Process for obtaining natural rubber, rubber composition containing natural rubber and use thereof

Abstract

The present invention relates to a process for obtaining age-resistant natural rubber, a rubber composition containing the natural rubber obtained thereby, and the use of the composition for producing consumer goods.

Description

[Technical field]

[0001] The present invention relates to a process for obtaining ageing-resistant natural rubber, to a rubber composition containing the natural rubber obtained thereby, and to the use of this composition for producing consumer goods. [Background technology]

[0002] Many consumer goods in modern daily life are made of rubber, where, in terms of possible stresses and qualities, natural rubber is often superior to synthetically produced rubber. For a long time, natural rubber was obtained mainly from rubber trees of the Hevea genus, and in particular from the Hevea brasiliensis, a plant species mainly cultivated in Asia.

[0003] In recent years, there has been a search for suitable alternatives for obtaining rubber, with particular interest in plants that also grow under the climatic conditions of Central Europe. A known suitable alternative for obtaining natural rubber is the dandelion (genus Taraxacum), in particular the Russian dandelion (Taraxacum kok-saghyz or Taraxacum koksaghyz). Furthermore, natural rubber, very similar to that from Hevea species, can also be obtained from guayule (Parthenium argenatatum).

[0004] Natural rubber derived from Hevea brasiliensis is known to contain, in addition to rubber polymers, a relatively high proportion of proteins and other cellular components or biomolecules, which, derived from the original plant, give it superior qualities and natural stability against aging, but some of these components are also known to cause allergies in humans.

[0005] For synthetic rubbers that do not usually contain protein and other cellular components, it is customary to add aging stabilizers, and many suitable aging stabilizers are known.Examples of suitable aging stabilizers are described in German Patent Application Publication No. 19818564A1, US Patent Application Publication No. 2010063189A, US Patent Application Publication No. 2011303338A, European Patent Application Publication No. 3181628A1, International Patent Application Publication No. 19057703 and European Patent Application Publication No. 3524639A1.

[0006] Additionally, US Pat. No. 4,568,711 discloses a synergistic combination of two antioxidants for natural rubber obtained from guayule. Summary of the Invention [Problem to be solved by the invention]

[0007] It is an object of the present invention to provide a process by which aging-resistant natural rubber can be produced. [Means for solving the problem]

[0008] This object is achieved by a method according to claim 1, the dependent claims defining preferred embodiments. From the natural rubber thus obtained elastic products having a high load-bearing capacity, for example vehicle tyres, can be produced. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The process described herein is a process in which, at the initial stage of obtaining natural rubber from a plant, before the natural rubber is (completely) dried, the obtained plant sap or components thereof (optionally having been previously removed and optionally already purified), in particular natural polyisoprene, is contacted with an aging stabilizer to obtain aging-resistant natural rubber.

[0010] Thus, the method comprises a step (I) in which plant material containing a polymer-containing sap is provided, said sap containing at least natural polyisoprene, in particular cis-1,4-polyisoprene.

[0011] "Plant material" is understood to mean a whole plant of a genera described herein, multiple plants of a genera described herein, multiple plants of different genera described herein, a part of a plant of a genera described herein or parts of a genera described herein, parts of plants of multiple genera described herein (e.g. roots or leaves of each plant), or parts of plants of multiple genera described herein.

[0012] "Sap" is understood according to the present specification to mean any liquid that is present in the plant material or that leaves the plant material by mechanical, thermal or chemical treatment and can be squeezed out, extracted or in some other way removed from the solid plant material. "Sap" always contains - besides water - at least one, preferably several components typical of plants. For utilization in the method according to the invention, sap is used that contains natural polyisoprene as polymer. Thus, plant material containing polyisoprene is involved.

[0013] According to step (II), this polymer-containing sap or at least its components, in particular natural polyisoprene, is obtained (herein also referred to as extracted) from the plant material. The natural rubber contained in the sap may already be solidified in the plant material before extraction. The extraction of the sap and / or its components may be carried out in any suitable manner that allows at least a preferred portion of the sap, in particular the components such as natural polyisoprene, contained in the plant material and / or its components to leave the plant material and be obtained therefrom. The extraction process for obtaining sap and / or its components, in particular natural polyisoprene, can include at least one of the following treatment steps: crushing the plant or plant parts, crushing the plant material, breaking the plant material by mechanical, chemical or thermal treatment, squeezing the plant material, heating the plant material and / or sap and / or its components, mixing the plant material / sap and / or its components with an aqueous solution, mixing the plant material with spores of fungi that decompose the plant material, in particular Phytophthora infestans, mixing the plant material / sap and / or its components with at least one compound, preferably an organic acid, fermenting the plant material aerobically or anaerobicly and / or separating the solid and liquid phases. However, it is preferred that the plant material / sap and / or its components are not mixed with enzymes before the natural polyisoprene solidifies. Preferably, no enzymes are added to the preparation throughout the methods for obtaining polyisoprene described herein.

[0014] Methods for obtaining sap and / or its components are known in principle. For example, suitable methods are described in US2007276112A, WO11139382A2, DE102013107279A1, US2016237254A, EP3371229A1, DE2017118163A1, WO18036825A1 and WO18064484A1.

[0015] Natural polyisoprene can be either cis-1,4-polyisoprene or trans-1,4-polyisoprene. Natural rubber is preferentially mainly cis-1,4-polyisoprene, the proportion of cis-1,4 in the natural rubber polymer generally being greater than 99% by weight.

[0016] According to step (III) of the invention, the sap and / or its components, in particular the natural polyisoprene, obtained is contacted with at least one ageing stabilizer. Here, the contacting of the sap and / or its components with the ageing stabilizer can be carried out by the plant material already being in contact with the ageing stabilizer before extraction, for example by placing the plant either in an aqueous solution containing the ageing stabilizer and in water, by wetting the plant with the ageing stabilizer in liquid form, or by adding the ageing stabilizer as a solid to the plant material before said plant material is broken down. Alternatively, the ageing stabilizer can be added in solid, liquid or dissolved form, for example during the breakup of the plant material by mechanical, chemical or thermal treatment of the plant material. Alternatively, the ageing stabilizer can be contacted after the sap and / or its components have left the plant material. It is also possible to add the ageing stabilizer later to the sap and / or its components, for example before, during or after the treatment step (IV) described above or before or during the treatment step (V) described below, but according to the invention before the natural rubber is dried. Thus, according to the invention, the natural rubber obtained from the plant material is already contacted with an ageing stabilizer before and / or at the latest during drying, i.e. mixed with the ageing stabilizer during drying. Preferably, the ageing stabilizer is contacted with the natural rubber before drying. According to the method of the invention, it is particularly preferred that the ageing stabilizer is contacted with the sap and / or its components, in particular the natural polyisoprene, as soon as possible after the decomposition of the plant material, so that the polymer contained in the sap is protected as effectively as possible from the effects of atmospheric oxygen and other environmental conditions outside the plant material.

[0017] Step (IV) of the method comprises the coagulation and / or flocculation of the polymer contained in the sap, in particular the natural polyisoprene, where the coagulation or flocculation can be carried out by any coagulation or flocculation process known in the art, in particular any of the coagulation or flocculation processes known for rubber. The coagulation / flocculation of polyisoprene preferably occurs in an aqueous solution. This may also mean that the coagulation / flocculation can already occur in the sap still present in the plant material, for example if the plant material has been stored or heat treated, for example by boiling. The coagulation or flocculation of the polymer can also occur during the treatment of the plant material to extract the sap and / or its components, for example by heating to break the plant material or heating the escaping sap, so that step (IV) does not require a separate addition of substances and / or does not require a separate additional procedure. Suitable processes for coagulating / flocculating the polymer are, but are not limited to, for example heating the plant material / sap, adding ions, adding organic solvents, etc.

[0018] As a result of the polymer coagulation or flocculation, the polymer chains originally pre-dissolved and / or emulsified in the sap are converted to a solid state and can be removed from the (preferably aqueous) mixture. Preferably, according to the present invention, the polyisoprene is coagulated by storing or heating the plant material / sap, preferably by heating to boiling in water or an aqueous solution. Upon heating, the polyisoprene contained in the sap coagulates and the resulting flakes of natural rubber can be removed from the other components of the plant material and sap. Any suitable separation process can be used to remove the rubber flakes, such as skimming, sieving, filtering, grinding, drawing off the liquid phase, centrifugation, etc., without being limited to the above processes.

[0019] The natural rubber flakes thus obtained may be washed in one or more intermediate steps according to step (V) in order to additionally purify the natural rubber obtained to remove other components of the plant material. For this purpose, the natural rubber flakes obtained may be contacted with fresh water or an aqueous solution, e.g., transferred therein. According to the invention, step (III), i.e., the addition of the ageing stabilizer, may also be carried out before, during or after such washing step, e.g., by adding the ageing stabilizer to the water / aqueous solution with which the natural rubber flakes are contacted in the washing step. Preferably, the rubber flakes are slurried or suspended or dispersed in the water / aqueous solution, e.g., by stirring or shaking or rolling in a rotating drum.

[0020] In step (VI) of the process, coagulated or agglomerated natural rubber particles (flakes) are obtained from the aqueous mixture / suspension or dispersion. "Obtained" at this point means that there are no additional washing or purification steps after removing the natural rubber flakes from the liquid phase. Again, the invention is not limited to a particular method of removing the solid particles from the aqueous mixture / suspension or dispersion. Instead, any suitable separation process can be used, such as, for example, skimming, sieving, filtration, drawing off the liquid phase, centrifugation, etc.

[0021] As a result of the removal of the natural rubber particles (flakes) from the liquid phase of the aqueous mixture / suspension or dispersion by steps (V) and (VI), they are at least partially, preferably to a large extent, removed from other components of the plant material, so that the natural rubber obtained contains only other components of the plant material, in particular other components of the sap, in amounts of up to a maximum of 30% by weight, preferably up to a maximum of 25% by weight, more preferably up to a maximum of 20% by weight, more preferably up to a maximum of 15% by weight. It should be noted here that the components of the original sap may be reduced to different extents, e.g. inulin, which is present in large proportions in the original sap, is preferentially substantially removed (washed out) from the natural rubber flakes, while, for example, proteins also aggregate to a certain extent themselves during the heating process and can likewise be removed from the aqueous solution when obtaining the rubber flakes. It is clearly preferred that the natural rubber obtained contains, in addition to natural polyisoprene, at least a certain content of other natural components derived from the plant material, such as oligomeric isoprenoids, lipids and proteins.

[0022] The natural rubber obtained from the mixture, suspension or dispersion is optionally dried by a suitable process for further processing. Suitable processes for drying natural rubber are known in the art and include, but are not limited to, air and / or heat treatment. According to the method of the present invention, the aging stabilizer is contacted with the natural rubber at the latest during the drying, and preferably even already prior to this step.

[0023] If the ageing stabilizer is not sufficiently dispersed or incorporated in the resulting natural rubber during or after the above-mentioned treatment steps, this can be achieved by further incorporating the ageing stabilizer in the natural rubber during the treatment, in particular before, during or after step (IV), during or after the (at least one) washing step according to step (V) or after step (VI) or after drying of the rubber, for example by stirring, kneading, grinding, diffusion in a suspension of the natural rubber and ageing stabilizer in water or another suitable process. The said "further incorporating" does not mean the addition / contact of the ageing stabilizer, but rather the homogeneous distribution and incorporation of the agent in the natural rubber material. As already mentioned above, the contact of the ageing stabilizer with the sap / its components is always carried out before the (complete) drying of the natural rubber. The temperature at which the ageing stabilizer is brought into contact with the natural rubber is preferably selected in the range of -25°C to 100°C, preferably in the range of 0°C to 90°C, particularly preferably in the range of 10°C to 80°C. The time should be at least 10 minutes, preferably at least 30 minutes, more preferably at least 1 hour, and if necessary can be extended to a suitable time as desired, for example the contact can be from 1 hour to 7 days, preferably from 2 hours to 3 days, more preferably from 4 hours to 36 hours, more preferably from 4 hours to 10 hours, in order to ensure effective activity of the aging stabilizer even before (complete) drying of the natural rubber.

[0024] The process according to the invention has been described above with reference to the process steps which are or can be carried out in the process according to the invention. However, it should be noted here that some of the process steps can be carried out simultaneously or together, individual steps can be repeated, and these steps do not necessarily have to be carried out in the specified order. However, according to the invention, it is preferred that all of steps (I) to (VI) are carried out before drying the natural rubber according to step (VII). In preferred embodiments of the process, at least some, preferably all of the steps described as optional in the claims or in the above description are carried out as well. It is particularly preferred to carry out a washing step (V) of the process. In preferred embodiments in which washing is carried out, at least a portion of the ageing stabilizer which is incorporated in the natural rubber during at least one of these washing steps is added to the fresh water used to wash the natural rubber flakes. Drying step (VII) is also preferably carried out as a separate process step.

[0025] The incorporation of the aging stabilizer according to step (VIII) is likewise preferably carried out, and such incorporation can take place before, during or after the drying of the natural rubber, or both before and during / after the drying of the natural rubber. Thus, the incorporation of the aging stabilizer into the natural rubber can still be carried out in an aqueous mixture / suspension of the natural rubber flakes after removal of the liquid phase from the natural rubber flakes, but before or during and / or after the actual drying. The incorporation of the aging stabilizer is preferably carried out by stirring, grinding, kneading, diffusion in a suspension of natural rubber and aging stabilizer in water, or any other suitable process over a period of time that allows for efficient incorporation into the finished (dried) natural rubber.

[0026] In principle, the method according to the invention can be applied to all plant species suitable for obtaining natural rubber. Besides the rubber tree (Hevea brasiliensis), examples of such plants are species of the genus Taraxacum or Scorzonera, in particular Taraxacum kok-saghyz, Taraxacum krim-saghyz, Taraxacum bicorne, Taraxacum brevicorniculatum or Scorzonera tau-saghyz, Scorzonera Uzbekistanica, Scorzonera tequesaghyz ... teke-saghyz, Scorzonera hispanica, Scorzonera tau-saghyz or guayule (Parthenium argentatum) or other species such as Apocynum venetum, Asclepias incarnata, Asclepias cornuti, Asclepias sub-lata, Asclepias syrica, Cacalia atriplicifolia, Campanula america, Chicorium intybus, Chondrilla ambigua, ambigua, Chondrilla pauciflora, Crysothamnus nauseousus, Cryptostegia grandiflora, Euphorbia lathyris,lathyris, Lactuca serriola, Lactuca sativa, Parthenium incanum, Pycnanthemum incanum, Solidago altissima, Solidago graminifolia, Solidago leavenworthii, Solidago rigida, Sonchus arvensis, Sonchus oleraceous, Teucreum canadense or Silphium sp. or mixtures of these plants and natural or cultivated hybrids of the aforementioned species.

[0027] According to the invention, the plant material from which the sap and / or components thereof are obtained may be a plant species or a mixture of plant species which grow in particular under Central European climatic conditions and which contain natural polyisoprene in its sap.

[0028] The plant or plant parts are preferably introduced into the process as fresh plant material, optionally after a certain storage period, for example up to one year, but without separately drying the plant or plant material used. Thus, according to the present invention, the plant material, when treated according to the method described herein, preferably still contains at least 10%, preferably at least 25%, more preferably at least 40%, 50%, 60%, 70%, 80%, 90% or even 95% of the moisture it had at harvest. However, it is also possible to use plant material - for example after storage - that has a relatively low moisture content, for example a moisture content of <10%, <5%, <3%, <2% or <1%.

[0029] According to the invention, the plant is preferably from the genus Taraxacum or Scorzonera, in particular the Russian dandelion, for example Taraxacum kok-saghyz, Taraxacum krim-saghyz, Taraxacum bicorne, Taraxacum brevicorniculatum or from Scorzonera tau-saghyz, Scorzonera Uzbekistanica, Scorzonera teke-saghyz, Scorzonera hispanica, Scorzonera hispanica, Scorzonera tau-saghyz or mixtures of these plants, preferably Taraxacum kok-saghyz, Scorzonera tau-saghyz, Scorzonera Uzbekistanica, Scorzonera teke-saghyz or mixtures or hybrids thereof, particularly preferably Taraxacum kok-saghyz or Scorzonera tau-saghyz. However, according to the invention, it is particularly preferred to obtain natural rubber from the dandelion (genus Taraxacum), in particular from the Russian dandelion, preferably from Taraxacum kok-saghyz or Taraxacum krim-saghyz, with Taraxacum kok-saghyz being particularly preferred. Hybrids containing Taraxacum kok-saghyz or Taraxacum krim-saghyz are also particularly suitable.For the process according to the invention, the plant material used can also be only parts of the whole plant, in particular only those parts which have a particularly high concentration of natural polyisoprene, for example in the case of the dandelion only the roots of the plant.

[0030] The ageing stabilizer used can in principle be any known ageing stabilizer, preferably selected from antioxidants, metal ion complexing agents and / or free radical scavengers, and various ageing stabilizers can also be used as mixtures or in combination.

[0031] Preferably, the aging stabilizer is butylated hydroxytoluene (BHT), at least one stereoisomeric form of vitamin E or a derivative thereof, NC 1~12 -Alkyl-N'-phenyl-p-phenylenediamines, such as 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), diaryl-p-phenylenediamines (DTPD), 4,4'-bis(C 1~12-alkylamino)triphenylamines, 7,8-dimethylisoalloxazine or compounds containing 7,8-dimethylisoalloxazine as a structural building block, such as riboflavin, p-phenylenediamine, p-di(nitroso)arenes, such as poly-p-di(nitroso)benzene, oligomerized 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ), styrenated diphenylamine (DDA), cumylated diphenylamine, zinc salts of 4- and 5-methylmercaptobenzimidazole, 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,2'-methylenebis(6-tert-butyl)-p-cresol, poly(dicyclopentadiene-co-p-cresol), n-octadecyl beta-( 4-hydroxy-3,5-di-tert-butylphenyl)propionate, 2,2'-methylenebis(4-methyl-6-tert-butylphenol) (BPH), 2-methyl-4,6-bis(octylsulfanylmethyl)phenol, thiobisphenol, 4,4'-bis(1,1-dimethylbenzyl)diphenylamine (CDPA), octylated diphenylamine (ODPA), phenyl-a-naphthylamine (PAN), phenyl-beta-naphthylamine (PBN), tris(nonylphenyl)phosphite, sodium hypophosphite, 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ), 2-mercaptobenzimidazole (MBI), methyl-2-mercaptobenzimidazole (MMBI), or any combination of the foregoing. Preferably, the aging stabilizer is selected from the group consisting of butylated hydroxytoluene (BHT), vitamin E in the form of tocopherol or tocotrienol, in particular desmethyl-tocotrienol, gamma-tocotrienol, delta-tocotrienol or a mixture of gamma-tocotrienol and delta-tocotrienol (e.g. "DMT3" from Tricutis), the zinc salt of di-n-butyldithiocarbamic acid, one of the phenylenediamines mentioned above, as well as the amines of formula (I) [ka] (where n=1, 2, 3, 4, 5, 6, 7, 8 or 9) The butylation reaction products of p-cresol and dicyclopentadiene by butylation ...

[0032] More preferably, the ageing stabilizer is selected from butylated hydroxytoluene (BHT), vitamin E in the form of tocopherols or tocotrienols, in particular desmethyl-tocotrienol, gamma-tocotrienol, delta-tocotrienol or a mixture of gamma-tocotrienol and delta-tocotrienol (e.g. "DMT3" from Tricutis) and compounds according to formula (I) (wherein n=1, 2, 3, 4, 5, 6, 7, 8 or 9) (e.g. Wingstay® L from Omnova Solutions), more preferably from BHT or compounds according to formula (I), in particular Wingstay® L from Omnova Solutions. Particularly preferably, the ageing stabilizer used is at least butylated hydroxytoluene (BHT), optionally combined with others as mentioned above. When mixtures are used, preferred mixtures are vitamin E in the form of tocopherol or tocotrienol and / or BHT in combination with a compound according to formula (I), especially Wingstay® L from Omnova Solutions.

[0033] The amount of ageing stabilizer used is calculated so that the ageing stabilizer is available on contact with the polymer-containing sap in an amount that results in a total amount of ageing stabilizer in the finished (dried) natural rubber of at least 0.01 phr, preferably from 0.05 to 5 phr, more preferably from 0.10 to 3.5 phr, especially preferably from 0.25 to 2 phr, and most preferably from 0.4 to 1 phr, based on the finished (dried) rubber.

[0034] The unit "phr" (parts per hundred parts rubber by weight) used herein is the customary designation of quantities for mixing recipes in the rubber industry. The parts by weight addition of individual materials herein are always based on 100 parts by weight of the total mass of all rubbers present in the mixture.

[0035] The ageing stabilizer can be added to the plant material / sap / its components in any suitable form. Depending on the state of matter of the ageing stabilizer itself, it can be added to the plant material / polymer-containing sap and / or its components in the form of a powder, suspension, liquid or solution. Particular preference here is given to - if the ageing stabilizer itself is solid - very finely ground, suspended in a liquid or dissolved in a suitable organic or aqueous solvent before contacting with the sap. If the ageing stabilizer is finely ground, it is preferred that it has a maximum particle size of 1000 μm. If the ageing stabilizer is dissolved, it is preferred to use an aqueous solvent or a suitable organic solvent. If an aqueous solvent is used, water or for example an aqueous buffer solution can be used, preferred as organic solvents are ethanol, isopropanol or process oils (vegetable oils or mineral oils). Mixtures of suitable aqueous and organic solvents can also be used. As the ageing stabilizer is insoluble in water, if an organic solvent is used, it is possible that the ageing stabilizer will crystallize again when added to the aqueous system used to obtain or purify the natural rubber. If the ageing stabilizer itself exists as a pure substance in liquid form, it can be used directly in this form or, if necessary, diluted with another suitable liquid, for example one of the solvents mentioned above.

[0036] Natural rubber obtained from the sap and mixed with aging stabilizers can be used to make a rubber composition from which rubber articles can be made.

[0037] In addition to the components derived from the natural source of natural rubber, further components may be added to the rubber composition in order to make the composition particularly suitable for the intended processing purposes. Thus, at least one of the following components may be added to the rubber composition according to the invention: (i) a further type of rubber selected from natural rubber or synthetic rubber; (ii) a filler, preferably carbon black and / or silica; (iii) a plasticizer, (iv) an activator; (v) adhesives; (vi) pigments, (vii) vulcanization accelerators, (viii) vulcanization retarders, (ix) a further cross-linking agent, (x) Other admixtures.

[0038] All these additives are well known in the art of rubber manufacture. The rubber mixture may additionally contain further ingredients such as further aging stabilizers, processing aids, ASMs, coupling agents, reinforcing resin systems, etc.

[0039] The natural rubber produced by the method of the present invention can be used alone or in rubber mixtures to produce rubber articles.Preferred rubber articles are those that can withstand mechanical stress and at the same time have elasticity.Such articles are preferably selected from tires, especially vehicle tires or tire parts, bellows, conveyor belts, air springs, belts, drive belts, such as V-belts, toothed belts, flat belts, V-ribbed belts, hoses, shoe soles, rubber rings, medical articles and tubes.

[0040] For the manufacture of tires, the rubber composition may optionally contain, in addition to natural polyisoprene, at least one further type of rubber. It may be selected from the group consisting of natural polyisoprene, and / or synthetic polyisoprene, and / or epoxidized polyisoprene, and / or butadiene rubber, and / or butadiene-isoprene rubber, and / or solution-polymerized styrene-butadiene rubber, and / or emulsion-polymerized styrene-butadiene rubber, and / or styrene-isoprene rubber, and / or liquid rubber with a molecular weight Mw of more than 20,000 g / mol, and / or halobutyl rubber, and / or polynorbornene, and / or isoprene-isobutylene copolymers, and / or ethylene-propylene-diene rubber, and / or nitrile rubber, and / or chloroprene rubber, and / or acrylate rubber, and / or fluororubber, and / or silicone rubber, and / or polysulfide rubber, and / or epichlorohydrin rubber, and / or styrene-isoprene-butadiene terpolymers, and / or hydrogenated acrylonitrile-butadiene rubber, and / or hydrogenated styrene-butadiene rubber. Preferably, it is selected from other types of natural rubber, for example from Hevea brasiliensis, synthetic polyisoprene, and / or butadiene rubber, and / or solution-polymerized styrene-butadiene rubber, and / or emulsion-polymerized styrene-butadiene rubber. Said synthetic rubber may optionally be functionalized with suitable groups. This type of rubber mixture is particularly suitable for the manufacture of environmentally friendly, low rolling resistance pneumatic vehicle tires, in particular their treads.

[0041] Possible additional rubber components in the manufacture of industrial rubber articles such as bellows, conveyor belts, belts, drive belts and hoses as well as shoe soles are in particular nitrile rubber, hydrogenated acrylonitrile-butadiene rubber, chloroprene rubber, butyl rubber, halobutyl rubber or ethylene-propylene-diene rubber, which are used everywhere in everyday life, for example in elevators, the automotive industry, the raw materials industry, the food industry and medical technology.

[0042] If a rubber mixture is used for the manufacture of rubber articles, it is preferred that said rubber mixture contains natural polyisoprene and natural rubber produced by the process according to the invention in an amount of 0.1 to 99 phr, preferably 0.5 to 90 phr, particularly preferably 5 to 85 phr. Other types of rubber that can be used are either other natural rubbers, for example natural rubber from the rubber tree (Hevea brasiliensis), or synthetic rubbers, for example preferably butadiene rubber and / or styrene-butadiene rubber, which can optionally be hydrogenated. However, according to the invention, it is also possible that the rubber used for the rubber composition contains only, i.e. consists of (up to 100 phr), natural rubber produced by the process according to the invention.

[0043] To produce rubber articles, the described polymers in the rubber composition can be at least partially covalently bonded to each other through a crosslinking agent (in any combination of natural and synthetic rubbers). This means that the crosslinking agent forms a covalent bond with at least two polymer chains, so that the polymer chains are covalently bonded to each other through the crosslinking agent. Crosslinking agents suitable for this purpose are known in the art.

[0044] When conventional vulcanization is carried out, the vulcanization of the rubber composition can be carried out in the presence of sulfur and / or sulfur donors using vulcanization accelerators, some of which can simultaneously function as sulfur donors. The accelerators can be selected from the group consisting of thiazole accelerators, and / or mercapto accelerators, and / or sulfenamide accelerators, and / or thiocarbamate accelerators, and / or thiuram accelerators, and / or thiophosphate accelerators, and / or thiourea accelerators, and / or xanthate accelerators, and / or guanidine accelerators, and / or morpholine derivatives. It is preferable to use sulfenamide accelerators selected from the group consisting of N-cyclohexyl-2-benzothiazole sulfenamide (CBS), and / or N,N-dicyclohexylbenzothiazole-2-sulfenamide (DCBS), and / or N-tert-butyl-2-sulfenamide (TBBS).

[0045] The sulfur donor material used can be any sulfur donor material known to those skilled in the art.

[0046] Further network-forming systems available, for example, under the trade names Vulkuren®, Duralink® or Perkalink® or as described in WO 2010 / 049216 A2 can also be used in the rubber composition.

[0047] The rubber composition preferably also contains at least one filler, such as silica, carbon black, and optionally further known polar and / or non-polar fillers, such as aluminosilicates and other silicates, chalk, kaolin, starch, magnesium oxide, zinc oxide, clay minerals, such as bentonite, titanium dioxide, and / or rubber gels, as well as fibers (e.g. aramid fibers, glass fibers, carbon fibers, cellulose fibers), carbon nanotubes (CNTs, including individual CNTs, so-called hollow carbon fibers (HCFs) and modified CNTs containing one or more functional groups, such as hydroxyl groups, carboxyl groups, carbonyl groups, etc.), and / or graphite, and / or graphene, and / or so-called "carbon-silica dual-phase fillers".

[0048] When the filler is at least one type of silica, the rubber composition preferably contains 1 to 300 phr, particularly preferably 1 to 200 phr, and most preferably 1 to 180 phr of the at least one type of silica.

[0049] When the filler is at least one type of carbon black, the rubber composition preferably contains 1 to 200 phr, particularly preferably 1 to 170 phr, and most preferably 1 to 100 phr of at least one type of carbon black.

[0050] The silica may be any silica known to those skilled in the art that is suitable as a filler for tire rubber mixtures. It is preferable to use precipitated silica. 2 / g, preferably 35 to 350m 2 / g, particularly preferably 85 to 320 m 2 / g nitrogen surface area (BET surface area) (in accordance with DIN ISO9277 and DIN66132) and 30-400 m 2 / g, preferably 60 to 330m 2 / g, particularly preferably 80 to 300m 2 It is particularly preferred to use finely divided precipitated silica having a CTAB surface area (according to ASTM D3765) of 100 / g.

[0051] When the rubber composition contains carbon black, any type of carbon black known to those skilled in the art is considered. However, it is preferable to use carbon black having an iodine adsorption amount according to ASTM D1510 of 30 to 250 g / kg, preferably 30 to 180 kg / g, and a DBP number according to ASTM D2414 of 80 to 200 mL / 100 g, preferably 100 to 200 mL / 100 g, particularly preferably 115 to 200 mL / 100 g.

[0052] The rubber composition of the present invention may also contain a mixture of two or more of the above mentioned fillers.

[0053] Silane coupling agents can be used as adhesion promoters between inorganic materials, such as glass beads, glass chips, glass surfaces, glass fibers or oxide fillers, preferably silica, and organic polymers, such as thermosets, thermoplastics or elastomers, or as crosslinkers and surface modifiers for oxide surfaces.

[0054] Silane coupling agents that can be used herein include any silane coupling agent known to those skilled in the art for use in rubber mixtures. Such coupling agents known from the prior art are difunctional organosilanes that have at least one alkoxy, cycloalkoxy or phenoxy group as a leaving group on the silicon atom and, as another functional group, a group that can participate in a chemical reaction with the double bond of the polymer, if necessary after cleavage. The latter group can include, for example, the following chemical groups: -SCN, -SH, -NH2 or -Sx- (where x=2 to 8).

[0055] Carbon black coupling agents may also be used.

[0056] In the context of the present invention, zinc oxide is not considered to be one of the fillers, although it may be present in the rubber composition, preferably in combination with stearic acid.

[0057] Furthermore, the rubber composition preferably also comprises further additives.

[0058] The further additives may essentially be - in addition to zinc oxide (ZnO) and stearic acid - plasticizers, vulcanisation accelerators, antiozonants, further ageing stabilizers, reinforcing resins including HMMM / HMT, tackifying resins, mastication aids, binding systems, reinforcing resins and further activators or processing aids, such as fatty acid salts, such as zinc soaps and fatty acid esters and derivatives thereof, such as zinc stearate or zinc complexes, such as zinc ethylhexanoate.

[0059] Known plasticizers include aromatic, naphthenic or paraffinic mineral oil plasticizers, such as MES (Mild Extraction Solvates), or RAE (Residual Aromatic Extract), or TDAE (Treated Distillate Aromatic Extract), or Rubber-Liquids (RTL), or Biomass-Liquids (BTL), or Factice, or Plasticizer Resins, or Liquid Polymers (such as Liquid BR).

[0060] The proportion of the total amount of further additives is preferably between 3 and 150 phr, preferably between 3 and 100 phr, particularly preferably between 5 and 100 phr.

[0061] The invention further provides the use of the rubber compositions described for the manufacture of elastic materials, such as bellows, conveyor belts, air springs, belts, drive belts, such as V-belts, toothed belts, flat belts, V-ribbed belts, hoses, shoe soles, rubber rings, tactile sensors for medical or robotic applications, medical articles, tubes or especially vehicle tyres, including parts thereof. The invention therefore further provides elastic materials, the manufacture of which comprises the use of at least one rubber composition according to the invention.

[0062] "Vehicle tires" should be understood to mean pneumatic vehicle tires and solid rubber tires, including industrial and construction vehicle tires, truck tires, car tires and motorcycle tires. The rubber composition of the present invention can also be used for the manufacture of certain parts of such tires, such as the tread or body mixtures, such as sidewalls, inner liners, apexes, belts, shoulders, squeegees, further inserts (e.g. runflats), belt profiles, carcasses, bead reinforcements and / or bandages. EXAMPLES

[0063] Example 1: Addition of various aging stabilizers Various aging stabilizers, as shown in Table 1, were contacted with natural rubber for an incubation period of 8 hours. The rubbers produced were stored at 70°C for up to 14 days. The stability to aging was evaluated by gel permeation chromatography to determine the number average (M n ) and weighted average (M w ) was determined for the resulting rubber by determining the molecular weight. From this the polydispersity can be calculated. Comparing these values ​​over time gives a measure of the aging of the rubber.

[0064] [Table 1]

[0065] [Table 2]

[0066] (1) Polydispersity (M w / Mn) (2) LNR = natural rubber derived from dandelion, in this case Taraxacum kok-saghyz (3)IR: Synthetic rubber (4) NR: Natural rubber derived from the rubber tree (Hevea brasiliensis)

[0067] The degree of stabilization against aging was determined by the ratio of number average molecular weight at 70°C, Mn fresh / Mn 14 days.

[0068] result: LNR without anti-aging: 2.55: Molecular weight loss, anti-aging LNR with BHT: 2.0: Average aging LNR with Wingstay®: 1.7: Average aging IR: 1.46: Slightly aged NR: 1.03: Virtually no molecular weight degradation, almost no material aging

[0069] Example 2: Quality characteristics of aging-resistant natural rubber compositions To prepare rubber compositions suitable for the manufacture of tires, the further components shown in Table 2 were incorporated into the natural rubber compositions 1 to 6 prepared according to Example 1 and likewise into the natural rubber mixed with a vitamin E derivative according to batches 11 and 12. For this purpose, 100 parts by weight of each of the rubber compositions 1 to 6 and 11 and 12 (see Table 2) were mixed with the further components (parts by weight) shown in Table 3 and processed to form a rubber material.

[0070] Table 2: Batch Number 1. LNR without anti-aging, fresh 2. LNR without anti-aging, aged at 70℃ for 14 days 3. LNR containing BHT, fresh 4. LNR containing BHT, aged for 14 days at 70℃ 5. LNR, Fresh, including Wingstay® 6. LNR with Wingstay®, aged 14 days at 70°C 11. LNR with DMT3, Fresh 12. LNR containing DMT3, aged for 14 days at 70°C LNR = Natural rubber from dandelion, in this case Taraxacum kok-saghyz

[0071] [Table 3]

[0072] The results of the quality test and the load test of the produced rubber composition are shown in Table 4.

[0073] [Table 4]

[0074] [Table 5]

[0075] Tabular data: Decision method Shore A hardness at room temperature and 70°C using a durometer according to DIN ISO 7619-1 [Shore A] Rebound resilience [%] at room temperature and 70°C according to DIN 53512 or ISO 4662 or ASTM D1054 Stress values ​​(elastic modulus) at 100%, 200% and 300% elongation at room temperature according to DIN 53504 [MPa] Tensile strength at room temperature according to DIN 53504 [MPa] Elongation at break at room temperature according to DIN 53504 [%] Fracture energy density measured in a tensile test according to DIN 53504. The fracture energy density is the amount of work required to break a specimen based on its volume [J / cm 3 ] Wear at room temperature according to DIN 53516 or the new DIN / ISO 4649 [mm 3 ]

[0076] Quality test results show that the addition of aging stabilizers to natural rubber compositions has a positive effect on the aging of natural rubber as well as the properties of rubbers made from this material.

[0077] Regarding the ratings in Table 4: (A) The smaller the decrease in the difference in resilience, the more favorable the trade-off between rolling resistance and wet grip of a vehicle tire; (B) The less the decrease in tensile strength after aging, the better the durability. (C) The smaller the decrease in fracture energy density after aging, the better the durability. (D) The lower the DIN wear after aging, the longer the tire will last. In addition, the present application relates to the invention described in the claims, but may also include the following as other aspects. 1. A process for obtaining ageing-resistant natural rubber, comprising the steps of: (I) providing a plant material comprising a polymer-containing sap, said polymer-containing sap comprising at least natural polyisoprene; (II) treating the plant / plant material such that the sap and / or its components are separated from the remaining plant tissue; (III) contacting the plant material / the polymer-containing sap and / or components thereof with at least one aging stabilizer; (IV) coagulating and / or agglomerating the natural polyisoprene to provide natural rubber flakes; (V) optionally washing the natural rubber flakes; (VI) obtaining the natural rubber flakes from the extract / wash solution; (VII) optionally drying the natural rubber; (VIII) optionally incorporating said aging stabilizer into said natural rubber. wherein said contacting of said aging stabilizer according to step (III) occurs before or at the latest during said drying of said natural rubber. 2. The method according to claim 1, carried out using fresh, optionally stored but not separately dried plant material. 3. The method according to claim 1 or 2, wherein step (III) is carried out before, during or after step (II), before, during or after step (IV) and / or before or during step (V), but in any case before or at the latest during step (VII). 4. The polymer-containing sap and / or its components are from the genus Taraxacum or Scorzonera, in particular the Russian dandelion, such as Taraxacum kok-saghyz, Taraxacum krim-saghyz, Taraxacum bicorne, Taraxacum brevicorniculatum or from Scorzonera tau-saghyz, Scorzonera Uzbekistanica, Scorzonera tau-saghyz ... The plant may be selected from the group consisting of Taraxacum taka-saghyz, Scorzonera hispanica, Scorzonera tau-saghyz or mixtures of said plants, preferably Taraxacum kok-saghyz, Scorzonera tau-saghyz, Scorzonera Uzbekistanica, Scorzonera teke-saghyz or mixtures or natural or cultivated hybrids thereof, and more preferably Taraxacum kok-saghyz, Taraxacum krimsaghiz or mixtures of said plants, The method according to any one of 1 to 3 above, wherein the extract is from at least one plant material selected from Taraxacum kok-saghyz (Taraxacum krim-saghyz) or a mixture or hybrid involving these, particularly preferably from at least Taraxacum kok-saghyz (Taraxacum kok-saghyz). 5. The aging stabilizer is selected from the group consisting of butylated hydroxytoluene (BHT), vitamin E or its derivatives in at least one stereoisomeric form, NC 1~12 -Alkyl-N'-phenyl-p-phenylenediamines, such as 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), diaryl-p-phenylenediamines (DTPD), 4,4'-bis(C 1~12 -alkylamino)triphenylamines, 7,8-dimethylisoalloxazine or compounds containing 7,8-dimethylisoalloxazine as a structural building block, such as riboflavin, p-phenylenediamine, p-di(nitroso)arenes, such as poly-p-di(nitroso)benzene, oligomerized 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ), styrenated diphenylamine (DDA), cumylated diphenylamine, zinc salts of 4- and 5-methylmercaptobenzimidazole, 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,2'-methylenebis(6-tert-butyl)-p-cresol, poly(dicyclopentadiene-co-p-cresol), n-octadecyl beta-(4-hydroxy-3,5-di-tert-butylphenyl)propionate, 2,2'-di-tert-butyl-4-ethylphenol, 2,2'-methylenebis(6-tert-butyl)-p-cresol, poly(dicyclopentadiene-co-p-cresol), n-octadecyl beta-(4-hydroxy-3,5-di-tert-butylphenyl)propionate, , 2'-methylenebis(4-methyl-6-tert-butylphenol) (BPH), 2-methyl-4,6-bis(octylsulfanylmethyl)phenol, thiobisphenol, 4,4'-bis(1,1-dimethylbenzyl)diphenylamine (CDPA), octylated diphenylamine (ODPA), phenyl-a-naphthylamine (PAN), phenyl-beta-naphthylamine (PBN), tris(nonylphenyl)phosphite, sodium hypophosphite, 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ), 2-mercaptobenzimidazole (MBI), methyl-2-mercaptobenzimidazole (MMBI) or any combination of the foregoing, butylated hydroxytoluene (BHT), vitamin E in the form of a tocopherol or tocotrienol, a zinc salt of di-n-butyldithiocarbamic acid, and a compound of formula (I) [ka] (where n=1, 2, 3, 4, 5, 6, 7, 8 or 9) 5. The method according to any one of claims 1 to 4, wherein the aging stabilizer is preferably selected from a mixture of butylated reaction products of p-cresol and dicyclopentadiene by the method according to claim 1, and it is particularly preferable to use at least butylated hydroxytoluene (BHT) as the aging stabilizer. 6. The method according to any one of 1 to 5 above, wherein the plant material comprises at least Russian dandelion, in particular Taraxacum kok-saghyz, and the at least one ageing stabilizer is selected from BHT, Vitamin E or a derivative thereof and a compound according to formula (I) (wherein n=1, 2, 3, 4, 5, 6, 7, 8 or 9). 7. The method according to any one of claims 1 to 6, wherein the ageing stabilizer is added to the plant material / the polymer-containing sap and / or components thereof in such an amount that it is present in the resulting natural rubber in a total amount of at least 0.01 phr, preferably between 0.05 and 5 phr, more preferably between 0.10 and 3.5 phr, particularly preferably between 0.25 and 2 phr, and most preferably between 0.4 and 1 phr. 8. The method according to any one of claims 1 to 7, wherein the ageing stabilizer is added to the plant material / the polymer-containing sap and / or its - optionally purified - components in the form of a powder, suspension, liquid or solution. 9. The contacting of the aging stabilizer with the natural rubber is carried out under the following conditions: (i) at a temperature in the range of -25°C to 100°C, preferably 0°C to 90°C, and particularly preferably 10°C to 80°C; (ii) by mechanical agitation, preferably by stirring, rolling, grinding or kneading or a combination thereof or by diffusion in a suspension of the rubber and the aging stabilizer in water; (iii) for a period of at least 10 minutes, preferably at least 30 minutes, and more preferably at least 1 hour; The method according to any one of 1 to 8 above, wherein the method is carried out under at least one of the following conditions. 10. A rubber composition containing a natural rubber produced by the method according to any one of 1 to 9 above. 11. The following additives: (i) a further type of rubber selected from natural rubber or synthetic rubber; (ii) a filler, preferably carbon black and / or silica; (iii) a plasticizer, (iv) an activator; (v) adhesives; (vi) pigments, (vii) vulcanization accelerators, (viii) vulcanization retarders, (ix) a further cross-linking agent, (x) Other admixtures 11. The rubber composition according to claim 10, further comprising at least one of the following: 12. Use of a rubber composition according to claim 10 or 11 for the manufacture of a rubber article. 13. A rubber article made from the rubber composition according to 10 or 11 above, preferably selected from a tire, in particular a vehicle tire or tire part, a bellows, a conveyor belt, an air spring, a belt, a drive belt, such as a V-belt, a toothed belt, a flat belt, a V-ribbed belt, a hose, a shoe sole, a rubber ring, a medical article or a tube.

Claims

1. A process for obtaining ageing resistant natural rubber, comprising the steps of: (I) providing a plant material comprising polymer-containing sap, said polymer-containing sap comprising at least natural polyisoprene; (II) treating the plant / plant material such that the sap and / or its components are separated from the remaining plant tissue; (III) contacting said plant material / sap containing said polymer and / or components thereof with at least one aging stabilizer; (IV) coagulating and / or agglomerating the natural polyisoprene to provide natural rubber flakes; (V) optionally washing the natural rubber flakes; (VI) obtaining the natural rubber flakes from the extract / wash liquor; (VII) optionally drying the natural rubber; (VIII) optionally incorporating said aging stabilizer into said natural rubber. wherein said contacting of said aging stabilizer according to step (III) occurs before or at the latest during said drying of said natural rubber; The plant material is selected from the dandelion genus (Taraxacum sp.), and the at least one aging stabilizer is selected from butylated hydroxytoluene (BHT), vitamin E or a derivative thereof, and a compound represented by the formula (I): 【Chemistry 1】 wherein n=1, 2, 3, 4, 5, 6, 7, 8 or 9.

2. 10. The method of claim 1 performed with plant material that has not been separately dried.

3. 3. The process according to claim 1 or 2, wherein step (III) is carried out before, during or after step (II), before, during or after step (IV) and / or before or during step (V), but in each case before or at the latest during step (VII).

4. The method according to any one of claims 1 to 3, wherein the polymer-containing sap and / or components thereof are extracted from at least one plant material selected from Russian dandelion.

5. The method according to any one of claims 1 to 4, wherein the plant material comprises at least Taraxacum kok-saghyz.

6. 6. The method according to any one of claims 1 to 5, wherein the aging stabilizer is added to the plant material / the polymer-containing sap and / or components thereof in an amount such that it is present in the resulting natural rubber in a total amount of at least 0.01 phr.

7. 7. The method according to any one of claims 1 to 6, wherein said ageing stabilizer is added to said plant material / sap containing polymer and / or its optionally purified components in the form of a powder, suspension, liquid or solution.

8. The contacting of the aging stabilizer with the natural rubber is performed under the following conditions: (i) at a temperature of −25° C. to 100° C.; (ii) by mechanical agitation, rolling, grinding or kneading or a combination thereof or by diffusion in a suspension of the rubber and the aging stabilizer in water; (iii) for a period of at least 10 minutes; The method according to any one of claims 1 to 7, wherein the method is carried out under at least one of the following conditions:

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