WO2023048013A1

WO2023048013A1 - Adhesive sheet, laminate, and device for transmitting or receiving electromagnetic waves

Info

Publication number: WO2023048013A1
Application number: PCT/JP2022/034159
Authority: WO
Inventors: 真理子野田; 徳之内田; 泰志石堂; 良介川原
Original assignee: 積水化学工業株式会社
Priority date: 2021-09-21
Filing date: 2022-09-13
Publication date: 2023-03-30
Also published as: JPWO2023048013A1; JP2024091913A; JP7481481B2; KR20240060515A; CN117255840A

Abstract

The purpose of the present invention is to provide: an adhesive sheet that has a low dielectric loss tangent for high-frequency bands and does not readily generate bubbles at an interface with an adherend, even at high temperatures; a laminate that uses the adhesive sheet; and a device that transmits or receives electromagnetic waves. The present invention is an adhesive sheet that has an adhesive layer that contains a styrene elastomer as a base resin and has a gel fraction of at least 30 weight%. The adhesive sheet does not include a base material and has a 90° peeling strength of at least 5 N/25 mm relative to glass.

Description

Adhesive sheets, laminates, and devices that transmit or receive electromagnetic waves

TECHNICAL FIELD The present invention relates to an adhesive sheet, a laminate, and an apparatus for transmitting or receiving electromagnetic waves.

Adhesive tapes or sheets are widely used in various fields. It is used to fix electronic equipment parts to a vehicle body (for example, Patent Documents 1 and 2).

JP 2009-242541 A JP 2009-258274 A

In recent years, there has been a demand in the field of electronic devices to transmit and receive large amounts of data at higher speeds, and so-called fifth-generation mobile communication systems (5G) are being put to practical use. Frequencies are in progress. However, there is a problem that the attenuation of the transmission signal (referred to as "transmission loss") increases due to the increase in frequency.
Adhesive tapes or sheets that can suppress such transmission loss are also desired as adhesive tapes or sheets used in electronic devices. In particular, in recent years, for example, antennas for small antenna base stations, vehicle-mounted antennas, and the like are becoming increasingly film-based. Even as an adhesive tape or sheet used for bonding between members inside such an antenna film, bonding the antenna film to other members, etc., transmission loss can be suppressed, and the frequency of the transmission signal can be increased. There is a demand for an adhesive tape or sheet that can be suitably used in any case.

The present invention provides a pressure-sensitive adhesive sheet that has a small dielectric loss tangent in a high frequency band and is less prone to foaming at the interface with an adherend even in a high-temperature environment, a laminate using the pressure-sensitive adhesive sheet, and an electromagnetic wave that is transmitted or received. The object is to provide a device for

The present disclosure 1 is a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer contains a styrene-based elastomer as a base resin and has a gel fraction of 30% by weight or more, and the pressure-sensitive adhesive sheet includes a base material and has a 90° peeling force to glass of 5 N/25 mm or more.
The present disclosure 2 is the pressure-sensitive adhesive sheet according to the present disclosure 1, wherein the pressure-sensitive adhesive sheet has a dielectric loss tangent of 0.005 or less at a frequency of 10 GHz.
Present Disclosure 3 is the adhesive sheet according to

Present Disclosure

1 or 2, wherein the styrene-based elastomer is a hydrogenated styrene-based elastomer.
Present Disclosure 4 is the adhesive sheet according to Present Disclosure 3, wherein the hydrogenated styrene-based elastomer is a hydrogenated block copolymer having an aromatic alkenyl polymer block and a conjugated diene polymer block.
In present disclosure 5, the pressure-sensitive adhesive layer further contains a tackifying resin, and the tackifying resin contains a tackifying resin (T1) having no double bond,

present disclosures

1, 2, and 3 Or 4 adhesive sheets.
Present Disclosure 6 is the pressure-sensitive adhesive sheet of Present Disclosure 5, wherein the tackifying resin consists only of a tackifying resin (T1) having no double bond.
The present disclosure 7 is a radial block in which the hydrogenated block copolymer having the aromatic alkenyl polymer block and the conjugated diene polymer block has a structure represented by the general formula (AB) _n C 4 is a pressure-sensitive adhesive sheet of the present disclosure 4, which is a hydrogenated copolymer.
A: Aromatic alkenyl polymer block B: Conjugated diene polymer block C: Component derived from coupling agent n: An integer of 3 or more It is the adhesive sheet of this

indication

1, 2, 3, 4, 5, 6 or 7 which is the above.
Present Disclosure 9 is the pressure-sensitive adhesive sheet according to

Present Disclosure

1, 2, 3, 4, 5, 6, 7, or 8, wherein the styrene-based elastomer has a styrene content of 30% by weight or less.
The present disclosure 10 is

present disclosures

1, 2, 3, 4, 5, 6, wherein the pressure-sensitive adhesive layer contains 15 parts by weight or less of a (meth)acrylic monomer with respect to 100 parts by weight of the styrene elastomer. 7, 8 or 9 adhesive sheets.
Present Disclosure 11 is the pressure-sensitive adhesive sheet according to Present Disclosure 5 or 6, wherein the pressure-sensitive adhesive layer contains 20 parts by weight or more and 80 parts by weight or less of the tackifying resin with respect to 100 parts by weight of the base resin.
Present disclosure 12 is the adhesive sheet according to

present disclosure

1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or 11, which is used in a device that transmits or receives electromagnetic waves with a frequency of 1 GHz or more.
The present disclosure 13 is used for bonding between members inside a laminate including a film having a conductive pattern formed thereon, or bonding a laminate including a film having a conductive pattern formed thereon and another member. , the adhesive sheet of the

present disclosure

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12.
The present disclosure 14 is a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive layer contains a styrene-based elastomer as a base resin and has a gel fraction of 30% by weight or more, and the pressure-sensitive adhesive sheet includes a base material and has a 90° peeling force to glass of 5 N/25 mm or more, the adhesive layer further contains a tackifying resin, and the tackifying resin does not have a double bond ( T1) only, the hydrogenated styrene elastomer is a hydrogenated block copolymer having an aromatic alkenyl polymer block and a conjugated diene polymer block, and the aromatic alkenyl polymer block and the conjugated diene The hydrogenated block copolymer having a polymer block is a hydrogenated radial block copolymer having a structure represented by the general formula (AB) _n C, and has a dielectric property at a frequency of 10 GHz. The adhesive sheet has a tangent of 0.002 or less.
A: Aromatic alkenyl polymer block B: Conjugated diene polymer block C: Component derived from coupling agent n: An integer of 3 or more , 8, 9, 10, 11, 12, 13 or 14 and a film having a conductive pattern formed thereon.
Disclosure 16 is a device for transmitting or receiving electromagnetic waves that includes the laminate of Disclosure 15.
The present invention will be described in detail below.

Since the transmission loss increases in proportion to the frequency, it is an unavoidable problem that the higher the frequency of the transmission signal, the greater the transmission loss. In order to suppress transmission loss in a high frequency band (for example, around 1 to 80 GHz), it is conceivable to use, for example, an adhesive sheet having excellent dielectric properties in a high frequency band. That is, the transmission loss is affected by not only the frequency but also the "permittivity" and "dielectric loss tangent" of the insulating parts existing around the conductive part. Using a small adhesive sheet is expected to suppress transmission loss.
The inventors of the present invention have investigated the base resin that constitutes the adhesive layer in the adhesive sheet having the adhesive layer. It was found that the modulus and dielectric loss tangent were small. Until now, almost no knowledge has been obtained about the dielectric properties of styrene-based elastomers in high frequency bands. The present inventors also found that the dielectric loss tangent in a high frequency band can be suppressed to a lower value by using a pressure-sensitive adhesive sheet that does not have a base material.

On the other hand, for example, antennas such as small antenna base stations and vehicle-mounted antennas are often used outdoors. The adhesive sheet used is exposed to high temperatures (about 120°C). When the adhesive sheet is exposed to high temperatures, outgassing occurs from the adherend, or microbubbles that enter between the adherend and the adhesive sheet due to insufficient adhesion to the adherend grow at high temperatures. As a result, foaming may occur at the interface between the adherend and the pressure-sensitive adhesive sheet, and changes in optical properties such as yellowing may occur, resulting in a problem of poor appearance. In particular, when the pressure-sensitive adhesive sheet does not have a substrate, the adhesive strength tends to be lower than when it has a substrate, so foaming is likely to occur at the interface between the adherend and the pressure-sensitive adhesive sheet. When foaming occurs at the interface between the adherend and the pressure-sensitive adhesive sheet, the dielectric properties change in a high frequency band, which may adversely affect signal transmission.
In a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer, the present inventors used a styrene-based elastomer for the pressure-sensitive adhesive layer, in addition to making the pressure-sensitive adhesive sheet without a substrate, the gel fraction of the pressure-sensitive adhesive layer, and A study was made to adjust the 90° peeling force of the pressure-sensitive adhesive sheet to glass within a specific range. The present inventors have found that such a pressure-sensitive adhesive sheet has a small dielectric loss tangent in a high frequency band and hardly causes foaming at the interface with the adherend even in a high-temperature environment. Arrived.

The adhesive sheet of the present invention has an adhesive layer.
The pressure-sensitive adhesive layer contains a styrene-based elastomer as a base resin. The styrene-based elastomer has a smaller dielectric constant and dielectric loss tangent in a high frequency band than, for example, an acrylic polymer. Therefore, since the pressure-sensitive adhesive layer contains the styrene-based elastomer, the pressure-sensitive adhesive sheet has a small dielectric loss tangent in a high frequency band, and can be suitably used even when the transmission signal has a high frequency.
In addition, the base resin refers to a resin that is contained in the largest amount among the resins other than the tackifying resin and the softening agent that are optionally blended to constitute the pressure-sensitive adhesive layer.

The styrene-based elastomer is not particularly limited, and may be a non-hydrogenated styrene-based elastomer or a hydrogenated styrene-based elastomer. Among them, a hydrogenated styrene elastomer is preferable. Since the hydrogenated styrene elastomer has a lower double bond (unsaturated bond) content than the non-hydrogenated styrene elastomer, the pressure-sensitive adhesive layer containing the hydrogenated styrene elastomer , the pressure-sensitive adhesive sheet is less susceptible to change in optical properties in a high-temperature environment than when the non-hydrogenated styrene-based elastomer is contained.

In addition, the hydrogenated styrene elastomer is preferably 80% or more, more preferably 90% or more, still more preferably 95% or more of the double bonds (unsaturated bonds) of the repeating units derived from the conjugated diene compound. Still more preferably, it means a styrene-based elastomer in which 96% or more is converted to saturated bonds by hydrogenation. The hydrogenated styrene elastomer may be partially hydrogenated or completely hydrogenated. The hydrogenation ratio (hydrogenation ratio) can be calculated by measuring the ¹ H-NMR spectrum at 20 Hz using deuterated chloroform as a solvent.

Although the hydrogenated styrene-based elastomer is not particularly limited, it is preferably a hydrogenated block copolymer having an aromatic alkenyl polymer block and a conjugated diene polymer block.

The hydrogenated block copolymer having the aromatic alkenyl polymer block and the conjugated diene polymer block is not particularly limited, has rubber elasticity at room temperature, and has a hard segment portion and a soft segment portion. It is sufficient if it is a hydrogenated product of a block copolymer having The aromatic alkenyl polymer block is the hard segment portion, and the conjugated diene polymer block is the soft segment portion.
As the hydrogenated block copolymer having the aromatic alkenyl polymer block and the conjugated diene polymer block, more specifically, for example, a block copolymer having a structure represented by the general formula ABA Hydrogenated products of coalescence, hydrogenated products of radial type block copolymers having a structure represented by the general formula (AB) _n C, and the like can be mentioned.
A: Aromatic alkenyl polymer block _B : Conjugated diene polymer block C: Component derived from coupling agent Hydrogenated versions of type block copolymers are preferred. By containing the hydrogenated product of the radial block copolymer having the structure represented by the general formula (AB) _n C, the adhesive strength of the adhesive layer is improved, and the adhesive sheet is 90 to glass. ° It becomes easier for the peel force to satisfy the range described later. In addition, since the hydrogenated radial block copolymer having the structure represented by the general formula (AB) _n C is crosslinked well, the gel fraction of the pressure-sensitive adhesive layer is within the range described later. easier to meet. Furthermore, by improving the adhesive strength of the pressure-sensitive adhesive layer, it is possible to reduce the amount of the tackifying resin (in particular, a tackifying resin (T2) that easily self-polymerizes as described later). AB) Crosslinking of the hydrogenated radial type block copolymer having the structure represented by _nC proceeds well, and the gel fraction of the pressure-sensitive adhesive layer easily satisfies the range described later. In this way, both the 90° peeling force of the pressure-sensitive adhesive sheet against glass and the gel fraction of the pressure-sensitive adhesive layer easily satisfy the range described below. Foaming occurring at the interface with the adherend is further reduced.

The aromatic alkenyl polymer block represented by A above means a block having repeating units derived from an aromatic alkenyl compound.
The aromatic alkenyl polymer block represented by A above may be a block having a repeating unit derived from an aromatic alkenyl compound. The aromatic alkenyl polymer block represented by A above includes ethylene, 1,3-butadiene (converted to an ethylene-butylene structure by hydrogenation), propylene, isoprene (converted to an ethylene-propylene structure by hydrogenation ) may contain repeating units derived from other compounds.
Examples of the aromatic alkenyl compounds include alkylstyrene, halogenated styrene, halogen-substituted alkylstyrene, alkoxystyrene, carboxyalkylstyrene, alkyletherstyrene, alkylsilylstyrene, vinylbenzyldimethoxyphosphide, vinylnaphthalene, vinylanthracene, N , N-diethyl-p-aminoethylstyrene, vinylpyridine and the like.

Examples of the alkylstyrene include styrene, methylstyrene, dimethylstyrene, t-butylstyrene and the like. Examples of the halogenated styrene include chlorostyrene, bromostyrene, fluorostyrene and the like. Examples of the halogen-substituted alkylstyrene include chloromethylstyrene. Examples of the alkoxystyrene include methoxystyrene and ethoxystyrene. Examples of the carboxyalkylstyrene include carboxymethylstyrene. Examples of the alkyl ether styrenes include vinyl benzyl propyl ether and the like. Examples of the alkylsilylstyrene include trimethylsilylstyrene.
These aromatic alkenyl compounds may be used alone or in combination of two or more. Among these, styrene, methylstyrene, and dimethylstyrene are preferred, and styrene is more preferred because of its industrial availability.

The conjugated diene polymer block represented by B has repeating units derived from a conjugated diene compound.
Examples of the conjugated diene compounds include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-octadiene, and 1,3-hexadiene. , 1,3-cyclohexadiene, 4,5-diethyl-1,3-octadiene, 3-butyl-1,3-octadiene, myrcene, chloroprene and the like. These conjugated diene compounds may be used alone or in combination of two or more. Among them, 1,3-butadiene and isoprene are preferred because of their high polymerization reactivity and industrial availability. In addition to the above conjugated diene compounds, 2,5-dihydrofuran-2,5-dione can be used, for example.

Specific examples of hydrogenated block copolymers having a structure represented by the general formula ABA include styrene-ethylene-butylene-styrene (SEBS) block copolymers, styrene-ethylene -Propylene-styrene (SEPS) block copolymer, styrene-ethylene-ethylene-propylene-styrene (SEEPS) and the like. The hydrogenated block copolymer having the structure represented by the general formula ABA also includes styrene-isobutylene-styrene (SIBS) block copolymer. Among them, the SEBS block copolymer is preferable because the cross-linking proceeds well and the gel fraction of the pressure-sensitive adhesive layer easily satisfies the below-described range.

The hydrogenated product of the radial block copolymer having the structure represented by the above general formula (AB) _n C contains one hard segment and a soft segment centering on the component (C) derived from the coupling agent. It is a branched styrenic block copolymer having a structure in which a plurality of diblock-structured styrenic block copolymers (AB) are bonded to each other and protrude radially.
Although n may be an integer of 3 or more, n is preferably 4 or more because the adhesive strength of the pressure-sensitive adhesive layer is improved. The upper limit of n is not particularly limited, but from the viewpoint of suppressing gelation of the hydrogenated radial block copolymer having the structure represented by the general formula (AB) _n C, it is usually 8 or less. .

The coupling agent, which is a raw material for the component derived from the coupling agent represented by C, is a polyfunctional compound that radially bonds the styrene-based block copolymer (AB) having the diblock structure.
Examples of the coupling agent include silane compounds such as silane halides and alkoxysilanes, tin compounds such as tin halides, epoxy compounds such as polycarboxylic acid esters and epoxidized soybean oil, and acrylic compounds such as pentaerythritol tetraacrylate. Divinyl compounds such as esters, epoxysilanes, and divinylbenzene, and the like are included. More specific examples include trichlorosilane, tribromosilane, tetrachlorosilane, tetrabromosilane, methyltrimethoxysilane, ethyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, tetramethoxysilane, tetraethoxysilane, tetrachlorotin, diethyl adipate and the like.

The hydrogenated product of the radial block copolymer having the structure represented by the general formula (A-B) _n C has a content of the aromatic alkenyl polymer block represented by A above of 5% by weight or more, It is preferably 30% by weight or less. When the content of the aromatic alkenyl polymer block represented by A is within the above range, the adhesive strength of the pressure-sensitive adhesive layer is further improved. From the viewpoint of further improving the adhesive strength, the aromatic alkenyl polymer block represented by A in the hydrogenated product of the radial block copolymer having the structure represented by the general formula (AB) _n C A more preferable lower limit of the content is 8% by weight, a more preferable upper limit is 25% by weight, a still more preferable lower limit is 9% by weight, and a further preferable upper limit is 20% by weight.

The styrene (St) content of the styrene-based elastomer is not particularly limited, but the preferred upper limit is 30% by weight. When the styrene content is 30% by weight or less, the pressure-sensitive adhesive layer has appropriate pressure-sensitive adhesive strength, and the pressure-sensitive adhesive sheet has a smaller dielectric loss tangent in a high frequency band. A more preferable upper limit of the styrene content is 20% by weight. The lower limit of the styrene content is not particularly limited, but from the viewpoint of maintaining the cohesive strength of the pressure-sensitive adhesive layer, the preferred lower limit is 8% by weight.
The styrene content is derived from the charged weight ratio of the monomers of the aromatic alkenyl compound before polymerization. That is, the styrene content is (weight of monomer of aromatic alkenyl compound)/(weight of monomer of aromatic alkenyl compound+weight of monomer of conjugated diene compound).
Also, the molar ratio of the styrene content can be calculated from the peak area ratio of each block of the block copolymer measured by ¹ H-NMR. The styrene content (molar ratio) is different from the styrene content (weight ratio of charged monomers), but in the case of SEBS, for example, there is the following tendency. When the styrene content (monomer weight ratio) is 10% by weight, the styrene content (molar ratio) is 4 to 7.9 mol%. ) is 8 to 9.9 mol %. When the styrene content (monomer weight ratio) is 20% by weight, the styrene content (molar ratio) is 10 to 15 mol%, and when the styrene content (monomer weight ratio) is 30% by weight, the styrene content (molar ratio) is 15-20 mol %. Therefore, when the monomer charge weight ratio is unknown, it can be estimated from the styrene content molar ratio obtained from the peak area ratio of each block measured by ¹ H-NMR.
In addition, when using a general-purpose product, the styrene content is described in the catalog, so that value is used as the styrene content.

The weight average molecular weight (Mw) of the styrene-based elastomer is not particularly limited, but a preferable lower limit is 200,000, a more preferable lower limit is 250,000, and a further preferable lower limit is 280,000. When the weight average molecular weight (Mw) is 200,000 or more, the adhesive strength of the adhesive layer is improved, and the dielectric loss tangent of the adhesive sheet in a high frequency band becomes smaller. The upper limit of the weight-average molecular weight (Mw) is not particularly limited. is limited to about 700,000.

In addition, the weight average molecular weight (Mw) of a styrene-type elastomer means the weight average molecular weight (Mw) measured as a polystyrene conversion molecular weight by gel permeation chromatography (GPC) method. Measurement of the weight average molecular weight (Mw) by GPC can be performed, for example, by the following method.
A solution of a styrene-based elastomer dissolved in tetrahydrofuran (THF) is filtered through a filter (material: polytetrafluoroethylene, pore size: 0.2 μm) to obtain a GPC test solution. Waters "ACQUITY ^TM Advanced Polymer Chromatography ^TM System" as a GPC system, Waters "HSPgel ^TM HR MB-M (6.0 mm × 150 mm)" as a GPC column, and a differential refractive index detector as a detector. and perform GPC measurement. The sample injection volume is 10 μL of a 20 mg/mL solution, the flow rate is 0.5 mL/min, and the column temperature is 40°C. As analysis software, Empower 3 attached to the apparatus is used. Polystyrene (peak top molecular weight: 2110000, 1090000, 427000, 190000, 37900, 18100, 5970, 2420, 500) (manufactured by Tosoh Corporation) is used as a standard. Polystyrene is measured as a standard, and a calibration curve for converting the elution amount to polystyrene molecular weight is created and analyzed using analysis software. Using this calibration curve, the weight average molecular weight (Mw) is converted from the GPC elution volume.

The content of the base resin is not particularly limited. be. When the above ratio is 80 parts by weight or more, the dielectric loss tangent of the pressure-sensitive adhesive sheet in a high frequency band becomes smaller. A more preferable lower limit of the above ratio is 90 parts by weight. The upper limit of the above ratio is not particularly limited, and may be 100 parts by weight. That is, the resin other than the tackifying resin and the softening agent, which are blended as necessary and which constitute the pressure-sensitive adhesive layer, may be the base resin alone.

The pressure-sensitive adhesive layer preferably further contains a tackifying resin.
By containing the tackifying resin, the adhesive strength of the adhesive layer is improved, the 90 ° peeling force of the adhesive sheet to glass easily satisfies the range described later, and the interface with the adherend in a high temperature environment Less foaming occurs.

The tackifying resin is not particularly limited, and may be a tackifying resin (T1) having no double bond (unsaturated bond), or at least one selected from the group consisting of double bonds and aromatic rings. It may be a tackifying resin (T2) having a These tackifying resins may be used alone or in combination of two or more. Among them, it is preferable to contain a tackifying resin (T1) having no double bond, and it is more preferable that the tackifying resin (T1) has a ratio of 80% by weight or more in the tackifying resin, and 90% by weight. The above is more preferable, and it is particularly preferable that the tackifying resin consists only of the tackifying resin (T1) having no double bond.
Since the tackifying resin (T1) having no double bond has a smaller dielectric constant and dielectric loss tangent in a high frequency band, the pressure-sensitive adhesive layer contains the tackifying resin (T1) having no double bond. By containing it, the dielectric loss tangent in the high frequency band of the pressure-sensitive adhesive sheet becomes smaller. In addition, the tackifying resin (T1) having no double bond is self-polymerized compared to the tackifying resin (T2) having at least one selected from the group consisting of the double bond and the aromatic ring. Hateful. Therefore, when the pressure-sensitive adhesive layer contains the tackifying resin (T1) having no double bond, the crosslinking of the styrene-based elastomer proceeds favorably. This makes it easier to satisfy the range to be used, and the foaming that occurs at the interface with the adherend in a high-temperature environment is further reduced.
The SP value of the tackifying resin (T1) having no double bond is not particularly limited, but since the dielectric constant and dielectric loss tangent are even smaller in the high frequency band, the preferred upper limit is 9.0, and more A preferred upper limit is 8.5. Although the lower limit of the SP value of the tackifying resin (T1) having no double bond is not particularly limited, considering the SP value of general tackifying resins, the practical lower limit is about 7.5.

In the present specification, the SP value is a parameter that determines the activity of each component in a multicomponent system, which is determined based on Hildebrand's theory of regular solutions, and using Hoy's constant according to the following formula (I) It means an SP value calculated by the Small method.
SP value (δ) = d * (ΣG) / M (I)
(d: density (g/ml), G: molecular attraction constant of each functional group of Hoy, M: molecular weight (g/mol))

A method for calculating the SP value is described in the following references.
K. L. Hoy, New values of the solubility parameters from vapor pressure data, J. Am. Paint Techn. , Vol. 42, No. 541, p. 76 (1970); L. Hoy, The Hoy tables of solubility parameters, Union Carbide Corp.; , 1985; L. Hoy, Solubility Parameters as a design parameter for water borne polymers and coatings. Preprints 14th Int. Conf. Athene, 1988. ;K. L. Hoy, J.; Coated Fabrics, 19, p. 53 (1989).

Examples of the tackifying resin (T1) having no double bond include hydrogenated C5 petroleum resins, alicyclic petroleum resins, hydrogenated C9 petroleum resins, hydrogenated C9 aromatic resins, hydrogenated α-methyl Examples include styrene resins and ultra-light-colored rosin esters.

As the tackifying resin (T2) having at least one selected from the group consisting of double bonds and aromatic rings, for example, terpene, aromatic modified terpene, aromatic modified hydrogenated terpene, terpene phenol, hydrogenated terpene phenol , rosin ester, rosin phenol, styrene copolymer tackifying resin, C5 petroleum resin, C9 petroleum resin, C5 aliphatic resin, C9 aromatic resin, pure C9 monomer resin, and the like. Among them, terpene, aromatic modified terpene, and rosin esters are preferred, and terpenes are more preferred.

The softening point of the tackifying resin is not particularly limited, but the preferred lower limit is 80°C. When the softening point is 80° C. or higher, the adhesive strength of the pressure-sensitive adhesive layer at high temperatures is improved, and foaming occurring at the interface with the adherend under high-temperature environments is further reduced. A more preferable lower limit of the softening point is 90°C, and a still more preferable lower limit is 100°C, because the adhesive strength at higher temperatures is improved. Although the upper limit of the softening point is not particularly limited, it is preferably 140° C. considering the temperature used.
In addition, the said softening point can be measured by the method according to JISK2207.

The content of the tackifying resin is not particularly limited, but the preferred lower limit is 20 parts by weight and the preferred upper limit is 80 parts by weight with respect to 100 parts by weight of the base resin. When the content of the tackifier resin is 20 parts by weight or more, the adhesive strength of the adhesive layer is further improved. When the content of the tackifying resin is 80 parts by weight or less, even if the pressure-sensitive adhesive layer contains the tackifying resin, cross-linking of the styrene-based elastomer proceeds well, and the gel fraction of the pressure-sensitive adhesive layer becomes easier to satisfy the range described later. A more preferable lower limit of the content of the tackifier resin is 25 parts by weight, and a more preferable upper limit thereof is 75 parts by weight.

The pressure-sensitive adhesive layer may further contain a softening agent.
By including the softener, the adhesive strength of the pressure-sensitive adhesive layer is further improved. Examples of the softening agent include polybutene, n-butene-isobutylene copolymer, polyisoprene, and paraffin oil. Among these, polybutene is preferable because it is well compatible with the styrene-based elastomer.
On the other hand, if the softener is used, the adhesive properties of the pressure-sensitive adhesive layer at high temperatures are lowered. Therefore, it is necessary to adjust the blending amount of the softening agent according to the performance, degree of crosslinking, etc. of the base resin to be used. The smaller the amount, the better. That is, the lower limit of the blending amount of the softening agent is not particularly limited, and may be 0 parts by weight. In addition, the base resin refers to a resin that is contained in the largest amount among resins other than the tackifying resin and the softening agent that constitute the pressure-sensitive adhesive layer.

The pressure-sensitive adhesive layer may further contain a (meth)acrylic monomer.
Since the (meth)acrylic monomer is likely to be radicalized, the adhesive layer containing the (meth)acrylic monomer facilitates cross-linking of the styrene elastomer, resulting in gel content of the adhesive layer. It becomes easier for the rate to satisfy the range described later.

The (meth)acrylic monomer is not particularly limited, and examples thereof include (meth)acrylic acid esters generally used as monomers constituting (meth)acrylic copolymers. The number of functional groups of the (meth)acrylic monomer is not particularly limited, and may be bifunctional, trifunctional, tetrafunctional, pentafunctional, hexafunctional or the like.
Specific examples of the (meth)acrylic monomer include ethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and 1,9-nonanediol. di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate and the like. These (meth)acrylic monomers may be used alone or in combination of two or more. Among the above (meth)acrylic acid esters, methacrylic acid esters are preferable from the viewpoint of efficient cross-linking. Among them, neopentyl glycol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,9-nonanediol dimethacrylate and trimethylolpropane trimethacrylate are preferred.

The content of the acrylic monomer is not particularly limited, but the preferred upper limit is 15 parts by weight with respect to 100 parts by weight of the base resin. When the content of the acrylic monomer is 15 parts by weight or less, the styrene-based elastomer is sufficiently crosslinked, and the gel fraction of the pressure-sensitive adhesive layer easily satisfies the below-described range. A more preferable upper limit of the content of the acrylic monomer is 10 parts by weight. The lower limit of the content of the acrylic monomer is not particularly limited, and may be 0 parts by weight, but the preferred lower limit is 2 parts by weight.

The lower limit of the gel fraction of the pressure-sensitive adhesive layer is 30% by weight.
When the adhesive layer has a gel fraction of 30% by weight or more, the adhesive sheet is less prone to foaming at the interface with the adherend even in a high-temperature environment. A preferable lower limit of the gel fraction of the adhesive layer is 35% by weight, a more preferable lower limit is 40% by weight, a further preferable lower limit is 45% by weight, and a particularly preferable lower limit is 50% by weight. The upper limit of the gel fraction of the pressure-sensitive adhesive layer is not particularly limited, but if it is too high, the 90° peeling force of the pressure-sensitive adhesive sheet to glass will decrease, and bubbles will easily occur at the interface with the adherend in a high-temperature environment. , the preferred upper limit is 70% by weight.
In addition, the gel fraction of an adhesive layer can be measured as follows, for example.
The release film of the pressure-sensitive adhesive sheet is peeled off, and a flat rectangular shape of 50 mm x 25 mm is cut to prepare a test piece, and the weight _W1 of the test piece is measured. After immersing the test piece in toluene at 23° C. for 24 hours, the test piece is removed from the toluene using a 200-mesh stainless steel mesh and dried at 110° C. for 1 hour. The weight _W2 of the test piece after drying is measured, and the gel fraction is calculated by the following formula (1).
Gel fraction (% by weight)=100×(W ₂ −W ₀ )/(W ₁ −W ₀ ) (1)
(W ₀ : Weight of base material, W ₁ : Weight of test piece before immersion in toluene, W ₂ : Weight of test piece after immersion in toluene and drying)

The method for adjusting the gel fraction of the pressure-sensitive adhesive layer to the above range is not particularly limited. and a method of adjusting the type and amount of the system elastomer and the tackifier resin to be blended as necessary. In addition, a method of adjusting the type and amount of a crosslinking reaction initiator that causes a crosslinking reaction, a crosslinking aid that promotes crosslinking, etc., a method of adjusting the irradiation intensity and irradiation time of UV light, which is an energy source that promotes crosslinking, A method of adjusting the irradiation intensity, irradiation time and acceleration voltage of the line irradiation, a method of adjusting the type and amount of the cross-linking inhibitor, and the like are also included.
The method of cross-linking is not particularly limited. A method of cross-linking by irradiating the above-mentioned tackifying resin or the like, which is blended according to the above, with UV light. In addition, a method of cross-linking the above-mentioned styrene-based elastomer and the optionally-blended tackifying resin by electron beam irradiation, the above-mentioned styrene-based elastomer, and the optionally-blended tackifying resin, etc. with crosslinkable functional groups. may be grafted by electron beam irradiation and then crosslinked by heat. Among them, the chemical cross-linking method requires introduction of a functional group, and the functional group tends to increase the dielectric loss tangent of the pressure-sensitive adhesive sheet in a high frequency band. A cross-linking method and a cross-linking method by electron beam irradiation are preferable, and a cross-linking method by electron beam irradiation is more preferable.
Although the electron beam irradiation intensity in the method of cross-linking by electron beam irradiation is not particularly limited, it is preferably 250 kGy or more, and preferably 350 kGy or less.

The thickness of the pressure-sensitive adhesive layer is not particularly limited, but the preferred lower limit is 1 µm and the preferred upper limit is 300 µm. When the thickness of the pressure-sensitive adhesive layer is within this range, both sufficient adhesive strength and handleability can be achieved. A more preferable lower limit of the thickness of the pressure-sensitive adhesive layer is 2.5 μm, and a more preferable upper limit thereof is 200 μm.

The pressure-sensitive adhesive sheet of the present invention is a pressure-sensitive adhesive sheet having no substrate. That is, it is a non-support type adhesive sheet. By not having a base material, the pressure-sensitive adhesive sheet can avoid an increase in the dielectric loss tangent in the high-frequency band due to the base material, and the dielectric loss tangent in the high-frequency band is small. It can be suitably used even when the frequency of the transmission signal is increased. Moreover, not having a substrate is preferable from the viewpoint of cost, thinness, and optical properties.
The base material is generally used as a support for adhesive sheets, for example, resin film (e.g., polyethylene terephthalate film), foam (e.g., polyurethane foam, polyolefin foam, acrylic foam), metal Non-adhesive sheet materials such as foil, non-woven fabric, and paper.

The pressure-sensitive adhesive sheet of the present invention has a preferable upper limit of dielectric loss tangent at a frequency of 10 GHz of 0.005. If the dielectric loss tangent at the frequency of 10 GHz is 0.005 or less, the pressure-sensitive adhesive sheet can be suitably used even when the transmission signal has a high frequency. A more preferable upper limit of the dielectric loss tangent at the frequency of 10 GHz is 0.002, a more preferable upper limit is 0.0015, and a particularly preferable upper limit is 0.001. The lower limit of the dielectric loss tangent at the frequency of 10 GHz is not particularly limited, and the lower the better.
The dielectric loss tangent of the pressure-sensitive adhesive sheet at a frequency of 10 GHz conforms to JIS C2565, and is measured in the measurement mode of a TM mode resonator using, for example, a dielectric constant measuring device (for example, ADMS01Nc manufactured by AET Corporation). be able to.

The method for adjusting the dielectric loss tangent at the frequency of 10 GHz to the above range is not particularly limited. a method of introducing a substituent, a method of introducing a hydrocarbon group), a method of increasing the molecular volume (for example, a method of introducing an alicyclic structure), and the like. In addition, for the adhesive layer, a method of mixing a substance with a low dielectric loss tangent (for example, a method of blending a filler such as a hollow cell, a fluorine filler, a silica filler, or a glass fiber), a method of lowering the mobility of molecules (for example, a method of blending a crystalline polymer), a method of increasing the polymer molecular weight, a method of decreasing the water absorption or water content (for example, a method of introducing a fluorine atom or a substituent, a method of introducing a hydrocarbon group), and the like.

The pressure-sensitive adhesive sheet of the present invention has a lower limit of 90° peeling force to glass of 5 N/25 mm. If the 90° peeling force to the glass is 5 N/25 mm or more, the adhesive sheet is a pressure-sensitive adhesive sheet that does not have a base material, but has high adhesion even to an adherend that is likely to generate outgassing in a high-temperature environment. It exerts its strength and prevents foaming from occurring at the interface with the adherend even in a high-temperature environment. Examples of adherends that tend to generate outgassing under high-temperature environments include adherends made of cycloolefin polymer (COP) (eg, ZF16-100 μm available from Nippon Zeon Co., Ltd.). A preferable lower limit of the 90° peeling force to glass is 10 N/25 mm, and a more preferable lower limit is 12 N/25 mm. Although the upper limit of the 90° peeling force to the glass is not particularly limited, the practical limit is about 30 N/25 mm.
The 90° peel strength of the pressure-sensitive adhesive sheet to glass can be measured by performing a tensile test in the 90° direction at a peel speed of 50 mm/min in accordance with JIS Z0237 in an environment of 25°C.

The method of adjusting the 90° peeling force to the glass to the above range is not particularly limited. Examples include a method of adjusting the gel fraction of the agent layer, a method of modifying the surface of the pressure-sensitive adhesive layer by a plasma treatment method or a corona treatment method, and the like. In addition, a method of adding a coupling agent that covalently bonds with a glass adherend to the adhesive layer, a method of reducing the styrene content of the styrene elastomer, a method of increasing the diblock content of the styrene elastomer, and the adhesive. A method of increasing the thickness of the layer, a method of adding a filler to the pressure-sensitive adhesive layer to increase deformation resistance, and the like can also be used.

The haze of the pressure-sensitive adhesive sheet of the present invention is not particularly limited, but is preferably 5.0% or less, more preferably less than 1.0%. The color tone is also not particularly limited, but b* (b value) is preferably 0.5% or less, more preferably 0.3% or less. The pressure-sensitive adhesive sheet of the present invention preferably does not easily cause changes in optical properties such as yellowing even in a high-temperature environment, and preferably satisfies the above ranges for haze and b* (b value) even after exposure to high temperatures.
The haze and b* (b value) of the adhesive sheet can be measured using, for example, CM3700A manufactured by Konica Minolta.

The method for producing the pressure-sensitive adhesive sheet of the present invention is not particularly limited, and conventionally known methods can be used. For example, a pressure-sensitive adhesive solution containing the styrene-based elastomer and, if necessary, other additives such as the tackifying resin is applied onto a release-treated film, and dried to form a pressure-sensitive adhesive layer. , can be produced by laminating a release-treated film on the pressure-sensitive adhesive layer.

The use of the pressure-sensitive adhesive sheet of the present invention is not particularly limited, but it is preferably used for devices that transmit or receive electromagnetic waves. The apparatus for transmitting or receiving electromagnetic waves preferably includes a laminate containing the pressure-sensitive adhesive sheet of the present invention and a film having a conductive pattern formed thereon. That is, a laminate containing the pressure-sensitive adhesive sheet of the present invention and a film having a conductive pattern formed thereon is also one aspect of the present invention. A device for transmitting or receiving electromagnetic waves including the laminate of the present invention is also one aspect of the present invention.
The pressure-sensitive adhesive sheet of the present invention has a small dielectric loss tangent in a high frequency band and can be suitably used even when the transmission signal has a high frequency. more preferably. More specifically, the pressure-sensitive adhesive sheet of the present invention can be used in devices for transmitting or receiving electromagnetic waves having a frequency of 1 GHz or more, and can be used in the interior of a laminate (e.g., antenna film, substrate, etc.) containing a film on which a conductive pattern is formed. It is preferably used for bonding between members, or bonding a laminate including a film on which the conductive pattern is formed and another member.
Devices that transmit or receive electromagnetic waves with a frequency of 1 GHz or higher are not particularly limited, and examples include small antenna base stations, antennas such as in-vehicle antennas, smartphones, tablet terminals, other mobile electronic devices, in-vehicle electronic devices, smart glasses, etc. is mentioned.

FIG. 1 shows a cross-sectional view schematically showing how the pressure-sensitive adhesive sheet of the present invention is used to bond members inside a laminate including a film having a conductive pattern formed thereon.
In FIG. 1, internal members 21 and 22 are bonded together by the pressure-sensitive adhesive sheet 1 of the present invention in a laminate 2 including a film having a conductive pattern formed thereon. The laminate 2 including the film on which the conductive pattern is formed has additional members (for example,

members

23 and 24 as shown in FIG. 1) in addition to the pressure-sensitive adhesive sheet 1 and members 21 and 22 of the present invention. may
FIG. 2 shows a cross-sectional view schematically showing how a laminate including a film having a conductive pattern formed thereon is attached to another member using the pressure-sensitive adhesive sheet of the present invention.
In FIG. 2, a laminate 2 including a film having a conductive pattern formed thereon and another member 3 are bonded together with an adhesive sheet 1 of the present invention.

According to the present invention, a pressure-sensitive adhesive sheet that has a small dielectric loss tangent in a high frequency band and is unlikely to cause foaming at the interface with an adherend even in a high-temperature environment, a laminate using the pressure-sensitive adhesive sheet, and an electromagnetic wave are transmitted. Or a receiving device can be provided.

FIG. 2 is a cross-sectional view schematically showing a state in which the pressure-sensitive adhesive sheet of the present invention is used to bond members inside a laminate including a film having a conductive pattern formed thereon. FIG. 2 is a cross-sectional view schematically showing a state in which a laminate including a film having a conductive pattern formed thereon is attached to another member using the pressure-sensitive adhesive sheet of the present invention.

EXAMPLES The aspects of the present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these Examples.

<Hydrogenated styrene elastomer>
(Synthesis of radial type hydrogenated styrene elastomer B (Mw 300,000))
4000 g of degassed and dehydrated cyclohexane, 200 g of 1,3-butadiene monomer, 3.0 g of n-butyllithium (n-BuLi) and tetrahydrofuran (THF) in a molar ratio of n-BuLi/THF=40 in an autoclave added with Then, polymerization was carried out at the polymerization initiation temperature of 40° C. for 40 minutes, and 100 g of styrene monomer was added and polymerized for 60 minutes (aromatic alkenyl polymer block (A)). Then, 700 g of 1,3-butadiene monomer was added and polymerized for 150 minutes (diblock structure styrene block copolymer (AB)).
A 0.25 mol amount of tetrachlorosilane (SiCl ₄ ) was added as a coupling agent to the end of the polymer to carry out a coupling reaction of the diblock-structured styrenic block copolymer (AB). % of styrenic block copolymer was obtained.
This copolymer was diluted with purified and dried cyclohexane, adjusted to a polymer concentration of 5% by weight, and subjected to a hydrogenation reaction.

In the hydrogenation reaction, first, 1000 g of the copolymer solution was charged into a sufficiently dried 2 L autoclave equipped with a stirrer, deaerated under reduced pressure, replaced with hydrogen, and maintained at 90° C. with stirring.
Next, 50 ml of a cyclohexane solution containing 0.2 mmol of di-p-tolylbis(η-cyclopentadienyl)titanium and 10 ml of a cyclohexane solution containing 0.108 mmol of n-butyllithium (n-BuLi) were added at 0°C. , under a hydrogen pressure of 2.0 kg/cm ² and added to the copolymer solution in the autoclave.
Under stirring, the hydrogenation reaction is started at a hydrogen gas supply pressure of 0.7 MPa-Gauge and a reaction temperature of 80° C. When the absorption of hydrogen is completed, the reaction solution is returned to normal temperature and normal pressure, and extracted from the reaction vessel. , to obtain a radial type hydrogenated styrene elastomer (AB) ₄ C.
According to ¹ H-NMR analysis, 95% or more of the butadiene units and less than 5% of the styrene units of the obtained radial hydrogenated styrene elastomer (AB) ₄ C were hydrogenated.

A solution obtained by dissolving the obtained radial type hydrogenated styrene elastomer (AB) ₄ C in tetrahydrofuran (THF) was filtered through a filter (material: polytetrafluoroethylene, pore diameter: 0.2 μm), and a GPC test solution was obtained. got Waters "ACQUITY ^TM Advanced Polymer Chromatography ^TM System" as a GPC system, Waters "HSPgel ^TM HR MB-M (6.0 mm × 150 mm)" as a GPC column, and a differential refractive index detector as a detector. Then, GPC measurement was performed. The sample injection volume was 10 µL of a 20 mg/mL solution, the flow rate was 0.5 mL/min, and the column temperature was 40°C. Empower 3 attached to the apparatus was used as analysis software. Polystyrene (peak top molecular weight: 2110000, 1090000, 427000, 190000, 37900, 18100, 5970, 2420, 500) (manufactured by Tosoh Corporation) was used as a standard. Polystyrene was measured as a standard, and a calibration curve for converting the elution amount to polystyrene molecular weight was created and analyzed using analysis software. Using this calibration curve, the weight average molecular weight (Mw) was converted from the GPC elution volume.

(Synthesis of radial type hydrogenated styrene elastomer A (Mw 500,000))
In the same manner as in the synthesis of the radial type hydrogenated styrene elastomer B (Mw 300,000), A radial type hydrogenated styrene elastomer A (Mw 500,000) was obtained.

The following hydrogenated styrene elastomer was used.
・ABA type hydrogenated styrene elastomer “8300P” (SEBS, weight average molecular weight (Mw) 200,000, St content 9% by weight, manufactured by JSR)
・ABA type hydrogenated styrene elastomer “8903P” (SEBS, weight average molecular weight (Mw) 200,000, St content 35% by weight, manufactured by JSR)
・ABA type hydrogenated styrene elastomer “FG1924” (acid-modified SEBS, weight average molecular weight (Mw) 130,000, St content 13% by weight, manufactured by Kraton)
・ ABA type hydrogenated styrene elastomer “Septon 2063” (SEPS, weight average molecular weight (Mw) 200,000, St content 13% by weight, manufactured by Kuraray Co., Ltd.)
・ ABA type hydrogenated styrene elastomer “SIBSTAR 102T” (SIBS, weight average molecular weight (Mw) 100,000, St content 15% by weight, manufactured by Kaneka Corporation)

<Non-hydrogenated styrene elastomer>
The following non-hydrogenated styrene elastomer was used.
・(AB) _n C-type non-hydrogenated styrene elastomer “Quintac 3620” (SIS, weight average molecular weight (Mw) 230,000, St content 14% by weight, manufactured by ZEON)
・(AB) _n C-type non-hydrogenated styrene elastomer “DX222” (SBS, weight average molecular weight (Mw) 200,000, St content 20% by weight, manufactured by Kraton)

<Other resins>
The following other resins were used.
・ Polyisobutylene “OPPANOL N80” (weight average molecular weight (Mw) 550,000, manufactured by BASF)
・Acrylic polymer (weight average molecular weight (Mw) 1,200,000)
An acrylic polymer was synthesized according to the following procedure.

(Synthesis of acrylic polymer)
A reactor equipped with a thermometer, a stirrer, a cooling tube, and an ultraviolet irradiation device was charged with 39.9 parts by weight of 2-ethylhexyl acrylate, 30 parts by weight of cyclohexyl acrylate, 22 parts by weight of 4-hydroxybutyl acrylate, and 8 parts by weight of dimethylacrylamide as monomers. , and 0.1 part by weight of dimethylaminopropyl acrylamide. 0.05 part by weight of 2,2-dimethoxy-1,2-diphenylethan-1-one was added as a photopolymerization initiator to the monomer mixture, and nitrogen gas was blown in to replace the mixture with nitrogen. Next, the reactor is irradiated with ultraviolet rays until the viscosity (BH viscometer No. 5 rotor, 10 rpm, measurement temperature 25 ° C.) reaches about 4 Pa s, and the acrylic polymer precursor in which a part of the monomer mixture is polymerized got
2 parts by weight of 3-glycidoxypropyltrimethoxysilane and 0.05 parts by weight of 1,6-hexanediol diacrylate as a cross-linking agent and 2,2-dimethoxy as a photopolymerization initiator were added to the obtained acrylic polymer precursor. 0.15 parts by weight of -1,2-diphenylethan-1-one was added and stirred to obtain an acrylic polymer. As 3-glycidoxypropyltrimethoxysilane, Shin-Etsu Chemical Co., Ltd., KBM-403, Shin-Nakamura Chemical Co., Ltd., A-HD-N as 1,6-hexanediol diacrylate, 2,2- IGM RESINS B.I. as dimethoxy-1,2-diphenylethan-1-one. V. company product, Omnirad651 was used.

<Acrylic monomer>
The following acrylic monomers were used.
・ Acrylic monomer "TMP-A" (trimethylolpropane triacrylate, manufactured by Kyoeisha Chemical Co., Ltd.)

<Tackifying resin (T1) having no double bond>
The following tackifying resins were used.
・ Aliphatic hydrocarbon-based tackifying resin “Arcon P125” (softening point 125 ° C., SP value 8.1, manufactured by Arakawa Chemical Co., Ltd.)
・ Aliphatic hydrocarbon-based tackifying resin “Arcon P140” (softening point 140 ° C, SP value 8.1, manufactured by Arakawa Chemical Co., Ltd.)
・ Aliphatic hydrocarbon-based tackifying resin "Arcon P100" (softening point 100 ° C, SP value 8.1, manufactured by Arakawa Chemical Co., Ltd.)
・ Hydrogenated α-methylstyrene resin “Regalrez 1126” (softening point 126°C, SP value 8.2, manufactured by Eastman Chemical Co.)
・ Aliphatic hydrocarbon-based tackifying resin “Plastolyn R1140” (softening point 140 ° C., SP value 8.1, manufactured by Eastman Chemical Co.)

<Tackifying resin (T2) having at least one selected from the group consisting of double bonds and aromatic rings>
The following tackifying resins were used.
・ Terpene “PX100” (YS resin PX100) (softening point 100° C., SP value 8.3, manufactured by Yasuhara Chemical Co., Ltd.)
・ Aromatic modified terpene “TO105 (YS resin TO105)” (softening point 105°C, SP value 8.7, manufactured by Yasuhara Chemical Co., Ltd.)
· Rosin ester "KE311" (softening point 100 ° C, SP value 9.2, manufactured by Arakawa Chemical Co., Ltd.)
・Styrene copolymer “FTR6100” (softening point 110°C, SP value 9.3, manufactured by Mitsui Chemicals)
・ Styrene copolymer “FMR0150” (softening point 145 ° C., SP value 9.3, manufactured by Mitsui Chemicals, Inc.)

(Example 1)
(1) Production of Adhesive Sheet To 350 parts by weight of toluene, 100 parts by weight of a styrene-based elastomer and 30 parts by weight of a tackifying resin were added to obtain an adhesive solution. On the release-treated surface of a polyethylene terephthalate (PET) film with a thickness of 50 μm, which has been subjected to release treatment, the obtained adhesive solution was applied so that the thickness after drying was 25 μm, and then dried at 100 ° C. It was dried for 10 minutes to form an adhesive layer. After that, the same PET film was laminated on the side of the adhesive layer not laminated with the release-treated PET film so that the release-treated side faced the adhesive layer. Further, the adhesive layer was irradiated with an electron beam using an electron beam irradiation apparatus EBC-200 (manufactured by NHV Corporation) to crosslink the adhesive layer. At this time, the acceleration voltage was 150 kV and the electron beam irradiation intensity was 300 kGy. A pressure-sensitive adhesive sheet was thus obtained.

(2) Measurement of gel fraction of pressure-sensitive adhesive layer The release film of the pressure-sensitive adhesive sheet was peeled off and cut into a rectangular plane of 50 mm x 25 mm to prepare a test piece, and the weight _W1 of the test piece was measured. After the test piece was immersed in toluene at 23° C. for 24 hours, the test piece was removed from the toluene using a 200-mesh stainless steel mesh and dried at 110° C. for 1 hour. The weight _W2 of the test piece after drying was measured, and the gel fraction was calculated by the following formula (1).
Gel fraction (% by weight)=100×(W ₂ −W ₀ )/(W ₁ −W ₀ ) (1)
(W ₀ : Weight of base material, W ₁ : Weight of test piece before immersion in toluene, W ₂ : Weight of test piece after immersion in toluene and drying)

(3) Measurement of 90° Peel Force to Glass A pressure-sensitive adhesive sheet was cut to have a planar shape of 25 mm×100 mm. The release film on one side of the cut pressure-sensitive adhesive sheet was peeled off to expose the pressure-sensitive adhesive layer. Then, the exposed surface of the pressure-sensitive adhesive sheet was attached to a cycloolefin film (ZF16-100 μm available from Nippon Zeon Co., Ltd.). Further, the release film on the other side of the adhesive sheet was peeled off to expose the adhesive layer, and the exposed surface of the adhesive sheet was placed on a glass plate (float plate glass FL3 manufactured by Asahi Glass Co., Ltd.). The surface of the glass plate was washed with ethanol, wiped with a dry cloth, and used after visually confirming that there were no scratches. A 2.0 kg rubber roller was placed on the cycloolefin film, and the rubber roller was reciprocated once at a speed of 300 mm/min to bond the glass plate and the adhesive sheet together. After standing at 23°C for 24 hours, a test sample was prepared. bottom.
The resulting test sample was subjected to a tensile test in the 90° direction at a peeling speed of 50 mm/min according to JIS Z0237 under an environment of 25°C, and the 90° peeling force (N/25mm) against glass was measured.

(Examples 2 to 24, Comparative Examples 1 to 15)
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1, except that the composition of the pressure-sensitive adhesive layer was changed as shown in Tables 1 to 5 and the electron beam irradiation conditions were changed as follows.
The electron beam irradiation conditions were as follows: electron beam irradiation intensity of 400 kGy in Example 18, electron beam irradiation intensity of 100 kGy in Comparative Example 11, electron beam irradiation intensity of 200 kGy in Comparative Example 12, and electron beam irradiation intensity of 100 kGy in Comparative Example 13. , Comparative Example 14 was not subjected to electron beam irradiation.
In Comparative Example 15, an adhesive tape having a substrate was obtained by applying the obtained adhesive solution onto a substrate (polyethylene terephthalate film) having a thickness of 100 μm.

<Evaluation>
The adhesive sheets obtained in Examples and Comparative Examples were evaluated as follows. The results are shown in Tables 1-5.

(1) Measurement of dielectric constant and dielectric loss tangent at a frequency of 10 GHz After the pressure-sensitive adhesive sheets were allowed to stand at 23° C. and 50% RH for 72 hours (3 days) or more, a plurality of sheets were laminated to a thickness of 100 μm. The release film of the pressure-sensitive adhesive sheet after lamination was peeled off, and a PET film having a thickness of 50 μm was attached to the upper and lower surfaces. The laminate of the obtained PET film and adhesive sheet was cut into a width of 3 mm and a length of 80 mm, and the TM mode resonator was measured using a dielectric constant measuring device (manufactured by AET Co., Ltd., ADMS01Nc) in accordance with JIS C2565. Dielectric constant and dielectric loss tangent were measured in the measurement mode.
The dielectric constant and dielectric loss tangent of the PET film alone were also measured by the above methods, and the values of the adhesive sheet alone were obtained using the measured values of the laminate of the PET film and the adhesive sheet and the measured values of the PET film alone.
A when the dielectric loss tangent was less than 0.0008, B when it was 0.0008 or more and less than 0.0009, C when it was 0.0009 or more and less than 0.001, 0.001 or more and 0.001 or more. When it was less than 002, it was judged as D, when it was 0.002 or more and 0.005 or less, it was judged as E, and when it exceeded 0.005, it was judged as F.

(2) Evaluation of foaming under high temperature environment (foaming resistance)
The pressure-sensitive adhesive sheet was cut to have a planar shape of 60 mm x 60 mm. The release film on one side of the cut pressure-sensitive adhesive sheet was peeled off to expose the pressure-sensitive adhesive layer. Then, the exposed surface of the pressure-sensitive adhesive sheet was attached to a cycloolefin film (ZF16-100 μm available from Nippon Zeon Co., Ltd.). Further, the release film on the other side of the pressure-sensitive adhesive sheet was peeled off to expose the pressure-sensitive adhesive layer, and the exposed surface of the pressure-sensitive adhesive sheet was placed on a glass plate. A 2.0 kg rubber roller was placed on the cycloolefin film, and the rubber roller was reciprocated once at a speed of 300 mm/min to bond the glass plate and the adhesive sheet together, and left at 23°C for 24 hours to prepare a test sample. bottom.
The obtained test sample was heat-treated at 120°C for 60 minutes and then naturally cooled to 25°C. After that, the test sample was observed with an optical microscope from a direction perpendicular to the interface between the pressure-sensitive adhesive sheet, the glass plate, and the cycloolefin film.
The ratio of the total area of air bubbles present at the interface between the adhesive sheet and the glass plate and the cycloolefin film to the entire adhesive area was calculated by image analysis. A when the ratio of the total area of the bubbles was less than 1%, B when it was 1% or more and less than 5%, C when it was 5% or more and less than 10%, and 10% or more. The case was judged as D.

(3) Evaluation of optical properties The adhesive sheet was measured for haze and b* (initial) using CM3700A manufactured by Konica Minolta. After the adhesive sheet was exposed to a high temperature environment of 80° C. and 85% RH for 196 hours, haze and b* (after high temperature treatment) were measured in the same manner.
When the haze was less than 1.0% both initially and after the high temperature treatment, it was evaluated as ◯, and when at least one of the initial haze and the haze after the high temperature treatment was 1.0% or more, it was evaluated as x.
◎ when b * was 0.3% or less both initially and after high temperature treatment, and at least one of b * was greater than 0.3% initially and after high temperature treatment, but b A case where * was 0.4% or less was judged as ◯, and a case where at least one of b* exceeded 0.4% at the initial stage or after high temperature treatment was judged as x.

1 Adhesive sheet 2

Laminates

21, 22, 23, 24 including films on which conductive patterns are formed Members (internal members)
3 other members

Claims

A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer,
The pressure-sensitive adhesive layer contains a styrene-based elastomer as a base resin and has a gel fraction of 30% by weight or more,
A pressure-sensitive adhesive sheet, wherein the pressure-sensitive adhesive sheet has no base material and has a 90° peeling force against glass of 5 N/25 mm or more.
2. The pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive sheet has a dielectric loss tangent of 0.005 or less at a frequency of 10 GHz.
3. The adhesive sheet according to claim 1, wherein the styrene elastomer is a hydrogenated styrene elastomer.
4. The adhesive sheet according to claim 3, wherein the hydrogenated styrene elastomer is a hydrogenated block copolymer having an aromatic alkenyl polymer block and a conjugated diene polymer block.
1, 2, 3 or 3, wherein the pressure-sensitive adhesive layer further contains a tackifying resin, and the tackifying resin contains a tackifying resin (T1) having no double bond, 4. The pressure-sensitive adhesive sheet described in 4 above.
6. The pressure-sensitive adhesive sheet according to claim 5, wherein the tackifying resin consists only of a tackifying resin (T1) having no double bond.
The hydrogenated product of the block copolymer having the aromatic alkenyl polymer block and the conjugated diene polymer block is hydrogen of a radial type block copolymer having a structure represented by the general formula (AB) n C 5. The pressure-sensitive adhesive sheet according to claim 4, which is an additive.
A: Aromatic alkenyl polymer block B: Conjugated diene polymer block C: Component derived from coupling agent n: An integer of 3 or more
8. The adhesive sheet according to claim 1, 2, 3, 4, 5, 6 or 7, wherein the styrene-based elastomer has a weight average molecular weight (Mw) of 200,000 or more.
9. The pressure-sensitive adhesive sheet according to claim 1, 2, 3, 4, 5, 6, 7 or 8, wherein the styrene-based elastomer has a styrene content of 30% by weight or less.
1, 2, 3, 4, 5, 6, 7, wherein the pressure-sensitive adhesive layer contains 15 parts by weight or less of a (meth)acrylic monomer with respect to 100 parts by weight of the styrene elastomer. , 8 or 9.
7. The pressure-sensitive adhesive sheet according to claim 5, wherein the pressure-sensitive adhesive layer contains 20 parts by weight or more and 80 parts by weight or less of the tackifying resin with respect to 100 parts by weight of the base resin.
12. The pressure-sensitive adhesive sheet according to claim 1, which is used in a device that transmits or receives electromagnetic waves having a frequency of 1 GHz or more.
It is characterized by being used for bonding between members inside a laminate including a film having a conductive pattern formed thereon, or bonding a laminate including a film having a conductive pattern formed thereon to another member. The adhesive sheet according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12.
A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer,
The pressure-sensitive adhesive layer contains a styrene-based elastomer as a base resin and has a gel fraction of 30% by weight or more,
The pressure-sensitive adhesive sheet has no base material and has a 90° peeling force against glass of 5 N/25 mm or more,
The pressure-sensitive adhesive layer further contains a tackifying resin, and the tackifying resin consists only of a tackifying resin (T1) having no double bond,
The hydrogenated styrene elastomer is a hydrogenated block copolymer having an aromatic alkenyl polymer block and a conjugated diene polymer block,
The hydrogenated product of the block copolymer having the aromatic alkenyl polymer block and the conjugated diene polymer block is hydrogen of a radial type block copolymer having a structure represented by the general formula (AB) n C is an additive,
A pressure-sensitive adhesive sheet having a dielectric loss tangent of 0.002 or less at a frequency of 10 GHz.
A: Aromatic alkenyl polymer block B: Conjugated diene polymer block C: Component derived from coupling agent n: An integer of 3 or more
A laminate comprising the adhesive sheet according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 or 14 and a film having a conductive pattern formed thereon. body.
A device for transmitting or receiving electromagnetic waves, comprising the laminate according to claim 15 .