EP1198504A1 - Couplage de caoutchouc de noir de charbon par mercaptopyridines - Google Patents

Couplage de caoutchouc de noir de charbon par mercaptopyridines

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Publication number
EP1198504A1
EP1198504A1 EP00962417A EP00962417A EP1198504A1 EP 1198504 A1 EP1198504 A1 EP 1198504A1 EP 00962417 A EP00962417 A EP 00962417A EP 00962417 A EP00962417 A EP 00962417A EP 1198504 A1 EP1198504 A1 EP 1198504A1
Authority
EP
European Patent Office
Prior art keywords
rubber
carbon black
sulfur
process according
vulcanization
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP00962417A
Other languages
German (de)
English (en)
Inventor
Rabindra Nath Datta
Nicolaas Maria Huntink
Paulus Gerhardus Johannes Nieuwenhuis
Auke Gerardus Talma
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Flexsys BV
Original Assignee
Flexsys BV
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Flexsys BV filed Critical Flexsys BV
Priority to EP00962417A priority Critical patent/EP1198504A1/fr
Publication of EP1198504A1 publication Critical patent/EP1198504A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/36—Sulfur-, selenium-, or tellurium-containing compounds
    • C08K5/37—Thiols
    • C08K5/378—Thiols containing heterocyclic rings

Definitions

  • the invention relates to a sulfur vulcanization process comprising (a) a non-productive stage of mixing of a rubber composition comprising a polyisoprene rubber and carbon black, (b) a productive stage of mixing of a rubber composition further comprising sulfur and a vulcanization accelerator, and (c) vulcanization of said rubber composition. It further relates to rubber articles comprising the rubber vulcanizate obtained by said process.
  • Rubber compositions typically contain a reinforcing filler such as carbon black or a combination of carbon black with a light-coloured filler such as silica.
  • a reinforcing filler such as carbon black or a combination of carbon black with a light-coloured filler such as silica.
  • a known problem of rubber vulcanizates containing reinforcing fillers is the poor interaction between the filler and the rubber, which leads to deteriorated physical and dynamic properties of the vulcanizate, in particular increased hysteresis and increased heat build-up. This problem is particularly relevant to rubber compositions comprising a polyisoprene rubber such as natural rubber.
  • silica is included as the reinforcing filler, in particular in so-called green tyres, to incorporate a silane coupling agent into the rubber composition before vulcanization.
  • carbon black coupling agents are also known in the art, see for example T. Yamaguchi et al. in Kautschuk Gu mi Kunststoffe, Vol. 42, No. 5, 1989, pages 403-409, which describes a coagent called Sumifine ® (i.e. N,N'-bis(2-methyl-2-nitropropyl)-1 ,6-diaminohexane), and L. Gonzalez et al. in Rubber Chemistry and Technology, Vol. 69, 1996, pages 266-272, they are not used commercially, most likely due to the toxic/carcinogenic byproducts formed during decomposition.
  • carbon black has been the most widely used reinforcing filler in the rubber industry, and it is often used in combination with a smaller amount of silica.
  • the problem of carbon black to rubber coupling has not been adequately solved so far, hence, there still is a need in the art for effective carbon black coupling coagents.
  • the coagents in accordance with the present invention have the effect of improving the hysteresis and heat build-up properties of carbon black-reinforced polyisoprene rubber vulcanizates and showing a decreased Payne effect.
  • the process according to the present invention is characterized in that the non-productive stage of mixing is carried out in an internal mixer in the presence of 0.1 to 5 phr of a carbon black coupling coagent according to any one of formulae l-IV:
  • R 1 , R 2 , and R 3 independently represent H or a C,-C 5 hydrocarbon group, optionally containing one or more oxygen, nitrogen or sulfur atoms,
  • the abbreviation "phr” means the number of parts by weight per 100 parts by weight of rubber. In the case of a rubber blend, it is based on 100 parts by weight of total rubber.
  • mercaptopy ⁇ dines according to formulae l-IV are already known to the person skilled in the art of rubber vulcanization and for example have been described in the following documents
  • SU-A-960203 discloses a sulfur vulcanization process wherein a composition comprising an unsaturated rubber such as cis-polybutadiene, 0 5-3 0 phr of zinc oxide, and 0 5-1 5 phr of zinc 2-pyr ⁇ dylth ⁇ oox ⁇ de (further referred to in this application as zinc 2-mercaptopyr ⁇ d ⁇ ne N-oxide) is vulcanized
  • the rubber composition is prepared on a roll mill It is mentioned that the rubber vulcanizates obtained by this process have an increased dynamic fatigue resistance
  • carbon black coupling is less of a problem for rubber compositions comprising cis- polybutadiene or butadiene-nit ⁇ le rubber
  • JP-A-04068042 discloses a vulcanizable rubber composition comprising 0.1 to 10 phr of a pyridine compound such as 2-mercaptopyrid ⁇ ne, 2- mercaptopyndine-N-oxide, 2,2'-d ⁇ thiodipyridine, and 2,2'-dithiob ⁇ s(pyridine- N-oxide) and 0.1-8 phr of sulfur It is mentioned in the description that the pyridine compound is used as a vulcanizer and that the rubber vulcanizates have anti-scorching properties and heat resistance
  • carbon black coupling coagents according to formulae l-IV can be prepared by synthetic methods that are known to a person skilled in the art and using conventional equipment
  • the 5 or 6-membered ring may be saturated or unsaturated, preferably unsaturated
  • R 1 , R 2 , and R 3 represent H
  • the C r C 5 hydrocarbon group is a C r C 5 alkyl group, most preferably a methyl group
  • the hydrocarbon group or ring is unsubstituted and does not contain an oxygen, nitrogen or sulfur atom.
  • n is 2
  • M is Zn.
  • x is 1
  • the polyisoprene rubber that is used in accordance with the invention process may be a natural rubber such as natural rubber (NR), a synthetic rubber such as isoprene rubber (IR) or a mixture thereof
  • NR natural rubber
  • IR isoprene rubber
  • the rubber composition comprises NR Blends of a polyisoprene rubber with one or more other rubbers such as polybutadiene rubber or butadiene rubber (BR), styrene-butadiene rubber (SBR), and a mixture of BR and SBR may also be used
  • the rubber blend contains more than 80 parts by weight of the natural rubber per 100 parts by weight of the total rubber blend
  • a sulfur-vulcanizable rubber composition in accordance with the present invention typically contains 10 to 80, preferably 20 to 60, more preferably 40 to 60 phr of carbon black and 0 to 80, preferably 0 to 60, more preferably 0 to 40 phr of silica.
  • the amount of carbon black coupling coagent employed in the process of the present invention is 0.2 to 4, more preferably 0.25 to 2, most preferably 0.5 to 1 phr.
  • sulfur a sulfur donor or a mixture thereof is employed.
  • the amount of sulfur to be compounded with the rubber usually is 0.1 to 10, preferably 0.1 to 5, more preferably 0.5 to 3 phr. If a sulfur donor is used, the amount thereof should be calculated in terms of the amount of sulfur.
  • Typical examples of sulfur donors that can be used in accordance with the present invention include dithiodimorpholine, caprolactam disulfide, tetramethylthiuram disulfide, and dipentamethylenethiuram tetrasulfide.
  • the reader is referred to W. Hofmann, Rubber Technology Handbook, Hanser Publishers, Kunststoff 1989, in particular pages 231-233.
  • vulcanization accelerators that can be used in accordance with the present invention the reader is referred to W. Hofmann, Rubber Technology Handbook, Hanser Publishers, Kunststoff 1989.
  • Typical vulcanization accelerators include thiazole- and benzothiazole- based accelerators, for example 2-mercaptobenzothiazole and bis(2- benzothiazolyl) disulfide, benzothiazole-2-sulfenamide-based accelerators, such as N-cyclohexyl-benzothiazole-2-sulfenamide (CBS), N-tert-butyl- benzothiazole-2-sulfenamide, N,N-dicyclohexyl-benzothiazole-2- sulfenamide, and 2-(morphol ⁇ noth ⁇ o)benzoth ⁇ azole, thiophospho ⁇ c acid derivatives, thiurams, dithiocarbamates, diphenylguanidine, diorthotolyl guanidine, dithiocarbamyl sulfenamides, xanthates, and mixtures of one or more of these accelerators
  • the vulcanization accelerator comprises a benzothi
  • the vulcanization accelerator usually is employed in an amount of 0 1 to 5, preferably 0 3 to 3, most preferably 0 5 to 2 5 phr
  • the carbon black coupling coagent used in accordance with the present invention is present in the invention process in a lower amount than the amount of vulcanization accelerator
  • a typical sulfur-vulcanizable rubber composition to be used in the process in accordance with the present invention comprises a polyisoprene rubber, preferably comprising NR, 0 1 to 10 phr of sulfur and/or a sulfur donor, 0 1 to 5 phr of a vulcanization accelerator, preferably comprising a benzoth ⁇ azole-2-sulfenam ⁇ de, 10 to 80 phr of carbon black, 0 to 80 phr of silica, and 0 1 to 5 phr of a carbon black coupling coagent according to any one of formulae l-IV, preferably according to formula I or III
  • the composition comprises 0 1 to 5 phr of sulfur and/or sulfur donor, 0 3 to 3 phr of a vulcanization accelerator, 20 to 60 phr of carbon black, 0 to 60 phr of silica, and 0 2 to 4 phr of a carbon black coupling coagent
  • Conventional rubber additives may also be included in the vulcanizable rubber composition in accordance with the present invention.
  • Examples include processing oils tackifiers, waxes, (phenolic) antioxidants, (phenylenediamine) antidegradants, antiozonants, pigments, e g titanium dioxide, resins, plasticizers, factices, and vulcanization activators, such as stea ⁇ c acid and zinc oxide
  • processing oils tackifiers waxes, (phenolic) antioxidants, (phenylenediamine) antidegradants, antiozonants, pigments, e g titanium dioxide, resins, plasticizers, factices, and vulcanization activators, such as stea ⁇ c acid and zinc oxide
  • vulcanization inhibitors i e scorch retarders, such as cyclohexyl- thiophthalimide, phthalic anhydride, pyromellitic anhydride, benzene hexacarboxy c t ⁇ anhydnde, 4-methylphthal ⁇ c anhydride, trimellitic anhydride, 4-chlorophthal ⁇ c anhydride, salicylic acid, benzoic acid, maleic anhydride, citraconic anhydride, itaconic anhydride, and N-nitrosodiphenyl- amine may be included in conventional, known amounts
  • scorch retarders such as cyclohexyl- thiophthalimide, phthalic anhydride, pyromellitic anhydride, benzene hexacarboxy c t ⁇ anhydnde, 4-methylphthal ⁇ c anhydride, trimellitic anhydride, 4-chlorophthal ⁇ c anhydride, salicylic acid, benzoic acid, maleic an
  • steel-cord adhesion promoters such as cobalt salts and dithiosulfates in conventional, known quantities
  • vulcanization process of the present invention can be carried out using means and equipment that are well-known to a person skilled in the art Suitable vulcanization procedures are described in W Hofmann, Rubber Technology Handbook, Hanser Publishers, Kunststoff 1989
  • a typical method comprises preparing a masterbatch comprising a polyisoprene rubber, carbon black, optionally silica, a vulcanization activator, a processing oil, and the carbon black coupling coagent in accordance with the present invention in an internal mixer such as a Banbury mixer or a Werner & Pfieiderer mixer i e , the non-productive stage of mixing, and subseguently adding a vulcanization system comprising sulfur and a vulcanization accelerator to the masterbatch on a two-roll mill, i e the productive stage of mixing
  • the uncured rubber composition is then vulcanized by heating, e g , by compression moulding
  • a carbon black coupling agent according to formula III and IV with x is 1.5 or 2, it should be ensured that the temperature in the internal mixer does not become too high.
  • the invention vulcanization process typically is carried out at a temperature of 110-200, preferably 120-190, more preferably 140-180°C for a period of time of up to 12, preferably up to 6, more preferably up to 3 hours.
  • the present invention also pertains to articles of manufacture, such as pneumatic tyres, e.g., for passenger cars and trucks, and industrial rubber goods, which comprise the rubber vulcanizate obtained by the invention process.
  • articles of manufacture such as pneumatic tyres, e.g., for passenger cars and trucks, and industrial rubber goods, which comprise the rubber vulcanizate obtained by the invention process.
  • a masterbatch of rubber, carbon black, stearic acid, zinc oxide, processing oil, antidegradant, and carbon black coupling coagent was made in an internal mixer (dump temperature 140-160°C). Subsequently, sulfur and an accelerator were mixed with the masterbatch on a two-roll mill at approx. 50-70°C. Rubber compounds were vulcanized by compression moulding at 150°C for a period of time equal to t 90 . After cooling the vulcanized rubber sheets for 24 h, test pieces were cut and their properties were determined.
  • Scorch time (t s 2) is the time to increase the torque 2 dNm above the minimum torque (M L ).
  • Optimum vulcanization time (t 90 ) is the time at 90% of the maximum torque (M H ).
  • T end is the time at the rheometer and is set at 1 h.
  • Delta torque (Delta S) is the difference between the minimum and the maximum torque.
  • the slope of a rheogram between M L and M H is a measure of the cure rate (RH).
  • Hysteresis is the percentage of energy lost per cycle of deformation.
  • the ratio of loss modulus to storage modulus is defined as mechanical loss and this corresponds to tangent delta (tan d).
  • HBU Heat build-up
  • the dynamic mechanical properties were determined using a Metravib R.D.S. viscoanalyzer (deformation type: tension-compression; temp.: 60°C; frequency: 15 Hz; dynamic strain: strain sweep of 0.01 % to 10% strain, i.e. 9 intervals on a logarithmic scale). From the data the Payne effect is calculated, the difference between the modulus at 0.01 % strain and at 10% strain. The lower the number, the better the carbon black rubber coupling.
  • Comparative Example B Pyro-S2 mixed at 50-70°C on mill Examples 1 and 2: Pyro-S2 mixed at 140-160°C in internal mixer
  • Pyro-S2 is 2,2'-dithiobis(pyridine N-oxide)
  • Pyr-S2 is 2,2'-dithiobispyridine
  • Example 5 ZPNO mixed at 140-160°C in internal mixer ZPNO is zinc 2-mercaptopyridine N-oxide
  • the carbon black coupling coagent was compounded into compositions comprising NR as shown in Tables 1 and 4.
  • the rheological properties of the rubber vulcanizates are shown in Tables 2 and 5, and the Payne effect is shown in Tables 3 and 6.
  • Table 1 Rubber compositions
  • the needle temperature (HBU measurements, cure at 150°C/2xt 90 ) of the vulcanizate prepared in the presence of a coagent in accordance with the present invention was significantly lower (i.e. 147.2°C and 144.9°C for Examples 1 and 2, respectively, and 141.8°C and 144.8°C for Examples 3 and 4, respectively) than that of the control (i.e. 168.7°C for Comparative Example A).
  • This effect was even more pronounced when the rubber composition was vulcanized at 180°C, i.e. needle temperatures of 149.8°C (Example 1 ') and 146.1°C (Example 2') were observed as compared to 186.3°C for the control.
  • the rubber vulcanizate obtained by the process of the present invention showed a lower hysteresis, which is an indication of a lower rolling resistance, as compared to the control.
  • Vayne effect is E at 0.01 % strain - E at 10% strain
  • the vulcanizate of Examples 1 and 2 showed a smaller difference between the modulus at low strain and at high strain (i.e. Payne effect) than the control A.
  • the conclusion is that coagent Pyro-S2 is acting as a coupling agent between carbon black and natural rubber.
  • Comparative Example B showed that when Pyro-S2 was added in the productive stage of mixing on the mill, the Payne effect increased relative to the control A.
  • the needle temperature (HBU measurements, cure at 150°C/2xt 90 ) of the vulcanizate prepared in the presence of a coagent in accordance with the present invention was significantly lower (i.e. 45.9°C for Example 5) than that of the control (i.e. 78.5°C for Comparative Example C).
  • the rubber vulcanizate obtained by the process of the present invention showed a lower hysteresis, which is an indication of a lower rolling resistance, as compared to the control.
  • the higher tensile modulus and reduced hysteresis are an indication of the chemical coupling of carbon black to natural rubber.
  • Example 5 The vulcanizate of Example 5 showed a smaller difference between the modulus at low strain and at high strain (i.e. Payne effect) than the control C. The conclusion is that ZPNO is acting as a coupling agent between carbon black and natural rubber.

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  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Compositions Of Macromolecular Compounds (AREA)

Abstract

L'invention concerne un procédé de vulcanisation souffrée comportant (a) une étape non-productive de mélange d'une composition de caoutchouc incluant un caoutchouc polyisoprène et du noir de charbon, (b) une étape productive de mélange d'une composition de caoutchouc incluant également du souffre et un accélérateur de vulcanisation, et (c) une étape de vulcanisation de ladite composition de caoutchouc, est caractérisée par le fait que l'étape non-productive de mélange est réalisée dans un mélangeur interne en présence de 0,1 à 5 phr d'agent de couplage de noir de charbon, selon l'une des formules (I)-(IV) dans laquelle R?1, R2, et R3¿ sont indépendamment H ou un groupe hydrocarbure C¿1?-C5, contenant éventuellement un ou plusieurs oxygène(s), nitrogène(s) ou atome(s) de souffre, R?1 et R2, si R1¿ est en position 4, ou R2 et R3 ensemble avec les atomes de carbone auxquels il sont reliés, peuvent former un cycle de 5 ou 6 éléments, ledit cycle étant éventuellement substitué par un groupe hydrocarbure C¿1?-C5, ledit groupe hydrocarbure contenant éventuellement un ou plusieurs oxygène(s), nitrogène(s) ou atome(s) de souffre, n vaut entre 1 et 4, M est sélectionné à partir de Na, Zn, Mg, AL, Fe, et Te, et x vaut 1, 1,5 ou 2. L'invention concerne également des articles en caoutchouc, comme des pneumatiques, comportant le caoutchouc vulcanisé obtenu par ledit procédé.
EP00962417A 1999-08-31 2000-08-29 Couplage de caoutchouc de noir de charbon par mercaptopyridines Withdrawn EP1198504A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP00962417A EP1198504A1 (fr) 1999-08-31 2000-08-29 Couplage de caoutchouc de noir de charbon par mercaptopyridines

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
EP99202823 1999-08-31
EP99202823 1999-08-31
EP00962417A EP1198504A1 (fr) 1999-08-31 2000-08-29 Couplage de caoutchouc de noir de charbon par mercaptopyridines
PCT/EP2000/008491 WO2001016227A1 (fr) 1999-08-31 2000-08-29 Couplage de caoutchouc de noir de charbon par mercaptopyridines

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EP1198504A1 true EP1198504A1 (fr) 2002-04-24

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EP (1) EP1198504A1 (fr)
AU (1) AU7415400A (fr)
CA (1) CA2373118A1 (fr)
WO (1) WO2001016227A1 (fr)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP7033374B2 (ja) * 2017-09-14 2022-03-10 住友化学株式会社 ゴム組成物
WO2020175344A1 (fr) * 2019-02-27 2020-09-03 住友化学株式会社 Composition de caoutchouc vulcanisé

Family Cites Families (2)

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Publication number Priority date Publication date Assignee Title
US4482663A (en) * 1982-07-12 1984-11-13 Phillips Petroleum Company Rubber compositions comprising a siliceous filler in combination with an organosulfur substituted pyridine promotor
JPH0468042A (ja) * 1990-07-10 1992-03-03 Bridgestone Corp ゴム組成物

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO0116227A1 *

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Publication number Publication date
CA2373118A1 (fr) 2001-03-08
WO2001016227A1 (fr) 2001-03-08
AU7415400A (en) 2001-03-26

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