CN113165362B

CN113165362B - Adhesive film, foldable device, and rollable device

Info

Publication number: CN113165362B
Application number: CN201980078499.9A
Authority: CN
Inventors: 设乐浩司; 仲野武史
Original assignee: Nitto Denko Corp
Current assignee: Nitto Denko Corp
Priority date: 2018-11-28
Filing date: 2019-11-15
Publication date: 2023-04-14
Anticipated expiration: 2039-11-15
Also published as: JP2020204010A; KR102579623B1; SG11202103223SA; CN113165362A; KR20210083295A

Abstract

Provided is an adhesive film having excellent flexibility and transparency. Also provided are a foldable device and a rollable device having excellent bendability. The adhesive film has a base layer and an adhesive layer, wherein the adhesive film has a tan delta (0.7%) at 0.7% strain of 0.1 or less as measured in a stretching mode of a viscoelasticity measuring apparatus. The adhesive film has a base layer and an adhesive layer, and the difference between tan delta (0.7%) -tan delta (0.1%) at 0.7% strain and tan delta (0.1%) at 0.1% strain, measured in a stretching mode of a viscoelasticity measuring apparatus, is 0.05 or less.

Description

Adhesive film, foldable device, and rollable device

Technical Field

The present invention relates to a pressure-sensitive adhesive film. The invention also relates to a foldable device comprising such a pressure sensitive adhesive film, and to a rollable device comprising such a pressure sensitive adhesive film.

Background

Pressure-sensitive adhesive films have been used for reinforcement, surface protection, and the like of members of various shapes.

For example, when an Integrated Circuit (IC) or a flexible printed circuit substrate (FPC) is bonded to a substrate of a semiconductor element (e.g., a TFT substrate), thermocompression bonding is generally performed with an Anisotropic Conductive Film (ACF). In performing such thermocompression bonding, a pressure-sensitive adhesive film may be previously attached to the back surface side of the substrate of the semiconductor element to reinforce the element (for example, patent document 1).

In addition, the manufacturing method of a flexible device or a rollable device, which has been developed in recent years, generally includes: forming a peeling layer and a flexible or rollable film substrate on a support substrate such as glass; forming a TFT substrate on the film substrate; further forming an organic EL layer on the TFT substrate; the support substrate is then peeled off to produce a flexible device or a rollable device. However, the flexible display layer or the rollable display layer is so thin as to cause inconvenience in the device due to its operation or the like. Therefore, a pressure-sensitive adhesive film may be attached to the back side of the film substrate to reinforce such a device (for example, patent document 2).

The substrate of the semiconductor element, or the flexible device or the rollable device may be repeatedly bent. Therefore, when the bending characteristics of the pressure-sensitive adhesive film attached to the back surface side of the substrate are poor, the recovery (recovery) of such a substrate or device after bending may be deteriorated, and in the worst case, the substrate or device may be broken due to repeated bending. Specifically, when an attempt is made to fit the pressure-sensitive adhesive film to a curved portion (e.g., a movable curved portion of a foldable member), for example, such a problem as described below may occur.

When the pressure-sensitive adhesive film is bent at a certain angle, a compressive force acts on the radially inner side of the bent film, and therefore the pressure-sensitive adhesive film itself is deformed, thereby relaxing the force. Specifically, for example, the film is liable to wrinkle.

When the pressure-sensitive adhesive film is bent at an angle, a stress that stretches the film acts on the radially outer side of the bent film. Therefore, the film floats from the adherend when the stress is relaxed.

When the pressure-sensitive adhesive film is bent at a certain angle, the thickness of the portion of the pressure-sensitive adhesive film to be bent or the portion thereof to be stretched is greatly changed. In this state, moreover, wrinkles are likely to occur in the film, or floating of the film occurs. For example, when the pressure-sensitive adhesive film is stretched, the thickness of the pressure-sensitive adhesive film is significantly reduced, and therefore, it is liable to occur its floating from the adherend.

As described above, in the pressure-sensitive adhesive film of the related art, it has not been possible to sufficiently follow the irregularities of the corner or the curved portion.

In particular, when the pressure-sensitive adhesive film is attached to the movable bending portion, the bending is repeated, and thus a state is established in which a bending trace (so-called "curl") is left in the pressure-sensitive adhesive film on the movable bending portion.

In addition, when an Integrated Circuit (IC) or a flexible printed circuit substrate (FPC) is bonded to a substrate (for example, a TFT substrate) of a semiconductor element by performing thermocompression bonding, bonding is performed after a position where the IC or FPC and the substrate are bonded to each other has been observed from the back surface side of the substrate. Therefore, the pressure-sensitive adhesive film attached to the back surface side of the substrate is required to have transparency.

Reference list

Patent document

[PTL 1]JP 5600039 B2

[PTL 2]JP 6376271 B1

Disclosure of Invention

Problems to be solved by the invention

The purpose of the present invention is to provide a pressure-sensitive adhesive film having excellent flexibility and transparency. Another object of the present invention is to provide a foldable device and a rollable device each having excellent bendability.

Means for solving the problems

According to an embodiment of the present invention, there is provided a pressure-sensitive adhesive film including: a substrate layer; and a pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive film has a tan δ (0.7%) at 0.7% strain of 0.1 or less as measured in a stretch mode of a viscoelasticity measuring apparatus.

According to an embodiment of the present invention, there is provided a pressure-sensitive adhesive film including: a substrate layer; and a pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive film has a difference (tan δ (0.7%) -tan δ (0.1%)) between tan δ (0.7%) at 0.7% strain and tan δ (0.1%) thereof at 0.1% strain of 0.05 or less as measured in a stretch mode of a viscoelasticity measuring apparatus.

In one embodiment, after the pressure sensitive adhesive film has been bent at a diameter of 6mm phi and maintained at 90 ℃ for 48 hours, and then the bend is released, and the pressure sensitive adhesive film is left to stand at 23 ℃ and 50% RH for 24 hours, the bending angle of the pressure sensitive adhesive film of the present invention is 60 DEG to 180 deg.

In one embodiment, the pressure-sensitive adhesive film of the present invention further comprises a topcoat layer on the surface of the substrate layer opposite to the surface thereof having the pressure-sensitive adhesive layer.

In one embodiment, the topcoat includes a binder containing at least one selected from a polyester resin and a polyurethane-based resin.

In one embodiment, the binder comprises a polyurethane-based resin.

In one embodiment, the topcoat comprises an antistatic component.

In one embodiment, the substrate layer has a Young's modulus at 23 ℃ of 6.0X 10 ⁷ Pa or above.

In one embodiment, the material of the substrate layer is at least one selected from the group consisting of polyimide and polyetheretherketone.

In one embodiment, the pressure-sensitive adhesive film of the present invention further comprises a topcoat layer on a surface of the substrate layer opposite to the surface thereof having the pressure-sensitive adhesive layer, wherein the topcoat layer comprises a binder containing a polyurethane-based resin and an antistatic component, and wherein the material of the substrate layer is at least one selected from polyimide and polyetheretherketone.

In one embodiment, the total light transmittance of the pressure-sensitive adhesive film of the present invention is 20% or more.

In one embodiment, the haze of the pressure-sensitive adhesive film of the present invention is 15% or less.

In one embodiment, the pressure-sensitive adhesive layer has a pressure-sensitive adhesive strength at 23 ℃ at a stretching speed of 300 mm/min and a peel angle of 180 ° with respect to the SUS board of 1N/25mm or more.

In one embodiment, the pressure sensitive adhesive layer comprises an acrylic pressure sensitive adhesive.

In one embodiment, the pressure sensitive adhesive film of the present invention is attached to a foldable member.

In one embodiment, the foldable member is an OLED.

In one embodiment, the pressure sensitive adhesive film of the present invention is attached to a rollable member.

In one embodiment, the rollable member is an OLED.

According to an embodiment of the present invention, there is provided a foldable device including the above-described pressure-sensitive adhesive film.

According to an embodiment of the present invention, there is provided a rollable device including the above pressure sensitive adhesive film.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, a pressure-sensitive adhesive film excellent in flexibility and transparency can be provided. According to the present invention, a foldable device and a rollable device each having excellent bendability can also be provided.

Drawings

Fig. 1 is a schematic sectional view for explaining a foldable device according to an embodiment of the present invention, and is an explanation of one use form of the pressure-sensitive adhesive film of the present invention.

Fig. 2 is a schematic cross-sectional view for explaining a method of evaluating the bending recovery property.

Fig. 3 is a schematic sectional view for explaining a peeling evaluation method.

Detailed Description

< < < pressure sensitive adhesive film > >)

The pressure-sensitive adhesive film of the present invention includes a substrate layer and a pressure-sensitive adhesive layer. That is, the pressure-sensitive adhesive film of the invention may include any suitable other layer within such a range that the effect of the invention is not impaired, as long as the pressure-sensitive adhesive film includes a base material layer and a pressure-sensitive adhesive layer.

The number of layers of the base material layer may be 1 or 2 or more. The number of layers of the base material layer is preferably 1 layer because the effects of the present invention can be further exhibited.

The number of pressure-sensitive adhesive layers may be 1 layer, or may be 2 or more layers. The number of layers of the pressure-sensitive adhesive layer is preferably 1 because the effects of the present invention can be further exhibited.

Any suitable release liner may be disposed on the surface of the pressure sensitive adhesive layer opposite the substrate layer for, e.g., protecting the pressure sensitive adhesive film of the present invention until its use.

Examples of release liners include: a release liner obtained by subjecting the surface of a substrate (liner substrate) such as paper or a plastic film to silicone treatment; and a release liner obtained by laminating a polyolefin-based resin on the surface of a substrate (liner substrate) such as paper or a plastic film. Examples of the plastic film as the backing substrate include a polyethylene film, a polypropylene film, a polybutylene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, a vinyl chloride copolymer film, a polyethylene terephthalate film, a polybutylene terephthalate film, a polyurethane film, and an ethylene-vinyl acetate copolymer film.

The thickness of the release liner is preferably 1 μm to 500. Mu.m, more preferably 3 μm to 450. Mu.m, still more preferably 5 μm to 400. Mu.m, and particularly preferably 10 μm to 300. Mu.m.

The total thickness "d" of the pressure-sensitive adhesive film of the present invention is preferably 1 to 500. Mu.m, more preferably 5 to 200. Mu.m, still more preferably 10 to 150. Mu.m, particularly preferably 20 to 100. Mu.m, most preferably 30 to 80 μm. When the total thickness "d" of the pressure-sensitive adhesive film of the present invention falls within the above range, the effects of the present invention can be further exhibited.

The pressure-sensitive adhesive film of the present invention has a tan δ (0.7%) at 0.7% strain of 0.1 or less, preferably 0.09 or less, more preferably 0.08 or less, still more preferably 0.07 or less, and particularly preferably 0.06 or less, as measured in a stretching mode of a viscoelasticity measuring apparatus. When the tan δ (0.7%) of the pressure-sensitive adhesive film of the present invention at 0.7% strain measured in the stretching mode of the viscoelasticity measuring apparatus falls within the above range, the effects of the present invention can be further exhibited.

Tan δ (0.7%) of the pressure-sensitive adhesive film at 0.7% strain measured in the stretching mode of the viscoelasticity measuring apparatus is an index showing loss tangent when the pressure-sensitive adhesive film is bent to a large extent. In the course of completing the present invention, the inventors have found, based on various experimental data, that when the value falls within the above range, the effects of the present invention can be further exhibited. The measurement method of tan δ (0.7%) at 0.7% strain measured in the stretching mode of the viscoelasticity measuring apparatus will be described later in detail.

The pressure-sensitive adhesive film of the present invention preferably has tan δ (0.1%) at 0.1% strain of 0.1% or less, more preferably 0.08 or less, still more preferably 0.06 or less, particularly preferably 0.05 or less, as measured in a stretching mode of a viscoelasticity measuring apparatus. When the tan δ (0.1%) of the pressure-sensitive adhesive film of the present invention at a strain of 0.1% measured in the stretching mode of the viscoelasticity measuring apparatus falls within the above range, the effect of the present invention can be further exhibited.

Tan δ (0.1%) of the pressure-sensitive adhesive film at 0.1% strain measured in the stretching mode of the viscoelasticity measuring apparatus is an index showing loss tangent when the pressure-sensitive adhesive film is bent to a small extent. In the course of completing the present invention, the inventors have found, based on various experimental data, that when the value falls within the above range, the effects of the present invention can be further exhibited. The measurement method of tan δ (0.1%) at 0.1% strain measured in the stretching mode of the viscoelasticity measuring apparatus will be described in detail later.

The difference between tan δ (0.7%) -tan δ (0.1%) at 0.7% strain and tan δ (0.1%) at 0.1% strain of the pressure-sensitive adhesive film of the present invention measured in the stretching mode of the viscoelasticity measuring device (tan δ (0.7%) -tan δ (0.1%)) is preferably 0.05 or less, more preferably 0.04 or less, still more preferably 0.03 or less. The effects of the present invention can be further exhibited when the difference between tan δ (0.7%) at 0.7% strain and tan δ (0.1%) thereof at 0.1% strain (tan δ (0.7%) -tan δ (0.1%) measured in a stretching mode of a viscoelasticity measuring apparatus) of the pressure-sensitive adhesive film of the present invention falls within the above-mentioned range.

The difference (tan δ (0.7%) -tan δ (0.1%)) between tan δ at 0.7% strain and tan δ at 0.1% strain thereof, measured in a tensile mode of a viscoelasticity measuring apparatus, of the pressure-sensitive adhesive film is an index showing the difference between the loss tangent at the time of bending the pressure-sensitive adhesive film to a large extent and the loss tangent at the time of bending the pressure-sensitive adhesive film to a small extent. In the course of completing the present invention, the inventors have found, based on various experimental data, that when the value falls within the above range, the effects of the present invention can be further exhibited.

The pressure-sensitive adhesive film of the present invention has been bent at a diameter of 6mm phi and held at 90 ℃ for 48 hours, then the bend is released, and the bending angle after the pressure-sensitive adhesive film is left to stand at 23 ℃ and 50% rh for 24 hours is preferably 60 ° to 180 °, more preferably 80 ° to 180 °, still more preferably 100 ° to 180 °, particularly preferably 120 ° to 180 °, and most preferably 150 ° to 180 °. The effects of the present invention can be further exhibited when the bending has been released after the pressure-sensitive adhesive film of the present invention has been bent at a diameter of 6mm phi and held at 90 ℃ for 48 hours, and the bending angle after the pressure-sensitive adhesive film is allowed to stand at 23 ℃ and 50% RH for 24 hours falls within the above-mentioned range.

After the pressure-sensitive adhesive film had been bent at a diameter of 6mm phi and held at 90 ℃ for 48 hours, the bend was released, and the bend angle after the pressure-sensitive adhesive film was left to stand at 23 ℃ and 50% RH for 24 hours was an index showing the recovery after bending. The method of measuring the bending angle after the pressure-sensitive adhesive film has been bent at a diameter of 6mm phi and held at 90 ℃ for 48 hours, then the bend is released, and the pressure-sensitive adhesive film is allowed to stand at 23 ℃ and 50% RH for 24 hours will be described in detail later.

The total light transmittance of the pressure-sensitive adhesive film of the present invention is preferably 20% or more, more preferably 30% or more, still more preferably 40% or more, particularly preferably 50% or more, most preferably 60% or more. When the total light transmittance of the pressure-sensitive adhesive film of the present invention falls within the above range, excellent transparency can be further exhibited.

The haze of the pressure-sensitive adhesive film of the present invention is preferably 15% or less, more preferably 13% or less, still more preferably 10% or less, particularly preferably 8% or less, and most preferably 6% or less. When the haze of the pressure-sensitive adhesive film of the present invention falls within the above range, excellent transparency can be further exhibited.

The pressure-sensitive adhesive film of the present invention is excellent in flexibility and transparency, and thus is preferably attached to a foldable member. Any suitable member may be used as the foldable member as long as the member can be repeatedly bent. Examples of such foldable members include foldable optical members and foldable electronic members, and a typical example thereof is a foldable OLED.

The pressure-sensitive adhesive film of the present invention is excellent in flexibility and transparency, and thus is preferably attached to a rollable member. Any suitable member may be used as the rollable member as long as the member can be repeatedly wound (wind) and rewound. Examples of such rollable members include rollable optical members and rollable electronic members, and a typical example thereof is a rollable OLED.

< substrate layer >)

The thickness of the substrate layer is preferably 1 to 500. Mu.m, more preferably 5 to 300. Mu.m, still more preferably 10 to 100. Mu.m, particularly preferably 15 to 80 μm, most preferably 20 to 60 μm. When the thickness of the base material layer falls within the above range, the effect of the present invention can be further exhibited.

The Young's modulus at 23 ℃ of the substrate layer is preferably 6.0X 10 ⁷ Pa or more, more preferably 1.0X 10 ⁸ Pa or more, still more preferably 5.0X 10 ⁸ Pa or more, particularly preferably 8.0X 10 ⁸ Pa or more, most preferably 1.0X 10 ⁹ Pa or above. Typically, the upper limit of the Young's modulus at 23 ℃ of the substrate layer is preferably 1.0X 10 ¹¹ Pa or less. When the young's modulus at 23 ℃ of the substrate layer falls within the above range, the effect of the present invention can be further exhibited. When the young's modulus at 23 ℃ of the base material layer is excessively low, in the case where the pressure-sensitive adhesive film is bent at a certain angle, there is a risk that the tension on the radially outer side thereof is not sufficiently maintained with respect to the compression on the radially inner side thereof. Therefore, there is a risk that the thickness of the pressure-sensitive adhesive film is easily changed, and thus it is easily floated from an adherend. When the Young's modulus at 23 ℃ of the substrate layer is too high, it is impossible to make the pressure-sensitive adhesive film easyThe ground is deformed. The method for measuring the Young's modulus will be described in detail later.

Any suitable material may be used as the material of the base layer within such a range that the effect of the present invention is not impaired. Such a material for the base material layer is generally, for example, a resin material.

Examples of the resin material as the material of the base material layer include: acrylic resins such as Polyimide (PI), polyether ether ketone (PEEK), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), and polymethyl methacrylate (PMMA); and polycarbonate, triacetyl cellulose (TAC), polysulfone, polyarylate, polyethylene (PE), polypropylene (PP), ethylene-propylene copolymer, ethylene-vinyl acetate copolymer (EVA), polyamide (nylon), wholly aromatic polyamide (aramid), polyvinyl chloride (PVC), polyvinyl acetate, polyphenylene Sulfide (PPs), fluorine-based resin, and cyclic olefin-based polymer.

The resin material as the material of the base layer is preferably at least one selected from, for example, polyimide (PI), polyether ether ketone (PEEK), and a cyclic olefin polymer, and more preferably at least one selected from, for example, polyimide (PI) and polyether ether ketone (PEEK), because the effects of the present invention can be further exhibited.

< pressure sensitive adhesive layer > <

The thickness of the pressure-sensitive adhesive layer is preferably 1 μm to 500. Mu.m, more preferably 5 μm to 300. Mu.m, still more preferably 10 μm to 100. Mu.m, particularly preferably 15 μm to 80 μm, most preferably 20 μm to 60 μm. When the thickness of the pressure-sensitive adhesive layer falls within the above range, the effect of the present invention can be further exhibited.

The pressure-sensitive adhesive layer preferably has a pressure-sensitive adhesive strength to a glass plate at 23 ℃ at a stretching speed of 300 mm/min and a peel angle of 180 DEG of 1N/25mm or more, more preferably 5N/25mm or more, still more preferably 10N/25mm or more, particularly preferably 12N/25mm or more, and most preferably 15N/25mm or more. Typically, the upper limit of the pressure-sensitive adhesive strength of the pressure-sensitive adhesive layer to the glass plate at 23 ℃ at a stretching speed of 300 mm/min and a peel angle of 180 ° is preferably 1,000n/25mm or less, more preferably 500N/25mm or less, still more preferably 300N/25mm or less, particularly preferably 200N/25mm or less, most preferably 100N/25mm or less. When the pressure-sensitive adhesive strength of the pressure-sensitive adhesive layer at 23 ℃ at a stretching speed of 300 mm/min and a peel angle of 180 ° with respect to the glass plate falls within the above range, the effect of the present invention can be further exhibited.

The pressure sensitive adhesive layer includes a base polymer. The base polymer may be used alone or in combination thereof. The content of the base polymer in the pressure-sensitive adhesive layer is preferably 20wt% to 100wt% because the effects of the present invention can be further exhibited, and is more preferably 30wt% to 95wt%, still more preferably 40wt% to 90wt%, particularly preferably 45wt% to 85wt%, most preferably 50wt% to 80wt%.

Any suitable polymer may be used as the base polymer within such a range that the effect of the present invention is not impaired. The base polymer is preferably at least one selected from, for example, acrylic polymers, rubber polymers, silicone polymers, and polyurethane polymers, because the effects of the present invention can be further exhibited. That is, the pressure-sensitive adhesive layer preferably contains at least one selected from the group consisting of an acrylic pressure-sensitive adhesive containing an acrylic polymer, a rubber pressure-sensitive adhesive containing a rubber polymer, a silicone pressure-sensitive adhesive containing a silicone polymer, and a polyurethane pressure-sensitive adhesive containing a polyurethane polymer. The pressure-sensitive adhesive layer preferably contains an acrylic pressure-sensitive adhesive because the effects of the present invention can be further exhibited. An acrylic pressure-sensitive adhesive is described in detail below as a typical example of a pressure-sensitive adhesive that can be incorporated into the pressure-sensitive adhesive layer.

< acrylic pressure-sensitive adhesive >

The acrylic pressure-sensitive adhesive contains an acrylic polymer as its base polymer. The acrylic pressure sensitive adhesive may include a tackifying resin. The acrylic pressure sensitive adhesive may include a crosslinking agent.

When the acrylic pressure-sensitive adhesive contains an acrylic polymer, a tackifier resin, and a crosslinking agent, the content of the total amount of the acrylic polymer, the tackifier resin, and the crosslinking agent is preferably 95wt% or more relative to the total amount of the acrylic pressure-sensitive adhesive, because the effect of the present invention can be further exhibited, and the content is more preferably 97wt% or more, and still more preferably 99wt% or more.

(acrylic acid Polymer)

The acrylic polymer is preferably a polymer of a monomer component containing, for example, an alkyl (meth) acrylate as a main monomer, and may further contain a secondary monomer copolymerizable with the main monomer. The term "main monomer" as used herein refers to a component that constitutes more than 50wt% of the total of the monomer components.

For example, a compound represented by the following formula (1) can be suitably used as the alkyl (meth) acrylate.

CH ₂ ＝C(R ¹ )COOR ² (1)

Here, in the formula (1), R ¹ Represents a hydrogen atom or a methyl group, and R ² Represents a chain alkyl group having 1 to 20 carbon atoms (hereinafter, such a range of the number of carbon atoms is sometimes referred to as "C1-20"). From the viewpoint of, for example, the storage elastic modulus of the pressure-sensitive adhesive layer, R ² The expression preferably represents a C1-14 chain alkyl group, more preferably a C2-10 chain alkyl group, and still more preferably a C4-8 chain alkyl group. The term "chain" as used herein encompasses straight chain groups and branched chain groups.

Wherein R is ² Examples of the alkyl (meth) acrylate representing the C1-20 chain alkyl group include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, pentyl (meth) acrylate, isoamyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, lauryl (meth) acrylate, andtridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, isostearyl (meth) acrylate, nonadecyl (meth) acrylate, and eicosyl (meth) acrylate. These alkyl (meth) acrylates may be used alone or in combination thereof.

The alkyl (meth) acrylate is preferably, for example, n-Butyl Acrylate (BA) or 2-ethylhexyl acrylate (2 EHA), because the effects of the present invention can be further exhibited.

The content of the alkyl (meth) acrylate in the entire monomer components used for synthesizing the acrylic polymer is preferably 70wt% or more because the effects of the present invention can be further exhibited, and the content is more preferably 85wt% or more, still more preferably 90wt% or more. The upper limit of the content of the alkyl (meth) acrylate is preferably 99.5wt% or less, more preferably 99wt% or less. However, the acrylic polymer can be obtained by polymerizing substantially only alkyl (meth) acrylate.

When using compounds in which R is ² In the case of an alkyl (meth) acrylate ester representing a C4-8 chain alkyl group, R in the alkyl (meth) acrylate ester in the monomer component ² The proportion of the alkyl (meth) acrylate representing the C4-8 chain alkyl group is preferably 50% by weight or more because the effect of the present invention can be further exhibited, and is more preferably 70% by weight or more, still more preferably 90% by weight or more, particularly preferably 95% by weight or more, most preferably 99% by weight to 100% by weight.

An acrylic polymer in which n-Butyl Acrylate (BA) accounts for 50wt% or more of the total monomer components is given as an embodiment of the acrylic polymer. In this case, the content of n-Butyl Acrylate (BA) in the entire monomer component is preferably more than 50% by weight and 100% by weight or less because the effect of the present invention can be further exhibited, and the content is more preferably 55% by weight to 95% by weight, still more preferably 60% by weight to 90% by weight, particularly preferably 63% by weight to 85% by weight, most preferably 65% by weight to 80% by weight. The entire monomer component may further include 2-ethylhexyl acrylate (2 EHA) in a proportion smaller than that of n-Butyl Acrylate (BA).

An acrylic polymer in which 2-ethylhexyl acrylate (2 EHA) comprises less than 50wt% of the total monomer components is given as one embodiment of the acrylic polymer. In this case, the content of 2-ethylhexyl acrylate (2 EHA) in the entire monomer component is preferably more than 0wt% and 48wt% or less because the effects of the present invention can be further exhibited, and the content is more preferably 5wt% to 45wt%, still more preferably 10wt% to 43wt%, particularly preferably 15wt% to 40wt%, most preferably 20wt% to 35wt%. The entire monomer component may further include n-Butyl Acrylate (BA) in a ratio greater than 2-ethylhexyl acrylate (2 EHA).

The acrylic polymer may be copolymerized with any other monomer within such a range that the effect of the present invention is not impaired. Other monomers may be used for purposes such as adjusting the glass transition temperature (Tg) of the acrylic polymer or adjusting its pressure sensitive adhesive properties. As the monomer that can improve the cohesive strength and heat resistance of the pressure-sensitive adhesive, for example, sulfonic acid group-containing monomers, phosphoric acid group-containing monomers, cyano group-containing monomers, vinyl esters, and aromatic vinyl compounds are given. Among them, vinyl esters are preferable. Specific examples of vinyl esters include vinyl acetate (VAc), vinyl propionate, and vinyl laurate. Among them, vinyl acetate (VAc) is preferable.

The "other monomers" may be used alone or in combination thereof. The content of the other monomer in the whole monomer component is preferably 0.001 to 40% by weight, more preferably 0.01 to 40% by weight, still more preferably 0.1 to 10% by weight, particularly preferably 0.5 to 5% by weight, most preferably 1 to 3% by weight.

Examples of other monomers that can introduce a functional group capable of serving as a crosslinking base point into the acrylic polymer or that can contribute to improvement of adhesive strength include a hydroxyl group (OH group) -containing monomer, a carboxyl group-containing monomer, an anhydride group-containing monomer, an amide group-containing monomer, an amino group-containing monomer, an imide group-containing monomer, an epoxy group-containing monomer, (meth) acryloyl morpholine, and vinyl ether.

An acrylic polymer copolymerized with a carboxyl group-containing monomer as another monomer is given as one embodiment of the acrylic polymer. Examples of the carboxyl group-containing monomer include Acrylic Acid (AA), methacrylic acid (MAA), carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid. Among them, the carboxyl group-containing monomer is preferably, for example, acrylic Acid (AA) or methacrylic acid (MAA), more preferably Acrylic Acid (AA), because the effects of the present invention can be further exhibited.

When a carboxyl group-containing monomer is used as the other monomer, the content of the other monomer in the whole monomer component is preferably 0.1 to 10% by weight because the effects of the present invention can be further exhibited, and the content is more preferably 0.2 to 8% by weight, still more preferably 0.5 to 5% by weight, particularly preferably 0.7 to 4% by weight, most preferably 1 to 3% by weight.

An acrylic polymer copolymerized with a hydroxyl group-containing monomer as another monomer is given as one embodiment of the acrylic polymer. Examples of the hydroxyl group-containing monomer include: hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate; polypropylene glycol mono (meth) acrylate; and N-hydroxyethyl (meth) acrylamide. Among them, the hydroxyl group-containing monomer is preferably, for example, hydroxyalkyl (meth) acrylate containing a linear alkyl group having 2 to 4 carbon atoms, because the effects of the present invention can be further exhibited, and specific examples thereof include 2-hydroxyethyl acrylate (HEA) and 4-hydroxybutyl acrylate (4 HBA). The hydroxyl group-containing monomer is more preferably 4-hydroxybutyl acrylate (4 HBA).

When a hydroxyl group-containing monomer is used as the other monomer, the content of the other monomer in the whole monomer component is preferably 0.001 to 10% by weight because the effects of the present invention can be further exhibited, and the content is more preferably 0.01 to 5% by weight, still more preferably 0.02 to 2% by weight, particularly preferably 0.03 to 1% by weight, most preferably 0.05 to 0.5% by weight.

The Tg of the base polymer may be, for example, -80 ℃ or higher, because the effects of the present invention can be further exhibited. From the viewpoint of improving the deformability of the pressure-sensitive adhesive layer with respect to the shear direction, the base polymer (suitably an acrylic polymer) is designed so that its Tg may preferably be-15 ℃ or less. In some embodiments, the Tg of the base polymer is, for example, preferably below-25 deg.C, more preferably below-40 deg.C, and still more preferably below-50 deg.C. From the viewpoint of improving the cohesiveness (cohesiveness) and shape-recovery properties of the polymer, the base polymer is designed so that its Tg may be, for example, preferably-70 ℃ or higher (more preferably-65 ℃ or higher, still more preferably-60 ℃ or higher).

The Tg of the base polymer refers to a value determined by the Fox equation (equation) based on the Tg of the homopolymer of each monomer forming the base polymer and the weight fraction of the monomer (copolymerization ratio on a weight basis). The Fox equation is a relationship between Tg of a copolymer and glass transition temperature Tgi of a homopolymer obtained by homopolymerization of each of monomers forming the copolymer, as described below.

1/Tg＝Σ(Wi/Tgi)

In the above Fox equation, tg represents the glass transition temperature (unit: K) of the copolymer, wi represents the weight fraction (copolymerization ratio on the basis of weight) of the monomer "i" in the copolymer, and Tgi represents the glass transition temperature (unit: K) of the homopolymer of the monomer "i". The values described in the known materials are used as Tg for the homopolymer.

Specifically, for example, the following values may each be used as the Tg of the homopolymer.

The values described in "Polymer handbook" (3 rd edition, john Wiley & Sons, inc, 1989) can be used as homopolymer Tg's in addition to those listed above. When a plurality of numerical values are described in the above "handbook of polymers", conventional values are used. For monomers not described in the "handbook of polymers" above, the catalog values for the monomer manufacturer are used. The value obtained by the measurement method described in JP 2007-51271A was used as the Tg of the homopolymer of the monomer which is not described in the above "polymer handbook" and for which the catalog value of the manufacturer of the monomer is not provided.

As a method for synthesizing an acrylic polymer, various polymerization methods such as solution polymerization, emulsion polymerization, bulk polymerization, and suspension polymerization, which are well known, can each be suitably used as a method for obtaining an acrylic polymer. Among these polymerization methods, the solution polymerization method can be preferably used. A one-shot addition system, a continuous supply (dropping) system, a batch supply (dropping) system, or the like in which the entire amount of the monomer component is supplied at once can be suitably used as a monomer supply method in carrying out solution polymerization. The polymerization temperature may be appropriately selected depending on, for example, the kinds of monomers and solvents used and the kind of polymerization initiator. The polymerization temperature is preferably 20 ℃ or more, more preferably 30 ℃ or more, still more preferably 40 ℃ or more, and preferably 170 ℃ or less, more preferably 160 ℃ or less, still more preferably 140 ℃ or less. Such living energy ray radiation polymerization as described below can be used as a method for obtaining an acrylic polymer: photopolymerization by irradiating the monomer component with light such as UV (typically in the presence of a photopolymerization initiator); or radiation polymerization by irradiating the monomer component with radiation such as beta rays or gamma rays.

The solvent (polymerization solvent) used in the solution polymerization may be appropriately selected from any suitable organic solvents. Examples thereof include: aromatic compounds (typically aromatic hydrocarbons), such as toluene; acetates such as ethyl acetate; and aliphatic or alicyclic hydrocarbons such as hexane and cyclohexane.

The initiator (polymerization initiator) used in the polymerization may be appropriately selected from any suitable polymerization initiator according to the kind of the polymerization method. The polymerization initiators may be used alone or in combination thereof. Examples of such polymerization initiators include: azo-based polymerization initiators such as 2,2' -Azobisisobutyronitrile (AIBN); persulfates, such as potassium persulfate; peroxide-based initiators such as benzoyl peroxide and hydrogen peroxide; substituted ethane-based initiators, such as phenyl substituted ethane; and an aromatic carbonyl compound. Other examples of the polymerization initiator include redox-type initiators each obtained by combining a peroxide and a reducing agent.

The amount of the polymerization initiator used is preferably 0.005 to 1 part by weight, more preferably 0.01 to 1 part by weight, relative to 100 parts by weight of the entire monomer components.

The Mw of the acrylic polymer is preferably 10X 10 ⁴ ～500×10 ⁴ More preferably 10X 10 ⁴ ～150×10 ⁴ Still more preferably 20X 10 ⁴ ～75×10 ⁴ Particularly preferably 35X 10 ⁴ ～65×10 ⁴ . Here, mw means a value in terms of standard polystyrene obtained by Gel Permeation Chromatography (GPC). For example, a product available under the model name "HLC-8320GPC" (column: TSKgel GMH-H (S), manufactured by Tosoh Corporation) can be used as the GPC device.

(tackifying resin)

The acrylic pressure-sensitive adhesive may contain a tackifier resin because the effects of the present invention can be further exhibited. Examples of the tackifying resin include rosin-based tackifying resins, terpene-based tackifying resins, hydrocarbon-based tackifying resins, epoxy-based tackifying resins, polyamide-based tackifying resins, elastic-based tackifying resins, phenol-based tackifying resins, and ketone-based tackifying resins. The tackifying resins may be used alone or in combination thereof.

The amount of the tackifier resin used is preferably 5 to 70 parts by weight with respect to 100 parts by weight of the base polymer because the effects of the present invention can be further exhibited, and is more preferably 10 to 60 parts by weight, still more preferably 15 to 50 parts by weight, still further more preferably 20 to 45 parts by weight, particularly preferably 25 to 40 parts by weight, most preferably 25 to 35 parts by weight.

The tackifying resin preferably contains a tackifying resin TL having a softening point of less than 105 ℃ because the effects of the present invention can be further exhibited. The tackifying resin TL can effectively contribute to improving the deformability of the pressure-sensitive adhesive layer in its planar direction (shear direction). The softening point of the tackifier resin used as the tackifier resin TL is preferably 50 to 103 ℃, more preferably 60 to 100 ℃, still more preferably 65 to 95 ℃, particularly preferably 70 to 90 ℃, and most preferably 75 to 85 ℃ from the viewpoint of obtaining a higher effect of improving the deformability.

The softening point of the tackifier resin is defined as a value measured based on a softening point test method (ring and ball method) specified in JIS K5902 and JIS K2207. Specifically, the sample was immediately melted at as low a temperature as possible, and the melted sample was filled into a ring placed on a flat metal plate, while taking care that no air bubbles were present therein. After the sample had cooled, the portion rising from the plane including the upper end of the loop was cut off with a slightly heated knife. Next, a support (ring stand) was charged into a glass container (heating bath) having a diameter of 85mm or more and a height of 127mm or more, and glycerin was poured into the container until the depth thereof became 90mm or more. Next, a steel ball (diameter 9.5mm, weight 3.5 g) and a ring filled with the sample were immersed in glycerin so as not to contact each other, and the temperature of the glycerin was maintained at 20 ℃ ± 5 ℃ for 15 minutes. Next, a steel ball is mounted in the center of the sample surface in the ring, and the result is placed in a fixed position on a support. Next, the distance from the upper end of the ring to the surface of the glycerol was kept at 50mm. The thermometer was placed in the container, and the center position of the mercury ball of the thermometer was set at the same height as the center of the ring, and then the container was heated. The flame of the bunsen burner used in heating is brought into contact with the midpoint between the center and the edge of the bottom of the container, so that the heating can be performed uniformly. After reaching 40 ℃ from the beginning of heating, the rate of rise of the bath temperature must be 5.0 ℃. + -. 0.5 ℃ per minute. The temperature at which the sample gradually softened as it flowed down the loop and eventually came into contact with the bottom plate of the loop was read, and the read temperature was used as the softening point. The softening points of two or more samples were measured simultaneously, and the average of the measured values was taken.

The amount of the tackifier resin TL used is preferably 5 to 50 parts by weight relative to 100 parts by weight of the base polymer because the effects of the present invention can be further exhibited, and is more preferably 10 to 45 parts by weight, still more preferably 15 to 40 parts by weight, particularly preferably 20 to 35 parts by weight, most preferably 25 to 32 parts by weight.

Suitably 1 or 2 or more selected from those of the above listed tackifying resins each having a softening point below 105 ℃ may each be used as tackifying resin TL. The tackifier resin TL preferably contains a rosin-based resin.

Examples of the rosin-based resin that can be preferably used as the tackifying resin TL include rosin esters such as unmodified rosin esters and modified rosin esters. An example of a modified rosin ester is a hydrogenated rosin ester.

The tackifying resin TL preferably contains a hydrogenated rosin ester, because the effects of the present invention can be further exhibited. The softening point of the hydrogenated rosin ester is preferably less than 105 ℃ because the effects of the present invention can be further exhibited, and the softening point is more preferably 50 ℃ to 100 ℃, still more preferably 60 ℃ to 90 ℃, particularly preferably 70 ℃ to 85 ℃, and most preferably 75 ℃ to 85 ℃.

The tackifying resin TL may comprise a non-hydrogenated rosin ester. The term "non-hydrogenated rosin ester" as used herein is a concept that generally refers to those of the above-mentioned rosin esters except hydrogenated rosin esters. Examples of the non-hydrogenated rosin esters include unmodified rosin esters, disproportionated rosin esters, and polymerized rosin esters.

The softening point of the non-hydrogenated rosin ester is preferably less than 105 ℃ because the effects of the present invention can be further exhibited, and the softening point is more preferably 50 ℃ to 100 ℃, still more preferably 60 ℃ to 90 ℃, particularly preferably 70 ℃ to 85 ℃, and most preferably 75 ℃ to 85 ℃.

The tackifier resin TL may contain any other tackifier resin other than the rosin-based resin. 1 or 2 or more kinds appropriately selected from those each having a softening point lower than 105 ℃ in the above-listed tackifying resins may be each used as the other tackifying resins. The tackifying resin TL may comprise, for example, rosin-based resins and terpene resins.

The content of the rosin-based resin in the entire tackifying resin TL is preferably more than 50wt% because the effects of the present invention can be further exhibited, and the content is more preferably 55wt% to 100wt%, still more preferably 60wt% to 99wt%, particularly preferably 65wt% to 97wt%, most preferably 75wt% to 97wt%.

The tackifying resin may comprise a tackifying resin TL and a tackifying resin TH having a softening point of 105 ℃ or higher (preferably 105 ℃ to 170 ℃) in combination, because the effects of the present invention can be further exhibited.

1 or 2 or more kinds appropriately selected from those each having a softening point of 105 ℃ or more among the above listed tackifying resins can be used as the tackifying resin TH each. The tackifying resin TH may contain at least one selected from rosin-based tackifying resins (e.g., rosin esters) and terpene-based tackifying resins (e.g., terpene phenol resins).

(crosslinking agent)

The crosslinking agent may be incorporated into the acrylic pressure sensitive adhesive. The crosslinking agent may be used alone or in combination thereof. The use of the crosslinking agent can impart moderate cohesive strength to the acrylic pressure-sensitive adhesive. The cross-linking agent can be used to adjust the offset and return distances in the retention test. The acrylic pressure-sensitive adhesive containing a crosslinking agent can be obtained by, for example, forming a pressure-sensitive adhesive layer using a pressure-sensitive adhesive composition containing a crosslinking agent. The crosslinking agent may be incorporated into the acrylic pressure-sensitive adhesive in, for example, a post-crosslinking reaction form, a pre-crosslinking reaction form, a form in which a crosslinking reaction is partially carried out, or an intermediate form or a composite form thereof. In typical cases, the crosslinking agent is introduced to the acrylic pressure sensitive adhesive only in the form of a post-crosslinking reaction.

The amount of the crosslinking agent used is preferably 0.005 to 10 parts by weight relative to 100 parts by weight of the base polymer because the effect of the present invention can be further exhibited, and is more preferably 0.01 to 7 parts by weight, still more preferably 0.05 to 5 parts by weight, particularly preferably 0.1 to 4 parts by weight, most preferably 1 to 3 parts by weight.

Examples of the crosslinking agent include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, silicone-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, silane-based crosslinking agents, alkyl etherified melamine-based crosslinking agents, metal chelate-based crosslinking agents, and crosslinking agents such as peroxides. Among them, an isocyanate-based crosslinking agent and an epoxy-based crosslinking agent are preferable, and an isocyanate-based crosslinking agent is more preferable because the effects of the present invention can be further exhibited.

A compound having two or more isocyanate groups in its molecule (including an isocyanate-regenerating functional group obtained by temporarily protecting an isocyanate group by means of, for example, a blocking agent or oligomerization) can be used as the isocyanate-based crosslinking agent. Examples of the isocyanate-based crosslinking agent include: aromatic isocyanates such as toluene diisocyanate and xylene diisocyanate; alicyclic isocyanates such as isophorone diisocyanate; and aliphatic isocyanates such as hexamethylene diisocyanate.

More specific examples of the isocyanate-based crosslinking agent include: lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate and isophorone diisocyanate; aromatic diisocyanates such as 2, 4-tolylene diisocyanate, 4' -diphenylmethane diisocyanate, xylylene diisocyanate and polymethylene polyphenyl isocyanate (polymethylene polyisocyanate); isocyanate adducts such as trimethylolpropane/toluene diisocyanate trimer adduct (for example, trade name: CORONATE L, manufactured by Tosoh Corporation), trimethylolpropane/hexamethylene diisocyanate trimer adduct (for example, trade name: CORONATE HL, manufactured by Tosoh Corporation), and isocyanurate form of hexamethylene diisocyanate (for example, trade name: CORONATE HX, manufactured by Tosoh Corporation); trimethylolpropane adduct of xylylene diisocyanate (e.g., trade name: TAKENATE D110N, manufactured by Mitsui Chemicals, inc.), trimethylolpropane adduct of xylylene diisocyanate (e.g., trade name: TAKENATE D120N, manufactured by Mitsui Chemicals, inc.), trimethylolpropane adduct of isophorone diisocyanate (e.g., trade name: TAKENATE D140N, manufactured by Mitsui Chemicals, inc.), and trimethylolpropane adduct of hexamethylene diisocyanate (e.g., trade name: TAKENATE D160N, manufactured by Mitsui Chemicals, inc.); polyether polyisocyanates, polyester polyisocyanates, and adducts of these compounds with various polyols; and polyisocyanates each of which is polyfunctional with an isocyanurate bond, a biuret bond, an allophanate (allophanate) bond or the like. Among them, aromatic isocyanates and alicyclic isocyanates are preferable from the viewpoint that deformability and cohesive strength can be well balanced.

The amount of the isocyanate-based crosslinking agent used is preferably 0.005 to 10 parts by weight relative to 100 parts by weight of the base polymer because the effects of the present invention can be further exhibited, and is more preferably 0.01 to 7 parts by weight, still more preferably 0.05 to 5 parts by weight, particularly preferably 0.1 to 4 parts by weight, most preferably 1 to 3 parts by weight.

When the monomer component forming the acrylic polymer contains a hydroxyl group-containing monomer, the weight ratio "isocyanate-based crosslinking agent/hydroxyl group-containing monomer" is preferably more than 20 and less than 50 because the effects of the present invention can be further exhibited, and the weight ratio is more preferably 22 to 45, still more preferably 25 to 40, particularly preferably 27 to 40, most preferably 30 to 35.

When the acrylic pressure-sensitive adhesive contains the tackifier resin TL having a softening point of less than 105 ℃, the weight ratio "tackifier resin TL/isocyanate-based crosslinking agent" is preferably more than 2 and less than 15 because the effects of the present invention can be further exhibited, and the weight ratio is more preferably 5 to 13, still more preferably 7 to 12, particularly preferably 7 to 11.

A polyfunctional epoxy compound having two or more epoxy groups in its molecule can be used as the epoxy-based crosslinking agent. Examples of the epoxy-based crosslinking agent include N, N' -tetraglycidyl-m-xylylenediamine, diglycidylaniline, 1, 3-bis (N, N-diglycidylaminomethyl) cyclohexane, 1, 6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether (polyglycidyl poly), sorbitan polyglycidyl ether, trimethylolpropane polyglycidyl ether, adipic acid diglycidyl ester, phthalic acid diglycidyl ester, triglycidyl-tris (2-hydroxyethyl) isocyanurate, resorcinol diglycidyl ether, bisphenol S diglycidyl ether, and epoxy-based resins having two or more epoxy groups in the molecule thereof. As a commercial product of the epoxy-based crosslinking agent, for example, a product available under the trade name "TETRAD C" or "TETRAD X" from Mitsubishi Gas Chemical Company is given.

The amount of the epoxy-based crosslinking agent used is preferably 0.005 to 10 parts by weight with respect to 100 parts by weight of the base polymer because the effects of the present invention can be further exhibited, and is more preferably 0.01 to 5 parts by weight, still more preferably 0.015 to 1 part by weight, particularly preferably 0.15 to 0.5 part by weight, most preferably 0.015 to 0.3 part by weight.

(other Components)

The acrylic pressure-sensitive adhesive may contain any of various additives that are generally used in the field of pressure-sensitive adhesives, such as leveling agents, crosslinking aids, plasticizers, softening agents, fillers, antistatic agents, anti-aging agents, UV absorbers, antioxidants, and light stabilizers, if necessary. Conventionally known additives can be used as such various additives by conventional methods.

< antistatic layer >

The pressure-sensitive adhesive film of the present invention may include an antistatic layer on a surface of the base material layer opposite to the surface thereof having the pressure-sensitive adhesive layer. A mode in which the pressure-sensitive adhesive film of the present invention includes an antistatic layer on the surface of the base material layer opposite to the surface thereof having the pressure-sensitive adhesive layer is preferable because electrification of the pressure-sensitive adhesive film itself can be suppressed and thus dust is hardly adsorbed.

The method of forming the antistatic layer is, for example, a method including applying an antistatic resin formed of an antistatic agent and a resin component, a conductive polymer, or a conductive resin containing a conductive substance onto a base material layer, or a method including vapor-depositing or plating a conductive substance onto a base material layer.

Examples of the antistatic agent to be incorporated into the antistatic resin include: cationic antistatic agents each having a cationic functional group such as a quaternary ammonium salt, a pyridinium salt, and a primary amino group, a secondary amino group, and a tertiary amino group; anionic antistatic agents each having an anionic functional group such as a sulfonate, a sulfate ester salt, a phosphonate, and a phosphate ester salt; zwitterionic antistatic agents, such as alkyl betaines and their derivatives, imidazolines and their derivatives, and alanines and their derivatives; nonionic antistatic agents, such as aminoalcohols and derivatives thereof, glycerol and derivatives thereof, polyethylene glycols and derivatives thereof; and an ion-conductive polymer obtained by polymerizing or copolymerizing any one of monomers each having a cationic, anionic, or zwitterionic conductive group. These antistatic agents may be used alone or in combination thereof.

Examples of cationic antistatic agents include: (meth) acrylic acid copolymers each having a quaternary ammonium group, such as alkyltrimethylammonium salts, amidopropyltrimethylammonium methylsulfate (acylaminopropyltrimethylammonium methosulfate), alkylbenzylmethylammonium salts, acylcholine chloride, and dimethylaminoethyl methacrylate; styrene copolymers each having a quaternary ammonium group, such as polyvinylbenzyltrimethylammonium chloride; and diallylamine copolymers each having a quaternary ammonium group, such as polydiallyldimethylammonium chloride. These antistatic agents may be used alone or in combination thereof.

Examples of the anionic antistatic agent include alkylsulfonates, alkylbenzenesulfonates, alkylsulfate salts, alkyl ethoxy sulfate salts, alkyl phosphate salts and sulfonic acid group-containing styrene copolymers. These antistatic agents may be used alone or in combination thereof.

Examples of zwitterionic antistatic agents include alkyl betaines, alkyl imidazole betaines, and carbonyl betaine graft copolymers. These antistatic agents may be used alone or in combination thereof.

Examples of the nonionic antistatic agent include fatty acid alkanolamides, bis (2-hydroxyethyl) alkylamines, polyoxyethylene alkylamines, fatty acid glycerides, polyoxyethylene glycol fatty acid esters, sorbitan fatty acid esters, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkyl ethers, polyethylene glycols, polyoxyethylene diamines, copolymers formed from polyethers, polyesters, and polyamides, and methoxypolyethylene glycol (meth) acrylates. These antistatic agents may be used alone or in combination thereof.

Examples of the conductive polymer include polyaniline, polypyrrole, and polythiophene. These conductive polymers may be used alone or in combination thereof.

Examples of the conductive substance include tin oxide, antimony oxide, indium oxide, cadmium oxide, titanium oxide, zinc oxide, indium, tin, antimony, gold, silver, copper, aluminum, nickel, chromium, titanium, iron, cobalt, and copper iodide, and an alloy or a mixture thereof. These conductive substances may be used alone or in combination thereof.

As the resin component used in the antistatic resin and the conductive resin, for example, general-purpose resins such as polyester resin, acrylic resin, polyethylene resin, polyurethane resin, melamine resin, or epoxy resin are used. When a high molecular type antistatic agent is used, the resin component may not be incorporated. In addition, as the crosslinking agent used as the antistatic resin component, for example, the following components may be incorporated: methylolated or hydroxyalkylated melamine-based compounds, urea-based compounds, glyoxal-based (glyoxal-based) compounds, or acrylamide-based compounds; an epoxy compound; and an isocyanate compound.

The antistatic layer is formed by, for example, a method including diluting the above antistatic resin, conductive polymer, conductive resin, or the like with a solvent such as an organic solvent or water, applying a coating liquid to a substrate or the like, and drying the liquid.

Examples of the diluting solution used in the formation of the antistatic layer include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexanone, n-hexane, toluene, xylene, methanol, ethanol, n-propanol, isopropanol, and water. These solvents may be used alone or in combination thereof.

Any suitable coating method is suitably used as the coating method in the formation of the antistatic layer. Examples of such coating methods include roll coating, gravure coating, reverse coating, roll brush coating, spray coating, air knife coating, dipping, and curtain coating.

Any suitable method is suitably used as the method for vapor deposition or electroplating of the conductive substance. Examples of such methods include vacuum deposition, sputtering, ion plating, chemical vapor deposition, spray pyrolysis, electroless plating, and electroplating methods.

Any suitable thickness may be used as the thickness of the antistatic layer within such a range that the effect of the present invention is not impaired. The thickness of the antistatic layer is preferably 0.001 μm to 5 μm because the effects of the present invention can be further exhibited, and more preferably 0.005 μm to 1 μm.

< topcoat layer >

The pressure-sensitive adhesive film of the present invention may include a topcoat layer on the surface of the substrate layer opposite to the surface thereof having the pressure-sensitive adhesive layer. The topcoat preferably comprises a binder, and more preferably a binder and a lubricious additive (slip additive). The mode in which the pressure-sensitive adhesive film of the present invention includes a top coat layer is preferable because the scratch resistance of the pressure-sensitive adhesive film is improved.

< Binder >

Any suitable resin may be used as the binder within such a range that the effect of the present invention is not impaired. Such a resin is preferably at least one selected from the group consisting of polyester resins and polyurethane-based resins, because the effects of the present invention can be further exhibited.

(polyester resin)

When the polyester resin is incorporated into the binder, the polyester resin may be used alone or in combination thereof.

The polyester resin is preferably a resin containing a polyester as a main component. The content of the polyester in the polyester resin is preferably more than 50wt%, more preferably 75wt% or more, and still more preferably 90wt% or more.

The polyester preferably has a structure in which at least one compound (polycarboxylic acid component) selected from polycarboxylic acids (preferably dicarboxylic acids) each having two or more carboxyl groups in the molecule thereof and derivatives thereof (for example, anhydrides, esterification products, and halides of polycarboxylic acids) and at least one compound (polyol component) selected from polyhydric alcohols (preferably glycols) each having two or more hydroxyl groups in the molecule thereof are condensed with each other.

Examples of compounds that can be used as the polycarboxylic acid component include: aliphatic dicarboxylic acids such as oxalic acid, malonic acid, difluoromalonic acid, alkylmalonic acid, succinic acid, tetrafluorosuccinic acid, alkylsuccinic acid, (±) -malic acid, meso-tartaric acid, itaconic acid, maleic acid, methylmaleic acid, fumaric acid, methylfumaric acid, acetylenedicarboxylic acid, glutaric acid, hexafluoroglutaric acid, methylglutaric acid, glutaconic acid, adipic acid, dithioadipic acid, methyladipic acid, dimethyladipic acid, tetramethyladipic acid, methyleneadipic acid, muconic acid, galactaric acid, pimelic acid, suberic acid, perfluorosuberic acid (perfluorosubic acid), 3, 6-tetramethylsuberic acid, azelaic acid, sebacic acid, perfluorosebacic acid, brassylic acid, dodecanedicarboxylic acid, tridecyldicarboxylic acid and tetradecyldicarboxylic acid; alicyclic dicarboxylic acids such as cycloalkyldicarboxylic acid (e.g., 1, 4-cyclohexanedicarboxylic acid or 1, 2-cyclohexanedicarboxylic acid), 1,4- (2-norbornene) dicarboxylic acid, 5-norbornene-2, 3-dicarboxylic acid (bicycloheptenedicarboxylic acid), adamantanedicarboxylic acid and spiroheptanedicarboxylic acid; an aromatic dicarboxylic acid(s) which is (are) an aromatic dicarboxylic acid(s), such as phthalic acid, isophthalic acid, dithioisophthalic acid, methylisophthalic acid, dimethylisophthalic acid, chloromisophthalic acid, dichloroisophthalic acid, terephthalic acid, methylterephthalic acid, dimethylterephthalic acid, chloroterephthalic acid, bromoterephthalic acid, naphthalenedicarboxylic acid, fluorenone dicarboxylic acid, anthracenedicarboxylic acid, diphenyldicarboxylic acid, biphenylenedicarboxylic acid (biphenylenedicarboxylic acid) dimethylbiphenylenedicarboxylic acid, 4 "-p-phenylenedicarboxylic acid, 4" -p-quaternarybenzenedicarboxylic acid, bibenzyldicarboxylic acid, azobenzenedicarboxylic acid, homophthalic acid, terephthallic acid, phenylenedipropionic acid, naphthalenedicarboxylic acid, naphthalenedipropionic acid, biphenyldiacetic acid, biphenyldipropionic acid, 3' - [4,4' - (methylenedi-p-biphenylene) dipropionic acid, 4' -bibenzyldiacetic acid, 3' - (4, 4' -bibenzyl) dipropionic acid, and oxo-di-p-phenylenediacetic acid; anhydrides of any of the foregoing polycarboxylic acids; esters (e.g., alkyl esters, monoesters, or diesters) of any of the foregoing polycarboxylic acids; and acid halides (e.g., diacid chlorides) corresponding to any of the above-described polycarboxylic acids.

Suitable examples of compounds that can be used as the polycarboxylic acid component include: aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid and naphthalenedicarboxylic acid, and anhydrides thereof; aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid, succinic acid, fumaric acid, maleic acid, bicycloheptenedicarboxylic acid and 1, 4-cyclohexanedicarboxylic acid, and anhydrides thereof; and lower alkyl esters of the above dicarboxylic acids (for example, esters with monohydric alcohols having 1 to 3 carbon atoms).

Examples of compounds which can be used as the polyol component include glycols such as ethylene glycol, propylene glycol, 1, 2-propanediol, 1, 3-butanediol, 1, 4-butanediol, neopentyl glycol, 1, 5-pentanediol, 1, 6-hexanediol, 3-methylpentanediol, diethylene glycol, 1, 4-cyclohexanedimethanol, 3-methyl-1, 5-pentanediol, 2-methyl-1, 3-propanediol, 2-diethyl-1, 3-propanediol, 2-butyl-2-ethyl-1, 3-propanediol, benzenedimethanol, hydrogenated bisphenol A and bisphenol A. Other examples thereof include alkylene oxide adducts (e.g., ethylene oxide adducts and propylene oxide adducts) of these compounds.

The polyester resin preferably contains a water-dispersible polyester, and more preferably contains a water-dispersible polyester as a main component. Such a water-dispersible polyester may be, for example, a polyester in which water dispersibility is improved by introducing a hydrophilic functional group (for example, at least one selected from hydrophilic functional groups such as a sulfonic acid metal salt group, a carboxyl group, an ether group, and a phosphoric acid group) to a polymer. As a method of introducing a hydrophilic functional group into a polymer as described above, any suitable method may be suitably employed, such as a method comprising copolymerizing compounds each having a hydrophilic functional group or a method comprising modifying a polyester or a precursor thereof (for example, a polycarboxylic acid component or a polyol component, or an oligomer thereof) to produce a hydrophilic functional group. A preferable water-dispersible polyester is, for example, a polyester (copolyester) obtained by copolymerizing compounds each having a hydrophilic functional group.

The polyester resin used as the binder may contain a saturated polyester as a main component, or may contain an unsaturated polyester as a main component. The main component of the polyester resin is preferably a saturated polyester, more preferably a saturated polyester (for example, a saturated copolyester) which imparts water dispersibility thereto. Such a polyester resin (polyester resin which can be prepared in the form of an aqueous dispersion) can be synthesized by any suitable method, or a commercially available product thereof is readily available.

The molecular weight of the polyester resin as a weight average molecular weight (Mw) in terms of standard polystyrene as measured by Gel Permeation Chromatography (GPC) is preferably 0.5X 10 ⁴ ～15×10 ⁴ More preferably 1X 10 ⁴ ～6×10 ⁴ 。

The glass transition temperature (Tg) of the polyester resin is preferably from 0 ℃ to 100 ℃, more preferably from 10 ℃ to 80 ℃.

(polyurethane resin)

When the polyurethane-based resin is incorporated into the adhesive, the polyurethane-based resin may be used alone or in combination thereof.

The polyurethane-based resin is preferably a polyurethane-based resin obtained by curing a composition containing the polyol (a) and the polyfunctional isocyanate compound (B).

The polyols (a) may be used alone or in combination thereof.

Any suitable polyol may be used as the polyol (a) as long as the polyol has two or more OH groups. Examples of such a polyol (a) include a polyol (diol) having two OH groups, a polyol (triol) having three OH groups, a polyol (tetraol) having four OH groups, a polyol (pentaol) having five OH groups, and a polyol (hexaol) having six OH groups.

Diols having more than two OH groups, such as ethylene glycol or propylene glycol, are preferably used as essential components of the polyol (A). When a diol is used as an essential component as described above, for example, a polyurethane-based cured resin excellent in the strength of a coating film after curing, adhesion to a substrate, and retention of an additive substance can be provided. The content of the diol in the polyol (A) is preferably from 30% by weight to 100% by weight, more preferably from 50% by weight to 100% by weight, still more preferably from 70% by weight to 100% by weight, still further more preferably from 90% by weight to 100% by weight, particularly preferably from 95% by weight to 100% by weight, most preferably substantially 100% by weight.

Examples of the polyol (A) include ethylene glycol, diethylene glycol, propylene glycol, 1, 3-butanediol, 1, 4-butanediol, neopentyl glycol, 3-methyl-1, 5-pentanediol, 2-butyl-2-ethyl-1, 3-propanediol, 2, 4-diethyl-1, 5-pentanediol, 1, 2-hexanediol, 1, 6-hexanediol, 1, 8-octanediol, 1, 9-nonanediol, 2-methyl-1, 8-octanediol, 1, 8-decanediol, octadecanediol, glycerin, trimethylolpropane, pentaerythritol, hexanetriol, polyethylene glycol, polypropylene glycol, polyester polyol, polyether polyol, polycaprolactone polyol, polycarbonate polyol and castor oil-based polyol.

The polyester polyol can be obtained by, for example, an esterification reaction between a polyol component and an acid component.

Examples of the acid component include succinic acid, methylsuccinic acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, 1, 12-dodecanedioic acid, 1, 14-tetradecanedioic acid, dimer acid, 2-methyl-1, 4-cyclohexanedicarboxylic acid, 2-ethyl-1, 4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, isophthalic acid, terephthalic acid, 1, 4-naphthalenedicarboxylic acid, 4' -biphenyldicarboxylic acid, and anhydrides thereof.

One example of the polyether polyol is a polyether polyol obtained by addition polymerization of an alkylene oxide such as ethylene oxide, propylene oxide or butylene oxide using, for example, water, a low molecular weight polyol (e.g., propylene glycol, ethylene glycol, glycerin, trimethylolpropane or pentaerythritol), a bisphenol (e.g., bisphenol a) or a dihydroxybenzene (e.g., catechol, resorcinol or hydroquinone) as an initiator. Specific examples thereof include polyethylene glycol, polypropylene glycol and polybutylene glycol.

An example of a polycaprolactone polyol is a caprolactone-based polyester diol obtained by ring-opening polymerization of a cyclic ester monomer such as epsilon-caprolactone or sigma-valerolactone.

Examples of the polycarbonate polyol include: a polycarbonate polyol obtained by subjecting the above-mentioned polyol component and phosgene to a polycondensation reaction; polycarbonate polyols obtained by the transesterification condensation of the above polyol components with carbonic acid diesters such as dimethyl carbonate, diethyl carbonate, dipropyl carbonate, diisopropyl carbonate, dibutyl carbonate, ethylbutyl carbonate, ethylene carbonate, propylene carbonate, diphenyl carbonate, or dibenzyl carbonate; a copolymerized polycarbonate polyol obtained by using two or more of the above-mentioned polyol components in combination; a polycarbonate polyol obtained by subjecting any of the various polycarbonate polyols described above to an esterification reaction with a carboxyl group-containing compound; a polycarbonate polyol obtained by subjecting any one of the above various polycarbonate polyols to an etherification reaction with a hydroxyl group-containing compound; a polycarbonate polyol obtained by subjecting any of the above various polycarbonate polyols to an ester exchange reaction with an ester compound; a polycarbonate polyol obtained by subjecting any of the above various polycarbonate polyols to an ester exchange reaction with a hydroxyl group-containing compound; a polyester polycarbonate polyol obtained by subjecting any of the various polycarbonate polyols described above to a polycondensation reaction with a dicarboxylic acid compound; and a copolymerized polyether polycarbonate polyol obtained by copolymerizing any of the above various polycarbonate polyols with an alkylene oxide.

The castor oil-based polyol is, for example, a castor oil-based polyol obtained by reacting a castor oil fatty acid and the above-mentioned polyol component with each other. The castor oil-based polyol is specifically, for example, a castor oil-based polyol obtained by reacting a castor oil fatty acid and a polypropylene glycol with each other.

The polyfunctional isocyanate compound (B) may be used alone or in combination thereof.

Any suitable polyfunctional isocyanate compound that can be used in the urethanization reaction may be used as the polyfunctional isocyanate compound (B). Examples of such a polyfunctional isocyanate compound (B) include polyfunctional aliphatic isocyanate compounds, polyfunctional alicyclic isocyanates, and polyfunctional aromatic isocyanate compounds.

Examples of the polyfunctional aliphatic isocyanate compound include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1, 2-propylene diisocyanate, 1, 3-butylene diisocyanate, dodecamethylene diisocyanate, and 2, 4-trimethylhexamethylene diisocyanate.

Examples of the polyfunctional alicyclic isocyanate compound include 1, 3-cyclopentene diisocyanate, 1, 3-cyclohexane diisocyanate, 1, 4-cyclohexane diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated toluene diisocyanate, and hydrogenated tetramethylxylylene diisocyanate.

Examples of the polyfunctional aromatic isocyanate compound include phenylene diisocyanate, 2, 4-tolylene diisocyanate, 2, 6-tolylene diisocyanate, 2 '-diphenylmethane diisocyanate, 4' -toluidine diisocyanate (tolulidine diisocyanate), 4 '-diphenyl ether diisocyanate, 4' -diphenyl diisocyanate, 1, 5-naphthalene diisocyanate, and xylylene diisocyanate.

Examples of the polyfunctional isocyanate compound (B) also include trimethylolpropane adducts, biuret bodies obtained by reaction with water, and trimers each having an isocyanurate ring of the above-mentioned various polyfunctional isocyanate compounds. In addition, these compounds may be used in combination thereof.

The content of the polyfunctional isocyanate compound (B) is preferably 5 to 60% by weight, more preferably 8 to 60% by weight, still more preferably 10 to 60% by weight, relative to the polyol (A). When the content of the polyfunctional isocyanate compound (B) is adjusted within this range, the effects of the present invention can be further exhibited.

The polyurethane-based resin is typically obtained by curing a composition comprising a polyol (a) and a polyfunctional isocyanate compound (B). Any suitable other components other than the polyol (a) and the polyfunctional isocyanate compound (B) may be incorporated into such a composition within such a range that the effect of the present invention is not impaired. Examples of such other components include catalysts, any other resin component other than the polyurethane-based resin, tackifiers, inorganic fillers, organic fillers, metal powders, pigments, foils, softeners, plasticizers, anti-aging agents, conductive agents, antioxidants, UV absorbers, light stabilizers, surface lubricants, leveling agents, corrosion inhibitors, heat stabilizers, polymerization inhibitors, lubricants, and solvents.

Within such a range that the effect of the present invention is not impaired, any suitable method such as a urethanization reaction method including the use of bulk polymerization, solution polymerization or the like may be used as a method of curing a composition comprising the polyol (a) and the polyfunctional isocyanate compound (B) to provide a polyurethane-based resin.

(other resins)

The topcoat layer may further contain any other resin (for example, at least one resin selected from the group consisting of acrylic resins, acrylic-styrene resins, acrylic-silicone resins, polysilazane resins, fluorine resins, and polyolefin resins) as a binder in such a range that the performance of the pressure-sensitive adhesive film is not greatly impaired. As a preferred embodiment of the top coat layer, the binder of the top coat layer is substantially formed only of at least one selected from the group consisting of polyester resins and polyurethane-based resins, and the ratio of the at least one selected from the group consisting of polyester resins and polyurethane-based resins to the binder is preferably 98wt% to 100wt%, more preferably 99wt% to 100wt%, still more preferably 99.5wt% to 100wt%. The proportion of binder to the whole of the top coat is preferably from 15 to 95wt%, more preferably from 25 to 80wt%.

< lubricating additives >

The top coat layer preferably contains an ester of a higher fatty acid and a higher alcohol (hereinafter sometimes referred to as "wax ester") as a lubricating additive.

The "higher fatty acid" is preferably a carboxylic acid having 8 or more carbon atoms, and the number of carbon atoms thereof is more preferably 10 or more, and still more preferably 10 to 40. The carboxylic acid is preferably a monocarboxylic acid.

The "higher alcohol" is preferably an alcohol having 6 or more carbon atoms, and the number of carbon atoms thereof is more preferably 10 or more, and still more preferably 10 to 40. The alcohol is preferably a monohydric or dihydric alcohol, more preferably a monohydric alcohol.

A topcoat layer of such a composition comprising such a wax ester and the above binder in combination is less likely to whiten even when kept under high-temperature and high-humidity conditions. Therefore, a pressure-sensitive adhesive film including a substrate having such a top coat layer may have higher appearance quality.

Possible reasons why excellent whitening resistance (e.g., a property that the topcoat is hardly whitened even when held under high-temperature and high-humidity conditions) is achieved by the topcoat of the above composition are, for example, the following. That is, it is assumed that the silicone-based lubricant used so far exudes to the surface of the topcoat layer to exhibit a function of imparting lubricity to the surface. However, the degree of bleeding of such silicone-based lubricants tends to vary depending on storage conditions (e.g., temperature, humidity, or elapsed time). Therefore, for example, when the amount of use of the silicone-based lubricant is set so that in the case where the pressure-sensitive adhesive film is stored under usual storage conditions (e.g., 25 ℃ and 50% rh), it is possible to obtain appropriate lubricity over a relatively long period of time (e.g., about 3 months) from the time point immediately after the manufacture of the pressure-sensitive adhesive film, in the case where the pressure-sensitive adhesive film is stored under high temperature and high humidity conditions (e.g., 60 ℃ and 95% rh) for 2 weeks, exudation of the lubricant excessively proceeds. The silicone-based lubricant excessively oozed as described above may whiten the top coat (even the pressure-sensitive adhesive film).

A specific combination of a wax ester as a lubricating additive and a polyester resin as a binder is used as a preferred embodiment of the top coat. This combination of lubricant additives and binders makes the extent to which the wax ester bleeds from the topcoat less sensitive to storage conditions. Therefore, the whitening resistance of the pressure-sensitive adhesive film can be improved.

1 or more compounds each represented by the general formula (W) can each be preferably used as the wax ester.

X-COO-Y (W)

In formula (W), X and Y each independently represent a hydrocarbon group having 10 to 40 carbon atoms, and the number of carbon atoms thereof is more preferably 10 to 35, still more preferably 14 to 35, and particularly preferably 20 to 32. When the number of carbon atoms is too small, the effect of imparting lubricity to the top coat by the wax ester may be insufficient. The hydrocarbon group may be a saturated hydrocarbon group, or may be an unsaturated hydrocarbon group. The hydrocarbon group is preferably a saturated hydrocarbon group. The hydrocarbon group may have a structure containing an aromatic ring, a structure containing no aromatic ring (aliphatic hydrocarbon group), a structure containing an aliphatic ring (alicyclic hydrocarbon group), or a chain hydrocarbon group (including linear and branched groups).

The wax ester is a compound in which X and Y in formula (W) each independently represent a chain alkyl group having preferably 10 to 40 carbon atoms, more preferably a straight chain alkyl group having 10 to 40 carbon atoms. Specific examples of such compounds include myricyl Cerolate (CH) ₃ (CH ₂ ) ₂₄ COO(CH ₂ ) ₂₉ CH ₃ ) Melissyl palmitate (CH) ₃ (CH ₂ ) ₁₄ COO(CH ₂ ) ₂₉ CH ₃ ) Cetyl palmitate (CH) ₃ (CH ₂ ) ₁₄ COO(CH ₂ ) ₁₅ CH ₃ ) And stearyl stearate (CH) ₃ (CH ₂ ) ₁₆ COO(CH ₂ ) ₁₇ CH ₃ )。

The melting point of the wax ester is preferably 50 ℃ or higher, more preferably 60 ℃ or higher, still more preferably 70 ℃ or higher, and particularly preferably 75 ℃ or higher. Such wax esters can achieve a higher whitening resistance. The melting point of the wax ester is preferably 100 ℃ or lower. Such wax esters have a high lubricity-imparting effect, and therefore can form a top coat having higher scratch resistance. The melting point of the wax ester is preferably 100 ℃ or lower, also because an aqueous dispersion of the wax ester is easy to prepare. For example, myricyl cerolate may be preferably used as such a wax ester.

Natural waxes comprising such wax esters can be used as a starting material for the top coat. In such a natural wax, the content of the wax ester (when the wax contains 2 or more wax esters, the sum of their contents) is preferably more than 50wt%, more preferably 65wt% or more, still more preferably 75wt% or more, relative to the nonvolatile component (NV). Examples of such natural waxes include: vegetable waxes such as carnauba wax (typically containing myricyl cerolate in a proportion of preferably 60wt% or more, more preferably 70wt% or more, still more preferably 80wt% or more) and carnauba wax; and animal waxes such as beeswax and spermaceti wax. The melting point of the natural wax is preferably 50 ℃ or higher, more preferably 60 ℃ or higher, still more preferably 70 ℃ or higher, and particularly preferably 75 ℃ or higher. Chemically synthesized wax esters may be used as a raw material for the top coat, or natural waxes refined to wax esters having higher purity may be used. These raw materials may be used alone or in combination thereof.

The proportion of the lubricant additive relative to the entire topcoat is preferably from 5% to 50%, more preferably from 10% to 40%. When the content of the lubricant additive is too small, the scratch resistance of the layer may be easily reduced. When the content of the lubricant additive is excessively large, the whitening resistance improving effect of the layer tends to be insufficient.

In addition to the wax ester, the topcoat may also contain any other lubricious additives. Examples of other lubricant additives include various waxes other than wax esters, such as petroleum-based waxes (e.g., paraffin wax), mineral-based waxes (e.g., montan wax), higher fatty acids (e.g., wax acid), and neutral fats (e.g., palmitic acid triglyceride). In addition, in addition to the wax ester, a silicone-based lubricant, a fluorine-based lubricant, or the like may be incorporated into the layer. A preferred embodiment of the topcoat is one in which the layer is substantially free of silicone-based lubricants and fluorine-based lubricants. For example, the total content of the silicone-based lubricant and the fluorine-based lubricant in the entire topcoat layer is preferably 0.01wt% or less, and more preferably detection limit or less.

The top coat layer may contain additives such as an antistatic component, a crosslinking agent, an antioxidant, a colorant (e.g., a pigment or a dye), a fluidity modifier (e.g., a thixotropic agent or a thickener), a film forming aid, a surfactant (e.g., an antifoaming agent or a dispersing agent), or a preservative, as necessary.

< antistatic component of topcoat layer >

As a preferred embodiment, the topcoat comprises an antistatic component. The antistatic component is a component that can exhibit an preventing or inhibiting effect on electrification of the pressure-sensitive adhesive film. When an antistatic component is incorporated into the topcoat layer, for example, an organic or inorganic conductive substance, and various antistatic agents may be each used as the antistatic component. In addition, antistatic agents that can be used in the above antistatic layer can be used individually.

Examples of the organic conductive substance include: cationic antistatic agents each having a cationic functional group such as a quaternary ammonium salt, a pyridinium salt, a primary amino group, a secondary amino group, and a tertiary amino group; anionic antistatic agents each having an anionic functional group such as a sulfonate, sulfate ester, phosphonate, phosphate ester, and the like; zwitterionic antistatic agents, such as alkylbetaines and their derivatives, imidazolines and their derivatives, and alanines and their derivatives; nonionic antistatic agents, such as aminoalcohols and derivatives thereof, glycerol and derivatives thereof, polyethylene glycols and derivatives thereof; ion-conductive polymers each obtained by polymerizing or copolymerizing a monomer having the above-mentioned cationic, anionic, or zwitterionic conductive group (e.g., a quaternary ammonium salt group); and conductive polymers such as polythiophene, polyaniline, polypyrrole, polyethyleneimine and allylamine-based polymers. Such antistatic agents may be used alone or in combination thereof.

Examples of the inorganic conductive substance include tin oxide, antimony oxide, indium oxide, cadmium oxide, titanium oxide, zinc oxide, indium, tin, antimony, gold, silver, copper, aluminum, nickel, chromium, titanium, iron, cobalt, copper iodide, ITO (indium oxide/tin oxide), and ATO (antimony oxide/tin oxide). Such inorganic conductive substances may be used alone or in combination thereof.

Examples of the antistatic agent include cationic antistatic agents, anionic antistatic agents, zwitterionic antistatic agents, nonionic antistatic agents, and ion-conductive polymers obtained by polymerizing or copolymerizing monomers having the above-mentioned cationic, anionic or zwitterionic conductive groups.

When the top coat layer contains an antistatic component, the antistatic component preferably contains an organic conductive substance. Various conductive polymers can each be preferably used as the organic conductive substance. This constitution can achieve both satisfactory antistatic properties and high scratch resistance at the same time.

Examples of the conductive polymer include polythiophene, polyaniline, polypyrrole, polyethyleneimine, and allylamine-based polymers. Such conductive polymers may be used alone or in combination thereof. In addition, any such polymer may be used in combination with any other antistatic component (e.g., an inorganic conductive substance or an antistatic agent).

The amount of the conductive polymer used is preferably 1 to 100 parts by weight, more preferably 2 to 70 parts by weight, and still more preferably 3 to 50 parts by weight, based on 100 parts by weight of the binder in the top coat layer. When the amount of the conductive polymer used is too small, its antistatic effect is reduced. When the amount of the conductive polymer used is too large, the compatibility of the conductive polymer in the topcoat tends to be insufficient, thereby degrading the appearance quality of the topcoat or reducing the solvent resistance thereof.

The conductive polymer is preferably, for example, polythiophene or polyaniline. The weight average molecular weight Mw of the polythiophene in terms of polystyrene is preferably 40X 10 ⁴ Hereinafter, more preferably 30X 10 ⁴ The following. The weight average molecular weight Mw of polyaniline in terms of polystyrene is preferably 50X 10 ⁴ Hereinafter, more preferably 30X 10 ⁴ The following. The weight average molecular weight Mw of the conductive polymer in terms of polystyrene is preferably 0.1X 10 ⁴ More preferably 0.5X 10 or more ⁴ The above. The term "polythiophene" as used herein refers to polymers of unsubstituted thiophene or substituted thiophene. The polymer of the substituted thiophene is, for example, poly (3, 4-ethylenedioxythiophene).

When a method comprising applying a coating material for forming a topcoat layer to a substrate and drying or curing the coating material is used as the formation method of the topcoat layer, as the conductive polymer used in the preparation of the coating material, a conductive polymer in the form of being dissolved or dispersed in water can be preferably usedPolymer (aqueous conductive polymer solution). Such an aqueous conductive polymer solution can be prepared, for example, by dissolving or dispersing a conductive polymer having a hydrophilic functional group (a conductive polymer which can be synthesized by a method such as copolymerization of monomers each having a hydrophilic functional group in its molecule) in water. Examples of hydrophilic functional groups include sulfo group, amino group, amide group, imino group, hydroxyl group, mercapto group, hydrazino group, carboxyl group, quaternary ammonium group, sulfate group (-O-SO) ₃ H) And phosphate groups (e.g., -O-PO (OH) ₂ ). Such hydrophilic functional groups may form salts. Commercial products of aqueous polythiophene solutions are, for example, a series of products available under the trade name "denatorn" from Nagase ChemteX Corporation. Commercially available products of aqueous polyaniline sulfonic acid solutions are, for example, products available under the trade name "aqua-PASS" from Mitsubishi Rayon co.

Aqueous solutions of polythiophenes are preferably used in the preparation of the coating materials. The aqueous polythiophene solution is preferably an aqueous polythiophene solution containing polystyrene sulfonate (PSS) (for example, a form in which PSS is added as a dopant to polythiophene). This aqueous polythiophene solution may preferably contain polythiophene and PSS in a mass ratio of 1. The total content of polythiophene and PSS in the polythiophene aqueous solution is preferably 1wt% to 5wt%. A commercial product of such an aqueous polythiophene solution is, for example, a product available under the trade name "Baytron" from h.c. starck GmbH. When the aqueous polythiophene solution containing PSS is used as described above, the total amount of polythiophene and PSS is preferably 5 to 200 parts by weight, more preferably 10 to 100 parts by weight, and still more preferably 25 to 70 parts by weight, relative to 100 parts by weight of the binder.

The topcoat layer may contain both the conductive polymer and any other 1 or more antistatic components (e.g., organic conductive substances other than the conductive polymer, inorganic conductive substances, and antistatic agents), as needed. Preferably, the topcoat is substantially free of any antistatic components other than the conductive polymer. That is, it is preferred that the antistatic component in the topcoat be formed substantially only from the conductive polymer.

< crosslinking agent >

The topcoat preferably comprises a crosslinker. A crosslinking agent appropriately selected from crosslinking agents used for crosslinking of general resins such as a melamine-based crosslinking agent, an isocyanate-based crosslinking agent, and an epoxy-based crosslinking agent may be used as the crosslinking agent. The use of any such crosslinking agent can achieve at least one of the effects of improvement in scratch resistance of the layer, improvement in solvent resistance thereof, improvement in printing adhesion thereof, and reduction in friction coefficient thereof (i.e., improvement in lubricity thereof). The crosslinking agent preferably contains a melamine-based crosslinking agent. The crosslinking agent of the top coat layer may be formed substantially only of the melamine-based crosslinking agent (melamine-based resin) (that is, the layer may be substantially free of any crosslinking agent other than the melamine-based crosslinking agent).

< one preferred mode of topcoat layer >

One preferred mode of the topcoat layer is a mode in which the topcoat layer contains a binder containing a polyurethane-based resin and an antistatic component when the material of the base material layer is at least one selected from polyimide and polyetheretherketone. When a binder containing a polyurethane-based resin is used as the binder of the antistatic component of the top coat layer as described above, the top coat layer becomes excellent in coating formability on the surface of the base material layer using at least one selected from polyimide and polyether ether ketone as a material. Therefore, the appearance of the topcoat can be improved, and excellent antistatic properties can be exhibited.

In many cases, binders containing polyester resins are preferred as binders for the antistatic component of the top coat. However, in some cases, the affinity of the binder containing a polyester resin for such a specific base material layer where the material of the base material layer is at least one selected from polyimide and polyetheretherketone is low, and therefore the appearance may be deteriorated after application and formation of the topcoat layer, or the layer may not exhibit excellent antistatic property. As described above, according to the mode in which when the material of the base material layer is at least one selected from the group consisting of polyimide and polyether ether ketone, the topcoat layer contains the binder containing the polyurethane-based resin and the antistatic component, the coating formability of the topcoat layer on the surface of the base material layer becomes excellent. Therefore, the appearance of the topcoat can be improved, and excellent antistatic properties can be exhibited.

< formation of topcoat layer >

The top coat layer can be suitably formed by a method including applying a liquid composition (coating material for top coat layer formation) obtained by dispersing or dissolving the above-described resin component and additives used as needed in an appropriate solvent onto the substrate. For example, a method including applying a coating material to the first surface of the base material, drying the coating material, and performing a curing treatment (for example, heat treatment or UV treatment) as needed may be preferably employed. The nonvolatile component (NV) of the coating material is preferably 5% by weight or less, more preferably 0.05% by weight to 5% by weight, still more preferably 0.05% by weight to 1% by weight, and particularly preferably 0.10% by weight to 1% by weight. When forming a topcoat layer having a small thickness, the NV of the coating material is set to preferably 0.05wt% to 0.50wt%, more preferably 0.10wt% to 0.30wt%. The use of a coating material having a low NV as described above can result in a more uniform topcoat.

The solvent in which the topcoat layer-forming component can be stably dissolved or dispersed is preferably used as the solvent for forming the topcoat layer-forming coating material. Such a solvent may be an organic solvent, water, or a mixed solvent thereof. The organic solvent is, for example, at least one selected from the group consisting of: esters, such as ethyl acetate; ketones such as methyl ethyl ketone, acetone and cyclohexanone; cyclic ethers such as Tetrahydrofuran (THF) and dioxane; aliphatic or alicyclic hydrocarbons such as n-hexane and cyclohexane; aromatic hydrocarbons such as toluene and xylene; aliphatic or alicyclic alcohols such as methanol, ethanol, n-propanol, isopropanol and cyclohexanol; and glycol ethers such as alkylene glycol monoalkyl ethers (e.g., ethylene glycol monomethyl ether or ethylene glycol monoethyl ether) and dialkylene glycol monoalkyl ethers. Among them, water or a mixed solvent containing water as a main component (for example, a mixed solvent of water and ethanol) is preferable as a solvent for forming the top coat forming coating material.

< Properties of topcoat layer >

The thickness of the topcoat is preferably 3nm to 500nm, more preferably 3nm to 100nm, and still more preferably 3nm to 60nm. When the thickness of the top coat layer is excessively large, the transparency (light transmittance) of the pressure-sensitive adhesive film may be easily reduced. When the thickness of the topcoat layer is too small, it may become difficult to form the topcoat layer uniformly. For example, the thickness of the top coat at different locations can vary greatly. Therefore, unevenness is liable to occur in the appearance of the pressure-sensitive adhesive film.

The thickness of the topcoat layer can be grasped by observing the cross section of the topcoat layer with a Transmission Electron Microscope (TEM). For example, the results obtained as follows can be preferably employed as the thickness of the top coat: subjecting a target sample (for example, a substrate having a top coat layer formed thereon or a pressure-sensitive adhesive film including the substrate) to a heavy metal dyeing treatment to make the top coat layer clear; then, resin embedding is carried out; and a cross section of the sample by the microtome method was observed with TEM. For example, a TEM (model: "H-7650") manufactured by Hitachi, ltd. can be used as the TEM. In the later described embodiments, the thickness of the top coat (average thickness in the field of view) is actually measured by: a cross-sectional image obtained under the conditions of an acceleration voltage of 100kV and a magnification of 60,000 was subjected to binarization processing, and then the cross-sectional area of the top coat was divided by the length of the sample in the field of view. When the top coat can be observed in a sufficiently clear manner without heavy metal staining, the heavy metal staining treatment can be omitted. Alternatively, the thickness of the top coat layer may be determined by calculation from a calibration curve generated based on the correlation between the thickness obtained with the TEM and the thickness obtained with various thickness detection devices (e.g., surface roughness meter, interferometric thickness meter, infrared spectrometer and various X-ray diffractometers).

The surface resistivity measured on the surface of the top coat is preferably 10 ¹² Omega or less, more preferably 10 ⁴ Ω～10 ¹² Ω, still more preferably 10 ⁴ Ω～10 ¹¹ Omega, particularly preferably 5X 10 ⁴ Ω～10 ¹⁰ Omega, most preferably 10 ⁴ Ω～10 ⁹ Omega. A pressure-sensitive adhesive film showing such surface resistivity can be suitably used as a pressure-sensitive adhesive film used in, for example, processing or transportation of an article to be protected from static electricity, such as a liquid crystal cell or a semiconductor device. The surface resistivity can be determined by determining the surface resistivity at 23 ℃ and 50% RH in a commercially available atmosphereThe value of the surface resistance of the layer measured by the edge resistance measuring device is calculated.

The friction coefficient of the topcoat layer is preferably 0.4 or less. When the topcoat layer having a low friction coefficient as described above is used, in the case where a load (a load that may cause a scratch defect) is applied to the topcoat layer, the load is avoided along the surface of the topcoat layer, and thus the frictional force due to the load can be reduced. Thus, cohesive failure (failure mode in which failure occurs in the top coat) or interfacial failure (failure mode in which the top coat peels off the back of the substrate) of the top coat is difficult to occur. Therefore, the occurrence of scratch defects in the pressure-sensitive adhesive film can be further prevented. The lower limit of the friction coefficient is preferably 0.1 or more, more preferably 0.15 or more, in view of balance with other characteristics (for example, appearance quality and printability). For example, under a measuring environment of 23 ℃ and 50% RH, a value determined by scratching (scratch) the surface of the topcoat under a vertical load of 40mN can be used as the friction coefficient. The amount of the lubricant additive used is desirably set so that a preferable friction coefficient can be achieved. For example, increasing the crosslinking density of the top coat by adding a crosslinking agent or adjusting film forming conditions is effective for adjusting the friction coefficient.

The back surface (surface of the top coat) of the pressure-sensitive adhesive film preferably has a property that printing can be easily performed thereon with an oil-based ink (for example, by using an oil-based marker pen). Such a pressure-sensitive adhesive film is suitable for use in the following: for example, in a process of processing or conveying an adherend (for example, an optical member) in which a pressure-sensitive adhesive film is adhered thereto, an identification number or the like of the adherend serving as an object to be protected is described and displayed on the pressure-sensitive adhesive film. Therefore, a surface protective film excellent not only in appearance quality but also in printability is preferable. For example, the pressure-sensitive adhesive film preferably has high printability to this type of oil-based ink whose solvent is an alcohol-based solvent and into which a pigment is incorporated. In addition, it is preferable that the ink printed on the pressure-sensitive adhesive film is difficult to remove by scratching or transferring (that is, the printing adhesiveness of the pressure-sensitive adhesive film is excellent). The pressure-sensitive adhesive film preferably has such solvent resistance that the appearance of the pressure-sensitive adhesive film does not change significantly when printed characters are corrected or erased, even when the printed characters are erased using alcohol (e.g., ethanol).

The top coat layer preferably contains a wax ester used as a lubricating additive, and therefore sufficient lubricity (e.g., the above-described preferred coefficient of friction) can be achieved even in a mode in which the surface of the top coat layer is not subjected to any further release treatment (e.g., a treatment in which any suitable release treatment agent such as a silicone-based release agent or a long-chain alkyl-based release agent is applied thereto and dried). For example, a mode in which the surface of the top coat layer is not subjected to any further peeling treatment as described above is preferable because whitening of the pressure-sensitive adhesive film caused by the peeling treatment agent (for example, whitening due to storage thereof under heating and humidified conditions) can be prevented in advance. In addition, this mode is advantageous in terms of solvent resistance.

The pressure-sensitive adhesive film may be performed according to a mode in which the pressure-sensitive adhesive film further includes any other layers except the substrate, the pressure-sensitive adhesive layer, and the topcoat layer. Such "other layer" may be disposed, for example, between the first surface (back surface) of the substrate and the topcoat layer, or between the second surface (front surface) of the substrate and the pressure-sensitive adhesive layer. The layer to be provided between the back surface of the substrate and the top coat layer may be, for example, a layer containing an antistatic component (antistatic layer). The layer provided between the front surface of the substrate and the pressure-sensitive adhesive layer may be, for example, a primer layer (anchor layer) for improving the anchorage of the pressure-sensitive adhesive layer to the second surface or an antistatic layer. The pressure-sensitive adhesive film having a configuration in which an antistatic layer is provided on the front surface of the substrate, an anchor layer is provided on the antistatic layer, and a pressure-sensitive adhesive layer is provided thereon is allowed.

< < < < foldable device and rollable device > >)

The pressure-sensitive adhesive film of the present invention is excellent in flexibility and transparency, and thus can be suitably provided in, for example, a bendable device (bendable device), a foldable device (foldable device), or a rollable device (rollable device) having a movable bending portion. In particular, the pressure-sensitive adhesive film of the present invention is excellent in flexibility and transparency, and thus can be suitably provided in a foldable device (a device that can be folded) or a rollable device (a device that can be rolled), and it has been more difficult to apply the pressure-sensitive adhesive film to these devices than to a bendable device so far.

The foldable device of the present invention includes the pressure-sensitive adhesive film of the present invention. The foldable device of the present invention may include any suitable other members as long as the device includes the pressure-sensitive adhesive film of the present invention.

The rollable device of the present invention includes the pressure-sensitive adhesive film of the present invention. The rollable device of the present invention may comprise any suitable other components as long as the device comprises the pressure sensitive adhesive film of the present invention.

Fig. 1 is a schematic sectional view for explaining a foldable device according to an embodiment of the present invention as a typical example of a use form of a pressure-sensitive adhesive film of the present invention. In fig. 1, a foldable device 1000 of the present invention includes a cover film 10, a pressure-sensitive adhesive layer 20, a polarizing plate 30, a pressure-sensitive adhesive layer 40, a touch sensor 50, a pressure-sensitive adhesive layer 60, an OLED70, and a pressure-sensitive adhesive film 100 of the present invention. In fig. 1, a pressure-sensitive adhesive film 100 of the present invention includes a pressure-sensitive adhesive layer 80 and a substrate layer 90. Each of the pressure-sensitive adhesive layer 20, the pressure-sensitive adhesive layer 40, and the pressure-sensitive adhesive layer 60 may be a pressure-sensitive adhesive layer including a pressure-sensitive adhesive having the same composition as the pressure-sensitive adhesive layer 80 forming the pressure-sensitive adhesive film 100 of the present invention, or may be a pressure-sensitive adhesive layer including a pressure-sensitive adhesive having a different composition from the pressure-sensitive adhesive layer 80.

The pressure-sensitive adhesive film of the present invention is excellent in flexibility and transparency, and therefore can be suitably provided on, for example, the back surface (surface opposite to the display surface) of a bendable device (bendable device), a foldable device (foldable device), or a rollable device (rollable device). Fig. 1 is a view in which a pressure-sensitive adhesive film is provided on the back surface (surface opposite to the display surface) of a foldable device (device that can be folded).

Examples

Now, the present invention will be described more specifically by way of examples and comparative examples. However, the present invention is by no means limited thereto. In the following description, the terms "part" and "%" are by weight unless otherwise specified.

<tanδ>

Tan δ of a sample measured in dimensions of 5mm width by 15mm length was measured in a tensile mode under an axial force of 100G with a viscoelasticity measuring apparatus "RSA-G2" (manufactured by TA Instruments Japan inc.). In the strain sweep (exposure amplitude) mode, the frequency, the measurement temperature, and the immersion time were set to 1Hz, 90 ℃, and 60 seconds, respectively, and the strain measurement range was set to 0.01% to 1.0%, and then the measurement was performed at a strain within this range. The values of tan δ at each strain are illustrated, and tan δ at 0.1% strain and tan δ at 0.7% strain are determined from the resulting curves. Regarding the thickness of the sample as the pressure-sensitive adhesive film, the measurement was performed by inputting only the thickness of the substrate thereof excluding the thickness of the pressure-sensitive adhesive thereof, assuming that the rigidity of the substrate was so large that the pressure-sensitive adhesive influences both the storage elastic modulus and the loss elastic modulus of the pressure-sensitive adhesive film negligibly.

tan δ is determined by the following equation.

tan δ = loss elastic modulus/storage elastic modulus

< bending test >

In a state in which the pressure-sensitive adhesive film was bent at a diameter of 6mm phi with the surface of the pressure-sensitive adhesive layer thereof facing outward, as shown in fig. 2, the pressure-sensitive adhesive film in a flat state was fixed in such a manner as to be sandwiched between silicone-treated surfaces of the silicone-treated separator, followed by holding at 90 ℃ for 48 hours. Thereafter, the bending was released, and the pressure-sensitive adhesive film was left to stand at 23 ℃ and 50% RH for 24 hours, followed by measuring the angle of the bent film. A case in which the film is completely restored to its original state is defined as 180 °, and a case in which the bent state at the time of initial fixation is maintained is defined as 0 °.

< evaluation of delamination >

The pressure-sensitive adhesive film was attached to a PET film (manufactured by Toray Industries, inc., S10) having a thickness of 50 μm, and as shown in fig. 3, the attached product was bent such that the pressure-sensitive adhesive film faced inward, and then held at 90 ℃ for 48 hours. After that, the fixed state was released, and the peeling of the pressure-sensitive adhesive film from the PET film was visually observed. Evaluation was performed according to the following criteria.

O: no peeling from the PET film was observed.

X: peeling from the PET film was observed.

< measurement of haze and Total light transmittance >

The haze of the pressure-sensitive adhesive film was calculated with a haze meter HM-150 (manufactured by Murakami Color Research Laboratory Co., ltd.) in accordance with JIS-K-7136 by the following equation: haze (%) = (Td/Tt) × 100 (Td: diffuse transmittance, tt: total transmittance). The total light transmittance was measured in accordance with JIS-K-7316.

< Young's modulus >

The sample piece was cut into a strip shape having a width of 10mm, and its strain-strength characteristics were measured by stretching the strip-shaped sample piece in its lengthwise direction at a clamp pitch of 100mm using a general tensile and compression Tester (TENSILON) under an environment having a temperature of 25 ℃, followed by determining its Young' S modulus from the resulting strain-strength (S-S) curve. The measurement was carried out at a drawing speed of 200 mm/min and a grip interval of 50mm. Young' S modulus is determined from the S-S curve by a method comprising: generating a map of the S-S curve; drawing a tangent line (linear expression) of the graph in a displacement range of 1mm to 2 mm; and determining the young's modulus from the slope of the tangent.

< pressure sensitive adhesive Strength >

The pressure-sensitive adhesive film was cut into dimensions measuring 25mm in width by 150mm in length to provide an evaluation sample. A2.0 kg roller was reciprocated once under an atmosphere of 23 ℃ and 50% RH at a temperature of 23 ℃ and humidity to bond the surface of the pressure-sensitive adhesive layer of the evaluation sample to a Glass plate (trade name: MICRO SLIDE GLASS S, manufactured by Matsunami Glass Ind., ltd.). The pressure-sensitive adhesive strength of the sample after aging the bonded product for 30 minutes under an atmosphere of 23 ℃ and 50% RH of humidity was measured by peeling with a general-purpose tensile tester (manufactured by Minebea Co., ltd., trade name: TCM-1 kNB) at a peel angle of 180 ℃ and a tensile speed of 300 mm/minute.

< coatability >

The number of circular uneven portions occurring in the applied topcoat layer (including the antistatic layer) was counted. Two A4 size layers were made and the average number of these parts was calculated.

Among them, the case where the number is 2 or less was judged to be good, and the case where the number is 3 or more was judged to be bad. The circular uneven portion is a portion in which the thickness of the top coat layer is reduced to become a defect in visual appearance, and a case in which the antistatic agent is repelled and thus cannot be applied at all is judged as "repelled".

< sheet resistance value (for example 8) >

In example 8, the surface resistance value of the layer having the antistatic treatment layer formed thereon was measured with a volume resistance meter type 152-1 and an attached probe 152P-2P (manufactured by Trek Japan) at a voltage of 10V.

< surface resistivity (for examples 9 to 17 and comparative examples 6 to 9) >

In each of examples 9 to 17 and comparative examples 6 to 9, a resistivity meter ("HIRESTA-UP MCP-HT450" manufactured by Mitsubishi Chemical analysis tech co., ltd.) was used, and its URS probe was brought into contact with the surface of the pressure-sensitive adhesive film on which the pressure-sensitive adhesive layer was not provided to measure the surface resistivity thereof under conditions of an applied voltage of 100V and a voltage application time of 10 seconds.

[ production example 1]: preparation of pressure-sensitive adhesive composition A

63 parts by weight of 2-ethylhexyl acrylate (2 EHA), 15 parts by weight of N-vinyl-2-pyrrolidone (NVP), 9 parts by weight of Methyl Methacrylate (MMA), and 13 parts by weight of 2-hydroxyethyl acrylate (HEA), 0.2 parts by weight of 2,2' -azobisisobutyronitrile as a polymerization initiator, and 133 parts by weight of ethyl acetate as a polymerization solvent were charged into a separable flask and stirred for 1 hour while introducing nitrogen gas into the flask. After oxygen in the polymerization system had been removed as described above, the temperature in the system was raised to 65 ℃ and the mixture was allowed to react for 10 hours, followed by addition of ethyl acetate. Thus, a solution of the acrylic polymer (a) having a solid content concentration of 30wt% was obtained.

Next, an isocyanate-based crosslinking agent (trade name: "TAKENATE D110N", manufactured by Mitsui Chemicals, inc.) was added to the solution of the acrylic polymer (a) in an amount of 1 part by weight in terms of solid content relative to 100 parts by weight of the acrylic polymer (a) (solid content). Thus, a pressure-sensitive adhesive composition a was prepared.

[ production example 2]: preparation of pressure-sensitive adhesive composition B

96.2 parts by weight of 2-ethylhexyl acrylate (2 EHA), 3.8 parts by weight of hydroxyethyl acrylate (HEA), 0.2 parts by weight of 2,2' -azobisisobutyronitrile as a polymerization initiator, and 150 parts by weight of ethyl acetate were charged into a four-necked flask including a stirring blade, a thermometer, a nitrogen introduction tube, and a condenser, and nitrogen was introduced into the flask while gently stirring the mixture. The liquid temperature in the flask was maintained at about 60 ℃ and polymerization was performed for 6 hours to prepare a solution (40 wt%) of the acrylic polymer (b). The weight average molecular weight of the acrylic polymer (b) was 540,000.

Next, a solution (40 wt%) of the acrylic polymer (b) was diluted to 25wt% with ethyl acetate, and 4 parts by weight (solid content: 4 parts by weight) of isocyanurate body of hexamethylene diisocyanate (CORONATE HX manufactured by Tosoh Corporation) (the isocyanurate body is a trifunctional isocyanate compound), 2 parts by weight (solid content: 0.02 parts by weight) of dioctyltin dilaurate (ethyl acetate solution by Tokyo Fine Chemical co., ltd., EMBILIZER OL-1, 1wt%) as a crosslinking catalyst, and 3 parts by weight of acetylacetone were added to a solution of 400 parts by weight (solid content: 100 parts by weight) as a crosslinking agent, followed by mixing and stirring. Thus, a pressure-sensitive adhesive composition B was prepared.

[ example 1]

A commercially available release liner ("DIAFOIL MRF-38", manufactured by Mitsubishi Plastics, inc.) was prepared. The pressure-sensitive adhesive composition a was coated on one surface (release face) of the release liner so that its dried thickness became 25 μm, followed by drying at 130 ℃ for 3 minutes. Thus, a 25 μm thick pressure-sensitive adhesive layer including the acrylic pressure-sensitive adhesive a corresponding to the pressure-sensitive adhesive composition a was formed on the release surface of the release liner.

A polyimide-based substrate (trade name: "Kapton", manufactured by Du Pont-Toray co., ltd.) having a thickness of 50 μm was prepared as the substrate layer. The pressure-sensitive adhesive layer formed on the release liner is attached to one surface of the base material layer. The release liner was left on the pressure-sensitive adhesive layer as it was for protecting the surface of the pressure-sensitive adhesive layer (pressure-sensitive adhesive layer surface). The resulting structure was passed through a laminator (0.3 MPa, speed: 0.5 m/min) once at 80 ℃ and then aged in an oven at 50 ℃ for 1 day. Thus, a pressure-sensitive adhesive film (1) was obtained.

The results are shown in Table 1.

[ example 2]

A pressure-sensitive adhesive film (2) was obtained in the same manner as in example 1, except that a polyimide-based substrate having a thickness of 50 μm (trade name: "UPILEX-50S", manufactured by Ube Industries, ltd.) was used as the substrate layer.

The results are shown in Table 1.

[ example 3]

A pressure-sensitive adhesive film (3) was obtained in the same manner as in example 1, except that a polyimide-based substrate (trade name: "PIXEO BP", manufactured by Kaneka Corporation) having a thickness of 50 μm was used as the substrate layer.

The results are shown in Table 1.

[ example 4]

A pressure-sensitive adhesive film (4) was obtained in the same manner as in example 1, except that a polyimide-based substrate having a thickness of 50 μm (trade name: "UPILEX-50RN", manufactured by Ube Industries, ltd.) was used as the substrate layer.

The results are shown in Table 1.

[ example 5]

A pressure-sensitive adhesive Film (5) was obtained in the same manner as in example 1, except that a polyether ether ketone (PEEK) based substrate (trade name: "Shin-Etsu Sepla Film", a high crystalline Film formed without stretching, manufactured by Shin-Etsu Polymer co., ltd.) having a thickness of 50 μm was used as the base material layer.

The results are shown in Table 1.

[ example 6]

A pressure-sensitive adhesive film (6) was obtained in the same manner as in example 1, except that a polyimide-based substrate having a thickness of 50 μm (trade name: "Neopulim S100", manufactured by Mitsubishi Gas Chemical Company) was used as the substrate layer.

The results are shown in Table 1.

[ example 7]

A pressure-sensitive adhesive film (7) was obtained in the same manner as in example 1, except that a polyether ether ketone (PEEK) based substrate (trade name: "exepeek", manufactured by Kurabo Industries ltd.) having a thickness of 25 μm was used as the substrate layer.

The results are shown in Table 1.

Comparative example 1

A pressure-sensitive adhesive film (C1) was obtained in the same manner as in example 1, except that a polyester-based substrate having a thickness of 25 μm (trade name: "lumiror S10", manufactured by Toray Industries, inc.) was used as the substrate layer.

The results are shown in Table 1.

Comparative example 2

A pressure-sensitive adhesive film (C2) was obtained in the same manner as in example 1, except that a polyester-based substrate having a thickness of 50 μm (trade name: "lumiror S10", manufactured by Toray Industries, inc.) was used as the substrate layer.

The results are shown in Table 1.

Comparative example 3

Except that the pressure-sensitive adhesive composition B was used instead of the pressure-sensitive adhesive composition a; and a pressure-sensitive adhesive film (C3) was obtained in the same manner as in example 1, except that a polyester-based substrate having a thickness of 50 μm (trade name: "lumiror S10", manufactured by Toray Industries, inc.) was used as the base material layer.

The results are shown in Table 1.

Comparative example 4

A pressure-sensitive adhesive film (C4) was obtained in the same manner as in example 6, except that the pressure-sensitive adhesive composition B was used instead of the pressure-sensitive adhesive composition a.

The results are shown in Table 1.

Comparative example 5

A pressure-sensitive adhesive film (C5) was obtained in the same manner as in example 7, except that the pressure-sensitive adhesive composition B was used instead of the pressure-sensitive adhesive composition a.

The results are shown in Table 1.

[ production example 3]: production of antistatic-treated polyimide film A

10 parts by weight of an antistatic agent (MICRO-solvent RMd-142, manufactured by Solvex inc., which contains tin oxide and a polyester resin as main components) was diluted with a mixed solvent formed of 30 parts by weight of water and 70 parts by weight of methanol to prepare an antistatic agent solution. The obtained antistatic agent solution was coated with a Meyer bar onto a polyimide-based substrate (trade name: "KAPTON", manufactured by Du Pont-Toray co., ltd.) having a thickness of 50 μm serving as a substrate, and an antistatic layer (thickness: 0.2 μm) was formed by drying the solution at 130 ℃ for 1 minute to remove the solvent thereof. Thus, an antistatic-treated polyimide film a was produced.

[ example 8]

A pressure-sensitive adhesive film (8) was obtained in the same manner as in example 1, except that the antistatic-treated polyimide film a was used as a substrate. The surface resistance value of the film was 5X 10 ⁶ Ω。

[ production example 4]: production of Top coat-Forming polyimide film B

< preparation of coating Material B >

A dispersion (product from Toyobo co., ltd.; trade name: VYLONAL MD-1480) containing 25wt% of a polyester resin (binder) serving as a binder (aqueous dispersion of a saturated copolymerized polyester resin; hereinafter also referred to as "binder dispersion") was prepared.

In addition, an aqueous dispersion of carnauba Wax (trade name: "refined carnauba Wax powder No.2", manufactured by Nippon Wax co., ltd.) was prepared (hereinafter also referred to as "lubricant additive dispersion") as a lubricant additive.

Further, an aqueous solution containing 0.5wt% of poly (3, 4-dioxythiophene) (PEDOT) and 0.8wt% of polystyrene sulfonate (number average molecular weight: 150,000) (PSS) (product from H.C. Starck GmbH, trade name: "Baytron P"; hereinafter also referred to as "aqueous conductive polymer solution") was prepared as a conductive polymer.

100 parts by weight of a binder dispersion liquid, 30 parts by weight of a lubricating additive dispersion liquid, 50 parts by weight of an aqueous conductive polymer solution, and 7 parts by weight of a melamine-based crosslinking agent in terms of solid content were added to a mixed solvent (50 by weight ratio 50) containing water and ethanol, and stirred for about 20 minutes, thereby sufficiently mixing. Thus, coating material B was prepared with an NV of about 0.15 wt%.

< production of polyimide film B having Top coat layer >

The coating material B was applied to a polyimide-based substrate (trade name: "KAPTON", manufactured by Du Pont-Toray co., ltd.) having a thickness of 50 μm as a substrate with a bar coater, and dried by heating at 130 ℃ for 2 minutes. Thus, a polyimide-based substrate having a transparent top coat layer having a thickness of 10nm on one surface thereof (top coat layer-forming polyimide film B) was produced.

[ production example 5]: production of Top coat-Forming polyimide film C

< preparation of coating Material C >

An aqueous solution containing 25% by weight of a polyester urethane resin formed from 25mol% of ethylene glycol, 25mol% of neopentyl glycol, 30mol% of terephthalic acid, 10mol% of adipic acid, and 10mol% of toluene diisocyanate (hereinafter also referred to as "adhesive dispersion") was prepared as an adhesive.

Further, an aqueous solution containing 10wt% of polyethylene glycol (PEG) alkyl ether and 10wt% of polyvinyl alcohol was prepared as a dispersant.

40 parts by weight of the binder dispersion liquid, 5 parts by weight of the lubricating additive dispersion liquid, 8 parts by weight of the aqueous conductive polymer solution, 40 parts by weight of the dispersant, and 7 parts by weight of the melamine-based crosslinking agent in terms of solid content ratio were added to a mixed solvent (50 by weight ratio. Thus, coating material C was prepared with an NV of about 0.30wt%.

< production of polyimide film C for Forming topcoat layer >

The coating material C was applied to a polyimide-based substrate (trade name: "KAPTON", manufactured by Du Pont-Toray co., ltd.) having a thickness of 50 μm as a substrate with a bar coater, and heated at 130 ℃ for 2 minutes to dry. Thus, a polyimide-based substrate having a transparent top coat layer with a thickness of 50nm on one surface thereof (top coat layer-forming polyimide film C) was produced.

[ example 9]

A pressure-sensitive adhesive film (9) was obtained in the same manner as in example 1, except that the polyimide film B forming the top coat layer was used as the substrate.

The results are shown in Table 2.

[ example 10]

A pressure-sensitive adhesive film (10) was obtained in the same manner as in example 2, except that the polyimide film B forming the top coat was used as the substrate.

The results are shown in Table 2.

[ example 11]

A pressure-sensitive adhesive film (11) was obtained in the same manner as in example 4, except that the polyimide film B forming the top coat layer was used as the substrate.

The results are shown in Table 2.

[ example 12]

A pressure-sensitive adhesive film (12) was obtained in the same manner as in example 7, except that the polyimide film B forming the top coat layer was used as the substrate.

The results are shown in Table 2.

[ example 13]

A pressure-sensitive adhesive film (13) was obtained in the same manner as in example 1, except that the polyimide film C forming the top coat was used as the substrate.

The results are shown in Table 2.

[ example 14]

A pressure-sensitive adhesive film (14) was obtained in the same manner as in example 2, except that the polyimide film C forming the top coat was used as the substrate.

The results are shown in Table 2.

[ example 15]

A pressure-sensitive adhesive film (15) was obtained in the same manner as in example 3, except that the polyimide film C forming the top coat was used as the substrate.

The results are shown in Table 2.

[ example 16]

A pressure-sensitive adhesive film (16) was obtained in the same manner as in example 4, except that the polyimide film C forming the top coat was used as the substrate.

The results are shown in Table 2.

[ example 17]

A pressure-sensitive adhesive film (17) was obtained in the same manner as in example 7, except that the polyimide film C forming the top coat layer was used as the substrate.

The results are shown in Table 2.

Comparative example 6

A pressure-sensitive adhesive film (C6) was obtained in the same manner as in comparative example 1, except that the polyimide film B forming the top coat layer was used as the substrate.

The results are shown in Table 2.

Comparative example 7

A pressure-sensitive adhesive film (C7) was obtained in the same manner as in comparative example 2, except that the polyimide film B forming the top coat layer was used as the substrate.

The results are shown in Table 2.

Comparative example 8

A pressure-sensitive adhesive film (C8) was obtained in the same manner as in comparative example 1, except that the polyimide film C forming the top coat was used as the substrate.

The results are shown in Table 2.

Comparative example 9

A pressure-sensitive adhesive film (C9) was obtained in the same manner as in comparative example 2, except that the polyimide film C forming the top coat layer was used as the substrate.

The results are shown in Table 2.

Industrial applicability

The pressure-sensitive adhesive film of the present invention is excellent in flexibility and transparency, and thus can be suitably provided in, for example, a bendable device (bendable device), a foldable device (foldable device), or a rollable device (rollable device) having a movable bending portion.

Description of the reference numerals

1000. Foldable device

100. Pressure-sensitive adhesive film

10. Covering film

20. Pressure sensitive adhesive layer

30. Polarizing plate

40. Pressure sensitive adhesive layer

50. Touch sensor

60. Pressure sensitive adhesive layer

70 OLED

80. Pressure sensitive adhesive layer

90. Substrate layer

16 mm phi glass rod

2. Silicone treated separator

3. Adhesive layer

4. Fixed glass

5 PET film

Claims

1. A pressure sensitive adhesive film, comprising:

a substrate layer; and

a layer of a pressure-sensitive adhesive,

wherein the material of the substrate layer is at least one selected from polyimide and polyether-ether-ketone,

the pressure-sensitive adhesive layer has a pressure-sensitive adhesive strength of 1N/25mm or more at 23 ℃ at a stretching speed of 300 mm/min and a peel angle of 180 DEG with respect to a glass plate,

the pressure-sensitive adhesive film has a tan delta (0.7%) at 0.7% strain of 0.1 or less as measured in a stretch mode of a viscoelasticity measuring apparatus.

2. A pressure sensitive adhesive film, comprising:

a substrate layer; and

a layer of a pressure-sensitive adhesive,

wherein the material of the substrate layer is at least one selected from polyimide and polyetheretherketone,

the pressure-sensitive adhesive layer has a pressure-sensitive adhesive strength of 1N/25mm or more to a glass plate at 23 ℃ at a stretching speed of 300 mm/min and a peel angle of 180 DEG,

the pressure-sensitive adhesive film has a difference (tan delta (0.7%) -tan delta (0.1%)) between tan delta (0.7%) at 0.7% strain and tan delta (0.1%) thereof at 0.1% strain, measured in a stretching mode of a viscoelasticity measuring apparatus, of 0.05 or less.

3. The pressure-sensitive adhesive film according to claim 1 or 2, wherein the bending angle of the pressure-sensitive adhesive film is 60 ° to 180 ° after the pressure-sensitive adhesive film has been bent at a diameter of 6mm ° and held at 90 ℃ for 48 hours, then the bend is released, and the pressure-sensitive adhesive film is left to stand at 23 ℃ and 50% rh for 24 hours.

4. The pressure-sensitive adhesive film according to claim 1 or 2, further comprising a topcoat on a surface of the base layer opposite to the surface thereof having the pressure-sensitive adhesive layer.

5. The pressure sensitive adhesive film according to claim 4, wherein the top coat layer comprises an adhesive containing at least one selected from the group consisting of polyester resins and polyurethane-based resins.

6. The pressure sensitive adhesive film according to claim 5, wherein the adhesive comprises a polyurethane-based resin.

7. The pressure sensitive adhesive film of claim 4 wherein the topcoat layer comprises an antistatic component.

8. The pressure-sensitive adhesive film according to claim 1 or 2, wherein the young's modulus at 23 ℃ of the substrate layer is 6.0 x 10 ⁷ Pa or above.

9. The pressure-sensitive adhesive film according to claim 1 or 2, further comprising a topcoat layer on a surface of the substrate layer opposite to the surface thereof having the pressure-sensitive adhesive layer,

wherein the top coat layer comprises a binder containing a polyurethane-based resin and an antistatic component, and

wherein the material of the substrate layer is at least one selected from polyimide and polyetheretherketone.

10. The pressure-sensitive adhesive film according to claim 1 or 2, wherein the total light transmittance of the pressure-sensitive adhesive film is 20% or more.

11. The pressure sensitive adhesive film according to claim 1 or 2, wherein the haze of the pressure sensitive adhesive film is 15% or less.

12. The pressure sensitive adhesive film according to claim 1 or 2, wherein the pressure sensitive adhesive layer comprises an acrylic pressure sensitive adhesive.

13. The pressure sensitive adhesive film according to claim 1 or 2, wherein the pressure sensitive adhesive film is adhered to a foldable member.

14. The pressure sensitive adhesive film of claim 13 wherein the foldable member is an OLED.

15. A pressure sensitive adhesive film according to claim 1 or 2 wherein the pressure sensitive adhesive film is adhered to a rollable member.

16. A pressure sensitive adhesive film according to claim 15 wherein the rollable member is an OLED.

17. A foldable device comprising the pressure sensitive adhesive film according to any one of claims 1 to 12.

18. A rollable device comprising the pressure sensitive adhesive film according to any one of claims 1 to 12.