Adhesive sheet

Abstract

To provide an adhesive sheet having excellent adhesiveness, haze stability with time, anti-static properties, sticking maintainability and temperature tolerance, and capable of being easily peeled without generating adhesive deposit stain after used.SOLUTION: An adhesive sheet comprises a substrate layer, an adhesive layer disposed at one side of the substrate layer, and a release film disposed at an opposite side to the substrate layer of the adhesive layer. The adhesive sheet is such that: a side separated from a sticking surface of the release film to the adhesive layer is a matte surface; an arithmetic mean surface roughness Ra of the matte surface is 0.25 μm or more, or the surface of the matte surface has a surface roughness having a maximum height (Rz) of 1.5 μm or more; the matte surface of the release film is brought into contact with a surface separated from the sticking surface of the substrate layer to the adhesive layer; and a haze measured after removing the release film in an environment at 23°C and a relative humidity of 50% after leaving the adhesive sheet at 50°C for 72 hours is 10-80%.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a pressure-sensitive adhesive sheet, and in particular to a pressure-sensitive adhesive sheet that has excellent adhesiveness, haze stability over time, antistatic properties, laminated storage stability, and temperature resistance, and that can be easily peeled off after use without leaving any adhesive residue or contamination. [Background technology]

[0002] Typically, pressure-sensitive adhesives are in a soft solid (viscoelastic) state at temperatures around room temperature and have the property of easily adhering to an adherend when pressure is applied. Utilizing this property, pressure-sensitive adhesives are widely used in the form of substrate-attached pressure-sensitive adhesive sheets, in which a pressure-sensitive adhesive layer is provided on at least one surface of a substrate, for purposes such as fixing various articles, or obtaining a desired appearance, such as surface protection or decoration of various articles.

[0003] In the above applications, there are problems with PSA sheets that cannot simultaneously achieve adhesive performance, no deterioration in haze over time, antistatic properties, laminated storage stability, and temperature resistance. Furthermore, PSA sheets are peeled off when they are no longer needed, but peeling and removal can cause tearing of the adherend or contamination by adhesive residue. Summary of the Invention

[0004] The present invention has been made to solve the above-mentioned conventional problems, and aims to provide a pressure-sensitive adhesive sheet that has excellent adhesiveness, haze stability over time, antistatic properties, laminated storage stability, and temperature resistance, and that can be easily peeled off without leaving any adhesive residue or contamination after use.

[0005] As a result of extensive research into solving the above-mentioned problems, the inventors have found that the above-mentioned problems can be solved by controlling the arithmetic mean surface roughness Ra or maximum height Rz of the matte surface of the release film to fall within a specific range, and by providing an adhesive sheet in a roll or laminate form, with the matte surface of the release film in contact with a surface of the base layer away from the surface bonded to the adhesive layer, and by setting the haze of the adhesive sheet after removal of the release film to 10 to 80%, thereby completing the present invention.

[0006] That is, the present invention is as follows. [1] A pressure-sensitive adhesive sheet comprising a base layer, a pressure-sensitive adhesive layer provided on one side of the base layer, and a release film provided on the pressure-sensitive adhesive layer on the opposite side to the base layer, wherein the release film has a matte surface on the side away from the surface to be bonded to the pressure-sensitive adhesive layer, and the matte surface has an arithmetic mean surface roughness Ra of 0.25 μm or more, or the surface of the matte surface has a surface roughness with a maximum height (Rz) of 1.5 μm or more; The pressure-sensitive adhesive sheet is present in a roll or laminate form, and the matte surface of the release film is in contact with the surface of the base layer away from the surface to be bonded to the pressure-sensitive adhesive layer. The pressure-sensitive adhesive sheet is left at 50°C for 72 hours, and then the release film is removed in an environment of 23°C and a relative humidity of 50%, and the measured haze is 10 to 80%. [2] The peel force A when peeled at 23°C in a 180° direction at a pulling rate of 300 mm / min is 0.3 to 2.0 N / 20 mm; The tape is attached to an adherend at 23°C, left at 50°C for 24 hours, and then peeled in a 180° direction at a pulling rate of 300mm / min. The peel strength B is 0.5 to 2.5N / 20mm. The pressure-sensitive adhesive sheet according to [1], wherein the difference between the peel strength B and the peel strength A, ie, peel strength B - peel strength A, is 0.1 to 0.8 N / 20 mm. [3] The peel force C when peeled at 23°C in a 180° direction at a tensile speed of 10 m / min is 1.0 to 5.0 N / 20 mm; The peel force D when peeled at a tensile speed of 10 m / min in a 20° direction at 23°C is 5.0 to 9.0 N / 20 mm. The pressure-sensitive adhesive sheet according to [1], wherein the difference between the peeling force D and the peeling force C, ie, peeling force D - peeling force C, is 4.0 to 8.0 N / 20 mm. [4] The film is attached to an adherend at 23°C and left at 50°C for 24 hours, and then peeled off in a 180° direction at a pulling rate of 10m / min. The peel force E is 1.5 to 5.5N / 20mm. The film is attached to an adherend at 23°C, left at 50°C for 24 hours, and then peeled at a 20° direction at 23°C at a pulling rate of 10 m / min, with a peel strength F of 5.5 to 9.5 N / 20 mm. The pressure-sensitive adhesive sheet according to [1], wherein the difference between the peel strength F and the peel strength E, ie, peel strength F - peel strength E, is 4.5 to 8.5 N / 20 mm. [5] The pressure-sensitive adhesive layer comprises a base polymer and a functional resin, the content of the functional resin is 10 to 40 parts by mass relative to 100 parts by mass of the base polymer, The pressure-sensitive adhesive sheet according to any one of [1] to [4], wherein the functional resin is at least one selected from the group consisting of epoxy resins, phenolic resins, vinyl resins, and rosin resins. [6] The pressure-sensitive adhesive sheet according to [5], wherein the pressure-sensitive adhesive layer further comprises at least one selected from the group consisting of a plasticizer, a crosslinking agent, an antistatic agent, and a release aid. [7] The plasticizer includes at least one selected from the group consisting of dioctyl phthalate, dioctyl terephthalate, and diisononyl phthalate; The pressure-sensitive adhesive sheet according to [6], wherein the content of the plasticizer is 20 to 90 parts by mass per 100 parts by mass of the base polymer. [8] The content of the crosslinking agent is 0.01 to 15 parts by mass relative to 100 parts by mass of the base polymer; the crosslinking agent includes an epoxy-based crosslinking agent and / or an isocyanate-based crosslinking agent; the content of the epoxy-based crosslinking agent is 0.01 to 5 parts by mass relative to 100 parts by mass of the base polymer; The pressure-sensitive adhesive sheet according to [6], wherein the content of the isocyanate-based crosslinking agent is 0.1 to 10 parts by mass relative to 100 parts by mass of the base polymer. [9] The content of the antistatic agent is 0.1 to 15 parts by mass relative to 100 parts by mass of the base polymer; The pressure-sensitive adhesive sheet according to [6], wherein the antistatic agent comprises at least one selected from the group consisting of conductive polymers, conductive inorganic fine particles, metal fine particles or fibers, ionic compounds, and ionic surfactants.

[10] . The peeling aid comprises an ionic surfactant and / or a nonionic surfactant; The pressure-sensitive adhesive sheet according to [6], wherein the content of the release aid is 0.1 to 5 parts by mass per 100 parts by mass of the base polymer.

[11] .The following characteristics: (a) In a peel test at a peel speed of 12 m / min, the peel electrification voltage generated when the pressure-sensitive adhesive sheet is peeled from the release film is 500 V or less; (b) the surface resistivity of the pressure-sensitive adhesive sheet is 1.0 × 10 4 ~1.0×10 11 ohms / sq. (c) After stretching the pressure-sensitive adhesive sheet in a 360° direction by 1 to 1.2 times, the surface resistivity of the base layer is 1.0 × 10 5 ~1.0×10 8 ohms / sq, and the surface resistivity of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is 1.0×10 11 ohms / sq or less, (d) The rate of change in the logarithmic value of the surface resistivity of the PSA sheet calculated by the following formula (1) is 100% or less; Change in logarithmic surface resistivity (%) = [(X2-X1) / X1] × 100% (1) (In the formula, X2 represents the logarithm of the surface resistivity after the pressure-sensitive adhesive sheet has been stretched 1 to 1.2 times in the 360° direction, and X1 represents the logarithm of the surface resistivity of the pressure-sensitive adhesive sheet before stretching.) (e) the pressure-sensitive adhesive sheet has a tensile strength in the longitudinal direction (MD direction) of 15 to 60 MPa; (f) the tensile strength of the pressure-sensitive adhesive sheet in the width direction (TD direction) is 10 to 50 MPa; (g) the ratio of the tensile strength in the longitudinal direction (MD direction) to the tensile strength in the transverse direction (TD direction) of the pressure-sensitive adhesive sheet is 1.0 to 1.5; (h) the 50% modulus of elasticity in the longitudinal direction (MD direction) of the pressure-sensitive adhesive sheet is 15 to 50 MPa; (i) the 50% modulus of elasticity in the width direction (TD direction) of the pressure-sensitive adhesive sheet is 10 to 45 MPa; (j) the breaking elongation in the longitudinal direction (MD direction) of the pressure-sensitive adhesive sheet is 100 to 300%; (k) the pressure-sensitive adhesive sheet has a breaking elongation in the width direction (TD direction) of 80 to 270%; (l) the ratio of the breaking elongation in the longitudinal direction (MD) to the breaking elongation in the transverse direction (TD) of the pressure-sensitive adhesive sheet is 1.0 to 1.5; (m) the pressure-sensitive adhesive sheet has a heat shrinkage rate at 50°C in the longitudinal direction (MD direction) of 1.0 to 8%; (n) the pressure-sensitive adhesive sheet has a heat shrinkage rate at 50°C in the width direction (TD direction) of -6.0 to 3.0%; (o) the light transmittance of the pressure-sensitive adhesive sheet after the release film is removed is 50 to 90%; (p) the pressure-sensitive adhesive sheet is left at 50°C for 72 hours, and then the release film is removed in an environment of 23°C and a relative humidity of 50%, and the haze measured thereafter is 15 to 55%; The pressure-sensitive adhesive sheet according to any one of [1] to

[10] , which satisfies at least one of the above.

[12] The substrate layer comprises a polyvinyl chloride resin and at least one selected from the group consisting of a plasticizer, a stabilizer, and a haze adjuster; The content of the plasticizer is 10 to 60 parts by mass relative to 100 parts by mass of the polyvinyl chloride resin, the plasticizer includes at least one selected from the group consisting of dioctyl phthalate, dioctyl terephthalate, and diisononyl phthalate; The content of the stabilizer is 0.1 to 5.0 parts by mass relative to 100 parts by mass of the polyvinyl chloride resin, The pressure-sensitive adhesive sheet according to any one of [1] to

[11] , wherein the content of the haze adjuster is 0.1 to 10 parts by mass per 100 parts by mass of polyvinyl chloride resin.

[13] . The pressure-sensitive adhesive sheet according to any one of [1] to

[12] , wherein the base layer has an arithmetic mean surface roughness Ra of 1 to 6 μm at 23°C, or the surface of the base layer has a surface roughness with a maximum height (Rz) of 6 to 12 μm at 23°C.

[14] . Further comprising an undercoat layer and / or a backcoat layer; the backcoat layer is provided on the substrate layer on the opposite side to the pressure-sensitive adhesive layer, The pressure-sensitive adhesive sheet according to any one of [1] to

[13] , wherein the undercoat layer is provided on the substrate layer on the side opposite to the backcoat layer.

[15] The backcoat layer has an arithmetic mean surface roughness Ra of 0.1 to 5.0 μm at 23° C., or the surface of the backcoat layer has a surface roughness of a maximum height (Rz) of 1 to 10 μm at 23° C.; The pressure-sensitive adhesive sheet according to

[14] , wherein the backcoat layer has an arithmetic mean surface roughness Ra of 0.1 to 4.0 μm at 50°C, or the surface of the backcoat layer has a surface roughness with a maximum height (Rz) of 2.0 to 8.0 μm at 50°C.

[16] The pressure-sensitive adhesive sheet according to any one of [1] to

[15] , wherein the thickness of the base layer is 5 to 300 μm, and the thickness of the pressure-sensitive adhesive layer is 1 to 40 μm.

[17] The pressure-sensitive adhesive sheet according to any one of [1] to

[16] , wherein the pressure-sensitive adhesive sheet has a rate of change in haze calculated by the following formula (2) of 10% or less. Haze change rate = (haze before aging - haze after aging) / haze before aging × 100% (2) (wherein the formula, the haze before aging is the haze measured after leaving the PSA sheet for 24 hours under a standard environment of 23°C and 50% relative humidity, and then removing the release film.) The post-storage haze is the haze measured after leaving the PSA sheet at 50°C for 72 hours and then removing the release film in an environment of 23°C and 50% relative humidity.

[18] A roll comprising the pressure-sensitive adhesive sheet according to any one of [1] to

[17] in a rolled form.

[19] A laminate comprising two or more pressure-sensitive adhesive sheets according to any one of [1] to

[17] in a laminated form.

[0007] The pressure-sensitive adhesive sheet of the present invention has excellent adhesiveness, stability of haze over time, antistatic properties, shelf life after lamination, and temperature resistance, and can be easily peeled off after use without causing adhesive residue or contamination. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view schematically illustrating the configuration of a pressure-sensitive adhesive sheet according to one embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view schematically showing the configuration of a pressure-sensitive adhesive sheet according to another embodiment of the present invention. [Figure 3] FIG. 3 is a cross-sectional view schematically showing the configuration of a pressure-sensitive adhesive sheet according to still another embodiment of the present invention. [Figure 4] FIG. 4 is a schematic diagram showing the structure of a roll of a pressure-sensitive adhesive sheet according to one embodiment of the present invention. [Figure 5] FIG. 5 is a schematic diagram showing the configuration of a laminate of pressure-sensitive adhesive sheets according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] Various exemplary embodiments, features, and aspects of the present invention are described in detail below. As used herein, the term "exemplary" means "serving as an example, example, or illustration." Any embodiment described as "exemplary" should not be construed as preferred or superior to other embodiments.

[0010] In addition, in order to better explain the present invention, various specific details are provided in the following specific embodiments. It should be understood by those skilled in the art that the present invention can be similarly implemented without certain specific details. In other instances, in order to emphasize the essence of the present invention, detailed descriptions of methods, means, devices, and steps that are familiar to those skilled in the art are not provided.

[0011] Unless otherwise specified, all units used in this specification are international standard units, and it should be understood that all numerical values ​​and numerical ranges described in the present specification include unavoidable systematic errors that occur during industrial production.

[0012] In this specification, the expression "may" includes the meaning of whether or not a certain process is performed.

[0013] As used herein, the terms "some specific / preferred embodiments," "some other specific / preferred embodiments," "embodiments," etc., mean that the particular element (e.g., feature, structure, property, and / or characteristic) associated with the described embodiment is included in at least one embodiment described herein and may or may not be present in other embodiments. Furthermore, it should be understood that the described elements can be combined in any suitable manner in the various embodiments.

[0014] In this specification, a numerical range expressed as "numerical value A to numerical value B" means a range including the limit values ​​A and B.

[0015] <Adhesive sheet> The pressure-sensitive adhesive sheet of the present invention comprises a base layer, a pressure-sensitive adhesive layer provided on one side of the base layer, and a release film provided on the pressure-sensitive adhesive layer on the opposite side to the base layer, wherein the side of the release film away from the surface to be attached to the pressure-sensitive adhesive layer is a matte surface, and the matte surface has an arithmetic mean surface roughness Ra of 0.25 μm or more, or the surface of the matte surface has a surface roughness with a maximum height (Rz) of 1.5 μm or more; The pressure-sensitive adhesive sheet is in a roll or laminate form, the matte surface of the release film is in contact with the surface of the base layer away from the surface that is bonded to the pressure-sensitive adhesive layer, and the haze of the pressure-sensitive adhesive sheet after the release film is removed is 10 to 80%.

[0016] Fig. 1 is a cross-sectional view schematically showing the configuration of a pressure-sensitive adhesive sheet according to one embodiment of the present invention. As shown in Fig. 1, the pressure-sensitive adhesive sheet 1 includes a base layer 10, a pressure-sensitive adhesive layer 20 provided on one side of the base layer 10, and a release film 30 provided on the side of the pressure-sensitive adhesive layer 20 opposite the base layer 10. The pressure-sensitive adhesive layer 20 is preferably provided on the entire surface of the base layer 10. The release film 30 is preferably provided on the entire surface of the pressure-sensitive adhesive layer 20.

[0017] As shown in Figure 1, the base layer 10 has a first surface 10A and a second surface 10B. The pressure-sensitive adhesive layer 20 has a third surface 20A and a fourth surface 20B. The release film 30 has a fifth surface 30A and a sixth surface 30B. The fifth surface 30A of the release film 30 is the side away from the bonding surface (third surface 20A) of the pressure-sensitive adhesive layer 20, and the fifth surface 30A of the release film 30 is the matte surface of the release film.

[0018] When the pressure-sensitive adhesive sheet of the present invention is in the form of a roll, the pressure-sensitive adhesive sheet is rolled up so that the friction surface of the release film abuts against the back surface of the pressure-sensitive adhesive sheet (i.e., the surface of the base layer opposite the adhesive surface of the pressure-sensitive adhesive layer).

[0019] An example of the configuration of a roll of the adhesive sheet disclosed herein is shown in Figure 4. The roll of the adhesive sheet 100 shown in Figure 4 is configured by rolling up in the longitudinal direction an adhesive sheet 1 including: a base layer 10 having a first surface 10A and a second surface 10B; an adhesive layer 20 disposed on the first surface 10A and having a third surface 20A and a fourth surface 20B; and a release film 30 disposed on the third surface 20A and having a fifth surface 30A and a sixth surface 30B. In the roll of the adhesive sheet 100, the adhesive sheet 1 is rolled up so that the fifth surface 30A (matte surface) of the release film 30 abuts against the second surface 10B of the base layer.

[0020] When the pressure-sensitive adhesive sheet of the present invention is present in a laminated form, in the laminate, the friction surface of the release film of the first pressure-sensitive adhesive sheet abuts the surface of the base layer of the second pressure-sensitive adhesive sheet that is away from the surface that is bonded to the pressure-sensitive adhesive layer.

[0021] One structural example of the laminate disclosed herein is shown in Figure 5. Laminate 200 shown in Figure 5 has a first adhesive sheet 201 and a second adhesive sheet 202. The matte surface (fifth surface 30A) of release film 30 of first adhesive sheet 201 contacts the surface (second surface 10B) of base layer 10 of second adhesive sheet 202 that is remote from the bonding surface (fourth surface 20B) of adhesive layer 20; that is, fifth surface 30A of release film 201 contacts second surface 10B of the base layer of second adhesive sheet 202.

[0022] Fig. 2 is a cross-sectional view schematically showing the configuration of a pressure-sensitive adhesive sheet according to another embodiment of the present invention. This pressure-sensitive adhesive sheet 2 further includes a backcoat layer 40. As shown in Fig. 2, the backcoat layer 40 is provided on the opposite side of the substrate layer 10 from the pressure-sensitive adhesive layer 20.

[0023] Fig. 3 is a cross-sectional view schematically showing the configuration of a pressure-sensitive adhesive sheet according to yet another embodiment of the present invention. This pressure-sensitive adhesive sheet 3 further includes an undercoat layer 50. As shown in Fig. 3, the undercoat layer 50 is provided on the opposite side of the substrate layer 10 to the backcoat layer 40, between the substrate layer 10 and the pressure-sensitive adhesive layer 20.

[0024] The concept of adhesive sheet in this specification may include what are called adhesive tapes, adhesive labels, adhesive films, and the like.

[0025] The pressure-sensitive adhesive sheet of the present invention has the following characteristics. The side of the release film away from the surface to be attached to the pressure-sensitive adhesive layer is a matte surface, and the matte surface has an arithmetic mean surface roughness Ra of 0.25 μm or more, preferably 0.35 μm or more, and more preferably 0.4 μm or more. In some preferred embodiments, the matte surface has an arithmetic mean surface roughness Ra of preferably 1.5 μm or less, and more preferably 1.0 μm or less.

[0026] The matte surface has a surface roughness of 1.5 μm or more, preferably 2.0 μm or more, more preferably 2.5 μm or more, in terms of maximum height (Rz). In some preferred embodiments, the matte surface has a surface roughness of 4.0 μm or less, more preferably 3.0 μm or less, in terms of maximum height (Rz).

[0027] The pressure-sensitive adhesive sheet of the present invention exists in a roll form or a laminate form, and the matte surface of the release film contacts the surface of the base layer away from the surface where it is bonded to the pressure-sensitive adhesive layer, and the rough surface of the base layer and the matte surface of the release film work together to distribute the plasticizer, etc. that has migrated to the surface of the base layer evenly on the surface of the base layer, i.e., to distribute it evenly along the unevenness of the surface of the base layer.Therefore, the haze of the pressure-sensitive adhesive sheet of the present invention does not decrease even when stored for a long period of time, and the desired haze can be well maintained.

[0028] The pressure-sensitive adhesive sheet of the present invention is left at 50°C for 72 hours, and then the release film is removed in an environment of 23°C and 50% relative humidity. The haze (post-aging haze) measured after this is 10 to 80%, preferably 15 to 55%. In some specific embodiments, the haze of the pressure-sensitive adhesive sheet of the present invention after removal of the release film is 10%, 20%, 30%, 40%, 50%, 60%, 70%, or 80%.

[0029] In the present invention, the haze change rate represented by the following formula (2) is preferably 10% or less, and more preferably 5% or less. Haze change rate = (haze before aging - haze after aging) / haze before aging × 100% (2) (In the formula, the haze before aging refers to the haze value (initial value) of the PSA sheet before it is stored in a high-temperature / high-humidity environment, i.e., the haze measured after the PSA sheet is left to stand for 24 hours in a standard environment of 23°C and 50% relative humidity, and then the release film is removed.) The haze after aging is measured after leaving the PSA sheet at 50°C for 72 hours, then removing the release film in an environment of 23°C and 50% relative humidity.

[0030] In the present invention, the peel force A when the pressure-sensitive adhesive sheet is peeled at 23°C in a 180° direction at a pulling rate of 300 mm / min is 0.3 to 2.0 N / 20 mm, preferably 0.3 to 1.5 N / 20 mm, and more preferably 0.3 to 1.0 N / 20 mm.

[0031] In the present invention, the pressure-sensitive adhesive sheet is attached to an adherend at 23°C, left at 50°C for 24 hours, and then peeled in a 180° direction at a pulling rate of 300 mm / min, resulting in a peel strength B of 0.5 to 2.5 N / 20 mm, preferably 0.5 to 2.0 N / 20 mm, and more preferably 0.5 to 1.5 N / 20 mm.

[0032] When the peel strength A and peel strength B of the pressure-sensitive adhesive sheet are each within the above ranges, the pressure-sensitive adhesive sheet is endowed with excellent adhesive performance and laminated storage stability, and can be easily peeled off without causing adhesive residue staining after use. On the other hand, when the peel strength is outside the above ranges, the above performance of the pressure-sensitive adhesive sheet may be impaired, and adhesive residue staining may be more likely to occur.

[0033] The peel force can be measured, for example, by the method described in the Examples below, and unless otherwise specified, the speed or peel speed in this specification refers to the speed of the instrument.

[0034] In the present invention, the peel strength when the pressure-sensitive adhesive sheet is peeled at a 180° angle at 23°C at a tensile speed of 300 mm / min is defined as A, and the peel strength when the pressure-sensitive adhesive sheet is attached to an adherend at 23°C, left at 50°C for 24 hours, and then peeled at a 180° angle at a tensile speed of 300 mm / min is defined as B. The difference between B and A, i.e., the difference between B and A, is 0.1 to 0.8 N / 20 mm, preferably 0.1 to 0.6 N / 20 mm, and more preferably 0.1 to 0.5 N / 20 mm. By keeping the difference between the two peel strengths B and B at 0.1 to 0.8 N / 20 mm, excellent stability of the peel strength over time can be achieved.

[0035] In the present invention, the peel force C when the pressure-sensitive adhesive sheet is peeled at 23°C in a 180° direction at a pulling rate of 10 m / min is 1.0 to 5.0 N / 20 mm, preferably 1.0 to 4.0 N / 20 mm, and more preferably 1.0 to 3.0 N / 20 mm.

[0036] In the present invention, the peel force D when the pressure-sensitive adhesive sheet is peeled at 23° C. in a 20° direction at a pulling rate of 10 m / min is 5.0 to 9.0 N / 20 mm, preferably 6.0 to 9.0 N / 20 mm, and more preferably 7.0 to 9.0 N / 20 mm.

[0037] If the peel strength when the pressure-sensitive adhesive sheet is peeled at a pulling rate of 10 m / min in the 180° direction and the 20° direction at 23°C is within the above ranges, the pressure-sensitive adhesive sheet is endowed with excellent chip transfer performance, adhesive performance, and laminated storage stability, and can be easily peeled without causing adhesive residue staining after use. On the other hand, if the peel strength is outside the above ranges, the above performance of the pressure-sensitive adhesive sheet may be impaired and adhesive residue staining may be more likely to occur.

[0038] In the present invention, the peel force when the pressure-sensitive adhesive sheet is peeled at 23°C in a 180° direction at a tensile speed of 10 m / min is defined as C, and the peel force when the pressure-sensitive adhesive sheet is peeled at 23°C in a 20° direction at a tensile speed of 10 m / min is defined as D. The difference DC, the value obtained by subtracting C from D, is 4.0 to 8.0 N / 20 mm, preferably 5.0 to 8.0 N / 20 mm, and more preferably 6.0 to 8.0 N / 20 mm. By setting the difference DC between the two peel forces to 4.0 to 8.0 N / 20 mm, the pressure-sensitive adhesive sheet is endowed with excellent chip transfer performance, adhesive performance, and laminated storage stability, and can be easily peeled without causing adhesive residue contamination after use. On the other hand, if the peel force is outside the above range, the pressure-sensitive adhesive sheet's performance may be impaired and adhesive residue contamination may be more likely to occur.

[0039] In the present invention, the pressure-sensitive adhesive sheet is attached to an adherend at 23°C, left at 50°C for 24 hours, and then peeled in a 180° direction at a pulling rate of 10 m / min, and the peel force E is 1.5 to 5.5 N / 20 mm, preferably 1.5 to 4.5 N / 20 mm, and more preferably 1.5 to 3.5 N / 20 mm.

[0040] In the present invention, the pressure-sensitive adhesive sheet is attached to an adherend at 23°C, left at 50°C for 24 hours, and then peeled at 23°C in a 20° direction at a pulling rate of 10 m / min, and the peel force F is 5.5 to 9.5 N / 20 mm, preferably 6.5 to 9.5 N / 20 mm, and more preferably 7.5 to 9.5 N / 20 mm.

[0041] When the peel strength E and peel strength F of the pressure-sensitive adhesive sheet are each within the above ranges, the pressure-sensitive adhesive sheet can be endowed with excellent stability of high-speed peel strength over time.

[0042] In the present invention, the pressure-sensitive adhesive sheet is attached to an adherend at 23°C, left at 50°C for 24 hours, and then peeled at a 180° angle at a tensile speed of 10 m / min, where E is the peel force; the pressure-sensitive adhesive sheet is attached to an adherend at 23°C, left at 50°C for 24 hours, and then peeled at a 20° angle at 23°C at a tensile speed of 10 m / min, where F is the peel force; the difference between F and E, i.e., FE, is 4.5 to 8.5 N / 20 mm, preferably 5.0 to 8.5 N / 20 mm, and more preferably 6.0 to 8.5 N / 20 mm. By ensuring that the difference between these two peel forces FE is 4.5 to 8.5 N / 20 mm, the pressure-sensitive adhesive sheet can be endowed with excellent high-speed peel strength stability over time.

[0043] In the present invention, the adherend is a SUS430BA plate.

[0044] In the present invention, the pressure-sensitive adhesive sheet satisfies at least one of the following properties: (a) to (p). Property (a): In a peel test at a peel speed of 12 m / min, the peel electrification voltage generated when peeling the pressure-sensitive adhesive sheet from the release film is 500 V or less, preferably 200 V or less, and more preferably 100 V or less. When the peeling electrification voltage is within the above range, peeling electrification that may occur when peeling the pressure-sensitive adhesive sheet can be suppressed, the pressure-sensitive adhesive sheet has excellent antistatic properties (peel-off antistatic properties), does not damage the adherend when peeled, and can effectively prevent problems such as electrostatic breakdown. The peeling electrification voltage can be measured, for example, by the method described in the Examples below. Property (b): The surface resistivity of the adhesive sheet is 1.0 x 10 4 ~1.0×10 11 ohms / sq, preferably 1.0×10 5 ~1.0×10 10 ohms / sq, more preferably 1.0×10 6 ~1.0×10 9 ohms / sq. When the surface resistivity of the pressure-sensitive adhesive sheet is within the above range, it can fulfill its antistatic function, and when it is attached to components such as electronic component materials in production, it can effectively suppress the generation of static electricity and prevent damage to the electronic component materials. Surface resistivity measurement conditions: (23°C / 50% RH atmosphere, electrode area: 20 cm 2 , Applied voltage: 100V, Application time: 30 seconds, Concentric electrode (probe) used). Property (c): After the adhesive sheet is stretched 1 to 1.2 times in the 360° direction, the surface resistivity of the base layer is 1.0 × 10 5 ~1.0×10 8 ohms / sq, preferably 1.0×10 6 ~1.0×10 8 ohms / sq, more preferably 1.0×10 7 ~1.0×10 8 The surface resistivity of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is 1.0×10 11 ohms / sq or less, preferably 1.0×10 10 ohms / sq or less, more preferably 1.0×10 9Within this range, the antistatic function can be satisfied, and when the film is bonded to a member such as an electronic component material, damage to the electronic component material can be prevented. Property (d): The rate of change in the logarithm of the surface resistivity of the pressure-sensitive adhesive sheet calculated by the following formula (1) is 100% or less, preferably 60% or less, and more preferably 30% or less. Change in logarithmic surface resistivity (%) = [(X2-X1) / X1] × 100% (1) (In the formula, X2 represents the logarithm of the surface resistivity after the pressure-sensitive adhesive sheet has been stretched 1 to 1.2 times in the 360° direction, and X1 represents the logarithm of the surface resistivity of the pressure-sensitive adhesive sheet before stretching.) By setting the rate of change in the logarithm of the surface resistivity within the above range, it is possible to achieve excellent antistatic properties and stability of peel electrification voltage over time, thereby satisfying the antistatic function and preventing damage to electronic component materials when the film is attached to members such as electronic component materials. Property (e): The pressure-sensitive adhesive sheet has a tensile strength in the machine direction (MD) of 15 to 60 MPa, preferably 20 to 60 MPa, and more preferably 20 to 50 MPa. Property (f): The tensile strength of the pressure-sensitive adhesive sheet in the width direction (TD direction) is 10 to 50 MPa, preferably 20 to 50 MPa, and more preferably 20 to 40 MPa. When the longitudinal tensile strength or width tensile strength is within the above range, the adhesive sheet has excellent ductility, and is less likely to tear when peeled off, so it has excellent removability and can exhibit good conformability to uneven steps on the adherend. If the tensile strength is not within the above range, sufficient strength cannot be obtained, and ductility may be poor, the flexibility of the adhesive sheet may decrease, and good repulsion resistance may not be obtained (causing tearing of the substrate). The tensile strength can be measured, for example, by the method described in the Examples below. Property (g): The ratio of the tensile strength in the longitudinal direction (MD) to the tensile strength in the transverse direction (TD) of the PSA sheet is 1.0 to 1.5, preferably 1.0 to 1.2. When the tensile strength ratio is within this range, the PSA sheet can be endowed with excellent expandability, adhesive performance, antistatic properties, laminated storage stability, temperature resistance, and transparency, and can be easily peeled off after use without leaving any adhesive residue or contamination. Property (h): The 50% elastic modulus in the longitudinal direction (MD direction) of the pressure-sensitive adhesive sheet is 15 to 50 MPa, and preferably 20 to 40 MPa. Property (i): The 50% modulus of elasticity in the width direction (TD direction) of the pressure-sensitive adhesive sheet is 10 to 45 MPa, and preferably 20 to 40 MPa. By setting the 50% modulus of elasticity in the longitudinal direction (MD direction) and width direction (TD direction) of the pressure-sensitive adhesive sheet within the above ranges, it is possible to avoid the bending strength of the pressure-sensitive adhesive sheet being too small, thereby suppressing a decrease in the workability of the pressure-sensitive adhesive sheet, and also to prevent the rigidity of the sheet from being too high, thereby suppressing problems such as warping or peeling of the pressure-sensitive adhesive sheet due to the repulsive force of the tape, which may occur when the pressure-sensitive adhesive sheet is attached to an adherend, etc. The 50% modulus of elasticity can be measured, for example, by the method described in the Examples below. Property (j): The pressure-sensitive adhesive sheet has a breaking elongation in the machine direction (MD) of 100 to 300%, preferably 150 to 250%. Property (k): The pressure-sensitive adhesive sheet has a breaking elongation in the width direction (TD) of 80 to 270%, and preferably 100 to 250%. When the breaking elongation in the longitudinal direction (MD) and transverse direction (TD) of the pressure-sensitive adhesive sheet is within the above range, the pressure-sensitive adhesive sheet of the present invention can be given an appropriate elongation, and for example, the ability to conform to the adherend is improved, and excellent expandability or ductility is obtained, thereby improving the transferability of the chip. The breaking elongation can be measured, for example, by the method described in the Examples below. Property (1): The ratio of the breaking elongation in the machine direction (MD) to the breaking elongation in the width direction (TD) of the pressure-sensitive adhesive sheet is 1.0 to 1.5, and preferably 1.0 to 1.2. When the elongation at break is within the above range, better conformability to uneven surfaces can be achieved, the occurrence of wrinkles and creases can be better suppressed, and excellent expandability (or ductility) can be provided, while excellent adhesion and removability can be achieved at the same time, thereby improving the transferability of the chip. Property (m): The heat shrinkage rate at 50°C in the longitudinal direction (MD) of the pressure-sensitive adhesive sheet is 1.0 to 8%, and preferably 1.5 to 7%. Property (n): The heat shrinkage rate at 50°C in the width direction (TD direction) of the pressure-sensitive adhesive sheet is -6.0 to 3.0%, and preferably -5.0 to 2%. When the shrinkage percentages of the pressure-sensitive adhesive sheet in the longitudinal direction (MD) and transverse direction (TD) are within the above ranges, the occurrence of wrinkles can be suppressed when the pressure-sensitive adhesive sheet is attached to an adherend and heated, thereby achieving an excellent appearance. The shrinkage percentages can be measured, for example, by the method described in the Examples below. Property (o): The pressure-sensitive adhesive sheet has a light transmittance of 50 to 90%, preferably 60 to 85%, and more preferably 70 to 80% after the release film has been removed. By ensuring that the pressure-sensitive adhesive sheet has a light transmittance within the above range, excellent transparency can be imparted to the pressure-sensitive adhesive sheet.

[0045] [Adhesive layer] The pressure-sensitive adhesive layer of the present invention contains a base polymer and a functional resin, and the content of the functional resin is 10 to 40 parts by mass per 100 parts by mass of the base polymer. The pressure-sensitive adhesive layer in the technology disclosed herein may be a layer formed from a pressure-sensitive adhesive composition containing the base polymer and the functional resin. The form of the pressure-sensitive adhesive composition is not particularly limited, and may be in various forms, such as a water-dispersible type, a solvent-based type, a hot-melt type, or an active energy ray-curable type (e.g., a photocurable type).

[0046] Each component of the pressure-sensitive adhesive composition of the present invention will be described in detail below.

[0047] (base polymer) The pressure-sensitive adhesive composition of the present invention contains a base polymer. Examples of the base polymer include acrylic polymers, rubber polymers, polyester polymers, urethane polymers, polyether polymers, silicone polymers, polyamide polymers, and fluorine-based polymers. Preferably, the pressure-sensitive adhesive composition contains an acrylic polymer as the base polymer.

[0048] The content of the base polymer is not particularly limited, but from the viewpoint of obtaining sufficient adhesive reliability, it is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more, relative to the total amount of the pressure-sensitive adhesive composition (total weight, 100% by mass). By adjusting the content of the base polymer in the pressure-sensitive adhesive composition to fall within the above range, a pressure-sensitive adhesive composition that is excellent in stress relaxation properties and durability and in adhesion to adherends can be provided.

[0049] The base polymer in the technology disclosed herein is preferably a polymer of monomer components including a soft monomer (adhesive monomer) as a main monomer, a functional monomer (copolymerizable monomer) copolymerizable with the main monomer, and a hard monomer. Here, the main monomer refers to the main component among the monomer components constituting the base polymer, i.e., a component contained in more than 50 wt% of the monomer components.

[0050] In a preferred embodiment, the soft monomer (adhesive monomer) comprises an alkyl (meth)acrylate. As used herein, the term "alkyl (meth)acrylate" refers to alkyl acrylate and / or alkyl methacrylate.

[0051] The alkyl (meth)acrylate is preferably an alkyl (meth)acrylate in which the alkyl group has 4 to 20 carbon atoms. Specific examples of the alkyl (meth)acrylate in which the alkyl group has 4 to 20 carbon atoms are not particularly limited, but include n-butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, Examples of the alkyl (meth)acrylate include nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate. Among these, n-butyl acrylate (BA) and 2-ethylhexyl acrylate (2EHA) are preferred. The alkyl (meth)acrylate may be used alone or in combination of two or more.

[0052] The content of the soft monomer (adhesive monomer) is preferably 60 to 93 parts by mass, and more preferably 60 to 80 parts by mass, relative to 100 parts by mass of all monomer components of the base polymer. When the content of the soft monomer is within the above range, excellent adhesiveness can be obtained.

[0053] As the hard monomer, a hard monomer capable of forming a hard polymer having a relatively high glass transition temperature can be preferably used. The hard monomer is useful for increasing the cohesive strength of the pressure-sensitive adhesive layer. The hard monomer can be used alone or in combination of two or more.

[0054] Non-limiting examples of hard monomers include N-vinylpyrrolidone (NVP), acrylonitrile (AN), methyl methacrylate (MMA), methyl acrylate (MA), vinyl acetate (VAC), styrene, and the like.

[0055] The content of the hard monomer is preferably 7 to 40 parts by mass, and more preferably 20 to 40 parts by mass, relative to 100 parts by mass of all monomer components of the base polymer. When the content of the hard monomer is within the above range, cohesive strength and heat resistance can be further improved.

[0056] As the functional monomer (copolymerizable monomer), a monomer having a polar group can be suitably used. The monomer having a polar group is useful for introducing crosslinking points into the base polymer and for increasing the cohesive strength of the base polymer. The functional monomer can be used alone or in combination of two or more types.

[0057] Non-limiting specific examples of functional monomers include hydroxyl group-containing monomers (monomers containing a hydroxyl group), carboxyl group-containing monomers (monomers containing a carboxyl group), sulfonic acid group-containing monomers, phosphoric acid group-containing monomers, epoxy group-containing monomers, isocyanate group-containing monomers, amide group-containing monomers, monomers having a succinimide skeleton, maleimide-based monomers, itaconimide-based monomers, aminoalkyl (meth)acrylate-based monomers, alkoxyalkyl (meth)acrylate-based monomers, vinyl ether-based monomers, olefin-based monomers, etc. Among these, at least one selected from hydroxyl group-containing monomers and carboxyl group-containing monomers is preferred.

[0058] The content of the functional monomer is preferably 1 to 10 parts by mass, and more preferably 1 to 5 parts by mass, relative to 100 parts by mass of all monomer components of the base polymer. When the content of the functional monomer is within the above range, the cohesive strength of the PSA can be prevented from becoming too high, and the adhesiveness can be improved.

[0059] A hydroxyl group-containing monomer refers to a monomer having at least one hydroxyl group in its molecule. When the monomer components constituting the base polymer contain a hydroxyl group-containing monomer, i.e., when the base polymer contains a monomer unit derived from a hydroxyl group-containing monomer, secondary bonds such as hydrogen bonds are formed with the adherend, thereby increasing the cohesive strength of the base polymer (preferably an acrylic polymer), more effectively suppressing changes in adhesive strength over time, and leaving less adhesive residue on the adherend after peeling, resulting in higher cohesive strength. Furthermore, by including a hydroxyl group-containing monomer in the raw material monomers of the base polymer, when a crosslinking agent is used, a crosslinking reaction with the crosslinking agent can be effectively initiated, allowing the adhesive to fully exert its effects as a pressure-sensitive adhesive. Furthermore, cracking of the adherend during peeling can also be effectively prevented. The base polymer of this embodiment may contain one type of hydroxyl group-containing monomer or two or more types of hydroxyl group-containing monomers.

[0060] Specific examples of hydroxyl group-containing monomers include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl (meth)acrylate.

[0061] The content of the hydroxyl group-containing monomer is not particularly limited. For example, the content of the hydroxyl group-containing monomer is 0.5 to 10 parts by mass, preferably 1 to 9 parts by mass, relative to 100 parts by mass of all monomer components of the base polymer. When the content of the hydroxyl group-containing monomer is within the above range, secondary bonds such as hydrogen bonds are formed with the adherend, thereby increasing the cohesive strength of the base polymer (preferably an acrylic polymer), more effectively suppressing changes in adhesive strength over time, and leaving less adhesive residue on the adherend after peeling, resulting in higher cohesiveness. When the content of the hydroxyl group-containing monomer is less than 0.5 parts by mass, sufficient adhesion cannot be obtained. When the content of the hydroxyl group-containing monomer is more than 10 parts by mass, the adhesive strength becomes too high, which may lead to blocking. Furthermore, the adherend may be more likely to crack during the peeling process.

[0062] A carboxyl group-containing monomer refers to a monomer having at least one carboxyl group in the molecule. By including a carboxyl group-containing monomer in the raw material monomer of the base polymer, secondary bonds such as hydrogen bonds with the adherend are formed, thereby increasing the cohesive strength of the base polymer (preferably an acrylic polymer), more effectively suppressing changes in adhesive strength over time, and leaving less adhesive residue on the adherend after peeling, resulting in higher cohesive strength. Furthermore, by including a carboxyl group-containing monomer in the raw material monomer of the base polymer, when a crosslinking agent is used, a crosslinking reaction with the crosslinking agent can be effectively initiated, allowing the adhesive to fully exhibit its effectiveness as an adhesive and effectively preventing cracking of the adherend during peeling.

[0063] Specific examples of carboxyl group-containing monomers include acrylic acid, methacrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, crotonic acid, isocrotonic acid, fumaric acid, itaconic acid, maleic acid, citric acid, maleic anhydride, and itaconic anhydride. Among these, acrylic acid and methacrylic acid are preferred. The above carboxyl group-containing monomers can be used alone or in combination of two or more.

[0064] The content of the carboxyl group-containing monomer is not particularly limited. For example, the content of the carboxyl group-containing monomer is preferably 0.5 to 10 parts by mass, more preferably 1 to 6 parts by mass, per 100 parts by mass of all monomer components of the base polymer. When the content of the carboxyl group-containing monomer is within the above range, secondary bonds such as hydrogen bonds are formed with the adherend, thereby increasing the cohesive strength of the base polymer (preferably an acrylic polymer), more effectively suppressing changes in adhesive strength over time, and leaving less adhesive residue on the adherend after peeling, resulting in higher cohesiveness. When the content of the carboxyl group-containing monomer exceeds 10 parts by mass, the adhesive strength may become too high, which may lead to blocking. Furthermore, the adherend may be more likely to crack during the peeling process. When the content of the carboxyl group-containing monomer is less than 0.5 parts by mass, sufficient adhesion cannot be obtained.

[0065] Examples of sulfonic acid group-containing monomers include styrenesulfonic acid, allylsulfonic acid, sodium vinylsulfonate, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid.

[0066] Examples of epoxy group-containing monomers include epoxy group-containing acrylates such as glycidyl (meth)acrylate and 2-ethyl glycidyl ether (meth)acrylate, allyl glycidyl ether, and glycidyl ether (meth)acrylate.

[0067] Examples of isocyanate group-containing monomers include 2-isocyanatoethyl (meth)acrylate.

[0068] Examples of the amide group-containing monomer include (meth)acrylamide; N,N-dialkyl(meth)acrylamides such as N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N,N-diisopropyl(meth)acrylamide, N,N-di(n-butyl)(meth)acrylamide, and N,N-di(t-butyl)(meth)acrylamide; N-ethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-butyl(meth)acrylamide, and Nn-butyl(meth)acrylamide; N-alkyl(meth)acrylamides such as N-vinyl amide; N-vinyl carboxylic acid amides such as N-vinylacetamide; N,N-dimethylaminopropyl(meth)acrylamide, hydroxyethyl acrylamide, N-methylol alkyl(meth)acrylamide, N-hydroxyethyl(meth)acrylamide, N-methylolpropane(meth)acrylamide, N-methoxymethyl(meth)acrylamide, N-methoxyethyl(meth)acrylamide, N-butoxymethyl(meth)acrylamide, N-(meth)acryloylmorpholine, and the like.

[0069] Examples of the monomer having a succinimide skeleton include N-(meth)acryloyloxymethylene succinimide, N-(meth)acryloyl-6-oxyhexamethylene succinimide, and N-(meth)acryloyl-8-oxyhexamethylene succinimide.

[0070] Examples of maleimide-based monomers include N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, and N-phenylmaleimide.

[0071] Examples of the itaconimide monomer include N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, and N-laurylitaconimide.

[0072] Examples of aminoalkyl (meth)acrylate monomers include aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, and t-butylaminoethyl (meth)acrylate.

[0073] Examples of the alkoxyalkyl (meth)acrylate monomer include methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, propoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, and ethoxypropyl (meth)acrylate.

[0074] Examples of vinyl ether monomers include vinyl alkyl ethers such as methyl vinyl ether and ethyl vinyl ether.

[0075] Examples of olefin-based monomers include ethylene, butadiene, isoprene, and isobutylene.

[0076] The method for obtaining the base polymer is not particularly limited, and various known polymerization methods such as solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, and photopolymerization can be appropriately employed. For example, solution polymerization can be preferably employed. The monomer supply method for solution polymerization can be appropriately selected from a batch feed mode in which all monomer raw materials are supplied at once, a continuous feed (dropping) mode, a divided feed (dropping) mode, and the like. The polymerization temperature for solution polymerization can be appropriately selected depending on the types of monomers and solvents used, the type of polymerization initiator, and the like, and can be, for example, about 20°C to 170°C (typically about 40°C to 140°C).

[0077] The solvent (polymerization solvent) used in solution polymerization can be appropriately selected from conventionally known organic solvents. For example, any one solvent or a mixture of two or more solvents selected from aromatic compounds (typically aromatic hydrocarbons) such as toluene, acetate esters such as ethyl acetate, aliphatic or alicyclic hydrocarbons such as hexane and cyclohexane, halogenated alkanes such as 1,2-dichloroethane, lower alcohols (for example, monohydric alcohols having 1 to 4 carbon atoms) such as isopropyl alcohol, ethers such as tert-butyl methyl ether, and ketones such as methyl ethyl ketone can be used.

[0078] The initiator used in the polymerization can be appropriately selected from conventionally known polymerization initiators depending on the type of polymerization method. For example, one or more azo-based polymerization initiators such as 2,2'-azobisisobutyronitrile (AIBN) can be preferably used. Other examples of polymerization initiators include 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 aromatic carbonyl compounds. Still other examples of polymerization initiators include redox-based initiators formed by combining a peroxide with a reducing agent. Such polymerization initiators can be used alone or in combination of two or more. The amount of polymerization initiator used may be a typical amount, and can be selected, for example, from about 0.005 to about 1 part by mass (typically about 0.01 to about 1 part by mass) per 100 parts by mass of all monomer components.

[0079] The weight-average molecular weight (Mw) of the base polymer (preferably an acrylic polymer) in the technology disclosed herein is not particularly limited and can be, for example, 1,000,000 or less, preferably 400,000 or more. Generally, when the weight-average molecular weight Mw exceeds 1,000,000, the cohesive force tends to increase due to the effect of entanglement of the polymer, reducing fluidity, and a sufficient adhesive area may not be obtained, making it impossible to fix the adherend.

[0080] Here, the weight-average molecular weight (Mw) refers to a value calculated as a standard polystyrene by gel permeation chromatography (GPC). The GPC apparatus used may be, for example, a model "HLC-8320GPC" (column: TSKgel GMH-H(S), manufactured by Tosoh Corporation).

[0081] (Functional resin) The pressure-sensitive adhesive composition of the present invention contains a functional resin, which may be at least one selected from the group consisting of epoxy resins, phenolic resins, vinyl resins, and rosin resins.

[0082] The epoxy resin is not particularly limited, and various epoxy resins such as triphenylmethane-type epoxy resins, cresol novolac-type epoxy resins, biphenyl-type epoxy resins, modified bisphenol A-type epoxy resins, bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, modified bisphenol F-type epoxy resins, dicyclopentadiene-type epoxy resins, phenol novolac-type epoxy resins, and phenoxy resins can be used. These epoxy resins can be used alone or in combination of two or more. From the viewpoint of ensuring the reactivity of the epoxy resin, epoxy resins having an epoxy equivalent of 150 to 250 g / eq, a softening point or melting point of 50 to 130°C, and being solid at room temperature are preferred. Among these, triphenylmethane-type epoxy resins, cresol phenol-type epoxy resins, and biphenyl-type epoxy resins are more preferred from the viewpoint of reliability. Bisphenol F-type epoxy resins are also preferred.

[0083] As the phenolic resin, phenol novolac resin, phenol aralkyl resin, and phenol biphenylene resin can be suitably used, and these phenolic resins can be used alone or in combination of two or more kinds.

[0084] The vinyl resin is not particularly limited, and may be a vinyl-containing homopolymer or copolymer, such as an ethylene-vinyl acetate copolymer, a vinyl chloride-vinyl acetate copolymer, polyvinyl chloride, polyvinyl alcohol, etc. These vinyl resins may be used alone or in combination of two or more.

[0085] The rosin resin is not particularly limited, and known resins can be used, and these can be used alone or in combination of two or more kinds.

[0086] The functional resin is preferably a phenol novolac resin, an ethylene-vinyl acetate copolymer, a vinyl chloride-vinyl acetate copolymer, polyvinyl chloride, polyvinyl alcohol, or the like.

[0087] The content of the functional resin relative to 100 parts by mass of the base polymer is 10 to 40 parts by mass, preferably 15 to 30 parts by mass, and more preferably 15 to 20 parts by mass. By setting the content of the functional resin within the above range, it is possible to impart excellent adhesive performance, antistatic properties, laminated storage stability, and temperature resistance to the pressure-sensitive adhesive sheet, and it can be easily peeled off after use without causing adhesive residue or contamination.

[0088] (plasticizer) In the present invention, the pressure-sensitive adhesive layer contains a plasticizer. Examples of the plasticizer include terephthalate esters, isophthalate esters, phthalate esters, trimellitate esters, adipate esters (e.g., dioctyl adipate, diisononyl adipate, etc.), adipate polyesters, phosphate esters (e.g., tricresyl phosphate, etc.), citrate esters (e.g., acetyl tributyl citrate, etc.), sebacate esters, acelate esters, maleate esters, benzoate esters, polyether polyesters, epoxy polyesters, and polyesters (e.g., low-molecular-weight polyesters formed from carboxylic acids and diols). At least one of diisononyl phthalate, dioctyl phthalate, dioctyl terephthalate, and bis(2-ethylhexyl) phthalate is preferred. The plasticizer may be used alone or in combination of two or more types.

[0089] Examples of terephthalate ester plasticizers include dibutyl terephthalate (DBTP), diisobutyl terephthalate (DIBTP), di-normal hexyl terephthalate (DHTP), bis(2-ethylhexyl) terephthalate (DOTP), di-normal octyl terephthalate (DnOTP), diisononyl terephthalate (DINTP), dinonyl terephthalate (DNTP), diisodecyl terephthalate (DIDTP), and bisbutylbenzyl terephthalate (BBTP).

[0090] As the phthalate ester plasticizer, for example, a diester of phthalic acid and an alkyl alcohol having 4 to 16 carbon atoms (preferably 6 to 14, typically 8 to 13) can be used, and suitable examples include di-n-octyl phthalate, di-2-ethylhexyl phthalate, diisononyl phthalate, and diisodecyl phthalate.

[0091] As the trimellitic acid ester plasticizer, for example, a triester of trimellitic acid and an alkyl alcohol having 6 to 14 carbon atoms (typically 8 to 12) is used, and suitable examples include trimellitic acid tri-n-octyl, trimellitic acid tri-2-ethylhexyl, triisononyl trimellitate, tri-n-decyl trimellitate, and triisodecyl trimellitate.

[0092] As the adipate plasticizer, for example, a diester of adipic acid and an alkyl alcohol having 4 to 16 carbon atoms (preferably 6 to 14, typically 8 to 13) is used, and suitable examples include di-n-octyl adipate, di-2-ethylhexyl adipate, and diisononyl adipate.

[0093] Examples of the polyester-based plasticizer include polyester compounds obtained from polycarboxylic acids such as succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, citric acid, phthalic acid, isophthalic acid, terephthalic acid, and trimellitic acid, and polyhydric alcohols such as (poly)ethylene glycol (here, so-called "(poly)ethylene glycol" refers collectively to ethylene glycol and polyethylene glycol; the same applies hereinafter), (poly)propylene glycol, (poly)butylene glycol, (poly)hexanediol, (poly)neopentyl glycol, and polyvinyl alcohol. The polycarboxylic acid is preferably an aliphatic dicarboxylic acid having 4 to 12 carbon atoms (typically 6 to 10), and suitable examples include adipic acid and sebacic acid. Adipic acid is particularly desirable from the standpoints of versatility and price. The polyhydric alcohol is preferably an aliphatic diol having 2 to 10 carbon atoms, and suitable examples include ethylene glycol and butanediol (for example, 1,3-butanediol, 1,4-butanediol).

[0094] The molecular weight of the plasticizer is not particularly limited. In some preferred embodiments, the molecular weight of the plasticizer is 1,000 or less, preferably 800 or less, and more preferably 600 or less. The upper limit of the molecular weight of the plasticizer is not particularly limited, but from the viewpoint of handleability and the like, the molecular weight of the plasticizer may be, for example, 250 or more, or 400 or more.

[0095] The content of the plasticizer is preferably 20 to 90 parts by mass, more preferably 25 to 80 parts by mass, per 100 parts by mass of the base polymer. Within this range, a PSA sheet with excellent flexibility and excellent conformability to the adherend can be obtained. If the content exceeds 90 parts by mass, unwanted elution of the plasticizer may occur.

[0096] In some specific embodiments, the plasticizer is present in an amount of 20 parts, 30 parts, 40 parts, 50 parts, 60 parts, 70 parts, 80 parts, or 90 parts by weight per 100 parts by weight of the base polymer.

[0097] (antistatic agent) In the present invention, the pressure-sensitive adhesive composition preferably further contains an antistatic agent.

[0098] Examples of the antistatic agent contained in the composition for forming a pressure-sensitive adhesive layer include conductive polymers, conductive inorganic fine particles, metal fine particles or fibers, ionic compounds, ionic surfactants, etc. These antistatic agents may be used alone or in combination of two or more.

[0099] <Conductive polymer> Examples of the conductive polymer include polyaniline, polypyrrole, polythiophene, polyquinoxaline, polyacetylene, polyethyleneimine, and allylamine-based polymers. Among these, polyaniline and polythiophene, which are easily capable of forming water-soluble conductive polymers or water-dispersible conductive polymers, are preferably used. These conductive polymers may be used alone or in combination of two or more.

[0100] <Conductive inorganic particles> Examples of the conductive inorganic fine particles include conductive metal oxides, carbon nanotubes, graphene, fullerene, acetylene black, ketjen black, natural graphite, artificial graphite, titanium black, etc. These conductive inorganic fine particles may be used alone or in combination of two or more.

[0101] Examples of conductive metal oxides include tin oxide, antimony oxide, indium oxide, and zinc oxide. Examples of tin oxide conductive fine particles include tin oxide, antimony-doped tin oxide, indium-doped tin oxide, aluminum-doped tin oxide, tungsten-doped tin oxide, a titanium oxide-cerium oxide-tin oxide composite, and a titanium oxide-tin oxide composite. The average particle size of the fine particles is 1 to 100 nm, preferably 2 to 50 nm.

[0102] <Metallic fine particles or fibers> Any suitable metal particles or fibers can be used as long as the effects of the present invention can be obtained. Examples include particles and nanowires made of gold, silver, copper, aluminum, nickel, or alloys thereof. These metal particles or fibers may be used alone or in combination of two or more.

[0103] <Ionic compounds> Examples of ionic compounds include alkali metal salts and / or organic cation-anion salts. In the present invention, the term "organic cation-anion salt" refers to an organic salt whose cation moiety is composed of an organic substance, and whose anion moiety may be either organic or inorganic. "Organic cation-anion salt" is also called an ionic liquid or ionic solid. These ionic compounds may be used alone or in combination of two or more.

[0104] The alkali metal salt may be an organic or inorganic salt of an alkali metal.

[0105] Examples of alkali metal ions constituting the cation moiety of the alkali metal salt include ions of lithium, sodium, potassium, etc. Among these alkali metal ions, lithium ions are preferred.

[0106] The anion portion of the alkali metal salt may be composed of an organic substance or an inorganic substance.

[0107] The anion moiety constituting the organic salt is, for example, CH3COO - , CF3COO - , CH3SO3 - , CF3SO3 - , (CF3SO2)3C - , C4F9SO3 - , C3F7COO - , (CF3SO2)(CF3CO)N - , (FSO2)2N - , - O3S(CF2)3SO3 - , PF6 - , CO3 2- or the following general formulas (1) to (4): (1):(C n F 2n+1 SO2)2N - (where n is an integer from 1 to 10), (2):CF2(C m F 2m SO2)2N - (where m is an integer from 1 to 10), (3): - O3S(CF2) l SO3 - (where l is an integer from 1 to 10), (4):(C p F 2p+1 SO2)N - (C q F 2q+1 SO2) (where p and q are integers from 1 to 10) In particular, an anion moiety containing a fluorine atom is preferably used because it gives an ionic compound with good ionic dissociation properties.

[0108] The anion moiety that constitutes inorganic salts is Cl. - , Br - , I - , AlCl4 - , Al2Cl7 - , BF4 - , PF6 - , ClO4 - , NO3 - , AsF6 - , SbF6 - , NbF6 - , TaF6 - , (CN)2N - etc. are used.

[0109] The anion portion is (CF3SO2)2N - , (C2F5SO2)2N - (Perfluoroalkylsulfonyl)imides represented by the above general formula (1), such as (CF3SO2)2N - Particularly preferred is trifluoromethanesulfonylimide represented by the following formula:

[0110] Specific examples of organic salts of alkali metals include sodium acetate, sodium alginate, sodium lignosulfonate, sodium toluenesulfonate, LiCF3SO3, Li(CF3SO2)2N, Li(CF3SO2)2N, Li(C2F5SO2)2N, Li(C4F9SO2)2N, Li(CF3SO2)3C, K03S(CF2)3SO3K, LiO3S(CF2)3SO3K, and the like. Of these, LiCF3SO3, Li(CF3SO2)2N, Li(C2F5SO2)2N, Li(C4F9SO2)2N, Li(CF3SO2)3C, and the like are preferred, with fluorine-containing imide lithium salts such as Li(CF3SO2)2N, Li(C2F5SO2)2N, and Li(C4F9SO2)2N being more preferred, and (perfluoroalkylsulfonyl)imide lithium salts being particularly preferred.

[0111] Examples of inorganic salts of alkali metals include lithium perchlorate and lithium iodide.

[0112] The organic cation-anion salt used in the present invention is composed of a cation component and an anion component, and the cation component is composed of an organic substance. Specific examples of the cation component include pyridinium cation, piperidinium cation, pyrrolidinium cation, cation having a pyrroline skeleton, cation having a pyrrole skeleton, imidazolium cation, tetrahydropyrimidinium cation, dihydropyrimidinium cation, pyrazolium cation, pyrazolinium cation, tetraalkylammonium cation, trialkylsulfonium cation, and tetraalkylphosphonium cation.

[0113] Examples of anion components include Cl - , Br - , I - , AlCl4 - , Al2Cl7 - , BF4 - , PF6 - , ClO4 - , NO3 - , CH3COO - , CF3COO - , CH3SO3 - , CF3SO3 - , (CF3SO2)3C - , AsF6 - , SbF6 - , NbF6 - , TaF6 - , (CN)2N - , C4F9SO3 - , C3F7COO - , (CF3SO2)(CF3CO)N - , (FSO2)2N - , - O3S(CF2)3SO3 - , or the following general formulas (1) to (4), (1):(C n F 2n+1 SO2)2N - (where n is an integer from 1 to 10), (2):CF2(C m F 2m SO2)2N - (where m is an integer from 1 to 10), (3): - O3S(CF2) l SO3 - (where l is an integer from 1 to 10), (4):(C p F 2p+1 SO2)N - (C q F 2q+1 SO2) (where p and q are integers from 1 to 10) Among these, an anion component containing a fluorine atom is particularly preferred because it gives an ionic compound with good ionic dissociation properties.

[0114] In some preferred embodiments, the organic cation-anion salt is preferably a nitrogen-containing onium salt, a sulfur-containing onium salt, or a phosphorus-containing onium salt, because these salts exhibit excellent antistatic properties.

[0115] Examples of the organic cation-anion salts in the present invention include 1-butylpyridinium tetrafluoroborate, 1-butylpyridinium hexafluorophosphate, 1-butyl-3-methylpyridinium tetrafluoroborate, 1-butyl-3-methylpyridinium trifluoromethanesulfonate, 1-butyl-3-methylpyridinium bis(trifluoromethanesulfonyl)imide, 1-butyl-3-methylpyridinium bis(pentafluoroethanesulfonyl)imide, 1-hexylpyridinium tetrafluoroborate, 1,1-dimethylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-methyl-1-ethylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-methyl-1-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-methyl-1-butylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-methyl-1-pentylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-methyl-1-hexylpyrrolidinium 1-methyl-1-heptylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-ethyl-1-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-ethyl-1-butylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-ethyl-1-pentylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-ethyl-1-hexylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-ethyl-1-heptylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1,1-dipropylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-propyl-1-butylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1,1-dibutylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-propylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-pentylpiperidinium bis(trifluoromethanesulfonyl)imide, 1,1-Dimethylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-methyl-1-ethylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-methyl-1-propylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-methyl-1-butylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-methyl-1-pentylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-methyl-1-hexylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-methyl-1-heptylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-ethyl-1-propylpiperidinium bis (trifluoromethanesulfonyl)imide, 1-ethyl-1-butylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-ethyl-1-pentylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-ethyl-1-hexylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-ethyl-1-heptylpiperidinium bis(trifluoromethanesulfonyl)imide, 1,1-dipropylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-propyl-1-butylpiperidinium bis(trifluoromethanesulfonyl)imide, 1,1-dibutylpiperidinium bis(trifluoromethanesulfonyl)imide,1-Dimethylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1-methyl-1-ethylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1-methyl-1-propylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1-methyl-1-butylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1-methyl-1-pentylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1-methyl-1-hexylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1-methyl-1-heptylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1-ethyl-1-propylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1-ethyl-1-butylpyrrolidinium 1-ethyl-1-pentylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1-ethyl-1-hexylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1-ethyl-1-heptylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1,1-dipropylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1-propyl-1-butylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1,1-dibutylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1-propylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1-pentylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1,1-dimethylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1-methyl-1-ethylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1-methyl-1-propylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1-methyl-1-butylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1-methyl-1-pentylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1-methyl-1-hexylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1-methyl-1-heptylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1-ethyl-1-propylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1-ethyl-1 -butylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1-ethyl-1-pentylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1-ethyl-1-hexylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1-ethyl-1-heptylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1,1-dipropylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1-propyl-1-butylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1,1-dibutylpiperidinium bis(pentafluoroethanesulfonyl)imide, 2-methyl-1-pyrroline tetrafluoroborate, 1-ethyl-2-phenylindolium tetrafluoroborate, 1,2-Dimethylindolium tetrafluoroborate, 1-ethylcarbazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium acetate, 1-ethyl-3-methylimidazolium trifluoroacetate, 1-ethyl-3-methylimidazolium heptafluorobutanoate, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, 1-ethyl-3-methylimidazolium perfluorobutanesulfonate, 1-ethyl-3-methylimidazolium difluoromethanesulfonate Cyandiamide salt, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-ethyl-3-methylimidazolium bis(pentafluoroethanesulfonyl)imide, 1-ethyl-3-methylimidazolium tri(trifluoromethanesulfonyl)methylate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium trifluoroacetate, 1-butyl-3-methylimidazolium heptafluorobutanol phosphate, 1-butyl-3-methylimidazolium trifluoromethanesulfonate, 1-butyl-3-methylimidazolium perfluorobutanesulfonate, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-hexyl-3-methylimidazolium bromide, 1-hexyl-3-methylimidazolium chloride, 1-hexyl-3-methylimidazolium tetrafluoroborate, 1-hexyl-3-methylimidazolium hexafluorophosphate, 1-hexyl-3-methylimidazolium trifluoro Methanesulfonate, 1-octyl-3-methylimidazolium tetrafluoroborate, 1-octyl-3-methylimidazolium hexafluorophosphate, 1-hexyl-2,3-dimethylimidazolium tetrafluoroborate, 1,2-dimethyl-3-propylimidazolium bis(trifluoromethanesulfonyl)imide, 1-methylpyrazolium tetrafluoroborate, 3-methylpyrazolium tetrafluoroborate, N,N-dimethyl-N-ethyl-N-propylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-ethyl-N-butylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-ethyl-N-pentylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-ethyl-N-hexylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-ethyl-N-heptylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-ethyl-N-nonylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N,N-dipropylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-propyl-N-butylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-propyl-N-pentylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-propyl-N-hexylammonium bis(trifluoromethanesulfonyl)imide N,N-dimethyl-N-propyl-N-heptylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-butyl-N-hexylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-butyl-N-heptylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-pentyl-N-hexylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N,N-dihexylammonium bis(trifluoromethanesulfonyl)imide, trimethylheptylammonium bis(trifluoromethanesulfonyl)imide, N,N-diethyl-N-methyl-N-propylammonium bis(trifluoromethanesulfonyl)imide, N,N-diethyl-N-methyl-N-pentylammonium bis(trifluoromethanesulfonyl)imide, N,N-diethyl-N-methyl-N-heptylammonium bis(trifluoromethanesulfonyl)imideN-diethyl-N-propyl-N-pentylammonium bis(trifluoromethanesulfonyl)imide, triethylpropylammonium bis(trifluoromethanesulfonyl)imide, triethylpentylammonium bis(trifluoromethanesulfonyl)imide, triethylheptylammonium bis(trifluoromethanesulfonyl)imide, N,N-dipropyl-N-methyl-N-ethylammonium bis(trifluoromethanesulfonyl)imide, N,N-dipropyl-N-methyl-N-pentylammonium bis(trifluoromethanesulfonyl)imide, N,N-dipropyl-N-butyl-N-hexylammonium bis(trifluoromethanesulfonyl)imide, N,N-dipropyl-N,N-dihexylammonium bis(trifluoromethanesulfonyl)imide, N,N-dibutyl-N-methyl-N-pentylammonium bis(trifluoromethanesulfonyl), trifluoromethanesulfonyl)imide, N,N-dibutyl-N-methyl-N-hexylammonium bis(trifluoromethanesulfonyl)imide, trioctylmethylammonium bis(trifluoromethanesulfonyl)imide, N-methyl-N-ethyl-N-propyl-N-pentylammonium bis(trifluoromethanesulfonyl)imide, 1-butylpyridinium (trifluoromethanesulfonyl)trifluoroacetamide salt, 1-butyl-3-methylpyridinium (trifluoromethanesulfonyl)trifluoroacetamide salt, 1-ethyl-3-methylimidazolium (trifluoromethanesulfonyl)trifluoroacetamide salt, tetrahexylammonium bis(trifluoromethanesulfonyl)imide, diallyldimethylammonium tetrafluoroborate, diallyldimethylammonium trifluoromethanesulfonate, diallyldimethylammonium bis(trifluoromethanesulfonyl)imide

[0033] Also included are N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium tetrafluoroborate, N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium trifluoromethanesulfonate, N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide, N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(pentafluoroethanesulfonyl)imide, glycidyltrimethylammonium trifluoromethanesulfonate, glycidyltrimethylammonium bis(trifluoromethanesulfonyl)imide, glycidyltrimethylammonium bis(pentafluoroethanesulfonyl)imide, and diallyldimethylbis(pentafluoroethanesulfonyl)imide.

[0116] The method for synthesizing the organic cation anion salt is not particularly limited as long as it can produce the desired organic cation anion salt, but generally, the halide method, hydroxide method, acid ester method, complex formation method, neutralization method, or the like, as described in the literature "Ionic Liquids - The Frontline and Future of Development" [published by CMC Publishing Co., Ltd.], is used. Alternatively, commercially available organic cation anion salts can also be used.

[0117] <Ionic surfactants> Examples of the ionic surfactant include cationic surfactants (e.g., quaternary ammonium salt type, phosphonium salt type, sulfonium salt type, etc.), anionic surfactants (e.g., carboxylic acid type, sulfonate type, sulfate type, phosphate type, phosphite type, etc.), zwitterionic surfactants (e.g., sulfobetaine type, alkylbetaine type, alkylimidazolium betaine type, etc.), and nonionic surfactants (e.g., polyhydric alcohol derivatives, β-cyclodextrin inclusion complexes, sorbitan fatty acid monoesters / diesters, polyalkylene oxide derivatives, amine oxide, etc.). These ionic surfactants may be used alone or in combination of two or more.

[0118] In some preferred embodiments, the content of the antistatic agent is preferably 0.1 to 15 parts by mass, more preferably 0.5 to 10 parts by mass, per 100 parts by mass of the base polymer. In some preferred embodiments, the content of the antistatic agent is preferably 0.1 parts by mass, 0.5 parts by mass, 1 part by mass, 5 parts by mass, 10 parts by mass, or 15 parts by mass, per 100 parts by mass of the base polymer. When the content of the antistatic agent is within the above range, a sufficient antistatic effect is obtained, peel electrification that occurs during peeling is sufficiently suppressed, and damage to the adherend can be avoided or reduced. The pressure-sensitive adhesive composition of the present invention preferably further contains a crosslinking agent.

[0119] (Crosslinking agent) In the present invention, in order to adjust the cohesive strength, etc., the pressure-sensitive adhesive composition preferably contains a crosslinking agent. A commonly used crosslinking agent can be used as the crosslinking agent, and examples thereof include epoxy-based crosslinking agents, isocyanate-based crosslinking agents, melamine-based crosslinking agents, aziridine-based crosslinking agents, and metal chelate-based crosslinking agents. The use of these crosslinking agents induces an appropriate crosslinking reaction, sufficiently improves the cohesive strength, ensures good adhesion, and effectively prevents cracking of the adherend during peeling. These crosslinking agents may be used alone or in combination of two or more.

[0120] As the epoxy crosslinking agent, any compound having two or more epoxy groups in one molecule can be used without any particular limitation. Epoxy crosslinking agents having 3 to 5 epoxy groups in one molecule are preferred. Epoxy crosslinking agents can be used alone or in combination of two or more.

[0121] Specific examples of epoxy crosslinking agents include, but are not limited to, bisphenol A, epichlorohydrin-type epoxy resins, ethylene glycidyl ether, N,N,N',N'-tetraglycidyl-m-xylylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, 1,6-hexanediol glycidyl ether, polyethylene glycol diglycidyl ether, polyglycerin polyglycidyl ether, etc. Commercially available epoxy crosslinking agents include "TETRAD-C" and "TETRAD-X" manufactured by Mitsubishi Gas Chemical Company, Inc., "EPICLON CR-5L" manufactured by DIC Corporation, "DENACOL EX-512" manufactured by Nagase ChemteX Corporation, and "TEPIC-G" manufactured by Nissan Chemical Industries, Ltd.

[0122] The amount of the epoxy crosslinking agent used is not particularly limited, but is, for example, preferably 0.01 to 5 parts by mass, more preferably 0.1 to 5 parts by mass, relative to 100 parts by mass of the base polymer. In some specific embodiments, the content of the epoxy crosslinking agent relative to 100 parts by mass of the base polymer is 0.01 parts by mass, 0.5 parts by mass, 1 part by mass, 2 parts by mass, 3 parts by mass, 4 parts by mass, or 5 parts by mass.

[0123] In an embodiment containing an epoxy-based crosslinking agent, the epoxy equivalent of the epoxy-based crosslinking agent is preferably 80 to 120 g / eq.

[0124] As the isocyanate-based crosslinking agent, a polyfunctional isocyanate (which refers to a compound having two or more isocyanate groups per molecule, including those having an isocyanurate structure) can be preferably used. The isocyanate-based crosslinking agent can be used alone or in combination of two or more.

[0125] Examples of polyfunctional isocyanates include aliphatic polyisocyanates, alicyclic polyisocyanates, and aromatic polyisocyanates.

[0126] Specific examples of aliphatic polyisocyanates include 1,2-ethylene diisocyanate; butylene diisocyanates such as 1,2-butylene diisocyanate, 1,3-butylene diisocyanate, and 1,4-butylene diisocyanate; hexylene diisocyanates such as 1,2-hexylene diisocyanate, 1,3-hexylene diisocyanate, 1,4-hexylene diisocyanate, 1,5-hexylene diisocyanate, 1,6-hexylene diisocyanate, and 2,5-hexylene diisocyanate; 2-methyl-1,5-pentylene diisocyanate, 3-methyl-1,5-pentylene diisocyanate, and lysine diisocyanate.

[0127] Specific examples of alicyclic polyisocyanates include isophorone diisocyanate; cyclohexylene diisocyanates such as 1,2-cyclohexylene diisocyanate, 1,3-cyclohexylene diisocyanate, and 1,4-cyclohexylene diisocyanate; cyclopentylene diisocyanates such as 1,2-cyclopentylene diisocyanate and 1,3-cyclopentylene diisocyanate; hydrogenated xylylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated tetramethylxylylene diisocyanate, and 4,4'-dicyclohexylmethane diisocyanate.

[0128] Specific examples of aromatic polyisocyanates include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 4,4'-diphenylether diisocyanate, 2-nitrobiphenyl-4,4'-diisocyanate, 2,2'-diphenylpropane-4,4'-diisocyanate, 3,4'-diphenylmethane diisocyanate, 4,4'-diphenylether ... ,3'-dimethyldiphenylmethane-4,4'-diisocyanate, 4,4'-diphenylpropane diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, naphthalene-1,4-diisocyanate, naphthalene-1,5-diisocyanate, 3,3'-dimethoxybiphenyl-4,4'-diisocyanate, xylylene-1,4-diisocyanate, xylylene-1,3-diisocyanate, and the like.

[0129] A preferred example of the polyfunctional isocyanate is a polyfunctional isocyanate having three or more isocyanate groups per molecule. The tri- or higher functional isocyanate may be a multimer (typically a dimer or trimer) of a bifunctional or tri- or higher functional isocyanate, a derivative (for example, an addition reaction product of a polyhydric alcohol and two or more molecules of a polyfunctional isocyanate), or a polymer. Examples of the polyfunctional isocyanate include a dimer or trimer of diphenylmethane diisocyanate, an isocyanurate of hexylene diisocyanate (a trimer adduct of an isocyanurate structure), a reaction product of trimethylolpropane and tolylene diisocyanate, a reaction product of trimethylolpropane and hexylene diisocyanate, polymethylene polyphenyl isocyanate, polyether polyisocyanate, polyester polyisocyanate, and the like. Commercially available products of the polyfunctional isocyanate include "DURANATE TPA-100" manufactured by Asahi Kasei Chemical Industry Co., Ltd., "Coronate L" manufactured by Nippon Polyurethane Industry Co., Ltd., "Coronate HL" manufactured by Nippon Polyurethane Industry Co., Ltd., "Coronate HK" manufactured by Nippon Polyurethane Industry Co., Ltd., "Coronate HX" manufactured by Nippon Polyurethane Industry Co., Ltd., and "Coronate 2096" manufactured by Nippon Polyurethane Industry Co., Ltd.

[0130] In an embodiment containing an isocyanate-based crosslinking agent, the isocyanate group content (NCO content) of the isocyanate-based crosslinking agent is preferably 7 to 15%.

[0131] The amount of the isocyanate crosslinking agent used is not particularly limited, but is, for example, preferably 0.1 to 10 parts by mass, and more preferably 0.5 to 5 parts by mass, relative to 100 parts by mass of the base polymer. In some specific embodiments, the amount of the isocyanate crosslinking agent relative to 100 parts by mass of the base polymer is 0.1 parts by mass, 0.5 parts by mass, 1 part by mass, 2 parts by mass, 3 parts by mass, 4 parts by mass, 5 parts by mass, 6 parts by mass, 7 parts by mass, 8 parts by mass, 9 parts by mass, or 10 parts by mass.

[0132] Examples of melamine-based crosslinking agents include hexamethylol melamine and butylated melamine resin (for example, "SUPER BECKAMINE J-820-60N" available from DIC Corporation).

[0133] The amount of the melamine-based crosslinking agent used is not particularly limited, but is, for example, preferably 0.5 to 12 parts by mass, and more preferably 1 to 8 parts by mass, relative to 100 parts by mass of the base polymer.

[0134] Examples of aziridine crosslinking agents include trimethylolpropane tri[3-(1-aziridinyl)propionate] and trimethylolpropane tri[3-(1-(2-methyl)aziridinylpropionate)]. Commercially available aziridine crosslinking agents may be used. For example, Chemitite series (manufactured by Nippon Shokubai Co., Ltd.), such as Chemitite PZ-33 and Chemitite DZ-22E, may be used.

[0135] Examples of metal chelate crosslinking agents include aluminum chelate compounds, titanium chelate compounds, zinc chelate compounds, zirconium chelate compounds, iron chelate compounds, cobalt chelate compounds, nickel chelate compounds, tin chelate compounds, manganese chelate compounds, and chromium chelate compounds.

[0136] The amount of crosslinking agent used is preferably 0.01 to 15 parts by mass per 100 parts by mass of base polymer. By using an amount of crosslinking agent within this range, the cohesive strength of the PSA can be improved, the occurrence of adhesive residue on the adherend can be prevented, and the adhesive tends to have appropriate fluidity, good wettability to the adherend, and therefore good adhesion. In some embodiments, from the viewpoint of avoiding a decrease in tack due to an excessive increase in cohesive strength, the amount of crosslinking agent used per 100 parts by mass of base polymer is more preferably 1 part by mass or more, even more preferably 3 parts by mass or more, and more preferably 10 parts by mass or less, even more preferably 8 parts by mass or less.

[0137] A crosslinking catalyst may be used to more effectively promote the crosslinking reaction. A preferred example of the crosslinking catalyst is a tin catalyst (e.g., dioctyltin dilaurate). The amount of the crosslinking catalyst used is not particularly limited, but is preferably 0.0001 to 1 part by mass per 100 parts by mass of the base polymer.

[0138] (peeling aid) The release aid contained in the pressure-sensitive adhesive layer migrates to the surface of the pressure-sensitive adhesive layer over time, suppressing an increase in adhesive strength and improving removability. The use of a release aid can achieve both adhesion to the adherend during protection and easy removability when removing the protective sheet. The release aid disclosed herein is typically a compound having a hydrophobic group and a hydrophilic group, and preferred examples include various surfactants such as ionic surfactants and nonionic surfactants. One type of release aid can be used alone, or two or more types can be used in combination. The release aid disclosed herein may typically have a hydrophilic group-polar group. This is because, particularly when the adherend is a metal plate, excellent easy removability can be achieved by the release aid migrating between the surface of the pressure-sensitive adhesive layer and the surface of the adherend.

[0139] Ionic surfactants include anionic surfactants. Examples of anionic surfactants that can be used as peeling aids include alkyl sulfate esters such as dodecyl sulfate, fatty acids and fatty acid salts (e.g., lauric acid, myristic acid, palmitic acid, stearic acid, laurate, etc.), alkyl phosphate esters, alkylbenzenesulfonates (e.g., nonylbenzenesulfonate), naphthalenesulfonates (e.g., dodecylnaphthalenesulfonate), alkyldiphenyletherdisulfonates, polyoxyethyleneoctadecylethersulfonate, polyoxyethylene alkylethersulfates such as polyoxyethylenelaurylethersulfonate, polyoxyethylene alkylphenylethersulfates such as polyoxyethylenelaurylphenylethersulfonate, polyoxyethylenephenylethersulfates, and sulfosuccinates such as laurylsulfosuccinate.

[0140] Examples of nonionic surfactants include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene alkyl phenyl ethers such as polyoxyethylene nonylphenyl ether, sorbitan fatty acid esters such as sorbitan dilauryl monolaurate, and polyoxyethylene glycerin fatty acid esters.

[0141] The content of the release aid is preferably 0.1 to 5 parts by mass, and more preferably 0.5 to 4 parts by mass, per 100 parts by mass of the base polymer. By setting the content of the release aid to 0.1 parts by mass or more, removability tends to be improved. Furthermore, since the content of the release aid is 5 parts by mass or less, the pressure-sensitive adhesive layer has good adhesion to the adherend and tends to prevent contamination of the adherend.

[0142] In addition to the above-mentioned components, the pressure-sensitive adhesive composition of the present invention may contain, as necessary, various additives commonly used in the field of pressure-sensitive adhesives, such as a photoinitiator, a softener, an antioxidant, an antioxidant, etc. Such various additives can be conventionally known and can be used in the usual manner, provided that the effects of the present invention are not impaired.

[0143] In a preferred embodiment, the gel fraction of the pressure-sensitive adhesive layer is preferably 45% or more, more preferably 50% or more, and even more preferably 55% or more. The upper limit of the gel fraction is preferably 98% or less, more preferably 95% or less, and even more preferably 90% or less. When the gel fraction is within the above range, excellent adhesive properties can be obtained. The gel fraction can be adjusted, for example, by selecting the composition and molecular weight of the base polymer, whether or not a crosslinking agent is used, and the type and amount of the crosslinking agent.

[0144] The gel fraction can be determined, for example, as follows. Approximately 0.1 g (weight Wg1) of a pressure-sensitive adhesive sample formed from the pressure-sensitive adhesive composition was wrapped in a porous polytetrafluoroethylene film (weight Wg2) with an average pore size of 0.2 μm in a drawstring bag, and the opening was tied with string (weight Wg3). The package was immersed in 50 mL of ethyl acetate and kept at room temperature (typically 23°C) for 7 days. After that, the package was removed, the ethyl acetate adhering to the outer surface was wiped off, and the package was dried at 130°C for 2 hours, and the weight of the package (Wg4) was measured. The gel fraction was calculated by substituting each value into the following formula. Gel ratio (%) = [(Wg4 - Wg2 - Wg3) / Wg1] x 100

[0145] (Formation of adhesive layer) The PSA layer disclosed herein can be formed by a conventionally known method. For example, a method (direct method) can be used in which a PSA composition is directly applied (typically coated) to the substrate layer and then dried to form a PSA layer. Alternatively, a method (transfer method) can be used in which a PSA composition is applied to a surface (release surface) having releasability and then dried to form a PSA layer on the surface, and then the PSA layer is transferred to the substrate layer. From the viewpoint of productivity, the transfer method is preferred. The release surface can be the surface of a release liner or the back surface of a release-treated substrate layer. The PSA layer disclosed herein is typically formed continuously, but is not limited to this form. For example, the PSA layer may be formed in a regular or random pattern, such as dots or stripes.

[0146] The pressure-sensitive adhesive composition can be applied using a conventionally known coater such as a gravure roll coater, a die coater, a bar coater, etc. Alternatively, the pressure-sensitive adhesive composition may be applied by impregnation or curtain coating.

[0147] From the viewpoints of promoting the crosslinking reaction, improving production efficiency, etc., the pressure-sensitive adhesive composition is preferably dried under heating. The drying temperature can be, for example, about 40 to 150° C., and is usually preferably about 60 to 130° C. After drying the pressure-sensitive adhesive composition, aging may be performed for the purposes of adjusting component migration within the pressure-sensitive adhesive layer, promoting the crosslinking reaction, and alleviating distortion that may exist within the base film or pressure-sensitive adhesive layer.

[0148] The thickness of the pressure-sensitive adhesive layer is not particularly limited, but in consideration of the balance between adhesion to the adherend and cohesion, the thickness of the pressure-sensitive adhesive layer is preferably 1 to 40 μm, more preferably 3 to 35 μm. By setting the thickness of the pressure-sensitive adhesive layer within this range, good adhesion can be achieved.

[0149] [Base material layer] Any appropriate material can be used as the material for the substrate, and it is preferable to use a plastic film as the substrate.

[0150] The plastic film may contain any appropriate resin material. Examples of such resin materials include polyvinyl chloride, polyolefin, ethylene-vinyl acetate copolymer, polyester, polyimide, polyamide, etc. Among these, polyvinyl chloride, polyolefin, or ethylene-vinyl acetate copolymer is preferred, and polyvinyl chloride is more preferred. Polyvinyl chloride has excellent stress relaxation properties, so it can adequately mitigate the impact when the needle is thrust up, and can prevent the fragmented adherend from shifting or falling off.

[0151] The content of the resin material in the plastic film is, for example, 50 to 100 parts by mass, preferably 60 to 100 parts by mass, and more preferably 70 to 100 parts by mass, per 100 parts by mass of the plastic film.

[0152] The plastic film may contain a plasticizer. The content of the plasticizer in the plastic film is preferably 10 to 60 parts by mass, more preferably 15 to 55 parts by mass, per 100 parts by mass of the resin material (e.g., polyvinyl chloride resin) in the plastic film. By incorporating a plasticizer in the plastic film in the above content, a pressure-sensitive adhesive sheet can be obtained that has excellent followability to deformation such as stretching and good pickup properties. Furthermore, the pressure-sensitive adhesive sheet does not decrease in haze even when stored for a long period of time, and has excellent haze stability over time.

[0153] In some specific embodiments, the content of the plasticizer in the plastic film is 10 parts by mass, 20 parts by mass, 30 parts by mass, 40 parts by mass, 50 parts by mass, or 60 parts by mass per 100 parts by mass of the resin material (e.g., polyvinyl chloride resin) in the plastic film.

[0154] The plasticizer can be the same type of plasticizer as the plasticizer contained in the pressure-sensitive adhesive layer. Examples of such plasticizers include dioctyl phthalate, dioctyl terephthalate, and diisononyl phthalate. When the pressure-sensitive adhesive layer contains a plasticizer of the same type as the plasticizer contained in the substrate layer, even if the plasticizer migrates from the substrate layer to the pressure-sensitive adhesive layer, the degradation of the substrate layer and the pressure-sensitive adhesive layer over time can be suppressed.

[0155] The plastic film may contain a stabilizer. Examples of the stabilizer include phosphite esters (phosphite ester compounds) or calcium, zinc, or barium salts of stearic acid or lauric acid. Examples of phosphite ester stabilizers include alkylaryl phosphites such as monoalkyl-diaryl phosphites and dialkyl-monoaryl phosphites.

[0156] The content of the stabilizer in the plastic film is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 4.5 parts by mass, per 100 parts by mass of the resin material (e.g., polyvinyl chloride resin) in the plastic film. By including the stabilizer in the plastic film in the above content ratio, deterioration of adhesive strength can be prevented, and the adhesive sheet has excellent long-term storage stability.

[0157] The plastic film may contain a haze adjuster, which may include at least one selected from the group consisting of a filler and a colorant.

[0158] Examples of colorants include known colorants such as inorganic pigments, organic pigments, and organic dyes.

[0159] Examples of organic pigments and organic dyes include aminium-based dyes, cyanine-based dyes, merocyanine-based dyes, croconium-based dyes, squarium-based dyes, azulenium-based dyes, polymethine-based dyes, naphthoquinone-based dyes, pyrylium-based dyes, phthalocyanine-based dyes, naphthalocyanine-based dyes, naphtholactam-based dyes, azo-based dyes, condensed azo-based dyes, indigo-based dyes, perinone-based dyes, perylene-based dyes, dioxazine-based dyes, quinacridone-based dyes, isoindolinone-based dyes, quinophthalone-based dyes, pyrrole-based dyes, thioindigo-based dyes, metal complex-based dyes (metal complex dyes), dithiol metal complex-based dyes, indolephenol-based dyes, triarylmethane-based dyes, anthraquinone-based dyes, dioxazine-based dyes, naphthol-based dyes, azomethine-based dyes, benzimidazolone-based dyes, pyranthrone-based dyes, and threne-based dyes.

[0160] Examples of inorganic pigments include carbon black, cobalt-based pigments, iron-based pigments, chromium-based pigments, titanium-based pigments, vanadium-based pigments, zirconium-based pigments, molybdenum-based pigments, ruthenium-based pigments, platinum-based pigments, ITO (indium tin oxide)-based pigments, and ATO (antimony tin oxide)-based pigments.

[0161] Examples of the filler include known fillers such as organic fillers and inorganic fillers.

[0162] Examples of organic fillers include rubber particles such as styrene particles, butadiene particles, and acrylic particles, silicone resin particles, and silicone composite particles such as silicone rubber particles.

[0163] Examples of inorganic fillers include powders of silica, alumina, talc, calcium carbonate, titanium oxide, red iron oxide, silicon carbide, boron nitride, etc.; beads obtained by spheroidizing these inorganic fillers; surface modifiers for these inorganic fillers; single-crystal fibers of these inorganic fillers; and glass fibers.

[0164] The content of the haze adjuster is preferably 0.1 to 10 parts by mass, more preferably 0.2 to 9 parts by mass, relative to 100 parts by mass of the resin material (for example, polyvinyl chloride resin) in the plastic film.

[0165] The plastic film may contain any other appropriate components as long as the effects of the present invention are not impaired.

[0166] The surface of the substrate layer of the present invention may be subjected to any surface treatment in order to improve adhesion to adjacent layers, retention, etc. Examples of the surface treatment include chemical or physical treatments such as chromic acid treatment, ozone exposure, flame exposure, high-voltage shock exposure, and ionizing radiation treatment, and coating treatment.

[0167] The thickness of the substrate layer of the present invention can be set to any appropriate thickness depending on the desired strength or flexibility, the intended use, etc. The thickness of the substrate layer is preferably 5 to 300 μm, more preferably 30 to 200 μm, and even more preferably 50 to 150 μm.

[0168] In some preferred embodiments, the arithmetic mean surface roughness Ra of the substrate layer at 23° C. is 1 to 6 μm, and preferably 3 to 5 μm.

[0169] In some preferred embodiments, the surface of the substrate layer has a surface roughness at 23°C of a maximum height (Rz) of 6 to 12 μm, or 6 to 9 μm.

[0170] In some preferred embodiments, the arithmetic mean surface roughness Ra of the substrate layer at 50° C. is 1 to 4 μm, and preferably 1 to 3 μm.

[0171] In some preferred embodiments, the surface of the substrate layer has a surface roughness at 50°C of a maximum height (Rz) of 6 to 10 μm, or 6 to 9 μm.

[0172] By setting the surface roughness Ra or Rz of the substrate layer at 23°C or 50°C within the above range, the haze of the pressure-sensitive adhesive sheet does not decrease even when stored for a long period of time, and the sheet has excellent haze stability over time.

[0173] [Release film] The release film may have a single-layer structure or a multi-layer structure and may be made of a material commonly used in the industry, such as release paper. The release film may be a sheet including a base film and a release agent layer formed on one side thereof.

[0174] The substrate film of the release film can be made of any suitable material and can be selected from, for example, polyether ether ketone film, polyetherimide film, polyaryl compound film, polyethylene naphthalate, polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, polyvinyl chloride copolymer film, polyethylene terephthalate film, polybutylene terephthalate film, polyurethane film, ethylene-vinyl acetate copolymer film, ionic bonding resin film, ethylene-(meth)acrylic acid copolymer film, ethylene-(meth)acrylic acid ester copolymer film, polystyrene film, and polycarbonate film.

[0175] The release agent layer can be formed by performing a surface treatment on the substrate film using various release treatment agents, such as a silicone-based release treatment agent, a long-chain alkyl-based release treatment agent, a fluorine-based release treatment agent, and a molybdenum sulfide-based release treatment agent.

[0176] In the present invention, the side of the release film away from the surface to be bonded to the pressure-sensitive adhesive layer is the matte surface, which can be obtained by making indentations with a polishing roller or by sandblasting. The thickness of the release film is not particularly limited, but is preferably 20 to 70 μm.

[0177] [Backcoat layer] As shown in FIG. 2, the pressure-sensitive adhesive sheet of the present invention may further include a backcoat layer 40 provided on the side of the substrate layer 10 opposite to the pressure-sensitive adhesive layer 20 .

[0178] The backcoat layer-forming material is not particularly limited, and can be one or more of polyurethane resins, epoxy resins, polyester resins, acrylic resins, polyamide resins, melamine resins, olefin resins, polystyrene resins, phenol resins, isocyanurate resins, polyvinyl acetate resins, etc. When an acrylic or other pressure-sensitive adhesive layer is provided on the resin film substrate layer, a polyurethane-, epoxy-, polyester-, or acrylic-based backcoat layer is preferred.

[0179] In some preferred embodiments, the backcoat layer preferably contains at least one selected from the group consisting of thermosetting acrylic, polyurethane, and epoxy resins.

[0180] In some preferred embodiments, the backcoat layer preferably contains an antistatic agent. This improves the antistatic properties of the PSA sheet and sufficiently suppresses peel electrification voltage. The backcoat layer may have a single-layer structure or a multi-layer structure of two or more layers. In embodiments in which a multi-layer backcoat layer is used, it is preferred that at least one of the layers (typically at least one layer including the layer in contact with the substrate layer) contains an antistatic agent.

[0181] Examples of the antistatic agent that can be used include those described above for the pressure-sensitive adhesive layer. Examples include conductive polymers such as polythiophene, polyaniline, polypyrrole, polyethyleneimine, and allylamine-based polymers; conductive inorganic fine particles such as conductive metal oxides, carbon nanotubes, graphene, fullerene, acetylene black, ketjen black, natural graphite, artificial graphite, and titanium black; and metal fine particles or fibers. These can be used alone or in combination of two or more.

[0182] In the embodiment where a backcoat layer is disposed, examples of conductive polymers that can be contained in the backcoat layer include polythiophene and polyaniline. Polythiophene has a polystyrene-equivalent Mw of 40×10 4Preferably, it is 30 x 10 4 The following is more preferred: Polyaniline having an Mw of 50×10 4 Preferably, it is 30 x 10 4 The Mw of these conductive polymers is usually 0.1 × 10 or less. 4 It is preferable that the value is 0.5×10 or more. 4 More preferably, the above is the case. In this specification, polythiophene refers to a polymer of unsubstituted or substituted thiophene. One suitable example of a substituted thiophene polymer in the technology disclosed herein is poly(3,4-ethylenedioxythiophene).

[0183] In some preferred embodiments, the backcoat layer may contain polystyrene sulfonate (PSS) as a dopant (e.g., a dopant for a thiophene-based polymer). In some embodiments, the backcoat layer is formed using a composition for forming a backcoat layer, which includes an aqueous polythiophene solution containing PSS (which may be in a form in which PSS is added to polythiophene as a dopant). Such an aqueous solution may contain polythiophene:PSS in a weight ratio of 1:1 to 1:10. The total content of polythiophene and PSS in the aqueous solution may be, for example, about 1 to 5 wt %.

[0184] From the viewpoint of improving antistatic properties, the amount of the conductive polymer used can be about 10 parts by mass or more, usually 25 parts by mass or more, and preferably 40 parts by mass or more, per 100 parts by mass of the resin contained in the backcoat layer. Considering the compatibility of the conductive polymer in the backcoat layer, the amount of the conductive polymer used is appropriately 200 parts by mass or less (e.g., 150 parts by mass or less) per 100 parts by mass of the resin, and preferably 120 parts by mass or less (e.g., 100 parts by mass or less). The amount of the conductive polymer used can also be 80 parts by mass or less (e.g., 60 parts by mass or less) per 100 parts by mass of the resin.

[0185] The total amount of antistatic agent in the backcoat layer (total amount of all antistatic agents including conductive polymers, conductive inorganic fine particles, etc.) can be about 5% by weight (e.g., about 10% by weight or more), and is suitably about 30% by weight or more, and may be, for example, more than 50% by weight. The upper limit of the total amount of antistatic agent in the backcoat layer is not particularly limited, and is suitably about 90% by weight or less (e.g., 80% by weight or less), and may be about 40% by weight or less (e.g., about 30% by weight or less) taking into consideration adhesion to the base layer, etc.

[0186] The backcoat layer may contain a binder in addition to the conductive agent described above. The binder that can be contained in the backcoat layer can be any of the above-described backcoat layer-forming materials without any particular limitations. Among these, thermosetting polyurethane and / or epoxy resins are preferred. The binder content of the entire backcoat layer can be, for example, about 30% by weight or more, and is preferably about 40% by weight or more (e.g., about 50% by weight or more). Furthermore, taking into consideration antistatic properties, the binder content is preferably less than 90% by weight (less than 80% by weight).

[0187] In some embodiments, the backcoat layer contains a crosslinking agent. The crosslinking agent can be appropriately selected from melamine-based, isocyanate-based, epoxy-based, and other crosslinking agents commonly used for crosslinking resins. This allows for favorable anchoring to the substrate layer.

[0188] The backcoat layer may contain additives such as antioxidants, colorants, flowability modifiers, film-forming aids, surfactants, and corrosion inhibitors, as required.

[0189] In some preferred embodiments, the backcoat layer is preferably formed using a backing treatment agent. The backing treatment agent that can be used to form the backcoat layer is not particularly limited, and known or commonly used treatment agents such as silicone-based backing treatment agents, fluorine-based backing treatment agents, and long-chain alkyl group-based backing treatment agents can be used depending on the purpose and application. The backing treatment agents can be used alone or in combination of two or more.

[0190] The backcoat layer can be suitably formed by applying a liquid composition (a coating material for forming the backcoat layer) in which the resin components and optional additives are dispersed or dissolved in an appropriate solvent to the substrate layer using a known or conventional coater such as a gravure roll coater or a reverse roll coater, followed by drying and curing treatments as necessary. From the viewpoint of forming a thin and uniform layer, the NV (non-volatile content) of the coating material can be, for example, 5 wt % or less (typically 0.05 to 5 wt %). The solvent that can be used to form the coating material can be any of organic solvents, water, and mixed solvents thereof, with water or mixed solvents containing water as the main component (e.g., a mixed solvent of water and ethanol) being preferred.

[0191] The thickness of the backcoat layer in the technology disclosed herein is not particularly limited, and is usually 0.01 μm or more. From the viewpoint of optimally exhibiting the function of the backcoat layer, it is appropriate to set it to 0.05 μm or more, and it may be preferably 0.1 μm or more (for example, 0.2 μm or more). The upper limit of the thickness of the backcoat layer can be 50 μm or less (for example, 10 μm or less), and from the viewpoint of transparency, etc., it is appropriate to set it to 3 μm or less, and preferably 1 μm or less (for example, 0.6 μm or less).

[0192] In some preferred embodiments, the backcoat layer has an arithmetic mean surface roughness Ra at 23° C. of 0.1 to 5.0 μm, preferably 0.5 to 3.0 μm.

[0193] In some preferred embodiments, the surface of the backcoat layer has a surface roughness at 23°C of 1 to 10 μm, or 1.5 to 9.0 μm, in terms of maximum height (Rz).

[0194] In some preferred embodiments, the backcoat layer has an arithmetic mean surface roughness Ra at 50° C. of 0.1 to 4.0 μm, preferably 0.5 to 3.0 μm.

[0195] In some preferred embodiments, the surface of the backcoat layer has a surface roughness at 50°C of 2.0 to 8.0 μm, or 2.0 to 7.0 μm in maximum height (Rz).

[0196] By setting the surface roughness Ra or Rz of the backcoat layer at 23° C. or 50° C. within the above range, the adhesive sheet does not lose haze even when stored for a long period of time, and has excellent haze stability over time.

[0197] [Undercoat layer] As shown in FIG. 3, the pressure-sensitive adhesive sheet of the present invention may further include an undercoat layer 50 provided between the substrate layer 10 and the pressure-sensitive adhesive layer 20 on the side of the substrate layer 10 opposite the backcoat layer 40.

[0198] The undercoat layer-forming material is not particularly limited, and can be one or more of polyurethane-based resins, epoxy-based resins, polyester-based resins, acrylic-based resins, polyamide-based resins, melamine-based resins, olefin-based resins, polystyrene-based resins, phenol-based resins, isocyanurate-based resins, polyvinyl acetate-based resins, etc. When an acrylic or other pressure-sensitive adhesive layer is provided on the resin film substrate layer, a polyurethane-based, epoxy-based, polyester-based, or acrylic-based undercoat layer is preferred.

[0199] In some preferred embodiments, the undercoat layer preferably contains at least one selected from the group consisting of thermosetting acrylic, polyurethane, and epoxy resins.

[0200] In some preferred embodiments, the undercoat layer preferably further contains an antistatic agent. This improves the antistatic properties of the PSA sheet and sufficiently suppresses peel electrification voltage. The undercoat layer may have a single-layer structure or a multi-layer structure of two or more layers. In embodiments in which a multi-layer undercoat layer is used, it is preferred that at least one of the layers (typically at least one layer including a layer in contact with the undercoat layer) be a backcoat layer containing an antistatic agent.

[0201] As the antistatic agent, for example, the antistatic agents described above for the pressure-sensitive adhesive layer can be used. For example, conductive polymers, conductive inorganic fine particles, metal fine particles or fibers, etc. can be used. These can be used alone or in combination of two or more.

[0202] The undercoat layer may contain the same conductive polymer, dopant, binder, etc. as the backcoat layer, and the content thereof is the same as that in the backcoat layer.

[0203] The undercoat layer may further contain any appropriate additives, such as ultraviolet absorbers, antioxidants, light stabilizers such as hindered amine light stabilizers, surface lubricants, leveling agents, plasticizers, low-molecular-weight polymers, preservatives, polymerization inhibitors, silane coupling agents, inorganic and organic fillers (e.g., calcium oxide, magnesium oxide, silicon oxide, zinc oxide, titanium oxide, etc.), metal powders, colorants, pigments, heat stabilizers, anti-sediment agents, lubricants, and anti-blocking agents.

[0204] In some preferred embodiments, the undercoat layer is preferably formed using a primer. The undercoat treatment agent that can be used to form the undercoat layer is not particularly limited, and known or commonly used treatment agents such as silicone-based back-treatment agents, fluorine-based back-treatment agents, and long-chain alkyl group-based back-treatment agents can be used depending on the purpose and application. The back-treatment agents can be used alone or in combination of two or more.

[0205] The thickness of the undercoat layer is not particularly limited, but is preferably 0.05 to 2 μm, and more preferably 0.1 to 1.5 μm. By setting the thickness of the undercoat layer within the above range, the effects of the present invention can be more suitably exhibited.

[0206] (Method of manufacturing pressure-sensitive adhesive sheet) The pressure-sensitive adhesive sheet of the present invention can be produced by any suitable method. For example, a method of coating a substrate layer with a pressure-sensitive adhesive composition, or a method of coating a substrate with a pressure-sensitive adhesive composition and transferring the resulting coating layer to the substrate layer, etc. Then, a release film is placed on the pressure-sensitive adhesive layer so that the matte surface of the release film is away from the surface to be bonded to the pressure-sensitive adhesive layer.

[0207] Any appropriate coating method can be used as the method for applying the pressure-sensitive adhesive composition. For example, each layer can be formed by coating and then drying. Examples of the coating method include coating methods using a multi-coater, die coater, gravure coater, applicator, bar coater coating, air knife coating, reverse roll coating, lip coating, dip coating, offset printing, flexographic printing, screen printing, etc. Examples of the drying method include natural drying and heat drying. When heat drying is performed, the heating temperature can be set to any appropriate temperature depending on the properties of the substance to be dried.

[0208] (Application) The pressure-sensitive adhesive sheets disclosed herein are attached to, for example, various members and devices, and are used for applications such as protection and packaging and fixing of semiconductor devices. Example

[0209] Hereinafter, the embodiments of the present invention will be described in detail with reference to examples. However, those skilled in the art will understand that the following examples are merely illustrative of the present invention and are not intended to limit the scope of the present invention. In the examples, unless specific conditions are specified, the procedures are carried out under standard conditions or in accordance with the manufacturer's recommendations. Unless the manufacturer is specified, all reagents or instruments used are commercially available and commonly used.

[0210] (Production of acrylic polymer A1) A reaction vessel equipped with a stirrer, thermometer, nitrogen gas inlet tube, and reflux condenser was charged with 70 parts of n-butyl acrylate (BA) (manufactured by Zhejiang Satellite), 25 parts of N-vinylpyrrolidone (NVP), 5 parts of 2-hydroxyethyl acrylate (HEA), and 200-300 parts of toluene as a polymerization solvent, and the mixture was stirred at 65°C under a nitrogen atmosphere for 1.5 hours. After that, 0.1 parts of 2,2'-azobisisobutyronitrile (AIBN) was charged as a thermal polymerization initiator, and the reaction was carried out at 65°C for 3-4 hours, yielding a solution of acrylic polymer A1.

[0211] (Production Example 1): Production of base layer 1 A substrate film was produced by rolling a mixture of 100 parts by weight of polyvinyl chloride, 20 parts by weight of DOTP as a plasticizer, 1 part by weight of zinc stearate (OW-5000LTS) as a stabilizer, and 5 parts by weight of talc as a haze adjuster. The thickness of the substrate film was 75 μm. The arithmetic mean surface roughness Ra of the substrate film immediately after production at 23°C was 3.5 μm, and the surface of the substrate film immediately after production had a surface roughness with a maximum height (Rz) of 10 μm at 23°C.

[0212] (Production Example 2): Production of base layer 2 A substrate film was produced by rolling a mixture of 100 parts by weight of polyvinyl chloride, 30 parts by weight of DOTP as a plasticizer, 1 part by weight of zinc stearate (OW-5000LTS) as a stabilizer, and 5 parts by weight of talc as a haze adjuster. The thickness of the substrate film was 75 μm. The arithmetic mean surface roughness Ra of the substrate film immediately after production at 23°C was 3.5 μm, and the surface of the substrate film immediately after production had a surface roughness with a maximum height (Rz) of 10 μm at 23°C.

[0213] (Production Example 3): Production of base layer 3 A substrate film was produced by rolling a mixture of 100 parts by weight of polyvinyl chloride, 70 parts by weight of DOTP as a plasticizer, 1 part by weight of zinc stearate (OW-5000LTS) as a stabilizer, and 5 parts by weight of talc as a haze adjuster. The thickness of the substrate film was 75 μm. The arithmetic mean surface roughness Ra of the substrate film immediately after production at 23°C was 3.5 μm, and the surface of the substrate film immediately after production had a surface roughness with a maximum height (Rz) of 10 μm at 23°C.

[0214] <Preparation of adhesive sheet> Example 1 To the solution of the acrylic polymer A1, 1 part of LiTFsl (organic lithium salt) as an antistatic agent, 10 parts of an ethylene-vinyl acetate copolymer as a functional resin, 3 parts of an isocyanate-based crosslinking agent (product number: Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.), 0.1 parts of an epoxy-based crosslinking agent (product number: TETRAD C, manufactured by Mitsubishi Gas Chemical Company, Inc.), and 30 parts of DOTP as a plasticizer were added per 100 parts of the acrylic polymer A1 contained in the solution, and the mixture was mixed uniformly to prepare a pressure-sensitive adhesive composition C1. The adhesive composition C1 was applied to one side of the base layer 1 produced in the above Production Example 1, and after coating, an adhesive layer having a thickness of 10 μm was dried by heating at 130° C. for 2 minutes. Antistatic backcoat liquid E1 (polythiophene dispersion, manufactured by OYI Organic Photoelectric Co., Ltd., product number: Polyelec OE-001) was applied to the other side of the substrate layer 1, and then dried in an air flotation oven at 80°C for 1 minute to form a backcoat layer with a thickness of 1 μm. A PET release film (manufactured by Yaoyang Technology Co., Ltd.) was placed on the adhesive layer so that the matte side of the release film was away from the surface to be bonded to the adhesive layer. The matte side had an arithmetic mean surface roughness Ra of 0.3 μm and a maximum height (Rz) of 1.5 μm. A pressure-sensitive adhesive sheet was thus obtained. The evaluation results are shown in Table 1.

[0215] Examples 2 to 5 A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1, except that the type of substrate layer, the amount of functional resin used, the amount of plasticizer used, and the type of release film were changed as shown in Table 1. The evaluation results are shown in Table 1.

[0216] Comparative Examples 1 to 3 A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1, except that the type of substrate layer, the amount of plasticizer used, and the type of release film were changed as shown in Table 2. The evaluation results are shown in Table 2.

[0217] In the table below, Li salt: LiTFsl, CAS number: 90076-65-6, manufactured by Shanghai Luyi Technology Isocyanate crosslinking agent: Product code: Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd. Epoxy crosslinking agent: Product number: TETRAD C, manufactured by Mitsubishi Gas Chemical Company, Inc. Ethylene-vinyl acetate copolymer: (ethylene-vinyl acetate copolymer with a vinyl acetate content of 15% or more) The "1 μm" in polythiophene (dry film thickness, μm) is the dry film thickness and was obtained as follows. The formulated antistatic backcoat solution was uniformly applied to the surface of the substrate using a microgravure coater, then heated and dried, and wound up. The speed V was set to 10-100 m / min, the mesh number to 100-300 mesh, and the heating and drying temperature to 60-120°C.

[0218] Table 1 [Table 1-1] [Table 1-2] [Table 1-3]

[0219] Table 2 [Table 2-1] [Table 2-2]

[0220] <Evaluation test> (1) Ra and Rz of the matte surface of the release film In accordance with JIS B 0601, the arithmetic surface roughness Ra and maximum height Rz of the matte surface of the release film were measured using an optical surface roughness measuring instrument (manufactured by Veeco Metrology Group, trade name "Wyko NT9100").

[0221] (2) Ra and Rz of the backcoat layer surface of the adhesive sheet The arithmetic surface roughness Ra and maximum height Rz of the surface of the backcoat layer of the pressure-sensitive adhesive sheet were measured in accordance with JIS B 0601 using an optical surface roughness measuring instrument (manufactured by Veeco Metrology Group, trade name "Wyko NT9100").

[0222] (3) Peeling force A The pressure-sensitive adhesive sheets prepared in each Example and Comparative Example were cut to a width of 20 mm and a length of 150 mm to prepare test specimens. Toluene-washed SUS plates (SUS430BA plates) were used as adherends. Under standard conditions of 23°C and 50% RH, the release liner covering the adhesive surface of each test specimen was peeled off, and the exposed adhesive surface was pressed against the adherend by rolling a 2 kg roller back and forth once. The test specimens thus pressed against the adherend were then left for 30 minutes under the standard conditions. After that, they were subjected to peeling at a tensile speed of 300 mm / min and a peel angle of 180° using a universal testing machine (Shimadzu Corporation, product name "AG-X plus Electronic Universal Testing Machine") in accordance with JIS Z 0237, and the force required for this peeling (N / 20 mm) was measured.

[0223] (4) Peeling force B The pressure-sensitive adhesive sheets prepared in each Example and Comparative Example were cut to a width of 20 mm and a length of 150 mm to prepare test specimens. Toluene-washed SUS plates (SUS430BA plates) were used as adherends. Under a standard environment of 23°C and 50% RH, the release liner covering the adhesive surface of each test specimen was peeled off, and the exposed adhesive surface was pressed against the adherend by rolling a 2 kg roller back and forth once. The test specimens were then left at 50°C for 24 hours. The test specimens thus pressed against the adherends were then left under the standard environment for 30 minutes. After that, they were subjected to peeling at a tensile speed of 300 mm / min and a peel angle of 180° using a universal testing machine (Shimadzu Corporation, product name "AG-X plus Electronic Universal Testing Machine") in accordance with JIS Z 0237, and the peel force (N / 20 mm) required for this measurement was measured.

[0224] (5) Peeling force C The steps of the above evaluation test (3) were repeated except that the peeling was performed at a peel angle of 180° and a pulling speed of 10 m / min, and the force (N / 20 mm) required for this peeling was measured.

[0225] (6) Peeling force D The steps of the above evaluation test (3) were repeated except that the peeling was performed at a peel angle of 20° and a pulling speed of 10 m / min, and the force (N / 20 mm) required for this peeling was measured.

[0226] (7) Peeling force E The steps of the above evaluation test (4) were repeated except that the peeling was performed at a peel angle of 180° and a pulling speed of 10 m / min, and the force (N / 20 mm) required for this peeling was measured.

[0227] (8) Peeling force F The steps of the above evaluation test (4) were repeated except that the peeling was performed at a peel angle of 20° and a pulling speed of 10 m / min, and the force (N / 20 mm) required for this peeling was measured.

[0228] (9) 50% elastic modulus (MD, TD) The pressure-sensitive adhesive sheets obtained in each Example and Comparative Example were cut to a size of 20 mm wide and 150 mm long to prepare test specimens. The test specimens were then adjusted to a length of 100 mm and a width of 20 mm, and stretched to 150 mm in the longitudinal or transverse direction at a tensile speed of 300 mm / min using a universal testing machine (manufactured by Shimadzu Corporation, product name "AG-X plus Electronic Universal Testing Machine") under a measurement environment of 23°C temperature and 50% relative humidity. The load (MPa) at this time was taken as the 50% modulus of elasticity in the MD or TD direction.

[0229] (10) Tensile strength (MD, TD) The pressure-sensitive adhesive sheets obtained in each Example and Comparative Example were cut to a size of 20 mm wide and 150 mm long to prepare test specimens. Then, the test specimens were cut to a length of 50 mm, and tensile tests were carried out at a tensile speed of 300 mm / min using a universal testing machine (manufactured by Shimadzu Corporation, product name "AG-X plus Electronic Universal Testing Machine") under a measurement environment of a temperature of 23°C and a relative humidity of 50%. The specimens were stretched in the longitudinal or transverse direction until they broke, and the load (MPa) at this time was recorded as the tensile strength in the MD or TD direction.

[0230] (11) Breaking elongation (MD, TD) The pressure-sensitive adhesive sheets obtained in each Example and Comparative Example were cut to a size of 20 mm wide and 150 mm long to prepare test pieces. Then, the test pieces were adjusted to a length of 50 mm, and a tensile test was carried out at a tensile speed of 300 mm / min using a universal material testing machine (manufactured by Shimadzu Corporation, product name "AG-X plus Electronic Universal Testing Machine") under a measurement environment of a temperature of 23°C and a relative humidity of 50%, and the test pieces were stretched in the longitudinal direction or width direction until they broke, thereby measuring the breaking elongation in the MD or TD direction.

[0231] (12) Surface resistivity (before expansion, after expansion) In each example and comparative example, the resistivity of the front and back surfaces of the adhesive layer (the back surface of the adhesive sheet, the backcoat surface) was measured using a resistivity meter (ACL Staticide, "ACL MODEL 800") under conditions of a temperature of 23°C, an atmosphere of 50% RH, an applied voltage of 100 V, and an application time of 30 seconds. After stretching and expanding by 1.2 times in the 360° direction, in each of the Examples and Comparative Examples, the resistivity of the front and back surfaces of the pressure-sensitive adhesive layer (the back surface of the pressure-sensitive adhesive sheet, the backcoat surface) was measured using a resistivity meter ("HIRESTA-UP MCP-HT450" manufactured by Mitsubishi Chemical Analytech Co., Ltd.) under conditions of a temperature of 23°C, an atmosphere of 50% RH, an applied voltage of 100 V, and an application time of 30 seconds. The adhesive surface resistivity represents the resistivity of the surface of the adhesive layer. In measuring the adhesive surface resistivity, a probe is brought into contact with the surface of the adhesive layer. The back surface resistivity represents the surface resistivity of the back surface of the substrate layer. In measuring the back surface resistivity, the probe is brought into contact with the back surface of the substrate layer, i.e., the surface of the substrate layer opposite the adhesive layer.

[0232] (13) Rate of change in the logarithm of adhesive surface resistivity The rate of change in the logarithmic value of the surface resistivity of the adhesive surface of the adhesive sheet is calculated by the following formula. Change in logarithmic value of adhesive surface resistivity (%) = [(X2-X1) / X1] × 100% (1) (wherein X2 represents the logarithm of the surface resistivity after the PSA sheet has been stretched 1 to 1.2 times in the 360° direction (i.e., the adhesive surface resistivity shown in the table above, after expanding 1.2 times), X1 represents the logarithm of the surface resistivity of the pressure-sensitive adhesive sheet before stretching (i.e., the surface resistivity of the adhesive surface shown in the table above, before expanding).

[0233] (14) Rate of change of the logarithm of the back surface resistivity The rate of change in the logarithmic value of the back surface resistivity of the pressure-sensitive adhesive sheet is calculated by the following formula. Change in logarithmic value of rear surface resistivity (%) = [(X4-X3) / X3] × 100% (1) (wherein X4 represents the logarithm of the surface resistivity after the PSA sheet has been stretched 1 to 1.2 times in the 360° direction (i.e., the back surface resistivity shown in the table above, after being expanded 1.2 times), X3 represents the logarithm of the surface resistivity of the PSA sheet before stretching (i.e., the back surface resistivity shown in the table above, before expanding).

[0234] (15) Peeling voltage An evaluation sample was prepared by laminating the silicone-treated surface of a charge-neutralized release film (silicone-treated PET film, manufactured by Toray Industries, Inc., product name "Cerapeel," thickness: 38 μm) to the adhesive surface of an adhesive sheet (70 mm wide x 130 mm long). The longitudinal end of the release film was allowed to protrude 30 mm beyond the adhesive sheet. The adhesive sheet and release film were then laminated together using a hand roller under conditions conforming to JIS Z 0237 (2000) (temperature: 23°C, humidity: 50% RH). The evaluation sample was left for one day in an environment of 23°C and 50% RH, and then the protruding portion of the release film was grasped and the release film was peeled off in the longitudinal direction at a peel angle of 150° and a peel speed of 12 mm / min. The voltage on the surface of the adhesive layer generated during peeling was measured at a position 100 mm away from the point where the release film and the adhesive sheet separated in a direction perpendicular to the adhesive surface, and the maximum value was taken as the peel voltage. The measuring device used was a potential meter (manufactured by Kasuga Electric Industrial Co., Ltd., product name "KSD-0103"). The measurement environment was 23°C and 50% RH.

[0235] (16) 50℃ heat shrinkage (MD, TD) The pressure-sensitive adhesive sheets of each Example and Comparative Example were heated at 50°C for 10 minutes, and then cooled to room temperature (23°C), after which the shrinkage rates in the MD and TD directions were measured. Specifically, the pressure-sensitive adhesive sheets obtained in each Example and Comparative Example were cut into a roughly square shape in plan view, measuring 100 mm in the MD direction and 100 mm in the TD direction, and a cross-pattern notch was made at each of the four corners to prepare a measurement sample. Using a CNC coordinate measuring machine (Mitutoyo Corporation, "LEGEX774"), the distance (length) between the notches (center of the cross pattern) in the MD direction and the distance (length) between the notches in the TD direction of the measurement sample before heating (25 ° C) were measured. This gave the lengths before heating in the MD and TD directions. Next, the test piece was placed on a horizontal table in an oven and heated at 50°C for 10 minutes, after which it was naturally cooled at room temperature (23°C) for 10 minutes. The distance between the notches in the MD and TD directions was then measured using a CNC coordinate measuring machine. This gave the post-heating lengths in the MD and TD directions. The shrinkage in the MD and TD directions was then calculated using the following formula: Shrinkage rate (%) = [length before heating (mm) - length after heating (mm)] / length before heating (mm) x 100

[0236] (17) Dirt on the adhesive surface The pressure-sensitive adhesive sheets prepared in each Example and Comparative Example were cut to a width of 400 mm and a length of 150 mm to prepare test specimens. The pressure-sensitive adhesive sheet sample was then rolled back and forth with a 2 kg roller, with the exposed adhesive surface being pressed against the shiny surface of a silicon wafer. The test specimens thus pressed against the adherend were left for 3 days under the standard conditions of 23°C and 50% RH, and then peeled off at 300 mm / min. The presence or absence of oily stains on the silicon wafer surface was then visually observed. Those with no visible oily stains were evaluated as "○", and those with slight visible oily stains were evaluated as "△".

[0237] (18) Glue residue The pressure-sensitive adhesive sheets prepared in each Example and Comparative Example were cut to a width of 400 mm and a length of 150 mm to prepare test specimens. The pressure-sensitive adhesive sheet sample was rolled back and forth with a 2 kg roller, and the exposed adhesive surface was then pressed onto a 125 μm PET film with a surface dyne value of over 38 dyn (mN / m). The test specimens thus pressed onto the adherend were placed under a standard environment of 23 °C and 50% RH for 3 days, and then peeled off at 1000 mm / min. The presence or absence of adhesive residue on the surface of the 125 μm PET film was visually observed. Those with no visible adhesive residue were evaluated as "○", and those with slight adhesive residue were evaluated as "△".

[0238] (19) Expandability (MD / TD) The PSA sheets produced in each Example and Comparative Example were cut to a width of 200 mm and a length of 200 mm to prepare test pieces, and the release film was peeled off. Measurements were performed using an expanding machine WE-4U (Mizo Precision Machinery) (measurement conditions: 1.2 times stretching and expansion in a 360° direction, rising speed: 5 mm / s, rising height: 56 mm, upper heating platen: 50°C, lower heating platen: 170°C). Test pieces that showed no external tearing after expansion were rated "Good."

[0239] (20) Regularity of chip arrangement after expansion The pressure-sensitive adhesive sheets prepared in each Example and Comparative Example were cut to a width of 200 mm and a length of 200 mm to prepare test pieces, and the release film was removed. The chips were arranged on the adhesive surface of the pressure-sensitive adhesive sheet at the same pitch lengthwise and widthwise, and measured using an expanding machine WE-4U (Mizo Precision Machinery and Electrical) (measurement conditions: 1.2x stretching and expansion in the 360° direction, rising speed: 5 mm / s, rising height: 56 mm, upper heating platen: 50°C, lower heating platen: 170°C). The longitudinal and lateral pitch change rates of the chip were measured, and those with an MD / TD change rate ratio in the range of 0.8 to 1.2 were marked as "○", and those with an MD / TD change rate ratio of 0.7 or more but less than 0.8 or more than 1.2 but less than 1.3 were marked as "△".

[0240] (21) Transfer rate The chips were arranged on the adhesive surface of the first adhesive sheet at the same pitch both vertically and horizontally. The adhesive surface of the first adhesive sheet with the chips was then placed facing up, and the adhesive surface of the second adhesive sheet without the chips was placed facing down. The sheets were then bonded together using a 5 kg roller and pressed back and forth three times under a standard environment of 23°C and 50% RH. The bonded composite adhesive sheet was then inverted, and the first adhesive sheet was peeled off at a 90° angle from above at a speed of 600 mm / min. A chip transfer rate of 85% or more was considered to be acceptable.

[0241] (22) Chip sinking After laminating a PET#125 protective film to a 200mm x 200mm adhesive sheet with chips, a 3kg weight was placed on the chips, and after 3 days, the chips were observed under a microscope. Those in which there was no obvious sinking of the chips into the adhesive or the sinking depth was less than 1 / 3 of the thickness of the chip were rated as "○", and those in which there was slight sinking of the chips into the adhesive or the sinking depth was 1 / 3 or more of the thickness of the chip were rated as "△".

[0242] (23) Light transmittance / haze The pressure-sensitive adhesive sheets prepared in each Example and Comparative Example were cut into 100 mm wide x 100 mm long test pieces. Three of these were selected and stacked, and left for 24 hours under a standard environment of 23°C and 50% RH. The middle sheet was then taken, the release film was removed, and the initial haze and initial light transmittance were measured. The pressure-sensitive adhesive sheets prepared in each Example and Comparative Example were cut into a 100 mm wide x 100 mm long test piece. Three of these were selected and stacked, and left at 50°C for 72 hours. The middle sheet was then taken and stored in a standard environment of 23°C and 50% RH. The release film was removed immediately after removal, and the haze and light transmittance were measured. To measure haze and light transmittance, the adhesive side of the test piece was attached to the detection hole of the instrument with its back to the light source, and the TEST button was pressed on the WGT-S light transmittance / haze meter (manufactured by Shanghai Seiko Co., Ltd.) under the standard environment of 23°C and 50% RH, and the data was read after 1 minute.

[0243] (24) Haze change rate Haze change rate = (haze before aging - haze after aging) / haze before aging × 100% (In the formula, the haze before aging is the initial haze measured as above, and the haze after aging is the haze measured as above immediately after removal from the container.) Haze stability evaluation: A haze change rate of more than 10% was rated "x", a haze change rate of 5 to 10% was rated "△", and a haze change rate of less than 5% was rated "◯".

[0244] (25) Overall Judgment When all the above measured values ​​were excellent and all the evaluation results were "○", it was rated as "○", when the above measured values ​​were good or there was at least one "△" in the evaluation results, it was rated as "△", and when the above measured values ​​were poor or there was at least one "×" in the evaluation results, it was rated as "×". As shown in Tables 1 and 2 above, Examples 1 to 5 all had excellent haze stability over time, expandability (or spreadability), adhesiveness, removability, antistatic properties, laminated storage stability, temperature resistance, transparency, and transferability, and were easily peeled off without leaving any adhesive residue after use. In contrast, Comparative Examples 1 to 3 did not all have excellent haze stability over time, expandability (or spreadability), adhesiveness, removability, antistatic properties, laminated storage stability, temperature resistance, transparency, and transferability.

[0245] Although the configuration of the present invention has been described using specific examples, those skilled in the art will understand that the present invention is not limited to these.

[0246] Although the embodiments of the present invention have been described above, the above description is merely illustrative and is not exhaustive, nor is it limited to the disclosed embodiments. Various modifications and alterations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terms chosen in this specification are intended to appropriately interpret the principles, practical applications, or improvements to commercially available technologies of the embodiments, or to allow other skilled artisans to understand the disclosed embodiments. [Explanation of symbols]

[0247] 1, 2, 3 adhesive sheet 10 Base material layer 20 adhesive layer 30 Release film 40 Backcoat Layer 50 Undercoat layer 100 Roll of adhesive sheet 200 laminate 201 First adhesive sheet 202 Second adhesive sheet

Claims

1. A pressure-sensitive adhesive sheet comprising a base layer, a pressure-sensitive adhesive layer provided on one side of the base layer, and a release film provided on the pressure-sensitive adhesive layer on the opposite side to the base layer, wherein the release film has a matte surface on the side away from the surface to be attached to the pressure-sensitive adhesive layer, and the matte surface has an arithmetic mean surface roughness Ra of 0.25 μm or more, or the surface of the matte surface has a surface roughness with a maximum height (Rz) of 1.5 μm or more; The pressure-sensitive adhesive sheet is present in a roll or laminate form, the matte surface of the release film is in contact with the surface of the base layer remote from the surface to be attached to the pressure-sensitive adhesive layer, and the pressure-sensitive adhesive sheet is left to stand at 50°C for 72 hours, and then the release film is removed in an environment of 23°C and a relative humidity of 50%, and the haze measured thereafter is 10 to 80%.

2. The peel force A when peeled at a pulling rate of 300 mm / min in a 180° direction at 23°C is 0.3 to 2.0 N / 20 mm, The film is attached to an adherend at 23°C, left at 50°C for 24 hours, and then peeled in a 180° direction at a pulling rate of 300 mm / min, with a peel strength B of 0.5 to 2.5 N / 20 mm; 2. The pressure-sensitive adhesive sheet according to claim 1, wherein the difference between the peeling force B and the peeling force A, ie, peeling force B - peeling force A, is 0.1 to 0.8 N / 20 mm.

3. The peel strength C when peeled at a pulling rate of 10 m / min in a 180° direction at 23°C is 1.0 to 5.0 N / 20 mm, The peel force D when peeled at a pulling rate of 10 m / min in a 20° direction at 23°C is 5.0 to 9.0 N / 20 mm, 2. The pressure-sensitive adhesive sheet according to claim 1, wherein the difference between the peel force D and the peel force C, ie, peel force D - peel force C, is 4.0 to 8.0 N / 20 mm.

4. the peel strength E when the tape is attached to an adherend at 23°C, left at 50°C for 24 hours, and then peeled off in a 180° direction at a pulling rate of 10 m / min is 1.5 to 5.5 N / 20 mm; the peel strength F is 5.5 to 9.5 N / 20 mm when the tape is attached to an adherend at 23°C, left at 50°C for 24 hours, and then peeled off at a pulling rate of 10 m / min in a 20° direction at 23°C, 2. The pressure-sensitive adhesive sheet according to claim 1, wherein the difference between the peel force F and the peel force E, ie, peel force F - peel force E, is 4.5 to 8.5 N / 20 mm.

5. the pressure-sensitive adhesive layer contains a base polymer and a functional resin, the content of the functional resin is 10 to 40 parts by mass relative to 100 parts by mass of the base polymer, 5. The pressure-sensitive adhesive sheet according to claim 1, wherein the functional resin is at least one selected from the group consisting of epoxy resins, phenolic resins, vinyl resins, and rosin resins.

6. The pressure-sensitive adhesive sheet according to claim 5 , wherein the pressure-sensitive adhesive layer further comprises at least one selected from the group consisting of a plasticizer, a crosslinking agent, an antistatic agent, and a release aid.

7. the plasticizer includes at least one selected from the group consisting of dioctyl phthalate, dioctyl terephthalate, and diisononyl phthalate; 7. The pressure-sensitive adhesive sheet according to claim 6, wherein the content of the plasticizer is 20 to 90 parts by mass relative to 100 parts by mass of the base polymer.

8. the content of the crosslinking agent is 0.01 to 15 parts by mass relative to 100 parts by mass of the base polymer; the crosslinking agent includes an epoxy-based crosslinking agent and / or an isocyanate-based crosslinking agent; the content of the epoxy-based crosslinking agent is 0.01 to 5 parts by mass relative to 100 parts by mass of the base polymer; 7. The pressure-sensitive adhesive sheet according to claim 6, wherein the content of the isocyanate-based crosslinking agent is 0.1 to 10 parts by mass relative to 100 parts by mass of the base polymer.

9. the content of the antistatic agent is 0.1 to 15 parts by mass relative to 100 parts by mass of the base polymer; The pressure-sensitive adhesive sheet according to claim 6, wherein the antistatic agent comprises at least one selected from the group consisting of conductive polymers, conductive inorganic fine particles, metal fine particles or fibers, ionic compounds, and ionic surfactants.

10. the peeling aid comprises an ionic surfactant and / or a nonionic surfactant; 7. The pressure-sensitive adhesive sheet according to claim 6, wherein the content of the release aid is 0.1 to 5 parts by mass per 100 parts by mass of the base polymer.

11. The following characteristics: (a) In a peel test at a peel speed of 12 m / min, the peel electrification voltage generated when the PSA sheet is peeled from a release film is 500 V or less; (b) the surface resistivity of the pressure-sensitive adhesive sheet is 1.0 × 10 ４ ~1.0 x 10 １１ ohms / sq. (c) After stretching the pressure-sensitive adhesive sheet in a 360° direction by 1 to 1.2 times, the surface resistivity of the base layer is 1.0 × 10 ５ ~1.0 x 10 ８ ohms / sq, and the surface resistivity of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is 1.0×10 １１ ohms / sq or less, (d) the rate of change in the logarithm of the surface resistivity of the PSA sheet calculated by the following formula (1) is 100% or less; Change in logarithmic value of surface resistivity (%) = [(X2 - X1) / X1] × 100% (1) (In the formula, X2 represents the logarithm of the surface resistivity after the pressure-sensitive adhesive sheet has been stretched 1 to 1.2 times in the 360° direction, and X1 represents the logarithm of the surface resistivity of the pressure-sensitive adhesive sheet before stretching.) (e) the pressure-sensitive adhesive sheet has a tensile strength in the longitudinal direction (MD direction) of 15 to 60 MPa; (f) the tensile strength of the pressure-sensitive adhesive sheet in the width direction (TD direction) is 10 to 50 MPa; (g) the ratio of the tensile strength in the longitudinal direction (MD direction) to the tensile strength in the transverse direction (TD direction) of the pressure-sensitive adhesive sheet is 1.0 to 1.5; (h) the 50% elastic modulus in the longitudinal direction (MD direction) of the pressure-sensitive adhesive sheet is 15 to 50 MPa; (i) the 50% elastic modulus in the width direction (TD direction) of the pressure-sensitive adhesive sheet is 10 to 45 MPa; (j) the breaking elongation in the longitudinal direction (MD direction) of the pressure-sensitive adhesive sheet is 100 to 300%; (k) the pressure-sensitive adhesive sheet has a breaking elongation in the width direction (TD direction) of 80 to 270%; (l) the ratio of the breaking elongation in the longitudinal direction (MD direction) to the breaking elongation in the width direction (TD direction) of the pressure-sensitive adhesive sheet is 1.0 to 1.5; (m) the pressure-sensitive adhesive sheet has a heat shrinkage rate at 50°C in the longitudinal direction (MD direction) of 1.0 to 8%; (n) the pressure-sensitive adhesive sheet has a 50°C heat shrinkage rate in the width direction (TD direction) of -6.0 to 3.0%; (o) the light transmittance of the pressure-sensitive adhesive sheet after removal of the release film is 50 to 90%; (p) the pressure-sensitive adhesive sheet is left at 50°C for 72 hours, and then the release film is removed in an environment of 23°C and a relative humidity of 50%, and the haze measured thereafter is 15 to 55%; The pressure-sensitive adhesive sheet according to any one of claims 1 to 10, wherein at least one of the following conditions is satisfied:

12. the substrate layer contains a polyvinyl chloride resin and at least one selected from the group consisting of a plasticizer, a stabilizer, and a haze adjuster; The content of the plasticizer is 10 to 60 parts by mass relative to 100 parts by mass of polyvinyl chloride resin, the plasticizer includes at least one selected from the group consisting of dioctyl phthalate, dioctyl terephthalate, and diisononyl phthalate; The content of the stabilizer is 0.1 to 5.0 parts by mass relative to 100 parts by mass of polyvinyl chloride resin, 12. The pressure-sensitive adhesive sheet according to claim 1, wherein the content of the haze adjuster is 0.1 to 10 parts by mass relative to 100 parts by mass of the polyvinyl chloride resin.

13. The pressure-sensitive adhesive sheet according to any one of claims 1 to 12, characterized in that the base layer has an arithmetic mean surface roughness Ra of 1 to 6 μm at 23 ° C., or the surface of the base layer has a surface roughness with a maximum height (Rz) of 6 to 12 μm at 23 ° C.

14. further comprising an undercoat layer and / or a backcoat layer; the backcoat layer is provided on the substrate layer on the opposite side to the pressure-sensitive adhesive layer, The pressure-sensitive adhesive sheet according to any one of claims 1 to 13, wherein the undercoat layer is provided on the substrate layer on the side opposite to the backcoat layer.

15. the backcoat layer has an arithmetic mean surface roughness Ra of 0.1 to 5.0 μm at 23° C., or the surface of the backcoat layer has a surface roughness with a maximum height (Rz) of 1 to 10 μm at 23° C., The pressure-sensitive adhesive sheet according to claim 14, wherein the backcoat layer has an arithmetic mean surface roughness Ra of 0.1 to 4.0 μm at 50°C, or the surface of the backcoat layer has a surface roughness with a maximum height (Rz) of 2.0 to 8.0 μm at 50°C.

16. The pressure-sensitive adhesive sheet according to any one of claims 1 to 15, wherein the thickness of the base layer is 5 to 300 µm, and the thickness of the pressure-sensitive adhesive layer is 1 to 40 µm.

17. The pressure-sensitive adhesive sheet according to any one of claims 1 to 16, wherein the pressure-sensitive adhesive sheet has a haze change rate of 10% or less as calculated by the following formula (2): Haze change rate = (haze before aging - haze after aging) / haze before aging × 100% (2) (wherein the formula, the haze before aging is the haze measured after leaving the PSA sheet for 24 hours under a standard environment of 23°C and 50% relative humidity, and then removing the release film, The haze after storage over time is measured after leaving the pressure-sensitive adhesive sheet at 50°C for 72 hours and then removing the release film in an environment of 23°C and a relative humidity of 50%.

18. A roll comprising the pressure-sensitive adhesive sheet according to any one of claims 1 to 17 in a rolled form.

19. A laminate comprising two or more pressure-sensitive adhesive sheets according to any one of claims 1 to 17 in a laminated form.

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