Adhesive sheet

Abstract

Provided is an adhesive sheet including an adhesive layer. The adhesive layer includes a polymerized product of a composition including: (A) at least one of a monomer having an aromatic ring and an oligomer including a repeating unit having an aromatic ring, and (B) a monomer having a hydroxyl group or a carboxyl group. The glass transition temperature Tg of the composition of the monomer components constituting the adhesive layer is A Above -3°C and below 40°C.

Description

Technical Field

[0001] The present invention relates to an adhesive sheet. Background Art

[0002] PSA sheets are used to adhere adherends firmly to adherends, fix articles to adherends, reinforce adherends, etc. PSA sheets that exhibit high adhesive strength from the initial stage of attachment have been used for such purposes.

[0003] In addition, recently, a kind of adhesive sheet has been proposed, which can show low adhesive force at the initial stage of being attached to the adherend, and then greatly increase the adhesive force (Japanese Patent Gazette No. 6223836, Japanese Patent Gazette No. 5890596, Japanese Patent Gazette No. 5951153). When using an adhesive sheet with such characteristics, it can exert re-pasteability (reprocessability) useful for suppressing the reduction of the yield rate caused by the wrong pasting and pasting damage of the adhesive sheet before the adhesive force increases, and exert strong adhesiveness suitable for the original purpose of use of the adhesive sheet after the adhesive force increases. Summary of the invention

[0004] Problem that the invention aims to solve

[0005] The present inventors have conducted further research to provide an adhesive sheet that can show low adhesive force at the initial stage of attachment and then significantly increase the adhesive force as described above. As a result, it was found that the use of monomers and / or oligomers with specific structures is effective to solve the above problems, thereby completing the present invention.

[0006] Solutions for solving problems

[0007] According to the specification, an adhesive sheet including an adhesive layer is provided. The adhesive layer includes a polymerized product of a composition, the composition including: (A) at least one of a monomer having an aromatic ring and an oligomer including a repeating unit having an aromatic ring, and (B) a monomer having a hydroxyl group or a carboxyl group. The adhesive layer preferably has a glass transition temperature Tg of 100° based on the composition of the monomer components constituting the adhesive layer. A It is higher than -3°C and not higher than 40°C. When the pressure-sensitive adhesive layer is used, a pressure-sensitive adhesive sheet can be preferably realized which exhibits low pressure-sensitive adhesive strength at the initial stage of attachment and can then significantly increase pressure-sensitive adhesive strength.

[0008] It should be noted that, hereinafter, a monomer having an aromatic ring is sometimes described as an "aromatic ring-containing monomer", and similarly, a monomer having a hydroxyl group is sometimes described as a "hydroxyl group-containing monomer", and a monomer having a carboxyl group is sometimes described as a "carboxyl group-containing monomer", etc. In addition, hereinafter, a repeating unit having an aromatic ring is sometimes described as an "aromatic ring-containing repeating unit", and an oligomer containing an aromatic ring-containing repeating unit is sometimes described as an "oligomer AR".

[0009] In some embodiments, the composition comprises at least the aromatic ring-containing monomer as the (A). The composition comprising the aromatic ring-containing monomer and the (B) is polymerized to form a polymer, which contains an aromatic ring-containing repeating unit and at least one of a hydroxyl-containing repeating unit and a carboxyl-containing repeating unit. When an adhesive layer comprising such a polymer is used, an adhesive sheet that exhibits low adhesive force at the initial stage of attachment and then greatly increases adhesive force can be appropriately realized.

[0010] As the aromatic ring-containing monomer (A), for example, at least one selected from the group consisting of benzyl acrylate, ethoxylated phenylphenol acrylate, biphenyl methyl acrylate, and phenoxybenzyl acrylate can be preferably used. When the aromatic ring-containing monomer is used, it is advantageous from the viewpoint of adjusting the adhesive properties and / or optical properties of the adhesive sheet.

[0011] In some embodiments, the monomer components constituting the adhesive layer may be 55% by weight or more of monomers having aromatic rings. When using such an adhesive layer containing a large number of repeating units derived from aromatic ring-containing monomers, an adhesive sheet that exhibits low adhesive force at the initial stage of attachment and then significantly increases adhesive force can be appropriately realized.

[0012] In some aspects, the composition preferably contains more than 50% by weight of acrylic monomers among monomers contained in the composition. This is advantageous from the viewpoint of ease of adjustment of the polymerization reactivity and adhesive properties of the composition, for example.

[0013] In some embodiments, the composition comprises at least an oligomer (oligomer AR) comprising a repeating unit having an aromatic ring as (A). Thus, at least one of the effects of suppressing the initial adhesive force and improving the subsequent adhesive force rise can be achieved. As the oligomer AR, for example, a styrene oligomer can be preferably used.

[0014] In some embodiments, the composition further comprises (C) at least one kind of (meth)acrylic acid alkyl ester having a homopolymer glass transition temperature of -40°C or less. When (C) is used, the glass transition temperature Tg can be appropriately adjusted. A Adjustment of, adjustment of bonding properties.

[0015] For some preferred adhesive sheets, the adhesive force N1 (hereinafter also referred to as "initial adhesive force") after being attached to a stainless steel plate and heated at 23°C for 30 minutes is less than 5N / 20mm, and the adhesive force N2 (hereinafter also referred to as "adhesive force after heating") after being attached to a stainless steel plate and heated at 80°C for 5 minutes and then at 23°C for 30 minutes is more than twice the above-mentioned adhesive force N1. According to the technology disclosed herein, an adhesive sheet having a low initial adhesive force at the time of attachment and a greatly increased adhesive force by heating for a short time can be provided.

[0016] It should be noted that solutions formed by appropriate combinations of the above-mentioned elements are also included in the scope of protection claimed for patent protection through this patent application. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a cross-sectional view schematically showing the structure of a pressure-sensitive adhesive sheet according to one embodiment.

[0018] Figure 2 This is a cross-sectional view schematically showing the structure of a pressure-sensitive adhesive sheet according to another embodiment.

[0019] Figure 3 This is a cross-sectional view schematically showing the structure of a pressure-sensitive adhesive sheet according to still another embodiment.

[0020] Description of Reference Numerals

[0021] 1, 2, 3 adhesive sheets

[0022] 10 Support substrate

[0023] 10A Side 1

[0024] 10B Side 2

[0025] 21 Adhesive layer (first adhesive layer)

[0026] 21A Adhesive surface (first adhesive surface)

[0027] 21B Adhesive surface (second adhesive surface)

[0028] 22 Adhesive layer (second adhesive layer)

[0029] 22A Adhesive surface (second adhesive surface)

[0030] 31, 32 Release liner

[0031] 100, 200, 300 Adhesive sheet with release liner (adhesive product) DETAILED DESCRIPTION

[0032] The following describes suitable embodiments of the present invention. For matters necessary for implementing the present invention other than matters specifically mentioned in this specification, those skilled in the art can understand based on the teachings related to the implementation of the invention recorded in this specification and the technical common sense at the time of application. The present invention can be implemented based on the contents disclosed in this specification and the technical common sense in the art.

[0033] It should be noted that, in the following drawings, the same symbols are sometimes used to describe the components and parts that play the same role, and the repeated description is sometimes omitted or simplified. In addition, the embodiments recorded in the drawings are schematically illustrated for the purpose of clearly describing the present invention, and do not necessarily accurately represent the size and scale of the actual product provided.

[0034] In this specification, "acrylic monomer" refers to a monomer having at least one (meth)acryloyl group in one molecule. Here, "(meth)acryloyl" means including acryloyl and methacryloyl. Therefore, the concept of acrylic monomers described here can include both monomers having acryloyl groups (acrylic monomers) and monomers having methacryloyl groups (methacrylic monomers). Similarly, in this specification, "(meth)acrylic acid" means including acrylic acid and methacrylic acid, and "(meth)acrylate" means including acrylate and methacrylate.

[0035] In addition, the "monomer components constituting the adhesive layer" in this specification refer to monomers corresponding to monomer units contained in all polymers contained in the adhesive layer, regardless of whether they are used in the form of monomers as starting materials or in the form of preformed polymers (which may be oligomers).

[0036] <Structural Example of Adhesive Sheet>

[0037] The adhesive sheet disclosed herein is composed of an adhesive layer. The adhesive sheet disclosed herein may be in the form of an adhesive sheet with a substrate in which the adhesive layer is laminated on one or both sides of a supporting substrate, or in the form of an adhesive sheet without a supporting substrate. Hereinafter, the supporting substrate may also be referred to as a "substrate".

[0038] Figure 1 The structure of an adhesive sheet according to one embodiment is schematically shown in FIG. The adhesive sheet 1 is formed in the form of a single-sided adhesive sheet with a substrate, which includes a sheet-shaped supporting substrate 10 having a first surface 10A and a second surface 10B, and an adhesive layer 21 provided on the first surface 10A side. The adhesive layer 21 is fixed to the first surface 10A side of the supporting substrate 10. The adhesive sheet 1 is used by attaching the adhesive layer 21 to an adherend. The adhesive sheet 1 before use (i.e., before being attached to an adherend) is as follows: Figure 1As shown, it can be a constituent element of the adhesive sheet 100 with a release liner in a form in which the surface (adhesive surface) 21A of the adhesive layer 21 is in contact with a release liner 31 which becomes a releasable surface (release surface) on at least one side opposite to the adhesive layer 21. As the release liner 31, for example, a release liner which is constituted in a manner that a release layer based on a release treatment agent is provided on a single side of a sheet-like substrate (liner substrate) so that the single side becomes a release surface can be preferably used. Alternatively, it can also be in the form of omitting the release liner 31, using the supporting substrate 10 whose second side 10B becomes the release surface, and winding the adhesive sheet 1, thereby making the adhesive surface 21A and the second side 10B of the supporting substrate 10 abut against each other (roll form). When the adhesive sheet 1 is attached to an adherend, the release liner 31 or the second side 10B of the supporting substrate 10 is peeled off from the adhesive surface 21A, and the exposed adhesive surface 21A is pressed against the adherend.

[0039] Figure 2 The structure of an adhesive sheet of another embodiment is schematically shown in the figure. The adhesive sheet 2 is constituted in the form of a double-sided adhesive sheet with a substrate, and the double-sided adhesive sheet with a substrate comprises: a sheet-shaped supporting substrate 10 having a first surface 10A and a second surface 10B, an adhesive layer 21 arranged on the first surface 10A side, and an adhesive layer 22 arranged on the second surface 10B side. The adhesive layer (first adhesive layer) 21 is fixed to the first surface 10A of the supporting substrate 10, and the adhesive layer (second adhesive layer) 22 is fixed to the second surface 10B of the supporting substrate 10. The adhesive sheet 2 is used by attaching the adhesive layers 21 and 22 to different parts of the adherend. The parts to which the adhesive layers 21 and 22 are to be attached can be respective parts of different components, or different parts within a single component. The adhesive sheet 2 before use is as shown in FIG. Figure 2 As shown, the component of the adhesive sheet 200 with release liner can be a morphology in which the surface (first adhesive surface) 21A of the adhesive layer 21 and the surface (second adhesive surface) 22A of the adhesive layer 22 are in contact with release liners 31 and 32, which are release surfaces on at least one side opposite to the adhesive layers 21 and 22. As the release liners 31 and 32, for example, it is preferable to use a release liner that is formed in a manner that a release layer based on a release treatment agent is provided on one side of a sheet-like substrate (liner substrate) so that the single side becomes a release surface. Alternatively, the following adhesive sheet with release liner can be formed: the release liner 32 is omitted, and a release liner 31 with both sides as release surfaces is used, which is overlapped with the adhesive sheet 2 and wound into a spiral shape, thereby the second adhesive surface 22A is in contact with the back side of the release liner 31 (rolled form).

[0040] Figure 3The structure of another embodiment of the adhesive sheet is schematically shown in FIG. The adhesive sheet 3 is formed in the form of a double-sided adhesive sheet without a substrate formed by an adhesive layer 21. The adhesive sheet 3 is used by attaching a first adhesive surface 21A formed by one surface (first surface) of the adhesive layer 21 and a second adhesive surface 21B formed by the other surface (second surface) of the adhesive layer 21 to different parts of the adherend. The adhesive sheet 3 before use is as shown in FIG. Figure 3 As shown, the first adhesive surface 21A and the second adhesive surface 21B may be in contact with release liners 31 and 32, which are release surfaces on at least one side opposite to the adhesive layer 21. Alternatively, the release liner 32 may be omitted, and a release liner 31 with both sides being release surfaces may be used, overlapped with the adhesive sheet 3, and wound into a spiral shape, so that the second adhesive surface 21B is in contact with the back side of the release liner 31 (rolled shape).

[0041] It should be noted that the concept of the adhesive sheet mentioned here may include objects called adhesive tapes, adhesive films, adhesive labels, etc. The adhesive sheet may be in the form of a roll, a sheet, or may be cut, punched, etc. into a suitable shape according to the purpose and the mode of use. The adhesive layer in the technology disclosed herein is typically formed continuously, but is not limited to this, and may be formed into a regular or irregular pattern such as dots or stripes, for example.

[0042] The adhesive layer constituting the adhesive sheet disclosed herein comprises a polymerized product of a composition comprising: (A) at least one of an aromatic ring-containing monomer and an oligomer containing an aromatic ring repeating unit (hereinafter, also referred to as "component (A)"); and (B) a monomer having a hydroxyl group or a carboxyl group (hereinafter, also referred to as "component (B)"). The adhesive layer comprising such a polymerized product is suitable for realizing an adhesive sheet that can exhibit low adhesive force at the initial stage of attachment and then significantly increase the adhesive force.

[0043] <Ingredients (A)>

[0044] (Containing aromatic ring monomers)

[0045] The aromatic ring-containing monomer as component (A) is a compound containing an aromatic ring in its structure and containing an ethylenically unsaturated group such as a (meth)acryloyl group, a vinyl group, an allyl group, etc. The aromatic ring-containing monomer can be used alone or in combination of two or more. The number of aromatic rings contained in one molecule of the aromatic ring-containing monomer can be one or more (typically 2 to 5, for example 2 to 4). The number of ethylenically unsaturated groups contained in one molecule of the aromatic ring-containing monomer is typically one.

[0046] The aromatic ring in the aromatic ring-containing monomer may be a benzene ring; a condensed ring of a naphthalene ring, an indene ring, an azulene ring, an anthracene ring, a phenanthrene ring; or a carbon ring, or a heterocyclic ring such as a pyridine ring, a pyrimidine ring, a pyrazine ring, a pyrrole ring, an imidazole ring, an oxazole ring, or a thiazole ring. When the aromatic ring-containing monomer contains two or more benzene rings, the benzene rings may form a biphenyl skeleton or a fluorene skeleton.

[0047] The above-mentioned aromatic ring may have one or more substituents on the ring-constituting atoms, or may not have substituents. In the case of having a substituent, examples of the substituent include alkyl, alkoxy, aryloxy, hydroxyl, and halogen atoms (fluorine atoms, chlorine atoms, bromine atoms, etc.), but are not limited to these. In the substituent containing carbon atoms, the number of carbon atoms contained in the substituent is preferably 1 to 4, more preferably 1 to 3, for example, 1 or 2. In some embodiments, the above-mentioned aromatic ring may be an aromatic ring that has no substituent on the ring-constituting atoms, or has one or more substituents selected from the group consisting of alkyl and alkoxy.

[0048] The aromatic ring and the ethylenically unsaturated group may be directly bonded or bonded via a connecting group. The connecting group may be, for example, a group containing one or more structures selected from an alkylene group, an oxyalkylene group, a poly(oxyalkylene) group, a phenyl group, an alkylphenyl group, an alkoxyphenyl group, a group in which one or more hydrogen atoms in these groups are substituted with a hydroxyl group (e.g., a hydroxyalkylene group), an oxy group (-O-), etc. In some embodiments, an aromatic ring-containing monomer having a structure in which an aromatic ring and an ethylenically unsaturated group are directly bonded or bonded via a connecting group selected from the group consisting of an alkylene group, an oxyalkylene group, and a poly(oxyalkylene) group may be preferably used. The number of carbon atoms in the alkylene group and the oxyalkylene group is preferably 1 to 4, more preferably 1 to 3, for example, 1 or 2. The number of repetitions of the oxyalkylene unit in the poly(oxyalkylene) group may be, for example, 2 to 3.

[0049] Examples of aromatic ring-containing monomers that can be preferably used include aromatic ring-containing (meth)acrylates and aromatic ring-containing vinyl compounds. Each of the aromatic ring-containing (meth)acrylates and aromatic ring-containing vinyl compounds can be used alone or in combination of two or more. One or two or more aromatic ring-containing (meth)acrylates and one or two or more aromatic ring-containing vinyl compounds can also be used in combination.

[0050] Specific examples of the benzene ring-containing (meth)acrylate include benzyl (meth)acrylate, methoxybenzyl (meth)acrylate, phenoxybenzyl (meth)acrylate (e.g., m-phenoxybenzyl (meth)acrylate), phenyl (meth)acrylate, ethoxylated phenol (meth)acrylate, ethoxylated nonylphenol (meth)acrylate, ethoxylated cresol (meth)acrylate, phenoxypropyl (meth)acrylate, phenoxybutyl (meth)acrylate, cresol (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, chlorobenzyl (meth)acrylate, etc. These are examples of benzene ring-containing (meth)acrylates that do not contain a biphenyl skeleton or a fluorene skeleton.

[0051] It should be noted that the "ethoxylation" in the above-mentioned ethoxylated phenol (meth)acrylate means that an oxyethylene chain exists between the phenoxy group and the (meth)acryloyl group. The number of repetitions of the oxyethylene unit in the above-mentioned oxyethylene chain is typically 1 to 4, preferably 1 to 3, more preferably 1 to 2, for example 1. The same applies to the ethoxylation in other aromatic ring-containing (meth)acrylates disclosed herein.

[0052] On the other hand, specific examples of (meth)acrylates containing a biphenyl skeleton among the benzene ring-containing (meth)acrylates include phenylphenol (meth)acrylate, ethoxylated phenylphenol (meth)acrylate and other phenylphenol (meth)acrylates; biphenyl methyl (meth)acrylate; etc. The concept of the ethoxylated phenylphenol (meth)acrylate includes phenylphenol ethyl (meth)acrylate (i.e., ethoxylated phenylphenol (meth)acrylate having 1 oxyethylene unit) and ethoxylated phenylphenol (meth)acrylate having more than 1 oxyethylene unit (e.g., 2 to 3).

[0053] The (meth)acrylate containing a fluorene skeleton in the benzene ring-containing (meth)acrylate is a compound having a structure in which a (meth)acryloyl group is bonded directly or by means of a connecting group containing an oxyalkylene chain (monooxyalkylene chain or polyoxyalkylene chain) on a fluorene skeleton (which can constitute a bisphenol fluorene skeleton). It is appropriate. As specific examples of (meth)acrylates containing a fluorene skeleton, 9,9-bis(4-hydroxyphenyl)fluorene (meth)acrylate, 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene (meth)acrylate, etc. can be cited. In some embodiments of the technology disclosed herein, from the perspective of improving the adhesion increase, etc., the above-mentioned (meth)acrylate containing a fluorene skeleton may not be used.

[0054] Specific examples of the (meth)acrylate having a naphthalene ring include hydroxyethylated β-naphthol acrylate, 2-naphthylethyl (meth)acrylate, 2-naphthyloxyethyl acrylate, and 2-(4-methoxy-1-naphthyloxy)ethyl (meth)acrylate.

[0055] When an aromatic ring-containing (meth)acrylate is used as component (A), the aromatic ring-containing acrylate can be preferably used in several aspects from the viewpoint of polymerization reactivity, etc. The proportion of the aromatic ring-containing acrylate in the aromatic ring-containing (meth)acrylate used can be, for example, more than 50% by weight, 75% by weight or more, 90% by weight or more, or substantially 100% by weight (typically 99.5 to 100% by weight).

[0056] Examples of aromatic ring-containing vinyl compounds include vinyl compounds containing a carbon ring (typically a benzene ring) or a heterocyclic ring as the aromatic ring. Specific examples of aromatic ring-containing vinyl compounds include aromatic ring-containing vinyl compounds having a vinyl substituent on a carbon ring (typically a benzene ring), such as styrene, α-methylstyrene, vinyltoluene, tert-butylstyrene, and vinylnaphthalene; aromatic ring-containing vinyl compounds having a vinyl substituent on a heterocyclic ring, such as N-vinylpyridine, N-vinylpyrimidine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, and N-vinyloxazole. Preferred aromatic ring-containing vinyl compounds include styrene, α-methylstyrene, and vinyltoluene. Among them, styrene is preferred.

[0057] As the aromatic ring-containing monomer of component (A), an aromatic ring-containing monomer having a homopolymer having a glass transition temperature in the range of -30°C to 65°C can be preferably used. In some embodiments, the glass transition temperature of the homopolymer of the aromatic ring-containing monomer can be, for example, -20°C to -10°C or 0°C, and 60°C to 60°C, 50°C to 40°C or 35°C. When an aromatic ring-containing monomer having a homopolymer having a glass transition temperature between any of the upper and lower limits described above is used, an adhesive sheet having both initial low adhesiveness and subsequent increased adhesiveness can be appropriately realized.

[0058] Preferred examples of aromatic ring-containing monomers that can be used in component (A) include benzyl (meth)acrylate, ethoxylated phenylphenol (meth)acrylates such as o-phenylphenol ethyl (meth)acrylate, biphenyl methyl (meth)acrylates such as p-biphenyl methyl (meth)acrylate, and phenoxybenzyl (meth)acrylates such as m-phenoxybenzyl (meth)acrylate; and aromatic ring-containing vinyl compounds such as styrene.

[0059] In some embodiments in which aromatic ring-containing (meth)acrylate is used as component (A), the proportion of benzene ring-containing (meth)acrylate in the aromatic ring-containing (meth)acrylate may be, for example, greater than 50% by weight, greater than 75% by weight, greater than 90% by weight, or substantially 100% by weight (typically 99.5 to 100% by weight).

[0060] (Oligomer AR)

[0061] In the technology disclosed herein, as the above-mentioned component (A), an oligomer (oligomer AR) containing an aromatic ring repeating unit can be used instead of the aromatic ring-containing monomer as described above or in combination with the aromatic ring-containing monomer. The above-mentioned oligomer AR is a polymer containing monomer units derived from aromatic ring-containing monomers. As the above-mentioned aromatic ring-containing monomer, one monomer selected from the monomers exemplified as aromatic ring-containing monomers that can be used in component (A) can be used alone or in combination of two or more monomers. By using oligomer AR, at least one effect of suppressing the initial adhesive force and improving the subsequent adhesive force rise can be achieved.

[0062] The weight ratio of the aromatic ring-containing monomer in the monomer components constituting the oligomer AR (hereinafter also referred to as the "aromatic ring-containing monomer ratio of the oligomer AR") can be, for example, 30% by weight or more. The above ratio is usually preferably more than 50% by weight, more preferably 70% by weight or more, and further preferably 90% by weight or more. When using an oligomer AR containing a large amount of aromatic ring-containing monomers in this way, there is a tendency for the above-mentioned effects to be more appropriately exerted. In some embodiments, the above ratio can be 95% by weight or more, 98% by weight or more, or substantially 100% by weight (typically 99.5 to 100% by weight).

[0063] As the monomer component constituting the oligomer AR, an aromatic ring-containing vinyl compound can be preferably used. Particularly preferred are aromatic ring-containing vinyl compounds having a vinyl substituent on a carbon ring (typically a benzene ring), among which styrene is preferred. In some embodiments, an oligomer AR in which the proportion of styrene in the monomer component constituting the oligomer AR exceeds 50% by weight can be preferably used. The proportion of the above-mentioned styrene is more preferably 70% by weight or more, further preferably 90% by weight or more, can be 95% by weight or more, can be 98% by weight or more, and can be substantially 100% by weight (typically 99.5 to 100% by weight).

[0064] In some embodiments, as an oligomer AR, one having no ethylenically unsaturated group can be preferably used. The oligomer AR is clearly distinguished from the monomer and the macromonomer. For example, it is preferred to have no ethylenically unsaturated group and an oligomer AR that is non-reactive to hydroxyl and carboxyl groups. Such an oligomer AR typically exists in the adhesive layer in a form that is not chemically bonded to the polymer formed by the monomer contained in the above-mentioned composition. When utilizing an adhesive layer containing an oligomer AR existing in the above-mentioned form, due to the mobility of the oligomer AR in the adhesive layer, there is a tendency to more appropriately exert at least one of the effects of suppressing the initial adhesion and improving the subsequent adhesion rise. As a suitable example of an oligomer AR having no ethylenically unsaturated group and being non-reactive to hydroxyl and carboxyl groups, a styrene oligomer substantially formed by styrene can be cited.

[0065] The weight average molecular weight (Mw) of the oligomer AR is not particularly limited. From the viewpoint of easily exerting the effect brought about by the use of the oligomer AR, the Mw of the oligomer AR is usually preferably about 0.5×10 3 More than and less than about 10×10 3 In some embodiments, the Mw of the oligomer AR may be, for example, 1.0×10 3 Above, it can be 1.5×10 3 Above, it can also be 2.0×10 3 When Mw increases, the cohesiveness of the adhesive layer tends to increase. In some embodiments, the Mw of the oligomer AR may be, for example, 8.0×10 3 Below, can be 6.0×10 3 Below, it can also be 4.0×10 3 When Mw is lower, the adhesive strength-increasing property tends to be improved.

[0066] In this specification, the Mw of a polymer or oligomer can be determined by gel permeation chromatography (GPC) in terms of polystyrene. Specifically, it can be determined by measuring under the following conditions using a GPC measuring apparatus with a trade name of "HLC-8220GPC" (manufactured by Tosoh Corporation).

[0067] [GPC measurement conditions]

[0068] Sample concentration: 0.2 wt% (tetrahydrofuran solution)

[0069] Sample injection volume: 10 μL

[0070] Eluent: Tetrahydrofuran (THF)

[0071] Flow rate: 0.6 mL / min

[0072] Column temperature (measurement temperature): 40°C

[0073] column:

[0074] Sample column: 1 product name "TSKguardcolumn SuperHZ-H" + 2 products brand name "TSKgel SuperHZM-H" (manufactured by Tosoh Corporation)

[0075] Reference column: 1 brand name "TSKgel SuperH-RC" (manufactured by Tosoh Corporation)

[0076] Detector: Differential Refractometer (RI)

[0077] Standard sample: polystyrene

[0078] (Aromatic ring-containing monomer ratio of monomer components)

[0079] The monomer components constituting the adhesive layer include an aromatic ring-containing monomer by using the component (A). The aromatic ring-containing monomer may be an aromatic ring-containing monomer used as the component (A) in the form of a monomer (hereinafter, sometimes referred to as "monomer m AR1 ”), and may be an aromatic ring-containing monomer (hereinafter, sometimes described as “monomer m AR2 ”.).

[0080] The weight ratio of the aromatic ring-containing monomer in the monomer components constituting the adhesive layer (ie, monomer m AR1 And monomer m AR2 The total weight of the monomer components. Hereinafter, it is sometimes recorded as "the aromatic ring-containing monomer ratio of the monomer components". ) is not particularly limited. From the viewpoint of properly exerting the effect of the use of the aromatic ring-containing monomer and / or oligomer AR, it is appropriate that the aromatic ring-containing monomer ratio is usually 10% by weight or more, preferably 25% by weight or more, 35% by weight or more, or 45% by weight or more. In some preferred embodiments, the aromatic ring-containing monomer ratio may be, for example, 55% by weight or more, 60% by weight or more, or 65% by weight or more. In addition, the aromatic ring-containing monomer ratio is typically less than 100% by weight, and it is usually appropriate that it is 95% by weight or less. From the glass transition temperature Tg A From the viewpoint of ease of adjustment and adhesion enhancement, in some embodiments, the aromatic ring-containing monomer ratio is preferably 90 wt % or less, 85 wt % or less, 80 wt % or less, or 75 wt % or less.

[0081] In some preferred embodiments, an aromatic ring-containing monomer and an oligomer AR may be used in combination as component (A). Thus, an adhesive sheet that exhibits low adhesive force at the initial stage of attachment and then greatly increases adhesive force may be appropriately realized. When an aromatic ring-containing monomer and an oligomer AR are used in combination, the monomer m AR2 The amount of monomer m AR1 There is no particular limitation on the usage ratio (weight basis). AR2 / m AR1 ) is set within the range of 0.1 to 10, so that the combined use effect of the aromatic ring-containing monomer and the oligomer AR can be better exerted. The above-mentioned usage ratio can be, for example, 0.3 or more, 0.5 or more, 0.7 or more, 1.0 or more, 1.2 or more, or 1.5 or more. In addition, the above-mentioned usage ratio can be, for example, 7 or less, 5 or less, 3 or less, or 2 or less.

[0082] (High refractive index monomer)

[0083] In some embodiments, at least a portion of the aromatic ring-containing monomer contained in the monomer component constituting the adhesive layer may preferably be a high refractive index monomer. Here, in this specification, "high refractive index monomer" refers to a monomer whose homopolymer has a refractive index of about 1.50 or more (typically 1.51 or more). The refractive index of the homopolymer of the aromatic ring-containing monomer can be measured using a commercially available Abbe refractometer (e.g., model "DR-M2", manufactured by ATAGO).

[0084] As aromatic ring-containing monomers that meet the requirements of the above-mentioned high refractive index monomers, for example, benzyl acrylate, ethoxylated o-phenylphenol acrylate, p-biphenylmethyl acrylate, m-phenoxybenzyl acrylate, styrene, etc. When a high refractive index monomer is included in the monomer components constituting the adhesive layer, it is advantageous for adhesive sheets that can be used, for example, for optical purposes. The proportion of the high refractive index monomer in the aromatic ring-containing monomers contained in the above-mentioned monomer components can be, for example, more than 50% by weight, can be more than 75% by weight, can be more than 90% by weight, and can be substantially 100% by weight (typically 99.5 to 100% by weight).

[0085] <Ingredient (B)>

[0086] As component (B), a monomer having a hydroxyl group or a carboxyl group can be used. A monomer having a hydroxyl group (hydroxyl-containing monomer) is a compound containing a hydroxyl group and an ethylenically unsaturated group in its structure. A monomer having a carboxyl group (carboxyl-containing monomer) is a compound containing a carboxyl group and an ethylenically unsaturated group in its structure. As component (B), a monomer that does not contain an aromatic ring can typically be used. As the above-mentioned ethylenically unsaturated group, (meth)acryloyl is preferred, and acryloyl is more preferred. In the monomer used as component (B), the number of ethylenically unsaturated groups contained in one molecule of the monomer is typically one.

[0087] As examples of hydroxyl-containing monomers, 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, (4-hydroxymethylcyclohexyl)methyl (meth)acrylate and other (meth)acrylate hydroxyalkyl esters can be listed, but are not limited to these. As examples of hydroxyl-containing monomers that can be preferably used, 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate can be listed. Hydroxyl-containing monomers can be used alone or in combination of two or more.

[0088] Examples of carboxyl-containing monomers include acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, etc., but are not limited to these. Examples of hydroxyl-containing monomers that can be preferably used include acrylic acid and methacrylic acid. Carboxyl-containing monomers can be used alone or in combination of two or more. Hydroxyl-containing monomers and carboxyl-containing monomers can also be used in combination.

[0089] The amount of component (B) is not particularly limited and can be set according to the purpose. In some embodiments, the amount of component (B) can be, for example, 0.01% by weight of the monomer component constituting the adhesive layer, and is usually preferably set to 0.1% by weight or more, and more preferably set to 0.5% by weight or more. In some embodiments, the amount of component (B) can be, for example, 1% by weight or more of the above-mentioned monomer component, or it can be 1.5% by weight or more. In addition, it is appropriate that the amount of component (B) is usually set to less than 40% by weight of the monomer component, and can be set to less than 30% by weight, can be set to less than 20% by weight, can also be set to less than 10% by weight or less than 5% by weight.

[0090] The amount of hydroxyl-containing monomer used as component (B) is not particularly limited, and it is usually appropriate to set it to 0.01% by weight or more (preferably 0.1% by weight or more, for example 0.5% by weight or more) of the monomer components constituting the adhesive layer. In some embodiments, the amount of hydroxyl-containing monomer can be set to, for example, 1% by weight or more of the above-mentioned monomer components, or it can be set to 1.5% by weight or more. In addition, it is usually appropriate to set the amount of hydroxyl-containing monomer to 40% by weight or less of the monomer components, and it can be set to 30% by weight or less, it can be set to 20% by weight or less, it can also be set to 10% by weight or less, or 5% by weight or less.

[0091] The amount used when using carboxyl-containing monomers as component (B) is not particularly limited, and it is usually appropriate to set it to more than 0.01% by weight (preferably more than 0.1% by weight, for example more than 0.5% by weight) of the monomer component constituting the adhesive layer. In some embodiments, the amount of carboxyl-containing monomers can be set to more than 1% by weight of the above-mentioned monomer component, for example, or more than 1.5% by weight. In addition, it is usually appropriate to set the amount of carboxyl-containing monomers to less than 40% by weight of the monomer component, and it can be set to less than 30% by weight, can be set to less than 20% by weight, can also be set to less than 10% by weight or less than 5% by weight. The technology disclosed herein, for example, can preferably be implemented in a manner using only hydroxyl-containing monomers as component (B).

[0092] Although it is not expected to be bound by theory, the reason for realizing an adhesive sheet having both initial low adhesion and subsequent adhesion increase by an adhesive layer comprising a polymerized product of a composition containing the above-mentioned component (A) and the above-mentioned component (B) is, for example, considered as described below. That is, by the use of the above-mentioned component (A), the above-mentioned adhesive layer contains a molecular chain containing an aromatic ring. The molecular chain containing an aromatic ring moves in a manner of leaving the interface with the above-mentioned adherend in the adhesive layer after being attached to the adherend, thereby contributing to the performance of initial low adhesion and subsequent adhesion increase. It is believed that the above-mentioned component (B) has the effect of making the above-mentioned molecular chain containing an aromatic ring easily move in the adhesive layer due to the polarity of the hydroxyl group and / or the carboxyl group. However, it is not limited to be interpreted as only this reason.

[0093] <Adhesive Layer>

[0094] (Glass transition temperature Tg A )

[0095] The glass transition temperature Tg of the adhesive layer is based on the composition of the monomer components constituting the adhesive layer. A It is preferably 40°C or lower. A From the above viewpoint, the glass transition temperature TgA For example, it may be 35° C. or lower, 30° C. or lower, or 25° C. or lower. In some aspects of the pressure-sensitive adhesive sheet disclosed herein, the glass transition temperature Tg A For example, it may be 20°C or lower, 15°C or lower, 10°C or lower, or 5°C or lower.

[0096] The glass transition temperature Tg A Generally, it is preferably higher than -3°C, and more preferably higher than 0°C. This allows appropriate initial low adhesiveness to be achieved. In order to easily control the increase in adhesive strength after attachment, in some embodiments, the glass transition temperature Tg A For example, the temperature may be 5°C or higher, 10°C or higher, 15°C or higher, or 18°C ​​or higher.

[0097] Here, the glass transition temperature Tg A It refers to the glass transition temperature obtained by the Fox equation based on the composition of the monomer corresponding to the above monomer component. The Fox equation is shown below, which is a relationship between the Tg of a copolymer and the glass transition temperature Tgi of a homopolymer obtained by homopolymerizing the monomers constituting the copolymer.

[0098] 1 / Tg=Σ(Wi / Tgi)

[0099] In the above Fox formula, Tg represents the glass transition temperature of the copolymer (unit: K), Wi represents the weight fraction of monomer i in the copolymer (copolymerization ratio based on weight), and Tgi represents the glass transition temperature of the homopolymer of monomer i (unit: K). As the glass transition temperature of the homopolymer used in the calculation of Tg, the value recorded in the known materials such as "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc., 1989) is used. For monomers with multiple values ​​recorded in the above Polymer Handbook, the highest value is used. In the case where the Tg of the homopolymer is not recorded in the known materials, the value obtained by the measurement method described in the Japanese Patent Application Publication No. 2007-51271 is used.

[0100] It should be noted that in this specification, the above Tg A The calculation of is performed with only monofunctional monomers (that is, monomers having a single ethylenically unsaturated group in one molecule) as the object.

[0101] (Alkyl (meth)acrylate)

[0102] In some embodiments of the technology disclosed herein, the composition used in preparing the above-mentioned polymer product may further contain an alkyl (meth)acrylate. As the alkyl (meth)acrylate, preferably, a alkyl (meth)acrylate having 1 to 20 carbon atoms at the ester terminal (i.e., C 1-20 (meth)acrylates containing a linear or branched alkyl group.

[0103] As (meth)acrylic acid C 1-20 Specific examples of the alkyl esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, tert-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, 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, stearyl (meth)acrylate, isostearyl (meth)acrylate, nonadecyl (meth)acrylate, eicosyl (meth)acrylate, etc., but are not limited to these.

[0104] The amount used in the case of using such an alkyl (meth)acrylate can be set in a manner that exerts an appropriate use effect. The above amount can be, for example, more than 5% by weight of the monomer component constituting the adhesive layer, and it is usually appropriate to set it to more than 10% by weight, or it can be set to more than 15% by weight or more than 20% by weight. In addition, it is usually appropriate to set the above amount to less than 80% by weight of the above monomer component, preferably to less than 75% by weight, and it can be less than 65% by weight, or it can be less than 55% by weight. In some preferred embodiments, the amount of the alkyl (meth)acrylate can be less than 45% by weight, less than 40% by weight, less than 35% by weight, or less than 30% by weight of the above monomer component.

[0105] In some preferred embodiments, the composition may contain, as the alkyl (meth)acrylate, an alkyl (meth)acrylate having a homopolymer glass transition temperature of -40°C or less (preferably -50°C or less) (hereinafter also referred to as "component (C)"). By appropriately using component (C), the glass transition temperature Tg can be effectively increased. AThe glass transition temperature of the homopolymer of the (meth)acrylate used as the component (C) may be, for example, -85°C or higher, -75°C or higher, -65°C or higher, or -60°C or higher.

[0106] Suitable examples of (meth)acrylic acid alkyl esters that can be used as component (C) include n-butyl acrylate (BA), 2-ethylhexyl acrylate (2EHA), isononyl acrylate (iNA), etc. For example, a composition containing one or both of BA and 2EHA is preferred, and a composition containing at least BA is more preferred. When BA and 2EHA are used in combination, the weight ratio of their amounts (BA:2EHA) is not particularly limited. The above weight ratio can be, for example, 5:95 or more, 20:80 or more, or 40:60 or more. In a preferred embodiment, the weight ratio of BA:2EHA can be 50:50 or more. In addition, the above weight ratio can be, for example, 95:5 or less, 80:20 or less, or 60:40 or less.

[0107] For the amount used in the case of using component (C), it can be set in a way that a suitable effect of use is exerted. From the viewpoint of improving the adhesive force after the adhesive force rises, the above-mentioned amount can be, for example, more than 5% by weight of the monomer component constituting the adhesive layer, and it is appropriate to be usually set to more than 10% by weight, or it can be set to more than 15% by weight or more than 20% by weight. In addition, from the viewpoint of suppressing the initial adhesive force, it is appropriate to usually set the above-mentioned amount to less than 80% by weight of the monomer component constituting the adhesive layer, preferably set to less than 75% by weight, can be less than 65% by weight, or can be less than 55% by weight. In some preferred modes, the amount of component (C) can be less than 45% by weight, less than 40% by weight, less than 35% by weight, or less than 30% by weight of the above-mentioned monomer component.

[0108] (Comonomer)

[0109] The composition used for preparing the above-mentioned polymer product may further contain other monomers (copolymerizable monomers) copolymerizable with the monomers that can be used as component (B) and the monomers that can be used as component (A). The copolymerizable monomers may be used alone or in combination of two or more.

[0110] Specific non-limiting examples of the copolymerizable monomer include the following.

[0111] Nitrogen-containing monomers: for example, (meth)acrylamide; 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, N,N-di(tert-butyl) (meth)acrylamide and the like N,N-dialkyl (meth)acrylamide; N-ethyl (meth)acrylamide, N-isopropyl (meth)acrylamide, N-butyl (meth)acrylamide, N-n-butyl (meth)acrylamide and the like N-alkyl (meth)acrylamide; N-vinyl carboxylic acid amides such as N-vinyl acetamide; monomers having an alkoxy group and an amide group, for example, N-methoxymethyl (meth)acrylamide, N-methoxyethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide and the like N- Alkoxyalkyl (meth) acrylamide; N,N-dimethylaminopropyl (meth) acrylamide; monomers having a ring containing a nitrogen atom, such as N-vinyl-2-pyrrolidone, N-methylvinyl pyrrolidone, N-vinyl piperidone, N-vinyl piperazine, N-(meth)acryloyl-2-pyrrolidone, N-(meth)acryloyl piperidine, N-(meth)acryloyl pyrrolidine, N-vinyl morpholine, N-(meth)acryloyl morpholine, N-vinyl-3-morpholinone, and N-vinyl-2-caprolactam; aminoalkyl (meth) acrylic acid esters, such as aminoethyl (meth) acrylate, N,N-dimethylaminoethyl (meth) acrylate, N,N-diethylaminoethyl (meth) acrylate, and tert-butylaminoethyl (meth) acrylate; and monomers having a succinimide skeleton, maleimides, itaconimides, and the like.

[0112] Alkoxy-containing monomers: for example, alkoxyalkyl (meth)acrylates such as 2-methoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, propoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, and ethoxypropyl (meth)acrylate; and alkoxyalkyl (meth)acrylates such as methoxyethylene glycol (meth)acrylate and methoxypolypropylene glycol (meth)acrylate.

[0113] Anhydride group-containing monomers: for example, maleic anhydride, itaconic anhydride.

[0114] Epoxy group-containing monomers: For example, epoxy group-containing acrylates such as glycidyl (meth)acrylate and 2-ethyl glycidyl (meth)acrylate, allyl glycidyl ether, and glycidyl (meth)acrylate.

[0115] Cyano group-containing monomers: for example, acrylonitrile, methacrylonitrile, etc.

[0116] Isocyanate group-containing monomers: for example, 2-isocyanatoethyl (meth)acrylate, and the like.

[0117] Vinyl esters: such as vinyl acetate, vinyl propionate, etc.

[0118] Vinyl ethers: vinyl alkyl ethers such as methyl vinyl ether and ethyl vinyl ether.

[0119] Olefins: such as ethylene, butadiene, isoprene, isobutylene, etc.

[0120] (Meth)acrylates having an alicyclic hydrocarbon group: for example, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentyl (meth)acrylate, and the like.

[0121] and heterocyclic-containing (meth)acrylates such as tetrahydrofurfuryl (meth)acrylate, halogen-containing (meth)acrylates such as vinyl chloride and / or fluorine-containing (meth)acrylates, silicon-containing (meth)acrylates such as silicone (meth)acrylate, sulfonic- or phosphoric-acid-containing monomers, and (meth)acrylates derived from terpene compound derivative alcohols.

[0122] When using such a copolymerizable monomer, its consumption is not particularly limited, and it is appropriate to usually be set to more than 0.01% by weight of the monomer component constituting the adhesive layer. From the viewpoint of better exerting the use effect of the copolymerizable monomer, the consumption of the copolymerizable monomer can be set to more than 0.1% by weight of the monomer component, or it can be set to more than 1% by weight. In addition, from the viewpoint of easily obtaining a balance with other performances, it is appropriate to usually set the consumption of the copolymerizable monomer to less than 40% by weight of the monomer component, preferably less than 30% by weight, less than 20% by weight, less than 15% by weight, less than 10% by weight, or less than 7.5% by weight.

[0123] (N-vinyl cyclic amide)

[0124] In some aspects, the composition preferably contains at least one monomer selected from the group consisting of N-vinyl cyclic amides represented by the following general formula (M1).

[0125]

[0126] Here, R in the above general formula (M1) 1 It is a divalent organic group.

[0127] By using N-vinyl cyclic amide, the cohesion and polarity of the adhesive can be adjusted, and the adhesive strength after the adhesive strength rises (for example, the adhesive strength after heating N2) can be improved. As specific examples of N-vinyl cyclic amide, N-vinyl-2-pyrrolidone, N-vinyl-2-piperidone, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-3,5-morpholinedione, etc. can be listed. Particularly preferred are N-vinyl-2-pyrrolidone and N-vinyl-2-caprolactam.

[0128] The amount used when using N-vinyl cyclic amide is not particularly limited, and it is usually appropriate to set it to more than 0.01% by weight (preferably more than 0.1% by weight, for example more than 0.5% by weight) of the monomer components constituting the adhesive layer. In some embodiments, the amount of N-vinyl cyclic amide can be set to more than 1% by weight of the above-mentioned monomer components, can be set to more than 3% by weight, or can be set to more than 4% by weight. In addition, from the viewpoint of easily achieving a balance with other properties, it is usually appropriate to set the amount of N-vinyl cyclic amide to less than 40% by weight of the monomer components, preferably less than 30% by weight, can be less than 20% by weight, can be less than 15% by weight, can be less than 10% by weight, or can be less than 7.5% by weight.

[0129] In some embodiments, the weight ratio of the monomer having a polyorganosiloxane skeleton (hereinafter, also referred to as a monomer containing a polyorganosiloxane structure) in the monomer components constituting the adhesive layer can be, for example, less than 1% by weight. In some embodiments, the above-mentioned weight ratio can be less than 0.5% by weight, less than 0.1% by weight, less than 0.05% by weight, or 0% by weight (i.e., a monomer component that does not contain a monomer containing a polyorganosiloxane structure). According to the technology disclosed herein, even if the amount of the monomer containing a polyorganosiloxane structure is limited in this way, an adhesive sheet having low adhesion at the initial stage of attachment and excellent adhesion increase thereafter can be appropriately achieved. The ability to suppress the amount of the monomer containing a polyorganosiloxane structure can be an advantageous feature for adhesive sheets used for applications where siloxane is not desired (e.g., electronic equipment applications, etc.).

[0130] (Polymer P)

[0131] The adhesive layer in the technology disclosed herein typically includes a polymer P formed from monomers contained in the above-mentioned composition (including at least a monomer used as component (B) and a monomer that can be used as component (A), and may further include other monomers), and in a method of using an oligomer AR as component (A), further includes an oligomer AR.

[0132] In the embodiment in which only an aromatic ring-containing monomer is used as component (A) (i.e., an embodiment in which an oligomer AR is not used), the weight ratio of the aromatic ring-containing monomer in the monomers contained in the above composition (hereinafter, also referred to as "the aromatic ring-containing monomer ratio of the polymer P") can be, for example, 10% by weight or more. From the viewpoint of being easy to properly exert the initial low adhesiveness and the subsequent adhesive force increase, it is usually preferably 25% by weight or more, 35% by weight or more, 45% by weight or more, 55% by weight or more, 60% by weight or more, or 65% by weight or more. In addition, in the above embodiment, the aromatic ring-containing monomer ratio of the polymer P can be, for example, 95% by weight or less. From the viewpoint of improving the adhesive force increase, it is usually preferably 90% by weight or less, 85% by weight or less, 80% by weight or less, or 75% by weight or less.

[0133] In the method of using oligomer AR as component (A), the aromatic ring-containing monomer ratio of polymer P can be, for example, 5% by weight or more, preferably 10% by weight or more, 15% by weight or more, or 20% by weight or more. In some methods, the aromatic ring-containing monomer ratio of polymer P can be, for example, 25% by weight or more, 30% by weight or more, 35% by weight or more, or 40% by weight or more, considering the compatibility of polymer P and oligomer AR. In addition, in the above method, the aromatic ring-containing monomer ratio of polymer P can be, for example, 85% by weight or less. From the perspective of easily improving the adhesive force after the adhesive force is increased, it is appropriate to be 70% by weight or less, and it can be 60% by weight or more, or 50% by weight or less.

[0134] In some embodiments, the aromatic ring-containing monomer ratio (R O [wt%]) to the aromatic ring-containing monomer ratio of polymer P (R P [weight %]), namely |R O -R P | For example, it may be 90 or less. From the viewpoint of improving the compatibility between the oligomer AR and the polymer P, it is usually appropriate to be 80 or less, preferably 70 or less, and may be 65 or less, or 60 or less. From the viewpoint of more easily expressing the initial low adhesion, in some embodiments, | R O -R P | For example, it may be 10 or more, 25 or more, 40 or more, or 50 or more. From the viewpoint of adhesive strength enhancement, R O With R P The relationship is preferably R O ≥R P , more preferably R O >R P .

[0135] In the embodiment in which the oligomer AR is used as the component (A), the glass transition temperature of the composition of the monomers contained in the above composition, that is, the glass transition temperature (Tg P ) is not particularly limited. The above glass transition temperature Tg P For example, it may be -70°C or higher, -60°C or higher, or -50°C or higher. In some embodiments, the glass transition temperature Tg is preferably -40°C or higher from the viewpoint of more easily expressing the initial low adhesiveness. P For example, it may be -40°C or higher, -35°C or higher, -30°C or higher, or -25°C or higher. P For example, it may be 30°C or lower, 20°C or lower, 10°C or lower, 5°C or lower, or 0°C or lower. From the viewpoint of improving the mobility of the oligomer AR and thus effectively increasing the adhesive force, in some embodiments, the glass transition temperature Tg P For example, the temperature may be -5°C or lower, -10°C or lower, or -15°C or lower.

[0136] The glass transition temperature (Tg O ) is not particularly limited, and may be, for example, -10°C or higher, or 0°C or higher. From the viewpoint of appropriately achieving low initial adhesion, the glass transition temperature (Tg O ) is preferably 10°C or higher, preferably 20°C or higher, and may be 35°C or higher, 50°C or higher, 65°C or higher, or 75°C or higher. O ) For example, it may be 180°C or lower. From the viewpoint of achieving good adhesive strength increase, 150°C or lower is usually appropriate. It may be 130°C or lower, or 110°C or lower.

[0137] From the viewpoint of more appropriately exerting the initial low adhesiveness and the subsequent adhesive strength increase, the glass transition temperature (Tg O [℃]) is higher than the glass transition temperature (Tg P [℃]) is appropriate, usually Tg O -Tg P It is preferably 10 or more. From the viewpoint of making it easier to better exert the effect of using the oligomer AR, in some embodiments, Tg O -Tg P For example, it may be 30°C or higher, 50°C or higher, 70°C or higher, 85°C or higher, 100°C or higher, or 105°C or higher. From the same viewpoint, in some embodiments, TgO -Tg P For example, the temperature may be 200°C or lower, and is usually appropriately 180°C or lower. The temperature may be 160°C or lower, 140°C or lower, or 130°C or lower.

[0138] It should be noted that the glass transition temperature (Tg P ) and the glass transition temperature (Tg O ) are determined by the above-mentioned Fox equation based on the composition of the monomer components constituting the polymer P (that is, the composition of the monomers contained in the above-mentioned composition) and the composition of the monomer components constituting the oligomer AR.

[0139] In some embodiments, the monomers contained in the composition may be, for example, 30% by weight or more of the acrylic monomers. From the viewpoint of ease of adjustment of polymerization reactivity and adhesive properties, the weight ratio of the acrylic monomers in the monomers contained in the composition may be, for example, preferably more than 50% by weight, more preferably more than 65% by weight, more than 80% by weight, more than 90% by weight, more than 95% by weight, or substantially 100% by weight (for example, more than 99.9% by weight and less than 100% by weight).

[0140] (Crosslinking agent)

[0141] For the purpose of adjusting cohesive force, suppressing initial adhesive force, etc., a crosslinking agent can be used in the adhesive layer as needed. As a crosslinking agent, a crosslinking agent known in the field of adhesives such as epoxy crosslinking agents, isocyanate crosslinking agents, oxazoline crosslinking agents, aziridine crosslinking agents, silane coupling agents, alkyl etherified melamine crosslinking agents, and metal chelate crosslinking agents can be used. As other examples of crosslinking agents, monomers having more than two ethylenically unsaturated groups in one molecule, i.e., multifunctional monomers, can be listed. A crosslinking agent can be used alone or in combination of two or more.

[0142] Examples of isocyanate crosslinking agents include toluene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, tetramethylxylylene diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, polymethylene polyphenyl isocyanate, and adducts thereof with polyols such as trimethylolpropane. Alternatively, compounds having at least one isocyanate group and one or more unsaturated bonds in one molecule, specifically 2-isocyanatoethyl (meth)acrylate, etc., can also be used as isocyanate crosslinking agents. These can be used alone or in combination of two or more.

[0143] Examples of epoxy crosslinking agents include bisphenol A, epichlorohydrin type epoxy resins, ethylene glycidyl ether, polyethylene glycol diglycidyl ether, glycerol diglycidyl ether, glycerol triglycidyl ether, 1,6-hexanediol glycidyl ether, trimethylolpropane triglycidyl ether, diglycidyl aniline, diamine glycidyl amine, N,N,N',N'-tetraglycidyl meta-xylylenediamine, and 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, etc. These can be used alone or in combination of two or more.

[0144] Examples of the polyfunctional monomer include ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, allyl(meth)acrylate, vinyl(meth)acrylate, divinylbenzene, bisphenol A di(meth)acrylate, epoxy acrylate, polyester acrylate, urethane acrylate, butanediol(meth)acrylate, and hexanediol di(meth)acrylate. As other examples, polyfunctional monomers containing a fluorene skeleton such as 9,9-bis(4-hydroxyphenyl)fluorene di(meth)acrylate and 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene di(meth)acrylate can be cited. As commercial products of the polyfunctional monomers, product names "OGSOL EA-0200", "OGSOLEA-0300", "OGSOL EA-0500", "OGSOL EA-1000" and the like manufactured by Osaka Gas Chemicals Co., Ltd. can be cited. For example, dipentaerythritol hexa(meth)acrylate, 1,6-hexanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate and the like can be preferably used. The polyfunctional monomers can be used alone or in combination of two or more.

[0145] The amount used when using a crosslinking agent (which can be a multifunctional monomer) is not particularly limited, for example, it can be set to a range of about 0.01 to 5.0 parts by weight relative to 100 parts by weight of the monomer components constituting the adhesive layer. In some embodiments, the amount of the crosslinking agent can be, for example, 0.01 parts by weight or more, or 0.03 parts by weight or more relative to 100 parts by weight of the monomer contained in the above-mentioned composition. By increasing the amount of the crosslinking agent, there is a tendency that the initial adhesion of the attachment is suppressed and the reprocessability is improved. On the other hand, from the viewpoint of improving the rising property of the adhesion, it is appropriate to generally set the amount of the crosslinking agent to 5.0 parts by weight or less relative to 100 parts by weight of the monomer contained in the above-mentioned composition, preferably 3.0 parts by weight or less, 2.0 parts by weight or less, 1.0 parts by weight or less, 0.5 parts by weight or less, 0.2 parts by weight or less, 0.1 parts by weight or less, or 0.08 parts by weight or less.

[0146] (Other additives)

[0147] The adhesive layer may contain a tackifier resin as needed. As the tackifier resin, rosin-based tackifier resins, terpene-based tackifier resins, phenol-based tackifier resins, hydrocarbon-based tackifier resins, ketone-based tackifier resins, polyamide-based tackifier resins, epoxy-based tackifier resins, elastic system tackifier resins, etc. can be listed. They can be used alone or in combination of two or more. As the tackifier resin, a tackifier resin having a softening point (softening temperature) of about 80°C or more (preferably about 100°C or more, for example, about 120°C or more) can be preferably used. The upper limit of the softening point is not particularly limited, for example, it can be about 200°C or less (typically 180°C or less). The softening point of the tackifier resin can be measured based on the softening point test method (ring and ball method) specified in JIS K 2207.

[0148] In the method of using a tackifying resin, its amount is not particularly limited and can be set according to the purpose and use in a manner that exerts appropriate adhesive properties. For example, the content of the tackifying resin relative to 100 parts by weight of the monomer contained in the above-mentioned composition (the total amount thereof in the case of containing two or more tackifying resins) can be, for example, about 0.5 to 200 parts by weight, 5 to 100 parts by weight, or 10 to 50 parts by weight. The technology disclosed herein can also be preferably implemented in a manner that the adhesive layer does not substantially contain a tackifying resin.

[0149] In addition, the adhesive layer in the technology disclosed herein may contain known additives that can be used in adhesives, such as leveling agents, plasticizers, softeners, colorants (dyes, pigments, etc.), fillers, antistatic agents, anti-aging agents, ultraviolet absorbers, antioxidants, light stabilizers, preservatives, etc., as needed within the range that does not significantly hinder the effects of the present invention.

[0150] <Method for Forming Adhesive Layer>

[0151] The adhesive layer of the adhesive sheet disclosed herein contains a polymerization product of a composition containing at least component (A) and component (B). The method for polymerizing the monomers contained in the above composition is not particularly limited, and various polymerization methods such as solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, and photopolymerization can be used alone or in appropriate combination.

[0152] The initiator used in the polymerization can be appropriately selected from the conventionally known thermal initiators, photoinitiators, etc. according to the polymerization method. As non-limiting examples of thermal initiators, azo initiators such as 2,2'-azobisisobutyronitrile (AIBN), persulfates such as potassium persulfate, peroxide initiators, redox initiators, etc. can be listed. As non-limiting examples of photoinitiators, benzoin ether photoinitiators, acetophenone photoinitiators, α-ketol photoinitiators, aromatic sulfonyl chloride photoinitiators, photoactive oxime photoinitiators, benzoin photoinitiators, benzyl photoinitiators, benzophenone photoinitiators, ketal photoinitiators, thioxanthone photoinitiators, acylphosphine oxide photoinitiators, etc. can be listed. The initiator can be used alone or in combination of two or more.

[0153] In some embodiments, as a method for obtaining a polymerized product from the above-mentioned composition, a photopolymerization method can be used. For example, a method of irradiating a composition containing components (A) and (B) as essential components, other components used as needed, and a photoinitiator with ultraviolet light (UV) can be preferably used. The above-mentioned UV irradiation can be performed all at once or in stages. As an example of a method for performing UV irradiation in stages, the following method can be cited: after the above-mentioned composition is irradiated with UV in a suitable reaction container and the monomers contained in the composition are partially polymerized, the composition is given to a suitable surface, and the above-mentioned monomers are completely polymerized on its surface. In the method of performing photopolymerization of the composition in stages, a part of the components (monomers, oligomers, etc.) can be added on the way of the above-mentioned staged photopolymerization. For example, a mixture containing a part of the monomers used in the above-mentioned composition can be irradiated with UV and the monomers in the mixture can be partially or completely polymerized, and then the remaining monomers are added and mixed, and then UV is irradiated to form a polymerized product. In addition, in the oligomer method, for example, after the monomers used in the above-mentioned composition are partially polymerized, oligomers and other materials used as needed are added, and then polymerization is performed to form a polymerized product.

[0154] Among other methods, solution polymerization can be preferably used. As a polymerization solvent, for example, ethyl acetate, toluene, etc. can be used. The solution concentration is usually about 20 to 80% by weight. As an initiator, various known initiators such as azo-based and peroxide-based initiators can be used. In order to adjust the molecular weight, a chain transfer agent can be used. The reaction temperature can be about 50 to 80°C. The reaction time can be about 1 to 8 hours.

[0155] The adhesive layer of the adhesive sheet disclosed herein can be a cured layer of a composition comprising the above-mentioned component (A) and the above-mentioned component (B) or an adhesive composition containing a partial polymer thereof. That is, the adhesive layer can be formed by applying (e.g., coating) the above-mentioned adhesive composition to an appropriate surface and then appropriately performing a curing treatment. In the case of performing two or more curing treatments (drying, crosslinking, polymerization, cooling, etc.), they can be performed simultaneously or in multiple stages. For an adhesive composition using a partial polymer of the above-mentioned composition, typically, a final copolymerization reaction is performed as the above-mentioned curing treatment. That is, a complete polymer is formed by a partial polymer. For example, in the case of a photocurable adhesive composition, light irradiation is performed. As required, curing treatments such as crosslinking and drying can be performed. For example, in the case where a photocurable adhesive composition needs to be dried, it is appropriate to perform photocuring after drying. For an adhesive composition using a complete polymer, typically, as the above-mentioned curing treatment, drying (heat drying), crosslinking, etc. are performed as required.

[0156] The pressure-sensitive adhesive composition can be applied using a conventional coater such as a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, or a spray coater.

[0157] The thickness of the adhesive layer is not particularly limited, for example, it can be set to 1 μm. In some embodiments, the thickness of the adhesive layer can be, for example, 5 μm or more, 10 μm or more, 20 μm or more, 30 μm or more, 50 μm or more, 70 μm or more, or 85 μm or more. By increasing the thickness of the adhesive layer, there is a tendency for the adhesive force to rise after heating. In addition, in some embodiments, the thickness of the adhesive layer can be, for example, 300 μm or less, 250 μm or less, 200 μm or less, 150 μm or less, or 120 μm or less. The thickness of the adhesive layer is not too large, which can be advantageous from the perspective of thinning the adhesive sheet. It should be noted that in the case of an adhesive sheet having a first adhesive layer and a second adhesive layer on the first and second surfaces of the substrate, the thickness of the adhesive layer can at least be applied to the thickness of the first adhesive layer. The thickness of the second adhesive layer can also be selected from the same range. In addition, in the case of an adhesive sheet without a substrate, the thickness of the adhesive sheet is consistent with the thickness of the adhesive layer.

[0158] <Supporting substrate>

[0159] The adhesive sheet of several modes can be in the form of an adhesive sheet with a substrate having an adhesive layer on one or both sides of the supporting substrate. The material of the supporting substrate is not particularly limited and can be appropriately selected according to the purpose of use, the mode of use, etc. of the adhesive sheet. As non-limiting examples of usable substrates, there can be listed polyolefin films with polyolefins such as polypropylene (PP) and ethylene-propylene copolymer as the main component, polyester films with polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN) as the main component, and polyvinyl chloride films with polyvinyl chloride as the main component, etc. Plastic films; foam sheets formed by foams such as polyurethane foam, polyethylene (PE) foam, and polychloroprene foam; woven and non-woven fabrics obtained by various fibrous materials (which can be natural fibers such as hemp and cotton, synthetic fibers such as polyester and vinylon, and semi-synthetic fibers such as acetate, etc.) alone or by blending; paper such as Japanese paper, high-quality paper, kraft paper, crepe paper; metal foils such as aluminum foil and copper foil; etc. The substrate may be a composite substrate of these structures. Examples of such composite substrates include a substrate having a structure in which a metal foil and the above-mentioned plastic film are laminated, and a plastic substrate reinforced with inorganic fibers such as glass cloth.

[0160] In some embodiments, various film substrates can be preferably used. The above-mentioned film substrate can be a porous substrate such as a foam film, a non-woven fabric sheet, etc., or a non-porous substrate, or a substrate with a structure in which a porous layer and a non-porous layer are stacked. In some embodiments, as the above-mentioned film substrate, a film substrate containing a resin film that can independently maintain its shape (self-supporting or non-dependent) as a base film can be preferably used. Here, "resin film" refers to a resin film that is a non-porous structure and typically does not substantially contain bubbles (voids). Therefore, the above-mentioned resin film is a concept that is different from foam films and non-woven fabrics. As the above-mentioned resin film, a resin film that can independently maintain its shape (self-supporting or non-dependent) can be preferably used. The above-mentioned resin film can be a single-layer structure, or it can be a multilayer structure of more than two layers (for example, a three-layer structure).

[0161] As the resin material constituting the resin film, for example, polyester, polyolefin, nylon 6, nylon 66, partially aromatic polyamide and other polyamide (PA), polyimide (PI), polyamideimide (PAI), polyetheretherketone (PEEK), polyethersulfone (PES), polyphenylene sulfide (PPS), polycarbonate (PC), polyurethane (PU), ethylene-vinyl acetate copolymer (EVA), polytetrafluoroethylene (PTFE) and other fluororesins, acrylic resins, polyacrylates, polystyrene, polyvinyl chloride, polyvinylidene chloride and other resins can be used.

[0162] The resin film can be a resin film formed by using a resin material containing a single resin, or a resin film formed by using a resin material mixed with two or more. The resin film can be unstretched or a resin film stretched (e.g., uniaxially stretched or biaxially stretched). For example, PET film, PBT film, PEN film, unstretched polypropylene (CPP) film, biaxially stretched polypropylene (OPP) film, low-density polyethylene (LDPE) film, linear low-density polyethylene (LLDPE) film, PP / PE mixed film, etc. can be preferably used. From the viewpoint of strength and dimensional stability, as examples of preferred resin films, PET film, PEN film, PPS film and PEEK film can be listed. From the viewpoint of ease of acquisition, PET film and PPS film are particularly preferred, wherein PET film is preferred.

[0163] The resin film may be mixed with known additives such as light stabilizers, antioxidants, antistatic agents, colorants (dyes, pigments, etc.), fillers, lubricants, anti-blocking agents, etc. as needed within the range that does not significantly hinder the effect of the present invention. The mixing amount of the additives is not particularly limited and can be appropriately set according to the use of the adhesive sheet, etc.

[0164] The method for producing the resin film is not particularly limited, and for example, conventionally known general resin film forming methods such as extrusion molding, blow molding, T-die casting, and calender roll molding can be appropriately used.

[0165] The substrate may be a substrate substantially composed of such a base film. Alternatively, the substrate may be a substrate further comprising an auxiliary layer in addition to the base film. Examples of the auxiliary layer include an optical property adjustment layer (e.g., a coloring layer, an antireflection layer), a printing layer for imparting a desired appearance to the substrate, a laminating layer, an antistatic layer, a primer layer, a peeling layer, and other surface treatment layers.

[0166] The thickness of the substrate is not particularly limited and can be selected according to the purpose and method of use of the adhesive sheet. The thickness of the substrate can be, for example, 1000 μm or less. In some embodiments, from the perspective of the handling and processing properties of the adhesive sheet, the thickness of the substrate can be, for example, 500 μm or less, 300 μm or less, 250 μm or less, or 200 μm or less. From the perspective of miniaturization and lightweight of products to which the adhesive sheet is applied, in some embodiments, the thickness of the substrate can be, for example, 160 μm or less, 130 μm or less, 100 μm or less, 90 μm or less, 70 μm or less, 50 μm or less, 25 μm or less, 10 μm or less, or 5 μm or less. If the thickness of the substrate becomes smaller, there is a tendency for the softness of the adhesive sheet and the ability to follow the surface shape of the adherend to be improved. In addition, from the viewpoint of handling and processing, the thickness of the substrate can be, for example, 2 μm or more, 5 μm or more, 10 μm or more, 20 μm or more, 25 μm or more, or more than 25 μm. In some embodiments, the thickness of the substrate can be, for example, 30 μm or more, 35 μm or more, 55 μm or more, 75 μm or more, or 120 μm or more. For example, in an adhesive sheet that can be used for the purpose of strengthening, supporting, and impact mitigation of an adherend, a substrate with a thickness of 30 μm or more can be preferably used.

[0167] The surface of one side of the laminated adhesive layer in the substrate can be subjected to corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, the formation of a primer layer based on the coating of a primer (primer) and other previously known surface treatments as needed. Such surface treatment can be a treatment for improving the anchoring of the adhesive layer to the substrate. The composition of the primer used in the formation of the primer layer is not particularly limited and can be appropriately selected from known substances. The thickness of the primer layer is not particularly limited, and is usually about 0.01 μm to 1 μm, preferably about 0.1 μm to 1 μm. As other treatments that can be implemented on the substrate as needed, antistatic layer formation treatment, coloring layer formation treatment, printing treatment, etc. can be listed. These treatments can be applied alone or in combination.

[0168] <Adhesive Sheet>

[0169] (Properties of adhesive sheets, etc.)

[0170] In several forms of the adhesive sheet disclosed herein, the adhesive sheet is attached to a stainless steel plate and the adhesive force N1 (initial adhesive force) after 30 minutes at 23°C can be, for example, 7N / 20mm or less. For the above-mentioned initial adhesive force, from the viewpoint of improving reprocessability, etc., it is preferably less than 5N / 20mm, more preferably less than 4N / 20mm, and can be less than 3N / 20mm, less than 2N / 20mm, or less than 1N / 20mm. There is no particular restriction on the lower limit of the initial adhesive force, for example, it can be 0.01N / 20mm or more. From the viewpoint of the workability of attaching to the adherend and the prevention of positional displacement before the adhesive force rises, it is appropriate that the adhesive force N1 is generally 0.1N / 20mm or more, and can also be 0.2N / 20mm or more. From the viewpoint of easily obtaining higher adhesive strength after heating, in some embodiments, the initial adhesive strength may be, for example, 0.5 N / 20 mm or more, 0.7 N / 20 mm or more, 1.2 N / 20 mm or more, or 1.5 N / 20 mm or more.

[0171] For the adhesive sheet disclosed herein, the ratio of the adhesive force N2 (adhesive force after heating) to the adhesive force N1 (initial adhesive force) after being attached to a stainless steel plate and heated at 80°C for 5 minutes at 23°C for 30 minutes, that is, N2 / N1 (adhesive force increase ratio) is preferably 2N / 20mm or more. Thus, good reprocessability can be shown at the initial stage of attachment, and the adhesive force can be greatly increased by subsequent heating, etc. From the perspective of taking into account both reprocessability and strong adhesion during use at a higher level, N2 / N1 is preferably 3 or more, more preferably 4 or more, and further preferably 6 or more. In some embodiments, the N2 / N1 of the adhesive sheet can be 8 or more, 10 or more, 15 or more, 20 or more, 25 or more, or 30 or more. The upper limit of N2 / N1 is not particularly limited. From the perspective of the ease of manufacturing and economy of the adhesive sheet, in some embodiments, N2 / N1 can be, for example, 80 or less, 60 or less, or 45 or less.

[0172] Here, the adhesive force N1 [N / 20mm] is determined by crimping a stainless steel (SUS) plate as an adherend and placing it in an environment of 23°C and 50% RH for 30 minutes, and then measuring the 180° peeling adhesive force under the conditions of a peeling angle of 180 degrees and a tensile speed of 300 mm / minute. The adhesive force N2 [N / 20mm] is determined by crimping a SUS plate as an adherend and heating it at 80°C for 5 minutes, then placing it in an environment of 23°C and 50% RH for 30 minutes, and then measuring the 180° peeling adhesive force under the conditions of a peeling angle of 180 degrees and a tensile speed of 300 mm / minute. As the adherend, a SUS304BA plate is used in any measurement of the adhesive forces N1 and N2. During the measurement, as needed, a suitable backing material (e.g., a PET film with a thickness of about 25 μm) can be attached to the adhesive sheet of the measurement object to strengthen it. More specifically, the adhesive forces N1 and N2 can be measured based on the method described in the embodiments described later.

[0173] The adhesive force N2 (adhesive force after heating) is usually appropriate to be 3N / 20mm or more, preferably 5N / 20mm or more, and more preferably 7.5N / 20mm or more. In some embodiments, the adhesive force N2 can be 10N / 20mm or more, 12N / 20mm or more, or 15N / 20mm or more. There is no particular limit to the upper limit of the adhesive force after heating. From the viewpoint of good reprocessability in the initial stage of attachment, in some embodiments, the adhesive force after heating can be, for example, 70N / 20mm or less, 60N / 20mm or less, or 50N / 20mm or less.

[0174] It should be noted that in this specification, the adhesive force of the adhesive sheet after heating represents a characteristic of the adhesive sheet, and does not limit the use of the adhesive sheet. In other words, the use of the adhesive sheet disclosed herein is not limited to the method of heating at 80°C for 5 minutes, and can be used in a method of not particularly heating to a room temperature range (usually 20°C to 30°C, typically 23°C to 25°C) or above. Even in this method of use, the adhesive force rises over a long period of time and a strong bond can be achieved. In addition, the adhesive sheet disclosed herein can promote the increase in adhesive force by performing a heat treatment at any time after attachment. The heating temperature in the heat treatment is not particularly limited, and can be set in consideration of workability, economy, the substrate of the adhesive sheet, the heat resistance of the adherend, etc. The above-mentioned heating temperature can be, for example, less than 150°C, or less than 120°C, or less than 100°C, less than 80°C, or less than 70°C. In addition, the above-mentioned heating temperature can be, for example, set to 35°C or more, or more than 50°C, or more than 60°C, more than 80°C, or more than 100°C. When a higher heating temperature is used, the adhesive force can be increased by a shorter treatment time. The heating time is not particularly limited, for example, it can be less than 1 hour, it can be less than 30 minutes, it can also be less than 10 minutes, less than 5 minutes. Alternatively, the heat treatment can be carried out for a longer time within the limit that the adhesive sheet and the adherend will not produce significant thermal degradation. It should be noted that the heat treatment can be carried out once or multiple times.

[0175] (Adhesive sheet with substrate)

[0176] In the case where the adhesive sheet disclosed here is in the form of an adhesive sheet with a substrate, the thickness of the adhesive sheet can be, for example, 1000 μm or less, 600 μm or less, 350 μm or less, or 250 μm or less. From the perspective of miniaturization, lightness, and thinness of products to which the adhesive sheet is applied, in some embodiments, the thickness of the adhesive sheet can be, for example, 200 μm or less, 175 μm or less, 140 μm or less, 120 μm or less, or 110 μm or less. In addition, from the perspective of handleability, the thickness of the adhesive sheet can be, for example, 10 μm or more, 25 μm or more, 50 μm or more, 80 μm or more, 100 μm or more, or 130 μm or more. The upper limit of the thickness of the adhesive sheet is not particularly limited.

[0177] It should be noted that the thickness of the adhesive sheet refers to the thickness of the portion attached to the adherend. Figure 1 In the PSA sheet 1 having the structure shown, the thickness is the thickness from the PSA surface 21A of the PSA sheet 1 to the second surface 10B of the substrate 10 , and does not include the thickness of the release liner 31 .

[0178] <Adhesive Sheet with Release Liner>

[0179] The adhesive sheet disclosed herein can be in the form of an adhesive product in which the surface (adhesive surface) of the adhesive layer is brought into contact with the release surface of the release liner. Therefore, according to this specification, an adhesive sheet with a release liner (adhesive product) can be provided, which comprises any adhesive sheet disclosed herein and a release liner having a release surface brought into contact with the adhesive surface of the adhesive sheet.

[0180] As the release liner, there is no particular limitation, for example, a release liner having a release layer on the surface of a liner substrate such as a resin film, paper (which can be a paper laminated with a resin such as polyethylene) or the like, a release liner made of a resin film formed of a low-adhesive material such as a fluorine-based polymer (polytetrafluoroethylene, etc.) or a polyolefin-based resin (polyethylene, polypropylene, etc.), etc. can be used. From the aspect of excellent surface smoothness, a release liner having a release layer on the surface of a resin film as a liner substrate, a release liner made of a resin film formed of a low-adhesive material can be preferably used. As the resin film, as long as it is a film that can protect the adhesive layer, there is no particular limitation, for example, polyethylene (PE) film, polypropylene (PP) film, polybutylene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyester film (PET film, PBT film, etc.), polyurethane film, ethylene-vinyl acetate copolymer film, etc. can be cited. The release layer may be formed by using known release agents such as silicone release agents, long-chain alkyl release agents, olefin release agents, fluorine release agents, fatty acid amide release agents, molybdenum sulfide, and silica powder.

[0181] <Purpose>

[0182] The adhesive sheet provided by the specification, for example, after being attached to the adherend, can suppress the adhesive force to be low for a long time at room temperature. The above-mentioned adhesive sheet can play a good reprocessing property during the period when the above-mentioned adhesive force is suppressed to be low, so it contributes to the suppression of the reduction of the yield rate and the high quality of the product containing the adhesive sheet. In addition, the above-mentioned adhesive sheet can be greatly increased by aging (which can be heating, time, their combination, etc.). For example, after the attachment of the adherend, it is heated at the desired moment, so that the adhesive sheet can be firmly bonded to the adherend. Utilizing such a usage mode, in the manufacture of portable electronic devices and other electronic devices, or the manufacture of automobiles, household appliances, etc., which include the process of attaching the adhesive sheet to the adherend, the degree of freedom of the handling of the adhesive sheet increases. Therefore, the above-mentioned adhesive sheet can be used as a bonding material in, for example, electronic equipment, automobiles, household appliances, etc. In addition, it can also be preferably used for optical purposes such as the bonding of optical films used in image display devices such as liquid crystal displays, plasma displays, organic EL displays, etc. The adhesive sheet disclosed herein can also be a composition using the above-mentioned optical film as a substrate (support substrate).

[0183] It can be understood from the above description and the following embodiments that the matters disclosed by this specification include the following matters.

[0184] [1] A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer,

[0185] The adhesive layer comprises a polymerization product of a composition comprising:

[0186] (A) at least one of a monomer having an aromatic ring and an oligomer including a repeating unit having an aromatic ring, and

[0187] (B) a monomer having a hydroxyl group or a carboxyl group,

[0188] The glass transition temperature Tg of the monomer components constituting the adhesive layer is A Above -3°C and below 40°C.

[0189] [2] The pressure-sensitive adhesive sheet according to [1] above, wherein the composition contains at least the monomer having an aromatic ring as the (A).

[0190] [3] The pressure-sensitive adhesive sheet according to [2] above, wherein the composition contains at least one selected from the group consisting of benzyl acrylate, ethoxylated phenylphenol acrylate, biphenyl methyl acrylate, and phenoxybenzyl acrylate as the monomer having an aromatic ring.

[0191] [4] The pressure-sensitive adhesive sheet according to any one of [1] to [3] above, wherein 55% by weight or more of the monomer components constituting the pressure-sensitive adhesive layer are monomers having an aromatic ring.

[0192] [5] The pressure-sensitive adhesive sheet according to any one of [1] to [4] above, wherein more than 50% by weight of the monomers contained in the composition are acrylic monomers.

[0193] [6] The pressure-sensitive adhesive sheet according to any one of [1] to [5] above, wherein the composition contains at least the oligomer containing a repeating unit having an aromatic ring as the (A).

[0194] [7] The pressure-sensitive adhesive sheet according to [6] above, wherein the composition contains a styrene oligomer as the oligomer containing a repeating unit having an aromatic ring.

[0195] [8] The pressure-sensitive adhesive sheet according to any one of [1] to [7] above, wherein the monomer (B) having a hydroxyl group or a carboxyl group is an acrylic monomer.

[0196] [9] The pressure-sensitive adhesive sheet according to any one of [1] to [8] above, wherein the composition further comprises an alkyl (meth)acrylate having a homopolymer glass transition temperature of -40°C or less.

[0197]

[10] The pressure-sensitive adhesive sheet according to any one of [1] to [9] above, wherein the composition further comprises an N-vinyl cyclic amide.

[0198]

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

[10] above, wherein the pressure-sensitive adhesive strength N1 after being bonded to a stainless steel plate at 23° C. for 30 minutes is less than 5 N / 20 mm.

[0199]

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

[11] above, wherein the pressure-sensitive adhesive sheet is bonded to a stainless steel plate and heated at 80°C for 5 minutes and then at 23°C for 30 minutes, and has a pressure-sensitive adhesive strength N2 that is at least twice the pressure-sensitive adhesive strength N1.

[0200]

[13] A pressure-sensitive adhesive composition for use in producing a pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to any one of [1] to

[12] above.

[0201]

[14] An adhesive composition comprising a polymerization product of a composition comprising:

[0202] (A) at least one of a monomer having an aromatic ring and an oligomer including a repeating unit having an aromatic ring, and

[0203] (B) a monomer having a hydroxyl group or a carboxyl group,

[0204] The glass transition temperature Tg of the monomer components constituting the above-mentioned adhesive composition is C Above -3°C and below 40°C.

[0205] [Example]

[0206] Several examples related to the present invention are described below, but the present invention is not intended to be limited to the contents shown in the specific examples. It should be noted that "parts" and "%" in the following description are based on weight unless otherwise specified.

[0207] <Preparation of Adhesive Compositions C1 to C6>

[0208] A mixture of monomers and photoinitiators of the types and amounts shown in Table 1 was irradiated with ultraviolet rays in a nitrogen atmosphere to partially polymerize the monomers contained in the mixture, and then a crosslinking agent (multifunctional monomer) in the amount shown in Table 1 and a styrene oligomer were added and mixed for adhesive compositions C1 and C5 to prepare adhesive compositions C1 to 6. It should be noted that in Table 1, the values ​​in brackets in Examples 1 and 5 represent the weight fraction [%] of each monomer and styrene oligomer relative to the total amount of the monomers and oligomers used.

[0209] <Preparation of Adhesive Sheet>

[0210] (Example 1)

[0211] Prepare two kinds of release liners R1 and R2 in which one side of a polyester film becomes a release surface based on a silicone-based release treatment agent. As the release liner R1, the trade name "Diafoil MRF" (thickness 38 μm) manufactured by Mitsubishi Resins Corporation is used. As the release liner R2, the trade name "Diafoil MRE" (thickness 38 μm) manufactured by Mitsubishi Resins Corporation is used. The adhesive composition C1 is applied to the release surface of the above-mentioned release liner R1 to form a coating layer with a thickness of 100 μm. Next, the release liner R2 is covered on the surface of the above-mentioned coating layer in a manner that its release surface becomes the side of the above-mentioned coating layer to block the air, and irradiated with an illumination of 3 mW / cm using a chemiluminescent lamp manufactured by Toshiba Corporation. 2 The coating layer was cured by ultraviolet light for 360 seconds to form an adhesive layer. In this way, an adhesive sheet of Example 1 including the adhesive layer was prepared. It should be noted that the above-mentioned illuminance value is a measured value based on an industrial UV detector (manufactured by TOPCON CORPORATION, trade name "UVR-T1", light receiving part model UD-T36) with a peak sensitivity wavelength of about 350nm.

[0212] (Examples 2~6)

[0213] PSA sheets of Examples 2 to 6 were prepared in the same manner as in the preparation of the PSA sheet of Example 1, except that PSA compositions C2 to C6 were used instead of PSA composition C1.

[0214] <Adhesion to SUS>

[0215] The PSA sheet of each example was cut into a 20 mm width piece together with the release liner to prepare a test piece. A SUS plate (SUS304BA plate) cleaned with toluene was used as an adherend, and the initial adhesive strength and the adhesive strength after heating were measured in the following procedure.

[0216] (Measurement of initial adhesive force (N1))

[0217] Under the standard environment of 23°C and 50%RH, the release liner covering the adhesive surface of each test piece was peeled off, and a 2kg roller was reciprocated once, and the exposed adhesive surface was pressed against the adherend. The test piece thus pressed against the adherend was placed under the above-mentioned standard environment for 30 minutes, and then, a universal tensile compression tester (device name "tensile compression tester, TCM-1kNB" Minebea company) was used to measure the 180° peeling adhesion (resistance to the above-mentioned stretching) under the conditions of a peeling angle of 180 degrees and a tensile speed of 300mm / min according to JIS Z0237. The measurement was carried out 3 times, and their average value was taken as the initial adhesion (N1) [N / 20mm].

[0218] (Measurement of Adhesion Strength (N2) after Heating)

[0219] The test piece pressed to the adherend in the same manner as the measurement of the initial adhesive strength was heated at 80°C for 5 minutes, then left in the above standard environment for 30 minutes, and then the 180° peel adhesive strength was measured in the same manner. The measurement was performed three times, and the average value thereof was taken as the adhesive strength after heating (N2) [N / 20mm].

[0220] <Adhesion strength increase ratio (N2 / N1)>

[0221] Based on the initial adhesive force (N1) and the adhesive force after heating (N2) obtained by the above measurement, the adhesive force increase ratio (N2 / N1) was calculated.

[0222] The obtained results are shown in Table 1.

[0223] [Table 1]

[0224] Table 1

[0225]

[0226] · BZA: benzyl acrylate, manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name "#BisCos#160", Tg 11°C

[0227] .A-LEN-10: o-ethoxylated phenylphenol acrylate, manufactured by Shin-Nakamura Industries, Ltd., Tg 33°C

[0228] Styrene oligomer: Yasuhara Chemical Co., LTD, trade name "YS Resin SX-100", Mw about 2500, Tg 100°C

[0229] ·DPHA: Dipentaerythritol hexaacrylate, manufactured by Nippon Kayaku Co., Ltd., trade name "KAYARAD DPHA"

[0230] ·Omnirad 184: 1-Hydroxycyclohexylphenylketone, | Made by GM Regins

[0231] ·Omnirad 651: 2,2-dimethoxy-1,2-diphenylethane-1-one, | Made by GM Regins

[0232] It should be noted that the above Tg A When calculating the glass transition temperature of the homopolymer of the aromatic ring-containing monomer, the values ​​recorded under the column of Table 1 are used. The styrene oligomer used in Examples 1 and 5 is a homopolymer of styrene, and its Tg is 100°C. As the glass transition temperature of the homopolymer of other monomers, the following values ​​are used. n-Butyl acrylate: -55°C, 2-ethylhexyl acrylate: -70°C, 4-hydroxybutyl acrylate: -32°C, acrylic acid: 105°C, N-vinyl-2-pyrrolidone: 54°C.

[0233] As shown in Table 1, it was confirmed that the glass transition temperature Tg A Compared with the PSA sheets of Examples 4 to 6 at -3°C or lower, the PSA sheets of Examples 1 to 3 showed good low tack in the initial stage, and the adhesive strength increased significantly by heating. The PSA sheet of Example 1 gave particularly good results.

[0234] Although the specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of protection of the claims. The technology described in the claims includes various modifications and changes to the specific examples described above.

Claims

1. An adhesive sheet comprising an adhesive layer, The adhesive layer comprises a polymerization product of a composition comprising: (A) at least one of a monomer having an aromatic ring and an oligomer including a repeating unit having an aromatic ring, and (B) a monomer having a hydroxyl group or a carboxyl group, The composition contains at least the monomer having an aromatic ring as the (A), wherein the monomer having an aromatic ring includes a compound having an aromatic ring and an ethylenically unsaturated group in its structure. The monomer having a hydroxyl group or a carboxyl group contains a hydroxyl group or a carboxyl group and a (meth)acryloyl group in its structure, The glass transition temperature Tg of the monomer components constituting the adhesive layer A Above -3℃ and below 40℃, Among the monomer components constituting the adhesive layer, 35% by weight or more and 90% by weight or less are monomers having an aromatic ring, The adhesive strength N2 after being bonded to a stainless steel plate and heated at 80°C for 5 minutes and then at 23°C for 30 minutes was 3 N / 20 mm or more.

2. The adhesive sheet according to claim 1, wherein The composition includes at least one selected from the group consisting of benzyl acrylate, ethoxylated phenylphenol acrylate, biphenyl methyl acrylate, and phenoxybenzyl acrylate as the monomer having an aromatic ring.

3. The adhesive sheet according to claim 1 or 2, wherein Among monomer components constituting the adhesive layer, 55% by weight or more and 90% by weight or less are monomers having an aromatic ring.

4. The adhesive sheet according to claim 1 or 2, wherein The composition comprises monomers of which more than 50% by weight are acrylic monomers.

5. The adhesive sheet according to claim 1 or 2, wherein The composition contains at least the oligomer containing a repeating unit having an aromatic ring as the (A).

6. The adhesive sheet according to claim 5, wherein The composition includes a styrene oligomer as the oligomer including a repeating unit having an aromatic ring.

7. The adhesive sheet according to claim 1 or 2, wherein The composition further comprises an alkyl (meth)acrylate having a homopolymer glass transition temperature of -40°C or less.

8. The adhesive sheet according to claim 1 or 2, wherein The adhesion N1 after being attached to a stainless steel plate at 23°C for 30 minutes is less than 5N / 20mm, and The adhesive force N2 after the plate was bonded to a stainless steel plate and heated at 80° C. for 5 minutes and then at 23° C. for 30 minutes was more than twice the adhesive force N1.

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