Copolymer composition, cross-linked molded article, and grommet

Abstract

To provide a copolymer composition excellent in mechanical strength and elongation even when the hardness of an obtained crosslinked molded article is in a low range.SOLUTION: A copolymer composition comprising a copolymer (S) having a structural unit derived from ethylene (A), a structural unit derived from an α - olefin (B) having 3 to 20 carbon atoms, and a structural unit derived from a non-conjugated polyene (C), a specific hydrosilyl group-containing compound (Y), a platinum-based catalyst, a reaction inhibitor, an organic peroxide (Z), hydrophobic silica, and a softener, wherein the hydrophobic silica is contained in an amount of 30 to 200 parts by mass based on 100 parts by mass of the copolymer (S).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a copolymer composition, a crosslinked molded article, and a grommet. [Background technology]

[0002] Ethylene-α-olefin copolymer elastomers, such as ethylene-propylene copolymers (EPM, EPR) and ethylene-propylene-diene copolymers (EPDM), do not have unsaturated bonds in the main chain of their molecular structure, and therefore have superior heat aging resistance, weather resistance, and ozone resistance compared to general-purpose conjugated diene rubbers. They are therefore widely used in applications such as automotive parts, electrical wire materials, electronic and electrical parts, construction and civil engineering materials, and industrial parts.

[0003] Crosslinked molded articles obtained by crosslinking EPDM with a hydrosilyl-containing compound have characteristics such as excellent mechanical strength, heat aging resistance, compression set, and bloom resistance, and the ability to perform continuous crosslinking, compared to common crosslinking methods such as sulfur vulcanization and peroxide crosslinking. For example, Patent Document 1 proposes crosslinking using a hydrosilyl-containing compound in combination with an organic peroxide, which is relatively inexpensive and easily available.

[0004] However, EPDM crosslinked molded articles obtained by crosslinking using a hydrosilyl-containing compound have insufficient physical properties such as mechanical strength. Furthermore, when a hydrosilyl-containing compound is used in combination with an organic peroxide, problems arise in that scorch resistance is reduced and injection moldability is impaired. To solve these problems, for example, Patent Document 2 proposes an EDPM copolymer composition that is excellent in injection moldability and that produces crosslinked molded articles with excellent hot strength. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-156950 [Patent Document 2] JP 2024-32010 A Summary of the Invention [Problem to be solved by the invention]

[0006] For example, grommets are used as component units in a wide range of fields, such as automotive parts, electrical wiring materials, electronic and electrical components, construction and civil engineering materials, and industrial parts, and are therefore required to have a wide range of hardness due to their wide range of applications. In particular, in recent years, there has been a demand for lower hardness products in order to reduce the weight of component units. However, Patent Documents 1 and 2 do not fully investigate copolymer compositions that can give crosslinked molded articles with a low hardness range (for example, a hardness (Durometer-A) of 60 or less).

[0007] An object of the present invention is to provide a copolymer composition which has excellent mechanical strength and elongation even when the hardness of the resulting crosslinked molded article is in a low range. [Means for solving the problem]

[0008] The present inventors have conducted extensive research to solve the above problems, and as a result have found that the above problems can be solved by the following configuration, thereby achieving the present invention. An example of the configuration of the present invention is as follows.

[0009] [1] a copolymer (S) having structural units derived from ethylene (A), structural units derived from an α-olefin (B) having 3 to 20 carbon atoms, and structural units derived from a non-conjugated polyene (C) containing, in one molecule, two or more partial structures selected from the group consisting of the following formula (I) and the following formula (II); a hydrosilyl group-containing compound (Y) which is an organohydrogenpolysiloxane represented by the following formula (a) and which has at least one silicon-bonded aralkyl group and at least two silicon-bonded hydrogen atoms in the molecule; A platinum-based catalyst; A reaction inhibitor; an organic peroxide (Z); Hydrophobic silica; Softener and Including, A copolymer composition comprising 30 to 200 parts by mass of the hydrophobic silica per 100 parts by mass of the copolymer (S).

[0010] [ka] (In formula (a), n and p are each independently 0 or a positive number, m is a number ranging from 1 to 20, and the sum of n, m, and p is 5 to 50. 1 and R 2 are each independently a monovalent alkyl group, and a plurality of R 1 and R 2 may be the same or different. a is an aralkyl group, and R is R 1 , R 2 , hydrogen atoms, and R a and the two R's may be the same or different. However, when n=1, at least one of R's is a hydrogen atom, and when n=0, both R's are hydrogen atoms.

[0011] [2] The copolymer composition according to [1], wherein the copolymer (S) satisfies one or more requirements selected from the following requirements (1) to (5): (1) The ratio [A] / [B] of the number of moles of structural units derived from ethylene (A) to the number of moles [B] of structural units derived from an α-olefin having 3 to 20 carbon atoms is 40 / 60 to 99.9 / 0.1; (2) The mass fraction (mass %) of the structural units derived from the non-conjugated polyene (C) is 0.07 to 10 mass % based on the total structural units constituting the copolymer (S); (3) The weight average molecular weight (Mw), the mass fraction of the constitutional unit derived from the non-conjugated polyene (C) (mass fraction (mass%) of (C)), and the molecular weight of the non-conjugated polyene (C) (molecular weight of (C)) satisfy the following formula (i): 4.5≦Mw×(C) mass fraction / 100 / (C) molecular weight≦80 …(i) (4) Complex viscosity η at a frequency of ω = 0.1 rad / s obtained by linear viscoelasticity measurement (190 °C) using a rheometer * (ω=0.1)(Pa·sec) and the complex viscosity η at frequency ω=100rad / s * (ω=100)(Pa·sec) * (ω=0.1) / η * (ω=100), the intrinsic viscosity [η], and the mass fraction of the constitutional unit derived from the non-conjugated polyene (C) satisfy the following formula (ii): P / ([η] 2.9 )≦(C) weight fraction × 6 …(ii) (5) Complex viscosity η* at a frequency of ω = 0.01 rad / s obtained by linear viscoelasticity measurement (190 °C) using a rheometer (ω=0.01) (Pa·sec) and the complex viscosity η* at a frequency of ω=10 rad / sec (ω=10) (Pa·sec) and the apparent iodine value derived from the non-conjugated polyene (C) satisfy the following formula (iii): Log[η* (ω=0.01) ] / Log[η* (ω=10) ]≦0.0753×{apparent iodine value derived from non-conjugated polyene (C)}+1.42 …(iii)

[0012] [3] The copolymer composition according to [1] or [2], wherein the α-olefin (B) having 3 to 20 carbon atoms is propylene.

[0013] [4] The copolymer composition according to any one of [1] to [3], wherein the non-conjugated polyene (C) contains 5-vinyl-2-norbornene (VNB).

[0014] [5] The copolymer composition according to any one of [1] to [4], wherein the copolymer (S) consists solely of an ethylene-propylene-VNB copolymer.

[0015] [6] It also contains carbon black, The copolymer composition according to any one of [1] to [5], wherein the carbon black is contained in an amount of 1 to 70 parts by mass per 100 parts by mass of the copolymer (S).

[0016] [7] The copolymer composition according to any one of [1] to [6], wherein the softener is a paraffin-based process oil.

[0017] [8] The copolymer composition according to any one of [1] to [7], wherein the softener is contained in an amount of 75 to 120 parts by mass per 100 parts by mass of the copolymer (S).

[0018] [9] The copolymer composition according to any one of [1] to [8], wherein a test piece made by stacking six 2 mm thick sheet-like crosslinked molded articles obtained by crosslinking the copolymer composition has a hardness (Durometer-A) of 60 or less as measured in accordance with JIS K 6253-3:2012.

[0019]

[10] A crosslinked molded article obtained by crosslinking the copolymer composition according to any one of [1] to [9].

[0020]

[11]

[10] A grommet made of the crosslinked molded article. [Effects of the Invention]

[0021] The copolymer composition containing the ethylene-α-olefin-non-conjugated polyene copolymer of the present invention exhibits excellent mechanical strength and elongation even when the hardness of the resulting crosslinked molded article is low. The crosslinked molded articles formed using the copolymer composition examples of the present invention can have a wide range of hardness, and are therefore suitable for use in rubber molded articles such as grommets. DETAILED DESCRIPTION OF THE INVENTION

[0022] [Copolymer composition] A copolymer composition according to one embodiment of the present invention (hereinafter also referred to as "the composition") contains a copolymer (S), a hydrosilyl group-containing compound (Y), a platinum-based catalyst, a reaction inhibitor, an organic peroxide (Z), hydrophobic silica, and a softener. In this specification and claims, "parts by mass" refers to parts by mass converted into solid content excluding solvent. Furthermore, a numerical range expressed by "to" means a numerical range in which the numbers before and after "to" are the lower and upper limits.

[0023] [Copolymer (S)] The copolymer (S) has structural units derived from ethylene (A), structural units derived from an α-olefin (B) having 3 to 20 carbon atoms, and structural units derived from a non-conjugated polyene (C) containing, in one molecule, two or more partial structures selected from the group consisting of the following formula (I) and the following formula (II):

[0024] [ka]

[0025] In the copolymer (S), the total mass fraction of the structural units derived from ethylene (A), the structural units derived from the α-olefin (B) having 3 to 20 carbon atoms, and the structural units derived from the non-conjugated polyene (C) relative to all structural units is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 92% by mass or more, and particularly preferably 100% by mass.

[0026] Examples of the α-olefin (B) having 3 to 20 carbon atoms (hereinafter simply referred to as "α-olefin (B)") include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, and 1-eicosene. Among these, α-olefins having 3 to 8 carbon atoms, such as propylene, 1-butene, 1-hexene, and 1-octene, are preferred, with propylene being particularly preferred. Such α-olefins are preferred because they are relatively inexpensive in terms of raw material cost, the resulting copolymer compositions exhibit excellent mechanical properties, and molded articles having rubber elasticity can be obtained. These α-olefins may be used alone or in combination of two or more.

[0027] Examples of the non-conjugated polyene (C) containing two or more partial structures selected from the group consisting of the formula (I) and the following formula (II) in a molecule include 5-vinyl-2-norbornene (VNB), norbornadiene, 1,4-hexadiene, 5-(2-propenyl)-2-norbornene, 5-(3-butenyl)-2-norbornene, 5-(1-methyl-2-propenyl)-2-norbornene, 5-(4-pentenyl)-2-norbornene, 5-(1-methyl-3-butenyl)-2-norbornene, 5-(5-hexenyl)-2-norbornene, 5-(1-methyl-3-butenyl)-2-norbornene, 5-(2-ethyl-4-pentenyl)-2-norbornene, 5-(2-ethyl-3-butenyl)-2-norbornene, 5-(6-heptenyl)-2-norbornene, 5-(3-methyl-5-hexenyl)-2-norbornene, 5-(3-ethyl-4-pentenyl)-2-norbornene, 5-(7-octenyl)-2-norbornene, 5-(2-methyl-6-heptenyl)-2-norbornene, 5-(1,2-dimethyl-5-hexenyl)-2-norbornene, 5-(1,2,3-trimethyl-4-pentenyl)-2-norbornene, dicyclopentadiene, and the like. Among these, the non-conjugated polyene (C) preferably contains VNB, and more preferably is VNB, because it is easily available, crosslinks well with the hydrosilyl-containing compound (Y) described below, and the heat resistance of the copolymer composition is likely to be improved. The non-conjugated polyene (C) may be used alone or in combination of two or more.

[0028] The copolymer (S) may further contain, in addition to the structural units derived from ethylene (A), α-olefin (B), and non-conjugated polyene (C), a structural unit derived from non-conjugated polyene (CX) containing only one partial structure selected from the group consisting of general formulas (I) and (II) in one molecule, within the range that does not impair the effects of the present invention.

[0029] Examples of the non-conjugated polyene (CX) include 5-ethylidene-2-norbornene (ENB), 5-methylene-2-norbornene, 5-(2,3-dimethyl-3-butenyl)-2-norbornene, 5-(3,4-dimethyl-4-pentenyl)-2-norbornene, 5-(5-ethyl-5-hexenyl)-2-norbornene, and 5-(2-methyl-1-propenyl)-2-norbornene.

[0030] Among these, ENB is preferred because it is readily available, the crosslinking rate during crosslinking with a hydrosilyl-containing compound is easily controlled, and good mechanical properties are easily obtained. The non-conjugated polyene (CX) may be used alone or in combination of two or more. When the copolymer (S) contains a structural unit derived from a non-conjugated polyene (CX), the content thereof is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 0.01 to 8% by mass, based on all structural units constituting the copolymer.

[0031] The copolymer (S) may contain at least one biomass-derived monomer (e.g., ethylene (A), α-olefin (B), non-conjugated polyene (C), and non-conjugated polyene (CX)), or may contain at least one chemically recycled monomer (e.g., ethylene (A), α-olefin (B), non-conjugated polyene (C), and non-conjugated polyene (CX)). The same type of monomer constituting the copolymer may consist solely of biomass-derived monomers, solely of chemically recycled monomers, solely of fossil fuel-derived monomers, or may contain biomass-derived monomers and / or chemically recycled monomers and / or fossil fuel-derived monomers. It is preferable that the copolymer (S) contain structural units derived from biomass-derived monomers from the viewpoint of reducing the environmental impact. It is preferable that the copolymer (S) contain structural units derived from chemically recycled monomers from the viewpoint of reducing the environmental impact (mainly waste reduction).

[0032] The copolymer (S) preferably contains an ethylene-propylene-VNB copolymer, and preferably consists of only an ethylene-propylene-VNB copolymer. When copolymer (S) contains an ethylene-α-olefin-non-conjugated polyene copolymer other than ethylene-propylene-VNB copolymer, the mass fraction of the ethylene-propylene-VNB copolymer relative to the total mass of copolymer (S) is preferably more than 50 mass% and less than 100 mass%, more preferably 60 to 99 mass%, even more preferably 65 to 98 mass%, and particularly preferably 70 to 97 mass%.

[0033] The intrinsic viscosity [η] of the copolymer (S) (in decalin at 135°C) is preferably 0.1 to 5.0 dL / g, more preferably 1.0 to 4.0 dL / g, even more preferably 1.5 to 3.5 L / g, and particularly preferably 2.0 to 3.0 L / g. When the intrinsic viscosity [η] of the copolymer component (S) (in decalin at 135°C) is equal to or greater than the lower limit, a molded article having better physical properties is easily obtained. When the intrinsic viscosity [η] of the copolymer component (S) (in decalin at 135°C) is equal to or less than the upper limit, a copolymer composition having better processability is easily obtained. The intrinsic viscosity [η] of the copolymer (S) (in decalin at 135°C) can be adjusted by the amount of hydrogen fed during polymerization. The intrinsic viscosity [η] (in decalin at 135°C) of the copolymer (S) is a value measured in decalin at 135°C.

[0034] The weight average molecular weight (Mw) of the copolymer component (S) is preferably 10,000 to 600,000, more preferably 150,000 to 550,000, even more preferably 300,000 to 520,000, and particularly preferably 400,000 to 500,000. When the weight average molecular weight (Mw) of the copolymer component (S) is equal to or greater than the lower limit, better physical properties are likely to be obtained. When the weight average molecular weight (Mw) of the copolymer component (S) is equal to or less than the upper limit, better processability is likely to be obtained. The weight average molecular weight (Mw) of the copolymer (S) can be measured by 3D-GPC using the apparatus and conditions described in the Examples section.

[0035] The Mooney viscosity ML(1+4)125°C of the copolymer (S) at 125°C is preferably 10-100, more preferably 30-90, still more preferably 50-80, and particularly preferably 65-75. When the Mooney viscosity ML(1+4)125°C is within the above range, a copolymer having excellent roll processability even in a high-hardness oil-less compound, good post-treatment (ribbon handling properties) and excellent rubber physical properties can be obtained.

[0036] The glass transition temperature (Tg) of the copolymer (S) measured by differential scanning calorimetry (DSC) is −50° C. or lower, preferably −53° C. or lower, more preferably −55° C. or lower, and particularly preferably −57° C. or lower. When Tg is within the above range, the obtained molded article has excellent low-temperature properties. Specifically, Tg can be determined by the method described in the Examples below.

[0037] The copolymer (S) preferably satisfies one or more of the requirements selected from the following requirements (1) to (5), more preferably satisfies two or more of the requirements, even more preferably satisfies three or more of the requirements, particularly preferably satisfies four or more of the requirements, and most preferably satisfies all five of the requirements.

[0038] Requirement (1): The ratio [A] / [B] of the number of moles of structural units derived from ethylene (A) to the number of moles [B] of structural units derived from an α-olefin having 3 to 20 carbon atoms is 40 / 60 to 99.9 / 0.1. Requirement (2): The mass fraction of the structural units derived from the non-conjugated polyene (C) is 0.07 to 10 mass % of all structural units constituting the copolymer.

[0039] Requirement (3): The weight-average molecular weight (Mw), the mass fraction of the constitutional unit derived from the non-conjugated polyene (C) (mass fraction (mass%) of (C)), and the molecular weight of the non-conjugated polyene (C) (molecular weight of (C)) satisfy the following formula (i): 4.5≦Mw×(C) mass fraction / 100 / (C) molecular weight≦80 …(i)

[0040] Requirement (4): Complex viscosity η at a frequency of ω = 0.1 rad / s obtained by linear viscoelasticity measurement (190 °C) using a rheometer * (ω=0.1) (Pa·sec) and the complex viscosity η at frequency ω=100rad / s * (ω=100) (Pa·sec) and the ratio P〔η * (ω=0.1) / η * (ω=100) ], the intrinsic viscosity [η] of the copolymer (A), and the mass fraction of (C) satisfy the following formula (ii). P / ([η] 2.9 )≦(C) weight fraction × 6 …(ii)

[0041] Requirement (5): Complex viscosity η at a frequency of ω = 0.01 rad / s obtained by linear viscoelasticity measurement (190 °C) using a rheometer * (ω=0.01) (Pa·sec) and the complex viscosity η at frequency ω=10 rad / s * (ω=10) (Pa·sec) and the apparent iodine value derived from the non-conjugated polyene (C) satisfy the following formula (iii): Log{η * (ω=0.01)} / Log{η * (ω=10)}≦0.0753×{apparent iodine value derived from non-conjugated polyene (C)}+1.42 …(iii)

[0042] Requirement (1) In the copolymer (S), the ratio [A] / [B] of the number of moles of structural units derived from ethylene (A) to the number of moles [B] of structural units derived from an α-olefin (B) having 3 to 20 carbon atoms is preferably 40 / 60 to 99.9 / 0.1, more preferably 50 / 50 to 90 / 10, even more preferably 55 / 45 to 85 / 15, and particularly preferably 60 / 40 to 78 / 22. When the copolymer (S) satisfies the requirement (1), the molded article obtained by crosslinking the copolymer (S) with a hydrosilyl-containing compound exhibits excellent rubber elasticity and is excellent in mechanical strength and flexibility. The ratio [A] / [B] of the copolymer (S) is 13 It can be determined by C-NMR.

[0043] Requirement (2) The mass fraction of the structural units derived from the non-conjugated polyene (C) in the copolymer (S) is preferably 0.07 to 10 mass%, more preferably 0.1 to 8.0 mass%, even more preferably 0.5 to 5.0 mass%, and particularly preferably 1.0 to 3.0 mass%, relative to 100 mass% of the total of all structural units constituting the copolymer (structural units derived from ethylene (A), structural units derived from α-olefin (B), structural units derived from the non-conjugated polyene (C), and structural units derived from the non-conjugated polyene (CX)). When copolymer (S) satisfies requirement (2), the crosslinked molded article obtained from this composition has sufficient hardness and excellent mechanical properties. Furthermore, when copolymer component (S) is crosslinked with a hydrosilyl-containing compound, it exhibits a fast crosslinking rate, allowing for efficient production of crosslinked molded articles. The mass fraction of the constitutional unit derived from the non-conjugated polyene (C) in the copolymer (S) is 13 It can be determined by C-NMR.

[0044] Furthermore, it is preferable that the mass fraction of the structural unit derived from the non-conjugated polyene (C) (mass fraction of (C)) (mass%) and the natural logarithm (Ln(Mw)) of the weight average molecular weight (Mw) of the copolymer satisfy the following formula: 6-0.45×Ln(Mw)≦(C) mass fraction≦10

[0045] Requirement (3) In the copolymer (S), it is preferable that the weight average molecular weight (Mw) of the copolymer, the mass fraction of the structural unit derived from the non-conjugated polyene (C) (mass fraction (mass%) of (C)), and the molecular weight of the non-conjugated polyene (C) (molecular weight of (C)) satisfy the following (i): 4.5≦Mw×(C) mass fraction / 100 / (C) molecular weight≦80 …(i) The weight average molecular weight (Mw) of the copolymer (S) can be determined as a polystyrene-equivalent value measured by 3D-GPC.

[0046] The "Mw × mass fraction of (C) / 100 / molecular weight of (C)" is the number of constitutional units derived from the non-conjugated polyene (C) per Mw of the copolymer (n C ), more preferably 4.5 or more and 78 or less, and even more preferably 4.5 or more and 75 or less. c When the ratio is equal to or greater than the lower limit, a sufficient crosslinking rate is easily obtained when crosslinking with a hydrosilyl-containing compound, and when the ratio is equal to or less than the upper limit, excessive crosslinking is unlikely to occur, and the resulting crosslinked molded article exhibits better mechanical properties.

[0047] When copolymer (S) satisfies requirement (3), the content of long chain branches in the copolymer falls within an appropriate range, resulting in a high crosslinking rate when crosslinked with a hydrosilyl-containing compound, an excellent balance of physical properties such as mechanical properties of the resulting crosslinked molded article, and a resistance to post-crosslinking, particularly excellent heat aging resistance.

[0048] When the copolymer contains the structural unit (CX), it is preferable that the weight average molecular weight (Mw) of the copolymer, the mass fraction (mass%) of (C), the molecular weight of (C), the mass fraction of the structural unit derived from the non-conjugated polyene (CX) (mass fraction (mass%) of (C)), and the molecular weight of the non-conjugated polyene (CX) (molecular weight of (C)) satisfy the following formula (i'): 4.5≦Mw×[{mass fraction of (C) / 100} / molecular weight of (C)+{mass fraction of (CX) / 100} / molecular weight of (CX)]≦80 …(i') The "Mw × [{mass fraction of (C) / 100} / molecular weight of (C) + {mass fraction of (CX) / 100} / molecular weight of (CX)]" is the total number (n C+CX ), more preferably 4.5 or more and 78 or less, and even more preferably 4.5 or more and 75 or less.

[0049] Requirement (4) The complex viscosity η of copolymer (S) at a frequency of ω = 0.1 rad / s was obtained by linear viscoelasticity measurement (190 °C) using a rheometer. * (ω=0.1) (Pa·sec) and the complex viscosity η at frequency ω=100rad / s * (ω=100) (Pa·sec) and the ratio P〔η * (ω=0.1) / η * (ω=100) ], the intrinsic viscosity [η] of the copolymer, and the mass fraction of (C) preferably satisfy the following formula (ii): P / ([η] 2.9 ) ≦ (C) mass fraction × 6 … (ii) The P value was calculated by measuring the complex viscosity at 0.1 rad / s and the complex viscosity at 100 rad / s using a viscoelasticity measuring device, Ares (manufactured by Rheometric Scientific), at 190°C, 1.0% strain, and various frequencies. The P value was calculated by calculating the ratio (η * The intrinsic viscosity [η] of the copolymer is the value measured in decalin at 135°C.

[0050] Furthermore, it is more preferable that the copolymer (S) satisfies the following formula (ii-1). P / ([η] 2.9 ) ≦ Weight fraction of [A3] × 5.7 … Formula (ii-1) Here, the complex viscosity η at frequency ω=0.1 rad / s * (ω=0.1) and the complex viscosity η at frequency ω=100rad / s * (ω=100) The ratio P [η * (ω=0.1) / η * (ω=100) ] represents the frequency dependence of viscosity, and corresponds to the P / ([η] 2.9 ) tends to show high values ​​when there are many long chain branches, although it is affected by factors such as short chain branches and molecular weight.

[0051] Generally, in an ethylene-α-olefin-non-conjugated polyene copolymer, the more structural units derived from non-conjugated polyenes the copolymer contains, the more long-chain branches it tends to contain. However, it is believed that copolymer (A) can satisfy the above formula (ii) or (ii-1) because it has fewer long-chain branches than conventionally known ethylene-α-olefin-non-conjugated polyene copolymers.

[0052] Requirement (5) The complex viscosity η of copolymer (S) at a frequency of ω = 0.01 rad / s was obtained by linear viscoelasticity measurement (190 °C) using a rheometer. * (ω=0.01) (Pa·sec) and the complex viscosity η at frequency ω=10 rad / s * (ω=10) It is preferable that the apparent iodine value (Pa·sec) derived from the non-conjugated polyene (C) satisfies the following formula (iii): Log{η * (ω=0.01)} / Log{η * (ω=10)}≦0.0753×{apparent iodine value derived from non-conjugated polyene (C)}+1.42 …(iii)

[0053] Complex viscosity η * (ω=0.01) and complex viscosity η * (ω=10) is the complex viscosity η in requirement (4) * (ω=0.1) and complex viscosity η * (ω=100) and can be obtained in the same way except for the measurement frequency. The apparent iodine value derived from the non-conjugated polyene (C) can be calculated by the following formula: Apparent iodine value derived from (C) = mass fraction of (C) × 253.81 / molecular weight of (C)

[0054] In the formula (iii), the left side represents shear rate dependency, which is an index of the amount of long chain branches, and the right side represents an index of the content of non-conjugated polyene (C) that is not consumed as long chain branches during polymerization. When the formula (iii) is satisfied, the degree of long chain branching is not too high, which is preferable. On the other hand, when the formula (iii) is not satisfied, this indicates that a large proportion of the copolymerized non-conjugated polyene (C) is consumed in the formation of long chain branches.

[0055] The copolymer (S) may contain two or more types of copolymers. For example, two or more types of copolymers (S) may be contained. For example, two or more types of copolymers (S) having different molar ratios of ethylene / α-olefin having 3 to 20 carbon atoms, two or more types of copolymers (S) having different iodine values, or two or more types of copolymers (S) having different intrinsic viscosities [η] (in decalin at 135°C) may be mixed and used.

[0056] <Method for producing copolymer (S)> The method for producing the copolymer (S) is not particularly limited, and it can be obtained by various known production methods, for example, a conventionally known production method using a metallocene catalyst in which a metallocene compound is used as one component of the catalyst. As the metallocene catalyst and the production method using the catalyst, for example, the examples described in WO 2015 / 122415, particularly paragraphs

[0249] to

[0320] of the publication can be used.

[0057] <Hydrosilyl Group-Containing Compound (Y)> The hydrosilyl group-containing compound (Y), one of the components of the present composition, is represented by the following formula (a), and is an organohydrogenpolysiloxane having at least one silicon-bonded aralkyl group and at least two silicon-bonded hydrogen atoms in the molecule. The hydrosilyl group-containing compound (Y) may be contained alone or in combination with two or more different compounds.

[0058] [ka]

[0059] In formula (a), n and p are each independently 0 or a positive number, m is a number ranging from 1 to 20, and the sum of n, m, and p is 5 to 50. 1 and R 2 are each independently a monovalent alkyl group, and a plurality of R 1 and R 2 may be the same or different. a is an aralkyl group, and R is R 1 , R 2 , hydrogen atoms, and R a and the two R's may be the same or different, provided that when n=1, at least one of R's is a hydrogen atom, and when n=0, both R's are hydrogen atoms.

[0060] The hydrosilyl group-containing compound (Y) is an organohydrogenpolysiloxane with a linear structure that has a relatively low degree of siloxane polymerization and has at least one silicon-bonded aralkyl group and at least two silicon-bonded hydrogen atoms in each molecule.

[0061] In formula (a), m is the number of diorganosiloxy units having silicon-bonded aralkyl groups, and is 1 to 20, preferably 2 to 10, more preferably 2 to 8, and even more preferably 3 to 6.

[0062] In formula (a), n is the number of organohydrogensiloxy units having silicon-bonded hydrogen atoms. n can be 0 or 1, but when n=1, at least one of the two Rs is a hydrogen atom, and when n=0, both Rs are hydrogen atoms. In other words, the organohydrogenpolysiloxane represented by formula (a) has a structure containing at least two silicon-bonded hydrogen atoms per molecule. Note that even if n is a number other than 0 or 1, one or both of the Rs at both ends of the molecular chain can be silicon-bonded hydrogen atoms.

[0063] n is preferably a number other than 0 or 1, and more preferably a number satisfying n≧m. n is preferably 3-10, more preferably 3-9, and even more preferably 5-9.

[0064] In formula (a), p is the number of diorganosiloxy units that do not contain aralkyl groups or silicon-bonded hydrogen atoms. p may be 0, or may be the number obtained by subtracting the values ​​of n and m from the total degree of polymerization of siloxy units, which is represented by the sum of n, m, and p, as described below. p is preferably 0 to 12, more preferably 0 to 10, even more preferably 0 to 5, and particularly preferably 0 to 2.

[0065] In the organohydrogenpolysiloxane represented by formula (a), the diorganosiloxy unit (-[O-Si(R 1 )(R 2 )]-), organohydrogensiloxy units having silicon-bonded hydrogen atoms (-[O-Si(R 1 )H]-), and diorganosiloxy units that do not contain aralkyl groups or silicon-bonded hydrogen atoms (-[O-Si(R 1 )(R 2 The siloxy units such as (a)-(a) may be arranged in a block form or randomly, i.e., the order of arrangement of the siloxy units in formula (a) is not particularly limited.

[0066] The hydrosilyl group-containing compound (Y) has a relatively low degree of siloxane polymerization. In formula (a), the sum of the values ​​of n, m, and p is 5 to 50, preferably 5 to 20, and more preferably 5 to 15. In formula (a), it is preferable that m is 3 to 6, n is 5 to 9, and p is 0 to 2.

[0067] In formula (a), R is R 1 , R 2 , hydrogen atoms, and R a However, when n=0 or 1, both or one of R is a hydrogen atom. R in the formula1 and R 2 R are monovalent alkyl groups, which may be the same or different, and some of the carbon atom-bonded hydrogen atoms may be substituted with halogen atoms. 1 and R 2 The number of carbon atoms in the alkyl group is preferably 1 to 20, more preferably 1 to 10, still more preferably 1 to 5, and particularly preferably 1 to 3. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, and a butyl group, with a methyl group being particularly preferred.

[0068] In formula (a), R a The number of carbon atoms in the aralkyl group in R is preferably 7 to 20, more preferably 7 to 15. Examples of the aralkyl group include a benzyl group, a phenylethyl group, a phenylpropyl group, and a phenylbutyl group. a As R, an aralkyl group containing at least one branching unit represented by -CH(CH3)- in the alkanediyl group between the aryl group such as a phenyl group and the silicon atom is preferred. a As the alkyl group, an aralkyl group represented by —CH2—CH(CH3)—C6H5 is particularly preferred.

[0069] The aralkyl group is a characteristic functional group that confers usefulness as a crosslinking agent to the hydrosilyl group-containing compound (Y). In particular, the presence of an aralkyl group together with a silicon-bonded hydrogen atom in the compound (Y) having n, m, and p within the above ranges tends to significantly improve the physical properties of the resulting crosslinked product. By applying the hydrosilyl group-containing compound (Y) to the copolymer (S) and then crosslinking it, it is possible to obtain a molded product that is particularly excellent in physical properties such as scorch resistance, moldability, elongation at break, and compression set.

[0070] In the present composition, the amount of the hydrosilyl group-containing compound (Y) blended per 100 parts by mass of the copolymer (S) is preferably 0.1 to 100 parts by mass, more preferably 0.5 to 30 parts by mass, even more preferably 1.0 to 10 parts by mass, and particularly preferably 1.0 to 5.0 parts by mass.

[0071] <Platinum catalyst> The platinum catalyst, one of the components of this composition, is an addition reaction catalyst, and any catalyst can be used without particular limitation, as long as it promotes the addition reaction (hydrosilylation reaction of an alkene) between the alkenyl group in the copolymer component (S) and the hydrosilyl group in the hydrosilyl group-containing compound (Y). Platinum catalysts for hydrosilylation crosslinking are widely used for the hydrosilylation crosslinking reaction, which involves the addition of silicon-bonded hydrogen atoms to carbon-carbon double bonds. The platinum catalyst may be contained alone or in combination of two or more.

[0072] Examples of platinum catalysts include platinum itself (platinum black), chloroplatinic acid, platinum-olefin complexes, platinum-alcohol complexes, and platinum supported on a carrier such as alumina or silica.

[0073] Examples of platinum-based catalysts include the fine powder metal platinum catalysts described in U.S. Pat. No. 2,970,150 and the like, the chloroplatinic acid catalysts described in U.S. Pat. No. 2,823,218 and the like, the complex compounds of platinum and hydrocarbons described in U.S. Pat. Nos. 3,159,601 and 159,662 and the like, the complex compounds of chloroplatinic acid and olefins described in U.S. Pat. No. 3,516,946 and the like, and the complex compounds of platinum and vinylsiloxanes described in U.S. Pat. Nos. 3,775,452 and 3,814,780 and the like.

[0074] Specific examples of platinum catalysts include platinum itself (platinum black); platinum complexes such as chloroplatinic acid, platinum-hydrocarbon complexes, platinum-vinylsiloxane complexes, platinum-alcohol complexes, chloroplatinic acid-olefin complexes, and chloroplatinic acid-vinylsiloxane complexes. Among these, platinum-vinylsiloxane complexes are preferred due to their high catalytic activity. Examples of platinum-vinylsiloxane complexes include 1,1,3,3-tetramethyl-1,3-divinyldisiloxane platinum complexes. The platinum-based catalyst may be supported on a carrier such as alumina or silica.

[0075] In the present composition, the amount of the platinum catalyst blended per 100 parts by mass of the copolymer (S) is preferably 0.00001 to 0.03 parts by mass, more preferably 0.0001 to 0.15 parts by mass, still more preferably 0.0005 to 0.09 parts by mass, and particularly preferably 0.001 to 0.03 parts by mass.

[0076] <Reaction inhibitor> The reaction inhibitor, one of the components of this composition, is a compound that has the function of suppressing the crosslinking reaction (hydrosilylation addition reaction to alkene) between the alkenyl groups of the copolymer (S) and the hydrosilyl groups of the hydrosilyl group-containing compound (Y). The addition of a reaction inhibitor is preferable in that it stabilizes the processability of the composition during kneading and molding. The reaction inhibitor may be contained alone or in combination of two or more kinds.

[0077] Specific examples of the reaction inhibitor include benzotriazole; acetylene alcohols such as 1-hexyn-3-ol, 3-methyl-1-butyn-3-ol, 3,6-dimethyl-4-octyne-3,6-diol, 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 1-ethynylcyclohexanol, and 3,5-dimethyl-1-hexyn-3-ol; acrylonitrile; amide compounds such as N,N-diallylacetamide, N,N-diallylbenzamide, N,N,N',N'-tetraallyl-o-phthalic acid diamide, N,N,N',N'-tetraallyl-m-phthalic acid diamide, and N,N,N',N'-tetraallyl-p-phthalic acid diamide; and others, sulfur, phosphorus, nitrogen, amine compounds, sulfur compounds, phosphorus compounds, tin, tin compounds, and tetramethyltetravinylcyclotetrasiloxane. Among these compounds, 3,5-dimethyl-1-hexyn-3-ol is particularly preferred.

[0078] In the present composition, the amount of the reaction inhibitor blended per 100 parts by mass of the copolymer (S) is preferably 0.05 to 5 parts by mass, more preferably 0.08 to 4 parts by mass, even more preferably 0.1 to 3 parts by mass, and particularly preferably 0.2 to 1.0 part by mass.

[0079] <Organic peroxide (Z)> The organic peroxide (Z), which is one of the components of the present composition, is a type of crosslinking agent. Specific examples of the organic peroxide (Z) include dicumyl peroxide (DCP), di-tert-butyl peroxide, 2,5-di-(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexyne-3, 1,3-bis(tert-butylperoxyisopropyl)benzene, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, n-butyl-4,4-bis(tert-butylperoxy)valerate, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, tert-butyl peroxybenzoate, tert-butylperoxyisopropyl carbonate, diacetyl peroxide, lauroyl peroxide, and tert-butylcumyl peroxide.

[0080] The organic peroxide (Z) is preferably one whose decomposition products produced during crosslinking are low molecular weight compounds with sufficiently high vapor pressures, since the use of such organic peroxide (Z) makes it difficult for odors to remain in the resulting crosslinked molded article.

[0081] In the present composition, the amount of organic peroxide (Z) blended per 100 parts by mass of copolymer (S) is preferably 0.1 to 8 parts by mass, more preferably 0.2 to 5 parts by mass, and even more preferably 0.3 to 2.0 parts by mass. When the amount of organic peroxide (Z) blended is within the above range, there is no blooming on the surface of the obtained molded article, and the copolymer composition exhibits excellent crosslinking properties.

[0082] The total amount of the hydrosilyl group-containing compound (Y) and the organic peroxide (Z) relative to 100 parts by mass of the copolymer (S) is preferably 0.2 to 108 parts by mass, more preferably 0.7 to 55 parts by mass, and even more preferably 1.3 to 12 parts by mass. The mass ratio [Y / Z] of the blending amounts of the hydrosilyl group-containing compound (Y) and the organic peroxide (Z) is preferably 23 / 77 to 99 / 1, more preferably 47 / 53 to 97 / 3, and even more preferably 60 / 40 to 95 / 5.

[0083] <Hydrophobic silica> The hydrophobic silica, which is one of the components of the composition, is a type of filler. The inclusion of hydrophobic silica improves the elongation of the copolymer composition, thereby improving mold release properties and improving the physical properties of the resulting molded article, such as tensile stress at break, tensile elongation at break, and abrasion resistance.

[0084] Hydrophobic silica is silica particles whose surface has been treated with a hydrophobizing agent, such as organosilicon compounds such as methyltrichlorosilane, dimethyldichlorosilane, hexamethyldisilazane, hexamethylcyclotrisiloxane, and octamethylcyclotetrasiloxane.

[0085] Examples of commercially available hydrophobic silica include AEROSIL (registered trademark) R972, R974, R9200, R976, R976S, RX50, NAX50, NX90G, NX90S, RX200, RX300, R8200, R812, R812S, RY50, RY51, NY50, RY200S, R202, RY200, RY200L, RY300, NA50H, NA50Y, REA90, and RA200 manufactured by EVONIK. H, RA200HS, REA200, R805, RM50, R711, R7200, CAB-O-SIL (registered trademark) TS-610, TS-612, TS-620, TS-622, Tg-709F manufactured by Cabot Corporation, HDK (registered trademark) H15, H18, H20, H30 (manufactured by Wacker Asahi Kasei Silicones Co., Ltd.), and Reolosil (registered trademark) manufactured by Tokuyama Corporation.

[0086] The average particle size of the hydrophobic silica is preferably 1 to 50 nm, more preferably 2 to 45 nm, even more preferably 5 to 40 nm, and particularly preferably 8 to 20 nm. When the average particle size is within the above range, the dispersibility of the hydrophobic silica in the composition is excellent. In addition, the specific surface area (BED method) of the hydrophobic silica is preferably 50 m 2 / g or more, more preferably 100 to 400m 2 / g, more preferably 150 to 300m 2 / g.

[0087] In the present composition, the amount of hydrophobic silica blended per 100 parts by mass of copolymer (S) is 30 to 200 parts by mass, more preferably 35 to 150 parts by mass, even more preferably 40 to 100 parts by mass, and particularly preferably 45 to 80 parts by mass.

[0088] <Softener> The softener, which is one of the components of the present composition, can be a softener (plasticizer) commonly used for rubber. The softener may be obtained from a fossil fuel-derived raw material or from an animal or vegetable source. Specific examples include petroleum-based plasticizers such as process oil, lubricating oil, paraffin oil, liquid paraffin, petroleum asphalt, and petrolatum; coal tar-based plasticizers such as coal tar and coal tar pitch; fatty oil-based plasticizers such as castor oil, linseed oil, rapeseed oil, soybean oil, and palm oil; tall oil; factice; waxes such as beeswax, carnauba wax, and lanolin; fatty acids and fatty acid salts such as ricinoleic acid, palmitic acid, stearic acid, barium stearate, calcium stearate, and zinc laurate; naphthenic acid; and pineapple. Examples of suitable plasticizers include oil, rosin or derivatives thereof; synthetic polymeric substances such as terpene resin, petroleum resin, and coumarone-indene resin; ester-based plasticizers such as dioctyl phthalate, dioctyl adipate, and dioctyl sebacate; microcrystalline wax, liquid polybutadiene, modified liquid polybutadine, liquid thiokol, and hydrocarbon-based synthetic lubricating oils. Of these, petroleum-based plasticizers, particularly process oils such as paraffin-based process oil and naphthene-based process oil, are preferred, with paraffin-based process oil being more preferred.

[0089] In the present composition, the amount of the softener to be blended per 100 parts by mass of copolymer (S) is preferably in the range of 75 to 120 parts by mass, more preferably 80 to 115 parts by mass, even more preferably 85 to 110 parts by mass, and particularly preferably 90 to 105 parts by mass. When the amount of the softener to be blended is within the above range, a copolymer composition can be obtained which has little tack and is excellent in processability, heat aging resistance, mechanical properties, etc.

[0090] <Other ingredients> The composition may contain other components depending on the purpose, for example, at least one selected from resins other than copolymer (S), carbon black, crosslinking aids, antioxidants, vulcanization accelerators, vulcanization aids, fillers, processing aids, activators, moisture absorbents, foaming agents, foaming aids, heat stabilizers, weather stabilizers, antistatic agents, colorants, lubricants, thickeners, and tackifiers. Each of these other components may be used alone, or two or more may be used in combination.

[0091] <Resins other than copolymer (S)> The present composition may contain a resin other than the copolymer (S). The resin other than the copolymer (S) may be contained alone or in combination of two or more.

[0092] Resins other than copolymer (S) include general-purpose resins such as polyethylene, polypropylene, and polystyrene; and rubbers such as silicone rubber, ethylene-propylene random copolymer rubber (EPR), natural rubber, styrene-butadiene rubber, isoprene rubber, butadiene rubber, and chloroprene rubber.

[0093] The resin other than the copolymer (S) is preferably a crystalline olefin polymer, which is a crystalline homopolymer or copolymer of an α-olefin having 2 to 20 carbon atoms. In the present invention, a crystalline polymer is a polymer having a melting point.

[0094] Specific examples of the α-olefin constituting the crystalline olefin polymer include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 3-methyl-1-pentene, 4-methyl-1-pentene, and 5-methyl-1-hexene. The crystalline olefin polymers may be used alone or in combination of two or more kinds.

[0095] Specific examples of crystalline olefin polymers include the following (co)polymers: In these (co)polymers, "mol %" refers to the proportion when the total of all monomers is 100 mol %. (1) Ethylene-based polymers such as ethylene homopolymers and copolymers of ethylene with 10 mol% or less of other α-olefins having 3 to 20 carbon atoms or vinyl monomers such as vinyl acetate and ethyl acrylate. More specifically, high-pressure low-density polyethylene (HP-LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene, high-density polyethylene (HDPE), ethylene-vinyl acetate copolymer (EVA), ethylene-acrylic acid copolymer, etc. (2) Propylene-based polymers such as propylene homopolymers, random copolymers of propylene with 10 mol% or less of other α-olefins having 2 or 4 to 20 carbon atoms, and block copolymers of propylene with 30 mol% or less of other α-olefins. These propylene-based polymers are generally also called homo-, random-, or block-type polypropylenes. (3) 1-butene polymers such as homopolymers of 1-butene and random copolymers of 1-butene with 10 mol % or less of other α-olefins having 2 to 3 carbon atoms or 5 to 20 carbon atoms. (4) 4-methyl-1-pentene polymers such as homopolymers of 4-methyl-1-pentene and random copolymers of 4-methyl-1-pentene with 20 mol % or less of other α-olefins. Among the crystalline olefin polymers, the ethylene polymers (1) above are preferred, and linear low-density polyethylene (LLDPE) is particularly preferred.

[0096] The MFR of resins other than copolymer (S) at 190°C and 2.16 kg, measured in accordance with JIS K7210: 1999, is preferably 0.1 to 100 g / 10 min, more preferably 0.5 to 80 g / 10 min. When the MFR is within the above range, a copolymer composition having a small mold shrinkage and excellent processability can be obtained.

[0097] When the composition contains a resin other than copolymer (S), the content thereof is preferably 1 to 50 parts by mass, more preferably 5 to 30 parts by mass, and even more preferably 7 to 20 parts by mass, per 100 parts by mass of copolymer (S). Within this range, the hardness of a molded article formed from the composition can be adjusted, and the compound viscosity at processing temperatures can be reduced, thereby further improving processability. In addition, the composition can be handled as a thermoplastic elastomer, which broadens the range of handling and kneading techniques.

[0098] <Carbon black> The composition preferably contains carbon black, which improves the injection moldability and mold releasability of the copolymer composition and also makes it possible to obtain a crosslinked molded article having improved mechanical properties such as tensile strength, tear strength, and abrasion resistance. The carbon black may be contained alone or in combination of two or more kinds.

[0099] Examples of carbon black include SRF, GPF, FEF, MAF, HAF, ISAF, SAF, FT, and MT. The surface of the carbon black may be treated with a silane coupling agent. Examples of commercially available carbon black include those sold under the trade names "Asahi #55G," "Asahi #50HG," "Asahi #60G," "Asahi #60UG," and "Asahi #70" (manufactured by Asahi Carbon Co., Ltd.), and those sold under the trade names "Seast SVH," "Seast V," and "Seast G-SO" (manufactured by Tokai Carbon Co., Ltd.).

[0100] When the composition contains carbon black, the amount of carbon black is preferably 1 to 70 parts by mass, more preferably 2 to 50 parts by mass, even more preferably 3 to 30 parts by mass, and particularly preferably 4 to 15 parts by mass, per 100 parts by mass of copolymer (S). When the amount of carbon black is within the above range, a copolymer composition excellent in dynamic magnification (dynamic modulus / static modulus), processability, mechanical properties (particularly, tensile strength at break), etc. can be obtained.

[0101] <Crosslinking aid> In addition to the organic peroxide (Z), the present composition preferably contains a crosslinking aid. Examples of crosslinking aids include sulfur; quinone dioxime crosslinking aids such as p-quinone dioxime; acrylic crosslinking aids such as ethylene glycol dimethacrylate and trimethylolpropane trimethacrylate; allyl crosslinking aids such as diallyl phthalate and triallyl isocyanurate; maleimide crosslinking aids; divinylbenzene; zinc oxide (e.g., ZnO#1 / zinc oxide type 2 (compliant with JIS K 1410) (manufactured by Hakusui Tech Co., Ltd.) and activated zinc oxide "META-Z102" (manufactured by Inoue Lime Industry Co., Ltd.)); and metal oxides such as magnesium oxide.

[0102] When the present composition contains a crosslinking aid, the amount of the crosslinking aid added is usually 0.5 to 10 mol, preferably 0.5 to 7 mol, more preferably 1 to 6 mol, per 1 mol of the organic peroxide (Z).

[0103] <Anti-aging agent> The composition may contain an antioxidant. Examples of the antioxidant include conventionally known antioxidants, such as amine-based antioxidants, phenol-based antioxidants, and sulfur-based antioxidants. In order to maintain heat aging resistance for a long period of time at high temperatures, it is preferable to use two or more of these antioxidants in combination.

[0104] Specifically, aromatic secondary amine antioxidants such as phenylbutylamine, N,N-di-2-naphthyl-p-phenylenediamine, and 4,4'-bis(α,α-dimethylbenzyl)diphenylamine (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., trade name: Nocrac CD); amine antioxidants such as 2,2,4-trimethyl-1,2-dihydroquinoline polymers; phenolic antioxidants such as dibutylhydroxytoluene and tetrakis[methylene(3,5-di-t-butyl-4-hydroxy)hydrocinnamate]methane; thioether-based antioxidants such as bis[2-methyl-4-(3-n-alkylthiopropionyloxy)-5-tert-butylphenyl]sulfide; dithiocarbamate-based antioxidants such as nickel dibutyldithiocarbamate; and sulfur-based antioxidants such as 2-mercaptobenzoylimidazole, 2-mercaptobenzimidazole, zinc salt of 2-mercaptobenzimidazole, dilauryl thiodipropionate, and distearyl thiodipropionate.

[0105] When the composition contains an antioxidant, the amount of the antioxidant is preferably 0.1 to 10 parts by mass, more preferably 0.2 to 5.0 parts by mass, even more preferably 0.3 to 3.0 parts by mass, and particularly preferably 0.4 to 1.0 parts by mass, per 100 parts by mass of copolymer (S). By adjusting the amount within this range, blooming on the surface of a crosslinked molded article obtained from the copolymer composition can be suppressed, and further, crosslinking inhibition can be suppressed.

[0106] Filler The composition may contain a filler to improve physical properties such as tensile stress at break and tensile elongation at break, or to reduce compounding costs. Examples of fillers include hydrophilic silica, calcium carbonate, activated calcium carbonate, light calcium carbonate, heavy calcium carbonate, talc, fine talc powder, fine silicic acid powder, and clay. Of these, hydrophilic silica and talc are preferred. The inclusion of hydrophilic silica improves the elongation of the copolymer composition, thereby improving its releasability from a mold.

[0107] When the composition contains a filler, the amount of the filler is preferably 1 to 500 parts by mass, more preferably 5 to 300 parts by mass, even more preferably 10 to 100 parts by mass, and particularly preferably 20 to 50 parts by mass, per 100 parts by mass of the copolymer (S). When the amount of the filler is within the above range, the mechanical properties such as tensile strength, tear strength, and abrasion resistance of the resulting molded article can be improved.

[0108] Hydrophilic silica refers to silica that does not have hydrophobic groups on its surface, and typically includes known dry silica, wet silica, etc. that are commonly used in the rubber industry. Examples of commercially available hydrophilic silica include Nipsil ER (registered trademark) (manufactured by Tosoh Silica Corporation).

[0109] When the present composition contains hydrophilic silica as a filler, the amount of hydrophilic silica blended is preferably 10 to 80 parts by mass, more preferably 15 to 60 parts by mass, per 100 parts by mass of copolymer (S).

[0110] <Moisture absorbent> Examples of moisture absorbents include calcium oxide, silica gel, sodium sulfate, molecular sieves, zeolite, and white carbon. When the composition contains a moisture absorbent, the amount of the moisture absorbent blended is preferably 0.5 to 15 parts by mass, more preferably 1.0 to 12 parts by mass, and even more preferably 1.0 to 10 parts by mass, per 100 parts by mass of copolymer (S).

[0111] <Processing aids> As the processing aid, for example, a wide range of processing aids that are generally compounded in rubber can be used. Specific examples of processing aids include fatty acids such as ricinoleic acid, stearic acid, palmitic acid, and lauric acid, fatty acid salts such as barium stearate, zinc stearate, and calcium stearate, esters of the above fatty acids, and organosilicones.

[0112] When the composition contains a processing aid, the amount of processing aid is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, even more preferably 10 parts by mass or less, and particularly preferably 5 parts by mass or less, per 100 parts by mass of copolymer (S). There is no particular lower limit to the amount of processing aid to be added, but it is, for example, 0.5 parts by mass or more per 100 parts by mass of copolymer (S). When the amount of processing aid is within the above range, excellent processability, such as kneading processability, extrusion processability, and injection moldability, is achieved.

[0113] <Activator> Examples of the surfactant include amines such as di-n-butylamine, dicyclohexylamine, and monoelanolamine; surfactants such as diethylene glycol, polyethylene glycol, lecithin, triaryl methylate, and zinc compounds of aliphatic or aromatic carboxylic acids; zinc peroxide preparations; octadecyltrimethylammonium bromide, synthetic hydrotalcite, and special quaternary ammonium compounds.

[0114] When the present composition contains an activator, the amount of the activator to be blended is preferably 0.2 to 15 parts by mass, more preferably 0.3 to 10 parts by mass, and even more preferably 0.5 to 8 parts by mass, per 100 parts by mass of copolymer (S).

[0115] <Foaming agent> The fuel cell gasket or packing formed using the present composition may be a non-foamed or foamed product. When the fuel cell gasket or packing is a foamed product, the present composition preferably contains a foaming agent.

[0116] Examples of blowing agents include physical blowing agents such as carbon dioxide, nitrogen, air, and water; inorganic blowing agents such as sodium bicarbonate (baking soda), sodium carbonate, ammonium bicarbonate, ammonium carbonate, and ammonium nitrite; nitroso compounds such as N,N'-dimethyl-N,N'-dinitrosoterephthalamide and N,N'-dinitrosopentamethylenetetramine (DPT); azodicarbonamide (ADCA), azobisisobutyronitrile, azocyclohexylnitrile, and azodiaminobenzene. Examples of suitable foaming agents include azo compounds such as benzenesulfonyl hydrazide, toluenesulfonyl hydrazide, p,p'-oxybis(benzenesulfonyl hydrazide), diphenylsulfone-3,3'-disulfonyl hydrazide, and 4,4'-oxybisbenzenesulfonyl hydrazide (OBSH); and azide compounds such as calcium azide, 4,4-diphenyldisulfonyl azide, and p-toluenesulfonyl azide. Among these, inorganic foaming agents are preferred, and sodium bicarbonate is more preferred, as they can lower the specific gravity and increase the crosslink density of foamed molded articles.

[0117] When the composition contains a foaming agent, the amount of the foaming agent is appropriately selected depending on the performance required for the fuel cell gasket or packing produced from the composition, but is preferably 0.001 to 10 parts by mass, more preferably 0.005 to 10 parts by mass, even more preferably 0.1 to 10 parts by mass, and particularly preferably 0.2 to 10 parts by mass, per 100 parts by mass of copolymer (S).

[0118] <Foaming aid> If necessary, a foaming aid may be used in combination with the foaming agent. The addition of the foaming aid is effective in adjusting the decomposition temperature of the foaming agent and uniforming the bubbles. Specific examples of the foaming aid include organic acids such as salicylic acid, phthalic acid, stearic acid, and oxalic acid, as well as urea and its derivatives.

[0119] When the present composition contains a foaming aid, the amount of the foaming aid is usually 1 to 100 parts by mass, preferably 2 to 80 parts by mass, per 100 parts by mass of the foaming agent.

[0120] <Method of manufacturing the present composition> This composition can be prepared in the same manner as in the preparation of known general rubber compositions. Specifically, the process is as follows. For example, the copolymer (S), the hydrosilyl group-containing compound (Y), the hydrophobic silica, the softener, and other components as needed are masticated or kneaded (first kneading), and then the resulting masticated or kneaded product is kneaded with the platinum catalyst, the reaction inhibitor, the organic peroxide (Z), and other components as needed (second kneading). The organic peroxide (Z) is preferably added during the second kneading. Specifically, copolymer (S), hydrosilyl group-containing compound (Y), hydrophobic silica, softener, and other components as needed are masticated or kneaded at 130 to 170°C for 1 to 10 minutes, preferably at 130 to 150°C for 3 to 8 minutes (first kneading), and then a platinum catalyst, a reaction inhibitor, an organic peroxide (Z), and other components as needed are added to the resulting masticated or kneaded product, and the mixture is kneaded at 30 to 80°C for 1 to 10 minutes, preferably at 50 to 80°C for 3 to 7 minutes (second kneading), followed by separation. In this way, a copolymer composition in the form of a ribbon or sheet is usually obtained.

[0121] When a reinforcing agent or the like is added, it may be added during either the first kneading or the second kneading, but is preferably added during the first kneading. When other components such as a moisture absorbent, an antioxidant, a filler, a processing aid, an activator, a plasticizer, a thickener, or a tackifier are added, it is preferable to add them during the first kneading, and it is preferable to add a crosslinking aid, a crosslinking accelerator, and a foaming agent during the second kneading.

[0122] The kneading device used in the first kneading may be any known kneading device capable of high-temperature processing. Specific examples include a Banbury mixer, a kneader, an extruder, etc. The kneading device used in the second kneading may be a roll, a kneader, or an extruder, which are easy to control the temperature of.

[0123] By dividing the kneading of each component into the first kneading and the second kneading, the kneading time can be shortened compared to when all components are kneaded without being divided. In addition, since the progress of crosslinking during the first kneading can be suppressed, the temperature during the first kneading can be increased, and moisture can be removed in a shorter time.

[0124] [Crosslinked molded product] The crosslinked molded article of the present invention (hereinafter also referred to as "the molded article") is obtained by crosslinking the present composition. The present molded article can be obtained by preforming the present composition into a desired shape by molding using various molding machines such as an extruder, a calendar roll, a press molding machine, an injection molding machine, or a transfer molding machine, and then introducing the molded article into a crosslinking tank and heating it to crosslink it, either simultaneously with molding. If the present composition contains a foaming agent, foaming will proceed along with crosslinking, resulting in a foamed crosslinked molded article (foamed molded article).

[0125] Any known heating method can be used without limitation, but it is particularly preferred to heat at a temperature of 150 to 200°C for 1 to 30 minutes using a heating bath such as a far-infrared heating furnace, hot air, a glass bead fluidized bed, UHF (ultra-high frequency electromagnetic waves), steam, or LCM (molten salt bath). Molding and crosslinking may or may not require the use of a mold. When a mold is not used, the rubber composition is usually molded and crosslinked continuously.

[0126] It is also preferable to press-mold the composition to perform primary crosslinking, remove the composition from the mold to obtain a primary molded article, and then subject the resulting primary molded article to secondary crosslinking in a heat medium. Specifically, the composition is press-molded at 120 to 200°C for 1 to 20 minutes, preferably 150 to 200°C for 10 to 18 minutes, to perform primary crosslinking, and then remove the composition from the mold to obtain a primary molded article. The resulting primary molded article is then subjected to secondary crosslinking in a heat medium at 120 to 160°C for 10 to 24 hours, preferably 140 to 160°C for 15 to 20 minutes. Examples of heat mediums used for secondary crosslinking include air, steam, paraffin-based process oil, and molten salt.

[0127] When primary crosslinking is performed by press molding, the crosslinked body does not become hot due to shear heating. This makes it possible to suppress the generation of low molecular weight siloxanes and polymer degradation. Furthermore, when press molding is performed in a sealed state, a certain amount of low molecular weight siloxanes are generated and remain inside the crosslinked body. However, by subsequently performing secondary crosslinking in a heat medium, the low molecular weight siloxanes are volatilized, making it possible to obtain a crosslinked body with a low amount of low molecular weight siloxanes.

[0128] The hardness (Durometer-A, according to JIS K 6253-3:2012) of the present molded product is preferably not more than 60, more preferably not more than 50, and even more preferably not more than 45. Specifically, the hardness (Durometer-A) of the present molded product is a value measured by the method described in the examples below. Even though the hardness (Durometer-A) of the present molded article is in the range generally considered to be low as described above, it has superior mechanical strength (tensile stress at break) and elongation (tensile elongation at break) compared to crosslinked molded articles obtained from conventional rubber compositions.

[0129] Specific applications of the molded article include grommets, tire rubber, O-rings, industrial rolls, packing (e.g., condenser packing), gaskets, belts (e.g., heat insulation belts, copier belts), hoses (e.g., water hoses, brake reservoir hoses, radiator hoses), waterproof rubber, sponges (e.g., weatherstrip sponges, heat insulation sponges, protect sponges, micro-foam sponges), cables (ignition cables, cab tire cables, high-tension cables), electric wire coating materials (high-voltage wire coating materials, low-voltage electric wire coating materials, marine electric wire coating materials), glass run channels, color skin materials, paper feed rolls, roofing sheets, all-solid-state batteries, etc. In particular, component units such as grommets are desired to have low hardness, particularly for the purpose of reducing weight, in order to provide products with a wide range of hardness variations, and therefore the present molded body can be suitably used as a grommet.

[0130] A method for producing a grommet from the present composition includes, for example, molding the present composition into a desired grommet shape, followed by crosslinking the composition (uncrosslinked molded article) simultaneously with molding. The molding can be carried out using an extrusion molding machine, a calendar roll, a press molding machine, an injection molding machine, a transfer molding machine, or the like. [Example]

[0131] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples. Unless otherwise specified, "parts" means "parts by mass."

[0132] The physical properties of each copolymer used in the examples and comparative examples were measured as follows. (1) Mass fraction (mass%) and mole number (mol%) of constituent units The mass fraction (mass%) of each structural unit in the copolymer and the number of moles (mol%) of each structural unit are: 13 The measurements were obtained by C-NMR using an ECX400P nuclear magnetic resonance spectrometer (manufactured by JEOL Ltd.), with a measurement temperature of 120°C, a measurement solvent of orthodichlorobenzene / deuterated benzene = 4 / 1, and an accumulation number of 8000. 13 The C-NMR spectrum was obtained.

[0133] (2) Intrinsic viscosity [η] The intrinsic viscosity [η] (dl / g) of the copolymer was measured using a fully automatic intrinsic viscometer manufactured by Rigo Co., Ltd. at a temperature of 135° C. and in decalin as a measurement solvent.

[0134] (3) Weight average molecular weight (Mw) The weight-average molecular weight (Mw) of the copolymer is a polystyrene-equivalent value measured by 3D-GPC. The measurement equipment and conditions are as follows. The dn / dc value (the differential value dn / dc of refractive index n with respect to concentration c) required to determine the absolute molecular weight was determined for each sample from the dn / dc value of standard polystyrene (molecular weight 190,000) of 0.053 and the response intensity of the differential refractometer per unit injected mass. Apparatus: 3D-high temperature GPC apparatus PL-GPC220 (Polymer Laboratories) Column: TSKgel GMH HR -H(S)HT x 2 + TSKgel GMH HR -M(S)×1 piece (Each piece has an inner diameter of 7.8mm and a length of 300mm) Column temperature: 140℃ Mobile phase: 1,2,4-trichlorobenzene (containing 0.025% BHT) Detector: Differential Refractometer (RI) / GPC device built-in 2-angle light scattering photometer PD2040 type (manufactured by Precison Detectors) Injection volume: 0.5mL Sample concentration: ca 1.0 mg / mL Sample filtration: Filtration through a sintered filter with a pore size of 1.0 μm

[0135] (4) Mooney viscosity ML(1+4) 125℃ The Mooney viscosity ML(1+4)125°C of the copolymer was measured at 125°C using a Mooney viscometer (SMV-301 model manufactured by Shimadzu Corporation) in accordance with JIS K 6300-1:2013.

[0136] (5) Complex viscosity η * and P value The rheometer used was a viscoelasticity measuring device, Ares (manufactured by Rheometric Scientific), and the complex viscosity η was measured at a frequency of ω = 0.01 rad / s under the conditions of 190°C and 1.0% strain. * (ω=0.01) , complex viscosity η at frequency ω=0.1rad / s * (ω=0.1) , complex viscosity η at frequency ω=10 rad / s * (ω=10) and the complex viscosity η at frequency ω = 100 rad / s * (ω=100) (All units are Pa·sec) In addition, from the obtained results, η * (ω=0.1)and η * (ω=100) The P value (η * (ω=0.1) / η * (ω=100) ) was calculated.

[0137] The glass transition temperature (Tg) of the copolymer was measured by DSC (differential scanning calorimeter) under the following conditions. Using a differential scanning calorimeter (RDC220, manufactured by SII Corporation), approximately 10 mg of a sample was heated from 30°C to 200°C at a heating rate of 50°C / min in a nitrogen atmosphere and held at 200°C for 10 minutes. The sample was then cooled to -100°C at a heating rate of 10°C / min, held at -100°C for 5 minutes, and then heated to 200°C at a heating rate of 10°C / min. The temperature at which the glass transition occurred was taken as the glass transition temperature (Tg).

[0138] [Copolymer component (S)] In the following examples and comparative examples, copolymer (S-1) obtained in the following Production Example 1 was used as copolymer (S).

[0139] [Manufacturing Example 1] A 300-L polymerization reactor equipped with a stirring blade was continuously fed with 58.3 L / hr of dehydrated and purified hexane solvent through line 1, and 4.5 mmol / hr of triisobutylaluminum (TiBA), 0.150 mmol / hr of (C6H5)3CB(C6F5)4, and 0.030 mmol / hr of di(p-tolyl)methylene(cyclopentadienyl)(octamethyloctahydrodibenzofluorenyl)zirconium dichloride through line 2. Simultaneously, 6.6 kg / hr of ethylene, 9.3 kg / hr of propylene, 18 L / hr of hydrogen, and 340 g / hr of VNB were continuously fed into the polymerization reactor through separate lines, and copolymerization was carried out under the conditions of a polymerization temperature of 87°C, a total pressure of 1.6 MPaG, and a residence time of 1.0 hour. In this way, a solution containing 20% ​​by mass of ethylene-propylene-VNB copolymer formed from ethylene, propylene, and VNB was obtained. A small amount of methanol was added to the polymerization reaction mixture withdrawn from the bottom of the polymerization reactor to terminate the polymerization reaction. The ethylene-propylene-VNB copolymer was separated from the solvent by steam stripping and then dried under reduced pressure at 80°C overnight. By the above procedure, ethylene-propylene-VNB copolymer (S-1) was obtained. The physical properties of the obtained copolymer (S-1) were measured by the methods described above. The results are shown in Table 1.

[0140] [Table 1]

[0141] [Hydrosilyl group-containing compound (Y)] In the following examples and comparative examples, the compound (Y-1) obtained in the following Production Example 2 was used as the hydrosilyl group-containing compound (Y).

[0142] [Manufacturing Example 2] A reactor was charged with 536 g of methylhydrogenpolysiloxane represented by the following formula (a-1-1), and the mixture was heated to 40°C while stirring under a nitrogen stream. 0.4 g of a toluene solution of platinum-1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane complex (Pt concentration 0.3 wt%) was added, and 265 g of α-methylstyrene was added dropwise while maintaining the reaction temperature at 40 to 90°C.

[0143] [ka]

[0144] After the dropwise addition was completed, stirring was continued for 2 hours at 85°C, and then 0.5 g of the reaction solution was sampled, and the reaction rate of the Si-H group was confirmed to be approximately 36% by an alkali decomposition gas generation method (the remaining Si-H group was decomposed with an ethanol / aqueous solution of KOH, and the reaction rate of the Si-H group was calculated from the volume of the generated hydrogen gas). The reaction solution was then heated to 135°C under reduced pressure for 2 hours to distill off low boiling points, yielding 673 g of crosslinking agent (Y-1), a hydrosilyl group-containing compound. The resulting crosslinking agent (Y-1) was 29 The resulting crosslinking agent (Y-1) was confirmed to be a compound represented by the following formula (a-1) by Si-NMR. The viscosity of the resulting crosslinking agent (Y-1) was measured at 25°C using an Ubbelohde viscometer according to JIS Z 8803. 2 / s.

[0145] [ka]

[0146] In the following examples and comparative examples, the raw materials other than the copolymer (S) and the hydrosilyl group-containing compound (Y) are as follows. Reaction inhibitor: ETCH (1-ethynyl-1-cyclohexanol), manufactured by Nissin Chemical Industry Co., Ltd. Platinum catalyst: SRX212Catalyst manufactured by Dow Toray Industries, Inc. (a product containing 1% by mass or more but less than 3% by mass of 1,1,3,3-tetramethyl-1,3-divinyldisiloxane platinum complex). Organic peroxide (Z): DPC-40C (dicumyl peroxide (40% masterbatch), 1-minute half-life temperature 171°C, 10-hour half-life temperature 117°C, molecular weight 270.37), manufactured by Kayaku Akzo Co., Ltd. Hydrophobic silica: Aerosil R974, manufactured by Nippon Aerosil Co., Ltd. Carbon black: Asahi #60UG, manufactured by Asahi Carbon Co., Ltd. Softener: Idemitsu Kosan Co., Ltd., Diana (registered trademark) Process PS-430 (paraffin-based process oil). Filler: Takehara Chemical Industry Co., Ltd., Hytron A (talc; hydrated magnesium silicate). Processing aid 1: Struktol WB212 (fatty acid ester mixture), manufactured by S&S Japan Co., Ltd. Processing aid 2: Struktol WS280 paste (organosilicone mixture), manufactured by S&S Japan Co., Ltd. Anti-aging agent: Nocrac CD (4,4'-bis(α,α-dimethylbenzyl)diphenylamine), manufactured by Ouchi Shinko Chemical Co., Ltd.

[0147] [Example 1] <<Preparation of Copolymer Composition>> In the first stage, the raw materials shown in Table 2, raw material 1, were mixed at 140°C for 2 minutes using a BB-L1800 Banbury mixer (manufactured by Kobe Steel, Ltd.). After that, the ram was raised and cleaned, and the mixture was mixed for another minute and then discharged at approximately 150°C to obtain the first stage blend. Copolymer (S-1) was prepared by mixing 100 parts of copolymer (S-1) and an oil extender (liquid ethylene-propylene copolymer (kinematic viscosity at 100°C: 2000 mmHg)). 2 15 parts of copolymer (S-1) was used as an oil-extended copolymer (S-1). Next, in the second step, the mixture obtained in the first step was wound around an 8-inch roll (manufactured by Nippon Roll Co., Ltd.; front roll surface temperature 50°C, rear roll surface temperature 50°C, front roll rotation speed 16 rpm, rear roll rotation speed 18 rpm), and the raw material shown in raw material 2 in Table 2 was added thereto and kneaded for 10 minutes to obtain an uncrosslinked copolymer composition.

[0148] <Evaluation of uncrosslinked rubber properties> [Mooney viscosity ML(1+4)100℃] The Mooney viscosity ML(1+4)100°C of the uncrosslinked copolymer composition was measured at 100°C using a Mooney viscometer (SMB-301RT model manufactured by Shimadzu Corporation) in accordance with JIS K 6300-1:2013.

[0149] <Crosslinking (vulcanization) speed evaluation> The following values ​​were determined from the crosslinking curve measured when an uncrosslinked copolymer composition was heated at 170°C for 20 minutes in accordance with JIS K 6300-2:2001. MDR2000 (manufactured by ALPHA TECHNOLOGIES) was used for the measurement. · S'Max (dNm): Maximum torque. · S'Min(dNm): Minimum torque value. · S'Max-Min (dNm): The difference between S'Max and S'Min. ·TS1(min): The time it takes for the torque value to increase by 1dNm from S'Min, based on the start of measurement. · tC10 (min): The time when the torque value of the measurement sample reaches 10%, with the minimum torque value S'Min being 0% and the maximum torque value S'Max being 100%. tC90 (min): The time it takes for the torque value of the measured sample to reach 90%, with the minimum torque value S'Min being 0% and the maximum torque value S'Max being 100%. The smaller the tC90, the faster the vulcanization rate (crosslinking rate). ·MCR: Maximum rate of change of torque in the crosslinking curve.

[0150] <Evaluation of physical properties of vulcanized (crosslinked) products> The uncrosslinked copolymer composition was crosslinked for 10 minutes at 170° C. using a press molding machine to prepare a crosslinked molded sheet having a thickness of 2 mm. The obtained sheet was subjected to a hardness test and a tensile test by the following methods, and the results are shown in Table 2.

[0151] [Hardness test: Hardness (Durometer-A; HA)] The flat portions of six of the resulting cross-linked molded sheets were stacked to form a test piece approximately 12 mm thick, and the hardness (Durometer-A) was measured in accordance with JIS K 6253-3:2012. However, test pieces containing foreign matter, bubbles, or scratches were not used. The dimensions of the test piece's measurement surface were such that measurements could be taken with the tip of the indenter positioned at least 12 mm away from the edge of the test piece. The results are shown in Table 2.

[0152] [Tensile test: tensile stress at break, tensile elongation at break, modulus] The resulting crosslinked sheet was punched out to prepare dumbbell-shaped No. 3 test pieces as described in JIS K 6251:2023. Tensile tests were performed using these test pieces according to the method specified in JIS K 6251 at a temperature of 25°C and a tensile speed of 500 mm / min to measure the tensile stress at break (TB; MPa), tensile elongation at break (EB; %), modulus at 25% elongation (M25; MPa), modulus at 50% elongation (M50; MPa), modulus at 100% elongation (M100; MPa), modulus at 200% elongation (M200; MPa), and modulus at 300% elongation (M300; MPa). The results are shown in Table 2.

[0153] [Examples 2 to 6, Comparative Examples 1 to 4] The same procedure as in Example 1 was carried out, except that raw materials 1 and 2 in Table 2 used in Example 1 were changed to the types and amounts shown in Table 2. The results are shown in Table 2.

[0154] [Table 2]

[0155] As shown in Table 2, the crosslinked molded articles (Examples 1 to 6) obtained from the copolymer compositions using a hydrosilyl group-containing compound (Y) and an organic peroxide (Z) in combination as crosslinking agents had improved tensile stress at break and tensile elongation at break compared to Comparative Examples 1 to 4, which did not use organic peroxide (Z), even when the hardness (Durometer-A) was in a low range (e.g., 60 or less).

Claims

1. a copolymer (S) having structural units derived from ethylene (A), structural units derived from an α-olefin (B) having 3 to 20 carbon atoms, and structural units derived from a non-conjugated polyene (C) containing, in one molecule, two or more partial structures selected from the group consisting of the following formula (I) and the following formula (II); a hydrosilyl group-containing compound (Y) which is an organohydrogenpolysiloxane represented by the following formula (a) and which has at least one silicon-bonded aralkyl group and at least two silicon-bonded hydrogen atoms in the molecule; A platinum-based catalyst; A reaction inhibitor; an organic peroxide (Z); Hydrophobic silica; Softener and Including, A copolymer composition comprising 30 to 200 parts by mass of the hydrophobic silica per 100 parts by mass of the copolymer (S). 【Chemistry 1】 (In formula (a), n and p are each independently 0 or a positive number, m is a number ranging from 1 to 20, and the sum of n, m, and p is 5 to 50. １ and R ２ are each independently a monovalent alkyl group, and a plurality of R １ and R ２ may be the same or different. ａ is an aralkyl group, and R is R １ , R ２ , a hydrogen atom, and R ａ and the two R's may be the same or different. However, when n=1, at least one of R's is a hydrogen atom, and when n=0, both R's are hydrogen atoms.

2. The copolymer composition according to claim 1, wherein the copolymer (S) satisfies one or more requirements selected from the following requirements (1) to (5): (1) The ratio [A] / [B] of the number of moles of structural units derived from ethylene (A) to the number of moles [B] of structural units derived from an α-olefin having 3 to 20 carbon atoms is 40 / 60 to 99.9 / 0.1; (2) The mass fraction (mass %) of the structural units derived from the non-conjugated polyene (C) is 0.07 to 10 mass % based on the total structural units constituting the copolymer (S); (3) The weight average molecular weight (Mw), the mass fraction of the constituent unit derived from the non-conjugated polyene (C) (mass fraction (mass%) of (C)), and the molecular weight of the non-conjugated polyene (C) (molecular weight of (C)) satisfy the following formula (i): 4.5≦Mw×mass fraction of (C) / 100 / molecular weight of (C)≦80 (i) (4) Complex viscosity η at a frequency ω = 0.1 rad / s obtained by linear viscoelasticity measurement (190 °C) using a rheometer ＊ (ω=0.1) (Pa·sec) and the complex viscosity η at a frequency ω=100 rad / s ＊ (ω=100) (Pa sec) ＊ (ω=0.1) / η ＊ (ω=100), the intrinsic viscosity [η], and the mass fraction of the structural unit derived from the non-conjugated polyene (C) satisfy the following formula (ii): P / ([η] 2.9 ) ≦ weight fraction of (C) × 6 (ii) (5) Complex viscosity η* at a frequency of ω = 0.01 rad / sec obtained by linear viscoelasticity measurement (190 ° C) using a rheometer (ω=0.01) (Pa sec) and the complex viscosity η* at a frequency ω = 10 rad / sec (ω=10) (Pa sec) and the apparent iodine value derived from the non-conjugated polyene (C) satisfy the following formula (iii): Log [η* (ω=0.01) ] / Log[η* (ω=10) ]≦0.0753×{apparent iodine value derived from non-conjugated polyene (C)}+1.42 ... (iii)

3. 2. The copolymer composition according to claim 1, wherein the α-olefin (B) having 3 to 20 carbon atoms is propylene.

4. The copolymer composition of claim 1, wherein the non-conjugated polyene (C) comprises 5-vinyl-2-norbornene (VNB).

5. 2. The copolymer composition according to claim 1, wherein the copolymer (S) consists solely of an ethylene-propylene-VNB copolymer.

6. It also contains carbon black, The copolymer composition according to claim 1, comprising 1 to 70 parts by mass of the carbon black per 100 parts by mass of the copolymer (S).

7. 10. The copolymer composition of claim 1, wherein the softening agent is a paraffinic processing oil.

8. The copolymer composition according to claim 1, comprising 75 to 120 parts by mass of the softener per 100 parts by mass of the copolymer (S).

9. The copolymer composition according to claim 1, wherein a test piece obtained by stacking six 2 mm thick crosslinked molded sheets obtained by crosslinking the copolymer composition has a hardness (Durometer-A) of 60 or less as measured in accordance with JIS K 6253-3:2012.

10. A crosslinked molded article obtained by crosslinking the copolymer composition according to any one of claims 1 to 9.

11. A grommet comprising the crosslinked molded article according to claim 10.

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