WO2019239925A1 - Adhesive sheet - Google Patents

Abstract

This adhesive sheet (10) is used when sealing a semiconductor element on an adhesive sheet and is provided with a substrate (11) and an adhesive agent layer (12) that contains an antistatic agent. The surface resistivity of the adhesive agent layer (12) is less than 10¹¹ Ω/□ after the adhesive sheet (10) is heated at 190°C for 60 minutes under a nitrogen atmosphere and then set aside for 24 hours at 23°C and 50% RH.

Description

Adhesive sheet

The present invention relates to an adhesive sheet.

In the manufacturing process of a semiconductor device, an adhesive sheet is used for the purpose of fixing a semiconductor wafer and protecting a semiconductor element (for example, a semiconductor chip).
The pressure-sensitive adhesive sheet is peeled off when a predetermined processing step is completed. At this time, static electricity called peeling charging may occur between the pressure-sensitive adhesive sheet and the semiconductor wafer or between the pressure-sensitive adhesive sheet and the semiconductor element. is there. Since such static electricity causes damage to the semiconductor wafer, the semiconductor element, and the circuits formed thereon, a method for preventing this damage (hereinafter also referred to as “electrostatic breakdown”) has been studied. ing.

For example, Patent Document 1 discloses a monomer mixture in which the pressure-sensitive adhesive layer contains (a) a specific (meth) acrylic acid alkyl ester as a main component and a monoethylenically unsaturated acid copolymerizable therewith. , (B) a polyfunctional (meth) acrylate as a cross-linking agent, (c) a photopolymerization initiator, and (d) a photopolymerization product of a photopolymerizable composition each containing a specific amount of an epoxy resin. An electronic component reinforcing adhesive sheet is disclosed. Patent Document 1 discloses that the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet for reinforcing electronic parts may contain an antistatic agent.
Patent Document 2 discloses (a) an ionic liquid, (b) a (meth) acrylic polymer containing as a main component at least one (meth) acrylate having an alkyl group having 4 to 12 carbon atoms, and ( c) A pressure-sensitive adhesive composition comprising a specific compound containing two or more hydroxyl groups in the molecule, wherein the (meth) acrylic polymer has a weight average molecular weight of 300,000 to 1.3 million. Is disclosed.
Moreover, the adhesive sheet formed by forming the adhesive layer formed by bridge | crosslinking this adhesive composition on the single side | surface or both surfaces of a support body is disclosed.

JP 2003-105278 A JP 2011-127130 A

However, in the manufacturing process of the semiconductor device, when the step of sealing the semiconductor element with the sealing material is performed, the pressure-sensitive adhesive sheet may be heated at a high temperature (for example, 150 ° C. or more and 190 ° C. or less). When the pressure-sensitive adhesive sheet is peeled off from the adherend after such a heating step, electronic components (for example, electronic circuits) are more easily destroyed by static electricity generated by peeling charging, and as a result, the semiconductor element is destroyed. Sometimes.
In Patent Documents 1 and 2 described above, it is disclosed that an antistatic agent may be included in the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet. Material selection is required. In particular, in the manufacturing process of the semiconductor device that performs the sealing process, it is necessary to select a material that also takes into account the characteristics after the pressure-sensitive adhesive sheet is heated at a high temperature.

The object of the present invention is to use a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer having a surface resistivity of less than a predetermined value after passing through a process of heating at a high temperature (for example, 150 ° C. or higher and 190 ° C. or lower). It is to provide an adhesive sheet that can suppress electrostatic breakdown of a semiconductor element even if it is peeled off from an adherend.

The pressure-sensitive adhesive sheet according to one embodiment of the present invention is a pressure-sensitive adhesive sheet used when sealing a semiconductor element on a pressure-sensitive adhesive sheet, and includes a base material and a pressure-sensitive adhesive layer containing an antistatic agent, and nitrogen. The surface resistivity of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet after heating in an atmosphere at 190 ° C. for 60 minutes and then standing at 23 ° C. and 50% RH for 24 hours is less than 10 ¹¹ Ω / □.

In the pressure-sensitive adhesive sheet according to one embodiment of the present invention, the band of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet after being heated in a nitrogen atmosphere at 190 ° C. for 60 minutes and then allowed to stand in an atmosphere at 23 ° C. and 50% RH for 24 hours. The voltage is preferably less than 0.1 kV.

In the pressure-sensitive adhesive sheet according to one aspect of the present invention, the antistatic agent preferably contains at least one selected from the group consisting of a carbon material and an ionic material.

In the pressure-sensitive adhesive sheet according to one aspect of the present invention, the carbon material is preferably at least one selected from the group consisting of carbon nanotubes, graphene, and carbon black.

In the pressure-sensitive adhesive sheet according to one aspect of the present invention, the ionic material is preferably at least one selected from the group consisting of an ionic liquid and an ionic polymer.

In the pressure-sensitive adhesive sheet according to one aspect of the present invention, it is preferable that the antistatic agent is the ionic liquid or a mixture of the ionic liquid and the carbon material.

In the pressure-sensitive adhesive sheet according to one aspect of the present invention, the ionic liquid preferably contains a cation and an anion represented by the following general formula (1).

In the general formula (1), R ¹ and R ² are each independently a fluorine atom or a perfluoroalkyl group having 1 to 8 carbon atoms, and R ¹ and R ² are the same or different.

In the pressure-sensitive adhesive sheet according to one aspect of the present invention, the content of the ionic liquid is preferably 0.01% by mass or more and 10% by mass or less with respect to the entire pressure-sensitive adhesive layer.

In the pressure-sensitive adhesive sheet according to one embodiment of the present invention, the pressure-sensitive adhesive layer contains an acrylic pressure-sensitive adhesive composition, and the acrylic pressure-sensitive adhesive composition has an alkyl group having 4 to 12 carbon atoms (meth). It is preferable to include an acrylic copolymer having an alkyl acrylate as a main monomer.

In the pressure-sensitive adhesive sheet according to one aspect of the present invention, the pressure-sensitive adhesive sheet is heated under conditions of 100 ° C. and 30 minutes, subsequently heated under conditions of 180 ° C. and 30 minutes, and further heated under conditions of 190 ° C. and 60 minutes. Then, the pressure-sensitive adhesive strength of the pressure-sensitive adhesive layer after being allowed to stand for 24 hours at 23 ° C. and 50% RH is 0.5 N / 25 mm or more and 3.0 N / 25 mm or less, and the pressure-sensitive adhesive The adhesive strength of the layer to the polyimide film is preferably 0.50 N / 25 mm or more and 2.00 N / 25 mm or less.

In the pressure-sensitive adhesive sheet according to one embodiment of the present invention, it is preferable that the surface of the substrate on the side of the pressure-sensitive adhesive layer has conductivity.

In the pressure-sensitive adhesive sheet according to one aspect of the present invention, the pressure-sensitive adhesive sheet is heated at 190 ° C. for 60 minutes in a nitrogen atmosphere, and then left to stand at 23 ° C. and 50% RH for 24 hours. The surface resistivity on the pressure-sensitive adhesive layer side is preferably 10 ⁻⁷ Ω / □ or more and 10 ⁷ Ω / □ or less.

In the pressure-sensitive adhesive sheet according to one embodiment of the present invention, it is preferable to have a conductive layer between the base material and the pressure-sensitive adhesive layer.

In the pressure-sensitive adhesive sheet according to one aspect of the present invention, the pressure-sensitive adhesive sheet is heated at 190 ° C. for 60 minutes in a nitrogen atmosphere, and then left to stand at 23 ° C. and 50% RH for 24 hours. The surface resistivity on the pressure-sensitive adhesive layer side is preferably 10 ⁻⁷ Ω / □ or more and 10 ⁷ Ω / □ or less.

According to the present invention, the pressure-sensitive adhesive sheet is obtained by using a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer having a surface resistivity of less than a predetermined value after undergoing a process of heating at a high temperature (for example, 150 ° C. or higher and 190 ° C. or lower). Even if it peels from a to-be-adhered body, the adhesive sheet which can suppress the electrostatic breakdown of a semiconductor element can be provided.

It is sectional drawing of the adhesive sheet which concerns on 1st embodiment. It is sectional drawing of the adhesive sheet which concerns on 2nd embodiment. It is sectional drawing of the adhesive sheet which concerns on 3rd embodiment. It is sectional drawing of the adhesive sheet which concerns on 4th embodiment. It is sectional drawing of the adhesive sheet which concerns on 5th embodiment.

Hereinafter, an adhesive sheet according to an embodiment of the present invention will be described with reference to the drawings.

[First embodiment]
FIG. 1 shows a cross-sectional view of an adhesive sheet 10 according to the first embodiment.
In the pressure-sensitive adhesive sheet 10 according to the first embodiment, the base material 11 and the pressure-sensitive adhesive layer 12 are in contact with each other.
The pressure-sensitive adhesive sheet 10 is used when sealing a semiconductor element on the pressure-sensitive adhesive sheet 10.
Not only the semiconductor element but also other members can be attached to the adhesive sheet 10. In this specification, a semiconductor element and other members may be referred to as an adherend. Examples of other members include a frame member. For example, when the semiconductor element on the pressure-sensitive adhesive sheet 10 is sealed with a sealing resin, the frame member can be used to prevent warping of the pressure-sensitive adhesive sheet 10 due to curing shrinkage of the sealing resin.

The pressure-sensitive adhesive sheet 10 includes a base material 11 and a pressure-sensitive adhesive layer 12 containing an antistatic agent. The base material 11 has a first base material surface 11a and a second base material surface 11b opposite to the first base material surface 11a. The pressure-sensitive adhesive layer 12 has a first pressure-sensitive adhesive surface 12a and a second pressure-sensitive adhesive surface 12b opposite to the first pressure-sensitive adhesive surface 12a. In the adhesive sheet 10, the adhesive layer 12 is laminated | stacked on the 1st base material surface 11a. An adherend such as a semiconductor element is attached to the adhesive layer 12. The pressure-sensitive adhesive layer 12 holds the adherend on the pressure-sensitive adhesive sheet 10 in the manufacturing process of the semiconductor device.
The shape of the pressure-sensitive adhesive sheet 10 can take any shape such as a sheet shape, a tape shape, and a label shape.

The pressure-sensitive adhesive sheet 10 of this embodiment has a surface resistivity of 10 ¹¹ Ω after being heated at 190 ° C. and 60 minutes in a nitrogen atmosphere and then allowed to stand at 23 ° C. and 50% RH for 24 hours. Less than / □.
Hereinafter, for example, 150 ° C. to 190 ° C. may be referred to as “high temperature”, and heating at 150 ° C. to 190 ° C. may be referred to as “high temperature heating”.
The present inventors have found that electrostatic breakdown of a semiconductor element can be suppressed by using a pressure-sensitive adhesive sheet having a surface resistivity of less than 10 ¹¹ Ω / □ after high-temperature heating, and to complete the present invention. It came.
According to the pressure-sensitive adhesive sheet 10 of the present embodiment, the electrostatic breakdown of the semiconductor element can be suppressed even after the pressure-sensitive adhesive sheet 10 is peeled off from the adherend after the process of being heated at a high temperature (hereinafter referred to as “book”). Also referred to as “effect of embodiment”).

〔Achievement means〕
The achievement means for obtaining the pressure-sensitive adhesive sheet 10 of the present embodiment (that is, the pressure-sensitive adhesive sheet 10 having a surface resistivity of less than 10 ¹¹ Ω / □ after high-temperature heating) is not particularly limited. The method is mentioned. These methods may be combined.
Method 1: Method of including a specific antistatic agent in the pressure-sensitive adhesive layer 12 Method 2: Method of including a specific antistatic agent in the pressure-sensitive adhesive layer 12 and adjusting the content of the antistatic agent Method 3 : Method / method 4: imparting conductivity to the surface of the base material 11 on the pressure-sensitive adhesive layer 12 side: Method of providing a conductive layer between the base material 11 and the pressure-sensitive adhesive layer 12

By using the above means, the surface resistivity of the pressure-sensitive adhesive layer 12 becomes less than 10 ¹¹ Ω / □ even after high-temperature heating. Therefore, static electricity generated when the pressure-sensitive adhesive sheet 10 is peeled is easily removed through the conductive path formed in the pressure-sensitive adhesive layer 12. In addition, the static electricity is applied even when the pressure-sensitive adhesive sheet 10 has another layer (for example, at least one of a conductive layer and an intermediate layer) between the base material 11 and the pressure-sensitive adhesive layer 12. It tends to be removed through the conductive path formed in the layer.

[Surface resistivity of pressure-sensitive adhesive layer after high-temperature heating]
The surface resistivity of the pressure-sensitive adhesive layer 12 of the pressure-sensitive adhesive sheet 10 refers to a value measured from the surface side of the pressure-sensitive adhesive layer 12 (in the case of FIG. 1, from the first pressure-sensitive adhesive surface 12a side).
The surface resistivity of the pressure-sensitive adhesive layer 12 of the pressure-sensitive adhesive sheet 10 after heating in a nitrogen atmosphere at 190 ° C. for 60 minutes and then standing in a 23 ° C. and 50% RH atmosphere for 24 hours is preferably 1 × 10 ¹¹ Ω. / □, more preferably less than 7 × 10 ¹⁰ Ω / □, and even more preferably less than 5 × 10 ¹⁰ Ω / □.
The lower limit of the surface resistivity of the pressure-sensitive adhesive layer 12 is not particularly limited, but is preferably 1 × 10 ⁴ Ω / □ or more.

The surface resistivity of the pressure-sensitive adhesive layer 12 is measured as follows.
When a release film is provided on the pressure-sensitive adhesive sheet, a part of this pressure-sensitive adhesive sheet with a release film is cut into a size of 90 mm × 90 mm with a cutter or the like. Next, the release film is peeled off from the cut-out pressure-sensitive adhesive sheet with a release film, and the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is affixed to the mirror surface of a silicon mirror wafer (diameter 6 inches, thickness 0.68 mm, mirror surface finished 2000). This is a test piece.
In addition, when the peeling film is not provided in the adhesive sheet, a test piece is obtained by the method similar to the above using the adhesive sheet in which the peeling film is not provided.
Next, the test piece was introduced into an atmospheric electric furnace (SKM-Series SKM-3035F, manufactured by Motoyama), the inside of the furnace was evacuated for 5 minutes, and then filled with nitrogen gas to normal pressure (1 atm). Vacuum the furnace for 5 minutes.
Then, after flowing nitrogen gas and making the inside of the furnace a nitrogen atmosphere, the temperature was raised to 190 ° C. at a rate of temperature rise of 2 ° C./min while maintaining a nitrogen purge (1.5 L / min) and held at 190 ° C. for 60 minutes. To do. Thereafter, the test piece is taken out from the furnace, allowed to cool to room temperature (25 ° C.), and left in an atmosphere of 23 ° C. and 50% RH for 24 hours. The adhesive sheet is peeled off from the test piece (adhesive sheet with a silicon mirror wafer) after being left for 24 hours, and this is used as a test piece for measuring surface resistivity.
Using this test piece for measuring surface resistivity, the surface resistivity of the pressure-sensitive adhesive layer 12 is measured under the following measurement conditions in accordance with JIS K6911 (2006).

-Measurement condition-
・ Device: DIGITAL ELECTROMETER (ADVANTEST)
Measurement environment: 23 ° C and 50% RH
・ Measurement voltage: 100V
・ Voltage application time: 1 min

[Battery voltage of pressure-sensitive adhesive layer after high-temperature heating]
The charged voltage of the pressure-sensitive adhesive layer 12 refers to a value measured from the surface side of the pressure-sensitive adhesive layer 12 (in the case of FIG. 1, from the first pressure-sensitive adhesive surface 12a side).
From the viewpoint of more manifesting the effects of the present embodiment, the pressure-sensitive adhesive sheet 10 is heated at 190 ° C. for 60 minutes in a nitrogen atmosphere and then left to stand at 23 ° C. and 50% RH for 24 hours. The charged voltage of the agent layer 12 is preferably less than 0.1 kV, more preferably less than 0.07 kV, and even more preferably less than 0.05 kV.
The lower limit of the charged voltage of the pressure-sensitive adhesive layer 12 is not particularly limited, but is preferably 0.001 kV or more.
The achievement means for obtaining the pressure-sensitive adhesive sheet 10 having a voltage of the pressure-sensitive adhesive layer 12 of less than 0.1 kV is not particularly limited, and examples thereof include the above-described method 1 to method 4.

The charged voltage of the pressure-sensitive adhesive layer 12 is measured as follows.
In the same manner as the method for measuring the surface resistivity of the pressure-sensitive adhesive layer 12, a test piece and a test piece for measuring charged voltage are obtained.
However, the size when cutting out a part of the pressure-sensitive adhesive sheet with a release film or a part of the pressure-sensitive adhesive sheet with a cutter or the like is 40 mm × 40 mm.
Using the test piece for measuring the charged voltage, the charged voltage of the pressure-sensitive adhesive layer 12 is measured under the following measurement conditions in accordance with JIS L1094 (2014).

-Measurement condition-
・ Apparatus: STATIC HONESTETER H-0110 (manufactured by Cicid Electrostatics)
Measurement environment: 23 ° C and 50% RH
・ Applied voltage: 10 kV
・ Voltage application time: 1 min

[Adhesive strength of the adhesive layer to copper foil and polyimide film after high-temperature heating]
<Adhesive strength to copper foil>
From the viewpoint of more manifesting the effect of the present embodiment, the pressure-sensitive adhesive sheet 10 is heated at 100 ° C. and 30 minutes, subsequently heated at 180 ° C. and 30 minutes, and further at 190 ° C. and 60 minutes. The adhesive strength of the adhesive layer 12 to the copper foil after being heated and then allowed to stand for 24 hours in an atmosphere of 23 ° C. and 50% RH is preferably 0.50 N / 25 mm to 3.00 N / 25 mm, more preferably It is 1.00 N / 25 mm or more and 2.50 N / 25 mm or less, More preferably, it is 1.50 N / 25 mm or more and 2.00 N / 25 mm or less.
When the adhesive strength of the adhesive layer 12 to the copper foil is 0.50 N / 25 mm or more, the adhesive sheet 10 can be prevented from peeling off from the adherend when the substrate 11 or the adherend is deformed by heating.
When the adhesive force of the adhesive layer 12 to the copper foil is 3.00 N / 25 mm or less, the peeling force does not become too high, and the adhesive sheet 10 is easily peeled from the adherend.
Although the achievement means for obtaining the adhesive sheet 10 whose adhesive force with respect to the copper foil of the adhesive layer 12 is the said range is not specifically limited, For example, the above-mentioned method 1 to method 4 are mentioned.

The adhesive force with respect to the copper foil of the adhesive layer 12 is measured as follows.
When a release film is provided on the pressure-sensitive adhesive sheet, a part of this pressure-sensitive adhesive sheet with a release film is cut into a size of 25 mm × 25 mm with a cutter or the like. Next, the release film is peeled off from the cut-out adhesive sheet with release film, and the adhesive layer of the adhesive sheet is copper foil (150 mm × 100 mm, thickness 0.08 mm, JIS H3100: 2010 C1220R-H (stretched copper foil)) Is attached in accordance with JIS Z 0237: 2009. This is a test piece for copper foil.
In addition, when the peeling film is not provided in the adhesive sheet, the test piece for copper foils is obtained by the method similar to the above using an adhesive sheet.
Next, the test piece for copper foil was introduced into an atmospheric electric furnace (SKM-Series SKM-3035F, manufactured by Motoyama), heated at 100 ° C. for 30 minutes, and then at 180 ° C. for 30 minutes. It heats, and also heats on the conditions of 190 degreeC and 1 hour. Thereafter, the test piece is taken out from the furnace, allowed to cool to room temperature (25 ° C.), and left to stand in an atmosphere of 23 ° C. and 50% RH for 24 hours.
Using the test piece for copper foil after being left for 24 hours, the adhesive strength of the adhesive layer 12 to the copper foil is measured under the following measurement conditions.

-Measurement condition-
・ Device: Tensile tester (manufactured by Shimadzu Corporation, Autograph AG-IS 500N)
・ Peeling angle: 180 degrees ・ Peeling speed: 300 mm / min
・ Measurement environment: 23 ° C. and 50% RH

<Adhesive strength to polyimide film>
From the viewpoint of more manifesting the effect of the present embodiment, the pressure-sensitive adhesive sheet 10 is heated at 100 ° C. and 30 minutes, subsequently heated at 180 ° C. and 30 minutes, and further at 190 ° C. and 60 minutes. The adhesive strength of the pressure-sensitive adhesive layer 12 to the polyimide film after being heated and then allowed to stand at 23 ° C. and 50% RH for 24 hours is preferably 0.50 N / 25 mm or more and 2.00 N / 25 mm or less, more preferably It is 0.70 N / 25 mm or more and 1.80 N / 25 mm or less, More preferably, it is 1.00 N / 25 mm or more and 1.50 N / 25 mm or less.
When the adhesive force of the adhesive layer 12 to the polyimide film is 0.50 N / 25 mm or more, the adhesive sheet 10 can be prevented from peeling off from the adherend when the substrate 11 or the adherend is deformed by heating.
When the adhesive force of the pressure-sensitive adhesive layer 12 to the polyimide film is 2.00 N / 25 mm or less, the peeling force does not become too high, and the pressure-sensitive adhesive sheet 10 is easily peeled off from the adherend.
Although it does not specifically limit as an achievement means for obtaining the adhesive sheet 10 whose adhesive force with respect to the polyimide film of the adhesive layer 12 is the said range, The above-mentioned method 1 to method 4, and the kind and content rate of the adhesive component mentioned later The method etc. of adjusting are mentioned.

The adhesive force with respect to the polyimide film of the adhesive layer 12 is measured as follows.
A polyimide film (150 mm × 70 mm, thickness 50 μm, manufactured by Toray DuPont, Kapton 200H) is attached to a stainless steel plate with a double-sided tape.
In the method for measuring the adhesive strength to the copper foil, the copper of the adhesive layer 12 is used except that the adhesive layer 12 of the adhesive sheet 10 is affixed to the polyimide film of the adherend A instead of being affixed to the copper foil. The adhesive force with respect to the polyimide film of the adhesive layer 12 is measured by the same method as the method for measuring the adhesive force with respect to the foil.

Next, the configuration of the pressure-sensitive adhesive sheet 10 of this embodiment will be described. Hereinafter, the description of the reference numerals is omitted.

<Base material>
A base material is a member which supports an adhesive layer.
As the substrate, for example, a sheet material such as a synthetic resin film can be used. Examples of synthetic resin films 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 copolymer film, ionomer resin film, ethylene / (meth) acrylic acid copolymer film, ethylene / (meth) acrylic acid ester copolymer film, polystyrene film, polycarbonate film, and polyimide film Etc. In addition, examples of the substrate include these crosslinked films and laminated films.

The base material preferably contains a polyester-based resin, and more preferably is made of a material mainly composed of a polyester-based resin. In this specification, the material having a polyester-based resin as a main component means that the proportion of the mass of the polyester-based resin in the entire material constituting the base material is 50% by mass or more.
The polyester resin is, for example, any resin selected from the group consisting of polyethylene terephthalate resin, polybutylene terephthalate resin, polyethylene naphthalate resin, polybutylene naphthalate resin, and copolymer resins of these resins. Is preferred, and polyethylene terephthalate resin is more preferred.
As the base material 11, a polyethylene terephthalate film or a polyethylene naphthalate film is preferable, and a polyethylene terephthalate film is more preferable. The oligomer contained in the polyester film is derived from a polyester-forming monomer, a dimer, a trimer, and the like.

In the pressure-sensitive adhesive sheet of the present embodiment, the storage elastic modulus at 100 ° C. of the substrate is preferably 1 × 10 ⁷ Pa or more from the viewpoint of improving the workability.
The lower limit of the storage elastic modulus at 100 ° C. of the substrate is preferably 1 × 10 ⁷ Pa or more, more preferably 1 × 10 ⁸ Pa or more, from the viewpoint of dimensional stability during processing. The upper limit of the storage elastic modulus at 100 ° C. of the substrate is preferably 1 × 10 ¹² Pa or less from the viewpoint of processability. In the present specification, the storage elastic modulus is a value measured at a frequency of 1 Hz by a torsional shear method using a dynamic viscoelasticity measuring device. The substrate to be measured is cut into a width of 5 mm and a length of 20 mm, and a viscoelasticity measuring device (manufactured by TA Instruments, DMAQ800) is used, and the storage viscoelasticity at 100 ° C. is measured at a frequency of 1 Hz and a tensile mode. Measure.

The first substrate surface of the substrate is subjected to primer treatment, corona treatment, plasma treatment, etc. in order to enhance adhesion with a layer (adhesive layer in this embodiment) formed on the first substrate surface. At least one of the surface treatments may be performed. In addition, when the pressure-sensitive adhesive layer is formed on the first base material surface through, for example, an intermediate layer, the first base material surface is coated with a pressure-sensitive adhesive in order to improve adhesion with the intermediate layer. An adhesion treatment may be performed. Examples of the pressure-sensitive adhesive used for this pressure-sensitive adhesive treatment include acrylic, rubber-based, silicone-based, and urethane-based pressure-sensitive adhesives.

From the viewpoint of more manifesting the effects of the present embodiment, the surface of the substrate on the side of the pressure-sensitive adhesive layer (in the case of FIG. 1, the first substrate surface 11a) preferably has conductivity. The whole base material may have electroconductivity as well as the surface. Thereby, it is considered that the antistatic performance of the surface of the pressure-sensitive adhesive layer after heating at high temperature (in the case of FIG. 1, the first pressure-sensitive adhesive surface 12a) is improved.

When the surface of the base material on the pressure-sensitive adhesive layer side (hereinafter also referred to as the base material surface) has conductivity, the pressure-sensitive adhesive sheet is heated at 190 ° C. under a nitrogen atmosphere from the viewpoint of further expressing the effects of the present embodiment. The surface resistivity of the substrate surface after being heated for 60 minutes and then allowed to stand for 24 hours in an atmosphere of 23 ° C. and 50% RH is preferably 10 ⁻⁷ Ω / □ or more and 10 ⁷ Ω / □ or less, more preferably It is 10 ⁻⁷ Ω / □ or more and 10 ⁵ Ω / □ or less, more preferably 10 ⁻⁷ Ω / □ or more and 10 ⁴ Ω / □ or less.
The surface resistivity of the substrate refers to a value measured from the surface side on the pressure-sensitive adhesive layer side of the substrate (in the case of FIG. 1, from the first substrate surface 11a side). The measuring method is the same as the measuring method of the surface resistivity of the pressure-sensitive adhesive layer described above.
As the test piece for measurement, a pressure-sensitive adhesive sheet in which the layer laminated on the substrate is removed and the surface of the substrate is exposed is used.

The method for imparting conductivity to the surface of the substrate is not particularly limited. For example, a substrate is prepared by dispersing or kneading a conductive material (for example, an antistatic agent described later) in advance in the material constituting the substrate. And a method of applying a conductive material to the surface of the substrate, a method of forming a layer made of a metal or an alloy on the surface of the substrate, and the like. Examples of the method for forming a layer made of a metal or alloy on the surface of the substrate include electroless plating, electrolytic plating, vapor deposition, and sputtering.

When the surface of the substrate does not have conductivity, the surface resistivity of the substrate is preferably 10 ⁴ Ω / □ or more and 10 ¹⁶ Ω / □ or less, more preferably 10 ⁷ Ω / □ or more and 10 ¹⁶ Ω / □ or less. More preferably, it is 10 ⁸ Ω / □ or more and 10 ¹⁶ Ω / □ or less.

The thickness of the substrate is preferably 10 μm or more and 300 μm or less, more preferably 15 μm or more and 200 μm or less, and further preferably 20 μm or more and 100 μm or less.

<Adhesive layer>
The pressure-sensitive adhesive layer is a layer formed from a pressure-sensitive adhesive composition containing an antistatic agent (hereinafter also simply referred to as “pressure-sensitive adhesive composition”).

(Antistatic agent)
Examples of the antistatic agent contained in the pressure-sensitive adhesive composition include carbon materials, ionic materials, metal fine particles, metal oxides, metal fillers, and surfactants.
From the viewpoint of more manifesting the effects of the present embodiment, the antistatic agent preferably includes at least one selected from the group consisting of a carbon material and an ionic material.

Carbon material Examples of the carbon material include carbon nanotubes, carbon nanofibers, graphene, carbon black, milled carbon fibers, and graphite. These materials may use commercially available products.
The carbon nanotubes and graphene may be single-walled or multi-layered.
Examples of carbon black include ketjen black, furnace black, and acetylene black.
These carbon materials can be used individually by 1 type or in combination of 2 or more types.
The carbon material is preferably at least one selected from the group consisting of carbon nanotubes, graphene, and carbon black.

When the pressure-sensitive adhesive sheet of this embodiment has a conductive layer (in the case of the second embodiment, the third embodiment, and the fifth embodiment described later) or the substrate surface has conductivity, a carbon material The content of depends on the type of carbon material, but is preferably 1.0% by mass or more and less than 15.0% by mass, more preferably 1.5% by mass or more and less than 13.0% by mass with respect to the entire pressure-sensitive adhesive layer. More preferably, it is 2.0 mass% or more and less than 10.0 mass%.
When the content of the carbon material is 1.0% by mass or more, antistatic performance is easily exhibited.
When the content of the carbon material is less than 15.0% by mass, the occurrence of aggregation and poor dispersion of the carbon material is easily suppressed. Moreover, since the viscosity increase of an adhesive composition is suppressed as content of a carbon material is less than 15 mass%, a smooth coating surface is easy to be obtained.
When the pressure-sensitive adhesive sheet of this embodiment does not have a conductive layer (in the case of the first embodiment and the fourth embodiment described later) or the substrate surface does not have conductivity, the content of the carbon material Depending on the type of the carbon material, it is preferably 2.5% by mass or more and less than 15.0% by mass, more preferably 3.0% by mass or more and less than 13.0% by mass, and still more preferably, with respect to the entire pressure-sensitive adhesive layer. Is 5.0 mass% or more and less than 10.0 mass%.
When the content of the carbon material is 2.5% by mass or more, antistatic performance is easily exhibited.
When the content of the carbon material is less than 15.0% by mass, the occurrence of aggregation and poor dispersion of the carbon material is easily suppressed. Moreover, since the viscosity increase of an adhesive composition is suppressed as content of a carbon material is less than 15 mass%, a smooth coating surface is easy to be obtained.

-Ionic material It is preferable that an ionic material is at least 1 sort (s) selected from the group which consists of an ionic liquid and an ionic polymer.

-Ionic liquid An ionic liquid is a salt comprised by a cation and an anion.
As the cation of the ionic liquid, a nonmetallic ion is preferable, and examples thereof include an imidazolium cation, a pyridinium cation, a pyrrolidinium cation, a quaternary ammonium cation, and a quaternary phosphonium cation.

Examples of the anion of the ionic liquid include an anion represented by the following general formula (1), CF ₃ CO ₂ ⁻ , CF ₃ (CF ₂ ) ₃ SO ₃ ⁻ , CF ₃ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₃ C ⁻ , CF ₃ (CF ₂ ) ₂ CO ₂ ⁻ , BF ₃ (CF ₃ ) ⁻ , BF ₃ (C ₂ F ₅ ) ⁻ , BF ₃ (C ₃ F ₇ ) ⁻ , BF ₂ (CF ₃ ) ₂ ⁻ , BF ₂ (CF ₃ ) (C ₂ F ₅ ) ⁻ , PF ₅ (CF ₃ ) ⁻ , PF ₅ (C ₂ F ₅ ) ⁻ , PF ₅ (C ₃ F ₇ ) ⁻ , PF ₄ (CF ₃ ) ₂ ⁻ , PF ₄ (CF ₃ ) (C ₂ F ₅ ) ⁻ , PF ₃ (CF ₃ ) ₃ ⁻ , B (C ₂ O ₄ ) ₂ ⁻ , CH ₃ CH ₂ OSO ₃ ⁻ , CH ₃ CO ₂ ⁻ Etc.
Among these, an anion having a van der Waals radius of 0.260 nm or more is preferable, an anion of 0.280 nm or more is more preferable, and an anion of 0.300 nm or more is more preferable.
When the van der Waals radius is an anion having a radius of 0.260 nm or more, the ionic liquid is hardly crystallized, and the ionic liquid tends to exist as a liquid at room temperature. That is, the ionic liquid is easily dissociated. Even if the pressure-sensitive adhesive layer containing such anions is heated at a high temperature, the pressure-sensitive adhesive layer is hardly deteriorated. As a result, the effect of the present embodiment is more easily expressed.

The ionic liquid preferably contains a cation and an anion represented by the following general formula (1) (hereinafter also referred to as “specific imide anion”).
When the anion of the ionic liquid is a specific imide anion, the van der Waals radius becomes large (preferably 0.260 nm or more), and therefore the effect of the present embodiment is more manifested for the same reason as described above. It becomes easy.
In this specification, the van der Waals radius is a value based on the following document.・ M.Ue, J. Electrochem. Soc., 141, 3336 (1994) ・ M. Ue, A. Murakami, S. Nakamura, J. Electrochem. Soc., 149, A1385 (2002)

In the general formula (1), R ¹ and R ² are each independently a fluorine atom or a perfluoroalkyl group having 1 to 8 carbon atoms, and R ¹ and R ² are the same or different.

In the general formula (1), R ¹ and R ² are each independently preferably a perfluoroalkyl group having 1 to 8 carbon atoms, more preferably a perfluoroalkyl group having 1 to 6 carbon atoms, still more preferably A perfluoroalkyl group having 1 to 4 carbon atoms.
R ¹ and R ² are preferably the same.

The content of the ionic liquid depends on the type of the ionic liquid, but is preferably 0.01% by mass or more and 10% by mass or less, more preferably 0.05% by mass or more and 8% by mass or less with respect to the entire pressure-sensitive adhesive layer. More preferably, it is 0.1 mass% or more and 5 mass% or less.
When the content of the ionic liquid is 0.01% by mass or more, antistatic performance is easily exhibited.
When the content of the ionic liquid is 10% by mass or less, contamination of the adherend due to bleed out is easily suppressed, and adhesive strength is easily secured.

From the viewpoint of more manifesting the effects of the present embodiment, the antistatic agent is preferably an ionic liquid or a mixture of an ionic liquid and a carbon material.
When the antistatic agent is a mixture of an ionic liquid and a carbon material, when developing the same surface resistivity, the total content of the antistatic agent is smaller than when using a single type of antistatic agent alone. Since a predetermined antistatic performance can be exhibited, it is preferable because a decrease in adhesive force accompanying a decrease in the content of the adhesive component can be suppressed.
When the antistatic agent is a mixture of an ionic liquid and a carbon material, the total content of the antistatic agent (the total content of the ionic liquid and the carbon material) is preferably 0. It is 01 mass% or more and 8 mass% or less, More preferably, it is 0.05 mass% or more and 7 mass% or less, More preferably, it is 0.1 mass% or more and 6 mass% or less.
When the antistatic agent is a mixture of an ionic liquid and a carbon material, the mass ratio (Iw / Cw) of the ionic liquid content Iw and the carbon material content Cw is preferably 0.01 / 15 or more. It is 10/2 or less, more preferably 0.05 / 13 or more and 8/3 or less, and further preferably 0.10 / 10 or more and 5/5 or less.
When the mass ratio (Iw / Cw) is 0.01 / 15 or more, the ratio of the ionic liquid becomes an appropriate amount, and an increase in the charged voltage can be suppressed. Thereby, it becomes easy to suppress generation | occurrence | production of the charge at the time of peeling of an adhesive sheet.
When the mass ratio (Iw / Cw) is 10/2 or less, the ratio of the ionic liquid is suppressed from being excessive, so that the component derived from the ionic liquid is transferred to the adherend surface when the adhesive sheet is peeled off. Is less likely to occur.

-Ionic polymer As an ionic polymer, the polymer which has an ionic functional group and an energy-beam curable group is mentioned, for example.
The ionic functional group is a concept including a cationic group (hereinafter also simply referred to as “cation”) and an anionic group (hereinafter also simply referred to as “anion”). That is, the ionic polymer is a polymer containing a cation and an anion for the cation, and can form an ionic bond between the cation and the anion.
The ionic polymer exhibits antistatic performance by having an ionic functional group.
The ionic polymer may have a cation in the main chain or a side chain, but preferably has a cation in the side chain.

・ Ionic functional groups (cations, anions)
Examples of the cation contained in the ionic polymer include a quaternary ammonium cation, a phosphonium cation, a sulfonium cation, an oxonium cation, a diazonium cation, a chloronium cation, an iodonium cation, and a pyrylium cation. These cations can be used alone or in combination of two or more.

Among these, a quaternary ammonium cation excellent in antistatic performance is particularly preferable as the cation.
Here, the “quaternary ammonium cation” means an onium cation of nitrogen, and includes heterocyclic onium ions such as imidazolium and pyridium. Examples of the quaternary ammonium cation include alkylammonium cations (herein, “alkyl” includes those substituted with a hydroxy group and an alkoxyalkyl in addition to a hydrocarbon group having 1 to 30 carbon atoms); Heterocyclic cation such as nium cation, pyrrolium cation, imidazolium cation, pyrazolium cation, pyridinium cation, piperidinium cation, piperazinium cation; indolium cation, benzimidazolium cation, carbazolium cation, key And condensed heterocyclic cations such as a norinium cation. Any of them includes a nitrogen atom and / or a ring to which a hydrocarbon group, hydroxyalkyl group or alkoxyalkyl group having 1 to 30 carbon atoms (for example, 1 to 10 carbon atoms) is bonded. In this specification, a numerical range expressed using “to” means a range including a numerical value described before “to” as a lower limit value and a numerical value described after “to” as an upper limit value. To do.

Examples of the anion contained in the ionic polymer include an anion having a halogen atom, and derivatives of oxo acids such as carboxylic acid, sulfonic acid, and phosphoric acid (for example, hydrogen sulfate, methanesulfonate, ethylsulfate, dimethylphosphate, 2- (2-methoxyethoxy) ethyl sulfate, dicyanamide, etc.), among which an anion having a halogen atom is preferred. Specifically, (FSO ₂ ) ₂ N ⁻ (bis {(fluoro) sulfonyl} imide anion), (CF ₃ SO ₂ ) ₂ N ⁻ (bis {(trifluoromethyl) sulfonyl} imide anion), (C ₂ F ₅ SO ₂ ) ₂ N ⁻ (bis {(pentafluoroethyl) sulfonyl} imide anion), CF ₃ SO ₂ —N—COCF ₃ ⁻ , R—SO ₂ —N—SO ₂ CF ₃ ^— (R is aliphatic Group), ArSO ₂ —N—SO ₂ CF ₃ ^— (Ar is an aromatic group) and other anions having a nitrogen atom; C _n F _{2n + 1} CO ₂ ^— (n is an integer of 1 to 4), (CF ₃ SO ₂ Anion having a fluorine atom as a halogen atom, such as ₃ C ⁻ , C _n F _{2n + 1} SO ₃ ⁻ (n is an integer of 1 to 4), BF ₄ ⁻ , PF ₆ ^{— and the} like, is preferably exemplified. Among these, bis {(fluoro) sulfonyl} imide anion, bis {(trifluoromethyl) sulfonyl} imide anion, bis {(pentafluoroethyl) sulfonyl} imide anion, 2,2,2-trifluoro-N- { (Trifluoromethyl) sulfonyl} acetimide anion, tetrafluoroborate anion, and hexafluorophosphate anion are particularly preferred.
These anions can be used individually by 1 type, and can also be used in combination of 2 or more type.

-Energy ray curable group The ionic polymer has an energy ray curable group in the side chain, so when the energy layer is irradiated to the adhesive layer, the ionic polymer or the ionic polymer and the adhesive composition described later are used. The adhesive in the product reacts and crosslinks. Therefore, bleeding out of the pressure-sensitive adhesive layer of the ionic polymer is suppressed, and when the pressure-sensitive adhesive sheet is peeled off from the adherend, it is difficult for adhesive residue (particles) to be generated, and contamination of the adherend is suppressed. be able to.

The energy ray curable group is, for example, a group containing an energy ray curable carbon-carbon double bond. Specific examples include a (meth) acryloyl group and a vinyl group. Among them, a (meth) acryloyl group, particularly a methacryloyl group is preferable.
The content of the energy ray-curable group per unit mass of the ionic polymer is preferably 5 × 10 ⁻⁵ to 2 × 10 ⁻³ mol / g, and 1 × 10 ⁻⁴ to 1.5 × 10 ^−3. The molar ratio is particularly preferably 3 × 10 ⁻⁴ to 1 × 10 ⁻³ mol / g.

The ionic polymer has, for example, a polymerizable monomer having an ionic functional group (preferably a polymerizable monomer having a quaternary ammonium cation), a polymerizable monomer having a reactive functional group, and, if necessary, an ether bond. A polymerizable monomer and another polymerizable monomer (preferably an acrylic polymerizable monomer) are copolymerized and then contain a curable group having a substituent that reacts with the reactive functional group and an energy ray-curable group. It can be obtained by reacting a compound (hereinafter also referred to as “energy ray curable compound”).

The “polymerizable monomer having a quaternary ammonium cation” is preferably composed of a quaternary ammonium cation having a polymerizable group and an anion corresponding thereto.
Examples of the polymerizable group include cyclic ethers having a carbon-carbon unsaturated group such as (meth) acryloyl group, vinyl group and allyl group, epoxy group and oxetane group, cyclic sulfides such as tetrahydrothiophene, and isocyanate groups. Among them, (meth) acryloyl group and vinyl group are preferable.

The proportion of the mass of the structural portion derived from the “polymerizable monomer having a quaternary ammonium cation” in the total mass of the ionic polymer is preferably 20% by mass or more and 80% by mass or less, and 25% by mass or more and 75% by mass or less. It is more preferable that it is 35 mass% or more and 60 mass% or less.
When the proportion of the mass of the structural portion derived from the “polymerizable monomer having a quaternary ammonium cation” is 20% by mass or more, the ionic polymer exhibits sufficient antistatic properties.
When the proportion of the mass of the structural portion derived from the “polymerizable monomer having a quaternary ammonium cation” is 80% by mass or less, the proportion of the mass of the structural portion derived from another monomer can be controlled within a preferable range.

As the “polymerizable monomer having a reactive functional group”, a (meth) acrylic acid ester monomer having a functional group such as a carboxyl group, a hydroxy group, an amino group, a substituted amino group, and an epoxy group in addition to (meth) acrylic acid Among them, (meth) acrylic acid is preferable.

The proportion of the mass of the structural portion derived from the “polymerizable monomer having a reactive functional group” in the mass of the entire ionic polymer is preferably 1% by mass to 35% by mass, and preferably 3% by mass to 20% by mass. It is more preferable that it is 3 mass% or more and 10 mass% or less.
When the proportion of the mass of the structural portion derived from the “polymerizable monomer having a reactive functional group” is within the above range, the amount of energy ray curable group introduced into the ion polymer of the energy ray curable compound is controlled within a preferable range. be able to.

Also, the ionic polymer preferably has a structural unit having an ether bond in the side chain. In this case, “polymerizable monomer having an ether bond” is used as a raw material of the ionic polymer. Examples of the “polymerizable monomer having an ether bond” include (meth) acrylate having an ether bond.

The proportion of the mass of the structural portion derived from the “polymerizable monomer having an ether bond” in the total mass of the ionic polymer is preferably 5% by mass or more and 70% by mass or less, and preferably 10% by mass or more and 50% by mass or less. Particularly preferred is 15% by mass or more and 40% by mass or less.
When the proportion of the mass of the structural portion derived from the “polymerizable monomer having an ether bond” is in the above range, the effect of improving the antistatic performance of the pressure-sensitive adhesive layer is more easily obtained.

As the “other polymerizable monomer”, an acrylic polymerizable monomer is preferable.
As the “other polymerizable monomer”, (meth) acrylic acid ester is preferably exemplified. Examples of the (meth) acrylic acid ester have a chain skeleton such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate ( (Meth) acrylate; having a cyclic skeleton such as cyclohexyl (meth) acrylate, benzyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, imide acrylate ( And (meth) acrylate. When the (meth) acrylic acid ester is a (meth) acrylic acid alkyl ester, the alkyl group preferably has 1 to 18 carbon atoms.

Examples of the “energy ray curable compound” are not particularly limited as long as they have an energy ray curable group, but are low molecular weight compounds (monofunctional and polyfunctional monomers and oligomers) from the viewpoint of versatility. Is preferred. Specific examples of the low molecular weight energy ray-curable compound (A2) include trimethylolpropane tri (meth) acrylate, tetramethylolmethanetetra (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol monohydroxypenta ( (Meth) acrylate, dipentaerythritol hexa (meth) acrylate or 1,4-butylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, dicyclopentadiene dimethoxydi (meth) acrylate, isobornyl (meth) ) Cyclic aliphatic skeleton-containing (meth) acrylate such as acrylate, oligoester (meth) acrylate, urethane (meth) acrylate oligomer, epoxy-modified (meth) acrylate, Include acrylate-based compound.

It is preferable that the “energy ray curable compound” and the “polymerizable monomer having a reactive functional group” are reacted so that the molar equivalent is about the same amount.

The weight average molecular weight of the ionic polymer is preferably 500 to 200,000, particularly preferably 800 to 100,000, and more preferably 800 to 50,000, from the viewpoint of more manifesting the effects of the present embodiment. preferable.
In addition, the weight average molecular weight of an ionic polymer is the value of standard polymethylmethacrylate conversion measured on the following measurement conditions by the gel permeation chromatography (GPC) method.

-Measurement condition-
Column: Shodex HFIP-LG and HFIP-806M (two) connected in this order Solvent: hexafluoroisopropanol (5 mM sodium trifluoroacetate added)
・ Measurement temperature: 40 ℃
・ Flow rate: 0.5 ml / min ・ Detector: Differential refractometer ・ Standard sample: Polymethyl methacrylate

The content of the ionic polymer depends on the type of the ionic functional group contained in the ionic polymer, but is preferably 0.01% by mass or more and 20% by mass or less, more preferably 0.05% by mass with respect to the entire pressure-sensitive adhesive layer. It is 18 mass% or less, More preferably, it is 0.10 mass% or more and 15 mass% or less.
When the content of the ionic polymer is 0.01% by mass or more, antistatic performance is easily exhibited.
When the content of the ionic polymer is 20% by mass or less, the cohesive force of the pressure-sensitive adhesive layer before irradiation with energy rays is maintained high, so that adhesive residue on the adherend surface when the pressure-sensitive adhesive sheet is peeled is easily suppressed.

Metal fine particles, metal oxides, metal fillers, and surfactants Examples of metal fine particles and metal fillers include aluminum, copper, titanium, iron, and nickel.
Examples of the metal oxide include ITO (indium tin oxide), ZnO (zinc oxide), IZO (indium zinc oxide), AZO (zinc aluminum oxide), GZO (zinc gallium oxide), IGZO (indium gallium zinc oxide), and ATO. (Tin antimony oxide) and the like.
As the surfactant, a known one can be used.

(Adhesive composition)
It does not specifically limit as an adhesive contained in the adhesive composition containing an antistatic agent, Various types of adhesive can be applied to an adhesive layer. Examples of the adhesive contained in the adhesive layer 12 include rubber-based, acrylic-based, silicone-based, polyester-based, and urethane-based. In addition, the kind of adhesive is selected in consideration of the use, the kind of adherend to be attached, and the like. The pressure-sensitive adhesive layer 12 preferably contains an acrylic pressure-sensitive adhesive composition or a silicone-based pressure-sensitive adhesive composition.

Acrylic pressure-sensitive adhesive composition The acrylic pressure-sensitive adhesive composition is also referred to as a (meth) acrylic acid alkyl ester having an alkyl group having 4 to 12 carbon atoms (hereinafter referred to as “specific (meth) acrylic acid alkyl ester”). It is preferable to include an acrylic copolymer having a main monomer.
In this specification, “(meth) acrylic acid” is a notation used to represent both “acrylic acid” and “methacrylic acid”, and the same applies to other similar terms.
In the present specification, “specific (meth) acrylic acid alkyl ester” is the main monomer, and the mass of the copolymer component derived from the specific (meth) acrylic acid alkyl ester in the total mass of the acrylic copolymer. It means that the ratio of is 50 mass% or more.
The carbon number of the alkyl group in the specific (meth) acrylic acid alkyl ester is preferably 4 or more and 12 or less, more preferably 4 or more and 10 or less, and still more preferably 4 or more and 8 or less.
The alkyl group in the specific (meth) acrylic acid alkyl ester may be linear, branched, or cyclic, but is preferably branched.
The specific (meth) acrylic acid alkyl ester may be used alone or in combination of two or more, but the main monomer is preferably used alone.

The specific (meth) acrylic acid alkyl ester is preferably 2-ethylhexyl acrylate. That is, the acrylic pressure-sensitive adhesive composition preferably contains an acrylic copolymer having 2-ethylhexyl acrylate as a main monomer.

In the present embodiment, the proportion of the copolymer component derived from the specific (meth) acrylic acid alkyl ester (preferably 2-ethylhexyl acrylate) in the acrylic copolymer is from 50% by mass to 95% by mass. It is preferably 60% by mass to 95% by mass, more preferably 80% by mass to 95% by mass, and still more preferably 85% by mass to 93% by mass. .
When the proportion of the copolymer component derived from a specific (meth) acrylic acid alkyl ester (preferably 2-ethylhexyl acrylate) is 50% by mass or more, the adhesive strength does not become too high after heating, The pressure-sensitive adhesive sheet is more easily peeled off, and is more easily peeled off at 80% by mass or more. If the proportion of the copolymer component derived from 2-ethylhexyl acrylate is 95% by mass or less, the initial adhesive force is insufficient and the substrate is deformed during heating, or the adhesive sheet is peeled off from the adherend due to the deformation. Can be prevented.
Moreover, when an adhesive layer contains an acrylic adhesive composition, it is preferable that the antistatic agent, the acrylic copolymer, and the adhesion adjuvant are included. The acrylic copolymer is preferably a copolymer having a specific (meth) acrylic acid alkyl ester (preferably 2-ethylhexyl acrylate) as a main monomer. The adhesion aid preferably contains a rubber-based material having a reactive group as a main component.

The type and number of copolymer components other than the specific (meth) acrylic acid alkyl ester (preferably 2-ethylhexyl acrylate) in the acrylic copolymer are not particularly limited. For example, as the second copolymer component, a functional group-containing monomer having a reactive functional group is preferable. As a reactive functional group of a 2nd copolymer component, when using the crosslinking agent mentioned later, it is preferable that it is a functional group which can react with the said crosslinking agent. This reactive functional group is preferably at least one substituent selected from the group consisting of, for example, a carboxyl group, a hydroxyl group, an amino group, a substituted amino group, and an epoxy group. These substituents are more preferable, and a carboxyl group is still more preferable.

Examples of the monomer having a carboxyl group (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 the carboxyl group-containing monomers, acrylic acid is preferable from the viewpoint of reactivity and copolymerization. A carboxyl group-containing monomer may be used independently and may be used in combination of 2 or more type.

Examples of the monomer having a hydroxyl group (hydroxyl group-containing monomer) include, for example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, (meth) acrylic acid 2 And (meth) acrylic acid hydroxyalkyl esters such as hydroxybutyl, 3-hydroxybutyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate. Among the hydroxyl group-containing monomers, 2-hydroxyethyl (meth) acrylate is preferred from the viewpoint of hydroxyl reactivity and copolymerization. A hydroxyl-containing monomer may be used independently and may be used in combination of 2 or more type.

Examples of the acrylate ester having an epoxy group include glycidyl acrylate and glycidyl methacrylate.

When the main monomer in the acrylic copolymer is one specific (meth) acrylic acid alkyl ester (preferably 2-ethylhexyl acrylate), other copolymer components other than the main monomer include an alkyl group (Meth) acrylic acid alkyl ester having 2 to 20 carbon atoms. Examples of (meth) acrylic acid alkyl esters include, for example, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, n-pentyl (meth) acrylate, and (meth) acrylic acid n. -Hexyl, 2-ethylhexyl methacrylate, isooctyl (meth) acrylate, n-decyl (meth) acrylate, n-dodecyl (meth) acrylate, myristyl (meth) acrylate, palmityl (meth) acrylate, and ( Examples thereof include stearyl methacrylate. Among these (meth) acrylic acid alkyl esters, from the viewpoint of further improving adhesiveness, (meth) acrylic acid esters having an alkyl group with 2 or more and 4 or less carbon atoms are preferred, and (meth) acrylic acid n-butyl is preferred. More preferred. The (meth) acrylic acid alkyl ester may be used alone or in combination of two or more.

Other copolymer components in the acrylic copolymer include, for example, alkoxyalkyl group-containing (meth) acrylic acid ester, (meth) acrylic acid ester having an aliphatic ring, and (meth) acrylic acid having an aromatic ring. A copolymer component derived from at least one monomer selected from the group consisting of an ester, a non-crosslinkable acrylamide, a (meth) acrylic acid ester having a non-crosslinkable tertiary amino group, vinyl acetate, and styrene; Can be mentioned.
Examples of the alkoxyalkyl group-containing (meth) acrylic acid ester include methoxymethyl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxymethyl (meth) acrylate, and ethoxyethyl (meth) acrylate. .
Examples of the (meth) acrylic acid ester having an aliphatic ring include cyclohexyl (meth) acrylate.
Examples of the (meth) acrylic acid ester having an aromatic ring include phenyl (meth) acrylate.
Examples of the non-crosslinkable acrylamide include acrylamide and methacrylamide.
Examples of the (meth) acrylic acid ester having a non-crosslinkable tertiary amino group include (meth) acrylic acid (N, N-dimethylamino) ethyl and (meth) acrylic acid (N, N-dimethylamino). Propyl.
As the other copolymer component in the acrylic copolymer, a copolymer component derived from a monomer having a nitrogen atom-containing ring is also preferable from the viewpoint of improving the polarity of the pressure-sensitive adhesive and improving the adhesion and adhesive force. .
Examples of monomers having a nitrogen atom-containing ring include N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpiperidone, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N- Examples include vinyl morpholine, N-vinyl caprolactam, and N- (meth) acryloyl morpholine. As the monomer having a nitrogen atom-containing ring, N- (meth) acryloylmorpholine is preferable.
These monomers may be used independently and may be used in combination of 2 or more type.

In the present embodiment, a carboxyl group-containing monomer or a hydroxyl group-containing monomer is preferable as the second copolymer component, and acrylic acid is more preferable. When the acrylic copolymer includes a copolymer component derived from 2-ethylhexyl acrylate and a copolymer component derived from acrylic acid, the copolymer component derived from acrylic acid occupies the total mass of the acrylic copolymer. The mass ratio is preferably 1% by mass or less, and more preferably 0.1% by mass or more and 0.5% by mass or less. If the ratio of acrylic acid is 1 mass% or less, when an adhesive composition contains a crosslinking agent, crosslinking of the acrylic copolymer can be prevented from proceeding too quickly.

The acrylic copolymer may contain a copolymer component derived from two or more kinds of functional group-containing monomers. For example, the acrylic copolymer may be a ternary copolymer. When the acrylic copolymer is a ternary copolymer, an acrylic copolymer obtained by copolymerizing 2-ethylhexyl acrylate, a carboxyl group-containing monomer and a hydroxyl group-containing monomer is preferred, and this carboxyl group-containing monomer is preferred. Is preferably acrylic acid, and the hydroxyl group-containing monomer is preferably 2-hydroxyethyl acrylate. The ratio of the copolymer component derived from 2-ethylhexyl acrylate in the acrylic copolymer is 80% by mass or more and 95% by mass or less, and the ratio of the mass of the copolymer component derived from acrylic acid is 1% by mass or less. And the balance is preferably a copolymer component derived from 2-hydroxyethyl acrylate.

The weight average molecular weight (Mw) of the acrylic copolymer is preferably from 300,000 to 2,000,000, more preferably from 600,000 to 1,500,000, and more preferably from 800,000 to 1,200,000. preferable. If the weight average molecular weight Mw of the acrylic copolymer is 300,000 or more, the acrylic copolymer can be peeled without a residue of the pressure-sensitive adhesive on the adherend. When the weight average molecular weight Mw of the acrylic copolymer is 2 million or less, it can be reliably attached to the adherend.
The weight average molecular weight Mw of the acrylic copolymer is a standard polystyrene equivalent value measured by a gel permeation chromatography (GPC) method.

The acrylic copolymer can be produced according to a conventionally known method using the above-mentioned various raw material monomers.

The form of copolymerization of the acrylic copolymer is not particularly limited, and any of a block copolymer, a random copolymer, and a graft copolymer may be used.
In the present embodiment, the content of the acrylic copolymer in the pressure-sensitive adhesive composition is preferably 40% by mass or more and 90% by mass or less, and more preferably 50% by mass or more and 90% by mass or less.

The adhesion aid preferably contains a rubber-based material having a reactive group as a main component. If the pressure-sensitive adhesive composition contains a reactive pressure-sensitive adhesive aid, the adhesive residue can be reduced. The content of the adhesion assistant in the pressure-sensitive adhesive composition is preferably 3% by mass or more and 50% by mass or less, and more preferably 5% by mass or more and 30% by mass or less. If the content rate of the adhesion promoter in an adhesive composition is 3 mass% or more, generation | occurrence | production of adhesive residue can be suppressed, and if it is 50 mass% or less, the fall of adhesive force can be suppressed.
In the present specification, including a rubber-based material having a reactive group as a main component means that the proportion of the mass of the rubber-based material having a reactive group in the total mass of the adhesive aid exceeds 50% by mass. To do. In the present embodiment, the ratio of the rubber-based material having a reactive group in the adhesion assistant is preferably more than 50% by mass, and more preferably 80% by mass or more. It is also preferable that the adhesion assistant is made of a rubber-based material having a substantially reactive group.

The reactive group is preferably one or more functional groups selected from the group consisting of a hydroxyl group, an isocyanate group, an amino group, an oxirane group, an acid anhydride group, an alkoxy group, an acryloyl group, and a methacryloyl group. More preferably. The reactive group possessed by the rubber material may be one type or two or more types. The rubber-based material having a hydroxyl group may further have the aforementioned reactive group. In addition, the number of reactive groups may be one per molecule constituting the rubber-based material, or two or more.

The rubber-based material is not particularly limited, but a polybutadiene-based resin and a hydrogenated product of a polybutadiene-based resin are preferable, and a hydrogenated product of a polybutadiene-based resin is more preferable.
Examples of the polybutadiene-based resin include resins having 1,4-repeat units, resins having 1,2-repeat units, and resins having both 1,4-repeat units and 1,2-repeat units. The hydrogenated product of the polybutadiene resin of the present embodiment includes a hydride of a resin having these repeating units.

The polybutadiene resin and the hydrogenated product of the polybutadiene resin preferably have reactive groups at both ends. The reactive groups at both ends may be the same or different. The reactive groups at both ends are preferably one or more functional groups selected from the group consisting of a hydroxyl group, an isocyanate group, an amino group, an oxirane group, an acid anhydride group, an alkoxy group, an acryloyl group, and a methacryloyl group. More preferably, it is a hydroxyl group. In the polybutadiene resin and the hydrogenated product of the polybutadiene resin, it is more preferable that both ends are hydroxyl groups.

The pressure-sensitive adhesive composition according to the present embodiment preferably contains a cross-linked product obtained by cross-linking a composition containing a cross-linking agent in addition to the acrylic copolymer and the pressure-sensitive adhesive aid. Moreover, it is preferable that the solid content of the pressure-sensitive adhesive composition is substantially composed of a cross-linked product obtained by cross-linking the above-mentioned acrylic copolymer, a pressure-sensitive adhesive aid, and a cross-linking agent. Here, “substantially” means that the solid content of the pressure-sensitive adhesive composition is composed only of the cross-linked product, excluding trace amounts of impurities that are inevitably mixed in the pressure-sensitive adhesive.

In the present embodiment, examples of the crosslinking agent include an isocyanate crosslinking agent, an epoxy crosslinking agent, an aziridine crosslinking agent, a metal chelate crosslinking agent, an amine crosslinking agent, and an amino resin crosslinking agent. These cross-linking agents may be used alone or in combination of two or more.
In the present embodiment, from the viewpoint of improving the heat resistance and adhesive strength of the pressure-sensitive adhesive composition, among these crosslinking agents, a crosslinking agent (isocyanate-based crosslinking agent) containing a compound having an isocyanate group as a main component is preferable. Examples of the isocyanate crosslinking agent include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, diphenylmethane-4,4′-diisocyanate, Polyvalent isocyanates such as diphenylmethane-2,4'-diisocyanate, 3-methyldiphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, dicyclohexylmethane-2,4'-diisocyanate, and lysine isocyanate Compounds.
The polyisocyanate compound may be a trimethylolpropane adduct-type modified product, a burette-type modified product reacted with water, or an isocyanurate-type modified product having an isocyanurate ring.
In the present specification, the term “crosslinking agent whose main component is a compound having an isocyanate group” means that the proportion of the compound having an isocyanate group in the total mass of the components constituting the crosslinking agent is 50% by mass or more. To do.

In the present embodiment, the content of the crosslinking agent in the pressure-sensitive adhesive composition is preferably 0.1 parts by mass or more and 20 parts by mass or less, more preferably 1 part by mass or more with respect to 100 parts by mass of the acrylic copolymer. 15 parts by mass or less, more preferably 5 parts by mass or more and 10 parts by mass or less. If content of the crosslinking agent in an adhesive composition is in such a range, the adhesiveness of the layer (adhesive layer) containing an adhesive composition and a to-be-adhered body (for example, base material) will be improved. It is possible to shorten the curing period for stabilizing the adhesive property after the production of the adhesive sheet.

In the present embodiment, from the viewpoint of heat resistance of the pressure-sensitive adhesive composition, the isocyanate-based crosslinking agent is more preferably a compound having an isocyanurate ring (isocyanurate-type modified product). The compound having an isocyanurate ring is preferably blended in an amount of 0.7 to 1.5 equivalents relative to the hydroxyl equivalent of the acrylic copolymer. If the compounding quantity of the compound which has an isocyanurate ring is 0.7 equivalent or more, adhesive force will not become high too high after a heating, it will become easy to peel the adhesive sheet 10, and adhesive residue can be reduced. If the compounding quantity of the compound which has an isocyanurate ring is 1.5 equivalent or less, it can prevent that an initial stage adhesive force becomes low too much, or can prevent a sticking fall.

When the pressure-sensitive adhesive composition in this embodiment contains a crosslinking agent, the pressure-sensitive adhesive composition preferably further contains a crosslinking accelerator. The crosslinking accelerator is preferably selected and used as appropriate according to the type of the crosslinking agent. For example, when the pressure-sensitive adhesive composition contains a polyisocyanate compound as a crosslinking agent, it is preferable to further contain an organic metal compound-based crosslinking accelerator such as an organic tin compound.

-Silicone-type adhesive composition When an adhesive layer contains a silicone-type adhesive composition, it is preferable that a silicone-type adhesive composition contains an addition polymerization type silicone resin. In the present specification, a silicone pressure-sensitive adhesive composition containing an addition polymerization type silicone resin is referred to as an addition reaction type silicone pressure-sensitive adhesive composition.

The addition reaction type silicone pressure-sensitive adhesive composition contains a main agent and a crosslinking agent. The addition reaction type silicone pressure-sensitive adhesive composition can be used only by primary curing at a low temperature, and has an advantage that secondary curing at a high temperature is not required. Incidentally, the conventional peroxide-curing silicone pressure-sensitive adhesive requires secondary curing at a high temperature such as 150 ° C. or higher.
Therefore, by using an addition reaction type silicone pressure-sensitive adhesive composition, it becomes possible to produce a pressure-sensitive adhesive sheet at a relatively low temperature, using a base material having excellent energy economy and relatively low heat resistance. It is also possible to produce an adhesive sheet. Further, since no by-product is produced during curing unlike the peroxide-curing silicone pressure-sensitive adhesive, there are no problems such as odor and corrosion.

The addition reaction type silicone pressure-sensitive adhesive composition is usually composed of a main agent composed of a mixture of a silicone resin component and a silicone rubber component, a hydrosilyl group (SiH group) -containing crosslinking agent, and a curing catalyst used as necessary. Become.
The silicone resin component is an organopolysiloxane having a network structure obtained by hydrolyzing organochlorosilane or organoalkoxysilane and then performing a dehydration condensation reaction.
The silicone rubber component is a diorganopolysiloxane having a linear structure.
Examples of the organo group in the silicone resin component and the silicone rubber component include a methyl group, an ethyl group, a propyl group, a butyl group, and a phenyl group. The aforementioned organo groups are partially vinyl, hexenyl, allyl, butenyl, pentenyl, octenyl, (meth) acryloyl, (meth) acryloylmethyl, (meth) acryloylpropyl, and cyclohexenyl. It may be substituted with an unsaturated group such as a group. An organo group having a vinyl group that is easily available industrially is preferred. In the addition-reaction type silicone pressure-sensitive adhesive composition, crosslinking proceeds by an addition reaction between an unsaturated group and a hydrosilyl group to form a network structure, thereby exhibiting adhesiveness.
The number of unsaturated groups such as vinyl groups is usually 0.05 or more and 3.0 or less, preferably 0.1 or more and 2.5 or less, per 100 organo groups. By setting the number of unsaturated groups to 100 or more organo groups to 0.05 or more, it is possible to prevent the reactivity with the hydrosilyl group from being lowered and difficult to cure, and to impart an appropriate adhesive force. . By setting the number of unsaturated groups per 100 organo groups to 3.0 or less, the crosslinking density of the pressure-sensitive adhesive is increased, and the adhesive force and cohesive force are increased, thereby preventing adverse effects on the adherend surface.

Specific examples of the organopolysiloxane described above include KS-3703 manufactured by Shin-Etsu Chemical Co., Ltd. (the number of vinyl groups is 0.6 with respect to 100 methyl groups), Toray Dow Corning BY23-753 manufactured by the company (the number of vinyl groups is 0.1 per 100 methyl groups) and BY24-162 (the number of vinyl groups is 1.4 per 100 methyl groups) )). In addition, SD4560PSA, SD4570PSA, SD4580PSA, SD4584PSA, SD4585PSA, SD4587L, and SD4592PSA manufactured by Toray Dow Corning can also be used.
As described above, organopolysiloxane, which is a silicone resin component, is usually used in a mixture with a silicone rubber component. As the silicone rubber component, KS-3800 (manufactured by Shin-Etsu Chemical Co., Ltd.) 7.6 for 100 methyl groups), BY24-162 made by Toray Dow Corning (number of vinyl groups is 1.4 for 100 methyl groups), BY24- 843 (having no unsaturated group) and SD-7292 (the number of vinyl groups is 5.0 with respect to 100 methyl groups).
Specific examples of the addition reaction type silicone as described above are described, for example, in JP-A-10-219229.

The crosslinking agent is usually 0.5 to 10 hydrogen atoms bonded to silicon atoms, preferably 1 or more to one unsaturated group such as a vinyl group of the silicone resin component and the silicone rubber component. It mix | blends so that it may become 2.5 or less. By setting the number to 0.5 or more, the reaction between the unsaturated group such as a vinyl group and the hydrosilyl group does not proceed completely, thereby preventing poor curing. By setting the number to 10 or less, it is possible to prevent the crosslinking agent from remaining unreacted and adversely affecting the adherend surface.

The addition reaction type silicone pressure-sensitive adhesive composition preferably contains a curing catalyst together with the above addition reaction type silicone component (main agent comprising a silicone resin component and a silicone rubber component) and a crosslinking agent.
This curing catalyst is used to accelerate the hydrosilylation reaction between the unsaturated group in the silicone resin component and the silicone rubber component and the Si—H group in the crosslinking agent.
As a curing catalyst, platinum-based catalysts, that is, chloroplatinic acid, an alcohol solution of chloroplatinic acid, a reaction product of chloroplatinic acid and an alcohol solution, a reaction product of chloroplatinic acid and an olefin compound, chloroplatinic acid and vinyl Examples thereof include a reaction product with a group-containing siloxane compound, a platinum-olefin complex, a platinum-vinyl group-containing siloxane complex, and a platinum-phosphorus complex. Specific examples of the curing catalyst as described above are described in, for example, JP-A-2006-28311 and JP-A-10-147758.
More specifically, commercially available products include SRX-212 manufactured by Toray Dow Corning, and PL-50T manufactured by Shin-Etsu Chemical Co., Ltd.

The blending amount of the curing catalyst is usually 5 mass ppm or more and 2000 mass ppm or less, preferably 10 mass ppm or more and 500 mass ppm or less with respect to the total amount of the silicone resin component and the silicone rubber component as platinum content. By setting the content to 5 mass ppm or more, curability is lowered and the crosslinking density is reduced, that is, the adhesive force and the cohesive force (holding force) are prevented from being reduced. While preventing, the stability of an adhesive layer can be hold | maintained, and it prevents that the curing catalyst used excessively has a bad influence on a to-be-adhered surface.

In the addition reaction type silicone pressure-sensitive adhesive composition, an adhesive force is exhibited even at room temperature (25 ° C.) by blending the above-mentioned components, but the addition reaction type silicone pressure-sensitive adhesive composition will be described later on the substrate 11 or later. Applying to a release sheet, bonding the substrate and release sheet, and then heating or irradiating active energy rays to promote the crosslinking reaction of the silicone resin component and the silicone rubber component by the crosslinking agent, stability of adhesive strength From the viewpoint of

When the crosslinking reaction is accelerated by heating, the heating temperature is usually 60 ° C. or higher and 140 ° C. or lower, preferably 80 ° C. or higher and 130 ° C. or lower. Heating at 60 ° C. or higher prevents insufficient crosslinking between the silicone resin component and the silicone rubber component and prevents the adhesive force from becoming insufficient. Heating at 140 ° C. or lower causes thermal shrinkage and wrinkles on the substrate. , Deterioration or discoloration can be prevented.

When the active energy ray is irradiated to promote the crosslinking reaction, an active energy ray having energy quanta in an electromagnetic wave or a charged particle beam, that is, an active light such as an ultraviolet ray or an electron beam can be used. In the case of crosslinking by irradiation with an electron beam, a photopolymerization initiator is not required. However, in the case of crosslinking by irradiation with active light such as ultraviolet rays, it is preferable that a photopolymerization initiator is present.
The photopolymerization initiator in the case of ultraviolet irradiation is not particularly limited, and any photopolymerization initiator that has been conventionally used in ultraviolet curable resins can be appropriately selected and used. it can. Examples of the photopolymerization initiator include benzoins, benzophenones, acetophenones, α-hydroxy ketones, α-amino ketones, α-diketones, α-diketone dialkyl acetals, anthraquinones, thioxanthones, and others. Compounds and the like.
These photopolymerization initiators may be used alone or in combination of two or more. The amount used is usually 0.01 parts by mass or more and 30 parts by mass or less, preferably 0.05 parts by mass with respect to 100 parts by mass of the total amount of the addition reaction type silicone component and the crosslinking agent used as the main agent. It is selected in the range of 20 parts by mass or less.
A pressure-sensitive adhesive sheet having stable adhesive strength can be obtained by crosslinking by irradiation with heat or active energy rays.

The acceleration voltage of an electron beam in the case of crosslinking by irradiating with an electron beam which is one of active energy rays is generally 130 kV to 300 kV, preferably 150 kV to 250 kV. Irradiation at an acceleration voltage of 130 kV or more can prevent the silicone resin component and the silicone rubber component from being insufficiently crosslinked and prevent the adhesive force from becoming insufficient. It is possible to prevent the layer 12 and the substrate 11 from being deteriorated or discolored. A preferable range of the beam current is 1 mA or more and 100 mA or less.
The dose of the irradiated electron beam is preferably 1 Mrad or more and 70 Mrad or less, and more preferably 2 Mrad or more and 20 Mrad or less. By irradiating with a dose of 1 Mrad or more, it is possible to prevent the pressure-sensitive adhesive layer and the base material from being deteriorated or discolored, and to prevent the adhesiveness from being insufficient due to insufficient crosslinking. By irradiating with a dose of 70 Mrad or less, it is possible to prevent the cohesive force from being lowered due to deterioration or discoloration of the pressure-sensitive adhesive layer, and it is possible to prevent the base material from being deteriorated or contracted.
The irradiation amount in the case of ultraviolet irradiation is appropriately selected. The light amount is from 100 mJ / cm ^{2 to} 500 mJ / cm ² and the illuminance is from 10 mW / cm ^{2 to} 500 mW / cm ² .
Heating and irradiation with active energy rays are preferably performed in a nitrogen atmosphere in order to prevent reaction inhibition by oxygen.

-Thickness of an adhesive layer The thickness of an adhesive layer is suitably determined according to the use of an adhesive sheet. In the present embodiment, the thickness of the pressure-sensitive adhesive layer is preferably 5 μm or more and 60 μm or less, and more preferably 10 μm or more and 50 μm or less.
When the thickness of the pressure-sensitive adhesive layer is 5 μm or more, for example, the pressure-sensitive adhesive layer easily follows unevenness on the circuit surface of the semiconductor chip. Thereby, since it becomes difficult to produce a clearance gap between an adhesive layer and a semiconductor chip, it is suppressed that an interlayer insulation material, sealing resin, etc. enter into the clearance gap, for example. As a result, the electrode pad for wiring connection on the chip circuit surface is prevented from being blocked.
When the thickness of the pressure-sensitive adhesive layer is 60 μm or less, for example, the semiconductor chip is suppressed from sinking into the pressure-sensitive adhesive layer. Accordingly, a step between the semiconductor chip portion and the resin portion for sealing the semiconductor chip is less likely to occur, and as a result, disconnection of the wiring during rewiring is suppressed.

-Other component In this embodiment, the adhesive composition may contain the other component in the range which does not impair the effect of this invention. Examples of other components that can be included in the pressure-sensitive adhesive composition include flame retardants, tackifiers, ultraviolet absorbers, light stabilizers, antioxidants, antiseptics, antifungal agents, plasticizers, antifoaming agents, and coloring. Agents, fillers, wettability adjusting agents and the like.
The addition reaction type silicone pressure-sensitive adhesive composition may contain non-reactive polyorganosiloxanes such as polydimethylsiloxane and polymethylphenylsiloxane as additives.

[Method for producing adhesive sheet]
As a manufacturing method of an adhesive sheet, for example, a method of applying an adhesive composition on the first substrate surface of a substrate to form an adhesive layer, on the first substrate surface of the substrate, if necessary Then, an intermediate layer or a conductive layer was formed by applying a composition for forming an intermediate layer or a conductive layer (for example, an oligomer sealing layer composition, a primer layer forming composition, a conductive layer forming composition, etc.). Then, the method of apply | coating an adhesive composition and forming an adhesive layer etc. are mentioned.
As a method for producing a pressure-sensitive adhesive sheet having a release sheet, for example, a pressure-sensitive adhesive layer is formed on a release sheet to be described later, and the pressure-sensitive adhesive layer on the release sheet and the oligomer sealing layer formed on the substrate Or the method of bonding the said conductive layer is mentioned.
The detail about the manufacturing method of the adhesive sheet which has a peeling sheet is mentioned later.

When the pressure-sensitive adhesive composition is applied to form a pressure-sensitive adhesive layer, it is preferable to dilute the pressure-sensitive adhesive composition with an organic solvent to prepare and use a coating solution. The same applies when the intermediate layer and the conductive layer are formed.
It does not specifically limit as an organic solvent used for preparation of a coating liquid. Examples of the organic solvent include aromatic solvents, aliphatic solvents, ester solvents, ketone solvents, and alcohol solvents. Examples of the aromatic solvent include benzene, toluene, and xylene. Examples of the aliphatic solvent include normal hexane and normal heptane. Examples of the ester solvent include ethyl acetate and butyl acetate. Examples of the ketone solvent include methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and cyclopentanone. Examples of the alcohol solvent include isopropyl alcohol and methanol.
Examples of the coating method include spin coating, spray coating, bar coating, knife coating, roll knife coating, roll coating, blade coating, die coating, and gravure coating.
In order to prevent the organic solvent and the low boiling point component from remaining in the pressure-sensitive adhesive layer, the intermediate layer, and the conductive layer, it is preferable to apply the coating liquid to, for example, a substrate and then heat and dry the coating film.

[Second Embodiment]
The pressure-sensitive adhesive sheet according to the second embodiment is different from the pressure-sensitive adhesive sheet according to the first embodiment in that a conductive layer is provided between the base material and the pressure-sensitive adhesive layer. Since the other points are the same as those of the first embodiment, the description is omitted or simplified.
That is, the pressure-sensitive adhesive sheet according to the second embodiment is a pressure-sensitive adhesive sheet having a base material, a conductive layer, and a pressure-sensitive adhesive layer in this order.

<Conductive layer>
The conductive layer is a layer containing a conductive material. The conductive layer is preferably formed from a resin composition containing a conductive material.
Although it does not specifically limit as a conductive material, For example, the material (carbon material, ionic material (ionic liquid, ionic polymer), metal microparticles, metal oxide, metal filler, and surfactant illustrated in the item of antistatic agent ), Compounds having an ionic functional group, and alloys. The conductive material may be a conductive polymer.

When the conductive material is a conductive polymer, the conductive layer is formed from a resin composition containing a conductive polymer (hereinafter also referred to as “conductive layer forming composition”).
The resin contained in the conductive layer forming composition preferably contains at least one selected from the group consisting of a polyester resin, a urethane resin and an acrylic resin (hereinafter referred to as “specific resin”) as a main component.
The main component means that the ratio of the total mass of the specific resin to the total mass of the resin contained in the conductive layer forming composition is 50% by mass or more.

As the resin contained in the composition for forming a conductive layer, one type may be used alone, or two different types may be used in combination. In particular, when the substrate is made of a polyester-based material, it is preferable that a polyester resin and a polyurethane resin are contained as the main component constituting the conductive layer from the viewpoint of adhesion to the substrate. In the case where the resin contained in the composition for forming a conductive layer is a polyester resin alone, the adhesiveness with the polyester base material is sufficient, but since it is a relatively brittle resin, it tends to cause cohesive failure during cutting, If the resin contained in the composition for forming a conductive layer is a single polyurethane resin, the adhesiveness with a polyester base material is poor. By containing a copolymerized polyester resin and a polyurethane resin as described above, a resin layer that solves these problems, has excellent adhesion to a polyester-based substrate, and is difficult to break even during cutting is obtained. “Containing a polyester resin and a polyurethane resin” also means that a polymer containing a polyester structure and a polyurethane structure in one molecule is included alone.

(Conductive polymer)
Examples of the conductive polymer include polythiophene-based, polyaniline-based, and polypyrrole-based conductive polymers.

Examples of the polythiophene-based conductive polymer include polythiophene, poly (3-alkylthiophene), poly (3-thiophene-β-ethanesulfonic acid), a mixture of polyalkylenedioxythiophene and polystyrene sulfonate, and the like. . Examples of the polyalkylene dioxythiophene include polyethylene dioxythiophene, polypropylene dioxythiophene, poly (ethylene / propylene) dioxythiophene, and the like.
Examples of the polyaniline-based conductive polymer include polyaniline, polymethylaniline, polymethoxyaniline, and the like.
Examples of the polypyrrole-based conductive polymer include polypyrrole, poly-3-methylpyrrole, and poly-3-octylpyrrole. These conductive polymer compounds may be used alone or in combination of two or more. These conductive polymers are preferably used in the form of an aqueous solution dispersed in water.

The content of the conductive polymer in the conductive layer is preferably from 0.1% by mass to 50% by mass in terms of solid content, and more preferably from 0.3% by mass to 30% by mass.
When the content of the conductive polymer is 0.1% by mass or more, antistatic performance is easily exhibited.
When the content of the conductive polymer is 50% by mass or less, the strength of the conductive layer is increased, the cohesive failure is less likely to occur, and the adhesiveness of the pressure-sensitive adhesive layer is easily secured.

The thickness of the conductive layer is 30 nm or more and 290 nm or less, and preferably 30 nm or more and 250 nm or less.
When the thickness of the conductive layer is 30 nm or more, the film-forming property on the surface of the substrate is good, and pinholes due to repellence are less likely to occur.
When the thickness of the conductive layer is 290 nm or less, the cohesive failure of the conductive layer is less likely to occur, and the adhesiveness of the pressure-sensitive adhesive layer is easily ensured.

In order to form the conductive layer, the composition for forming a conductive layer may be applied to the surface of the substrate on the side of the pressure-sensitive adhesive layer (in the case of FIG. 2, the first substrate surface 11c) and then dried.
Examples of the coating method include the coating methods described in the section of the method for producing the pressure-sensitive adhesive sheet.
The composition for forming a conductive layer may contain an organic solvent capable of dissolving or dispersing each component in the composition for forming a conductive layer. As the organic solvent, ether solvents, alcohol solvents, mixed solvents of alcohol solvents and purified water, and the like are preferable.

FIG. 2 shows a cross-sectional view of the pressure-sensitive adhesive sheet 10A according to the second embodiment.
The pressure-sensitive adhesive sheet 10A has a conductive layer 13 between the base material 11A and the pressure-sensitive adhesive layer 12A. That is, the pressure-sensitive adhesive sheet 10A has a base material 11A, a conductive layer 13 containing a conductive material, and a pressure-sensitive adhesive layer 12A in this order.
The substrate 11A has a first substrate surface 11c and a second substrate surface 11d opposite to the first substrate surface 11c. The pressure-sensitive adhesive layer 12A has a first pressure-sensitive adhesive surface 12c and a second pressure-sensitive adhesive surface 12d opposite to the first pressure-sensitive adhesive surface 12c.
In the adhesive sheet 10A, the conductive layer 13 is laminated on the first base material surface 11c.
In the pressure-sensitive adhesive sheet 10A, the surface resistivity of the first pressure-sensitive adhesive surface 12c of the pressure-sensitive adhesive layer 12A after high-temperature heating is less than 10 ¹¹ Ω / □.
According to the pressure-sensitive adhesive sheet 10A of the second embodiment, since the conductive layer 13 is provided between the base material 11A and the pressure-sensitive adhesive layer 12A, the antistatic performance of the first pressure-sensitive adhesive surface 12c of the pressure-sensitive adhesive layer 12A after high-temperature heating. Is thought to improve.
Therefore, according to the second embodiment, the electrostatic breakdown of the semiconductor element can be further suppressed even if the pressure-sensitive adhesive sheet 10A is peeled off from the adherend after the process of being heated at a high temperature.

[Third embodiment]
The pressure-sensitive adhesive sheet according to the third embodiment is different from the pressure-sensitive adhesive sheet according to the second embodiment in that an intermediate layer is included between the base material and the conductive layer. Since the other points are the same as those of the second embodiment, the description is omitted or simplified.
That is, the pressure-sensitive adhesive sheet according to the third embodiment is a pressure-sensitive adhesive sheet having a base material, an intermediate layer, a conductive layer, and a pressure-sensitive adhesive layer in this order.

<Intermediate layer>
The intermediate layer is provided between the base material and the conductive layer. The intermediate layer preferably has a function corresponding to a desired purpose. Examples of the intermediate layer include an oligomer sealing layer, a primer layer, and a hard coat layer. For example, by providing an intermediate layer (for example, an oligomer sealing layer, a primer layer, and a hard coat layer), adhesion between the substrate and the conductive layer, suppression of oligomer precipitation on the substrate surface, and heating step At least one of the substrate thermal shrinkage can be improved.

Here, the oligomer sealing layer is a layer for preventing the oligomer from entering the pressure-sensitive adhesive layer and the conductive layer in the third embodiment. When the pressure-sensitive adhesive sheet is exposed to high temperature conditions, oligomers contained in the substrate may be deposited on the surface of the substrate by heating. For this reason, when an adhesive sheet has an oligomer sealing layer, the penetration | invasion to the adhesive layer and conductive layer of the oligomer contained in a base material can be suppressed. Thereby, since it can suppress that an oligomer component moves from a base material, peeling arises in the interface of an adhesive layer and a conductive layer, or an adhesive sheet becomes more difficult to peel from an adherend.
The oligomer sealing layer preferably prevents the oligomer from entering the pressure-sensitive adhesive layer even under high temperature conditions of 180 ° C. or higher and 200 ° C. or lower.

Hereinafter, the oligomer sealing layer will be described.

(Oligomer sealing layer)
The material of the oligomer sealing layer is not particularly limited as long as the oligomer in the base material can be prevented from entering the pressure-sensitive adhesive layer and the conductive layer.
For example, the oligomer sealing layer is preferably a cured film obtained by curing the composition for the oligomer sealing layer. The composition for the oligomer sealing layer preferably contains, for example, at least one selected from the group consisting of (A) an epoxy compound, (B) a polyester compound, and (C) a polyfunctional amino compound. It is more preferable that a compound, (B) polyester compound, and (C) polyfunctional amino compound are included.
The composition for oligomer sealing layer may further contain (D) an acidic catalyst in order to promote the curing reaction.

-(A) Epoxy Compound (A) The epoxy compound is preferably a bisphenol A type epoxy compound. Examples of the bisphenol A type epoxy compound include bisphenol A diglycidyl ether.

-(B) Polyester compound (B) It does not specifically limit as a polyester compound, It can select from a well-known polyester compound suitably, and can be used. Specifically, the polyester compound is a resin obtained by a condensation reaction between a polyhydric alcohol and a polybasic acid, and is a compound modified with a condensate of a dibasic acid and a dihydric alcohol or a non-drying oil fatty acid. And a convertible polyester compound that is a condensate of a dibasic acid and a trivalent or higher alcohol.

(B) As the polyhydric alcohol and polybasic acid used as a raw material for the polyester compound, known polyhydric alcohols and polybasic acids can be appropriately selected and used.

-(C) Polyfunctional amino compound (C) As a polyfunctional amino compound, a melamine compound, a urea compound, a benzoguanamine compound, and diamine can be used, for example.
Examples of melamine compounds include hexamethoxymethyl melamine, methylated melamine compounds, and butylated melamine compounds.
Examples of the urea compound include a methylated urea compound and a butylated urea compound.
Examples of the benzoguanamine compound include a methylated benzoguanamine compound and a butylated benzoguanamine compound.
Examples of diamines include ethylenediamine, tetramethylenediamine, hexamethylenediamine, N, N′-diphenylethylenediamine, and p-xylylenediamine.
From the viewpoint of curability, the (C) polyfunctional amino compound is preferably hexamethoxymethylmelamine.

-(D) Acidic catalyst Examples of the acidic catalyst (D) include hydrochloric acid and p-toluenesulfonic acid.

-Cured film In this embodiment, the oligomer sealing layer comprises (A) 50 mass% or more and 80 mass% of (A) bisphenol A type epoxy compound, (B) polyester compound, and (C) polyfunctional amino compound, respectively. % Or less, (B) 5% by mass or more and 30% by mass or less, and (C) a cured film obtained by curing an oligomer sealing layer composition containing 10% by mass or more and 40% by mass or less. . (D) When mix | blending an acidic catalyst with the composition for oligomer sealing layers, it is preferable that content of (D) component shall be 1 mass% or more and 5 mass% or less.
According to the cured film obtained by curing the composition for the oligomer sealing layer having the blending ratio in the above range, the effect of preventing the oligomer from entering the pressure-sensitive adhesive layer by the oligomer sealing layer can be improved.

-Film thickness of the intermediate layer The thickness of the intermediate layer is preferably 50 nm or more and 500 nm or less, and more preferably 80 nm or more and 300 nm or less.
If the thickness of the intermediate layer is 50 nm or more, good adhesion between the substrate and the conductive layer can be easily obtained.
In 3rd embodiment, when an intermediate | middle layer is an oligomer sealing layer especially, the penetration | invasion to the adhesive layer and conductive layer of the oligomer contained in a base material can be prevented effectively.
When the thickness of the intermediate layer is 500 nm or less, for example, when the pressure-sensitive adhesive sheet is wound around the core material in a roll shape, the intermediate layer is easily wound. Examples of the material of the core material include paper, plastic, and metal.

FIG. 3 shows a cross-sectional view of the pressure-sensitive adhesive sheet 10B according to the third embodiment. Between the base material 11B and the conductive layer 13A, an oligomer sealing layer 14 is provided as an intermediate layer.
That is, the pressure-sensitive adhesive sheet 10B has a base material 11B, an oligomer sealing layer 14, a conductive layer 13A, and a pressure-sensitive adhesive layer 12B in this order.
The base material 11B has a first base material surface 11e and a second base material surface 11f opposite to the first base material surface 11e. The pressure-sensitive adhesive layer 12B has a first pressure-sensitive adhesive surface 12e and a second pressure-sensitive adhesive surface 12f opposite to the first pressure-sensitive adhesive surface 12e. In the pressure-sensitive adhesive sheet 10B, the oligomer sealing layer 14 is stacked on the first base material surface 11e, and the conductive layer 13A and the pressure-sensitive adhesive layer 12B are stacked on the oligomer sealing layer 14 in this order.
In the pressure-sensitive adhesive sheet 10B, the surface resistivity of the first pressure-sensitive adhesive surface 12e of the pressure-sensitive adhesive layer 12B after high-temperature heating is less than 10 ¹¹ Ω / □.
According to the pressure-sensitive adhesive sheet 10B of the third embodiment, the antistatic performance on the first pressure-sensitive adhesive surface 12e of the pressure-sensitive adhesive layer 12B is considered to be improved because it has the conductive layer 13A as in the second embodiment.
Therefore, according to 3rd embodiment, even if it peels off the adhesive sheet 10B from a to-be-adhered body after passing through the process heated at high temperature, the electrostatic breakdown of a semiconductor element can be suppressed more.
Furthermore, according to the pressure-sensitive adhesive sheet 10B of the third embodiment, since the oligomer sealing layer 14 is provided between the base material 11B and the conductive layer 13A, the oligomer pressure-sensitive adhesive layer 12B and the conductive layer contained in the base material 11B. Intrusion into 13A can also be prevented.

[Fourth embodiment]
The pressure-sensitive adhesive sheet according to the fourth embodiment is different from the pressure-sensitive adhesive sheet according to the second embodiment in that an intermediate layer is included instead of the conductive layer between the base material and the pressure-sensitive adhesive layer. Since the other points are the same as those of the second embodiment, the description is omitted or simplified.

FIG. 4 shows a cross-sectional view of the pressure-sensitive adhesive sheet 10C according to the fourth embodiment. Between the base material 11C and the pressure-sensitive adhesive layer 12C, an oligomer sealing layer 14A is provided as an intermediate layer.
That is, the pressure-sensitive adhesive sheet 10C has a base material 11C, an oligomer sealing layer 14A, and a pressure-sensitive adhesive layer 12C in this order.
Here, the oligomer sealing layer 14 </ b> A is a layer for preventing the oligomer from entering the pressure-sensitive adhesive layer in the fourth embodiment.
The substrate 11C has a first substrate surface 11g and a second substrate surface 11h opposite to the first substrate surface 11g. The pressure-sensitive adhesive layer 12C has a first pressure-sensitive adhesive surface 12g and a second pressure-sensitive adhesive surface 12h opposite to the first pressure-sensitive adhesive surface 12g. In the pressure-sensitive adhesive sheet 10C, an oligomer sealing layer 14A is laminated on the first base material surface 11g.
In the pressure-sensitive adhesive sheet 10C, the surface resistivity of the first pressure-sensitive adhesive surface 12g of the pressure-sensitive adhesive layer 12C after high-temperature heating is less than 10 ¹¹ Ω / □.
Therefore, according to the fourth embodiment, electrostatic breakdown of the semiconductor element can be further suppressed even if the pressure-sensitive adhesive sheet 10C is peeled off from the adherend after the process of being heated at a high temperature.
Furthermore, according to the pressure-sensitive adhesive sheet 10C of the fourth embodiment, since the oligomer sealing layer 14A is provided between the base material 11C and the pressure-sensitive adhesive layer 12C, the oligomer contained in the base material 11C is applied to the pressure-sensitive adhesive layer 12C. Intrusion can also be prevented. Thereby, 10 C of adhesive sheets become difficult to peel from a to-be-adhered body.

[Fifth embodiment]
The pressure-sensitive adhesive sheet according to the fifth embodiment is the fourth embodiment in that it further includes a conductive layer on the side of the base material between the base material and the pressure-sensitive adhesive layer, and the intermediate layer is a primer layer. It is different from the adhesive sheet according to the form. Since other points are the same as those of the fourth embodiment, description thereof is omitted or simplified.

FIG. 5 shows a cross-sectional view of an adhesive sheet 10D according to the fifth embodiment.
The pressure-sensitive adhesive sheet 10D includes a base material 11D, a conductive layer 13B, a primer layer 14B, and a pressure-sensitive adhesive layer 12D in this order.
The substrate 11D has a first substrate surface 11i and a second substrate surface 11j opposite to the first substrate surface 11i. The pressure-sensitive adhesive layer 12D has a first pressure-sensitive adhesive surface 12i and a second pressure-sensitive adhesive surface 12j opposite to the first pressure-sensitive adhesive surface 12i. In the adhesive sheet 10D, the conductive layer 13B is laminated on the first base material surface 11i.
In the pressure-sensitive adhesive sheet 10D, the surface resistivity of the first pressure-sensitive adhesive surface 12i of the pressure-sensitive adhesive layer 12D after high-temperature heating is less than 10 ¹¹ Ω / □.
Therefore, according to the fifth embodiment, the electrostatic breakdown of the semiconductor element can be further suppressed even if the pressure-sensitive adhesive sheet 10D is peeled off from the adherend after the process of being heated at a high temperature.
Furthermore, according to the pressure-sensitive adhesive sheet 10D of the fifth embodiment, since the primer layer 14B is provided between the pressure-sensitive adhesive layer 12D and the conductive layer 13B, the adhesion between the pressure-sensitive adhesive layer 12D and the conductive layer 13B can be improved. it can. Thereby, it becomes easy to suppress the adhesive residue to the to-be-adhered body after peeling an adhesive sheet.

[Sixth embodiment]
<Use of adhesive sheet>
The adhesive sheet of the said embodiment (any one of 5th embodiment from 1st embodiment) is used when sealing a semiconductor element. The pressure-sensitive adhesive sheet is not mounted on a metal lead frame, and is preferably used when sealing a semiconductor element stuck on the pressure-sensitive adhesive sheet. Specifically, the pressure-sensitive adhesive sheet of the above embodiment is not used when sealing a semiconductor element mounted on a metal lead frame, but seals the semiconductor element in a state of being adhered to an adhesive layer. It is preferably used when stopping. As a form of packaging a semiconductor element without using a metal lead frame, a panel scale package (Panel Scale Package; PSP) and a wafer level package (Wafer Level Package; WLP) can be cited.
The pressure-sensitive adhesive sheet attaches a semiconductor chip (an example of a semiconductor element) to the pressure-sensitive adhesive layer exposed at the step of attaching the frame member formed with a plurality of openings to the pressure-sensitive adhesive sheet and the opening of the frame member. It is preferably used in a process having a step, a step of covering the semiconductor chip with a sealing resin, and a step of thermosetting the sealing resin.

[Modification of Embodiment]
The present invention is not limited to the above-described embodiment, and modifications and improvements as long as the object of the present invention can be achieved are included in the present invention. In the following description, if it is the same as the member described in the above embodiment, the same reference numeral is given and the description is omitted or simplified.

The adhesive sheet may be a single sheet or may be provided in a state where a plurality of adhesive sheets are laminated.
The adhesive sheet may be a long sheet or may be provided in a state of being wound in a roll. The pressure-sensitive adhesive sheet wound up in a roll shape can be used by being unwound from a roll and cut into a desired size.

The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet may be covered with a release sheet. The release sheet is not particularly limited. For example, from the viewpoint of ease of handling, the release sheet preferably includes a release substrate and a release agent layer formed by applying a release agent on the release substrate. Moreover, the release sheet may be provided with a release agent layer only on one side of the release substrate, or may be provided with a release agent layer on both sides of the release substrate. Examples of the release substrate include a paper substrate, a laminated paper obtained by laminating a thermoplastic resin such as polyethylene on the paper substrate, and a plastic film. Examples of the paper substrate include glassine paper, coated paper, and cast coated paper. Examples of the plastic film include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, and polyolefin films such as polypropylene and polyethylene. Examples of the release agent include olefin resins, rubber elastomers (eg, butadiene resins, isoprene resins, etc.), long chain alkyl resins, alkyd resins, fluorine resins, and silicone resins.
In addition, the sheet | seat in this specification is the concept including not only what is generally called a sheet | seat but what is generally called a film | membrane.

The thickness of the release sheet is not particularly limited. The thickness of the release sheet is usually 20 μm or more and 200 μm or less, and preferably 25 μm or more and 150 μm or less.
The thickness of the release agent layer is not particularly limited. When a release agent layer is formed by applying a solution containing a release agent, the thickness of the release agent layer is preferably 0.01 μm or more and 2.0 μm or less, and 0.03 μm or more and 1.0 μm or less. Is more preferable.
When a plastic film is used as the release substrate, the thickness of the plastic film is preferably 3 μm or more and 50 μm or less, and more preferably 5 μm or more and 40 μm or less.

The pressure-sensitive adhesive sheet having a release sheet is produced, for example, through the following steps.
First, a pressure-sensitive adhesive composition is applied on a release sheet to form a coating film. Next, the coating film is dried to form an adhesive layer. Next, the adhesive layer on the release sheet and the substrate are bonded together.
In the case where the pressure-sensitive adhesive sheet has an oligomer sealing layer as an intermediate layer, for example, an oligomer sealing layer is formed on the first base material surface of the base material. Next, the pressure-sensitive adhesive layer on the release sheet and the oligomer sealing layer on the substrate are bonded together.
Even when the pressure-sensitive adhesive sheet has a conductive layer, after the conductive layer is formed on the first base material surface of the base material or the oligomer sealing layer in the same manner, the pressure-sensitive adhesive layer on the release sheet and the base material The conductive layer is attached.

In the above embodiment, the case where the material of the sealing resin is a thermosetting resin has been described as an example, but the present invention is not limited to such a mode.

Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited to these examples.

[Preparation of adhesive sheet]
(Example 1)
(1) Preparation of oligomer sealing agent liquid for coating The following (A) bisphenol A type epoxy compound, (B) polyester compound, (C) polyfunctional amino compound, and (D) acidic catalyst are blended and stirred sufficiently. Thus, an oligomer sealing agent liquid for coating (composition for oligomer sealing layer) was prepared.

(A) Bisphenol A type epoxy compound “EPICLON H-360” (trade name) manufactured by DIC, solid content concentration: 40 mass%, weight average molecular weight: 25000
(B) Polyester compound “Byron GK680” (trade name) manufactured by Toyobo Co., Ltd., number average molecular weight: 6000, glass transition temperature: 10 ° C.
(C) Polyfunctional amino compound Hexamethoxymethylmelamine, “Cymel 303” (trade name) manufactured by Nippon Cytec Industries, Ltd.
(D) Methanol solution of p-toluenesulfonic acid (solid content concentration 50% by mass)

Specifically, 100 parts by mass of the (A) bisphenol A type epoxy compound, 14.29 parts by mass of a toluene diluted solution of the (B) polyester compound (solid content concentration: 30%), and the above (C) hexamethoxy 11.4 parts by mass of methylmelamine was added, and the mixture was further diluted with a mixed solvent of toluene / methyl ethyl ketone = 50% by mass / 50% by mass so that the solid content became 3% by mass and stirred. 2.9 parts by mass of methanol solution (solid content concentration 50% by mass) of (D) p-toluenesulfonic acid (based on 100 parts by mass of (A) bisphenol A type epoxy compound) was added to the stirred solution, An oligomer sealing agent solution for coating was obtained.

(2) Preparation of oligomer sealing layer As a base material, a biaxially stretched polyethylene terephthalate film (“Diafoil T-100” (trade name) manufactured by Mitsubishi Plastics, Inc., thickness 50 μm, storage elastic modulus at 100 ° C. 3.2 × 10 ⁹ Pa, hereinafter also simply referred to as “film”).
The prepared oligomer sealing agent solution for coating was uniformly coated on one side of the prepared film by the Mayer bar coating method. The coated film was passed through the oven, and the coating film was thermally cured to obtain an oligomer sealing layer having a thickness of 150 nm as an intermediate layer. As conditions for blowing hot air in the oven, the temperature was set to 150 ° C., the wind speed was set to 8 m / min, and the processing speed in the oven was adjusted so that the coated film passed through the oven in 20 seconds.

(3) Production of conductive layer Resin in which polyethylene dioxythiophene (PEDOT) and polystyrene sulfonate (PSS), which are conductive polymers, are mixed in a mixed resin emulsion containing copolyester and polyurethane in a total amount of 1.0% by mass. A composition (manufactured by Chukyo Yushi Co., Ltd .; P-973, solid content of 10% by mass) was diluted to a solid content of 1.0% by mass with a mixture of isopropyl alcohol and purified water (mixing ratio 1: 1). Was used as a composition for forming a conductive layer. This conductive layer forming composition was uniformly applied to the oligomer sealing layer prepared in the above (2) and dried at 120 ° C. for 1 minute to prepare a conductive layer having a thickness of 100 nm.

(4) Preparation of pressure-sensitive adhesive composition A1 The following materials were blended and stirred sufficiently to prepare pressure-sensitive adhesive composition A1 as a pressure-sensitive adhesive liquid for application.
Specifically, 1.5 parts by mass of ketjen black as an antistatic agent was added to 100 parts by mass of polymer (X), and ketjen black was dispersed in polymer (X) using a disper. .
Next, 12.5 parts by mass (solid content) of an adhesion assistant and 8.75 parts by mass (solid content) of a crosslinking agent are added to the polymer (X) in which ketjen black is dispersed, and solidified using methyl ethyl ketone. A pressure-sensitive adhesive composition A1 having a partial concentration of 30% by mass was prepared.

-Materials used for preparation of adhesive composition A1-
-Polymer (X): Acrylate ester copolymer, 100 parts by mass (solid content)
The acrylic ester copolymer was prepared by copolymerizing 92.8% by mass of 2-ethylhexyl acrylate, 7.0% by mass of 2-hydroxyethyl acrylate, and 0.2% by mass of acrylic acid.
・ Antistatic agent: Ketjen Black (Lion Specialty Chemicals, ED-600JD), 1.5 parts by mass Adhesive aid: Hydroxylated polybutadiene at both ends (Nippon Soda Co., Ltd .; GI-1000) 12.5 parts by mass (solid content)
Crosslinking agent: aliphatic isocyanate having hexamethylene diisocyanate (isocyanurate-type modified product of hexamethylene diisocyanate) [manufactured by Nippon Polyurethane Industry Co., Ltd .; Coronate HX], 8.75 parts by mass (solid content)
・ Diluting solvent: Methyl ethyl ketone

(5) Preparation of pressure-sensitive adhesive layer A transparent polyethylene terephthalate film (manufactured by Lintec Corporation; SP-PET 382150, thickness 38 μm) provided with a silicone-based release layer was prepared as a release film.
The prepared pressure-sensitive adhesive composition A1 is applied to the release layer side of the release film using a comma coater (registered trademark), heated at 90 ° C. for 90 seconds, and then heated at 115 ° C. for 90 seconds. The coating film was dried to produce an adhesive layer having a thickness of 50 μm.

(6) Production of Laminate A pressure-sensitive adhesive layer produced on the release layer surface side of a release film and a conductive layer produced on the substrate via an oligomer sealing layer are bonded together to form a substrate and an oligomer sealing layer. The laminated body which consists of a conductive layer, an adhesive layer, and a peeling film was obtained.
Thereafter, the release film was peeled off from the laminate, and the pressure-sensitive adhesive sheet of Example 1 was obtained.

(Example 2)
In the preparation of the pressure-sensitive adhesive composition A1, pressure-sensitive adhesive composition A2 was prepared by adding 2.0 parts by mass of carbon nanotubes (manufactured by Kumho Petrochemical; K-Nanos 100P) instead of ketjen black.
A pressure-sensitive adhesive sheet of Example 2 was obtained in the same manner as Example 1 except that a pressure-sensitive adhesive layer was produced using this pressure-sensitive adhesive composition A2.

Example 3
In the preparation of the pressure-sensitive adhesive composition A1, 1.0 part by mass of the ionic liquid (1) (1-ethyl-3-methylpyridinium bis (trifluoromethanesulfonyl) imide) was added instead of the ketjen black and the pressure-sensitive adhesive Composition A3 was prepared.
A pressure-sensitive adhesive sheet of Example 3 was obtained in the same manner as Example 1 except that a pressure-sensitive adhesive layer was produced using this pressure-sensitive adhesive composition A3.

(Example 4)
Instead of the pressure-sensitive adhesive composition A1, the following pressure-sensitive adhesive composition A4 was used, and in the same manner as in Example 1, a laminate comprising a substrate, an oligomer sealing layer, a conductive layer, a pressure-sensitive adhesive layer, and a release film was prepared. Obtained.
Next, ultraviolet rays were irradiated from the side of the release film of the pressure-sensitive adhesive sheet under the conditions of an illuminance of 200 mW / cm ² and an integrated irradiation amount of 200 mJ / cm ² using a high-pressure mercury lamp manufactured by Eye Graphics as an ultraviolet irradiation device.
Thereafter, the release film was peeled off from the laminate, and the pressure-sensitive adhesive sheet of Example 4 was obtained.

-Preparation of pressure-sensitive adhesive composition A4 The following materials were blended and sufficiently stirred to prepare pressure-sensitive adhesive composition A4 as a pressure-sensitive adhesive liquid for application.
Specifically, 12.5 parts by mass of an adhesion assistant is added to a polymer obtained by mixing 90 parts by mass (solid content) of polymer (X) and 10.0 parts by mass (solid content) of an ionic polymer as an antistatic agent. Solid content), 8.75 parts by mass of the cross-linking agent (solid content), and 1.0 parts by mass (solid content) of a photopolymerization initiator (IGM Resins; Omnirad-127) were added, and methyl ethyl ketone was used. A pressure-sensitive adhesive composition A4 having a solid content concentration of 30% by mass was prepared.

-Materials used for preparation of adhesive composition A4-
Polymer (X): acrylic acid ester copolymer (similar to polymer (X) used in the preparation of pressure-sensitive adhesive composition A1), 90 parts by mass (solid content)
-Adhesion aid: hydroxylated hydrogenated polybutadiene at both ends (manufactured by Nippon Soda Co., Ltd .; GI-1000), 12.5 parts by mass (solid content)
Crosslinking agent: aliphatic isocyanate having hexamethylene diisocyanate (isocyanurate-type modified product of hexamethylene diisocyanate) [manufactured by Nippon Polyurethane Industry Co., Ltd .; Coronate HX], 8.75 parts by mass (solid content)
Photopolymerization initiator: 2-hydroxy-1- [4- (4- (2-hydroxy-2-methyl-propionyl) -benzyl) phenyl] -2-methyl-propan-1-one [manufactured by IGM Resin; Omnirad 127], 1.0 part by mass (solid content)
・ Diluting solvent: Methyl ethyl ketone ・ Antistatic agent: Ionic polymer (material with methacryloyl group added to polymer containing quaternary ammonium cation) 10.0 parts by mass (solid content)
The ionic polymer was produced by the following method.
[2- (Methacryloyloxy) ethyl] trimethylammonium bis (trifluoromethylsulfonyl) imide as “polymerizable monomer having a quaternary ammonium cation”, methacrylic acid as a polymerizable monomer having a reactive functional group, and polymerizability A polymerizable monomer having a quaternary ammonium cation as a monomer having 2-ethylhexyl acrylate and 2-hydroxyethyl acrylate: methacrylic acid: 2-ethylhexyl acrylate: 2-hydroxyethyl acrylate = 44.27: Copolymerization was performed so that 4.68: 40.24: 4.63.
The resulting polymer is reacted with glycidyl methacrylate as an energy ray-curable compound (6.18 in terms of the above mass ratio) to have an ionic polymer (a methacryloyl group and a quaternary ammonium cation in the side chain). )
When the molecular weight of this ionic polymer was measured by the method described above, the weight average molecular weight was 170,000.

(Example 5)
In the preparation of the pressure-sensitive adhesive composition A1, a mixture of 5 parts by mass of furnace black (manufactured by Mitsubishi Chemical; product name # 3030B) and 0.5 parts by mass of the ionic liquid (1) was added instead of ketjen black. An adhesive composition A5 was prepared.
A pressure-sensitive adhesive sheet of Example 5 was obtained in the same manner as Example 1 except that a pressure-sensitive adhesive layer was produced using this pressure-sensitive adhesive composition A5.

(Example 6)
In the preparation of the pressure-sensitive adhesive composition A1, 2.5 parts by mass of ketjen black was added to prepare a pressure-sensitive adhesive composition A6.
A pressure-sensitive adhesive sheet of Example 6 was obtained in the same manner as Example 1 except that the pressure-sensitive adhesive composition A6 was used to prepare a pressure-sensitive adhesive layer and the conductive layer was not prepared.

(Example 7)
A pressure-sensitive adhesive sheet of Example 7 was obtained in the same manner as Example 3 except that the following pressure-sensitive adhesive composition B1 was used instead of the pressure-sensitive adhesive composition A1.

-Preparation of pressure-sensitive adhesive composition B1 The following materials were blended and sufficiently stirred to prepare pressure-sensitive adhesive composition B1 as a pressure-sensitive adhesive liquid for application.
Specifically, with respect to 100 parts by mass (solid content) of the polymer (X), 1.0 part by mass of an ionic liquid (1) as an antistatic agent, 7.4 parts by mass (solid content) of a crosslinking agent, reactivity 23.3 parts by mass (solid content) of a low molecular compound having a functional group and 4.1 parts by mass (solid content) of a photopolymerization initiator are added, and an adhesive composition having a solid content concentration of 30% by mass using ethyl acetate. Product B1 was prepared.

-Materials used for preparation of adhesive composition B1-
-Polymer (X): Acrylic ester copolymer (similar to polymer (X) used in the preparation of pressure-sensitive adhesive composition A1), 100 parts by mass (solid content)
Antistatic agent: ionic liquid (1) (1-ethyl-3-methylpyridinium bis (trifluoromethanesulfonyl) imide)
Crosslinking agent: aliphatic isocyanate having hexamethylene diisocyanate (isocyanurate type modified hexamethylene diisocyanate) [manufactured by Nippon Polyurethane Industry Co., Ltd .; Coronate HX], 7.4 parts by mass (solid content)
Low molecular weight compound having a reactive functional group: propoxylated bisphenol A diacrylate [manufactured by Shin-Nakamura Chemical Co., Ltd .; A-BPP]
Photopolymerization initiator: 2-hydroxy-1- [4- (4- (2-hydroxy-2-methyl-propionyl) -benzyl) phenyl] -2-methyl-propan-1-one [manufactured by IGM Resin; Omnirad 127], 4.1 parts by mass (solid content)
・ Diluting solvent: Ethyl acetate

(Example 8)
Low molecular weight compound having a reactive functional group, 10.0 parts by mass of an ionic polymer as an antistatic agent, 7.4 parts by mass (solid content), and a reactive functional group with respect to 90 parts by mass (solid content) of the polymer (X). 3 parts by mass (solid content) and 4.1 parts by mass (solid content) of a photopolymerization initiator were added, and an adhesive composition B2 having a solid content concentration of 30% by mass was prepared using ethyl acetate.
In addition, an ionic polymer is the same as the ionic polymer used by preparation of adhesive composition A4. The crosslinking agent, the low molecular compound having a reactive functional group, and the photopolymerization initiator are the same as the materials used in the preparation of the pressure-sensitive adhesive composition B1.
A pressure-sensitive adhesive sheet of Example 8 was obtained in the same manner as Example 7 except that a pressure-sensitive adhesive layer was produced using this pressure-sensitive adhesive composition B2.

(Comparative Example 1)
In the preparation of the pressure-sensitive adhesive composition A1, 2.0 parts by mass of ketjen black was added to prepare a pressure-sensitive adhesive composition A7.
A pressure-sensitive adhesive sheet of Comparative Example 1 was obtained in the same manner as in Example 1 except that this pressure-sensitive adhesive composition A7 was used to prepare a pressure-sensitive adhesive layer and that a conductive layer was not prepared.

(Comparative Example 2)
In the preparation of the pressure-sensitive adhesive composition A1, instead of ketjen black, 1.0 part by mass of the ionic liquid (1) was added to prepare a pressure-sensitive adhesive composition A8.
A pressure-sensitive adhesive sheet of Comparative Example 2 was obtained in the same manner as in Example 1 except that a pressure-sensitive adhesive layer was prepared using this pressure-sensitive adhesive composition A8 and a conductive layer was not prepared.

(Comparative Example 3)
In the preparation of the pressure-sensitive adhesive composition A1, 1.0 part by mass of the ionic liquid (2) (1-butyl-4-methylpyridinium hexafluorophosphate) was added in place of the ketjen black to add the pressure-sensitive adhesive composition A9. Was prepared.
A pressure-sensitive adhesive sheet of Comparative Example 3 was obtained in the same manner as in Example 1 except that a pressure-sensitive adhesive layer was produced using this pressure-sensitive adhesive composition A9.

(Comparative Example 4)
In preparing the pressure-sensitive adhesive composition A1, pressure-sensitive adhesive composition A10 was prepared without adding an antistatic agent.
A pressure-sensitive adhesive sheet of Comparative Example 4 was obtained in the same manner as in Example 1 except that a pressure-sensitive adhesive layer was produced using this pressure-sensitive adhesive composition A10.

Table 1 shows the configuration of the pressure-sensitive adhesive sheet obtained in each example.

The following evaluation was performed using the adhesive sheet obtained in each example. The results are shown in Table 1.

[Charging characteristics evaluation]
(Surface resistivity)
The surface resistivity of the pressure-sensitive adhesive layer after the pressure-sensitive adhesive sheet was heated at 190 ° C. for 60 minutes in a nitrogen atmosphere and then allowed to stand for 24 hours in an atmosphere at 23 ° C. and 50% RH was measured.

(Battery voltage)
By the above-described method, the pressure-sensitive adhesive layer was measured after the pressure-sensitive adhesive sheet was heated at 190 ° C. for 60 minutes in a nitrogen atmosphere and then allowed to stand at 23 ° C. and 50% RH for 24 hours.

(Adhesive strength evaluation)
(Adhesive strength to copper foil and polyimide film)
According to the method described above, the pressure-sensitive adhesive sheet is heated at 100 ° C. for 30 minutes, subsequently heated at 180 ° C. for 30 minutes, further heated at 190 ° C. and 60 minutes, and then at 23 ° C. and The adhesive strength of the adhesive layer to the copper foil and the adhesive strength to the polyimide film after being allowed to stand for 24 hours in an atmosphere of 50% RH were measured.

[Evaluation of residue]
The surface of a copper foil (150 mm × 100 mm, thickness 0.08 mm, JIS H3100: 2010 C1220R-H (stretched copper foil)) is polished with a # 800 water file, and the arithmetic average roughness Ra of the copper foil is 0.00. Polishing scratches were made so as to be 2 ± 0.1 μm. The adhesive sheet cut out to 25 mm x 100 mm was stuck on this copper foil. The pasting was performed in accordance with JIS Z 0237: 2009. Thereafter, in the same manner as the adhesive strength evaluation, the pressure-sensitive adhesive sheet is heated at 100 ° C. for 30 minutes, subsequently heated at 180 ° C. for 30 minutes, and further heated at 190 ° C. for 60 minutes. And allowed to cool to room temperature (25 ° C.).
The pressure-sensitive adhesive sheet (adhesive sheet with copper foil) after being allowed to cool is peeled off using an autograph (manufactured by Shimadzu Corporation, Autograph AG-IS 500N) at a peeling direction of 90 degrees and a peeling speed of 3 mm / min. The subsequent copper foil and the pressure-sensitive adhesive sheet were observed with a digital microscope (manufactured by Keyence Corporation: Digital Microscope, VHX-1000) to confirm the presence or absence of adhesive residue. The observation magnification was 500 times.
The case where no adhesive remained was determined as “A”, and the case where adhesive remained partially was determined as “B”.

(Explanation of Table 1)
“Polymer type” means an ionic polymer.
“Yes” means that there is a conductive layer, and “No” means that there is no conductive layer.
“CNT” means carbon nanotubes.
“Ionic liquid 1” means ionic liquid (1).
“Ionic liquid 2” means the ionic liquid (2).

In the pressure-sensitive adhesive sheets of Examples 1 to 8, the surface resistivity of the pressure-sensitive adhesive layer was less than 10 ¹¹ Ω / □ even after heating at 190 ° C. for 60 minutes in a nitrogen atmosphere.
On the other hand, the pressure-sensitive adhesive sheets of Comparative Examples 1 to 4 had a surface resistivity of 10 ¹¹ Ω / □ or more after high-temperature heating.
By comparing Example 3 with Comparative Example 3, the pressure-sensitive adhesive sheet of Example 3 using the ionic liquid (1) as the antistatic agent is compared with the pressure-sensitive adhesive sheet of Comparative Example 3 using the ionic liquid (2). It can be seen that the rate of increase in surface resistivity after high-temperature heating (after heating / before heating) is greatly suppressed.
According to the comparison between Example 1 and Comparative Example 1, and the comparison between Example 3 and Comparative Example 2, the adhesive sheets of Examples 1 and 3 having a conductive layer are those of Comparative Examples 1 and 2 having no conductive layer. It can be seen that the rate of increase in surface resistivity after high-temperature heating (after heating / before heating) is significantly suppressed as compared to the pressure-sensitive adhesive sheet.
In addition, in the pressure-sensitive adhesive sheets of Examples 1 to 8, the charged voltage of the pressure-sensitive adhesive layer was less than 0.1 kV even after high temperature heating.
Further, the pressure-sensitive adhesive sheets of Examples 1 to 8 were heated under the conditions of 100 ° C. and 30 minutes, subsequently heated under the conditions of 180 ° C. and 30 minutes, and further heated under the conditions of 190 ° C. and 60 minutes. Both the adhesive force to the copper foil of the adhesive layer and the adhesive force to the polyimide film were ensured. The residue evaluation was also good.
Therefore, according to the pressure-sensitive adhesive sheet of this example, the electrostatic breakdown of the semiconductor element can be suppressed even if the pressure-sensitive adhesive sheet is peeled off from the adherend after being subjected to a process of heating at a high temperature.

10, 10A, 10B, 10C, 10D ... Adhesive sheet, 11, 11A, 11B, 11C, 11D ... Base material, 11a, 11c, 11e, 11g, 11i ... First base material surface, 11b, 11d, 11f, 11h, 11j ... second substrate surface, 12, 12A, 12B, 12C, 12D ... adhesive layer, 12a, 12c, 12e, 12g, 12i ... first adhesive surface, 12b, 12d, 12f, 12h, 12j ... second adhesive Surface, 13, 13A, 13B ... conductive layer, 14, 14A ... oligomer sealing layer, 14B ... primer layer.

Claims (14)

1. A pressure-sensitive adhesive sheet used when sealing a semiconductor element on a pressure-sensitive adhesive sheet,
   A substrate;
   An adhesive layer containing an antistatic agent, and
   The surface resistivity of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is less than 10 ¹¹ Ω / □ after being heated at 190 ° C. for 60 minutes in a nitrogen atmosphere and then allowed to stand at 23 ° C. and 50% RH for 24 hours. ,
   Adhesive sheet.
2. The charged voltage of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet after being heated in a nitrogen atmosphere at 190 ° C. for 60 minutes and then allowed to stand in a 23 ° C. and 50% RH atmosphere for 24 hours is less than 0.1 kV.
   The pressure-sensitive adhesive sheet according to claim 1.
3. The antistatic agent includes at least one selected from the group consisting of a carbon material and an ionic material.
   The pressure-sensitive adhesive sheet according to claim 1 or claim 2.
4. The carbon material is at least one selected from the group consisting of carbon nanotubes, graphene, and carbon black.
   The pressure-sensitive adhesive sheet according to claim 3.
5. The ionic material is at least one selected from the group consisting of an ionic liquid and an ionic polymer.
   The pressure-sensitive adhesive sheet according to claim 3 or claim 4.
6. The antistatic agent is the ionic liquid or a mixture of the ionic liquid and the carbon material.
   The pressure-sensitive adhesive sheet according to claim 5.
7. The ionic liquid includes a cation and an anion represented by the following general formula (1).
   The pressure-sensitive adhesive sheet according to claim 5 or 6.
   

   

   (In General Formula (1), R ¹ and R ² are each independently a fluorine atom or a perfluoroalkyl group having 1 to 8 carbon atoms, and R ¹ and R ² are the same or different.)
8. The content of the ionic liquid is 0.01% by mass or more and 10% by mass or less with respect to the entire pressure-sensitive adhesive layer.
   The pressure-sensitive adhesive sheet according to any one of claims 5 to 7.
9. The pressure-sensitive adhesive layer contains an acrylic pressure-sensitive adhesive composition,
   The acrylic pressure-sensitive adhesive composition includes an acrylic copolymer having a main monomer of (meth) acrylic acid alkyl ester having an alkyl group having 4 to 12 carbon atoms,
   The pressure-sensitive adhesive sheet according to any one of claims 1 to 8.
10. The pressure-sensitive adhesive sheet is heated under conditions of 100 ° C. and 30 minutes, subsequently heated under conditions of 180 ° C. and 30 minutes, further heated under conditions of 190 ° C. and 60 minutes, and then in an atmosphere of 23 ° C. and 50% RH The pressure-sensitive adhesive strength of the pressure-sensitive adhesive layer to the copper foil after standing for 24 hours is 0.5 N / 25 mm to 3.0 N / 25 mm and the pressure-sensitive adhesive strength of the pressure-sensitive adhesive layer to the polyimide film is 0.00. 50N / 25mm or more and 2.00N / 25mm or less,
    The pressure-sensitive adhesive sheet according to any one of claims 1 to 9.
11. The surface of the substrate on the side of the pressure-sensitive adhesive layer has conductivity.
    The pressure-sensitive adhesive sheet according to any one of claims 1 to 10.
12. The pressure-sensitive adhesive sheet was heated at 190 ° C. for 60 minutes in a nitrogen atmosphere and then allowed to stand for 24 hours in an atmosphere at 23 ° C. and 50% RH, and then the surface resistivity on the pressure-sensitive adhesive layer side of the substrate was 10 ⁻⁷ Ω / □ or more and 10 ⁷ Ω / □ or less,
    The pressure-sensitive adhesive sheet according to claim 11.
13. Having a conductive layer between the substrate and the adhesive layer;
    The pressure-sensitive adhesive sheet according to any one of claims 1 to 12.
14. The pressure-sensitive adhesive sheet was heated at 190 ° C. for 60 minutes in a nitrogen atmosphere, and then allowed to stand for 24 hours in an atmosphere at 23 ° C. and 50% RH, and then the surface resistivity on the pressure-sensitive adhesive layer side of the conductive layer was 10 ^-7 Ω / □ or more and 10 ⁷ Ω / □ or less,
    The pressure-sensitive adhesive sheet according to claim 13.

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