WO2017191835A1 - Adhesive sheet - Google Patents

Abstract

Provided is an adhesive sheet having good adhesion in a normal state, excellent release properties when releasing from an adherend, and excellent nonflammability. This adhesive sheet is provided with an adhesive layer having a surface A in which the adhesive force thereof is decreased by an external stimulus, the adhesive force X_A1 with respect to SUS304BA at 23°C of the surface A prior to the external stimulus being at least 10 N/20 mm, the adhesive force X_A2 with respect to SUS304BA at 23°C of the surface A being made less than 8 N/20 mm by the external stimulus, and the adhesive sheet having flame nonflammability corresponding to V-0 in a test in accordance with a UL94 vertical flame test.

Description

Adhesive sheet

The present invention relates to an adhesive sheet.

Conventionally, materials applied to buildings such as houses, vehicles, aircraft, ships, etc. (for example, inner wall materials) have been required to be flame retardant or non-flammable to prevent the spread of fire in the event of a fire. Further, in electronic devices that are becoming smaller in size, there is a tendency that the influence of heat accumulated in the devices is increased, and the materials constituting the electronic devices are also required to be flame retardant and nonflammable. Under such circumstances, excellent flame retardancy is also required for the pressure-sensitive adhesive sheet used for sticking the above materials.

On the other hand, the pressure-sensitive adhesive sheet used for sticking the inner wall material has sufficient adhesive strength in normal conditions, and in situations where the inner wall material needs to be peeled off, such as when changing the inner wall material, damage to the adherend and It is preferable that the adhesive can be easily peeled off without any adhesive residue. Moreover, the adhesive sheet used for an electronic device may be requested | required to have moderate removability (rework property) according to the malfunction in a manufacturing process.

JP 2014-167092 A

The present invention has been made in order to solve the above-described conventional problems, and the object is to have good adhesiveness in a normal state, excellent peelability when peeling from an adherend, and An object of the present invention is to provide a pressure-sensitive adhesive sheet having excellent flame retardancy.

The pressure-sensitive adhesive sheet of the present invention is a pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer having a surface A whose adhesive strength is reduced by an external stimulus, and the adhesive force X to SUS304BA at 23 ° C. of the surface A before applying the external stimulus. _{When A1} is 10 N / 20 mm or more and the external stimulus is applied, the adhesive strength X _A2 of the surface A to SUS304BA at 23 ° C. is less than 10 N / 20 mm. In the test according to the UL94 vertical combustion test, V− Has flame resistance equivalent to zero.
In one embodiment, the pressure-sensitive adhesive layer is composed of a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer,
The first pressure-sensitive adhesive layer has the surface A in which the adhesive force is reduced by an external stimulus, and in a test according to FAR 25.853, the combustion time is 12 seconds or less, the combustion distance is 200 mm or less, The drip time is within 5 seconds.
In one embodiment, the above-mentioned adhesive layer contains a flame retardant.
In one embodiment, the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer contain a flame retardant.
In one embodiment, the adhesive strength _{X A2} for SUS304BA at 23 ° C. of the surface A after giving the external stimulus, adhesion to SUS304BA at 23 ° C. of said surface A before providing the external stimulus _{X A1} Is 90% or less.
In one embodiment, the external stimulus is heating, cooling, or active energy ray irradiation.
In one embodiment, the pressure-sensitive adhesive layer contains thermally expandable microspheres.
In one embodiment, the above-mentioned adhesive layer contains an acrylic adhesive.
In one embodiment, the pressure-sensitive adhesive layer is a layer obtained by curing an active energy ray-curable monomer composition.
In one embodiment, the first pressure-sensitive adhesive layer includes thermally expandable microspheres.
In one embodiment, the first pressure-sensitive adhesive layer contains an acrylic pressure-sensitive adhesive.
In one embodiment, the first pressure-sensitive adhesive layer is a layer obtained by curing an active energy ray-curable monomer composition.
In one embodiment, the flame retardant is a metal hydroxide.

According to the present invention, it is possible to provide a pressure-sensitive adhesive sheet having good adhesiveness in a normal state, excellent peelability when peeled from an adherend, and excellent flame retardancy.

It is a schematic sectional drawing of the adhesive sheet by one Embodiment of this invention. It is a schematic sectional drawing of the adhesive sheet by another embodiment of this invention.

A. Outline of Adhesive Sheet FIG. 1 is a schematic sectional view of an adhesive sheet according to one embodiment of the present invention. The pressure-sensitive adhesive sheet 100 includes a pressure-sensitive adhesive layer 10. The pressure-sensitive adhesive layer 10 has a surface A whose adhesive force is reduced by an external stimulus. Practically, the pressure-sensitive adhesive layer 10 can include a flame retardant and a pressure-sensitive adhesive. The pressure-sensitive adhesive sheet of the present invention can be used as a double-sided pressure-sensitive adhesive sheet.

The pressure-sensitive adhesive sheet of the present invention is composed of a pressure-sensitive adhesive layer having a surface A whose adhesive strength is reduced by an external stimulus, and thus gives an external stimulus such as heating while having good adhesiveness under normal conditions. Thus, it can be easily peeled off from the adherend without any adhesive residue. The pressure-sensitive adhesive sheet of the present invention thus exhibits excellent removability and is also excellent in flame retardancy. In addition, the pressure-sensitive adhesive sheet of the present invention has a feature that even when exposed to a flame, it is difficult to peel off from the adherend around a portion exposed to the flame. If the pressure-sensitive adhesive sheet of the present invention is used, for example, when wallpaper is applied to the inner wall, the fire resistance of the inner wall can be improved without requiring special flame retardant treatment (for example, formation of a metal layer) on the wallpaper. This makes it easy to attach wallpaper to uneven surfaces and corners.

Examples of the external stimulus include heating, cooling, and active energy ray irradiation. Examples of active energy rays include ultraviolet rays. The external stimulus is defined as a stimulus (for example, heating, cooling or irradiation with active energy rays) that can reduce the adhesive strength of a predetermined surface to 90% or less (preferably 80% or less, more preferably 70%). You can also. The details of the pressure-sensitive adhesive layer whose adhesive force is reduced by these external stimuli will be described later.

FIG. 2 is a schematic cross-sectional view of an adhesive sheet according to another embodiment of the present invention. This pressure-sensitive adhesive sheet 200 has a two-layer structure of pressure-sensitive adhesive layers, and includes a first pressure-sensitive adhesive layer 11 and a second pressure-sensitive adhesive layer 12 as pressure-sensitive adhesive layers. The 1st adhesive layer 11 and the 2nd adhesive layer 12 may contain a flame retardant. The 1st adhesive layer 11 has the surface A from which adhesive force falls by external stimulation. Thus, when the pressure-sensitive adhesive layer has a two-layer structure, only one surface of the pressure-sensitive adhesive sheet (only surface A in FIG. 2) exhibits the desired peelability. If such an adhesive sheet is used, at the time of peeling, the adhesive sheet is not left on the adherend on the surface A side, and is adhered to the other surface (surface B opposite to surface A in FIG. 2). The attached adherend and the pressure-sensitive adhesive sheet can be peeled together. For example, when wallpaper is attached to the inner wall via the pressure-sensitive adhesive sheet, the wallpaper with the pressure-sensitive adhesive sheet can be reliably peeled off from the inner wall, and the pressure-sensitive adhesive sheet is prevented from remaining on the inner wall. Can do. Use of such an adhesive sheet can contribute to the improvement of workability when the wallpaper is replaced. If the pressure-sensitive adhesive layer has a two-layer structure, it becomes easy to adjust the adhesiveness of each surface according to the adherend.

The pressure-sensitive adhesive sheet of the present invention may be composed of only a pressure-sensitive adhesive layer (or a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer), and any appropriate layer (not shown) in addition to the pressure-sensitive adhesive layer. May be further provided. Examples of layers other than the pressure-sensitive adhesive layer include a base material layer that can function as a support, and an elastic layer that can impart elasticity to the pressure-sensitive adhesive sheet. The base material layer and the elastic layer are preferably disposed between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer. The base material layer and the elastic layer are preferably flame retardant. Moreover, the adhesive sheet of this invention may be provided in combination with the separator arrange | positioned so that peeling is possible on an adhesive layer. The separator protects the pressure-sensitive adhesive layer until the pressure-sensitive adhesive sheet is used.

The adhesive strength X _A1 of the surface A before applying external stimulus to the SUS304BA plate at 23 ° C. is 10 N / 20 mm or more, preferably 10 N / 20 mm to 50 N / 20 mm, more preferably 12 N / 20 mm to 50 N / 20 mm. If it is such a range, the adhesive sheet which has suitable adhesiveness can be obtained in the use for which a flame retardance is calculated | required. In this specification, the adhesive strength refers to an adhesive strength measured by a method according to JIS Z 0237: 2000 (bonding conditions: 2 kg roller 1 reciprocation, peeling speed: 300 mm / min, peeling angle 180 °).

Adhesion _{X B1} for SUS304BA plate at 23 ° C. on the opposite side of the surface B from the front of the surface A providing an external stimulus is preferably 10 N / 20 mm or higher, more preferably at 10N / 20mm ~ 50N / 20mm More preferably, it is 12 N / 20 mm to 50 N / 20 mm. If it is such a range, the adhesive sheet which has suitable adhesiveness can be obtained in the use for which a flame retardance is calculated | required. Incidentally, before applying an external stimulus, the adhesive force X _B1 of adhesion X _A1 and face B side A may be the same or may be different.

In the pressure-sensitive adhesive sheet of the present invention, by applying an external stimulus, the adhesive force X _{A2 of the} surface A to the SUS304BA plate at 23 ° C. is less than 10 N / 20 mm, preferably 9 N / 20 mm or less, more preferably 8 N / 20 mm or less. If it is such a range, in the scene which needs peeling, the easily peelable adhesive sheet can be obtained. The lower limit of the adhesive strength _{X A2} for SUS304BA plate at 23 ° C. of said surface A after applying an external stimulus, preferably at 0.1 N / 20 mm or more, more preferably be 0.5 N / 20 mm or more, more preferably 1.0 N / 20 mm or more. If it is such a range, in the scene which needs peeling, an adhesive sheet with favorable workability | operativity can be obtained. After applying an external stimulus, the adhesive force X _A2 of the surface A and the adhesive force X _B2 of the surface B may be the same or different. In one embodiment, when the pressure-sensitive adhesive layer has a single-layer structure, the adhesive force X _A2 of the surface A and the adhesive force X _B2 of the surface B are the same after external stimulation is applied. In one embodiment, when the pressure-sensitive adhesive layer has a two-layer structure, the decrease in the adhesive force _{XA2 on} the surface A is greater than the change in the adhesive force _{XB2 on} the surface B after external stimulation is applied.

The adhesive force X _A2 of the surface A after applying the external stimulus to SUS304BA at 23 ° C. is preferably 90 relative to the adhesive force X _A1 of the surface A to 23 ° C. before applying the external stimulus. % Or less, more preferably 80% or less, and even more preferably 70% or less.

The pressure-sensitive adhesive sheet of the present invention has a flame retardancy equivalent to V-0 in a test according to the UL94 vertical combustion test. Details of the combustion test method will be described later.

In one embodiment, the pressure-sensitive adhesive sheet of the present invention has a combustion time of 12 seconds or less (preferably 10 seconds or less, more preferably 5 seconds or less) and a combustion distance of 200 mm in a test according to FAR 25.853. Or less (preferably 150 mm or less, more preferably 100 mm or less), and the drip time is within 5 seconds (preferably within 3 seconds, more preferably within 1 second). Details of the combustion test method will be described later.

The thickness of the pressure-sensitive adhesive sheet of the present invention is preferably 20 μm to 1000 μm, more preferably 30 μm to 500 μm.

The thickness of the pressure-sensitive adhesive layer is preferably 20 μm to 1000 μm, more preferably 30 μm to 500 μm. The thickness of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer is preferably 10 μm to 500 μm, more preferably 15 μm to 250 μm, and still more preferably 20 μm to 150 μm. The thickness of the first pressure-sensitive adhesive layer and the thickness of the second pressure-sensitive adhesive layer may be the same or different.

B. Adhesive layer
B-1. In the paragraph B-1 of the pressure-sensitive adhesive layer having the surface A whose adhesive strength is reduced by an external stimulus, the “pressure-sensitive adhesive layer having the surface A whose adhesive strength is reduced by an external stimulus” will be described. When the pressure-sensitive adhesive layer has a single-layer structure, the pressure-sensitive adhesive layer corresponds to “a pressure-sensitive adhesive layer having a surface A whose adhesive force is reduced by an external stimulus”. In the case where the pressure-sensitive adhesive layer has a two-layer structure, the first pressure-sensitive adhesive layer corresponds to a “pressure-sensitive adhesive layer having a surface A whose adhesive force is reduced by an external stimulus”.

As the pressure-sensitive adhesive layer having the surface A whose adhesive strength is reduced by external stimulation, the pressure-sensitive adhesive layer whose adhesive strength is reduced by heating that is external stimulation (for example, a pressure-sensitive adhesive layer containing thermally expandable microspheres, heat-curing pressure-sensitive adhesive) Adhesive layer), an adhesive layer whose adhesive strength is reduced by cooling as an external stimulus, an adhesive layer whose adhesive strength is reduced by active energy ray irradiation as an external stimulus (for example, an ultraviolet-curing adhesive layer), and the like. .

B-1-1. Pressure-sensitive adhesive layer whose adhesive strength is reduced by heating In one embodiment, the pressure-sensitive adhesive layer is reduced or disappears by heating. Examples of such a pressure-sensitive adhesive layer include a pressure-sensitive adhesive layer containing thermally expandable microspheres, a heat-curable adhesive layer, and the like.

B-1-1-1. Pressure-sensitive adhesive layer containing thermally expandable microspheres The pressure-sensitive adhesive layer containing thermally expandable microspheres contains pressure-sensitive adhesive A, thermally expandable microspheres, and a flame retardant (described in detail in Section B-3). When the pressure-sensitive adhesive layer is heated, the heat-expandable microspheres expand or foam, and as a result, unevenness is generated on the pressure-sensitive adhesive surface, resulting in a decrease or disappearance of the adhesive force. In the pressure-sensitive adhesive layer containing thermally expandable microspheres, heating at a temperature at which the thermally expandable microspheres can expand or foam corresponds to the external stimulus.

(Adhesive A)
The pressure-sensitive adhesive A contained in the pressure-sensitive adhesive layer containing the thermally expandable microspheres is preferably one that does not restrain expansion or foaming of the thermally expandable microspheres during heating. Examples of the adhesive include acrylic adhesives, rubber adhesives, vinyl alkyl ether adhesives, silicone adhesives, polyester adhesives, polyamide adhesives, urethane adhesives, and styrene-diene block copolymers. Examples thereof include a polymer-based pressure-sensitive adhesive. Among these, an acrylic pressure-sensitive adhesive is preferable. In addition, you may use the said adhesive individually or in combination of 2 or more types.

Examples of the acrylic pressure-sensitive adhesive include an acrylic pressure-sensitive adhesive based on a (meth) acrylic polymer (homopolymer or copolymer) using one or more (meth) acrylic acid alkyl esters as monomer components. Agents and the like. The alkyl group of the (meth) acrylic acid alkyl ester is preferably a C1-20 linear, branched, or cyclic alkyl group, more preferably a C1-10 linear, branched, Or a cyclic alkyl group, particularly preferably a methyl group, an ethyl group, a butyl group, a 2-ethylhexyl group, and an octyl group. The (meth) acrylic polymer may be a homopolymer obtained using only one kind of (meth) acrylic acid alkyl ester, or obtained using two or more kinds of (meth) acrylic acid alkyl ester. A copolymer may also be used. In the present specification, (meth) acrylic means to include both acrylic and methacrylic.

The (meth) acrylic polymer corresponds to other monomer components copolymerizable with the (meth) acrylic acid alkyl ester as necessary for the purpose of modifying cohesive strength, heat resistance, crosslinkability and the like. A structural unit may be included. Examples of such monomer components include carboxyl group-containing monomers such as acrylic acid and methacrylic acid; acid anhydride monomers such as maleic anhydride and itaconic anhydride; hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate Hydroxyl group-containing monomers such as styrene sulfonic acid and allyl sulfonic acid, etc .; (N-substituted) amide monomers such as (meth) acrylamide and N, N-dimethyl (meth) acrylamide; (Meth) acrylic acid aminoalkyl monomers such as aminoethyl acrylate; (meth) alkoxyalkyl monomers such as methoxyethyl (meth) acrylate; maleimide monomers such as N-cyclohexylmaleimide; N-methylitaconimide Etc. Succinimide monomers such as N- (meth) acryloyloxymethylene succinimide; vinyl monomers such as vinyl acetate, vinyl propionate and N-vinylpyrrolidone; cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; Epoxy group-containing acrylic monomers such as glycidyl acrylate; glycol acrylic ester monomers such as polyethylene glycol (meth) acrylate; tetrahydrofurfuryl (meth) acrylate, complex such as fluorine (meth) acrylate and silicone (meth) acrylate Acrylic acid ester monomers having rings, halogen atoms, silicon atoms, etc .; hexanediol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) pro Lenglycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate And polyfunctional monomers such as epoxy acrylate, polyester acrylate, and urethane acrylate; olefin monomers such as isoprene, butadiene, and isobutylene; vinyl ether monomers such as vinyl ether, and the like. These monomer components may be used alone or in combination of two or more.

In one embodiment, the (meth) acrylic polymer does not substantially contain a structural unit corresponding to a carboxyl group-containing monomer. Such a pressure-sensitive adhesive composed of a (meth) acrylic polymer is particularly useful when the adherend is a metal or the like, and the use of the pressure-sensitive adhesive can prevent corrosion of the adherend. . A “carboxyl group-containing monomer” is a monomer having one or more carboxyl groups (may be in the form of anhydrides) in one molecule, such as (meth) acrylic acid, itaconic acid, maleic acid, fumaric acid , Crotonic acid, isocrotonic acid, maleic anhydride, itaconic anhydride and the like. Further, “substantially free” means that it is not actively blended unless it is inevitably mixed. Specifically, in a (meth) acrylic polymer, it is derived from a carboxyl group-containing monomer. It means that the content ratio of the structural unit is 0.1% by weight or less (preferably less than 0.05% by weight, more preferably less than 0.01% by weight).

In the (meth) acrylic polymer, the content of the structural unit derived from the (meth) acrylic acid alkyl ester is preferably 60% by weight or more, more preferably 80% by weight or more, and still more preferably 80% by weight. ~ 99% by weight.

The (meth) acrylic polymer can be obtained by polymerizing one or more of the above monomers. The polymerization can be performed by any method such as solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization and the like.

In one embodiment, the pressure-sensitive adhesive layer is a layer obtained by curing an active energy ray-curable monomer composition. The active energy ray-curable monomer composition includes, for example, the (meth) acrylic acid alkyl ester and the other monomer component (particularly, a crosslinkable monomer such as a polyfunctional monomer). The layer obtained by curing the active energy ray-curable monomer composition is a layer formed by curing the active energy ray-curable monomer composition by irradiating active energy rays (for example, ultraviolet rays), and an adhesive. A cured product (base polymer) of the active energy ray-curable monomer composition is included as A (preferably an acrylic pressure-sensitive adhesive).

The pressure-sensitive adhesive A (and the active energy ray-curable monomer composition) may contain any appropriate additive as necessary. Examples of the additive include a crosslinking agent, a tackifier, a plasticizer (for example, trimellitic acid ester plasticizer, pyromellitic acid ester plasticizer), pigment, dye, filler, anti-aging agent, conductive material. , Antistatic agents, ultraviolet absorbers, light stabilizers, release modifiers, softeners, surfactants, antioxidants, and the like.

(Thermally expandable microsphere)
As the thermally expandable microsphere, any appropriate thermally expandable microsphere can be used as long as it is a microsphere that can expand or foam by heating. As the thermally expandable microsphere, for example, a microsphere in which a substance that easily expands by heating is encapsulated in an elastic shell can be used. Such thermally expandable microspheres can be produced by any appropriate method, for example, a coacervation method, an interfacial polymerization method, or the like.

Examples of the material that easily expands when heated include propane, propylene, butene, normal butane, isobutane, isopentane, neopentane, normal pentane, normal hexane, isohexane, heptane, octane, petroleum ether, methane halide, tetraalkylsilane. And low-boiling-point liquids such as azodicarbonamide that is gasified by thermal decomposition.

Examples of the material constituting the shell include nitrile monomers such as acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-ethoxyacrylonitrile, fumaronitrile; acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid Carboxylic acid monomers such as vinylidene chloride; vinyl acetate; methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, isobornyl (meth) (Meth) acrylic acid esters such as acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, β-carboxyethyl acrylate; styrene such as styrene, α-methylstyrene, chlorostyrene Nomar; include polymer composed like; acrylamides, substituted acrylamides, methacrylamide, amides monomers such as substituted methacrylamide. The polymer composed of these monomers may be a homopolymer or a copolymer. Examples of the copolymer include vinylidene chloride-methyl methacrylate-acrylonitrile copolymer, methyl methacrylate-acrylonitrile-methacrylonitrile copolymer, methyl methacrylate-acrylonitrile copolymer, acrylonitrile-methacrylonitrile-itaconic acid copolymer. A polymer etc. are mentioned.

An inorganic foaming agent or an organic foaming agent may be used as the thermally expandable microsphere. Examples of the inorganic foaming agent include ammonium carbonate, ammonium hydrogen carbonate, sodium hydrogen carbonate, ammonium nitrite, sodium borohydride, various azides and the like. Examples of the organic foaming agent include chlorofluorinated alkane compounds such as trichloromonofluoromethane and dichloromonofluoromethane; azo compounds such as azobisisobutyronitrile, azodicarbonamide, and barium azodicarboxylate. Hydrazine compounds such as paratoluenesulfonyl hydrazide, diphenylsulfone-3,3′-disulfonyl hydrazide, 4,4′-oxybis (benzenesulfonyl hydrazide), allyl bis (sulfonyl hydrazide); p-toluylene sulfonyl semicarbazide, 4, Semicarbazide compounds such as 4′-oxybis (benzenesulfonyl semicarbazide); Triazole compounds such as 5-morpholyl-1,2,3,4-thiatriazole; N, N′-dinitrosopentamethylenetetramine, N, '- dimethyl -N, N'-dinitrosoterephthalamide; etc. N- nitroso compounds, and the like.

Commercially available products may be used for the above-mentioned thermally expandable microspheres. Specific examples of commercially available thermally expandable microspheres include “Matsumoto Microsphere” (grade: F-30, F-30D, F-36D, F-36LV, F-50) manufactured by Matsumoto Yushi Seiyaku Co., Ltd. F-50D, F-65, F-65D, FN-100SS, FN-100SSD, FN-180SS, FN-180SSD, F-190D, F-260D, F-2800D), trade names “Nippon Philite” "Expansel" (grade: 053-40, 031-40, 920-40, 909-80, 930-120), "Die Form" (grade: H750, H850, H1100, S2320D, S2640D, manufactured by Kureha Chemical Industry Co., Ltd.) M330, M430, M520), “ADVANCEL” manufactured by Sekisui Chemical Co., Ltd. (grade: EML101, EMH204, EHM3) 1, EHM302, EHM303, EM304, EHM401, EM403, EM501) and the like.

The particle diameter of the thermally expandable microsphere before heating is preferably 0.5 μm to 80 μm, more preferably 5 μm to 45 μm, still more preferably 10 μm to 20 μm, and particularly preferably 10 μm to 15 μm. . Speaking of the average particle size of the heat-expandable microspheres before heating, the particle size is preferably 6 μm to 45 μm, more preferably 13 μm to 35 μm. Thermally expandable microspheres having a particle size in such a range are excellent in dispersibility. In addition, said particle diameter and average particle diameter are the values calculated | required by the particle size distribution measuring method in a laser scattering method.

It is preferable that the thermally expandable microspheres have an appropriate strength that does not rupture until the volume expansion coefficient is preferably 5 times or more, more preferably 7 times or more, and even more preferably 10 times or more. When such a heat-expandable microsphere is used, the adhesive force can be efficiently reduced by heat treatment.

The content ratio of the heat-expandable microspheres in the pressure-sensitive adhesive layer can be appropriately set according to the desired decrease in adhesive strength. The content ratio of the heat-expandable microspheres is, for example, 1 part by weight to 150 parts by weight, preferably 5 parts by weight to 130 parts by weight, and more preferably 10 parts by weight with respect to 100 parts by weight of the base polymer forming the adhesive A. ~ 100 parts by weight.

B-1-1-2. Heat-curable adhesive layer The above-mentioned heat-curable adhesive layer includes a heat-curable adhesive B and a flame retardant (described in detail in Section B-3). The pressure-sensitive adhesive B can be formed from, for example, a thermosetting pressure-sensitive adhesive containing a base polymer and a thermosetting resin (monomer or oligomer), or a thermosetting pressure-sensitive adhesive containing a thermosetting resin as a base polymer. . Examples of the thermosetting resin used for the adhesive B include phenolic resins, amino resins, unsaturated polyester resins, epoxy resins, polyurethane resins, silicone resins, thermosetting polyimide resins, and the like. It is done. Examples of the base polymer used in combination with the thermosetting resin include (meth) acrylic polymers and rubber polymers.

B-1-1-3. Other pressure-sensitive adhesive layers whose adhesive strength is reduced by heating The pressure-sensitive adhesive layer whose pressure-sensitive adhesive strength is reduced by heating is not limited to the above-described pressure-sensitive adhesive layer, as long as the effects of the present invention can be obtained. An adhesive layer can be used. Examples of other pressure-sensitive adhesive layers whose pressure-sensitive adhesive strength is reduced by heating include pressure-sensitive pressure-sensitive adhesive C, a side chain crystalline polymer, and a flame retardant (described in detail in Section B-3). . Details of such a pressure-sensitive adhesive layer are described in, for example, JP-A-2015-097195, and the description is incorporated herein by reference.

B-1-2. Pressure-sensitive adhesive layer whose adhesive strength is reduced by irradiation with active energy rays In one embodiment, the pressure-sensitive adhesive layer is cured by irradiation with active energy rays, and the pressure-sensitive adhesive strength is reduced or eliminated. The pressure-sensitive adhesive layer whose adhesive strength is reduced by irradiation with active energy rays can include an active energy ray-curable pressure-sensitive adhesive D that is cured by irradiation with active energy rays and a flame retardant (described in detail in Section B-3). . Examples of the active energy rays include gamma rays, ultraviolet rays, visible rays, infrared rays (heat rays), radio waves, alpha rays, beta rays, electron beams, plasma flows, ionizing rays, particle rays and the like.

Examples of the active energy ray-curable pressure-sensitive adhesive D include an active energy ray-curable pressure-sensitive adhesive containing a base polymer and an active energy ray-curable monomer and / or oligomer (hereinafter referred to as “addition type active energy ray-curable pressure-sensitive adhesive”). Active energy ray-curable pressure-sensitive adhesive containing a polymer having a polymerizable carbon-carbon double bond as a base polymer (hereinafter, also referred to as “base polymer-type active energy ray-curable pressure-sensitive adhesive”). .

As the base polymer contained in the additive-type active energy ray-curable pressure-sensitive adhesive, any appropriate polymer can be adopted as long as it can exhibit adhesiveness. Specific examples of the base polymer include (meth) acrylic polymers and rubber polymers. Preferably, the base polymer is a (meth) acrylic polymer. Examples of the (meth) acrylic polymer include the polymers described above.

The (meth) acrylic polymer contained in the additive-type active energy ray-curable pressure-sensitive adhesive may have a polymerizable carbon-carbon double bond. As the (meth) acrylic polymer having a polymerizable carbon-carbon double bond, a (meth) acrylic polymer that can be used as a base polymer of the base polymer type active energy ray-curable pressure-sensitive adhesive can be used. The polymer will be described later.

As the active energy ray-curable monomer or oligomer, a monomer or oligomer having a functional group that crosslinks upon irradiation with active energy rays such as a polymerizable carbon-carbon double bond can be employed. Examples of the monomer or oligomer having a functional group include trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, tetraethylene glycol di (meth) acrylate, 1, 6-hexanediol (meth) acrylate, neopentyl glycol di (meth) acrylate, esterified product of (meth) acrylic acid and polyhydric alcohol, ester acrylate oligomer, 2-propenyl-3-butenyl cyanurate, isocyanurate, Examples include isocyanurate compounds. Of these, monomers or oligomers containing an average of 6 or more polymerizable carbon-carbon double bonds in one molecule, such as dipentaerythritol hexa (meth) acrylate, are preferred. Only one type of active energy ray-curable monomer or oligomer may be used, or two or more types may be used in combination. The viscosity of the active energy ray-curable monomer or oligomer is not particularly limited.

The total amount of the active energy ray-curable monomer and oligomer in the additive active energy ray-curable pressure-sensitive adhesive is preferably 1 to 150 parts by weight, more preferably 1 part by weight with respect to 100 parts by weight of the base polymer. -100 parts by weight, particularly preferably 5 parts by weight to 50 parts by weight, and most preferably 10 parts by weight to 40 parts by weight. When the blending amount is within the above range, the adhesive strength is sufficiently lowered by curing.

On the other hand, in the base polymer type active energy ray-curable pressure-sensitive adhesive, since the base polymer itself has a property of crosslinking by irradiation with active energy rays, the addition of the active energy ray-curable monomer or oligomer is not necessarily required. Is optional. In the pressure-sensitive adhesive not containing the monomer or oligomer having a low molecular weight, these low-molecular components do not move with time, so that a pressure-sensitive adhesive layer having a stable structure can be formed.

The polymer having a polymerizable carbon-carbon double bond, which is the base polymer of the base polymer type active energy ray-curable adhesive, includes a polymerizable carbon-carbon double bond in the side chain, in the main chain, or in the main chain. A terminal polymer can be used. As such a polymer, a (meth) acrylic polymer that can be used as a base polymer in the additive-type active energy ray-curable pressure-sensitive adhesive has a basic skeleton, and a polymerizable carbon-carbon double bond is introduced into the basic skeleton. Polymers are preferred. Considering the ease of molecular design, the polymerizable carbon-carbon double bond is preferably introduced into the side chain of the (meth) acrylic polymer.

The number of polymerizable carbon-carbon double bonds per molecule of the polymer having a polymerizable carbon-carbon double bond is preferably 6 or more on average. When the number of polymerizable carbon-carbon double bonds per molecule is 6 or more on average, the pressure-sensitive adhesive is sufficiently cured by irradiation with active energy rays and the adhesive strength is reduced.

The weight average molecular weight of the polymer having a polymerizable carbon-carbon double bond is preferably about 500,000 or more, more preferably about 800,000 to 3,000,000. If the weight average molecular weight is less than 500,000, sufficient cohesive force cannot be obtained and the adherend may be contaminated.

The base polymer type active energy ray-curable pressure-sensitive adhesive may contain an active energy ray-curable monomer and / or oligomer as necessary. Preferred examples of the active energy ray-curable monomer and oligomer include the active energy ray-curable monomer and oligomer used in the additive-type active energy ray-curable pressure-sensitive adhesive.

The total amount of the active energy ray-curable monomer and oligomer in the base polymer type active energy ray-curable pressure-sensitive adhesive is preferably 1 to 150 parts by weight, more preferably 1 part by weight based on 100 parts by weight of the base polymer. Parts to 100 parts by weight, particularly preferably 1 part to 50 parts by weight, and most preferably 5 parts to 40 parts by weight.

The additive type and base polymer type active energy ray-curable pressure-sensitive adhesive may further contain a photopolymerization initiator, if necessary.

Examples of the photopolymerization initiator include benzoin alkyl ethers such as benzoin methyl ether, benzoisopropyl ether, benzoin isopropyl ether and benzoin isobutyl ether; fragrances of benzyl, benzoin, benzophenone and α-hydroxycyclohexyl phenyl ketones. Aromatic ketones such as benzyldimethyl ketal; thioxanthones such as polyvinylbenzophenone, chlorothioxanthone, dodecylthioxanthone, dimethylthioxanthone, and diethylthioxanthone.

The blending amount of the photopolymerization initiator is, for example, 0.1 to 20 parts by weight, preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of the base polymer contained in the pressure-sensitive adhesive.

B-1-3. Pressure-sensitive adhesive layer whose adhesive strength is reduced by cooling In one embodiment, the pressure-sensitive adhesive layer is reduced or disappears by cooling. The pressure-sensitive adhesive layer may contain a pressure-sensitive adhesive E whose adhesive strength is reduced by cooling and a flame retardant (described in detail in Section B-3). Examples of the adhesive E include natural rubber adhesive, cis-isoprene rubber, styrene-isoprene rubber, budadien rubber, nitrile rubber adhesive, chloroprene rubber adhesive, chlorosulfonated polyethylene adhesive, and polysulfide rubber. -Based adhesives, butyl rubber-based adhesives, and the like. The pressure-sensitive adhesive E may contain a tackifier such as alkylphenol-formaldehyde resin, coumarone-indene resin, xylene-formaldehyde resin.

Further, as the adhesive E, a side chain crystalline polymer may be used. By using the side-chain crystalline polymer alone or using the side-chain crystalline polymer as a main component, an adhesive layer whose adhesive strength is reduced by cooling can be formed. Examples of the side chain crystalline polymer include (meth) acrylic acid alkyl ester having a linear alkyl group of C18 or more (preferably C18-22) and (meth) acrylic acid having an alkyl group of C6 or less. Examples thereof include polymers obtained using an alkyl ester and a polar monomer as monomer components. Examples of the polar monomer include carboxyl-containing ethylenically unsaturated monomers such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid and fumaric acid; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl ( Examples thereof include ethylenically unsaturated monomers having a hydroxyl group such as (meth) acrylate and 2-hydroxyhexyl (meth) acrylate.

B-2. Second pressure-sensitive adhesive layer The second pressure-sensitive adhesive layer contains any appropriate pressure-sensitive adhesive and a flame retardant (described in detail in Section B-3).

Examples of the pressure-sensitive adhesive contained in the second pressure-sensitive adhesive layer include the pressure-sensitive adhesive A. In one embodiment, the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer include an acrylic pressure-sensitive adhesive. If the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer are both composed of an acrylic pressure-sensitive adhesive, a two-layer pressure-sensitive adhesive layer having excellent interlayer adhesion can be obtained. The acrylic pressure-sensitive adhesive contained in the first pressure-sensitive adhesive layer and the acrylic pressure-sensitive adhesive contained in the second pressure-sensitive adhesive layer may have the same composition or different compositions.

B-3. Flame retardant As described above, the pressure-sensitive adhesive layer contains a flame retardant. When the pressure-sensitive adhesive layer has a two-layer structure, it is preferable that both the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer contain a flame retardant.

Any appropriate flame retardant is used as the flame retardant. Examples of the flame retardant include metal hydroxide, hydrated metal compound, metal carbonate, barium metaborate, magnesium oxide, zinc borate, tin compound, carbon black, and layered silicate. Among these, a metal hydroxide or a hydrated metal compound is preferable, and a metal hydroxide is more preferable.

Examples of the metal hydroxide include aluminum hydroxide, magnesium hydroxide, calcium hydroxide, zinc hydroxide, iron hydroxide, copper hydroxide, and barium hydroxide. Of these, aluminum hydroxide or calcium hydroxide is preferable, and aluminum hydroxide is more preferable. If these metal hydroxides are used, a pressure-sensitive adhesive sheet having more excellent flame retardancy can be obtained.

Examples of the hydrated metal compound include boehmite, zirconium oxide hydrate, basic magnesium carbonate, hydrotalcite, dowsonite, zinc borate and the like.

The average particle size of the flame retardant is preferably 0.1 μm to 100 μm, more preferably 0.5 μm to 70 μm, and further preferably 1 μm to 50 μm. If it is such a range, the adhesive layer excellent in the balance of adhesiveness and a flame retardance can be formed. The average particle size of the flame retardant is a volume-based value (D50 value) determined by a particle size distribution measurement method in the laser scattering method.

In one embodiment, two or more flame retardants having different particle size distributions are used. According to such an embodiment, it is possible to easily obtain an adhesive layer that is excellent in both adhesiveness and flame retardancy. In one embodiment, a flame retardant (eg, metal hydroxide) having an average particle size of 0.1 μm to 30 μm (preferably 0.5 μm to 20 μm, more preferably 1 μm to 10 μm) and an average particle size of 35 μm. A flame retardant (for example, metal hydroxide) of ˜100 μm (preferably 40 μm to 70 μm, more preferably 40 μm to 60 μm) is used in combination.

The content ratio of the flame retardant contained in each pressure-sensitive adhesive layer is preferably 30 parts by weight to 500 parts by weight, and more preferably 50 parts by weight with respect to 100 parts by weight of the base polymer constituting the pressure-sensitive adhesive layer containing the flame retardant. Parts by weight to 450 parts by weight, more preferably 80 parts by weight to 400 parts by weight, and particularly preferably 100 parts by weight to 300 parts by weight. If it is such a range, the adhesive layer excellent in the balance of adhesiveness and a flame retardance can be formed. When two types of flame retardants having different particle size distributions are used, the ratio of the content ratio of the large particle size flame retardant and the small particle size flame retardant (large particle size / small particle size; weight basis) is preferably 0.5. Is more preferably 0.65 to 1.5, still more preferably 0.8 to 1.2, and particularly preferably 0.95 to 1.05.

C. Manufacturing method of adhesive sheet The adhesive sheet of this invention can be manufactured by arbitrary appropriate methods. The pressure-sensitive adhesive sheet of the present invention can be obtained, for example, by coating a pressure-sensitive adhesive layer forming composition on any appropriate substrate to form a pressure-sensitive adhesive layer. The substrate may be peeled off after the pressure-sensitive adhesive layer is formed, or may be used as it is as a separator for the pressure-sensitive adhesive sheet.

The pressure-sensitive adhesive layer forming composition contains the pressure-sensitive adhesive (or active energy ray-curable monomer composition) and the flame retardant. When forming a pressure-sensitive adhesive layer containing thermally expandable microspheres, the pressure-sensitive adhesive forming composition used for forming the pressure-sensitive adhesive layer further includes thermally expandable microspheres. Moreover, after forming an adhesive coating layer with the composition containing the adhesive A, after sprinkling thermally expandable microspheres on the adhesive coating layer, the thermally expandable microspheres are formed using a laminator or the like. A pressure-sensitive adhesive layer containing thermally expandable microspheres may be formed by being embedded in the coating layer. In addition, the composition for adhesive layer formation may contain the said additive and / or arbitrary appropriate solvents as needed.

In one embodiment, the pressure-sensitive adhesive layer forming composition may contain a dispersant. If the dispersant is included, the aggregation of the flame retardant can be prevented, and the effect of the present invention becomes remarkable. Examples of the dispersant include polyoxyethylene alkyl (or alkyl allyl) ether or polyoxyethylene alkyl aryl ether phosphoric acid monoester, polyoxyethylene alkyl ether or polyoxyethylene alkyl aryl ether phosphoric acid diester, and phosphoric acid triester. Examples include esters or derivatives thereof. Among these, phosphoric acid esters such as polyoxyethylene alkyl ethers or polyoxyethylene alkyl aryl ethers such as phosphoric acid monoesters and phosphoric acid diesters. The content of the dispersant is preferably 0.001 to 10 parts by weight with respect to 100 parts by weight of the base polymer constituting the pressure-sensitive adhesive.

Examples of the substrate include a resin sheet, nonwoven fabric, paper, metal foil, woven fabric, rubber sheet, foamed sheet, and a laminate thereof (particularly, a laminate including a resin sheet). Examples of the resin constituting the resin sheet include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polyethylene (PE), polypropylene (PP), ethylene-propylene copolymer, ethylene- Vinyl acetate copolymer (EVA), polyamide (nylon), wholly aromatic polyamide (aramid), polyimide (PI), polyvinyl chloride (PVC), polyphenylene sulfide (PPS), fluororesin, polyether ether ketone (PEEK) ) And the like.

Any appropriate coating method can be adopted as a coating method of the pressure-sensitive adhesive layer forming composition. For example, each layer can be formed by drying after coating. Moreover, a hardening process may be given to the composition for adhesive layer formation as needed. Examples of the coating method include a coating method using a multi coater, a die coater, a gravure coater, an applicator, and the like. Examples of the drying method include natural drying and heat drying. The heating temperature in the case of heating and drying can be set to any appropriate temperature according to the characteristics of the substance to be dried. Examples of the curing treatment include heating, active energy ray irradiation (for example, UV irradiation), and the like.

In one embodiment, the pressure-sensitive adhesive layer is composed of a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer, and the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer are cured with active energy rays. When the adhesive monomer composition is a cured layer, the first pressure-sensitive adhesive layer-forming composition is applied onto the first substrate to form a coating layer (a precursor layer of the first pressure-sensitive adhesive layer). The second pressure-sensitive adhesive layer-forming composition is applied onto the substrate 2 to form a coating layer (precursor layer of the second pressure-sensitive adhesive layer), and these coating layers are bonded together. The first pressure-sensitive adhesive layer forming composition and the second pressure-sensitive adhesive layer forming composition are cured to obtain a pressure-sensitive adhesive sheet. After bonding the coating layer, the first and second pressure-sensitive adhesive layer-forming compositions are cured to obtain a pressure-sensitive adhesive sheet having excellent adhesion between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer. be able to.

A mixed layer may be formed between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer. The mixed layer is formed by mixing the components of the first pressure-sensitive adhesive layer and the components of the second pressure-sensitive adhesive layer. For example, as described above, after bonding the coating layers, the first and second pressure-sensitive adhesive layer forming compositions are cured to form a mixed layer. When the mixed layer is formed, the interface between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer may not be discriminated. ) And / or composition (presence or absence or presence of thermally expandable microspheres), the pressure-sensitive adhesive sheet is understood as a two-layer pressure-sensitive adhesive sheet.

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. The evaluation methods in the examples are as follows. In Examples, “parts” and “%” are based on weight unless otherwise specified.

(1) Normal adhesive strength (evaluation method in Example 1)
An adhesive sheet having a width of 20 mm and a length of 75 mm was used as an evaluation sample. The separator is peeled from the pressure-sensitive adhesive sheet, and the pressure-sensitive tape (product name “NO.31D”, manufactured by Nitto Denko Corporation) is lined on the second pressure-sensitive adhesive layer side, and the first pressure-sensitive adhesive layer is used as an adherend. It stuck on the SUS304BA board (2 kg roller 1 reciprocation). The sample for evaluation stuck to the adherend was left in an environment at 23 ° C. for 30 minutes. Then, the normal pressure-sensitive adhesive force (unit: N / 20 mm) of the first pressure-sensitive adhesive layer to the SUS304BA plate is peeled off at a tensile speed of 300 mm / min in a 180 ° peeling direction using a tensile tester. Was measured.
Similarly, the normal-state adhesive force (unit: N / 20mm) with respect to the SUS304BA board of a 2nd adhesive layer was measured.
(Evaluation methods in Examples 2 to 4 and Comparative Examples 1 to 4)
An adhesive sheet having a width of 20 mm and a length of 75 mm was used as an evaluation sample. The separator is peeled off from the pressure-sensitive adhesive sheet, pressure-sensitive tape (product name “NO.31D” manufactured by Nitto Denko Corporation) is lined on one side of the pressure-sensitive adhesive sheet, and the other side of the pressure-sensitive adhesive sheet is a SUS304BA plate as an adherend. (2 kg roller 1 reciprocation). The sample for evaluation stuck to the adherend was left in an environment at 23 ° C. for 30 minutes. Then, the normal-state adhesive force (unit: N / 20mm) with respect to a SUS304BA board was measured by peeling an adhesive sheet in a 180 degree peeling direction using a tensile tester at a tensile speed of 300 mm / min. By the same method, the normal pressure-sensitive adhesive force on both sides of the pressure-sensitive adhesive sheet was measured.

(2) Adhesive strength (terminal peeling)
(Evaluation method in Example 1)
After separating the separator from the 10 mm wide x 50 mm long pressure sensitive adhesive sheet, the second pressure sensitive adhesive layer side is attached to a commercially available wallpaper (fleece wallpaper (nonwoven fabric)), and the pressure sensitive adhesive sheet is placed on the first pressure sensitive adhesive layer side. One side of the SUS304BA plate was stuck so that the longitudinal direction of the SUS304BA plate protruded by 20 mm, and the protruding adhesive sheet 20 mm was folded and stuck to the other surface side of the SUS304BA plate. After 50 ° C x 24 hours, check whether the adhesive sheet is peeled off on the other side of the SUS304BA plate, and if it is peeled off, the height from the SUS304BA plate to the edge of the adhesive sheet is lifted The distance. Note that the adhesive strength of the first pressure-sensitive adhesive layer does not decrease at “50 ° C. × 24 hours”.
(Evaluation methods in Examples 2 to 4 and Comparative Examples 1 to 4)
After peeling the separator from the adhesive sheet having a width of 10 mm x 50 mm, one side of the adhesive sheet was stuck to a commercially available wallpaper, and the longitudinal direction of the adhesive sheet protruded 10 mm from the other side of the adhesive sheet. The pressure-sensitive adhesive sheet 10 mm sticked to one surface of the plate was folded and attached to the other surface side of the SUS304BA plate. After 50 ° C x 24 hours, check whether the adhesive sheet is peeled off on the other side of the SUS304BA plate, and if it is peeled off, the height from the SUS304BA plate to the edge of the adhesive sheet is lifted The distance.

(3) Peelability 1 (Adhesive strength after applying external stimulus)
An adhesive sheet having a width of 20 mm and a length of 75 mm was used as an evaluation sample. Heat (125 ° C. × 30 seconds) as an external stimulus was applied to the pressure-sensitive adhesive sheet. Thereafter, the separator is peeled off from the pressure-sensitive adhesive sheet, pressure-sensitive tape (product name “NO.31D” manufactured by Nitto Denko Corporation) is lined on one side of the pressure-sensitive adhesive sheet, and the other side of the pressure-sensitive adhesive sheet is used as an adherend. It stuck on the SUS304BA board (2 kg roller 1 reciprocation). The sample for evaluation stuck to the adherend was left in an environment at 23 ° C. for 30 minutes. Then, the adhesive strength (unit: N / 20 mm) after applying external stimulus to the SUS304BA plate was measured by peeling the adhesive sheet in a 180 ° peeling direction using a tensile tester at a tensile speed of 300 mm / min.
In addition, about Example 1, the adhesive force after the said external stimulus provision was measured about the 1st adhesive layer.

(4) Peelability 2 (Adherent tearability)
(Evaluation method in Example 1)
After separating the separator from the adhesive sheet 50 mm wide x 100 mm long, the first adhesive layer side is attached to the SUS304BA board, and the commercially available wallpaper (fleece wallpaper (nonwoven fabric)) is applied to the second adhesive layer side. Sticked. After 40 ° C. × 24 hours, heat (130 ° C. × 1 minute) as an external stimulus was applied using a hot plate. After that, the commercially available wallpaper is peeled off from the SUS304BA board, and the adhesive residue on the SUS304BA board (in Table 1, no adhesive residue is indicated as “O” and “Yes” is indicated), and the load when peeling (in Table 1, the size is described) ) And fracture morphology.
In addition, about the destruction mode, in Table 1, when the commercially available wallpaper and the pressure-sensitive adhesive sheet can be peeled integrally as a laminate, A, when the adherend peels on both sides of the pressure-sensitive adhesive sheet (ie, from the SUS304BA board, The case where the pressure-sensitive adhesive sheet and the commercially available wallpaper are peeled off separately) is B, and the case where the pressure-sensitive adhesive sheet is peeled in other forms is C.
(Evaluation methods in Examples 2 to 4 and Comparative Example 1)
After separating the separator from the adhesive sheet 50 mm wide x 100 mm long, one side of the adhesive sheet is attached to the SUS304BA board, and a commercially available wallpaper (fleece wallpaper (nonwoven fabric)) is attached to the other side of the adhesive sheet did. After 40 ° C. × 24 hours, heat (130 ° C. × 1 minute) as an external stimulus was applied using a hot plate. Then, the commercially available wallpaper was peeled from the SUS304BA board, the adhesive residue on the SUS304BA board, the load at the time of peeling, and the peeling mode were evaluated. The evaluation criteria in Table 1 are as described above.
(Evaluation method in Comparative Examples 2 to 4)
After separating the separator from the adhesive sheet having a width of 50 mm and a length of 100 mm, one side of the adhesive sheet was attached to a SUS304BA plate, and a commercially available wallpaper was attached to the other side of the adhesive sheet. Then, the commercially available wallpaper was peeled from the SUS304BA board, the adhesive residue on the SUS304BA board, the load at the time of peeling, and the peeling mode were evaluated. The evaluation criteria in Table 1 are as described above.

(5) Flame retardancy (UL94)
Evaluation was performed according to UL94 (20 mm vertical combustion test) described in ASTM D3801.
After separating the separator from the adhesive sheet having a width of 12.7 mm and a length of 127 mm, one end in the length direction of the adhesive sheet was fixed with a clamp and suspended. In the air, a propane gas burner flame (height: 20 mm) was indirectly flamed for 10 seconds at the other end of the pressure-sensitive adhesive sheet. The flame contact for 10 seconds was performed twice, and this total combustion time was defined as the combustion time of one sample.
The test was performed on five samples and the total burning time was measured.
Moreover, the presence or absence of the combustion to a clamp, the presence or absence of the cotton ignition (drip) by a dripping material, and the sum total of the combustion time of each sample, and the red hot time (glowing time) were confirmed.
In addition, the burning time of one sample is 10 seconds or less, the total burning time of five samples is 50 seconds or less, the sum of the burning time and the glowing time of one sample is 30 seconds or less, and the combustion up to the clamp In the case where there is no cotton ignition due to the dropped material, the pressure-sensitive adhesive sheet is judged to have flame retardancy equivalent to V-0 in a test according to the UL94 vertical combustion test. When all the pressure-sensitive adhesive sheets are burned out, “Burn out” is described in Table 1.

(6) Flame retardancy (FAR 25.853)
Evaluation was performed according to the vertical combustion test described in FAR 25.853.
After the separator was peeled from the adhesive sheet of 75 mm × length 305 mm, one end in the length direction of the adhesive sheet was fixed with a clamp and suspended. In the atmosphere, an upper 19 mm flame of a propane gas burner flame (height: 39 mm) was indirectly flamed on the other end of the pressure-sensitive adhesive sheet for 12 seconds. After completion of flame contact, the time that the adhesive sheet continues to burn (burning time), the height of the adhesive sheet defined by the FAR25.853 standard test (burning distance), and the adhesive sheet falls on the floor and continues to burn. Time (drip time) was evaluated. When the combustion time is 15 seconds or less, the combustion distance is 200 mm or less, and the drip time is within 5 seconds, it is judged that the flame retardant is equivalent to FAR 25.853.

[Production Example 1] Preparation of syrup (I) 11.5 parts by weight of 2-methoxyethyl acrylate (trade name “Aclix C1” manufactured by Toagosei Co., Ltd.), 80 parts by weight of 2-ethylhexyl acrylate, and N-vinylpyrrolidone 7 parts by weight, 1.5 parts by weight of hydroxyethylacrylamide, 0.05 parts by weight of initiator (trade name “Irgacure 184” manufactured by BASF), and initiator (trade name “Irgacure 651” manufactured by BASF) Syrup (I) was prepared by mixing 0.05 part by weight.

[Production Example 2] Preparation of syrup (II) 40.5 parts by weight of 2-ethylhexyl acrylate, 40.5 parts by weight of isostearyl acrylate, 18 parts by weight of N-vinylpyrrolidone, and 1 part by weight of 4-hydroxybutyl acrylate , 0.05 parts by weight of an initiator (BASF, trade name “Irgacure 184”) and 0.05 parts by weight of an initiator (BASF, trade name “Irgacure 651”) are mixed with a syrup (II ) Was prepared.

[Example 1]
(Preparation of UV-curable monomer composition (I))
42 parts by weight of the above syrup (I), 2.1 parts by weight of 2-methoxyethyl acrylate (trade name “Acryx C1” manufactured by Toagosei Co., Ltd.), 14.9 parts by weight of 2-ethylhexyl acrylate, and N-vinyl 1.3 parts by weight of pyrrolidone, 0.3 parts by weight of hydroxyethylacrylamide, 0.003 parts by weight of dipentaerythritol hexaacrylate (manufactured by Nippon Kayaku Co., Ltd., trade name “KAYARAD DPHA”), and surfactant (first An ultraviolet curable monomer composition (I) was prepared by mixing 0.9 part by weight of Kogyo Seiyaku Co., Ltd., trade name “Plisurf A212E”.
(Preparation of first pressure-sensitive adhesive layer-forming composition A)
100 parts by weight of the ultraviolet curable monomer composition (I), 125 parts by weight of a flame retardant (aluminum hydroxide, Showa Denko KK, trade name “Hydylide H42”, average particle size: 1 μm), and flame retardant (water 125 parts by weight of aluminum oxide, manufactured by Showa Denko KK, trade name “Hijiride H10”, average particle size: 55 μm, and thermally expandable microspheres (manufactured by Matsumoto Yushi Seiyaku Co., Ltd., trade name “Matsumoto Microsphere F-50”) The first pressure-sensitive adhesive layer-forming composition A was prepared by mixing 20 parts by weight with a foaming temperature of 130 ° C. and an average particle size of about 14 μm.

(Preparation of UV-curable monomer composition (II))
42 parts by weight of the syrup (II), 18.1 parts by weight of 2-ethylhexyl acrylate, 0.012 parts by weight of dipentaerythritol hexaacrylate (manufactured by Nippon Kayaku Co., Ltd., trade name “KAYARAD DPHA”), and surfactant (Daiichi Kogyo Seiyaku Co., Ltd., trade name “Plisurf A212E”) 0.9 part by weight was mixed to prepare an ultraviolet curable monomer composition (II).
(Preparation of second adhesive layer forming composition B)
100 parts by weight of an ultraviolet curable monomer composition (II), 125 parts by weight of a flame retardant (aluminum hydroxide, Showa Denko KK, trade name “Hydylide H42”, average particle size: 1 μm), and a flame retardant (hydroxylation) A second pressure-sensitive adhesive layer-forming composition B was prepared by mixing 125 parts by weight of aluminum, manufactured by Showa Denko KK, trade name “Hydylide H10”, average particle size: 55 μm).

(Preparation of adhesive sheet)
On the PET separator, the first pressure-sensitive adhesive layer-forming composition A was applied to form a first coating layer.
On another PET separator, the 2nd adhesive layer formation composition B was apply | coated and the 2nd application layer was formed.
The separator is laminated so that the first coating layer and the second coating layer are in contact with each other, and a laminate composed of PET separator / first coating layer / second coating layer / another PET separator is formed. Obtained. As the PET separator, a trade name “MRF” manufactured by Mitsubishi Polyester Film Co., Ltd. was used.
The first coating layer and the second coating layer are irradiated with ultraviolet rays (5 mW / cm ² × 3 minutes) from both sides of the laminate through the PET separator, and the coating layer is cured to produce the first adhesive layer. An adhesive sheet having an adhesive layer (thickness: 100 μm) and a second adhesive layer (thickness: 100 μm) was obtained. As a source of ultraviolet rays, the product name “Black Light” manufactured by Toshiba is used, and the UV illuminance is a UV checker manufactured by Topcon (product name “UVR-T1”, measured at a maximum sensitivity of 350 n). It was.
The obtained pressure-sensitive adhesive sheet was subjected to the above evaluations (1) to (6). The results are shown in Table 1.
The normal pressure-sensitive adhesive strength of the second pressure-sensitive adhesive layer was 25.6 N / 20 mm.

[Example 2]
Using the first pressure-sensitive adhesive layer forming composition A prepared in Example 1, a single-layer pressure-sensitive adhesive layer was formed. Specifically, on the PET separator, the first pressure-sensitive adhesive layer-forming composition A prepared in Example 1 was applied to form a coating layer, and ultraviolet rays (5 mW / cm ² × 3 minutes were formed on the coating layer. ) Was cured to obtain a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer (thickness: 200 μm). The obtained pressure-sensitive adhesive sheet was subjected to the above evaluations (1) to (6). The results are shown in Table 1.

[Example 3]
In the same manner as in Example 1, an ultraviolet curable monomer composition (II) was prepared.
100 parts by weight of an ultraviolet curable monomer composition (II), 250 parts of a flame retardant (aluminum hydroxide, manufactured by Nippon Light Metal Co., Ltd., trade name “B103”, average particle size: 7 μm), and thermally expandable microspheres (Matsumoto Yushi) A pressure-sensitive adhesive layer-forming composition C was prepared by mixing 10 parts by weight of a product name “Matsumoto Microsphere F-48D ^* ” manufactured by Pharmaceutical Co., Ltd., foaming temperature: 110 ° C., average particle size: about 13 μm). .
Using this pressure-sensitive adhesive layer forming composition C, a single-layer pressure-sensitive adhesive layer was formed. Specifically, the pressure-sensitive adhesive layer forming composition C is coated on a PET separator to form a coating layer, and the coating layer is irradiated with ultraviolet rays (5 mW / cm ² × 3 minutes). Was cured to obtain a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer (thickness: 100 μm). The obtained pressure-sensitive adhesive sheet was subjected to the above evaluations (1) to (6). The results are shown in Table 1.

[Example 4]
In the same manner as in Example 1, an ultraviolet curable monomer composition (II) was prepared.
100 parts by weight of an ultraviolet curable monomer composition (II), 250 parts of a flame retardant (aluminum hydroxide, manufactured by Nippon Light Metal Co., Ltd., trade name “B103”, average particle size: 7 μm), and thermally expandable microspheres (Matsumoto Yushi) A pressure-sensitive adhesive layer forming composition D was prepared by mixing 20 parts by weight of a pharmaceutical product, “Matsumoto Microsphere F-48D ^* ”, foaming temperature: 110 ° C., average particle size: about 13 μm. .
A pressure-sensitive adhesive layer having a single layer structure was formed using the pressure-sensitive adhesive layer forming composition D. Specifically, an adhesive layer forming composition D is applied onto a PET separator to form a coating layer, and the coating layer is irradiated with ultraviolet rays (5 mW / cm ² × 3 minutes) to cure the coating layer. Thus, a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer (thickness: 100 μm) was obtained. The obtained pressure-sensitive adhesive sheet was subjected to the above evaluations (1) to (6). The results are shown in Table 1.

[Comparative Example 1]
100 parts by weight of the ultraviolet curable monomer composition (I) prepared in Example 1 and thermally expandable microspheres (manufactured by Matsumoto Yushi Seiyaku Co., Ltd., trade name “Matsumoto Microsphere F-50”, foaming temperature: 130 ° C., 20 parts by weight of (average particle diameter: about 14 μm) was mixed to prepare an adhesive layer forming composition e.
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 2 except that this pressure-sensitive adhesive layer-forming composition e was used in place of the first pressure-sensitive adhesive layer-forming composition A. The obtained pressure-sensitive adhesive sheet was subjected to the above evaluations (1) to (6). The results are shown in Table 1.

[Comparative Example 2]
The second adhesive layer-forming composition B prepared in Example 1 is a polyethylene terephthalate release liner (Mitsubishi Chemical Polyester Film Co., Ltd., trade name “Diafoil MRF38”) having a release treatment on one side. The composition layer was applied to the release-treated surface. On this composition layer, the same release liner as described above was laminated such that the release treatment surface was on the composition layer side. Next, ultraviolet rays with an illuminance of about 5 mW / cm ² are irradiated from both sides of the laminate for 3 minutes to cure the composition layer to form an adhesive layer having a thickness of 94 μm. Release liner / adhesive layer / release liner A laminate having the following structure was obtained. Similarly, another laminate was produced. Next, the release liner on one side of the pressure-sensitive adhesive layer was peeled off for each of the two laminates, and the surface of the pressure-sensitive adhesive layer and a polyethylene terephthalate film (base material) (trade name “Lumirror S10 # 12”, manufactured by Toray Industries, Inc. And a double-sided pressure-sensitive adhesive sheet with a base material having a configuration of release liner / adhesive layer (thickness 94 μm) / base material (thickness 12 μm) / adhesive layer (thickness 94 μm) / release liner. . The obtained pressure-sensitive adhesive sheet was subjected to the above evaluations (1) to (6). The results are shown in Table 1.

[Comparative Example 3]
The second adhesive layer-forming composition B prepared in Example 1 is a polyethylene terephthalate release liner (Mitsubishi Chemical Polyester Film Co., Ltd., trade name “Diafoil MRF38”) having a release treatment on one side. The composition was coated on the release treatment surface to provide a composition layer, and a release liner similar to the above was laminated on the composition layer so that the release treatment surface was on the composition layer side. Next, ultraviolet rays with an illuminance of about 5 mW / cm ² are irradiated from both sides of the laminate for 3 minutes to cure the composition layer to form an adhesive layer having a thickness of 200 μm, and release liner / adhesive layer / release liner A laminate having the following structure was obtained. The obtained pressure-sensitive adhesive sheet was subjected to the above evaluations (1) to (6). The results are shown in Table 1.

DESCRIPTION OF SYMBOLS 10 Adhesive layer 11 1st adhesive layer 12 2nd adhesive layer 100,200 Adhesive sheet

Claims (13)

1. A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer having a surface A whose adhesive force is reduced by external stimulation,
   The adhesive strength X _A1 to SUS304BA at 23 ° C. of the surface A before applying the external stimulus is 10 N / 20 mm or more,
   By applying the external stimulus, the adhesive force X _A2 of the surface A to SUS304BA at 23 ° C. is less than 10 N / 20 mm,
   Has flame retardancy equivalent to V-0 in a test according to UL94 vertical combustion test,
   Adhesive sheet.
2. The pressure-sensitive adhesive layer is composed of a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer,
   The first pressure-sensitive adhesive layer has the surface A whose adhesive force is reduced by an external stimulus,
   In a test according to FAR 25.853, the combustion time is 12 seconds or less, the combustion distance is 200 mm or less, and the drip time is within 5 seconds.
   The pressure-sensitive adhesive sheet according to claim 1.
3. The pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive layer contains a flame retardant.
4. The pressure-sensitive adhesive sheet according to claim 2, wherein the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer contain a flame retardant.
5. 90% or less of the adhesive force X _A2 of SUS304BA at 23 ° C. of the surface A after applying the external stimulus is less than the adhesive force X _A1 of SUS304BA at 23 ° C. of the surface A before applying the external stimulus Is,
   The pressure-sensitive adhesive sheet according to claim 1.
6. The pressure-sensitive adhesive sheet according to any one of claims 1 to 5, wherein the external stimulus is heating, cooling, or active energy ray irradiation.
7. The pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive layer comprises thermally expandable microspheres.
8. The pressure-sensitive adhesive sheet according to claim 7, wherein the pressure-sensitive adhesive layer contains an acrylic pressure-sensitive adhesive.
9. The pressure-sensitive adhesive sheet according to claim 7 or 8, wherein the pressure-sensitive adhesive layer is a layer obtained by curing the active energy ray-curable monomer composition.
10. The pressure-sensitive adhesive sheet according to claim 2, wherein the first pressure-sensitive adhesive layer contains thermally expandable microspheres.
11. The pressure-sensitive adhesive sheet according to claim 10, wherein the first pressure-sensitive adhesive layer contains an acrylic pressure-sensitive adhesive.
12. The pressure-sensitive adhesive sheet according to claim 10 or 11, wherein the first pressure-sensitive adhesive layer is a layer obtained by curing the active energy ray-curable monomer composition.
13. The pressure-sensitive adhesive sheet according to any one of claims 1 to 12, wherein the flame retardant is a metal hydroxide.
    
    
    

Images