Vulcanized HNBR products with improved hot air resistance.

Abstract

To provide a vulcanizate based on a vulcanizable composition, the vulcanizate having very good hot air stability, especially a reduced change in elongation at break and / or a reduced change in tensile strength.SOLUTION: The present invention relates to vulcanizable compositions that contain HNBR rubber, polyamide and peroxidic crosslinkers, along with optional light fillers and antioxidants, to the vulcanized products thereof, and to the use thereof for the production of shaped parts.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a vulcanizable composition comprising HNBR rubber, polyamide, a peroxide crosslinking agent, and optionally a light-colored filler and an anti-aging stabilizer, to vulcanizates thereof, and to their use for the production of molded articles.

Background Art

[0002] Vulcanizates produced from vulcanizable compositions should be noted for their different hot air stabilities. According to the classification according to the ASTM-D 2000 standard, vulcanizates made of natural rubber (NR) can be used up to 70°C; HNBR rubber has a significantly reduced number of double bonds (typically less than 50% of the double bonds in the original NBR), which achieves an improvement in hot air stability up to 150°C, among other things. When the application requires even higher hot air stability, it is often necessary to use fluorinated rubber (e.g., FKM), which can be understood to be disadvantageous in both technical and financial terms. Thus, NBR vulcanizates typically have better low-temperature flexibility and better stability in basic media. By a suitable formulation of a rubber mixture based on HNBR rubber, the object was therefore to find a way to further improve the hot air stability in order to provide customers with a technically and economically attractive alternative to FKM formulations.

[0003] (Patent Document 1) discloses a composition comprising acrylate rubber having less than 40% by weight of acrylate rubber and 10% to 60% by weight of polyamide having a melting point above 160°C. There is no disclosure of a composition based on HNBR rubber at all.

[0004] (Patent Document 2) describes a composition comprising EVM (ethylene vinyl acetate polymer), a crosslinkable polyacrylate, and polyamide, wherein the polyamide has a melting point above 160°C. There is no disclosure of a composition based on HNBR rubber at all.

[0005] Patent document 3 discloses vulcanizable compositions of HNBR with a residual double bond content of less than 1% containing polyamide (Nylon® 12; Grilamid L20G). The amount of polyamide in the vulcanizable composition is 20% to 55% by weight. The example used is an HNBR rubber with 34% by weight of acrylonitrile (ACN).

[0006] Patent Document 4 discloses a thermoplastic elastomer composition (TPE) consisting of 40 parts by weight of carboxyl group-containing HXNBR and 60 parts by weight of polyamide.

[0007] Patent Document 5 discloses a composition containing 20 or 30 parts by weight of polyamide (Nylon (registered trademark) 6 or Nylon (registered trademark) 12) and 70 to 80 parts by weight of highly saturated nitrile rubber and / or highly saturated nitrile rubber containing carboxyl groups.

[0008] Patent Document 6 discloses compositions containing rubber and a thermoplastic resin. Examples of rubbers that can be used include NBR, XNBR, or HNBR. The thermoplastic resin is present in an amount of 5 to 60 parts. Specifically disclosed is a composition containing HNBR (Zetpol 2000) and a TPC (Pebax) consisting of polyether blocks and polyamide blocks. There is no disclosure of the hot air aging properties of these compositions. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] International Publication No. A-2012 / 177879 Brochure [Patent Document 2] International Publication No. A-2014 / 089136 Brochure [Patent Document 3] European Patent Application Publication No. A-0364859 [Patent Document 4] European Patent Application Publication No. EP-A-1672027 [Patent Document 5] European Patent Application Publication No. EP-A-2692788 [Patent Document 6] U.S. Patent No. 6,133,375 Summary of the Invention [Problem to be solved by the invention]

[0010] The problem addressed by the present invention is to provide a vulcanizate based on a vulcanizable composition, said vulcanizate having very good hot air stability, in particular a reduced variation in elongation at break and / or a reduced variation in tensile strength. [Means for solving the problem]

[0011] The solution to this problem and the subject of the present invention is therefore: (a) HNBR rubber; (b) a polyamide; (c) a peroxide crosslinker; (d) optionally with a light-colored filler; (e) optionally with an aging stabilizer; A vulcanizable composition comprising: The composition has a ratio of (a) to (b) of 1:0.01 to 1:0.15, preferably 1:0.05 to 1:0.10.

[0012] Thanks to the vulcanizable composition according to the invention it is already possible to provide vulcanizates which overcome the drawbacks of the prior art. DETAILED DESCRIPTION OF THE INVENTION

[0013] It should be pointed out at this point that the scope of the present invention encompasses any and all possible combinations of the components, ranges of values, basic definitions and / or process parameters set forth above and recited herein below, in general terms or within areas of preference.

[0014] The individual components of the vulcanizable composition according to the present invention are described in detail herein below.

[0015] Vulcanizable compositions based on HNBR rubber The present invention provides a vulcanizable composition comprising (a) HNBR rubber, (b) polyamide, and (c) peroxide crosslinker, wherein the ratio of (a) to (b) is 1:0.01 to 1:0.15, preferably 1:0.05 to 1:0.1. A preferred embodiment relates to a vulcanizable composition further comprising (d) at least one light-colored filler and / or (e) at least one aging stabilizer.

[0016] (a) HNBR rubber In the context of this application, "nitrile-diene copolymer" (nitrile-butadiene copolymer, nitrile rubber, also abbreviated as "NBR") is understood to mean a rubber which is a copolymer, terpolymer or quaterpolymer of at least one α,β-ethylenically unsaturated nitrile, at least one conjugated diene and optionally one or more additional copolymerizable monomers. This term therefore also encompasses copolymers having two or more α,β-ethylenically unsaturated nitrile monomer units and two or more conjugated diene monomer units.

[0017] "Hydrogenated nitrile-diene copolymer" ("HNBR") is understood to mean the corresponding copolymer, terpolymer or quaterpolymer in which at least some of the C=C double bonds in the copolymerized diene units, preferably at least 50% of the C=C double bonds, are hydrogenated. In a preferred embodiment, the hydrogenated HNBR rubber is fully hydrogenated.

[0018] The term "fully hydrogenated" means that the degree of hydrogenation of the butadiene units in the hydrogenated nitrile-diene copolymer is between 99.1% and 100%.

[0019] The term "copolymer" includes polymers having two or more monomer units.

[0020] α,β-ethylenically unsaturated nitrile The α,β-ethylenically unsaturated nitrile used to form the α,β-ethylenically unsaturated nitrile unit can be any known α,β-ethylenically unsaturated nitrile. (C3-C5) α,β-ethylenically unsaturated nitriles such as acrylonitrile, α-haloacrylonitrile, for example α-chloroacrylonitrile and α-bromoacrylonitrile, α-alkylacrylonitrile, for example methacrylonitrile, ethacrylonitrile, or a mixture of two or more α,β-ethylenically unsaturated nitriles are preferred. Acrylonitrile, methacrylonitrile, ethacrylonitrile or a mixture thereof are particularly preferred. Acrylonitrile is highly particularly preferred.

[0021] The amount of α,β-ethylenically unsaturated nitrile unit is typically in the range of 10% to 60% by weight, preferably 15% to 50% by weight, more preferably 17% to 44% by weight, based on the total amount of 100% by weight of all monomer units in the HNBR rubber.

[0022] Conjugated diene The conjugated diene forming the conjugated diene unit can be any conjugated diene, especially conjugated C4-C 12 diene. 1,3-Butadiene, isoprene, 2,3-dimethylbutadiene, 1,3-pentadiene (piperylene), 2-chloro-1,3-butadiene or a mixture thereof are particularly preferred. 1,3-Butadiene and isoprene or a mixture thereof are especially preferred. 1,3-Butadiene is highly particularly preferred.

[0023] The amount of conjugated diene is typically in the range of 40% to 90% by weight, preferably 50% to 85% by weight, more preferably 56% to 83% by weight, based on the total amount of 100% by weight of all monomer units in the HNBR rubber.

[0024] Further comonomer α,β-ethylenically unsaturated carboxylic acid ester unit In addition to the α,β-ethylenically unsaturated nitrile units and conjugated diene units, the HNBR rubber may contain at least one α,β-ethylenically unsaturated carboxylic acid ester unit.

[0025] Typical α,β-ethylenically unsaturated carboxylic acid ester units are: Alkyl (meth)acrylates, especially C4-C 18 alkyl(meth)acrylates, preferably n-butyl, tert-butyl, n-pentyl or n-hexyl(meth)acrylate; Alkoxyalkyl (meth)acrylates, especially C4-C 18 Alkoxyalkyl (meth)acrylate, preferably C4-C 12 Alkoxyalkyl (meth)acrylates; ● Hydroxyalkyl (meth)acrylates, especially C4-C 18 Hydroxyalkyl (meth)acrylate, preferably C4-C 12 Hydroxyalkyl (meth)acrylate; Cycloalkyl (meth)acrylates, especially C5-C 18 -cycloalkyl(meth)acrylates, preferably C6-C 12 cycloalkyl(meth)acrylates, more preferably cyclopentyl(meth)acrylate, cyclohexyl(meth)acrylate, cycloheptyl(meth)acrylate; Alkylcycloalkyl (meth)acrylates, especially C6-C 12 Alkylcycloalkyl(meth)acrylate, preferably C7-C 10 Alkylcycloalkyl(meth)acrylates, more preferably methylcyclopentyl(meth)acrylate and ethylcyclohexyl(meth)acrylate; Aryl monoesters, especially C6-C 14 aryl monoesters, preferably phenyl (meth)acrylate or benzyl (meth)acrylate; amino-containing α,β-ethylenically unsaturated carboxylic acid esters, such as dimethylaminomethyl acrylate or diethylaminoethyl acrylate; - α,β-ethylenically unsaturated monoalkyl dicarboxylates, preferably Alkyl monoesters, especially C4-C 18 alkyl monoesters, preferably n-butyl, tert-butyl, n-pentyl or n-hexyl monoesters, more preferably mono-n-butyl maleate, mono-n-butyl fumarate, mono-n-butyl citraconate, mono-n-butyl itaconate, most preferably mono-n-butyl maleate; Alkoxyalkyl monoesters, especially C4-C 18 Alkoxyalkyl monoesters, preferably C4-C 12 Alkoxyalkyl monoesters, Hydroxyalkyl monoesters, especially C4-C 18 Hydroxyalkyl monoesters, preferably C4-C 12 hydroxyalkyl monoesters, Cycloalkyl monoesters, especially C5-C 18 Cycloalkyl monoesters, preferably C6-C 12 cycloalkyl monoesters, more preferably monocyclopentyl maleate, monocyclohexyl maleate, monocycloheptyl maleate, monocyclopentyl fumarate, monocyclohexyl fumarate, monocycloheptyl fumarate, monocyclopentyl citraconate, monocyclohexyl citraconate, monocycloheptyl citraconate, monocyclopentyl itaconate, monocyclohexyl itaconate and monocycloheptyl itaconate; Alkylcycloalkyl monoesters, especially C6-C 12 Alkyl cycloalkyl monoesters, preferably C7-C 10Alkyl cycloalkyl monoesters, more preferably monomethyl cyclopentyl maleate and monoethyl cyclohexyl maleate, monomethyl cyclopentyl fumarate and monoethyl cyclohexyl fumarate, monomethyl cyclopentyl citraconate and monoethyl cyclohexyl citraconate; monomethyl cyclopentyl itaconate and monoethyl cyclohexyl itaconate; Aryl monoesters, especially C6-C 14 Aryl monoesters, preferably monoaryl maleates, monoaryl fumarates, monoaryl citraconates or monoaryl itaconates, particularly preferably monophenyl maleates or monobenzyl maleates, monophenyl fumarates or monobenzyl fumarates, monophenyl citraconates or monobenzyl citraconates, monophenyl itaconates or monobenzyl itaconates, unsaturated polyalkylpolycarboxylates, such as dimethyl maleate, dimethyl fumarate, dimethyl itaconate or diethyl itaconate; or a mixture thereof is.

[0026] In a particularly preferred embodiment, the fully or partially hydrogenated HNBR rubber contains a (C1-C4) alkyl methacrylate, most preferably butyl acrylate.

[0027] The amount of optional α,β-ethylenically unsaturated carboxylic acid ester units in the HNBR rubber according to the present invention is typically in the range of 0% to 20% by weight, preferably 0.5% to 15% by weight, more preferably 1% to 10% by weight, based on 100% by weight of the total amount of all monomer units.

[0028] PEG acrylate In addition to the α,β-ethylenically unsaturated nitrile units and conjugated diene units, the HNBR rubber contains, as further units, units of the general formula (I) [ka] (In the formula, R is a branched or unbranched C1 to C 20 Alkyl, preferably C2-C 20 alkyl, more preferably methyl, ethyl, butyl or ethylhexyl; n is 1 to 12, preferably 1 to 8, more preferably 1 to 5, and most preferably 1, 2, or 3; R 1 is hydrogen or CH3-) The copolymer may contain at least one PEG acrylate unit derived from

[0029] The term "(meth)acrylate" in the context of the present invention stands for "acrylate" and "methacrylate". 1 If the radical is CH3-, the molecule is a methacrylate.

[0030] The term "polyethylene glycol" or the abbreviation "PEG" in the context of the present invention refers to an ethylene glycol section having from 2 repeating ethylene glycol units (PEG-2; n=2) to 12 repeating ethylene glycol units (PEG-2 to PEG-12; n=2 to 12).

[0031] The term "PEG acrylate" is also abbreviated as PEG-X-(M)A, where "X" is the number of repeating ethylene glycol units, "MA" is methacrylate, and "A" is acrylate.

[0032] The acrylate units derived from the PEG acrylate of general formula (I) are referred to in the context of the present invention as "PEG acrylate units".

[0033] Preferred PEG acrylate units are derived from PEG acrylates having the following formulae no. 1 to no. 8, where n is 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12, preferably 2, 3, 4, 5, 6, 7 or 8, more preferably 2, 3, 4 or 5, and most preferably 2 or 3:

[0034]

Table 1

[0035] Other commonly used names for ethoxypolyethylene glycol acrylate (Formula no. 1) are, for example, poly(ethylene glycol) ethyl ether acrylate, ethoxy PEG acrylate, ethoxypoly(ethylene glycol) monoacrylate or poly(ethylene glycol) monoethyl ether monoacrylate.

[0036] These PEG acrylates can be purchased commercially, for example, from Arkema under the Sartomer® trade name, from Evonik under the Visiomer® trade name, or from Sigma Aldrich.

[0037] The amount of optional PEG acrylate units in the HNBR rubber according to the present invention is typically in the range of 0 wt% to 60 wt%, preferably 20 wt% to 60 wt%, more preferably 20 wt% to 55 wt%, based on the total amount of all 100 wt% of the monomer units.

[0038] In an alternative embodiment, the HNBR rubber contains, in addition to α,β-ethylenically unsaturated nitrile units and conjugated diene units, PEG acrylate units derived from PEG acrylate of general formula (I) as a further monomer and monobutyl maleate as a further unsaturated carboxylic acid ester unit, preferably monobutyl maleate.

[0039] In preferred HNBR rubbers according to the present invention, the α,β-ethylenically unsaturated nitrile units are derived from acrylonitrile or methacrylonitrile, more preferably from acrylonitrile, the conjugated diene units are derived from isoprene or 1,3-butadiene, more preferably from 1,3-butadiene, and the optional PEG acrylate units are derived from PEG acrylates of general formula (I) where n is 2 to 8, more preferably from PEG acrylates of general formula (I) where n is 2 or 3, wherein no further carboxylic acid ester units are present.

[0040] In further preferred HNBR rubbers according to the invention, the α,β-ethylenically unsaturated nitrile units are derived from acrylonitrile or methacrylonitrile, more preferably from acrylonitrile, the conjugated diene units are derived from isoprene or 1,3-butadiene, more preferably from 1,3-butadiene, and the optional PEG acrylate units are derived from PEG acrylates of general formula (I) where n is 2 to 12, more preferably from PEG acrylates of general formula (I) where n is 2 or 3.

[0041] In addition, the HNBR rubber and the optional α,β-ethylenically unsaturated carboxylic acid ester units and / or the optional PEG acrylate units may contain one or more further copolymerizable monomers in an amount of 0% to 20% by weight, preferably 0.1% to 10% by weight, based on a total amount of 100% by weight of all monomer units. In that case, the amount of the other monomer units is reduced in a suitable manner so that the sum of all monomer units is always 100% by weight. The HNBR rubber may contain one or more further copolymerizable monomers as further copolymerizable monomers. aromatic vinyl monomers, preferably styrene, α-methylstyrene and vinylpyridine; fluorine-containing vinyl monomers, preferably fluoroethyl vinyl ether, fluoropropyl vinyl ether, o-fluoromethylstyrene, vinyl pentafluorobenzoate, difluoroethylene and tetrafluoroethylene, etc. α-olefins, preferably C2-C 12Olefins, such as ethylene, 1-butene, 4-butene, 4-methyl-1-pentene, 1-hexene or 1-octene, ● Non-conjugated dienes, preferably C4-C such as 1,4-pentadiene, 1,4-hexadiene, 4-cyanocyclohexene, 4-vinylcyclohexene, vinylnorbornene, dicyclopentadiene, etc. 12 Dienes, etc., ● Alkynes such as 1- or 2-butyne, ● α,β-ethylenically unsaturated monocarboxylic acids, preferably acrylic acid, methacrylic acid, crotonic acid or cinnamic acid, ● α,β-ethylenically unsaturated dicarboxylic acids, preferably maleic acid, fumaric acid, citraconic acid, itaconic acid, ● Copolymerizable antioxidants such as N-(4-aminophenyl)acrylamide, N-(4-aminophenyl)methacrylamide, N-(4-aminophenyl)cinnamide, N-(4-aminophenyl)crotonamide, N-phenyl-4-(3-vinylbenzyloxy)aniline, N-phenyl-4-(4-vinylbenzyloxy)aniline or ● Crosslinkable monomers, for example divinyl components such as divinylbenzene may be contained.

[0042] In an alternative embodiment, the HNBR rubber contains, as optional PEG acrylate units, ethoxy, butoxy or ethylhexyloxy polyethylene glycol (meth)acrylate containing 2 to 12 repeating ethylene glycol units, more preferably ethoxy or butoxy polyethylene glycol (meth)acrylate containing 2 to 5 repeating ethylene glycol units, and most preferably ethoxy or butoxy polyethylene glycol (meth)acrylate containing 2 or 3 repeating ethylene glycol units.

[0043] In a further alternative embodiment, the HNBR rubber comprises 8% to 18% by weight of acrylonitrile units, 27% to 65% by weight of 1,3-butadiene units, and optionally 27% to 55% by weight of PEG-2 acrylate units or PEG-3 acrylate units.

[0044] The most preferred HNBR rubbers contain acrylonitrile / butadiene; acrylonitrile / butadiene / (meth)acrylic acid; acrylonitrile / butadiene / butyl (meth)acrylate; acrylonitrile / butadiene / butyl maleate; acrylonitrile / butadiene / butyl itaconate; acrylonitrile / butadiene / methoxyethyl (meth)acrylate; acrylonitrile / butadiene / butoxydiglycol (meth)acrylate or acrylonitrile / butadiene / ethoxytriglycol (meth)acrylate.

[0045] The HNBR rubber according to the present invention typically has a number average molecular weight (Mn) of 10,000 g / mol to 2,000,000 g / mol, preferably 50,000 g / mol to 1,000,000 g / mol, more preferably 50,000 g / mol to 500,000 g / mol, and most preferably 50,000 g / mol to 300,000 g / mol.

[0046] The HNBR rubber according to the present invention typically has a polydispersity index (PDI=M) of 1.5 to 6, preferably 2 to 5, more preferably 2.5 to 4. w / M n (where M w is the weight molecular weight).

[0047] The HNBR rubber according to the present invention typically has a Mooney viscosity (ML1+4@100°C) of 10-150, preferably 20-120, more preferably 25-100.

[0048] Method for preparing non-hydrogenated nitrile-diene copolymers The preparation of the non-hydrogenated nitrile-diene copolymer required as an intermediate for hydrogenation can be achieved by polymerization of the above-described monomers and is described extensively in the literature (e.g., Houben-Weyl, Methoden der Organischen Chemie [Methods of Organic Chemistry], vol. 14 / 1, 30 Georg Thieme Verlag Stuttgart 1961) and is not particularly limited. Generally, the process is one in which the α,β-ethylenically unsaturated nitrile units, the conjugated diene units, and optional further monomer units are copolymerized as desired. The polymerization process used can be any known emulsion polymerization process, suspension polymerization process, bulk polymerization process, or solution polymerization process. An emulsion polymerization process is preferred. Emulsion polymerization is understood to mean a process known per se in which the reaction medium used is usually water (see, inter alia, Roempp Lexikon der Chemie [Roempp’s Chemistry Lexicon], volume 2, 10th edition 1997; P.A. Lovell, M.S. El-Aasser, Emulsion Polymerization and Emulsion Polymers, John Wiley & Sons, ISBN: 0471 96746 7; H. Gerrens, Fortschr. Hochpolym. Forsch. 1, 234 (1959)). The incorporation ratio of the terpolymer can be easily adjusted by those skilled in the art so that the terpolymer according to the invention is obtained. The monomers can be charged initially or reacted incrementally in two or more steps.

[0049] Metathesis and / or hydrogenation: In the production of non-hydrogenated nitrile-diene copolymers, it is also possible for a metathesis reaction or a metathesis reaction followed by subsequent hydrogenation or hydrogenation only to proceed due to the decrease in the molecular weight of the nitrile-diene copolymers. These metathesis or hydrogenation reactions are well known to those skilled in the art and are described in the literature. Metathesis is known, for example, from WO A-02 / 100941 and WO A-02 / 100905 pamphlets and can be used to reduce the molecular weight.

[0050] (b) Polyamide The polyamide in the vulcanizable composition according to the present invention can be prepared from a combination of a diamine and a dicarboxylic acid, from an ω-aminocarboxylic acid or the corresponding lactam. In principle, any polyamide, preferably PA6, PA66, PA610, PA88, PA612, PA810, PA108, PA9, PA613, PA614, PA812, PA1010, PA10, PA814, PA148, PA1012, PA11, PA1014, PA1212 or PA12 can be used.

[0051] Nylon-6 (PA6) or nylon-6,6 (PA66) is particularly preferred, and it is highly particularly preferred to use nylon-6.

[0052] Preferred polyamides according to the present invention are semi-crystalline or amorphous polyamides that can be prepared starting from diamines and dicarboxylic acids and / or lactams or corresponding amino acids having at least five ring members.

[0053] Useful reactants are preferably aliphatic and / or aromatic dicarboxylic acids, more preferably adipic acid, 2,2,4-trimethyladipic acid, 2,4,4-trimethyladipic acid, azelaic acid, sebacic acid, isophthalic acid, terephthalic acid, aliphatic and / or aromatic diamines, more preferably tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, nonane-1,9-diamine, 2,2,4- and 2,4,4-trimethylhexamethylenediamine, isomeric diaminodicyclohexylmethanes, diaminodicyclohexylpropanes, bis(aminomethyl)cyclohexanes, phenylenediamines, xylylenediamines, aminocarboxylic acids, especially aminocaproic acid, or the corresponding lactams. Copolyamides of several of the mentioned monomers are also included.

[0054] Polyamides suitable according to the invention are known, for example, under the brand names Durethan® or Nylon®. Most preferably, Durethan® B31F PA 6 from LANXESS is used.

[0055] It is of course also possible to use mixtures of these polyamides in any desired mixing ratio.

[0056] Proportions of recycled polyamide molding compounds and / or recycled fibres may also be present.

[0057] The polyamide preferably has a relative viscosity of 2.3 to 4.0, more preferably 2.7 to 3.5, where the relative viscosity is determined / can be measured on a 1 wt % solution in m-cresol at 25°C.

[0058] The preparation of polyamides is prior art. Alternatively, of course, it is possible to use copolyamides based on the polyamides mentioned above.

[0059] Numerous polyamide preparation procedures are known, using different monomer units and various chain transfer agents or monomers with reactive groups to establish the desired molecular weight, depending on the desired end product. Industrially relevant processes for preparing polyamides for use in substance mixtures preferably proceed by polycondensation in the melt. In this context, the hydrolytic polymerization of lactams is also considered polycondensation. The preparation of polyamides by thermal polycondensation is known to those skilled in the art; see, inter alia, Nylon Plastics Handbook, Hanser-Verlag Munich 1995, pages 17-27, and Kunststoff-Handbuch [Plastics Handbook] 3 / 4, Polyamide [Polyamides], Carl Hanser Verlag, Munich 1998, pages 22-36.

[0060] Particularly preferred is the random, semi-crystalline, aliphatic PA 6 / 66 copolyamide polymerized from ε-caprolactam and hexamethylenediamine adipate.

[0061] ε-Caprolactam (CAS No. 105-60-2) is particularly preferred for the preparation of polyamides. Cyclohexanone oxime is first prepared from cyclohexanone by reaction with the hydrogen sulfate or hydrochloride of hydroxylamine. This cyclohexanone oxime is converted to ε-caprolactam by Beckmann rearrangement.

[0062] Hexamethylenediamine adipate (CAS number 3323-53-3) is the reaction product of adipic acid and hexamethylenediamine. One of its uses is as an intermediate in the preparation of nylon-6,6. The common name AH salt comes from the initials of the starting material.

[0063] It is also possible to use mixtures of different polyamides, provided they are sufficiently compatible. Compatible polyamide combinations are known to those skilled in the art. Preferred polyamide combinations are PA6 / PA66, PA12 / PA1012, PA12 / PA1212, PA612 / PA12, PA613 / PA12, PA1014 / PA12, or PA610 / PA12, and the corresponding combinations with PA11, more preferably PA6 / PA66. In case of doubt, compatible combinations can be determined by routine experimentation.

[0064] Instead of aliphatic polyamides, the dicarboxylic acid component is derived to an extent of 5 to 100 mol % from aromatic dicarboxylic acids having 8 to 22 carbon atoms, and preferably has a crystallite melting point T according to ISO 11357-3 of at least 250 ° C, more preferably at least 260 ° C, particularly preferably at least 270 ° C. m It is also possible to advantageously use semi-aromatic polyamides having the formula: These polyamides are typically characterized by the addition T (=semi-aromatic). They can be prepared from a combination of diamines and dicarboxylic acids, optionally with the addition of an ω-aminocarboxylic acid or the corresponding lactam. Suitable types are preferably PA66 / 6T, PA6 / 6T, PA6T / MPMDT (MPMD stands for 2-methylpentamethylenediamine), PA9T, PA10T, PA11T, PA12T, PA14T, and copolycondensates of these latter types with aliphatic diamines and aliphatic dicarboxylic acids or with ω-aminocarboxylic acids or lactams. Semi-aromatic polyamides can also be used in the form of blends with other, preferably aliphatic, polyamides, more preferably with PA6, PA66, PA11, or PA12.

[0065] Another suitable class of polyamides is that of the transparent polyamides; these are, in most cases, amorphous but can also be microcrystalline. These can be used as such or as a mixture with aliphatic and / or semi-aromatic polyamides, preferably PA6, PA66, PA11 or PA12. The glass transition temperature Tg, measured according to ISO 11357-3, is at least 110 °C, preferably at least 120 °C, more preferably at least 130 °C, even more preferably at least 140 °C.Preferred transparent polyamides are, inter alia, polyamides of dodecane-1,12-dioic acid and 4,4'-diaminodicyclohexylmethane, which proceed from 4,4'-diaminodicyclohexylmethane having a trans,trans isomer content of 35% to 65%, polyamides of terephthalic acid and / or isophthalic acid and an isomer mixture of 2,2,4- and 2,4,4-trimethylhexamethylenediamine, polyamides of isophthalic acid and hexamethylene-1,6-diamine, copolyamides of hexamethylene-1,6-diamine with a mixture of terephthalic acid / isophthalic acid and optionally 4,4'-diaminodicyclohexylmethane, copolyamides from terephthalic acid and / or isophthalic acid, 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, laurolactam or caprolactam, (co)polyamides of dodecane-1,12-dioic acid or sebacic acid with 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane and optionally laurolactam or caprolactam, copolyamides of isophthalic acid with 4,4'-diaminodicyclohexylmethane and laurolactam or caprolactam, polyamides of dodecane-1,12-dioic acid and 4,4'-diaminodicyclohexylmethane (with a low trans,trans isomer content), copolyamides of terephthalic acid and / or isophthalic acid with an alkyl-substituted bis(4-aminocyclohexyl)methane homolog and optionally hexamethylenediamine, copolyamides of isophthalic acid with bis(4-amino-3-methyl-5-ethylcyclohexyl)methane and optionally a further diamine and optionally a further dicarboxylic acid, copolyamides of isophthalic acid with a mixture of m-xylylenediamine and a further diamine, such as hexamethylenediamine, and optionally a further dicarboxylic acid, such as terephthalic acid and / or naphthalene-2,6-dicarboxylic acid, copolyamides of a mixture of bis(4-aminocyclohexyl)methane and bis(4-amino-3-methylcyclohexyl)methane with an aliphatic dicarboxylic acid having 8 to 14 carbon atoms, and polyamides or copolyamides formed from tetradecane-1,14-dioic acid and a mixture containing an aromatic, arylaliphatic or cycloaliphatic diamine.

[0066] These examples can be modified quite substantially by the addition of further components, preferably caprolactam, laurolactam or diamine / dicarboxylic acid combinations, or by partial or complete replacement of the starting components with other components.

[0067] The lactams or ω-aminocarboxylic acids used as polyamide-forming monomers contain 4 to 19, especially 6 to 12, carbon atoms. Particular preference is given to using ε-caprolactam, ε-aminocaproic acid, caprylolactam, ω-aminocaprylic acid, laurolactam, ω-aminododecanoic acid and / or ω-aminoundecanoic acid.

[0068] Combinations of diamines and dicarboxylic acids are, for example, hexamethylenediamine / adipic acid, hexamethylenediamine / dodecanedioic acid, octamethylenediamine / sebacic acid, decamethylenediamine / sebacic acid, decamethylenediamine / dodecanedioic acid, dodecamethylenediamine / dodecanedioic acid, and dodecamethylenediamine / naphthalene-2,6-dicarboxylic acid. Additionally, alternatively, all other combinations can be used, in particular decamethylenediamine / dodecanedioic acid / terephthalic acid, hexamethylenediamine / adipic acid / terephthalic acid, hexamethylenediamine / adipic acid / caprolactam, decamethylenediamine / dodecanedioic acid / ω-aminoundecanoic acid, decamethylenediamine / dodecanedioic acid / laurolactam, decamethylenediamine / terephthalic acid / laurolactam or dodecamethylenediamine / naphthalene-2,6-dicarboxylic acid / laurolactam.

[0069] The ratio of HNBR rubber (a) to polyamide (b) in the composition according to the present invention is from more than 1:0.01 to 1:0.15, preferably from 1:0.05 to 1:0.1.

[0070] The amount of polyamide (b) in the vulcanizable composition is 1 to 15 parts by weight, preferably 1 to 12.5 parts by weight, more preferably 2 to 12.5 parts by weight, and most preferably 5 to 10 parts by weight based on 100 parts by weight of HNBR rubber (a).

[0071] When the amount of polyamide is too small, i.e., less than 5 phr, no improvement in hot air aging, especially no change in elongation at break and / or change in tensile strength, occurs at all.

[0072] When the amount of polyamide is too high, i.e., more than 10 phr, no sufficient improvement in hot air aging, especially no change in hardness, change in elongation at break and / or change in tensile strength, occurs either.

[0073] (c) Peroxide crosslinking agent Examples of useful peroxide crosslinking agents include bis(2,4-dichlorobenzyl) peroxide, dibenzoyl peroxide, bis(4-chlorobenzoyl) peroxide, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, tert-butyl perbenzoate, 2,2-bis(t-butylperoxy)butene, 4,4-di-tert-butylperoxynonyl valerate, dicumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, tert-butylcumyl peroxide, 1,3-bis(t-butylperoxyisopropyl)benzene, di-t-butyl peroxide, and 2,5-dimethyl-2,5-di(t-butylperoxy)hexa-3-yne and other peroxide crosslinking agents.

[0074] In a preferred embodiment, the composition according to the invention comprises at least one peroxide crosslinking agent selected from dicumyl peroxide, 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexane, 1,3-di(tert-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-di-tert-butylperoxy (hexyne), preferably 1,3-di(tert-butylperoxyisopropyl)benzene.

[0075] In addition to these peroxide crosslinking agents, it may be advantageous to use further additives that can help to increase the crosslinking yield: suitable examples of these include triallyl isocyanurate, triallyl cyanurate, trimethylolpropane tri(meth)acrylate, triallyl trimellitate, ethylene glycol dimethacrylate, butanediol dimethacrylate, zinc diacrylate, zinc dimethacrylate, 1,2-polybutadiene or N,N-m-phenylene bismaleimide.

[0076] The total amount of peroxide crosslinking agent is typically in the range of 0.1 to 20 phr, preferably in the range of 1.5 to 15 phr, more preferably in the range of 2 to 10 phr, based on the HNBR rubber.

[0077] (d) Light-colored fillers The term "light-colored filler" is well known to those skilled in the art and is sufficiently well known, for example, from F. Roethemeyer / F. Sommer: Kautschuktechnologie [Rubber Technology], p. 262 ff., 2001. Examples of light-colored fillers include natural and synthetic light-colored fillers, especially silica-based and / or oxide-based fillers.

[0078] Synthetic light-colored fillers are silica (amorphous silicon dioxide) or silicates, especially calcium silicate, silanized calcium silicate, sodium aluminum silicate or aluminum silicate, silica, fumed silica, water glass or surface-modified silica.

[0079] Natural light-colored fillers are, for example, siliceous earth, Neuburg siliceous earth, quartz powder, alumina, diatomaceous earth, bentonite, chalk (CaCO3), kaolin, wollastonite (CaSiO3) or talc.

[0080] Further light-coloured fillers are metal compounds, such as alkaline earth metal sulfates, especially barium sulfate, metal oxides, especially titanium dioxide, zinc oxide, calcium oxide, magnesium oxide, aluminium oxide (hydrate), iron oxide, alkaline earth metal carbonates, especially calcium carbonate, zinc carbonate or magnesium carbonate, metal hydroxides, especially aluminium hydroxide, aluminium oxyhydrate or magnesium hydroxide.

[0081] The light-coloured filler in the context of the present invention is preferably a basic silica- or oxide-based filler, more preferably zinc oxide, magnesium oxide, sodium aluminium silicate, precipitated silica, silanized calcium silicate or calcined kaolin, most preferably calcined kaolin, e.g. Polestar® 200 R, or silanized calcium silicate, e.g. Tremin® 283-600 VST.

[0082] (e) Aging stabilizer The vulcanizable composition according to the invention also contains at least one aging stabilizer, preferably a phenolic aging stabilizer, an amine aging stabilizer or a phosphite.

[0083] Suitable phenolic ageing stabilizers are alkylated phenols, styrenated phenols; sterically hindered phenols such as 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-p-cresol (BHT), 2,6-di-tert-butyl-4-ethylphenol, 2,2'-methylenebis(6-tert-butyl)-p-cresol, poly(dicyclopentadiene-co-p-cresol); sterically hindered phenols containing ester groups such as n-octadecyl beta-(4-hydroxy-3,5-di-tert-butylphenyl)propionate; sterically hindered phenols containing thioester groups, 2,2'-methylenebis(4-methyl-6-tert-butylphenol) (BPH), 2-methyl-4,6-bis(octylsulfanylmethyl)phenol and sterically hindered thiobisphenols. In a particularly preferred embodiment, two or more aging stabilizers are also added, such as a mixture of 2,2'-methylenebis(6-tert-butyl)-p-cresol, poly(dicyclopentadiene-co-p-cresol) and 2-methyl-4,6-bis(octylsulfanylmethyl)phenol.

[0084] Suitable amine-based aging stabilizers are diaryl-p-phenylenediamine (DTPD), 4,4'-bis(1,1-dimethylbenzyl)diphenylamine (CDPA), octylated diphenylamine (ODPA), phenyl-α-naphthylamine (PAN), phenyl-β-naphthylamine (PBN) or mixtures thereof, preferably based on phenylenediamine. Examples of phenylenediamines are N-isopropyl-N'-phenyl-p-phenylenediamine, N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine (6PPD), N-1,4-dimethylpentyl-N'-phenyl-p-phenylenediamine (7PPD) or N,N-bis-1,4-(1,4-dimethylpentyl)-p-phenylenediamine (77PD).

[0085] Suitable phosphites are tris(nonylphenyl) phosphite or sodium hypophosphite. A preferred phosphite is sodium hypophosphite. Phosphites are generally used in combination with phenolic anti-aging stabilizers.

[0086] Further suitable anti-aging stabilizers are 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ), 2-mercaptobenzimidazole (MBI), methyl-2-mercaptobenzimidazole (MMBI) or zinc methylmercaptobenzimidazole (ZMMBI).

[0087] The anti-aging stabilizer is typically used in the vulcanizable composition in an amount of 0 to 5 parts by weight, preferably 0.5 to 3 parts by weight, based on 100 parts by weight of the HNBR rubber.

[0088] Other optional components: Optionally, the vulcanizable composition according to the invention may further comprise one or more additives and fiber materials well known to those skilled in the art of rubber. These include filler activators, reversion stabilizers, light stabilizers, ozone degradation inhibitors, processing aids, mold release agents, plasticizers, mineral oils, tackifiers, blowing agents, dyes, pigments, waxes, resins, extenders, carbon black, carbon nanotubes, graphene, Teflon® (the latter preferably in powder form), vulcanization retarders, glass reinforcing members (fibers), cords, fabrics, fibers of polyester and natural fiber products, salts of unsaturated carboxylic acids such as zinc diacrylate (ZDA), zinc methacrylate (ZMA) and zinc dimethylacrylate (ZDMA), liquid acrylates, further rubbers or other additives known in the rubber industry (Ullmann’s Encyclopedia of Industrial Chemistry, VCH Verlagsgesellschaft mbH, D-69451 Weinheim, 1993, vol A 23 “Chemicals and Additives”, p. 366-417).

[0089] Useful filler activators include, inter alia, organic silanes such as vinyltrimethyloxysilane, vinyldimethoxymethylsilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, N-cyclohexyl-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, trimethylethoxysilane, isooctyltrimethoxysilane, isooctyltriethoxysilane, hexadecyltrimethoxysilane, or (octadecyl)methyldimethoxysilane. Further filler activators are surface-active substances such as triethanolamine and ethylene glycol having a molecular weight of 74 to 10,000 g / mol. The amount of filler activator is typically 0 to 10 parts by weight based on 100 parts by weight of HNBR.

[0090] The additional rubber may optionally be present in an amount of up to 30 wt%, preferably up to 20 wt%, more preferably up to 10 wt%, based on the total weight of the vulcanizable composition. A preferred additional rubber is ethylene-vinyl acetate polymer (EVM).

[0091] The total amount of additive and fibrous material is typically in the range of 1 to 300 parts by weight based on 100 parts by weight of nitrile rubber.

[0092] In a preferred embodiment of the present invention, the vulcanizable composition comprises (a) 100 parts by weight of HNBR rubber; (b) 1 to 15 parts by weight, preferably 1 to 12.5 parts by weight, more preferably 2 to 12.5 parts by weight, and most preferably 5 to 10 parts by weight of a polyamide; (c) 0.1 to 20 parts by weight of a peroxide crosslinking agent; (d) 0 to 300 parts by weight of a light-colored filler; (e) 0 to 5 parts by weight of an aging stabilizer; Contains:

[0093] In a particularly preferred embodiment of the present invention, the vulcanizable composition comprises (a) 100 parts by weight of HNBR rubber; (b) 1 to 15 parts by weight, preferably 1 to 12.5 parts by weight, more preferably 2 to 12.5 parts by weight, and most preferably 5 to 10 parts by weight of a polyamide; (c) 0.5 to 10 parts by weight of a peroxide crosslinking agent; (d) 10 to 120 parts by weight of a light-colored filler; (e) 0.5 to 3 parts by weight of an aging stabilizer; Contains:

[0094] Method for producing vulcanizable compositions based on HNBR rubber The present invention further provides a method for preparing a vulcanizable composition based on HNBR rubber by mixing HNBR rubber (a), polyamide (b), and peroxide crosslinking agent (c), optionally light-colored filler (d) and aging stabilizer (e), and optionally any additional components. This mixing operation can be accomplished in standard mixing equipment, such as an internal mixer, Banbury mixer, or roller, capable of establishing a temperature high enough to reach the melting point of the polyamide. The order of metered addition is accomplished as described in Process A.

[0095] Two possible procedural variations are presented here below as examples:

[0096] Process A: Preparation of PA / HNBR blends in an internal mixer An internal mixer with intermeshing rotor geometry is preferred.

[0097] Before use, the polyamide is stored at 80 °C for 16 h. At the start, the internal mixer is charged with the polyamide. After a suitable mixing period, HNBR rubber and an anti-aging stabilizer are added. The mixing is achieved under temperature control on condition that the mixture stays at a temperature in the region of at least 230 °C for a suitable time. After a further suitable mixing period, further mixture constituents such as fillers, white pigments (e.g. titanium dioxide), dyes and other processing activators are optionally added. After a further suitable mixing period, the internal mixer is degassed and the shaft is cleaned. After a further suitable period, the internal mixer is emptied to obtain the vulcanizable mixture. A suitable period is understood to mean from 2, 3 seconds to 2, 3 minutes. The crosslinking chemical is incorporated either in a separate step on a roller or added directly together to the internal mixer, especially when the mixing is carried out at an elevated mixing temperature. In this case, it must be ensured that the mixing temperature is sufficiently below the reaction temperature of the crosslinking chemical. The mixture can thus be produced completely by method A (with complete addition of all constituents) or by method A in combination with method B (without addition of the crosslinking chemical). A combination of methods A and B is preferred.

[0098] The vulcanizable mixture produced in this way can be evaluated in the customary manner, for example by Mooney viscosity, by Mooney scorch or by a rheometer test.

[0099] Process B: Production on a roller When the roller is used as the mixing device, the HNBR rubber-PA mixture produced by method A is first applied to the roller. As soon as a uniform milled sheet is formed, fillers, plasticizers and other additives except for the crosslinking chemical are added. After incorporation of all constituents, the crosslinking chemical is added and incorporated. The mixture is then cut three times to the right and three times to the left and turned over five times. The finished milled sheet is rolled to the desired thickness and subjected to further processing according to the desired test method.

[0100] Method for producing a vulcanizate based on HNBR rubber The present invention further provides a method for producing a vulcanizate according to the present invention, preferably as a molded article, characterized in that a vulcanizable composition comprising components (a), (b), (c), optionally (d) and optionally (e) and optionally further components is vulcanized, preferably in a molding process, and more preferably at a temperature in the range of 100°C to 250°C, more preferably at a temperature in the range of 120°C to 250°C, and most preferably at a temperature in the range of 130°C to 250°C. For this purpose, the vulcanizable composition is subjected to further processing on a calender, roll or extruder. The pre-formed mass is then vulcanized in a press, autoclave, hot air system or in what is called an automatic mat vulcanization system ("Auma"), and the preferred temperatures are found to be in the range of 100°C to 250°C, particularly preferably in the range of 120°C to 250°C, and very particularly preferably in the range of 130°C to 250°C. The vulcanization time is typically from 1 minute to 24 hours, preferably from 2 minutes to 1 hour. Depending on the shape and size of the vulcanizate, a second vulcanization by reheating may be required to achieve complete vulcanization.

[0101] The present invention further provides a vulcanizate obtained in this way, based on the vulcanizable composition according to the present invention.

[0102] The present invention also provides the use of a vulcanizate based on the vulcanizable composition according to the present invention for the production of molded articles, preferably for the production of molded articles selected from the group consisting of belts, gaskets, cover panels, rollers, footwear components, hoses, damping elements, stators, cable sheaths and packing elements, more preferably belts and gaskets.

[0103] The present invention thus provides a vulcanizate as a molded article based on a vulcanizable composition according to the invention, preferably selected from a belt, a gasket, a cover panel, a roller, a footwear component, a hose, a damping element, a stator, a cable sheath and a packing element, more preferably a belt and a gasket. Methods which can be used for this purpose by way of example, such as casting, injection molding or extrusion methods, and corresponding injection molding devices or extruders are well known to the person skilled in the art. In the production of these molded articles, the vulcanizable composition according to the invention has to be supplemented with the aforementioned standard auxiliaries known to the person skilled in the art and preferably selected using customary technical knowledge, for example filler activators, vulcanization accelerators, crosslinking agents, anti-ozone agents, processing oils, extender oils, plasticizers, activators or scorch inhibitors.

[0104] A particular advantage of the present invention is that the vulcanizable composition according to the invention based on HNBR rubber is suitable for the production of vulcanizates having improved hot air resistance, i.e. having a small change in tensile strength and / or elongation at break.

Examples

[0105] Test method: For the tensile test, 2 mm sheets were produced by vulcanization of the vulcanizable mixture at 180 °C. Dumbbell-shaped test specimens were punched out from these sheets and the tensile strength and elongation were measured according to DIN 553504.

[0106] The hardness was measured with a durometer according to DIN-ISO 7619.

[0107] The compression set (CS) was measured according to DIN ISO 850 Part A.

[0108] The aging properties of the vulcanizates were measured according to DIN 53508.

[0109] The following substances were used in the examples: The following chemicals were purchased as commercial products from the company specified in each case or were derived from the production plants of the company specified in each case.

[0110] Substances used in vulcanizable compositions: Therban® 3907 HNBR rubber; 39±1.5 wt% acrylonitrile (ACN), residual double bond content (RDB) ≤0.9%; Mooney viscosity 70 MU; volatile matter ≤0.5 wt% (ARLANXEO) Therban® LT 2007 HNBR rubber (acrylate terpolymer); 21±1.5 wt% acrylonitrile (ACN); residual double bond content (RDB) ≤0.9%; Mooney viscosity 74 MU; volatile matter ≤0.49 wt% (ARLANXEO) Durethan® B 31 F PA6 Polyamide (LANXESS) Perkadox® 14-40 Di(tert-butylperoxyisopropyl)benzene 40% supported on silica; peroxide crosslinker (Akzo Nobel Polymer Chemicals) Vulkasil® A1: a sodium aluminum silicate (LANXESS) having a pH in water (5% by weight in water) measured according to DIN ISO 787 / 9 of 11.3±0.7, a content of volatile components measured according to DIN ISO 787 / 2 of 5.5±1.5 and a surface area (BET) measured according to ISO 9277 of 65±15. Aktifit® VM activated Silfit® Z91 (= natural mixture of particulate silica and lamellar kaolinite); light-colored filler (Hoffmann Mineral) Polestar® 200R pH 6.5±0.5 and 8.5m 2 Calcined kaolin containing 55 wt. % SiO2, 41 wt. % Al2O3 with a surface area (BET) of 1 / g; light color filler (Imerys) Vulkanox® HS / LG 2,2,4-trimethyl-1,2-dihydroquinoline polymer (TMQ); lenticular granules (LG); aging stabilizer (LANXESS) Luvomaxx® CDPA 4,4'-bis(1,1-dimethylbenzyl)diphenylamine; aging stabilizer (Lehmann und Voss) Antilux® 110: A mixture of paraffin and moderately broad molecular weight distribution microwax; antiozonant wax (LANXESS) Vulkanox® MB2 4- and 5-methyl-2-mercaptobenzimidazole; aging stabilizer (LANXESS) Uniplex® 546 Trioctyl Trimellitate (TO™); Plasticizer (LANXESS) Maglite® DE Magnesium Oxide (CP Hall) Lithium carbonate Li2CO3 Sodium hypophosphite * H2O NaH2PO2 Aging Stabilizer TAIC 70% KETTLITZ-TAIC 70;Crosslinking aid;(Kettlitz-Chemie)

[0111] Preparation of vulcanizable compositions Before use, the polyamide was stored at 80°C for 16 h. At the beginning, the polyamide was charged to the internal mixer. Before the addition, the internal mixer was heated to 200°C, and after the addition, the rotor speed was adjusted to bring the temperature to at least the melt temperature of the polyamide, in this case 230°C. After 1 minute, the HNBR rubber and aging stabilizer were added. Mixing was achieved under temperature control, provided that the mixture remained at a temperature in the region of at least 230°C for 10 minutes. After that, the further mixture components were added, except for the crosslinking coagent and peroxide. After 1 minute, the internal mixer was vented and the shaft was cleaned. The internal mixer was then emptied to obtain the mixture.

[0112] After the mixture cooled to room temperature, it was applied to a roller unit. The counter-rotating rollers had a diameter of 200 mm and a length of 450 mm. The rollers were preheated to 40°C. The front roller had a speed of 20 rpm and the rear roller had a speed of 22 rpm, so that they operated at a friction of 1:1.1. Once a homogeneous milled sheet was formed, the cross-linking chemicals were added and mixed in. The mixture was then scored three times to the right and three times to the left, and turned five times. The finished milled sheet was rolled to the desired thickness and subjected to further processing according to the desired test method.

[0113] Manufacturing of vulcanized materials The vulcanization properties of the vulcanizable mixtures prepared by the above method are determined using a moving die rheometer (MDR). Measurements are carried out at 180°C to determine indices familiar to those skilled in the art, such as scorch time, t95 and Smax.

[0114] The vulcanizable composition described above is subjected to a heat treatment, the duration of which corresponds to the t95 determined in the MDR.

[0115] The vulcanizable composition according to the invention is subjected to a temperature of 180° C. in a suitable mold (compression vulcanization).

[0116] In the course of crosslinking of the vulcanizable compositions according to the invention, the peroxide compounds (c) bring about free radical crosslinking between and with the hydrogenated nitrile rubbers (a) used.

[0117] All figures shown in the tables in "phr" units mean parts per hundred parts of rubber. The sum of all elastomeric components, including HNBR, equals 100 phr.

[0118] [Table 2]

[0119] [Table 3]

[0120]

Table 4

[0121]

Table 5

[0122]

Table 6

[0123]

Table 7

[0124]

Table 8

[0125]

Table 9

[0126]

Table 10

[0127]

Table 11

[0128] The vulcanizates according to the invention contain 5 to 10 phr of polyamide (b) and have a smaller change in tensile strength and / or a smaller change in elongation at break after 2 or 3 weeks (336 h or 504 h) of hot air aging at 170° C. The vulcanizates without polyamide (V1 or V B1) have a larger change in tensile strength and elongation at break than the vulcanizates with polyamide (P1, P2, P3, P4, P5, P6, and P4.1, P4.2 and P B1).

[0129] The vulcanizates (V2) with 15 phr or more of polyamide have a smaller variation than the vulcanizates (V1) without polyamide, but the variation of tensile strength or of elongation at break or both is much greater and therefore worse than the vulcanizates according to the invention with only 5 to less than 15 phr of polyamide.

[0130] After 504 hours of hot aging at 170°C, vulcanizate P4 with 10 phr of polyamide has both the smallest change in elongation at break (ΔEB) and the smallest change in tensile strength (ΔTS) compared to the comparative vulcanizate without polyamide (V1) and the vulcanizate with too much polyamide (V2).

[0131] After 336 hours of hot aging at 180°C, the inventive vulcanizates P1 to P6 with 1 to 15 phr of polyamide have a smaller change in elongation at break (ΔEB) and a smaller change in tensile strength (ΔTS) than the vulcanizates without polyamide (V1) and with more than 15 phr of polyamide (V2).

[0132] A comparison of vulcanizates V B1 and P B1 shows that even in the case of vulcanizates based on acrylate-containing HNBR terpolymers, the addition of a small amount of polyamide, just 7 phr, leads to a considerable improvement in hot air aging, especially a reduction in the change in elongation at break and in tensile strength.

Claims

1. (a) HNBR rubber, and (b) polyamide 6, optionally (c) a light-colored filler, and optionally (d) an anti-aging stabilizer, wherein the method for producing a vulcanizable composition has a ratio of (a) to (b) of 1:0.01 to 1:0.15, and in the step of providing a vulcanizable mixture obtained by a process of mixing HNBR rubber, polyamide 6, and optionally a light-colored filler and an anti-aging stabilizer, the ratio of HNBR rubber to polyamide 6 is 1:0.01 to 1:0.15, the mixture is not vulcanized, and does not contain any additional rubber, wherein the composition does not contain a functional group-containing ethylene copolymer.

2. The vulcanizable composition according to claim 1, wherein the composition contains 100 parts by weight of hydrogenated HNBR rubber, 1 to 15 parts by weight of polyamide 6, 0 to 300 parts by weight of a light-colored filler, and 0 to 5 parts by weight of an anti-aging stabilizer.

3. The method according to claim 1 or 2, wherein the HNBR rubber (a) contains 20% to 40% by weight of acrylonitrile units, 20% to 80% by weight of butadiene units, and 0% to 60% by weight of additional copolymerizable monomers.

4. The method according to any one of claims 1 to 3, wherein the light-colored filler (c) is zinc oxide, magnesium oxide, sodium aluminum silicate, precipitated silica, silanized calcium silicate, or calcined kaolin.

5. The method according to any one of claims 1 to 4, wherein the anti-aging stabilizer (d) is diaryl-p-phenylenediamine (DTDP), 4,4'-bis(1,1-dimethylbenzyl)diphenylamine (CDPA), octylated diphenylamine (ODPA), 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ), 2-mercaptobenzimidazole (MBI), methyl-2-mercaptobenzimidazole (MMBI), or zinc methylmercaptobenzimidazole (ZMMBI).

6. The vulcanizable composition according to any one of claims 1 to 5, wherein the composition contains 100 parts by weight of HNBR rubber, 5 to 10 parts by weight of polyamide 6, 10 to 120 parts by weight of a light-colored filler, and 0.5 to 3 parts by weight of an anti-aging stabilizer.

7. ​ ​ ​ ​ A method for producing a vulcanizate, characterized in that the vulcanizable composition obtained by the method according to any one of claims 1 to 6 is subjected to vulcanization.

8. A vulcanizate obtained by the method according to claim 7.

9. Use of a vulcanizable composition obtained by the method according to any one of claims 1 to 6 for the production of a molded article.

10. The method according to any one of claims 1 to 6, wherein the ratio of (a) to (b) is 1:0.05 to 1:0.10.

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