Adhesive sheet for film or substrate with conductive pattern formed on it
The adhesive sheet with a radial styrene-based elastomer and tackifying resins addresses the challenge of high transmission loss and adhesive strength issues for cycloolefin polymers, providing stable bonding and dielectric properties in high-frequency electronic devices.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- SEKISUI CHEMICAL CO LTD
- Filing Date
- 2021-09-24
- Publication Date
- 2026-06-17
Smart Images
Figure 0007874946000001 
Figure 0007874946000002 
Figure 0007874946000003
Abstract
Description
[Technical Field]
[0001] The present invention relates to an adhesive sheet for films or substrates, which can be suitably used even when the transmission signal is high frequency, and which has a conductive pattern formed on it that can exhibit high adhesive strength to substrates made of difficult-to-adhere materials such as cycloolefin polymers. [Background technology]
[0002] Adhesive tapes or sheets are widely used in a variety of fields, for example, for assembling portable electronic devices such as mobile phones and personal digital assistants (PDAs), or for fixing in-vehicle electronic device components such as in-vehicle panels to the vehicle body (for example, Patent Documents 1 and 2). [Prior art documents] [Patent Documents]
[0003] [Patent Document 1] Japanese Patent Publication No. 2009-242541 [Patent Document 2] Japanese Patent Publication No. 2009-258274 [Overview of the project] [Problems that the invention aims to solve]
[0004] In recent years, the field of electronic devices has demanded the transmission and reception of larger amounts of data at higher speeds, and the practical application of so-called fifth-generation mobile communication systems (5G) is progressing. Consequently, the frequency of transmission signals is increasing. However, this increase in frequency leads to the problem of increased attenuation of transmission signals ("transmission loss"). Therefore, there is a need for adhesive tapes or sheets used in electronic devices that can suppress such transmission loss and can be suitably used even when transmission signals are at higher frequencies.
[0005] The present invention aims to provide an adhesive sheet for films or substrates that can be suitably used even when the transmission signal is high frequency and has a conductive pattern formed on it that can exhibit high adhesive strength to substrates made of difficult-to-adhere materials such as cycloolefin polymers. [Means for solving the problem]
[0006] The present invention relates to an adhesive sheet used for bonding components in a laminate including a film on which a conductive pattern is formed, bonding components inside a substrate, or bonding a film or substrate on which a conductive pattern is formed to other components, and is of general formula (AB) n The adhesive sheet for films or substrates has an adhesive layer containing a radial styrene elastomer having a structure represented by C and a tackifying resin, wherein the tackifying resin is at least one selected from the group consisting of a natural product-based tackifying resin (T1) containing an aromatic ring with an SP value of 8.0 to 9.0, and a petroleum resin-based or natural product-based tackifying resin (T2) not containing an aromatic ring with an SP value of 7.5 to 8.5, and has a conductive pattern formed on it. A: Aromatic alkenyl polymer block B: Conjugated diene polymer block C: Components derived from coupling agents n: an integer greater than or equal to 3. The present invention will be described in detail below.
[0007] Since transmission loss increases proportionally with frequency, it is an unavoidable problem that transmission loss increases as the frequency of the transmitted signal increases. On the other hand, in electronic devices, films with conductive patterns formed on substrates made of polyimide resin (PI), polyethylene terephthalate (PET), ABS resin, polycarbonate (PC), glass, etc., and substrates with circuit patterns made of copper foil, etc., formed on these substrates are used. As a method to suppress transmission loss in the high frequency band (for example, around 1 to 80 GHz), one known method is to improve the smoothness of the conductive portion made of copper foil, etc., in such films or substrates on which conductive patterns are formed. In addition, a method of using a material with excellent dielectric properties in the high frequency band as the insulating material of the adhesive sheet used to bond the film or substrate on which the conductive pattern is formed to other components is also being considered. That is, since transmission loss is proportional not only to frequency but also to the square root of the dielectric constant of the insulating portion and the linear equation of the dielectric loss tangent, it is expected that transmission loss can be suppressed by using a material with a low dielectric constant and / or a low dielectric loss tangent in the high frequency band.
[0008] The inventors investigated the base resin constituting the adhesive layer in an adhesive sheet used for bonding components in a laminate including a film with a conductive pattern, bonding components within a substrate, or bonding a film or substrate with a conductive pattern to other components. As a result, the inventors found that styrene-based elastomers exhibit excellent dielectric properties in the high-frequency range, that is, they have a low dielectric constant and a low dielectric loss tangent in the high-frequency range. Furthermore, the dielectric properties in the high-frequency range are also affected by the moisture content of the material. The inventors found that styrene-based elastomers have a low moisture content after exposure to a humid environment, and that their dielectric properties in the high-frequency range remain stable even when used in environments with fluctuating humidity, such as outdoors. While there has been some knowledge regarding the dielectric properties of styrene-based elastomers in the low-frequency range (e.g., 100 Hz, 100 kHz, etc.), there has been very little knowledge regarding their dielectric properties in the high-frequency range.
[0009] On the other hand, for the substrate of films or substrates on which conductive patterns are formed, there is a growing interest in using materials with excellent dielectric properties at high frequencies, such as cycloolefin polymers (COP) and liquid crystal polymers (LCP), instead of conventionally used polyimide resins. However, because these materials are difficult to adhere to, when adhesive sheets are bonded to substrates made of these materials, the adhesive strength is insufficient, leading to problems such as peeling. In response to this, the present inventors have discovered that by using a radial-type styrene elastomer having a structure represented by a specific formula, and by adding a specific tackifying resin with excellent compatibility with the radial-type styrene elastomer, an adhesive sheet can be obtained that exhibits high adhesive strength to substrates made of materials that are difficult to adhere to. This led to the completion of the present invention.
[0010] The adhesive sheet for films or substrates having a conductive pattern formed on it (hereinafter also simply referred to as "adhesive sheet") of the present invention is an adhesive sheet used for bonding components together in a laminate including a film having a conductive pattern formed on it, bonding components together inside a substrate, or bonding a film or substrate having a conductive pattern formed on it to other components. The film or substrate on which the above conductive pattern is formed is not particularly limited and may be any film or substrate on which a conductive pattern is formed that is used in electronic devices. Examples include a film on which a conductive pattern is formed on an insulating substrate, and a substrate on which a circuit pattern made of copper foil or the like is formed on an insulating substrate. The above substrate is not particularly limited and may be a substrate made of polyimide resin or the like that which has been used conventionally, but a substrate made of a material with excellent dielectric properties in the high frequency band (a material that is difficult to adhere to), such as cycloolefin polymer (COP) or liquid crystal polymer (LCP), is preferred.
[0011] The adhesive sheet of the present invention is of general formula (AB) n The material has an adhesive layer containing a radial styrene-based elastomer having a structure represented by C, and a tackifying resin. A: Aromatic alkenyl polymer block B: Conjugated diene polymer block C: Components derived from coupling agents n: an integer greater than or equal to 3.
[0012] Styrene-based elastomers exhibit excellent dielectric properties in the high-frequency range. Specifically, they have a low dielectric constant and low dielectric loss tangent in the high-frequency range. Furthermore, the dielectric properties in the high-frequency range are also affected by the moisture content of the material. This is because water molecules have high dielectric constants and dielectric loss tangents, resulting in poor dielectric properties; therefore, the absence of water molecules is necessary to improve dielectric properties. Styrene-based elastomers have a low moisture content after exposure to humid environments, and their dielectric properties in the high-frequency range remain stable even when used in environments with fluctuating humidity, such as outdoors. For these reasons, by including the radial-type styrene-based elastomer in the adhesive layer, the adhesive sheet of the present invention can be suitably used even when the transmitted signal is at a high frequency. Furthermore, the inclusion of the radial-type styrene elastomer improves the adhesive strength of the adhesive layer. In particular, the radial-type styrene elastomer has the property of suppressing viscosity increase even when the molecular weight of the hard segment is increased to improve the adhesive strength of the adhesive layer at high temperatures, thereby improving the adhesive strength of the adhesive layer at high temperatures while also ensuring adhesive strength at room temperature.
[0013] The above general formula (AB) n In C, A represents an aromatic alkenyl polymer block (hard segment), B represents a conjugated diene polymer block (soft segment), C represents a component derived from a coupling agent, and n represents an integer greater than or equal to 3. The above radial-type styrene elastomer is a branched styrene block copolymer having a structure in which multiple styrene block copolymers (AB) with a diblock structure, in which one hard segment and one soft segment are bonded together, protrude radially from a central component (C) derived from a coupling agent. n may be an integer of 3 or more, but n is preferably 4 or more because the adhesive strength of the adhesive layer, particularly the adhesive strength at high temperatures, is improved. The upper limit of n is not particularly limited, but is usually 8 or less from the viewpoint of suppressing the gelation of the radial styrenic elastomer.
[0014] The aromatic alkenyl polymer block represented by A above means a block having a repeating unit derived from an aromatic alkenyl compound. The aromatic alkenyl polymer block represented by A above may be a block having a repeating unit derived from an aromatic alkenyl compound as a main constituent, and may contain a repeating unit derived from another compound such as ethylene. Examples of the aromatic alkenyl polymer block represented by A above include polyalkylstyrenes such as polystyrene, polymethylstyrene, polydimethylstyrene, and poly(t-butylstyrene); polyhalogenated styrenes such as polychlorostyrene, polybromostyrene, polyfluorostyrene, and polyfluorostyrene; polyhalogen-substituted alkylstyrenes such as polychloromethylstyrene; polyalkoxystyrenes such as polymethoxystyrene and polyethoxystyrene; polycarboxyalkylstyrenes such as polycarboxymethylstyrene; polyalkyl ether styrenes such as polyvinylbenzyl propyl ether; polyalkylsilylstyrenes such as polytrimethylsilylstyrene; poly(vinylbenzyl dimethoxyphosphide); acrylonitrile-butadiene-styrene copolymer, and the like. Among them, polystyrene, polymethylstyrene, polydimethylstyrene, and acrylonitrile-butadiene-styrene copolymer are preferable. These aromatic alkenyl polymer blocks may be used alone or in combination of two or more. In addition, vinyl naphthalene, vinyl anthracene, N,N-diethyl-p-aminoethyl styrene, vinyl pyridine, etc. can also be used as the aromatic alkenyl compound. Among the above aromatic alkenyl compounds, styrene is preferable because it is easily available industrially.
[0015] The conjugated diene polymer block represented by B above has repeating units derived from a conjugated diene compound. Examples of the conjugated diene compound include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-octadiene, 1,3-hexadiene, 1,3-cyclohexadiene, 4,5-diethyl-1,3-octadiene, 3-butyl-1,3-octadiene, myrcene, chloroprene, etc. These conjugated diene compounds may be used alone or in combination of two or more. Among them, 1,3-butadiene and isoprene are preferred because of their high polymerization reactivity and easy availability industrially. In addition, examples of those available other than the above conjugated diene compounds include 2,5-dihydrofuran-2,5-dione.
[0016] The coupling agent that is a raw material for the component derived from the coupling agent represented by C above is a polyfunctional compound that radially bonds the above styrene-based block copolymer (A-B). Examples of the coupling agent include silane compounds such as halogenated silane and alkoxysilane, tin compounds such as tin halide, epoxy compounds such as polycarboxylic acid ester and epoxidized soybean oil, acrylic esters such as pentaerythritol tetraacrylate, and divinyl compounds such as epoxy silane and divinylbenzene. More specific examples include, for example, trichlorosilane, tribromosilane, tetrachlorosilane, tetrabromosilane, methyltrimethoxysilane, ethyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, tetramethoxysilane, tetraethoxysilane, tin tetrachloride, diethyl adipate, etc.
[0017] It is preferable that the content of the aromatic alkenyl polymer block represented by A above in the above radial styrene-based elastomer is 5% by weight or more and 50% by weight or less. When the content of the aromatic alkenyl polymer block represented by A in the radial-type styrene elastomer is within the above range, the storage modulus of the adhesive layer at high temperatures is increased, further improving the adhesive strength at high temperatures, while also ensuring adhesive strength at room temperature. From the viewpoint of balancing adhesive strength at high temperatures and adhesive strength at room temperature, a more preferable lower limit for the content of the aromatic alkenyl polymer block represented by A in the radial-type styrene elastomer is 7% by weight, and a more preferable upper limit is 25% by weight.
[0018] The above radial-type styrene elastomer preferably has a hydrogenation rate of 95% or higher, and more preferably 96% or higher, from the viewpoint of enhancing optical colorless transparency. The hydrogenation rate of the above radial-type styrene elastomer is usually 100% or less.
[0019] The weight-average molecular weight (Mw) of the above radial-type styrene elastomer is not particularly limited, but a preferred lower limit is 250,000, and a more preferred lower limit is 300,000. The upper limit of the above weight-average molecular weight (Mw) is not particularly limited, and the larger the value, the greater the adhesive strength of the adhesive layer, especially at high temperatures. However, since viscosity increases with increasing weight-average molecular weight (Mw), the practical limit for production is around 700,000.
[0020] The inclusion of the above-mentioned tackifying resin improves the adhesive strength of the adhesive layer. The above-mentioned tackifying resin contains at least one selected from the group consisting of a natural product-based tackifying resin (T1) containing an aromatic ring with an SP value of 8.0 to 9.0, and a petroleum resin-based or natural product-based tackifying resin (T2) that does not contain an aromatic ring and has an SP value of 7.5 to 8.5.
[0021] The natural product-based tackifying resin (T1) containing the aromatic ring has an SP value of 8.0 to 9.0, making it compatible with the aromatic alkenyl polymer block in the radial-type styrene elastomer. This allows for increased tackiness of the adhesive layer while suppressing a decrease in transparency. Furthermore, because the natural product-based tackifying resin (T1) containing the aromatic ring has an SP value of 8.0 to 9.0 and is relatively low polarity, the inclusion of this tackifying resin (T1) in the adhesive layer reduces its polarity. As a result, the adhesive sheet of the present invention can exhibit high tackiness to substrates made of difficult-to-bond materials such as cycloolefin polymers. Because it is more compatible with the aromatic alkenyl polymer block, the adhesive strength of the adhesive layer is increased, and transparency is less likely to decrease, the natural product-based tackifying resin (T1) containing the aromatic ring has a preferred lower limit of 8.5 for its SP value, a more preferred lower limit of 8.6, and a preferred upper limit of 8.9. Furthermore, if the SP value is 9.0 or less, even petroleum resin-based tackifying resins containing aromatic rings (for example, hydrogenated aromatic tackifying resins) may be compatible with the aromatic alkenyl polymer blocks in the radial styrene elastomer. However, petroleum resin-based tackifying resins containing aromatic rings generally have an SP value exceeding 9.0, and when the SP value exceeds 9.0, they are not compatible with the aromatic alkenyl polymer blocks, making it difficult to increase the tackiness of the adhesive layer while suppressing a decrease in transparency.
[0022] The above-mentioned petroleum resin-based or natural product-based tackifying resin (T2) that does not contain aromatic rings has an SP value of 7.5 to 8.5, which allows it to be compatible with the above-mentioned conjugated diene polymer block in the radial-type styrene elastomer, thereby increasing the tackiness of the adhesive layer while suppressing a decrease in transparency. Furthermore, since the above-mentioned petroleum resin-based or natural product-based tackifying resin (T2) that does not contain aromatic rings has an SP value of 7.5 to 8.5 and is relatively low polarity, the inclusion of the above-mentioned tackifying resin (T2) reduces the polarity of the adhesive layer. As a result, the adhesive sheet of the present invention can exhibit high tackiness to substrates made of difficult-to-bond materials such as cycloolefin polymers. Because it is more compatible with the above-mentioned conjugated diene polymer block, the adhesive strength of the adhesive layer is increased, and transparency is less likely to decrease, the petroleum resin-based or natural product-based tackifying resin (T2) that does not contain aromatic rings has a preferred upper limit of SP value of 8.4.
[0023] In this specification, the SP value is referred to as the Solubility Parameter, and it is an index that can represent the ease of dissolution. In this specification, the Fedors method (RFFedors, Polym. Eng. Sci., 14(2), 147-154 (1974)) is used to calculate the SP value.
[0024] The natural product-based tackifying resin (T1) containing the above-mentioned aromatic ring, and the petroleum resin-based or natural product-based tackifying resin (T2) not containing the above-mentioned aromatic ring, preferably have a softening point of 80°C or higher. This enhances the adhesive strength of the adhesive layer at high temperatures. Since the adhesive strength at higher temperatures is improved, the softening point is preferably 90°C or higher, and more preferably 100°C or higher. The upper limit of the softening point is not particularly limited, but considering the operating temperature, 140°C is preferred. The above softening point can be measured using a method in accordance with JIS K2207.
[0025] Examples of natural product-based tackifying resins (T1) containing the above-mentioned aromatic rings include aromatically modified terpenes, aromatically modified hydrogenated terpenes, terpene phenols, hydrogenated terpene phenols, and rosin esters (e.g., ultra-pale rosin esters). Among these, aromatically modified terpenes, aromatically modified hydrogenated terpenes, and ultra-pale rosin esters are preferred because they are more compatible with the aromatic alkenyl polymer block, increasing the tackiness of the adhesive layer and preventing a decrease in transparency.
[0026] Examples of petroleum resin-based or natural product-based tackifying resins (T2) that do not contain the above aromatic ring include C5 petroleum resins, alicyclic petroleum resins, terpenes, hydrogenated terpenes, and hydrogenated α-methylstyrene resins. Among these, alicyclic petroleum resins, terpenes, hydrogenated terpenes, and hydrogenated α-methylstyrene resins are preferred because they are more compatible with the above conjugated diene polymer block, resulting in higher tackiness of the adhesive layer and less reduction in transparency.
[0027] The content of the natural product-based tackifying resin (T1) containing the above aromatic ring is not particularly limited, but a preferred lower limit is 5 parts by weight, a more preferred lower limit is 10 parts by weight, a preferred upper limit is 100 parts by weight, and a more preferred upper limit is 80 parts by weight relative to 100 parts by weight of the radial-type styrene elastomer. By having the content of the above tackifying resin (T1) within the above range, an adhesive layer with superior transparency and tackiness can be obtained.
[0028] The content of the petroleum resin-based or natural product-based tackifying resin (T2) that does not contain the above aromatic ring is not particularly limited, but a preferred lower limit is 5 parts by weight, a more preferred lower limit is 10 parts by weight, a preferred upper limit is 100 parts by weight, and a more preferred upper limit is 80 parts by weight relative to 100 parts by weight of the radial-type styrene elastomer. By having the content of the above tackifying resin (T2) within the above range, an adhesive layer with superior transparency and tackiness can be obtained.
[0029] The content of the tackifying resin (total content of the tackifying resin) is not particularly limited, as the radial-type styrene elastomer can improve the adhesive strength of the adhesive layer at high temperatures while also ensuring adhesive strength at room temperature. Therefore, sufficient adhesive strength can be obtained even with a relatively small amount of the tackifying resin. The preferred lower limit of the content of the tackifying resin (total content of the tackifying resin) is 5 parts by weight, a more preferred lower limit is 10 parts by weight, a preferred upper limit is 100 parts by weight, and a more preferred upper limit is 80 parts by weight, per 100 parts by weight of the radial-type styrene elastomer. By having the content of the tackifying resin (total content of the tackifying resin) within the above range, an adhesive layer with superior transparency and adhesive strength can be obtained.
[0030] The above adhesive layer may further contain a liquid softener with an SP value of 8.5 or less at 23°C. By incorporating the above-mentioned softening agent, the adhesive strength of the adhesive layer at room temperature can be improved. Furthermore, since the dielectric properties in the high-frequency range are also affected by the moisture content of the material, incorporating the above-mentioned softening agent can reduce the moisture content of the adhesive layer after exposure to a humid environment, thereby stabilizing the dielectric properties in the high-frequency range even when used in environments with fluctuating humidity, such as outdoors. In addition, since the above-mentioned softening agent is compatible with the conjugated diene polymer block in the radial-type styrene elastomer, it can suppress the decrease in transparency of the adhesive layer. It is more preferable that the SP value of the softener be 8.3 or less, as this improves compatibility with the conjugated diene polymer block and prevents a decrease in the transparency of the adhesive layer. The lower limit of the SP value of the softener is not particularly limited, but it is preferable to be 7.0 or higher from the viewpoint of compatibility.
[0031] Examples of the softening agents mentioned above include polybutene, n-butene-isobutylene copolymer, polyisoprene, and paraffinic oils. Among these, polybutene is preferred because it is well compatible with the radial-type styrene elastomer and can further suppress the decrease in transparency of the adhesive layer.
[0032] The above-mentioned softening agent, if it has the above-mentioned SP value, is less likely to reduce the transparency of the adhesive layer. However, if used in large quantities, it may reduce the adhesive strength at high temperatures. Therefore, if high-temperature adhesive strength is more important than adhesive strength and moisture content at room temperature, it is preferable to use as little as possible. The content of the above-mentioned softening agent is not particularly limited, but it is preferably 50 parts by weight or less, more preferably 30 parts by weight or less, and may even be 0 parts by weight, per 100 parts by weight of the radial-type styrene elastomer. By having the content of the above-mentioned softening agent within this range, it is possible to improve the tackiness and water content at room temperature while minimizing the decrease in tackiness at high temperatures, resulting in an adhesive layer with an excellent balance of performance. If the content of the above-mentioned softening agent exceeds 50 parts by weight, the effect of the decrease in tackiness at high temperatures becomes greater.
[0033] Preferably, the adhesive layer has a moisture content of 1% by weight or less after being exposed to an environment of 85°C and 85% RH for 72 hours. Since dielectric properties in the high-frequency range are also affected by the moisture content of the material, having the moisture content of the adhesive layer within the above range allows for stable dielectric properties in the high-frequency range even when used in environments with humidity fluctuations, such as outdoors. More preferably, the moisture content of the adhesive layer is 0.5% by weight or less. The lower limit of the moisture content of the adhesive layer is not particularly limited, but the smaller the moisture content, the more stable the dielectric properties in the high-frequency range can be. The moisture content of the adhesive layer after exposure to an environment of 85°C and 85%RH for 72 hours can be calculated using the following formula (1), where α (g) is the weight of the adhesive layer with the release PET film at room temperature, γ (g) is the moisture content of the adhesive layer after exposure to an environment of 85°C and 85%RH for 72 hours, and β (g) is the weight of the peeled release PET film after returning it to room temperature. The moisture content of the adhesive layer can be measured using the Karl Fischer method. Moisture content (%)={γ / (α-β)}×100 (1)
[0034] Preferably, the adhesive layer has an α value of 0.005 or less in the 10 GHz band. If the α value of the adhesive layer in the 10 GHz band is within the above range, the adhesive layer can be said to have excellent dielectric properties in the high frequency band, and the adhesive sheet can be suitably used even when the transmission signal is at a high frequency. The α value of the adhesive layer in the 10 GHz band can be calculated from the dielectric constant ε and dielectric loss tangent tanδ of the adhesive layer in the 10 GHz band using the following formula (2). The dielectric constant and dielectric loss tangent of the adhesive layer in the 10 GHz band can be measured in accordance with JIS C2565, for example, using a dielectric constant measuring device (e.g., ADMS01Nc, manufactured by AET Corporation) in the measurement mode of a TM mode resonator. α = (√ε) × tanδ (2)
[0035] The adhesive layer described above preferably has an adhesive strength of 10 N / 25 mm or more to a cycloolefin polymer substrate at 23°C. By having an adhesive strength of the adhesive layer to a cycloolefin polymer substrate at 23°C within this range, the adhesive layer can exhibit high adhesive strength to substrates made of materials that are difficult to adhere to. More preferably, the adhesive strength of the adhesive layer to a cycloolefin polymer substrate at 23°C is 12 N / 25 mm or more. The adhesive strength of the adhesive layer to the cycloolefin polymer substrate at 23°C can be measured by performing a 180° peel test at a tensile speed of 300 mm / min, in accordance with JIS Z 0237:2009.
[0036] In gel permeation chromatography (GPC) measurements, the adhesive layer preferably exhibits a first peak with a weight-average molecular weight of 250,000 or more, and a second peak with a weight-average molecular weight smaller than the first peak. The ratio of the weight-average molecular weights of the first peak to the second peak (weight-average molecular weight of the first peak / weight-average molecular weight of the second peak) is preferably 3.5 or higher. The first peak shown above represents the weight-average molecular weight of the radial styrene elastomer. If the weight-average molecular weight of the first peak, i.e., the weight-average molecular weight of the radial styrene elastomer, is 250,000 or more, the adhesive strength of the adhesive layer, especially at high temperatures, can be increased. Furthermore, since the radial styrene elastomer has the property of suppressing viscosity increase even if the molecular weight of the hard segment is increased to improve the adhesive strength of the adhesive layer at high temperatures, the adhesive strength at room temperature can also be ensured even if the adhesive strength of the adhesive layer at high temperatures is improved. It is more preferable that the weight-average molecular weight of the first peak is 300,000 or more.
[0037] Furthermore, the second peak represents the weight-average molecular weight of the diblock styrene-based block copolymer (AB). If the first peak and the second peak are observed, and the ratio of their weight-average molecular weights, i.e., the ratio of the weight-average molecular weight of the radial-type styrene-based elastomer to the weight-average molecular weight of the styrene-based block copolymer (AB), is 3.5 or higher, then the adhesive strength of the adhesive layer can be improved at high temperatures while maintaining its adhesive strength at room temperature. In other words, since the adhesive layer can simultaneously contain a radial-type styrene-based elastomer with a large molecular weight and a low-molecular-weight styrene-based block copolymer (AB) with good wettability, it is possible to improve the adhesive strength at high temperatures while maintaining its adhesive strength at room temperature. It is more preferable that the ratio of the weight-average molecular weights of the first peak and the second peak is 3.6 or higher.
[0038] Furthermore, GPC measurement of the adhesive layer can be performed, for example, by the following method. A solution of a portion of the adhesive layer dissolved in tetrahydrofuran (THF) is filtered through a filter (material: polytetrafluoroethylene, pore diameter: 0.2 μm) to obtain a GPC sample solution. The GPC system used is the "ACQUITY" manufactured by Waters. TM Advanced Polymer Chromatography TM The "System" uses Waters' "HSPgel" as the GPC column. TMGPC measurements will be performed using an HR MB-M (6.0 mm × 150 mm) column with a differential refractive index detector. The sample injection volume will be 10 μL of a 20 mg / mL solution, the flow rate will be 0.5 mL / min, and the column temperature will be 40°C. The analysis software will be Empower3, which is included with the instrument. Polystyrene (peak top molecular weight: 2,110,000, 1,090,000, 427,000, 1,900,000, 37,900, 18,100, 5,970, 2,420, 500) (manufactured by Tosoh Corporation) will be used as the standard sample. The polystyrene will be measured, and a calibration curve will be created using the analysis software to convert the eluted amount to the polystyrene molecular weight. This calibration curve will then be used to convert the weight-average molecular weight (Mw) from the GPC elution volume.
[0039] Furthermore, the weight-average molecular weight of the first peak and the weight-average molecular weight of the second peak can be calculated as follows. For peaks with an elution time between 3.0 and 4.7 minutes, the first peak is defined as the range from the initial detection time of the fastest elution peak to the inflection point after the peak peak. The first peak occupies more than 50% of the total area. The weight-average molecular weight (Mw) of the first peak is the weight-average molecular weight (Mw) of the peaks obtained by longitudinally splitting at this inflection point. On the other hand, for peaks with an elution time between 4.1 and 5.5 minutes, the second peak is defined as the range from the inflection point of the first peak to the next inflection point. The second peak occupies more than 10% of the total area. The weight-average molecular weight (Mw) of the second peak is the weight-average molecular weight (Mw) of the peaks obtained by longitudinally splitting at this inflection point.
[0040] The gel fraction of the adhesive layer described above is not particularly limited, but a preferred lower limit is 30% by weight. If the gel fraction of the adhesive layer is 30% by weight or more, the storage modulus of the adhesive layer at high temperatures increases, which can further improve the adhesive strength at high temperatures, while also ensuring adhesive strength at room temperature. A more preferred lower limit for the gel fraction of the adhesive layer is 45% by weight, and an even more preferred lower limit is 50% by weight. The upper limit for the gel fraction of the adhesive layer is not particularly limited, but since excessively high gel fractions reduce adhesive strength, a preferred upper limit is 70% by weight. The gel fraction of the adhesive layer can be measured, for example, as follows. The release film is peeled off the adhesive sheet, and a 50mm x 25mm rectangular flat specimen is cut to prepare a test specimen. The weight W1 of the test specimen is measured. The test specimen is immersed in ethyl acetate at 23°C for 24 hours, then removed from the ethyl acetate using a 200-mesh stainless steel mesh and dried at 110°C for 1 hour. The weight W2 of the dried test specimen is measured, and the gel fraction is calculated using the following formula (3). Gel fraction (weight %) = 100 × (W2 - W0) / (W1 - W0) (3) (W0: Weight of the substrate, W1: Weight of the test specimen before ethyl acetate immersion, W2: Weight of the test specimen after ethyl acetate immersion and drying)
[0041] The method for adjusting the gel fraction of the adhesive layer to the above range is not particularly limited and includes, for example, a method for crosslinking the radial styrene elastomer, the tackifying resin, etc., and a method for adjusting the type and amount of the radial styrene elastomer, the tackifying resin, etc. involved in crosslinking. Other methods include adjusting the type and amount of the crosslinking initiator that causes the crosslinking reaction, the crosslinking aid that promotes crosslinking, a method for adjusting the irradiation intensity and irradiation time of UV light, which is an energy source that promotes crosslinking, a method for adjusting the irradiation intensity, irradiation time and acceleration voltage of electron beam irradiation, and a method for adjusting the type and amount of the crosslinking inhibitor. The crosslinking method described above is not particularly limited. Examples include a method of chemically crosslinking the radial styrene elastomer or tackifying resin by introducing functional groups into it beforehand, or a method of crosslinking the radial styrene elastomer or tackifying resin by irradiating it with UV light. Other examples include a method of crosslinking the radial styrene elastomer or tackifying resin by electron beam irradiation, or a method of grafting crosslinkable functional groups onto the radial styrene elastomer or tackifying resin by electron beam irradiation and then crosslinking them with heat. In particular, the chemical crosslinking method requires the introduction of functional groups, and since these functional groups tend to increase the dielectric loss tangent of the adhesive layer, the method of crosslinking by UV light irradiation and the method of crosslinking by electron beam irradiation are preferred, and the method of crosslinking by electron beam irradiation is more preferred. The electron beam irradiation intensity in the above-described method of crosslinking by electron beam irradiation is not particularly limited, but is preferably 80 kGy or more, and more preferably 200 kGy or more and 350 kGy or less.
[0042] The thickness of the adhesive layer described above is not particularly limited, but a preferred lower limit is 1 μm and a preferred upper limit is 300 μm. When the thickness of the adhesive layer is within this range, sufficient adhesive strength and ease of handling can be achieved. A more preferred lower limit for the thickness of the adhesive layer is 2.5 μm and a more preferred upper limit is 200 μm.
[0043] The adhesive sheet of the present invention may be a support type with a base material, or a non-support type without a base material, as long as it has the above-mentioned adhesive layer. Among these, the non-support type is preferred from the viewpoint of cost and thinness.
[0044] The adhesive sheet of the present invention preferably has a haze of 5.0% or less. A haze of 5.0% or less allows the adhesive sheet to be used for fixing optical devices such as liquid crystal displays. A haze of 1.0% or less is more preferable.
[0045] The method for manufacturing the adhesive sheet of the present invention is not particularly limited, and conventionally known methods can be used. For example, the adhesive sheet can be manufactured by coating a film that has been treated with a release agent with an adhesive solution containing the radial styrene-based elastomer, the tackifying resin, and other additives such as a softener as needed, drying it to form an adhesive layer, and then layering a film that has been treated with a release agent onto the adhesive layer.
[0046] The applications of the adhesive sheet of the present invention are not particularly limited, as long as it is used for bonding components in a laminate including a film on which a conductive pattern is formed, bonding components inside a substrate, or bonding a film or substrate on which a conductive pattern is formed to other components. The film or substrate on which the conductive pattern is formed is not particularly limited, and as described above, any film or substrate on which a conductive pattern is formed that is used in electronic devices may be used. The electronic devices are not particularly limited, and examples include portable electronic devices, in-vehicle electronic devices, base station antennas, base station transceivers and receivers, smart glasses, and the like. [Effects of the Invention]
[0047] According to the present invention, it is possible to provide an adhesive sheet for films or substrates that can be suitably used even when the transmission signal is high frequency and has a conductive pattern formed on it that can exhibit high adhesive strength to substrates made of difficult-to-adhere materials such as cycloolefin polymers. [Modes for carrying out the invention]
[0048] The embodiments of the present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.
[0049] <Base resin> In the examples and comparative examples, radial styrene elastomers, non-radial styrene elastomers, and acrylic polymers synthesized by the following methods, as well as commercially available base resins, were used.
[0050] (Synthesis of radial styrene-based elastomer (Mw 300,000)) 4000 g of degassed and dehydrated cyclohexane, 200 g of 1,3-butadiene monomer, 3.0 g of n-butyllithium (n-BuLi), and tetrahydrofuran (THF) were added in an autoclave in a molar ratio of n-BuLi / THF = 40. Polymerization was then carried out at the polymerization initiation temperature of 40°C for 40 minutes, and 100 g of styrene monomer was added and polymerization was carried out for 60 minutes (aromatic alkenyl polymer block (A)). Next, 700 g of 1,3-butadiene monomer was added and polymerization was carried out for 150 minutes (diblock styrene-based block copolymer (AB)). Tetrachlorosilane (SiCl4) was added as a coupling agent in an amount of 0.25 molar relative to the polymer ends to perform a coupling reaction of the diblock styrene-based block copolymer (AB), obtaining a styrene-based block copolymer with a bound styrene content of 10%. This copolymer was diluted with purified and dried cyclohexane to adjust the polymer concentration to 5% by weight, and then subjected to the hydrogenation reaction.
[0051] In the hydrogenation reaction, first, 1000 g of the copolymer solution was placed in a thoroughly dried 2 L autoclave equipped with a stirrer, degassed under reduced pressure, and then hydrogenated, and maintained at 90°C under stirring. Next, 50 ml of cyclohexane solution containing 0.2 mmol of di-p-trilbis(η-cyclopentadienyl)titanium and 10 ml of cyclohexane solution containing 0.108 mmol of n-butyllithium (n-BuLi) were mixed at 0°C and 2.0 kg / cm³. 2 The mixture was mixed under hydrogen pressure and added to the copolymer solution in an autoclave. The hydrogenation reaction was started with a hydrogen gas supply pressure of 0.7 MPa-Gauge and a reaction temperature of 80°C under stirring. Once hydrogen absorption was complete, the reaction solution was returned to room temperature and atmospheric pressure and withdrawn from the reaction vessel to obtain radial styrene-based elastomer (AB) 4C. The resulting radial styrene-based elastomer (AB)4C is 1 ¹H-NMR analysis revealed that more than 95% of the butadiene units and less than 5% of the styrene units were hydrogenated.
[0052] A solution of the obtained radial styrene-based elastomer (A-B)4C dissolved in tetrahydrofuran (THF) was filtered through a filter (material: polytetrafluoroethylene, pore size: 0.2 μm) to obtain a GPC test solution. As the GPC system, "ACQUITY TM Advanced Polymer Chromatography TM System" manufactured by Waters was used, and as the GPC column, "HSPgel TM HR MB-M (6.0 mm × 150 mm)" manufactured by Waters was used. GPC measurement was performed using a differential refractive index detector as the detector. The sample injection volume was 10 μL of a 20 mg / mL solution, the flow rate was 0.5 mL / min, and the column temperature was 40°C. Empower3 attached to the apparatus was used as the analysis software. Polystyrene (peak top molecular weights: 2110000, 1090000, 427000, 190000, 37900, 18100, 5970, 2420, 500) (manufactured by Tosoh Corporation) was used as the standard. Polystyrene was measured as the standard, and a calibration curve for converting the elution volume to the polystyrene molecular weight was created and analyzed using the analysis software. The weight average molecular weight (Mw) was converted from the GPC elution volume using this calibration curve.
[0053] (Synthesis of radial styrene-based elastomer (Mw 500,000)) A radial styrene-based elastomer (Mw 500,000) was obtained in the same manner as the synthesis of the radial styrene-based elastomer (Mw 300,000), except that the amount of n-butyllithium (n-BuLi) was changed so that the weight average molecular weight (Mw) was 500,000.
[0054] (Synthesis of non-radial styrene-based elastomer (Mw 500,000)) We attempted to obtain a non-radial styrene-based elastomer (Mw 500,000) in the same manner as the synthesis of a radial styrene-based elastomer (Mw 500,000), except that we used methyldichlorosilane as a coupling agent and changed the proportions of styrene, 1,3-butadiene, and the coupling agent. However, when we tried to adjust the weight-average molecular weight (Mw) to 500,000 or more, gelation occurred as polymerization progressed, and we were unable to obtain a non-radial styrene-based elastomer (Mw 500,000) or an adhesive sheet.
[0055] (Synthesis of acrylic polymers) In a reactor equipped with a thermometer, stirrer, condenser, and ultraviolet irradiation device, 39.9 parts by weight of 2-ethylhexyl acrylate, 30 parts by weight of cyclohexyl acrylate, 22 parts by weight of 4-hydroxybutyl acrylate, 8 parts by weight of dimethylacrylamide, and 0.1 parts by weight of dimethylaminopropylacrylamide were added as monomers. To this monomer mixture, 0.05 parts by weight of 2,2-dimethoxy-1,2-diphenylethane-1-one was added as a photopolymerization initiator, and the mixture was purged with nitrogen gas. Then, ultraviolet light was irradiated into the reactor until the viscosity (BH viscometer No. 5 rotor, 10 rpm, measurement temperature 25°C) was approximately 4 Pa·s, to obtain an acrylic polymer precursor in which a portion of the monomer mixture had polymerized. To the obtained acrylic polymer precursor, 2 parts by weight of 3-glycidoxypropyltrimethoxysilane and 0.05 parts by weight of 1,6-hexanediol diacrylate as crosslinking agents, and 0.15 parts by weight of 2,2-dimethoxy-1,2-diphenylethane-1-one as a photopolymerization initiator were added and stirred to obtain an acrylic polymer. For 3-glycidoxypropyltrimethoxysilane, KBM-403 from Shin-Etsu Chemical Co., Ltd. was used; for 1,6-hexanediol diacrylate, A-HD-N from Shin-Nakamura Chemical Co., Ltd. was used; and for 2,2-dimethoxy-1,2-diphenylethane-1-one, Omnirad651 from IGM Resins BV was used.
[0056] (Commercially available base resin) • SEPS (Mw 150,000) (Septon 2063, SEPS block copolymer, manufactured by Kuraray Co., Ltd.) • Polyisobutylene (OPPANOL N80, manufactured by BASF)
[0057] <Softener> The following softening agents were used in the examples and comparative examples. • Nippon Oil Polybutene HV-300 (referred to as HV-300 in the table): n-butene-isobutylene copolymer, SP value 7.0~8.5, pour point -55℃, manufactured by JXTG Energy Corporation. • Nippon Oil Polybutene LV-100 (LV-100 in the table): n-butene-isobutylene copolymer, SP value 7.0~8.5, pour point -12.5℃, manufactured by JXTG Energy Corporation.
[0058] <Adhesive-granting resin> The following tackifying resins were used in the examples and comparative examples. (Tackifying resin (T1)) • YS Resin TO105 (referred to as TO105 in the table): Aromatic modified terpene resin, SP value 8.5-9.0, softening point 105°C, manufactured by Yasuhara Chemical Co., Ltd. • Rosin ester KE311 (KE311 in the table): Ultra-pale rosin ester resin, SP value 8.5-9.0, softening point 100°C, manufactured by Arakawa Chemical Co., Ltd. (Tackifying resin (T2)) • YS Resin PX100 (PX100 in the table): Terpene resin, SP value 8.0-8.5, softening point 100℃, manufactured by Yasuhara Chemical Co., Ltd. Alcon P125: Hydrogenated petroleum resin (aliphatic hydrocarbon resin), SP value 8.0-8.5, softening point 100℃, manufactured by Arakawa Chemical Co., Ltd. • Regalrez 1126: Hydrogenated α-methylstyrene resin, SP value 8.2, softening point 126°C, manufactured by Eastman Chemical Company. Plastolyn R1140: Aliphatic hydrocarbon resin, SP value 8.1, softening point 140°C, manufactured by Eastman Chemical Company. (others) FTR6100: Styrene copolymer, SP value 8.7-9.2, softening point 110°C, manufactured by Mitsui Chemicals, Inc. • FMR0150: Styrene copolymer, SP value 8.7-9.2, softening point 145°C, manufactured by Mitsui Chemicals, Inc.
[0059] (Example 1) An adhesive solution was obtained by adding 100 parts by weight of the obtained radial-type styrene elastomer and 30 parts by weight of PX100, a tackifying resin (T2), to 350 parts by weight of toluene. The obtained adhesive solution was coated onto the release-treated surface of a polyethylene terephthalate (PET) film with a thickness of 50 μm to a thickness of 25 μm after drying, and then dried at 100°C for 10 minutes to form an adhesive layer. Subsequently, an adhesive sheet was obtained by laminating a similar PET film onto the side of the adhesive layer that was not laminated with a PET film, with the release-treated side facing the adhesive layer. The gel fraction of the adhesive layer in the obtained adhesive sheet was determined by the method calculated using equation (3) described above.
[0060] (Examples 2-22, Comparative Examples 1-9) An adhesive sheet was obtained in the same manner as in Example 1, except that the composition of the adhesive layer was changed as shown in Tables 1-4. In Examples 9 and 17-22, after forming the adhesive layer, the adhesive layer was irradiated with an electron beam using an electron beam irradiation device EBC-200 (manufactured by NHV Corporation) to crosslink the adhesive layer. In Comparative Example 6, as described above, it was not possible to obtain a non-radial styrene-based elastomer (Mw 500,000) and an adhesive sheet.
[0061] <Rating> The adhesive sheets obtained in the examples and comparative examples were evaluated as follows. The results are shown in Tables 1-3.
[0062] (1) Measurement of moisture content The adhesive sheet was left to stand at 23°C and 50% RH for 72 hours (3 days) or more, then cut into 1.3 cm x 4 cm pieces. One release PET film (referred to as release PET film 1) was peeled off and its weight α (g) was measured. A 25 μm thick aluminum foil was bonded to the adhesive surface from which release PET film 1 had been peeled off, and it was left to stand at 85°C and 85% RH for 72 hours (3 days). The other release PET film (referred to as release PET film 2) was peeled off, and the amount of moisture γ (g) generated when heated at 120°C for 10 minutes using a Karl Fischer method moisture analyzer (Hiranuma trace moisture analyzer, AQ-2000) and a moisture vaporizer (Hiranuma moisture vaporizer, EV-2000) was measured. Furthermore, the peeled release PET film 2 was left to stand again at 23°C and 50% RH for 72 hours (3 days) or more and its weight β (g) was measured. The moisture content was calculated using the following formula (1). Moisture content (%)={γ / (α-β)}×100 (1)
[0063] (2) Measurement of dielectric properties (dielectric constant, dielectric loss tangent, and alpha value) in the 10 GHz band The adhesive sheets were left to stand at 23°C and 50% RH for 72 hours (3 days) or more, and then multiple sheets were laminated until a thickness of 100 μm was achieved. After lamination, the release PET film was peeled off the adhesive sheets, and 50 μm thick PET films were bonded to the top and bottom surfaces. The resulting laminate of PET film and adhesive sheets was cut to a width of 3 mm and a length of 80 mm, and the dielectric properties were measured in accordance with JIS C2565 using a dielectric constant measuring device (ADMS01Nc, manufactured by AET Co., Ltd.) in the TM mode resonator measurement mode. The dielectric properties of the PET film alone were also measured using the method described above. The dielectric properties of the adhesive sheet alone were determined using the measured values of the dielectric properties of the laminate of the PET film and adhesive sheet, and the dielectric properties of the PET film alone. The obtained α value was defined as the α-1 value.
[0064] (3) Measurement of the rate of change in dielectric properties The laminate of the PET film and adhesive sheet obtained in the same manner as in (2) above was exposed to an environment of 85°C and 85%RH for 72 hours (3 days), and the dielectric properties of the adhesive sheet alone were determined in the same manner as in (2) above. The obtained α value was taken as the α-2 value. The value of (α-2) / (α-1) was calculated from the α-1 and α-2 values. A value of (α-2) / (α-1) of 1.2 or greater was marked with ×, and a value less than 1.2 was marked with ○.
[0065] (4) Measurement of adhesion strength at 23°C and 85°C (compared to PI and COP) Test specimens were prepared by cutting adhesive sheets to a width of 25 mm. Next, the obtained test specimens were attached to a polyimide (PI) substrate or a cycloolefin polymer (COP) substrate and pressed down by one pass of a 2 kg rubber roller to prepare measurement samples. Subsequently, the obtained measurement samples were subjected to a 180° peel test at a tensile speed of 300 mm / min in accordance with JIS Z 0237:2009, and the adhesive strength at 23°C was measured. If adhesive residue was present, it was marked as × because in actual use the bonded components may shift or peel off. Among cases where the components peeled off at the interface without adhesive residue, adhesive strength of less than 8N / 25mm was marked as ×, 8N / 25mm or more but less than 10N / 25mm was marked as △, 10N / 25mm or more but less than 13N / 25mm was marked as ○, and 13N / 25mm or more was marked as ◎. Next, for the case using a cycloolefin polymer (COP) substrate, measurement samples were prepared in the same manner and subjected to heat treatment at 85°C for 10 minutes. Immediately after heat treatment, the measurement samples were subjected to a 180° peel test in the same manner as for the adhesive strength at 23°C, and the adhesive strength at 85°C was measured. If adhesive residue was present, it was marked as × because in actual use the bonded components may shift or peel off. Among cases where the components peeled off at the interface without adhesive residue, adhesive strength of less than 1N / 25mm was marked as ×, 1N / 25mm or more but less than 3N / 25mm was marked as △, 3N / 25mm or more but less than 4N / 25mm was marked as ○, and 4N / 25mm or more was marked as ◎.
[0066] (5) Evaluation of adhesion to the substrate A substrate (Hitachi Chemical Co., Ltd., MCL-E-679FG type, copper foil thickness 12 μm / substrate thickness 0.6 mm, substrate material: cycloolefin polymer (COP)) was prepared. This substrate was subjected to an ultra-roughening adhesion improvement treatment (CZ roughening treatment process) (pre-treatment: MEC Bright CA-5330A, copper surface roughening: MEC Etchbond CZ8201) to achieve an etching amount of 0.5 μm. The adhesive sheet was pressed and bonded to the processed substrate by using a 2kg rubber roller to press it back and forth once. A score of ○ indicated that the adhesive sheet adhered firmly without peeling from the edges, while a score of × indicated that the adhesive sheet did not adhere sufficiently.
[0067] (6) Transparency assessment Haze and b* were measured for the adhesive sheets using a haze meter (HM-150, manufactured by Murakami Color Technology Research Institute). After exposing the adhesive sheets to an environment of 80°C and 85%RH for 196 hours, haze and b* were measured in the same manner. For the measurements after exposure to an environment of 80°C and 85%RH for 196 hours, ◎ was used to indicate haze of 0.5 or less and b* of 0.3 or less, ○ to indicate haze of 0.5 to 1 and b* of 0.3 or less, △ to indicate haze of 0.5 to 1 and b* of 0.3 to 0.5, and × to indicate haze of 1 or more or b* of 0.5 or more.
[0068] [Table 1]
[0069] [Table 2]
[0070] [Table 3]
[0071] [Table 4] [Industrial applicability]
[0072] According to the present invention, it is possible to provide an adhesive sheet for films or substrates that can be suitably used even when the transmission signal is high frequency and has a conductive pattern formed on it that can exhibit high adhesive strength to substrates made of difficult-to-adhere materials such as cycloolefin polymers.
Claims
1. An adhesive sheet used for bonding components in a laminate including a film on which a conductive pattern is formed, bonding components inside a substrate, or bonding a film or substrate on which a conductive pattern is formed to other components, The adhesive layer contains a radial styrene-based elastomer having a structure represented by the general formula (A-B)nC, and a tackifying resin. The tackifying resin contains at least one selected from the group consisting of a natural product-based tackifying resin (T1) containing an aromatic ring with an SP value of 8.0 to 9.0, and a petroleum resin-based or natural product-based tackifying resin (T2) not containing an aromatic ring with an SP value of 7.5 to 8.
5. The adhesive layer has a gel fraction of 30% by weight or more, a water content of 1% by weight or less after exposure to an environment of 85°C and 85% RH for 72 hours, and an α value of 0.005 or less in the 10 GHz band. An adhesive sheet for films or substrates characterized by having a conductive pattern formed on it. A: Aromatic alkenyl polymer block B: Conjugated diene polymer block C: Components derived from coupling agents n: an integer greater than or equal to 3
2. The adhesive layer is characterized in that it has an adhesive strength of 10 N / 25 mm or more to a cycloolefin polymer substrate at 23°C, and is used to form a conductive pattern on an adhesive sheet for films or substrates according to claim 1.
3. The adhesive layer is characterized in that, in gel permeation chromatography (GPC) measurement, a first peak with a weight-average molecular weight of 250,000 or more and a second peak with a weight-average molecular weight smaller than the first peak are observed, and the ratio of the weight-average molecular weights of the first peak to the second peak (weight-average molecular weight of the first peak / weight-average molecular weight of the second peak) is 3.5 or more, and the conductive pattern is formed on the adhesive sheet for film or substrate according to claim 1 or 2.
4. The adhesive sheet for films or substrates having a conductive pattern formed on it, characterized in that the content of the tackifying resin is 5 parts by weight or more and 80 parts by weight or less per 100 parts by weight of the radial styrene elastomer.
5. The adhesive layer further contains a liquid softener with an SP value of 8.5 or less at 23°C, and the content of the softener is 50 parts by weight or less per 100 parts by weight of the radial styrene elastomer, characterized in that an adhesive sheet for film or substrate having a conductive pattern formed on it according to 1, 2, 3, or 4.
6. The radial styrene-based elastomer is characterized in that it has a weight-average molecular weight (Mw) of 300,000 or more, and is used to form a conductive pattern on an adhesive sheet for films or substrates according to claim 1, 2, 3, 4, or 5.