic hydrocarbon group (R) is a branched alkyl group, the upper limit of the carbon number is not limited, but it is usually 30 or less.

  Even if the aliphatic hydrocarbon group (R) is a linear alkyl group, if the carbon number is 18 or less, preferably 16 or less, crystallization by monofunctional aliphatic (meth) acrylates hardly occurs. Therefore, transparency due to low haze and high total light transmittance is easily developed.

As described above, the HSP of the monofunctional aliphatic (meth) acrylate (b-1) is preferably at a position where the HSP distance to the polyisobutylene resin (A) is 5.0 or less, and 4.5 or less. It is more preferable that it is in the position.
The monofunctional aliphatic (meth) acrylate (b-1) having a HSP distance of 5.0 or less with a typical polyisobutylene resin (A) is a monofunctional compound having 8 or more carbon atoms shown in Table 1. Aliphatic acrylate (b-1) can be mentioned, and specifically, isostearyl (meth) acrylate, isohexadecyl (meth) acrylate, stearyl (meth) acrylate, hexadecyl (meth) acrylate, isotetradecyl (meth) Examples include acrylate, tetradecyl (meth) acrylate, isododecyl (meth) acrylate, dodecyl (meth) acrylate, isodecyl (meth) acrylate, and isooctyl (meth) acrylate.

  The aliphatic mono (meth) acrylate (b-1) of the present invention may be used alone or in combination.

  When employing a coating method in sheet molding, from the viewpoint of preventing phase separation during solvent drying, a monofunctional aliphatic (meth) acrylate (b-1) having an HSP distance of 5.0 or less from the component (A) ) Is preferable, and 4.5 or less is more preferable.

  Further, when melt molding is employed in sheet molding, the aliphatic hydrocarbon group (R) has 12 or more carbon atoms, preferably 14 or more carbon atoms in that volatilization due to heat during melt molding can be suppressed to some extent.

<Polyfunctional aliphatic (meth) acrylate (b-2)>
The polyfunctional aliphatic (meth) acrylate (b-2) used in the present invention has two or more (meth) acryloyloxy groups, and at least (meth) acryloyloxy groups are bonded via a hydrocarbon group. (Meth) acrylate. The structure of a bifunctional aliphatic (meth) acrylate is shown in the following formula (3) as an example of the polyfunctional aliphatic (meth) acrylate (b-2).

In the above formula, R is hydrogen (H) or a methyl group (CH ₃ ).
X is an aliphatic hydrocarbon group or an alicyclic hydrocarbon group.

The content of the polyfunctional aliphatic (meth) acrylate (b-2) in the curable composition is preferably less than 10% by mass, more preferably less than 9% by mass, and less than 8% by mass. Is more preferable. By setting the polyfunctional aliphatic (meth) acrylate content to less than 10% by mass, bleeding out can be reduced, and in combination with the monofunctional aliphatic (meth) acrylate (b-1), transparency Can be increased.
On the other hand, the lower limit of the content of the polyfunctional aliphatic (meth) acrylate (b-2) with respect to the curable composition is not particularly limited. In particular, it is preferably 0.1% by mass or more, and more preferably 0.3% by mass or more.

The HSP of the polyfunctional aliphatic (meth) acrylate (b-2) is preferably at a position where the HSP distance to the polyisobutylene resin (A) is 9.0 or less, and at a position of 8.0 or less. Is more preferable.
In the case of the polyfunctional aliphatic (meth) acrylate (b-2), it is difficult to reduce the distance as much as the component (b-1) due to a plurality of (meth) acryloyloxy groups, but the HSP distance is within the above range. By doing so, troubles related to transparency and adhesiveness such as bleeding out can be suppressed.

  In the polyfunctional aliphatic (meth) acrylate (b-2), the aliphatic hydrocarbon group or alicyclic hydrocarbon group (X) is a hydrocarbon that does not contain multiple bonds from the viewpoint of long-term stability of the sheet. It is preferably a group.

  As polyfunctional aliphatic (meth) acrylate (b-2) used in the present invention, 1,9-nonanediol di (meth) acrylate, 1,10-decandiol di (meth) acrylate, hydrogenated polybutadiene ( Di (meth) acrylate having a linear alkyl group such as (meth) acrylate; di (meth) acrylate having an alicyclic skeleton such as tricyclodecanediol di (meth) acrylate and tricyclodecane dimethanol di (meth) acrylate However, it is not limited to these.

The polyfunctional aliphatic (meth) acrylate (b-2) is not limited to a bifunctional (meth) acrylate, and is a polyfunctional aliphatic (meta) having 3, 4, or more than 4 (meth) acryloyl groups. Acrylate (b-2) may be used, but a bifunctional (meth) acrylate is preferred from the viewpoint of long-term stability of the sheet and easy availability of the acrylate.
Moreover, the polyfunctional aliphatic (meth) acrylate (b-2) of this invention may use only 1 type, or may use several types together.

(Polymerization initiator)
The curable composition of the present invention contains a polymerization initiator in order to impart curability. The polymerization initiator is not particularly limited as long as it is a polymerization initiator that can be used for the polymerization reaction of acrylate, and any of those that are activated by heat and those that are activated by active energy rays can be used. Any of those that generate radicals to cause radical reaction and those that generate cations and anions to cause addition reaction can be used.
Preferred polymerization initiators are photopolymerization initiators, and generally the selection of the photopolymerization initiator depends at least in part on the specific components used in the curable composition and the desired cure rate.

  Examples of photopolymerization initiators include acetophenone, benzoin, benzophenone, benzoyl compounds, anthraquinone, thioxanthone, phosphine oxide, such as phenyl and diphenylphosphine oxide, ketone, and acridine. Specifically, LUCIRIN (BASF) available as trade names DAROCUR (Ciba Specialty Chemicals), IRGACURE (Ciba Specialty Chemicals) and ethyl-2,4,6-trimethylbenzoyldiphenylphosphinates available as LUCIRIN TPO A photoinitiator is mentioned.

  As the photopolymerization initiator, one having an excitation wavelength region of 400 nm or more can be selected and used. Specific photopolymerization initiators include α-diketones such as camphorquinone and 1-phenyl-1,2-propanedione; 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,4,6- Acylphosphine oxides such as trimethylbenzoyl) -phenylphosphine oxide; 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1,2-methyl-1- (4-methylthiophenyl)- Α-aminoalkylphenones such as 2-morpholinopropan-1-one; or bis (η5-2,4-cyclopentadien-1-yl) -bis (2,6-difluoro-3- (1H-pyrrole) And titanocenes such as titanocene compounds such as 1-yl) phenyl) titanium. Among these, α-diketones and acylphosphine oxides are preferable from the viewpoint of good polymerization activity and low harm to the living body, and camphorquinone and 2,4,6-trimethylbenzoyldiphenylphosphine oxide are more preferable. preferable.

On the other hand, a thermal polymerization initiator can be used in addition to the photopolymerization initiator to form a crosslinked structure.
Examples of thermal polymerization initiators include azo compounds, quinine, nitro compounds, acyl halides, hydrazones, mercapto compounds, pyrylium compounds, imidazoles, chlorotriazines, benzoins, benzoin alkyl ethers, diketones, phenones, and dilauroyl peroxide and NOF. Co. And organic peroxides such as 1,1-di (t-hexylperoxy) -3,3,5-trimethylcyclohexane available as PERHEXA TMH.

  The polymerization initiator is often used at a concentration of about 0.01 to about 10% by weight, or about 0.01 to about 5% by weight, based on the total weight of the curable composition. A mixture of polymerization initiators may be used.

[Tackifier]
In some embodiments, a tackifier may be used. In general, the tackifier may be any compound or mixture of compounds that increases the tack of the curable composition.

  The tackifier is not particularly limited, and conventionally known tackifiers can be used. For example, terpene tackifier, phenol tackifier, rosin tackifier, aliphatic petroleum resin, aromatic petroleum resin, copolymer petroleum resin, alicyclic petroleum resin, xylene resin, epoxy Examples include tackifiers, polyamide tackifiers, ketone tackifiers, elastomer tackifiers, and the like, and these can be used alone or in combination of two or more.

[Softening agent]
The curable composition may contain a softening agent. The softening agent adjusts the viscosity of the composition in order to improve processability, for example.

  Examples of softening agents that can be used include petroleum-based hydrocarbons such as aromatic, paraffinic, and naphthene types, liquid polyisobutylene resins, liquid polybutene, and liquid rubbers such as hydrogenated liquid polyisoprene or derivatives thereof, Examples include, but are not limited to, petroleum jelly and petroleum-based asphalt. In embodiments that use a softener, a single softener or a combination of softeners can be used.

[Curing accelerator]
In the curable composition of the present invention, a conventionally known curing accelerator can be added to accelerate the curing reaction. Preferable curing accelerators include thiols.

  In addition, fillers, rust inhibitors, acrylamides, silane coupling agents, UV absorbers, UV stabilizers, antioxidants, stabilizers, or some combination thereof may be added to the curable composition. The amount of additive is typically selected so as not to adversely affect the cure rate of the aliphatic mono (meth) acrylate or to adversely affect the physical properties of the curable composition.

<Uncured sheet>
The uncured sheet of the present invention is a sheet comprising the curable composition of the present invention.
The loss tangent (tan δ) in the shear at a frequency of 1 Hz of the uncured sheet of the present invention is preferably 1 or more at 160 ° C. If tan δ is 1 or more at the molding temperature, it can be determined that it is before curing.

  The haze when the uncured sheet of the present invention is formed to a thickness of 100 μm is preferably 2.5% or less, more preferably 2% or less, and particularly preferably 1.8% or less. . When the haze is 2.5% or less, the sheet can be used for a display device depending on the application.

When the uncured sheet of the present invention is formed to a thickness of 100 μm, the total light transmittance is preferably 85% or more, more preferably 88% or more, and particularly preferably 90% or more.
If the haze is 2.5% or less and the total light transmittance is 85% or less, the sheet has transparency.

In order to set the haze and the total light transmittance within the above ranges, the mass ratio of the polyisobutylene resin (A) and the (meth) acrylate (B) is within a predetermined range, and the (meth) acrylate (B) A monofunctional aliphatic (meth) acrylate (b-1) of a chain and a polyfunctional aliphatic (meth) acrylate (b-2) are used in combination, and a polyfunctional aliphatic (meth) acrylate for a curable composition It is preferable to use a curable composition having a content of (b-2) of less than 10% by mass.
Here, the total light transmittance is measured according to JIS K7361-1, and the haze is measured according to JIS K7136.

  The thickness of the uncured sheet is not particularly limited, but is preferably 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, and still more preferably 0.5 mm or less. If the thickness is 0.01 mm or more, the handleability is good, and if the thickness is 1 mm or less, it can contribute to thinning.

It is preferable to laminate a protective film on at least one surface of the uncured sheet from the viewpoint of preventing blocking and preventing foreign matter adhesion. Or you may perform embossing and various unevenness | corrugation (a cone, a pyramid shape, a hemispherical shape, etc.) processing as needed. Further, various surface treatments such as corona treatment, plasma treatment and primer treatment may be performed on the surface for the purpose of improving adhesion to various adherends.
In particular, the uncured sheet of the present invention may be a laminate in which a release film is laminated on at least one surface thereof. Here, as the release film, it is preferable to adopt a PET (polyethylene terephthalate) film subjected to release treatment from the viewpoint of light transmittance and cost.

<Curing sheet>
The cured sheet of the present invention is a sheet obtained by curing the uncured sheet of the present invention, specifically, a sheet in which a (mono) acrylate component is polymerized by heat and / or active energy rays.

The loss tangent (tan δ) in shear at a frequency of 1 Hz of the uncured sheet of the present invention is preferably less than 1 at 160 ° C. If tan δ is less than 1 at the molding temperature, it can be determined that curing has been completed.
Hereinafter, the cured sheet will be described.

The total light transmittance when the cured sheet of the present invention is formed to a thickness of 100 μm is preferably 85% or more, more preferably 88% or more, and more preferably 91% or more.
In particular, the cured sheet of the present invention preferably has a total light transmittance of 85% or more, more preferably 88% or more, and even more preferably 90% or more, regardless of the thickness.

Further, the haze when the cured sheet of the present invention is formed to a thickness of 100 μm is preferably 10% or less, more preferably 5% or less, and particularly preferably 2% or less.
When the haze is 10% or less, the sheet can be used for a display device depending on the application.
In particular, the cured sheet of the present invention preferably has a haze of 2.0% or less, more preferably less than 1.0%, and particularly preferably less than 0.9%, regardless of thickness. preferable.

In order to make the total light transmittance and haze within the above ranges, the mass ratio of the polyisobutylene resin (A) and the (meth) acrylate (B) is within a predetermined range, and the (meth) acrylate (B) A monofunctional aliphatic (meth) acrylate (b-1) of a chain and a polyfunctional aliphatic (meth) acrylate (b-2) are used in combination, and a polyfunctional aliphatic (meth) acrylate for a curable composition It is preferable to use a curable composition having a content of (b-2) of less than 10% by mass.
Here, the total light transmittance is measured according to JIS K7361-1, and the haze is measured according to JIS K7136.

  The thickness of the cured sheet is not particularly limited, but is preferably 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, and still more preferably 0.5 mm or less. If the thickness is 0.01 mm or more, the handleability is good, and if the thickness is 1 mm or less, it can contribute to the thinning of the laminate.

The cured sheet of the present invention preferably has a loss tangent (tan δ) at 160 ° C. of less than 1.0 at a shear of 1 Hz. Further, the loss tangent (tan δ) at 160 ° C. is preferably less than 0.7, and more preferably less than 0.5. If the loss tangent at 160 ° C. is less than 1.0, the sheet is excellent in creep resistance.
The lower limit is not particularly limited but is generally 0.05 or more.

  In this composition, if the (meth) acrylate (B) is less than 5 parts by mass with respect to 100 parts by mass of the polyisobutylene resin (A), the loss tangent value at 160 ° C. of the cured sheet is 1. Can be adjusted to less than zero.

In the cured sheet of the present invention, it is preferable that a peak of a loss tangent (tan δ) maximum value of 0.1 or more in shearing at a frequency of 1 Hz exists in a temperature range of −60 to −20 ° C.
Since the loss tangent (tan δ) peak at a frequency of 1 Hz exists in the temperature range of −60 ° C. to −20 ° C., the impact energy absorbability at the time of high-speed deformation is exhibited even in a state after curing.
If polybutylene resin in the composition contains isobutylene having a polymerization average molecular weight of 1,000 to 100,000 g / mol, the loss tangent (tan δ) peak of the cured sheet has a temperature of −60 ° C. to −20 ° C. It becomes easier to adjust the temperature range.

  The elastic modulus (storage elastic modulus) G ′ and the viscosity modulus (loss elastic modulus) G ″ and tan δ = G ″ / G ′ at various temperatures can be measured using a strain rheometer.

The cured sheet of the present invention is required to have a water vapor transmission rate as low as possible in order to suppress deterioration of the light emitting element due to water and improve the life of the display device.
The water vapor transmission rate in the environment of the cured sheet thickness of the present invention in terms of 100 μm (when the thickness is 100 μm) at a temperature of 40 ° C. and a relative humidity of 90% RH is preferably 20 g / m ² · 24 h or less, particularly 15 g. / M ² · 24 h or less is preferable, and 10 g / m ² · 24 h or less is particularly preferable. The lower limit is not particularly limited, but is generally 0.5 or more.
When the water vapor transmission rate is 20 g / m ² · 24 h or less, water vapor from the outside is prevented / suppressed from reaching the object to be sealed, and the water vapor barrier property is improved.
In order to make the water vapor transmission rate in the above range, it is preferable that the polyisobutylene resin (A) is contained in an appropriate amount as the curable composition.
Here, the water vapor transmission rate is measured according to JIS K7129B.
For example, when the thickness is A μm and the water vapor transmission rate is Bg / (m 2 · day), the water vapor transmission rate in terms of 100 μm thickness is obtained by applying the formula B × A / 100. Can do.

  The cured sheet of the present invention may have the structure of only the cured sheet of the present invention, or may have a structure combined with other layers. By making the structure only of the cured sheet, the film forming process can be simplified.

<Manufacturing method>
Hereinafter, the resin composition, the uncured sheet, and the method for producing the cured sheet of the present invention will be described, but the following explanation is for the method for producing the resin composition, the uncured sheet, and the cured sheet of the present invention. It is an example, and the resin composition, uncured sheet, and cured sheet of the present invention are not limited to those produced by such a production method.

There is no restriction | limiting in particular in the preparation method of the curable composition of this invention, A well-known method can be used. For example, a kneading machine (for example, a single screw extruder, a twin screw extruder, a planetary mixer, a twin screw mixer, a high shear mixer, etc.) capable of adjusting the temperature of the component (A), the component (B) and an optional component. It can be prepared by using and kneading.
When mixing various raw material resins to obtain a curable composition, various additives such as silane coupling agents and antioxidants may be blended with the resin in advance and then supplied to the extruder. All materials may be supplied after being melt-mixed, or a master batch in which only the additive is previously concentrated in the resin may be prepared and supplied.

  As a method for producing an uncured sheet from the curable composition, a known method such as an extrusion casting method using a T die, an extrusion laminating method, a calendar method, an inflation method, or the like can be employed. Among these, from the viewpoint of handling properties, productivity, and the like, a melt molding method such as an extrusion casting method and an extrusion lamination method is preferable.

When selecting a melt molding that does not use a solvent, the curable composition for melt molding has a storage elastic modulus (G ′) at a shear rate of 1 Hz in an uncured state at 50,000 Pa or more at 20 ° C. It is preferable that it is 10,000 Pa or less at 160 degreeC.
If G ′ at 20 ° C. is in the above range, the shape can be maintained at room temperature after molding. If G ′ at 160 ° C. is in the above range, molding can be performed without entraining bubbles.

  The elastic modulus (storage elastic modulus) G ′ and the viscosity modulus (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, and the like, but is preferably 80 to 230 ° C, more preferably 90 to 160 ° C.
In the case of melt molding, the thickness of the sheet can be appropriately adjusted by the lip gap of the T die, the sheet take-up speed, and the like.

  Moreover, it is preferable to laminate | stack a protective film on the single side | surface or both surfaces of an uncured sheet from a viewpoint of blocking prevention and a foreign material adhesion prevention. Or you may perform embossing and various unevenness | corrugation (a cone, a pyramid shape, a hemispherical shape, etc.) processing as needed. Further, various surface treatments such as corona treatment, plasma treatment and primer treatment may be performed on the surface for the purpose of improving adhesion to various adherends.

  A cured sheet can be produced by irradiating the uncured sheet with active energy rays. Here, as the active energy rays to be irradiated, ionizing radiation such as α rays, β rays, γ rays, neutron rays, electron rays, ultraviolet rays, visible rays, and the like can be mentioned. Ultraviolet rays are preferred from the viewpoint of reaction control. Moreover, it does not specifically limit regarding the irradiation energy of an active energy ray, irradiation time, an irradiation method, etc., A sheet | seat should just be hardened by activating a polymerization initiator and advancing bridge | crosslinking.

  As another embodiment of the method for producing an uncured sheet, although there is a problem of production cost such as solvent recovery, the curable composition of the present invention may be dissolved in an appropriate solvent and carried out using various coating techniques. I can do it. When the coating technique is used, a cured sheet can be obtained by heat curing in addition to the above active energy ray irradiation curing.

  When selecting molding by a coating technique, as the cured composition, in addition to active energy ray curing, it is easy to obtain a cured composition that is thermosetting, and in the case of a thermosetting composition, from the drying temperature of the solvent A polymerization initiator having a high decomposition temperature is selected.

  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.

<Laminated body for image display device configuration, image display device>
Before the uncured sheet is cured, the image display device constituting laminate can be formed in advance by laminating the image display device constituting member on at least one surface thereof, and the image display device constituting laminate is used. Thus, an image display device can be configured.
For example, after the uncured sheet and the structural member for constituting an image display device are heated and bonded at 80 ° C. or less to form a laminated body for constituting an image display device, heat or active energy rays are applied from the image display device constituting member side. Is applied to the uncured sheet to cure the sheet, whereby a laminate for constituting the target image display device can be formed. This cured sheet is used as a sealing material and a member of an image display device, and becomes a foldable member.
Moreover, when a thermal polymerization initiator is included, the laminated body for the target image display apparatus structure can also be formed by putting a heating process instead of irradiation of an active energy ray.

  As said image display apparatus structural member, from the group which consists of a touch panel, an image display panel, a surface protection panel, a phase difference film, a polarizing film, a color filter, and a flexible substrate, for example, from the combination of 2 or more types. The image display apparatus can be configured using the laminate for configuring the image display apparatus.

  Further, as the image display device constituent member, for example, it can be arranged on a non-display surface. For example, in a top emission type flexible OLED display, a light emitting layer is formed on a resin substrate such as polyimide, and the light emitting layer side is a display surface, but by disposing the sealing material on the non-display surface side of the resin substrate, Infiltration of water from the non-display surface side and moisture absorption of polyimide can be prevented, which can contribute to extending the life of the OLED. Further, it is possible to suppress the deformation of the display surface and the influence of external force.

[Explanation of words]
In the present specification, when expressed as “X to Y” (X and Y are arbitrary numbers), unless otherwise specified, “X is preferably greater than X” or “preferably Y”. It also includes the meaning of “smaller”.
In addition, when expressed as “X or more” (X is an arbitrary number) or “Y or less” (Y is an arbitrary number), it is “preferably greater than X” or “preferably less than Y”. Includes intentions.

  The invention is further illustrated by the following examples, which are not intended to limit the invention in any way.

  The compounds and materials used in each example are shown below.

[Polyisobutylene resin (A)]
Opanol N50 (manufactured by BASF, polyisobutylene, Mw: 56,550,000 g / mol, (HSP δD: 15.1, δP: 0, δH: 0))
Tetrax 3T (manufactured by JX Energy, polyisobutylene, Mw: 49,000 g / mol, (HSP δD: 15.1, δP: 0, δH: 0))
Polybutene (iso-butene 96% by mass, n-butene 4% by mass, Mw: 3,720 Mn: 1,660 (HSP δD: 15.1, δP: 0, δH: 0))

[(Meth) acrylate (B)]
(I) Monofunctional aliphatic (meth) acrylate (b-1))
S-1800 ACL (manufactured by Shin-Nakamura Chemical Co., Ltd., isostearyl acrylate, branched alkyl having 18 carbon atoms, one acryloyloxy group added, HSP distance from component (A): 3.74)
Blemmer CA (manufactured by NOF Corporation, cetyl acrylate, (HSP δD: 16.1, δP = 2.2, δH = 2.8, HSP distance from component A: 4.08))

(Ii) Multifunctional aliphatic (meth) acrylate (b-2))
A-DCP (manufactured by Shin-Nakamura Chemical Co., Ltd., tricyclodecane dimethanol diacrylate, HSP distance from component (A): 7.77)
A-NOD-N (manufactured by Shin-Nakamura Chemical Co., Ltd., 1.9-nonanediol diacrylate, HSP distance from component (A): 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 from component A) Distance: 6.64))
CN9014NS (Sartomer, hydrogenated polybutadiene bifunctional urethane acrylate)

[Tackifier]
・ Quinton CX495: Petroleum resin (antioxidant) manufactured by ZEON
Irganox 1076: manufactured by BASF, hindered phenol antioxidant (polymerization initiator)
-Omnirad TPO-G: manufactured by BASF, acylphosphine oxide photopolymerization initiator-Irgacure 184 (manufactured by BASF, 1-hydroxycyclohexyl phenyl ketone)

<Uncured sheet manufacturing method>
In the formulation described in Table 2, polyisobutylene resin (A), monofunctional aliphatic (meth) acrylate (b-1), polyfunctional aliphatic (meth) acrylate (b-2), and polymerization initiator are lab plasts. A curable composition was obtained by kneading at 110 ° C. and 60 rpm in a mill (manufactured by Toyo Seiki Seisakusho).
Subsequently, a melted curable composition is supplied between two sheets of polyethylene terephthalate film (Mitsubishi Resin Co., Ltd., Diafoil MRF38, thickness: 38 μm) that has been subjected to a release treatment. By passing through, sandwich lamination was performed, and release films were provided on both sides, and an uncured sheet having a curable composition layer thickness of about 100 μm was obtained.
At this time, the temperature of the heating roll was 160 ° C., and the speed was 100 mm / min.

<Evaluation test of curable composition and uncured sheet>
(HSP, HSP distance (Ra))
The HSP was obtained from the chemical structure by the Y-MB method installed in HSPiP (trade name) which is HSP integrated software.
HSP distance (Ra) was a (meth) acrylate HSP of _{(B) (δD 1, δP} 1, δH 1) and then, the HSP polyisobutylene resin _{(A) (δD 2, δP} 2, δH 2) When 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 distances between the HSPs obtained by the Y-MB method of several (b-1) components and (b-2) components and typical polyisobutylenes (A).

(Total light transmittance, haze)
Further, the total light transmittance and haze are obtained by attaching a peeled release film on one side to the measurement hole, peeling off the other release film, and using a haze meter (NDH5000, manufactured by Nippon Denshoku Industries Co., Ltd.). The total light transmittance was measured according to JIS K7361-1, and the haze was measured according to JIS K7136. For Examples 1 and 2, in addition to sheets other than a thickness of 100 μm, cured sheets having a thickness of 25 μm and 50 μm were also prepared, and haze was measured.

(Dynamic viscoelasticity)
The release film on both sides of the sheet obtained from the composition was peeled off, and a plurality of sheets were stacked to prepare a sheet having a thickness of about 2 mm, and punched into a circle with a diameter of 20 mm. A rheometer (manufactured by Eiko Seiki Co., Ltd., MARS), adhesive jig: 20 mm parallel plate, strain: 0.1%, frequency: 1 Hz, temperature: -70 to 200 ° C., temperature increase rate: 3 ° C./min. The storage elastic modulus (G ′), loss elastic modulus (G ″), and loss tangent (tan δ) in the cured state were obtained.

<Curing sheet manufacturing method>
With the obtained uncured sheet laminated with a release film, the uncured sheet is cured by irradiating ultraviolet rays with a high-pressure mercury lamp so that the integrated light quantity at 365 nm is 2000 mJ / cm ^2, and 23 ° C. and 50% RH. The cured sheet was obtained by curing for 15 hours or longer.

<Evaluation test of cured sheet>
(Total light transmittance, haze)
Using the obtained cured sheet, measurement was performed in the same manner as the uncured sheet. The results are shown in Table 2.

(Dynamic viscoelasticity)
Using the obtained cured sheet, the storage elastic modulus (G ′), loss elastic modulus (G ″), and loss tangent (tan δ) in a cured state were obtained by measuring in the same manner as the uncured sheet.

(Water vapor barrier property)
After measuring the thickness of the obtained cured sheet, the release PET on both sides was peeled off, a PET nonwoven fabric was attached instead, and the water vapor transmission rate of 40 ° C. and 90% Rh was measured by the JIS K7129B method. evaluated.
Good: Water vapor permeability in terms of 100 μm is 20 g or less Bad: Water vapor permeability in terms of 100 μm is over 20 g

In order to compare those with slightly different thicknesses, in the case of a cured sheet having a cured sheet thickness of A μm and a water vapor transmission rate of B (g / m ² · 24 h), the formula A × B / 100 is used. It applied and calculated | required the value of 100 micrometer conversion.

The uncured sheets obtained in Examples 1 and 2 had low haze and high total light transmittance and had excellent transparency. Further, cured sheets obtained by curing these uncured sheets also had excellent transparency with low haze and high total light transmittance. Furthermore, the cured sheet obtained in Example 3 also had excellent transparency with low haze and high total light transmittance.
The cured sheet of Example 1 is excellent in impact energy absorption during high-speed deformation because the peak of the loss tangent (tan δ) having a maximum value of 0.3 at −35 ° C. in shear at a frequency of 1 Hz exists. Also, the water vapor permeability in terms of 100 μm was as good as 20 g / m ² · 24 h or less.
The cured sheet of Example 2 is excellent in impact energy absorption at high-speed deformation because the peak of loss tangent (tan δ) at a frequency of 1 Hz has a peak value of 0.4 at −38 ° C. Also, the water vapor permeability in terms of 100 μm was as good as 20 g / m ² · 24 h or less.
The cured sheet of Example 3 is excellent in impact energy absorption during high-speed deformation because the peak of loss tangent (tan δ) having a maximum value of about 1.6 at −20 ° C. in shear at a frequency of 1 Hz exists.

The cured sheets of Comparative Examples 1 to 3, which used only the monofunctional aliphatic (meth) acrylate (b-1) as the (meth) acrylate, had high haze and poor transparency. This is considered to be because the polymer produced and the polyisobutylene phase-separated on the order of micrometers by the polymerization proceeding only with the monofunctional acrylate.
The cured sheet of Comparative Example 4 using only the polyfunctional alicyclic (meth) acrylate (b-2) as the (meth) acrylate was confirmed to bleed out in an uncured state, and haze was not preferred in the uncured sheet. . Further, the transparency of the cured sheet obtained by curing this uncured sheet also deteriorated.

Claims (8)

A curable composition comprising a polyisobutylene resin (A) as a main component,
Containing 5 parts by weight or more and less than 99 parts by weight of (meth) acrylate (B) with respect to 100 parts by weight of the polyisobutylene resin (A),
As said (meth) acrylate (B), it has a monofunctional aliphatic (meth) acrylate (b-1) and a polyfunctional aliphatic (meth) acrylate (b-2),
The curable composition whose content rate of the said polyfunctional aliphatic (meth) acrylate (b-2) with respect to a curable composition is less than 10 mass%.   The curable composition according to claim 1, wherein a Hansen solubility parameter distance between the polyisobutylene resin (A) and the monofunctional aliphatic (meth) acrylate (b-1) is 5.0 or less.   An uncured sheet comprising the curable composition according to claim 1.   A laminate in which a release film is laminated on at least one side of the uncured sheet according to claim 3.   A cured sheet obtained by curing the uncured sheet according to claim 3.   The cured sheet according to claim 5, wherein the haze when formed to a thickness of 100 μm is 10% or less.   At least one of the groups consisting of a touch panel, an image display panel, a surface protection panel, a retardation film, a polarizing film, a color filter, and a flexible substrate is provided on at least one side of the cured sheet according to claim 5 or 6. The laminated body for image display apparatuses provided with the structure formed by laminating | stacking.   An image display device in which the cured sheet according to claim 5 or 6 is provided on the non-display surface side.