Copolymer composition for sealing component and use thereof

Abstract

To obtain a copolymer composition for a sealing component suitable for a sealing material having good compression set.SOLUTION: A copolymer composition for a sealing component satisfies a specific requirement and comprises: (A) an ethylene / α-olefin / non-conjugated polyene copolymer (A) having a constitutional unit derived from ethylene [A1], a constitutional unit derived from an α-olefin [A2] having 4 to 20 carbon atoms, and a constitutional unit derived from a non-conjugated polyene [A3]; (B) 0.1-200 pts.mass of carbon black per 100 pts.mass of the copolymer (A); and (C) 0.1-100 pts.mass of at least one liquid rubber selected from a liquid polyisoprene having an average molecular weight (Mn) of 1,000 to 100,000 and a liquid polybutadiene.SELECTED DRAWING: None

Description

[Technical field]

[0001] 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 widely used in applications such as automotive parts, electric wire materials, electronic and electrical parts, building and civil engineering materials, and industrial parts.

[0002] It is known that a rubber molded article for sealing is obtained by using EPDM (for example, Patent Document 1). Seal packings, which are rubber molded articles for sealing, are used for various purposes such as automobiles, industrial machines, and electronic parts, but since automobiles and industrial machines are also used in cold regions, the seal packings are required to have low-temperature properties in addition to mechanical strength at room temperature.

[0003] Furthermore, Patent Document 2 proposes an ethylene copolymer composition for fuel cell gaskets capable of forming a seal packing that combines low-temperature properties and mechanical strength (strength and elongation), the composition containing an ethylene-α-olefin-non-conjugated polyene copolymer including a structural unit derived from ethylene [A] having a B value of 1.20 or more, a structural unit derived from an α-olefin [B] having 4 to 20 carbon atoms, and a structural unit derived from a non-conjugated polyene [C].

[0004] On the other hand, sealing materials such as seal packings are constantly subjected to load (stress), and there is a demand for sealing materials with better compression set. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2000 / 59962 [Patent Document 2] JP 2017-075293 A Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to obtain a copolymer composition for sealing parts which is suitable for a sealing material having good compression set. [Means for solving the problem]

[0007] The present invention relates to the following [1] to [5]. [1] A copolymer composition for a sealing part, comprising: an ethylene-α-olefin-non-conjugated polyene copolymer (A) having a structural unit derived from ethylene [A1], a structural unit derived from an α-olefin [A2] having 4 to 20 carbon atoms, and a structural unit derived from a non-conjugated polyene [A3], which satisfy the following requirements (1) to (3); 0.1 to 200 parts by mass of carbon black (B); and 0.1 to 100 parts by mass of at least one liquid rubber (C) selected from liquid polyisoprene and liquid polybutadiene, each having an average molecular weight (Mn) of 1,000 to 100,000, per 100 parts by mass of the copolymer (A). (1) the molar ratio [[A1] / [A2]] of the structural unit derived from ethylene [A1] to the structural unit derived from an α-olefin having 4 to 20 carbon atoms is 40 / 60 to 90 / 10; (2) the content of structural units derived from the non-conjugated polyene [A3] is 0.1 to 6.0 mol % relative to 100 mol % of the total of the structural units derived from [A1], [A2] and [A3]; (3) The B value represented by the following formula (i) is 1.20 or more.

[0008] B value=([EX]+2[Y]) / [2×[E]×([X]+[Y])]···(i) [Here, [E], [X] and [Y] respectively represent the molar fractions of structural units derived from ethylene [A1], α-olefins [A2] having 4 to 20 carbon atoms, and non-conjugated polyenes [A3], and [EX] represents the ethylene [A1]-α-olefins [A2] having 4 to 20 carbon atoms dyad chain fraction.] [2] 2. The copolymer composition for sealing parts according to claim 1, wherein the α-olefin having 4 to 20 carbon atoms constituting the copolymer (A) is 1-butene. [3] The copolymer composition for sealing parts according to item [1] or [2], wherein the non-conjugated polyene [A3] constituting the copolymer (A) is 5-ethylidene-2-norbornene (ENB). [4] The copolymer composition for sealing parts according to any one of items [1] to [3], wherein the copolymer (A) further satisfies the following requirement (4): (4) The Mooney viscosity at 125°C, ML(1+4)125°C, is 5 to 100. [5] A seal part comprising the copolymer composition for seal parts according to any one of items [1] to [4]. Effect of the Invention

[0009] The copolymer composition for sealing parts of the present invention has good low-temperature properties such as low-temperature flexibility and good compression set, and therefore can be used to provide sealing parts such as sealing materials. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] ≪Ethylene-α-olefin-non-conjugated polyene copolymer (A)≫ The ethylene-α-olefin-non-conjugated polyene copolymer (A), which is one of the components constituting the copolymer composition for sealing parts of the present invention (hereinafter, sometimes abbreviated as "copolymer (A)"), is a copolymer having a structural unit derived from ethylene [A1], a structural unit derived from an α-olefin having 4 to 20 carbon atoms [A2], and a structural unit derived from a non-conjugated polyene [A3], which satisfies the following requirements (1) to (3).

[0011] Requirement (1) The copolymer (A) has a molar ratio [[A1] / [A2]] of structural units derived from ethylene [A1] to structural units derived from an α-olefin [A2] having 4 to 20 carbon atoms of 40 / 60 to 90 / 10. The ethylene-based copolymer (L) having a molar ratio within the above range has an excellent balance between rubber elasticity at low temperatures and tensile strength at room temperature.

[0012] The lower limit of [A1] / [A2] is preferably 45 / 55, more preferably 50 / 50, and particularly preferably 55 / 45. The upper limit of [A1] / [A2] is preferably 80 / 20, more preferably 75 / 25, and even more preferably 70 / 30.

[0013] Examples of the α-olefins [A2] having 4 to 20 carbon atoms include linear α-olefins such as 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-nonadecene, and 1-eicosene; and side chain-containing α-olefins such as 4-methyl-1-pentene, 9-methyl-1-decene, 11-methyl-1-dodecene, and 12-ethyl-1-tetradecene. Among these, α-olefins having 4 to 10 carbon atoms are preferred, with 1-butene, 1-hexene, and 1-octene being more preferred, and 1-butene being even more preferred.

[0014] The α-olefins [A2] having 4 to 20 carbon atoms can be used alone or in combination of two or more kinds. A sealant obtained from a copolymer composition for sealing parts containing an ethylene-propylene-non-conjugated polyene copolymer in which the α-olefin is propylene may have poor sealing properties.

[0015] Requirement (2) The content of the structural unit derived from the non-conjugated polyene [A3] in the copolymer (A) is 0.1 to 6.0 mol % relative to 100 mol % of the total of the structural units derived from the [A1], the [A2] and the [A3]. The copolymer (A) having this content in the above range has sufficient crosslinkability and flexibility.

[0016] The lower limit of the content of the structural unit derived from [A3] is preferably 0.5 mol %. The upper limit of the content of the structural unit derived from [A3] is preferably 4.0 mol %, more preferably 3.5 mol %, and further preferably 3.0 mol %. When the content of the structural unit derived from the non-conjugated polyene [A3] is within the above range, a copolymer (A) having sufficient crosslinkability and flexibility can be obtained.

[0017] Examples of the non-conjugated polyenes [A3] include linear non-conjugated dienes such as 1,4-hexadiene, 1,6-octadiene, 2-methyl-1,5-hexadiene, 6-methyl-1,5-heptadiene, and 7-methyl-1,6-octadiene; cyclohexadiene, dicyclopentadiene, methyltetrahydroindene, 5-vinyl-2-norbornene, 5-ethylidene-2-norbornene, 5-methylene-2-norbornene, and 5-isopropylidene-2-norbornene. cyclic non-conjugated dienes such as norbornene and 6-chloromethyl-5-isopropenyl-2-norbornene; and trienes such as 2,3-diisopropylidene-5-norbornene, 2-ethylidene-3-isopropylidene-5-norbornene, 2-propenyl-2,5-norbornadiene, 1,3,7-octatriene, 1,4,9-decatriene, 4,8-dimethyl-1,4,8-decatriene, and 4-ethylidene-8-methyl-1,7-nonadiene. Among these, preferred are linear non-conjugated dienes such as 1,4-hexadiene, and cyclic non-conjugated dienes such as 5-ethylidene-2-norbornene and 5-vinyl-2-norbornene, more preferred are cyclic non-conjugated dienes, and even more preferred are 5-ethylidene-2-norbornene and 5-vinyl-2-norbornene. The non-conjugated polyenes [A3] can be used alone or in combination of two or more kinds.

[0018] Examples of the copolymer (A) include ethylene-1-butene-1,4-hexadiene copolymer, ethylene-1-pentene-1,4-hexadiene copolymer, ethylene-1-hexene-1,4-hexadiene copolymer, ethylene-1-heptene-1,4-hexadiene copolymer, ethylene-1-octene-1,4-hexadiene copolymer, ethylene-1-nonene-1,4-hexadiene copolymer, ethylene-1-decene-1,4-hexadiene copolymer, ethylene-1-butene-1,4-hexadiene copolymer, -hexadiene copolymer, ethylene-1-butene-5-ethylidene-2-norbornene copolymer, ethylene-1-pentene-5-ethylidene-2-norbornene copolymer, ethylene-1-hexene-5-ethylidene-2-norbornene copolymer, ethylene-1-heptene-5-ethylidene-2-norbornene copolymer, ethylene-1-octene-5-ethylidene-2-norbornene copolymer, ethylene-1-nonene-5-ethylidene-2-norbornene copolymer, ethylene-1-decene-5-ethylidene Ethylene-1-butene-1-octene-5-ethylidene-2-norbornene copolymer, Ethylene-1-butene-5-ethylidene-2-norbornene-5-vinyl-2-norbornene copolymer, Ethylene-1-pentene-5-ethylidene-2-norbornene-5-vinyl-2-norbornene copolymer, Ethylene-1-hexene-5-ethylidene-2-norbornene-5-vinyl-2-norbornene copolymer, Ethylene-1-heptene-5-ethylidene-2-norbornene-5-vinyl-2-norbornene copolymer Examples of such copolymers include ethylene-1-octene-5-ethylidene-2-norbornene-5-vinyl-2-norbornene copolymers, ethylene-1-nonene-5-ethylidene-2-norbornene-5-vinyl-2-norbornene copolymers, ethylene-1-nonene-5-ethylidene-2-norbornene-5-vinyl-2-norbornene copolymers, ethylene-1-decene-5-ethylidene-2-norbornene-5-vinyl-2-norbornene copolymers, and ethylene-1-butene-1-octene-5-ethylidene-2-norbornene-5-vinyl-2-norbornene copolymers.

[0019] The ethylene [A1], the α-olefin [A2] and the non-conjugated polyene [A3] may each be derived from biomass.

[0020] Requirement (3) The copolymer (A) has a B value of 1.20 or more, preferably in the range of 1.20 to 1.80, and particularly preferably 1.22 to 1.40. An ethylene copolymer having a B value of less than 1.20 exhibits a large compression set at low temperatures, and a copolymer composition containing such a copolymer may not provide a sealing material with good sealing properties. Copolymer (A) having a B value of 1.20 or more has high alternation of monomer units constituting the copolymer and low crystallinity, and therefore the seal material obtained from the resulting copolymer composition for sealing parts has excellent sealing properties.

[0021] The B value is an index showing the randomness of the distribution of copolymerized monomer sequences in a copolymer, and [E], [X], [Y], and [EX] in the formula (i) are 13 It can be determined by measuring the C-NMR spectrum and based on the reports of JC Randal [Macromolecules, 15, 353 (1982)] and J. Ray [Macromolecules, 10, 773 (1977)]. On the other hand, the molar amounts of the structural units derived from ethylene [A1], the structural units derived from the α-olefins having 4 to 20 carbon atoms [A2], and the structural units derived from the non-conjugated polyenes [A3] in the above (1) and (2) are 1 It can be determined by intensity measurement using a H-NMR spectrometer.

[0022] The copolymer (A) according to the present invention preferably satisfies the following requirement (4) in addition to the requirements (1) to (3) above.

[0023] Requirement (4) The Mooney viscosity at 125°C ML(1+4)125°C is 5 to 100, preferably 10 to 95, and more preferably 10 to 60. The copolymer (A) having a Mooney viscosity in the above range has good processability and flowability, and also exhibits good post-treatment quality (ribbon handling property) and has excellent rubber physical properties.

[0024] <Production method of ethylene-α-olefin-non-conjugated polyene copolymer (A)> The ethylene-α-olefin-non-conjugated polyene copolymer (A) according to the present invention can be obtained by various known production methods, for example, a conventionally known production method using a metallocene 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 adopted.

[0025] Carbon Black (B) Carbon black (B), which is one of the components of the copolymer composition for seal parts of the present invention, is a component that contributes to improving the mechanical strength, modulus, and abrasion resistance of the sealing material obtained from the copolymer composition for seal parts.

[0026] Examples of carbon black (B) 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 "Asahi #55G", "Asahi #50HG", "Asahi #60G", and "Asahi #60UG" (trade names, manufactured by Asahi Carbon Co., Ltd.), "Seest V", and "Seest SO" (trade names, manufactured by Tokai Carbon Co., Ltd.). The carbon black (B) may be used alone or in combination of two or more kinds.

[0027] Liquid Rubber (C) The liquid rubber (C), which is one of the components of the copolymer composition for sealing parts of the present invention, is at least one type of liquid rubber (C) selected from liquid polyisoprene (C1) and liquid polybutadiene (C2), and has an average molecular weight (Mn) preferably in the range of 1,000 to 100,000, more preferably 2,000 to 90,000, and even more preferably 2,500 to 80,000.

[0028] The average molecular weight (Mn) in the present invention means the number average molecular weight calculated as polystyrene by analysis using gel permeation chromatography (GPC). The liquid rubber (C) may be one type or two or more types of liquid rubbers (C) may be used, and the liquid polyisoprene (C1) and the liquid polybutadiene (C2) may be used in combination.

[0029] Since the copolymer composition for sealing parts of the present invention contains the liquid rubber (C), Liquid polyisoprene (C1) is manufactured and sold, for example, by Kuraray Co., Ltd. under the name of liquid isoprene rubber (L-IR).

[0030] Moreover, the liquid polybutadiene (C2) is manufactured and sold, for example, by Kuraray Co., Ltd. under the name of liquid butadiene rubber (L-BR).

[0031] <Copolymer composition for sealing parts> The copolymer composition for sealing parts of the present invention contains the copolymer (A), and per 100 parts by mass of the copolymer (A), 0.1 to 200 parts by mass, preferably 1 to 180 parts by mass, and more preferably 5 to 160 parts by mass of the carbon black (B), and 0.1 to 100 parts by mass, preferably 1 to 90 parts by mass, and more preferably 5 to 80 parts by mass of the liquid rubber (C).

[0032] The copolymer composition for sealing parts of the present invention contains, in addition to the copolymer (A), the carbon black (B) and the liquid rubber (C) in the above-mentioned ranges, and therefore has improved processability, low-temperature properties such as low-temperature flexibility, and compression set, and further, sealing parts obtained from this copolymer composition have improved low-temperature properties such as low-temperature flexibility, and compression set.

[0033] The copolymer composition for sealing parts of the present invention preferably further contains a crosslinking agent in addition to the copolymer (A), the carbon black (B) and the liquid rubber (C).

[0034] <Crosslinking Agent> Examples of the crosslinking agent include crosslinking agents that are generally used when crosslinking rubber, such as organic peroxides, sulfur-based compounds, phenolic resins, hydrosilicone-based compounds, amino resins, quinones or their derivatives, amine-based compounds, azo-based compounds, epoxy-based compounds, and isocyanate-based compounds. Among these, organic peroxides and sulfur-based compounds (also called vulcanizing agents) are preferred.

[0035] 《Organic peroxide》 Examples of organic peroxides include dicumyl peroxide, 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.

[0036] In the copolymer composition for sealing parts of the present invention, when an organic peroxide is used as a crosslinking agent, the content of the organic peroxide is usually 0.1 to 20 parts by mass, preferably 0.2 to 15 parts by mass, and more preferably 0.5 to 10 parts by mass, based on 100 parts by mass of copolymer (A).

[0037] When an organic peroxide is used as a crosslinking agent, it is preferable to use a crosslinking auxiliary in combination. In this case, the copolymer composition for sealing parts of the present invention further containing a crosslinking auxiliary may be used, and the organic peroxide may be blended with the copolymer composition before the crosslinking step, and the crosslinking step may be performed.

[0038] <Crosslinking aid> Examples of the crosslinking aid include sulfur; quinone dioxime-based crosslinking aids such as p-quinone dioxime; crosslinking aids having two or more ethylenic double bonds; maleimide-based crosslinking aids; and metal oxides such as zinc oxide (e.g., ZnO#1 / zinc oxide type 2 (JIS standard (K-1410)), manufactured by Hakusui Tech Co., Ltd.), magnesium oxide, and zinc oxide (e.g., zinc oxide such as "META-Z102" (trade name, manufactured by Inoue Lime Industry Co., Ltd.)). Of these, crosslinking aids having two or more ethylenic double bonds are preferred.

[0039] The number of ethylenic double bonds in the crosslinking aid having two or more ethylenic double bonds is preferably 2 to 6, more preferably 2 to 4. Examples of the crosslinking aid having two or more ethylenic double bonds include (meth)acrylic crosslinking aids such as ethylene glycol di(meth)acrylate and trimethylolpropane tri(meth)acrylate; allyl crosslinking aids such as diallyl phthalate and triallyl isocyanurate; and vinyl crosslinking aids such as divinylbenzene. Among these, (meth)acrylic crosslinking aids are preferred, and ethylene glycol dimethacrylate is more preferred.

[0040] When the copolymer composition for sealing parts of the present invention contains a crosslinking auxiliary, the content of the crosslinking auxiliary is usually 0.5 to 10 mol, preferably 0.5 to 7 mol, more preferably 1 to 5 mol, per 1 mol of the organic peroxide.

[0041] 《Sulfur compounds》 Specific examples of sulfur-based compounds include sulfur, sulfur chloride, sulfur dichloride, morpholine disulfide, alkylphenol disulfide, tetramethylthiuram disulfide, and selenium dithiocarbamate.

[0042] In the copolymer composition for sealing parts of the present invention, when a sulfur-based compound is used as a crosslinking agent, the content of the sulfur-based compound is usually 0.3 to 10 parts by mass, preferably 0.5 to 7.0 parts by mass, and more preferably 0.7 to 5.0 parts by mass, based on 100 parts by mass of copolymer (A).

[0043] When a sulfur-based compound is used as a crosslinking agent, it is preferable to use a vulcanization accelerator in combination. Examples of the vulcanization accelerator include thiazole-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazole sulfenamide, N-oxydiethylene-2-benzothiazole sulfenamide, N,N'-diisopropyl-2-benzothiazole sulfenamide, 2-mercaptobenzothiazole, 2-(4-morpholinodithio)benzothiazole, 2-(2,4-dinitrophenyl)mercaptobenzothiazole, 2-(2,6-diethyl-4-morpholinothio)benzothiazole, and dibenzothiazyl disulfide; guanidine-based vulcanization accelerators such as diphenylguanidine, triphenylguanidine, and diorthotolylguanidine; aldehyde amine-based vulcanization accelerators such as acetaldehyde-aniline condensation product and butylaldehyde-aniline condensation product; 2-mercaptoimidazoline; imidazoline-based vulcanization accelerators such as diethylthiourea and dibutylthiourea; thiuram-based vulcanization accelerators such as tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, and dipentamethylenethiuram tetrasulfide; dithioacid salt-based vulcanization accelerators such as zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc dibutyldithiocarbamate, and tellurium diethyldithiocarbamate; thiourea-based vulcanization accelerators such as ethylenethiourea (for example, Suncerer 22C (trade name; manufactured by Sanshin Chemical Industry Co., Ltd.)), N,N'-diethylthiourea, and N,N'-dibutylthiourea; xanthate-based vulcanization accelerators such as zinc dibutylxatogenate; and others such as zinc oxide.

[0044] When the copolymer composition for sealing parts of the present invention contains a vulcanization accelerator, the content of the vulcanization accelerator is usually 0.1 to 20 parts by mass, preferably 0.2 to 15 parts by mass, and more preferably 0.5 to 10 parts by mass, based on 100 parts by mass of the copolymer (A).

[0045] The vulcanization aid can be preferably used when the crosslinking agent is a sulfur-based compound, and examples thereof include zinc oxide (e.g., ZnO#1 / zinc oxide type 2, manufactured by Hakusui Tech Co., Ltd.), magnesium oxide, and zinc oxide (e.g., zinc oxide such as "META-Z102" (trade name; manufactured by Inoue Seki Kogyo Co., Ltd.)).

[0046] When the copolymer composition for sealing parts of the present invention contains a vulcanization aid, the content of the vulcanization aid is usually 1 to 20 parts by mass based on 100 parts by mass of the copolymer (A). The copolymer composition for sealing parts of the present invention may further contain at least one selected from inorganic fillers, reinforcing materials other than carbon black, antioxidants, processing aids, activators, moisture absorbents, antistatic agents, colorants, lubricants, and thickeners. The copolymer composition for sealing parts of the present invention may further contain other polymers than the copolymer (A), such as elastomers and / or rubbers. Each of the components described below may be used alone or in combination of two or more.

[0047] <Inorganic fillers> Examples of inorganic fillers include light calcium carbonate, heavy calcium carbonate, talc, and clay. Of these, heavy calcium carbonate is preferred.

[0048] When the copolymer composition of the present invention contains an inorganic filler, the content of the inorganic filler is usually 2 to 50 parts by mass, preferably 5 to 50 parts by mass, based on 100 parts by mass of the copolymer (A).

[0049] <Reinforcing agent> Examples of the reinforcing agent include silica, calcium carbonate, activated calcium carbonate, fine talc, and differential silicic acid, except for the above-mentioned carbon black (B).

[0050] When the copolymer composition of the present invention contains a reinforcing agent, the content of the reinforcing agent is usually 0.1 to 100 parts by mass, preferably 5 to 30 parts by mass, based on 100 parts by mass of the copolymer (A).

[0051] <Anti-aging agent (stabilizer)> The copolymer composition for sealing parts of the present invention contains an antioxidant (stabilizer), which can extend the life of a (crosslinked) molded article formed from the copolymer composition for sealing parts. Examples of the antioxidant include amine-based antioxidants, phenol-based antioxidants, and sulfur-based antioxidants.

[0052] Examples of the amine-based antiaging agents include aromatic secondary amine-based antiaging agents such as phenylbutylamine and N,N-di-2-naphthyl-p-phenylenediamine. Examples of the phenol-based antiaging agents include dibutylhydroxytoluene and pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]. Examples of the sulfur-based antiaging agents include thioether-based antiaging agents such as bis[2-methyl-4-(3-n-alkylthiopropionyloxy)-5-t-butylphenyl]sulfide; dithiocarbamate-based antiaging agents such as nickel dibutyldithiocarbamate; 2-mercaptobenzoylimidazole, 2-mercaptobenzimidazole, zinc salt of 2-mercaptobenzimidazole, dilaurylthiodipropionate, and distearylthiodipropionate.

[0053] When the copolymer composition for sealing parts of the present invention contains an antioxidant, the content of the antioxidant is usually 0.3 to 10 parts by mass, and preferably 0.5 to 7.0 parts by mass, per 100 parts by mass in total of component (A) and other polymers (elastomers, rubbers, etc.) blended as necessary.

[0054] <Processing aids> As the processing aid, a wide variety of processing aids that are generally compounded with rubber can be used. Examples of processing aids include ricinoleic acid, stearic acid, palmitic acid, lauric acid, barium stearate, zinc stearate, calcium stearate, and esters. Among these, stearic acid is preferred.

[0055] When the copolymer composition for sealing parts of the present invention contains a processing aid, the content of the processing aid is usually 10 parts by mass or less, preferably 8.0 parts by mass or less, based on 100 parts by mass of the copolymer (A).

[0056] <Activator> Examples of the activator include amines such as di-n-butylamine, dicyclohexylamine, and monoethanolamine; activators 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.

[0057] When the copolymer composition for sealing parts of the present invention contains an activator, the content of the activator is usually 0.2 to 10 parts by mass, preferably 0.3 to 5 parts by mass, based on 100 parts by mass of the copolymer (A).

[0058] <Moisture absorbent> Examples of moisture absorbents include calcium oxide, silica gel, sodium sulfate, molecular sieves, zeolite, and white carbon.

[0059] When the copolymer composition for sealing parts of the present invention contains a moisture absorbent, the content of the moisture absorbent is usually 0.5 to 15 parts by mass, preferably 1.0 to 12 parts by mass, based on 100 parts by mass of the copolymer (A).

[0060] <Other polymers> The copolymer composition for sealing parts of the present invention may further contain another polymer other than the copolymer (A).

[0061] Other polymers that require crosslinking include, for example, rubbers such as natural rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, chloroprene rubber, nitrile rubber, butyl rubber, acrylic rubber, silicone rubber, fluororubber, and urethane rubber.

[0062] Other polymers that do not require crosslinking include, for example, elastomers such as styrene-butadiene block copolymers (SBS), styrene-based thermoplastic elastomers (TPS) such as polystyrene-poly(ethylene-butylene)-polystyrene (SEBS) and polystyrene-poly(ethylene-propylene)-polystyrene (SEPS), olefin-based thermoplastic elastomers (TPO), vinyl chloride-based elastomers (TPVC), ester-based thermoplastic elastomers (TPC), amide-based thermoplastic elastomers (TPA), urethane-based thermoplastic elastomers (TPU), and other thermoplastic elastomers (TPZ).

[0063] When the copolymer composition for sealing parts of the present invention contains another polymer, the content of the other polymer is usually 100 parts by mass or less, preferably 80 parts by mass or less, per 100 parts by mass of component (A).

[0064] <Preparation of Copolymer Composition for Seal Parts> The copolymer composition for sealing parts of the present invention can be prepared by kneading the copolymer (A), the carbon black (B), the liquid rubber (C), a crosslinking agent blended as necessary, and other components at a desired temperature using a kneading machine such as a mixer, a kneader, or a roll.

[0065] One embodiment of the copolymer composition of the present invention is prepared, for example, as follows. Copolymer (A), carbon black (B), liquid rubber (C), and other predetermined components are put into a kneader and kneaded and homogenized under predetermined heating conditions (e.g., 80 to 200°C for 3 to 30 minutes) (kneading A). In kneading A, a crosslinking agent or the like that crosslinks copolymer (A) when heated to the heating temperature of kneading A is not added. The temperature of the mixture kneaded in kneading A is then lowered to below the crosslinking temperature of the crosslinking agent (e.g., 130°C or lower), and then the crosslinking agent or the like that was not added in kneading A is added to the mixture, and further kneaded and homogenized under predetermined heating conditions (e.g., roll temperature 30 to 80°C for 1 to 30 minutes) (kneading B), to obtain the copolymer composition of the present invention.

[0066] <Sealing parts> Specific examples of sealing parts made of the sealing part copolymer composition of the present invention include O-rings, industrial rolls, packings (eg, condenser packings), gaskets, and various other parts that require sealing. EXAMPLES

[0067] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples in any way. The ethylene / α-olefin / non-conjugated polyene copolymer (A) used in the examples of the present invention is shown below.

[0068] [Ethylene-α-olefin-non-conjugated polyene copolymer (A)] According to the description of [Synthesis Example C1] of WO 2015 / 122415, an ethylene-1-butene-5-ethylidene-2-norbornene (ENB) copolymer having the following physical properties was obtained. Hereinafter, this is referred to as "ethylene copolymer (A-1)".

[0069] The constitution and physical properties of the ethylene copolymer (A-1) are as follows: Structural units derived from ethylene: 67.7 mol% Structural units derived from 1-butene: 30.0 mol% Structural units derived from ENB: 2.3 mol% Mooney Viscosity ML(1+4)100℃:30 Mooney Viscosity ML(1+4)125℃:22 B value: 1.3

[0070] [Physical properties of ethylene copolymer (A-1)] <Molar amounts of structural units derived from ethylene, structural units derived from α-olefins, and structural units derived from non-conjugated polyenes> The molar amount is 1 The intensity was measured using a H-NMR spectrometer. Details of the measurement conditions are described in WO 2015 / 122415.

[0071] <Mooney Viscosity> The Mooney viscosity (ML(1+4) 100° C., 125° C.) was measured using a Mooney viscometer (Shimadzu Corporation, SMV202 type) in accordance with JIS K6300 (1994).

[0072] The measurement solvent was o-dichlorobenzene-d4 / benzene-d6 (4 / 1 [v / v]) at a measurement temperature of 120°C. 13 A C-NMR spectrum (100 MHz, JEOL ECX400P) was measured, and calculation was performed based on the following formula (i). B value=([EX]+2[Y]) / [2×[E]×([X]+[Y])]···(i) [Here, [E], [X] and [Y] respectively represent the molar fractions of structural units derived from ethylene [A], α-olefins [B] having 4 to 20 carbon atoms, and non-conjugated polyenes [C], and [EX] represents the ethylene [A]-α-olefins [B] having 4 to 20 carbon atoms dyad chain fraction.]

[0073] The ethylene-α-olefin-non-conjugated polyene copolymers used in the comparative examples of the present invention are shown below.

[0074] [Ethylene-α-olefin-non-conjugated polyene copolymer] The ethylene-propylene-ENB copolymer (copolymer-2) shown below was used as the ethylene-α-olefin-non-conjugated polyene copolymer. Product name: Mitsui EPT 4045M: Mooney viscosity ML (1+4) 100℃ = 45, ethylene content = 45% by weight, diene (ENB) content = 7.6% by weight.

[0075] The ethylene-propylene-VNB copolymer (S-1) [copolymer (S-1)] used in Example 2 of the present invention and Comparative Example 3 had the following physical properties. Structural units derived from ethylene: 70.9 mol% Structural units derived from propylene: 28.7 mol% Structural units derived from VNB: 0.4 mol% Mooney Viscosity ML(1+4)100℃:10 B value: 1.2

[0076] [Carbon black (B)] In the examples and comparative examples, the following carbon blacks were used as the carbon black (B). Product name: Asahi #60UG, manufactured by Asahi Carbon Co., Ltd.

[0077] [Liquid rubber (C)] In the examples and comparative examples, the liquid rubber (C) used was liquid polyisoprene LIR-50 (C-1-1), manufactured by Kuraray Co., Ltd.

[0078] <<Physical Properties of Crosslinked Ethylene-Based Copolymer Composition>> <Tensile stress at break, tensile elongation at break> The tensile stress at break and the tensile elongation at break of the sheet were measured by the following method. The sheet was punched out to prepare No. 3 dumbbell test pieces as described in JIS K 6251 (1993). Using these test pieces, tensile tests were carried out according to the method specified in JIS K6251, section 3, at a measurement temperature of 25°C and a tensile speed of 500 mm / min, and the modulus at 100% elongation (M100), tensile stress at break (TB), and tensile elongation at break (EB) were measured.

[0079] TR Test The sheet was subjected to a TR test (low-temperature elastic recovery test) in accordance with JIS K 6261-4. A cold resistance test was conducted to measure the cold resistance. In this test, the stretched sheet is frozen and the temperature is raised continuously to increase the stretch rate. The recovery of the sheet that had been stretched was measured (the length of the test piece was stretched by 10% and 7% by increasing the temperature). The temperatures at which the material shrinks (recovers) by 0% are indicated as TR10 and TR70, respectively. The lower the R10 (unit: °C), the better the cold resistance.

[0080] <Compression set> The test pieces for measuring compression set (CS) were measured according to JIS K6262 (1997). The compression set was measured after treatment at 120°C for 70 hours. It is desirable for the compression set to be small.

[0081] Example 1 MIXTRON BB MIXER (manufactured by Kobe Steel, BB-2 type, volume 1.7L, Using a thermocouple 2WH, 5 parts by mass of Meta Z102 as a crosslinking aid, 1 part by mass of stearic acid as a processing aid, 70 parts by mass of Asahi #60UG as carbon black, 2 parts by mass of Sandant MB (2-mercaptobenzimidazole) as an antiaging agent, 1 part by mass of Irganox 1010 (pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate]) as an antiaging agent, and 15 parts by mass of the liquid polyisoprene LIR-50 (C-1-1) as a liquid rubber (C) were blended and kneaded to obtain Compound 1.

[0082] The mixing conditions for compound 1 were: rotor speed 40 rpm, floating weight Pressure is 3kg / cm 2 The kneading time was 5 minutes, and the kneading discharge temperature was 150°C. The Mooney viscosity ML(1+4) of Compound 1 at 100°C was measured using a Mooney viscometer (Shimadzu Corporation SM The measurements were performed using a thermocouple (V202 type) in accordance with JIS K6300 (1994).

[0083] Next, after confirming that the temperature of Compound 1 had reached 40°C, it was rolled using a 6-inch roll. To Compound 1, 9.5 parts by mass of 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexane (product name: Perhexa 25B-40, manufactured by NOF Corporation) was added as a crosslinking agent, and the mixture was kneaded to obtain Compound 2.

[0084] The kneading conditions for preparation of compound 2 were: roll temperature front roll / rear roll = 50°C / 50°C; The roll speed is front roll / rear roll = 18 rpm / 15 rpm, and the roll gap is 3 mm. The mixture was mixed for 8 minutes and then discharged to obtain Compound 2.

[0085] Compound 2 was pressed at 180°C for 15 minutes using a press molding machine to obtain a thick molded product. A crosslinked sheet having a thickness of 2 mm was prepared. The crosslinked sheet thus obtained was subjected to the hardness test and the pull test described later. Tension and TR tests were performed.

[0086] Compound 2 was heated at 180°C for 20 minutes using a press molding machine equipped with a cylindrical mold. The specimen was pressed for 10 minutes to prepare a cylindrical test piece with a thickness of 12.7 mm and a diameter of 29 mm. Then, a test piece for measuring compression set (CS) was obtained. The evaluation results are shown in Table 1.

[0087] [Comparative Examples 1 to 3, Example 2] The same procedure as in Example 1 was followed, but based on the composition and cure system set out in Table 1. Table 1 shows the materials used in the examples and comparative examples, and the evaluation results.

[0088] [Table 1]

Claims

1. A copolymer composition for a sealing part, characterized by comprising: an ethylene-α-olefin-non-conjugated polyene copolymer (A) having structural units derived from ethylene [A1], structural units derived from an α-olefin [A2] having 4 to 20 carbon atoms, and structural units derived from a non-conjugated polyene [A3], which satisfy the following requirements (1) to (3): 0.1 to 200 parts by mass of carbon black (B) and 0.1 to 100 parts by mass of at least one liquid rubber (C) selected from liquid polyisoprene and liquid polybutadiene, each having an average molecular weight (Mn) of 1,000 to 100,000, per 100 parts by mass of the copolymer (A). (1) the molar ratio [[A1] / [A2]] of the structural units derived from ethylene [A1] to the structural units derived from an α-olefin [A2] having 4 to 20 carbon atoms is 40 / 60 to 90 / 10; (2) the content of the structural units derived from the non-conjugated polyene [A3] is 0.1 to 6.0 mol %, relative to 100 mol % of the total of the structural units derived from [A1], [A2] and [A3]; (3) The B value represented by the following formula (i) is 1.20 or more. B value = ([EX]+2[Y]) / [2×[E]×([X]+[Y])]...(i) [Here, [E], [X], and [Y] represent the molar fractions of structural units derived from ethylene [A1], C4-C20 α-olefin [A2], and non-conjugated polyene [A3], respectively, and [EX] represents the ethylene [A1]-C4-C20 α-olefin [A2] dyad chain fraction.]

2. 2. The copolymer composition for sealing parts according to claim 1, wherein the α-olefin [A2] having 4 to 20 carbon atoms constituting the copolymer (A) is 1-butene.

3. 2. The copolymer composition for sealing parts according to claim 1, wherein the non-conjugated polyene [A3] constituting the copolymer (A) is 5-ethylidene-2-norbornene (ENB).

4. The copolymer composition for sealing parts according to claim 1, wherein the copolymer (A) further satisfies the following requirement (4): (4) The Mooney viscosity ML(1+4)125°C at 125°C is 5 to 100.

5. A sealing part comprising the copolymer composition for sealing parts according to any one of claims 1 to 4.