EXTENDED SEALING GELS, PROCESS FOR PRODUCTION THEROF AND USE THEROF IN SEALING COMPOUNDS FOR SELF-SEALING TYRES

Abstract

A sealing compound comprising an inventive extended sealing gel, a process for producing this sealing compound, the use of sealing gels in sealing compounds, and the use of sealing gel-containing sealing compounds in tyres

Claims

1. A sealing gel i) in the form of a mixture comprising a diene rubber gel (A) formed by emulsion polymerization of at least one conjugated diene in the presence of at least one crosslinker (I) and a second diene rubber gel (B) formed by emulsion polymerization of at least one conjugated diene in the presence of at least one crosslinker (II), or ii) formed by emulsion polymerization of at least one conjugated diene in the presence of at least one crosslinker (I) and/or in the presence of at least one crosslinker (II), wherein: the at least one crosslinker (I) are selected from: acrylates and methacrylates of polyhydric C.sub.2-C.sub.20 alcohols, and the at least one crosslinker (II) are selected from: compounds having two or more vinyl, allyl or isopropenyl groups or one maleimide unit, wherein the sealing gel further comprises an extender compound incorporated therein, and wherein said extender compound is a liquid elastomer and/or a lubricant oil.

2. A sealing gel i) in the form of a mixture comprising a diene rubber gel (A) formed by emulsion polymerization of at least one conjugated diene in the presence of at least one crosslinker (I) and a second diene rubber gel (B) formed by emulsion polymerization of at least one conjugated diene in the presence of at least one crosslinker (II), or ii) formed by emulsion polymerization of at least one conjugated diene in the presence of at least one crosslinker (I) and in the presence of at least one crosslinker (II), where crosslinkers (I) are acrylates and methacrylates of polyhydric C.sub.2-C.sub.20 alcohols, and crosslinkers (II) are compounds having two or more vinyl, allyl or isopropenyl groups or one maleimide unit, wherein the sealing gel further comprises an extender compound incorporated therein, and wherein said extender compound is a liquid elastomer, a lubricant oil, a factice and/or mixtures thereof.

3. The sealing gel according to claim 1, wherein: the extender compound is at least one of a paraffinic oil, a hydrogenated or non-hydrogenated naphthenic oil, an aromatic or DAE (Distilled Aromatic Extracts) oil, a MES (Medium Extracted Solvates) oil, a Treated Distillate Aromatic Extracts (TDAE) oil, a mineral oil, a vegetable oil and/or oligomers and mixtures thereof.

4. The sealing gel according to claim 1, wherein: the extender compound is a lubricant oil based on polybutene, preferably polyisobutylene (PIB)-based oils, or ether-, ester-, phosphate- and sulphonate-based plasticizers.

5. The sealing gel according to claim 2, wherein the extender compound is factice.

6. The sealing gel according to claim 1, wherein: said sealing gel has a Mooney viscosity (ML1+4) @ 100 C. of less than 100 MU.

7. The sealing gel according to claim 1, wherein the diene rubber gel (A), has a Mooney viscosity (ML1+4) @ 100 C. of 170 MU to 195 MU and the diene rubber gel (B) has a Mooney viscosity (ML1+4) @ 100 C. of 75 MU to 110 MU.

8. The sealing gel according to claim 1, wherein the at least one conjugated diene is selected from: 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, isoprene or chloroprene.

9. The sealing gel according to claim 1, wherein further monomers are polymerized in the emulsion polymerization of the at least one conjugated diene, wherein said further monomers are selected from: 1,3-butadiene, vinylaromatics, styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, -methylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 4-tert-butylstyrene or tert-butoxystyrene, acrylonitrile, isoprene, esters of acrylic acid and methacrylic acid, tetrafluoroethylene, vinylidene fluoride, hexafluoropropene, 2-chlorobutadiene, 2,3-dichlorobutadiene, carboxylic acids containing double bonds, acrylic acid, methacrylic acid, maleic acid itaconic acid, hydroxyl compounds containing double bonds, hydroxyethyl methacrylate, hydroxyethyl acrylate or hydroxybutyl methacrylate, amine-functionalized (meth)acrylates, glycidyl methacrylate, acrolein, N-vinyl-2-pyrrolidone, N-allylurea, N-allylthiourea, secondary amino (meth)acrylates, 2-tert-butylaminoethyl methacrylate, 2-tert-butylaminoethylmethacrylamide, and/or vinylic heteroaromatics including 2-, 4-vinylpyridine and 1-vinylimidazole.

10. The sealing gel according to claim 9, wherein the at least one conjugated diene is 1,3-butadiene and the further monomer is styrene and wherein said emulsion polymerization occurred at 5 C. to 20 C.

11. Sealing compounds comprising: at least one sealing gel according to claim 1, in an amount of 45 phr to 100 phr, resin (C) in an amount of 10 phr to 60 phr, and a natural rubber or synthetic rubber (E), such as copolymers based on conjugated diolefins from a group comprising 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, 3-butyl-1,3-octadiene, 2-phenyl-1,3-butadiene or mixtures thereof, more preferably from a group comprising natural cis-1,4-polyisoprene, synthetic cis-1,4-polyisoprene, 3,4-polyisoprene, polybutadiene, 1,3-butadiene-acrylonitrile copolymer and mixtures thereof, in an amount of less than 55 phr, based in each case on the total amount of sealing gel and natural and/or synthetic rubber (E) in the sealing compound.

12. Process for producing sealing compounds of claim 11, comprising the steps of mixing the sealing gel, the natural or synthetic rubber (E) and the resin (C), wherein the sealing gel and the natural or synthetic rubber (E) are mixed in the form of their lattices.

13. Sealing compounds exhibiting improved adhesion and cohesion properties comprising a sealing gel according to claim 1.

14. A sealing layer in tyres, sealing layers on inner liners in pneumatic motor vehicle tyres, hollow bodies or membranes, comprising a sealing compound according to claim 11.

15. Pneumatic motor vehicle tyres having a sealing compound according to claim 11.

16. The sealing gel of claim 1, wherein: the at least one crosslinker (I) is selected from the group consisting of: acrylates and methacrylates of ethylene glycol, propane-1,2-diol, butane-1,4-diol, hexanediol, polyethylene glycol having 2 to 8 oxyethylene units, neopentyl glycol, bisphenol A, glycerol, trimethylolpropane, pentaerythritol, sorbitol with unsaturated polyesters of aliphatic di- and polyols and mixtures thereof.

17. The sealing gel of claim 16, wherein: the at least one crosslinker (I) is selected from the group consisting of: acrylates and methacrylates of propane-1,2-diol, butane-1,4-diol, neopentyl glycol, bisphenol A, glycerol, trimethylolpropane and pentaerythritol, and trimethylolpropane trimethacrylate (TMPTMA).

18. The sealing gel of claim 1, wherein: the at least one crosslinker (II) is selected from the group consisting of: diisopropenylbenzene, divinylbenzene (DVB), divinyl ether, divinyl sulphone, diallyl phthalate, trivinylbenzene, triallyl cyanurate, triallyl isocyanurate, 1,2-polybutadiene, N,N-m-phenylenemaleimide, tolylene-2,4-bis(maleimide) and triallyl trimellitate and mixtures thereof.

19. The sealing gel of claim 2, wherein: the crosslinker (I) is selected from the group consisting of: acrylates and methacrylates of ethylene glycol, propane-1,2-diol, butane-1,4-diol, hexanediol, polyethylene glycol having 2 to 8 oxyethylene units, neopentyl glycol, bisphenol A, glycerol, trimethylolpropane, pentaerythritol, sorbitol with unsaturated polyesters of aliphatic di- and polyols, trimethylolpropane trimethacrylate (TMPTMA) and mixtures thereof.

20. The sealing gel of claim 2, wherein: the crosslinker (II) is a compound selected from the group consisting of: diisopropenylbenzene, divinylbenzene (DVB), divinyl ether, divinyl sulphone, diallyl phthalate, trivinylbenzene, triallyl cyanurate, triallyl isocyanurate, 1,2-polybutadiene, N,N-m-phenylenemaleimide, tolylene-2,4-bis(maleimide) and triallyl trimellitate and mixtures thereof.

Description

EXAMPLES

[0273] In the examples which follow, the following substances are used:

TABLE-US-00001 Name Source Styrene (ST) Azelis 1,3-Butadiene unstabilized (BDN) Air Liquide Deutschland GmbH Acrynitrile (ACN) Merck KGaA tert-Dodecyl mercaptan (tDDM) Phillips Dresinate 835 (Abieta DRS 835) Arizona Chemical B.K. (emulsifier) Oleic acid Merck KGaA Trimethylolpropane trimethylacrylate Sigma-Aldrich Chemie GmbH (TMPTMA) Divinylbenzene (DVB) Sigma-Aldrich Chemie GmbH Potassium hydroxide (KOH) Riedel-de-Haen Potassium chloride (KCl) Riedel-de-Haen p-Menthane hydroperoxide Akzo-Degussa (Trigonox NT 50) Sodium phosphate dodecahydrate Merck KGaA (Na.sub.3PO.sub.4 * 12 H.sub.2O) Rongalit C (for synthesis) Merck KGaA Ethylenediaminetetraacetic acid EDTA Merck KGaA (ultrapure) Iron(II) sulphate heptahydrate Merck KGaA (FeSO.sub.4 * 7 H.sub.2O) Sodium chloride (NaCl) Merck KGaA Phosphoric acid (H.sub.3PO.sub.4) VWR Calcium chloride anhydrous (CaCl.sub.2) Merck KGaA E-SBR rubber (Buna SE 1502 H) LANXESS Deutschland GmbH Butyl rubber (X_Butyl RB 301) LANXESS Deutschland GmbH Natural rubber (SVR 3L) Weber & Schaer Escorez 2173 (hydrocarbon resin) ExxonMobil Chemical TDAE oil Vivatec 500 (extender LANXESS Deutschland GmbH compound) Rhenopren EPS (factice) LANXESS Deutschland GmbH Vulkanox HS LG (ageing stabilizer) LANXESS Deutschland GmbH Vulkanox 4020 (ageing stabilizer) LANXESS Deutschland GmbH Regal SRF (carbon black) Cabot Radglo GM-25 (pigment) Radiant Color N.V. Tronox Titanium Dioxide (pigment) Tronox Oppasin Blue 6900 (pigment) BASF

[0274] Test Methods:

[0275] Characterization of the Diene Rubber Gels and Sealing Gels

[0276] Determination of conversion: The conversion of the cold emulsion polymerization is calculated from the solids content of the latex solution. The determination of solids in the latex is effected by means of a halogen moisture analyser (Mettler Toledo, Halogen Moisture Analyzer HG63). For this purpose, an aluminium pan (Mettler, article no. 13865) is inserted into the sample holder and tared. Then an HAF1 glass fibre filter (Mettler, article no. 214464) is placed on top and the measurement is started. Typically, the glass fibre filter in the course of storage absorbs about 0.5% air humidity. Subsequently, the aluminium pan with the dried glass fibre filter is inserted into the sample holder and the balance is tared. About 1 g to 1.5 g of latex are weighed in and distributed over a maximum area in order to enable complete absorption of the liquid through the glass fibre filter. Then the measurement is started. When the weight loss of the sample is less than 1 mg per 50 seconds, the measurement is ended and the solids content is noted. The measured solids content of the latex and the theoretical solids content of the latex at the end of the polymerization are used to calculate the conversion of the emulsion polymerization.

[0277] Determination of gel content: The fraction insoluble in toluene is determined in toluene at 23 C. This is done by swelling 250 mg of the diene rubber gel in 20 ml of toluene with agitation at 23 C. for 24 hours. After centrifugation at 20 000 rpm, the insoluble fraction is removed and dried. The gel content is calculated from the quotient of the dried residue and the starting weight and is reported in percent.

[0278] Glass transition temperature: The glass transition temperatures (Tg) and the breadth of the glass transition (Tg) of the diene rubber gels are determined by differential thermoanalysis (DTA, differential scanning calorimetry (DSC)) on a 2003 Perkin Elmer DSC-7 calorimeter. For the determination of Tg and Tg, two cooling/heating cycles are conducted. Tg and Tg are determined in the second heating cycle. For the determinations, 10 mg to 12 mg of the diene rubber gels are used in a DSC sample holder (standard aluminium pan) from Perkin Elmer. The first DSC cycle is conducted by first cooling the sample down to 100 C. with liquid nitrogen and then heating it up to +150 C. at a rate of 20 K/min. The second DSC cycle is commenced by immediate cooling of the sample as soon as a sample temperature of +150 C. has been achieved. The cooling is effected at a rate of about 320 K/min. In the second heating cycle, the sample is heated up once more to +150 C. as in the first cycle. The heating rate in the second cycle is again 20 K/min. Tg and Tg are determined from the graph of the DSC curve of the second heating operation. For this purpose, three straight lines are applied to the DSC curve. The first straight line is applied to the part of the DSC curve below Tg, the second straight line to the curve section with a turning point that runs through Tg, and the third straight line to the curve section of the DSC curve above Tg. In this way, three straight lines with two points of intersection are obtained. Each point of intersection is characterized by a characteristic temperature. The glass transition temperature Tg is obtained as the mean of these two temperatures and the breadth of the glass transition Tg is obtained from the difference between the two temperatures.

[0279] To determine the swelling index, 250 mg of the diene rubber gel are swollen under agitation in 25 ml of toluene at 23 C. for 24 h. The gel is centrifuged off at 20 000 rpm, weighed and then dried to constant weight at 70 C. and weighed once again. The swelling index is calculated as follows:

Qi=wet weight of the gel/dry weight of the gel.

[0280] The Mooney viscosity of the diene rubber gels and the sealing gels is determined by the standard ASTM D1646 (1999) and measures the torque of the sample at elevated temperature using a 1999 Alpha Technologies MV 2000 Mooney viscometer (manufacturer serial number: 25AIH2753). It has been found to be useful to calender the diene rubber gel or the sealing gel beforehand. For this purpose, the diene rubber gel or the sealing gel is processed on a roller at a roller temperature of T60 C. to give a rolled sheet. The roller gap is varied between 1 mm and 3 mm, the friction is 10% and the roller revolutions per minute are 7-8 rpm. The measurement is conducted as follows: The cylindrical sample punched out is placed into the heating chamber and heated up to the desired temperature (here 100 C.). After a preheating time of one minute, the rotor (of size L) rotates at a constant 2 revolutions/minute and the torque is measured after four minutes. The Mooney viscosity measured (ML 1+4) is in Mooney units (MU, with 100 MU=8.3 Nm).

[0281] Characterization of the Sealing Compound

[0282] The tackiness (measurement parameter for adhesion) of the sealing compound of the invention is determined by means of a rolling ball tack tester.

[0283] The test is conducted on the basis of the standard ASTM D3121-06 at ambient temperature. The sealing compound is pressed to a thickness of 1 mm at 105 C. and 120 bar for 10 min and cooled to room temperature under pressure over a period of 12 h. The sealing compound thus pressed is cut to a rectangle of edge length 20 cm10 cm, ensuring a smooth and contamination-free surface. The rectangular sealing compound of thickness 1 mm is placed onto a flat surface and the rolling ball tack tester is set up on the rectangular sealing film such that the tester is likewise flat (checked by means of a spirit level) and a ball rolling distance of 6 cm is possible. The polished steel ball having a diameter of 1 cm (ChemInstruments) is cleaned in acetone before each test and then placed onto the rolling ball tack tester. In this case, surface contamination of the ball, which can be caused, for example, by direct contact with the hands, should be avoided. By actuating the trigger mechanism of the rolling ball tack tester, the ball is put in a state of controlled movement. The distance that the ball has rolled on the test material is measured. This is done by measuring from the end of the rolling ball tester to the middle of the ball. Each experiment is conducted on a contamination-free surface. The experiment is repeated at least three times and the average is reported as the result.

[0284] To determine the failure temperature (measurement parameter for cohesion), the SAFT test (Shear Adhesion Failure Temperature) is conducted on the basis of standard ASTM D4498-07 (called Heat Fail Temperature therein). For this purpose, the sealing compound is pressed to a thickness of 1 mm at 105 C. and 120 bar for 10 min and cooled to room temperature under pressure over a period of 12 h. The pressed sealing compound which has been cut to an edge length of 2.5 cm2.5 cm is positioned halfway between two polished stainless steel plates of dimensions 7.5 cm7.5 cm2.5 cm which have been cleaned beforehand with acetone, so as to give a square sample geometry of dimensions 2.5 cm2.5 cm0.1 cm between the two plates. The stainless steel plates from ChemInstruments each have a hole at the end of the plate. The sealing compound is pressed between the two stainless steel plates at room temperature at 5.4 bar with the stainless steel plates for 3 min, in order to establish an adhesive bond between stainless steel plate and sealing compound. Subsequently, the adhesive bond construction is suspended in a shear tester (ChemInstruments SS-HT-8). It should be ensured that the stainless steel plates along with the sealing compound hang vertically. A weight of 500 g is suspended on the hole in the plate pointing downward. The temperature of the shear testing oven (Memmert, UF 110 Plus) is left at room temperature for one hour. Subsequently, the time measurement is started and the temperature is increased to 40 C. in a linear manner within 10 min and kept constant for 20 min, before the oven is heated up to 175 C. at a heating rate of 0.5 C./min and kept constant for not more than 4 hours. The temperature and time at which the adhesive construction fails and the weight falls down are noted.

[0285] The determination of the loss factor tan at 60 C. as an indicator of rolling resistance is effected on the basis of standard DIN-ISO 6721-1 and 6721-2. The preparation of the sealing compound for the measurement of the loss factor as an indicator of rolling resistance is conducted as follows: The sealing compound is processed on a roller at a roller temperature of T60 C. to give a rolled sheet. The sheet is subsequently passed through a roll gap of 0.5 mm, which results in a sheet having a thickness of 3.5 mm. A sample of size 10 cm10 cm is taken from this sheet and pressed in a mould of 10 cm10 cm0.1 cm at a pressure of 120 bar and a temperature T105 C. for 10 min. After cooling to room temperature within 10 minutes, a round sample having a diameter of 8 mm is punched out of the pressed material for dynamic-mechanical measurements. This sample is fixed between two plates. Before the temperature run, a time run is conducted on the sample for a period of 10 min at 100 C. and an initial force of 2 N. Subsequently, a temperature run is conducted with an initial force of 2 N and maximum deformation of 2% in the range from 100 C. to 170 C. at a constant frequency of 10 Hz and a heating rate of 3 K/min.

[0286] Production and Characterization of Extended Sealing Gels.

[0287] There following is a description of the production of diene rubber gels (A1 to A3 and B1 to B3) and extended diene rubber gels (XX1 to XX3)XX, and gel (H2) having extender compound incorporated therein (XX4). The diene rubber gels A1 to A3 and B1 to B3 and the extended diene rubber gels XX1, XX2 and XX5, and the extended sealing gel XX3,) XX4 and XX6 were used in the further examples as well. Also described is the production of SBR comparative examples W1.

[0288] The diene rubber gels and the sealing gel are produced by emulsion polymerization, using 1,3-butadiene (BDN), acrynitrile (ACN) and styrene (ST) as monomers and trimethylolpropane trimethacrylate (TMPTMA) and/or divinylbenzene (DVB) as crosslinkers. The monomers and essential formulation constituents used for the production of the diene rubber gels and the sealing gel are summarized in the following table:

TABLE-US-00002 TABLE 1 Emulsifiers Diene Solvent Oleic Dres- Monomers Crosslinker rubber Water acid inate BDN ST ACN TMPTMA DVB gel [g] [g] [g] [g] [g] [g] [g] [g] A1 11939 80 171 3492 400 112.5 A2 11939 80 171 3892 112.5 A3 11939 80 171 3492 400 112.5 B1 11939 80 171 3528 400 90.0 B2 11939 80 171 4193 134 B3 11939 80 171 3528 400 90 H2 11939 80 171 3904 62.5 45 W1 11939 80 171 3528 400 75

[0289] (a) Emulsion Polymerization and Crosslinking of BR, SBR and NBR Rubber

Examples A1 to A3, B1 to B3 and H2

[0290] The figures relate to 100% pure feedstocks. The diene rubber gels are produced in a 20 I autoclave with stirrer system. Monomers, crosslinker, emulsifiers and the amounts of water specified in the table (minus the amounts of water required for the production of the aqueous premix and initiator solutions) were initially charged in the autoclave.

[0291] After adjusting the temperature of the reaction mixture to 10 C., freshly produced aqueous premix solution (4% strength) was introduced into the autoclave to activate the initiator. These premix solutions consisted of 1.10 g of ethylenediaminetetraacetic acid, 0.86 g of iron(II) sulphate*7H.sub.2O (calculated without water of crystallization) and 2.07 g of Rongalit C (sodium formaldehydesulphoxylate 2-hydrate, calculated without water of crystallization). At first, half the solution was added. Also metered into the reactor for initiation was 0.058% by weight (again based on the sum total of all the monomers) of p-menthane hydroperoxide (Trigonox NT50 from Akzo-Degussa), which was emulsified in 200 ml of the emulsifier solution prepared in the reactor. On attainment of 30% conversion, the remaining 50% of the premix solution was metered in.

[0292] The temperature was controlled during the polymerization by adjusting the coolant volume and coolant temperature at 100.5 C.

[0293] On attainment of a polymerization conversion of more than 85% (typically: 90% to 100%), the polymerization was stopped by adding an aqueous solution of 2.35 g of diethylhydroxylamine. To remove volatile constituents from the latex, the latex was stripped with steam.

Comparative Examples W1

[0294] SBR rubber gels that are not in accordance with the invention were produced by means of hot emulsion polymerizations. The production of W1 was effected like the cold emulsion polymerization in each case, but at a polymerization temperature of 50 C.

[0295] (b) Workup of the Diene Rubber Gels and Sealing Gel

[0296] The precipitation of the diene rubber gel was conducted as follows:

[0297] A 15 l stainless steel pot equipped with a dissolver stirrer was initially charged with 3 kg of latex while stirring, and heated to 60 C. Then 1 kg of a 20% NaCl solution (333 g/kg of latex) was added, forming a very fine coagulate. Subsequently, the suspension was heated to 75 C. and 25% phosphoric acid was slowly added dropwise. In the course of this, it was important that the dissolver stirrer ran at maximum stirrer speed (1500 rpm), since the coagulate otherwise conglutinated readily to a large ball. In the neutral pH range, the suspension formed a foam, which disappeared completely in the acidic range. The precipitation was complete and the serum was colourless and clear.

[0298] Then the coagulate was filtered through a 200 m cloth and then washed to neutrality with demineralized water. Two washing cycles were sufficient for the purpose.

[0299] Subsequently, the polymer was dried down to a residual moisture content of 0.5% in a vacuum drying cabinet at 55 C.

[0300] (c) Workup of the Extended Diene Rubber Gels and Sealing Gel XX1 to XX5

[0301] The precipitation of the diene rubber gel was conducted as follows:

[0302] A 15 l stainless steel pot equipped with a dissolver stirrer was initially charged with 3.3 kg of latex while stirring, and heated to 60 C. Then 1.1 kg of a 20% NaCl solution (333 g/kg of latex) was added, forming a very fine coagulate. Subsequently, TDAE oil was added, forming a brownish suspension. After heating to 75 C. 25% phosphoric acid was added dropwise. In the course of this, it was important that the dissolver stirrer ran at maximum stirrer speed (1500 rpm), since the coagulate otherwise conglutinated readily to a large ball. In the neutral pH range, the suspension formed a foam, which disappeared completely in the acidic range. The precipitation was complete and the serum was colourless and clear.

[0303] Then the coagulate was filtered through a 200 m cloth and then washed to neutrality with demineralized water. Three washing cycles were sufficient for the purpose. Subsequently, the polymer was dried down to a residual moisture content of 0.5% in a vacuum drying cabinet at 55 C.

[0304] (d) Workup of the Extended Sealing Gel XX6

[0305] Dien rubber gel A and B and extender compound were mixed together homogeneously on a Collin W 150 G roll as described below.

[0306] The analytical data, determined by the methods described above, are reproduced in Table 2 below.

TABLE-US-00003 TABLE 2 Primary (ML1 + Con- particle Swel- 4) ver- dia- Gel ling @ sion meter content index Tg Tg 100 C. [%] [nm] [%] QI [ C.] [ C.] [MU] A1 93 42 88 24 70 7 183 A2 96 29 90 24 78 10 194 A3 93 34 87 16 73 8 126 B1 92 41 94 12 69 6 77 B2 92 45 94 11 74 12 88 B3 96 38 94 15 69 19 81 H2 96 35 79 10 76 13.3 88 W1 97 36 17 15 71 6 74

[0307] The cold-polymerized rubber gels (A) and (B) shown in Table 2, at a conversion of more than 85%, have a gel content of more than 75% and a Mooney viscosity (ML1+4@100 C.) of more than 75 MU.

[0308] The cold-polymerized BR gel (H) shown in Table 2, at a conversion of more than 85%, have a gel content of more than 70% and a Mooney viscosity (ML1+4@100 C.) of more than 80 MU.

[0309] Cold-polymerized SBR rubber gels of the invention differ from the hot-polymerized SBR rubber gels that are not in accordance with the invention in terms of microstructure. A comparison of the microstructure of the polymerized SBR rubber gels A1 and B1 of the invention with the corresponding hot-polymerized SBR rubber gels W1 which has been produced by a hot emulsion polymerization and are not in accordance with the invention is compiled in Table 3 below. Additionally, the microstructure of the cold-polymerized BR gels A2 and B2 of the invention is shown in Table 3. The measurements were conducted on a 1999 Thermo Scientific Nicolet FTIR Nexus instrument.

TABLE-US-00004 TABLE 3 Diene cis trans vinyl rubber gel [% by wt.] [% by wt.] [% by wt.] A1 13.9 66.3 19.8 W1 21.7 57.1 21.2 B1 14.9 64.8 20.3 H2 14.5 65.4 20.1 A2 15 64 21 B2 15 65 20

[0310] Polymerized diene rubber gels (A) and (B) of the invention have a proportion of cis-1,4-butadiene units of 8% by weight to 17% by weight, a proportion of trans-1,4-butadiene units of 59% by weight to 75% by weight and a proportion of 1,2-vinylbutadiene units of 17% by weight to 21% by weight, based on 1,3-butadiene incorporated.

[0311] Polymerized gel (H) of the invention have a proportion of cis-1,4-butadiene units of 8% by weight to 17% by weight, a proportion of trans-1,4-butadiene units of 59% by weight to 75% by weight and a proportion of 1,2-vinylbutadiene units of 17% by weight to 21% by weight, based on 1,3-butadiene incorporated.

TABLE-US-00005 TABLE 4 Ex- tender Diene Diene Diene Diene Ex- com- rubber rubber rubber rubber tender pound gel gel gel gel com- (Rhen- (ML1 + A1 B1 H2 A2 pound opren 4) [% [% [% [% (TDAE EPS) @ by by by by oil) [% 100 C. wt.] wt.] wt.] wt.] [phr] by wt.] [MU] XX1 100 0 0 0 50 0 74 XX2 0 100 0 0 40 0 49 XX3 30 70 0 0 47 0 63 XX4 0 0 100 0 50 0 49 XX5 0 0 0 100 55 0 57 XX6 25.5 59.5 0 0 0 15 66

[0312] Diene rubber gels (A1), (A2) and (B1), and the gel (H2) are extended by the incorporation therein of TDAE oil as the extender compound in the workup process shown in Table 4 have a Mooney viscosity (ML1+4100 C.) less than 80 MU. Diene rubber gels (A1) and (B1) extended with factice as the extender compound have a have a Mooney viscosity (ML1+4@100 C.) less than 80 MU shown in Table 4.

[0313] The sealing compound was produced on a Collin W 150 G roll mill built in April 2013. The roll temperature during the mixing operation was 90 C. The roller gap was varied between 1 mm and 3 mm, the friction was 10% and the roller revolutions per minute were 7 rpm to 8 rpm.

[0314] For the production of the sealing compounds V1 to V11 of the invention, the extended diene rubber gels XX were first each mixed together homogeneously on the roll as described above. Subsequently, rubber (E) was added in each case and well-dispersed. Thereafter, resin (C) was added gradually in small portions, followed by the ageing stabilizers (D), the pigment (G) and lastly, additionally the plasticizer (F). Rolling was continued until the mixture appeared homogeneous to the eye.

[0315] The composition of the sealing compounds VV1 to VV3 that are not in accordance with the invention and of the sealing compounds V1 to V11 of the invention and the amounts thereof are specified in Table 5 and 6. The amounts of the individual components are reported in phr.

TABLE-US-00006 TABLE 5 Sealing compound VV1 VV2 V1 V2 V3 V4 V5 V6 V7 Diene 25.5 0 0 25.5 0 0 0 0 0 rubber gel A1 [phr] Diene 59.5 40 59.5 0 0 0 0 0 0 rubber gel B1 [phr] Diene 0 0 0 0 0 0 0 0 0 rubber gel B2 [phr] Diene 0 0 38.25 0 0 0 0 0 0 rubber gel XX1 [phr] Diene 0 0 0 83.3 0 0 0 0 0 rubber gel XX2 [phr] Diene 0 0 0 0 125 117.6 125 0 0 rubber gel XX3 [phr] Diene 0 0 0 0 0 0 0 127.5 0 rubber gel XX4 [phr] Diene 0 0 0 0 0 0 0 0 131.75 rubber gel XX5 [phr] Diene 0 40 0 0 0 0 0 0 0 rubber gel W1 [phr] Resin (C) 30 30 30 30 30 30 30 30 30 Escorez 2173 [phr] Ageing 1.5 1.5 3 3 3 3 3 3 3 stabilizer (D) Vulkanox HS LG [phr] Ageing 0 1.5 0 0 0 0 0 0 0 stabilizer (D) Vulkanox MB2/MG- C [phr] Ageing 1.5 0 3 3 3 3 3 3 3 stabilizer (D) Vulkanox 4020 [phr] Rubber 0 20 0 0 0 20 0 0 0 (E) Buna SE 1502H [phr] Rubber 15 0 15 15 15 0 0 15 15 (E) NR (SVR- 3 L ML (1 + 4) @ 100 C. = 20 MU) [phr] Rubber 0 0 0 0 0 0 15 0 0 (E) X_Butyl RB 301 Plasticizer 40 40 27.25 16.2 0 0 0 0 0 (F) TDAE oil Vivatec 500 [phr] Pigment 0 1 0 0 0 1 0 0 0 (G) Radglo GM-25 [phr] Pigment 3 0 3 3 3 0 3 3 3 (G) Regal SRF [phr]

TABLE-US-00007 TABLE 6 Sealing compound VV3 V8 V9 V10 V11 Diene 0 25.5 0 0 25.5 rubber gel A1 [phr] Diene 59.25 59.5 0 0 59.5 rubber gel B1 [phr] Diene 0 0 25.5 0 rubber gel A2 [phr] Diene 0 0 59.5 0 rubber gel B2 [phr] Diene 0 0 0 25.5 rubber gel A3 [phr] Diene 0 0 0 59.5 rubber gel B3 [phr] Resin (C) 30 30 30 30 30 Escorez 2173 [phr] Ageing 3 3 3 3 3 stabilizer (D) Vulkanox HS LG [phr] Ageing 3 3 3 3 3 stabilizer (D) Vulkanox 4020 [phr] Rubber (E) 15 0 0 0 7.5 Buna SE 1502H [phr] Factice (F) 25.5 15 15 15 7.5 Rhenopren EPS [phr] Plasticizer 40 40 50 40 40 (F) TDAE oil Vivatec 500 [phr] Pigment (G) 1 1 1 1 1 Oppasin Blue [phr] Pigment (G) 1 1 1 1 1 Tronox [phr]

[0316] The characterization of the sealing compounds VV1 to VV3 and V1 to V11 is compiled in Table 7 and 8 below.

TABLE-US-00008 TABLE 7 Sealing com- pound VV1 VV2 VV3 V1 V2 V3 (ML1 + 12 10 10 11 11 12 4) @ 100 C. [MU] Rolling 1.0 1.3 0.9 0 0 0 ball tack tester [cm] tan @ 0.28 0.3 0.24 0.24 0.25 0.20 60 C. Sealing compound V4 V5 V6 V7 (ML1 + 11 14 13 12 4) @ 100 C. [MU] Rolling 0.8 2.4 1.5 1.7 ball tack tester [cm] tan @ 0.24 0.23 0.22 0.20 60 C.

TABLE-US-00009 TABLE 8 Sealing compound V8 V9 V10 V11 (ML1 + 4) @ 100 C. 11 12 10 12 [MU] Rolling ball tack 1.0 0 1.1 0.7 tester [cm] tan @ 60 C. 0.16 0.14 0.19 0.22

[0317] The Mooney viscosity is determined by the methods described above on an Alpha Technologies MV 2000 Mooney viscometer.

[0318] Tackiness is determined by the methods described above on a rolling ball tack tester (RBT-100) from ChemInstruments.

[0319] The tan value is determined by the methods described above by means of an ARES-G2 rheometer from TA Instruments.

[0320] The determination of the failure temperature of the particular sealing compound by means of the SAFT test was effected in a double determination on two specimens of the particular sealing compound. The measurements were conducted by the methods described above on a ChemInstruments HT-8 shear tester in a Memmert UF 110 Plus heating cabinet. The mean values for the results are compiled in Table 9 and 10 below.

TABLE-US-00010 TABLE 9 VV1 VV2 VV3 V1 V2 V3 Failure 72 51 40 89 120 142 temperature [ C.] V4 V5 V6 V7 Failure 98 >175 76 116 temperature [ C.]

TABLE-US-00011 TABLE 10 V8 V9 V10 V11 Failure 92 108 92 92 temperature [ C.]

[0321] A sealing compound which is ready to use in practice has to pass both the rolling ball tack test and the SAFT test. In this case, the rolling ball tack test is considered to have been passed when the distance that the ball rolls is less than 3 cm.

[0322] The SAFT test is considered to have been passed when the failure temperature is greater than 75 C. An overall assessment of the sealing compounds \N1 to VV3 and V1 to V11 is compiled in Table 11 and 12 below.

TABLE-US-00012 TABLE 11 Sealing compound VV1 VV2 VV3 V1 V2 V3 V4 V5 V6 V7 Rolling P P P P P P P P P P ball tack test assessment SAFT F F F P P P P P P test assessment Overall F F F P P P P P P assessment P means passed and F means failed.

TABLE-US-00013 TABLE 12 Sealing compound V8 V9 V10 V11 Rolling ball tackiest assessment P P P P SAFT test assessment P P P P Overall assessment P P P P P means passed and F means failed.

[0323] The sealing compounds that are not in accordance with the invention fail at least one of the two tests.

[0324] The sealing compounds of the invention V1 to V11 are notable in that they pass both tests. Further, they show increased failure temperature in the SAFT test resulting in an improved sealing performance.

[0325] If the sealing compound of the invention is applied to the tyre liner as a film of thickness 3 mm and the tyre is filled with air such that it has an air pressure of 2.5 bar, the sealing compound has a self-sealing effect when a nail which has been hammered in (to diameter 5 mm) is pulled out. The air pressure in the tyre remains constant for at least one week.