Mercaptosilane-carbon black blend

Abstract

The invention provides mercaptosilane-carbon black blends comprising at least 20 wt. % of mercaptosilanes of the general formula I ##STR00001##
and carbon black, the mercaptosilane-carbon black blend having an iron content of <9 ppm. They are produced by mixing the mercaptosilanes of the general formula I with the carbon black. They can be used in rubber mixtures.

Claims

1. Mercaptosilane-carbon black blend, comprising at least 20 wt. % of mercaptosilane of the general formula I ##STR00008## based on the mercaptosilane-carbon black blend, wherein R.sup.1 is an alkyl polyether group O(R.sup.5O).sub.m R.sup.6, with R.sup.5, identical or different at each occurrence, being a branched or unbranched, saturated or unsaturated, aliphatic divalent C1-C30 hydrocarbon group, m being on average 1 to 30, and R.sup.6 consisting of at least 1 C atom and being an unsubstituted or substituted, branched or unbranched monovalent alkyl, alkenyl, aryl or aralkyl group, R.sup.2 is identical or different at each occurrence and is an R.sup.1, C1-C12 alkyl or R.sup.7O group, with R.sup.7 being H, methyl, ethyl, propyl, C9-C30 branched or unbranched monovalent alkyl, alkenyl, aryl or aralkyl group or (R.sup.8).sub.3Si group, with R.sup.8 being C1-C30 branched or unbranched alkyl or alkenyl group, R.sup.3 is a branched or unbranched, saturated or unsaturated, aliphatic, aromatic or mixed aliphatic/aromatic divalent C1-C30 hydrocarbon group, and R.sup.4 is H, CN or (CO)R.sup.9, with R.sup.9 being a branched or unbranched, saturated or unsaturated, aliphatic, aromatic or mixed aliphatic/aromatic monovalent C1-C30 hydrocarbon group, and carbon black, wherein the mercaptosilane-carbon black blend has an iron content of <9 ppm.

2. Mercaptosilane-carbon black blend according to claim 1, wherein it comprises a mixture of mercaptosilanes of the general formula I.

3. Mercaptosilane-carbon black blend according to claim 1, wherein the mixture of mercaptosilanes of the general formula I comprises ##STR00009## and/or hydrolysis and/or condensation products of the aforementioned compounds.

4. Method for producing mercaptosilane-carbon black blend according to claim 1, wherein at least 20 wt. % of mercaptosilane of the general formula I, based on the mercaptosilane-carbon black blend, is mixed with carbon black, the carbon black having an iron content of <9 ppm.

5. Rubber mixture wherein it comprises (A) a rubber or mixture of rubbers, (B) a filler and (C) at least one mercaptosilane-carbon black blend according to claim 1.

6. Method for producing the rubber mixture containing (a) a rubber or mixture of rubbers, (b) a filler and (c) at least one mercaptosilane-carbon black blend, comprising, mixing at least one mercaptosilane-carbon black blend according to claim 1, the rubber or mixture of rubbers, the filler, optionally further rubber assistants.

7. A process for producing a shaped article comprising, providing a rubber mixture, which includes the mercaptosilane-carbon black blend according to claim 1, and moulding the mixture to form the shaped article.

8. A process according to claim 7, wherein the shaped article is pneumatic tyres, tyre treads, cable sheathing, hoses, drive belts, conveyor belts, roll coverings, tyres, footwear soles, sealing rings or damping elements.

Description

EXAMPLES

(1) Determination of Iron Content in Mercaptosilane-carbon Black Blend

(2) Total Iron Assay After High-pressure Ashing Using ICP-MS:

(3) Approximately 200-300 mg of the mercaptosilane-carbon black blend, are weighed out to an accuracy of 0.1 mg into a vessel made of vitreous silica.

(4) 10 ml of HNO3 (approximately 65 wt. %, super-pure) are added and the sample is digested completely in a pressure vessel at a temperature from at least 280 C. to not more than 500 C.

(5) Thereafter the digestion product is made up to 50 ml with water (ultra-pure) and transferred to a volumetric flask (plastic).

(6) Digestion takes place with a duplicate determination.

(7) Prior to each digestion, 1 ml is introduced into a test-tube and made up to 10 ml with water (ultra-pure).

(8) Each solution is subjected to measurement in an inductively coupled plasma mass spectrometer (ICP-MS) with a calibration.

(9) For the calibration, four reference solutions and one blank solution are produced from a standard solution, based on an NIST reference material.

(10) Corresponding chemical blank values are subjected to measurement together with the sample solutions. An internal standard is added at the same concentration to all of the measurement solutions.

(11) Determination of Carbon Black by Sieve Residue

(12) The 325 mesh sieve residue is determined in accordance with ASTM D1514, in ppm.

(13) STSA Surface Area

(14) The STSA is determined in accordance with ASTM D 6556.

(15) OAN Number

(16) The OAN is determined in accordance with ASTM D 2414.

(17) Shelf Life, Determination by GPC:

(18) Procedure:

(19) The acetonitrile extracts are analyzed on a GPC column. To quantify the amounts of silane, a 1-point calibration is carried out with a pure specimen of the particular silane being assayed.

(20) Instrument Settings:

(21) HPLC system: HPLC pump S2100 from SFD, Autosampler SIL10-AF from Shimadzu, RI detector 7515A from ERC, Controller CBM-20A from Shimadzu analysis software Class VP5 from Shimadzu

(22) Preliminary column: MZ-gel SDplus 50 5 503 mm, from MZ-Analysentechnik

(23) Analytic column: MZ-gel SDplus 50 5 3008 mm, from MZ-Analysentechnik

(24) Mobile phase: 100% methyl ethyl ketone (MEK)

(25) Flow rate: 1.0 ml/min

(26) Metering volume: 30 l Analysis temperature: room temperature 20 C.

(27) 10 g of product are admixed with 180 ml of acetonitrile and stirred for 2 hours, then filtered, diluted 1:1 with methyl ethyl ketone, and injected.

(28) The parameter evaluated is the peak area of the respective silane in the HPLC chromatogram of the RI detector (no GPC molar mass evaluation).

(29) In the comparative examples, the reference carbon block used is N 330 (iron content: 16 ppm), and Purex HS 45 (iron content: 6 ppm) is used in the inventive examples (both commercial products from Orion Engineered Carbons). The mercaptosilane of the formula I that is used is Si 363 ((R*O).sub.3Si(CH.sub.2).sub.3SH with R*C.sub.13H.sub.27(OC.sub.2H.sub.4).sub.n and C.sub.2H.sub.5, average C.sub.2H.sub.5 content=33%, average number n=5) from Evonik Industries.

Example 1

(30) A Henschel mixer is charged with 1 kg of carbon black (a: N 330, b: Purex HS 45). At a through-flow temperature of 20 C., a rotary speed of 1500 rpm and a pressure of 40 bar, in one stage with a nozzle diameter of 0.5 mm, 462 g of mercaptosilane Si 363 are added until a final mixing temperature of 62-65 C. is reached (fill level: 45%).

(31) The shelf life is determined by storing the mercaptosilane-carbon black blends at T=20 C. and 60% atmospheric humidity for 18 days.

(32) The measurement for the comparative mercaptosilane-carbon black blend (a: N 330/Si 363 11 ppm Fe) after storage gives 7-1 wt. % of Si 363, relative to the theoretical value. The measurement for the inventive mercaptosilane-carbon black blend (b: Purex 45/Si 363 4 ppm Fe) after storage gives 85 wt. % of Si 363, relative to the theoretical value.

Example 2

(33) The formula used for the rubber mixtures is shown in Table 1 below. In the table, the unit phr denotes weight fractions relative to 100 parts of the crude rubber used.

(34) TABLE-US-00001 TABLE 1 Amount Amount Amount Substance [phr] [phr] [phr] 1st stage Reference Reference Inventive rubber rubber rubber mixture I mixture II, mixture, in situ containing containing mercaptosilane- mercaptosilane- carbon black carbon black blend as per blend as per Example 1a Example 1b Buna VSL 5025-1 96 96 96 Buna CB 24 30 30 30 Ultrasil 7000 GR 80 80 80 ZnO 3 3 3 Stearic acid 2 2 2 Naftolen ZD 10 10 10 Vulkanox 4020 1.5 1.5 1.5 Corax N 330 10 Protektor G 3108 1 1 Si 363 10 Mercaptosilane- 20 20 carbon black blend 2nd stage Batch stage 1 3rd stage Batch stage 2 Perkacit TBzTD 0.2 0.2 0.2 Vulkacit CZ 1.5 1.5 1.5 Sulphur 2.2 2.2 2.2

(35) The polymer VSL 5025-1 is a solution polymerized SBR copolymer from Bayer AG, having a styrene content of 25 wt. % and a butadiene content of 75 wt. %. The copolymer contains 37.5 phr of oil and has a Mooney viscosity (ML 1+4/100 C.) of 50.

(36) The polymer Buna CB 24 is a cis-1,4-polybutadiene (neodymium type) from Bayer AG, having a cis-1,4 content of at least 96% and a Mooney viscosity of 445.

(37) Ultrasil 7000 GR is a readily dispersible silica from Evonik Industries AG and has a BET surface area of 170 m.sup.2/g. Corax N330 is a carbon black from Orion Engineered Carbons with an STSA surface area of 76 in.sup.2/g.

(38) Naftolen ZD from Chemetall is used as aromatic oil; Vulkanox 4020 is 6PPD from Bayer AG, and Protektor G3108 is an ozone protection wax from Paramelt B.V. Vulkacit D (DPG) and Vulkacit CZ (CBS) are commercial products of Bayer AG, Perkacit TBzTD (Tetrabenzylthiuram disulphide) is a product from Flexsys N.V.

(39) The rubber mixture is produced in three stages in an internal mixer in accordance with Table 2.

(40) TABLE-US-00002 TABLE 2 Stage 1 Settings Mixing Werner & Pfleiderer GK 1.5E assembly Rotary speed 70 min.sup.-1 Ram pressure 5.5 bar Through-flow 80 C. temp. Mixing 0 to 1 min Buna VSL 5025-1 + Buna CB 24 1 to 2 min Ultrasil 7000 GR, ZnO, stearic acid, Naftolen ZD, carbon black, silane-carbon black blend 2 to 4 min Ultrasil 7000 GR, Vulkanox 4020, Protektor G3108 4 to 5 min Mixing (changing rotary speed if necessary) at 155 C. 5 min Aerating 5 to 6 min Mixing and discharging Batch temp. 150-160 C. Storage 24 h at 20 C. Stage 2 Settings Mixing As in stage 1 except for: assembly Rotary speed 80 min.sup.-1 Mixing 0 to 2 min Breakup stage 1 batch 2 to 5 min Maintain batch temperature 155 C. by speed variation 5 min Discharging Batch temp. 150-160 C. Storage 4 h at 20 C. Stage 3 Settings Mixing As in stage 1 except for: assembly Rotary speed 40 min.sup.-1 Through-flow 50 C. temp. Mixing 0 to 0.5 min Stage 2 batch 0.5 to 2 min Accelerant(s) and sulphur 2 min Discharge and form milled sheet on laboratory mixing rolls (Diameter 200 mm, length 450 mm, through-flow temperature 50 C.) Homogenizing: cut in 5* left, 5* right and fold over and roll 3* with narrow roll nip (3 mm) and 3* with wide roll nip (6 mm) and then draw off a milled sheet Batch temp. <110 C.

(41) The general method for producing rubber mixtures and vulcanizates thereof is described in Rubber Technology Handbook, W. Hofmann, Hanser Verlag 1994.

(42) Technical rubber testing takes place in accordance with the test methods specified in Table 3.

(43) TABLE-US-00003 TABLE 3 Physical testing Standard/conditions ML 1 + 4, 100 C. (3rd stage) DIN 53523/3, ISO 667 Ring tensile test, 23 C. DIN 53504, ISO 37 Tensile strength Stress values Elongation at break Shore A hardness, 23 C. DIN 53 505 Ball rebound, 60 C. DIN EN ISO 8307 Steel ball 19 mm, 28 g DIN abrasion, 10 N force DIN 53 516 Viscoelastic properties DIN 53 513, ISO 2856 0 and 60 C., 16 Hz, 50 N initial force and 25 N amplitude force Complex modulus E* (MPa) Loss factor tan ()

(44) Table 4 reports the technical rubber data for crude mixture and vulcanizate.

(45) TABLE-US-00004 TABLE 4 Inventive rubber mixture containing mercapto- silane- carbon Reference black rubber Reference blend as mixture I rubber per in situ mixture II Example 1b Crude mixture results ML (1 + 4) at 100 C., 3rd [MU] 64 107 64 stage Vulcanizate results Stress value 100% [MPa] 2 1.9 1.9 Elongation at break [%] 290 305 315 DIN abrasion [mm.sup.3] 73 81 77 Ball rebound, 70 C. [%] 70.2 61.1 69.1 MTS, 16 Hz, 50 N Initial force, 25 N Amplitude force Loss factor tan , [] 0.888 0.134 0.091 60 C.

(46) It is found that only in the case of the inventive rubber mixture is it possible to achieve the values of the in situ mixture (reference rubber mixture I). Reference rubber mixture II, which contains a carbon black with an iron fraction greater than 9 ppm, exhibits marked disadvantages in viscosity and in the dynamic data, corresponding to a significantly poorer rolling resistance.

Example 3

(47) The formula used for the rubber mixtures is given in Table 5 below. The unit phr denotes weight fractions relative to 100 parts of the crude rubber used.

(48) The silane-carbon black blend X 50-S (Si 69 on N 330) used for the reference rubber mixtures is available commercially from Evonik Industries.

(49) TABLE-US-00005 TABLE 5 Amount Amount Substance [phr] [phr] 1st stage Reference Inventive rubber rubber mixture mixture containing III mercaptosilane- carbon black blend as per Example 1b Buna VSL 5025-1 96 96 Buna CB 24 30 30 Ultrasil 7000 GR 80 80 ZnO 3 3 Stearic acid 2 2 Naftolen ZD 10 10 Vulkanox 4020 1.5 1.5 Protektor G 3108 1 1 X 50-S 12.8 Silane-carbon 20 black blend 2nd stage Batch stage 1 3rd stage Batch stage 2 Vulkacit D 2 0 Perkacit TBzTD 0.2 0.5 Vulkacit CZ 1.5 1.5 Sulphur 1.5 2.2

(50) The polymer VSL 5025-1 is a solution polymerized SBR copolymer from Bayer AG, having a styrene content of 25 wt. % and a butadiene content of 75 wt. %. The copolymer contains 37.5 phr of oil and has a Mooney viscosity (ML 1+4/100 C.) of 50.

(51) The polymer Buna CB 24 is a cis-1,4-polybutadiene (neodymium type) from Bayer AG, having a cis-1,4 content of at least 96% and a Mooney viscosity of 445.

(52) Ultrasil 7000 GR is a readily dispersible silica from Evonik Industries AG and has a BET surface area of 170 m.sup.2/g.

(53) Naftolen ZD from Chemetall is used as aromatic oil; Vulkanox 4020 is 6PPD from Bayer AG, and Protektor G3108 is an ozone protection wax from Paramelt B.V. Vulkacit D (DPG) and Vulkacit CZ (CBS) are commercial products of Bayer AG. Perkacit TBzTD (Tetrabenzylthiuram disulphide) is a product from Flexsys N.V.

(54) The rubber mixture is produced in three stages in an internal mixer in accordance with Table 2.

(55) The general method for producing rubber mixtures and vulcanizates thereof is described in Rubber Technology Handbook, W. Hofmann, Hanser Verlag 1994.

(56) Technical rubber testing takes place in accordance with the test methods specified in Table 3.

(57) Table 6 reports the technical rubber data for crude mixture and vulcanizate.

(58) TABLE-US-00006 TABLE 6 Inventive rubber mixture containing Methods mercaptosilane- (vulcanization Reference carbon black time: 25 min at rubber mixture blend as per 165 C.) III Example 1b Tensile strength [MPa] 13.0 14.7 Modulus 100% [MPa] 2.5 2.2 Modulus 300% [MPa] 12.2 10.6 Modulus 300%/ [] 4.9 4.8 100% Elongation at [%] 310 370 break Shore A hardness [SH] 70 71 Ball rebound, RT [%] 36 42 DIN Abrasion [mm.sup.3] 83 77 Tear propagation [N/mm] 18 40 resistance MTS, 16 Hz, 50 N +/ 25 N E*, 0 C. [MPa] 33.5 29 E*, 60 C. [MPa] 13.0 13.9 E, 0 C. [MPa] 12.0 8.8 E, 60 C. [MPa] 1.5 1.2 tan , 0 C. [] 0.390 0.314 tan , 60 C. [] 0.112 0.088

(59) In comparison to the reference rubber mixture III, the inventive rubber mixture comprising the mercaptosilane-carbon black blend, as per Example 1b exhibits better tensile strength, greater elongation at break, lower DIN abrasion (corresponding to reduced wear), a significantly higher tear propagation resistance, a very low tan at 60 C. (corresponding to a level reduced by 20% relative to the X50-S reference), which is an indicator of a significantly improved rolling resistance.