Flame-retardant polymer composition, process for its production, use of polyarylene sulfide as a flame retardant and use of the flame-retardant polymer composition

Abstract

Flame-retardant polymer composition, comprising a) 5 to 75 wt.%, based on the total weight of the flame-retardant polymer composition, at least one elastomeric polymer containing at least one polymerized monomer selected under C2-C 30 -Alkylenes, wherein the elastomeric polymer a) is selected from among curable elastomers, b) 2 to 35 wt.%, based on the total weight of the flame-retardant polymer composition, polyarylene sulfide, where component b) is in particle form with a mean particle size in the range of 0.1 to 70 µm, c) at least one hardening agent, d) 0.5 to 75 wt.%, based on the total weight of the flame-retardant polymer composition, at least one compound of an element selected from magnesium, calcium, boron, aluminium, antimony, tin, zinc, organophosphorus compounds, organohalogen compounds and mixtures thereof.

Description

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a flame-retardant polymer composition, a method for producing a flame-retardant polymer composition, the use of polyarylene sulfide as a flame retardant, and the use of the flame-retardant polymer composition. STATE OF THE ART

[0002] Polyolefinic polymers are successfully used in large quantities as molding compounds, for example in the automotive industry, electrical engineering, household appliance technology, and mechanical engineering. In these applications, it is often necessary to make the polymers flame-retardant enough to meet the technical requirements of flammability tests, such as the UL 94 test (Underwriters Laboratories USA).

[0003] To increase the flame-retardant properties of materials and molding compounds based on polyolefinic polymers, flame retardants such as organic halogen compounds, organic phosphate compounds, antimony, tin, and / or zinc compounds are commonly added. However, many flame retardants are classified as extremely harmful to health and / or pose environmental risks.

[0004] To avoid the aforementioned disadvantages, flame retardants that are harmless to health and the environment, such as magnesium hydroxide and / or aluminum hydroxide, can be incorporated into polyolefinic polymers.

[0005] EP 0 605 861 describes halogen-free, flame-retardant molding compounds based on polyamide. The polyamide is modified with magnesium hydroxide and polyphenylene sulfide.

[0006] However, magnesium hydroxide, aluminum hydroxide, and organic phosphate compounds have the disadvantage that their flame-retardant performance is not satisfactory. They can only meet a high standard for molding compounds based on sulfur-crosslinked polyolefinic polymers and be classified as UL 94 V0 in the flammability test according to UL 94.

[0007] Molding compounds based on sulfur-crosslinked polyolefinic polymers exhibit some disadvantages in their application profile. They are less heat-resistant and less resistant to compression set than comparable peroxide-crosslinked polyolefinic polymers. However, molding compounds with advantageous application-related properties based on peroxide-crosslinked polyolefinic polymers, in combination with known, environmentally and health-safe flame retardants such as magnesium hydroxide, aluminum hydroxide, and / or organic phosphate compounds, can only be classified as UL 94 V2 or, at best, UL 94 V1 in the flammability test according to UL 94.

[0008] EP 2418255 A1 describes a cross-linked polymer composition containing polyphenylene sulfide (PPS) and an impact modifier / elasticizer. To obtain the cross-linked polymer composition, the components, such as PPS and the impact modifiers / elasticizers, are subjected to a melt mixture. The continuous phase is formed by the PPS and the dispersed phase by the polyolefin. The cross-linked polymer contains large amounts of PPS, namely 50 to 80 wt.%, preferably even 70 to 80 wt.%.

[0009] US 6,303,708 B1 describes a poly(phenylene ether) / poly(arylene sulfide) resin composition. The composition also contains a salt, e.g., sodium, magnesium, lithium, potassium salts, etc., and elastomeric block copolymers. This composition is produced by melt mixing (extrusion). Here, too, large amounts of PPS (at least 40 wt.%) must be used in the resin to achieve the desired properties.

[0010] WO 2018 / 193019 A1 describes a polymer alloy containing polyphenylene sulfide (PSS) and at least one thermoplastic vulcanizate. A thermoplastic vulcanizate, as defined in WO 2018 / 193019 A1, is both a thermoplastic fluorinated polymer and a dispersed phase of fluorine-containing elastomer. The polymer alloy is obtained by melt mixing the two components.

[0011] It is therefore an object of the invention to provide a flame-retardant polymer composition based on polyolefinic polymers that has both an advantageous property profile and high flame-retardant performance.

[0012] Surprisingly, it was found that this problem is solved by the flame-retardant polymer composition according to the invention and its use.

[0013] The flame-retardant polymer composition according to the invention has the following advantages: - The fire protection properties, especially of peroxide-crosslinked polymers, are improved. - The polymers and products based on them are characterized by advantageous application-related properties, e.g. good heat, weather and fatigue resistance. - The polymers and products based on them are characterized by good sealing properties. SUMMARY OF THE INVENTION

[0014] A first object of the invention is a flame-retardant polymer composition comprising a) 5 to 75 wt.%, based on the total weight of the flame-retardant polymer composition, at least one elastomeric polymer containing at least one polymerized monomer selected under C2-C 30 -Alkylenes, wherein the elastomeric polymer a) is selected from among curable elastomers, b) 2 to 35 wt.%, based on the total weight of the flame-retardant polymer composition, polyarylene sulfide where component b) is in particle form with a mean particle size in the range of 0.1 to 70 µm, c) at least one hardening agent, d) 0.5 to 75 wt.%, based on the total weight of the flame-retardant polymer composition, at least one compound of an element selected from magnesium, calcium, boron, aluminium, antimony, tin, zinc, organophosphorus compounds, organohalogen compounds and mixtures thereof.

[0015] Another object of the invention is a method for producing a curable flame-retardant polymer composition, comprising the steps of: i) Providing at least one curable elastomer a), ii) Providing at least one polyarylene sulfide b), iii) Mixing the curable elastomer a) with the polyarylene sulfide b) at a temperature that is higher than the plasticization temperature of the elastomer a) and lower than the melting temperature of the polyarylene sulfide b), iv) Addition of a curing agent c), in particular a peroxide curing agent, to the polymer mixture to form a curable elastomer composition, wherein the curable flame-retardant polymer composition additionally comprises as component d) at least one compound of an element selected from magnesium, calcium, boron, aluminium, antimony, tin, zinc, organophosphorus compounds, organohalogen compounds and mixtures thereof.

[0016] Another aspect of the invention is the use of a mixture containing component b) and component c) for the flame-retardant treatment of component a).

[0017] Another object of the invention is a method for producing a hardened flame-retardant polymer composition, comprising the steps of: i) Providing at least one curable elastomer a), ii) Providing at least one polyarylene sulfide b), iii) Mixing the curable elastomer a) with the polyarylene sulfide b) at a temperature that is higher than the plasticization temperature of the elastomer a) and lower than the melting temperature of the polyarylene sulfide b), iv) Addition of a curing agent c), in particular a peroxide curing agent, to the polymer mixture to form a curable elastomer composition, wherein the curable flame-retardant polymer composition additionally comprises as component d) at least one compound of an element selected from magnesium, calcium, boron, aluminium, antimony, tin, zinc, organophosphorus compounds, organohalogen compounds and mixtures thereof, and wherein the polymer composition may further contain additives and fillers, v) Curing of the curable elastomer composition obtained in step iv).

[0018] Another object of the invention is a hardened flame-retardant polymer composition obtainable according to the inventive method.

[0019] Another object of the invention is the use of a polyarylene sulfide b) as a flame retardant for a polymer composition comprising at least one elastomeric polymer a), as defined above and below.

[0020] Another object of the invention is the use of the flame-retardant polymer composition, as defined above and below, in automotive parts, for the manufacture of seals, in particular O-rings, frame seals, radial shaft seals, bellows and valve stem seals. DESCRIPTION OF THE INVENTION

[0021] C2-C 30-Alkylene, as defined in the invention, is a linear or branched ethylene unsaturated hydrocarbon with 2 to 30, preferably 2 to 10, and in particular 2 to 6 carbon atoms, having one or more, preferably two, non-cumulative, C=C double bonds in any position, such as ethene, propene, 1-butene, 2-butene, isobutene, 2-methylpropene, 1,2-butylene, 2,3-butylene, isoprene, butadiene, 1-pentene, 2-pentene, 3-pentene, 2-methyl-1-butene, 3-methyl-1-butene, 2-methyl-2-butene, 3-methyl-2-butene, 2-methyl-3-butene, 3-methyl-3-butene, 1,1-dimethylpropene. 1-hexene, 2-hexene, 3-hexene, 4-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene.

[0022] Within the scope of the present invention, the expression C1-C 12-Alkyl for unbranched and branched saturated hydrocarbon residues with 1 to 12, preferably 1 to 8, particularly 1 to 6, carbon atoms. C1-C6 alkyls are particularly suitable. E.g. methyl, ethyl, propyl, 1-methylethyl, butyl, 1-methylpropyl, 2-methylpropyl, 1,1-dimethylethyl, pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 2,2-dimethylpropyl, 1-ethylpropyl, hexyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1,1-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, 3,3-dimethylbutyl, 1-ethylbutyl, 2-ethylbutyl, 1,1,2-trimethylpropyl, 1,2,2-trimethylpropyl, 1-ethyl-1-methylpropyl or 1-ethyl-2-methylpropyl. C1-C4 alkyl means, for example, methyl, ethyl, propyl, 1-methylethyl, butyl, 1-methylpropyl, 2-methylpropyl or 1,1-dimethylethyl.

[0023] Within the scope of the present invention, the expression C1-C 12-Alkoxy for an unbranched or branched saturated C1-C 12 -Alkyl group, as defined above, bonded via an oxygen atom. Preferably, alkoxy groups have 1 to 8, in particular 1 to 6, carbon atoms, especially preferably 1 or 4, and specifically 1 to 2 carbon atoms. C1-C2 alkoxy is methoxy or ethoxy. C1-C4 alkoxy is, for example, methoxy, ethoxy, n-propoxy, 1-methylethoxy (isopropoxy), butoxy, 1-methylpropoxy (sec-butoxy), 2-methylpropoxy (isobutoxy), or 1,1-dimethylethoxy (tert-butoxy). C1-C6 alkoxy includes the meanings given for C1-C4 alkoxy and additionally, for example, 1,1-methylethoxy (sec-butoxy). B. Pentoxy, 1-methylbutoxy, 2-methylbutoxy, 3-methylbutoxy, 1,1-dimethylpropoxy, 1,2-dimethylpropoxy, 2,2-dimethylpropoxy, 1-ethylpropoxy, hexyloxy, 1-methylpentoxy, 2-methylpentoxy, 3-methylpentoxy, 4-methylpentoxy, 1,1-dimethylbutoxy, 1,2-Dimethylbutoxy, 1,3-Dimethylbutoxy, 2,2-Dimethylbutoxy, 2,3-Dimethylbutoxy and 3,3-Dimethylbutoxy.

[0024] Within the scope of the present invention, the expression C1-C 12 -Alkylthio for an unbranched or branched saturated C1-C 12 -Alkyl group, as defined above, bonded via a sulfur atom. It is synonymous with C1-C 12C1-C2 alkyl thio groups are understood to be alkyl thio groups. Alkyl thio groups with 1 to 8 carbon atoms are preferred, particularly those with 1 or 4, and especially 1 to 2 carbon atoms. C1-C2 alkyl thio groups are methyl sulfanyl or ethyl sulfanyl. C1-C4 alkyl sulfanyl groups are, for example, methyl sulfanyl, ethyl sulfanyl, n-propyl sulfanyl, 1-methyl ethyl sulfanyl (isopropyl sulfanyl), butyl sulfanyl, 1-methyl propyl sulfanyl (sec-butyl sulfanyl), 2-methyl propyl sulfanyl (isobutyl sulfanyl), or 1,1-dimethyl ethyl sulfanyl (tert-butyl sulfanyl).C1-C6-Alkylthio beinhaltet die für C1-C4-Alkylsulfanyl angegebenen Bedeutungen und zusätzlich beispielsweise auch Pentylsulfanyl, 1-Methylbutylsulfanyl, 2-Methylbutylsulfanyl, 3-Methylbutylsulfanyl, 1,1-Dimethylpropylsulfanyl, 1,2-Dimethylpropylsulfanyl, 2,2-Dimethylpropylsulfanyl, 1-Ethylpropylsulfanyl, Hexylsulfanyl, 1-Methylpentylsulfanyl, 2-Methylpentylsulfanyl, 3-Methylpentylsulfanyl, 4-Methylpentylsulfanyl, 1,1-Dimethylbutylsulfanyl, 1,2-Dimethylbutylsulfanyl, 1,3-Dimethylbutylsulfanyl, 2,2-Dimethylbutylsulfanyl, 2,3-Dimethylbutylsulfanyl, 3,3-Dimethylbutylsulfanyl, 1-Ethylbutylsulfanyl, 2-Ethylbutylsulfanyl, 1,1,2-Trimethylpropylsulfanyl, 1,2,2-Trimethylpropylsulfanyl, 1-Ethyl-1-methylpropylsulfanyl oder 1-Ethyl-2-methylpropylsulfanyl.

[0025] Within the scope of the present invention, the term "aryl" encompasses mono- or polynuclear aromatic hydrocarbon residues typically having 6 to 24, preferably 6 to 14, and particularly preferably 6 to 10 carbon atoms. Examples of aryl include, in particular, phenyl, naphthyl, indenyl, fluorenyl, anthracenyl, phenanthrenyl, naphthacenyl, chrysenyl, pyrenyl, etc., and specifically phenyl or naphthyl.

[0026] Within the scope of the present invention, the term ‘alkylaryl’ represents an aryl group, as defined above, which is bonded via C1-C6 alkyl, as defined above.

[0027] Within the scope of the present invention, the term ‘arylalkyl’ refers to an alkyl group, as defined above, comprising a C6-C 24 -Aryl, as previously defined, is bound.

[0028] Within the scope of the present invention, the term “aryloxy” refers to an aryl group, as defined above, bonded via oxygen.

[0029] Within the scope of the present invention, the term ‘arylthio’ refers to an aryl group, as defined above, bonded via sulfur. Component a)

[0030] The flame-retardant polymer composition according to the invention can, as an elastomeric polymer, contain a) at least one uncured curable polymer or at least one cured curable polymer or at least one non-curable polymer or a combination thereof.

[0031] The flame-retardant polymer composition comprises as component a) at least one elastomeric polymer containing at least one polymerized monomer selected under C2-C 30 -Alkylenes.

[0032] The term "elastomers" as used in this invention refers to dimensionally stable but elastically deformable plastics whose glass transition temperature is below the temperature at which the polymers are typically used. Elastomers can deform elastically under tensile and compressive stress, but subsequently return to their original, undeformed shape.

[0033] A special type of elastomer is thermoplastic elastomers, which exhibit thermoplastic properties within certain temperature ranges. Generally, thermoplastic elastomers behave similarly to conventional elastomers at low temperatures. However, when heated, they become plastically deformable and exhibit thermoplastic behavior.

[0034] According to the invention, the elastomeric polymer a) is selected from among curable elastomers.

[0035] Curing is a chemical, irreversible cross-linking reaction. As a result of cross-linking (curing), the macromolecules are linked together to form a three-dimensional network. With increasing degree of cross-linking (proportion of cross-link points relative to the volume of the polymer), there is an increase in mechanical and thermal properties, such as strength, modulus of elasticity, hardness, and toughness.

[0036] Elastomers can be hardened by vulcanization, using, for example, sulfur-containing compounds as crosslinking agents or network formers. Hardening can also occur via radical processes, specifically using peroxides.

[0037] Preferably, the elastomeric polymer a) is radically curable, in particular peroxide-curable. Radically curable elastomeric polymers a) are understood to be those capable of forming free radicals that can be crosslinked. For this purpose, the curable elastomeric polymer a) can be reacted with a radical curing agent, resulting in crosslinking sites. These crosslinking sites can, for example, react with the unsaturated sites of a crosslinking coagulator. Crosslinking coagulators contain at least two unsaturated, preferably olefinically unsaturated, groups.

[0038] In a preferred embodiment, the elastomeric polymer is a) crosslinked by CC single bonds. These are obtained by direct reaction of the radical sites of two polymer chains or by reaction of the radical sites of two polymer chains with the crosslinking agent.

[0039] In one embodiment, the elastomeric polymer is a) selected from polyurethanes, silicones, fluorosilicones, polycarbonates, ethylene vinyl acetates (EVA), acrylonitrile / butadiene / acrylates (ABA), acrylonitrile butadiene rubbers (ABN), acrylonitrile butadiene styrenes (ABS), acrylonitrile methyl methacrylates (AMMA), acrylonitrile styrene acrylates (ASA), cellulose acetates (CA), cellulose acetate butyrates (CAB), polysulfones (PSU), poly(meth)acrylates, polyvinyl chlorides (PVC), polyphenylene ethers (PPE = polyphenylene oxides (PPO)), polystyrenes (PS), polyamides (PA), polyolefins, e.g. polyethylene (PE) or polypropylene (PP), polyketones (PK), etc. B. aliphatic polyketones or aromatic polyketones, polyetherketones (PEK), e.g. aliphatic polyetherketones or aromatic polyetherketones, polyimides (Pl), polyetherimides, polyethylene terephthalates (PET), polybutylene terephthalates (PBT), fluoropolymers, polyesters, polyacetals, e.g.Polyoxymethylene (POM), liquid crystal polymers, polyethersulfones (PES), epoxy resins (EP), phenolic resins, chlorosulfonates, polybutadienes, polybutylenes, polyneoprenes, polynitriles, polyisoprenes, natural rubbers, copolymer rubbers such as styrene-isoprene-styrenes (SIS), styrene-butadiene-styrenes (SBS), ethylene-propylene (EPR), ethylene-propylene-diene rubbers (EPDM), styrene-butadiene rubbers (SBR) and their copolymers and blends thereof.

[0040] In a particular embodiment, the polymer a) is selected from diene rubbers. Preferably, the polymer a) is then selected from ethylene propylene diene rubbers (EPDM), natural rubbers (NR), isoprene rubbers (IR), butadiene rubbers (BR), styrene butadiene rubbers (SBR), acrylonitrile butadiene rubbers (NBR) and chloroprene rubbers (CR).

[0041] In particular, the elastomeric polymer contains a) at least one polymerized monomer selected from ethylene, propylene, 1-butene, 1,2-butylene, 2,3-butylene, isobutene, isoprene, styrene, butadiene, unconjugated dienes, 1-hexene, 1-octene, of which different C5-C 20 -Alkenes and mixtures thereof.

[0042] Preferably, the elastomeric polymer a) contains at least one diene monomer polymerized into it.

[0043] In a particular embodiment, the elastomeric polymer a) is an ethylene-propylene-diene rubber. For the purposes of the invention, this term also includes polymers that contain at least one triply or polyunsaturated polymer polymerized in place of or in addition to at least one diene.

[0044] Preferably, the polymer a) contains at least one non-conjugated diene incorporated into the polymer. Suitable dienes are selected from 1,4-hexadiene, 1,6-octadiene, 2-methyl-1,5-hexadiene, 6-methyl-1,5-heptadiene, 7-methyl-1,6-octadiene, cyclohexadiene, dicyclopentadiene, methyltetrahydroindene, 5-vinylnorbornene, 5-methylenenorbornene, 5-ethylidenenorbornene, 5-isopropylidene-2-norbornene, 6-chloromethyl-5-isopropenyl-2-norbornene, and mixtures thereof. The polymer a) may contain at least one triene incorporated into the polymer instead of, or in addition to, at least one diene. Suitable trienes are selected from among 2,3-diisopropylidene-5-norbornene, 2-ethylidene-3-isopropylidene-5-norbornene, 2-propenyl-2,2-norbornadiene, 1,3,7-octatriene, 1,4,9-decatriene and mixtures thereof.

[0045] Preferably the polymer contains a) at least one non-conjugated diene polymerized, selected from dicyclopentadiene, 1,4-hexadiene, 5-methylene, 5-ethylidene and 5-isopropylidene-2-norbornene.

[0046] Preferably the elastomeric polymer contains a) a double bond content of 0 to 20 wt.%, in particular 0 to 10 wt.%.

[0047] According to the invention, component a) is used in an amount of 5 to 75 wt.%, based on the total weight of the flame-retardant polymer composition, preferably in an amount of 20 to 50 wt.%, based on the total weight of the flame-retardant polymer composition. Component b)

[0048] The flame-retardant polymer composition includes component b) polyarylene sulfide.

[0049] According to the invention, component b) is in particle form with an average particle size in the range of 0.1 to 70 µm. Component b) can be in particle form with an average particle size in the range of 0.1 to 70 µm and / or in fiber form with an average fiber diameter in the range of 0.1 to 70 µm.

[0050] If component b) is in particle form, it preferably has a mean particle size in the range of 0.2 to 50 µm, particularly in the range of 0.3 to 30 µm, especially in the range of 0.4 to 20 µm, specifically in the range of 0.4 to 12.5 µm, and particularly in the range of 0.4 to 8 µm.

[0051] If component b) is in fiber form, it preferably has a mean fiber diameter in the range of 0.2 to 50 µm, particularly in the range of 0.3 to 30 µm, especially in the range of 0.4 to 20 µm, specifically in the range of 0.4 to 12.5 µm, and particularly in the range of 0.4 to 8 µm.

[0052] According to the invention, the mean particle size is determined according to ISO 13320 and the mean fiber diameter is determined according to image analysis.

[0053] According to the invention, component b) is used in an amount of 2 to 35 wt.%, based on the total weight of the flame-retardant polymer composition, preferably in an amount of 3 to 25 wt.%, based on the total weight of the flame-retardant polymer composition.

[0054] In a preferred embodiment, component b) contains or is a polyphenylene sulfide, in particular poly-p-phenylene sulfide.

[0055] Polyphenylene sulfide means any polymer which, based on the total number of repeating units in the polymer, contains at least 50 mol-% of a repeating unit of the following formula (I): where R 1 and R 2 , same or different from each other and selected from the group consisting of hydrogen, halogen, C1-C 12 -Alkyl, C7-C 24 -Alkylaryl, C7-C 24 -Aralkyl, C6-C 24 -Aryl, C1-C 12 -Alkoxy, C1-C 12 -Alkylthio, C6-C 18-Aryloxy, C6-C 18 -Arylthio and polyarylene sulfide, wherein the aromatic rings of polyarylene sulfide are each unsubstituted or bear one or two substituents selected from halogen, C1-C 12 -Alkyl, C7-C 24 -Alkylaryl, C7-C 24 -Aralkyl, C6-C 24 -Aryl, C1-C 12 -Alkoxy, C1-C 12 -Alkylthio, C6-C 18 -Aryloxy and C6-C 18 -Arylthio, wherein the arylene groups of polyarylene sulfide each form sulfide groups via a direct CS linkage and are thereby branched or cross-linked. Preferably, the polyarylene sulfides are unsubstituted.

[0056] Preferably both R 1 as well as R 2 Hydrogen.

[0057] In one embodiment, the polyphenylene sulfide has at least 60 mol%, at least 70 mol%, at least 80 mol%, at least 90 mol%, at least 95 mol%, at least 99 mol% or at least 99.9 mol% of the repeating unit of formula (I), based on the total number of repeating units in the polyphenylene sulfide.

[0058] In one embodiment, the weight-average molecular weight of the polyphenylene sulfide is at least 500 g / mol, preferably from 500 g / mol to 1,000,000 g / mol, and more preferably from 5,000 g / mol to 150,000 g / mol. The weight-average molecular weight can be determined by gel permeation chromatography (GPC) using ASTM D5296 with polystyrene standards. Component c)

[0059] The flame-retardant polymer composition may additionally comprise at least one hardening agent as component c).

[0060] The curing agent is preferably a radical curing agent. It preferably contains a radical initiator and a crosslinking agent.

[0061] Suitable crosslinking agents contain at least two unsaturated, preferably olefinically unsaturated, sites.

[0062] In one embodiment, the radical initiators have peroxide functionality. Numerous organic peroxides are known and commercially available as examples of radical initiators. The radical initiators, including the organic peroxides, can be activated over a wide temperature range. The activation temperature can be described using a parameter known as the half-life (T1 / 2). Typical half-life values ​​of, for example, 0.1 hours, 1 hour, and 10 hours are given in degrees Celsius. For example, a T1 / 2 of 0.1 hours at 143 °C indicates that half of the radical initiator decomposes within 0.1 hours at this temperature. Organic peroxides with a T1 / 2 of 0.1 hours ranging from 118 °C to 228 °C are commercially available. Such peroxides have a half-life of at least 0.1 hours at the specified temperatures.The T1 / 2 values ​​indicate the kinetics of the initial reaction during the crosslinking of the elastomeric polymer, i.e., the decomposition of the peroxide to form a radical-containing intermediate.

[0063] Non-restrictive examples of commercially available organic peroxides for initiating the curing of elastomeric polymers include butyl 4,4-di-(tert-butylperoxy)valerate, tert-butyl peroxybenzoate, di-tert-amyl peroxide, dicumyl peroxide, di(tert-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, tert-butylcumyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hex-3-yne, di-tert-butyl peroxide, 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxonane, 1,1,3,3-tetramethylbutyl hydroperoxide, diisopropylbenzene monohydroperoxide, cumyl hydroperoxide, tert-butyl hydroperoxide, and tert-amyl hydroperoxide. tert-butyl peroxyisobutyrate, tert-amyl peroxyacetate, tert-butyl peroxystearyl carbonate, di(1-hydroxycyclohexyl) peroxide, ethyl 3,3-di(tert-butyl peroxy) butyrate and tert-butyl-3-isopropenyl cumyl peroxide.

[0064] Suitable crosslinking agents are selected from triallyl cyanurate, triallyl isocyanurate, tri(methallyl) isocyanurate, tris(diallylamin)-s-triazine, triallylphosphite, N,N-diallylacrylamide, hexaallylphosphoramide, N,N,N',N'-tetraallyl-terephthalamide, N,N,N',N'-tetraallylmalonamide, trivinyl isocyanurate, 2,4,6-trivinylmethyltrisiloxane, bisolefins, 1,2-polybutadienes and tri(5-norbornene-2-methylene)cyanurate.

[0065] The crosslinking agents preferably contain at least two olefinic unsaturated sites. These unsaturated sites react with the free radical generated at the elastomeric polymer a) and crosslink the elastomer. A commonly used crosslinking agent is triallyl isocyanurate (TAIC).

[0066] If the flame-retardant polymer composition contains component c), then component c) is present in an amount of 0.01 to 15 wt.%, based on the total weight of the flame-retardant polymer composition, preferably 0.1 to 7.5 wt.%, based on the total weight of the flame-retardant polymer composition. Component d)

[0067] To achieve good fire protection properties, it can be advantageous for the flame-retardant polymer composition to additionally comprise, as component d), at least one compound selected from magnesium, calcium, boron, aluminum, antimony, tin, zinc, organophosphorus compounds, organohalogen compounds, and mixtures thereof. Such compounds are known to those skilled in the art.

[0068] In a preferred embodiment, component d) is selected from magnesium hydroxide, aluminium hydroxide, phosphorus compounds and / or nanoclays.

[0069] Suitable phosphorus compounds are generally flame retardants that act by forming a protective "polyphosphoric acid" layer in the condensed phase. Typical phosphorus compounds include ammonium polyphosphate, melamine polyphosphate, red phosphorus, metal phosphinates (DE60115673), phosphoric and phosphonic acid esters, and phosphazenes.

[0070] According to the invention, the flame-retardant polymer composition contains component d) in an amount of 0.5 to 75 wt.%, based on the total weight of the flame-retardant polymer composition, preferably 10 to 70 wt.%, based on the total weight of the flame-retardant polymer composition. Additives and fillers

[0071] In addition to components a), b), c) and d), the polymer composition according to the invention may contain additives and fillers as further components.

[0072] Suitable additives are selected from stabilizers, processing aids, hardening accelerators, pigments, dyes, adhesives, tackifiers and waxes.

[0073] A wide variety of processing aids can be used, including plasticizers and mold release agents. Non-limiting examples of processing aids include carnauba wax, ester plasticizers such as dioctyl sebacate (DOS), fatty acid salts such as zinc stearate and sodium stearate, polyethylene wax, and keramide. In some embodiments, high-temperature processing aids are preferred. Such include, without limitation, linear fatty alcohols such as mixtures of C 10 -C 28 -Alcohols, organosilicones and functionalized perfluoropolyethers. In some embodiments, the compositions contain approximately 0.1 to approximately 25 wt.% processing aids, preferably approximately 0.1 to approximately 15 wt.%.

[0074] Suitable fillers are selected from among organic and inorganic fillers.

[0075] Suitable inorganic fillers include barium sulfate, carbon black, graphite, plastic powders such as PTFE powder, silicon dioxide, titanium dioxide, glass fiber, quartz dust, graphene, and fibers such as mineral fibers, plastic fibers such as ultra-high molecular weight polyethylene fibers, carbon fibers, carbon nanotubes (CNTs), and boron fibers. In various embodiments, fillers such as plastic powders like PTFE powder, graphite, and CNTs are used to improve the wear resistance and other properties of molded parts intended, for example, for use as dynamic sealing elements.

[0076] In a preferred embodiment, fillers can constitute up to approximately 70 wt.% of the total weight of the compositions of the invention. Preferably, the compositions comprise 0.1 to 50 wt.% filler, based on the total weight of the flame-retardant polymer composition. In other embodiments, the filler constitutes 1 to 30 wt.%, based on the total weight of the flame-retardant polymer composition.

[0077] Carbon black is preferably used as a filler. Production

[0078] The flame-retardant polymer composition according to the invention can, as an elastomeric polymer, contain a) at least one uncured curable polymer or at least one cured curable polymer or at least one non-curable polymer or a combination thereof.

[0079] A non-curable polymer exists if the elastomeric polymer a) does not have crosslinkable molecular units (i.e., mutually complementary groups or groups complementary to a hardener that are suitable for crosslinking).

[0080] Within the scope of the invention, complementary curable groups are understood to be groups that can be crosslinked by chemical reaction, i.e., by forming covalent bonds, by salt formation, or by non-covalent interaction.

[0081] The elastomeric polymer a) and polyarylene sulfide b) and optionally other components can be processed into a flame-retardant polymer composition using methods common in the rubber industry. This can be achieved, for example, by means of an internal mixer or a rolling mill at a temperature higher than the plasticization temperature of the elastomer a) and lower than the melting temperature of the polyarylene sulfide b). Other components that can be added include those commonly used in polymer compositions as described above.

[0082] The resulting polymer composition can then be shaped to form a polymer article. A conventional shaping method known to those skilled in the art can be used for this purpose.

[0083] If the polymer composition is thermosetting, it is cured during and / or after shaping. Curing typically takes place at approximately 100 to 250 °C, preferably 150 to 200 °C. A typical curing time ranges from 0.2 to 60 minutes.

[0084] In a first embodiment, the process for producing the curable flame-retardant polymer composition according to the invention comprises the following steps: i) Providing at least one curable elastomer a), ii) Providing at least one polyarylene sulfide b), iii) Mixing the curable elastomer a) with the polyarylene sulfide b) at a temperature that is higher than the plasticization temperature of the elastomer a) and lower than the melting temperature of the polyarylene sulfide b), iv) Addition of a curing agent c), in particular a peroxide curing agent, to the polymer mixture to form a curable elastomer composition, wherein the curable flame-retardant polymer composition additionally comprises as component d) at least one compound of an element selected from magnesium, calcium, boron, aluminium, antimony, tin, zinc, organophosphorus compounds, organohalogen compounds and mixtures thereof.

[0085] In a further embodiment, the process for producing the hardened flame-retardant polymer composition according to the invention comprises the following steps: i) Providing at least one curable elastomer a), ii) Providing at least one polyarylene sulfide b), iii) Mixing the curable elastomer a) with the polyarylene sulfide b) at a temperature that is higher than the plasticization temperature of the elastomer a) and lower than the melting temperature of the polyarylene sulfide b), iv) Addition of a curing agent, in particular a peroxide curing agent, to the polymer mixture to form a curable elastomer composition, wherein the curable flame-retardant polymer composition further comprises as component d) at least one compound of an element selected from magnesium, calcium, boron, aluminium, antimony, tin, zinc, organophosphorus compounds, organohalogen compounds and mixtures thereof, and wherein the polymer composition may further contain additives and fillers, v) Curing of the curable elastomer composition obtained in step iv).

[0086] In a further embodiment, the process for producing the non-curable flame-retardant polymer composition according to the invention comprises the following steps: i) Providing at least one non-curable elastomer a), ii) Providing at least one polyarylene sulfide b), iii) Mixing the non-curable elastomer a) with the polyarylene sulfide b) at a temperature greater than the plasticization temperature of the elastomer a) and less than the melting temperature of the polyarylene sulfide b) to form a non-curable elastomer composition.

[0087] The invention relates to non-hardened, hardened and non-hardenable flame-retardant polymer compositions obtainable by the methods described above.

[0088] A preferred embodiment also comprises flame-retardant polymer compositions according to the invention, comprising a) of 5 to 75 wt.% elastomeric polymer a), b) of 2 to 35 wt% polyarylene sulfide b), c) of 0 to 15 wt.% hardening agent c), d) Compounds of 0 to 50 wt.% selected from compounds of magnesium, calcium, boron, aluminium and phosphorus, e) from 0 to 50 wt.% additives, where the sum of components a), b), c) and d) equals 100 wt.%.

[0089] Another aspect of the invention is the use of a mixture containing component b) and component d), as defined above, as a flame retardant.

[0090] Another object of the invention is the use of a mixture containing component b) and component d), as defined above, for the flame-retardant treatment of component a), as defined above.

[0091] Another aspect of the invention is the use of the flame-retardant polymer composition, as defined above, in automotive parts.

[0092] The invention also relates to the use of a flame-retardant polymer composition according to the invention for the manufacture of a polymer article, selected from spring elements, damping elements, seals, hoses, mats, molded parts, protective coverings, etc., or as a component thereof. The article can, in particular, be designed as a continuous profile. A preferred embodiment is seals, especially O-rings, frame seals, radial shaft seals, bellows, and valve stem seals. Another preferred embodiment is an article in the form of a continuous profile, particularly for windows or as a seal between the frame and the glass.

[0093] The invention further relates to a flame-retardant article. This article can consist entirely of the composition according to the invention, for example as a molded part. Alternatively, such an article can also comprise only part of this composition, for example in the form of a coating on a substrate, such as a fabric.

[0094] The invention also relates to an elastic composite element suitable for damping vibrations and suspension, comprising a base body which is provided at least partially or section by section on its outer surface, optionally on its entire outer surface, with at least one coating of the composition according to the invention.

[0095] In a suitable embodiment, a flame-retardant polymer composition according to the invention is firmly and inseparably bonded to a base body as a coating. The coating can be applied to the base body by fabrication, extrusion, pressing, injection molding, etc. In this way, a bond can be created between the base body and the coating.

[0096] It may also be provided that the base body is equipped with reinforcement, for example fibers, in particular glass fibers, plastic fibers, CFRP fibers, GFRP fibers, a fabric or textile or the like. EXAMPLES

[0097] The following examples serve to illustrate the invention without limiting it in any way.

[0098] The following examples show that the flame retardancy of polyolefinic polymers made from ethylene propylene diene rubbers, magnesium hydroxide and aluminum hydroxide can be significantly improved by poly-p-phenylene sulfide.

[0099] The following initial components were used for the examples. Materials used: EPDM1: Ethylene-propylene rubber, ethylene content 53 wt.%; ENB content 6.0 wt.%, Mooney viscosity 25 (ML1+4@121°C) EPDM2: Ethylene-propylene rubber, oil content 50 wt.%, ethylene content 63 wt.%; ENB content 4.5 wt.%, Mooney viscosity 52 (ML1+4 @ 121°C) PPS: Poly-p-phenylene sulfide, particle size 20 µm Antioxidant: 2,2,4-trimethyl-1,2-dihydroquinoline, polymerized Peroxide: Dicumyl peroxide Coagent: Triallyl cyanurate DOA: Plasticizer, dioctyl adipate Carbon Black: Soot, flame soot N-550 ATH: Aluminum hydroxide, vinylsilanized MDH: Magnesium hydroxide, vinylsilanized SiOx: Silica, vinylsilanized Processing aid 1: Resorcinol bisdiphenyl phosphate (RDP) Processing aid 2: Polyoxyethylene octadecyl ether phosphate

[0100] The composition was produced using an internal mixer and a rolling mill suitable for the production of rubber compounds.

[0101] The tests were carried out on 2 mm thick test plates, which were cured for 5 minutes at 180 °C and then post-heated for 4 hours at 150 °C. The following rubber compounds were produced and tested for various parameters relevant to sealing applications. The compositions are listed in Table 1. Table 1: Ingredients E1* [phr] C1 # [phr] EPDM1 90 90 EPDM 2 oil extended 20 20 Dioctyl adipate 10 10 Carbon Black 4 4 ATH 190 190 MDH 10 10 SiOx 15 15 Antioxidant 1,5 1,5 peroxide 7 7 Coagent 5 5 Processing machine 1 2 2 Processing unit 2 1 1 PPS 25 - [phr] ... parts per hundred rubber* Inventive example, # Comparative example Sealing application:

[0102] Comparison mixture C1: The cross-linked material shows a tensile strength of 14.8 N / mm². 2 and a compression set of 24% after 24 hours at 150°C. The tensile strength according to DIN ISO 34-1: 2016-09 B / a without cutting is 14.0 N / mm², and according to DIN ISO 34-1: 2016-09 B / b with cutting, it is 7.9 N / mm².

[0103] Inventive composition E1: The cross-linked material exhibits a tensile strength of 11.4 N / mm². 2 and a compression set of 16% after 24 hours at 150°C. The tensile strength according to DIN ISO 34-1: 2016-09 B / a without cutting is 15.2 N / mm², and according to DIN ISO 34-1: 2016-09 B / b with cutting, it is 9.3 N / mm². Fire protection testing according to UL 94:

[0104] The flammability test according to UL 94 was carried out and yielded the following result: Classification E1: UL 94 V0 Classification C1: UL 94 V1

[0105] The mixture E1 according to the invention shows a significant improvement in fire protection properties compared to the comparison C1.

Claims

[1] Flame-retardant polymer composition comprising a) 5 to 75 wt.%, based on the total weight of the flame-retardant polymer composition, at least one elastomeric polymer containing at least one polymerized monomer selected under C2-C 30 -Alkylenes, wherein the elastomeric polymer a) is selected from among curable elastomers, b) 2 to 35 wt.%, based on the total weight of the flame-retardant polymer composition, polyarylene sulfide, where component b) is in particle form with a mean particle size in the range of 0.1 to 70 µm, c) at least one hardening agent, d) 0.5 to 75 wt.%, based on the total weight of the flame-retardant polymer composition, at least one compound of an element selected from magnesium, calcium, boron, aluminium, antimony, tin, zinc, organophosphorus compounds, organohalogen compounds and mixtures thereof. [2] Flame-retardant polymer composition according to claim 1, wherein the elastomeric polymer a) is selected from radically curable, in particular peroxide-curable, elastomers. [3] Flame-retardant polymer composition according to any of the preceding claims, wherein the elastomeric polymer a) contains at least one diene monomer polymerized into it. [4] Flame-retardant polymer composition according to any of the preceding claims, wherein the at least one elastomeric polymer contains a) polymerized monomers selected as ethylene, propylene, 1-butene, 1,2-butylene, 2,3-butylene, isobutene, isoprene, styrene, butadiene, 1-hexene, 1-octene, of which different C5-C 20 -Alkenes and mixtures thereof, wherein the elastomeric polymer a) is preferably an ethylene propylene diene rubber. [5] Flame-retardant polymer composition according to any of the preceding claims, wherein the at least one elastomeric polymer a) has a double bond content of 0 to 20 wt.%, in particular 0 to 10 wt.%. [6] A method for producing a curable flame-retardant polymer composition as defined in any one of claims 1 to 5, comprising the steps of: i) Providing at least one curable elastomer a), ii) Providing at least one polyarylene sulfide b), iii) Mixing the curable elastomer a) with the polyarylene sulfide b) at a temperature that is higher than the plasticization temperature of the elastomer a) and lower than the melting temperature of the polyarylene sulfide b), iv) Addition of a curing agent c), in particular a peroxide curing agent, to the polymer mixture to form a curable elastomer composition, wherein the curable flame-retardant polymer composition further comprises as component d) at least one compound of an element selected from magnesium, calcium, boron, aluminium, antimony, tin, zinc, organophosphorus compounds, organohalogen compounds and mixtures thereof. [7] Method for producing a hardened flame-retardant polymer composition comprising the steps: i) Providing at least one curable elastomer a), ii) Providing at least one polyarylene sulfide b), iii) Mixing the curable elastomer a) with the polyarylene sulfide b) at a temperature that is higher than the plasticization temperature of the elastomer a) and lower than the melting temperature of the polyarylene sulfide b), iv) Addition of a curing agent c), in particular a peroxide curing agent, to the polymer mixture to form a curable elastomer composition, wherein the curable flame-retardant polymer composition further comprises as component d) at least one compound of an element selected from magnesium, calcium, boron, aluminium, antimony, tin, zinc, organophosphorus compounds, organohalogen compounds and mixtures thereof, and wherein the polymer composition may further contain additives and fillers, v) Curing of the curable elastomer composition obtained in step iv). [8] Hardened flame-retardant polymer composition obtainable by a process as defined in claim 7. [9] Use of a polyarylene sulfide b) in particle form having a mean particle size in the range of 0.1 to 70 µm as a flame retardant for a polymer composition comprising at least one elastomeric polymer a), as defined in any one of claims 1 to 5. [10] Use of the flame-retardant polymer composition as defined in any one of claims 1 to 5 in automotive parts, for the manufacture of seals, in particular O-rings, frame seals, radial shaft seals, bellows and valve stem seals.