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

Abstract

To provide a rubber composition containing aging-resistant natural rubber, the use of the composition for producing consumer goods, and a rubber article produced from the composition.SOLUTION: The present invention provides a rubber composition containing natural rubber produced by a process for obtaining aging-resistant natural rubber, in which, at an early point when the natural rubber is obtained from the plants, an aging stabilizer is contacted with the plant sap obtained or its ingredients, in particular with natural polyisoprene, before the natural rubber has been (completely) dried. Preferably, the plant material is selected from the genus Taraxacum sp., and the aging stabilizer is butylated hydroxytoluene (BHT), vitamin E, or a derivative thereof.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a method for obtaining aging-resistant natural rubber, a rubber composition containing the natural rubber obtained thereby, and the use of this composition for manufacturing consumer goods. [Background technology]

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

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

[0004] Natural rubber derived from the Para rubber tree is known to contain relatively high proportions of proteins and other cellular components or biomolecules in addition to rubber polymers. While these components derived from the original plant impart excellent quality and natural stability against aging to natural rubber, some of these components are also known to cause allergies in humans.

[0005] In the case of synthetic rubber that does not typically contain proteins 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, U.S. Patent Application Publication No. 2010063189A, U.S. Patent Application Publication No. 2011303338A, European Patent Application Publication No. 3181628A1, International Publication No. 19057703, and European Patent Application Publication No. 3524639A1.

[0006] Furthermore, U.S. Patent No. 4,568,711 discloses a synergistic combination of two antioxidants for natural rubber derived from guayule. [Overview of the project] [Problems that the invention aims to solve]

[0007] The object of the present invention is to provide a method for producing aging-resistant natural rubber. [Means for solving the problem]

[0008] This objective is achieved by the method described in claim 1, and the dependent claims specify preferred embodiments. From the natural rubber thus obtained, elastic products having high load-bearing capacity, such as vehicle tires, can be manufactured. [Modes for carrying out the invention]

[0009] The method described herein is a method for obtaining aging-resistant natural rubber by contacting the resulting plant sap or its components (which have been optionally removed in advance and optionally already purified), particularly natural polyisoprene, with an aging stabilizer at an early stage in obtaining natural rubber from a plant, before the natural rubber is completely dried.

[0010] Therefore, the method comprises step (I) providing a plant material containing polymer-containing sap, the sap containing at least natural polyisoprene, particularly cis-1,4-polyisoprene.

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

[0012] "Sap" is understood, as used herein, to mean any liquid present in plant material or that can be extracted from plant material by mechanical, thermal, or chemical treatment, and can be squeezed, extracted, or otherwise removed from solid plant material. "Sap" always contains at least one, preferably more, components typical of plants, in addition to water. For use in the methods according to the present invention, sap containing natural polyisoprene as a polymer is used. Thus, plant material containing polyisoprene is involved.

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

[0014] Methods for obtaining sap and / or its components are, in principle, publicly known. For example, suitable methods are described in U.S. Patent Publication No. 2007276112A, International Publication No. 11139382A2, German Patent Publication No. 102013107279A1, U.S. Patent Publication No. 2016237254A, European Patent Publication No. 3371229A1, German Patent Publication No. 2017118163A1, International Publication No. 18036825A1, and International Publication No. 18064484A1.

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

[0016] According to step (III) of the present invention, the obtained sap and / or its components, in particular natural polyisoprene, is contacted with at least one aging stabilizer. Here, contact between the sap and / or its components and the aging stabilizer can be carried out by, for example, placing the plant in either an aqueous solution or water containing the aging stabilizer, wetting the plant with the aging stabilizer in liquid form, or adding the aging stabilizer to the plant material as a solid before the plant material is destroyed, provided that the plant material has already been in contact with the aging stabilizer before extraction. Alternatively, the aging stabilizer can be added in solid, liquid or dissolved form, for example, during the destruction of the plant material by mechanical, chemical or thermal treatment of the plant material. Alternatively, the aging stabilizer can be contacted after the sap and / or its components have been removed from the plant material. It is also possible to add the aging stabilizer to the sap and / or its components later, for example, before, during, or after the aforementioned processing step (IV) or before or during the following processing step (V), but according to the present invention, before the natural rubber is dried. Therefore, according to the present invention, the natural rubber obtained from plant material is already in contact with the aging stabilizer before drying and / or at the latest during drying, i.e., mixed with the aging stabilizer during drying. It is preferable that the aging stabilizer be in contact with the natural rubber before drying. According to the method of the present invention, it is particularly preferable that the aging stabilizer be in contact with the sap and / or its components, especially natural polyisoprene, as soon as possible after the plant material has decomposed, so that the polymer contained in the sap is protected as effectively as possible from the effects of oxygen in the atmosphere and other environmental conditions other than the plant material.

[0017] Step (IV) of the method comprises the coagulation and / or aggregation of polymers contained in the sap, particularly natural polyisoprene. Here, coagulation or aggregation can be carried out by any coagulation or aggregation process known in the art, particularly coagulation or aggregation processes known for rubber. Coagulation / aggregation of polyisoprene is preferably carried out in an aqueous solution. This also means that, for example, if the plant material is stored or heat-treated, such as by boiling, coagulation / aggregation may already occur in the sap that is still present in the plant material. Coagulation or aggregation of polymers can also be caused when the plant material is treated to extract the sap and / or its components, for example by heating to break down the plant material or heating the sap from which it is extracted, so that step (IV) does not require the separate addition of a substance and / or requires a separate additional procedure. Suitable processes for coagulating / aggregating polymers include, but are not limited to, heating of the plant material / sap, addition of ions, addition of organic solvents, etc.

[0018] As a result of polymer coagulation or aggregation, polymer chains that were originally pre-dissolved and / or emulsified in the sap change to a solid state and can be removed from the mixture (preferably aqueous). Preferably, according to the present invention, polyisoprene is coagulated by storing or heating the plant material / sap, preferably by heating it to a boil in water or an aqueous solution. Upon heating, the polyisoprene contained in the sap aggregates, and the resulting natural rubber flakes can be removed from the other components of the plant material and sap. Any suitable separation process, such as skimming, sieving, filtration, grinding, liquid phase extraction, centrifugation, etc., can be used to remove the rubber flakes, but is not limited to the above process.

[0019] The natural rubber flakes thus obtained can be washed in one or more intermediate steps according to step (V) to further purify the obtained natural rubber and remove other components of the plant material. For this purpose, the obtained natural rubber flakes can be brought into contact with fresh water or aqueous solution, for example, by moving them into it. According to the present invention, step (III), i.e., the addition of the aging stabilizer, can also be carried out before, during, or after such a washing step, for example, by adding the aging stabilizer to the water / aqueous solution into which the natural rubber flakes are brought in the washing step. Preferably, the rubber flakes are slurryed, suspended, or dispersed in water / aqueous solution, for example by stirring or shaking or by rotation in a rotating drum.

[0020] In step (VI) of the method, the solidified or aggregated natural rubber particles (flakes) are obtained from the aqueous mixture / suspension or dispersion. At this point, “obtained” means that there are no additional washing or purification steps after the natural rubber flakes have been removed from the liquid phase. Again, the present invention is not limited to any particular method for removing solid particles from the aqueous mixture / suspension or dispersion. Instead, any suitable separation process can be used, such as skimming, sieving, filtration, liquid phase withdrawal, or centrifugation.

[0021] As a result of the removal of natural rubber particles (flakes) from the liquid phase of the aqueous mixture / suspension or dispersion by processes (V) and (VI), they are at least partially, preferably substantially removed from other components of the plant material, so that the resulting natural rubber contains other components of the plant material, especially other components of the sap, in an amount of up to 30% by weight, preferably up to 25% by weight, more preferably up to 20% by weight, even more preferably up to 15% by weight. Here, the components of the original sap can be reduced to different degrees. For example, inulin, which is present in a large proportion in the original sap, is preferentially and substantially removed (washed away) from the natural rubber flakes. On the other hand, it should be noted that, for example, proteins also aggregate to some extent during the heating process and can be removed from the aqueous solution when obtaining the rubber flakes as well. It is clearly preferred that the resulting natural rubber contains, in addition to natural polyisoprene, other natural components derived from the plant material, such as oligomeric isoprenoids, lipids and proteins, at least in a certain content.

[0022] The natural rubber obtained from the mixture, suspension or dispersion is optionally dried by a process suitable 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 anti-aging agent is in contact with the natural rubber at least during drying, preferably already before this step.

[0023] During or after the above-mentioned processing steps, if the anti-aging agent is not sufficiently dispersed or incorporated into the resulting natural rubber, this can be achieved by further incorporating the anti-aging agent into the natural rubber, for example, by stirring, kneading, grinding, diffusion in a suspension of natural rubber and anti-aging agent in water or another suitable process, during processing, especially before, during or after step (IV), during or after the (at least one) washing step by step (V) or after step (VI) or after drying of the rubber. The "further incorporation" does not mean the addition / contact of the anti-aging agent, but means the uniform distribution and incorporation of the agent in the natural rubber material. As already mentioned above, the contact between the anti-aging agent and the sap / its components is always carried out before the (complete) drying of the natural rubber. The temperature at which the anti-aging agent 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 needs to be at least 10 minutes, preferably at least 30 minutes, more preferably at least 1 hour, and can be extended to an appropriate time as desired if necessary. For example, the contact can be 1 hour to 7 days, preferably 2 hours to 3 days, more preferably 4 hours to 36 hours, even more preferably 4 hours to 10 hours, even before the (complete) drying of the natural rubber to ensure the effective activity of the anti-aging agent.

[0024] The present method according to the present invention has been described above with reference to the processing steps that are or may be performed by the present method. However, it should be noted that some of the processing steps may be performed simultaneously or together, individual steps may be repeated, and these steps do not necessarily have to be performed in a specified order. However, according to the present invention, it is preferable that all of steps (I) to (VI) are performed before drying the natural rubber by step (VII). In preferred embodiments of the method, at least some, preferably all, of the steps described as optional in the claims or above are performed in the same manner. It is particularly preferable to perform a washing step (V) of the method. In preferred embodiments in which washing is performed, at least some of the aging stabilizers incorporated into the natural rubber are added to the fresh water used to wash the natural rubber flakes during at least one of these washing steps. The drying step (VII) is also preferably performed as a separate processing step.

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

[0026] Basically, the method according to the present invention can be applied to all plant species suitable for obtaining natural rubber. Besides the Para rubber tree (Hevea brasiliensis), examples of such plants include the genera Taraxacum sp. or Scorzonera sp., particularly Taraxacum kok-saghyz, Taraxacum krim-saghyz, Taraxacum bicorne, Taraxacum brevicorniculatum, or Scorzonera tau-saghyz, Scorzonera Uzbekistanica, and Scorzonera tekesaghyz. 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, Chrysothamnus nauseousus, Cryptostegia grandiflora, Euphorbia lacilis, (EuphorbiaExamples include plants of the Asteraceae family such as *Lathyris*, *Lactuca serriola*, *Lactuca sativa*, *Parthenium incanum*, *Pycnanthemum incanum*, *Solidago altissima*, *Solidago graminifolia*, *Solidago leavenworthii*, *Solidago rigida*, *Sonchus arvensis*, *Sonchus oleraceous*, *Teucreum canadense*, or the genus *Silphium*, or mixtures of these plants, and natural or cultivated hybrids of the aforementioned species.

[0027] According to the present invention, the plant material from which sap and / or its components are obtained may be a plant species or a mixture of plant species that grow particularly under the climatic conditions of Central Europe and whose sap contains natural polyisoprene.

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

[0029] According to the present invention, the plant is preferably from the genus Taraxacum (Taraxacum sp.) or Scorzonera (Scorzonera sp.), particularly Russian dandelions, such as Taraxacum kok-saghyz, Taraxacum krim-saghyz, Taraxacum bicorne, Taraxacum brevicorniculatum, or Scorzonera tau-saghyz, Scorzonera Uzbekistanica, Scorzonera teke-saghyz, Scorzonera hispanica From hispanica), Scorzonera tau-saghyz, or a mixture of these plants, preferably selected from Taraxacum kok-saghyz, Scorzonera tau-saghyz, Scorzonera Uzbekistanica, Scorzonera teke-saghyz, or a mixture or hybrid thereof, particularly preferably selected from Taraxacum kok-saghyz, or Scorzonera tau-saghyz. However, according to the present invention, it is particularly preferable to obtain natural rubber from the genus Taraxacum, especially from the Russian dandelion, and more 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 method according to the present invention, the plant material used may be only a part of the whole plant, in particular only the part with a particularly high concentration of natural polyisoprene, for example, in the case of dandelions only the roots of the plant.

[0030] The aging stabilizer used can essentially be any known aging stabilizer. The aging stabilizer is preferably selected from antioxidants, metal ion complexing agents and / or free radical scavengers, and various aging stabilizers can be used as a mixture or in combination.

[0031] Preferably, the anti-aging stabilizer is butylated hydroxytoluene (BHT), at least one stereoisomer of vitamin E or a derivative thereof, NC 1~12 -Alkyl-N'-phenyl-p-phenylenediamine, e.g., 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-phenylenediamine (DTPD), 4,4'-bis(C 1~12-alkylamino)triphenylamine, 7,8-dimethylisoaloxazine or compounds containing 7,8-dimethylisoaloxazine as a structural building block, e.g., riboflavin, p-phenylenediamine, p-di(nitroso)arenes, e.g., poly-p-di(nitroso)benzene, oligomerized 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ), styrene-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-octadecylbeta-( Selected from 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-α-naphthylamine (PAN), phenyl-beta-naphthylamine (PBN), tris(nonylphenyl)phosphite, sodium hypophosphate, 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ), 2-mercaptobenzimidazole (MBI), methyl-2-mercaptobenzimidazole (MMBI), or any combination thereof. Preferably, the anti-aging stabilizer is butylated hydroxytoluene (BHT), vitamin E in the form of tocopherol or tocotrienol, particularly desmethyl-tocotrienol, gamma-tocotrienol, delta-tocotrienol or a mixture of gamma-tocotrienol and delta-tocotrienol (e.g., Tricutis' "DMT3"), zinc salt of di-n-butyldithiocarbamate, one of the aforementioned phenylenediamines, and formula (I) [ka] (Here, n = 1, 2, 3, 4, 5, 6, 7, 8, or 9) The mixture is selected from a mixture of butylation reaction products of p-cresol and dicyclopentadiene (for example, a product sold by Omnova Solutions under the name Wingstay® L).

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

[0033] The amount of aging stabilizer used is calculated such that, based on the finished dried rubber, a total amount of at least 0.01 phr, preferably 0.05 to 5 phr, more preferably 0.10 to 3.5 phr, particularly preferably 0.25 to 2 phr, and most preferably 0.4 to 1 phr of aging stabilizer is available when it comes into contact with the polymer-containing sap in the amount obtained in the finished (dried) natural rubber.

[0034] The unit "phr" (parts per 100 parts by weight of rubber) as used herein is a conventional expression of quantities in the rubber industry for mixing recipes. The amount of individual substances added is always based on 100 parts by weight of the total mass of rubber present in the mixture.

[0035] Antioxidants can be added to plant materials / sap / components in any suitable form. Depending on the state of the antioxidant itself, it can be added to plant materials / polymer-containing sap and / or components in the form of a powder, suspension, liquid, or solution. Particularly preferred here is—if the antioxidant itself is solid—to grind the antioxidant very finely, suspend it in a liquid, or dissolve it in a suitable organic solvent or aqueous solvent before contacting it with the sap. If the antioxidant is ground finely, a maximum particle size of 1000 μm is preferred. If the antioxidant 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 can be used, and preferred organic solvents are ethanol, isopropanol, or process oil (vegetable oil or mineral oil). A mixture of a suitable aqueous solvent and an organic solvent can also be used. Since antioxidants are insoluble in water, if an organic solvent is used, the antioxidant may recrystallize when added to an aqueous system used to obtain or purify natural rubber. If the aging stabilizer itself exists as a pure substance in liquid form, it can be used directly in this form, or it can be diluted as needed with another suitable liquid, such as one of the aforementioned solvents.

[0036] Natural rubber, obtained from tree sap and mixed with aging stabilizers, can be used to produce rubber compositions capable of manufacturing rubber articles.

[0037] In order to make the composition particularly suitable for its intended processing purpose, additional components may be added to the rubber composition in addition to components derived from natural sources of natural rubber. Therefore, at least one of the following components may be added to the rubber composition according to the present invention: (i) Further types of rubber selected from natural rubber or synthetic rubber, (ii) Filler, preferably carbon black and / or silica, (iii) Plasticizers, (iv) an activator; (v) adhesive, (vi) pigments, (vii) vulcanization accelerator, (viii) vulcanization retarder, (ix) Further crosslinking agents, (x) Other mixtures.

[0038] All of these additives are well known in the technical field of rubber manufacturing. The rubber mixture may also contain additional components (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 for the manufacture of rubber articles. Preferred rubber articles are those that can withstand mechanical stress and are elastic at the same time. 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 at least one further type of rubber in addition to natural polyisoprene. This can 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 exceeding 20,000 g / mol, and / or halobutyl rubber, and / or polynorbornene, and / or isoprene-isobutylene copolymer, 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 polymer, and / or hydrogenated acrylonitrile-butadiene rubber, and / or hydrogenated styrene-butadiene rubber. Preferably, this is selected from other types of natural rubber, such as natural rubber derived from the Para rubber tree (Hevea brasiliensis), synthetic polyisoprene, and / or butadiene rubber, and / or solution-polymerized styrene-butadiene rubber, and / or emulsion-polymerized styrene-butadiene rubber. The synthetic rubber may optionally be functionalized with appropriate groups. This type of rubber mixture is environmentally friendly and particularly suitable for the manufacture of pneumatic vehicle tires, especially their treads, which have low rolling resistance.

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

[0042] When a rubber mixture is used in the manufacture of rubber articles, the rubber mixture preferably contains natural polyisoprene and contains natural rubber produced by the method according to the present invention in an amount of 0.1 to 99 phr, preferably 0.5 to 90 phr, and particularly preferably 5 to 85 phr. Other types of rubber that may be used are other natural rubbers, such as natural rubber derived from Hevea brasiliensis, or synthetic rubbers, for example, preferably butadiene rubber and / or styrene-butadiene rubber, which may be optionally hydrogenated. However, according to the present invention, the rubber used for the rubber composition may contain, i.e., consist only of, natural rubber produced by the method according to the present invention (up to 100 phr).

[0043] For the manufacture of rubber articles, the polymers described in the rubber composition can be at least partially covalently bonded to one another via a crosslinking agent (in any combination of natural rubber and synthetic rubber). This means that the crosslinking agent forms covalent bonds with at least two polymer chains, and as a result, the polymer chains are covalently bonded to one another via the crosslinking agent. Crosslinking agents suitable for this purpose are known in the art.

[0044] In conventional vulcanization, the vulcanization of the rubber composition can be carried out in the presence of sulfur and / or a sulfur donor using a vulcanization accelerator, and some vulcanization accelerators can simultaneously function as sulfur donors. The accelerator 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 xanthogenic acid accelerators and / or guanidine accelerators and / or morpholine derivatives. It is preferable to use a sulfenamide accelerator 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 substance used may be any sulfur donor substance known to those skilled in the art.

[0046] For example, further network-forming systems available under trade names such as Vulkuren®, Duralink®, or Perkalink®, or network-forming systems described in International Publication No. 2010 / 049216 A2, can also be used in rubber compositions.

[0047] The rubber composition preferably contains at least one filler such as silica and carbon black, and optionally further known polar and / or nonpolar 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 and fibers (e.g., aramid fibers, glass fibers, carbon fibers, cellulose fibers), carbon nanotubes (CNTs containing 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)), and / or graphite and / or graphene and / or so-called "carbon-silica two-phase fillers".

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

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

[0050] Silica may be a type of silica known to those skilled in the art, suitable as a filler for tire rubber mixtures. Precipitated silica is preferred. 35-400 m 2 / g, preferably 35-350m 2 / g, particularly preferably 85-320m 2 Nitrogen surface area (BET surface area) per gram (according to DIN ISO9277 and DIN66132), and 30-400 m 2 / g, preferably 60-330m 2 / g, particularly preferably 80-300m 2 It is particularly preferable to use finely ground precipitated silica having a CTAB surface area of ​​1 / g (according to ASTM D3765).

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

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

[0053] Silane coupling reagents can be used as adhesion promoters between inorganic materials, such as glass beads, glass fragments, glass surfaces, glass fibers, or oxide fillers, preferably silica, and organic polymers, such as thermosetting resins, thermoplastic resins, or elastomers, or as crosslinking agents and surface modifiers for oxide surfaces.

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

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

[0056] In relation to the present invention, zinc oxide is not considered a filler, but it can preferably be present in the rubber composition in combination with stearic acid.

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

[0058] Further additives may, in essence, be - zinc oxide (ZnO) and stearic acid - plasticizers, vulcanization accelerators, ozone degradation inhibitors, further aging stabilizers, reinforcing resins containing HMMM / HMT, tackifying resins, mixing 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 their derivatives, 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 Extract Solvate), RAE (Residual Aromatic Extract), or TDAE (Treated Distillate Aromatic Extract), or rubber-liquid oil (RTL), or biomass-liquid oil (BTL), or Factis, or plasticizer resins, or liquid polymers (such as liquid BR).

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

[0061] The present invention further provides the use of the described rubber compositions 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 in particular vehicle tires (including their components). Accordingly, the present invention also further provides elastic materials, the manufacture of which involves the use of at least one of the rubber compositions of the present invention.

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

Examples

[0063] Example 1: Addition of various anti-aging agents Various anti-aging agents shown in Table 1 were brought into contact with natural rubber over a heat retention time of 8 hours. The rubber produced was stored at 70 °C for a maximum of 14 days. The stability against aging was determined for the resulting rubber by determining the number average (M n ) and weight average (M w ) molecular weights of the natural rubber polymer by gel permeation chromatography. From this, the polydispersity can be calculated. By comparing these values over time, a measure of the aging of the rubber is obtained.

[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 Para rubber tree (Hevea brasiliensis)

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

[0068] result: LNR without anti-aging: 2.55: Decreased molecular weight, aging LNR including BHT: 2.0: Average aging LNR: 1.7: Average aging, including Wingstay (registered trademark) IR:1.46: Slightly aged NR:1.03: There is virtually no decrease in molecular weight, and the material shows almost no aging.

[0069] Example 2: Quality characteristics of an aging-resistant natural rubber composition To produce rubber compositions suitable for tire manufacturing, the additional components shown in Table 2 were incorporated into natural rubber compositions 1-6, prepared according to Example 1, and similarly into natural rubber mixed with vitamin E derivatives according to batches 11 and 12. For this purpose, 100 parts by weight each of rubber compositions 1-6 and 11 and 12 (see Table 2) were mixed with the additional components (by weight) shown in Table 3 and processed to form rubber materials.

[0070] Table 2: Batch number 1. LNR without anti-aging, Fresh 2. LNR without anti-aging measures, aging in 14 days / 70°C 3. LNR containing BHT, fresh 4. LNR containing BHT, aged for 14 days at 70°C. 5. LNR including Wingstay (registered trademark), Fresh 6. LNR containing Wingstay®, aged for 14 days at 70°C. 11. LNR containing DMT3, fresh 12. LNR containing DMT3, aged for 14 days at 70°C. LNR = Dandelion, in this case natural rubber derived from Taraxacum kok-saghyz.

[0071] [Table 3]

[0072] Table 4 shows the results of quality tests and load tests on the manufactured rubber composition.

[0073] [Table 4]

[0074] [Table 5]

[0075] Table data: Decision method Shore A hardness at room temperature and 70°C, measured using a durometer compliant with DIN ISO7619-1. • Rebound elasticity [%] at room temperature and 70°C in accordance with DIN53512, ISO4662, or ASTM D1054 • Stress values ​​(modulus of elasticity) [MPa] at 100%, 200%, and 300% elongation at room temperature, in accordance with DIN53504. • Tensile strength at room temperature [MPa] according to DIN53504 • Elongation at break at room temperature in accordance with DIN53504 [%] • Fracture energy density measured by a tensile test in accordance with DIN 53504. Fracture energy density is the work required to fracture the specimen relative to its volume [J / cm²]. 3 ] • Wear at room temperature [mm] in accordance with DIN53516 or the new DIN / ISO4649 3 ]

[0076] The results of quality tests indicate that the addition of aging stabilizers to natural rubber compositions has a positive effect not only on the aging of natural rubber but also on the properties of rubber produced from this material.

[0077] Regarding the evaluation in Table 4: (A) The smaller the decrease in the difference in rebound elasticity, the more favorable the trade-off between rolling resistance and wet grip of the 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 less DIN wear there is after aging, the longer the tire will last. While this application relates to the invention described in the claims, it may also encompass the following other embodiments. 1. A method for obtaining aging-resistant natural rubber, (I) A step of providing a plant material containing polymer-containing sap, wherein the polymer-containing sap contains at least natural polyisoprene, (II) A step of processing the plant / plant material such that the sap and / or its components are separated from the remaining plant tissue, (III) A step of contacting the plant material / the polymer-containing sap and / or its components with at least one aging stabilizer. (IV) A step of coagulating and / or agglomerating the natural polyisoprene to obtain natural rubber flakes. (V) Optionally, a step of washing the natural rubber flakes. (VI) Steps to obtain the natural rubber flakes from the extract / washing solution, (VII) Optionally, a step of drying the natural rubber, (VIII) A step of optionally incorporating the aging stabilizer into the natural rubber. A method comprising, wherein the contact of the aging stabilizer by step (III) is performed before or at the latest during the drying of the natural rubber. 2. The method according to 1 above, wherein the method is carried out using fresh, selectively stored, but not separately dried plant material. 3. The method described in 1 or 2 above, wherein step (III) is performed before, during, or after step (II), before, during, or after step (IV), and / or before or during step (V), but in any case is performed before or at the latest during step (VII). 4. The polymer-containing sap and / or its components are derived from the genus Taraxacum (Taraxacum sp.) or Scorzonera (Scorzonera sp.), particularly from Russian dandelions, such as Taraxacum kok-saghyz, Taraxacum krim-saghyz, Taraxacum bicorne, Taraxacum brevicorniculatum, or from Scorzonera tau-saghyz, Scorzonera Uzbekistanica, Scorzonera takasaghyz. From Taraxacum taka-saghyz), Scorzonera hispanica, Scorzonera tau-saghyz, or a mixture of the above plants, preferably Taraxacum kok-saghyz, Scorzonera tau-saghyz, Scorzonera Uzbekistanica, Scorzonera teke-saghyz, or a mixture thereof, or natural or cultivated hybrids, more preferably at least Taraxacum kok-saghyz, Taraxacum krimsaghii, The method according to any one of claims 1 to 3 above, wherein the extract is obtained from at least one plant material selected from krim-saghyz or mixtures thereof or hybrids involving thereof, particularly preferably from at least Taraxacum kok-saghyz. 5. The anti-aging stabilizer is butylated hydroxytoluene (BHT), at least one stereoisomer of vitamin E or a derivative thereof, NC 1~12 -Alkyl-N'-phenyl-p-phenylenediamine, e.g., 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-phenylenediamine (DTPD), 4,4'-bis(C 1~12 -alkylamino)triphenylamine, 7,8-dimethylisoaloxazine or compounds containing 7,8-dimethylisoaloxazine as a structural building block, e.g., riboflavin, p-phenylenediamine, p-di(nitroso)arenes, e.g., poly-p-di(nitroso)benzene, oligomerized 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ), styrene-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-octadecylbeta-(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-α-naphthylamine (PAN), phenyl-beta-naphthylamine (PBN), tris(nonylphenyl) phosphite, sodium hypophosphate, 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ), 2-mercaptobenzimidazole (MBI), methyl-2-mercaptobenzimidazole (MMBI), or any combination thereof, selected from butylated hydroxytoluene (BHT), vitamin E in the form of tocopherol or tocotrienol, zinc salt of di-n-butyldithiocarbamate, and formula (I) [ka] (Here, n = 1, 2, 3, 4, 5, 6, 7, 8, or 9) The method according to any one of claims 1 to 4, wherein the aging stabilizer is preferably selected from a mixture of butylation reaction products of p-cresol and dicyclopentadiene, and it is particularly preferable to use at least butylated hydroxytoluene (BHT) as the aging stabilizer. 6. The method according to any one of claims 1 to 5 above, wherein the plant material comprises at least Russian dandelion, particularly Taraxacum kok-saghyz, and at least one aging stabilizer is selected from BHT, vitamin E or its derivatives and compounds of formula (I) (where 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 aging stabilizer is added to the plant material / polymer-containing sap and / or its components in an amount such that it is present in the resulting natural rubber in a total amount of at least 0.01 phr, preferably 0.05 to 5 phr, more preferably 0.10 to 3.5 phr, particularly preferably 0.25 to 2 phr, and most preferably 0.4 to 1 phr. 8. The method according to any one of items 1 to 7 above, wherein the aging stabilizer is added in the form of a powder, suspension, liquid, or solution to the plant material / polymer-containing sap and / or its components, which are optionally purified. 9. The contact of the aging stabilizer with the natural rubber is subject to the following conditions: (i) The temperature range is -25°C to 100°C, preferably 0°C to 90°C, and particularly preferably 10°C to 80°C. (ii) Mechanical stirring, preferably by stirring, rolling, crushing or kneading or a combination thereof, or by diffusion in a suspension of rubber and aging stabilizer in water. (iii) The period of time is at least 10 minutes, preferably at least 30 minutes, and more preferably at least 1 hour. The method described in any one of items 1 to 8 above, carried out under at least one of the following conditions. 10. A rubber composition containing natural rubber produced by any one of the methods described in items 1 to 9 above. 11. The following additives: (i) Further types of rubber selected from natural rubber or synthetic rubber, (ii) Filler, preferably carbon black and / or silica, (iii) Plasticizers, (iv) an activator; (v) adhesive, (vi) pigments, (vii) vulcanization accelerator, (viii) vulcanization retarder, (ix) Further crosslinking agents, (x) Other mixtures The rubber composition according to 10, further comprising at least one of the above. 12. Use of the rubber composition described in 10 or 11 above for the manufacture of rubber articles. 13. Rubber articles manufactured from the rubber compositions described in 10 or 11 above, preferably selected from tires, particularly 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, or tubes.

Claims

1. A method for obtaining aging-resistant natural rubber, (I) A step of providing a plant material containing polymer-containing sap, wherein the polymer-containing sap contains at least natural polyisoprene, (II) A step of processing the plant / plant material such that the sap and / or its components are separated from the remaining plant tissue, (III) A step of contacting the plant material / the polymer-containing sap and / or its components with at least one aging stabilizer. (IV) A step of coagulating and / or agglomerating the natural polyisoprene to obtain natural rubber flakes. (V) Optionally, a step of washing the natural rubber flakes. (VI) Steps to obtain the natural rubber flakes from the extract / washing solution, (VII) Optionally, a step of drying the natural rubber, (VIII) A step of optionally incorporating the aging stabilizer into the natural rubber. The contact of the aging stabilizer in step (III) is performed before or at the latest during the drying of the natural rubber. The plant material is selected from the genus Taraxacum sp., and at least one aging stabilizer is butylated hydroxytoluene (BHT), vitamin E or a derivative thereof, and formula (I) 【Chemistry 1】 Use for the manufacture of rubber articles of a rubber composition containing natural rubber produced by the method described above, selected from compounds by (where n = 1, 2, 3, 4, 5, 6, 7, 8, or 9).

2. The use according to claim 1, wherein the method is carried out using plant material that has not been dried separately.

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

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

6. The use according to any one of claims 1 to 5, wherein the aging stabilizer is added to the plant material / polymer-containing sap and / or its components in such an amount as at least 0.01 phr in total in the natural rubber obtained.

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

8. The contact of the aging stabilizer with the natural rubber is under the following conditions: (i) The temperature range is from -25°C to 100°C. (ii) by mechanical stirring, rolling, grinding or kneading or a combination thereof, or by diffusion in a suspension of rubber and aging stabilizer in water. (iii) It must last for a period of at least 10 minutes. The use according to any one of claims 1 to 7, carried out under at least one of the following.

9. The rubber composition contains the following additives: (i) Further types of rubber selected from natural rubber or synthetic rubber, (ii) Filler, (iii) Plasticizer, (iv) an activator; (v) Adhesive, (vi) Pigments, (vii) vulcanization accelerator, (viiii) vulcanization retarder, (ix) Further crosslinking agents, (x) Other mixtures The use according to any one of claims 1 to 8, further comprising at least one of the above.

10. The use according to any one of claims 1 to 9, wherein the rubber article is selected from tires, bellows, conveyor belts, air springs, belts, drive belts, hoses, shoe soles, rubber rings, medical articles, or tubes.

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