TW202313891A - Adhesive composition, adhesive layer, and adhesive sheet - Google Patents

Abstract

Provided are: an adhesive composition which can form an adhesive layer that has low permittivity and low dielectric loss in a high-frequency band, and which is suitable for bonding members constituting a millimeter-wave antenna; and an adhesive sheet. An adhesive composition according to the present invention comprises a mixture, partially polymerized product, or copolymer of a (meth)acrylate compound having a cross-linkable functional group and a methacrylate compound having a hydrocarbon group with six or more carbon atoms, the permittivity thereof at a frequency of 28 GHz or at a frequency of 60 GHz being 2.0-5.0.

Description

Adhesive composition, adhesive layer and adhesive sheet

The invention relates to an adhesive composition, an adhesive layer and an adhesive sheet. More specifically, the present invention relates to an adhesive composition, an adhesive layer, and an adhesive sheet suitable for bonding components of a millimeter-wave antenna.

In recent years, the high-speed and large-capacity communication in portable communication devices such as smartphones has been increasing year by year. Compared with 4G), it can achieve 100 times the ultra-high speed, large-capacity communication, 1/10 the low delay, and more than 10 times the number of simultaneous connections.

In order to realize the ultra-high-speed, large-capacity communication, low-latency, and multiple simultaneous connections in 5G, it is possible to use high-frequency electromagnetic waves with a frequency exceeding 24 GHz called millimeter waves, and shorten the wavelength to the millimeter level. Send large amounts of data at once.

On the other hand, compared with the frequency band used by 4G, millimeter wave is easy to attenuate due to resonance absorption with rain or oxygen in the air, water molecules, etc., and has strong linearity and easy reflection properties. The antenna used (hereinafter, sometimes referred to as "millimeter wave antenna") requires higher antenna gain than the previous 4G communication.

Patent Document 1 discloses a configuration in which a cover member is laminated on a substrate provided with an antenna element as a millimeter-wave antenna mounted on a portable communication device such as a smartphone, and an adhesive is applied to the substrate Fitting with the cover member.

As such an adhesive, for example, Patent Document 2 discloses an adhesive containing a monomer mixture including 2-ethylhexyl acrylate, a specific alkyl (meth)acrylate, and a hydroxyl-containing monomer. The polymer formed by polymerization can form an adhesive layer with a dielectric constant of 3.5 or less at a frequency of 100 kHz.

In addition, Patent Document 3 discloses an adhesive layer containing a specific acrylic polymer, a vinyl monomer having a polyalkylene oxide chain, a photopolymerization initiator, and a crosslinking agent, and at a frequency of 1 The relative permittivity at MHz is 3.5 or less. prior art literature patent documents

Patent Document 1: Japanese Patent Laid-Open No. 2019-186942 Patent Document 2: Japanese Patent Laid-Open No. 2015-183178 Patent Document 3: Japanese Patent Laid-Open No. 2020-007570

[Problem to be solved by the invention]

It is known that for the components that make up the millimeter wave antenna, because of the dielectric loss of the material, the millimeter wave will decrease. In order not to reduce the antenna gain, a low dielectric constant, especially a low dielectric constant in the high frequency band of the millimeter wave is also required. properties of loss. Low dielectric constant and low dielectric loss characteristics in high frequency bands are also required for the adhesive used to bond the components constituting the millimeter wave antenna.

Although the adhesive in Patent Document 2 has a low dielectric constant at low frequencies (100 kHz), the dielectric loss in high frequency bands is not low enough. Similarly, the adhesive layer in Patent Document 3 is also low in frequency (1 MHz) has a low relative permittivity, but the dielectric loss in the high frequency band is not low enough. Also, it is only a description related to the dielectric constant in the low frequency band, and does not disclose information related to the dielectric loss in the high frequency band, and does not provide a solution to the subject of the present application.

The present invention is conceived based on the above circumstances. The purpose of the present invention is to provide an adhesive composition that can be formed in a high-frequency band with low dielectric constant and dielectric loss, and is suitable for bonding to form millimeter waves. Adhesive layer for antenna components. Moreover, another object of the present invention is to provide an adhesive layer, which has low dielectric constant and dielectric loss in the high frequency band, and is suitable for laminating the components constituting the millimeter wave antenna. In addition, another object of the present invention is to provide an adhesive sheet, which has a low dielectric constant and dielectric loss in high frequency bands, and is suitable for bonding adhesive layers of components constituting millimeter wave antennas. [Technical means to solve the problem]

That is, the present invention provides an adhesive composition of the first aspect, which has a dielectric constant of 2.0 to 5.0 at a frequency of 28 GHz, a dielectric loss of 0.0001 to 0.05 at a frequency of 28 GHz, and contains A mixture of a methacrylate compound having 6 or more hydrocarbon groups, a (meth)acrylate compound having a crosslinkable functional group, a partial polymer or a copolymer thereof.

In the adhesive composition of the first aspect of the present invention, the composition having a dielectric constant of 2.0 to 5.0 at a frequency of 28 GHz can improve the antenna gain of a millimeter-wave antenna for bonding components using the adhesive composition better.

The adhesive composition of the first aspect of the present invention preferably has a dielectric constant of 2.0 to 5.0 at a frequency of 60 GHz. This configuration is preferable in that the antenna gain of the millimeter-wave antenna in which the constituent members are bonded using the adhesive composition of the first aspect of the present invention can be increased.

Also, the present invention provides an adhesive composition of the second aspect, which has a dielectric constant of 2.0 to 5.0 at a frequency of 60 GHz, a dielectric loss of 0.0001 to 0.05 at a frequency of 60 GHz, and contains A mixture of a methacrylate compound having 6 or more hydrocarbon groups, a (meth)acrylate compound having a crosslinkable functional group, a partial polymer or a copolymer thereof.

In the adhesive composition of the second aspect of the present invention, the composition having a dielectric constant of 2.0 to 5.0 at a frequency of 60 GHz can improve the antenna gain of a millimeter wave antenna that uses the above-mentioned adhesive composition to bond components. better.

The above-mentioned hydrocarbon group preferably has an aliphatic group, contains an alicyclic group, or contains an aromatic ring group.

The content of the above-mentioned methacrylate compound having a hydrocarbon group having 6 or more carbon atoms, or a structural unit derived from the compound in the above-mentioned mixture, its partial polymer or copolymer is preferably 25% by mass or more.

It is preferable that content of the said (meth)acrylate compound which has a crosslinkable functional group, or the structural unit derived from this compound in the said mixture, its partial polymer, or a copolymer is 0.1-30 mass %.

The above-mentioned hydrocarbon group preferably has an alicyclic group or an aromatic group at the terminal.

Moreover, this invention provides the adhesive agent layer formed from the said adhesive agent composition.

Moreover, this invention provides the adhesive sheet which has the said adhesive agent layer.

In addition, the present invention provides a millimeter wave antenna comprising at least the above-mentioned adhesive sheet and a substrate, wherein the above-mentioned substrate is provided with an antenna element on at least one side, and the above-mentioned Adhesive sheet. [Effect of Invention]

The adhesive composition and adhesive layer of the present invention can exhibit lower dielectric constant and dielectric loss in the high frequency band of millimeter waves, and suppress the radiation loss of millimeter waves to a lower level. Therefore, by bonding the constituent members of the millimeter-wave antenna using the adhesive sheet of the present invention, it is possible to efficiently manufacture a millimeter-wave antenna exhibiting higher antenna gain.

[adhesive composition] The adhesive composition of the first aspect of the present invention has a dielectric constant of 2.0 to 5.0 at a frequency of 28 GHz, a dielectric loss of 0.0001 to 0.05 at a frequency of 28 GHz, and contains a hydrocarbon group having 6 or more carbon atoms. A mixture of a methacrylate compound and a (meth)acrylate compound having a crosslinkable functional group, a partial polymer or a copolymer thereof.

The adhesive composition of the second aspect of the present invention has a dielectric constant of 2.0 to 5.0 at a frequency of 60 GHz, a dielectric loss of 0.0001 to 0.05 at a frequency of 60 GHz, and contains a hydrocarbon group having 6 or more carbon atoms. A mixture of a methacrylate compound and a (meth)acrylate compound having a crosslinkable functional group, a partial polymer or a copolymer thereof.

The adhesive composition of the present invention may have any form, for example, solvent type, emulsion type, heat-melt type (hot-melt type), solvent-free type (active energy ray hardening type, such as monomer mixture, or single body mixture and its part of the polymer, etc.) and so on.

As mentioned above, the adhesive composition of the present invention may be a solvent type, that is, may contain an organic solvent.

As the above-mentioned organic solvent, as long as it is an organic compound that can be used as a solvent, for example: hydrocarbon-based solvents such as cyclohexane, hexane, heptane, and methylcyclohexane; aromatic solvents such as toluene and xylene; Solvents; ester solvents such as butyl acetate, ethyl acetate, and methyl acetate; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; methanol, ethanol, propanol, butanol, isopropanol Alcohol-based solvents, etc. The above-mentioned organic solvent may be a mixed solvent containing two or more organic solvents.

The dielectric constant of the adhesive composition of the first aspect of the present invention is controlled to be low at 28 GHz, and the radiation loss of millimeter waves can be suppressed. The dielectric constant of the adhesive composition according to the first aspect of the present invention at a frequency of 28 GHz is 5.0 or less, preferably 4.5 or less, more preferably 4.0 or less, further preferably 3.5 or less, still more preferably 3.4 or less , preferably less than 3.3, most preferably less than 3.2, less than 3.1, less than 3.0 or less than 2.9. The lower limit is not particularly limited, and may be 2.0 or more, and may be 2.1 or more or 2.2 or more. Also, it is preferable that the dielectric constant of the adhesive composition of the second aspect at a frequency of 28 GHz is within the above-mentioned range.

In this specification, the dielectric constant is measured by the method described in the examples disclosed below. Furthermore, "relative permittivity" is a value obtained by dividing "dielectric constant" by "vacuum permittivity", but since "vacuum permittivity" is 1, in this specification, "dielectric constant" It is treated as a synonym with "relative permittivity". Also, the adhesive composition of the first aspect of the present invention and the adhesive composition of the second aspect of the present invention may be collectively referred to as "the adhesive composition of the present invention".

In the adhesive composition of the first aspect of the present invention, it is preferable that the dielectric loss at 28 GHz is controlled to be low, and it is preferable that the radiation loss of millimeter waves can be suppressed. The dielectric loss of the adhesive composition according to the first aspect of the present invention at a frequency of 28 GHz is 0.050 or less, preferably 0.045 or less, more preferably 0.040 or less, further preferably 0.035 or less, still more preferably 0.030 or less , preferably less than 0.025, most preferably less than 0.020. The lower limit may be not less than 0.0001, and may be not less than 0.0005 or not less than 0.0010. Also, it is preferable that the dielectric loss of the adhesive composition of the second aspect of the present invention at a frequency of 28 GHz is within the above-mentioned range.

The dielectric constant of the adhesive composition of the second aspect of the present invention is controlled to be low at 60 GHz, and the radiation loss of millimeter waves can be suppressed. The dielectric constant of the adhesive composition of the second aspect of the present invention at a frequency of 60 GHz is 5.0 or less, preferably 4.5 or less, more preferably 4.0 or less, still more preferably 3.5 or less, still more preferably 3.4 or less , preferably less than 3.3, most preferably less than 3.2, less than 3.1, less than 3.0 or less than 2.9. The lower limit is not particularly limited, and may be 2.0 or more, and may be 2.1 or more or 2.2 or more. In addition, it is preferable that the dielectric constant of the adhesive composition of the first aspect of the present invention at a frequency of 60 GHz is within the above-mentioned range.

In the adhesive composition of the second aspect of the present invention, it is preferable that the dielectric loss at 60 GHz is controlled to be low, and it is preferable that the radiation loss of millimeter waves can be suppressed. The dielectric loss of the adhesive composition of the second aspect of the present invention at a frequency of 60 GHz is 0.050 or less, preferably 0.045 or less, more preferably 0.040 or less, still more preferably 0.035 or less, still more preferably 0.030 or less , especially preferably 0.025 or less, most preferably 0.020 or less, 0.019 or less, 0.018 or less, 0.017 or less, 0.016 or less, 0.015 or less, 0.014 or less, 0.013 or less, or 0.012 or less. The lower limit of the dielectric loss at a frequency of 60 GHz is above 0.0001, and may be above 0.0005 or above 0.0010. Also, it is preferable that the dielectric loss of the adhesive composition of the first aspect of the present invention at a frequency of 60 GHz is within the above-mentioned range.

The adhesive composition of the present invention preferably has a lower saturated moisture absorption rate. If the saturated moisture absorption rate is low, the attenuation of resonance absorption of millimeter waves originating from water molecules can be suppressed, so it has excellent water resistance when used as an adhesive layer in millimeter wave antennas, etc., and can suppress millimeter waves. Radiation loss is better. The saturated moisture absorption rate of the adhesive composition of the present invention at 25°C and 90% R.H. is preferably 2.8% or less, more preferably 2.7% or less, further preferably 2.6% or less, and even more preferably 2.5% or less. Especially preferably less than 2.4%, most preferably less than 2.3%, less than 2.2%, less than 2.1%, less than 2.0%, less than 1.9%, less than 1.8%, less than 1.7%, less than 1.6%, less than 1.5%, less than 1.4%, Less than 1.3%, less than 1.2%, less than 1.1%, less than 1.0%, less than 0.9%, less than 0.8%, less than 0.7%, or less than 0.6%. If the saturated moisture absorption rate at 25°C and 90% R.H. is low, the radiation loss of millimeter waves near room temperature can be suppressed. The lower limit of the saturated moisture absorption rate is not particularly limited, for example, it may be 0.3% or more, 0.4% or 0.5% or more.

The saturated moisture absorption rate of the adhesive composition of the present invention at 65°C and 90% R.H. is preferably less than 2.8%, more preferably less than 2.6%, further preferably less than 2.4%, and even more preferably less than 2.3%. Especially preferably less than 2.2%, most preferably less than 2.1%, less than 2.0%, less than 1.9%, less than 1.8%, less than 1.7%, less than 1.6%, less than 1.5%, less than 1.4%, less than 1.3%, less than 1.2%, Less than 1.1%, less than 1.0%, less than 0.9%, less than 0.8%, or less than 0.7%. The lower limit of the saturated moisture absorption rate is not particularly limited, for example, it may be 0.4% or more, or 0.5% or more, or 0.6% or more. If the saturated moisture absorption rate at 65°C and 90% R.H. is low, the radiation loss of millimeter waves can be suppressed even when placed in a high-temperature environment with an adhesive layer or the like applied.

The saturated moisture absorption rate of the adhesive composition of the present invention at 85°C and 85% R.H. is preferably 5.0% or less, more preferably 4.0% or less, further preferably 3.5% or less, and even more preferably 3.0% or less, Especially preferably 2.8% or less, most preferably 2.6% or less, 2.4% or less, 2.2% or less, 2.0% or less, 1.8% or less, 1.6% or less, 1.4% or less, 1.2% or less, 1.0% or less, or 0.8% or less. The lower limit of the saturated moisture absorption rate is not particularly limited, for example, it may be 0.4% or more, or 0.5% or more, or 0.6% or more. If the saturated moisture absorption rate at 85°C and 85% R.H. is low, the radiation loss of millimeter waves can be suppressed even when placed in a high-temperature environment with an adhesive layer applied.

The above-mentioned saturated moisture absorption rate under various temperature and humidity environments can be obtained, for example, from the weight of the sample in a dry state (w1) and the point at which the weight change stops when the sample is placed in an atmosphere of 65°C and 90% R.H. (saturated moisture absorption rate time) weight (w2) can be obtained by the following formula. It can also be obtained under the conditions of 25°C, 90%R.H. and 85°C, 85%R.H. Furthermore, the values of w1 and w2 are those measured under the same temperature and humidity. Saturation moisture absorption rate (%)={(w2－w1)/w1}×100

In the adhesive composition of the present invention, it is preferable that the amount of change in dielectric loss caused by moisture absorption is controlled to be low, and it is preferable in that it can suppress the radiation loss of millimeter waves and its change over time. The change in the dielectric loss of the adhesive composition of the present invention at a frequency of 28 GHz due to moisture absorption is preferably 0.006 or less, more preferably 0.005 or less, and still more preferably 0.004 or less. The lower limit of the variation of the dielectric constant due to moisture absorption is not particularly limited, and may be, for example, 0.0001 or more, 0.0002 or 0.0003 or more.

The change in the dielectric loss of the adhesive composition of the present invention at a frequency of 60 GHz due to moisture absorption is preferably 0.003 or less, more preferably 0.002 or less, and still more preferably 0.001 or less. The lower limit of the change in dielectric constant caused by moisture absorption is not particularly limited, for example, it may be 0.0001 or more, or 0.0002 or more, 0.0003 or more, 0.0004 or more, 0.0005 or more, 0.0006 or more, 0.0007 or more, 0.0008 or more, or Above 0.0009.

The variation of dielectric loss at the above frequency of 28 GHz and 60 GHz can be kept at 65°C, 90%RH for more than 5 days, and then restored to 23±1°C, 52%±1%RH (Elapsed time = 0 minutes), after 4 minutes to 180 minutes, measure the dielectric loss at each frequency every 10 minutes, from the maximum value (D _fmax ) and minimum value (D _fmin ), by Calculated by the following formula. Variation of dielectric loss = D _fmax - D _fmin

The adhesive composition of the present invention can suppress the movement of water molecules in the adhesive composition because the water vapor permeability is controlled to be low, and can suppress the change of the radiation loss of millimeter waves. The water vapor permeability of the adhesive composition of the present invention at 40°C and 92% RH is preferably 430 g/m ² /day or less, more preferably 300 g/m ² /day or less, and still more preferably 250 g /m ² /day or less, more preferably 200 g/m ² /day or less, particularly preferably 150 g/m ² /day or less, most preferably 100 g/m ² /day or less, 50 g/m ² /day day or less than 30 g/m ² /day. The lower limit of the water vapor permeability is not particularly limited, and may be, for example, not less than 10 g/m ² /day, or not less than 20 g/m ² /day, or not less than 25 g/m ² /day.

The above water vapor transmission rate (Water Vapor Transmission Rate; WVTR) is based on the value measured by the cup method. It can be obtained by measuring the weight (w1) of the dry state of calcium chloride isolated from the outside in the adhesive layer, and placing the sample in an atmosphere of 40°C and 92%RH for a specified period of time The weight (w2) at the time point (when the moisture absorption rate is saturated), the weight change is converted into the unit time (1 day) and the unit area of the adhesive layer (1 m ² ).

The dielectric constant or dielectric loss of the adhesive composition of the present invention at 28 GHz or 60 GHz, the saturated moisture absorption rate, the change in dielectric loss caused by moisture absorption, and the water vapor permeability can be adjusted by adjusting the monomer Adjust the composition, type or content of additives, etc. In this specification, the dielectric constant or dielectric loss at 28 GHz or 60 GHz is measured by the method described in the examples disclosed below.

Furthermore, the dielectric constant, dielectric loss, saturated moisture absorption rate, and water vapor permeability of the adhesive composition of the present invention refer to the dielectric constant, dielectric loss, and dielectric constant of the adhesive layer formed from the adhesive composition of the present invention. , and saturated moisture absorption rate and water vapor permeability.

The adhesive composition of the present invention can control the dielectric constant and dielectric loss at high frequency bands by including a mixture of specific methacrylate compounds and (meth)acrylate compounds, or part of their polymers or copolymers. The value is lower, and the moisture absorption which is the cause of the deterioration of the dielectric loss is suppressed. In addition, the said "mixture, its partial polymer, or copolymer" may be called a methacrylic-type copolymer. Also, the "methacrylate compound" is a compound having a "methacryl group", and the "(meth)acrylate compound" is a compound having at least one of an "acryl group" and a "methacryl group". compound of those. Also, "(meth)acrylic acid" means either or both of "acrylic acid" and "methacrylic acid".

The above-mentioned partial polymer means a composition in which one or two or more monomer components constituting the above-mentioned mixture are partially polymerized.

The content of the above-mentioned methacrylic copolymer in the adhesive composition of the present invention is not particularly limited, but is preferably at least 75% by mass (for example, 75 to 99.9% by mass), more preferably at least 85% by mass (for example, 85 to 99.9% by mass). 99.9% by mass).

[Mixture, its partial polymer or copolymer (methacrylic copolymer)] The adhesive composition of the present invention is a methacrylic adhesive composition using a mixture, a partial polymer thereof, or a copolymer (methacrylic copolymer) as a base polymer. The content of the above-mentioned methacrylic copolymer is not particularly limited, but it is preferably 75% by mass or more (for example, 75 to 99.9% by mass), preferably 85% by mass relative to 100% by mass of the adhesive composition of the present invention. % or more (for example, 85 to 99.9% by mass).

As the adhesive composition of the present invention, for example, a water-dispersed composition (emulsion type composition) containing the above-mentioned copolymer as an essential component, or an active energy ray containing the above-mentioned mixture or a partial polymer thereof as an essential component Among them, curable compositions and the like are preferably compositions containing a mixture or a partial polymer thereof as an essential component.

The methacrylic copolymer of the present invention contains a methacrylate compound having a hydrocarbon group having 6 or more carbon atoms and a (meth)acrylate compound having a crosslinkable functional group as constituent monomers.

<Methacrylate compound having a hydrocarbon group with 6 or more carbon atoms> The methacrylate compound used for the above-mentioned methacrylic copolymer contains a hydrocarbon group having 6 or more carbon atoms. The hydrocarbon group having 6 or more carbon atoms in the methacrylate compound preferably has an aliphatic group, contains an alicyclic group, or contains an aromatic ring group. The methacrylate compound which has these hydrocarbon groups can be used individually or in combination of 2 or more types.

Since the above-mentioned methacrylic copolymer has an α-methyl group derived from a methacrylate compound as its main structural unit, compared with the case derived from an acrylate compound, the polarization near the main chain is reduced. As a result, it is considered that Dielectric loss is reduced. In addition, methacryl group has higher hydrophobicity than acryl group and suppresses moisture absorption, so it is possible to suppress deterioration and change in dielectric loss in high frequency bands caused by moisture absorption.

If the above-mentioned methacrylate compound has an alicyclic group or an aromatic group, it is easy to obtain moderate cohesive force in the methacrylic copolymer, and it is easy to obtain strong adhesiveness. In addition, it is easy to obtain excellent foaming and peeling resistance by increasing the gel fraction. Furthermore, it is easy to obtain moderate flexibility in the adhesive layer, and it is easy to obtain excellent stress relaxation property and excellent step followability.

When the above-mentioned hydrocarbon group having 6 or more carbon atoms is an aliphatic group, the number of carbon atoms in the above-mentioned hydrocarbon group is preferably 8 or more, more preferably 9 or more, and still more preferably 10 or more. The number of carbon atoms in the hydrocarbon group is preferably 22 or less, more preferably 20 or less, and still more preferably 16 or less.

Examples of methacrylate compounds in which the hydrocarbon group having 6 or more carbon atoms is an aliphatic group include hexyl methacrylate, heptyl methacrylate, octyl methacrylate, and 2-ethylhexyl methacrylate. ester, isooctyl methacrylate, nonyl methacrylate, isononyl methacrylate, decyl methacrylate, isodecyl methacrylate, undecyl methacrylate, lauryl methacrylate, Tridecyl Methacrylate, Myristyl Methacrylate, Pentadecyl Methacrylate, Hexadecyl Methacrylate, Heptadecyl Methacrylate, Octadecyl Methacrylate Alkyl esters, isostearyl methacrylate, stearyl methacrylate, nonadecyl methacrylate, eicosyl methacrylate, etc. Among them, lauryl methacrylate, tridecyl methacrylate, and isodecyl methacrylate are preferable.

The content of the methacrylate compound in which the hydrocarbon group having 6 or more carbon atoms is an aliphatic group in the methacrylic copolymer of the present invention is not particularly limited, but is preferably 25% by mass relative to 100% by mass of all structural units More preferably, it is 25.0-99.5 mass %, More preferably, it is 30.0-99.3 mass %, More preferably, it is 40.0-99.0 mass %. From the viewpoint of low dielectric constant and low dielectric loss in high frequency bands, it is preferable to use 25% by mass or more.

When the above-mentioned hydrocarbon group having 6 or more carbon atoms contains an alicyclic group, the number of carbon atoms in the above-mentioned hydrocarbon group is preferably 6 or more, more preferably 8 or more. The carbon number in the above-mentioned hydrocarbon group is preferably 22 or less, more preferably 16 or less.

Examples of methacrylate compounds in which the above-mentioned hydrocarbon group having 6 or more carbon atoms is an alicyclic group include: ) cycloalkyl methacrylates, methacrylates with bicyclic hydrocarbon rings (pinane, pinene, alkanes, nor-alkanes, nor-camphenes, etc.), and aliphatic hydrocarbons with more than three rings Ring (dicyclopentane ring, dicyclopentene ring, adamantane ring, tricyclopentane ring, tricyclopentene ring, etc.) methacrylate, etc.

Examples of the cycloalkyl methacrylate include cyclohexyl methacrylate, 3,3,5-trimethylcyclohexyl methacrylate, cycloheptyl methacrylate, and cyclooctyl methacrylate. Esters etc.

As the methacrylate having the above-mentioned bicyclic hydrocarbon ring, methacrylate, isomethacrylate, etc. may, for example, be mentioned.

Examples of methacrylates having hydrocarbon rings having three or more rings include: dicyclopentyl methacrylate, dicyclopentyloxyethyl methacrylate, tricyclopentyl methacrylate, 1- Adamantyl ester, 2-methyl-2-adamantyl methacrylate, 2-ethyl-2-adamantyl methacrylate, and the like.

When the above-mentioned hydrocarbon group having 6 or more carbon atoms is an aromatic ring group, the carbon number in the above-mentioned hydrocarbon group is preferably 6-14, more preferably 6-10.

The above-mentioned hydrocarbon group having 6 or more carbon atoms is a methacrylate compound containing an aromatic ring group, for example, one having an aromatic carbocycle (such as a monocyclic carbocycle such as a benzene ring, or a condensed carbocycle such as a naphthalene ring, etc.) Specific examples of the compound include: benzyl methacrylate, phenyl methacrylate, naphthyl methacrylate, 6-(1,1'-biphenyl-4-oxy)hexyl methacrylate Esters etc.

In the methacrylic copolymer of the present invention, the total content of the above-mentioned hydrocarbon group having 6 or more carbon atoms as an alicyclic group-containing or aromatic ring-containing methacrylate compound is not particularly limited, and is 100% by mass relative to all structural units. , preferably 1.0 to 60.0 mass %, more preferably 5.0 to 55.0 mass %, further preferably 10.0 to 50.0 mass %.

The above-mentioned methacrylate compound may have a (poly)oxyalkylene chain. When having a (poly)oxyalkylene chain, it is preferable to have the said hydrocarbon group of 6 or more carbon atoms at the terminal of the ester part in the said methacrylate compound. The number of oxygen atoms in the (poly)oxyalkylene chain (ie, the number of repetitions of the oxyalkylene group) is preferably 1-10, more preferably 1-3. The above-mentioned hydrocarbon group having 6 or more carbon atoms at the terminal may be any of aliphatic group, alicyclic group, and aromatic group, but is preferably an alicyclic group or an aromatic group, and is particularly preferably an aromatic group.

The content of the above-mentioned methacrylate compound having a (poly)oxyalkylene chain in the methacrylic copolymer of the present invention is not particularly limited, but is preferably 1.0 to 30.0% by mass relative to 100% by mass of all structural units %, more preferably 5.0 to 25.0 mass %, still more preferably 10.0 to 20.0 mass %.

In the above-mentioned methacrylate compound having a (poly)oxyalkylene chain, when there is an aromatic group at the end, the polarizability of the repeating unit as a whole is lowered, so the dielectric strength lowered in the high frequency band Loss is more effective.

The total content of the methacrylate compounds having a hydrocarbon group having 6 or more carbon atoms in the methacrylic copolymer is preferably at least 25% by mass, more preferably 25.0 to 99.5% by mass, based on 100% by mass of all structural units. %, more preferably 30.0 to 99.3% by mass, particularly preferably 40.0 to 99.0% by mass. From the viewpoint of low dielectric constant and low dielectric loss in high frequency bands, it is preferable to use 25% by mass or more.

＜(Meth)acrylate Compounds Containing Crosslinkable Functional Groups＞ The above-mentioned methacrylic copolymer contains a crosslinkable functional group-containing (meth)acrylate compound having a crosslinkable functional group in the ester portion, so when a crosslinking agent is used, crosslinking occurs and the coagulation is increased. Adhesive fraction, easy to obtain excellent resistance to foaming and peeling. Also, since it is easy to obtain good cohesive force, it is easy to obtain strong adhesiveness. Furthermore, it is easy to suppress whitening of the adhesive sheet which occurs in a high-humidity environment.

Examples of the crosslinkable functional group contained in the above-mentioned crosslinkable functional group-containing (meth)acrylate compound include hydroxyl group, carboxyl group, acid anhydride group, and glycidyl group from the viewpoint of easy adjustment of the gel fraction. Such as groups containing epoxy groups, isocyanate groups, aziridinyl groups, etc. Among them, a hydroxyl group is preferable from the viewpoint of easy adjustment of the gel fraction. The said crosslinkable functional group containing (meth)acrylate compound can be used individually or in combination of 2 or more types.

Examples of the crosslinkable functional group-containing (meth)acrylate compound having a hydroxyl group include: 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, (meth)acrylate ) 2-hydroxybutyl acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, hydroxyoctyl (meth)acrylate, Hydroxydecyl (meth)acrylate, hydroxylauryl (meth)acrylate, 4-hydroxymethylcyclohexyl (meth)acrylate, etc. Among them, 2-hydroxyethyl (meth)acrylate is preferred from the viewpoints of easily obtaining good cohesive force and adhesive reliability at high temperature.

The content of the crosslinkable functional group-containing (meth)acrylate compound in the methacrylic copolymer of the present invention is preferably 0.1 to 30.0 mass %, more preferably 0.2 mass %, relative to 100 mass % of all structural units. ~20.0 mass%, More preferably, it is 0.3-10.0 mass%, Most preferably, it is 0.5-5.0 mass%. From the viewpoint of adjusting the gel fraction, it is preferable to use 0.1 mass % or more, and it is preferable to use 30.0 mass % or less from the viewpoint of low dielectric constant and low dielectric loss in a high frequency band.

＜Copolymerizable monomer＞ The above-mentioned methacrylic copolymer may contain a copolymerizable monomer in addition to the above-mentioned methacrylate compound having a hydrocarbon group having 6 or more carbon atoms and the crosslinkable functional group-containing (meth)acrylate compound. A copolymerizable monomer can be used individually or in combination of 2 or more types.

Examples of the above-mentioned copolymerizable monomers include: acrylate compounds having a hydrocarbon group having 1 to 24 carbons, methacrylate compounds having a hydrocarbon group having 1 to 5 carbons, and all carbons in the repeating unit of the main chain having side Chain substituted methylene compounds, heterocycle-containing monomers, carboxyl-containing monomers, nitrile-containing monomers, isocyanate-containing monomers, amide-containing monomers, amine-containing monomers, having 5 carbon atoms The following alkoxy alkoxyalkyl (meth)acrylates, sulfonic acid group-containing monomers, phosphoric acid group-containing monomers, vinyl esters (vinyl acetate, vinyl propionate, etc.), aromatic vinyl series Compounds (styrene, vinyl toluene, etc.), olefins or dienes (ethylene, propylene, butadiene, isoprene, isobutylene, etc.), vinyl ethers (vinyl alkyl ether, etc.), vinyl chloride, Vinyl alcohol, macromonomers with a weight average molecular weight of 30,000 or less, polyfunctional monomers with two or more polymerizable functional groups, etc. These can be used individually or in combination of 2 or more types.

Furthermore, the adhesive composition of the present invention preferably does not contain or substantially does not contain acidic group-containing monomers (such as carboxyl group-containing monomers, sulfo group-containing monomers, phosphoric acid group-containing monomers, etc.). This configuration is preferable in that an excellent anti-corrosion effect on antenna elements and wiring can be obtained. Furthermore, relative to the total amount of the above-mentioned adhesive composition, the content of the acidic group-containing monomer is preferably 0.05% by weight or less (such as 0-0.05% by weight), more preferably 0.01% by weight or less (such as 0-0.01% by weight ), and more preferably 0.001% by weight or less (for example, 0 to 0.001% by weight) can be regarded as substantially free.

Among the above-mentioned copolymerizable monomers, heterocyclic monomers, carboxyl-containing monomers, amide-containing monomers, amine-containing monomers, sulfonic acid-containing monomers, and phosphoric acid-containing monomers are easily available in the adhesive layer Moderate cohesion is better in terms of easily increasing the 180° peeling adhesion to glass plates or acrylic plates to obtain strong adhesion. From the perspective of preventing metal corrosion, heterocyclic monomers are more preferred.

Examples of the methacrylate compound having a hydrocarbon group having 1 to 5 carbon atoms include methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, and pentyl methacrylate. ester, isopropyl methacrylate, isobutyl methacrylate, second butyl methacrylate, third butyl methacrylate, isoamyl methacrylate, etc.

Examples of the acrylate compound having a hydrocarbon group having 1 to 24 carbon atoms include methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, isobutyl acrylate, and second butyl acrylate. ester, tertiary butyl acrylate, pentyl acrylate, isopentyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, decyl acrylate, Isodecyl Acrylate, Undecyl Acrylate, Lauryl Acrylate, Lauryl Acrylate, Tridecyl Acrylate, Myristyl Acrylate, Pentadecyl Acrylate, Hexadecyl Acrylate , heptadecyl acrylate, stearyl acrylate, isostearyl acrylate, stearyl acrylate, nonadecyl acrylate, eicosyl acrylate, cyclohexyl acrylate, acrylate 3,3, 5-trimethylcyclohexyl, cycloheptyl acrylate, cyclooctyl acrylate, methacrylate, isomethacrylate, dicyclopentanyl acrylate, dicyclopentyloxyethyl acrylate, tricyclopentanyl acrylate, 1-acrylate Adamantyl acrylate, 2-methyl-2-adamantyl acrylate, 2-ethyl-2-adamantyl acrylate, phenyl acrylate, naphthyl acrylate, 6-(1,1'-biphenyl acrylate Base-4-oxy)hexyl ester, etc.

The above-mentioned heterocyclic monomer system has a heterocyclic copolymerizable monomer such as the following: a heterocyclic ring having only a nitrogen atom as a heteroatom (pyrrolidine, pyrrole, imidazole, pyrazole, piperidine, pyridine, pyrimidine, pyrroline, piperidine, etc.) 𠯤, pyridone, etc.), heterocycles with nitrogen and oxygen atoms (pyrrolidone, oxazole, isoxazole, morpholine, morpholone, piperidone, lactam, 㗁𠯤, morpholinedione , succinimide, imine, etc.), heterocycles with nitrogen and sulfur atoms (thiazole, isothiazole, thiamine, etc.), heterocycles with oxygen atoms (lactone, tetrahydrofuran, furan, tetrahydropiper Furan, dioxane, etc.), heterocycles with sulfur atoms (tetrahydrothiophene, thiophene, tetrahydrothiopyran, thiopyran, etc.).

If the methacrylic acid-based copolymer of the present invention contains a heterocyclic monomer, moderate flexibility can be obtained in the adhesive layer, and excellent stress relaxation and excellent step followability can be easily obtained.

As the heterocyclic ring-containing monomer having the above-mentioned heterocyclic ring having only a nitrogen atom as a heteroatom, for example, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperidine 𠯤, N-vinylpyrrole, N-vinylpyrrole, N-vinylimidazole, N-(meth)acrylpiperidine, N-(meth)acrylpyrrolidine, N-vinylpyrrole azole etc.

As the heterocycle-containing monomer having the above-mentioned heterocycle having a nitrogen atom and an oxygen atom as a heteroatom, for example, N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N- (Meth)acryl-2-pyrrolidone, N-vinylxazole, N-vinylisoxazole, N-vinylmorpholine, N-vinyl-3-morpholinone, N-vinyl N-2-caprolactamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-vinyl-1,3-㗁𠯤 -2-ketone, N-vinyl-3,5-morpholinedione, N-(meth)acryloxymethylenesuccinimide, N-(meth)acryl-6- Oxyhexamethylene succinimide, N-(meth)acryl-8-oxyhexamethylene succinimide, N-methyl succinimide, N-ethyl succinimide Amines, N-butylimide, N-octylimide, N-2-ethylhexylimide, N-cyclohexylimide, N-laurylimide, and the like.

Examples of the heterocyclic ring-containing monomer having a heterocyclic ring containing a nitrogen atom and a sulfur atom as a heteroatom include N-vinylthiazole and N-vinylisothiazole.

Among these, N-vinyl-2-pyrrolidone is particularly preferred.

As said carboxyl group-containing monomer, (meth)acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, methacrylic acid, etc. are mentioned, for example. Moreover, acid anhydride group containing monomers, such as maleic anhydride and itaconic anhydride, are contained in the said carboxyl group containing monomer, for example. Moreover, for example, a derivative obtained by ester-bonding with itaconic acid or the like may be used.

As said nitrile group containing monomer, (meth)acrylonitrile etc. are mentioned, for example.

As said isocyanate group containing monomer, 2-isocyanatoethyl (meth)acrylate etc. are mentioned, for example.

Examples of the amide group-containing monomer include: (meth)acrylamides; N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide Amide, N,N-dipropyl(meth)acrylamide, N,N-diisopropyl(meth)acrylamide, N,N-di(n-butyl)(meth)acrylamide Amine, N,N-di(tert-butyl)(meth)acrylamide and other N,N-dialkyl(meth)acrylamide; N-ethyl(meth)acrylamide, N- N-alkyl(meth)acrylamides such as isopropyl(meth)acrylamide, N-butyl(meth)acrylamide, N-n-butyl(meth)acrylamide; N- N-vinylcarboxamides such as vinylacetamide; monomers with hydroxyl and amido groups, such as N-(2-hydroxyethyl)(meth)acrylamide, N-(2-hydroxypropyl base) (meth)acrylamide, N-(1-hydroxypropyl)(meth)acrylamide, N-(3-hydroxypropyl)(meth)acrylamide, N-(2-hydroxypropyl) N-hydroxyalkyl groups such as butyl)(meth)acrylamide, N-(3-hydroxybutyl)(meth)acrylamide, N-(4-hydroxybutyl)(meth)acrylamide, etc. (Meth)acrylamide; monomers with alkoxy and amide groups, such as N-methoxymethyl(meth)acrylamide, N-methoxyethyl(meth)acrylamide , N-butoxymethyl(meth)acrylamide and other N-alkoxyalkyl(meth)acrylamide; in addition, N,N-dimethylaminopropyl(meth)acrylamide Amines, N-(meth)acryloylmorpholine, etc.

In addition, the above-mentioned (meth)acrylamides include, for example, various N-alkoxyalkyl(meth)acrylamides, for example, N-methoxymethyl(meth)acrylamide, N-butoxymethyl(meth)acrylamide and the like.

Examples of the amino group-containing monomer include: Aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, tert-butylamine (meth)acrylate ethyl ethyl ester etc.

Examples of the alkoxyalkyl (meth)acrylate having an alkoxy group having 5 or less carbon atoms include: 2-methoxyethyl (meth)acrylate, 2-ethyl (meth)acrylate Oxyethyl ester, Methoxytriethylene glycol (meth)acrylate, 3-methoxypropyl (meth)acrylate, 3-ethoxypropyl (meth)acrylate, (meth)acrylic acid 4-methoxybutyl, 4-ethoxybutyl (meth)acrylate, etc.

As said sulfonic acid group containing monomer, vinylsulfonate sodium etc. are mentioned, for example.

The above-mentioned macromonomer system is a high-molecular-weight monomer obtained by polymerizing a plurality of the above-mentioned monomer components. In the case of using a macromonomer, structural units derived from monomer components constituting the macromonomer exist continuously to some extent in the base polymer. Therefore, by using a macromonomer, a high-order structure derived from a macromonomer can be introduced into the base polymer, and the properties required as an adhesive (adhesive force or cohesive force, step followability, etc.) can be easily adjusted . The weight average molecular weight of the macromonomer is preferably 3,000-35,000, more preferably 4,000-30,000, more preferably 5,000-25,000, and even more preferably 6,000-20,000.

Examples of the polyfunctional monomer having two or more polymerizable functional groups include: hexanediol di(meth)acrylate, butanediol di(meth)acrylate, (poly)ethylene glycol Alcohol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate , dipentaerythritol hexa(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, allyl (meth)acrylate, (meth) Vinyl acrylate, divinylbenzene, polyester acrylate, urethane acrylate, etc. A polyfunctional monomer can be used individually or in combination of 2 or more types.

The content of the polyfunctional monomer in the methacrylic copolymer of the present invention is not particularly limited, but is preferably 0.5% by mass or less (for example, 0 to 0.5% by mass) relative to 100% by mass of all structural units, and more preferably Preferably, it is 0-0.35 mass %, More preferably, it is 0-0.2 mass %. If the content of the above polyfunctional monomer is 0.5% by mass or less, the adhesive layer has moderate cohesive force, and the adhesive force or step absorbability is likely to be improved, which is preferable. Furthermore, when a crosslinking agent is used, the polyfunctional monomer may not be used, and the content of the polyfunctional monomer when not using a crosslinking agent is preferably 0.001 to 0.5% by mass, more preferably 0.001 to 0.35% by mass. % by mass, and more preferably 0.002 to 0.2% by mass.

The total content of the above-mentioned copolymerizable monomers in the above-mentioned methacrylic copolymer is not particularly limited, but is preferably 30.0% by mass or less, more preferably 15.0% by mass or less, based on 100% by mass of all structural units.

The above-mentioned methacrylic copolymer can be obtained by mixing the above-mentioned methacrylate compound having a hydrocarbon group having 6 or more carbon atoms, the (meth)acrylate compound containing a crosslinkable functional group, and a copolymerizable monomer, or by Polymerization obtained by known or customary polymerization methods. As the above-mentioned polymerization method, for example, a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, a polymerization method by irradiating active energy rays (active energy ray polymerization method) and the like may, for example, be mentioned. Among them, in view of the transparency, water resistance, and cost of the adhesive layer, the solution polymerization method and the active energy ray polymerization method are preferable, and the active energy ray polymerization method is more preferable.

The active energy rays irradiated during the above-mentioned active energy ray polymerization (photopolymerization) include, for example, ionizing radiation such as α-rays, β-rays, γ-rays, neutron rays, and electron beams, or ultraviolet rays. ultraviolet light. In addition, the irradiation energy, irradiation time, and irradiation method of active energy rays are not particularly limited, as long as the photopolymerization initiator can be activated to cause a reaction of the monomer components.

Various common solvents can also be used at the time of polymerization of the said methacryl-type copolymer. As such solvents, for example, esters (ethyl acetate, n-butyl acetate, etc.), aromatic hydrocarbons (toluene, benzene, etc.), aliphatic hydrocarbons (n-hexane, n-heptane, etc.), fatty acids, etc. Cyclic hydrocarbons (cyclohexane, methylcyclohexane, etc.), ketones (methyl ethyl ketone, methyl isobutyl ketone, etc.) and other organic solvents. A solvent can be used individually or in combination of 2 or more types.

Moreover, when superposing|polymerizing the said methacrylic-type copolymer, depending on the kind of polymerization reaction, a polymerization initiator, such as a thermal polymerization initiator or a photopolymerization initiator (photoinitiator), can be used. A polymerization initiator can be used individually or in combination of 2 or more types.

The above-mentioned photopolymerization initiator is not particularly limited, and examples thereof include: benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-keto alcohol-based photopolymerization initiators, aromatic Sulfonyl chloride-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzoyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, Ketone-based photopolymerization initiators, 9-oxothiol-based photopolymerization initiators, etc. A photopolymerization initiator can be used individually or in combination of 2 or more types.

Examples of the benzoin ether-based photopolymerization initiator include: benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2- Diphenylethane-1-one, anisole methyl ether, etc. Examples of the acetophenone-based photopolymerization initiator include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclo Hexyl phenyl ketone, 4-phenoxydichloroacetophenone, 4-(tert-butyl)dichloroacetophenone and the like. Examples of the α-ketol-based photopolymerization initiator include 2-methyl-2-hydroxypropiophenone, 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropane- 1-keto etc. As said aromatic sulfonyl chloride type photopolymerization initiator, 2-naphthalenesulfonyl chloride etc. are mentioned, for example. As said photoactive oxime type photoinitiator, 1-phenyl-1, 1-propanedione-2-(O-ethoxycarbonyl)-oxime etc. are mentioned, for example. As said benzoin type photoinitiator, a benzoin etc. are mentioned, for example. As said benzoyl photopolymerization initiator, benzoyl etc. are mentioned, for example. Examples of the benzophenone-based photopolymerization initiator include: benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyethylene Benzophenone, α-hydroxycyclohexyl phenyl ketone, etc. As said ketal type photoinitiator, a benzoyl dimethyl ketal etc. are mentioned, for example. Examples of the above-mentioned 9-oxothiophene-based photopolymerization initiator include: 9-oxothiophene, 2-chloro-9-oxothiophene, 2-methyl-9-oxothiophene, 2,4- Dimethyl-9-oxosulfur, isopropyl-9-oxosulfur, 2,4-diisopropyl-9-oxosulfur, dodecyl-9-oxosulfur, etc.

The amount of the photopolymerization initiator used is not particularly limited, for example, it is preferably 0.001-10.0 parts by mass, more preferably 0.01-5.0 parts by mass with respect to 100 parts by mass of all the structural units of the above-mentioned methacrylic copolymer .

In addition, as the thermal polymerization initiator, for example, an azo-based polymerization initiator, a peroxide-based polymerization initiator (for example, dibenzoyl peroxide, tertiary butyl peroxymaleic acid, etc.) esters, etc.), redox system polymerization initiators, etc. Among them, the azo-based polymerization initiator disclosed in Japanese Patent Application Laid-Open No. 2002-69411 is preferable. Examples of the azo-based polymerization initiators include: 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis-2-methylbutyronitrile (AMBN), 2, Dimethyl 2'-azobis(2-methylpropionate), 4,4'-azobis-4-cyanovaleric acid, etc.

The usage-amount of the said thermal-polymerization initiator is preferably 0.05-0.5 mass parts with respect to 100 mass parts of all structural units of the said methacrylic-type copolymer, for example, in the case of the said azo-type polymerization initiator. parts, more preferably 0.1 to 0.3 parts by mass.

The weight average molecular weight (Mw) of the copolymer forming the adhesive layer of the present invention is preferably from 100,000 to 5,000,000, more preferably from 2,000,000 to 4,000,000, and still more preferably from 300,000 to 3,000,000. A composition having a weight-average molecular weight of 100,000 or more is preferable in terms of improving adhesive force and retention characteristics, and improving foaming and peeling resistance. A composition having a weight-average molecular weight of 5,000,000 or less is preferable in that it is easy to increase adhesive force and improve foaming and peeling resistance.

The weight average molecular weight (Mw) of the said copolymer can be calculated|required by polystyrene conversion by the GPC method (Gel Permeation Chromatography, gel permeation chromatography). For example, it can be measured using a high-speed GPC device (product name "HPLC-8120GPC", manufactured by Tosoh Corporation) under the following conditions. ・Column: TSKgel SuperHZM-H/HZ4000/HZ3000/HZ2000 ・Solvent: Tetrahydrofuran ・Flow rate: 0.6 ml/min

The glass transition temperature (Tg) of the above copolymer is preferably -70 to 100°C, more preferably -65 to 50°C, still more preferably -60 to 10°C. When the glass transition temperature of the said methacryl-type copolymer is -70 degreeC or more, cohesive force will improve and foaming peeling resistance will improve easily, and it is preferable. Also, if the above-mentioned glass transition temperature is 100° C. or lower, the adhesive composition has moderate flexibility, and it is easy to obtain good adhesive force or good step absorption, and it is easy to obtain excellent adhesion reliability, so it is preferable.

The glass transition temperature (Tg) of the above copolymer is the glass transition temperature (theoretical value) represented by the following FOX formula. In the following formula, Tg represents the glass transition temperature (unit: K) of the above-mentioned copolymer, Tgi monomer _i represents the glass transition temperature (unit: K) when forming a homopolymer, W _i represents the monomer i in the monomer The mass fraction in the total amount of ingredients (i=1, 2,・・・・n). 1/Tg＝W ₁ /Tg ₁ ＋W ₂ /Tg ₂ ＋・・・＋W _n /Tg _n

As the Tg of the homopolymer of the monomers constituting the above-mentioned copolymer, the following values can be adopted. ・Lauryl methacrylate -65℃ ・2-Ethylhexyl methacrylate -10℃ ・Lauryl Acrylate 0℃ ・2-Ethylhexyl Acrylate -70℃ ・Isodecyl Methacrylate -41℃ ・2-Hydroxyethyl methacrylate 55℃ ・Methyl methacrylate 105℃ ・Cyclohexyl methacrylate 66℃ ・Isomethacrylate ・Dicyclopentyl methacrylate                                                                               ・Methacrylic acid 228℃ ・N-Vinylpyrrolidone 86℃ ・2-Phenoxyethyl methacrylate 5℃ ・Benzyl methacrylate 54℃ ・2-(2-Methoxyethoxy)ethyl methacrylate -3℃

In addition, as the Tg of the homopolymer of the monomer not described above, the value described in "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc, 1989) can be used. Furthermore, as Tg of the homopolymer of the monomer which is not described in the said document, the value obtained by the said measurement method (the peak top temperature of tan δ based on the viscoelasticity test) can be used.

In the polymerization of the above-mentioned methacrylic acid-based copolymer, a chain transfer agent may be used in order to adjust the molecular weight. Examples of the chain transfer agent include: 2-mercaptoethanol, α-thioglycerol, 2,3-dimercapto-1-propanol, octylmercaptan, tertiary nonylmercaptan, dodecyl Mercaptan (lauryl mercaptan), tertiary-dodecyl mercaptan, glycidyl mercaptan, thioglycolic acid, methyl thioglycolate, ethyl thioglycolate, propyl thioglycolate , butyl thioglycolate, tertiary butyl thioglycolate, 2-ethylhexyl thioglycolate, octyl thioglycolate, isooctyl thioglycolate, decyl thioglycolate, sulfur Lauryl glycolate, thioglycolic acid ester of ethylene glycol, thioglycolic acid ester of neopentyl glycol, thioglycolic acid ester of pentaerythritol, α-methylstyrene dimer, etc. Among these, α-thioglycerol and methyl thioglycolate are preferred, and α-thioglycerol is particularly preferred from the viewpoint of suppressing whitening of the adhesive sheet due to humidification. A chain transfer agent can be used individually or in combination of 2 or more types.

The content of the chain transfer agent is preferably from 0.1 to 20 parts by mass, more preferably from 0.2 to 15 parts by mass, and still more preferably from 0.3 to 10 parts by mass relative to 100 parts by mass of all structural units of the above-mentioned methacrylic acid-based copolymer. . By making content (amount of use) of a chain transfer agent into the said range, the methacryl-type copolymer which controlled the weight average molecular weight to 1000-30000 can be obtained easily.

The adhesive composition of the present invention preferably contains a crosslinking agent. When a crosslinking agent is included in the adhesive composition, the base polymer is crosslinked to increase the gel fraction, and it is easy to improve the resistance to foaming and peeling. Examples of the crosslinking agent include isocyanate crosslinking agents, epoxy crosslinking agents, melamine crosslinking agents, peroxide crosslinking agents, other urea crosslinking agents, and metal alkoxides. Crosslinking agent, metal chelate crosslinking agent, metal salt crosslinking agent, carbodiimide crosslinking agent, oxazoline crosslinking agent, aziridine crosslinking agent, amine crosslinking agent Joint agent, etc. Among them, in terms of improving foaming and peeling resistance, an isocyanate-based crosslinking agent and an epoxy-based crosslinking agent are preferred, and an isocyanate-based crosslinking agent is more preferred. A crosslinking agent can be used individually or in combination of 2 or more types.

Examples of the isocyanate-based crosslinking agent (polyfunctional isocyanate compound) include 1,2-ethylidene diisocyanate, 1,4-butylene diisocyanate, 1,6-hexamethylene diisocyanate, etc. Lower aliphatic polyisocyanates; cyclopentyl diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate, hydrogenated toluene diisocyanate, hydrogenated xylene diisocyanate and other alicyclic polyisocyanates; 2,4-toluene Aromatic polyisocyanates such as diisocyanate, 2,6-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, etc. In addition, examples of the above-mentioned isocyanate-based crosslinking agent include trimethylolpropane/toluene diisocyanate adduct (trade name "Coronate L", manufactured by Nippon Polyurethane Industries Co., Ltd.), trimethylolpropane / Hexamethylene diisocyanate adduct (trade name "Coronate HL", manufactured by Nippon Polyurethane Industry Co., Ltd.), trimethylolpropane/xylylene diisocyanate adduct (trade name "Takenate D-110N ", manufactured by Mitsui Chemicals Co., Ltd.) and other commercially available products.

Examples of the epoxy-based crosslinking agent (polyfunctional epoxy compound) include: N,N,N',N'-tetraglycidyl m-xylylenediamine, diglycidylaniline, 1,3 -Bis(N,N-diglycidylaminomethyl)cyclohexane, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol Diglycidyl ether, Polyethylene glycol diglycidyl ether, Polypropylene glycol diglycidyl ether, Sorbitol polyglycidyl ether, Glycerin polyglycidyl ether, Pentaerythritol polyglycidyl ether, Polyglycerol polyglycidyl ether, Sorbitan Polyglycidyl ether, trimethylolpropane polyglycidyl ether, diglycidyl adipate, diglycidyl phthalate, tris(2-hydroxyethyl)isocyanurate triglycidyl, m-phenyl Diphenol diglycidyl ether, bisphenol S diglycidyl ether, and other epoxy-based resins having two or more epoxy groups in the molecule, etc. Moreover, as said epoxy type crosslinking agent, a commercial item, such as a brand name "Tetrad C" (made by Mitsubishi Gas Chemical Co., Ltd.), can also be mentioned, for example.

As content of the crosslinking agent in the said adhesive composition, it is preferable that it is 0.001-10 mass parts with respect to 100 mass parts of said methacryl-type copolymers, and it is more preferable that it is 0.01-5 mass parts, for example. If the content of the crosslinking agent is 0.001 parts by mass or more, the foaming and peeling resistance is likely to be improved, which is preferable. On the other hand, when the content of the crosslinking agent is 10 parts by mass or less, the adhesive layer has moderate flexibility and the adhesive force is likely to increase, which is preferable.

From the perspective of further lowering the dielectric constant and lowering the dielectric loss in the high-frequency band, the adhesive composition of the present invention may contain inorganic fine particles, organic fine particles, and polymers other than the basic polymer in addition to the above-mentioned base polymer. material. These can be used individually or in combination of 2 or more types. The above-mentioned inorganic fine particles and organic fine particles are preferably those exhibiting insulating properties (insulating fillers) from the viewpoint of low dielectric constant and low dielectric loss in high frequency bands.

(inorganic microparticles) Examples of inorganic fine particles that can be formulated in the adhesive composition of the present invention include: metal oxides such as silicon dioxide, aluminum oxide, zirconium oxide, and titanium oxide; metal salts such as aluminum borate and aluminum hydroxide; mica, etc. Minerals, hollow nano-silicon dioxide and other inorganic particles with a hollow structure, etc. These can be used individually or in combination of 2 or more types.

From the viewpoint of dispersibility in the base polymer, the above-mentioned inorganic fine particles may be surface-treated. As the surface treatment agent, known or commonly used ones can be used without limitation, for example, silane coupling agents, titanium coupling agents, organic acids, polyhydric alcohols, polysiloxane, etc., preferably silane coupling agents. Examples of silane coupling agents include: vinyltrimethoxysilane, vinyltriethoxysilane, dimethylvinylmethoxysilane, dimethylvinylethoxysilane, methylvinyldimethylsilane Oxysilane, Methylvinyldiethoxysilane, Vinyltris(2-Methoxy)silane, Vinyltriacetyloxysilane, 2-Methacryloxyethyltriethoxysilane , 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, Triethoxyphenylsilane, trimethoxyphenylsilane, dimethoxydiphenylsilane, methyldiethoxyphenylsilane, dimethoxymethylphenylsilane, etc.

From the viewpoint of low dielectric constant, low dielectric loss, and transparency of the adhesive composition at high frequencies, the particle size (D50) of the above-mentioned inorganic fine particles is preferably 1-100 nm, more preferably 5-80 nm. nm, and more preferably 10 to 50 nm. The above-mentioned central particle diameter means the particle diameter (median diameter) at 50% of the cumulative value in the particle size distribution measured by laser diffraction and scattering method.

When the adhesive composition of the present invention contains inorganic microparticles, from the viewpoints of low dielectric constant, low dielectric loss, and transparency of the adhesive composition at high frequencies, compared to the above-mentioned methacrylic copolymer 100 parts by weight, the content is preferably 0.01 to 30 parts by mass, more preferably 0.05 to 25 parts by mass, further preferably 0.10 to 20 parts by mass, even more preferably 0.15 to 10 parts by mass, especially preferably 0.2 to 10 parts by mass 5 parts by mass.

(organic microparticles) As the organic microparticles that can be formulated in the adhesive composition of the present invention, for example, styrene-based resins, acrylic resins, polysiloxane-based resins, acrylic-styrene-based resins, vinyl chloride-based resins, di Polymerization of vinyl chloride resin, amide resin, urethane resin, phenol resin, styrene-conjugated diene resin, acrylic acid-conjugated diene resin, olefin resin, fluorine resin, etc. objects, or microparticles of cross-linked polymers, and microparticles of polymer-polymer cross-linked bodies in a hollow structure. These can be used individually or in combination of 2 or more types.

From the viewpoint of low dielectric constant, low dielectric loss, and transparency of the adhesive composition at high frequencies, the particle size (D50) of the above-mentioned organic microparticles is preferably 1-100 nm, more preferably 5-80 nm. nm, and more preferably 10 to 50 nm. The above-mentioned central particle diameter means the particle diameter (median diameter) at 50% of the cumulative value in the particle size distribution measured by laser diffraction and scattering method.

When the adhesive composition of the present invention contains organic microparticles, from the viewpoints of low dielectric constant, low dielectric loss, and transparency of the adhesive composition at high frequencies, compared to the above-mentioned methacrylic copolymer 100 parts by mass, the content is usually 0.01 to 30 parts by mass, preferably 0.05 to 25 parts by mass, more preferably 0.1 to 20 parts by mass, further preferably 0.15 to 10 parts by mass, especially preferably 0.2 to 5 parts by mass share.

(polymer material) As the polymer material that can be formulated in the adhesive composition of the present invention, it is preferable to have a low dielectric constant and dielectric loss, and have compatibility with the base polymer, for example: fluororesin, fluororubber , (meth)acrylates containing fluorine functional groups, polyethylene, polypropylene, polystyrene, polycarbonate, norbornene-based resins or addition-copolymerized resins with olefins, polyphenylene ether, bis-butadiene Ethylene imide-trimethoprene resin, polyether imide, polyimide, polyether ether ketone (PEEK), liquid crystal polymer, rubber elastomer, hydrogenated polyolefin resin, terpene, isoprene, Terpene phenol resins, aromatic modified terpene resins and their hydrogenated resins, etc. These can be used individually or in combination of 2 or more types.

When the adhesive composition of the present invention contains a polymer material, its content is not particularly limited. Considering the low dielectric constant, low dielectric loss, and transparency of the adhesive composition at high frequency bands, It is 0.01-50 mass parts normally with respect to 100 mass parts of said methacryl-type copolymers, Preferably it is 0.05-40 mass parts, More preferably, it is 0.1-30 mass parts.

(Rust inhibitor) The adhesive composition of the present invention may further contain a rust inhibitor. When an antirust agent is included in the adhesive composition, it is preferable in terms of obtaining an excellent anticorrosion effect on antenna elements and metal wiring.

Rust inhibitors are compounds that prevent rust or corrosion of metals. As a rust preventive agent, an amine compound, a benzotriazole compound, nitrite etc. are mentioned, for example. In addition, ammonium benzoate, ammonium phthalate, ammonium stearate, ammonium palmitate, ammonium oleate, ammonium carbonate, dicyclohexylamine benzoate, urea, hexamethylene tetra Amine (Urotropine), thiourea, phenyl carbamate, cyclohexyl ammonium N-cyclohexyl carbamate (CHC), etc. The rust inhibitors can be used alone or in combination of two or more.

As the above-mentioned amine compound, for example, hydroxyl-containing amine compounds such as 2-amino-2-methyl-1-propanol, monoethanolamine, monoisopropanolamine, diethylethanolamine, ammonia or ammonia water; Cyclic amines such as morphine; Cyclic alkylamine compounds such as cyclohexylamine; Linear alkylamines such as 3-methoxypropylamine, etc. Moreover, as nitrites, dicyclohexylammonium nitrite (DICHAN), diisopropylammonium nitrite (DIPAN), sodium nitrite, potassium nitrite, calcium nitrite etc. are mentioned, for example.

It is preferable to contain 0.02-15 mass parts with respect to 100 mass parts of said methacryl-type copolymers about content of the said rust preventive agent. If the said content is 0.02 mass part or more, since favorable anticorrosion performance is easy to be acquired, it is preferable. On the other hand, when the said content is 15 parts by mass or less, it is easy to ensure transparency, and it is easy to ensure adhesive reliability, such as foaming-resistant peeling property, and it is preferable.

Among them, the above-mentioned antirust agent is preferably Benzotriazole compounds.

(其中，上述式(1)中，R ¹以及R ²相同或不同，R ¹為苯環上之取代基，表示碳數1～6之烷基、碳數1～6之烷氧基、碳數6～14之芳基、胺基、單或二C _1-10烷基胺基、胺基-C _1-6烷基、單或二C _1-10烷基胺基-C _1-6烷基、巰基、碳數1～6之烷氧基羰基、或碳數1～6之烷氧基等取代基，n為0～4之整數，於n為2以上之情形時，n個R ¹可相同亦可不同，R ²表示氫原子、碳數1～12之烷基、碳數1～12之烷氧基、碳數6～14之芳基、胺基、單或二C _1-10烷基胺基、胺基-C _1-6烷基、單或二C _1-10烷基胺基-C _1-6烷基、巰基、碳數1～12之烷氧基羰基、或碳數1～12之烷氧基等取代基) The above-mentioned benzotriazole-based compound is not particularly limited as long as it is a compound having a benzotriazole skeleton. From the viewpoint of obtaining a more excellent anti-corrosion effect, one having the following formula (1) is preferred. representation structure. [chemical 1]

(wherein, in the above formula (1), R ¹ and R ² are the same or different, and R ¹ is a substituent on the benzene ring, representing an alkyl group with 1 to 6 carbons, an alkoxy group with 1 to 6 carbons, a carbon Aryl, amino, mono or _di C _{1-10 alkyl amino, amino-C 1-6} alkyl, mono or di C _1-10 alkyl amino-C _1-6 alkane with the number 6-14 Substituents such as radical, mercapto, alkoxycarbonyl with 1 to 6 carbons, or alkoxy with 1 to 6 carbons, n is an integer of 0 to 4, when n is 2 or more, n ^R1 Can be the same or different, ^R2 represents a hydrogen atom, an alkyl group with 1 to 12 carbons, an alkoxy group with 1 to 12 carbons, an aryl group with 6 to 14 carbons, an amino group, a single or two C _1-10 Alkylamino, amino-C _1-6 alkyl, mono- or di-C _1-10 alkylamino-C _1-6 alkyl, mercapto, alkoxycarbonyl with 1 to 12 carbons, or carbon number 1 to 12 substituents such as alkoxy)

From the standpoint of obtaining a more excellent anti-corrosion effect, R ¹ is preferably an alkyl group having 1 to 3 carbon atoms, an alkoxycarbonyl group, or the like, more preferably a methyl group, or the like. Also, n is preferably 0 or 1. From the same point of view, R ² is preferably a hydrogen atom, mono- or di-C _1-10 alkylamino-C _1-6 alkyl, etc., more preferably a hydrogen atom, di-C _1-8 alkylamine Group C _1-4 alkyl and so on.

The content of the benzotriazole-based compound is preferably from 0.02 to 3 parts by mass, more preferably from 0.02 to 2.5 parts by mass, and still more preferably from 0.02 to 2 parts by mass, based on 100 parts by mass of the above-mentioned methacrylic acid-based copolymer. When the amount of the benzotriazole-based compound is within a certain range, adhesion reliability such as resistance to foaming and peeling can be reliably ensured, and an increase in the haze of the adhesive sheet can also be reliably prevented.

(silane coupling agent) The adhesive composition of the present invention may further contain a silane coupling agent. If a silane coupling agent is included in the adhesive composition, it is preferable in terms of easily obtaining excellent adhesion to glass (especially excellent adhesion reliability to glass under high temperature and high humidity).

Examples of the silane coupling agent include: γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N- Phenyl-aminopropyltrimethoxysilane, etc. Among them, γ-glycidoxypropyltrimethoxysilane is preferred. As said silane coupling agent, a commercial item, such as a brand name "KBM-403" (made by Shin-Etsu Chemical Co., Ltd.), can also be mentioned, for example. A silane coupling agent can be used individually or in combination of 2 or more types.

From the viewpoint of improving the bonding reliability to glass, the content of the silane coupling agent is preferably from 0.01 to 1 part by mass, more preferably from 0.03 to 0.5 parts by mass, based on 100 parts by mass of the above-mentioned methacrylic copolymer.

(other additives) In the adhesive composition of the present invention, antioxidants, crosslinking accelerators, crosslinking retarders, adhesion-imparting resins (rosin derivatives, polyterpene resins, oil soluble phenol, etc.), anti-aging agents, colorants (pigments or dyes, etc.), ultraviolet absorbers, chain transfer agents, plasticizers, softeners, surfactants, antistatic agents and other known additives. These can be used individually or in combination of 2 or more types.

When the adhesive composition of the present invention contains an adhesive imparting agent, its content is preferably at least 0.01 parts by mass based on 100 parts by mass of the above-mentioned methacrylic copolymer, more preferably It is 0.05 mass parts or more. Moreover, from the viewpoint of avoiding that the peeling strength becomes too high, it is preferably at most 50 parts by mass, more preferably at most 40 parts by mass.

[adhesive layer] The adhesive layer of the present invention is formed from the adhesive composition of the present invention, so it exhibits low dielectric constant and low dielectric loss under millimeter waves in the high frequency band (28-60 GHz). That is, the adhesive layer of the present invention can suppress the radiation loss of millimeter waves.

The adhesive layer of the present invention has a lower dielectric constant at 28 GHz, which is better in suppressing the radiation loss of millimeter waves. The dielectric constant of the adhesive layer of the present invention at a frequency of 28 GHz is preferably 2.00-5.00, more preferably 2.05-4.50, further preferably 2.10-4.00, further preferably 2.15-3.50, especially preferably 2.20- 3.40, the best is 2.20-3.30, 2.20-3.20, 2.20-3.10, 2.20-3.00 or 2.20-2.90.

The dielectric constant of the adhesive layer of the present invention at 28 GHz can be adjusted by adjusting the type of base polymer, monomer composition, type or content of additives, etc. constituting the adhesive composition used to form the adhesive layer .

The dielectric loss of the adhesive layer of the present invention is lower at 28 GHz, and it is better in suppressing the radiation loss of millimeter waves. The dielectric loss of the adhesive layer of the present invention at a frequency of 28 GHz is preferably less than 0.050, more preferably less than 0.045, further preferably less than 0.040, still more preferably less than 0.035, especially preferably less than 0.030, and most preferably less than 0.030. 0.025 or less or 0.020 or less. The lower limit is not particularly limited, but is preferably 0.0001 or more, and may be 0.0005 or more or 0.0010 or more.

The dielectric loss of the adhesive layer of the present invention at 28 GHz can be adjusted by adjusting the type of base polymer, the monomer composition, the type or content of additives, etc. constituting the adhesive composition used to form the adhesive layer .

The adhesive layer of the present invention has a lower dielectric constant at 60 GHz, which is better in suppressing the radiation loss of millimeter waves. The dielectric constant of the adhesive layer of the present invention at a frequency of 60 GHz is preferably 2.0 to 5.0, more preferably 2.1 to 4.5, further preferably 2.2 to 4.0, further preferably 2.2 to 3.5, especially preferably 2.2 to 3.4, the best is 2.2-3.3, 2.2-3.2, 2.2-3.1, 2.2-3.0 or 2.2-2.9.

The dielectric constant of the adhesive layer of the present invention at 60 GHz can be adjusted by adjusting the type of base polymer, monomer composition, type or content of additives, etc. constituting the adhesive composition used to form the adhesive layer .

In the adhesive layer of the present invention, the dielectric loss at 60 GHz is preferably controlled to be relatively low, and it is preferable in that the radiation loss of millimeter waves can be suppressed. The dielectric loss of the adhesive layer of the present invention at a frequency of 60 GHz is preferably less than 0.050, more preferably less than 0.045, further preferably less than 0.040, still more preferably less than 0.035, especially preferably less than 0.030, and most preferably less than 0.030. 0.025 or less or 0.020 or less. The lower limit of the dielectric loss at a frequency of 60 GHz is preferably not less than 0.0001, and may be not less than 0.0005 or not less than 0.0010.

The dielectric loss of the adhesive layer of the present invention at 60 GHz can be adjusted by adjusting the type of base polymer, the monomer composition, the type or content of additives, etc. constituting the adhesive composition used to form the adhesive layer .

The adhesive layer of the present invention is transparent or has transparency. Therefore, the visibility and appearance through the said adhesive composition are excellent. Thus, the pressure-sensitive adhesive layer of this invention can be used suitably for an optical use.

The haze of the adhesive layer of the present invention (based on JIS K7136) is not particularly limited, but is preferably 1.2% or less, more preferably 1.1% or less, further preferably 1.0% or less, still more preferably 0.9% or less, especially Preferably less than 0.8%. When the haze is, for example, 1.2% or less, excellent transparency or an excellent appearance can be easily obtained. For example, the above-mentioned haze can be set to a thickness of 25 μm of the adhesive layer, which is left to stand at a normal state (23°C, 50% R.H.) for at least 24 hours, and then attached to a glass slide (for example, the total light transmittance is 91.8%, haze 0.4%), and the obtained product was used as a sample, and measured using a haze meter (product name "HM-150", manufactured by Murakami Color Technology Laboratory Co., Ltd.).

The total light transmittance (according to JIS K7361-1) of the adhesive layer of the present invention in the visible light wavelength region is not particularly limited, but is preferably 85% or more, more preferably 88% or more, and still more preferably 89% or more, Furthermore, it is more preferably 90% or more, especially preferably 91% or more, most preferably 92% or more. When the total light transmittance is 85% or more, it is easy to obtain excellent transparency or excellent appearance. The above-mentioned total light transmittance can be set, for example, to a thickness of 25 μm of the adhesive layer, which is left to stand at a normal state (23°C, 50% R.H.) for at least 24 hours, and then peeled off when there is a spacer, and bonded On a slide glass (for example, total light transmittance 91.8%, haze 0.4%), set the resultant as a sample, and use a haze meter (product name "HM-150", manufactured by Murakami Color Technology Research Institute Co., Ltd. ) to measure.

The haze and total light transmittance of the adhesive layer of the present invention can be adjusted by adjusting the type of base polymer, monomer composition, type or content of additives, etc. constituting the adhesive composition used to form the adhesive layer. .

The gel fraction (ratio of insoluble components) of the adhesive layer of the present invention is preferably 30-95%, more preferably 35-90%, still more preferably 40-85%, still more preferably 45-80% , preferably 50-75%. If the gel fraction is more than 30%, the cohesive force of the above-mentioned adhesive layer is improved, and it is difficult to produce dents during operation. In addition, foaming or peeling at the interface with the adherend in a high-temperature environment is suppressed, and it is easy to It is preferred to obtain excellent resistance to foaming and peeling. If the gel fraction is 95% or less, moderate flexibility can be obtained, the adhesiveness and step followability can be further improved, and foreign matter is less likely to be absorbed, which is preferable.

The said gel fraction (ratio of a solvent-insoluble component) can be calculated as follows, for example.

About 0.1 g was taken from the adhesive layer, wrapped in a porous tetrafluoroethylene sheet with an average pore size of 0.2 μm (trade name "NTF1122", manufactured by Nitto Denko Co., Ltd.), and then tied tightly with a kite string to measure the time The mass of the mass is set as the mass before immersion (Z). The mass before dipping is the total mass of the adhesive layer, the tetrafluoroethylene sheet, and the kite string. In addition, the total mass of the tetrafluoroethylene sheet and the kite string was also measured in advance, and this mass was set as the packaging mass (Y). Next, put the adhesive layer wrapped with tetrafluoroethylene sheet and tied tightly with kite string (called "sample") into a 50 ml container filled with ethyl acetate or toluene, and let stand at 23°C for 7 days . Thereafter, the sample was taken out from the container (after treatment with ethyl acetate or toluene), transferred to an aluminum cup, dried in a drier at 130° C. for 2 hours to remove ethyl acetate or toluene, and then the mass was measured. Let this mass be the mass after immersion (X). And, the gel fraction was calculated according to the following formula. Gel fraction (%)={(X－Y)/(Z－Y)}×100

The gel fraction of the adhesive layer of the present invention can be controlled by, for example, monomer composition, weight average molecular weight, usage amount of crosslinking agent, type or usage amount of other additives, and the like.

The storage modulus of the adhesive layer of the present invention at 25°C is preferably at least 0.01 MPa, more preferably at least 0.02 MPa, still more preferably at least 0.03 MPa, still more preferably at least 0.04 MPa, especially preferably at least 0.05 MPa , preferably above 0.10 MPa. If the above-mentioned storage modulus is 0.01 MPa or more, dents are less likely to be generated during handling, and good bonding reliability can be easily obtained, which is preferable. In addition, from the viewpoint of step followability and foreign matter absorption, the storage modulus of the above-mentioned adhesive layer at 25° C. is preferably 5 MPa or less, more preferably 4.5 MPa or less, further preferably 4.0 MPa or less, and still more preferably 4.0 MPa or less. Preferably it is 3.5 MPa or less, more preferably 3.0 MPa or less, most preferably 2.5 MPa or less or 2.0 MPa or less. The storage modulus of the adhesive layer is measured when dynamic viscoelasticity is measured at a frequency of 1 Hz. The above storage modulus is the real part of the shear elastic modulus represented by a miscellaneous number, and the tensile elastic modulus can be converted by considering the Poisson's ratio of the sample.

The storage modulus of the adhesive layer of the present invention can be controlled by monomer composition, weight average molecular weight, usage amount (addition amount) of crosslinking agent, type or usage amount of other additives, and the like.

The 300% tensile residual stress of the adhesive layer of the present invention is not particularly limited, preferably 2-24 N/cm ² , more preferably 2.5-20 N/cm ² , and still more preferably 3-16 N/cm 2 ² . If the above-mentioned 300% tensile residual stress is 2 N/cm ² or more, it is easy to obtain good foaming and peeling resistance, and if it is 24 N/cm ² or less, it is easy to obtain good stress relaxation and good step Poor followability is better.

If the above-mentioned 300% tensile residual stress of the adhesive layer of the present invention is within the above-mentioned range, it is easy to obtain excellent stress relaxation, and it is easy to exert excellent step followability, for example, for larger steps (about 45 μm, For example, a height of 20-50 μm) can also be tracked well.

The above-mentioned 300% tensile residual stress is the following value (N/cm ² ), which is in an environment of 23°C and 50%RH, stretching the adhesive layer along the length direction to an elongation (strain) of 300%, and maintaining the For elongation, the tensile load applied to the adhesive layer after 300 seconds from the end of stretching was obtained, and the tensile load was divided by the initial cross-sectional area of the adhesive layer (the cross-sectional area before stretching). Furthermore, the initial elongation of the adhesive layer is 100%.

The 300% tensile residual stress of the adhesive layer of the present invention can be controlled by the monomer composition of the base polymer, the weight average molecular weight, the amount (addition amount) of the crosslinking agent, the type or amount of other additives, etc. .

The adhesive layer of the present invention can suppress the radiation loss of millimeter waves because the saturated moisture absorption rate is controlled to be low. The saturated moisture absorption rate of the adhesive layer of the present invention at 25°C and 90% R.H. is preferably 2.8% or less, more preferably 2.7% or less, further preferably 2.6% or less, and even more preferably 2.5% or less, especially The best is less than 2.4%, the best is less than 2.3%, less than 2.2%, less than 2.1%, less than 2.0%, less than 1.9%, less than 1.8%, less than 1.7%, less than 1.6%, less than 1.5%, less than 1.4%, less than 1.3 % or less, 1.2% or less, 1.1% or less, 1.0% or less, 0.9% or less, 0.8% or less, 0.7% or less, or 0.6% or less. If the saturated moisture absorption rate at 25°C and 90% R.H. is low, the radiation loss of millimeter waves near room temperature can be suppressed. The lower limit of the saturated moisture absorption rate is not particularly limited, for example, it may be 0.3% or more, 0.4% or 0.5% or more.

The saturated moisture absorption rate of the adhesive layer of the present invention at 65°C and 90% R.H. is preferably 2.8% or less, more preferably 2.6% or less, further preferably 2.4% or less, and even more preferably 2.3% or less, especially The best is less than 2.2%, the best is less than 2.1%, less than 2.0%, less than 1.9%, less than 1.8%, less than 1.7%, less than 1.6%, less than 1.5%, less than 1.4%, less than 1.3%, less than 1.2%, and less than 1.1 % or less, 1.0% or less, 0.9% or less, 0.8% or less, or 0.7% or less. The lower limit of the saturated moisture absorption rate is not particularly limited, for example, it may be 0.4% or more, or 0.5% or more, or 0.6% or more. If the saturated moisture absorption rate at 65°C and 90% R.H. is low, it can also suppress the radiation loss of millimeter waves when placed in a high temperature environment.

The saturated moisture absorption rate of the adhesive layer of the present invention at 85°C and 85% R.H. is preferably 5.0% or less, more preferably 4.0% or less, further preferably 3.5% or less, and even more preferably 3.0% or less, especially Preferably it is 2.8% or less, most preferably 2.6% or less, 2.4% or less, 2.2% or less, 2.0% or less, 1.8% or less, 1.6% or less, 1.4% or less, 1.2% or less, 1.0% or less, or 0.8% or less. The lower limit of the saturated moisture absorption rate is not particularly limited, for example, it may be 0.4% or more, or 0.5% or more, or 0.6% or more. If the saturated moisture absorption rate at 85°C and 85% R.H. is low, the radiation loss of millimeter waves can also be suppressed when placed in a high temperature environment.

The above-mentioned saturated moisture absorption rate under various temperature and humidity environments can be obtained, for example, from the weight of the sample in a dry state (w1) and the point at which the weight change stops when the sample is placed in an atmosphere of 65°C and 90% R.H. (the moisture absorption rate The weight (w2) at the time of saturation) can be obtained by the following formula. It can also be obtained under the conditions of 25°C, 90%R.H. and 85°C, 85%R.H. Furthermore, the values of w1 and w2 are those measured under the same temperature and humidity. Saturation moisture absorption rate (%)={(w2－w1)/w1}×100

The adhesive layer of the present invention can suppress the radiation loss of millimeter waves because the variation of dielectric loss caused by moisture absorption is controlled to be low. The change in the dielectric loss of the adhesive layer of the present invention at a frequency of 28 GHz due to moisture absorption is preferably 0.006 or less, more preferably 0.005 or less, and still more preferably 0.004 or less. The lower limit of the saturated moisture absorption rate is not particularly limited, and may be, for example, not less than 0.0001, or not less than 0.0002, or not less than 0.0003.

The change in the dielectric loss of the adhesive layer of the present invention at a frequency of 60 GHz due to moisture absorption is preferably 0.003 or less, more preferably 0.002 or less, and still more preferably 0.001 or less. The lower limit of the saturated moisture absorption rate is not particularly limited. For example, it may be at least 0.0001, or at least 0.0002, at least 0.0003, at least 0.0004, at least 0.0005, at least 0.0006, at least 0.0007, at least 0.0008, or at least 0.0009.

The variation of dielectric loss at the above frequency of 28 GHz and 60 GHz can be kept at 65°C, 90%RH for more than 5 days, and then restored to 23±1°C, 52%±1%RH (Elapsed time = 0 minutes), after 4 minutes to 180 minutes, measure the dielectric loss at each frequency every 10 minutes, from the maximum value (D _fmax ) and minimum value (D _fmin ), by Calculated by the following formula. Variation of dielectric loss = D _fmax - D _fmin

The adhesive layer of the present invention can suppress the radiation loss of millimeter waves because the water vapor permeability is controlled to be low. The water vapor permeability of the adhesive layer of the present invention at 40°C and 92%RH is preferably 430 g/m ² /day or less, more preferably 300 g/m ² /day or less, and even more preferably 250 g/m 2 /day m ² /day or less, more preferably 200 g/m ² /day or less, especially 150 g/m ² /day or less, most preferably 100 g/m ² /day or less, 50 g/m ² /day below or below 30 g/m ² /day. If the water vapor permeability at 40°C and 92%RH is low, the water resistance of the adhesive layer will be improved, and the radiation loss of millimeter waves in the adhesive layer can be suppressed. The lower limit of the water vapor permeability is not particularly limited, for example, it may be 10 g/m ² /day or more, 20 g/m ² /day or 25 g/m ² /day or more.

The above water vapor transmission rate (Water Vapor Transmission Rate; WVTR) is based on the value measured by the cup method. It can be obtained by measuring the weight (w1) of the dry state of calcium chloride isolated from the outside by the adhesive layer, and placing the sample in an atmosphere of 40°C and 92%RH for a predetermined time. The weight (w2) when the moisture absorption rate is saturated, and the weight change is converted into unit time (1 day) and unit area (1 m ² ).

The dielectric constant or dielectric loss of the adhesive layer of the present invention at 28 GHz or 60 GHz, the saturated moisture absorption rate, the change in dielectric loss caused by moisture absorption, and the water vapor permeability can be adjusted by adjusting the monomer composition , the type or content of additives, etc.

The thickness of the adhesive layer of the present invention is not particularly limited, but is preferably 10-500 μm, more preferably 11-400 μm, further preferably 12-350 μm, and even more preferably 12-300 μm. When the thickness is equal to or greater than a certain level, step followability or adhesion reliability tends to improve. Moreover, if the thickness is not more than a certain value, foreign substances are not easily absorbed during handling, and the manufacturability tends to be excellent.

The method for producing the above-mentioned adhesive layer is not particularly limited, and for example, a method of applying (coating) the above-mentioned adhesive composition on a substrate or a release liner, drying, curing, and Or dry and harden. Curing can be performed by irradiating active energy rays, heating and drying, or the like.

In addition, a well-known coating method can also be used for coating (coating) of the said adhesive composition. For example, a gravure roll coater, reverse roll coater, touch roll coater, dip roll coater, rod coater, knife coater, spray coater, etc. Corner wheel coater, direct coater and other coating machines.

[adhesive sheet] The adhesive sheet of the present invention is not particularly limited in other respects as long as it has the adhesive layer of the present invention.

The adhesive sheet of the present invention may be a double-sided adhesive sheet with both sides being the surface of the adhesive layer, or a single-sided adhesive sheet with only one side being the surface of the adhesive layer. Among these, a double-sided adhesive sheet is preferable from the viewpoint of bonding two members together. In addition, in this specification, when referring to an "adhesive sheet", what is made into a belt shape is also included in an "adhesive tape". Also, in this specification, the surface of the adhesive layer may be referred to as an "adhesive surface".

The adhesive sheet of the present invention may be provided with a spacer (release liner) on the adhesive surface before use.

The adhesive sheet of the present invention may be a so-called "substrate-less type" adhesive sheet (hereinafter, sometimes referred to as "substrate-less adhesive sheet") that does not have a substrate (substrate layer), or may have Adhesive sheet of substrate type (hereinafter, sometimes referred to as "adhesive sheet with substrate"). Examples of the base-less adhesive sheet include, for example, a double-sided adhesive sheet including only the above-mentioned adhesive layer, or a double-sided adhesive sheet including the above-mentioned adhesive layer and an adhesive layer other than the above-mentioned adhesive layer (sometimes referred to as "" Other adhesive layers") double-sided adhesive sheets, etc. On the other hand, as an adhesive sheet with a base material, the adhesive sheet etc. which have the said adhesive agent layer on the at least one side of a base material are mentioned. Among them, a substrate-less adhesive sheet (substrate-free double-sided adhesive sheet) is preferred, and a substrate-less double-sided adhesive sheet comprising only the above-mentioned adhesive layer is more preferred. Moreover, it is also preferable that it is an adhesive sheet which has the said adhesive agent layer on both surfaces of a base material (double-sided adhesive sheet with base material). The adhesive layers on both sides of the above-mentioned double-sided adhesive sheet with substrate may be the adhesive layer of the present invention, or one side may be the adhesive layer of the present invention and the other side may be another adhesive layer. In addition, the above-mentioned "substrate (substrate layer)" does not include a spacer that is peeled off when the adhesive sheet is used (attached).

In order to avoid the radiation loss of millimeter waves caused by the substrate, the adhesive sheet of the present invention is preferably an adhesive sheet without a substrate. Wherein, when the base material includes a material with low dielectric constant and low dielectric loss, it can also be an adhesive sheet with the base material. Ideally, the base material can be used regardless of the polarization state of the millimeter wave, so it is preferably non-stretching, and especially isotropic.

The adhesive sheet of the present invention has no special 180° peel adhesion to the glass plate at a tensile speed of 300 mm/min (especially the 180° peel adhesion of the adhesive surface provided by the adhesive layer of the present invention to the glass plate) Restricted, if the adhesive force is high, it is preferably 3 N/20 mm or more, more preferably 3.5 N/20 mm or more, and more preferably 4 N/20 from the aspect of obtaining sufficient adhesion to the antenna element. mm or more, more preferably 5 N/20 mm or more, particularly preferably 6 N/20 mm or more, most preferably 7 N/20 mm or more, 8 N/20 mm or more, 9 N/20 mm or more or 10 N/20 mm or more More than 20mm. When the above-mentioned peeling adhesive strength is at least a certain value, the adhesiveness to glass and the suppression of swelling in the step difference are more excellent. Furthermore, the adhesive sheet of the present invention has no particular limitation on the upper limit of the 180° peel adhesive force at a tensile speed of 300 mm/min for the glass plate, for example, it is preferably below 30 N/20 mm, more preferably 25 N/20 mm or less, more preferably 22 N/20 mm or less, more preferably 20 N/20 mm, especially 19 N/20 mm or less, most preferably 18 N/20 mm or less, 17 N/20 mm or less, 16 N/20 mm or less, 15 N/20 mm or less, 14 N/20 mm or less, 13 N/20 mm or less, 12 N/20 mm or less, or 11 N/20 mm or less. The 180° peel adhesion force for the glass plate at a tensile speed of 300 mm/min is obtained by the following method for measuring the 180° peel adhesion force.

As said glass plate, a brand name "soda-lime glass (SODA-LIME GLASS)♯0050" (made by Songnang Glass Industry Co., Ltd.) can be mentioned, for example. Moreover, non-alkali glass, chemically strengthened glass, etc. are also mentioned.

The 180° peel adhesion force at a tensile speed of 300 mm/min for a glass plate was obtained by the following measurement method. Attach the adhesive surface of the adhesive sheet to the adherend, and perform crimping under the conditions of 2 kg roller, one reciprocation, and aging for 30 minutes in an atmosphere of 23°C and 50% R.H. According to JIS Z0237, Under the atmosphere of 23°C and 50% R.H., under the conditions of tensile speed 300 mm/min and peeling angle 180°, the adhesive sheet was peeled off from the adherend, and the 180° peeling adhesion force was measured (N/20 mm) .

The 180° peel adhesion of the adhesive sheet of the present invention can be determined by the monomer composition of the base polymer (acrylic polymer), the weight average molecular weight, the amount of crosslinking agent used (addition amount), the type or use of other additives amount etc. to control.

The thickness (total thickness) of the adhesive sheet of the present invention is not particularly limited, but is preferably 10-500 μm, more preferably 11-400 μm, further preferably 12-350 μm, and still more preferably 12-300 μm . If the thickness is equal to or greater than a certain level, peeling at the step portion is less likely to occur. Moreover, if the thickness is not more than a certain value, it will be easy to maintain an excellent appearance at the time of manufacture. Furthermore, the thickness of the adhesive sheet of the present invention does not include the thickness of the spacer.

The haze (in accordance with JIS K7136) of the adhesive sheet of the present invention is not particularly limited, but is preferably 1.2% or less, more preferably 1.1% or less, further preferably 1.0% or less, still more preferably 0.9% or less, especially Preferably less than 0.8%. When the haze is 1.2% or less, it is easy to obtain excellent transparency or an excellent appearance. For example, the above-mentioned haze can be set to a thickness of 25 μm of the adhesive layer, which is left to stand at a normal state (23°C, 50% R.H.) for at least 24 hours, and then attached to a glass slide (for example, the total light transmittance is 91.8%, haze 0.4%), and the obtained product was used as a sample, and measured using a haze meter (product name "HM-150", manufactured by Murakami Color Technology Laboratory Co., Ltd.).

The total light transmittance (according to JIS K7361-1) of the adhesive sheet of the present invention in the visible light wavelength region is preferably 85% or more, more preferably 88% or more, further preferably 89% or more, and still more preferably 90% More than 91%, preferably more than 91%, and most preferably more than 92%. When the total light transmittance is 85% or more, it is easy to obtain excellent transparency or excellent appearance. The above-mentioned total light transmittance can be set, for example, to a thickness of 25 μm of the adhesive layer, which is left to stand at a normal state (23°C, 50% R.H.) for at least 24 hours, and then peeled off when there is a spacer, and bonded On a slide glass (for example, total light transmittance 91.8%, haze 0.4%), set the resultant as a sample, and use a haze meter (product name "HM-150", manufactured by Murakami Color Technology Research Institute Co., Ltd. ) to measure.

The haze and total light transmittance of the adhesive layer of the present invention can be adjusted by adjusting the monomer composition, the type or content of additives, and the like.

The adhesive sheet of the present invention is not particularly limited, and is preferably manufactured according to known or customary manufacturing methods. For example, when the adhesive sheet of the present invention is a substrate-less adhesive sheet, it can be obtained by forming the above-mentioned adhesive layer on a separator by the above-mentioned method. Also, when the adhesive sheet of the present invention is an adhesive sheet with a base material, it can be obtained by directly forming the above-mentioned adhesive layer on the surface of the base material (direct printing method), or by temporarily applying the adhesive layer on the spacer. Form the above-mentioned adhesive layer on the substrate, and then transfer (laminate) to the substrate, thereby obtaining the above-mentioned adhesive layer on the substrate (transfer printing method).

The adhesive sheet of the present invention may have other layers in addition to the above-mentioned adhesive layer. Examples of other layers include: other adhesive layers (adhesive layers other than the above-mentioned adhesive layer (adhesive layer other than the adhesive layer formed from the adhesive composition of the present invention)), intermediate layer, base layer, etc. coating etc. In addition, the adhesive sheet of this invention may have other layers of 2 or more layers.

When the adhesive sheet of the present invention is an adhesive sheet with a base material, for example, various optical films such as plastic films, anti-reflection (AR) films, polarizing plates, and retardation plates may be mentioned. Examples of materials such as the aforementioned plastic film include: polyester resins such as polyethylene terephthalate (PET); (meth)acrylic resins such as polymethyl methacrylate (PMMA); polycarbonate , triacetyl cellulose (TAC), polystyrene, polyarylate, polyimide, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, ethylene-propylene copolymer, trade name "Arton (cyclic Olefin-based polymers, manufactured by JSR Co., Ltd.), cyclic olefin-based polymers such as "Zeonor (cyclic olefin-based polymers, manufactured by Japan Zeon Co., Ltd.)" and "Zeonor"; fluorine-based polymers and other plastic materials. Furthermore, these plastic materials can be used alone or in combination of two or more. In addition, the above-mentioned "substrate" refers to the part that is attached to the adherend together with the adhesive layer when the adhesive sheet is attached to the adherend. The spacer (release liner) to be peeled off when the adhesive sheet is used (attached) is not included in the "substrate".

The aforementioned substrate is preferably transparent. The total light transmittance (according to JIS K7361-1) of the above substrate in the visible light wavelength region is preferably 85% or more, more preferably 88% or more, further preferably 89% or more, and still more preferably 90% or more, The best is above 91%, and the best is above 92%. Moreover, the haze of the said base material (according to JIS K7136) becomes like this. Preferably it is 1.0 % or less, More preferably, it is 0.8 % or less. As such a transparent base material, non-alignment films, such as a PET film, a brand name "Arton", and a brand name "Zeonor", etc. are mentioned, for example. In particular, a non-alignment film is preferable because its characteristics do not depend on the direction of the electric field of the millimeter wave.

The thickness of the above substrate is not particularly limited, for example, it is preferably 12-500 μm. Furthermore, the aforementioned base material may have any form of a single layer or a multi-layer. In addition, known and conventional surface treatments such as physical treatments such as corona discharge treatment, plasma treatment, and electron beam treatment; and chemical treatments such as primer treatment can also be appropriately performed on the surface of the above-mentioned substrate.

The adhesive sheet of the present invention may be provided with a spacer (release liner) on the adhesive surface before use. Furthermore, when the adhesive sheet of the present invention is a double-sided adhesive sheet, each adhesive surface can be protected by two spacers, or one spacer can be used as a double-sided peeling surface, and the winding can be Rolled shape protection. The spacer is used as a protective material for the adhesive layer, and it is peeled off when it is attached to the adherend. In addition, when the adhesive sheet of the present invention is a substrate-less adhesive sheet, the spacer also serves as a support for the adhesive layer. Furthermore, the spacer may not necessarily be provided.

As the separator, a commonly used release paper or the like can be used without any particular limitation. For example, a base material having a release treatment layer, a low-adhesion base material containing a fluoropolymer, or a low-adhesion base material containing a non-polar polymer, etc. may be mentioned. Examples of the base material having the release treatment layer include plastic films or paper surface-treated with a release treatment agent such as silicone-based, long-chain alkyl-based, fluorine-based, or molybdenum sulfide. As the fluorine-based polymer in the above-mentioned low-adhesion base material containing a fluoropolymer, for example, polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene-hexafluoroethylene Fluoropropylene copolymer, chlorofluorovinyl-vinylidene fluoride copolymer, etc. In addition, as the above-mentioned nonpolar polymer, for example, olefin-based resins (such as polyethylene, polypropylene, etc.) can be exemplified, and polyester-based substrates (polyethylene terephthalate-based substrates, polynaphthalene-based substrates, etc.) can also be used. Diformate-based substrates, polybutylene terephthalate-based substrates, etc.), etc. Furthermore, the spacers can be formed by known or customary methods. Moreover, the thickness etc. of a spacer are not specifically limited, either.

Since the adhesive sheet of the present invention has the adhesive layer of the present invention, it is excellent in adhesiveness and foaming and peeling resistance, furthermore, it is excellent in stress relaxation and excellent in step followability. Therefore, adhesion reliability, especially adhesion reliability at high temperature is excellent. Moreover, it is excellent in appearance.

Therefore, the adhesive sheet of the present invention can be usefully used for lamination of members which tend to generate foaming at the interface at high temperature. For example, polymethyl methacrylate resin (PMMA) sometimes contains unreacted monomers, and foaming caused by foreign matter is likely to occur at high temperatures. In addition, polycarbonate (PC) is prone to outgassing of water and carbon dioxide at high temperature. Since the adhesive sheet of the present invention is excellent in foaming and peeling resistance, it can also be usefully used for a plastic adherend including such a resin.

In addition, the adhesive sheet of the present invention can be usefully used for an adherend having a relatively large linear expansion coefficient as well as being useful for an adherend having a relatively small linear expansion coefficient. In addition, as an adherend with a small linear expansion coefficient, for example, a glass plate (with a linear expansion coefficient of 0.3×10 ^-5 to 0.8×10 ^-5 /°C), a polyethylene terephthalate base material (PET film, coefficient of linear expansion 1.5×10 ^-5 to 2×10 ^-5 /°C), etc. In addition, as the adhered body with a large linear expansion coefficient, for example, a resin base material with a large linear expansion coefficient can be cited, and more specifically, a polycarbonate resin base material (PC, with a linear expansion coefficient of 7 ×10 ^-5 ～8×10 ^-5 /℃), polymethyl methacrylate resin substrate (PMMA, linear expansion coefficient 7×10 ^-5 ～8×10 ^-5 /℃), cycloolefin polymer substrate (COP, coefficient of linear expansion 6×10 ^-5 to 7×10 ^-5 /°C), trade name “Zeonor” (manufactured by Japan Zeon Co., Ltd.), trade name “Arton” (manufactured by JSR Co., Ltd.), etc.

The adhesive sheet of the present invention can be usefully used for laminating an adherend with a small coefficient of linear expansion and an adherend with a large coefficient of linear expansion. Specifically, the adhesive sheet of the present invention can be preferably used for laminating glass substrates (such as glass plates, chemically strengthened glass, glass lenses, etc.) and the above-mentioned resin substrates with a large coefficient of linear expansion.

In this way, the adhesive sheet of the present invention is useful for laminating adherends of various materials, especially for lamination of glass adherends and plastic adherends. Furthermore, the plastic adherend can also be an optical film such as a plastic film having an ITO (Indium Tin Oxide) (indium and tin oxide) layer on its surface.

Furthermore, the adhesive sheet of this invention can be usefully used not only for the adherend which has a smooth surface, but also usefully for the adherend which has a level difference in the surface. In particular, even if at least one of the glass substrate and the aforementioned resin substrate having a large linear expansion coefficient has a step difference on the surface, the adhesive sheet of the present invention can be usefully used for a glass substrate and the above-mentioned resin substrate having a large linear expansion coefficient. Bonding of larger resin substrates.

The adhesive sheet of the present invention can be preferably used in the manufacture of portable electronic devices. As above-mentioned portable electronic equipment, for example can enumerate: mobile phone, PHS (Personal Handyphone System, personal portable telephone system), smart phone, tablet (tablet type computer), mobile computer (mobile PC), portable information terminal (PDA), electronic notepad, portable TV or portable radio and other portable broadcast transceivers, portable game consoles, walkmans, portable DVD (Digital Versatile Disc) players, digital cameras Such as cameras, camcorder type camcorders, etc.

The adhesive sheet of the present invention can be preferably used for attaching components or modules constituting a portable electronic device to each other, or fixing components or modules constituting a portable electronic device to a housing, etc., for example. More specifically, it can be exemplified: bonding of cover glass or lens (especially glass lens) to touch panel or touch sensor, antenna module; cover glass or lens (especially glass lens) to the housing Fixing of the display panel to the casing; fixing of the antenna module to the casing; fixing of input devices such as sheet keyboards or touch panels to the casing; bonding of the protective panel of the information display part and the casing; Bonding of bodies; bonding of shells and decorative sheets; fixing or bonding of various components or modules that constitute portable electronic devices, etc. Furthermore, in this specification, a display panel refers to a structure including at least a lens (especially a glass lens) and a touch panel. In addition, the lens in this specification includes both the concept of the transparent body which shows the refraction action of light, and the transparent body which does not have the refraction action of light. That is, the lens in this specification also includes a simple window panel without refraction.

Furthermore, the adhesive sheet of this invention can be used preferably for an optical use. That is, the adhesive sheet of the present invention is preferably an optical adhesive sheet used for optical use. More specifically, for example, it is preferably used for bonding optical members (for bonding optical members), or manufacturing applications of products (optical products) using the above-mentioned optical members, and the like.

As an optical member, the following optical members may be mentioned, which are those having at least the above-mentioned adhesive sheet and a substrate, and the above-mentioned substrate is provided with metal electrodes and wiring (such as copper, silver, ITO wiring, etc.) The adhesive layer of the present invention is bonded to the surface on the side having the above-mentioned metal electrodes and wiring. Furthermore, the above-mentioned adhesive sheet may be provided with a spacer on the adhesive surface before use, but the above-mentioned adhesive sheet in the optical member of the present invention is an adhesive sheet for use, and therefore does not have a spacer.

Furthermore, it is preferable that the optical member has the adhesive layer on the side of the substrate opposite to the side having the metal electrodes and wiring, and it is further more preferable that it has the adhesive layer on the side of the substrate opposite to the side having the metal electrodes and wiring. The above-mentioned adhesive layer is pasted on the surface.

Examples of materials constituting the metal electrodes and wiring include titanium, silicon, niobium, indium, zinc, tin, gold, silver, copper, aluminum, cobalt, chromium, nickel, lead, iron, palladium, platinum, and tungsten. , zirconium, tantalum, hafnium and other metals; ITO (indium and tin oxide), zinc oxide, tin oxide and other metal oxides. Furthermore, those containing two or more of these metals and metal oxides, or alloys containing these metals as main components can also be exemplified. Among them, gold, silver, copper, and ITO are preferable from the viewpoint of conductivity, silver, copper, and ITO are more preferable from the viewpoint of conductivity and cost, and ITO is further preferable from the viewpoint of transparency. That is, the above-mentioned metal electrodes and wiring are preferably silver, copper, or ITO wiring, more preferably ITO wiring. In addition, the same applies to the materials constituting the millimeter-wave antenna element described below. The above-mentioned metal electrodes and wirings can be blackened by forming films such as nitrides, oxides, sulfides, etc. processing.

Optical components refer to components with optical properties (such as polarization, light refraction, light scattering, light reflection, light transmission, light absorption, light diffraction, optical rotation, visibility, electromagnetic wave transmission, etc.) . As the substrate constituting the above-mentioned optical member, for example, devices such as display devices (image display devices) and input devices (optical devices), substrates constituting antenna modules, or substrates used for such devices, for example, : Polarizing plate, wave plate, phase difference plate, optical compensation film, brightness enhancement film, light guide plate, reflective film, anti-reflective film, antenna substrate, hard coating film (hard coating is implemented on at least one side of plastic film such as PET film) treated film), transparent conductive film (such as plastic film with ITO layer on the surface (preferably ITO film such as PET-ITO, polycarbonate, cycloolefin polymer, etc.), etc.), design film, decorative film, surface protection board, Glasses, lenses, color filters, transparent substrates (glass sensors, glass display panels (LCD, etc.), glass substrates with transparent electrodes, etc.), or substrates on which these are laminated (with collectively referred to as "functional film"), etc. In addition, these films may have a metal nanowire layer, a conductive polymer layer, or the like. In addition, thin metal lines may be screen-printed on these films. Also, antenna elements may be provided on the films. In addition, the above-mentioned "plate" and "film" are respectively defined to include forms such as plate, film, sheet, etc., for example, "polarizing film" is defined to include "polarizing plate" and "polarizing sheet". In addition, "film" is assumed to include film sensors and the like.

The metal thin wires may be blackened in advance by forming a film of nitride, oxide, sulfide, etc. of the metal in order to prevent degradation of visibility due to metal reflection and for the purpose of concealment.

As said display device, a liquid crystal display device, an organic EL (electroluminescence) display device, a PDP (plasma display panel), electronic paper, etc. are mentioned, for example. Moreover, a touch panel etc. are mentioned as said input device. Moreover, as an antenna module, the millimeter-wave antenna etc. which are disclosed below can be mentioned, for example.

As the substrate constituting the above-mentioned optical member, for example, a substrate (such as a sheet-shaped Or film, plate substrate, etc.) and so on. Furthermore, the "optical member" in the present invention, as mentioned above, also includes a member that maintains the visibility of the display device or input device and is responsible for decoration or protection (design film, decorative film or surface protection film, etc.) .

If the adhesive sheet of the present invention is an adhesive sheet with a substrate, and the above-mentioned adhesive sheet constitutes a member with optical properties, the above-mentioned substrate can be treated in the same way as the above-mentioned substrate, and the above-mentioned adhesive sheet can also be considered to be a part of the present invention. The optical components.

When the adhesive sheet of the present invention is an adhesive sheet with a substrate, and the above-mentioned functional film is used as the above-mentioned substrate, the adhesive sheet of the present invention can also be used as an "adhesive functional film". "Adhesive functional film" has the above-mentioned adhesive layer on at least one side of the functional film.

[millimeter wave antenna] Since the adhesive sheet of the present invention has an adhesive layer (adhesive layer of the present invention) with a lower dielectric constant and lower dielectric loss at high frequency bands such as millimeter waves, the radiation loss of millimeter waves can be suppressed. Therefore, the adhesive sheet of the present invention can be used for bonding members constituting an antenna for millimeter wave communication (millimeter wave antenna).

In this specification, "millimeter wave communication" refers to communication in the frequency band of 20 GHz to 300 GHz.

As a member constituting a millimeter-wave antenna, there may be, for example, a substrate (hereinafter, sometimes referred to as a "millimeter-wave antenna element") for at least one side of an antenna element (hereinafter, sometimes referred to as a "millimeter-wave antenna element") for transmitting and receiving millimeter waves. Antenna Substrate").

As the millimeter-wave antenna substrate, the plastic film used in the base material of the above-mentioned adhesive sheet can be exemplified. From the viewpoint of suppressing the radiation loss of the millimeter-wave, it is preferably a material with a low dielectric constant and low dielectric loss, especially Cyclic olefin-based polymers such as trade name "Arton" (manufactured by JSR Co., Ltd.) and trade name "Zeonor" (manufactured by Japan Zeon Co., Ltd.).

From the aspect of suppressing the radiation loss of the millimeter wave, the dielectric constant of the millimeter wave antenna substrate at 28 GHz and/or 60 GHz is preferably 2.0 to 5.0, more preferably 2.1 to 4.5, further preferably 2.2 to 4.0, and further More preferably 2.2-3.5, especially preferably 2.2-3.4, most preferably 2.2-3.3, 2.2-3.2, 2.2-3.1 or 2.2-3.0. Also, from the aspect of suppressing the radiation loss of the millimeter wave, the dielectric loss of the millimeter wave antenna substrate at 28 GHz and/or 60 GHz is preferably 0.0001-0.05, more preferably 0.001-0.029, and more preferably 0.002-0.028 , and more preferably 0.003-0.027, especially 0.004-0.026, most preferably 0.005-0.025, 0.006-0.024, 0.007-0.023, 0.008-0.022, 0.009-0.021, 0.010-0.020, 0.011-0.019, 0.0 12～0.018 , 0.013~0.017, 0.014~0.016 or 0.014~0.015.

The millimeter wave antenna substrate is preferably transparent. The total light transmittance (according to JIS K7361-1) of the millimeter-wave antenna substrate in the visible light wavelength region is not particularly limited, but is preferably 85% or more, more preferably 88% or more, further preferably 89% or more, and even more preferably The best is more than 90%, the best is more than 91%, and the best is more than 92%. Also, the haze of the millimeter-wave antenna substrate (based on JIS K7136) is not particularly limited, but is preferably 1.2% or less, more preferably 1.1% or less, further preferably 1.0% or less, still more preferably 0.9% or less, especially Preferably less than 0.8%.

Considering the installation of the millimeter-wave antenna element and the suppression of the radiation loss of the millimeter-wave, the thickness of the millimeter-wave antenna substrate is preferably 5-250 μm. Furthermore, the millimeter-wave antenna substrate may have any form of a single layer or a multi-layer. In addition, the surface of the millimeter-wave antenna substrate may be appropriately subjected to known and conventional surface treatments such as physical treatment such as corona discharge treatment and plasma treatment; chemical treatment such as primer treatment; and coating such as hard coating.

The millimeter-wave antenna element included in the millimeter-wave antenna substrate is not particularly limited as long as it can transmit and receive millimeter waves. From the viewpoint of efficiently receiving millimeter waves with portable communication devices such as smartphones, it is preferable to use related array antenna. The phase array antenna is an antenna capable of transmitting and receiving in a desired direction by arranging a plurality of antenna elements in an array and controlling the phase of each antenna element. That is, the phase array antenna is capable of transmitting or receiving radio waves in a desired direction by electronically controlling the phase (beam steering) of each antenna element regardless of the direction of the antenna.

Known antennas can be used without particular limitation as the millimeter wave antenna element, for example, an antenna element having a resonant element constructed from a loop antenna structure, a patch antenna structure, or a stacked patch antenna Body, patch antenna structure with parasitic elements, inverted F antenna structure, slot antenna structure, planar inverted F antenna structure, monopole, dipole, helical antenna structure, Yagi (Yagi/Uda) antenna structure Bulk, surface-area bulk waveguide structures, mixtures of these designs, etc. For combinations of different frequency bands, different kinds of mmWave antenna elements can be used. From the viewpoint of efficiently receiving millimeter waves with portable communication devices such as smartphones, a phase array antenna in which patch antenna elements are arranged in an array is preferable.

The material constituting the millimeter wave antenna element is not particularly limited, for example, titanium, silicon, niobium, indium, zinc, tin, gold, silver, copper, aluminum, cobalt, chromium, nickel, lead, iron, palladium, Platinum, tungsten, zirconium, tantalum, hafnium and other metals; ITO (indium and tin oxide), zinc oxide, tin oxide and other metal oxides. Furthermore, one containing two or more of these metals or metal oxides, or an alloy containing these metals as a main component may also be exemplified. Among them, silver, copper, and ITO are preferable from the viewpoint of conductivity, and ITO is more preferable from the viewpoint of transparency and visibility. That is, the millimeter-wave antenna element described above preferably contains ITO.

In addition, when the antenna element contains metals such as silver and copper, for the purpose of hiding the antenna element and preventing the degradation of visibility caused by the reflection of the metal, it can also be formed by forming the nitride, oxide, or sulfide of the metal. The film of objects and the like shall be blackened in advance.

In addition, the millimeter-wave antenna substrate may also have a transmission line path for transmitting signals received and received by the millimeter-wave antenna element to the transceiver circuit. Transmission line paths may include coaxial cable paths, microstrip transmission lines, stripline transmission lines, edge-coupled microstrip transmission lines, edge-coupled stripline transmission lines, waveguide structures (such as coplanar waveguides or grounded coplanar waveguide), a transmission line formed by a combination of these types of transmission lines, etc. The material constituting the transmission line path is also not particularly limited, and the material constituting the millimeter wave antenna element can be used.

As a member constituting the millimeter wave antenna, there may be mentioned a cover member which is laminated on the millimeter wave antenna substrate in order to protect the millimeter wave antenna elements arranged on the millimeter wave antenna substrate. As a cover member, optical films, such as glass or a plastic film, can be used, for example.

Examples of materials such as plastic films include: polyester resins such as polyethylene terephthalate (PET); (meth)acrylic resins such as polymethyl methacrylate (PMMA); polycarbonate; Triacetyl cellulose (TAC); Polyethylene; Polyarylate; Polyimide; Transparent polyimide; Polyvinyl chloride; Polyvinyl acetate; Fluorine resin; Polyethylene, polypropylene, ethylene-propylene copolymer Plastic materials such as polyolefin-based resins such as polyolefin resins; trade names "Arton" (manufactured by JSR Co., Ltd.) and "Zeonor" (manufactured by Japan Zeon Co., Ltd.) and other cyclic olefin-based polymers. These plastic materials can be used alone or in combination of two or more.

Considering the suppression of radiation loss of millimeter waves, the dielectric constant of the cover member at 28 GHz and/or 60 GHz is preferably 2.0 to 5.0, more preferably 2.1 to 4.5, more preferably 2.2 to 4.0, and even more preferably Preferably it is 2.2-3.5, especially preferably 2.2-3.4, most preferably 2.2-3.3, 2.2-3.2, 2.2-3.1 or 2.2-3.0. Also, from the aspect of suppressing the radiation loss of millimeter waves, the dielectric loss of the cover member at 28 GHz and/or 60 GHz is preferably 0.0001-0.050, more preferably 0.001-0.02, and still more preferably 0.002-0.019, Furthermore, it is more preferably 0.003 to 0.018, especially preferably 0.004 to 0.017, most preferably 0.005 to 0.016, 0.006 to 0.015, 0.007 to 0.014, 0.008 to 0.013, 0.009 to 0.012, or 0.010 to 0.011.

The above-mentioned cover member is preferably transparent. The total light transmittance (according to JIS K7361-1) of the cover member in the visible light wavelength region is preferably 85% or more, more preferably 88% or more, further preferably 89% or more, and still more preferably 90% or more, The best is above 91%, and the best is above 92%. Also, the haze of the cover member (in accordance with JIS K7136) is preferably 1.2% or less, more preferably 1.1% or less, further preferably 1.0% or less, still more preferably 0.9% or less, especially preferably 0.8% or less.

In view of suppressing the radiation loss of millimeter waves, the thickness of the cover member is preferably 0.025-1.5 mm. Furthermore, the cover member may have either a single layer or a multilayer form. In addition, the surface of the cover member may be suitably subjected to known and commonly used surface treatments such as physical treatment such as corona discharge treatment and plasma treatment; chemical treatment such as primer treatment; and coating such as hard coating.

The adhesive sheet of the present invention can be preferably used in the manufacture of millimeter-wave antennas used in portable communication devices. As said portable communication device, a mobile phone, PHS, a smart phone, a tablet (tablet computer), a mobile computer (mobile PC), a portable information terminal (PDA), etc. are mentioned, for example.

The millimeter-wave antenna may have members other than the above-mentioned millimeter-wave antenna substrate, cover member, and adhesive sheet, such as a polarizer, a wave plate, a phase difference plate, an optical compensation film, a brightness enhancement film, a light guide plate, a reflection film, an anti- Reflective film, hard coat film, transparent conductive film, design film, decorative film, surface protection plate, stencil, lens, color filter, transparent substrate, or image display panel (such as liquid crystal display panel, organic EL panel, electric pulp display panel, etc.), etc. The image display panel may have a touch sensor.

The millimeter wave antenna can be arranged at any position of the portable communication device, specifically, it can be arranged at the front, back and side of the portable communication device. Moreover, the front of the portable communication device refers to the surface facing the user when the user uses the portable communication device. For example, the surface with the display panel corresponds to the front, and the housing corresponds to the back and side. Furthermore, a display panel refers to a composition including at least a lens (especially a glass lens) and a touch panel.

The size (area) of the millimeter wave antenna is also not limited, and it may be formed on the entire surface of each surface of the portable communication device, or arranged on a part thereof. Also, the shape of the millimeter wave antenna is not particularly limited, and may be, for example, square, circular, or wire-shaped. Moreover, it is also possible to arrange|position in frame shape. Furthermore, the number of millimeter-wave antennas arranged in the portable communication device is not limited, and may be one, or a plurality of antennas may be arranged at any position. When a plurality of millimeter-wave antennas are arranged, the sizes (areas) may be the same or different. In order to improve the visibility, a dummy pattern without a millimeter wave antenna can also be arranged on the part of the portable communication device that does not have a millimeter wave antenna.

The millimeter-wave antenna of the present invention has at least the above-mentioned adhesive sheet and a substrate, as long as the above-mentioned substrate is provided with an antenna element (millimeter-wave antenna element) on one side, and on the side of the above-mentioned substrate (millimeter-wave antenna substrate) that has the above-mentioned antenna element It only needs to stick the above-mentioned adhesive sheet on the surface, and there is no special limitation on other aspects. Furthermore, since the above-mentioned adhesive sheet in the millimeter wave antenna of the present invention is an adhesive sheet for use, there is no spacer.

As the above-mentioned millimeter-wave antenna, it is preferable to bond the millimeter-wave antenna substrate to other optical members (the above-mentioned adhesive sheet may or may not be provided, but it is preferable to have it in view of further suppressing the radiation loss of the millimeter-wave). form of composition. In addition, the above-mentioned other optical members may be singular or plural.

In the case of the above-mentioned aspect, the bonding aspect of the millimeter-wave antenna of the present invention and the above-mentioned other optical members can be exemplified, for example: (1) The millimeter-wave antenna substrate of the present invention is bonded to the above-mentioned optical member through the adhesive sheet of the present invention. Aspects of attaching other optical components, (2) Aspects of adhering the adhesive sheet of the present invention including or constituting a millimeter-wave antenna substrate to the above-mentioned other optical components, (3) attaching the millimeter-wave antenna substrate through the adhesive tape of the present invention An aspect of attaching the antenna substrate to members other than the millimeter wave antenna substrate, (4) an aspect of attaching the adhesive tape of the present invention including or constituting the millimeter wave antenna substrate to members other than the millimeter wave antenna substrate. Furthermore, in the aspect of (2) above, the adhesive sheet of the present invention is preferably a double-sided adhesive sheet whose base material is a millimeter-wave antenna substrate.

Next, preferred embodiments of the millimeter-wave antenna of the present invention will be described with reference to the drawings.

FIG. 1 shows a millimeter-wave antenna 1A having at least an adhesive sheet 10 and a millimeter-wave antenna substrate 11 as a substrate. The millimeter-wave antenna substrate 11 has a millimeter-wave antenna element 2 on one side. The adhesive sheet 10 is pasted on the surface of the millimeter-wave antenna substrate 11 on the side with the millimeter-wave antenna element 2 .

FIG. 2 shows a millimeter-wave antenna 1B having a cover member 12 , an adhesive sheet 10 , and a millimeter-wave antenna substrate 11 sequentially in contact with each other. The millimeter-wave antenna substrate 11 is provided with the millimeter-wave antenna element 2 on the side of the adhesive sheet 10 , and the adhesive sheet 10 is attached to the surface of the millimeter-wave antenna substrate 11 on the side having the millimeter-wave antenna element 2 . The cover member 12 is preferably glass. In view of low dielectric constant and low dielectric loss, the millimeter-wave antenna substrate 11 is preferably COP, and the millimeter-wave antenna element 2 is preferably copper, silver, or ITO.

FIG. 3 shows a millimeter-wave antenna 1C having a cover member 12 , an adhesive sheet 10 a , a millimeter-wave antenna substrate 11 , an adhesive sheet 10 b , and an image display panel 13 in sequential contact with each other. The millimeter-wave antenna substrate 11 is provided with the millimeter-wave antenna element 2 on the side of the adhesive sheet 10 a , and the adhesive sheet 10 a is bonded to the surface of the millimeter-wave antenna substrate 11 on the side having the millimeter-wave antenna element 2 . The cover member 12 is preferably made of glass. In terms of low dielectric constant and low dielectric loss, the millimeter-wave antenna substrate 11 is preferably COP. In terms of transparency and visibility, the millimeter-wave antenna element 2 is preferably ITO. , or silver or copper that has been blackened with a film such as nitride, oxide, or sulfide. The adhesive sheet 10b may or may not be the adhesive sheet of the present invention, but is preferably the adhesive sheet of the present invention. The image display panel 13 may have a touch sensor (not shown).

In the millimeter-wave antennas 1A-1C of FIGS. 1-3, since the adhesive sheets 10, 10a and the preferred adhesive sheet 10b include the adhesive layer of the present invention with low dielectric constant and low dielectric loss in the high-frequency band, Therefore, the radiation loss of the millimeter wave can be suppressed, and the millimeter wave communication can be carried out efficiently. In addition, since millimeter wave communication can be efficiently performed, the area of the antenna can be reduced and the antenna can be miniaturized. [Example]

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited by these examples.

(Example 1) In a reaction vessel equipped with a condenser tube, a nitrogen gas introduction tube, a thermometer, and a stirring device, _C12-13 alkyl methacrylate (Kyoeisha Chemical Co., Ltd. Co., Ltd., product name "L-7MA") 99.0 parts by mass, 1.0 parts by mass of hydroxyethyl methacrylate (HEMA), 2,2'-azobisisobutyronitrile ( AIBN) 0.2 parts by mass, ethyl acetate as a polymerization solvent, nitrogen gas was flowed in, and nitrogen substitution was performed for about 1 hour while stirring. Thereafter, the reaction vessel was heated to 70° C., and reacted for 6 hours. Furthermore, the reaction container was heated at 80 degreeC, it reacted for 3 hours, and the (meth)acrylic-type polymer with a weight average molecular weight (Mw) of 400,000 was obtained. In this (meth)acrylic polymer solution (100 parts by mass of solid content), an isocyanate-based crosslinking agent (trade name "Coronate HX", manufactured by Tosoh Co., Ltd., solid content) was added on the basis of solid content. 0.1 part by mass of dioctyltin dilaurate (trade name "EMBILIZEROL-1", manufactured by Tokyo Fine Chemicals Co., Ltd.) as a crosslinking accelerator, 0.01 part by mass as a crosslinking retarder 5 parts by mass of acetylacetone were uniformly mixed to prepare the adhesive composition of this example.

The above-mentioned adhesive composition was applied to a polyethylene terephthalate (PET) spacer (trade name "MRF38", Mitsubishi Chemical Corporation Manufacturing), a coating layer (adhesive composition layer) is formed. Then, drying treatment was carried out for 120 minutes using a dryer at 130° C. to volatilize the residual monomers. Furthermore, a PET spacer (trade name "MRE38", manufactured by Mitsubishi Chemical Co., Ltd.) was placed on the above-mentioned coating layer to obtain a double-sided adhesive sheet without a substrate. The double-sided adhesive sheet without a substrate only includes an adhesive The adhesive layer, and both sides of the adhesive layer are protected by spacers.

(Examples 2-38) A substrate-less double-sided adhesive sheet was obtained in the same manner as in Example 1, except that each monomer component was prepared in the amount shown in Tables 1 and 2.

(comparative example 1) Mix 2-ethylhexyl acrylate (2EHA), isodecyl acrylate (IDA), acrylic acid (MA), 4-hydroxybutyl acrylate (4HBA), and 2,2'-azobisisobutyronitrile (AIBN) as a thermal polymerization initiator are put into the polymerization solvent so that the monomer component becomes 40%. Ethyl acetate was flowed into nitrogen, and nitrogen replacement was performed for about 1 hour while stirring. Thereafter, the reaction vessel was heated to 60° C., and reacted for 6 hours. Furthermore, the reaction container was heated to 75 degreeC, it reacted for 2 hours, and the acryl-type polymer was obtained. Except for this, the substrate-less double-sided adhesive sheet was obtained in the same manner as in Example 1.

In addition, the monomers used shown in Tables 1 and 2 are as follows.・LMA: Lauryl methacrylate ・LA: Lauryl acrylate ・2-EHA: 2-Ethylhexyl acrylate ・i-NA: Isononyl acrylate ・L-7MA: C _12-13 alkyl methacrylate・IDMA: Isodecyl methacrylate ・HEMA: 2-Hydroxyethyl methacrylate ・MMA: Methyl methacrylate ・MMA-macromonomer: Methyl methacrylate ・CHMA: Cyclohexyl methacrylate・IBXMA: Isomethacrylate ・MAA: Methacrylic acid ・NVP: N-vinylpyrrolidone ・PHE-1G: 2-phenoxyethyl methacrylate ・BzMA: Benzyl methacrylate ・M- 20G: 2-(2-methoxyethoxy)ethyl methacrylate・IDA: Isodecyl acrylate・MA: Methyl acrylate・4-HBA: 4-Hydroxybutyl acrylate

[Characteristic evaluation] The following measurements and evaluations were performed on the substrate-less double-sided adhesive sheets of Examples and Comparative Examples. The evaluation results are shown in Tables 1 and 2.

(1) Evaluation of dielectric constant and dielectric loss For the adhesive layer monomer obtained in the examples or comparative examples (those obtained by peeling the silicone-treated PET spacer from the double-sided adhesive sheet), the following equipment was used to measure at frequencies of 28 GHz and 60 GHz The dielectric constant and dielectric loss. About the measurement, in the case of 28 GHz, it was carried out on the area of the circle with a diameter of 8 cm, and in the case of 60 GHz, it was carried out on the area of the circle with the diameter of 4 cm. Make at least 3 samples for each sample, remove the maximum and minimum values of the measured values of the 3 samples, and set the average value as the dielectric constant and dielectric loss at each frequency. ・Measurement method: Open type resonator method JIS R1660-2 ・Device: Made by KEYCOM Co., Ltd., dielectric constant measurement system by interference type resonator method ・Measurement environment: 23±1℃, 52%±1%R.H.

(2) Total light transmittance and haze Peel off one spacer from the double-sided adhesive sheet, and attach the double-sided adhesive sheet to a glass slide (manufactured by Songnang Glass Industry Co., Ltd., "White Polishing No. 1", thickness 0.8-1.0 mm, full light The transmittance is 92%, the haze is 0.2%), and then the other spacer is peeled off to make a test piece with a double-sided adhesive sheet (adhesive layer)/glass slide layer. Using a haze meter (product name "HM-150", manufactured by Murakami Color Research Institute Co., Ltd.), measure the total light transmittance of the above test piece in the visible light region in an environment of 23±1°C and 52±1%RH and haze. Three samples were prepared for each specimen, and the average of the measured values of the three samples was defined as the total light transmittance and haze in the visible light region. Furthermore, the greater the thickness of the test piece, the lower the value of the total light transmittance, and the greater the value of the haze.

(3) Sending and receiving characteristics The transmitting and receiving characteristics of the adhesive layer obtained in the examples or comparative examples (from the double-sided adhesive sheet to which the silicone-treated PET spacer was peeled off) were obtained using the square microstrip antenna shown in FIG. 4 (refer to Electronic Communications "Planar Antenna", Chapter 5, Volume 2, Group 4, Information Society, URL: http://www.ieice hbkb.org/files/04/04Gun_02hen_05.pdf) for evaluation. Specifically, an antenna film 46 was produced, which was formed on the surface of a COP base material (trade name "Zeonor", manufactured by Zeon Co., Ltd., Japan) with a thickness of 100 μm as the antenna substrate 44. The shape shown in FIG. A patch antenna 43, and a copper ground layer 45 with a thickness of 1 μm is formed on the back. The dimensions of the millimeter wave patch antenna 43 were adjusted so as to be optimal for lamination with the adhesives of the examples and comparative examples (vertical A: 2.8 to 3.2 mm, horizontal B: 4.13 mm). On the patch antenna 43 side of the above-mentioned antenna film 46, the adhesive layer 42 of each example and comparative example is pasted so that air bubbles or foreign matter do not enter, and then bonded to chemically strengthened glass with a thickness of 0.7 mm as the cover glass 41 (manufactured by Corning Incorporated), and the antenna laminate 4 of the cover glass 41/adhesive layer 42/antenna film 46 was produced. Power is supplied from the microstrip line 43a connected to the millimeter-wave patch antenna 43 of various antenna laminates 4, and the transmission and reception characteristics at a frequency band of 30 GHz are evaluated. The gain (5.7 dB) of the antenna film 46) was evaluated as ◯, and the case where the gain (5.7 dB) was improved was evaluated as ×.

[Table 1] Table 1 Example 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Monomers used (parts by mass) LMA parts by mass 99.0 86.0 86.0 98.9 96.9 94.9 94.9 86.0 79.0 66.0 50.0 86.0 79.0 66.0 86.0 79.0 66.0 L-7MA 99.0 IDMA 99 HEMA 1.0 1.0 1.0 1.0 1.0 0.1 0.1 0.1 0.1 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 MMA 13.0 MMA - macromonomer 13.0 CHMA 13.0 20.0 33.0 49.0 DCPMA 13.0 20.0 33.0 IBXMA 13.0 20.0 33.0 MAA 1.0 3.0 5.0 NVP 5.0 AIBN (parts by mass) 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 Dielectric constant 28GHz 2.27 2.32 2.41 2.47 2.30 2.24 2.69 2.26 2.31 2.18 2.26 2.46 2.34 2.55 2.38 2.35 2.32 2.56 2.63 60GHz 2.39 2.33 2.44 2.12 2.47 2.44 2.66 2.66 2.23 2.13 2.44 2.49 2.48 2.35 2.34 2.89 2.19 2.24 2.49 Dielectric loss 28GHz 0.004 0.005 0.006 0.004 0.006 0.003 0.004 0.003 0.005 0.005 0.004 0.004 0.004 0.004 0.003 0.003 0.003 0.004 0.003 60GHz 0.001 0.003 0.004 0.003 0.004 0.002 0.004 0.002 0.003 0.003 0.003 0.002 0.003 0.002 0.003 0.002 0.004 0.002 0.003 transparency Total light transmittance % 93.0 93.0 92.8 92.8 92.6 92.9 92.7 92.8 92.8 92.4 92.8 92.6 92.5 92.8 92.7 92.7 92.8 92.7 92.6 Haze 0.20 0.30 0.40 0.60 1.20 0.20 0.60 0.80 0.30 0.40 0.50 0.70 0.88 0.30 0.50 0.20 0.40 0.50 0.80 Adherence N/20 mm 4.8 5.0 16.2 7.5 6.1 8.3 13.2 12.2 6.0 8.5 12.1 19.0 0.2 9.1 12.6 19.6 8.0 12.6 21.6 reception characteristics ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○

[Table 2] Table 2 Example comparative example 20 twenty one twenty two twenty three twenty four 25 26 27 28 29 30 31 32 33 34 35 36 37 38 1 use monomer LMA parts by mass 86.0 79.0 86.0 79.0 86.0 95.0 90.0 80.0 84.5 79.5 74.5 49.5 24.5 74.5 74.5 36.0 50.0 44.5 LA 24.5 2-EHA 14.5 19.5 24.5 49.5 74.5 50.0 40.0 i-NA 24.5 IDMA 39.0 44.5 89.0 HEMA 1.0 1.0 1.0 1.0 1.0 5.0 10.0 20.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 CHMA 13.0 10.0 10.0 10.0 PHE-1G 13.0 20.0 BYZGR 13.0 20.0 IDA 50.00 MA 9.5 4-HBA 13.0 0.5 AIBN (parts by mass) 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 Dielectric constant 28GHz 2.33 2.30 2.52 2.59 2.54 2.26 2.26 2.30 2.31 2.49 2.46 2.25 2.38 2.29 2.45 2.50 2.69 2.61 2.50 2.57 60GHz 2.28 2.32 2.37 3.29 2.19 2.22 2.26 2.64 2.28 2.47 2.39 2.19 2.44 2.18 2.21 2.47 2.58 2.51 2.44 2.47 Dielectric loss 28GHz 0.004 0.005 0.005 0.007 0.029 0.008 0.013 0.019 0.006 0.007 0.007 0.012 0.019 0.006 0.007 0.012 0.004 0.004 0.005 0.030 60GHz 0.003 0.004 0.004 0.003 0.016 0.003 0.009 0.008 0.004 0.006 0.004 0.008 0.011 0.004 0.004 0.008 0.002 0.004 0.005 0.017 transparency Total light transmittance % 92.7 92.6 92.7 92.7 92.8 92.8 92.8 92.7 92.8 92.8 92.9 93.0 92.9 92.9 92.9 92.8 92.7 92.7 92.7 92.1 Haze 0.30 0.40 0.30 0.40 0.30 0.50 0.70 0.10 0.20 0.10 0.40 0.60 0.10 0.10 0.20 0.20 0.40 0.40 0.50 0.3 Adherence N/20 mm 7.9 9.0 10.2 11.4 7.0 5.5 7.9 10.0 6.8 5.9 3.5 3.3 2.9 1.7 4.2 5.1 11.9 13.4 17.0 2.2 reception characteristics ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○

1A: Millimeter wave antenna 1B: Millimeter wave antenna 1C: Millimeter wave antenna 2: Millimeter wave antenna elements 4: Antenna laminate 10: Adhesive sheet 10a: Adhesive sheet 10b: Adhesive sheet 11: Millimeter wave antenna substrate 12: cover member 13: Image display panel 41: cover glass 42: Adhesive layer 43: Patch antenna for millimeter wave 43a: Microstrip line 44: Antenna substrate 45: copper ground plane 46: Antenna film

FIG. 1 is a schematic diagram (sectional view) showing one embodiment of the millimeter wave antenna of the present invention. Fig. 2 is a schematic diagram (sectional view) showing an embodiment of the millimeter wave antenna of the present invention. Fig. 3 is a schematic diagram (sectional view) showing an embodiment of the millimeter wave antenna of the present invention. Fig. 4 is a schematic diagram (cross-sectional view) showing an antenna laminate used for evaluation of transmission and reception characteristics. Fig. 4(a) is a side sectional view, and Fig. 4(b) is a top projection view.

Claims (10)

An adhesive composition having a dielectric constant of 2.0 to 5.0 at a frequency of 28 GHz, The dielectric loss at the frequency of 28 GHz is 0.0001~0.05, and A mixture of a methacrylate compound having a hydrocarbon group having 6 or more carbon atoms and a (meth)acrylate compound having a crosslinkable functional group, a partial polymer or a copolymer thereof. As for the adhesive composition of claim 1, its dielectric constant at a frequency of 60 GHz is 2.0-5.0. An adhesive composition having a dielectric constant of 2.0 to 5.0 at a frequency of 60 GHz, The dielectric loss at the frequency of 60 GHz is 0.0001~0.05, and A mixture of a methacrylate compound having a hydrocarbon group having 6 or more carbon atoms and a (meth)acrylate compound having a crosslinkable functional group, a partial polymer or a copolymer thereof. The adhesive composition according to any one of claims 1 to 3, wherein the above-mentioned hydrocarbon group has an aliphatic group, contains an alicyclic group, or contains an aromatic ring group. The adhesive composition according to any one of claims 1 to 4, wherein the above-mentioned methacrylate compound having a hydrocarbon group having 6 or more carbon atoms in the above-mentioned mixture, a part of its polymer or a copolymer, or a methacrylate compound derived from the compound The content of the structural unit is 25% by mass or more. The adhesive composition according to any one of claims 1 to 5, wherein the above-mentioned (meth)acrylate compound having a crosslinkable functional group in the above-mentioned mixture, its partial polymer or copolymer, or derived from the compound The content of the structural unit is 0.1 to 30% by mass. The adhesive composition according to any one of claims 1 to 6, wherein the above-mentioned hydrocarbon has an alicyclic group or an aromatic group based on the terminal. An adhesive layer formed from the adhesive composition according to any one of claims 1 to 7. An adhesive sheet having an adhesive layer according to claim 8. A millimeter wave antenna, which has at least the adhesive sheet and the substrate according to claim 9, and the above-mentioned substrate has an antenna element on at least one side, and the above-mentioned adhesive is pasted on the surface of the above-mentioned substrate having the above-mentioned antenna element Sheet.

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