Uncured sheet and cured body of same

Abstract

The purpose of the present disclosure is to reduce the tackiness of an uncured sheet. This uncured sheet: comprises a composition that includes an olefin / aromatic vinyl compound / aromatic polyene copolymer that satisfies the conditions in (2a); and has a tack force of no more than 2 N at 25°C as measured by probe tack testing. (2a) The aromatic vinyl compound monomer unit content is 60–80 mass%, and the total of the aromatic vinyl compound monomer units, the aromatic polyene monomer units, and the olefin monomer units is 100 mass%.

Description

Uncured sheet and its cured body

[0001] The present invention relates to uncured sheets and insulating materials obtained by curing the sheets.

[0002] As communication frequencies shift to the gigahertz band and higher, there is an increasing need for multilayer substrates, transmission lines, antennas, etc., made of CCLs or FCCLs containing insulating materials with low dielectric properties. Fluorine-based resins such as perfluoroethylene are characterized by their excellent low dielectric constant, low dielectric loss, and excellent heat resistance, but they are difficult to mold and form into films, and also have issues with adhesion to copper foil in wiring, making them difficult to apply to multilayer substrates, etc. Meanwhile, substrates and insulating materials made from post-curing resins such as epoxy resins, unsaturated polyester resins, polyimide resins, and phenolic resins have been widely used due to their heat resistance and ease of handling, but their relatively high dielectric constants and dielectric loss mean that improvements are needed as insulating materials for high frequencies (Patent Document 1).

[0003] Therefore, hydrocarbon-based resins, which inherently possess low dielectric properties, have attracted attention. To convert hydrocarbon-based resins, which are essentially thermoplastic resins, into curable resins requires the introduction of functional groups. However, functional groups that undergo radical or thermal crosslinking reactions generally have polarity, and introducing these functional groups into hydrocarbon-based resins results in poor dielectric properties. Attempts to introduce functional groups composed solely of hydrocarbons, such as aromatic vinyl groups, often require the use of expensive intermolecular reactions between hydrocarbon monomers (Patent Document 2), which is often uneconomical. Patent Document 3 discloses a cured product obtained from a specific coordination polymerization catalyst and consisting of an ethylene-olefin (aromatic vinyl compound)-aromatic polyene copolymer and a nonpolar vinyl compound copolymer with a specific composition and blend. This technology selectively copolymerizes only one of the two vinyl groups of the aromatic polyene (divinylbenzene), preserving the remaining vinyl group, thereby easily producing a crosslinkable hydrocarbon-based copolymer macromonomer with aromatic vinyl functional groups. Cured products obtained from similar olefin-aromatic vinyl compound-aromatic polyene copolymers and compositions with auxiliary materials, etc., are characterized by low dielectric constants and low dielectric dissipation factors (Patent Documents 4, 5, and 6).

[0004] Japanese Patent Application Laid-Open No. 06-192392 Japanese Patent Application Laid-Open No. 2004-087639 Japanese Patent Application Laid-Open No. 2007-217706 International Publication No. 2021 / 112087 International Publication No. 2021 / 112088 International Publication No. 2022 / 014599

[0005] Here, when low-dielectric resin materials for high-frequency insulation according to the prior art are provided as sheets such as bonding sheets or interlayer insulating sheets, it is sometimes desirable to distribute them in an uncured state before they are completely cured. In this case, even when the uncured sheets are rolled up for transportation, storage, etc., it is required that the sheets do not stick to each other without increasing tackiness (self-adhesion), thereby preventing problems in use. However, the soft olefin-aromatic vinyl compound-aromatic polyene copolymers specifically described in Patent Documents 4 to 6 have relatively high tackiness (self-adhesion) in the uncured sheet or film state.

[0006] The present invention has been made in view of the above-mentioned problems, and aims to provide a sheet or the like that has low tackiness in the uncured state and that exhibits excellent low dielectric properties when cured.

[0007] That is, the present invention provides various specific embodiments as shown below.

[0008] Aspect 1. An uncured sheet comprising a composition containing an olefin-aromatic vinyl compound-aromatic polyene copolymer, which satisfies the following condition (2a), and which has a tack strength of 2 N or less at 25°C in a probe tack test: (2a) The content of aromatic vinyl compound monomer units is in the range of 60% to 80% by mass, and the total of the aromatic vinyl compound monomer units, aromatic polyene monomer units, and olefin monomer units is 100% by mass.

[0009] Aspect 2. An uncured sheet made of a composition containing an olefin-aromatic vinyl compound-aromatic polyene copolymer, satisfying all of the following conditions (1) to (4), wherein the tack strength measured at 25°C by a probe tack test is 2N or less: (1) The number average molecular weight of the copolymer is 500 to 25,000; (2) The aromatic vinyl compound monomer units are aromatic vinyl compounds having 8 to 20 carbon atoms, and the content of the aromatic vinyl compound monomer units is in the range of 60 to 80 mass%; (3) The aromatic polyene monomer units are one or more selected from polyenes having 5 to 20 carbon atoms and having multiple vinyl groups and / or vinylene groups in the molecule, and the content of vinyl groups and / or vinylene groups derived from the aromatic polyene monomer units is 2 to less than 30 per number average molecular weight. (4) The olefin monomer unit is one or more olefins selected from olefins having from 2 to 20 carbon atoms, and the total of the aromatic vinyl compound monomer units, aromatic polyene monomer units, and olefin monomer units is 100 mass%.

[0010] Aspect 3. The uncured sheet according to any one of Aspects 1 and 2, wherein the composition further comprises one or more selected from the group consisting of the following (a) to (c): (a) a curing agent; (b) a radically crosslinkable resin component; and (c) a radically polymerizable monomer.

[0011] Aspect 4. The uncured sheet according to Aspect 3, wherein the (b) radically crosslinkable resin component is a second olefin-aromatic vinyl compound-aromatic polyene copolymer other than the olefin-aromatic vinyl compound-aromatic polyene copolymer, which satisfies all of the following conditions (i) to (iv): (i) the number-average molecular weight of the copolymer is 500 or more and less than 100,000; (ii) the aromatic vinyl compound monomer is an aromatic vinyl compound having 8 to 20 carbon atoms, and the content of the aromatic vinyl compound monomer units is 10% by mass or more and less than 55% by mass; and (iii) the aromatic polyene monomer units are one or more polyenes selected from polyenes having 5 to 20 carbon atoms and having a vinyl group and / or a vinylene group, preferably a plurality of vinyl groups, in the molecule, and the content of the vinyl group and / or vinylene group derived from the aromatic polyene monomer units is 2 or more and less than 20 per number-average molecular weight. (iv) The olefin monomer unit is one or more olefins selected from olefins having from 2 to 20 carbon atoms, the content of the olefin monomer units is 40% by mass or more, and the total of the olefin monomer units, aromatic vinyl compound monomer units, and aromatic polyene monomer units is 100% by mass.

[0012] Aspect 5. The uncured sheet according to any one of Aspects 1 to 4, which is an interlayer insulating material or a bonding sheet.

[0013] Aspect 6. A method for producing the uncured sheet according to any one of Aspects 1 to 5, comprising the steps of kneading raw materials under conditions that do not substantially cure the raw materials to obtain the composition, and molding the composition under conditions that do not substantially cure the raw materials to obtain the uncured sheet.

[0014] Aspect 7. A cured product of the uncured sheet according to any one of Aspects 1 to 5.

[0015] Aspect 8. A multilayer substrate comprising the cured body according to aspect 7.

[0016] According to the present invention, it is possible to realize an uncured sheet or the like which has low tackiness in an uncured state, is easy to mold, and is easy to store and preserve, and which, when subjected to a curing treatment, can provide a low-dielectric insulating material suitable as a high-frequency insulating material.

[0017] Hereinafter, embodiments of the present invention will be described in detail. However, the following embodiments are merely examples for explaining the present invention, and the present invention is not limited thereto. That is, the present invention can be implemented with any modifications within the scope of the gist thereof. In this specification, the term "sheet" also encompasses the concept of "film." Furthermore, the term "film" in this specification also encompasses the concept of "sheet." In this specification, the term "varnish" includes a composition and at least a solvent. In this specification, the term "interlayer insulating material" encompasses the concept of an interlayer adhesive. In this specification, the term "uncured state" encompasses the concept of "semi-cured state," which means a state in which the material itself exhibits thermoplasticity (i.e., the property of being able to be molded into a sheet or the like under molding conditions that do not cause hardening), and refers to a state in which it can be hardened by applying appropriate hardening conditions (heating, pressure, etc.) after molding.

[0018] In this specification, unless otherwise specified, numerical ranges include the lower and upper limits. For example, a numerical range expressed as "1 to 100" includes both the lower limit "1" and the upper limit "100." The same applies to other numerical ranges.

[0019] <Uncured Sheet Comprising Olefin-Aromatic Vinyl Compound-Aromatic Polyene Copolymer> In one embodiment of the present invention, there is provided an uncured sheet made of a composition comprising an olefin-aromatic vinyl compound-aromatic polyene copolymer (hereinafter sometimes abbreviated as "copolymer") that satisfies the following condition (2a), wherein the uncured sheet has a tack strength of 2N or less at 25°C in a probe tack test: (2a) The content of aromatic vinyl compound monomer units is in the range of 60% to 80% by mass, and the total of the aromatic vinyl compound monomer units, aromatic polyene monomer units, and olefin monomer units is 100% by mass. In another embodiment of the present invention, there is provided an uncured sheet made of a composition (hereinafter sometimes abbreviated as "resin composition") comprising an olefin-aromatic vinyl compound-aromatic polyene copolymer (hereinafter sometimes abbreviated as "copolymer") that satisfies all of the following conditions (1), (2a), (3), and (4), wherein the uncured sheet has a tack strength of 2N or less at 25°C in a probe tack test: (1) The number-average molecular weight of the copolymer is 500 or more and 25,000 or less. (2a) The content of aromatic vinyl compound monomer units is in the range of 60% by mass or more and 80% by mass or less. (3) The aromatic polyene monomer units are one or more selected from polyenes having 5 to 20 carbon atoms and having multiple vinyl groups and / or vinylene groups in the molecule, and the content of vinyl groups and / or vinylene groups derived from the aromatic polyene monomer units is 2 or more and less than 30 per number-average molecular weight. (4) The olefin monomer units are one or more selected from olefins having 2 to 20 carbon atoms, and the total of the aromatic vinyl compound monomer units, aromatic polyene monomer units, and olefin monomer units is 100% by mass.

[0020] In one embodiment, the above (2a) may be the following (2): (2) The aromatic vinyl compound monomer unit is an aromatic vinyl compound having from 8 to 20 carbon atoms, and the content of the aromatic vinyl compound monomer unit is in the range of from 60% by mass to 80% by mass.

[0021] In this specification, the term "uncured" is defined as a sheet composition (resin component) having a gel content of 50% by mass or less. The gel content is a value obtained by measurement in accordance with JIS K6796:1998. The uncured sheet of this embodiment may be composed of a composition containing an olefin-aromatic vinyl compound-aromatic polyene copolymer and, if necessary, other resin components and additives typically used in resins, such as fillers, stabilizers, antioxidants, and flame retardants. On the other hand, the composition constituting the uncured sheet of this embodiment preferably does not intentionally contain volatile components such as solvents or monomer components, and is therefore substantially free of these. Specifically, a sheet having a thickness of 0.2 mm or less (preferably a thickness of 0.05 mm or more and 0.2 mm or less) is defined as being substantially free of volatile components when the mass loss (mass change rate) before and after treatment when the sheet is held at 80°C and a reduced pressure of 10 hectopascals or less for one hour is less than 1% by mass relative to the mass of the original composition. By being substantially free of volatile components, the uncured sheet can be stored and distributed without causing sheet-to-sheet adhesion (blocking) at room temperature, whether in a laminated state or in a rolled state, and while suppressing changes in physical properties over time due to the evaporation of volatile components, which is preferable. Furthermore, by being substantially free of volatile components, the uncured sheet has little odor, which is preferable because it can suppress deterioration of the working environment. Here, tack strength refers to the tack strength measured by a probe tack test at 25°C. The probe tack test method is a method in which a probe tack tester is used to measure the load when peeled at a peel speed of 10 mm / sec. More detailed measurement conditions are as described in the Examples below. To suppress blocking between sheets when uncured sheets are stacked or stored in a rolled state, the tack strength must be 2 N or less at 25°C, preferably 0.5 N or less, more preferably 0.3 N or less, and even more preferably 0.2 N or less. It is presumed that the tack strength within the specified range is due to the characteristics of the microphase-separated structure in the sheet.

[0022] Herein, the term "olefin monomer (unit)" refers to one or more compounds (units) selected from α-olefins having from 2 to 20 carbon atoms and cyclic olefins having from 5 to 20 carbon atoms, which are substantially free of oxygen, nitrogen, and halogens and are composed of carbon and hydrogen. Examples of α-olefins having from 2 to 20 carbon atoms include, but are not limited to, ethylene, propylene, 1-butene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 4-methyl-1-pentene, and 3,5,5-trimethyl-1-hexene. Examples of cyclic olefins having from 5 to 20 carbon atoms include, but are not limited to, norbornene, cyclopentene, dimethanooctahydronaphthalene (DMON), trimethanododecahydroanthracene (TMDA), methylphenylnorbornene (5-methyl-5-phenylbicyclo[2.2.1]hept-2-ene), and acenaphthylene. The olefin that can be preferably used is a combination of ethylene with an α-olefin other than ethylene or a cyclic olefin, or ethylene alone.

[0023] In this specification, the aromatic vinyl compound monomer (unit) is an aromatic vinyl compound (unit) having a carbon number of 8 to 20. Examples of the aromatic vinyl compound monomer include, but are not limited to, styrene, paramethylstyrene, ethylstyrene (ethylvinylbenzene), paraisobutylstyrene, various vinylnaphthalenes, and various vinylanthracenes.

[0024] In this specification, the term "aromatic polyene monomer (unit)" refers to a polyene compound (unit) having 5 to 20 carbon atoms and containing multiple vinyl groups and / or vinylene groups within its molecule. Preferred examples of the aromatic polyene monomer include various ortho-, meta-, and para-divinylbenzenes or mixtures thereof, and compounds having an aromatic vinyl structure, such as divinylnaphthalene, divinylanthracene, p-2-propenylstyrene, and p-3-butenylstyrene, which are composed of carbon and hydrogen and substantially free of oxygen, nitrogen, and halogens. However, the aromatic polyene monomer is not particularly limited to these. Furthermore, bifunctional aromatic vinyl compounds such as 1,2-bis(vinylphenyl)ethane (abbreviation: BVPE), as described in JP-A-2004-087639, can also be used. Among these, various ortho-, meta-, and para-divinylbenzenes or mixtures thereof are preferably used, and a mixture of meta-divinylbenzene and para-divinylbenzene is more preferably used. In this specification, these divinylbenzenes are referred to as "divinylbenzenes." When divinylbenzenes are used as the aromatic polyene, they are preferred because they have high curing efficiency and are easy to cure when subjected to a curing treatment.

[0025] The above-mentioned olefin, aromatic vinyl compound, and aromatic polyene monomers may also contain polar groups, such as olefins containing oxygen atoms, nitrogen atoms, etc., aromatic vinyl compounds containing oxygen atoms or nitrogen atoms, or aromatic polyenes containing oxygen atoms or nitrogen atoms, but the total mass of these polar group-containing monomers is preferably 10 mass% or less of the total mass of the resin composition, more preferably 3 mass% or less, and most preferably no polar group-containing monomers are included. By keeping the total mass of the resin composition at 10 mass% or less, the dielectric properties (low dielectric constant / low dielectric loss) of the cured product obtained by curing the resin composition tend to be improved.

[0026] The number average molecular weight (Mn) of the copolymer can be appropriately set depending on the desired performance and is not particularly limited. In one embodiment, it is preferably 500 to 25,000, more preferably 5,000 to 25,000. If the number average molecular weight (Mn) exceeds 25,000, when the uncured sheet is heated and softened to adhere to the substrate layer, the embedding ability (filling ability) of the unevenness of the substrate surface may be poor, and the tackiness may not be sufficiently reduced. If the number average molecular weight (Mn) is less than 500, the mechanical properties of the uncured sheet itself may be reduced. In this specification, the number average molecular weight refers to a value corresponding to the molecular weight in terms of standard polystyrene obtained by GPC (gel permeation chromatography).

[0027] The content of aromatic vinyl compound monomer units contained in this copolymer is in the range of 60% by mass to 80% by mass, preferably 60% by mass to 70% by mass. This range ensures that the uncured state of this copolymer and compositions containing this copolymer have low tackiness (self-adhesion) and facilitates maintaining flexibility in sheet form. From the viewpoint of reducing the tackiness of the uncured sheet while further increasing its flexibility, it is also preferable to set the content of aromatic vinyl compound monomer units in the range of more than 70% by mass to 80% by mass. If the content of aromatic vinyl compound monomer units contained in this copolymer is less than 60% by mass, the uncured sheet will have high tackiness, which may lead to self-adhesion (blocking) when sheets are laminated together. If the content of aromatic vinyl compound monomer units contained in this copolymer exceeds 80% by mass, the uncured sheet will tend to harden and crack, which may reduce the ease of winding it onto a roll, for example. Furthermore, when the content of aromatic vinyl compound monomer units contained in the copolymer is in the range of more than 70% by mass and not more than 80% by mass, hardening of the uncured sheet can be easily prevented by adding or blending a relatively small amount of a soft component, for example, a substance exemplified in the section <Conjugated diene polymers, aromatic vinyl compound-conjugated diene block copolymers or random copolymers, and hydrogenated products thereof> or the section <Another olefin-aromatic vinyl compound-aromatic polyene copolymer> below.

[0028] In the copolymer, the content of vinyl groups and / or vinylene groups derived from aromatic polyene monomer units, preferably the content of vinyl groups, may be 2 or more and less than 30, preferably 3 or more and less than 20, per number average molecular weight. If the content of vinyl groups and / or vinylene groups is less than 2, the crosslinking efficiency tends to be low, making it difficult to obtain a cured product with sufficient crosslinking density. The content of vinyl groups derived from aromatic polyene monomer units (divinylbenzene units) per number average molecular weight in the copolymer can be calculated, for example, by multiplying the number average molecular weight (Mn) in terms of standard polystyrene obtained by GPC (gel permeation chromatography) known to those skilled in the art by: １The content of vinyl groups derived from aromatic polyene units can be obtained by comparing the content of vinyl groups derived from aromatic polyene units obtained by H-NMR measurement. １ The assignment of peaks obtained by H-NMR measurement is known from literature. １ A method for determining the composition of a copolymer from a comparison of peak areas obtained by H-NMR measurement is also known. １ The measurement was performed in a known quantitative mode using a H-NMR measurement method. １３ It is also possible to improve the accuracy of the composition by adding data on the peak areas and their ratios in the C-NMR spectrum. １３ The composition can also be determined from the peak area and ratio data of the C-NMR spectrum. In this specification, the content of divinylbenzene units in a copolymer is determined based on the peak intensity ( １ That is, the content of divinylbenzene units is calculated from the content of vinyl groups derived from divinylbenzene units, with one vinyl group being considered as a vinyl group derived from one divinylbenzene unit in the copolymer.

[0029] In a preferred embodiment of the copolymer, the total content of the olefin monomer units, aromatic vinyl compound monomer units, and aromatic polyene monomer units is 100% by mass. The content of the olefin monomer units is preferably 20% by mass or more and less than 40% by mass.

[0030] <Method for Producing Olefin-Aromatic Vinyl Compound-Aromatic Polyene Copolymer> The olefin-aromatic vinyl compound-aromatic polyene copolymer of this embodiment can be produced by copolymerizing the respective monomers of an aromatic vinyl compound, an aromatic polyene, and an olefin, which is used as needed, by coordination polymerization. For example, it is preferable to use a single-site coordination polymerization catalyst composed of a transition metal compound and a co-catalyst, as described in JP 2009-161743 A, JP 2010-280771 A, WO 00 / 37517, etc., because the olefin-aromatic vinyl compound-aromatic polyene copolymer can be produced efficiently.

[0031] In the present copolymer, examples of the olefin-aromatic vinyl compound-aromatic polyene copolymer (which may contain an olefin) include, but are not particularly limited to, an ethylene-styrene-divinylbenzene copolymer, an ethylene-propylene-styrene-divinylbenzene copolymer, an ethylene-1-hexene-styrene-divinylbenzene copolymer, and an ethylene-1-octene-styrene-divinylbenzene copolymer.

[0032] The composition of the present embodiment may contain the present copolymer alone, or may further contain, as other components, one or more members selected from the group consisting of (a) a curing agent, (b) a radical-crosslinkable resin component, and (c) a radical-crosslinkable monomer.

[0033] <(a) Curing Agent> The curing agent that may be contained in the composition of this embodiment can be any known curing agent that can be used for the polymerization or curing of conventional aromatic polyenes or aromatic vinyl compounds. Examples of such curing agents include, but are not limited to, radical polymerization initiators (radical generators), cationic polymerization initiators, and anionic polymerization initiators. Radical polymerization initiators are preferred. Organic peroxides and azo-based polymerization initiators are even more preferred, and can be freely selected depending on the application and conditions. Catalogs listing organic peroxides can be downloaded from the NOF Corporation website, for example, https: / / www.nof.co.jp / business / functional-materials / functional-materials-product09. Organic peroxides are also listed in catalogs from Fujifilm Wako Pure Chemical Industries, Ltd. and Tokyo Chemical Industry Co., Ltd. Curing agents that can be used in this embodiment can be obtained from these companies. Furthermore, hydrocarbon-based radical polymerization initiators that do not contain oxygen or nitrogen atoms in their structure, i.e., radical polymerization initiators composed only of carbon and hydrogen atoms, such as 2,3-dimethyl-2,3-diphenylbutane, can also be suitably used. When a cured product is produced using such a hydrocarbon-based radical polymerization initiator, a cured product containing no oxygen or nitrogen atoms can be obtained with a lower dielectric constant and dielectric dissipation factor, further improving the low dielectric properties of the cured product. Azo-based polymerization initiators are also preferred because the nitrogen atoms contained in the polar group upon radical generation are released from the system as nitrogen gas, resulting in a cured product with even lower dielectric properties. Known photopolymerization initiators that utilize light, ultraviolet light, or radiation can also be used as curing agents. Examples of photopolymerization initiators include photoradical polymerization initiators, photocationic polymerization initiators, and photoanionic polymerization initiators. Such photopolymerization initiators are available, for example, from Tokyo Chemical Industry Co., Ltd. Furthermore, curing using radiation or electron beams themselves is also possible. Crosslinking and curing by thermal polymerization of the raw materials contained therein can also be performed without the use of a curing agent.

[0034] There are no particular restrictions on the amount of curing agent used, but generally, 0.01 to 10 parts by mass of curing agent per 100 parts by mass of resin composition is preferred. In one embodiment, the resin composition preferably excludes the curing agent and solvent. When using a curing agent such as a peroxide or azo-based polymerization initiator, the curing process is carried out at an appropriate temperature and time, taking into account its half-life. In this case, the conditions are optional depending on the curing agent, but generally, a temperature range of approximately 50°C to 200°C is appropriate.

[0035] The composition according to this embodiment may contain one or more soft or hard resins as the radically crosslinkable resin component (b). The addition of these components allows the mechanical properties of the uncured sheet and the resulting cured product to be adapted to the mechanical properties required for various applications. The distinction between soft and hard is based on the state (at room temperature and atmospheric pressure) provided by the manufacturer.

[0036] <Radical Crosslinkable Soft Resin> Radical crosslinkable soft resins that can be suitably used in the composition of this embodiment preferably include one or more elastomers selected from ethylene-based or propylene-based elastomers having a radical crosslinkable functional group, conjugated diene polymers, aromatic vinyl compound-conjugated diene block or random copolymers, and hydrogenated products thereof, but are not particularly limited thereto. The amount of the radical crosslinkable soft resin used can be appropriately set depending on the desired performance, taking into account the handleability and moldability (handleability as a thermoplastic resin) of the composition in an uncured state, as well as reduced tackiness, and is not particularly limited. The amount is preferably 100 parts by mass or less, more preferably 1 to 50 parts by mass, and most preferably 1 to 30 parts by mass per 100 parts by mass of the copolymer. The radical crosslinkable soft resin that can be suitably used in the composition of this embodiment preferably has a number average molecular weight (Mn) of 500 to 100,000, and more preferably 1,000 to 4,500.

[0037] <Ethylene-based or propylene-based elastomers having radically crosslinkable functional groups> Examples of ethylene-based elastomers include ethylene-α-olefin copolymers such as ethylene-octene copolymer and ethylene-1-hexene copolymer, EPR, EPDM, etc. Examples of propylene-based elastomers include atactic polypropylene, low stereoregular polypropylene, propylene-α-olefin copolymers such as propylene-1-butene copolymer, etc., but are not particularly limited to these. Examples of radically crosslinkable functional groups include functional groups typically contained in rubber raw materials such as EPDM, such as vinyl groups, allyl groups, and ethylidene norbornene groups (units). These radically crosslinkable soft resins may be modified, for example, by introducing functional groups with maleic anhydride or other compounds.

[0038] <Conjugated diene polymers, aromatic vinyl compound-conjugated diene block copolymers or random copolymers, and hydrogenated products thereof> Examples of conjugated diene polymers include, but are not limited to, polybutadiene and 1,2-polybutadiene. Examples of aromatic vinyl compound-conjugated diene block copolymers or random copolymers and hydrogenated products thereof include, but are not limited to, SBS, SIS, SEBS, SEPS, SEEPS, and SEEBS. Suitable 1,2-polybutadienes are available, for example, from Nippon Soda Co., Ltd. under the product names B-1000, 2000, and 3000 of liquid polybutadiene. Another suitable copolymer containing a 1,2-polybutadiene structure is "Ricon 100" manufactured by TOTAL CRAY VALLEY. Furthermore, copolymers containing a 1,2-polybutadiene structure, including 1,2-polybutadiene, may be partially hydrogenated for the purpose of improving low dielectric properties, etc. These conjugated diene polymers and their hydrogenated products may be modified, for example, by introducing functional groups with maleic anhydride or other compounds. Among conjugated diene polymers, polymers that do not contain vinylene groups in the main chain or that contain fewer vinylene groups are preferred. Vinylene groups in the main chain tend to remain in the cured product even after curing, and these vinylene groups tend to react with oxygen in the air to generate oxygen-containing polar groups, which undesirably tends to increase the dielectric constant and dielectric dissipation factor of the cured product after high-temperature durability testing (e.g., 125°C in air). From this perspective, 1,4-polybutadiene copolymers are not suitable as conjugated diene polymers, and 1,2-polybutadiene polymers or copolymers containing a 1,2-polybutadiene structure are preferred. Further preferred from this viewpoint are various hydrogenated polymers in which the vinylene group content has been significantly reduced by hydrogenation. Examples of hydrogenated polymers of conjugated diene polymers include hydrogenated SBR, SEBS, SEPS, SEEPS, and SEEBS, and preferred are hydrogenated polymers of conjugated diene polymers having methyl-substituted styrene.

[0039] As the radical crosslinkable soft resin that can be suitably used in the composition of the present embodiment, an olefin-aromatic vinyl compound-aromatic polyene copolymer (hereinafter, sometimes abbreviated as "second copolymer") other than the above-mentioned olefin-aromatic vinyl compound-aromatic polyene copolymer can also be used.

[0040] <Another Olefin-Aromatic Vinyl Compound-Aromatic Polyene Copolymer (Second Copolymer)> The composition of this embodiment may contain one or more second olefin-aromatic vinyl compound-aromatic polyene copolymers other than the present copolymer, which satisfy all of the following conditions (i) to (iv): (i) the number-average molecular weight of the copolymer is 500 or more and less than 100,000; (ii) the aromatic vinyl compound monomer units are aromatic vinyl compounds having 8 to 20 carbon atoms, and the content of the aromatic vinyl compound monomer units is 10% by mass or more and less than 60% by mass, preferably 10% by mass or more and less than 55% by mass; (iii) the aromatic polyene monomer units are one or more selected from polyenes having 5 to 20 carbon atoms and having a vinyl group and / or vinylene group, preferably a plurality of vinyl groups, in the molecule, and the content of the vinyl group and / or vinylene group derived from the aromatic polyene monomer units is 2 or more and less than 20 per number-average molecular weight. (iv) The olefin monomer unit is a single or multiple unit selected from olefins having 2 to 20 carbon atoms, the content of the olefin monomer unit is 40% by mass or more, and the total of the olefin monomer unit, aromatic vinyl compound monomer unit, and aromatic polyene monomer unit is 100% by mass. Examples of second olefin-aromatic vinyl compound-aromatic polyene copolymers that satisfy all of these other specific conditions are described in, for example, WO 2021 / 112087, WO 2021 / 112088, and WO 2022 / 014599, but are not particularly limited thereto. A second olefin-aromatic vinyl compound-aromatic polyene copolymer that satisfies all of these other specific conditions is soft and exhibits a low dielectric constant and a low dielectric loss tangent. Therefore, by combining it with the olefin-aromatic vinyl compound-aromatic polyene copolymer of this embodiment to form a composition, it is possible to obtain a cured product with a low dielectric constant and a low dielectric loss tangent that covers a wide range of physical properties, making it suitable. Specifically, a composition containing 1 to 50 parts by mass, preferably 1 to 30 parts by mass, of the second olefin-aromatic vinyl compound-aromatic polyene copolymer relative to 100 parts by mass of the olefin-aromatic vinyl compound-aromatic polyene copolymer of this embodiment can exhibit the advantage of having little tackiness (self-adhesiveness) in an uncured state.

[0041] <Radical Crosslinkable Hard Resin> Radical crosslinkable hard resins suitable for use in the composition of this embodiment include, but are not limited to, polyether resins, polyether ketone resins, and aromatic polyene resins having radical crosslinkable functional groups. From the viewpoint of not impairing the flexibility of the uncured sheet, the amount of radical crosslinkable hard resin used is preferably 1 to 70 parts by mass, more preferably 1 to 50 parts by mass, and even more preferably 1 to 30 parts by mass, per 100 parts by mass of the copolymer. Using these hard resins in amounts within the above ranges is preferable for adjusting the tackiness in the uncured state, adjusting the adhesiveness of the cured product to other components, maintaining strength, and maintaining a high elastic modulus. Radical crosslinkable hard resins suitable for use in the composition of this embodiment preferably have a number average molecular weight (Mn) of 500 to 100,000, more preferably 1,000 to 4,500.

[0042] <Polyether-Based Resin Having Functional Groups> Examples of polyether-based resins include, but are not limited to, polyphenylene ether and polyether. It is preferable that the molecular terminals of the polyphenylene ether having functional groups are modified with functional groups. Furthermore, when added for the purpose of curing the composition of this embodiment, it is preferable that the polyphenylene ether has multiple functional groups in one molecule. For example, a modified polyphenylene ether is preferable. Examples of functional groups include radically polymerizable functional groups and functional groups such as epoxy groups, and preferably radically polymerizable functional groups. A vinyl group is preferable as the radically polymerizable functional group. As the vinyl group, one or more of the group consisting of an allyl group, a (meth)acryloyl group, and an aromatic vinyl group are preferable, one or more of the group consisting of a (meth)acryloyl group and an aromatic vinyl group are more preferable, and an aromatic vinyl group is most preferable. In other words, in the composition of this embodiment, a bifunctional polyphenylene ether in which both molecular chain terminals are modified with radically polymerizable functional groups is particularly preferable. Examples of such polyphenylene ethers include, but are not limited to, Noryl (registered trademark) SA9000 manufactured by SABIC (modified polyphenylene ether having methacryloyl groups at both ends, number average molecular weight 2200) and bifunctional polyphenylene ether oligomer manufactured by Mitsubishi Gas Chemical Company, Inc. (OPE-2St, modified polyphenylene ether having vinylbenzyl groups at both ends, number average molecular weight 1200). Also usable are allylated PPE manufactured by Asahi Kasei Corporation and aromatic polyethers (ELPAC HC-F series) manufactured by JSR Corporation. Of these, the bifunctional polyphenylene ether oligomer (OPE-2St) manufactured by Mitsubishi Gas Chemical Company, Inc. and aromatic polyethers (ELPAC HC-F series) manufactured by JSR Corporation are preferred.

[0043] <Aromatic Polyene Resin> The aromatic polyene resin includes a divinylbenzene-based reactive hyperbranched copolymer (PDV or ODV) manufactured by Nippon Steel Chemical & Material Co., Ltd. Such PDV is described, for example, in the literature "Synthesis of Polyfunctional Aromatic Vinyl Copolymer and Development of a New IPN-Type Low Dielectric Loss Material Using the Same" (Kawabe Masanao, Journal of the Japan Institute of Electronics Packaging, p. 125, Vol. 12 No. 2 (2009)), but is not particularly limited thereto.

[0044] <(c) Radical Crosslinkable Monomer> The radical crosslinkable monomer that may be contained in the composition is a monomer that can be polymerized with a radical polymerization initiator, and its content may preferably be 10 parts by mass or less per 100 parts by mass of the copolymer. The composition may be substantially free of a monomer. When the monomer content is 10 parts by mass or less, the uncured composition does not become viscous, making it easy to mold as a thermoplastic resin. When the uncured sheet contains a monomer within the above range, the content of the monomer is less likely to change during storage. Suitable monomers have a molecular weight of less than 1,000, more preferably less than 500. Preferred examples of the monomer include, but are not limited to, aromatic vinyl compound monomers, aromatic polyene monomers, and / or polar monomers. More preferred examples of the monomer include aromatic vinyl compounds and aromatic polyenes. Also suitable for use are BVPE (1,2-bis(vinylphenyl)ethane) and the like, as described in JP 2003-212941 A. From the viewpoint of increasing the mechanical strength (elastic modulus) of the cured product at high temperatures, the aromatic polyene is preferably used in an amount of 1 part by mass or more and 30 parts by mass or less per 100 parts by mass of the copolymer. Furthermore, a relatively small amount of a polar monomer can be used for the purpose of imparting adhesion to other materials required as an insulating material or improving crosslink density. Examples of the polar monomer include, but are not limited to, various maleimides, bismaleimides, maleic anhydride, glycidyl (meth)acrylate, triallyl isocyanurate, tri(meth)acrylic isocyanurate, and trimethylolpropane tri(meth)acrylate. Maleimides and bismaleimides that can be used in the present embodiment are described in, for example, WO 2016 / 114287 and JP 2008-291227 A, and can be purchased from, for example, Daiwa Chemical Industry Co., Ltd. or Designer Molecules Inc. Of these maleimide group-containing compounds, bismaleimides are preferred from the viewpoints of solubility in organic solvents, high-frequency characteristics, high adhesion to conductors, moldability of prepregs, and the like.

[0045] The bismaleimides are preferably those represented by the following formula (B-1).

[0046]

[0047] In formula (B-1), R represents an alkylene group having 5 or more carbon atoms, and L represents a single bond or a divalent linking group. R and L each independently may have a substituent. The maleimide represented by formula (B-1) is preferably represented by the following formula (B-2).

[0048]

[0049] In formula (B-2), R' each independently represents an alkylene group having 5 or more carbon atoms which may have a substituent, A each independently represents an alkylene group having 5 or more carbon atoms which may have a substituent or a divalent group having an aromatic ring which may have a substituent, and n represents an integer of 1 to 10.

[0050] Examples of the maleimides represented by formula (B-2) include compounds represented by the following formula (B-3): In formula (B-3), n represents an integer of 1 to 10. Examples of the compound represented by formula (B-3) include BMI-1500 (average n value=1.3) manufactured by Designer Molecules Inc.

[0051]

[0052] Bismaleimides may be used as polyaminobismaleimide compounds. Polyaminobismaleimide compounds can be obtained, for example, by subjecting a compound having two maleimide groups at its terminals to a Michael addition reaction with an aromatic diamine compound having two primary amino groups in its molecule. To achieve high crosslinking efficiency with a small amount of addition, it is preferable to use a polar monomer having a bifunctional or higher polyfunctional group. Examples of such polar monomers include bismaleimides, triallyl isocyanurate (TAIC), and trimethylolpropane tri(meth)acrylate. The amount of polar monomer that may be contained in the composition can be appropriately determined depending on the desired performance. While not particularly limited, it is preferably in the range of 0.1 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, per 100 parts by weight of the copolymer. Using 10 parts by weight or less tends to lower the dielectric constant and dielectric dissipation factor of the resulting cured product. For example, the dielectric constant tends to be lower than 3.0, and the dielectric dissipation factor tends to be lower than 0.005.

[0053] Furthermore, the composition of this embodiment may contain one or more selected from the following (d) to (f), so long as the low tackiness of the uncured sheet and the dielectric properties of the cured product are not excessively impaired: (d) filler (e) flame retardant (f) surface modifier In a preferred embodiment, from the viewpoint of achieving both low tackiness and low dielectric properties, it is desirable to add these additives in small amounts (for example, 100 parts by mass or less of each per 100 parts by mass of the copolymer) or to include essentially no additives.

[0054] <Filler> Known inorganic or organic fillers can be added as needed. In one embodiment, these fillers are added for the purposes of controlling the coefficient of thermal expansion, controlling thermal conductivity, and reducing cost. The amount used is optional depending on the purpose. In particular, when adding an inorganic filler, it is preferable to use a known surface modifier, such as a silane coupling agent. In particular, when the objective of this embodiment is to produce a resin composition with excellent low dielectric constant and low dielectric loss, the inorganic filler is preferably one or more of boron nitride (BN) or silica, and silica is more preferred. As silica, fused silica is preferred. From the perspective of low dielectric properties, preferably 100 parts by mass or less of filler may be used per 100 parts by mass of the copolymer. Furthermore, hollow fillers or fillers with many voids may be added to improve or enhance low dielectric properties (low dielectric constant, low dielectric loss tangent).

[0055] Alternatively, organic fillers such as high molecular weight polyethylene or ultra-high molecular weight polyethylene may be used instead of inorganic fillers. The organic fillers are preferably crosslinked themselves from the viewpoint of heat resistance, and are preferably blended in the form of fine particles or powder. The incorporation of these organic fillers tends to suppress increases in the dielectric constant and dielectric loss tangent.

[0056] On the other hand, by mixing and dispersing a high-dielectric-constant insulating filler, for example, having a dielectric constant of preferably 4 to 10,000, more preferably 5 to 10,000 at 1 GHz, into the resin composition of this embodiment, it is possible to produce an insulating cured body having a high-dielectric-constant insulating layer with a dielectric constant of preferably 4 to 20 while suppressing an increase in dielectric loss tangent (dielectric loss). Increasing the dielectric constant of a film made of the insulating cured body enables circuit miniaturization and increased capacitor capacity, contributing to the miniaturization of high-frequency electrical components. High-dielectric-constant, low-dielectric-loss-tangent insulating layers are suitable for applications such as capacitors, inductors for resonant circuits, filters, and antennas. Examples of high-dielectric-constant insulating fillers used in this embodiment include, but are not limited to, inorganic fillers or metal particles that have been subjected to an insulating treatment. Specific examples include known high-dielectric-constant inorganic fillers such as barium titanate and strontium titanate, and are specifically described, for example, in JP 2004-087639 A.

[0057] <Flame Retardant> A flame retardant can be used in the composition of this embodiment. From the viewpoint of maintaining a low dielectric constant and a low dielectric loss tangent, preferred flame retardants include known organic phosphorus-based flame retardants such as phosphate esters or condensates thereof, known bromine-based flame retardants, and red phosphorus. Among phosphate esters, compounds having multiple xylenyl groups in the molecule are particularly preferred from the viewpoint of flame retardancy and a low dielectric loss tangent.

[0058] In addition to the flame retardant, antimony compounds such as antimony trioxide, antimony tetraoxide, antimony pentoxide, and sodium antimonate, or nitrogen-containing compounds such as melamine, triallyl-1,3,5-triazine-2,3,4-(1H,3H,5H)-trione, and 2,4,6-triaryloxy-1,3,5-triazine may be added as a flame retardant aid. The total amount of these flame retardants and flame retardant aids can be appropriately determined depending on the desired performance and is not particularly limited, but is typically 1 to 100 parts by mass per 100 parts by mass of the copolymer. Furthermore, 30 to 100 parts by mass of a polyphenylene ether (PPE) resin with a low dielectric constant and excellent flame retardancy may be used per 100 parts by mass of the flame retardant.

[0059] <Surface Modifier> The composition of this embodiment may contain a surface modifier from the viewpoint of improving adhesion to copper foil for wiring. In particular, the purpose may be to increase the adhesive strength (peel strength) to the smooth surface of copper foil. The amount of surface modifier used can be appropriately set depending on the desired performance and is not particularly limited. However, it is preferably in the range of 0.001 to 10 parts by mass, more preferably 0.01 to 5 parts by mass, and most preferably 0.01 to 1 part by mass, per 100 parts by mass of the olefin-aromatic vinyl compound-aromatic polyene copolymer. By using an amount of surface modifier of 10 parts by mass or less, the dielectric constant and dielectric dissipation factor of the cured product obtained from this composition tend to be low. Furthermore, known surface modifiers can be used in this embodiment. Examples of such surface modifiers include, but are not limited to, silane-based surface modifiers (also known as silane coupling agents), titanate-based surface modifiers, and isocyanate-based surface modifiers. Preferably, a silane-based surface modifier can be used. These surface modifiers may be used singly or in combination. Such silane-based surface modifiers are available from, for example, Shin-Etsu Chemical Co., Ltd., Dow Corning Corporation, and Evonik Corporation.

[0060] The composition and varnish of this embodiment may contain additives that are commonly used in resins in the industry, such as antioxidants, weathering agents, light stabilizers, lubricants, compatibilizers, antistatic agents, etc., to the extent that the desired effects and purposes are not impaired. The composition and varnish of this embodiment are obtained by mixing, dissolving, or melting the various additives described above, and any known method can be used for mixing, dissolving, or melting.

[0061] <Resin Composition> The resin composition of the present embodiment can be mixed by a known kneading method, for example, using a twin-screw kneader, various rolls, various kneaders, or the like.

[0062] <Varnish> An uncured sheet according to this embodiment can be produced from a varnish. The varnish can be obtained by dissolving or dispersing the copolymer and other raw materials in a solvent. A solvent with a high boiling point at atmospheric pressure, i.e., low volatility, results in a uniform thickness of the applied film, so a solvent with a boiling point above a certain level is preferred. The boiling point is preferably approximately 75°C or higher at atmospheric pressure, more preferably 130°C or higher and 300°C or lower. Solvents known in the art can be used, and are not particularly limited. Examples of solvents that can be used include, but are not limited to, cyclohexane, cyclohexanone, methyl ethyl ketone (MEK), toluene, ethylbenzene, xylene, mesitylene, tetralin, acetone, limonene, mixed alkanes, and mixed aromatic solvents. The concentration of the resin component of the varnish and the viscosity of the varnish are optional, but are generally several hundred thousand mPa·s or less at room temperature, preferably several tens of thousands mPa·s or less, more preferably 10,000 mPa·s or less, and most preferably 2,000 mPa·s or less. The amount of solvent used can be appropriately determined depending on the desired performance and is not particularly limited, but 10 to 2000 parts by mass per 100 parts by mass of the composition of this embodiment is preferred. Specifically, the varnish can be applied, impregnated, filled, or dripped onto another material using an appropriate method, and the solvent removed to produce a molded product. The resulting product can then be cured with heat or light to obtain the desired cured product. Furthermore, the polymerization liquid obtained during copolymerization of the olefin-aromatic vinyl compound-aromatic polyene copolymer of this embodiment (which generally contains, in addition to the copolymer, solvents used in polymerization such as toluene, ethylbenzene, cyclohexane, and methylcyclohexane, residual monomers such as styrene and divinylbenzene, residual monomers such as olefin monomers, catalysts, and co-catalyst components) can be used directly as a varnish. Alternatively, a varnish can be obtained by distilling off some or all of the solvent and residual monomers from the polymerization liquid under reduced pressure and diluting the resulting solution with the solvent as needed. That is, the varnish may contain residual monomers from the polymerization or the solvent used in the polymerization. The uncured sheet according to this embodiment can be obtained by substantially removing the solvent from the varnish.

[0063] <Uncured Sheet> The shape and thickness of the uncured sheet obtained from the composition of this embodiment are arbitrary. The sheet may be a single layer or may be one or more layers contained in a multilayer sheet. In the case of a multilayer sheet, it may also include a substrate layer or a protective layer. The uncured sheet of this embodiment has low tackiness, so it can be easily peeled from the protective layer or substrate layer during actual use. In the case of a resinous composition, the uncured sheet of this embodiment exhibits the properties of a thermoplastic resin and can be molded into a sheet shape in a substantially uncured state using known molding methods for thermoplastic resins, such as extrusion molding, press molding, and inflation molding, under conditions that do not cause substantial crosslinking. For example, in the case of a varnish-like composition, a sheet-like molded product is generally obtained by applying the composition to a substrate and then removing the solvent by heating, reducing pressure, air-drying, or the like. Uncured sheets can be obtained by these methods. Alternatively, a sheet-like composite can be obtained by impregnating a porous substrate, woven fabric, or nonwoven fabric with the varnish of this embodiment and removing the solvent.

[0064] In the case of interlayer insulating materials (bonding sheets), which are applications of the present composition, the composition is in the form of a sheet or film. For these applications, it may be necessary to store and transport the uncured composition by laminating it with a protective film as needed or by winding it into a roll. In such cases, low tackiness (self-adhesion) is necessary. High tackiness makes it difficult to isolate the composition as an interlayer insulating sheet during actual use due to self-adhesion. Tackiness can be reduced by adding fillers or auxiliary materials (preferably hard). In some cases, reducing the tackiness of the olefin-aromatic vinyl compound-aromatic polyene copolymer itself, which is the main component, is important for reducing the tackiness of the present sheet. Specifically, it is preferable that the tackiness of an uncured sheet of the present olefin-aromatic vinyl compound-aromatic polyene copolymer itself, which is the main component, is 2N or less in tackiness as measured by probe tack measurement. The sheet or film may be uncured (semi-cured) to the extent that it can maintain its shape, or it may be fully cured. The degree of cure of the composition can be quantitatively measured by measuring the gel content, flowability, or by known dynamic mechanical analysis (DMA). The uncured molded article can then be crosslinked (cured).

[0065] <Curing> The uncured sheet of this embodiment can be cured by a known method, taking into consideration the curing conditions (temperature, time, pressure) of the raw materials and curing agent contained therein. When the curing agent used is a peroxide, the curing conditions can be determined by referring to the half-life temperature and the like disclosed for each peroxide.

[0066] <Cured product obtained from composition, cured product of molded article> The cured sheet obtained from the composition of this embodiment is sufficiently cured, and the gel content (gel fraction) measured in accordance with the description of JIS K6796:1998 is not particularly limited, but may be 90% by mass or more. Furthermore, in the measurement range of 10 to 50 GHz of the cured product, particularly at 10 GHz, the dielectric constant is not particularly limited, but is preferably 3.0 to 2.0 or more, more preferably 2.8 to 2.0 or more, and most preferably 2.5 to 2.0 or more. Similarly, the dielectric loss tangent is not particularly limited, but is preferably 0.0015 to 0.0005 or more, more preferably 0.0012 to 0.0005 or more. Furthermore, the volume resistivity of the obtained cured product is not particularly limited, but is preferably 1 x 10 １５ The water absorption is not particularly limited, but is preferably 0.1% by mass or less, and such a cured product is preferable as an electrical insulating material. These values ​​are particularly preferable as an electrical insulating material for high frequencies of 3 GHz or more.

[0067] The cured products obtained from the uncured sheets of this embodiment are particularly suitable as electrical insulating materials for high-frequency signals, and these cured products can be suitably used for CCL substrates, FCCL substrates, interlayer insulating materials, or coverlays. In one embodiment, the present copolymer or a composition containing the copolymer is used for a CCL substrate, FCCL substrate, interlayer insulating material, or coverlay. This embodiment can be suitably used for a multilayer substrate.

[0068] The features of the present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited thereto. That is, the materials, amounts used, ratios, processing details, processing procedures, etc. shown in the following examples can be appropriately changed as long as they do not deviate from the spirit of the present invention. Furthermore, the values ​​of various production conditions and evaluation results in the following examples represent preferred upper or lower limits in the embodiments of the present invention, and preferred numerical ranges may be defined by combining the above-mentioned upper or lower limits with the values ​​of the following examples or values ​​between the examples.

[0069] The copolymers and compositions obtained in the synthesis examples were analyzed by the following methods.

[0070] <Analysis of Chemical Structure of Compound> The content of vinyl group units derived from ethylene, styrene, and divinylbenzene in the copolymer is determined by: １ The H-NMR was performed based on the peak area intensity assigned to each compound. The sample was dissolved in deuterated 1,1,2,2-tetrachloroethane, and the measurement was carried out at 80 to 130°C.

[0071] <Measurement of Molecular Weight> The molecular weight was determined as a number average molecular weight (Mn) converted to standard polystyrene using GPC (gel permeation chromatography) under the following conditions.

[0072] Column: TSK-GEL MultiporeHXL-M φ7.8 × 300 mm (manufactured by Tosoh Corporation), four columns connected in series. Column temperature: 40°C. Solvent: THF. Flow rate: 1.0 ml / min. Detector: RI detector.

[0073] <Gel content> The gel content was determined as the content insoluble in boiling xylene according to JIS K6796:1998.

[0074] <Dielectric constant and dielectric loss (dielectric loss tangent)> The dielectric constant and dielectric loss tangent were measured by the split cylinder resonator method. The measurement devices used were an 8722ES network analyzer manufactured by Agilent Technologies and a split cylinder resonator (CR-740 40 GHz) manufactured by EM Lab Co., Ltd. Using a 0.2 mm × 30 mm × 40 mm sample cut out from the sheet, values ​​were measured at 23°C in the measurement frequency range of 35 to 42 GHz.

[0075] <Tensile modulus> In accordance with JIS K6251:2017, a cured product of the composition according to each Example and Comparative Example was formed into a film sheet with a thickness of approximately 1 mm, and cut into the shape of a No. 2 dumbbell 1 / 2 test piece. The tensile modulus was measured using a Tensilon UCT-1T model manufactured by Orientec Co., Ltd. at 25°C at a pulling rate of 500 mm / min to determine the modulus of elasticity.

[0076] <Evaluation of Tackiness> The varnish-like compositions prepared in the Examples and Comparative Examples were applied to a Teflon (registered trademark) sheet using an applicator so that the film thickness after drying would be approximately 50 μm, and the sheet was thoroughly dried in a vacuum dryer at 80°C and a vacuum of 10 hectopascals or less for 3 hours or longer until it was confirmed that the mass change rate per hour of drying was less than 1% by mass. The test was performed using a probe tack tester (TE6001, manufactured by Tester Sangyo Co., Ltd.) with a φ5.05 mm stainless steel probe at 25°C and a load of 1 kgf / cm. ２ The probe was pressed against the sample surface at a contact speed of 10 mm / sec and held for 10 seconds. The sample was then peeled off at a peeling speed of 10 mm / sec, and the load at that time was measured. This measurement was carried out eight times, and the average value of the measurements was taken as the tack force.

[0077] <Production of Copolymer> Each compound was produced with reference to the production methods described in JP-A-2009-161743, JP-A-2010-280771, and WO 2017 / 122295. Polymerization was carried out using Rac-diphenylmethylene(1-indenyl)(cyclopentadienyl)zirconium dichloride (structure: see formula (1) below), Rac-dimethylmethylenebis(4,5-benzo-1-indenyl)zirconium dichloride (structure: see formula (2) below), or dimethylmethylenebiscyclopentadienylzirconium dichloride (structure: see formula (3) below) as a catalyst, tritium tetrakis(pentafluorophenyl)borate (TRI-FABA, manufactured by Tosoh Finechem Co., Ltd.) as a co-catalyst, toluene as a solvent, and styrene, divinylbenzene, ethylene, and, if necessary, 1-octene as raw materials, using a 10 L polymerization vessel equipped with a stirrer and a heating / cooling jacket, and adjusting the monomer concentration, ethylene pressure, and polymerization temperature as appropriate to obtain a copolymer having the desired composition and molecular weight.

[0078]

[0079]

[0080]

[0081] (Synthesis Example P-1) Ethylene, styrene, and divinylbenzene were copolymerized using Rac-diphenylmethylene(1-indenyl)(cyclopentadienyl)zirconium dichloride as a catalyst and tritium tetrakis(pentafluorophenyl)borate as a co-catalyst to obtain copolymer P-1. Table 1 shows the composition and number average molecular weight of the copolymer.

[0082] (Synthesis Example P-2) Ethylene, styrene, 1-octene, and divinylbenzene were copolymerized using Rac-dimethylmethylenebis(4,5-benzo-1-indenyl)zirconium dichloride as a catalyst and tritium tetrakis(pentafluorophenyl)borate as a co-catalyst to obtain P-2. Table 1 shows the composition and number average molecular weight of the copolymer.

[0083] (Synthesis Example P-3) Ethylene, styrene, and divinylbenzene were copolymerized using dimethylmethylenebiscyclopentadienylzirconium dichloride and tritium tetrakis(pentafluorophenyl)borate as a co-catalyst to obtain P-3. Table 1 shows the composition and number average molecular weight of the copolymer.

[0084] (Synthesis Example P-4) Ethylene, styrene, and divinylbenzene were copolymerized using Rac-diphenylmethylene(1-indenyl)(cyclopentadienyl)zirconium dichloride as a catalyst and tritium tetrakis(pentafluorophenyl)borate as a co-catalyst to obtain P-4. Table 1 shows the composition and number average molecular weight of the copolymer.

[0085] Other raw materials are as follows: Bifunctional polyphenylene ether oligomer (OPE-2St, modified polyphenylene ether having vinylbenzyl groups at both ends, number-average molecular weight 1,200) was prepared by diluting a toluene solution product manufactured by Mitsubishi Gas Chemical Company, Inc. with toluene, adding a large amount of methanol to perform methanol precipitation, air-drying, and then drying under reduced pressure, thereby obtaining a powdery polyphenylene ether oligomer.

[0086] SEBS: Hydrogenated styrene-based thermoplastic elastomer (SEBS), "Tuftec H1041" manufactured by Asahi Kasei Corporation, number average molecular weight 58,000

[0087] The curing agent used was Perbutyl P (α,α'-di(t-butylperoxy)diisopropylbenzene) manufactured by NOF Corporation.

[0088]

[0089]

[0090] Example 1 Using a vessel equipped with a heating and cooling jacket and a stirring blade, P-1 (ethylene-styrene-divinylbenzene copolymer) obtained in the synthesis example and a solvent (toluene) were mixed according to the formulation shown in Table 2 (units in the table are parts by mass), heated to approximately 60°C, and stirred to dissolve the copolymer. Furthermore, 1 part by mass of curing agent was added per 100 parts by mass of the resin components excluding the curing agent and solvent, dissolved, and mixed with stirring to obtain a varnish-like composition. The resulting composition was poured into a Teflon (registered trademark) mold (frame length 7 cm, width 7 cm, thickness 0.2 mm, 0.5 mm, or 1.0 mm) on a PET sheet placed on a glass plate, air-dried, and then further dried at 80°C for 3 hours or more in a vacuum dryer (pressure 10 hectopascals or less) to obtain an uncured sheet. Here, the sheet was removed during drying in the vacuum dryer, the sheet mass was measured, and it was confirmed that the mass change rate per hour of drying was less than 1% by mass. This was confirmed in the following examples as well. Furthermore, a Teflon sheet and a Teflon mold were placed under a load of 5 MPa in a press, and the sheet was heat-treated at 120°C for 30 minutes, 150°C for 30 minutes, and then 200°C for 120 minutes. The Teflon sheet and the Teflon mold were then removed to obtain a cured sheet.

[0091] (Examples 2 to 4) Using the same procedure as in Example 1, curable resin compositions were prepared according to the formulations shown in Table 2 (units in the table are parts by mass), and uncured sheets and cured sheets of the compositions of the examples were obtained using the same procedure.

[0092] Comparative Examples 1 to 3 Curable resin compositions were prepared using the formulations shown in Table 2 (units in the table are parts by mass) in the same manner as in Example 1, and uncured sheets and cured sheets of the compositions of the comparative examples were obtained in the same manner.

[0093] The tackiness of the uncured sheets obtained in each Example and Comparative Example was evaluated. The tackiness (adhesive strength) of the uncured sheets obtained in each Example was very low, satisfying the condition of a tackiness of 2N or less at 25°C in a probe tack test. In contrast, the tackiness (adhesive strength) of the uncured sheets obtained in the Comparative Examples was high in all cases, and did not satisfy the condition of a tackiness of 2N or less at 25°C in a probe tack test.

[0094] The tensile modulus, dielectric constant, and dielectric dissipation factor at 25°C of the cured sheets obtained in each of the Examples and Comparative Examples are shown in Table 2. It can be seen that the cured sheets of the Examples all exhibit low dielectric constants and dielectric dissipation factors that compare favorably with those of the Comparative Examples.

Claims

1. An uncured sheet consisting of a composition containing an olefin-aromatic vinyl compound-aromatic polyene copolymer that satisfies the following condition (2a), and has a tack strength of 2N or less at 25°C in a probe tack test: (2a) The content of aromatic vinyl compound monomer units is in the range of 60% by mass or more and 80% by mass or less, and the total of the aromatic vinyl compound monomer units, aromatic polyene monomer units, and olefin monomer units is 100% by mass.

2. An uncured sheet made of a composition containing an olefin-aromatic vinyl compound-aromatic polyene copolymer, which satisfies all of the following conditions (1) to (4), and has a tack strength of 2N or less as measured at 25°C by a probe tack test: (1) The number average molecular weight of the copolymer is 500 to 25,000; (2) The aromatic vinyl compound monomer unit is an aromatic vinyl compound having 8 to 20 carbon atoms, and the content of the aromatic vinyl compound monomer unit is in the range of 60% by mass to 80% by mass; (3) The aromatic polyene monomer unit is one or more selected from polyenes having 5 to 20 carbon atoms and having multiple vinyl groups and / or vinylene groups in the molecule, and the content of the vinyl groups and / or vinylene groups derived from the aromatic polyene monomer unit is 2 to less than 30 per number average molecular weight. (4) The olefin monomer unit is one or more olefins selected from olefins having from 2 to 20 carbon atoms, and the total of the aromatic vinyl compound monomer units, the aromatic polyene monomer units and the olefin monomer units is 100 mass %.

3. The uncured sheet according to claim 1 or 2, wherein the composition further comprises one or more selected from the group consisting of the following (a) to (c): (a) a curing agent; (b) a radically crosslinkable resin component; and (c) a radically polymerizable monomer.

4. The uncured sheet according to claim 3, wherein the (b) radical crosslinkable resin component is a second olefin-aromatic vinyl compound-aromatic polyene copolymer other than the olefin-aromatic vinyl compound-aromatic polyene copolymer, which satisfies all of the following conditions (i) to (iv): (i) the number average molecular weight of the copolymer is 500 or more and less than 100,000; (ii) the aromatic vinyl compound monomer is an aromatic vinyl compound having 8 to 20 carbon atoms, and the content of the aromatic vinyl compound monomer unit is 10% by mass or more and less than 55% by mass; (iii) the aromatic polyene monomer unit is one or more selected from polyenes having 5 to 20 carbon atoms and having a vinyl group and / or a vinylene group, preferably a plurality of vinyl groups, in the molecule, and the content of the vinyl group and / or the vinylene group derived from the aromatic polyene monomer unit is 2 or more and less than 20 per number average molecular weight. (iv) The olefin monomer unit is one or more selected from olefins having 2 to 20 carbon atoms, the content of the olefin monomer unit is 40 mass% or more, and the total of the olefin monomer unit, aromatic vinyl compound monomer unit, and aromatic polyene monomer unit is 100 mass%.

5. The uncured sheet according to claim 1 or 2, which is an interlayer insulating material or a bonding sheet.

6. A method for producing the uncured sheet according to claim 1 or 2, comprising the steps of: kneading raw materials under conditions that do not substantially cure the raw materials to obtain the composition; and molding and processing the composition under conditions that do not substantially cure the raw materials to obtain an uncured sheet.

7. A cured product of the uncured sheet according to claim 1 or 2.

8. A multilayer substrate comprising the cured product according to claim 7.

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