DELAYED SEALING COMPOUNDS FOR SELF-SEALING TYRES

Abstract

A delayed sealing compound comprising inventive sealing gel, a process for producing this sealing compound, and the use of sealing compounds in tyres with warning ability.

Claims

1. A sealing compound, comprising: a sealing gel in an amount of 45 phr to 100 phr, resin (C) in an amount of 10 phr to 60 phr, and a natural rubber and/or synthetic rubber (E) in an amount of 1 phr to 50 phr, where said phr is based in each case on the total amount of seating gel and the natural and/or synthetic rubber (E) in the sealing compound, and wherein the sealing compound has a failure temperature greater than 70 C. as measured by the SAFT test, wherein the sealing compound passes a Puncture-Sealing-Test (PST), and where, said sealing gel is i) in the form of a mixture comprising diene rubber gel (A) formed by emulsion polymerization of at least one conjugated diene in the presence of at least one crosslinker (I) and 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), 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, and wherein the sealing compound has an elongation at break of less than or equal to 500%.

2. A sealing compound according to claim 1, wherein the sealing gel is formed 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).

3. A sealing compound according to claim 1, wherein the sealing compound has a tan .sub.f@20 C. of greater than 0.003 as measured by the Oberst Measurement method.

4. (canceled)

5. A sealing compound according to claim 1, wherein the sealing compound has a stress at break .sub.B of less than 0.15 MPa as measured according to ASTM D412.

6. A sealing compound according to claim 1, wherein the at least one conjugated diene is 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, isoprene or chloroprene.

7. A sealing compound 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, 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.

8. A sealing compound according to claim 1, wherein: the natural and/or synthetic rubber (E) is a copolymer based on conjugated diolefins are selected from 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 and mixtures thereof.

9. A sealing compound according to claim 1, wherein: the 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, pentaerythritol and trimethylolpropane trimethacrylate (TMPTMA) and crosslinker (II) is divinylbenzene.

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

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

12. A process for producing sealing compounds according to claim 1, comprising the steps of mixing the sealing gel, the natural or synthetic rubber (E) and the resin (C).

13. The process according to claim 12, wherein the sealing gel natural or synthetic rubber (F) are mixed in the form of their latices.

14. A sealing layer in tyres, or a layer inner liners in pneumatic motor vehicle tyres, hollow bodies or membranes comprising the sealing compound of claim 1.

15. Pneumatic motor vehicle tyres having a sea according to claim 1.

16. A sealing compound of claim 1, wherein: the crosslinkers (I) are 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 trimethylacrylate (TMPTMA) and mixtures thereof.

17. A sealing compound of claim 1, wherein: the crosslinkers (II) are selected from the group consisting of: diisopropenylbenzene, divinylbenzene (DVB), divinyl ether, divinyl sulphone, diallyl phthalate, divinylbenzene, triallyl cyanurate, triallyl isocyanurate, 1,2-polybutadiene, N,N-m-phenylenemaleimide, tolylene-2,4-bis(maleimide) and triallyl trimellitate and mixtures thereof.

18. The sealing compound of claim 1, comprising the sealing gel in an amount of 60 phr to 100 phr.

19. The sealing compound of claim 1, comprising the resin (C) in an amount of 20 phr to 50 phr.

20. The sealing compound of claim 1, comprising the natural rubber and/or synthetic rubber (E) in an amount of 5 phr to 40 phr.

21. The sealing compound of claim 1, comprising: the sealing gel in an amount of 60 phr to 100 phr; the resin (C) in an amount of 20 phr to 50 phr; and, the natural rubber and/or synthetic rubber (E) in an amount of 5 phr to 40 phr.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0244] FIG. 1 schematically illustrates an apparatus for conducting a Puncture-Sealing-Test (PST).

EXAMPLES

[0245] 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) (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 * 12 Merck KGaA H.sub.2O) Rongalit C (for synthesis) Merck KGaA Ethylenediaminetetraacetic acid EDTA (ultrapure) Merck KGaA Iron(ll) sulphate heptahydrate (FeSO.sub.4 * 7 H.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 EPDM rubber (Keltan 2660 ) LANXESS Deutschland GmbH Natural rubber (SVR 3L) Weber & Schaer Escorez 2173 (hydrocarbon resin) ExxonMobil 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 Radglo GM-25 (pigment) Radiant Color N.V. Regal SRF (carbon black) Cabot Tronox Titanium Dioxide (pigment) Tronox Oppasin Blue 6900 (pigment) BASF 3M Glass Bubbles iM16K (additive (K)) 3M Expancel 051 DU 40 (additive (K)) AkzoNobel Rhenopren EPS (factice) LANXESS Deutschland GmbH

[0246] Test Methods:

[0247] Characterization of the Diene Rubber Gels and Sealing Gels

[0248] 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 analyzer (Mettler Toledo, Halogen Moisture Analyzer HG63). For this purpose, an aluminum pan (Mettler, article no. 13865) is inserted into the sample holder and tared. Then an HAF1 glass fiber filter (Mettler, article no. 214464) is placed on top and the measurement is started. Typically, the glass fiber filter in the course of storage absorbs about 0.5% air humidity. Subsequently, the aluminum pan with the dried glass fiber 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.

[0249] 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.

[0250] 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 aluminum 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.

[0251] 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.

[0252] 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 calendar 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).

[0253] Characterization of the Sealing Compound

[0254] The cohesion of the sealing compound is determined by the failure temperature (measurement parameter for cohesion), the SAFT test (Shear Adhesion Failure Temperature) which 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.

[0255] 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.

[0256] The frequency-dependent tan value at 20 C. can be 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).

[0257] 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.

[0258] 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.

[0259] 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.

[0260] The bending loss factor of the attenuating coating deposited on the steel strip becomes

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

[0261] Where [0262] f.sub.r,i is the i.sup.th maximum of the measured transfer function in Hz and [0263] 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).

[0264] The sample is suspended on two strings at the nodes of the flexural vibration. The distance

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

[0265] 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]$E_f^{}={\left(4.Math..Math..Math.\sqrt{3.Math..Math.}.Math.\frac{l^2}{h}\right)}^2.Math.{\left(\frac{f_{r,i}}{k_i^2}\right)}^2,$

[0266] The bending loss modulus is defined as

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

[0267] Where [0268] h is the thickness of the sample and [0269] k.sub.i.sup.2 is a constant depending on the measurement method; for method B k.sub.i.sup.2=22.4.

[0270] 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.

[0271] 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, -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.

[0272] Puncture-Sealing-Test (PST)

[0273] The non-instant sealing behaviour of the sealing compounds is determined by the puncture-sealing-test (PST) at ambient temperature. The test set-up consists of a glass pressure vessel simulating a tyre, which can be filled with nitrogen, a manometer for monitoring the pressure, a tyre cross section equipped with a 3 mm thick layer of the sealing compound. For this purpose, the sealing compound is pressed to a thickness of 3 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 the dimension of the tyre cross section is pressed onto the tyre section surface and positioned between the tyre cross section and the pressure vessel.

[0274] Before starting the test, the the pressure vessel is filled with nitrogen reaching a pressure of 2.5 bar. The pressure should stay constant over at least 12 hours. Puncturing is done by pressing a steel nail of 5 mm diameter into the tyre cross section so that at least a length of 2.5 cm of the nail is in the pressure vessel. After monitoring the pressure for 15 min, the nail is quickly taken out, and again the pressure is observed for further 15 min.

[0275] The sealing compound passes the PST test, if the pressure loss is between 0.1 and 1 bar, preferred between 0.15 and 0.8 bar in the first 25 min of total testing time and remains constant afterwards for a period of one week thereafter.

[0276] Elongation at Break Test Method.

[0277] The extension modulus of the sealing compound is understood to mean the apparent secant extension modulus obtained for a given uniaxial extension deformation , at first elongation (i.e. without an accomodatin cycle), measured at 23 C., pull rate 200 mm/min (ASTM D412 standard) using a Zwick Z005 Retroline tensile machine (manufacturer serial number: 146903, year of manufacture: 2000). This modulus is called the modulus E.

E=.Math.

[0278] Where [0279] is the elongation and [0280] is the stress.

[0281] The terms .sub.B and .sub.B are understood to mean the measured elongation and stress at break of the test piece (S2 dumbbells) of the compound.

[0282] Production and Characterization of the Diene Rubber Gels and Sealing Gels

[0283] There follows a description of the production of the cold-polymerized diene rubber gels (A) of the invention (A1, A2), (B) (B1, B2) and the gel (H) (H1), and the diene rubber gels A1 to A3 and B1 to B3 and the sealing gel H1 were used in the further examples. Also described is the production of hot-polymerized SBR comparative examples W1 that are not in accordance with the invention.

[0284] The diene rubber gels A1 to A3 and B1 to B3 and the sealing gels H1 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 (A), (B) and (W) and the sealing gels (H) are summarized in the following table:

TABLE-US-00002 TABLE 1 Emulsifiers Crosslinker Diene Solvent Oleic Dresinate Monomers TMPTMA DVB rubber gel Water [g] acid [g] [g] BDN [g] ST [g] [g] [g] A1 11939 80 171 3492 400 112.5 A2 11939 80 171 3892 112.5 B1 11939 80 171 3528 400 90.0 B2 11939 80 171 4193 134 H1 11939 80 171 3904 62.5 45 W1 11939 80 171 3528 400 75

(a) Emulsion Polymerization and Crosslinking of the BR and SBR Rubber

Examples A1 and A2, B1 and B2 and H1

[0285] The figures relate to 100% pure feedstocks. The diene rubber gels are produced in a 20 l 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.

[0286] 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 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.

[0287] The temperature was controlled during the polymerization by adjusting the coolant volume and coolant temperature at 100.5 C.

[0288] 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

[0289] 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.

(b) Workup of the Diene Rubber Gels

[0290] The precipitation of the diene rubber gel was conducted as follows:

[0291] 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 colorless and clear.

[0292] 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.

[0293] Subsequently, the polymer was dried down to a residual moisture content of 0.5% in a vacuum drying cabinet at 55 C.

[0294] The analytical data, determined by the methods described above, are reproduced in Table 2 below.

TABLE-US-00003 TABLE 2 Primary Gel (ML1+4) Conversion particle content Swelling index Tg Tg @100 C. [%] diameter [nm] [%] QI [ C.] [ C.] [MU] A1 93 42 88 24 70 7 183 A2 96 29 90 24 78 10 194 B1 92 41 94 12 69 6 77 B2 92 45 94 11 74 12 88 H1 96 35 74 10 76 13.3 88 W1 97 36 17 15 71 6 74

[0295] The cold-polymerized BR and 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.

[0296] The cold-polymerized SBR gels (H) 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 100 MU.

[0297] 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 cold-polymerized SBR rubber gels A1 and B1 of the invention and the sealing gels H1 with the corresponding hot-polymerized SBR rubber gels W1 which have 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 rubber gel cis [% by wt.] trans [% by wt.] vinyl [% 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

[0298] Cold-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.

[0299] Cold-polymerized sealing gels (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.

[0300] Production and characterization of sealing gels M1 to M7 of the invention and the sealing gel N not in accordance with the invention

[0301] The sealing gels M1 to M7 and N1 were produced on the basis of A1, A2, B1, B2, H1 and W1 on a Collin W 150 G roll mill built in April 2013. The roll temperature during the mixing operation was 60 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.

[0302] The compositions of the sealing gels (M) of the invention and of the sealing gel (N) that is not in accordance with the invention are 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 A1 B1 A2 B2 H1 W1 [% by [% by [% by [% by [% by [% by (ML1+4) @ 100 C. Sealing gel wt.] wt.] wt.] wt.] wt.] wt.] [MU] M1 70 30 0 0 0 0 168 M2 50 50 0 0 0 0 125 M3 30 70 0 0 0 0 103 M4 20 80 0 0 0 0 104 M5 0 0 0 0 100 0 124 M6 20 0 0 0 80 0 108 M7 0 0 70 30 0 0 113 N1 0 50 0 0 0 50 73

[0303] Production and characterization of the sealing compounds VV1 to VV3 that are not in accordance with the invention and the sealing compounds V1 to V5 of the invention

[0304] 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.

[0305] For the production of the sealing compounds V1 to V5 of the invention, the diene rubber gels A1, A2 and B1, B2 were first each mixed together homogeneously on the roll as described above to give the sealing gels M1 to M4 and M6 and M7. 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). For the production of the sealing compound V4 of the invention, the further additive (K) was added on the roller after the compound was cooled down to 60 C. and was mixed until the mixture appeared homogeneous.

[0306] The composition of the sealing compounds VV1 to VV3 that are 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 VV2 VV3 V1 V2 V3 V4 V5 Diene 25.5 0 0 25.5 25.5 0 25.5 0 rubber gel A1 [phr] Diene 59.5 80 40 59.5 59.5 0 59.5 85 rubber gel B1 [phr] Diene 0 0 0 0 0 25.5 0 0 rubber gel A2 [phr] Diene 0 0 0 0 0 59.5 0 0 rubber gel B2 [phr] Diene 0 0 40 0 0 0 0 0 rubber gel W1 [phr] Resin (C) 30 40 40 30 30 30 30 30 Escorez 2173 [phr] Ageing 1.5 1.5 1.5 3 3 3 3 3 stabilizer (D) Vulkanox HS LG [phr] Ageing 0 1.5 1.5 0 0 0 0 0 stabilizer (D) Vulkanox MB2/MG-C [phr] Ageing 1.5 0 0 3 3 3 3 3 stabilizer (D) Vulkanox 4020 [phr] Rubber (E) 0 20 20 0 0 0 15 15 Buna SE 1502H [phr] Rubber (E) 15 0 0 0 0 0 0 0 NR (SVR- 3 L ML (1 + 4) @100 C. = 20 MU) [phr] Rubber (E) 0 0 0 15 0 0 0 0 Keltan 2660 [phr] Plasticizer 40 40 40 40 50 40 55 30 (F) TDAE oil Vivatec 500 [phr] Plasticizer 0 0 0 0 15 15 0 0 (F) Rhenopren EPS [phr] Pigment (G) 0 1 1 0 0 0 0 0 Radglo GM- 25 [phr] Pigment (G) 0 0 0 1 1 1 0 0 Oppasin Blue [phr] Pigment (G) 0 0 0 1 1 1 0 0 Tronox [phr] Pigment (G) 3 0 0 0 0 0 3 3 Regal SRF [phr] Additive (K) 0 0 0 0 0 0 5 0 Expancel 051 DU 40 [phr] Additive (K) 0 0 0 0 0 0 0 25 Glass Bubbles iM16K [phr]

[0307] VV4 is commercially available sealing material used in Cinturato All Season Seal Inside brand tyres

[0308] The characterization of the sealing compounds \N1 to VV3 and V1 to V5 is compiled in Table 7 and 8 below.

TABLE-US-00007 TABLE 6 Sealing compound VV1 VV2 VV3 VV4 V1 V2 V3 V4 V5 (ML1+4) @ 100 C. [MU] 12 11 10 11 14 12 14 12 9.8 Pressure loss [bar] 0 0 0.11 0 0.6 0.23 0.49 0.57 0.59 tan @ 0.28 0.21 0.3 0.37 0.22 0.17 0.14 0.28 0.27 60 C. Failure temperature [ C.] 72 66 51 27 115 72 >175 71 88

[0309] The Mooney viscosity is determined by the methods described above on an Alpha Technologies MV 2000 Mooney viscometer.

[0310] The tan value is determined by the methods described above by means of an ARES-G2 rheometer from TA Instruments.

[0311] The elongation at break is determined by the methods described above on an Zwick Z005 Retroline machine. In one embodiment (V1) the .sub.B at 23 C. is 474% and .sub.B is 0.02 MPa.

[0312] The tan .sub.f at 20 C. determined by the methods described above for VV4 is 0.003 and for V4 is 0.019.

[0313] 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.

[0314] A sealing compound which is ready to use in practice has to pass both the puncture-sealing-test as described above and the SAFT test. The SAFT test is considered to have been passed when the failure temperature is greater than 70 C.

[0315] An overall assessment 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 VV4 V1 V2 V3 V4 V5 Puncture-sealing- F F P F P P P P P test assessment SAFT test P F F F P P P P P assessment Overall assessment F F F F P P P P P P means passed and F means failed.

[0316] The sealing compounds of the invention are notable in that they pass both tests.

[0317] The sealing compounds that are not in accordance with the invention fail at least one of the two tests.