TW202239915A - Active energy ray curable adhesive sheet, adhesive sheet equipped with mold release film, laminate, production method for laminate, laminated sheet, laminate for image display devices, flexible image display device ,adhesive sheet for flexible displays, and production method for laminate for image display devices - Google Patents

Abstract

Proposed as an adhesive sheet which, even in the case of an image display device constituent member having a step part in the surface thereof, can conform to the step and be filled up to the corners, which exhibits excellent resilience and durability even when a laminate obtained by laminating an image display device constituent member and the adhesive sheet is subjected to a bending operation at high temperature, and which exhibits excellent durability even when the laminate is subjected to a bending operation at a low temperature, is an active energy ray curable adhesive sheet that comprises an adhesive agent layer comprising a meth)acrylic polymer (A) and that satisfies the following requirements (1)-(3). (1) Strain (creep strain) is not less than 50% when thickness is 0.8-1.5 mm and a pressure of 1,000 Pa is applied for 3,600 seconds at 25 DEG C. (2) Strain (creep strain) is not less than 10% when thickness is 0.8-1.5 mm, irradiation with an active energy ray having a wavelength of 365 nm is performed such that the integrated quantity of light is 2,000-4,000 mJ/cm2, and thereafter a pressure of 1,000 Pa is applied for 180 seconds at 80 DEG C. (3) Recovery after 200% deformation at 25 DEG C as represented by the formula below is not less than 60% when irradiation with an active energy ray having a wavelength of 365 nm is performed such that the integrated quantity of light is 2,000-4,000 mJ/cm2. Recovery (%)=\{(x-y)/x\}*100 (where x is the initial strain applied in the shear direction of the adhesive sheet having a thickness of 0.8-1.5 mm, and y is the residual strain 600 seconds after release of the initial strain that has been applied for 600 seconds.).

Description

Active energy ray curable adhesive sheet, adhesive sheet with release film, laminate, method for producing laminate, laminate sheet, laminate for image display device, flexible image display device, flexible Adhesive sheet for display and laminate for image display device and manufacturing method

The present invention relates to an adhesive sheet, which can be preferably used in image display devices including curved surfaces, or bendable flexible image display devices, and the like. In particular, it relates to an adhesive sheet that can be preferably used for bonding a member for constituting an image display device having a step portion to a bonding surface, an adhesive sheet with a release film using the adhesive sheet, and a laminate A body, a method for manufacturing a laminate, a laminated sheet, a laminate for an image display device, a flexible image display device, an adhesive sheet for a flexible display, and a method for manufacturing a laminate for an image display device.

In recent years, image display devices using organic light-emitting diodes (OLEDs) or quantum dots (QDs) including curved portions, or flexible image display devices that can be bent or rolled up, are being developed and widely commercialized. change. In this kind of display device, a plurality of sheet members such as housing lens, circular polarizing plate, touch film sensor, and light emitting element form a laminated structure formed by bonding transparent adhesive sheets. The sheet can be regarded as a laminate formed by laminating components and adhesive sheets.

Regarding flexible image display devices that can be bent or rolled up, there are various problems caused by interlayer stress during bending. For example, there are cases where peeling occurs between layers during folding (the phenomenon of delamination and peeling between layers is called "delamination"), so a laminate that does not peel off even when folded is required. Furthermore, there is a demand for a laminate that quickly returns to a flat state when the screen is unfolded from the folded state. Furthermore, when the bending or winding operation is repeated, cracks may occur due to the stress applied to the member of the adherend as the adhesive sheet and eventually break, so it is also required to repeat the folding operation especially at low temperature. A durable laminate.

Regarding a foldable flexible image display device, for example, Patent Document 1 discloses an adhesive and an adhesive sheet for repeated bending devices, and a curved laminated member and a repeated bending device, which, by changing the creep compliance The product value of the change value and the change value of the relaxation modulus is set to a better range, and when it is applied to a repeated bending device and placed in a long-term bending state, after the bending state is released, it shows the following high recovery: Inhibition The deformation of the adhesive layer alleviates the influence caused by placing it in a bent state. [Prior Art Literature] [Patent Document]

Patent Document 1: Japanese Patent Laid-Open No. 2019-123826

[Problem to be Solved by the Invention]

Even if the product of the creep compliance variation value and the relaxation modulus variation value of the adhesive sheet is controlled within a better range at room temperature as disclosed in Patent Document 1, the following abnormalities sometimes occur: If the folding operation is performed at a low temperature, the influence caused by being placed in a bent state will remain, and the recovery will become insufficient; or if the folding operation is repeated at a low temperature, stress will be applied to the members of the adherend as the adhesive sheet , and component cracking occurs. Regarding the device including the adhesive sheet, it is assumed that the device is used at a high temperature due to heat generation, or it is used at a high temperature and a low temperature depending on the environment such as regions or seasons, so the adhesive sheet is required to have stable performance over a wide temperature range The properties of resilience or durability.

Also, regarding the surface of a member constituting an image display device (also referred to as "constituting member of an image display device"), there is a possibility that the surface of a member constituting an image display device may be damaged by wiring, printing, pattern development, or surface treatment. The implementation of concave and convex situation. With regard to the adhesive sheet used to bond the constituent members of the image display device with the stepped portion, the adhesive sheet is required to have a higher flow rate under the limitation that the image display device is required to be thinner and cannot be thickened. The reason is that if the adhesive sheet is thin-walled and cannot be filled to every corner in line with the step difference, air bubbles will be generated inside the adhesive layer. However, it is not easy to be stable in a wide temperature range and exhibit recovery or durability in an adhesive sheet with high fluidity when laminating.

Therefore, the present invention intends to provide an adhesive sheet, a laminate for an image display device using the same, and a method for producing the adhesive sheet, which does not cause any damage even to components of an image display device having a stepped portion on the surface. Bubbles are filled to every corner in accordance with the level difference, and it can also be exhibited when the laminated body with the structure of the image display device and the adhesive sheet is laminated in a high-temperature environment. Excellent recovery and durability, it can also show excellent durability when bending operation in low temperature environment. [Technical means to solve the problem]

The present invention proposes an active energy ray-curable adhesive sheet, which has an adhesive layer containing a (meth)acrylic polymer (A), and satisfies the following requirements (1) to (3): (1) When the thickness It is set to 0.8 mm to 1.5 mm, and when a pressure of 1000 Pa is applied for 3600 seconds at a temperature of 25°C, the deformation (creep deformation) is more than 50%; (2) When the thickness is set to 0.8 mm to 1.5 mm, and the cumulative light intensity After irradiating active energy rays with a wavelength of 365 nm at 2000-4000 mJ/ ^cm2 , when a pressure of 1000 Pa is applied at a temperature of 80 ° C for 180 seconds, the deformation (creep deformation) is more than 10%; When 4000 mJ/cm ² is irradiated with active energy rays with a wavelength of 365 nm, the recovery rate after deformation of 200% at 25°C is above 60% as represented by the following formula; recovery rate (%)={(x－y)/ x}×100 (x is the initial deformation applied to the adhesive sheet with a thickness of 0.8 mm to 1.5 mm in the shear direction, y is the residual after 600 seconds after the initial deformation is released and 600 seconds deformation).

Also, the present invention proposes an adhesive sheet with a release film, which has a structure in which the above-mentioned active energy ray-curable adhesive sheet proposed in the present invention and a release film are laminated.

In addition, the present invention proposes a laminate comprising a structure in which a release film and an image display device constituting member having a level difference of 2 μm or more on the surface to be laminated are passed through the above-mentioned components proposed by the present invention. Active energy ray-curable adhesive sheets are laminated.

In addition, the present invention proposes a method for manufacturing a laminate, which uses the above-mentioned active energy ray-curable adhesive sheet proposed by the present invention to separate the release film and the laminated surface with a step difference of 2 μm or more. The members for constituting an image display device are laminated, and the above-mentioned adhesive sheet is irradiated with active energy rays through the release film from the side of the above-mentioned release film.

Furthermore, the present invention proposes a laminated sheet having a structure in which the active energy ray-curable adhesive sheet proposed in the present invention is laminated with another adhesive sheet.

Also, the present invention proposes a laminate for an image display device, which has a structure in which two image display device constituting members are laminated through the above-mentioned active energy ray-curable adhesive sheet proposed by the present invention. configuration, and at least one of the above image display device constituting members has a level difference of 2 μm or more on the contact surface with the above adhesive sheet.

In addition, the present invention proposes an adhesive sheet for flexible displays, which is characterized in that it is provided with an adhesive layer comprising a (meth)acrylic polymer (A), has a thickness of not less than 15 μm and not more than 50 μm, and has Active energy ray curability, when bonded to a member for constituting an image display device having a step of 2 to 10 μm at an interval of 10 mm or less under the following bonding conditions, the surroundings of the above step are free Blistering: (Adhesion conditions) a) UV rays are irradiated on the adhesive sheet with a thickness of 15-50 μm so that the cumulative light intensity at 365 nm becomes 2000-4000 mJ/cm ² ; b) Pressing pressure is 0.2 MPa for 30 seconds Under certain conditions, the above-mentioned adhesive sheet is vacuum bonded to the surface of the substrate with a step difference of 2 to 10 μm at an interval of 10 mm or less; c) Under the conditions of 70°C, air pressure 0.45 MPa, and 20 minutes Autoclave processing.

In addition, the present invention proposes a method for manufacturing a laminated body for constituting an image display device, which is characterized in that the laminated system for constituting an image display device has the following structure, that is, two members 1 for constituting an image display device, 2. Composed of laminated active energy ray-curable adhesive sheets, and The above-mentioned method for manufacturing a laminate for constituting an image display device has the following steps 1 to 3, and step 3 is performed after performing steps 1 and 2: Step 1: Attach one surface of the active energy ray-curable adhesive sheet proposed by the present invention to the member 1 for constituting an image display device; Step 2: irradiating active energy rays to harden the above-mentioned active energy ray-curable adhesive sheet proposed by the present invention; Step 3: The image display device constituting member 2 is attached to the other surface of the above-mentioned adhesive sheet to form a laminate. [Effect of Invention]

Regarding the adhesive sheet proposed by the present invention, even if there is a level difference on the bonding surface of the component of the image display device as the adherend, the above-mentioned adhesive sheet can be filled in accordance with the level difference without generating air bubbles to every corner. Furthermore, the adhesive sheet proposed by the present invention exhibits excellent performance even when bending operations are performed in a high-temperature environment for a laminate having a structure in which the adhesive sheet and image display device constituent members are laminated. Recoverability and durability, even in low temperature environment for bending operation, can also show excellent durability. Therefore, for example, when the laminate is bent, bent, or wound up under high-temperature or low-temperature environments, excellent durability and resilience can be exhibited. In terms of the above aspects, the adhesive sheet proposed by the present invention can be preferably used as an adhesive sheet for a flexible display, for example.

Next, the present invention will be described based on examples of embodiments. However, the present invention is not limited to the embodiments described below.

＜This adhesive sheet＞ An adhesive sheet (referred to as "the present adhesive sheet") as an example of an embodiment of the present invention is provided with an adhesive layer (referred to as "This adhesive layer") is an active energy ray-curable adhesive sheet. The present adhesive layer in the present adhesive sheet can be formed, for example, from an adhesive composition (referred to as "the present adhesive composition"). The above-mentioned adhesive composition contains a (meth)acrylic polymer (A), especially The (meth)acrylic polymer (A) preferably contains a crosslinking agent (B) and/or a polymerization initiator (C) as the main component resin, and further optionally other components.

The above-mentioned "active energy ray-curable adhesive sheet" refers to an adhesive sheet that has the property of being curable by active energy ray, in other words, means an adhesive sheet that is curable by active energy ray and has room for curing by active energy ray. Adhesive sheet of sex. This adhesive sheet may be hardened in a state where there is room for hardening by active energy rays (also called "temporarily hardened"), or it may not have undergone any hardening (called "uncured") and may be Those hardened by active energy rays. If this adhesive sheet is temporarily hardened or not hardened, it can be hardened by active energy rays (also called "full hardening") before or after attaching this adhesive sheet to the adherend. The sheet, as a result, can improve cohesion and improve adhesion.

In addition, the above-mentioned "main component resin" means the resin having the highest mass ratio among the resins constituting the present adhesive layer or the present adhesive composition. Among the resins constituting the present adhesive layer or present adhesive composition, the content of the main component resin may account for 70% by mass or more, especially 80% by mass or more, 90% by mass or more (including 100% by mass).

＜Creep characteristics＞ Regarding the adhesive sheet, when the thickness is 0.8 mm to 1.5 mm and a pressure of 1000 Pa is applied at a temperature of 25° C. for 3600 seconds, the deformation (creep deformation) is preferably 50% or more. In this adhesive sheet, in the state before hardening, the creep deformation when a pressure of 1000 Pa is applied for 3600 seconds at a temperature of 25°C is 50% or more. In the case where the surface of the image display device constituting the body has unevenness, it can fit to every corner of the step portion, so it is preferable. From this point of view, the above-mentioned creep deformation of the adhesive sheet is preferably 50% or more, especially more preferably 100% or more, especially 105% or more, especially 110% or more. On the other hand, regarding the upper limit, the aforementioned creep deformation is preferably 10000% or less in terms of maintaining the shape at room temperature or lower. From this point of view, the above-mentioned creep deformation of the adhesive sheet is more preferably 5000% or less, especially more preferably 2500% or less, further preferably 1000% or less, especially preferably 500% or less, especially 250% or less.

As mentioned above, the above-mentioned creep deformation in this adhesive sheet refers to the value when the thickness is set to 0.8 mm to 1.5 mm. In order to accurately measure the creep deformation of this adhesive sheet, it is necessary to avoid damage caused by Insufficient thickness caused by the influence of the measurement fixture will change the measurement results. Therefore, it is necessary to adjust the adhesive sheet to a fixed thickness range for measurement. By adjusting the thickness of the adhesive sheet in advance to measure the creep deformation within the above range, the creep deformation of the adhesive sheet can be accurately grasped without being affected by the measurement fixture.

Furthermore, the above-mentioned "setting the thickness to 0.8 mm to 1.5 mm" means that when the thickness of the adhesive sheet used as the measurement sample does not conform to the range, how many sheets are stacked to adjust the thickness of the measurement sample to the range. In other tests, the same applies when the thickness of the sample is specified.

In this adhesive sheet, in order to adjust the creep deformation to the above range, it is preferable to adjust the composition or molecular weight of the (meth)acrylic polymer (A), or adjust the type or amount of the crosslinking agent (B) . However, it is not limited to this means.

Also, for this adhesive sheet, after the thickness is set to 0.8 mm to 1.5 mm, and the cumulative light intensity is 2000 to 4000 mJ/ ^cm2 after irradiating active energy rays with a wavelength of 365 nm, a pressure of 1000 Pa is applied at a temperature of 80°C for 180 seconds. , the deformation (creep deformation) is preferably 10% or more. After hardening, the adhesive sheet has a deformation (creep deformation) of 10% or more when a pressure of 1000 Pa is applied at a temperature of 80°C for 180 seconds. Even after hardening, it is easy to deform under heating, so even in In the case where the image display device constituting member to be an adherend has unevenness on the surface, it can also be heated after hardening, and then fitted to each corner of the step part, and the step part can be absorbed until the surface becomes smooth . From this point of view, the creep deformation after active energy ray hardening is more preferably 10% or more, especially preferably 20% or more, especially 30% or more, and further preferably 40% or more. On the other hand, regarding the upper limit of the above-mentioned deformation (creep deformation) after hardening, if the upper limit is too high, there is a possibility that the adhesive sheet may protrude from the end surface of the laminate under a high temperature environment. , the end surface becomes sticky, or agglutination and peeling occur when bending, or damage recovery when unfolded from the bent state, so the upper limit is preferably 500% or less, more preferably 300% or less, and more preferably 100% Below, preferably below 80%, most preferably below 60%.

Furthermore, the above-mentioned creep deformation of the above-mentioned adhesive sheet after active energy ray hardening is also the same as the above, and the thickness of the adhesive sheet is adjusted to 0.8 mm to 1.5 mm for measurement. The reason is considered as described above. The influence caused by the measuring fixture does not mean that the thickness of the adhesive sheet must be within the above range.

In this adhesive sheet, in order to adjust the creep deformation after active energy ray curing to the above range, it is preferable to adjust the composition or molecular weight of the following (meth)acrylic polymer (A) as the base polymer, Or adjust the type or amount of crosslinking agent (B), or adjust the irradiation amount of active energy rays. However, it is not limited to this means.

<Recovery> Regarding this adhesive sheet, when irradiated with active energy rays with a wavelength of 365 nm at a cumulative light intensity of 2000 to 4000 mJ/cm ² , the recovery rate after deformation of 200% at 25°C represented by the following formula is better more than 60%.

This response rate is represented by the following formula. Response rate (%) = {(x－y)/x}×100 (x is the initial deformation applied to the adhesive sheet with a thickness of 0.8 mm to 1.5 mm in the shear direction, y is the residual deformation after 600 seconds after the initial deformation is released and 600 seconds after the initial deformation is applied. More specific The measuring method is described in the embodiment)

If the recovery rate of the adhesive sheet after hardening is 60% or more, permanent deformation can be suppressed, and the recovery property is also good when unfolded from a bent state. From this point of view, the above-mentioned response rate is preferably 70% or more, especially more preferably 75% or more, especially 80% or more.

Furthermore, regarding the recovery rate of the above-mentioned adhesive sheet, it is the same as above, and the thickness of the adhesive sheet is adjusted to 0.8 mm to 1.5 mm for measurement. However, it does not mean that the thickness of the adhesive sheet must be within the above range.

＜Gel fraction＞ The present adhesive sheet is preferably in an uncrosslinked state or a slightly crosslinked state, that is, a state in which the gel fraction is 0% to 20% before hardening by active energy rays. From the viewpoint of conformability to unevenness on the surface to be adhered, the gel fraction is more preferably 10% or less, further preferably 8% or less, still more preferably 5% or less.

Also, regarding this adhesive sheet, if it is cured by irradiating active energy rays with a wavelength of 365 nm at a cumulative light intensity of 2000 to 4000 mJ/ ^cm2 , the gel fraction will increase compared with that before hardening, which is preferable. More than 10% and less than 85%. By setting the gel fraction after active energy ray hardening to 10% or more, it is possible to impart shape stability to the adhesive sheet, or recovery or durability when bent when it is made into a laminate. From this point of view, the gel fraction after curing with active energy rays is preferably at least 10%, more preferably at least 30%, and most preferably at least 40%. On the other hand, the gel fraction after active energy ray hardening is preferably 85% or less.

Furthermore, when pasting this adhesive sheet hardened by active energy rays, if the gel fraction after curing by active energy rays is not too high, it will have a certain degree of flexibility, so even if the adherend is the surface The components of the image display device having the stepped portion can also be filled to every corner in accordance with the stepped portion without generating air bubbles. From this point of view, the gel fraction after curing with active energy rays is more preferably 70% or less, further preferably 60% or less, and particularly preferably 55% or less.

Also, even if this adhesive sheet is irradiated with active energy rays with a wavelength of 365 nm at a cumulative light intensity of 1000 mJ/cm ² to harden it, the gel fraction does not change or reaches 0.5 % increase. The present adhesive sheet may also be a slow-sensitivity one in this way.

In this adhesive sheet, in order to adjust the gel fraction after hardening to the above range, it is preferable to adjust the composition or molecular weight of the (meth)acrylic polymer (A) as the base polymer, or to adjust the crosslinking The type or amount of agent (B), or adjust the intensity of the irradiated active energy rays or the cumulative amount of light. However, it is not limited to these means.

＜Adhesion＞ This adhesive sheet preferably has the following characteristic (4). (4) Under the conditions of 23°C, 50%RH, peeling angle of 180°, and peeling speed of 300 mm/min, the adhesion to the surface of soda-lime glass is above 1 N/cm

When the adhesive force is 1 N/cm or more, positioning or temporary fixation at the time of laminating components of an image display device described later becomes easier, which is preferable. From this point of view, the adhesive force is preferably 1 N/cm or more, more preferably 2 N/cm or more, further preferably 4 N/cm or more, especially preferably 5 N/cm or more, more preferably 10 N/cm or more. N/cm above. Also, usually, the upper limit is 40 N/cm.

Moreover, it is preferable that this adhesive sheet has the following characteristic (5). (5) After bonding the adhesive sheet to the soda-lime glass, when irradiating active energy rays with a wavelength of 365 nm at a cumulative light intensity of 2000-4000 mJ/ ^cm2 , at 23°C 50%RH, peeling angle 180°, and peeling speed 300 Under the condition of mm/min, the adhesion to the surface of the above-mentioned soda-lime glass is more than 1 N/cm

If the adhesive force is 1 N/cm or more, when it is laminated with the following image display device components to form a laminate, it will not peel off when it is bent, and the durability will become good, so it is preferable. . From this point of view, after bonding to soda lime glass, the adhesive force when irradiated with active energy rays is preferably 1 N/cm or more, more preferably 2 N/cm or more, and still more preferably 3 N/cm or more. More preferably, it is 5 N/cm or more. Also, usually, the upper limit is 40 N/cm.

Moreover, it is preferable that this adhesive sheet further has the following characteristic (6). (6) When irradiating active energy rays with a wavelength of 365 nm at a cumulative light intensity of 2000 to 4000 mJ/ ^cm2 , and then bonding the adhesive sheet to soda-lime glass, at 23°C 50% RH, peeling angle 180°, Under the condition of peeling speed of 300 mm/min, the adhesion to the surface of the above-mentioned soda-lime glass is more than 1 N/cm

If the adhesive force is 1 N/cm or more, when it is laminated with the following image display device components to form a laminate, it will not peel off when it is bent, and the durability will become good, so it is preferable. . From this point of view, after curing the active energy ray of the present adhesive sheet, the adhesive force when it is bonded to soda lime glass is preferably 1 N/cm or more, more preferably 2 N/cm or more, and still more preferably 2 N/cm or more. 3 N/cm or more, more preferably 5 N/cm or more. Also, usually, the upper limit is 40 N/cm.

＜Loss tangent (tanδ)＞ Regarding this adhesive sheet, the thickness is set to 0.8 mm to 1.5 mm, and the loss tangent obtained by dynamic viscoelasticity measurement in a shear mode at a frequency of 1 Hz is preferably 0.8 or more at -30°C. It is more preferably 1 or more, especially 1.2 or more, still more preferably 1.5 or more, and more preferably 2.0 or less, and still more preferably 1.8 or less. Since the loss tangent (tanδ) of the present adhesive sheet is within the above range, even when the adherend surface of the adherend has unevenness, the adhesive resin can be flow-filled to the step portion by heating. Words are better.

Also, this adhesive sheet has a thickness of 0.8 mm to 1.5 mm after active energy ray hardening, that is, after irradiating active energy rays with a wavelength of 365 nm at a cumulative light intensity of 2000 to 4000 mJ/cm ² . The loss tangent obtained by the dynamic viscoelasticity measurement in the 1 Hz shear mode is preferably not less than 0.5 and not more than 2.3 in the range of -30°C to -10°C. Since the loss tangent (tanδ) after hardening is within the above range, even if the laminate using this adhesive sheet is bent in a low temperature environment, it will not cause peeling or buckling of the interface of the constituent members of the image display device. It is preferable for cracking of constituent members of a display device, etc. From this point of view, the loss tangent (tan δ) in the range of -30°C to -10°C is preferably 0.5 to 2.3, more preferably 0.8 to 2.0, and even more preferably 1.1 or more or Below 1.9.

Also, in the present invention, when the thickness of the above-mentioned adhesive sheet is set to 0.8 mm to 1.5 mm, and the dynamic viscoelasticity measurement is performed in a shear mode with a frequency of 1 Hz, the maximum point of the obtained loss tangent is better below -20°C. Since the maximum point of the loss tangent is -20° C. or lower, durability at the time of bending when forming a laminate can be imparted, which is preferable in this point. From this point of view, the maximum point of the loss tangent is more preferably -25°C or lower, more preferably -30°C or lower, still more preferably -33°C or lower, especially preferably -35°C or lower. Also, usually, the lower limit is -60°C or higher.

Furthermore, regarding the loss tangent of the above-mentioned adhesive sheet before or after curing, the same as above, the thickness of the adhesive sheet is adjusted to 0.8 mm to 1.5 mm for measurement. The reason is considered as described above. The influence caused by the measurement fixture does not mean that the thickness of the adhesive sheet must be within the above range.

In order to adjust the loss tangent (tanδ) of the adhesive sheet before or after hardening, it is preferable to adjust the composition or molecular weight of the following (meth)acrylic polymer (A) as the base polymer, or to adjust the crosslinking The type or amount of agent (B), or adjust the irradiation dose of active energy rays. However, it is not limited to this means.

＜Storage modulus (G')＞ Regarding this adhesive sheet, the thickness is set at 0.8 mm to 1.5 mm, and the storage modulus (G') obtained by dynamic viscoelasticity measurement under the shear mode at a temperature of 25°C and a frequency of 1 Hz is preferably 0.01 to 1.5 mm. 0.2 MPa. With the above-mentioned storage modulus (G') of the adhesive sheet within this range, even when the adhered surface of the adherend has unevenness, the effect of absorbing the unevenness can be obtained by matching the unevenness. The way of bonding and so on. From this point of view, the above-mentioned storage modulus (G') of the adhesive sheet is preferably 0.01 MPa to 0.2 MPa at a temperature of 25°C and a frequency of 1 Hz, especially preferably 0.02 MPa to 0.1 MPa, In particular, it is more preferably 0.03 MPa or more or 0.09 MPa or less.

Also, for this adhesive sheet, after hardening with active energy rays, that is, after irradiating active energy rays with a wavelength of 365 nm at a cumulative light intensity of 2000 to 4000 ^mJ /cm The storage modulus (G') obtained by the dynamic viscoelasticity measurement under the shear mode at ℃ and a frequency of 1 Hz is preferably not less than 0.02 MPa and not more than 0.24 MPa. When the above-mentioned storage modulus (G') of the adhesive sheet after hardening is within this range, when it is laminated with the following image display device constituent members to form a laminate, delamination, etc. will not occur when it is bent. , the durability becomes good. From this point of view, the above-mentioned storage modulus (G') of the adhesive sheet after hardening is preferably 0.02 MPa or more and 0.24 MPa or less at a temperature of 25°C and a frequency of 1 Hz, especially preferably 0.03 MPa or more or 0.20 MPa or less, especially more preferably 0.04 MPa or more or 0.10 MPa or less.

Furthermore, regarding the storage modulus (G') of the above-mentioned adhesive sheet before or after curing, it is the same as the above, and the thickness of the adhesive sheet is adjusted to 0.8 mm to 1.5 mm for measurement. The reason is as above The consideration of the influence caused by the measuring fixture does not mean that the thickness of the adhesive sheet must be within the above range.

In order to adjust the storage modulus (G') of the adhesive sheet before or after hardening, it is preferable to adjust the composition or molecular weight of the following (meth)acrylic polymer (A) as the base polymer, or adjust The type or addition amount of the crosslinking agent (B), or the adjustment of the irradiation dose of active energy rays. However, it is not limited to this means.

＜This adhesive composition＞ The present adhesive composition is a composition comprising a (meth)acrylic polymer (A), preferably a crosslinking agent (B) and/or a polymerization initiator (C), and other components as needed.

＜(Meth)acrylic polymer (A)＞ In this pressure-sensitive adhesive composition, a (meth)acrylic polymer (A) is contained, and a (meth)acrylic polymer (A) is contained especially as a main component resin. That is, the (meth)acrylic polymer (A) is the resin with the highest mass ratio among the resins constituting this adhesive composition. In this case, the mass ratio of the (meth)acrylic polymer (A) in the resin constituting the adhesive composition may be 50 mass % or more, especially 70 mass % or more, especially 80 mass % or more, especially 90 mass % or more. % or more (including 100% by mass).

As the above-mentioned (meth)acrylic polymer (A), it contains the following formula 1 (wherein, R ₁ represents a hydrogen atom or a methyl group, and R ₂ represents a straight-chain or branched-chain alkyl group with 4 to 18 carbon atoms. The structural unit of the compound represented by the monomer component or alicyclic hydrocarbon) is preferably one obtained by polymerizing a polymer component comprising 50% by mass or more of the monomer component.

Among them, the (meth)acrylic polymer (A) is more preferably one obtained by polymerizing the above-mentioned monomer components in an amount of 55% by mass or more as a polymerization component, particularly preferably containing 60% by mass or more of the above-mentioned monomer components as a polymerization component. ingredients to make it aggregated.

Furthermore, in the present invention, "(meth)acrylic acid" means including acrylic acid and methacrylic acid, "(meth)acryl" means including acryl and methacryl, and "(meth)acryl" means including acryl and methacryl. "Acrylic ester" means to include acrylate and methacrylate, and "(co)polymer" means to include polymers and copolymers.

式1

Formula 1

Examples of the monomer represented by the above formula 1 include: n-butyl (meth)acrylate, isobutyl (meth)acrylate, second-butyl (meth)acrylate, third-butyl (meth)acrylate Butyl, Amyl (meth)acrylate, Isoamyl (meth)acrylate, Neopentyl (meth)acrylate, Hexyl (meth)acrylate, Cyclohexyl (meth)acrylate, (Meth) Heptyl acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate , tertiary butylcyclohexyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, lauryl (meth)acrylate, Tridecyl (meth)acrylate, Myristyl (meth)acrylate, Cetyl (meth)acrylate, Stearyl (meth)acrylate, Isostearyl (meth)acrylate ester, iso(meth)acrylate, 3,5,5-trimethylcyclohexane (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate Wait. These can be used 1 type or in combination of 2 or more types. Among the above, it is particularly preferable to include butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, (meth) One or more types of lauryl acrylate.

The above-mentioned (meth)acrylic polymer (A) is preferably a copolymer having "other copolymerizable monomers" other than the above-mentioned monomer components as a copolymerization component.

The above-mentioned "other copolymerizable monomer" is preferably contained in the (meth)acrylic polymer (A) in an amount of 1 to 30% by mass, and more preferably contained in a ratio of 2% by mass or more or 25% by mass or less. other copolymerizable monomers".

Examples of the "other copolymerizable monomers" include: (a) carboxyl group-containing monomers (hereinafter, also referred to as "copolymerizable monomer a1"), (b) hydroxyl-containing monomers (hereinafter, , also known as "copolymerizable monomer a2"), (c) amino-containing monomer (hereinafter, also referred to as "copolymerizable monomer a3"), (d) epoxy group-containing monomer ( Hereinafter, also referred to as "copolymerizable monomer a4"), (e) amide group-containing monomer (hereinafter also referred to as "copolymerizable monomer a5"), (f) vinyl monomer (hereinafter , also referred to as "copolymerizable monomer a6"), (g) (meth)acrylate monomer of an alkyl group having 1 to 3 carbon atoms (hereinafter also referred to as "copolymerizable monomer a7"), (h) Macromonomer (hereinafter also referred to as "copolymerizable monomer a8"), (i) aromatic-containing monomer (hereinafter referred to as "copolymerizable monomer a9"), or (j) Monomers containing other functional groups (hereinafter "copolymerizable monomer a10"). These can be used 1 type or in combination of 2 or more types.

Examples of the copolymerizable monomer a1 include: (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypropyl (meth)acrylate, carboxybutyl (meth)acrylate, ω-carboxyl Polycaprolactone mono(meth)acrylate, 2-(meth)acryloxyethyl hexahydrophthalate, 2-(meth)acryloxypropyl hexahydrophthalate, 2-(meth)acryloxyethyl phthalate, 2-(meth)acryloxypropyl phthalate, 2-(meth)acryloxyethyl maleate ester, 2-(meth)acryloxypropyl maleate, 2-(meth)acryloxyethyl succinate, 2-(meth)acryloxypropyl succinate, Crotonic acid, fumaric acid, maleic acid, itaconic acid. These can be used 1 type or in combination of 2 or more types.

Examples of the copolymerizable monomer a2 include: 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxy-1-methylethyl acrylate, (meth)acrylate base) 3-hydroxypropyl acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, glycerol mono(meth)acrylate, polyethylene glycol mono(meth)acrylate Ester, Polypropylene Glycol Mono(meth)acrylate, Polyethylene Glycol Polypropylene Glycol Mono(meth)acrylate, Polyethylene Glycol Polybutylene Glycol Mono(meth)acrylate, Polypropylene Glycol Polybutylene Glycol Mono(meth)acrylate Hydroxyalkyl (meth)acrylates such as meth)acrylate and hydroxyphenyl (meth)acrylate. These can be used 1 type or in combination of 2 or more types.

As the above-mentioned copolymerizable monomer a3, for example, aminomethyl (meth)acrylate, aminoethyl (meth)acrylate, aminopropyl (meth)acrylate, amine (meth)acrylate Aminoalkyl (meth)acrylate, N-alkylaminoalkyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, (meth) ) N,N-dialkylaminoalkyl (meth)acrylates such as N,N-dimethylaminopropyl acrylate. These can be used 1 type or in combination of 2 or more types.

As the above-mentioned copolymerizable monomer a4, for example, glycidyl (meth)acrylate, methylglycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, 4-Hydroxybutyl glycidyl ether (meth)acrylate. These can be used 1 type or in combination of 2 or more types.

Examples of the above-mentioned copolymerizable monomer a5 include (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-butyl(meth)acrylamide, N -Methylol(meth)acrylamide, N-methylolpropane(meth)acrylamide, N-methoxymethyl(meth)acrylamide, N-butoxymethyl(meth)acrylamide base) acrylamide, diacetone (meth)acrylamide, maleimide, maleimide. These can be used 1 type or in combination of 2 or more types.

As said copolymerizable monomer a6, the compound which has a vinyl group in a molecule|numerator is mentioned. As such compounds, for example, ethoxy diethylene glycol acrylate, methoxy triethylene glycol acrylate, methoxy polyethylene glycol acrylate, methoxy dipropylene glycol acrylate, methoxy Polypropylene glycol acrylate and other functional monomers with functional groups such as alkoxyalkyl groups, polyalkylene glycol di(meth)acrylates, vinyl acetate, N-vinyl-2-pyrrolidone , Vinyl propionate, vinyl laurate and other vinyl ester monomers, and aromatic vinyl monomers such as styrene, chlorostyrene, chloromethylstyrene, α-methylstyrene and other substituted styrenes. These can be used 1 type or in combination of 2 or more types.

As said copolymerizable monomer a7, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, etc. are mentioned, for example. These can be used 1 type or in combination of 2 or more types.

The macromonomer system which is the above-mentioned copolymerizable monomer a8 is a polymer monomer having a terminal functional group and a high molecular weight skeleton component. When the above-mentioned "other copolymerizable monomer" is the copolymerizable monomer a8, the above-mentioned (meth)acrylic polymer (A) is a copolymer containing a structural unit derived from a macromonomer.

The skeleton component of the above-mentioned macromonomer preferably includes an acrylate polymer or a vinyl polymer. For example, the above-mentioned (meth)acrylate having a straight-chain or branched-chain alkyl group having 4 to 18 carbon atoms, the above-mentioned copolymerizable monomer a1, the above-mentioned copolymerizable monomer a2, the above-mentioned copolymerizable monomer Those exemplified by the body a6, the above-mentioned copolymerizable monomer a7, and the like can be used alone or in combination of two or more. The number average molecular weight of the macromonomer is preferably at least 1000, more preferably at least 1500, and still more preferably at least 2000. Furthermore, the upper limit of the number average molecular weight is usually 20,000.

In this resin composition, the processability can be improved by the above-mentioned macromonomer being a macromonomer copolymerized with (meth)acrylate having a straight chain or branched chain alkyl group having 1 to 3 carbons. Or storage stability is relatively good in this point. The number average molecular weight of the macromonomer is preferably from 1,000 to 10,000, more preferably from 1,500 to 5,000, and further preferably from 2,000 to 4,000. In addition, the above-mentioned macromonomer is a macromonomer formed by copolymerization of (meth)acrylic acid esters having straight-chain or branched-chain alkyl groups with 8 to 18 carbons, even on the adherend surface of the adherend. When there are irregularities, the conformability of the irregularities can be further improved, which is good in this respect. The number average molecular weight of the macromer is preferably 2,000 to 20,000, more preferably 3,000 or more or 15,000 or less, further preferably 4,000 or more or 10,000 or less.

By using the copolymerizable monomer a8, a macromonomer can be introduced as a branch component of the graft copolymer, and a (meth)acrylate copolymer can be used as a graft copolymer. For example, it can be set as a (meth)acrylic polymer (A) containing a copolymer containing a structural unit derived from a macromonomer as a branch component. Therefore, the characteristics of the main chain and side chain of the graft copolymer can be changed according to the selection or compounding ratio of the copolymerizable monomer a8 and other monomers. In particular, in this resin composition, the copolymerization ratio of the macromonomer in the (meth)acrylic polymer (A) is preferably 30% by mass or less, and more preferably Preferably, it is 2 mass % or more and 15 mass % or less, More preferably, it is 3 mass % or more and 10 mass % or less, Most preferably, it is 4 mass % or more and 7 mass % or less.

Examples of the above-mentioned copolymerizable monomer a9 include benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, Nonylphenol EO modified (meth)acrylate, etc. These can be used 1 type or in combination of 2 or more types.

Examples of the copolymerizable monomer a10 include: (meth)acrylic modified silicone, 2-acryloxyethyl acid phosphate, (meth)acrylic acid 2,2,2-tris Fluoroethyl ester, 2,2,3,3-tetrafluoropropyl (meth)acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate, 1H,1H,5H (meth)acrylate - Octafluoropentyl ester, (meth)acrylic acid 1H, 1H, 2H, 2H-tridecafluoro-n-octyl ester and other fluorine-containing monomers, etc. These can be used 1 type or in combination of 2 or more types.

Among the repeating units derived from the (meth)acrylate that the acrylic polymer (A) has, the glass transition temperature of at least one repeating unit is preferably -70 to 0°C.

In addition, the glass transition temperature of a copolymer component means the value calculated by Fox's calculation formula based on the glass transition temperature and composition ratio of the polymer obtained from the homopolymer of each component of this copolymer. The calculation formula of Fox is a calculated value obtained by the following formula, and can be obtained using the value recorded in the polymer handbook [Polymer Handbook, J. Brandrup, Interscience, 1989]. 1/(273+Tg)=Σ(Wi/(273+Tgi)) [Where, Wi represents the weight fraction of monomer i, and Tgi represents the Tg (°C) of the homopolymer of monomer i]

When the above-mentioned (meth)acrylic polymer (A) is obtained, the glass transition temperature of at least one repeating unit derived from the (meth)acrylate ester contained in the acrylic polymer (A) is preferable. It is -70～0℃.

Examples of (meth)acrylate constituting such a repeating unit include n-butyl acrylate, n-hexyl acrylate, n-octyl acrylate, n-nonyl acrylate, n-decyl acrylate, and 2-ethylhexyl acrylate. , 2-ethylhexyl methacrylate, 2-methylhexyl acrylate, isooctyl acrylate, isononyl acrylate, isodecyl acrylate, isodecyl methacrylate, isostearyl acrylate, (methyl ) isostearyl acrylate, multibranched stearyl acrylate, multibranched (meth)stearyl acrylate, etc., but are not limited thereto.

In addition, when the glass transition temperature of at least one of the repeating units derived from (meth)acrylate contained in the acrylic polymer (A) is 20 to 120°C, excellent processability can be maintained. Or storage stability, so it is preferable. Specifically, since it affects the melting temperature of the adhesive sheet, the glass transition temperature (Tg) is preferably 30°C to 120°C, more preferably 40°C or higher or 110°C or lower, especially 50°C above or below 100°C. If a repeating unit having such a glass transition temperature (Tg) is contained, excellent processability or storage stability can be maintained by adjusting the molecular weight, and it can be adjusted to be hot-melt at 50°C or higher.

Examples of (meth)acrylate constituting such a repeating unit include methyl acrylate, ethyl methacrylate, n-propyl acrylate, n-propyl methacrylate, isopropyl acrylate, and isopropyl methacrylate. Propyl, n-butyl methacrylate, tert-butyl acrylate, isobutyl acrylate, isobutyl methacrylate, iso-butyl acrylate, cyclohexyl acrylate, cyclohexyl methacrylate, 1,4-cyclo Hexanedimethanol monoacrylate, tetrahydrofurylmethyl methacrylate, benzyl acrylate, benzyl methacrylate, phenoxyethyl acrylate, phenoxyethyl methacrylate, and the like.

Moreover, if the glass transition temperature of all the repeating units derived from (meth)acrylate in the acrylic polymer (A) is -70 to 20°C, when the adherend has unevenness on the adherend surface, Since the concavo-convex matching property can be further improved, it is preferable.

Among the above, the above-mentioned (meth)acrylic polymer (A) is preferably a block copolymer and/or a graft copolymer from the viewpoint of imparting hot-melt property to the adhesive. When the (meth)acrylic polymer (A) is a block copolymer or a graft copolymer, an adhesive sheet excellent in shape stability and heat-melt property can be produced.

Here, the block copolymer refers to a copolymer having a plurality of polymer chains containing a repeating unit derived from (meth)acrylate, and a plurality of polymer chains having different chemical structures are combined into a linear chain. Part of the block of the block copolymer preferably contains repeating units derived from macromonomers. On the other hand, a graft copolymer is a copolymer containing a repeating unit derived from (meth)acrylate as a dry component, and refers to a copolymer having a comb-like polymer, a brush-like polymer, Star-shaped polymers, coconut-shaped polymers, dumbbell-shaped polymers and other structures. As the branch component of the graft copolymer, a copolymer containing a repeating unit derived from a macromonomer is preferable. Furthermore, in the following examples, graft copolymers containing repeating units derived from macromonomers were used as base polymers. Even if it is a block copolymer containing a repeating unit derived from a macromonomer, the repeating unit derived from a macromonomer aggregates and undergoes phase separation to exert an effect, which is common to a graft copolymer, so blocks containing a macromonomer can be predicted Copolymers can also achieve the same effect as graft copolymers containing macromonomers.

As described above, when the above-mentioned (meth)acrylic polymer (A) is a copolymer containing a structural unit derived from a macromonomer, if the copolymerization ratio of the macromonomer is 2% by mass or more, it can impart Therefore, it is preferable because it is hot-melt. On the other hand, if it is 30% by mass or less, when it is laminated with the constituent members of the image display device described below to form a laminate, it will not peel off when it is bent, and it will be durable. Sex becomes good, so better. From this point of view, the copolymerization ratio of the macromonomer in the (meth)acrylic polymer (A) is preferably 2% by mass or more, particularly preferably 3% by mass or more, especially 4% by mass or more. On the other hand, it is preferably 30% by mass or less, especially preferably 15% by mass or less, even more preferably 10% by mass or less, especially 8% by mass or less, and even more preferably 7% by mass or less.

In the present invention, in the (meth)acrylic system using a macromonomer obtained by copolymerization of a (meth)acrylic acid ester having a linear or branched alkyl group having 1 to 3 carbon atoms as the macromonomer In the case of the polymer (A), the glass transition temperature of the repeating unit derived from the macromer is preferably 20 to 150°C, more preferably 40°C or higher or 130°C or lower, especially 60°C or higher or 120°C or lower . In addition, when the above-mentioned (meth)acrylic polymer (A) is a block copolymer and/or a graft copolymer, for the same reason as above, the copolymerization component whose glass transition temperature is in the above-mentioned range The content is preferably at least 3 mass % with respect to the above-mentioned (meth)acrylic polymer (A), and particularly preferably at least 4 mass %. On the other hand, it is preferably 10% by mass or less, especially preferably 9% by mass or less, especially 8% by mass or less, and even more preferably 7% by mass or less. Furthermore, as confirmed in the following examples, if the repeating unit derived from the macromonomer, that is, the copolymer component with a glass transition temperature of 20 to 150° C., is 3% by mass or more with respect to the (meth)acrylic polymer (A), If it is 4 mass % or more, a heat-meltability can be provided, and shape can be stabilized, if it is this range, the same effect as an Example can be acquired.

＜Crosslinking agent (B)＞ The crosslinking agent (B) is a compound or composition that forms a crosslinked structure in this adhesive composition, and is a compound having two or more crosslinkable functional groups. When the present adhesive composition contains the crosslinking agent (B), the present adhesive composition can form a crosslinked structure, and durability or recovery can be imparted to the present adhesive sheet.

As said crosslinkable functional group, an isocyanate group, an epoxy group, a (meth)acryl group, a thioisocyanate group, a primary or secondary amino group, and a thiol group are mentioned, for example. These can be protected by suitable protecting groups.

As a preferred combination of crosslinkable functional groups contained in the crosslinking agent, only epoxy groups, only isocyanate groups, only (meth)acryl groups, only thioisocyanate groups, Only thiol group, only primary or secondary amine group, combination of epoxy group and (meth)acryl group, combination of isocyanate group and (meth)acryl group. Among them, from the viewpoint of ensuring the hardening property of the present adhesive sheet by irradiating active energy rays, the crosslinking agent (B) is preferably a polyfunctional one having two or more (meth)acryl groups. (Meth)acrylate (b).

The content of the polyfunctional (meth)acrylate (b) is preferably at least 0.5 parts by mass, particularly preferably at least 1 part by mass, especially 1.5 parts by mass, relative to 100 parts by mass of the (meth)acrylic polymer (A). parts by mass or more. The upper limit is preferably at most 10 parts by mass, more preferably at most 7 parts by mass, and still more preferably at most 5 parts by mass, from the viewpoint of maintaining moderate flexibility and ensuring conformability to the adherend when bent. or less, more preferably 3 parts by mass or less, especially 2 parts by mass or less. In particular, after curing, in the case of bonding image display device components having steps, etc., it is preferably 5 parts by mass or less, especially More preferably, it is 3 parts by mass or less, especially 2 parts by mass or less.

Examples of the polyfunctional (meth)acrylate (b) include: 1,4-butanediol di(meth)acrylate, glycerin di(meth)acrylate, neopentyl glycol di(meth)acrylate, ) acrylate, glyceryl glycidyl ether di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, tricyclodecane Dimethacrylate, tricyclodecane dimethanol di(meth)acrylate, bisphenol A polyethoxy di(meth)acrylate, bisphenol A polypropoxy di(meth)acrylate, bisphenol A polyethoxy di(meth)acrylate, Phenol F polyethoxy di(meth)acrylate, ethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane trioxy(meth)acrylate Ethyl ester, ε-caprolactone modified tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propoxylated pentaerythritol tri(meth)acrylate , Ethoxylated pentaerythritol tri(meth)acrylate, Pentaerythritol tetra(meth)acrylate, Propoxylated pentaerythritol tetra(meth)acrylate, Ethoxylated pentaerythritol tetra(meth)acrylate, Dipentaerythritol hexa(meth)acrylate Acrylates, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, isocyanuric acid tris(acryloxyethyl) base) ester, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, tripentaerythritol hexa(meth)acrylate, tripentaerythritol penta(meth)acrylate, hydroxypivalate neopentyl Diol di(meth)acrylate, di(meth)acrylate of ε-caprolactone adduct of neopentyl glycol hydroxypivalate, trimethylolpropane tri(meth)acrylate, UV-curable polyfunctional (meth)acrylic monomers such as trimethylolpropane polyethoxy tri(meth)acrylate, di-trimethylolpropane tetra(meth)acrylate, and polyester ( Multifunctional (meth)acrylic oligomers such as meth)acrylate, epoxy (meth)acrylate, urethane (meth)acrylate, polyether (meth)acrylate, etc. Among them, propoxylated pentaerythritol tri(meth)acrylate and polytetramethylene glycol di(meth)acrylate are preferred. These can be used 1 type or in combination of 2 or more types.

This adhesive composition may further contain the monofunctional (meth)acrylate component (D) which has 1 (meth)acryl group. By including the monofunctional (meth)acrylate component, the molecular weight between the cross-linking points of the cured product can be increased, so the freedom of movement of the molecular chain increases. When the laminated body including the constituent members of the image display device is bent, the adhesive sheet including the adhesive composition of the present invention can conform to the laminated body and be deformed.

Examples of the monofunctional (meth)acrylate component (D) include: ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate ester, isobutyl (meth)acrylate, tertiary butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, Lauryl (meth)acrylate, Octyl (meth)acrylate, Isooctyl (meth)acrylate, Decyl (meth)acrylate, Isodecyl (meth)acrylate, Dodecyl (meth)acrylate Isododecyl (meth)acrylate, Myristyl (meth)acrylate, Stearyl (meth)acrylate, Isostearyl (meth)acrylate, (Meth)acrylic acid Behenyl, Cyclopropyl (meth)acrylate, Cyclobutyl (meth)acrylate, Cyclopentyl (meth)acrylate, Cyclohexyl (meth)acrylate, Cycloheptyl (meth)acrylate, ( Cyclooctyl methacrylate, Cyclononyl (meth)acrylate, Cyclodecyl (meth)acrylate, Iso(meth)acrylate, Normethacrylate (meth)acrylate, Adamantium (meth)acrylate Alkyl esters, tricyclodecane dimethanol acrylate, ethoxylated o-phenylphenol acrylate, 2-hydroxy-o-phenylphenol propyl acrylate, methoxypolyethylene glycol (meth)acrylate, methoxy Polypropylene glycol (meth)acrylate, polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, phenoxyethylene glycol (meth)acrylate, phenoxydiethylene glycol ( Meth)acrylate, Phenoxypolyethylene glycol (meth)acrylate, 2-Hydroxy-o-phenylphenol propyl acrylate, 2-(meth)acryloxyethyl succinate, Tetrahydro-o-phenyl 2-(meth)acryloxyethyl dicarboxylate, 2-(meth)acryloxyethyl hexahydrophthalate, 2-(meth)acryloxypropyl phthalate , 2-(meth)acryloxypropyl hydrophthalate, 2-(meth)acryloxypropyl hexahydrophthalate, benzyl (meth)acrylate, (methyl) Benzyl acrylate, phenoxyethyl (meth)acrylate, phenoxyethylene glycol (meth)acrylate, 2-naphthyl (meth)acrylate, 9-anthracene (meth)acrylate, (meth)acrylate base) 1-pyrenylmethyl acrylate, benzyl (meth)acrylate, tricyclodecane dimethanol monocarboxylate monoacrylate, dicyclopentanyl acrylate, 2-hydroxyethyl (meth)acrylate, (meth)acrylate Base) 2-hydroxypropyl acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, trimethylolpropane mono(meth) base) acrylate, glycerol mono(meth)acrylate, pentaerythritol mono(meth)acrylate, diglycerol mono(meth)acrylate, di-trimethylolpropane mono(meth)acrylate, dipentaerythritol Mono(meth)acrylate, Ethoxylated trimethylolpropane mono(meth)acrylate, Propoxylated trimethylolpropane mono(meth)acrylate, Ethoxylated glycerol mono(meth)acrylate, Propylene Oxidized glycerol mono(meth)acrylate, ethyl Oxidized pentaerythritol mono(meth)acrylate, Propoxylated pentaerythritol mono(meth)acrylate, Ethoxylated di-trimethylolpropane mono(meth)acrylate, Propoxylated di-trimethylolpropane mono(meth)acrylate base) acrylate, alkylene oxide modified diglycerol mono(meth)acrylate and alkylene oxide modified dipentaerythritol mono(meth)acrylate, etc., and monofunctional urethane (meth)acrylate , monofunctional epoxy (meth)acrylate, monofunctional polyester (meth)acrylate and other monofunctional oligomers. These can be used 1 type or in combination of 2 or more types.

When the monofunctional (meth)acrylate component (D) is included, the mass ratio of the polyfunctional (meth)acrylate (b) to the monofunctional (meth)acrylate component (D) is preferably more than Functional (meth)acrylate (b): monofunctional (meth)acrylate (D) = 1:0.1 to 1:9, more preferably 1:1 to 1:9, more preferably 1:2 to 1:9. By being in this range, the monofunctional (meth)acrylate component does not become too much, and there is no possibility that the sensitivity to light may fall and productivity may fall.

＜Polymerization initiator (C)＞ The polymerization initiator (C) may impart active energy ray curability to the present adhesive sheet, as long as it is a compound that generates radicals by active energy rays. The polymerization initiator (C) can be roughly divided into two types by the mechanism of free radical generation, which can be roughly divided into: cracking type photoinitiator, which can cause the single bond of the polymerization initiator to be cleaved and decomposed to generate free radicals; Hydrogen-type photoinitiator, which can make the excited initiator and the hydrogen donor in the system form an excited complex and transfer the hydrogen of the hydrogen donor.

As the polymerization initiator (C), it may be any one of a cleavage type photoinitiator and a hydrogen abstraction type photoinitiator, and may be used alone or in combination. 2 or more. When a hydrogen abstraction type photoinitiator is used as the photoinitiator, the hydrogen abstraction reaction also occurs from the acrylic (co)polymer, and not only active energy ray hardening compounds, but also acrylic (co)polymers are included As for the cross-linked structure, a cross-linked structure with many cross-linked points can be formed, which is preferable in this respect. Also, when using a cleavage-type photoinitiator as the polymerization initiator (C), once free radicals are generated, they are decomposed and inactivated, so there is no possibility of unexpected reactions or deterioration after hardening. It is preferable in this aspect.

As the cleavage-type photoinitiator, for example, 2,2-dimethoxy-1,2-diphenylethan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2 -Methyl-1-phenyl-propan-1-one, 1-(4-(2-hydroxyethoxy)phenyl)-2-hydroxy-2-methyl-1-propan-1-one, 2 -Hydroxy-1-[4-{4-(2-hydroxy-2-methyl-propionyl)benzyl}phenyl]-2-methyl-propan-1-one, oligo(2-hydroxy- 2-methyl-1-(4-(1-methylvinyl)phenyl)acetone), methyl phenylglyoxylate, 2-benzyl-2-dimethylamino-1-(4-𠰌 Linylphenyl)butan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-𠰌linylpropan-1-one, 2-(dimethylamino) -2-[(4-methylphenyl)methyl]-1-[4-(4-𠰌linyl)phenyl]-1-butanone, bis(2,4,6-trimethylbenzyl) Acyl)-phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, (2,4,6-trimethylbenzoyl)ethoxyphenylphosphine oxide , bis(2,6-dimethoxybenzoyl) 2,4,4-trimethylpentylphosphine oxide, or their derivatives.

、2-氯9-氧硫𠮿

、3-甲基9-氧硫𠮿

、2,4-二甲基9-氧硫𠮿

、2-甲基蒽醌、2-乙基蒽醌、2-第三丁基蒽醌、2-胺基蒽醌或其衍生物等。Examples of hydrogen abstraction photoinitiators include: benzophenone, 4-methyl-benzophenone, 2,4,6-trimethylbenzophenone, 4-phenylbenzophenone Ketone, 3,3'-dimethyl-4-methoxybenzophenone, 4-(meth)acryloxybenzophenone, methyl 2-benzoylbenzoate, benzoylformic acid Methyl ester, bis(2-phenyl-2-oxyacetic acid) diethylene oxide, 4-(1,3-acryloyl-1,4,7,10,13-pentaoxytridecyl)benzidine Ketone, 9-oxosulfur𠮿

, 2-Chloro9-oxosulfur 𠮿

, 3-methyl 9-oxosulfur 𠮿

, 2,4-Dimethyl 9-oxosulfur 𠮿

, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone or its derivatives, etc.

The content of the above-mentioned polymerization initiator (C) is not particularly limited. As a standard, it is preferably at least 0.5 parts by mass and not more than 5 parts by mass, especially at least 1 part by mass or at most 4 parts by mass, especially at least 1.2 parts by mass or at most 3 parts by mass, based on 100 parts by mass of the (meth)acrylic polymer (A). The said polymerization initiator (C) is contained in the ratio of mass parts or less.

＜Other ingredients＞ As the "other components" contained in the adhesive composition other than the above, for example, silane coupling agent, or adhesion-imparting resin, plasticizer, antioxidant, light stabilizer, metal deactivator, Various additives such as anti-aging agents, moisture absorbents, polymerization inhibitors, ultraviolet absorbers, rust inhibitors, inorganic particles, sensitizers, and pigments. Typically, the amounts of these additives are preferably selected such that they do not adversely affect the hardening of the adhesive sheet or do not adversely affect the physical properties of the adhesive sheet. Moreover, reaction catalysts, such as a tertiary amine type compound, a quaternary ammonium type compound, and a tin laurate compound, may be contained suitably as needed.

Examples of the silane coupling agent include unsaturated groups such as vinyl, acryloxy, and methacryloxy groups, amino groups, epoxy groups, etc., and hydrolyzable ones such as alkoxy groups. functional compounds. Specific examples of silane coupling agents include N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyl Methyldimethoxysilane, γ-Aminopropyltriethoxysilane, γ-Glycidoxypropyltrimethoxysilane, γ-Methacryloxypropyltrimethoxysilane, etc. Among them, γ-glycidoxypropyltrimethoxysilane or γ-methacryloxypropyltrimethoxysilane can be preferably used in terms of good adhesion and less discoloration such as yellowing. . The said silane coupling agent can be used individually by 1 type or in combination of 2 or more types.

When containing a silane coupling agent, it is preferable that it is 0.1-5 mass parts with respect to 100 mass parts of (meth)acryl-type polymers, and it is especially more preferable that it is 0.2 mass parts or more or 3 mass parts or less. Furthermore, like the silane coupling agent, coupling agents such as organic titanate compounds can also be effectively used.

The adhesive composition may contain a hydrocarbon adhesive imparting agent for imparting adhesiveness or hot-melt property to the adhesive sheet. Examples of hydrocarbon tackifiers include polyterpenes (for example, α-pinene-based resins, β-pinene-based resins, and limonene-based resins), and aromatic-modified polyterpene resins (for example, phenol-modified polyterpene resins). Terpene resins) such as terpene resins, coumarone-indene resins, petroleum-based resins such as C5-based hydrocarbon resins, C9-based hydrocarbon resins, C5/C9-based hydrocarbon resins, and dicyclopentadiene-based resins, modified rosin Or rosins such as hydrogenated rosin, polymerized rosin, and rosin ester. The hydrocarbon adhesion-imparting agent is preferably compatible with the present adhesive composition.

The content of the hydrocarbon adhesion imparting agent is not particularly limited. Preferably it is 0.1-20 mass parts with respect to 100 mass parts of (meth)acryl-type polymers, Especially more preferably, it is 0.5 mass parts or more or 15 mass parts or less.

By including these silane coupling agents or adhesion-imparting agents, an adhesive composition having excellent adhesive properties can be preferably produced.

＜Manufacturing method of this adhesive sheet＞ Next, the manufacturing method of this adhesive sheet is demonstrated. However, the following description is an example of the method of manufacturing this adhesive sheet, and this adhesive sheet is not limited to what was manufactured by this manufacturing method.

In the production of this adhesive sheet, the (meth)acrylic polymer (A), and the crosslinking agent (B) and/or the polymerization initiator (C) if necessary, and then The adhesive composition is prepared by mixing the other components in specific amounts, the adhesive composition is shaped into a sheet, and the curable compound is crosslinked, that is, polymerized to harden as needed, to produce the adhesive sheet. However, it is not limited to this method.

When preparing the adhesive composition, a temperature-adjustable kneader (for example, single-screw extruder, twin-screw extruder, planetary mixer, twin-screw mixer, pressurized kneader, etc.) can be used to The above raw materials are kneaded. Furthermore, when mixing various raw materials, various additives such as silane coupling agent and antioxidant can be mixed with the resin in advance and then supplied to the kneader, or all the materials can be melted and mixed in advance and supplied, or only the additives can be pre-concentrated. Supplied as masterbatch in resin.

As a method of forming this adhesive composition into a sheet, known methods can be used: for example, wet lamination method, dry lamination method, extrusion casting method using a T-die, extrusion lamination method, Calendering method or inflation method, injection molding, liquid injection hardening method, etc. Among them, in the case of producing a sheet, wet lamination, extrusion casting, and extrusion lamination are preferred.

Also, when the present adhesive composition contains a radical initiator, it can be cured by irradiating heat and/or active energy rays to produce a cured product. In particular, the present adhesive sheet can be produced by irradiating heat and/or active energy rays to the present adhesive composition formed into a molded body such as a sheet body. Here, the active energy rays to be irradiated include, for example, α-rays, β-rays, γ-rays, neutron rays, electron beams, and other ionizing radiation, ultraviolet rays, and visible rays. Or from the viewpoint of controlling the reaction, ultraviolet rays are preferred. In addition, the irradiation energy, irradiation time, and irradiation method of active energy rays are not particularly limited as long as the initiator can be activated to polymerize the (meth)acrylate component.

Moreover, as another embodiment of the manufacturing method of this adhesive sheet, this adhesive composition is dissolved in an appropriate solvent, and it can implement using various coating methods. In the case of using the coating method, the present adhesive sheet can be obtained not only by hardening by the above-mentioned active energy ray irradiation, but also by hardening by heat.

In the case of coating, the thickness of the adhesive sheet can be adjusted according to the coating thickness and the solid content concentration of the coating liquid.

(layers other than this adhesive layer) This adhesive sheet may be composed of a single layer including this adhesive layer, or may be composed of two or more layers including this adhesive layer. When this adhesive sheet is composed of two or more layers, the layers other than the layer containing this adhesive composition may have any composition. Among them, for example, when the middle layer or the outermost layer or the innermost layer is formed by a layer other than this adhesive layer, from the viewpoint of further improving interlayer adhesion, forming a layer other than this adhesive layer The adhesive composition is also preferably formed of an adhesive composition containing a (meth)acrylic polymer, and more preferably contains the same (meth)acrylic polymer (A) as the adhesive layer. Furthermore, it is more preferable that the layer other than this adhesive agent layer contains a crosslinking agent (B) and/or a polymerization initiator (C).

When the present adhesive sheet is composed of two or more layers, it is preferable that at least the outermost layer, the innermost layer, or these two layers are layers corresponding to the present adhesive layer. All the layers may be layers corresponding to the present adhesive layer.

When the adhesive sheet is composed of two or more layers, the ratio of the thickness of the adhesive layer to the overall thickness of the adhesive sheet is preferably 10% to 100%. A ratio of 14% or more or 70% or less is preferable, and a ratio of 20% or more or 50% or less is especially preferable.

(thickness of this adhesive sheet) Since the bending stress at the time of bending or bending is proportional to the thickness, if the thickness of this adhesive sheet is 50 μm or less, the stress at the time of bending or bending can be relaxed, and it can also contribute to the thinning of the laminated body. and even the thinning of flexible image display devices. On the other hand, if it is 15 μm or more, the handleability is good, and even when there are concavo-convex portions with a step difference of 2 μm or more and 10 μm or less in the constituent members of the image display device, it can match the level difference. Therefore, the thickness of the adhesive sheet is preferably 50 μm or less, more preferably 45 μm or less, further preferably 40 μm or less, especially preferably 35 μm or less. On the other hand, the lower limit is preferably at least 15 μm, more preferably at least 17 μm, and most preferably at least 20 μm.

Although the adhesive sheet is thin as described above, it can be deformed to conform to the unevenness on the surface of the member for an image display device, and penetrate into the inside of the unevenness. Therefore, the unevenness can be absorbed, and the surface opposite to the bonding surface, which is the surface of the adhesive sheet, can be smoothed. At this time, if the level difference of the unevenness is 12% or less of the thickness of the adhesive sheet, the unevenness can be absorbed.

As an example of the present adhesive sheet, an adhesive sheet for a flexible display can be cited, which is characterized in that it is provided with an adhesive layer containing a (meth)acrylic polymer (A), and the adhesive sheet The thickness is not less than 15 μm and not more than 50 μm, it has active energy ray hardening, and when it is bonded under the following bonding conditions, it has a step difference of 2 μm or more, such as 2 to 10 μm, at an interval of 10 mm or less When constituting a member for an image display device, there are no bubbles around the above-mentioned level difference. (Adhering conditions) a) The adhesive sheet with a thickness of 15 to 50 μm is irradiated with ultraviolet rays so that the cumulative light intensity at 365 nm becomes 2000 to 4000 mJ/cm ² . b) Vacuum-laminate the above-mentioned adhesive sheet on the surface of the substrate with a step difference of 2 μm or more, such as 2 to 10 μm, at an interval of 10 mm or less under the condition of a pressure of 0.2 MPa and 30 seconds. c) Autoclave treatment under the conditions of 70°C, 0.45 MPa, and 20 minutes.

＜How to use this adhesive sheet＞ The adhesive sheet can also be used alone as an adhesive sheet. For example, the present adhesive composition can be directly applied to the member for image display device described below to form a sheet, or the present adhesive composition can be directly extruded or injected into a mold to use the present adhesive sheet. Furthermore, this adhesive sheet can also be used by directly filling this adhesive composition between the constituent members of an image display device.

Moreover, this adhesive sheet can also be used by laminating with other adhesive sheets. For example, if the flexibility of other adhesive sheets is better than that of this adhesive sheet, it is more suitable for flexible image display devices. Examples of such other adhesive sheets include a gel fraction of 70% or more, a thickness of 0.8 mm to 1.5 mm, and loss measured by dynamic viscoelasticity in a shear mode at a frequency of 1 Hz. The maximum point of tangent is the adhesive sheet below -25℃. At this time, if the maximum point of the loss tangent is -25° C. or lower, recovery is possible even when bent at high or low temperatures, which is preferable. From this point of view, the maximum point of the loss tangent of other adhesive sheets is preferably -25°C or lower, particularly preferably -30°C or lower, especially -35°C or lower.

(Adhesive sheet with release film attached) This adhesive sheet can also be used as an adhesive sheet with a release film including this adhesive layer formed from this adhesive composition and a release film (referred to as "this adhesive sheet with a release film") . For example, the present adhesive composition may be in the form of an adhesive sheet with a release film formed on a release film as a single-layer or multi-layer sheet.

As a material of the said release film, a polyester film, a polyolefin film, a polycarbonate film, a polystyrene film, an acrylic film, a triacetyl cellulose film, a fluororesin film etc. are mentioned, for example. Among these, polyester films and polyolefin films are particularly preferred.

The thickness of the release film is not particularly limited. Among them, for example, from the standpoint of workability and handleability, it is preferably 25 μm to 500 μm, especially more preferably 38 μm or more or 250 μm or less, especially 50 μm or more or 200 μm or less.

The release film of the adhesive sheet with a release film is preferably a polyester-based film, and in terms of releasability, it is preferable that it is easy to peel off after irradiation with active energy rays. From this point of view, when irradiated with active energy rays with a wavelength of 365 nm at a cumulative light intensity of 2000 to 4000 mJ/ ^cm2 , the peeling force of this adhesive sheet under the conditions of a peeling angle of 180° and a peeling speed of 300 mm/min Preferably it is 0.1 N/cm or less.

＜This laminate＞ A laminate (referred to as "the present laminate") as an example of an embodiment of the present invention is a laminate having a structure in which a release film and a level difference of 2 μm or more are formed on the surface to be laminated. A member for constituting an image display device is formed by laminating the above-mentioned adhesive sheet.

The release film of this laminate is the same as the release film of the above-mentioned adhesive sheet with release film.

For example, this laminate can be produced by laminating a release film and an image display device constituting member having a step difference of 2 μm or more on the layer to be laminated via this adhesive sheet, and passing the release film side through the above-mentioned release film. The release film irradiates the present adhesive sheet with active energy rays. In this case, in terms of step absorption, the irradiation dose of active energy rays is preferably 4000 mJ/cm ² or less, particularly preferably 3500 mJ/cm ² or less, further preferably 3200 mJ/cm ² or less. Also, in terms of sufficiently hardening and improving recovery, it is preferably at least 2000 mJ/cm ² , more preferably at least 2500 mJ/cm ² , and still more preferably at least 2800 mJ/cm ² .

<Laminated body for this image display device> A laminate for an image display device (hereinafter, sometimes referred to as "this laminate") as an example of an embodiment of the present invention is a laminate provided with an image display device constituting member on at least one side of the above-mentioned present adhesive sheet. .

This laminate is preferably a laminate having a structure in which a first image display device constituting member (hereinafter, sometimes referred to as "first member"), this adhesive sheet, and a second image display device A structure in which constituent members (hereinafter, sometimes referred to as "second member") are sequentially laminated. Furthermore, it may be a laminate having a structure in which a first member, a second member, and a third image display device constituting member (hereinafter, sometimes referred to as "third member") are respectively passed through this adhesive sheet. It is composed of successive layers. Two or more members to be laminated may be the same or different.

The thickness of this laminate is not particularly limited. For example, as an example of the case where it is used in an image display device, if the present laminate is in the form of a sheet with a thickness of 0.02 mm or more, the handleability is good, and if the thickness is 1.0 mm or less, it can facilitate lamination. Thinning of the body. Therefore, the thickness of the present laminate is preferably at least 0.02 mm, particularly preferably at least 0.03 mm, particularly preferably at least 0.05 mm. On the other hand, the upper limit is preferably 1.0 mm or less, particularly preferably 0.7 mm or less, especially 0.5 mm or less.

This laminated body can be produced by bonding this adhesive sheet to a 1st member, a 2nd member, and/or a 3rd member. However, it is not limited to such a manufacturing method.

(Constituent components of image display device) Depending on the configuration of the flexible image display device or the position of the adhesive sheet, as the first member, the second member, and the third member (these are sometimes collectively referred to as "this member"), for example: Housing lens, polarizing plate, phase difference film, barrier film, touch sensor film, light emitting element, PSA (Phase Sensitive Amplifier, phase sensitive amplifier), etc.

In particular, considering the configuration of image display, it is preferable that the first member has a touch input function. When this adhesive sheet has the said 2nd member, 3rd member, a 2nd member or a 3rd member may have a touch input function. In addition, various unevenness can be formed on the contact surface of at least one of the members and the adhesive sheet by wiring, printing, pattern development or surface treatment, embossing, and the like. When the surface of the member has unevenness, the level difference of the unevenness is preferably 2 μm or more, for example, 2 μm or more and 10 μm or less, especially preferably 8 μm or less, especially preferably 3 μm or more or 7 μm Below, especially more preferably 4 μm or more or 6 μm or less.

At least one of the attached image display device constituent members (including the first member, the second member and the third member) may be a resin sheet or film glass, and the resin sheet or film glass is selected from polyurethane Resins, cycloolefin resins, triacetyl cellulose resins, (meth)acrylate resins, epoxy resins and polyimide resins are one or more resins as the main component. Here, the "main component" refers to the component that accounts for the largest mass ratio among the components constituting the image display device constituting member, specifically, it accounts for 50% of the image display device constituting member or the adhesive composition forming the member. % or more by mass, more preferably at least 55% by mass, especially at least 60% by mass.

This adhesive sheet can be thermally melted after hardening by active energy rays. Even when the surface to be adhered of the adherend has unevenness by this heat fusion, it can be bonded so as to match the unevenness and absorb the unevenness, and the surface can be smoothed. Therefore, when bonding two image display device constituting members via this adhesive sheet, even if one or both image display device constituting members are opaque members, the unevenness can be absorbed, and the bonded two A component for forming an image display device.

<This image display device> By assembling this laminated body, for example, by laminating this laminated volume on other image display device constituent members, a flexible image display device (also referred to as "the present image display device") having this laminated body can be formed ). A flexible image display device refers to an image display device that does not leave traces of bending even if repeated bending or bending operations or winding operations are performed, but when the bending state or the bending state or the winding state is released , can quickly return to the state before the bending or bending operation, coiling operation, and can display images without deformation. In particular, one of the characteristics of this laminate is that it is possible to manufacture an image display device: Even if there are unevennesses with a step difference of 2 μm or more on the contact surface between the constituent members of the image display device and this adhesive sheet, The method of not generating bubbles matches the step difference and absorbs the step difference. Not only that, even if the bending or bending or coiling operation is performed in a low-temperature or high-temperature environment, it can also prevent the laminate from peeling or cracking, and the recovery property is also good. , so it has excellent flexibility.

In this image display device, the adhesive sheet may be disposed on the viewing side of an image display panel such as a liquid crystal panel, or may be disposed on the side opposite to the viewing side of the image display panel, that is, the light source side.

<Manufacturing method of laminated body for constituting image display device> Next, an example of the manufacturing method of this laminated body is demonstrated. However, the manufacturing method of this laminate is not limited to the method described below.

This laminated body can be manufactured by the manufacturing method of the laminated body for image display devices which has the following steps 1-3, and further step 4 as needed. Step 1: One surface of this adhesive sheet is bonded to the image display device constituting member 1 . Step 2: The present adhesive sheet is hardened by irradiating active energy rays. Step 3: The image display device constituting member 2 is attached to the other surface of the above-mentioned adhesive sheet to form a laminate. Step 4: heat-treating the above-mentioned laminate to heat-melt the above-mentioned adhesive sheet.

It is also possible to carry out step 2 after carrying out step 1, or to carry out step 1 after carrying out step 2. After performing steps 1 and 2, proceed to step 3.

(step 1) Step 1 is a step of bonding one surface of this adhesive sheet to the image display device constituting member 1 . As a lamination method, known methods such as roll lamination, pressure lamination using parallel flat plates, and separator lamination can be used. As the bonding environment, there are an atmospheric bonding method in which bonding is carried out under normal pressure, and a vacuum bonding method in which bonding is carried out under reduced pressure. From the viewpoint of preventing air bubbles during bonding, a method of bonding with parallel plates under a reduced pressure environment is preferable. Moreover, the bonding temperature can also be adjusted suitably.

(Step 2) Step 2 is a step of irradiating active energy rays to harden the adhesive sheet. As active energy rays, ultraviolet rays and visible rays are preferable. As for the light source when irradiating active energy rays, for example, high-pressure mercury lamps, metal halide lamps, xenon lamps, halogen lamps, and LED (Light Emitting Diode) lamps can be used according to the wavelength of the irradiated light or the amount of irradiation. , fluorescent lamps, etc. There are no particular limitations on the irradiation time or irradiation means. For example, it is preferable to irradiate in such a manner that, in the case of ultraviolet irradiation, the cumulative light amount at a wavelength of 365 nm is 2000 mJ/ ^cm2 or more, especially 3000 mJ/cm2 or more. ^cm2 or more.

When the surface of the first member or the second member, such as the layer to be laminated, has unevenness with a step difference of 2 μm or more, for example, 2 μm or more and 10 μm or less, the hot-melt adhesive sheet can be used. It is preferable that the adhesive sheet absorbs the step according to the step and smoothes the surface of the laminate.

(step 3) Step 3 is a step of attaching the image display device constituting member 2 to the other surface of the adhesive sheet passed through Step 1 and Step 2 to form a laminate. In step 3, the member 1 for constituting an image display device and/or the member 2 for constituting an image display device may be heated as needed, and the member 2 for constituting an image display device may be bonded together. Regarding the heating at this time, for example, a drawing of a member 1 for constituting an image display device/this adhesive sheet/member 2 for constituting an image display device is viewed from both sides by a pressurized plate heated to a specific temperature A method of pressurizing a laminate for a display device, etc. In addition, the heating temperature at this time is preferably at least 50°C and at most 80°C. That is, it is preferable to heat the image display device constituting member 1 and/or the image display device constituting member 2 to 50° C. to 80° C. to heat-melt the above-mentioned adhesive sheet, and to bond the image display device constituting Use component 2. Further, the pressurization pressure when pressurized by the pressurizing plate is more preferably 0.01 MPa or more and 0.4 MPa or less, especially 0.02 MPa or more or 0.35 MPa or less.

(step 4) Step 4 is a step of heat-treating the bonded laminate obtained in step 3 to heat-melt the adhesive sheet. This step 4 can be implemented as required. By applying heat treatment to the above-mentioned laminated body after bonding, the above-mentioned adhesive sheet is thermally fused, and even if there is a difference in height of 2 μm or more, for example, 2 μm or more, on the surface of the first member or the second member, such as the layer to be laminated. In the case of irregularities with a step difference of 10 μm or less, the above-mentioned adhesive sheet can also match the step difference and absorb the step difference to smooth the surface.

The heating temperature when heat-treating the laminate is preferably at a temperature of 40°C or higher and 90°C or lower. Among them, the above-mentioned temperature is more preferably 50°C or higher or 80°C or lower, especially 60°C or higher or 70°C or lower. Also, together with the heat treatment, an air pressure of 0.2 MPa to 0.8 MPa may be applied to the laminate for 5 minutes or longer. The air pressure at this time is preferably not less than 0.2 MPa and not more than 0.8 MPa, more preferably not less than 0.4 MPa or not more than 0.6 MPa. The above treatment time is more preferably 5 minutes or more or 60 minutes or less, especially 10 minutes or more or 30 minutes or less.

In Step 4, together with the heat treatment described above, a pressure of 0.01 MPa to 0.4 MPa may be applied to the present laminate. The pressurized pressure is more preferably 0.01 MPa or more and 0.4 MPa or less, especially 0.02 MPa or more and 0.35 MPa or less. The above-mentioned processing time is more preferably 5 seconds or more or 10 minutes or less, especially 10 seconds or more or 5 minutes or less.

Moreover, when implementing step 4, it is preferable to implement in order of steps 1, 2, 3, and 4. This manufacturing method is effective when the first and second members do not transmit active energy rays. When heat-melting the hardened adhesive sheet, it is preferable to heat-melt the adhesive sheet within 30 minutes after irradiating the active energy ray. The reason for this is that, by heat-melting before complete hardening, it is easy to fit more unevenly with a step difference of 2 μm or more. From this point of view, the time from irradiating active energy rays to heat-melt treatment is preferably within 30 minutes, more preferably within 20 minutes, and still more preferably within 10 minutes.

＜Explanation of words, etc.＞ In the present invention, "sheet" is also included when it is called "film", and "film" is also included when it is called "sheet". Also, when expressed as a "panel" such as an image display panel, a protective panel, etc., it includes a board, a sheet, and a film.

In this specification, when it is described as "X~Y" (X, Y are arbitrary numbers), unless otherwise specified, it includes the meaning of "more than X but less than Y" and also includes "preferably greater than X". ” or “preferably less than Y”. Also, when it is described as "more than X" (X is an arbitrary number), unless otherwise specified, it includes the meaning of "preferably greater than X", and when it is described as "below Y" (Y is an arbitrary number) In a case, unless otherwise specified, the meaning of "preferably smaller than Y" is also included. [Example]

The invention is further illustrated by the following examples. However, the present invention is not limited to the Examples shown below and explained.

First, the details of the raw materials of the adhesive composition prepared in the examples will be described.

＜(Meth)acrylic polymer (A)＞ ・(Meth)acrylic polymer (A-1): 6 parts by mass of polymethylmethacrylate macromonomer (Tg105°C) with a number average molecular weight of 2800, 90 parts by mass of butyl acrylate (Tg-55°C), Acrylic acid graft copolymer (mass average molecular weight: 220,000, Tg-45°C) copolymerized with 4 parts by mass of acrylic acid (Tg106°C) ・(Meth)acrylic polymer (A-2): 15 parts by mass of polymethyl methacrylate macromonomer (Tg105°C) with a number average molecular weight of 2800, 81 parts by mass of butyl acrylate (Tg-55°C), Acrylic acid graft copolymer (mass average molecular weight: 160,000, Tg-36°C) obtained by copolymerization of 4 (106°C) parts by mass of acrylic acid ・(Meth)acrylic polymer (A-3): 2-ethylhexyl acrylate (Tg-70°C), methyl acrylate (Tg8°C), ethyl acrylate (Tg-20°C), 2-acrylate Acrylic acid copolymer (mass average molecular weight: about 700,000, Tg-54°C) copolymerized with hydroxyethyl ester (Tg-15°C) and 4-hydroxybutyl acrylate (Tg-40°C) ・(Meth)acrylic polymer (A-4): 15 parts by mass of SLMA (lauryl methacrylate) macromonomer (Tg-65°C) with a number average molecular weight of 5,500, butyl acrylate (Tg-55°C) Acrylic graft copolymer formed by random copolymerization of 85 parts by mass (mass average molecular weight: 410,000, Tg-38°C) ・(Meth)acrylic polymer (A-5): 9 parts by mass of polymethyl methacrylate macromonomer (Tg105°C) with a number average molecular weight of 2800, 87 parts by mass of butyl acrylate (Tg-55°C), Acrylic acid graft copolymer (mass average molecular weight: 160,000, Tg-36°C) obtained by copolymerization of 4 (106°C) parts by mass of acrylic acid ・(Meth)acrylic polymer (A-6): 2-ethylhexyl acrylate (Tg-70°C), methyl acrylate (Tg8°C), 2-hydroxyethyl acrylate (Tg-15°C) Polymerized acrylic acid copolymer (mass average molecular weight: about 400,000, Tg-50°C)

The glass transition temperature of each component of the copolymerization in the above-mentioned (meth)acrylic polymer is a literature value of the glass transition temperature obtained from the homopolymer of the component. Regarding the macromonomer, a literature value of the glass transition temperature obtained from a homopolymer of a component forming a high-molecular-weight skeleton in the macromonomer is set. The glass transition temperature of the acrylic copolymer is described as the theoretical Tg calculated by Fox's calculation formula based on the glass transition temperature and composition ratio of the above-mentioned copolymerization components.

＜Crosslinking agent (B)＞ ・Crosslinking agent (B-1): propoxylated pentaerythritol triacrylate ・Crosslinking agent (B-2): Polytetramethylene glycol di(meth)acrylate

＜Polymerization initiator (C)＞ ・Initiator (C-1): Mixture of 2,4,6-trimethylbenzophenone and 4-methylbenzophenone ("Esacure TZT" manufactured by IGM Corporation)

＜Monofunctional (meth)acrylate (D)＞ ・Monofunctional (meth)acrylate (D-1): 4-hydroxybutyl acrylate ・Monofunctional (meth)acrylate (D-2): Monofunctional urethane acrylate containing a propylene glycol skeleton ("PEM-X264" manufactured by AGC, mass average molecular weight: 10,000)

＜Other＞ ・Silane coupling agent (E-1): KBM403 (manufactured by Shin-Etsu Silicone Co., Ltd.) ・Rust inhibitor (E-2): 1,2,3-Benzotriazole

[Example 1] 100 parts by mass of (meth)acrylic polymer (A-1), 1.5 parts by mass of crosslinking agent (B-1), 1.5 parts by mass of initiator (C-1), antirust agent (E-2) 0.5 parts by mass were uniformly mixed to prepare an adhesive composition. On a release film with a thickness of 100 μm (PET film manufactured by Mitsubishi Chemical Co., Ltd.) subjected to a silicone release treatment, the above adhesive composition was spread into a sheet shape so as to have a thickness of 25 μm.

Next, on the sheet-like adhesive composition, a release film (PET film manufactured by Mitsubishi Chemical Co., Ltd.) with a thickness of 75 μm treated with silicone release was laminated to form a laminate, and a release film/adhesive sheet comprising Material 1/ Adhesive sheet 1 with release film attached. In addition, the adhesive sheet 1 is an active energy ray curable adhesive sheet having active energy ray curability that is cured by irradiating active energy rays.

[Example 2] Except for changing the thickness as shown in Table 1, the adhesive sheet 2 and the adhesive sheet 2 with a release film including the release film/adhesive sheet 2/release film were produced in the same manner as in Example 1. In addition, the adhesive sheet 2 is an adhesive sheet having active energy ray curability that is cured by irradiation with light.

[Example 3] Each component was prepared as shown in Table 1 as a raw material for the adhesive layer.

Next, the above-mentioned adhesive composition was sandwiched between a 100 μm release film (PET film manufactured by Mitsubishi Chemical Co., Ltd., thickness 100 μm) treated with silicone release and a 75 μm release film treated with silicone release (PET film manufactured by Mitsubishi Chemical Co.) That is, two pieces of release film are hot-melted into a sheet with a thickness of 50 μm to obtain a release film with a release film/adhesive sheet 3/release film. Adhesive sheet 3. Furthermore, the adhesive sheet 3 is an adhesive sheet having active energy ray curability that is cured by irradiation with light.

[Example 4] Each component was prepared as shown in Table 1 as a raw material for the adhesive layer.

The adhesive sheet 4 and the adhesive sheet 4 with a release film comprising a release film/adhesive sheet 4/release film were produced in the same manner as in Example 3. Furthermore, the adhesive sheet 4 is an adhesive sheet having active energy ray curability that is cured by irradiation with light.

[Example 5] Each component was prepared as shown in Table 1 as a raw material for the adhesive layer. The adhesive sheet 5 and the adhesive sheet 5 with a release film comprising a release film/adhesive sheet 5/release film were produced in the same manner as in Example 1. Furthermore, the adhesive sheet 5 is an adhesive sheet having active energy ray curability that is cured by irradiation with light.

[Example 6] Each component was prepared as shown in Table 1 as a raw material for the adhesive layer. The adhesive sheet 6 and the adhesive sheet 6 with a release film comprising a release film/adhesive sheet 6/release film were produced in the same manner as in Example 3. Furthermore, the adhesive sheet 6 is an adhesive sheet having active energy ray curability that is cured by irradiation with light.

[Example 7] Each component was prepared as shown in Table 1 as a raw material for the adhesive layer. The adhesive sheet 7 and the adhesive sheet 7 with a release film comprising a release film/adhesive sheet 7/release film were produced in the same manner as in Example 3. Furthermore, the adhesive sheet 7 is an adhesive sheet having active energy ray curability that is cured by irradiation with light.

[Comparative example 1] Blend 100 parts by mass of (meth)acrylic polymer (A-3), 25 parts by mass of monofunctional (meth)acrylate (D-1), 3 parts by mass of initiator (C-1), and silane coupling agent 0.3 parts by mass and 0.3 parts by mass of anti-rust agent to prepare an adhesive composition, on a release film (PET film manufactured by Mitsubishi Chemical Co., Ltd.) with a thickness of 100 μm treated with silicone, the above adhesive composition was made into a thickness of The pattern of 25 μm is expanded into a sheet.

Next, on the sheet-like adhesive composition, a release film (PET film manufactured by Mitsubishi Chemical Co., Ltd.) with a thickness of 75 μm treated with silicone release was laminated to form a laminate, and a metal halide lamp irradiation device (Oxtail Denki Co., Ltd., UVC-0516S1, lamp UVL-8001M3-N), irradiated the above adhesive composition with light through the release film with a wavelength of 365 nm and a cumulative irradiation amount of 3000 mJ/ ^cm2 , and obtained The adhesive sheet (adhesive sheet 8) is an adhesive sheet laminate in which a release film is laminated on both sides of the front and back sides. The adhesive sheet 8 is an adhesive sheet that sufficiently reacts by light irradiation and has little room for hardening by active energy rays.

[Comparative example 2] Prepare 100 parts by mass of (meth)acrylic polymer (A-2), 2.5 parts by mass of crosslinking agent (B-1), 7.5 parts by mass of monofunctional (meth)acrylate (D-1), initiator (C-1) 1.5 parts by mass and 0.3 parts by mass of the antirust agent are used as raw materials for the adhesive layer.

Next, the above-mentioned adhesive composition was sandwiched between a 100 μm release film (PET film manufactured by Mitsubishi Chemical Co., Ltd., thickness 100 μm) treated with silicone release and a 75 μm release film treated with silicone release (PET film manufactured by Mitsubishi Chemical Co., Ltd.), that is, between two release films, hot-melt forming into a sheet with a thickness of 25 μm, and obtain a release film comprising a release film/adhesive sheet 9/release film Adhesive sheet 9. Furthermore, the adhesive sheet 9 is an adhesive sheet having active energy ray curability that is cured by irradiation with light.

[Reference example 1] The adhesive sheet 1 produced in Example 1 and the adhesive sheet 8 produced in Comparative Example 1 as another adhesive sheet were laminated by a hand roll to produce a laminated sheet with a total thickness of 50 μm. Furthermore, the adhesive sheet 5, which is another adhesive sheet, has a gel fraction of 70%, and the maximum point of the loss tangent obtained by the dynamic viscoelasticity measurement in the shear mode at a frequency of 1 Hz is -37°C.

[Evaluation of Adhesive Sheet] The measurement and evaluation of the adhesive sheet obtained in the Example were performed as follows.

＜Creep test＞ Remove the release film from the adhesive sheet with release film produced in Examples and Comparative Examples, and laminate it with a hand roller. Repeat the above steps until the thickness becomes about 0.9 mm. mm round adhesive sheet with release film as a sample. Regarding the above sample, when installed in a rheometer ("DHR-2" manufactured by TA Instruments Co., Ltd.), use it after removing the release film. The measurement jig is a parallel plate with a diameter of 8 mm, the temperature is 25°C, and the pressure is 1000 Pa. Under the conditions, the deformation (creep deformation) (%) after 3600 seconds was measured.

For the adhesive sheets produced in the examples and comparative examples, in the adhesive sheets 1-4, 6-7, using a high-pressure mercury lamp, the cumulative light intensity at 365 nm is 3000 mJ/cm ² , through the release film to the The adhesive sheet is irradiated with ultraviolet rays to harden the adhesive sheet. In the adhesive sheets 5 and 9, a high-pressure mercury lamp is used to irradiate the adhesive sheet with ultraviolet rays through the release film in such a way that the cumulative light intensity at 365 nm is 4000 mJ/cm ² , to harden the adhesive sheet. In addition, the adhesive sheet 8 produced in Comparative Example 1 is an adhesive sheet that reacts sufficiently by light irradiation and has little room for hardening by active energy rays, so it was used for measurement without the above-mentioned ultraviolet irradiation.

The hardened adhesive sheet was laminated so as to have a thickness of about 0.9 mm, and punched out into a circular shape with a diameter of 8 mm, which was used as a sample. For the above sample, the rheometer ("DHR-2" manufactured by TA Instruments Co., Ltd.) was used to measure the rheometer after 180 seconds under the condition that the measurement jig was a parallel plate with a diameter of 8 mm, the temperature was 80°C, and the pressure was 1000 Pa. Deformation (creep deformation) (%).

<Recovery rate> For the adhesive sheets with release film produced in Examples and Comparative Examples, in adhesive sheets 1-4, 6-7, the cumulative light intensity at 365 nm was 3000 mJ/cm using a high-pressure mercury lamp In the method ² , the adhesive sheet is irradiated with ultraviolet rays through the release film to harden the adhesive sheet. On the adhesive sheets 5 and 9, a high-pressure mercury lamp is used so that the cumulative light intensity at 365 nm becomes 4000 mJ/cm ² . The release film irradiates ultraviolet rays to the adhesive sheet to harden the adhesive sheet. In addition, the adhesive sheet 8 produced in Comparative Example 1 is an adhesive sheet that reacts sufficiently by light irradiation and has little room for hardening by active energy rays, so it was used for measurement without the above-mentioned ultraviolet irradiation.

The hardened adhesive sheet was laminated so as to have a thickness of about 0.9 mm, and punched out into a circular shape with a diameter of 8 mm, which was used as a sample. Regarding the above-mentioned sample, using a rheometer ("DHR-2" manufactured by TA Instruments, the measurement jig is a parallel plate with a diameter of 8 mm), at a temperature of 25°C, the shear deformation as the initial deformation (x) is 200 %, apply stress to the sample in the shear direction for 600 seconds. Thereafter, the residual deformation (y) after 600 seconds after the stress was released was measured, and the recovery rate was obtained from the following formula. Response rate (%) = {(x－y)/x}×100 In the above formula, x is the initial deformation applied to the laminated adhesive sheet with a thickness of about 0.9 mm in the shear direction, and y is the residual deformation after 600 seconds after the initial deformation is released and 600 seconds after the initial deformation is applied.

＜Loss tangent (tanδ)＞ The adhesive sheets produced in Examples and Comparative Examples were laminated so that the thickness became about 0.9 mm, and punched out into a circular shape with a diameter of 8 mm was produced. Regarding the above sample, using a viscoelasticity measuring device (manufactured by T.A. Instruments, product name "DHR-2"), the measurement jig is a parallel plate with a diameter of 8 mm, the frequency is 1 Hz, the measurement temperature is -50 to 150°C, and the temperature is raised. The dynamic viscoelasticity was measured at a speed of 5°C/min, and the loss tangent (tanδ) value at -30°C was read from the obtained data.

＜Gel fraction＞ The release film was removed from each of the adhesive sheets with release film produced in Examples and Comparative Examples, and about 0.1 g of the adhesive sheet was collected. Wrap the collected adhesive sheet in a SUS (Steel Use Stainless, stainless steel) net (#150) with a quality (X) made into a bag in advance, close the mouth of the bag to make a sample, and measure the quality (Y) of the sample. Store the above sample immersed in ethyl acetate in a dark place at 23°C for 24 hours, then take out the above sample and heat it at 70°C for 4.5 hours to evaporate the ethyl acetate and measure the content of the dried sample. mass (Z). For each measured mass, the gel fraction before hardening was calculated by the following formula. Gel fraction (%)=[(Z－X)/(Y－X)]×100

For the adhesive sheets with release film produced in Examples and Comparative Examples, in adhesive sheets 1 to 4 and 6 to 7, use a high-pressure mercury lamp so that the cumulative light intensity at 365 nm becomes 3000 mJ/cm ² , The adhesive sheet is irradiated with ultraviolet light through the release film to harden the adhesive sheet. On the adhesive sheets 5 and 9, use a high-pressure mercury lamp so that the cumulative light intensity at 365 nm becomes 4000 mJ/cm ² . The adhesive sheet is irradiated with ultraviolet rays to harden the adhesive sheet. With regard to the adhesive sheet after hardening, the gel fraction after active energy ray hardening was determined in the same manner as the above-mentioned evaluation procedure of the gel fraction. In addition, the adhesive sheet 8 produced in Comparative Example 1 is an adhesive sheet that is fully reacted by light irradiation and has almost no room for hardening by active energy rays, so it is used as the gel fraction after hardening for measurement.

＜Adhesion＞ One release film was removed from each of the adhesive sheets with release film produced in Examples and Comparative Examples, and a polyethylene terephthalate film ("Cosmoshine A4300" manufactured by Toyobo Co., Ltd., thickness of 100 μm) was used as a substrate film by roll bonding. Cut it into short strips of 10 mm wide x 150 mm long, peel off the remaining release film to expose the adhesive surface, and use a hand roller to roll the exposed adhesive surface onto the soda-lime glass. The body was subjected to autoclave treatment (60°C, gauge pressure 0.2 MPa, 20 minutes) for fine lamination to make samples for adhesion measurement. Under the conditions of 23°C and 40%RH, one side is stretched at an angle of 180° at a peeling speed of 300 mm/min, and the substrate film is peeled off from the soda-lime glass, and the tensile strength is measured by a load cell. Adhesion of soda lime glass (N/cm).

<Adhesive force (hardening after lamination)> One release film was removed from each of the adhesive sheets with release film produced in the examples and comparative examples, and the polyethylene terephthalate film ( "Cosmoshine A4300" manufactured by Toyobo Co., Ltd., thickness 100 μm) was roll-bonded as a substrate film. Cut it into short strips of 10 mm wide x 150 mm long, peel off the remaining release film to expose the adhesive surface, and use a hand roller to roll the exposed adhesive surface onto the soda-lime glass. The body is subjected to autoclave treatment (60°C, gauge pressure 0.2 MPa, 20 minutes) for fine lamination. Thereafter, ultraviolet rays were irradiated on the adhesive sheets 1 to 4 and 6 to 7 through the base film so that the cumulative light intensity at 365 nm became 3000 mJ/cm ² using a high-pressure mercury lamp, and the adhesive sheets were made Harden and prepare samples for adhesion measurement. Use a high-pressure mercury lamp on the adhesive sheets 5 and 9 to irradiate the adhesive sheets with ultraviolet rays through the substrate film so that the cumulative light intensity at 365 nm becomes 4000 mJ/ ^cm2 , and the adhesive sheets Harden the material and make a sample for adhesion measurement. Under the condition of 23°C and 40%RH, one side is stretched at an angle of 180° at a peeling speed of 300 mm/min, and the substrate film is peeled off from the soda-lime glass, and the tensile strength is measured by a load cell, and the active energy is measured The 180° peeling strength (N/cm) of the adhesive sheet to the soda lime glass after the line hardening was set as the adhesive force (hardening after bonding). In addition, since the adhesive sheet 8 produced in Comparative Example 1 was sufficiently reacted by light irradiation, and there was little room for hardening by active energy rays, this measurement was not carried out.

<Adhesive force (hardening before bonding)> Remove one release film from each of the adhesive sheets with release film produced in Examples and Comparative Examples, and press the polyethylene terephthalate film ( "Cosmoshine A4300" manufactured by Toyobo Co., Ltd., thickness 100 μm) was roll-bonded as a substrate film. Adhesive sheets 1 to 4 and 6 to 7 were irradiated with ultraviolet light through the substrate film so that the cumulative light intensity at 365 nm became 3000 mJ/ ^cm2 using a high-pressure mercury lamp to harden the adhesive sheet. Adhesive sheets 5 and 9 were irradiated with ultraviolet rays through the substrate film to harden the adhesive sheets using a high-pressure mercury lamp so that the cumulative light intensity at 365 nm became 4000 mJ/cm ² . In addition, the adhesive sheet 8 produced in Comparative Example 1 is an adhesive sheet that is fully reacted by light irradiation and has almost no room for hardening by active energy rays, so it is used as a hardened sheet before lamination for measurement.

Cut the hardened adhesive sheet into 10 mm wide x 150 mm long strips, peel off the remaining release film to expose the adhesive surface, and use a hand roller to roll the exposed adhesive surface onto the For soda-lime glass, the laminate was subjected to autoclave treatment (60°C, gauge pressure 0.2 MPa, 20 minutes) for fine lamination to prepare a sample for adhesion measurement. Under the condition of 23°C and 40%RH, one side is stretched at an angle of 180° at a peeling speed of 300 mm/min, and the substrate film is peeled off from the soda-lime glass, and the tensile strength is measured by a load cell, and the active energy is measured The 180° peel strength (N/cm) of the adhesive sheet to soda-lime glass after line hardening was defined as the adhesive force (hardening before bonding).

＜Gradient absorbency＞ Two PET films of 6 mm x 100 mm x 5.4 μm in thickness are arranged at 10 mm intervals on soda lime glass of 54 mm x 82 mm x 0.55 mm in thickness, and a convex surface with a step difference of 5.4 μm is formed on the surface. The base material for evaluation made of shaped parts.

Cut the adhesive sheets with release film produced in Examples and Comparative Examples into a size of 5 cm×5 cm, so that the adhesive surface exposed by peeling off one release film and the above-mentioned base material for evaluation have a step difference. The surfaces of the sides face each other, vacuum bonding is carried out under the conditions of pressurization pressure 0.2 MPa, 30 seconds, and autoclave treatment is carried out under the conditions of 70 ℃, air pressure 0.45 MPa, 20 minutes, and the laminated body for the evaluation of the level difference absorption is produced. .

The produced laminate was visually observed, and evaluated by the following evaluation criteria. ⊚: Adhesive sheet fits around all the steps, and there are no air bubbles. ○: Air bubbles generated near the level difference are 2 or less. ×: The adhesive sheet did not fit at three or more places near the level difference, and bubbles were generated.

<Gap absorption (after curing)> For the adhesive sheets with release film produced in Examples 1 to 4, a high-pressure mercury lamp was used to pass through the release film so that the cumulative light intensity at 365 nm became 3000 mJ/cm ² The film irradiates ultraviolet rays to the adhesive sheet to harden the adhesive sheet.

The adhesive surface exposed by peeling off one of the release films of the adhesive sheet hardened as described above faces the surface of the above-mentioned base material for evaluation on the side with a step difference, and is carried out under the conditions of a pressure of 0.2 MPa and 30 seconds. Vacuum bonding, autoclave treatment at 70°C, air pressure 0.45 MPa, 20 minutes. The above-mentioned procedure was performed within 10 minutes after the ultraviolet irradiation treatment, and a cured laminate for evaluating step absorption was produced. The produced laminate was visually observed, and evaluated by the same evaluation criteria as the above-mentioned step absorption evaluation.

[Evaluation of laminates] For the adhesive sheets with release film produced in Examples and Comparative Examples, a high-pressure mercury lamp was used for adhesive sheets 1-4, 6-7 and the laminated sheet of Reference Example 1 to The cumulative light intensity at 365 nm becomes 3000 mJ/cm ² , irradiate the adhesive sheet with ultraviolet rays through the release film to harden the adhesive sheet, and use a high-pressure mercury lamp on the adhesive sheets 5 and 9 to achieve the cumulative light intensity at 365 nm To achieve 4000 mJ/cm ² , the adhesive sheet was irradiated with ultraviolet light through the release film to harden the adhesive sheet. In addition, the adhesive sheet 8 produced in Comparative Example 1 is an adhesive sheet that is sufficiently reacted by light irradiation and has little room for hardening by active energy rays. Therefore, it was evaluated for flexibility without the above-mentioned ultraviolet irradiation. Use laminate samples.

The release film of each adhesive sheet was removed, and a transparent polyimide film (manufactured by Kolon, thickness 50 μm) was rolled and bonded to both sides of the adhesive sheet with a hand roller. Thereafter, autoclave treatment was performed under the conditions of 60° C. and an air pressure of 0.2 MPa for 20 minutes to obtain a laminate sample for flexibility evaluation.

＜Dynamic Flexibility＞ For the above-mentioned laminated body samples, use a constant temperature and humidity device internal durability system and planar body no-load U-shaped stretching tester (manufactured by Yuasa System Co., Ltd.), at the setting of curvature radius R = 3 mm, 60 rpm (1 Hz) Under certain conditions, the cycle evaluation of U-shaped bending is carried out. In addition, with respect to the laminated sheet of Reference Example 1, the side of the adhesive sheet 5 which is another adhesive sheet was made into the inner side, and it evaluated. After bending 200,000 times under the test environment -20°C or 60°C, 90%RH, the following evaluation criteria are used for evaluation.

○: No delamination, breakage, buckling, or flow occurred at the bent portion. ×: Any of delamination, fracture, buckling, and flow of the bent portion occurred.

＜Static Flexibility＞ The above-mentioned laminate sample was bent at a radius of curvature R=3 mm, stored at 60° C. and 90% RH for 24 hours, and then evaluated according to the following evaluation criteria. In addition, about the laminated sheet of the reference example 1, the adhesive sheet 5 which is another adhesive sheet was set as the inner side, and it tested in the state bent at curvature radius R=3 mm. ○: No delamination, breakage, buckling, or flow occurred at the bent portion. x: Any of delamination, fracture, buckling, and flow was observed at the bent portion.

Table 1 shows the results obtained by measuring and evaluating the adhesive sheet and the laminate.

[Table 1] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Comparative example 1 Comparative example 2 Adhesive sheet 1 Adhesive sheet 2 Adhesive sheet 3 Adhesive sheet 4 Adhesive sheet 5 Adhesive sheet 6 Adhesive sheet 7 Adhesive sheet 8 Adhesive sheet 9 Adhesive layer Methacrylic polymer (A) A-1 parts by mass 100 100 100 100 - - - - - A-2 - - - - - - - - 100 A-3 - - - - - - - 100 A-4 - - - - 100 - - - - A-5 - - - - - 100 - - - A-6 - - - - - - 100 - - Cross-linking agent (B) B-1 1.5 1.5 3 - 1.5 - - - 2.5 B-2 - - - 3 - 3 3 - - Initiator (C) C-1 1.5 1.5 1.5 1.5 1.5 1.5 1.5 3 1.5 Monofunctional (meth)acrylate (D) D-1 - - - - - - - - 7.5 D-2 - - - - - - - 25 - Silane coupling agent rust inhibitor E-1 - - - - - - - 0.3 - E-2 0.5 0.5 0.3 0.3 - 0.5 0.5 0.3 0.3 thickness μm 25 15 50 50 25 50 50 25 25 Creep test Deformation after 3600 seconds at 25°C % 120 120 229 149 356 53 1951 12 39 Deformation after 180 seconds at 80°C (after hardening) % 56 76 12 41 11 twenty one 37 12 8 response rate Recovery rate after 600 seconds at 25°C (after hardening) % 79 83 89 83 88 86 93 94 55 loss tangent Loss tangent at -30℃ - 1.2 1.2 1 1.5 1.5 1.2 1.6 1.4 0.4 gel fraction Gel Fraction of Adhesive Sheet % 0 0 0 0 0 0 0 70 0 After hardening % 43 54 59 39 72 54 78 - 60 Adhesion - N/cm 14 10 13 14 1.8 9 11 - 4.8 hardening after lamination N/cm 8 7.5 14 17 7.0 12 13 - 11 hardening before lamination N/cm 7 5.9 5.4 6.7 1.3 12.3 11.7 4.9 3.6 Step absorbency 5.4 μm step absorption ◎ ◎ ◎ ◎ ◎ 〇 〇 x 〇 5.4 μm step absorption (after hardening) ◎ 〇 ◎ ◎ - - - - - Dynamic Flexibility Appearance after bending 200,000 times at -20°C 〇 〇 〇 〇 〇 〇 〇 〇 〇 Appearance after bending 200,000 times at 60℃90%RH 〇 〇 〇 〇 〇 〇 〇 〇 〇 static bending Appearance after 24 hours at 60℃90%RH 〇 〇 〇 〇 〇 〇 〇 〇 x

The adhesive sheets of Examples 1-7 showed good adhesion in the step absorption test and excellent recovery properties, and also showed excellent durability in the bending test when they were made into laminates. Furthermore, even when the adhesive sheets of Examples 1-4 were bonded after hardening, they showed good bonding properties in the step absorption test. The adhesive sheet of Reference Example 1 also exhibited excellent step absorbency and excellent bending durability. On the other hand, since the adhesive sheet produced in Comparative Example 1 uses a material that does not have high fluidity, the deformation after 3600 seconds at 25°C is less than 50%, and the step absorption is poor. Since the adhesive sheet produced in Comparative Example 2 uses a material with low flexibility after hardening, after active energy hardening, it has poor recovery after being deformed by 200% at 25°C, and the bending durability when it is made into a laminate Also poor.

Claims (32)

An active energy ray-curable adhesive sheet comprising an adhesive layer containing a (meth)acrylic polymer (A) and satisfying the following requirements (1) to (3): (1) When the thickness is 0.8 mm to 1.5 mm, and when a pressure of 1000 Pa is applied for 3600 seconds at a temperature of 25°C, the deformation (creep deformation) is more than 50%; After mJ/cm ² is irradiated with active energy rays with a wavelength of 365 nm, when a pressure of 1000 Pa is applied at a temperature of 80°C for 180 seconds, the deformation (creep deformation) is more than 10%; When cm ² is irradiated with active energy rays with a wavelength of 365 nm, the recovery rate after deformation of 200% at 25°C is above 60% as represented by the following formula; recovery rate (%)={(x－y)/x}× 100 (x is the initial deformation applied to the adhesive sheet with a thickness of 0.8 mm to 1.5 mm in the shear direction, y is the residual deformation after 600 seconds of initial deformation and 600 seconds after the initial deformation is released). The active energy ray-curable adhesive sheet according to claim 1, wherein the (meth)acrylic polymer (A) is a block copolymer and/or a graft copolymer. The active energy ray-curable adhesive sheet according to claim 1 or 2, wherein when the thickness of the above-mentioned adhesive sheet is set to 0.8 mm to 1.5 mm, and the dynamic viscoelasticity is measured in a shear mode with a frequency of 1 Hz, The maximum point of the obtained loss tangent was -20°C or lower. The active energy ray-curable adhesive sheet according to any one of claims 1 to 3, wherein the (meth)acrylic polymer (A) is a copolymer comprising a structural unit derived from a macromonomer. The energy ray-curable adhesive sheet according to any one of claims 1 to 4, wherein the above-mentioned macromer is obtained by copolymerizing (meth)acrylate having a straight-chain or branched-chain alkyl group having 1 to 3 carbons. Become a giant monomer. The energy ray-curable adhesive sheet according to any one of claims 1 to 4, wherein the macromonomer is copolymerized with (meth)acrylate having a straight-chain or branched-chain alkyl group having 8 to 18 carbons Become a giant monomer. The active energy ray-curable adhesive sheet according to any one of claims 4 to 6, wherein in the (meth)acrylic polymer (A), the copolymerization ratio of the macromonomer is 2% by mass or more and 30% by mass or less . The active energy ray-curable adhesive sheet according to any one of claims 1 to 7, wherein the adhesive layer is made of a (meth)acrylic polymer (A), a crosslinking agent (B) and/or a polymer The layer formed by the adhesive composition of the initiator (C). The active energy ray-curable adhesive sheet according to claim 8, wherein the above-mentioned crosslinking agent (B) is a multifunctional (meth)acrylate (b). The active energy ray-curable adhesive sheet according to claim 9, wherein the content of the polyfunctional (meth)acrylate (b) is 0.5 parts by mass relative to 100 parts by mass of the above-mentioned (meth)acrylic polymer (A). More than 10 parts by mass and less than 10 parts by mass. The active energy ray-curable adhesive sheet according to any one of claims 1 to 10, wherein the gel fraction is not less than 0% and not more than 20%. The active energy ray-curable adhesive sheet according to any one of claims 1 to 11, wherein when the active energy ray with a wavelength of 365 nm is irradiated with a cumulative light intensity of 2000 to 4000 mJ/ ^cm2 , the gel fraction is the same as that before the irradiation. Ratio increases, the gel fraction is not less than 10% and not more than 85%. The energy ray-curable adhesive sheet according to any one of Claims 1 to 12, the thickness of which is set to 0.8 mm to 1.5 mm, and the loss tangent obtained by dynamic viscoelasticity measurement in a shear mode with a frequency of 1 Hz It is 0.8 or more at -30°C. The active energy ray-curable adhesive sheet according to any one of claims 1 to 13, which further has the following characteristics (4) and (5): (4) at 23°C 50%RH, peeling angle 180°, peeling Under the condition of speed 300 mm/min, the adhesive force to the surface of soda-lime glass is more than 1 N/cm; (5) After attaching the adhesive sheet to the soda-lime glass, irradiate with cumulative light intensity of 2000-4000 mJ/ ^cm2 When active energy rays with a wavelength of 365 nm, under the conditions of 23°C, 50%RH, peeling angle of 180°, and peeling speed of 300 mm/min, the adhesion to the above-mentioned soda-lime glass surface is above 1 N/cm. The active energy ray-curable adhesive sheet as claimed in claim 14 further has the characteristic (6): (6) When the active energy ray with a wavelength of 365 nm is irradiated with a cumulative light intensity of 2000-4000 mJ/ ^cm2 , the adhesive sheet is then When the sheet is bonded to soda-lime glass, under the conditions of 23°C, 40%RH, peeling angle of 180°, and peeling speed of 300 mm/min, the adhesion to the surface of the above-mentioned soda-lime glass is above 1 N/cm. The active energy ray-curable adhesive sheet according to any one of claims 1 to 15, which has a thickness of not less than 15 μm and not more than 50 μm. An adhesive sheet with a release film, comprising a laminate of the active energy ray-curable adhesive sheet and a release film according to any one of Claims 1 to 16. Such as the adhesive sheet with a release film as claimed in claim 17, wherein the above release film is a polyester film, and after irradiating active energy rays with a wavelength of 365 nm at a cumulative light intensity of 2000 to 4000 mJ/ ^cm2 , at a peeling angle of 180 ° and a peeling speed of 300 mm/min, the peeling force against the above-mentioned active energy ray-curable adhesive sheet is 0.1 N/cm or less. A laminate, which has the following structure, that is, the release film and the image display device constituting member having a step difference of 2 μm or more on the layer to be laminated are passed through any one of claims 1 to 16 Active energy ray-curable adhesive sheets are laminated. A method of manufacturing a laminate, which uses the active energy ray-curable adhesive sheet according to any one of claims 1 to 16 to form a pattern with a step difference of 2 μm or more between the release film and the layer to be laminated The members for constituting an image display device are laminated, and the above-mentioned adhesive sheet is irradiated with active energy rays through the release film from the side of the above-mentioned release film. A laminated sheet having a structure in which the active energy ray-curable adhesive sheet according to any one of claims 1 to 16 is laminated with another adhesive sheet. Such as the laminated sheet of claim 21, wherein the gel fraction of the above-mentioned other adhesive sheet is more than 70%, the thickness is set to 0.8 mm to 1.5 mm, and it is measured by dynamic viscoelasticity under a shear mode with a frequency of 1 Hz The maximum point of the obtained loss tangent was -25°C or lower. A laminated body for an image display device, which has the following structure, that is, two members for constituting an image display device are laminated through the active energy ray-curable adhesive sheet according to any one of claims 1 to 16 constitute, and At least one of the image display device constituting members has a level difference of 2 μm or more on a contact surface with the adhesive sheet. A laminate for image display devices according to Claim 23, wherein at least one of the members constituting the image display device is a resin sheet or film glass, and the resin sheet or film glass is selected from polyurethane resin and cycloolefin resin , triacetyl cellulose resin, (meth)acrylate resin, epoxy resin and polyimide resin in the group consisting of one or two or more resins as the main component. A flexible image display device comprising the laminate according to claim 23 or 24. An adhesive sheet for a flexible display, characterized in that it is provided with an adhesive layer containing a (meth)acrylic polymer (A), has a thickness of 15 μm to 50 μm, and has active energy ray curing When it is bonded to a member for constituting an image display device having a step of 2 to 10 μm at an interval of 10 mm or less under the following bonding conditions, there will be no bubbles around the above step: ( Bonding conditions) a) UV rays are irradiated to an adhesive sheet with a thickness of 15 to 50 μm so that the cumulative light intensity at 365 nm becomes 2000 to 4000 mJ/cm ² ; b) Apply pressure at 0.2 MPa for 30 seconds The above-mentioned adhesive sheet is vacuum bonded to the surface of the base material with a step difference of 2-10 μm at an interval of less than 10 mm; c) Autoclave treatment at 70°C and 0.45 MPa pressure for 20 minutes. A method for manufacturing a laminate for an image display device, characterized in that the laminate system for an image display device has a structure in which two members 1 and 2 constituting an image display device are hardened by active energy rays Adhesive sheets are laminated, and The above-mentioned method for manufacturing a laminate for an image display device has the following steps 1 to 3, and step 3 is performed after performing steps 1 and 2: Step 1: Attach one surface of the active energy ray-curable adhesive sheet according to any one of claims 1 to 16 to the image display device constituting member 1; Step 2: irradiating active energy rays to harden the active energy ray-curable adhesive sheet according to any one of Claims 1 to 16; Step 3: The image display device constituting member 2 is attached to the other surface of the above-mentioned adhesive sheet to form a laminate. The method for manufacturing a laminate for an image display device according to claim 27, wherein in the above-mentioned step 3, the above-mentioned adhesive sheet is heated to 50°C to 80°C to heat-melt it, and the image display device is bonded to form it. A laminated body was produced using the member 2 . The method for manufacturing a laminate for an image display device according to claim 27 or 28, further comprising a step 4 of heat-treating the laminate to melt the adhesive sheet after the above-mentioned step 3. The method of manufacturing a laminate for an image display device according to claim 29, wherein in the above-mentioned step 4, in the above-mentioned heat treatment, while heating the above-mentioned laminate to a temperature of 40°C to 90°C, while applying 0.2 MPa to 0.8 Pressure below MPa for more than 5 minutes. The method for manufacturing a laminate for an image display device according to claim 29 or 30, wherein the above steps 1 to 4 are carried out in the order of steps 1, 2, 3, and 4. The method for manufacturing a laminate for an image display device according to any one of claims 27 to 31, wherein at least one of the image display device constituting member 1 or the image display device constituting member 2 is combined with the above-mentioned adhesive sheet The contact surface of the material has a level difference of more than 2 μm.