FOAMED SEALING COMPOUNDS

Abstract

A polymer based sealing compound which is foamed, which is applied to vehicle tyres for the reduction in weight and improvement of driving dynamics, a process for producing such foamed sealing compounds, and the use thereof in tyres.

Claims

1. Foamed sealing compound for self-sealing tires, comprising: a sealing gel in an amount of 45 phr to 100 phr; resin (C) in an amount of 10 phr to 60 phr; a natural rubber or synthetic rubber (E) in an amount of 1 to 50 phr, wherein: said phr being based in each case on the total amount of sealing gel and the natural and/or synthetic rubber (E) in the sealing compound; the sealing compound has a density of 0.001 to 0.935 g/mL; said sealing gel is: i) in the form of a mixture comprising diene rubber gel (A) obtainable by emulsion polymerization of at least one conjugated diene in the presence of at least one crosslinker (I) and diene rubber gel (B) obtainable by emulsion polymerization of at least one conjugated diene in the presence of at least one crosslinker (II); or ii) obtainable 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), where: crosslinkers (I) are acrylates and methacrylates of polyhydric C.sub.2 C.sub.20 alcohols, preferably 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, acrylates and methacrylates of propane-1,2-diol, butane-1,4-diol, neopentyl glycol, bisphenol A, glycerol, trimethylolpropane, and pentaerythritol, and trimethylolpropane trimethacrylate (TMPTMA); and crosslinkers (II) are compound having two or more vinyl, allyl or isopropenyl groups or one maleimide unit 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, diisopropenylbenzene, divinylbenzene,. and trivinylbenzene.

2. Foamed sealing compound according to claim 1, having a tan .sub.f at 20 C. greater than 0.003 as measured by the Oberst Measurement method.

3. Foamed sealing compound according to claim 1, further comprising a blowing agent in an amount of 1 phr to 50 phr, wherein the blowing agent comprises hollow microspheres, hollow glass spheres, plastic hollow spheres based on phenolic resins, ceramic hollow spheres, hollow glass spheres, based on polyvinylidene chloride copolymers, ef-expanded hollow plastic microspheres, based on polyvinylidene chloride copolymers, acrylonitrile copolymers, and mixtures thereof.

4. Foamed sealing compound according to claim 1, wherein the sealing gel is obtainable by emulsion polymerization of at least one conjugated diene in the presence of at least one crosslinker (I) and simultaneously in the presence of at least one crosslinker (II).

5. Foamed sealing compound according to claim 1 4, wherein: further monomers are polymerized in the emulsion polymerization of the at least one conjugated diene; said further monomers are 1,3-butadiene, vinylaromatics, styrene, 2-methyl styrene, 3-methyl styrene, 4-methyl styrene, -methylstyrene, 2,4-dimethyl styrene, 2,4-diisopropylstyrene, 4-tert-butyl styrene 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 compound containing double bonds, hydroxyethyl methacrylate, hydroxyethyl acrylate, 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, vinylic heteroaromatics, 2,4-vinylpyridine, and 1-vinylimidazole.

6. Foamed sealing compound according to claim 5, wherein: the at least one conjugated diene is 1,3-butadiene; the further monomer is styrene; and said emulsion polymerization is performed at 5 C. to 20 C.

7. Foamed sealing compound according to claim 1, wherein: 1,3-butadiene is used as the at least one conjugated diene; and the sealing gel has 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 the 1,3-butadiene incorporated.

8. Foamed sealing compound according to claim 1, wherein the natural and/or synthetic rubber (E) is copolymers based on conjugated diolefins selected 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, natural cis-1,4-polyisoprene, synthetic cis-1,4-polyisoprene, 3,4-polyisoprene, polybutadiene, 1,3-butadiene-acrylonitrile copolymer, and mixtures thereof.

9. Foamed sealing compound according to claim 1, comprising an ageing stabilizer (D) in an amount of 0.5 phr to 20 phr.

10. Foamed sealing compound according to claim 1, comprising a plasticizer (F) in an amount of less than 75 phr.

11. Foamed sealing compound according to claim 1, comprising at least one filler (G) in an amount of 1 phr to 50 phr.

12. Process for producing the foamed sealing compound according to claim 1, comprising mixing the sealing gel, the natural or synthetic rubber (E), the resin (C), and the foaming agent.

13. Process for producing the foamed sealing compound according to claim 12, further comprising dispersing in a mixing apparatus said foaming agents under pressure in the sealing composition whereby gases expand upon leaving an extruder.

14. Process for producing the foamed sealing compound according to claim 12, wherein the sealing gel and the natural or synthetic rubber (E) are mixed in the form of their lattices.

15. A method for sealing a tire comprising applying the foamed sealing compound according to claim 1, thereby improving adhesion and cohesion properties.

16. A method for sealing a tire comprising applying the foamed sealing compound according to claim 1, to seal a tire.

17. A pneumatic motor vehicle tire having a foamed sealing compound according to claim 1.

Description

EXAMPLES

[0240] 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 tert-Dodecyl mercaptan (tDDM) Phillips Dresinate 835 (Abieta DRS 835) (emulsifier) Arizona Chemical B.K. Oleic acid Merck KGaA Trimethylolpropane trimethylacrylate (TMPTMA) Sigma-Aldrich Chemie GmbH Divinylbenzene (DVB) Sigma-Aldrich Chemie GmbH Potassium hydroxide (KOH) Riedel-de-Haen Potassium chloride (KCl) Riedel-de-Haen p-Menthane hydroperoxide (Trigonox NT 50) Akzo-Degussa Sodium phosphate dodecahydrate (Na.sub.3PO.sub.4 * 12H.sub.2O) Merck KGaA Rongalit C (for synthesis) Merck KGaA Ethylenediaminetetraacetic acid EDTA (ultrapure) Merck KGaA Iron(II) sulphate heptahydrate (FeSO.sub.4 * 7H.sub.2O) Merck KGaA 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 Escorez 2173 (hydrocarbon resin) EonMobil Chemical TDAE oil Vivatec 500 (plasticizer) LANXESS Deutschland GmbH Vulkanox HS LG (ageing stabilizer) LANXESS Deutschland GmbH Vulkanox MB2/MG-C (ageing stabilizer) LANXESS Deutschland GmbH Vulkanox 4020 (ageing stabilizer) LANXESS Deutschland GmbH Regal SRF (carbon black) Cabot Microlen Red 4060 MC BASF 3M Glass Bubbles iM16K (foaming agent (K)) 3M Expancel 051 DU 40 (foaming agent (K)) AkzoNobel

[0241] Test Methods:

[0242] Characterization of the Diene Rubber Gels and Sealing Gels

[0243] 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.

[0244] 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 per cent.

[0245] 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.

[0246] 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.

[0247] 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).

[0248] Characterization of the Sealing Compound

[0249] 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.

[0250] The density of the sealing compounds is measured by hydrodensitometry according to DIN 53479. Based on Archimedes' principle, the sample is weighed in air and water and the density of the sample is calculated.

[0251] The acoustic damping properties of the sealing compounds are analyzed by Dr. Oberst-Measurements according to DIN 53440, part 3, method B (DIN EN ISO 6721-3PlasticsDetermination of dynamic mechanical propertiesPart 3: Flexural vibration; resonance-curve, December 1996).

[0252] The temperature-dependent loss factor and the average complex bending elastic modulus of attenuating coatings deposited on a carrier material, in this case a steel strip, are determined.

[0253] The test is performed on rectangular bars suspended horizontally by fine fibres at vibrational nodes (method B). The apparatus consists of devices for suspending the specimen, electronic devices (frequency generator and recording device) for exciting the specimen to forced bending vibration and for measuring the frequency as well as the velocity amplitude of the sample. For excitation and detection of the vibrations, two electromagnetic transducers are situated near the ends of the sample.

[0254] The sample consists of steel strip coated with a sealing compound. The sealing compound is pressed to a thickness of 5 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 15 cm1 cm is positioned on the steel strip of dimensions 15 cm1 cm0.1 cm) which has been cleaned before with acetone.

[0255] The sample is placed in the measurement device which excites the flexural vibration of the sample on one side of the sample without contact (typical frequency range: 10 Hz to 1000 Hz). The resulting state of vibration of the sample is measured. By means of a FFT analyzer, the resonance curve can be calculated. The resonance curve describes the spectra transfer function between both ends of the sample.

[0256] The bending loss factor of the attenuating coating deposited on the steel strip becomes

[00001]$\tan .Math..Math.{}_f=\frac{.Math..Math.f_i}{f_{r,i}}.$

[0257] Where [0258] f.sub.r,i is the i.sup.th maximum of the measured transfer function in Hz and [0259] f.sub.i is the bandwidth in Hz (corresponds to the difference of the frequencies on both sides of the i.sup.th resonance frequency f.sub.r,i, where the amplitude of the transfer function is 3 dB smaller than the amplitude at the i.sup.th maximum).

[0260] The sample is suspended on two strings at the nodes of the flexural vibration. The distance

[00002]$L_i=\{\begin{array}{cc}0.224.Math.l& i=1\\ 0.660.Math.\frac{l}{2.Math.i+1}& i>1\end{array}$

of the i.sup.th node of the vibration to the end of the sample depends on the total length of the sample. For the sample length of l=150 mm during this investigation the distance of the 1.sup.st node of the fundamental resonance frequency to the sample end is L.sub.1=33.6 mm. The complex bending elastic modulus is determined by using the average density p of the sample consisting of attenuating coating and steel strip. The bending storage modulus is given by

[00003]$E_f^{}={\left(4.Math..Math.\sqrt{3.Math.}.Math.\frac{t^2}{h}\right)}^2.Math.{\left(\frac{f_{r,i}}{k_i^2}\right)}^2,$

[0261] The bending loss modulus is defined as

E.sub.f=E.sub.f.Math.tan .sub.f

[0262] Where [0263] h is the thickness of the sample and [0264] k.sub.i.sup.2 is a constant depending on the measurement method; for method B k.sub.i.sup.2=22.4.

[0265] The sample, the supporting device and the electromagnetic transducers are enclosed in a temperature-controlled chamber at 20 C. Reference measurements are performed only with the steel strip without any coating.

[0266] The devices used for the measurement setup including the climate chamber were 4-channel-data-acquisition unit Apollo Plus from SINUS Messtechnik GmbH with 24 bits per sample, class 1 sound level meter in accordance with IEC 61672 1, 1/3-octaves of class 0 in accordance with IEC 61260, analysis software SAMURAI from SINUS Messtechnik GmbH, version 2.6, amplifier Apart-AudioMB-150, climate chamber Mytron WB 120 K.

[0267] Production and characterization of the diene rubber gels and sealing gels

[0268] There follows a description of the production of the cold-polymerized diene rubber gels (A) of the invention and (B) and the diene rubber gels A and B were used in the further examples.

[0269] The diene rubber gels A and B are produced by emulsion polymerization, using 1,3-butadiene (BDN) 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 (A) and (B) are summarized in the following table:

TABLE-US-00002 TABLE 1 Diene Solvent Emulsifiers Monomers Crosslinker rubber Water Oleic Dresinate BDN ST TMPTMA DVB gel [g] acid [g] [g] [g] [g] [g] [g] A 11939 80 171 3492 400 112.5 B 11939 80 171 3528 400 90.0

[0270] (a) Emulsion Polymerization and Crosslinking of the SBR Rubber

Examples A and B

[0271] 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. 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 * 7 H.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 NT 50 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.

[0272] The temperature was controlled during the polymerization by adjusting the coolant volume and coolant temperature at 100.5 C.

[0273] 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.

[0274] (b) Workup of the Diene Rubber Gels

[0275] The precipitation of the diene rubber gel was conducted as follows:

[0276] A 15 I 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% NaCI 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.

[0277] 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.

[0278] Subsequently, the polymer was dried down to a residual moisture content of 0.5% in a vacuum drying cabinet at 55 C.

[0279] The analytical data, determined by the methods described above, are reproduced in Table 2 below.

TABLE-US-00003 TABLE 2 Primary Conver- particle Gel Swelling (ML1 + 4) sion diameter content index Tg Tg @100 C. [%] [nm] [%] QI [ C.] [ C.] [MU] A 93 42 88 24 70 7 183 B 92 41 94 12 69 6 77

[0280] The cold-polymerized SBR 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.

[0281] 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. The microstructure of the polymerized SBR rubber gels A and B of the invention is compiled in Table 3 below. The measurements were conducted on a 1999 Thermo Scientific Nicolet FTIR Nexus instrument.

TABLE-US-00004 TABLE 3 Diene rubber gel cis [% by wt.] trans [% by wt.] vinyl [% by wt.] A 13.9 66.3 19.8 B 14.9 64.8 20.3

[0282] 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.

[0283] Production and characterization of sealing gels M of the invention.

[0284] The sealing gel were produced on the basis of A1 and B1 on a Collin W 150 G roll mill built in 04/2013. The roll temperature during the mixing operation was60 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.

[0285] The composition of the sealing gels (M) of the invention eis specified in Table 4 below. The determination of the Mooney viscosity was determined by the above-described method with a rolled sheet using an Alpha Technologies MV 2000 Mooney viscometer. The amounts of the individual components are reported in % by weight. By varying the composition of the diene rubber gels, it is possible to control the Mooney viscosity of the sealing gel.

TABLE-US-00005 TABLE 4 A B [% by [% by (ML1 + 4) @ 100 C. Sealing gel wt.] wt.] [MU] M 30 70 103

[0286] Production and characterization of the sealing compounds VV1 that is not in accordance with the invention and the sealing compounds V1 to V5 of the invention.

[0287] The sealing compound was produced on a Collin W 150 G roll mill built in 04/2013. 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.

[0288] For the production of the sealing compounds V1 and V2 of the invention, the diene rubber gels A and B, were first each mixed together homogeneously on the roll as described above to give the sealing gels M. 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 the plasticizer (F). Rolling was continued until the mixture appeared homogeneous to the eye. The compound was cooled down to 60 C. and foaming agent (K) was added and mixed until the mixture appeared homogeneous to the eye. The sealing compounds were then expanded for 10 minutes at 105 C. to give foamed sealing compounds.

[0289] For the production of the sealing compounds V3 and V4 of the invention, the diene rubber gels A and B, were first each mixed together homogeneously on the roll as described above to give the sealing gels M. 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), foaming agent (K) and lastly the plasticizer (F). Rolling was continued until the mixture appeared homogeneous to the eye.

[0290] For the production of the sealing compounds V5 of the invention, the diene rubber gel B was mixed with rubber (E). Thereafter, resin (C) was added gradually in small portions, followed by the ageing stabilizers (D), the pigment (G), foaming agent (K) and lastly the plasticizer (F). Rolling was continued until the mixture appeared homogeneous to the eye.

[0291] The composition of the sealing compounds VV1 that is not in accordance with the invention and of the sealing compounds V1 to V5 of the invention and the amounts thereof are specified in Table 5. The amounts of the individual components are reported in phr.

TABLE-US-00006 TABLE 5 Sealing compound VV1 V1 V2 V3 V4 V5 Diene rubber gel 21 25.5 25.5 25.5 25.5 0 A [phr] Diene rubber gel 49 59.5 59.5 59.5 59.5 85 B [phr] Resin (C) 30 30 30 30 30 30 Escorez 2173 [phr] Ageing stabilizer 1.5 3 3 3 3 3 (D) Vulkanox HS LG [phr] Ageing stabilizer 1.5 0 0 0 0 0 (D) Vulkanox MB2/MG-C [phr] Ageing stabilizer 0 3 3 3 3 3 (D) Vulkanox 4020 [phr] Rubber (E) 30 15 15 15 15 15 Buna SE 1502H [phr] Plasticizer (F) 30 55 55 50 65 30 TDAE oil Vivatec 500 [phr] Foaming agent 0 5 2.5 0 0 0 (K) Expancel 051 DU 40[phr] Foaming agent 0 0 0 10 25 25 (K) 3M Glass Bubbles iM16K [phr] Pigment (G) 0 3 3 3 3 3 Regal SRF [phr] Pigment (G) 1 0 0 0 0 0 Microlen Red 4060 MC [phr]

TABLE-US-00007 TABLE 6 tan .sub.f @ 20 C. Without coating 0.003 With VV1 0.001 With V1 0.019 With V2 0.010 With V3 0.010 With V4 0.011 With V5 0.006

[0292] The acoustic damping properties of the compounds are analyzed by Dr. Oberst-Measurements according to DIN 53440, part 3, method B.

[0293] The characterization of the sealing compounds VV1 to VV3 and V1 to V5 is compiled in Table 7 below.

TABLE-US-00008 TABLE 7 Sealing compound VV1 VV2 VV3 V1 V2 V3 V4 V5 (ML1 + 4) @ 100 C. [MU] 20 4 10 16 12 10 12 13 Density [g/mL] 0.937 0.958 0.969 0.924 0.929 0.901 0.846 0.843 tan @ 0.25 0.58 0.38 0.27 0.27 0.27 0.30 0.31 60 C.

[0294] VV2 is sealing material available as part of the Continental Premium Contact 2 tyre from Continental.

[0295] VV3 is sealing material available as part of the Michelin Primacy 3 Selfseal tyre from Michelin.

[0296] The Mooney viscosity is determined by the methods described above on an Alpha Technologies MV 2000 Mooney viscometer.

[0297] The tan value is determined by the methods described above by means of an ARES-G2 rheometer from TA Instruments.

[0298] The density is determined by hydrodensitometry according to DIN 53479.

[0299] 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-00009 TABLE 9 VV1 V1 V2 V3 V4 V5 Failure 91 114 60 53 40 88 temperature [ C.]

[0300] 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 is allowed to decrease up to 1.0 bar and remains constant for at least one week.