JP2020176185A - Adhesive tape - Google Patents

Abstract

To provide an adhesive tape which suppresses generation of air pool between the adhesive tape and a member when a member is fixed, and can improve workability for peeling the member from the adhesive tape.SOLUTION: An adhesive tape includes a base material layer that is a resin-made film, a first adhesive layer provided on a surface on one side of the base material layer, and a second adhesive layer provided on a surface on the other side of the base material layer. A recess recessed from the surface is provided at least on the surface on one side of the first adhesive layer. The recess is open on the end of the first adhesive layer. An adhesive force of the first adhesive layer is smaller than an adhesive force of the second adhesive layer and is 6-14 N/20 mm, and the adhesive force of the second adhesive layer is 14-22 N/20 mm.SELECTED DRAWING: Figure 1

Description

The present invention relates to an adhesive tape.

Since the adhesive tape has excellent workability and high adhesive reliability, it is widely used as a joining means for fixing members of various sizes in various industrial fields.

Japanese Unexamined Patent Publication No. 2012-11123

By the way, when the members are bonded to each other using the adhesive tape, an air pool may be generated between the members and the adhesive tape in the conventional adhesive tape, which makes it difficult to sufficiently fix the members to each other or air. There was a problem that unevenness was generated due to the accumulation. As a technique for improving such a problem, a release liner having an embossed surface (convex on the surface is formed) is used to form a depression on the surface of the adhesive layer of the adhesive tape, and the depression is a member. There is a technique for facilitating the discharge of air and reducing the amount of air pooled during bonding (for example, Patent Document 1). However, since the technology uses the same adhesive on both sides of the adhesive tape, the adhesive tape is used, for example, for misalignment and then alignment, or for collecting and reworking the bonded members. When peeling the members from (when separating the members from each other), it is difficult to peel the members from the adhesive tape, or the residual state of the adhesive tape on each member when the members are peeled off becomes different, which makes workability easier. Improvement was desired.

Therefore, the present invention provides an adhesive tape capable of suppressing the generation of air pools between the adhesive tape and the member when the members are fixed and improving workability when the members are peeled off from each other. The purpose.

The present invention is as follows.
[1] A base material layer which is a resin film, a first pressure-sensitive adhesive layer provided on the surface on one side of the base material layer, and a second provided on the surface on the other side of the base material layer. With an adhesive layer,
At least one surface of the first pressure-sensitive adhesive layer is provided with a recess recessed from the surface.
The recess is opened at the end of the first pressure-sensitive adhesive layer.
The adhesive strength of the first pressure-sensitive adhesive layer is lower than the adhesive strength of the second pressure-sensitive adhesive layer, and is 6 to 14 N / 20 mm.
An adhesive tape having an adhesive strength of 14 to 22 N / 20 mm of the second adhesive layer.
[2] The adhesive tape according to the above [1], wherein the recess has a width of 5 to 150 μm and a depth of 5 to 80 μm.
[3] The loss tangent of the first pressure-sensitive adhesive layer at 85 ° C. is 0.1 to 0.5.
The adhesive tape according to the above [1] or [2], wherein the loss tangent of the second adhesive layer at 85 ° C. is 0.5 to 1.0.
[4] The adhesive tape according to any one of [1] to [3] above, wherein the difference between the adhesive force of the first pressure-sensitive adhesive layer and the adhesive force of the second pressure-sensitive adhesive layer is 3 to 16 N / 20 mm. ..
[5] The adhesive tape according to any one of [1] to [4] above, wherein the thickness of the resin film is 5 to 75 μm.
[6] The first pressure-sensitive adhesive layer has a plurality of the recesses.
When the surface of the first pressure-sensitive adhesive layer is viewed from one side, at the intersection where one recess intersects with the other recess, one recess intersects with two or more other recesses. ] To [5]. The adhesive tape according to any one of.

According to the present invention, it is possible to provide an adhesive tape capable of suppressing the generation of air pools between the adhesive tape and the member when fixing the members and improving workability when peeling the members from each other. it can.

It is sectional drawing which shows the adhesive tape which concerns on one Embodiment of this invention. It is a top view which shows the adhesive tape shown in FIG. 1 in the state which removed the release liner.

Hereinafter, embodiments of the present invention (hereinafter referred to as “the present embodiment”) will be described in detail with reference to the drawings, but the present invention is not limited to the present embodiment.
"Adhesive tape"
The adhesive tape of the present embodiment can be used in various fields and applications, and is not particularly limited, but may be used, for example, for fixing and printing a member in an electronic device, specifically, for fixing a printing plate in flexographic printing. it can.
As shown in the cross-sectional view of FIG. 1, the adhesive tape 1 of the present embodiment has a base material layer 2 which is a resin film and a first pressure-sensitive adhesive layer 3 provided on one surface of the base material layer 2. And a second pressure-sensitive adhesive layer provided on the surface of the base material layer 2 on the other side. Further, in the adhesive tape 1 of the present embodiment, at least one surface of the first pressure-sensitive adhesive layer 3 is provided with a recess 31 recessed from the surface, and the recess 31 is the first pressure-sensitive adhesive layer 3. It is open at the end. Further, in the adhesive tape 1 of the present embodiment, the adhesive strength of the first adhesive layer 3 is lower than the adhesive strength of the second adhesive layer 4 and is 6 to 14 N / 20 mm, and the second adhesive layer 4 The adhesive strength of is 14 to 22 N / 20 mm.
According to the adhesive tape 1 of the present embodiment, it is possible to suppress the generation of air pools between the adhesive tape 1 and the member when the member is fixed, and when the member is peeled off from the adhesive tape 1 (the fixed members are separated from each other). It is possible to improve the workability of the product. Specifically, since the first adhesive layer 3 of the adhesive tape 1 of the present embodiment has the recess 31, when the members are bonded to each other using the adhesive tape 1, air first adheres to the recess 31 as a flow path. It is possible to sufficiently suppress the generation of air pools between the member and the adhesive tape 1 due to coming out of the end portion of the agent layer 3.
Further, in the adhesive tape 1 of the present embodiment, the adhesive strength of the first pressure-sensitive adhesive layer 3 is lower than the adhesive strength of the second pressure-sensitive adhesive layer 4, and each has a predetermined range of adhesive strength. When the member is peeled off from the adhesive tape 1 (when one member and the other member are separated) in order to align after bonding or to collect and rework the bonded member, the adhesive layer Due to the difference in adhesive strength, the second adhesive layer 4 of the adhesive tape 1 can be peeled off from the other member on the first adhesive layer 3 side while being attached to the surface of one member. Therefore, since the residual state of the adhesive tape 1 when the members are peeled off is easily determined, workability can be improved.
In particular, for example, when the members are bonded and then aligned and re-bonded, the adhesive tape 1 after the members are peeled off has a second adhesive layer 4 of the adhesive tape 1 attached to the member and has a recess 31. 1 The adhesive layer 3 is in a state where it can be reattached. Therefore, even when the members are reattached to each other, they can be attached while suppressing air accumulation by the recess 31.

Hereinafter, each layer of the adhesive tape 1 will be described.
<Resin film>
In the adhesive tape 1 of the present embodiment, the base material layer 2 is formed of a resin film. By forming with a resin film, an adhesive tape 1 having an appropriate thickness can be obtained.
In the present embodiment, the resin film is not particularly limited, and examples thereof include plastic films such as polyester film, polypropylene film, polyethylene film, and polyimide film, and polyester film is preferable from the viewpoint of workability of the adhesive tape 1. ..

Further, in the present embodiment, the thickness of the resin film is preferably 5 to 75 μm, more preferably 10 to 45 μm, and further preferably 10 to 20 μm. When the thickness is within the range, the handleability of the adhesive tape 1 is improved. Further, when the thickness is 75 μm or less, the cost of the resin film can be suppressed, and the members can be easily peeled off from each other.
In the present embodiment, the thickness is measured by a method using a dial gauge according to JIS K6250, and specifically, a dial gauge having a flat surface having a contact surface with the adhesive tape 1 having a diameter of 8 mm is 0.51N. It is a value measured when the contact is made by the force of.

In the present embodiment, in order to improve the adhesion between the base material layer 2 and the pressure-sensitive adhesive, the resin film can be subjected to easy-adhesion treatment such as primer treatment, corona treatment, and plasma treatment.

<First adhesive layer, second adhesive layer>
In the adhesive tape 1 of the present embodiment, the first pressure-sensitive adhesive layer 3 is provided on the surface of one side of the base material layer 2, and the second pressure-sensitive adhesive layer is provided on the surface of the other side of the base material layer 2.

In the present embodiment, the adhesive strength of the first pressure-sensitive adhesive layer 3 is lower than the adhesive strength of the second pressure-sensitive adhesive layer 4, and is 6 to 14 N / 20 mm. The adhesive strength of the second pressure-sensitive adhesive layer 4 is 14 to 22 N / 20 mm.
The adhesive strength of the first pressure-sensitive adhesive layer 3 is preferably 6 to 14 N / 20 mm, more preferably 7 to 12 N / 20 mm, and even more preferably 8 to 11 N / 20 mm. The adhesive strength of the second pressure-sensitive adhesive layer 4 is preferably 14 to 22 N / 20 mm, more preferably 16 to 21 N / 20 mm, and even more preferably 18 to 21 N / 20 mm.
In the present embodiment, the adhesive strength of the first pressure-sensitive adhesive layer 3 is made lower than the adhesive strength of the second pressure-sensitive adhesive layer 4, so that the members are bonded to each other using the adhesive tape 1 as described above. When the member is peeled off, the workability of the peeling work can be improved. Further, by setting the adhesive force of the first pressure-sensitive adhesive layer 3 to 6 N / 20 mm or more and the adhesive force of the second pressure-sensitive adhesive layer 4 to 22 N / 20 mm or less, an appropriate adhesive force of the adhesive tape 1 can be obtained. Further, by setting the adhesive strength of the first pressure-sensitive adhesive layer 3 to 14 N / 20 mm or less and the adhesive strength of the second pressure-sensitive adhesive layer 4 to 14 N / 20 mm or more, the members are peeled off, and then the adhesive tape 1 is used. With the second adhesive layer 4 still attached to the surface of the member, it can be easily peeled off on the first adhesive layer 3 side of the adhesive tape 1.

Further, in the present embodiment, the difference between the adhesive force of the first pressure-sensitive adhesive layer 3 and the adhesive force of the second pressure-sensitive adhesive layer 4 is preferably 3 to 16 N / 20 mm, more preferably 4 to 14 N / 20 mm. Yes, more preferably 5-12N / 20mm. By setting the difference to 3N / 20 mm or more, it is possible to facilitate the state in which the second adhesive layer 4 of the adhesive tape 1 remains attached to the surface of the member after the member is peeled off. Further, by setting the difference to 16 N / 20 mm or less, the second pressure-sensitive adhesive layer 4 can also be peeled off from the member, so that the member can be reused or the like.

In this embodiment, the adhesive strength can be measured by the method described in the examples.
Further, in the present embodiment, in order to make the adhesive strength of the first pressure-sensitive adhesive layer 3 and the second pressure-sensitive adhesive layer 4 within the above range, the pressure-sensitive adhesive composition, molecular weight, cross-linking agent, etc. of the pressure-sensitive adhesive layer are set within a specific range. It can be adjusted by.

In the present embodiment, the loss tangent of the first pressure-sensitive adhesive layer 3 at 85 ° C. is 0.1 to 0.5, and the loss tangent of the second pressure-sensitive adhesive layer 4 at 85 ° C. is 0.5 to 1.0. Is preferable.
By setting the loss tangent of the first pressure-sensitive adhesive layer 3 at 85 ° C. to 0.1 or more, the adhesion to the member is improved and excellent adhesiveness can be obtained.
Further, by setting the loss tangent of the first pressure-sensitive adhesive layer 3 at 85 ° C. to 0.5 or less, it is easy to maintain the shape of the recess 31 of the first pressure-sensitive adhesive layer 3, and after the pressure-sensitive adhesive tape 1 is bonded, Workability when peeling off the members can be improved. Specifically, the shape of the recess 31 is likely to be maintained even after the release liner 5 is peeled off from the adhesive tape 1, while the adhesive tape 1 is pressurized when the members are bonded to each other using the adhesive tape 1. As a result, the recess 31 is closed and the members can be securely bonded to each other. Further, for example, when the members are bonded to each other and then aligned, the shape of the recess 31 of the adhesive tape 1 can be maintained even after the members are peeled off, and an air pool is formed when the members are reattached. Can be suppressed.
By setting the loss tangent of the second pressure-sensitive adhesive layer 4 at 85 ° C. to 0.5 or more, the adhesion to each member can be improved. Further, by setting the loss tangent to 1.0 or less, the storage stability of the adhesive tape 1 can be improved. Specifically, for example, it is possible to prevent the adhesive from squeezing out from the edge of the adhesive tape 1 and maintain the roll shape.

In the present embodiment, the loss tangent can be measured using a viscoelasticity tester (manufactured by Leometrics, trade name: Ares 2KSTD). Specifically, a test piece is sandwiched between parallel disks, which are the measuring parts of the testing machine, and the loss tangent at a temperature of 85 ° C. and a frequency of 1 Hz is measured and obtained. As the test piece used in the above measurement, a circular test piece having a thickness of 1 mm and a diameter of 8 mm, which is produced by using the adhesive of the pressure-sensitive adhesive layer, is used.
Further, in the present embodiment, in order to set the loss tangent of the first pressure-sensitive adhesive layer 3 and the second pressure-sensitive adhesive layer 4 at 85 ° C. within the above range, the pressure-sensitive adhesive composition, molecular weight, cross-linking agent, etc. of the pressure-sensitive adhesive layer are specified. It can be adjusted by setting the range to.

The thickness of the first pressure-sensitive adhesive layer 3 is preferably 20 to 70 μm, more preferably 30 to 65 μm, and even more preferably 35 to 55 μm. The thickness of the second pressure-sensitive adhesive layer 4 is preferably 40 to 90 μm, more preferably 50 to 80 μm, and even more preferably 55 to 75 μm.
By making the first pressure-sensitive adhesive layer 3 and the second pressure-sensitive adhesive layer 4 having the above-mentioned thickness, it is possible to easily develop an appropriate adhesive force and to easily obtain a pressure-sensitive adhesive tape 1 having good workability.

The thickness of the first pressure-sensitive adhesive layer 3 and the second pressure-sensitive adhesive layer 4 is an average of the measured values of the thicknesses of the adhesive tape 1 at any five locations. Specifically, the vicinity of any five points of the adhesive tape 1 is cut out as test pieces, each test piece is immersed in liquid nitrogen for 1 minute, and then in liquid nitrogen using a tweezers, in the width direction of the adhesive tape 1. Is folded and split as a crease to prepare a section for observing the split cross section of the adhesive tape 1 in the thickness direction. After returning the section to room temperature in a desiccator, the section was fixed on a sample table so that an electron beam was vertically incident on the fractured surface, and an electron microscope (Miniscope (registered trademark) TM3030Plus, manufactured by Hitachi High Technology Co., Ltd.) Is used to observe the fractured surface. Based on the scale of the electron microscope, the thicknesses of the first adhesive layer 3 and the second adhesive layer 4 of the adhesive tape 1 are measured at five points (parts other than the recess 31), and the average value is taken as the thickness of each layer. To do. The thickness of the first pressure-sensitive adhesive layer 3 and the second pressure-sensitive adhesive layer 4 is a length measured from the surface of the pressure-sensitive adhesive layer to the surface of the base material layer 2 along the stacking direction.

Here, as the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer 3 and the second pressure-sensitive adhesive layer 4 used for the pressure-sensitive adhesive tape 1 of the present embodiment, known acrylic, silicone-based, or rubber-based pressure-sensitive adhesive resins are used. The first pressure-sensitive adhesive layer 3 and the second pressure-sensitive adhesive layer 4 may be different types of pressure-sensitive adhesives or the same type of pressure-sensitive adhesives.

As the rubber-based pressure-sensitive adhesive, block copolymers such as styrene-isoprene-styrene, synthetic rubber-based pressure-sensitive adhesives such as polybutadiene and polybutylene, and natural rubber can be used. When natural rubber is used, it is preferably sulfur-free. If sulfur is contained, for example, when the adhesive tape 1 is used in an electronic device, contact failure may occur.

Further, as the silicone-based pressure-sensitive adhesive, a peroxide cross-linked type or an addition condensation type may be used alone or in combination. Further, it can be used by mixing with an acrylic or rubber adhesive, or an adhesive having a silicone component pendant on the polymer main chain or side chain of the acrylic adhesive may be used.

When an acrylic resin is used as the pressure-sensitive adhesive, it is preferable to use a resin obtained by reacting a radically polymerizable monomer containing an acrylic acid ester having an alkyl side chain having 1 to 14 carbon atoms as a monomer component. Examples of acrylic acid esters having an alkyl side chain having 1 to 14 carbon atoms include, for example.
(Group 1) Methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, sce-butyl acrylate, t-butyl acrylate, n-hexyl acrylate, cyclohexyl acrylate, n-octyl acrylate, isooctyl acrylate, 2-Ethylhexyl acrylate, isononyl acrylate, isodecyl acrylate, lauryl acrylate methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, sce-butyl methacrylate, t-butyl methacrylate, n-hexyl methacrylate, cyclohexyl Examples thereof include methacrylate, n-octyl methacrylate, isooctyl methacrylate, 2-ethylhexyl methacrylate, isononyl methacrylate, isodecyl methacrylate, and lauryl methacrylate. Among them, as the acrylic acid ester, it is preferable to use a methacrylic acid alkyl ester having an alkyl side chain having 4 to 9 carbon atoms or an acrylic acid alkyl ester having an alkyl side chain having 4 to 9 carbon atoms. Further, it is more preferable to use an acrylic acid alkyl ester having an alkyl side chain having 4 to 9 carbon atoms.

Further, as a monomer component, it is preferable to add an acrylic acid ester or other vinyl-based monomer having a polar group such as a hydroxyl group, a carboxyl group or an amino group in the side chain.
As a monomer containing a hydroxyl group,
(Group 2) 2-Hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, hydroxypropyl (meth) acrylate, caprolactone-modified (meth) acrylate, polyethylene glycol mono (meth) ) Acrylate, polypropylene glycol (meth) acrylate and the like. As the monomer containing a hydroxyl group, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate and the like are preferable.

Further, as a monomer having a polar group other than a hydroxyl group,
(Group 3) Monomers having a carboxyl group such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, crotonic acid, acrylic acid dimer, ethylene oxide-modified succinic acid acrylate, N-vinyl-2-pyrrolidone, n-vinylcaprolactam, Monomers having an amide group such as acryloylmorpholine, acrylamide, N, N-dimethylacrylamide, 2- (perhydrophthalimide-N-yl) ethyl acrylate, acrylonitrile, maleic anhydride, itaconic anhydride and the like can be mentioned.

In particular, as the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer 3 used for the pressure-sensitive adhesive tape 1 of the present embodiment, in addition to the above-mentioned (group 1) monomer, a compound represented by the following formula (I) and the following formula ( It is preferable to use an adhesive resin obtained by reacting a polymerizable monomer containing a compound represented by II) and a compound represented by the following formula (III).

（式中、Ｘは水素原子又はメチル基、Ｒ₁は分岐鎖を有していてもよい炭素数１〜１２のアルキレン基、Ｒ₂は分岐鎖を有していてもよい炭素数１〜１２のアルキル基を表す。）

(In the formula, X is a hydrogen atom or a methyl group, R ₁ is an alkylene group having 1 to 12 carbon atoms which may have a branched chain, and R ₂ is an alkylene group having 1 to 12 carbon atoms which may have a branched chain. Represents the alkyl group of.)

（式中、Ｘは水素原子又はメチル基、Ｒ₁は分岐鎖を有していてもよい炭素数１〜１２のアルキレン基を表す。）

(In the formula, X represents a hydrogen atom or a methyl group, and R ₁ represents an alkylene group having 1 to 12 carbon atoms which may have a branched chain.)

（式中、Ｘは水素原子又はメチル基を表す。）

(In the formula, X represents a hydrogen atom or a methyl group.)

The Tg of the adhesive resin is preferably −60 to −10 ° C. Among them, −50 to −20 ° C. is more preferable, and −40 to −20 ° C. is particularly preferable. If the temperature is lower than -60 ° C, the cohesive force of the pressure-sensitive adhesive is lowered, and the heat resistance is likely to be lowered. If the temperature exceeds -10 ° C, peeling and cracking are likely to occur when dropped.

As the compound represented by the above formula (I), in the formula (I), X is a hydrogen atom, R ₁ is -CH ₂ CH _2- , and R ₂ is -CH ₃ and -CH ₂ CH _3. , -CH ₂ CH ₂ CH ₃ , -CH ₂ CH ₂ CH ₂ CH ₃ , where X is a hydrogen atom, R ₁ is -CH ₂ CH _2- , and R ₂ is -CH ₃ . It is particularly preferable to have.
Further, as the compound represented by the above formula (II), in the formula (II), X is a hydrogen atom and R ₁ is -CH ₂ CH _2- , -CH ₂ CH ₂ CH _2- , -CH _2. CH ₂ CH ₂ CH _2- is preferable, X is a hydrogen atom, and R ₁ is -CH ₂ CH _2- .
Further, in the formula (III), it is preferable that X is a hydrogen atom.
The compound represented by the above formula (I) is preferably used in an amount of 2 to 15% by mass, more preferably 5 to 10% by mass, based on all the monomers. Further, the compound represented by the above formula (II) is preferably used in an amount of 0.5 to 15% by mass, more preferably 2 to 10% by mass, based on all the monomers. Further, the compound represented by the formula (III) is preferably used in an amount of 0.05 to 5% by mass, more preferably 0.1 to 3% by mass, based on all the monomers.
When the resin obtained by reacting the monomers represented by the formulas (I) to (III) as described above is used as the resin used for the first pressure-sensitive adhesive layer 3 of the present embodiment, the adhesive strength of the first pressure-sensitive adhesive layer 3 is used. Even when the pressure is set to 6 to 14 N / 20 mm, the adhesive layer is unlikely to come off or be damaged even if it receives a mechanical share such as friction or scratching during repair or tape processing.

The acrylic copolymer can be obtained by copolymerizing with a known polymerization method such as a solution polymerization method, a foil-like polymerization method, a suspension polymerization method, or an emulsion polymerization method. The polymerization initiation method is also a method of initiating by heat using a peroxide-based thermal polymerization initiator such as benzoyl peroxide or lauroyl peroxide, an azo-based thermal polymerization initiator such as azobisisobutylnitrile, or an acetphenone-based, benzoin ether-based, or benzyl. The starting method by ultraviolet irradiation using a ketal-based, acylphosphine oxide-based, benzoin-based, or benzophenone-based photopolymerization initiator, or the method by electron beam irradiation can be arbitrarily selected.

The weight average molecular weight of the acrylic copolymer is preferably 400,000 to 2.2 million, more preferably 500,000 to 1.8 million, and further preferably 600,000 to 1.6 million. By setting the weight average molecular weight in the above range, the adhesion to the member is improved, and excellent adhesiveness can be obtained. The weight average molecular weight is the weight average molecular weight in terms of standard polystyrene measured by gel permeation chromatography (GPC).

The measurement of the molecular weight by the GPC method is a value obtained by measuring using a GPC apparatus (HLC-8329GPC) manufactured by Tosoh Corporation and converting to polystyrene.

Sample concentration: 0.5% by mass (tetrahydrofuran solution)
Sample injection volume: 100 μL
Eluent: THF
Flow velocity: 1.0 mL / min Measurement temperature: 40 ° C
Main column: 2 TSKgel GMHHR-H (20) Guard column: TSKgel HXL-H
Detector: Differential refractometer Standard polystyrene Molecular weight: 10,000 to 20 million (manufactured by Tosoh Corporation)

Further, in order to increase the cohesive force of the first pressure-sensitive adhesive layer 3 and the second pressure-sensitive adhesive layer 4, a cross-linking agent may be added to the pressure-sensitive adhesive. Examples of the cross-linking agent include isocyanate-based cross-linking agents, epoxy-based cross-linking agents, chelate-based cross-linking agents, and photocurable cross-linking agents. As for the amount of the cross-linking agent added, the gel fraction of the first pressure-sensitive adhesive layer 3 is preferably adjusted to 50 to 99%, and most preferably 60 to 90%. On the other hand, the gel fraction of the second pressure-sensitive adhesive layer 4 is preferably adjusted to 10 to 50%, and most preferably 20 to 45%. The gel fraction was determined by immersing the composition of the first pressure-sensitive adhesive layer 3 and the second pressure-sensitive adhesive layer 4 after curing in toluene, and measuring the mass of the unnecessary portion remaining after leaving for 24 hours after drying. Expressed as a percentage by weight.

If necessary, various additives such as a tackifier resin, an antioxidant, an ultraviolet absorber, a filler, a pigment, and a thickener may be added to the above-mentioned pressure-sensitive adhesive as long as the performance is not impaired.

The coating liquid for forming the first pressure-sensitive adhesive layer 3 and the second pressure-sensitive adhesive layer 4 is prepared by dissolving the above-mentioned pressure-sensitive adhesive and, if necessary, other additives in an organic solvent. The organic solvent is not particularly limited as long as the above-mentioned compounding components are dissolved, but known and commonly used organic solvents such as ethyl acetate, toluene, xylene, methanol, and isoprepyl alcohol are used alone or in combination. be able to.

<< Surface shape of adhesive layer >>
In the present embodiment, as shown in FIG. 1, the first adhesive layer 3 of the adhesive tape 1 has an uneven portion 31 recessed from the surface on one surface, and is also shown in FIG. As described above, the recess 31 is opened at the end of the first adhesive layer 3. In the present embodiment, the recess 31 becomes a flow path through which air flows when the members are bonded to each other, and it is possible to suppress the formation of an air pool.
As a specific recess 31, as shown in FIG. 2, the surface of one side of the first pressure-sensitive adhesive layer 3 extends, for example, in a straight line or a curved line (straight line in the illustrated example), and is viewed in a plan view. At least one end (both ends in the illustrated example) of the recess 31 is open to the end of the first pressure-sensitive adhesive layer 3. Further, a plurality of recesses 31 can be provided on the surface of the first pressure-sensitive adhesive layer 3. The arrangement of the recesses 31 can be arbitrary. For example, when the vertical direction of FIG. 2 is the MD direction of the adhesive tape 11 and the horizontal direction is the TD direction, a plurality of recesses 31 extending in the TD direction are provided in the MD direction in a plan view. In addition to being arranged, a plurality of recesses 31 that are inclined with respect to the MD direction can be arranged. More specifically, in the example of FIG. 2, a plurality of recesses 31 extending in the TD direction, a recess 31 inclined to one side with respect to the MD direction, and a recess 31 inclined to the other side with respect to the MD direction are formed. It is arranged so that the portion surrounded by the recess 31 is triangular.
As described above, when the surface of the first pressure-sensitive adhesive layer 3 is viewed from one side, at the intersection where one recess 31 intersects with the other recess 31, one recess 31 and two or more other recesses 31. By intersecting, the air pool can be effectively removed when the members are bonded to each other.

In the present embodiment, the method of forming the recess 31 on the surface of the first pressure-sensitive adhesive layer 3 is not particularly limited, and for example, the pressure-sensitive adhesive is applied onto the release liner 5 having the shape corresponding to the recess 31 embossed. It can be formed by.

In the present embodiment, the cross-sectional shape of the recess 31 is not particularly limited and can be any shape. For example, the cross-sectional shape may be a shape in which a plurality of straight lines are connected in a cross-sectional view and one or more corners are present in the recess 31, only a curved line, or a combination of a straight line and a curved line as in the example of FIG. For example, it can be U-shaped or arc-shaped).

In the present embodiment, the width of the recess 31 is preferably 5 to 150 μm, more preferably 10 to 120 μm. By setting the width to 5 μm or more, it is possible to prevent a sufficient air pool from remaining when the members are bonded to each other, and by setting the width to 150 μm or less, sufficient adhesive force is secured. be able to.
Further, in the present embodiment, the depth of the recess 31 is preferably 5 to 80 μm, more preferably 10 to 60 μm. By setting the depth to 5 μm or more, it is possible to prevent a sufficient air pool from remaining when the members are bonded to each other. Further, by setting the depth to 80 μm or less, sufficient adhesive force can be secured.
The width of the recess 31 is the length measured at the opening of the recess 31 that opens to the surface of the first adhesive layer 3 in a cross-sectional view in a direction orthogonal to the extending direction of the recess 31. In the same cross-sectional view, the depth is from the surface of the first adhesive layer 3 provided with the recess 31 to the bottom of the recess 31 along the direction orthogonal to the surface (the direction in which the adhesive tape 1 is laminated). It is the measured length.

In addition, in this embodiment, the cross-sectional shape, width, depth, etc. of the surface of the recess 31 may be the same or different within one recess 31 or among a plurality of recesses 31. ..

In the present embodiment, in a plan view of the first pressure-sensitive adhesive layer 3 of the pressure-sensitive adhesive tape 1, the distance between the intersections where the plurality of recesses 31 intersect is preferably 0.3 to 3.0 mm, more preferably. It is 0.5 to 2.0 mm, more preferably 0.7 to 1.5 mm. By setting the distance to 0.3 mm or more, excellent adhesiveness can be obtained. Further, by setting the distance to 3.0 mm or less, it is possible to prevent a sufficient air pool from remaining when the members are bonded to each other.

In the present embodiment, the area of the recess 31 is subtracted from the area of the surface of the first adhesive layer 3 with respect to the area of the surface of the first adhesive layer 3 in a plan view of the first adhesive layer 3 of the adhesive tape 1. The area ratio is preferably 50 to 99%, more preferably 70 to 90%. By setting the ratio to 50% or more, excellent adhesiveness can be obtained. Further, by setting the ratio to 99% or less, it is possible to prevent a sufficient air pool from remaining when the members are bonded to each other.

Further, although the adhesive tape 1 of the present embodiment has a recess 31 on the surface of one side of the first pressure-sensitive adhesive layer 3, the recess 31 can also be provided on the surface of the other side of the second pressure-sensitive adhesive layer 4. ..

<Peeling liner>
In the present embodiment, the pressure-sensitive adhesive tape 1 can be provided with a release liner 5 on the surfaces of the first pressure-sensitive adhesive layer 3 and the second pressure-sensitive adhesive layer 4. By providing the release liner 5, the adhesive surface side of the adhesive tape 1 can be protected.
In particular, the release liner 5 provided on the surface of the first pressure-sensitive adhesive layer 3 has a protrusion 51, and the protrusion 51 is the first in a state where the release liner 5 is bonded on the surface of the adhesive tape 1. It is preferable that the shape corresponds to the recess 31 of the pressure-sensitive adhesive layer 3 and exists at a position corresponding to the recess 31. By providing such a release liner 5, it is possible to easily maintain the shape of the recess 31 of the first pressure-sensitive adhesive layer 3.
When the adhesive tape 1 of the present embodiment has a recess 31 on the surface of the second adhesive layer 4, the release liner 5 provided on the surface of the second adhesive layer 4 also has a protruding portion in the same manner as described above. It is preferable to have 51.

In the present embodiment, the release liner 5 is not particularly limited as long as it has mold releasability with respect to the pressure-sensitive adhesive layer, and for example, papers such as kraft paper, glassin paper, and high-quality paper, polyethylene, and polypropylene (OPP, CPP), resin film such as polyethylene terephthalate, laminated paper in which the paper and resin film are laminated, and peeling of silicon-based resin or the like on one or both sides of the paper that has been sealed with clay or polyvinyl alcohol. Conventionally known ones such as treated ones can be used. The thickness of the release liner is not particularly limited, but is preferably 25 μm to 250 μm, and more preferably 50 μm to 150 μm.
The release agent is not particularly limited, but a silicon-based agent is preferable because the peeling force can be easily adjusted.

<Characteristics of adhesive tape>
In a plan view, the adhesive tape 1 has a sheet-like structure in which the layers in the adhesive tape 1 are laminated as a whole, and the total thickness of the base material layer 2 and the adhesive layer of the adhesive tape 1 is It is preferably 50 to 250 μm. The total thickness is more preferably 75 to 200 μm, and even more preferably 100 to 175 μm. By making the adhesive tape 1 having such a thickness, it is possible to suppress the generation of air pools between the adhesive tape and the member when fixing the member, and improve the workability when peeling the member from the adhesive tape. Can be done.
The thickness of the adhesive tape 1 is measured by a method using a dial gauge according to JIS K6250. Specifically, a dial gauge having a flat surface having a contact surface with the adhesive tape 1 having a diameter of 8 mm is 0.51N. It is a value measured when the contact is made with the force of. The thickness does not include the thickness of the release liner 5. Further, for example, it can be measured using a thickness gauge FFG-6 manufactured by Ozaki Seisakusho.

<Manufacturing method of adhesive tape>
The adhesive tape 1 of the present embodiment is not particularly limited and can be produced, for example, by a known method. Specifically, the first pressure-sensitive adhesive layer 3 is formed by using a release liner 5 in which a protrusion 51 having a corresponding shape and a position corresponding to the recess 31 of the first pressure-sensitive adhesive layer 3 is formed. The first pressure-sensitive adhesive layer 3 is formed by applying the pressure-sensitive adhesive of the first pressure-sensitive adhesive layer 3 on the surface of the release liner 5 in which the portion 51 is present and drying or the like. When the second pressure-sensitive adhesive layer 4 does not have a recess 31 on the surface, a smooth release liner is used, and the pressure-sensitive adhesive of the second pressure-sensitive adhesive layer 4 is applied on the surface of the release liner and dried. The second pressure-sensitive adhesive layer 4 is formed. Then, the obtained pressure-sensitive adhesive layers 3 and 4 are attached to both surfaces of the base material with the pressure-sensitive adhesive layers 3 and 4 having the above-mentioned release liner, and pressure is applied as necessary. Adhesive tape 1 can be obtained.
When the second adhesive layer 4 of the adhesive tape 1 has the recess 31, the one having the protruding portion 51 formed is used as in the release liner 5 used for forming the first adhesive layer 3. ..

Although the embodiment of the present invention has been described above with reference to the drawings, the adhesive tape of the present invention is not limited to the above example, and the above adhesive tape can be appropriately modified.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

First, the measurement method and the evaluation method used in Examples and Comparative Examples will be described.
(1) Thickness of 1st Adhesive Layer and 2nd Adhesive Layer The thickness of the 1st adhesive layer and the 2nd adhesive layer is the average of the measured values of the thicknesses of 5 arbitrary points of the adhesive tape. The value was taken. Specifically, the vicinity of any five points of the adhesive tape is cut out as test pieces, each test piece is immersed in liquid nitrogen for 1 minute, and then the width direction of the adhesive tape is folded in liquid nitrogen using a tweezers. The adhesive tape was bent and split to prepare a section for observing the split cross section in the thickness direction of the adhesive tape. After returning the section to room temperature in a desiccator, the section was fixed on a sample table so that an electron beam was vertically incident on the fractured surface, and an electron microscope (Miniscope (registered trademark) TM3030Plus, manufactured by Hitachi High Technology Co., Ltd.) The fracture surface was observed using the above. Based on the scale of the electron microscope, the thicknesses of the first adhesive layer and the second adhesive layer of the adhesive tape were measured at five points (parts other than the recesses), and the average value was taken as the thickness of each layer. The thickness of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer is a length measured from the surface of the pressure-sensitive adhesive layer to the surface of the base material layer along the lamination direction.

(2) Adhesive strength of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer The adhesive strength of each pressure-sensitive adhesive layer was measured as follows. First, a polyester film having a thickness of 25 μm was attached to an adhesive layer not to be measured for adhesive strength, and the film was cut into a width of 20 mm to prepare a test piece. Then, the test piece was attached to a stainless steel plate, and a roller weighing 2 kg was reciprocated once on the test piece at room temperature to apply pressure. Then, after leaving it for 1 hour, the peeling adhesive strength was measured at 180 degrees at a peeling speed of 300 mm / min at room temperature.

(3) Loss tangent of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer The loss tangent of each pressure-sensitive adhesive layer was measured as follows. Using a viscoelasticity tester (manufactured by Leometrics, trade name: Ares 2KSTD), a test piece is sandwiched between parallel disks, which are the measuring parts of the tester, and loss tangent is measured at a temperature of 25 ° C and a frequency of 1 Hz. I asked. As the test piece, the adhesive of the adhesive layer was laminated so as to have a thickness of 1 mm and cut into a circle having a diameter of 8 mm.

(4) Air bleeding property The air bleeding property was evaluated as follows. First, a polyester film having a thickness of 25 μm was attached to the second pressure-sensitive adhesive layer and cut into 10 cm × 5 cm to prepare a test piece. Then, the test piece was placed on the glass plate so that the first pressure-sensitive adhesive layer was in contact with the glass plate, and further, a polycarbonate plate (weight 14 g) larger than the test piece and a weight of 500 g were placed and allowed to stand for 5 seconds. Next, the polycarbonate plate and the weight were removed, and the test piece was reciprocated once on the test piece by a 2 kg roller. Subsequently, the state of air accumulation between the first pressure-sensitive adhesive layer and the glass plate was visually observed through the glass plate to which the test piece was attached, and evaluated as follows.
◯: No air pool with a size of 5 mm or more ×: There is an air pool with a size of 5 mm or more

(5) Reworkability A second adhesive layer of a test piece of an adhesive tape having a size of 25 mm × 50 mm is attached to a photosensitive resin plate (photosensitive resin “Cyrell” manufactured by DuPont) with a roller, and then the first. The pressure-sensitive adhesive layer was attached to the polyvinyl chloride resin with a roller. Then, the photosensitive resin plate was peeled off and evaluated as follows.
⊚: The test piece of the adhesive tape can be peeled off from the polyvinyl chloride without leaving any test piece, and the adhesive tape does not peel off from the urethane plate.
◯: The test piece of the adhesive tape can be peeled off without remaining on the polyvinyl chloride, but the adhesive tape is peeled off from the urethane plate by more than 0% and 33% or less of the test piece.
Δ: The test piece of the adhesive tape can be peeled off without remaining on the polyvinyl chloride, but the adhesive tape is peeled off from the urethane plate by more than 33% and 50% or less.
X: A test piece of adhesive tape remains on the polyvinyl chloride, and all the adhesive tape is peeled off from the urethane plate.

Subsequently, each component used in Examples and Comparative Examples will be described.
-Manufacturing example 1: Embossed peeling liner a
High-quality paper was used as the base sheet, and polyethylene was laminated on both sides thereof. Next, embossing to form a convex portion (height 30 μm, width 70 μm) on one side thereof was performed so as to correspond to the concave portion formed as shown in FIG. The distance between the intersections where the plurality of convex portions intersect was 1.0 mm (in FIG. 2, the length of one side of the triangle formed by the concave portions is 1.0 mm). Next, both sides of the embossed base material were subjected to a peeling treatment of a silicon-based resin to obtain an embossed peeling liner a.

-Manufacturing example 2: Release liner b
A release liner b was obtained in the same manner except that the release liner a was not embossed.

-Preparation example 1: Adhesive A
Using a reaction vessel equipped with a stirrer, a recirculation cooler, a thermometer, a dropping funnel and a nitrogen gas inlet, n-butyl acrylate 89.9 parts by mass, acrylic acid 10.0 parts by mass, 4-hydroxybutyl acrylate 0. 1 part by mass and 0.03 part by mass of 2,2'-azobisisonitri as a polymerization initiator were dissolved in a mixed solvent consisting of 63 parts by mass of ethyl acetate and 100 parts by mass of acetone. Then, it was polymerized at 65 ° C. for 6 hours, and an additional 0.2 part by mass of 2,2'-azobisisobutynitrile and 45 parts by mass of ethyl acetate were added thereto, and further polymerized for 6 hours to obtain a weight average molecular weight of 900,000. An acrylic pressure-sensitive adhesive composition was obtained. Ethyl acetate was added to this acrylic copolymer solution to prepare an acrylic pressure-sensitive adhesive composition having a non-volatile content of 30% by mass.
To 100 parts by mass of the acrylic pressure-sensitive adhesive composition, an epoxy-based cross-linking agent (“E-05X” manufactured by Soken Kagaku Co., Ltd., solid content 0.5% by mass) was added to the acrylic pressure-sensitive adhesive composition obtained above. 0.5 parts by mass was added and stirred to prepare an acrylic pressure-sensitive adhesive A.

-Preparation example 2: Adhesive B
75.0 parts by mass of n-butyl acrylate, 19.0 parts by mass of 2-ethylhexyl acrylate, 3.9 parts of vinyl acetate, acrylic in a reaction vessel equipped with a cooling tube, stirrer, thermometer, dropping funnel and nitrogen gas inlet. 2.0 parts by mass of acid, 0.1 part by mass of 2-hydroxyethyl acrylate and 0.1 part by mass of 2,2'-azobisisobutylnitrile as a polymerization initiator were dissolved in 100 parts by mass of ethyl acetate, and after nitrogen substitution, The polymerization was carried out at 80 ° C. for 12 hours to obtain an acrylic copolymer having a weight average molecular weight of 600,000. Polymerized rosin pentaerythritol ester (manufactured by Arakawa Chemical Co., Ltd., Pencel D-135, softening point 135 ° C.), 10 parts by mass, disproportionated rosin lyserin ester (manufactured by Arakawa Chemical Co., Ltd., softening point 135 ° C.), based on 100 parts by mass of the solid content of this acrylic copolymer solution. Arakawa Chemical Co., Ltd., Super Ester A-100, softening point 100 ° C.) 10 parts by mass was blended, and the resin solid content concentration was adjusted to 45% by mass with ethyl acetate to prepare an acrylic pressure-sensitive adhesive composition. ..
In the acrylic pressure-sensitive adhesive composition obtained above, an isocyanate-based cross-linking agent (“Barnock NC-40” manufactured by Dainippon Ink and Chemicals Co., Ltd., solid content 40% by mass) is added to 100 parts by mass of the acrylic pressure-sensitive adhesive composition. , Ethyl acetate solution) was added in an amount of 2.1 parts by mass and stirred to prepare an acrylic pressure-sensitive adhesive B.

-Preparation example 3: Adhesive C
Adhesive is performed in the same manner except that the isocyanate-based cross-linking agent (“Barnock NC-40” manufactured by Dainippon Ink and Chemicals, Inc., solid content 40% by mass, ethyl acetate solution) of the above adhesive B is changed to 1.7 parts by mass. Agent C was adjusted.

Preparation Example 4: Adhesive D
N-butyl acrylate 93.4 parts by mass, acrylic acid 3.5 parts by mass, vinyl acetate 3 parts by mass, 2-hydroxy in a reaction vessel equipped with a stirrer, a reflux cooler, a thermometer, a dropping funnel and a nitrogen gas inlet. 0.1 part by mass of ethyl acrylate and 0.1 part by mass of 2,2'-azobisisobutyronitrile as a polymerization initiator were dissolved in a solvent consisting of 100 parts by mass of ethyl acetate and polymerized at 85 ° C. for 12 hours. An acrylic copolymer having a weight average molecular weight of 1.6 million was obtained. Next, with respect to 100 parts by mass of the acrylic copolymer, 9.4 parts by mass of "Super Ester A100" (glycerin ester of disproportionate rosin) manufactured by Arakawa Chemical Co., Ltd. and "Haritac PCJ" (polymerized rosin) manufactured by Harima Kasei Co., Ltd. 9.4 parts by mass of pentaerythritol ester () was blended, and the resin solid content concentration was adjusted to 45% by mass with ethyl acetate to prepare an acrylic pressure-sensitive adhesive composition.
In the acrylic pressure-sensitive adhesive composition obtained above, an isocyanate-based cross-linking agent (“Barnock NC-40” manufactured by Dainippon Ink and Chemicals, Inc., solid content 40% by mass) is added to 100 parts by mass of the acrylic pressure-sensitive adhesive composition. , Ethyl acetate solution) was added in an amount of 1.24 parts by mass and stirred to prepare an acrylic pressure-sensitive adhesive D.

Next, Examples and Comparative Examples will be described.
・ Example 1
The surface of the embossed peeling liner a is coated with the acrylic adhesive A using a bar coater so that the thickness of the adhesive layer after drying is 65 μm, and the adhesive is dried at 80 ° C. for 3 minutes. This produced a first pressure-sensitive adhesive layer. Next, the first pressure-sensitive adhesive layer was attached to one side of a resin film (a PET film having a thickness of 16 μm) as a base material layer.
Next, the surface of the release liner b is coated with the adhesive using a bar coater so that the thickness of the adhesive layer after drying the acrylic adhesive B is 50 μm, and the adhesive is dried at 80 ° C. for 3 minutes. A second pressure-sensitive adhesive layer was prepared by allowing the mixture to grow. The second pressure-sensitive adhesive layer was attached to the other surface of the base material and cured in an environment of 40 ° C. for 48 hours to prepare an adhesive tape.

-Example 2
An adhesive tape was produced in the same manner except that the thickness of the acrylic pressure-sensitive adhesive A of Example 1 was changed to 50 μm and the thickness of the acrylic pressure-sensitive adhesive B was changed to 65 μm.

・ Example 3
An adhesive tape was produced in the same manner except that the thickness of the acrylic pressure-sensitive adhesive A of Example 1 was changed to 40 μm and the thickness of the acrylic pressure-sensitive adhesive B was changed to 65 μm.

・ Example 4
An adhesive tape was produced in the same manner except that the acrylic pressure-sensitive adhesive B of Example 3 was changed to the acrylic pressure-sensitive adhesive C.

・ Example 5
An adhesive tape was produced in the same manner except that the acrylic pressure-sensitive adhesive B of Example 3 was changed to the acrylic pressure-sensitive adhesive D.

・ Comparative example 1
An adhesive tape was produced in the same manner except that the acrylic pressure-sensitive adhesive B of Example 1 was changed to the acrylic pressure-sensitive adhesive A.

・ Comparative example 2
An adhesive tape was produced in the same manner except that the acrylic pressure-sensitive adhesive B of Example 3 was changed to the acrylic pressure-sensitive adhesive A.

・ Comparative example 3
An adhesive tape was produced in the same manner except that the acrylic pressure-sensitive adhesive A of Example 1 was changed to the acrylic pressure-sensitive adhesive B.

・ Comparative example 4
An adhesive tape was produced in the same manner except that the embossed release liner a of Example 2 was changed to the release liner b and the acrylic pressure-sensitive adhesive B was changed to the acrylic pressure-sensitive adhesive A.

・ Comparative example 5
An adhesive tape was produced in the same manner except that the embossed peeling liner a of Example 3 was changed to the peeling liner b.

As shown in Table 1, in Examples 1 to 5, at least one surface of the first pressure-sensitive adhesive layer is provided with a recess recessed from the surface, and the recess is formed at the end of the first pressure-sensitive adhesive layer. The adhesive strength of the first pressure-sensitive adhesive layer is lower than that of the second pressure-sensitive adhesive layer and is 6 to 14 N / 20 mm, and the adhesive strength of the second pressure-sensitive adhesive layer is 14 to 22 N / 20 mm. Therefore, it was possible to obtain an adhesive tape having high air bleeding property and reworkability.
Further, as shown in Table 2, in Comparative Examples 1 and 2 in which the adhesive strength of the second adhesive layer was less than 14 N / 20 mm, the adhesive strength of the second adhesive layer was small, so that the reworkability was low. Further, in Comparative Example 3 in which the adhesive force of the first adhesive layer was more than 14 N / 20 mm, the adhesive force of the first adhesive layer was large, so that the reworkability was low. Further, in Comparative Examples 4 and 5 in which the first pressure-sensitive adhesive layer did not have a recess, the air bleeding property was low because the first pressure-sensitive adhesive layer did not have a recess.

According to the present invention, it is possible to provide an adhesive tape capable of suppressing the generation of air pools between the adhesive tape and the member when fixing the members and improving workability when peeling the members from each other. it can.

1: Adhesive tape 2: Base material layer 3: First adhesive layer 31: Recessed 4: Second adhesive layer 5: Release liner 51: Protruding part

Claims (6)

A base material layer that is a resin film, a first pressure-sensitive adhesive layer provided on one surface of the base material layer, and a second pressure-sensitive adhesive layer provided on the other side surface of the base material layer. With and
At least one surface of the first pressure-sensitive adhesive layer is provided with a recess recessed from the surface.
The recess is opened at the end of the first pressure-sensitive adhesive layer.
The adhesive strength of the first pressure-sensitive adhesive layer is lower than the adhesive strength of the second pressure-sensitive adhesive layer, and is 6 to 14 N / 20 mm.
An adhesive tape having an adhesive strength of 14 to 22 N / 20 mm of the second adhesive layer. The adhesive tape according to claim 1, wherein the recess has a width of 5 to 150 μm and a depth of 5 to 80 μm. The loss tangent of the first pressure-sensitive adhesive layer at 85 ° C. is 0.1 to 0.5.
The adhesive tape according to claim 1 or 2, wherein the loss tangent of the second adhesive layer at 85 ° C. is 0.5 to 1.0. The adhesive tape according to any one of claims 1 to 3, wherein the difference between the adhesive strength of the first pressure-sensitive adhesive layer and the adhesive strength of the second pressure-sensitive adhesive layer is 3 to 16 N / 20 mm. The adhesive tape according to any one of claims 1 to 4, wherein the thickness of the resin film is 5 to 75 μm. The first pressure-sensitive adhesive layer has a plurality of the recesses.
Claim 1 in which one recess intersects with two or more other recesses at an intersection of one recess with another recess when the surface of the first pressure-sensitive adhesive layer is viewed from one side. The adhesive tape according to any one of ~ 5.

Images