INCREASED EFFICIENCY DESULFURIZATION REAGENTS

Abstract

Polymer masterbatch compositions, the production and use thereof, as well as vulcanizable rubber compounds comprising these masterbatch compositions, and their use for the production of moldings in the production of tires.

Claims

1. A masterbatch composition comprising: a diene homopolymer or a diene copolymer, and a phosphine desulfurization reagent, wherein the masterbatch composition has a gel content of less than 5%, as measured by gravimetric gel determination.

2. The masterbatch composition according claim 1, wherein the desulfurization reagent is a trivalent phosphine according to one of the general formula (I)-(IV):
P[(R).sub.a(OR).sub.b(NR.sub.2).sub.c(SR).sub.d(SiR.sub.3).sub.e](I) where 0a3; 0b2, 0c3, 0d3, and a+b+c+d+e=3
R.sub.2PPR.sub.2(II)
PR.sub.2R.sup.1[PRR.sup.1].sub.nPR.sub.2 with n=0 to 4(III)
P(R.sup.1PR.sub.2).sub.3(IV) where R, R.sub.2, R.sub.3 same or independently: H, linear and branched alkyl, aryl especially phenyl and alkylated phenyl, benzyl, polybutadienyl, polyisoprenyl, or polyacryl, halide, and R.sup.1 same or independently: alkylidene, ethylene glycole, propylene glycole, or di-substituted aryl.

3. The masterbatch composition according to claim 1, wherein the phosphine desulfurization reagent is in the form of a phosphonium salt of the formula (V),
[PR.sub.3R.sup.x].sup.+A.sup.(V) where R.sub.3 is the same or independently: H, linear and branched alkyl, aryl especially phenyl and alkylated phenyl, benzyl, polybutadienyl, polyisoprenyl, polyacryl, halide, R.sup.x is H, linear and branched alkyl, aryl especially phenyl and alkylated phenyl, benzyl, polybutadienyl, polyisoprenyl, polyacryl, and A.sup. is F.sup., Cl.sup., Br.sup., J.sup., OH.sup., SH.sup., BF.sub.4.sup., 1/2 SO.sub.4.sup.2, HSO.sub.4.sup., HSO.sub.3.sup., NO.sub.2.sup., NO.sub.3.sup., carboxylate RC(O)O.sup., dialkyl phosphate (RO).sub.2P(O)O.sup., dialkyl dithiophosphate (RO).sub.2P(S)S.sup., dialkyl phosphorothioate (RO).sub.2P(S)O.sup..

4. The masterbatch composition according to claim 1, wherein: the masterbatch composition has a decrease of less than 5% in Mooney viscosity (M.sub.L(1+4).sub.100 C.) when maintained at 25 C. for five days, and the masterbatch composition has a decrease of more than 25% in Mooney viscosity (M.sub.L(1+4).sub.100 C.) when maintained at 70 C. for seven days.

5. The masterbatch composition according to claim 4, wherein the masterbatch composition, when mixed with a rubber compound mixture comprising: a rubber, a filler, a coupling agent, and at least one crosslinking system comprising at least one crosslinker and optionally one or more crosslinking accelerators, does not decrease the Mooney viscosity (M.sub.L(1+4).sub.100 C.) of the rubber compound mixture.

6. The masterbatch composition according to claim 1, wherein the desulfurization reagent is present in an amount of from 0.01 to 5 phr, preferably 0.05 to 3 phr, and particularly preferred 0.1 to 2.5 phr.

7. The masterbatch composition according to claim 1, further comprising a coupling agent, wherein the coupling agent is a sulphur containing silane comprising a sulfane moiety and having a molar ratio of sulfur to silicium of less than 1.35:1, more preferably less than 1.175:1.

8. The masterbatch composition according to claim 1, wherein the diene homopolymer or the diene copolymer are obtained via copolymerization of conjugated diene monomers or conjugated diene monomers with vinylaromatic comonomers.

9. The masterbatch composition according to claim 1, wherein the diene homopolymer or the diene copolymer are one or more of polyisoprene, natural rubber, polybutadiene, or polybutadiene-styrene.

10. The masterbatch composition according to claim 1, wherein the desulfurization reagent is triphenyl phosphine.

11. A vulcanizable rubber compound comprising: the masterbatch composition according to claim 1, a rubber, a filler, a coupling agent, and at least one crosslinking system comprising at least one crosslinker and optionally one or more crosslinking accelerators.

12. The vulcanizable rubber compound according to claim 11, further comprising one or more further rubber auxiliaries.

13. The vulcanizable rubber compound according to claim 11, wherein the filler comprises a mixture of silica filler and carbon black filler, with a mixing ratio of silica filler to carbon black being 0.01:1 to 50:1.

14. The vulcanizable rubber compound according to claim 11, wherein the coupling agent is a sulphur containing silane comprising a sulfane moiety.

15. The vulcanizable rubber compound according to claim 11, wherein the coupling agent is one or more of bis[3-(triethoxysilyl)propyl]monosulfane, bis[3(triethoxysilyl)propyl]disulfane, bis[3-(triethoxysilyl)propyl]trisulfane and bis[3(triethoxysilyl)propyl]tetrasulfane.

16. A process for producing the vulcanizable rubber compound according to claim 11, the process comprising mixing together the masterbatch composition, the rubber, the silica filler, the coupling agent, and the at least one crosslinking system having at least one crosslinker, wherein the mixing does not decrease the Mooney viscosity (M.sub.L(1+4).sub.100 C.) of the vulcanizable rubber compound.

17. A process for producing vulcanizates, the process comprising vulcanizing the vulcanizable compound according to claim 11.

18. The process according to claim 17, wherein the vulcanizing is performed at a temperature of 100 C. to 200 C., preferably from 120 C. to 190 C.

19. Vulcanizates obtained by the process according to claim 17.

20. The vulcanizates according to claim 19, wherein the vulcanizates are shaped in the form of shaped bodies in the form of a drive belt, of roller coverings, of a seal, of a cap, of a stopper, of a hose, of floor covering, of sealing mats or sheets, profiles or membranes, tires, tire treads, or layers thereof.

Description

EXAMPLES

[0059] The following properties were determined in accordance with the stated standards:

DIN 52523/52524 Mooney viscosity M.sub.L(1+4).sub.100 C.
DIN 53505: Shore A hardness
DIN 53512: rebound resilience at 60 C.
DIN 53504: tensile test
DIN53513: dynamic damping via Eplexor equipmentEplexor equipment (Eplexor 500 N) from Gabo-Testanlagen GmbH, Ahlden, Germany was used to determine dynamic properties (temperature dependency of storage modulus E in the temperature range from 60 C. to 0 C. and also tan at 60 C.). The values were determined in accordance with DIN53513 at 10 Hz on Ares strips in the temperature range from 100 C. to +100 C. at a heating rate of 1 K/min.

[0060] The method was used to obtain the following variables, the terminology here being in accordance with ASTM 5992-96: tan (60 C.): loss factor (E/E) at 60 C., tan (60 C.) is a measure of hysteresis loss from the tire under operating conditions. As tan (60 C.) decreases, the rolling resistance of the tire decreases.

[0061] DIN 53513-1990: Elastic propertiesAn MTS elastomer test system (MTS Flex Test) from MTS was used to determine the elastic properties. The measurements were carried out in accordance with DIN53513-1990 on cylindrical samples (2 samples each 206 mm) with a total 2 mm compression at a temperature of 60 C. and a measurement frequency of 1 Hz in the range of amplitude sweep from 0.1 to 40%. The method was used to obtain the following variables, the terminology here being in accordance with ASTM 5992-96: G* (15%): dynamic modulus at 15% amplitude sweep; tan (max): maximum loss factor (G/G) of entire measuring range at 60 C.

[0062] The gel content and bound rubber of the masterbatch and the vulcanizable compounds, respectively, were determined by the gravimetric gel determination as described previously above.

[0063] Following substances were used in the compounds:

TABLE-US-00001 Tradename Producer BUNA CB 22 (Nd-Polybutadiene) Lanxess Deutschland GmbH BUNA CB 25 (Nd-Polybutadiene) Lanxess Deutschland GmbH BUNA Nd 24 EZ (Nd-Polybutadiene) Lanxess Deutschland GmbH BUNA PBR4070 (end-functionalized Lanxess Deutschland GmbH SSBR containing 37.5 phr of TDAE oil) VSL4526-0 HM (non-functionalized Lanxess Deutschland GmbH SSBR, clear grade) Zeosil 1165MP (silica) Solvay GmbH VIVATEC 500 (TDAE oil) Hansen und Rosenthal KG EDENOR C 18 98-100 (stearic acid) Caldic Deutschland GmbH VULKANOX 4010 NA/LG (stabilizer) Lanxess Deutschland GmbH VULKANOX 4020 LG (stabilizer) Lanxess Deutschland GmbH RHENOGRAN ZNO-80 (ZnO) Lanxess Deutschland GmbH VOLKANOX HS/LG (stabilizer) Lanxess Deutschland GmbH RHENOGRAN CBS-80 (accelerator) Lanxess Deutschland GmbH RHENOGRAN IS 90-65 (sulfur) Lanxess Deutschland GmbH ANTILUX 654 (ozone protection) Lanxess Deutschland GmbH SI 266 (silane) Evonik Industries AG Triphenylphosphine Sigma Aldrich GmbH

Examples

[0064] Preparation of a Masterbatch Containing Solution-SBR and Triphenylphosphine:

[0065] A masterbatch was prepared by first milling a solution-SBR VSL4526-0 HM at 80 C. using a nip of 4 mm thereby forming a rubber sheet, to which 2 phr of fine-powered phosphine was added and then further mixed until a homogeneous rubber sheet was obtained. The gel content of the masterbatch was determined to 0.33%.

[0066] Examples of a Decrease in Masterbatch Mooney Viscosity

[0067] Shown in Tables 1(a) and (b) are results of a comparison of the Mooney viscosities between an S-SBR and an S-SBR/TPP masterbatches (having 2 phr TPP) upon storage at various temperature conditions. The Mooney viscosity is measured via the conditions of ML(1+4).sub.100 C. and provided in the Table below in percentages standardized to 0 at day 0.

TABLE-US-00002 TABLE 1(a) Increased temperature Ex1 Ex2 Ex3 CE1 SSBR CE2 SSBR CE3 SSBR SSBR VSL4526- SSBR VSL4526- SSBR VSL4526- VSL4526- 0HM 2 phr VSL4526- 0HM 2 phr VSL4526- 0HM 2 phr 0HM TPP 0HM TPP 0HM TPP Mooney @ 23 C. Mooney @ 50 C. Mooney @ 70 C. days storage days storage days storage 0 0.0 0.0 0 0.0 0.0 0 0.0 0.0 5 0.8 0.4 7 0.9 30.4 5 2.8 45.2 11 0.2 0.2 17 2.8 43.0 11 2.5 59.8

TABLE-US-00003 TABLE 1(b) Increased temperature and shear in a Haake Rheomix 600p mixer at 10 rpm. Change in Mixer Mixer temp. Mixing Mooney TPP Temp. After mixing time viscosity Rubber phr C. time [ C.] [min] [%] ** CE4 110 120 11 1.9 BUNA CB 22 Ex 4 0.2 110 120 11 11.2 BUNA CB 22 CE5 120 130 11 22.9 BUNA CB 22 Ex 5 0.2 120 130 11 31.2 BUNA CB 22 CE6 130 140 12 20.6 BUNA CB 22 Ex 6 0.2 130 140 12 43.4 BUNA CB 22 ** Change in Mooney viscosity is measured upon allowing a sample to cool for 6 hours at ambient temperatures after completion of the mixing.

[0068] The following rubber compound mixture recipes (Table 2) were used for the following comparative study. All quantities mentioned below are provided in phr (parts per hundred).

TABLE-US-00004 TABLE 2 Reference 1 Reference 2 Example 1 Reference 3 Example 2 BUNA CB 25 20 20 20 BUNA Nd 24 EZ 20 20 ZEOSIL 1165MP 90 90 90 90 90 VIVATEC 500 2 2 2 36 36 AFLUX 37 2 2 2 2 2 EDENOR C 18 98-100 1.5 1.5 1.5 1 1 VULKANOX 4010 NA/LG 2 2 2 VULKANOX 4020 LG 1 1 VULKANOX HS/LG 1 1 1 1 1 ANTILUX 654 1 1 1 1 1 SI 266 6.7 6.7 6.7 6.5 RHENOGRAN CBS-80 2 2 2 1.6 1.6 RHENOGRAN IS 90-65 3.3 3.3 3.3 3.4 3.4 RHENOGRAN DPG-80 2 2 2 1.65 1.65 RHENOGRAN ZNO-80 5 5 5 3.8 3.8 PBR4070 110 110 PBR4070 Masterbatch 111.8 (containing 1.8 phr of TPP) SSBR VSL4526-0 HM 80 SSBR VSL4526-0 HM 81.8 Masterbatch (containing 1.8 phr of TPP) Triphenyl phosphine (TPP) 1.8 1.8

[0069] The compounds for references 1 to 3 were mixed as illustrated in the following mixing protocol. For references 2 and 3, the tri(phenyl)phosphine was added together with filler, silane, stearic acid and oil. Mixing was performed in a 1.5 L intermeshing mixer with a mixer speed of 40 rpm, an indenter pressure of 8 bar at a starting temperature of 70 C. The filling degree was 72%.

TABLE-US-00005 Step 1 mixer 0 sec addition of polymers addition of of filler, silane, stearic acid, oil and 30 sec optionally of TPP addition of of filler, silane, stearic acid, oil 90 sec addition of carbon black and optionally of TPP 150 sec addition of ZnO 210 sec heating to silanization temperature (150 C.) 390 sec stop Step 2 milling at 40 C., nip of 4 mm Cut sheet threetimes left and right, continue with three endwise passes Step 3 storage for 24 hours at 23 C. Step 4 mixer 0 sec addition of rubber sheet and heating to 150 C. 210 sec stop Step 5 Milling at 40 C., nip of 4 mm addition of sulphur and accelerator, cut sheet threetimes left and right, continue with three endwise passes

[0070] Examples 1 and 2 according to the invention, were mixed as illustrated in the following mixing protocol. Mixing was performed in a 1.5 L intermeshing mixer with a mixer speed of 40 rpm, an indenter pressure of 8 bar at a starting temperature of 70 C. The filling degree was 72%.

TABLE-US-00006 Step 1 mixer 0 sec addition of polybutadiene and masterbatch SSBR 30 sec addition of of filler, silane, stearic acid, oil and addition of of filler, silane, stearic acid, oil 90 sec addition of carbon black 150 sec addition of ZnO 210 sec heating to silanization temperature (150 C.) 390 sec stop Step 2 milling at 40 C., nip of 4 mm Cut sheet threetimes left and right, continue with three endwise passes Step 3 storage for 24 hours at 23 C. Step 4 mixer 0 sec addition of rubber sheet and heating to 150 C. 210 sec stop Step 5 Milling at 40 C., nip of 4 mm addition of sulphur and accelerator, cut sheet threetimes left and right, continue with three endwise passes

[0071] Per Table 3, the following are comparative results for the compounded materials and vulcanizates of the BR/SBR/silica mixtures of Table 2.

TABLE-US-00007 TABLE 3 Reference 1 Reference 2 Example 1 Reference 3 Example 2 ML Compound MU 76.6 87.21 88.21 47.3 47.2 Tensile strain at 100% stretch 23 C. MPa 2.2 2.4 3.3 1.7 2.2 60 C. MPa 2 2.3 3 1.5 1.8 Dynamic Damping 10 Hz tan d (0 C.) 0.392 0.54 0.6 0.498 0.529 tan d (60 C.) 0.101 0.069 0.064 0.107 0.107 MTS Amplitude Sweep 1 Hz, 60 C. tan d (max.) 0.154 0.118 0.098 0.152 0.145 G(0.5%)-G(15%)* [MPa] 0.927 0.401 0.283 0.310 0.250 Rebound at 23 C. % 27 31.5 32.33 30 32 at 60 C. % 55 63.5 68 55 57 Abrasion DIN 53516 mm.sup.3 92 79 77 102 91 Hardness at 23 C. Shore A 62.9 60.7 64.8 54.2 55.9 at 60 C. Shore A 60.0 60.0 62.0 60.0 60.0 Gel content % 23.72 36.67 39.27 *a small Payne Effect is described by a small difference of G at small and large amplitude.

[0072] Comparing reference 1 (without desulfurization reagent) and reference 2 (triphenylphosphine as desulfurization reagent, added in step 1 of the mixing procedure), a significant improvement in rolling resistance parameters, such as an increase in rebound at 60 C., a decrease in tan d (60 C.) from the dynamic damping experiment and a decrease in tan d max from the amplitude sweep experiment at 60 C. is observed. An increase in tan d (0 C.) in the dynamic damping experiment indicates an improved wet grip. In addition, abrasion is diminished. The difference G(0.5%)G(15%) from the amplitude sweep measurement is reduced indicating improved rubber-filler interactions which is further confirmed by an increase of bound rubber. Concerning measurements which correlate with stiffness of the vulcanisates which is known to be important for handling of a tire having this tread compound, the addition of a desulfurization reagent to the mixing process shows no effect. This is expressed by only marginal changes in the tensile strain at 100% stretch and constant hardness at 60 C. or even a softening effect at 23 C.

[0073] In Example 1 using a solution-SBR/triphenylphosphine masterbatch the same amount of desulfurization reagent is used as in reference 2. All rolling resistance relevant parameters (rebound at 60 C., decrease in loss factor tan d at 60 C. in dynamic damping experiments and tan d max in amplitude sweep measurement at 60 C. show a distinct and considerable improvement. Further the tan d (0 C.) indicates further improved wet grip. Payne Effect decreases by 30% and bound rubber increases by another 2.6% in comparison to the desulfurization reagent containing reference 2. It is further noteworthy that the Compound Mooney viscosity is not diminished despite using the thermal- and shear sensitive masterbatch.

[0074] In contrast to reference 2, example 1 exhibits substantial improvement in stiffness e.g. the tensile strength at 100% stretch and 23 C. increases by 37% and 30% at 60 C., respectively (referred to the desulfurization reagent containing reference 2). Hardness at 60 C. increases by 2 Shore A in comparison to reference 1 and 2 and by 1.8 Shore A referred to reference 1 and 4.1 Shore A referred to reference 2, respectively. This evidences that the use of the inventive masterbatch of a desulfurization reagent in a rubber, as it is described here, improves he properties significantly although the overall recipe itself remains the same.

[0075] A comparison of reference 3 with example 2 further provides the evidence that this beneficial effect of a masterbatch of desulfurization reagents in SBR can be obtained with non-functionalized S-SBR as well. The indicative parameters described above suggest reduced rolling resistance, improved wet grip and increased stiffness. Again, this can be attributed to an improved rubber-filler and reduced filler-filler interaction as illustrated in a lower Payne Effect achieved by an intermediate Mooney drop of the masterbatch.

[0076] Per the above, it was surprisingly found that the masterbatch composition will have a stable Mooney viscosity at ambient conditions, a decreased Mooney viscosity upon application of a stressing condition, which allows improved dispersibility of the auxiliaries and which masterbatch composition when added to a rubber compound does not decrease the Mooney viscosity of such a compound. As such, it should be appreciated that the rubber masterbatch composition allows a more effective increase of rubber-filler interaction resulting in an unexpected increase in performance.