JP2017075281A - Adhesive sheet and display body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive sheet and a display body having good processability in which an adhesive layer is excellent both in step followability and blister resistance.SOLUTION: There is provided an adhesive sheet 1 having an adhesive layer 2, wherein: the adhesive layer 2 comprises a first adhesive layer 21 as an outer layer on one surface side, a second adhesive layer 22 as an outer layer on the other surface side and a third adhesive layer 23 positioned as an intermediate layer between the first adhesive layer 21 and the second adhesive layer 22; an adhesive constituting the first adhesive layer 21 and an adhesive constituting the second adhesive layer 22 have a storage modulus (G') at 23°C of 0.1 MPa or more, respectively; the third adhesive layer 23 is constituted of an active energy ray-curable pressure-sensitive adhesive; and the storage modulus (G') at 23°C of the active energy ray-curable pressure-sensitive adhesive before curing is lower than the storage modulus (G') at 23°C of the adhesive constituting the first adhesive layer 21 and the storage modulus (G') at 23°C of the adhesive constituting the second adhesive layer 22.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pressure-sensitive adhesive sheet suitable for laminating a display member constituting member, and a display body obtained by using a pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet.

  Various mobile electronic devices such as smartphones and tablet terminals in recent years include a display using a display module having a liquid crystal element, a light emitting diode (LED element), an organic electroluminescence (organic EL) element, and the like. It is also becoming more and more a touch panel.

  In the display as described above, a protective panel is usually provided on the surface side of the display module. With the reduction in thickness and weight of electronic devices, the protective panel has been changed from a conventional glass plate to a plastic plate such as an acrylic plate or a polycarbonate plate.

  Here, a gap is provided between the protection panel and the display module so that the deformed protection panel does not collide with the display module even when the protection panel is deformed by an external force.

  However, if there is a gap as described above, that is, an air layer, the difference in refractive index between the protective panel and the air layer, and the reflection loss of light due to the difference in refractive index between the air layer and the display module is large. There is a problem that the image quality deteriorates.

  Therefore, it has been proposed to improve the image quality of the display by filling the gap between the protective panel and the display module with an adhesive layer. However, a frame-like printed layer may exist as a step on the display module side of the protective panel. If the pressure-sensitive adhesive layer does not follow the step, the pressure-sensitive adhesive layer floats in the vicinity of the step, thereby causing light reflection loss. For this reason, the pressure-sensitive adhesive layer is required to have a step following ability.

In order to solve the above problems, Patent Document 1 discloses a shear storage elastic modulus (G ′) (G ′) at 25 ° C. and 1 Hz as an adhesive layer that fills the gap between the protective panel and the display module. Discloses a pressure-sensitive adhesive layer having a gel fraction of 40% or more and 1.0 × 10 ⁵ Pa or less.

  In the invention disclosed in Patent Document 1, the step following ability is improved by lowering the storage elastic modulus (G ′) at normal temperature in the pressure-sensitive adhesive layer. However, when the storage elastic modulus (G ′) at normal temperature is lowered as described above, the storage elastic modulus (G ′) at high temperature is unnecessarily lowered, and a problem occurs under durability conditions. For example, when high-temperature and high-humidity conditions are applied, bubbles are generated in the vicinity of a step, or outgas is generated from a plastic plate that is a protective panel, and blisters such as bubbles, floating, and peeling are generated. On the other hand, when the pressure-sensitive adhesive layer is hardened in order to improve the blister resistance, the step following ability is lowered.

  Further, when the storage elastic modulus (G ′) of the pressure-sensitive adhesive layer is lowered as described above, the film strength of the pressure-sensitive adhesive layer is lowered and workability is deteriorated. For example, when the adhesive sheet is punched, the adhesive protrudes from the cut surface and the adhesive adheres to the blade.

  On the other hand, Patent Document 2 discloses that the pressure-sensitive adhesive layer is composed of two or more layers and the storage shear modulus of the intermediate layer is stored in the surface layer in order to solve the above-described problems of step following and workability. An adhesive sheet is disclosed in which the shear modulus is higher and the indentation hardness of the entire sheet is set within a predetermined range.

JP 2010-97070 A JP 2012-184390 A

  However, the pressure-sensitive adhesive sheet of Patent Document 2 has a problem that blistering occurs when it is affixed to a protective panel made of a plastic plate and placed in a high-temperature and high-humidity condition because the surface layer has a low storage shear modulus.

  The present invention has been made in view of such a situation, and the pressure-sensitive adhesive layer provides an adhesive sheet and a display body excellent in both step followability and blister resistance, and having good workability. Objective.

  In order to achieve the above object, first, the present invention provides a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive layer includes a first pressure-sensitive adhesive layer as an outer layer on one side, and the other side. A second pressure-sensitive adhesive layer as an outer layer on the surface side, and a third pressure-sensitive adhesive layer positioned as an intermediate layer between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer, The storage elastic modulus (G ′) at 23 ° C. of the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer and the pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer is each 0.1 MPa or more, and the third pressure-sensitive adhesive The adhesive layer is composed of an active energy ray-curable adhesive, and the storage elastic modulus (G ′) at 23 ° C. before curing of the active energy ray-curable adhesive is the adhesive constituting the first adhesive layer. Of the adhesive at 23 ° C. and 2 of the adhesive constituting the second adhesive layer Lower than the storage modulus at ° C. (G ') to provide a pressure-sensitive adhesive sheet characterized by (invention 1).

  2ndly, this invention is an adhesive sheet provided with the adhesive layer, Comprising: The said adhesive layer is the 1st adhesive layer as an outer layer of one surface side, and the 1st as an outer layer of the other surface side. 2 pressure-sensitive adhesive layers, and a third pressure-sensitive adhesive layer positioned as an intermediate layer between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer, and the first pressure-sensitive adhesive layer The 100% modulus of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive and the pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer are each 60 kPa or more, the third pressure-sensitive adhesive layer is composed of an active energy ray-curable pressure-sensitive adhesive, and the activity The 100% modulus before curing of the energy ray curable adhesive is lower than the 100% modulus of the adhesive constituting the first adhesive layer and the 100% modulus of the adhesive constituting the second adhesive layer. A pressure-sensitive adhesive sheet is provided (Invention 2)

  According to the above inventions (Inventions 1 and 2), the pressure-sensitive adhesive layer includes the third pressure-sensitive adhesive layer having a low storage elastic modulus (G ′) or 100% modulus before curing as an intermediate layer. The layer is excellent in the initial step following property, and the first adhesive layer and the second adhesive layer which are the outer layers have high storage elastic modulus (G ′) or 100% modulus, and the third adhesive layer. Is cured by irradiation with active energy rays, so that the step following ability is excellent even under high temperature and high humidity conditions. The pressure-sensitive adhesive layer has a high storage elastic modulus (G ′) or 100% modulus of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer, which are outer layers, and the third pressure-sensitive adhesive layer has active energy rays. By curing by irradiating, it becomes excellent in blister resistance. Further, the pressure-sensitive adhesive layer has the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer having a high storage elastic modulus (G ′) or 100% modulus as outer layers, and the storage elastic modulus (G ′) or 100 before curing. Good workability by using a third pressure-sensitive adhesive layer having a low% modulus as an intermediate layer and reducing the storage modulus (G ′) before curing or the cross-sectional area of the pressure-sensitive adhesive layer having a low 100% modulus. It becomes.

  In the said invention (invention 1 and 2), it is preferable that the adhesive which comprises the said 1st adhesive layer and the adhesive which comprises a 2nd adhesive layer are active energy ray non-curable adhesives. (Invention 3).

  In the above inventions (Inventions 1 to 3), the ratio of the thickness of the third pressure-sensitive adhesive layer to the total thickness of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer is 0.3 or more, 5 The following is preferable (Invention 4).

  In the said invention (invention 1-4), it is preferable that the total thickness of the said adhesive layer is 50 micrometers or more and 300 micrometers or less (invention 5).

  In the said invention (invention 1-5), it is preferable to use it for bonding one display body structural member which has a level | step difference at the surface of the side bonded together, and another display body structural member ( Invention 6).

  In the above inventions (Inventions 1 to 6), the pressure-sensitive adhesive sheet includes two release sheets, and the pressure-sensitive adhesive layer is sandwiched between the release sheets so as to be in contact with the release surfaces of the two release sheets. (Invention 7)

  3rdly, this invention is the one display body structural member which has a level | step difference in the surface on the side bonded together, another display body structural member, the said 1 display body structural member, and the said other display body structural member And a pressure-sensitive adhesive layer that is bonded to each other, wherein the pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer obtained by curing the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet (Invention 1 to 7). A characteristic display is provided (Invention 8).

  The pressure-sensitive adhesive sheet and the pressure-sensitive adhesive layer of the display body according to the present invention are excellent in both step followability and blister resistance and have good workability.

It is sectional drawing of the adhesive sheet which concerns on one Embodiment of this invention. It is sectional drawing of the laminated body which concerns on one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described.
[Adhesive sheet]
A cross-sectional view of an adhesive sheet according to an embodiment of the present invention is shown in FIG.
As shown in FIG. 1, the pressure-sensitive adhesive sheet 1 according to the present embodiment includes two release sheets 31 and 32 and the two release sheets 31 so as to be in contact with the release surfaces of the two release sheets 31 and 32. , 32 and the pressure-sensitive adhesive layer 2. In addition, the release surface of the release sheet in this specification refers to a surface having peelability in the release sheet, and includes both a surface that has been subjected to a release treatment and a surface that exhibits peelability without being subjected to a release treatment. .

  In the present embodiment, the pressure-sensitive adhesive layer 2 includes a first pressure-sensitive adhesive layer as an outer layer on one surface side (release sheet 31 side) and a second pressure-sensitive adhesive as an outer layer on the other surface side (release sheet 32 side). The adhesive layer and the 3rd adhesive layer 23 located as an intermediate | middle layer between the 1st adhesive layer 21 and the 2nd adhesive layer 22 are provided. In the present embodiment, the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22 are the outermost layers of the pressure-sensitive adhesive layer 2, respectively, and the first pressure-sensitive adhesive layer 21 is in contact with the release surface of the release sheet 31. The second pressure-sensitive adhesive layer 22 is in contact with the release surface of the release sheet 32, but is not limited to this.

  The storage elastic modulus (G ′) at 23 ° C. of the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer 21 and the pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer 22 in this embodiment is 0.1 MPa or more, respectively. Moreover, the 3rd adhesive layer 23 is comprised from an active energy ray hardening adhesive. The storage elastic modulus (G ′) at 23 ° C. before curing of the active energy ray-curable adhesive (before curing by irradiation with active energy rays) is 23 ° C. of the adhesive constituting the first adhesive layer 21. Is set lower than the storage elastic modulus (G ′) at 23 ° C. and the storage elastic modulus (G ′) at 23 ° C. of the adhesive constituting the second adhesive layer 22 (first alternative condition). .

  Or the 100% modulus of the adhesive which comprises the 1st adhesive layer 21 in this embodiment, and the adhesive which comprises the 2nd adhesive layer 22 is 60 kPa or more, respectively. Moreover, the 3rd adhesive layer 23 is comprised from an active energy ray hardening adhesive. The 100% modulus before curing of the active energy ray-curable adhesive (before curing by irradiation with active energy rays) is the 100% modulus of the adhesive constituting the first adhesive layer 21 and the second adhesive. The pressure is set lower than the 100% modulus of the pressure-sensitive adhesive constituting the layer 22 (the second alternative condition).

  The pressure-sensitive adhesive layer 2 in the present embodiment has the above three-layer structure, and each pressure-sensitive adhesive layer 21, 22, 23 satisfies the above requirements, thereby being excellent in both step followability and blister resistance and processing. Property is improved. That is, the pressure-sensitive adhesive layer 2 in the present embodiment includes the third pressure-sensitive adhesive layer 23 having a low storage elastic modulus (G ′) or 100% modulus before curing as an intermediate layer. Excellent step following capability. Furthermore, the storage elastic modulus (G ′) or 100% modulus of the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22 which are outer layers is high, and the third pressure-sensitive adhesive layer 23 is irradiated with active energy rays. By curing, the step following ability is excellent even under high temperature and high humidity conditions. For example, when the pressure-sensitive adhesive sheet according to this embodiment is affixed to a display member constituting member having a step, it is possible to prevent a gap, a float, or the like from being generated in the vicinity of the step. And even when it is left for 72 hours under high-temperature and high-humidity conditions, for example, 85 ° C. and 85% RH in that state, the occurrence of bubbles, floating, peeling, etc. in the vicinity of the step is suppressed. Further, the pressure-sensitive adhesive layer 2 in the present embodiment has a high storage elastic modulus (G ′) or 100% modulus of the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22 which are outer layers, and a third pressure-sensitive adhesive. When the agent layer 23 is cured by irradiation with active energy rays, the agent layer 23 has excellent blister resistance. For example, a display body (display) obtained by using the pressure-sensitive adhesive sheet 1 according to this embodiment is placed for 72 hours under a high-temperature and high-humidity condition, for example, 85 ° C. and 85% RH, and is made of a plastic plate or the like Even when outgas is generated from the body constituent member, the occurrence of blisters such as bubbles, floating, and peeling at the interface between the pressure-sensitive adhesive layer and the display member constituent member is suppressed. Furthermore, the pressure-sensitive adhesive layer 2 in the present embodiment has the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22 having a high storage elastic modulus (G ′) or 100% modulus as outer layers, and the storage elastic modulus before curing. (G ′) or the third pressure-sensitive adhesive layer 23 having a low 100% modulus is used as an intermediate layer. Thereby, the workability is improved by reducing the cross-sectional area of the adhesive layer portion having a low storage elastic modulus (G ′) or 100% modulus before curing in the entire adhesive layer 2. Therefore, for example, when the pressure-sensitive adhesive sheet 1 is punched or the like, problems such as the pressure-sensitive adhesive protruding from the cut surface and the pressure-sensitive adhesive adhering to the blade are suppressed.

  As described above, as the first alternative condition, the storage elastic modulus (G ′) at 23 ° C. of the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer 21 and the pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer 22 is as follows. These are each 0.1 MPa or more, preferably 0.12 MPa or more, and particularly preferably 0.14 MPa or more. Further, the storage elastic modulus (G ′) is preferably 0.5 MPa or less, particularly preferably 0.25 MPa or less, and further preferably 0.18 MPa or less. When the storage elastic modulus (G ′) is 0.5 MPa or less, the step following property of the pressure-sensitive adhesive layer 2 can be maintained high. Note that the storage elastic modulus (G ′) at 23 ° C. of the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer 21 and the storage elastic modulus (G ′) at 23 ° C. of the pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer 22 are May be the same or different.

  Further, as a first alternative condition, the storage elastic modulus (G ′) at 23 ° C. before curing of the active energy ray-curable pressure-sensitive adhesive constituting the third pressure-sensitive adhesive layer 23 is the first pressure-sensitive adhesive layer. The storage elastic modulus (G ′) at 23 ° C. of the pressure-sensitive adhesive constituting 21 and the storage elastic modulus (G ′) at 23 ° C. of the pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer 22 are set lower. As a specific numerical value, the storage elastic modulus (G ′) is preferably 0.10 MPa or less, particularly preferably 0.09 MPa or less, and further preferably 0.08 MPa or less. Thereby, the level | step difference followability of the adhesive layer 2 can be made more excellent. Further, the storage elastic modulus (G ′) is preferably 0.01 MPa or more, particularly preferably 0.03 MPa or more, and further preferably 0.06 MPa or more. Thereby, the workability of the pressure-sensitive adhesive layer 2 can be improved. In addition, the measuring method of the said storage elastic modulus (G ') is as showing in the test example mentioned later.

  Here, the storage elastic modulus (G ′) at 23 ° C. after curing of the active energy ray-curable adhesive constituting the third pressure-sensitive adhesive layer 23 (after curing by irradiation with active energy rays) is 0.1 MPa or more. Preferably, it is preferably 0.11 MPa or more, more preferably 0.12 MPa or more. Thereby, the blister resistance of the pressure-sensitive adhesive layer 2 and the step following property under high temperature and high humidity conditions can be further improved. On the other hand, the storage elastic modulus (G ′) is preferably 0.5 MPa or less, particularly preferably 0.3 MPa or less, and further preferably 0.18 MPa or less. Thereby, it becomes possible to maintain the adhesive force of the 3rd adhesive layer 23, especially the adhesive force with respect to the 1st adhesive layer 21 and the 2nd adhesive layer 22 highly.

  In addition, the storage elastic modulus (G ′) at 23 ° C. after curing of the active energy ray-curable pressure-sensitive adhesive constituting the third pressure-sensitive adhesive layer 23 is 23 ° C. of the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer 21. The storage elastic modulus (G ′) at 2 ° C. and the storage elastic modulus (G ′) at 23 ° C. of the pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer 22 may be smaller or larger, and both are equal. Also good. Among these, the storage elastic modulus (G ′) at 23 ° C. after curing of the active energy ray-curable pressure-sensitive adhesive constituting the third pressure-sensitive adhesive layer 23 is that of the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer 21. The storage elastic modulus (G ′) at 23 ° C. and the storage elastic modulus (G ′) at 23 ° C. of the pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer 22 are preferably larger. Thereby, the blister resistance of the pressure-sensitive adhesive layer 2 and the step following property under high temperature and high humidity conditions become more excellent.

  As described above, as a second alternative condition, the 100% modulus of the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer 21 and the pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer 22 are each 60 kPa or more, Preferably it is 70 kPa or more, Most preferably, it is 80 kPa or more. The 100% modulus is preferably 150 kPa or less, particularly preferably 140 kPa or less, and further preferably 130 kPa or less. When the 100% modulus is 150 kPa or less, the step following property of the pressure-sensitive adhesive layer 2 can be maintained high. The 100% modulus of the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer 21 and the 100% modulus of the pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer 22 may be the same or different. .

  In addition, as a second alternative condition, the 100% modulus before curing of the active energy ray-curable pressure-sensitive adhesive constituting the third pressure-sensitive adhesive layer 23 is equal to that of the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer 21. The 100% modulus and the 100% modulus of the pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer 22 are set lower. As a specific numerical value, the storage elastic modulus (G ′) is preferably 60 kPa or less, particularly preferably 50 kPa or less, and further preferably 40 kPa or less. Thereby, the level | step difference followability of the adhesive layer 2 can be made more excellent. The 100% modulus is preferably 5 kPa or more, particularly preferably 10 kPa or more, and further preferably 15 kPa or more. Thereby, the workability of the pressure-sensitive adhesive layer 2 can be improved. In addition, the measuring method of the said 100% modulus is as showing to the test example mentioned later.

  Here, the 100% modulus after curing of the active energy ray-curable pressure-sensitive adhesive constituting the third pressure-sensitive adhesive layer 23 (after curing by irradiation with active energy rays) is preferably 30 kPa or more, particularly 40 kPa or more. It is preferable that there is, more preferably 50 kPa or more. Thereby, the blister resistance of the pressure-sensitive adhesive layer 2 and the step following property under high temperature and high humidity conditions can be further improved. On the other hand, the 100% modulus is preferably 300 kPa or less, particularly preferably 200 kPa or less, and more preferably 180 kPa or less. Thereby, it becomes possible to maintain the adhesive force of the 3rd adhesive layer 23, especially the adhesive force with respect to the 1st adhesive layer 21 and the 2nd adhesive layer 22 highly.

  The 100% modulus after curing of the active energy ray-curable pressure-sensitive adhesive constituting the third pressure-sensitive adhesive layer 23 (after curing by irradiation with active energy rays) is that of the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer 21. The 100% modulus and the 100% modulus of the pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer 22 may be smaller or larger, or both may be equal. Among these, the 100% modulus after curing of the active energy ray-curable pressure-sensitive adhesive constituting the third pressure-sensitive adhesive layer 23 is equal to the 100% modulus of the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer 21 and the second It is preferably larger than the 100% modulus of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 22. Thereby, the blister resistance of the pressure-sensitive adhesive layer 2 and the step following property under high temperature and high humidity conditions become more excellent.

  The ratio of the thickness of the third pressure-sensitive adhesive layer 23 to the total thickness of the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22 is preferably 0.3 or more, particularly 0.4 or more. It is preferable that it is 0.5 or more. Further, the ratio is preferably 5 or less, particularly preferably 3 or less, further preferably 2 or less, and most preferably 0.8 or less. When the ratio falls within the above range, the above-described effects of step following ability, blister resistance, and workability can be exhibited more satisfactorily. The thickness of each layer is a value measured according to JIS K7130.

  The total thickness of the pressure-sensitive adhesive layer 2 is preferably 50 μm or more, particularly preferably 75 μm or more, and more preferably 100 μm or more. The total thickness is preferably 300 μm or less, particularly preferably 250 μm or less, and more preferably 200 μm or less. When the total thickness of the pressure-sensitive adhesive layer 2 falls within the above range, the effects of the step followability, blister resistance, and workability described above are more satisfactorily exhibited.

  The thickness of the first pressure-sensitive adhesive layer 21 and the thickness of the second pressure-sensitive adhesive layer 22 are each preferably 25 μm or more, particularly preferably 30 μm or more, and more preferably 50 μm or more. . The thickness is preferably 100 μm or less, particularly preferably 80 μm or less, and more preferably 75 μm or less. When the thickness is within the above range, the effects of the step followability, the blister resistance, and the workability described above are more effectively exhibited. In addition, the thickness of the 1st adhesive layer 21 and the thickness of the 2nd adhesive layer 22 may be the same, and may differ.

  The thickness of the third pressure-sensitive adhesive layer 23 is preferably 25 μm or more, particularly preferably 30 μm or more, and further preferably 50 μm or more. The thickness is preferably 150 μm or less, particularly preferably 125 μm or less, more preferably 100 μm or less, and most preferably 75 μm or less. When the thickness is within the above range, the effects of the step followability, the blister resistance, and the workability described above are more effectively exhibited.

1. The first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer The pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer and the pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer are particularly limited as long as they satisfy the above-described physical properties. However, it may be an active energy ray-curable adhesive or an active energy ray non-curable adhesive, but is preferably an active energy ray non-curable adhesive. Thereby, the adhesiveness (adhesive force) with respect to the to-be-adhered body (especially display body structural member) after irradiating the adhesive layer 2 with an active energy ray can be maintained higher. Note that the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer and the pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer may be the same pressure-sensitive adhesive or different pressure-sensitive adhesives.

  Hereinafter, the active energy ray non-curable adhesive will be mainly described. In the case of an active energy ray-curable pressure-sensitive adhesive, a pressure-sensitive adhesive similar to the active energy ray-curable pressure-sensitive adhesive constituting the third pressure-sensitive adhesive layer 23 described later can be used.

  Examples of the active energy ray non-curable adhesive constituting the first adhesive layer and the second adhesive layer include, for example, an acrylic adhesive, a rubber adhesive, a silicone adhesive, a urethane adhesive, Any of a polyester-based pressure-sensitive adhesive, a polyvinyl ether-based pressure-sensitive adhesive, or the like may be used. The pressure-sensitive adhesive may be any of an emulsion type, a solvent type, or a solventless type, and may be a crosslinked type or a non-crosslinked type.

  Among these, acrylic adhesives are preferable. In that case, the pressure-sensitive adhesive in the present embodiment is obtained from a pressure-sensitive adhesive composition containing the (meth) acrylic acid ester polymer (A) (hereinafter sometimes referred to as “pressure-sensitive adhesive composition P”). It is preferable. The pressure-sensitive adhesive composition P preferably further contains a crosslinking agent (B). In that case, the pressure-sensitive adhesive in the present embodiment is obtained by crosslinking the pressure-sensitive adhesive composition P. In this specification, (meth) acrylic acid ester means both acrylic acid ester and methacrylic acid ester. The same applies to other similar terms. Further, the “polymer” includes the concept of “copolymer”.

(1) (Meth) acrylic acid ester polymer (A)
The (meth) acrylic acid ester polymer (A) contains a (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group as a monomer unit constituting the polymer. Can be expressed. From such a viewpoint, the (meth) acrylic acid ester polymer (A) has a lower limit of 50 (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms as the monomer unit constituting the polymer. It is preferably contained in an amount of at least mass%, particularly preferably at least 60 mass%, more preferably at least 70 mass%. When the (meth) acrylic acid alkyl ester is contained in an amount of 50% by mass or more, the (meth) acrylic acid ester polymer (A) can exhibit suitable tackiness. The (meth) acrylic acid ester polymer (A) preferably contains 97% by mass or less of the above (meth) acrylic acid alkyl ester as a monomer unit constituting the polymer, and particularly 90% by mass. % Or less, preferably 85% by mass or less. By containing 97% by mass or less of the (meth) acrylic acid alkyl ester, a suitable amount of other monomer components can be introduced into the (meth) acrylic acid ester polymer (A).

  Examples of the (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and (meth) acrylic acid n-. Butyl, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, n-decyl (meth) acrylate, (meth) acrylic acid n-dodecyl, myristyl (meth) acrylate, palmityl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, adamantyl (meth) acrylate, etc. Among these, from the viewpoint of further improving the adhesiveness, the alkyl group having 4 to 8 carbon atoms is a (meth) a. It is preferred to include acrylic acid esters. These may be used alone or in combination of two or more. In addition, the alkyl group in the (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group refers to a linear, branched or cyclic alkyl group.

  Further, as a (meth) acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms, a hard monomer having a glass transition temperature (Tg) exceeding 0 ° C. (preferably 70 ° C. or more) as a homopolymer, and a homopolymer It is also preferable to use in combination with a soft monomer having a glass transition temperature (Tg) of 0 ° C. or less. This is because the step followability can be further improved by improving cohesion with the hard monomer while ensuring adhesiveness and flexibility with the soft monomer. In this case, the mass ratio of the hard monomer to the soft monomer is preferably 5:95 to 40:60, and particularly preferably 20:80 to 30:70.

  Examples of the hard monomer include methyl acrylate (Tg 10 ° C.), methyl methacrylate (Tg 105 ° C.), isobornyl acrylate (Tg 94 ° C.), isobornyl methacrylate (Tg 180 ° C.), adamantyl acrylate (Tg 115 ° C.), and methacrylic acid. And adamantyl (Tg 141 ° C.). These may be used alone or in combination of two or more.

  Among the hard monomers, methyl acrylate, methyl methacrylate, and isobornyl acrylate are preferable from the viewpoint of further exerting the performance of the hard monomer while preventing adverse effects on other properties such as adhesiveness and transparency. In view of tackiness, methyl acrylate and methyl methacrylate are more preferable, and methyl methacrylate is particularly preferable.

  Preferable examples of the soft monomer include acrylic acid alkyl esters having a linear or branched alkyl group having 2 to 12 carbon atoms. For example, 2-ethylhexyl acrylate (Tg-70 ° C.), n-butyl acrylate (Tg-54 ° C.) and the like are preferable. These may be used alone or in combination of two or more.

  The (meth) acrylic acid ester polymer (A) preferably contains a reactive functional group-containing monomer as a monomer unit constituting the polymer. The reactive functional group derived from this reactive functional group-containing monomer reacts with the crosslinking agent (B) described later, thereby forming a crosslinked structure (three-dimensional network structure), and obtaining a pressure-sensitive adhesive having a desired cohesive force. It is done.

  The reactive functional group-containing monomer contained in the (meth) acrylic acid ester polymer (A) as a monomer unit constituting the polymer includes a monomer having a hydroxyl group in the molecule (hydroxyl group-containing monomer) and a carboxyl in the molecule. Preferred examples include a monomer having a group (carboxyl group-containing monomer) and a monomer having an amino group in the molecule (amino group-containing monomer). Among these, a hydroxyl group-containing monomer that is excellent in reactivity with the crosslinking agent (B) and has little adverse effect on the adherend is particularly preferable.

  Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, (meth And (meth) acrylic acid hydroxyalkyl esters such as 3-hydroxybutyl acrylate and 4-hydroxybutyl (meth) acrylate. Among them, 2-hydroxyethyl (meth) acrylate is preferred from the viewpoint of the reactivity of the hydroxyl group in the resulting (meth) acrylic acid ester polymer (A) with the crosslinking agent (B) and the copolymerizability with other monomers. Or 4-hydroxybutyl (meth) acrylate is preferable. These may be used alone or in combination of two or more.

  Examples of the carboxyl group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. Among these, acrylic acid is preferable from the viewpoint of the reactivity of the resulting (meth) acrylic acid ester polymer (A) with the crosslinking agent (B) of the carboxyl group and the copolymerizability with other monomers. These may be used alone or in combination of two or more.

  Examples of the amino group-containing monomer include aminoethyl (meth) acrylate, n-butylaminoethyl (meth) acrylate, and the like. These may be used alone or in combination of two or more.

When the (meth) acrylic acid ester polymer (A) contains a hydroxyl group-containing monomer as a monomer unit constituting the polymer, the content is preferably 3% by mass or more as a lower limit, particularly 10% by mass. % Or more, and more preferably 15% by mass or more. The content is preferably 35% by mass or less as an upper limit, particularly preferably 30% by mass or less, and further preferably 25% by mass or less. When the (meth) acrylic acid ester polymer (A) contains a hydroxyl group-containing monomer in the above amount as a monomer unit, a predetermined amount of hydroxyl group remains in the resulting adhesive. A hydroxyl group is a hydrophilic group, and when such a hydrophilic group is present in a pressure-sensitive adhesive, even if the pressure-sensitive adhesive is placed under a high temperature and high humidity condition, it penetrates into the pressure sensitive adhesive under the high temperature and high humidity condition. As a result, the whitening of the pressure-sensitive adhesive when it is returned to room temperature and normal humidity is suppressed (excellent moisture and heat whitening resistance).

  When the (meth) acrylic acid ester polymer (A) contains a carboxy group-containing monomer as a monomer unit constituting the polymer, the content is preferably 0.5% by mass or more as a lower limit, It is more preferably 1% by mass or more, and particularly preferably 6% by mass or more. Moreover, it is preferable that the content is 20 mass% or less as an upper limit, It is more preferable that it is 15 mass% or less, It is especially preferable that it is 10 mass% or less.

  In addition, in the case where the adherend is easily affected by an acid, such as a transparent conductive film or a metal wiring, the (meth) acrylic acid ester polymer (A) is used as a monomer unit constituting the polymer. It is preferable not to contain a carboxyl group-containing monomer. Thereby, for example, it is possible to suppress corrosion of the transparent conductive film and the metal wiring, and change of the resistance value of the transparent conductive film.

  Here, “not containing a monomer having a carboxyl group” means substantially not containing a monomer having a carboxyl group, and contains no carboxyl group-containing monomer at all. It is allowed to contain a carboxyl group-containing monomer to such an extent that corrosion of wiring or the like does not occur. Specifically, the carboxyl group-containing monomer is contained in the (meth) acrylic acid ester polymer (A) as a monomer unit in an amount of 0.01% by mass or less, preferably 0.001% by mass or less. It is acceptable.

  The (meth) acrylic acid ester polymer (A) may contain other monomers as monomer units constituting the polymer, if desired. The other monomer is preferably a monomer that does not contain a reactive functional group so as not to interfere with the action of the reactive functional group-containing monomer. Examples of such other monomers include (meth) acrylic acid alkoxyalkyl esters such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, (meth) ) N, N-dimethylaminopropyl acrylate, (meth) acrylic acid ester having a non-crosslinkable tertiary amino group such as (meth) acryloylmorpholine, (meth) acrylamide, dimethylacrylamide, vinyl acetate, styrene, etc. It is done. These may be used alone or in combination of two or more.

  The polymerization mode of the (meth) acrylic acid ester polymer (A) may be a random copolymer or a block copolymer.

  The lower limit of the weight average molecular weight of the (meth) acrylic acid ester polymer (A) is preferably 200,000 or more, particularly preferably 300,000 or more, and more preferably 400,000 or more. In addition, the weight average molecular weight in this specification is the value of standard polystyrene conversion measured by the gel permeation chromatography (GPC) method. When the lower limit of the weight average molecular weight of the (meth) acrylic acid ester polymer (A) is not less than the above, the pressure-sensitive adhesive will be more excellent in blister resistance and step following ability under high temperature and high humidity conditions.

  The upper limit of the weight average molecular weight of the (meth) acrylic acid ester polymer (A) is preferably 1,000,000 or less, particularly preferably 900,000 or less, and more preferably 700,000 or less. preferable. When the upper limit value of the weight average molecular weight of the (meth) acrylic acid ester polymer (A) is not more than the above, the pressure-sensitive adhesive is more excellent in the step following ability at the time of sticking.

  In the adhesive composition P, the (meth) acrylic acid ester polymer (A) may be used singly or in combination of two or more.

(2) Crosslinking agent (B)
The adhesive composition P preferably contains a crosslinking agent (B). The pressure-sensitive adhesive composition P contains the cross-linking agent (B), thereby cross-linking the (meth) acrylic acid ester polymer (A) to form a three-dimensional network structure and improving the cohesive strength of the resulting pressure-sensitive adhesive. Thus, the blister resistance and the step following ability under high temperature and high humidity conditions can be further improved.

  As a crosslinking agent (B), what is necessary is just to react with the reactive group which (meth) acrylic acid ester polymer (A) has, for example, an isocyanate type crosslinking agent, an epoxy type crosslinking agent, an amine type crosslinking agent, Melamine-based crosslinking agents, aziridine-based crosslinking agents, hydrazine-based crosslinking agents, aldehyde-based crosslinking agents, oxazoline-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, ammonium salt-based crosslinking agents, etc. Can be mentioned. When the (meth) acrylic acid ester polymer (A) contains a hydroxyl group-containing monomer as a monomer unit constituting the polymer, it is preferable to use an isocyanate-based crosslinking agent excellent in reactivity with the hydroxyl group. Moreover, when the (meth) acrylic acid ester polymer (A) contains a carboxyl group-containing monomer as a monomer unit constituting the polymer, an epoxy-based crosslinking agent having excellent reactivity with the carboxyl group is used. It is preferable. In addition, a crosslinking agent (B) can be used individually by 1 type or in combination of 2 or more types.

  The isocyanate-based crosslinking agent contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate, and the like. , And their biuret bodies, isocyanurate bodies, and adduct bodies that are a reaction product with low molecular active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. Among these, trimethylolpropane-modified aromatic polyisocyanate, particularly trimethylolpropane-modified tolylene diisocyanate is preferable from the viewpoint of reactivity with hydroxyl groups.

  Examples of the epoxy crosslinking agent include 1,3-bis (N, N′-diglycidylaminomethyl) cyclohexane, N, N, N ′, N′-tetraglycidyl-m-xylylenediamine, ethylene glycol diglycidyl. Examples include ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, diglycidyl amine and the like. Among these, 1,3-bis (N, N′-diglycidylaminomethyl) cyclohexane is preferable from the viewpoint of reactivity with a carboxyl group.

  The content of the crosslinking agent (B) in the adhesive composition P is preferably 0.001 part by mass or more as a lower limit with respect to 100 parts by mass of the (meth) acrylic acid ester polymer (A), In particular, it is preferably 0.01 parts by mass or more, and more preferably 0.02 parts by mass or more. Moreover, it is preferable that it is 10 mass parts or less as an upper limit, It is especially preferable that it is 5 mass parts or less, Furthermore, it is preferable that it is 1 mass part or less.

  When the content of the crosslinking agent (B) is in the above range, the cohesive force of the obtained pressure-sensitive adhesive becomes preferable, and the blister resistance of the pressure-sensitive adhesive and the step following property under high temperature and high humidity conditions are improved.

(3) Various additives For the adhesive composition P, various additives usually used for acrylic pressure-sensitive adhesives, for example, silane coupling agents, antistatic agents, tackifiers, antioxidants, ultraviolet rays, if desired. Absorbers, light stabilizers, softeners, fillers, refractive index adjusters and the like can be added.

  The pressure-sensitive adhesive composition P represents a mixture of various components that remain in the pressure-sensitive adhesive layer or in a reacted state, and is a component that is removed in a drying step or the like, for example, polymerization described later. Solvents and dilution solvents are not included in the adhesive composition P.

  Here, when the pressure-sensitive adhesive composition P contains a silane coupling agent, the resulting pressure-sensitive adhesive has improved adhesion to a glass member or a plastic plate. Thereby, the obtained adhesive becomes excellent in the blister resistance and the step following property under high temperature and high humidity conditions.

  As the silane coupling agent, an organosilicon compound having at least one alkoxysilyl group in the molecule, having good compatibility with the (meth) acrylic acid ester polymer (A), and having light transmittance. preferable.

  Examples of the silane coupling agent include polymerizable unsaturated group-containing silicon compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, and methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 2- ( 3,4-epoxycyclohexyl) silicon compounds having an epoxy structure such as ethyltrimethoxysilane, mercapto group-containing silicon compounds such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, and 3-mercaptopropyldimethoxymethylsilane Amino group-containing silicon such as 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane Compound, 3-chloropropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, or at least one of them, and alkyl group-containing silicon such as methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane Examples include condensates with compounds. These may be used individually by 1 type and may be used in combination of 2 or more type.

  When the adhesive composition P contains a silane coupling agent, the content thereof is 0.01 parts by mass or more as a lower limit with respect to 100 parts by mass of the (meth) acrylic acid ester polymer (A). In particular, it is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more. In addition, the content is preferably 5 parts by mass or less, particularly preferably 1 part by mass or less, and more preferably 0.5 parts by mass or less as an upper limit.

(4) Manufacture of adhesive composition The adhesive composition P manufactured the (meth) acrylic acid ester polymer (A), and cross-linked the obtained (meth) acrylic acid ester polymer (A) as desired. It can manufacture by adding an agent (B) and an additive.

  The (meth) acrylic acid ester polymer (A) can be produced by polymerizing a mixture of monomers constituting the polymer by an ordinary radical polymerization method. The polymerization of the (meth) acrylic acid ester polymer (A) is preferably carried out by a solution polymerization method using a polymerization initiator if desired. Examples of the polymerization solvent include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone, and the like. Two or more kinds may be used in combination.

  Examples of the polymerization initiator include azo compounds and organic peroxides, and two or more kinds may be used in combination. Examples of the azo compound include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), 1,1′-azobis (cyclohexane 1-carbonitrile), 2 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (2,4-dimethyl-4-methoxyvaleronitrile), dimethyl 2,2′-azobis (2-methylpropionate) 4,4′-azobis (4-cyanovaleric acid), 2,2′-azobis (2-hydroxymethylpropionitrile), 2,2′-azobis [2- (2-imidazolin-2-yl) Propane] and the like.

  Examples of organic peroxides include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, and di (2-ethoxyethyl) peroxy. Examples include dicarbonate, t-butyl peroxyneodecanoate, t-butyl peroxybivalate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, diacetyl peroxide and the like.

  In addition, in the said superposition | polymerization process, the weight average molecular weight of the polymer obtained can be adjusted by mix | blending chain transfer agents, such as 2-mercaptoethanol.

  When the (meth) acrylic acid ester polymer (A) is obtained, the crosslinking agent (B), the additive and the diluting solvent are added to the solution of the (meth) acrylic acid ester polymer (A) as required. By mixing, adhesive composition P (coating solution) diluted with a solvent is obtained. When any of the above components is used in a solid state or when precipitation occurs when mixed with other components in an undiluted state, the component is used alone as a dilution solvent. It may be dissolved or diluted and then mixed with other components.

  Examples of the dilution solvent include aliphatic hydrocarbons such as hexane, heptane, and cyclohexane, aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as methylene chloride and ethylene chloride, methanol, ethanol, propanol, butanol, Alcohols such as 1-methoxy-2-propanol, ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, and cyclohexanone, esters such as ethyl acetate and butyl acetate, and cellosolve solvents such as ethyl cellosolve are used.

  The concentration / viscosity of the coating solution thus prepared is not particularly limited as long as it can be coated, and can be appropriately selected depending on the situation. For example, it dilutes so that the density | concentration of the adhesive composition P may be 10-60 mass%. In addition, when obtaining a coating solution, addition of a dilution solvent etc. is not a necessary condition, and if a viscosity etc. which can be coated with the adhesive composition P are not necessary, a dilution solvent does not need to be added. In this case, the adhesive composition P becomes a coating solution using the polymerization solvent of the (meth) acrylic acid ester polymer (A) as a dilution solvent.

(5) Production of pressure-sensitive adhesive The pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer 21 and the pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer 22 can be preferably obtained by crosslinking the pressure-sensitive adhesive composition P. The crosslinking of the pressure-sensitive adhesive composition P can be usually performed by heat treatment. In addition, this heat processing can also serve as the drying process at the time of volatilizing a dilution solvent etc. from the coating film of the adhesive composition P apply | coated to the desired target object.

  The heating temperature of the heat treatment is preferably 50 to 150 ° C, and particularly preferably 70 to 120 ° C. The heating time is preferably 10 seconds to 10 minutes, particularly preferably 50 seconds to 2 minutes.

  After the heat treatment, if necessary, a curing period of about 1 to 2 weeks may be provided at room temperature (for example, 23 ° C., 50% RH). When this curing period is necessary, after the curing period has elapsed, and when the curing period is unnecessary, an adhesive is formed after the heat treatment.

  By the above heat treatment (and curing) (when the crosslinking agent (B) is contained, the (meth) acrylic acid ester polymer (A) is sufficiently crosslinked via the crosslinking agent (B)). .

(6) Gel fraction It is preferable that the gel fraction of the adhesive which comprises the 1st adhesive layer 21 and the adhesive which comprises the 2nd adhesive layer 22 is 50% or more as a lower limit, especially It is preferably 60% or more, and more preferably 65% or more. When the gel fraction of the pressure-sensitive adhesive is 50% or more, the cohesive force of the pressure-sensitive adhesive becomes high, and the blister resistance of the pressure-sensitive adhesive layer 2 and the step following property under high temperature and high humidity become better. The gel fraction of the pressure-sensitive adhesive is preferably 85% or less as an upper limit, particularly preferably 80% or less, and more preferably 75% or less. When the gel fraction of the pressure-sensitive adhesive is 85% or less, the pressure-sensitive adhesive does not become too hard, and the step followability becomes more excellent. Here, the measuring method of the gel fraction of an adhesive is as showing to the test example mentioned later.

(7) Adhesive strength The adhesive strength of the first pressure-sensitive adhesive layer 21 (laminated body with the base material) and the second pressure-sensitive adhesive layer 22 (laminated body with the base material) with respect to soda lime glass is a lower limit value. It is preferably 5 N / 25 mm or more, particularly preferably 10 N / 25 mm or more, and more preferably 15 N / 25 mm or more. When the adhesive force is not less than the above, the blister resistance and the step following property under high temperature and high humidity conditions are more excellent. The adhesive strength is preferably 50 N / 25 mm or less as an upper limit, particularly preferably 40 N / 25 mm or less, and more preferably 35 N / 25 mm or less. When the adhesive force is not more than the above, good reworkability can be obtained, and when a bonding error occurs, it is possible to reuse an expensive display member constituting member.

  Here, the adhesive force in the present specification basically means an adhesive force measured by a 180-degree peeling method according to JIS Z0237: 2009. The measurement sample is 25 mm wide and 100 mm long. Affixed to the adherend, pressurized at 0.5 MPa, 50 ° C. for 20 minutes, left under normal pressure, 23 ° C., 50% RH for 24 hours, and then measured at a peeling rate of 300 mm / min. Shall. As the substrate, a polyethylene terephthalate film having a thickness of 100 μm is used.

(8) Step following rate The step following rate (%) represented by the following formula of the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22 is preferably 10% or more as a lower limit, and particularly It is preferably 15% or more, and more preferably 20% or more. In addition, the step following rate (%) is preferably 50% or less as an upper limit value, particularly preferably 45% or less, and further preferably 40% or less.
Step follow-up rate (%) = {(the height of the step (μm) in which the buried state is maintained without bubbles, floats, peeling, etc. after a predetermined durability test) / (thickness of the adhesive layer)} × 100
In addition, the test method of a level | step difference tracking rate is as showing to the test example mentioned later.

  Due to the step following rate of the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22 as the outer layer being in the above range, the pressure-sensitive adhesive layer 2 of the pressure-sensitive adhesive sheet 1 according to the present embodiment has a step following property. It becomes easy to become excellent.

2. 3rd adhesive layer The active energy ray hardening adhesive which comprises the 3rd adhesive layer 23 will not be specifically limited if the physical property mentioned above is satisfy | filled. The active energy ray-curable pressure-sensitive adhesive preferably contains at least one of active energy ray-curable monomers, oligomers and polymers, or a mixture thereof, in addition to the active energy ray-curable monomer, Any of oligomers and polymers, or a mixture thereof may be contained.

  In this embodiment, the active energy ray-curable pressure-sensitive adhesive constituting the third pressure-sensitive adhesive layer 23 contains a (meth) acrylic acid ester polymer (C) and an active energy ray-curable compound (D). It is preferable that it is obtained from the adhesive composition Q. It is preferable that the adhesive composition Q further contains a crosslinking agent (B). In that case, the active energy ray-curable adhesive is obtained by crosslinking the adhesive composition Q.

(1) (Meth) acrylic acid ester polymer (C)
The (meth) acrylic acid ester polymer (C) basically has the above-mentioned (meth) acrylic acid as long as the active energy ray-curable pressure-sensitive adhesive constituting the third pressure-sensitive adhesive layer 23 satisfies the physical properties described above. The same as in the ester polymer (A). However, since the third pressure-sensitive adhesive layer 23 is an intermediate layer and does not directly contact the adherend, the (meth) acrylate polymer (C) is used as a monomer unit constituting the polymer. It is also preferable to contain a carboxyl group-containing monomer.

  The (meth) acrylic acid ester polymer (C) also preferably contains a nitrogen atom-containing monomer as a monomer unit constituting the polymer. By allowing the nitrogen atom-containing monomer to be present in the polymer as a structural unit, the crosslinking reaction between the reactive functional group of the (meth) acrylic acid ester polymer (C) and the crosslinking agent (B) can be promoted. Examples of the nitrogen atom-containing monomer include a monomer having an amino group, a monomer having an amide group, and a monomer having a nitrogen-containing heterocyclic ring. Among them, the (meth) acrylic acid ester polymer (C) has an appropriate rigidity. From the viewpoint of imparting, a monomer having a nitrogen-containing heterocyclic ring is preferable.

  Examples of the monomer having a nitrogen-containing heterocyclic ring include N- (meth) acryloylmorpholine, N-vinyl-2-pyrrolidone, N- (meth) acryloylpyrrolidone, N- (meth) acryloylpiperidine, N- (meth) acryloyl. Pyrrolidine, N- (meth) acryloylaziridine, aziridinylethyl (meth) acrylate, 2-vinylpyridine, 4-vinylpyridine, 2-vinylpyrazine, 1-vinylimidazole, N-vinylcarbazole, N-vinylphthalimide, etc. Among them, N- (meth) acryloylmorpholine exhibiting more excellent adhesive strength is preferable, and N-acryloylmorpholine is particularly preferable.

Examples of nitrogen atom-containing monomers include (meth) acrylamide, N-methyl (meth) acrylamide, N-methylol (meth) acrylamide, N-tert-butyl (meth) acrylamide, and N, N-dimethyl (meth) acrylamide. N, N-ethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-phenyl (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, N-vinyl Caprolactam, monomethylaminoethyl (meth) acrylate, monoethylaminoethyl (meth) acrylate, monomethylaminopropyl (meth) acrylate, monoethylaminopropyl (meth) acrylate, dimethylamino (meth) acrylate It is also possible to use the chill and the like.
The above nitrogen atom containing monomers may be used individually by 1 type, and may be used in combination of 2 or more type.

  When the (meth) acrylic acid ester polymer (C) contains a nitrogen atom-containing monomer as a monomer unit constituting the polymer, the nitrogen atom-containing monomer is preferably contained in an amount of 1% by mass or more, particularly 2% by mass. % Or more, preferably 3% by mass or more. Further, the (meth) acrylic acid ester polymer (A) preferably contains 20% by mass or less of the nitrogen atom-containing monomer as a monomer unit constituting the polymer, and particularly 15% by mass or less. More preferably, the content is preferably 10% by mass or less. When the content of the nitrogen atom-containing monomer is within the above range, the effect of promoting the crosslinking reaction between the (meth) acrylic acid ester polymer (C) and the crosslinking agent (B) can be favorably obtained.

(2) Active energy ray-curable compound (D)
When the adhesive composition Q contains the active energy ray-curable compound (D), the active energy ray-curable adhesive obtained by thermally crosslinking the adhesive composition Q is cured by irradiation with active energy rays. In addition, the active energy ray-curable compound (D) is polymerized with each other, and the polymerized active energy ray-curable compound (D) becomes a crosslinked structure (three-dimensional network structure) of the (meth) acrylate polymer (A). Presumed to be entangled. Since the pressure-sensitive adhesive having such a higher-order structure has a high cohesive force and a relatively high elastic modulus, the pressure-sensitive adhesive layer 2 having the third pressure-sensitive adhesive layer 23 in the intermediate layer is more excellent in blister resistance. .

  The active energy ray-curable compound (D) is not particularly limited as long as it is a compound that is cured by irradiation with active energy rays and can obtain the above-described effects, and may be any of a monomer, an oligomer, or a polymer, or It may be a mixture of Among them, a polyfunctional acrylate monomer having a molecular weight of less than 1000 that is excellent in compatibility with the (meth) acrylic acid ester polymer (C) and the like can be preferably exemplified.

  Examples of polyfunctional acrylate monomers having a molecular weight of less than 1000 include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, and polyethylene glycol diene. (Meth) acrylate, neopentyl glycol adipate di (meth) acrylate, hydroxypivalic acid neopentyl glycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone modified dicyclopentenyl di (meth) acrylate, ethylene oxide modified Di (meth) acrylate phosphate, di (acryloxyethyl) isocyanurate, allylated cyclohexyl di (meth) acrylate, ethoxylated bisphenol A diacrylate, 9,9-bi Bifunctional type such as [4- (2-acryloyloxyethoxy) phenyl] fluorene; trimethylolpropane tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, propionic acid-modified dipentaerythritol tri (meth) acrylate, penta Trifunctional such as erythritol tri (meth) acrylate, propylene oxide modified trimethylolpropane tri (meth) acrylate, tris (acryloxyethyl) isocyanurate, ε-caprolactone modified tris- (2- (meth) acryloxyethyl) isocyanurate Type; tetrafunctional type such as diglycerin tetra (meth) acrylate and pentaerythritol tetra (meth) acrylate; pentafunctional type such as propionic acid-modified dipentaerythritol penta (meth) acrylate And hexafunctional types such as dipentaerythritol hexa (meth) acrylate and caprolactone-modified dipentaerythritol hexa (meth) acrylate. Among these, pentaerythritol tri (meth) acrylate and ε-caprolactone-modified tris- (2- (meth) acryloxyethyl) isocyanurate are preferable from the viewpoint of blister resistance of the obtained pressure-sensitive adhesive. These may be used individually by 1 type and may be used in combination of 2 or more type.

  As the active energy ray-curable compound (D), an active energy ray-curable acrylate oligomer can also be used. The acrylate oligomer preferably has a weight average molecular weight of 50,000 or less. Examples of such acrylate oligomers include polyester acrylate, epoxy acrylate, urethane acrylate, polyether acrylate, polybutadiene acrylate, and silicone acrylate.

  The weight average molecular weight of the acrylate oligomer is preferably 50,000 or less as an upper limit, and particularly preferably 40,000 or less. Further, the weight average molecular weight is preferably 500 or more as a lower limit, and particularly preferably 3,000 or more. These acrylate oligomers may be used alone or in combination of two or more.

  Moreover, as the active energy ray-curable compound (D), an adduct acrylate polymer in which a group having a (meth) acryloyl group is introduced into the side chain can also be used. Such an adduct acrylate-based polymer uses a copolymer of (meth) acrylic acid ester and a monomer having a crosslinkable functional group in the molecule, and a part of the crosslinkable functional group of the copolymer. , A (meth) acryloyl group and a compound having a group that reacts with a crosslinkable functional group can be reacted.

  The weight average molecular weight of the adduct acrylate polymer is preferably 50,000 or more as a lower limit, and particularly preferably 100,000 or more. The weight average molecular weight is preferably 900,000 or less as an upper limit, and particularly preferably 500,000 or less.

  The active energy ray-curable compound (D) can be used by selecting one from among the above-mentioned polyfunctional acrylate monomers, acrylate oligomers and adduct acrylate polymers, or a combination of two or more. It can also be used in combination with other active energy ray-curable components.

  The content of the active energy ray-curable compound (D) in the pressure-sensitive adhesive composition Q is from the viewpoint of improving the cohesive strength of the resulting pressure-sensitive adhesive and improving the blister resistance. It is preferable that it is 0.5 mass part or more as a lower limit with respect to 100 mass parts of unification | combination (C), It is more preferable that it is 1.0 mass part or more, It is especially 3.0 mass part or more. preferable. On the other hand, the content is 50 parts by mass or less as an upper limit from the viewpoint of preventing the active energy ray-curable compound (D) from phase-separating with the (meth) acrylic acid ester polymer (C). Preferably, it is more preferably 20 parts by mass or less, and more preferably 12 parts by mass or less considering the viewpoint of further improving the blister resistance.

(3) Crosslinking agent (B)
It is preferable that the adhesive composition Q contains a crosslinking agent (B). The pressure-sensitive adhesive composition Q contains the crosslinking agent (B), thereby cross-linking the (meth) acrylic acid ester polymer (C) to form a three-dimensional network structure. It is possible to improve the blister resistance and the step following ability under high temperature and high humidity conditions. As a crosslinking agent (B), the thing similar to what was demonstrated in the adhesive composition P can be used, and the usage-amount is also the same.

(4) Photopolymerization initiator (E)
When the active energy ray-curable pressure-sensitive adhesive constituting the third pressure-sensitive adhesive layer 23 is cured, when ultraviolet rays are used as the active energy ray to be irradiated, the pressure-sensitive adhesive composition Q further contains a photopolymerization initiator (E ) Is preferably contained. By containing the photopolymerization initiator (E) as described above, the active energy ray-curable compound (D) can be efficiently polymerized, and the polymerization curing time and the active energy ray irradiation amount can be reduced. it can.

  Examples of such photopolymerization initiator (E) include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, and 2,2-dimethoxy. 2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (Methylthio) phenyl] -2-morpholino-propan-1-one, 4- (2-hydroxyethoxy) phenyl-2- (hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4 -Diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone 2,4-diethylthioxanthone, benzyldimethyl ketal, acetophenone dimethyl ketal, p-dimethylaminobenzoate, oligo [2-hydroxy-2-methyl-1 [4- (1-methylvinyl) phenyl] propanone], 2 4,6-trimethylbenzoyl-diphenyl-phosphine oxide and the like. These may be used alone or in combination of two or more.

  The content of the photopolymerization initiator (E) in the adhesive composition Q is preferably 0.1 parts by mass or more as a lower limit with respect to 100 parts by mass of the active energy ray-curable compound (D). In particular, the amount is preferably 1 part by mass or more. Moreover, it is preferable that it is 30 mass parts or less as an upper limit, and it is preferable that it is especially 10 mass parts or less.

(5) Various additives For the adhesive composition Q, various additives usually used in acrylic pressure-sensitive adhesives, for example, silane coupling agents, antistatic agents, tackifiers, antioxidants, ultraviolet rays, if desired. Absorbers, light stabilizers, softeners, fillers, refractive index adjusters and the like can be added.

  The pressure-sensitive adhesive composition Q represents a mixture of various components remaining in the pressure-sensitive adhesive layer as it is or in a reacted state, and is a component removed in a drying step or the like, for example, polymerization described later. A solvent or a diluting solvent is not included in the adhesive composition Q.

(6) Manufacture of adhesive composition The adhesive composition Q manufactured the (meth) acrylic acid ester polymer (C), the obtained (meth) acrylic acid ester polymer (C), and an active energy ray. While mixing with a sclerosing | hardenable compound (D), it can manufacture by adding a crosslinking agent (B), a photoinitiator (E), and an additive depending on necessity. Specifically, it can be produced by the same method as the adhesive composition P.

(7) Production of pressure-sensitive adhesive The active energy ray-curable pressure-sensitive adhesive constituting the third pressure-sensitive adhesive layer 23 can be preferably obtained by crosslinking (thermal crosslinking) the pressure-sensitive adhesive composition Q. The pressure-sensitive adhesive composition Q can be crosslinked by the same method as that for the pressure-sensitive adhesive composition P.

(8) Gel fraction The gel fraction before curing of the active energy ray-curable pressure-sensitive adhesive constituting the third pressure-sensitive adhesive layer 23 is preferably 40% or more, particularly 45% or more as a lower limit. It is preferable that it is 50% or more. When the gel fraction before curing is 40% or more, the cohesive force of the active energy ray-curable pressure-sensitive adhesive becomes high, and the workability of the pressure-sensitive adhesive layer 2 becomes better. The gel fraction before curing is preferably 75% or less as an upper limit, particularly preferably 70% or less, and more preferably 65% or less. When the gel fraction before curing is 75% or less, the active energy ray-curable pressure-sensitive adhesive does not become too hard, and the initial step following property of the pressure-sensitive adhesive layer 2 becomes more excellent.

  The gel fraction after curing of the active energy ray-curable pressure-sensitive adhesive constituting the third pressure-sensitive adhesive layer 23 (after curing by irradiation with active energy rays) is preferably 70% or more, particularly 75%. It is preferable that it is above, and more preferably 79% or more. When the gel fraction after curing is 70% or more, the cohesive force is increased, and the blister resistance and the step following property under high temperature and high humidity are excellent. Further, the gel fraction after curing is preferably 95% or less as an upper limit, particularly preferably 92% or less, and more preferably 90% or less. When the gel fraction after curing is 95% or less, the adhesiveness between the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22 adjacent to each other is excellent. The step following ability is more excellent. Here, the measuring method of the gel fraction of the active energy ray-curable pressure-sensitive adhesive is as shown in the test examples described later.

(9) Adhesive strength The adhesive strength to soda lime glass before curing of the active energy ray-curable adhesive constituting the third adhesive layer 23 (laminate with the base material) is 20 N / 25 mm or more as a lower limit. In particular, it is preferably 25 N / 25 mm or more, and more preferably 30 N / 25 mm or more. When the adhesive force before curing is equal to or higher than the above, the adhesion between the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22 is increased, and delamination in the pressure-sensitive adhesive layer 2 can be suppressed. The upper limit value of the adhesive strength is not particularly limited, but it is usually preferably 50 N / 25 mm or less, and particularly preferably 45 N / 25 mm or less.

  The adhesive strength to soda lime glass after curing (after curing by irradiation with active energy rays) of the active energy ray-curable adhesive (laminate of the base material) constituting the third adhesive layer 23 is the lower limit. It is preferably 20 N / 25 mm or more, particularly preferably 25 N / 25 mm or more, and more preferably 30 N / 25 mm or more. When the adhesive force after curing is higher than the above, the adhesiveness with the first adhesive layer 21 and the second adhesive layer 22 is increased, and the resulting product (display body) has high durability. It becomes. The upper limit value of the adhesive strength is not particularly limited, but usually it is preferably 55 N / 25 mm or less, and particularly preferably 50 N / 25 mm or less.

(10) Step following rate The step following rate (%) after curing of the third pressure-sensitive adhesive layer 23 (after curing by irradiation with active energy rays) is preferably 30% or more, particularly 35% or more as a lower limit. It is preferable that it is 40% or more. In addition, the step following rate (%) is preferably 65% or less as an upper limit, particularly preferably 60% or less, and more preferably 55% or less.

  When the level | step difference follow-up rate of the 3rd adhesive layer 23 as an intermediate | middle layer exists in said range, as the adhesive layer 2 of the adhesive sheet 1 which concerns on this embodiment, it becomes what was excellent by level | step difference followability.

3. Release sheet The release sheets 31 and 32 protect the adhesive layer 2 until the adhesive sheet 1 is used, and are released when the adhesive sheet 1 (adhesive layer 2) is used. In the pressure-sensitive adhesive sheet 1 according to this embodiment, one or both of the release sheets 31 and 32 are not necessarily required.

  Examples of the release sheets 31 and 32 include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate film, and polybutylene. Terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene / (meth) acrylic acid copolymer film, ethylene / (meth) acrylic acid ester copolymer film, polystyrene film, polycarbonate film, polyimide film, fluorine A resin film or the like is used. These crosslinked films are also used. Furthermore, these laminated films may be sufficient.

  It is preferable that the peeling surface (especially the surface in contact with the pressure-sensitive adhesive layer 2) of the release sheets 31 and 32 is subjected to a peeling treatment. Examples of the release agent used for the release treatment include alkyd, silicone, fluorine, unsaturated polyester, polyolefin, and wax release agents. Of the release sheets 31 and 32, one release sheet is preferably a heavy release release sheet having a large release force, and the other release sheet is preferably a light release release sheet having a low release force.

  Although there is no restriction | limiting in particular about the thickness of the peeling sheets 31 and 32, Usually, it is about 20-150 micrometers.

4). Physical property of pressure-sensitive adhesive sheet (1) Step following rate The step following rate (%) after curing of the pressure-sensitive adhesive layer 2 of the pressure-sensitive adhesive sheet 1 according to this embodiment (after curing by irradiation with active energy rays) is 25% or more as a lower limit. In particular, it is preferably 30% or more, and more preferably 40% or more. Further, the step following rate (%) is preferably 60% or less as an upper limit value, particularly preferably 55% or less, and further preferably 50% or less.

  Since the adhesive layer 2 in this embodiment is excellent in level | step difference followability as mentioned above, it can achieve the above high level | step difference follow-up rates. As a result, the pressure-sensitive adhesive layer 2 follows the step of the display member constituting member satisfactorily, and even after the endurance test, the occurrence of bubbles, floats, peeling, etc. is suppressed in the vicinity of the step, thereby reducing the light reflection loss. Occurrence is suppressed.

(2) 100% modulus The 100% modulus before curing of the pressure-sensitive adhesive layer 2 of the pressure-sensitive adhesive sheet 1 according to the present embodiment (before curing by irradiation with active energy rays) is preferably 40 kPa or more as a lower limit, and particularly 50 kPa. It is preferable that it is above, and it is more preferable that it is 60 kPa or more. When the lower limit of the 100% modulus is equal to or higher than the above, the pressure-sensitive adhesive layer 2 has better workability. The 100% modulus before curing of the pressure-sensitive adhesive layer 2 is preferably 200 kPa or less, particularly preferably 150 kPa or less, and more preferably 90 kPa or less as an upper limit. When the upper limit value of the 100% modulus is equal to or less than the above, the pressure-sensitive adhesive layer 2 is more excellent in the initial step following ability.

  The 100% modulus after curing of the pressure-sensitive adhesive layer 2 of the pressure-sensitive adhesive sheet 1 according to the present embodiment (after curing by irradiation with active energy rays) is preferably 70 kPa or more, and particularly preferably 80 kPa or more as a lower limit. Further, it is preferably 125 kPa or more. When the lower limit value of the 100% modulus is equal to or higher than the above, the pressure-sensitive adhesive layer 2 is more excellent in blister resistance and step following ability under high temperature and high humidity. Moreover, the 100% modulus before curing of the pressure-sensitive adhesive layer 2 is preferably 200 kPa or less as an upper limit, particularly preferably 170 kPa or less, and more preferably 150 kPa or less. When the upper limit value of the 100% modulus is equal to or less than the above, it becomes easy to maintain high adhesion (adhesive force) to the adherend (display member) of the pressure-sensitive adhesive layer 2.

5). Manufacture of an adhesive sheet As one manufacture example of the adhesive sheet 1, the coating liquid of the said adhesive composition P is apply | coated to the peeling surface of one peeling sheet 31, and it heat-processes, and heat-crosslinks the adhesive composition P. Then, a coating layer is formed, and the release sheet 31 with the coating layer of the adhesive composition P is obtained. In addition, the adhesive composition P is applied to the release surface of the other release sheet 32, heat-treated to thermally crosslink the adhesive composition P, and a coating layer is formed. A release sheet 32 with a coating layer of the object P is obtained. Furthermore, the coating liquid of the adhesive composition Q is applied to the release surface of another release sheet, heat-treated to thermally crosslink the adhesive composition Q, and an application layer is formed. A release sheet with a Q coating layer is obtained.

  Next, the release sheet 31 with the application layer of the adhesive composition P and the release sheet with the application layer of the adhesive composition Q are bonded together so that the two application layers are in contact with each other. The release sheet is peeled from the coating layer. Subsequently, the coating layer of the adhesive composition Q and the release sheet 32 with the coating layer of the adhesive composition P are bonded together so that both coating layers are in contact with each other. When a curing period is required, a curing period is set, and when the curing period is unnecessary, the application layer of the one adhesive composition P that is laminated is the first adhesive layer 21, the adhesive composition. The coating layer of the product Q is the third pressure-sensitive adhesive layer 23, and the coating layer of the other pressure-sensitive adhesive composition P is the second pressure-sensitive adhesive layer 22. Thereby, the adhesive sheet 1 in which the adhesive layer 2 composed of the first adhesive layer 21, the third adhesive layer 23, and the second adhesive layer 22 is sandwiched between the release sheets 31 and 32 is obtained. . In addition, the curing of the application layer of the adhesive composition may be performed after the application layer of the adhesive composition is bonded into three layers as described above, or may be performed before the bonding.

  For example, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method, or the like can be used as a method for applying the coating solution of the adhesive composition P.

  Since the pressure-sensitive adhesive sheet 1 according to the present embodiment has good workability, when the pressure-sensitive adhesive sheet 1 is punched, the pressure-sensitive adhesive protrudes from the cut surface, and the pressure-sensitive adhesive adheres to the blade. Is suppressed from occurring.

[Display]
As shown in FIG. 2, the display body 4 according to the present embodiment includes a first display body constituent member 51 (one display body constituent member) having a step on at least a surface to be bonded, and a second display body. Display body constituting member 52 (other display body constituting member) and pressure-sensitive adhesive layer 2 which is located between them and bonds first display body constituting member 51 and second display body constituting member 52 to each other. It is prepared for. In the display body 4 according to the present embodiment, the first display body constituting member 51 has a step on the surface on the pressure-sensitive adhesive layer 2 side, specifically, a step due to the printing layer 6. .

  The pressure-sensitive adhesive layer 2 in the display body 4 is obtained by curing the pressure-sensitive adhesive layer 2 (particularly the third pressure-sensitive adhesive layer 23) of the pressure-sensitive adhesive sheet 1 described above by irradiation with active energy rays (for convenience, the same name and Sign). Here, active energy rays refer to those having energy quanta among electromagnetic waves or charged particle beams, and specific examples include ultraviolet rays and electron beams. Among active energy rays, ultraviolet rays that are easy to handle are particularly preferable.

Irradiation with ultraviolet rays can be performed by a high-pressure mercury lamp, a fusion H lamp, a xenon lamp, or the like, and the irradiation amount of ultraviolet rays is preferably about 50 to 1000 mW / cm ^{2 in} illuminance. Further, the light quantity is preferably 50~10000mJ / cm ^2, more preferably 80~5000mJ / cm ^2, and particularly preferably 200~2000mJ / cm ^2. On the other hand, the electron beam irradiation can be performed by an electron beam accelerator or the like, and the electron beam irradiation amount is preferably about 10 to 1000 krad.

  Irradiation of the active energy ray with respect to the adhesive layer 2 is performed by bonding the first display body constituting member 51 and the second display body constituting member 52 to each other by the adhesive layer 2 and then the first display body constituting member 51. Of the second display member constituting member 52, it is preferable to carry out through the member that transmits the active energy ray.

  When the adhesive layer 2 is irradiated with active energy rays, the active energy ray curable compound (D) in the third adhesive layer 23 is polymerized and cured. The pressure-sensitive adhesive layer 2 that is cured by irradiation with active energy rays (particularly, the third pressure-sensitive adhesive layer 23 is cured) has extremely excellent blister resistance and step following capability under high temperature and high humidity.

  Examples of the display body 4 include a liquid crystal (LCD) display, a light emitting diode (LED) display, an organic electroluminescence (organic EL) display, electronic paper, and the like, and may be a touch panel. Moreover, as the display body 4, the member which comprises those some may be sufficient.

  It is preferable that the 1st display body structural member 51 is a protection panel which consists of a laminated body etc. other than a glass plate, a plastic plate, etc. In this case, the printing layer 6 is generally formed in a frame shape on the pressure-sensitive adhesive layer 2 side in the first display member constituting member 51.

  The glass plate is not particularly limited. For example, chemically tempered glass, alkali-free glass, quartz glass, soda lime glass, barium / strontium-containing glass, aluminosilicate glass, lead glass, borosilicate glass, barium borosilicate Glass etc. are mentioned. Although the thickness of a glass plate is not specifically limited, Usually, it is 0.1-5 mm, Preferably it is 0.2-2 mm.

  The plastic plate is not particularly limited, and examples thereof include an acrylic plate and a polycarbonate plate. Although the thickness of a plastic board is not specifically limited, Usually, it is 0.2-5 mm, Preferably it is 0.4-3 mm.

  Various functional layers (transparent conductive film, metal layer, silica layer, hard coat layer, antiglare layer, etc.) may be provided on one or both surfaces of the glass plate or plastic plate, or an optical member. May be laminated. Moreover, the transparent conductive film and the metal layer may be patterned.

  The second display member constituting member 52 includes an optical member to be attached to the first display member constituting member 51, a display member module (for example, a liquid crystal (LCD) module, a light emitting diode (LED) module, an organic electroluminescence (organic) EL) module, etc.), an optical member as a part of the display module, or a laminate including the display module.

  Examples of the optical member include a scattering prevention film, a polarizing plate (polarizing film), a polarizer, a retardation plate (retarding film), a viewing angle compensation film, a brightness enhancement film, a contrast enhancement film, a liquid crystal polymer film, and a diffusion film. , Transflective film, transparent conductive film, and the like. Examples of the scattering prevention film include a hard coat film in which a hard coat layer is formed on one side of a base film.

  The material which comprises the printing layer 6 is not specifically limited, The well-known material for printing is used. The lower limit value of the thickness of the printing layer 6, that is, the height of the step, is preferably 3 μm or more, more preferably 5 μm or more, particularly preferably 7 μm or more, and most preferably 10 μm or more. preferable. When the lower limit value is equal to or greater than the above, it is possible to sufficiently ensure concealability such as making the electrical wiring invisible from the viewer side. The upper limit value is preferably 50 μm or less, more preferably 35 μm or less, particularly preferably 25 μm or less, and further preferably 20 μm or less. When the upper limit is less than or equal to the above, it is possible to prevent the step following ability of the pressure-sensitive adhesive layer 2 from deteriorating with respect to the print layer 6.

  In order to manufacture the display body 4, as an example, one release sheet 31 of the pressure-sensitive adhesive sheet 1 is peeled off, and the pressure-sensitive adhesive layer 2 exposed from the pressure-sensitive adhesive sheet 1 is replaced with a print layer of the first display body constituting member 51. It is bonded to the surface on the side where 6 is present. At this time, since the pressure-sensitive adhesive layer 2 is excellent in level difference followability, the occurrence of gaps and floating near the level difference due to the printing layer 6 is suppressed.

  Then, the other peeling sheet 32 is peeled from the pressure-sensitive adhesive layer 2 of the pressure-sensitive adhesive sheet 1, and the pressure-sensitive adhesive layer 2 exposed from the pressure-sensitive adhesive sheet 1 and the second display member constituting member 52 are bonded together. As another example, the bonding order of the first display member constituting member 51 and the second display member constituting member 52 may be switched.

  In the display body 4 described above, since the pressure-sensitive adhesive layer 2 is excellent in blister resistance, the display body 4 is placed under a high temperature and high humidity condition (for example, 85 ° C., 85% RH, 72 hours). Even when outgas is generated from the display member constituting member, occurrence of blisters such as bubbles, floating and peeling at the interface between the pressure-sensitive adhesive layer 2 and the display member constituting members 51 and 52 is suppressed.

  Moreover, in the said display body 4, since the adhesive layer 2 is excellent in level | step difference followability also on high temperature / humidity conditions, the display body 4 is on high temperature / humidity conditions (for example, 85 degreeC, 85% RH, 72 hours). Even when placed, the occurrence of bubbles, floating, peeling, etc. near the step is suppressed.

  The embodiment described above is described for facilitating understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

  For example, either or both of the release sheets 31 and 32 in the pressure-sensitive adhesive sheet 1 may be omitted, and a desired optical member may be laminated instead of the release sheets 31 and / or 32. Furthermore, another layer may exist between the first pressure-sensitive adhesive layer 21 and / or the second pressure-sensitive adhesive layer 22 and the third pressure-sensitive adhesive layer 23 in the pressure-sensitive adhesive layer 2, or pressure-sensitive adhesive. Another layer may exist on the outer side (release sheet 31, 32 side) of the first pressure-sensitive adhesive layer 21 and / or the second pressure-sensitive adhesive layer 22 in the agent layer 2.

  Further, the first display member constituting member 51 may have a step other than the printed layer 6. Furthermore, not only the 1st display body structural member 51 but the 2nd display body structural member 52 may also have a level | step difference in the adhesive layer 2 side.

  EXAMPLES Hereinafter, although an Example etc. demonstrate this invention further more concretely, the scope of the present invention is not limited to these Examples etc.

[Production Example 1]
-Production of a laminate having a first pressure-sensitive adhesive layer or a second pressure-sensitive adhesive layer-
(1) Preparation of (meth) acrylic acid ester polymer (A) 60 parts by mass of 2-ethylhexyl acrylate, 20 parts by mass of methyl methacrylate and 20 parts by mass of 2-hydroxyethyl acrylate were copolymerized to give (meth) Acrylic ester polymer (A) was prepared. When the molecular weight of this (meth) acrylic acid ester polymer (A) was measured by the method described later, it was a weight average molecular weight (Mw) of 600,000.

(2) Preparation of adhesive composition P As a cross-linking agent (B), 100 parts by mass of the (meth) acrylic acid ester polymer (A) obtained in the above step (1) (solid content conversion value; the same shall apply hereinafter). 0.25 parts by mass of trimethylolpropane-modified tolylene diisocyanate (manufactured by Nippon Polyurethane Co., Ltd., product name “Coronate L”) and 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent Product name “KBM-403”) 0.30 part by mass was mixed, sufficiently stirred, and diluted with methyl ethyl ketone to obtain a coating solution of adhesive composition P having a solid content concentration of 35% by mass.

Here, Table 1 shows each formulation (solid content converted value) of the adhesive composition when the (meth) acrylic acid ester polymer is 100 parts by mass (solid content converted value). Details of the abbreviations and the like described in Table 1 are as follows.
[(Meth) acrylic acid ester polymer]
2EHA: 2-ethylhexyl acrylate MMA: methyl methacrylate HEA: 2-hydroxyethyl acrylate BA: n-butyl acrylate IBXMA: isobornyl methacrylate IBXA: isobornyl acrylate ACMO: 4-acryloylmorpholine AA: acrylic acid
[Crosslinking agent]
TDI system: trimethylolpropane-modified tolylene diisocyanate (manufactured by Nippon Polyurethane Co., Ltd., product name “Coronate L”)
Epoxy system: 1,3-bis (N, N′-diglycidylaminomethyl) cyclohexane (manufactured by Mitsubishi Gas Chemical Company, product name “TETRAD C-5”)

(3) Production of Laminate Heavy Release Type Release Sheet (manufactured by Lintec Corporation), which was obtained by subjecting one side of a polyethylene terephthalate film to a release treatment with a silicone-based release agent from the adhesive composition P obtained in the above step (2). After coating with a knife coater on the peel-treated surface of the product name “SP-PET752150”), the coated layer (thickness: 25 μm) was formed by heat treatment at 90 ° C. for 1 minute. Similarly, the light release release sheet (product name “SP-PET 382120”, manufactured by Lintec Co., Ltd.) obtained by removing one surface of the polyethylene terephthalate film with a silicone-based release agent from the coating solution of the adhesive composition obtained in Step 2 above. ) Was applied with a knife coater, followed by heat treatment at 90 ° C. for 1 minute to form a coating layer (thickness: 25 μm).

  Subsequently, the heavy release type release sheet with the coating layer obtained above and the light release type release sheet with the coating layer obtained above were bonded so that both coating layers were in contact with each other. Then, by curing for 7 days under the condition of 50% RH, a laminate having a structure of heavy release type release sheet / adhesive layer (thickness: 50 μm) / light release type release sheet was produced. In addition, this adhesive layer is comprised from an active energy ray non-curable adhesive, and corresponds to the 1st adhesive layer and the 2nd adhesive layer.

  The thickness of the pressure-sensitive adhesive layer is a value measured using a constant pressure thickness measuring instrument (manufactured by Teclock, product name “PG-02”) in accordance with JIS K7130.

[Production Examples 2-3]
Production examples other than changing the type and ratio of each monomer constituting the (meth) acrylate polymer (A) and the weight average molecular weight of the (meth) acrylate polymer (A) as shown in Table 1. A laminate was produced in the same manner as in Example 1.

[Production Example 4]
-Production of a laminate having a third pressure-sensitive adhesive layer-
(1) Preparation of (meth) acrylic acid ester polymer (C) 60 parts by mass of 2-ethylhexyl acrylate, 10 parts by mass of isobornyl acrylate, 10 parts by mass of 4-acryloylmorpholine and 20 parts by mass of 2-hydroxyethyl acrylate By polymerization, a (meth) acrylic acid ester polymer (C) was prepared. When the molecular weight of this (meth) acrylic acid ester polymer (C) was measured by the method described later, the weight average molecular weight (Mw) was 500,000.

(2) Preparation of adhesive composition Q 100 parts by mass of the (meth) acrylic acid ester polymer (C) obtained in the above step (1) and ε-caprolactone modification as an active energy ray-curable compound (D) Tris- (2-acryloxyethyl) isocyanurate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name “NK Ester A-9300-1CL”), benzophenone and 1- 0.50 part by mass of hydroxycyclohexyl phenyl ketone mixed at a mass ratio of 1: 1 (manufactured by BASF, product name “Irgacure 500”) and trimethylolpropane-modified tolylene diisocyanate as a crosslinking agent (B) (Japan) 0.25 parts by mass of polyurethane (product name “Coronate L”) and 3-glycidoxypropyl as a silane coupling agent Mixing with 0.30 parts by mass of Limethoxysilane (Shin-Etsu Chemical Co., Ltd., product name “KBM-403”), thoroughly stirring, and diluting with methyl ethyl ketone, the solid content concentration is 48% by mass. A coating solution of composition Q was obtained.

(3) Production of Laminate Using the coating solution of the adhesive composition Q obtained in the above step (2), in the same manner as the adhesive composition P described above, a heavy release type release sheet / adhesive layer ( (Thickness: 50 μm) / A laminate having a structure of a light release type release sheet was produced. This pressure-sensitive adhesive layer is composed of an active energy ray-curable pressure-sensitive adhesive and corresponds to the third pressure-sensitive adhesive layer.

[Production Example 5]
Kind and ratio of each monomer constituting (meth) acrylate polymer (A), weight average molecular weight of (meth) acrylate polymer (A), ratio of active energy ray curable compound (D), light A laminate was produced in the same manner as in Production Example 4 except that the ratio of the polymerization initiator (E) and the type and ratio of the crosslinking agent (B) were changed as shown in Table 1.

Here, the above-mentioned weight average molecular weight (Mw) is a polystyrene-reduced weight average molecular weight measured under the following conditions (GPC measurement) using gel permeation chromatography (GPC).
<Measurement conditions>
GPC measurement device: manufactured by Tosoh Corporation, HLC-8020
GPC column (passed in the following order): TSK guard column HXL-H manufactured by Tosoh Corporation
TSK gel GMHXL (× 2)
TSK gel G2000HXL
・ Measurement solvent: Tetrahydrofuran ・ Measurement temperature: 40 ° C.

[Example 1]
While peeling a light peelable release sheet from the laminate obtained in Production Example 1, the light peelable release sheet was peeled from the laminate obtained in Production Example 4, and the exposed first adhesive layer and third The pressure-sensitive adhesive layers were bonded together so that they were in contact with each other, and the heavy release release sheet was peeled from the third pressure-sensitive adhesive layer. Next, the light release type release sheet is peeled from the laminate obtained in Production Example 1, and the second adhesive layer exposed and the third adhesive layer are bonded together so that they are in contact with each other. A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer, a third pressure-sensitive adhesive layer, and a second pressure-sensitive adhesive layer was sandwiched between two heavy release release sheets.

[Examples 2-6, Comparative Examples 1-7]
The pressure-sensitive adhesive layers of the laminates produced in Production Examples 1 to 5 were laminated so as to have the lamination order shown in Table 2, and pressure-sensitive adhesive sheets were produced in the same manner as in Example 1. At this time, the thickness of each pressure-sensitive adhesive layer was changed to the thickness shown in Table 2.

[Test Example 1] (Measurement of gel fraction)
The laminates produced in Production Examples 1 to 5 were cut into a size of 80 mm × 80 mm, the pressure-sensitive adhesive layer was wrapped in a polyester mesh (mesh size 200), the mass was weighed with a precision balance, and the mesh alone The mass of only the adhesive was calculated by subtracting the mass of. The mass at this time is M1.

  Next, the pressure-sensitive adhesive wrapped in the polyester mesh was immersed in ethyl acetate at room temperature (23 ° C.) for 24 hours. Thereafter, the pressure-sensitive adhesive was taken out, air-dried for 24 hours in an environment of a temperature of 23 ° C. and a relative humidity of 50%, and further dried in an oven at 80 ° C. for 12 hours. After drying, the mass was weighed with a precision balance, and the mass of the pressure sensitive adhesive alone was calculated by subtracting the mass of the mesh alone. The mass at this time is M2. The gel fraction (%) is represented by (M2 / M1) × 100. The results are shown in Table 3.

In addition, about the adhesive layer of the laminated body of manufacture example 4 and 5, the gel fraction before and behind irradiating an ultraviolet-ray with respect to an adhesive layer (irradiation from the heavy peeling type peeling sheet side) was measured. In the table, the result before UV irradiation is described as “before UV”, and the result after UV irradiation is described as “after UV” (hereinafter the same). The irradiation conditions of ultraviolet rays are as follows.
<Ultraviolet irradiation conditions>
-Fusion company electrodeless lamp H bulb use-Illuminance 500mW / cm ² , Light quantity 200mJ / cm ²
・ Use UV-illumination meter "UVPF-36" manufactured by iGraphics.

[Test Example 2] (Measurement of adhesive strength)
The peelable release sheet was peeled from the laminates produced in Production Examples 1 to 5, and the exposed pressure-sensitive adhesive layer was replaced with a polyethylene terephthalate (PET) film having an easy-adhesion layer (product name “PET A4300”, manufactured by Toyobo Co., Ltd.). The laminate was bonded to an easy-adhesion layer having a thickness of 100 μm to obtain a laminate of release sheet / adhesive layer / PET film. The obtained laminate was cut into a width of 25 mm and a length of 100 mm, and this was used as a sample.

  In an environment of 23 ° C. and 50% RH, the heavy release type release sheet was peeled from the above sample, and the exposed adhesive layer was attached to soda lime glass (manufactured by Nippon Sheet Glass Co., Ltd.), and then placed in an autoclave manufactured by Kurihara Seisakusho. And pressurized at 0.5 MPa and 50 ° C. for 20 minutes. Then, after being allowed to stand for 24 hours under the conditions of 23 ° C. and 50% RH, using a tensile tester (Orientec, Tensilon), the adhesive strength (N / 25 mm). Conditions other than those described here were measured according to JIS Z 0237: 2009. The results are shown in Table 3.

  In addition, about the laminated body of manufacture example 4 and 5, after sticking to soda-lime glass similarly to the above and performing pressurization with an autoclave, an ultraviolet-ray is irradiated with respect to an adhesive layer through soda-lime glass, and then In the same manner as described above, the adhesive strength after standing for 24 hours was also measured. The ultraviolet irradiation conditions are the same as in Test Example 1.

[Test Example 3] (Measurement of storage elastic modulus (G ′))
A plurality of the pressure-sensitive adhesive layers of the laminates produced in Production Examples 1 to 5 were laminated to obtain a laminate having a thickness of 3 mm. A cylindrical body (height 3 mm) having a diameter of 8 mm was punched out from the obtained laminate of the pressure-sensitive adhesive layer, and this was used as a sample.

About the said sample, based on JISK7244-6, the storage elastic modulus (G ') (MPa) was measured on condition of the following by the torsional shearing method using the viscoelasticity measuring device (the product made by REOMETRIC, DYNAMIC ANALAYZER). The results are shown in Table 3.
Measurement frequency: 1Hz
Measurement temperature: 23 ° C

  In addition, about the adhesive layer of the laminated body of manufacture example 4 and 5, the storage elastic modulus (G ') before and behind irradiating an ultraviolet-ray with respect to the laminated body of an adhesive layer was measured. The ultraviolet irradiation conditions are the same as in Test Example 1.

[Test Example 4] (Measurement of 100% modulus)
After laminating a plurality of the pressure-sensitive adhesive layers of the laminates produced in Production Examples 1 to 5 to a total thickness of 800 μm, a 10 mm wide × 75 mm long sample was cut out. The sample is set on a tensile tester (Orientec, product name “Tensilon”) so that the sample measurement site is 10 mm wide × 25 mm long (extension direction), and the measurement is performed in an environment of 23 ° C. and 50% RH. The sample was stretched at a tensile rate of 200 mm / min using a tensile tester, and the stress value at which the elongation was 100% was calculated (measured) as a 100% modulus (kPa) on a stress-strain curve (SS curve). The results are shown in Table 3.

  In addition, about the adhesive layer of the laminated body of manufacture example 4 and 5, 100% modulus (kPa) before and behind irradiating an ultraviolet-ray with respect to the laminated body of an adhesive layer was measured. The ultraviolet irradiation conditions are the same as in Test Example 1.

  Moreover, also about the adhesive layer of the adhesive sheet obtained in Examples 1-6 and Comparative Examples 6-7, 100% modulus (kPa) was measured by the method similar to the above (for Comparative Examples 1-5, Since the result is the same as in Production Examples 1 to 5, the test is omitted. However, in Examples and Comparative Examples other than Example 2, a plurality of pressure-sensitive adhesive layers (three-layer structure) were laminated to a total thickness of 750 μm. The results are shown in Table 4. In addition, about the adhesive layer of the adhesive sheet obtained in Examples 1-6 and Comparative Example 6, 100% modulus (kPa) before and behind irradiating an ultraviolet-ray with respect to an adhesive layer was measured. The ultraviolet irradiation conditions are the same as in Test Example 1.

[Test Example 5] (Evaluation of blister resistance)
Transparent adhesive made of tin-doped indium oxide (ITO) on one side of the pressure-sensitive adhesive layer of the laminates produced in Production Examples 1 to 5 and the pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets obtained in Examples 1 to 6 and Comparative Examples 1 to 7 Transparent conductive film of polyethylene terephthalate film (Oike Kogyo Co., Ltd., ITO film, thickness: 125 μm) provided with a film and polycarbonate (PC) plate (Mitsubishi Gas Chemical Co., Ltd., Iupilon sheet MR58, thickness: 1 mm) ) Or an acrylic plate made of polymethyl methacrylate (PMMA) (Mitsubishi Gas Chemical Co., Ltd., Iupilon sheet MR200, thickness: 1 mm) to obtain a laminate.

  The obtained laminate was autoclaved for 30 minutes at 50 ° C. and 0.5 MPa. Then, the pressure-sensitive adhesive layer was irradiated with ultraviolet rays through the PC plate or the acrylic plate under the same ultraviolet irradiation conditions as in Test Example 1 to cure the pressure-sensitive adhesive layer (the pressure-sensitive adhesive layer of Production Examples 1 to 3, comparison) Except for the pressure-sensitive adhesive layers of Examples 1 to 3 and 7.)

The sample obtained as described above was allowed to stand at normal pressure, 23 ° C., 50% RH for 15 hours. Subsequently, it was stored for 72 hours under 85 ° C. and 85% RH durability conditions. Thereafter, it was visually confirmed whether or not the pressure-sensitive adhesive layer had bubbles, floating or peeling, and blister resistance was evaluated according to the following criteria. The results are shown in Tables 3 and 4.
A: There were no bubbles, no floating, and no peeling.
○: Only bubbles with a diameter of 0.1 mm or less were generated.
X: Bubbles with a diameter of more than 0.1 mm, floating or peeling occurred.

[Test Example 6] (Measurement of step following rate)
On the surface of a glass plate (manufactured by NSG Precision, product name “Corning Glass Eagle XG”, length 90 mm × width 50 mm × thickness 0.5 mm), UV curable ink (product name “POS-911 Black”, manufactured by Teikoku Ink Co., Ltd.) ) With a coating thickness of 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, and 60 μm (outer shape: vertical 90 mm × width 50 mm, width 5 mm) Screen printed. Next, irradiation with ultraviolet rays (80 W / cm ² , ^two metal halide lamps, lamp height of 15 cm, belt speed of 10 to 15 m / min) is performed to cure the printed ultraviolet curable ink, and a level difference due to printing (level difference) A stepped glass plate having a thickness of any one of 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, and 60 μm) was produced.

  One release sheet was peeled off from the laminates produced in Production Examples 1 to 5 and the pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples, and the exposed pressure-sensitive adhesive layer was converted into a polyethylene terephthalate film (manufactured by Toyobo Co., Ltd., It was bonded to an easy adhesion layer having a product name “PET A4300” (thickness: 100 μm). Next, the other release sheet was peeled off to expose the pressure-sensitive adhesive layer. And using the laminator (The product name "LPD3214" by the Fuji plastic company), the said laminated body was laminated on each glass plate with a level | step difference so that an adhesive layer might cover the frame-like printing whole surface. Thereafter, autoclaving was performed for 30 minutes at 50 ° C. and 0.5 MPa.

  The pressure-sensitive adhesive layer was irradiated with ultraviolet rays through the PET film under the same ultraviolet irradiation conditions as in Test Example 1 to cure the pressure-sensitive adhesive layer (the pressure-sensitive adhesive layers of Production Examples 1 to 3, Comparative Examples 1 to 3). 3 and 7 adhesive layers are excluded).

The sample for evaluation obtained as described above was stored for 72 hours under a high-temperature and high-humidity condition of 85 ° C. and 85% RH (endurance test), and then the step following ability was evaluated. Step followability is determined by whether or not the printing step is completely filled with the adhesive layer.If air bubbles, floating, peeling, etc. are observed at the interface between the printing step and the adhesive layer, It is judged that it was not able to follow. Here, the step following property was evaluated as a step following rate (%) represented by the following formula. The results are shown in Tables 3 and 4.
Step follow-up rate (%) = {(height of the step in which the embedded state is maintained without bubbles, floats, peeling, etc. after the durability test (μm)) / (thickness of the adhesive layer)} × 100

[Test Example 7] (Evaluation of workability)
The pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples were cut with an automatic cutting machine (manufactured by Hadano Seisakusho, product name “Super Cutter OSS-PN1 type NL”). The cut surface (length: 100 mm) of the pressure-sensitive adhesive sheet after cutting was visually confirmed, and workability was evaluated according to the following criteria. The results are shown in Table 4.
○: No sticking of the adhesive layer ×: Sticking of the adhesive layer

  As can be seen from Table 4, the pressure-sensitive adhesive sheets obtained in the examples were excellent in both step followability and blister resistance, and had good workability.

  The pressure-sensitive adhesive sheet of the present invention can be suitably used, for example, for bonding between a protective panel having a step and a desired display member constituting member.

DESCRIPTION OF SYMBOLS 1 ... Adhesive sheet 2 ... Adhesive layer 21 ... 1st adhesive layer 22 ... 2nd adhesive layer 23 ... 3rd adhesive layer 31, 32 ... Release sheet 4 ... Display body 51 ... 1st display body Constituent member 52 ... second display member constituent member 6 ... printing layer

Claims (8)

An adhesive sheet having an adhesive layer,
The pressure-sensitive adhesive layer is
A first pressure-sensitive adhesive layer as an outer layer on one side;
A second pressure-sensitive adhesive layer as an outer layer on the other surface side;
A third pressure-sensitive adhesive layer positioned as an intermediate layer between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer,
The storage elastic modulus (G ′) at 23 ° C. of the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer and the pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer is 0.1 MPa or more, respectively.
The third pressure-sensitive adhesive layer is composed of an active energy ray-curable pressure-sensitive adhesive,
The storage elastic modulus (G ′) at 23 ° C. before curing of the active energy ray-curable pressure-sensitive adhesive is the storage elastic modulus (G ′) at 23 ° C. of the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer. A pressure-sensitive adhesive sheet characterized by being lower than the storage elastic modulus (G ′) at 23 ° C. of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer. An adhesive sheet having an adhesive layer,
The pressure-sensitive adhesive layer is
A first pressure-sensitive adhesive layer as an outer layer on one side;
A second pressure-sensitive adhesive layer as an outer layer on the other surface side;
A third pressure-sensitive adhesive layer positioned as an intermediate layer between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer,
The 100% modulus of the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer and the pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer are each 60 kPa or more,
The third pressure-sensitive adhesive layer is composed of an active energy ray-curable pressure-sensitive adhesive,
The 100% modulus before curing of the active energy ray-curable adhesive is 100% modulus of the adhesive constituting the first adhesive layer and the 100% modulus of the adhesive constituting the second adhesive layer. Is a low pressure-sensitive adhesive sheet.   The pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer and the pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer are non-active energy ray-curable pressure-sensitive adhesives, according to claim 1 or 2. Adhesive sheet.   The ratio of the thickness of the third pressure-sensitive adhesive layer to the total thickness of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer is 0.3 or more and 5 or less. The adhesive sheet as described in any one of 1-3.   The total thickness of the said adhesive layer is 50 micrometers or more and 300 micrometers or less, The adhesive sheet as described in any one of Claims 1-4 characterized by the above-mentioned.   It is used for bonding one display body constituent member which has a level | step difference to the surface of the side bonded at least, and another display body structural member, The any one of Claims 1-5 characterized by the above-mentioned. The pressure-sensitive adhesive sheet described in 1. The pressure-sensitive adhesive sheet includes two release sheets,
The pressure-sensitive adhesive sheet according to any one of claims 1 to 6, wherein the pressure-sensitive adhesive layer is sandwiched between the release sheets so as to be in contact with release surfaces of the two release sheets. At least one display member constituting member having a step on the surface to be bonded;
Other display body components,
A display body comprising an adhesive layer that bonds the one display body constituent member and the other display body constituent member together,
The said adhesive layer is an adhesive layer formed by hardening | curing the adhesive layer of the adhesive sheet as described in any one of Claims 1-7, The display body characterized by the above-mentioned.

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