IL43615A

Rubber mixtures containing reinforcing additives

Abstract

This record has no abstract on file.

IL43615A, drawing sheet 1 — Sheet 1 of 8

Term

No projected expiry on record.

5 claims: 1 independent, 4 dependent

1
Rubber mixtures comprising at least one rubber, a .crosslinking system, one or more silicate fillers, optionally in.combination with carbon black and, if desired, other conventional rubber auxiliaries and as reinforcing additive, one or more organosilanes of the general formula Z-Alk-S^-Alk-rZ (I). in which Z represents ן p where R is an alkyl (C^-C^) or phenyl radical and R is an alkoxy group with 1 to 8, preferably 1 to 4 carbon atoms, a cycloalkoxy group with 5 to 8 carbon atoms,' Aik :. ! represents a divalent, optionally unsaturated, linear or branched aliphatic, cycloaliphatic or aromatic hydrocarbon radical with 1 to 18 carbon atoms, more particularly with 1 to 6 end preferably with 2 or 3 carbon atoms, and .n is a number from 2 to 6, more particularly from 2 to 4, preferably from 3 to 4¢
2
Rubber mixtures according to Claim 1, wherein the organosilane or a mixture of organosilanes is applied to’the surface of the silicate filler particles.
3
Rubber mixtures according to Claim 1 substantially as described herein with reference to the Examples.
4
Additives for rubber mixtures according to Claims 1 or 2, comprising a mixture of at least one silicate filler and at least one organosil&ne of the formula I in Claim 1.
5
A process for the production of rubber mixtures according to Claim 1, wherein at least one organosilane of the formula I in Claim 1 is first mixed, uniformly with a silicate filler, or with a proportion thereof, and the resulting mixture is worked into and uniformly distributed in the rubber mixture or the other constituents of the rubber mixture, 6* A process according to Claim 5, wherein the organosilane(s) is/are first applied to the surface of the filler particles and the coated filler particles are added to, and uniformly distributed in, the rubber mixture or the other constituents of the rubber mixture.

Independent claims5

734 paragraphs in 13 sections, as filed

This invention relates to additives for rubber mixtures containing silicate fillers which have a favourable effect both upon production of the rubber mixtures and upon the . properties of the vulcanisates in a surprising and decisive ;.

manner. Chemically, these additives belong to the group of: organosilicon compounds containing sulphur in the molecule.; The additives provide the silicate fillers with improved reinforcing properties and increase the crosslinking yield during vulcanisation. They are referred to hereinafter as ' TO reinforcing additives.

It is known that carbon blacks in general and the specially developed types of carbon black in particular do not act merely as fillers in rubber vulcanisates, but instead ' act as a reinforcing filler (active filler) in a certain way.

The effect of the carbon black in reinforcing the polymer and determination of the rubber-filler interaction are described for example in the Journal Kautschuk und. Gummi, Kunststoffe (1966, No. 8, pages 470 - 474 and 1970, No. 1, pages 7 - 14);

Silicate fillers such as, for example, highly disperse j 20 silicas, silicates or the like are known to differ in their activity from carboriblacks. This difference is characterised by two factors. Firstly, the reinforcing effect of silicate fillers is different from that of carbon blacks on account of their totally different surface. Secondly, active silicas 25 influence the vulcanisation process, especially in cases where vulcanisation is effected by sulphur and accelerator additives. There has not yet been a sulphur vulcanisation process in which the silicate fillers do not reduce the crosslinking yield.

In recent years, attempts have been made to improve the activity of silicate fillers by adding chemical substances to the starting mixtures.

Thus, it is known that raercaptomethyl alkoxysilanes can be used as adhesion promoters between silicate materials such as glass, clay, asbestos or silicon dioxide and organic resins such as butadiene-styrene copolymers, natural rubber, polyester resins, polystyrene and styrene-maleic acid anhydride copolymers, the silanes being applied to the substrates and united with the resins in any way (DOS 2,038,715).

Compounds known as organosilicon siflphides with a sulphide sulphur atom between two hydrocarbon radicals are also known and have been recommended for use as adhesion promoters or even as intermediate products for compounds which can beused as water repellents or oxidation inhibitors. However, the aforementioned organosilicon compounds can also comprise sulphur-containing terminal groups such as the '׳ thiocyanato, xanthogenato, thioether, thionic acid ester group or the like (DOS 1,911,227).

Similar terminal groups are also present in organo- i organohydroxysilanes, for example 3-thiocyanatopropyl trimethoxy or triethoxysilane which, according to Belgian . ' Patent Specification 770,097, are eminently suitable for use in crosslinkable or vulcanisable mixtures of organic polymers, inorganic substances and corresponding crosslinking . or vulcanisation agents or systems. The silanes disclosed in

DOS 1,911,227 and Belgian Patent Specification 770,097 have, only one silicon atom attached to carbon or another silicon atom still attached thereto through an oxygen or amino nitrogen atom.

γ-Mercaptopropyltrimethoxy and triethoxysilanes, β-mercaptoethyltriethoxysilane and other sulphur-free silanes are also known. After they have been partially hydrolysed and applied to the surface of silica or silicate ־- .־ . 43615/2 . <

- 4 - . . .. ' filler particles, these silanes are intended to facilitate the processibility of rubber mixtures and to improve the ' strength properties of reinforced rubber articles (US

Patent Specification 3,350,345). 1 5 Tyre.treads-produced-from-a-rubber-mixture' containing...* a silica as filler and a silane as coupling agent are also know (Belgian Patent Specification 760,999). Although numerous silanes are represented by general formulae, γ-mercaptopropyltrimethoxysilane is the only proven coupling TO agent among those referred to in the preamble, the Tables and Examples.

The present invention relates to a class of organosilanes containing sulphur in the molecule which distinguish them'selves . in several respects, stand out from the'numerous known silanes 15 in their service properties and are particularly suitable for use as reinforcing additives, as will be described and demonstrated hereinafter. The new additives produce ' .׳ . unexpected, valuable and technically outstanding properties, in rubber mixtures and vulcanisates containing silicate fillers, the rubber mixtures containing at least one rubber, «׳ a crosslinking system, a sulphur-containing organosilane, | fillers and, preferably, other conventional rubber auxiliaries. The.-invention .is distinguished by the fact that the rubber j mixtures contain as reinforcing additive one or more organo25 Silanes corresponding to the general formula . '. ׳ . . i '־Tw. ' I Z - Aik - S - Aik - Z .':*־ ־ . י . . £ . י . י 7י.י ' '' . . / ' ' .' '</ i ׳ , . in which Z stands for the groups ' . .R

S T S רS' ׳>

- Si—- R - si—R and - Si—R , . k :X* T:

where R is an alkyl or phenyl radical and R is an alkoxy group with 1 to 8, preferably 1 to 4 carbon atoms, a cycloalkoxy g־oup . with 5 to 8 carbon atoms ׳ ' ;״? !׳

Aik represents a divalent, optionally unsaturated, linear or branched aliphatic, cycloaliphatic or aromatic hydrocarbon radical with 1 to 18 carbon atoms, more particularly with 1 to 6 and preferably with 2 or 3 carbon atoms, and n is a number from 2 to 6, more particularly'from 2 to 4, preferably from 3 to 4, and one or more silicate fillers,־ optionally in admixture with carbon black

The rubber mixtures preferably contain at least one organosilane, more particularly one or two, preferably one organosilane corresponding to general formula I above in which Z represents the group

1 ׳2 in which group R represents an alkoxy group with 1 to 8 i carbon, atoms, preferably with 1 to 4 carbon atoms,. and :( * .,.'. !

.I . ’f , ' ' . - Aik -'.

. r. ; ' . ' . ' :

represents a divalent linear, saturated hydrocarbon radical with_1 to 6, preferably 2 or 3, carbon atoms.

• . .

preferred reinforcingsdditives are those referred to earlier, more particularly those which correspond to the general :formulaי

in which‘

R2=-OCH ; .-OCH -CH ; -0C1I -CK-CH-; andJ • - צ '. CH, , . . י J

Alk=-CH2-CH2-; -CH2-CH-,- -CH2-CH2-CH2-;

-CH״-CH״-CH-; -CH.-CH -CH״-CH -ץ -CH -CH״-CH-CH and f (m £ I <-.־

CH,CH,

-ch2-ch2-ch2-?h-;

CH5 n - 2 to 4,

In addition,, those silanes can advantageously be used which, instead of the group (cf. also Z in general formula I) ,R2

-SiiilR2 contain the groups , /R /R /9/ 1

-Si—4r or -Si—-R \k2\r in which R^ represents alkyl (linear or branched) with 1 to 4 carbon atoms, phenyl or cyclohexyl.

Accordingly, the new selected silanes have two or more sulphur atoms and two separate as it were terminal silane groups in the middle of the substantially symmetrical molecule. It must be assumed that this molecular structure is responsible for the outstanding properties of the new vulcanisation reinforcing; agents.

In rubber mixtures containing silica as filler, the 3mereaptopropyltrimethoxysilane already mentioned above increases the stress values, tensile strength, abrasion resistance, shock elasticity and Shore hardness of the vulcanisates.

By contrast, the pre-cure times and Defo elasticity of the unvulcanised mixtures are adversely affected. The 5 pre-cure times are drastically shortened. In cases where mixtures of this kind are prepared in internal mixers, it is not uncommon for premature prevulcanisation to occur, making the mixtures impossible to further process.

The Defo elasticities are greatly increased which 10׳ .: increases the elastic rubber component of the crude mixture and complicates its further processing, for example by extrusion.

By contrast, rubber mixtures containing the new '. . reinforcing additives are distinguished’by significant ' 15 technical advantages- in regard to the properties of the crude mixtures and vulcanisates by comparison with those of the prior art. The crude mixtures now provide in particular for a hitherto unknown level of safety in processing, bring about a marked reduction in tightening 20 and only a slight increase in the Defo elasticities. All these advantageous properties and effects enable mixtures 1 of thiskind to be industrially used for the first time. The properties of the vulcanisates obtained are outstanding; and are comparable with or, as will be shown hereinafter, 25 even superior to the properties of corresponding carbonblack-filled vulcanisates. The aforementioned improvements in the properties of the crude mixtures and vulcanisates enable silicate fillers to be used for the first time in . fields of application hitherto reserved solely for carbon 30 black as reinforcing filler.

The term silicate filler is a generic term and relates to fillers which are compatible with rubbers or .can be worked into rubber mixtures and which consist of silicates, contain silicates and/or contain silicates in 35 . the broadest sense in chemically combined form, including ־ 6 mixtures of two or more silicate fillers. In particular, silicate fillers include;

highly disperse :silicas (silicon dioxide) with specific surfaces of from about 5 to 1000, preferably from 20 to

400 m /g (determined with gaseous nitrogen by the BET method) and with primary particle sizes of from about 10 to 400 nm, which can be produced for example by precipitation from solutions of silicates, by the hydrolytic and/or oxidative high-temperature reaction, also known as flame hydrolysis, of volatile silicon halides, or by an arc process. These silicas may optionally also be present in the form of mixed oxides or oxide mixtures with oxides of the metals ' aluminium, magnesium, calcium, barium, zinc, zirconium qnd or titanium; ’ .*,.!

synthetic silicates for example aluminium silicate or alkaline earth silicates such as magnesiumor calcium ' 2 silicate, with specific surfaces of from about 20 to 400 m /g and primary particle'sizes of about 10 to 400 nm;

.natural silicates, for example kaolins and asbestoses, also 20 natural silicas;

glass fibres and glass fibre products such as mats, rovings, woven cloths, nonwoven cloths and the like, also microglass beads.

The aforementioned silicate fillers can be used in quantities of from about 10 parts by weight or, optionally, even less, to about 250 parts by weight, based on 100 parts by weight of the rubber polymer.

Examples of filler mixtures include silica/kaolin or A silica/glass fibres/asbestos, also blends of the silicate30 containing reinforcing fillers.with carbon blacks of the kind commonly used in rubber, for example silica/lSAF carbon black or silica/glass fibre cord/HAF carbon black.

Typical examples of the silicate fillers suitable for use in accordance with the invention include the silicas and silicates manufactured and marketed by DEGUSSA under , —....tt(

- ' 1 the trade names AER0SI15R\ ULTRASIl/R\ SILTEG^,

DUROSIL^, EXTRUSI15R\ CALSI1/R\ etc.

In addition, various additives of the kind well known and widely used in the rubber industry can be added to the rubber mixtures.

Rather than adding the additive according to the invention as such to the rubber mixture, there are . considerable advantages in initially preparing a mixture of at least one silicate filler and at least one organo10 silane corresponding to general formula I above and incorporating and uniformly distributing this mixture in the rubber mixture or in the remaining constituents of the rubber mixture thereafter or even at some subsequent stage . i . ’ in the usual way and with conventional mixers*.

In the preparation of the master batch, a free-flowing, substantially dry product is formed even when an equivalent or even larger quantity by weight of liquid organosilane is added to the silicate filler. Accordingly, it is also possible to use only part of the total quantity of filler , .י י required, which as master batch already contains the total . quantity of silane required, for preparing the rubber mixture. ‘

Examples of! organosilanes corresponding to general formula I above include bis-[trialkoxysilyl alkyl-(1)]25 polysulphides such as bis-[2-trimethoxy-, -triethoxy-, -tri-(methylethoxy)-, -tripropoxy-, -tributoxy- etcv up to -trioctylhydroxysilyl ethyl]-polysulphides, more specifically the di-, tri-, tetra-, penta- and hexa-sulphides, also bis[3-trimethoxy-, -triethoxy-, -tri-(methylethoxy)-, -tripropoxy-, :

-tributoxy- etc. up to -trioctylhydroxypropyl]-polysulphides, more specifically the di-, tri-, tetra- etc. up to hexaSulphides, the corresponding bis-[3-trialkoxysilyl isobutyl]polysulphides, the corresponding bis-[4-trialkoxysilyl butyl]- , .־ polysulphides etc. up to the bis-[6-trialkoxysilyl hexyl]35 polysulphides. Among these selected, relatively simple

--8-organosilanes of getieral formula I, it is preferred to use the bis-[3-trimethoxy-, -triethoxy- and -tripropoxysilylpropyl]-polysulphides, more specifically the di-, tri- and tetra-sulphides. These and other organosilanes of general 5 formula I which can also be used to good effect can be obtained for example by the methods described in German Patents .. (Patent Applications P 2159.6 41 1־, P 21 41 160.9 and P. 22 12 239.9),.

The new silanes used in accordance with the invention 10 can be used in the rubber mixtures in quantities of from 0.1 to 50 parts by weight and preferably in quantities of from. 0.5 to 25 parts by weight, based on 100 parts by weight of rubber. '

For application, the described organosilanes can be 15 directly added to the rubber mixtures or to the constituents of these mixtures. There is no need, nor is it of advantage, to hydrolyse the organosilanes before they are used.

However, in order in particular to facilitate dosage and handling, the described organosilicon compounds can 20 also be added to part of the filler to be used so that the liquid organosilanes are converted into a powdered product and are used in this form. However, it is also possible, : although not specifically of advantage, uniformly to apply the organosilanes to the surface of the filler particles 25 and to use them in this form. The three or even only two of the described forms of application can also be combined.

The rubber mixtures can be prepared with one or. more optionally oil-extended natural and/or synthetic rubbers • such as, in particular, natural rubbers, synthetic rubbers, 30 preferably diene elastomers such as, for example, those of butadiene, of isoprene, of butadiene and styrene, of butadiene and acrylonitrile or of 2-chlorobutadiene, also butyl rubber and halogenated butyl rubber such as chlorinated or brominated butyl rubber, the other known diene rubbers 35 such as, for example, terpolymers of ethylene, propylene and,for example, undonjugated dienes, also trans-polypentenamer, carboxyl or epoxide rubbers and similar known elastomers. The chemical derivatives of natural rubber and modified natural rubbers may also be used for the purposes of the invention.

The rubber mixtures of the organic polymers, the crosslinking system, the silicate fillers and the organosilane additives may optionally have added to them known reaction accelerators and, optionally, one or more compounds from the group of antiagers, heat stabilisers, light סף stabilisers, ozone stabilisers, processing aids, plasticisers, tackifiers, expanding agents, dyes, pigments, waxes, extending . agents such as, for example, sawdust, organic acids such as, for example, stearic acid, benzoic acid or.salicylic acid, also lead oxide or zinc oxide, activators sucld as, for ’ [ ' example, triethanolamine, polyethylene glycol or hexane triol, all of which are well knowi in the rubber industry and in rubber technology. For vulcanisation, crosslinking י agents such as, in particular, peroxides, sulphur or, in special cases, magnesium oxide, and optionally vulcanisation ' accelerators or mixtures thereof are generally added to the rubber mixtures.

Production of the rubber mixtures, forming and vulcanisation are carried out by the methods commonly used in the rubber industry.

The following are examples of fields of industrial application for the described rubber mixtures: industrial ! rubber articles such as cable sheaths, hoses, drive belts, V-belts, conveyor belts, roll coatings, tyre treads for • motor vehicles, especially motor cars and lorries, also tyre carcases and side walls, heavy-duty tyres, soling materials for shoes,. sealing rings, damping elements and many others. The new rubber mixtures have also proved to be effective for glass fibre bonding mixtures and the like.

Some exemplary recipes for the new rubber mixtures with test results of vulcanisates and evaluations and . comparisons of these results are given in the following without limiting thd invention in any way. A number of different terms occur repeatedly in the following so that abbreviations can be used.

<td colspan="3"> List of abbreviations used</td>

<td> Abbreviation .</td><td> Designation in full</td><td> Measured in:</td>

<td> DH</td><td> Defo hardness</td><td> o</td>

<td> DE</td><td> Defo elasticity</td><td> -</td>

<td></td><td> Mooney scorch time</td><td> minutes</td>

<td> ½35</td><td> Mooney cure time</td><td> minutes</td>

<td> ML 4</td><td> Mooney plasticity</td><td></td>

<td></td><td> at 100°C, normal</td><td></td>

<td> ו</td><td> rotor, test time:</td><td></td>

<td></td><td> 4 minutes</td><td> -</td>

<td> SG</td><td> Specific gravity</td><td> g/ec ; '</td>

<td> V time</td><td> i Vulcanisation time</td><td> minuses</td>

<td> V temp</td><td> Vulcanisation</td><td></td>

<td></td><td> temperature</td><td> °C</td>

<td> TS</td><td> Tensile strength</td><td> kp/cra^</td>

<td> M 300</td><td> Stress value at</td><td></td>

<td></td><td> 300 % elongation</td><td> kp/cm</td>

<td> BE</td><td> Breaking elongation</td><td> % ' *</td>

<td> PE</td><td> Permanent elongation</td><td></td>

<td></td><td> after break</td><td> %</td>

<td> E</td><td> Shock elasticity</td><td> %</td>

<td> SH</td><td> Shore-A-har.dne s s,</td><td> -</td>

<td> TPR</td><td> Tear propagation</td><td></td>

<td></td><td> resistance</td><td> kp/cm</td>

<td> A</td><td> Abrasion (also</td><td> q</td>

<td></td><td> DIN-abrasion)</td><td> O mm</td>

<td> Δ T</td><td> Temperature increase</td><td></td>

<td></td><td colspan="2"> (cf. Goodrich Flexometer)°C</td>

<td> * Test Standards</td><td></td><td></td>

<td colspan="2"> The physical tests were carried out</td><td> at room temperature</td>

<td colspan="3"> . in accordance with the following Standards:</td>

<td> Tensile strength</td><td> , breaking elongation</td><td></td>

<td> and stress value</td><td> on 6 mm thick rings</td><td> DIN 53 504</td>

<td colspan="2"> .Tear propagation resistance</td><td> DIN 53 507</td>

<td> . !Shock elasticity</td><td></td><td> DIN 53 512</td>

<td> Shore-A-harduess</td><td> DIN 53 505</td>

<td> Specific gravity</td><td> DIN 53 550</td>

<td> Mooney test</td><td> ׳. 524 53 DIN</td>

<td> Goodrich Flexometer (determination of heat build-up ΔΤ)</td><td> ASTM D 623-62</td>

<td> Abrasion</td><td> DIN 53 516</td>

AH the vulcanisates were produced in a steam-heated stage press at the vulcanisation temperatures indicated.

Inthe Examples, the quantities of the mixture components are always given in parts by weight.

EXAMPLE 1 ' ' ' .

<td> Recipe:</td><td> Mixture 1</td><td colspan="2"> Mixture 2 Mixture 3</td>

<td> Natural rubber (ribbed smoked sheets I)</td><td> 100</td><td> 100</td><td> 100 ; '</td>

<td> Pentachlorothiophenyl zinc salt (Renacit IV, a product of Farbenfabriken BAYER, Leverkusen)</td><td> 0.25</td><td> 0.25</td><td> . 0.25</td>

<td colspan="2"> Finely divided precipitated silica (ULTRASIL VN 3, ProducL of DEGUSSA^r . 40 Zinc oxide Stearic acid 2</td><td> 40 3 2</td><td> 40 3 , . 2</td>

<td> .3-Mercaptopropyl- ' . trimethoxysilane</td><td> -</td><td> 2 , </td><td></td>

<td> bis-[3-trimethoxysilyl. propylj-trisulphide</td><td> -</td><td></td><td> 2</td>

<td> Dibenzothiazyldisulphide</td><td> 0.8</td><td> 0.8</td><td> 0.8</td>

<td> Diphenylguanidine</td><td> 2.25</td><td> 2.25 '</td><td> 2.25 i</td>

<td> Sulphur</td><td> 2.5</td><td> 2.5</td><td> 2.5</td>

<td> Mixing, procedure</td><td> -</td><td></td><td> • .</td>

<td> ;. ' Premixing in a kneader at</td><td colspan="3"> a throughflow temperature of 80°C.</td>

<td> Addition and handling</td><td></td><td> over</td><td> after</td>

<td> Natural rubber J</td><td></td><td> 0</td><td> minute</td>

<td colspan="2"> Half the quantity of silica, stearic acid</td><td> 1</td><td> minute</td>

<td colspan="2"> Half the quantity of silica, ׳ zinc oxide organosilane</td><td> 1.5</td><td> minutes .</td>

<td> • Cleaning, venting</td><td></td><td> 4</td><td> minutes</td>

<td> Discharge</td><td></td><td> 4.5</td><td> minutes</td>

This mixture was stored for 24 hours, after which the final mixture was prepared in a kneader at a throughflow temperature of 80°C (mixing time 1.5 minutes).

Properties of the unvulcanised mixtures

<td></td><td> fixture 1</td><td> Mixture 2</td><td> j Mixture 3</td>

<td> DH/DE</td><td> 675/20</td><td> prevulcanised</td><td> j 650/20 I</td>

<td> ML 4</td><td> 57</td><td> 232 (increases)</td><td>54</td>

Properties of the vulcanised mixtures

<td colspan="7"> Vulcanisation temperature: 150°C</td><td rowspan="2"> q SH</td><td rowspan="2"> TPR</td><td rowspan="2"> * A</td>

<td> Mixture</td><td> V. | cimej</td><td> TSi</td><td> M 300</td><td> BE .</td><td> PE</td><td> , E</td>

<td></td><td></td><td colspan="7"> could not be measured on account of premature prevulcanisation</td><td></td>

EXAMPLE 2

Recipe: Mixture 1 Mixture 2 Mixture 3 cis1,4־-polyisoprene rubber 100 . 100 100

Finely divided precipitated silica (ULTRASIL VN 3, a product of DEGUSSA) 50 50 . 50

־ 13 -

<td></td><td> Mixture .1</td><td> Mixture</td><td> 2 Mixture 3</td>

<td> Plasticiser (naphthenic hydrocarbon)</td><td> 3</td><td> 3</td><td> 3</td>

<td> Line oxide (active)</td><td> 2</td><td> 2</td><td> 2</td>

<td> Antiager (a mixture of aralkylated phenols)</td><td></td><td> 1</td><td> 1</td>

<td> mixture of equal parts of finely divided precipitated silica and hexane trio! (Aktivator^S), a product of DEGUSSA)</td><td> y</td><td> 4</td><td> 4</td>

<td> Benzoic acid</td><td> 0.8</td><td> 0.8</td><td> 0.8</td>

<td> 3-Mercaptopropyl- trimethoxysilane</td><td> -</td><td> 1.5</td><td> -</td>

<td> bis-[3-triethoxysilylpropyl]-tetrasulphide .</td><td> -</td><td> -</td><td> 1.5</td>

<td> Dibenzothiazyldisulphide</td><td> 0.8</td><td> 0.8 &</td><td> 0.8 ; ' ?</td>

<td> Diphenylguanidine</td><td> 1.6</td><td> 1 . 0</td><td> 1.6</td>

<td> Sulphur Mixing procedure</td><td> 2.5</td><td> 2.5</td><td> 2.5</td>

<td> Premixing in a kneader at</td><td colspan="2"> a throughflow temper.</td><td> ature of 80°C.</td>

<td> Addition and handling</td><td></td><td> ו over</td><td> after</td>

<td colspan="2"> cis 1,4-polyisoprene rubber</td><td> 0</td><td> minutes</td>

<td colspan="2"> Half the quantity of silica, stearic acid</td><td> ' 1</td><td> minute ί</td>

<td> Half the quantity of silica zinc oxide, organosilane</td><td colspan="2"> , plasticiser, 2.5</td><td> minutes</td>

<td> Cleaning, venting</td><td></td><td> 4</td><td> minutes</td>

<td> Discharge </td><td></td><td> 4.5</td><td> minutes</td>

After storage for 24 hours, the.mixture was completed in the kneader at a throughflow temperature of 80°C (mixing time 1.5 minutes).

Properties of the unvulcanised mixtures

<td> J .</td><td> Mixture 1</td><td> Mixture 2</td><td> Mixture 3</td>

<td> DH/DE</td><td> 1500/6.0</td><td> prevulcanised</td><td> 1375/7.0 . </td>

<td> ML 4</td><td> 100</td><td> 154 (increases)</td><td> 91 / </td>

Pro-parties of the vulcanised mixtures

Vulcanisation temperature: 134°C

<td> Mixture</td><td> V j time</td><td> TS</td><td> M 300 j</td><td> BE j i</td><td> BE ’ Ξ l i</td><td> sh;</td><td> TPR</td><td> i A ί</td>

<td></td><td></td><td colspan="2"> could not b</td><td colspan="4"> e measured on account of</td><td></td>

<td></td><td></td><td colspan="4"> premature prevulcanisation</td><td></td><td></td><td></td>

Rubber mixtures based on natural and synthetic cis-1,4polyisoprene containing a precipitated finely divided silica (DEGUSSA‘.s ULTRASIL VN' 3) as silicate filler, are used in Examples 1 and 2. Bis-[3-trimethoxysilyl propyl J-trisulphide 5 and bis-[3-triethoxysilyl propyl]-tetrasulphiae were used as reinforcing additives for the rubber mixtures, 3-mercaptopropyltrimethoxysilane (prior art) being used as comparison substance. As can be seen from the properties of the unvulcanised mixtures,.preparation of the mixture under . true practical conditions in an internal mixer only gives . further processible crude mixtures in the case of the rubber mixtures made up in accordance with the invention, whilst the comparison mixtures could not be further processed on account ofpremature prevulcanisation.

. In the mixtures, the polysulphide organosilanes shorten the pre-cure times and t.^ only slightly and do not have a negative effect upon the Mooney plasticities (ML 4) or upon the ratio DH/DE by comparison with the organosilane-free reference mixtures.

By comparison with the silane-free reference mixture, the vulcanisate properties of the new rubber mixtures are slightly improved in regard to tensile strength and distinctly improved in regard to the stress, values (moduli 300), so that

<td rowspan="2"> 5 .</td><td colspan="4"> the reinforcing effect obtained in accordance with the</td>

<td colspan="2"> invention, illustrated with figures,</td><td colspan="2"> is clearly in evidence.</td>

<td></td><td> The important advantages r</td><td> eferred to</td><td colspan="2"> are obtained by virtue</td>

<td></td><td> of the organosilanes used. In addition, mixture</td><td colspan="3"> 3 of Example 2 shows extremely high</td>

<td> 10,</td><td colspan="2"> tear-propagation resistance values. EXAMPLE 3 . Recipe: Mixture 1</td><td> Mixture 2</td><td> Mixture 3</td>

<td></td><td> Styrene-butadiene rubber (Buna Huis 1502)</td><td> 100 .</td><td> .) , 00׳ •</td><td> 100 / .-.</td>

<td></td><td> Aluminium silicate, • precipitated (DEGUSSA's SILTEG AS 7)</td><td> 40 .</td><td> 40</td><td> 40</td>

<td></td><td> Zinc oxide (active)</td><td> 3 ..</td><td> 3</td><td> 3 .</td>

<td></td><td> Stearic acid</td><td> .1</td><td> 1</td><td> 1</td>

<td></td><td> Coumarone resin (B 1/2 85°)</td><td> 5</td><td> 5</td><td> '5</td>

<td></td><td> Mixture of equal parts of finely divided precipitated silica , and hexane trial /,,-. (DEGUSSA’s Aktivator' ')</td><td> 5</td><td> 5 '</td><td> f 5' .</td>

<td></td><td> Antiager (mixture of aralkylated phenols)</td><td> 1</td><td> .1־</td><td> 1</td>

<td> ׳</td><td> 3-Mercaptopropyl trimethoxysi1ane</td><td> -</td><td> 1.5</td><td> -</td>

<td></td><td> bis3]־-triethoxysilyl propyl]-tetrasulphide</td><td> -</td><td> .יי</td><td> 1.5 .'</td>

<td></td><td> Benzothiazyl-2-cyclohexyl sulphenamide</td><td> 0.4 .</td><td> 0.4.</td><td> 0.4 ,:</td>

<td></td><td> Diphenylguanidine</td><td> 0.8</td><td> 0.8</td><td> 0.8 .,:</td>

<td></td><td> Sulphur</td><td> 2.0</td><td> 2.0</td><td> 2.0</td>

Mixing procedure

Premixing in a kneader at a throughflow temperature of 80°C.

<td> Addition and handling</td><td> over</td><td> after</td>

<td> Polymer (SBR)</td><td> 0</td><td> minutes .</td>

<td> Half the quantity of aluminium silicate, stearic acid, antiager</td><td> 1</td><td> minute</td>

<td> Half the quantity of aluminium silicate, plasticiser, zinc oxide, organosilane, other chemicals</td><td> 2.5</td><td> minutes</td>

<td> Cleaning, venting</td><td> 4</td><td> minutes</td>

<td> Discharge</td><td> 4.5</td><td> minutes</td>

<td> The accelerator and sulphur are</td><td> mixed in</td><td> on a mixin;</td>

roll (mixing time 1.5 minutes).

Properties of the unvulcanised mixtures

<td></td><td> Mixture 1</td><td> Mixture 2</td><td> Mixture 3</td>

<td> ML 4</td><td> 78</td><td> 196 (increases)</td><td> 82</td>

Properties of the vulcanised mixtures

Vulcanisation temperature: 150°C

<td> Mixture</td><td> v I time</td><td> TS</td><td colspan="2"> M 300</td><td> BE</td><td> . PE</td><td> E</td><td> SH</td><td> TPR</td><td> A</td>

<td></td><td></td><td colspan="2"> could not premature</td><td colspan="6"> be measured on account of prevulcanisation</td><td></td>

EXAMPLE 4

<td> Recipe:</td><td> Mixture 1</td><td> Mixture</td><td> 2 , Mixture 3</td>

<td> Styrene-butadiene rubber . . ,<1502 . . :.־ן/:) \ Xi</td><td> 100</td><td> 100 .</td><td> 100</td>

<td colspan="2"> rmeiy .aividea precipitated silica (DEGUSSA^’s ULTRASIL VN 3) 50 '</td><td> 50</td><td>50 ;.</td>

<td> Zinc oxide (active)</td><td> 1</td><td> . 1</td><td> '1</td>

<td> Stearic acid</td><td> 2</td><td> 2</td><td> 2</td>

<td> Antiager (mixture of aralkylated phenols)</td><td> '1</td><td> 1'</td><td> 1</td>

<td> Polyethylene glycol (PEG 4000)</td><td> 2</td><td> 2</td><td> 2</td>

<td> 3-Mercaptopropyl trimethoxysilane</td><td> -</td><td> 2 $</td><td> ' i.</td>

<td> bis-[3-trimethoxysilyl propyl]-disulphide</td><td> - </td><td></td><td> 2</td>

<td> Dibenzothiazyldisulphide</td><td> z</td><td> 1</td><td> 1</td>

<td> Diphenylguanidine</td><td> 2</td><td> 2</td><td> 2</td>

<td> Sulphur Mixing procedure:</td><td> 2</td><td> 2</td><td> 2</td>

<td> Premixing in a kneader at</td><td colspan="3"> a throughflow temperature of 80°C.</td>

<td> Addition and handling</td><td></td><td> over</td><td> after</td>

<td> Polymer (SBR)</td><td></td><td> 0</td><td> minutes</td>

<td colspan="2"> Half the quantity of silica,' stearic acid, antiager</td><td> 1</td><td> minute</td>

<td colspan="2"> Half the quantity of silica, zinc oxide, organosilane, other chemicals</td><td> 2.5</td><td> minutes .</td>

<td> Cleaning, venting</td><td></td><td> 4</td><td> minutes</td>

<td> Discharge</td><td></td><td> 4.5 .</td><td> minutes.</td>

<td colspan="2"> After storage for 24 hours, the</td><td> mixture i</td><td> s completed.</td>

in a kneader at(a throughflow temperature of SO°C (mixing time 1.5׳ minutes).

<td> Property</td><td> .es of</td><td colspan="3"> the urivulcanised mixtur</td><td> es</td><td></td><td></td>

<td colspan="4"></td><td> Mixture 1</td><td colspan="2"> Mixture 2</td><td> Mixture 3</td>

<td> OH/DE</td><td></td><td></td><td></td><td> 2250/19.5</td><td colspan="2"> prevulcanised</td><td> 2050/31.0</td>

<td> -35 ML 4</td><td></td><td></td><td></td><td> 8.1 10.0 143</td><td colspan="2"> 242 (increases) i</td><td> 7.8 9.6 116 . I</td>

<td colspan="2"> Properties of</td><td colspan="3"> the vulcanised mixtures</td><td></td><td></td><td></td>

<td colspan="2"> Vulcanisation</td><td colspan="2"> temperature:</td><td> 150°C .</td><td></td><td></td><td></td>

<td> Mixture .</td><td> V ! time</td><td> TS j i</td><td> M 300</td><td> BE; PE ;</td><td> Ξ ן SH</td><td> TPR</td><td> A</td>

<td></td><td> L</td><td colspan="5"> could not be measured on account of premature prevulcanisation</td><td></td>

<td> EXAMPLE</td><td> _5</td><td></td><td></td><td></td><td></td><td></td><td></td>

<td> Recipe;</td><td></td><td></td><td></td><td> Mixture 1</td><td colspan="2"> Mixture 2</td><td> Mixture 3</td>

<td colspan="4"> Styrene-butadiene rubber ־ (Luna Huis 1500)</td><td> 100</td><td> 100</td><td></td><td> 100</td>

<td colspan="3"> Colloidal kaolin</td><td></td><td> 75</td><td> 75</td><td></td><td>75</td>

<td colspan="2"> Zinc oxide</td><td></td><td></td><td> 4 </td><td> 4</td><td> i</td><td> 4</td>

<td> Stearic</td><td> acid</td><td></td><td></td><td> 2</td><td> 2</td><td></td><td> 2</td>

<td colspan="3"> 3-Mercaptopropyl trimethoxysilane</td><td></td><td> -</td><td> 2.5.</td><td></td><td> -</td>

<td colspan="4"> bis-[3-triethoxysilyl propyl]-tetrasulphide</td><td> -</td><td> «Β</td><td></td><td> 2.5 </td>

<td colspan="4"> Dibenzothiazy!disulphide Diphenylguanidine</td><td> 1.2 1.2</td><td> 1.2 1.2</td><td></td><td> י.. .1.2 1.2</td>

<td colspan="4"> Mixing procedure Premixing in a kneader at Addition and handling</td><td colspan="5"> ס. a throughflow temperature of 80°C. over after__________ ,</td>

<td colspan="4"> Rubber Half the quantity of kaoli oxide, organosilane Cleaning,, venting Discharge After storage for 24 in a kneader at a through! time 1.5 minutes). Properties of the unvulcar</td><td> n, zin hours, low te lisedjr</td><td colspan="4"> 0 minutes c 2.5 minutes 4 minutes 4.5 minutes the mixture was completed mperaturepf 80°C (mixing lixtures ־ .</td>

<td colspan="4"></td><td> Mixtv</td><td> ire 1</td><td colspan="3"> Mixture 2 ן Mixture 3</td>

<td colspan="4"> DH/DE ' 5־ -35 ML 4 . SG Properties of the vulcanis</td><td colspan="2"> 1750/27 34.0 41.3 63 1.32 ' ed mixtures</td><td colspan="3"> 2550/32.5 1450/23.-5 6.6 ' 29.2 ; 11.6 . 38.2 8.0 61 1.32 I. 1.32</td>

<td colspan="6"> Vulcanisation temperature: 150°C</td><td colspan="3"></td>

<td rowspan="2"> Mixture</td><td rowspan="2"> V time</td><td colspan="2" rowspan="2"> IS! M 300</td><td rowspan="2"> BE ' </td><td colspan="3"> PE ן E! SH ! TPR</td><td rowspan="2"> A</td>

Rubber mixtures based on styrene-butadiene copolymers containing synthetic aluminium silicate, precipitated silica and a natural silicate (colloidal kaolin), respectively, as silicate fillers were used in Examples 3 to 5. Bis-[,3-triethoxy5 silyl propyl]-tetrasulphide and bis-[3-trimethoxysilyl propyljdisulphide were used as organosilane reinforcing additives; they were compared with 3-mercaptopropyl triraethoxysilane (priorjart) in otherwise identical mixtures.

According to Examples 3 and 4, it is not possible to 10 prepare kneader mixtures with 3-mercaptopropyl trimethoxysilane in the absence of premature prevalcanisation under true practical conditions, whereas this is readily possible in the case of the rubber mixtures containing the polysulphide organosilanes.

The vulcanisate properties of the ‘new rubber mixtures 15 are distinctly improved by comparison with the particular silane-free reference, mixture: tensile strength and stress value are increased, permanent elongation after break is reduced and DIN-abrasion improved.

Example 5 shows that these effects also occur in cases 20 where such a relatively inactive silicate filler as colloidal <׳ kaolin is used. ; c

Example5 demonstrates the distinct advance of the invention over the prior art, even in regard' to the properties of the unvulcanised mixtures: as a mixture component, 325 mercaptopropyl trimethoxysilane increases the ,values for DH/DE and ML 4, and drastically shortens the precure time

With the new rubber mixtures, however, the values DH/DE and ML 4 are modified in a positive sense whilst the precure time t^ is not appreciably different from that of the i 30 comparison mixture.

Examples 6 to 9 below show that the new rubber mixtures can also be prepared with equally good effect on the basis of butadiene-acrylonitrile copolymers, butyl rubber, polychloroprene rubber or ethylene-propylene terpolymers.

EXAMPLE 6'

<td> Recipe:</td><td> Mixtu</td><td> 2 Mixture ׳ 1 re.</td>

<td> Butadiene-aery1onitrile rubber (Perbunan N 3310, aproduct of Farbenfabriken Bayer AG).</td><td> 100</td><td> 100</td>

<td> Pyrogenic silica (DEGUSSA's' Aerosil 130 V)</td><td> ' 40</td><td> 40 .</td>

<td> Zinc oxide</td><td> 4</td><td> . 4</td>

<td> bis-[3-triethoxysilyl propyl]tetrasulphide</td><td> -</td><td> 1.5</td>

<td> Dibenzothiazyldisulphide </td><td> 1.5</td><td> 1.5</td>

<td> Diphenylguanidine</td><td> 1.5</td><td> . 1.5</td>

<td> Sulphur</td><td> 2.75</td><td> 2.75</td>

<td> Mixing Procedure</td><td></td><td> ',</td>

<td colspan="2"> Premixing in a kneader at a throughflow temper</td><td> :ature of 80°.C.\</td>

<td> Addition and handling</td><td> over</td><td> after</td>

<td> Butadiene-acrylonitrile rubber</td><td> 0.</td><td> minutes</td>

<td> Half the quantity of silica, stearic acid</td><td> '1</td><td> minute</td>

<td> Half the quantity of silica, zinc oxide, organosilane</td><td> 2.5</td><td> minutes</td>

<td> Cleaning, venting</td><td> 4</td><td> minutes</td>

<td> Discharge</td><td> 4.5</td><td> minutes</td>

After storage for 24 hours, the mixture was completed in a kneader.at a throughflow temperature of 80°C (mixing time 1.5 minutes).

<td colspan="3"> Properties of the unvulcanised mixtures:</td>

<td></td><td> Mixture 1</td><td> Mixture. 2</td>

<td> Properties of t</td><td> he vulc</td><td> .anised</td><td> mixtur</td><td> .es</td><td></td><td></td><td></td><td></td>

<td> Vulcanisation t</td><td> emperat</td><td></td><td> 150°C</td><td></td><td></td><td></td><td></td><td></td>

<td> Mixture V time</td><td> TS</td><td> M 200</td><td> BE</td><td> PE</td><td></td><td> SH</td><td> TPR</td><td> A</td>

<td rowspan="2"> EXAMPLE Recipe;</td><td rowspan="2"> ׳ Mixta</td><td> »</td>

<td> re 1 Mixture 2</td>

<td> Butyl rubber</td><td> 100</td><td> . 100</td>

<td> Finely divided precipitated silica (DEGUSSA's ULTRASIL VN 3)</td><td> 50</td><td> 50 . , .</td>

<td> Zinc oxide</td><td> 5 ,.</td><td> .5;</td>

<td> Stearic acid</td><td> 1</td><td> 1 </td>

<td> Plasticiser (petroleum oil)</td><td> 5</td><td> ,, 5 1</td>

<td> bis-[3-triethoxysilyl propyl]tetrasulphide</td><td> -</td><td> 1,5</td>

<td> 2-Mercaptobenzothiazole</td><td> . 1</td><td> 1</td>

<td> Tetramethylthiuramdisulphide</td><td> 0.5</td><td> . 0.5 </td>

<td> Sulphur</td><td> 1.5</td><td> 1.5</td>

<td colspan="3"> Mixing procedure Premixing in a kneader at a throughflow temperature of 60°C:</td>

<td> Addition and handling</td><td> over</td><td> after</td>

<td> Butyl rubber</td><td> 0 .</td><td> minute</td>

<td> Half the quantity of silica, stearic acid</td><td> 2</td><td> minutes</td>

<td> Half the quantity of s.ilica, zinc oxide, organosilane, plasticiser</td><td> 4</td><td> minutes</td>

<td> Cleaning, venting</td><td> , 6</td><td> minutes .</td>

<td> Discharge</td><td> 7 .</td><td> minutes</td>

<td> The mixture was completed on mixing</td><td> rolls at a</td><td> roll</td>

temperature of 50°C.

Addition and handling over after

Introduce batch ; 0 minutes

Cut in twice right and left ' 1 ׳ ‘ minute

Accelerator and sulphur 2 minutes

Cut in twice right and left 4 minutes

Draw out mixture sheet 5 minutes

Properties of the unvulcanised mixtures

I Mixture 1 1 Mixture 2 i_______________________________________________________________________i___________________________________________________________________

SG : 1.15 . I 1.15 '' t

Properties of the vulcanised mixtures

Vulcanisation temperature: 160°C

<td> Mixture ί I</td><td> V I time!</td><td> TS</td><td> M 300 ;</td><td> BE</td><td> PE |</td><td> E |</td><td> SH</td><td> TPR</td><td> ' -A</td>

EXAMPLE 8

<td> Recipe;</td><td> Mixture1 ׳</td><td> Mixture 2</td>

<td> Polychlorobutadiene rubber (Baypren 210, a product of Farbenfabriken Bayer AG,. Leverkusen).</td><td> 100</td><td> 100</td>

<td> Di-£-tolylguanidine</td><td> ׳ 0.5</td><td> 0.5</td>

<td> Magnesium oxide</td><td> 4</td><td> 4</td>

<td> Stearic acid</td><td> 1</td><td> 1</td>

Mixture 1 Mixture 2

Mixture of liquid and soft paraffins (Vaseline)

Pheny1-β-naphthylamine (antiager) 2 ! Finely divided precipitated ' silica (DSGUSSA’s ״״ | .1• ״ -,/ ULTRASIL VN 2&|> , 50 , , , , , ״ . '

Wt«j» . ?fn«.,)

Γ׳ . ' (naphthenic hydrocarbons). 10׳ bis-[3-triethoxysilyl propyl]-tetrasulphide

2-Mercaptoimidazoline0.75

Zinc oxide5

Mixing procedure. '

Premixing in a kneader at a throughflow'tempeshture of 60°C.'

Addition and handling over after

Polychlorobutadiene, guanidine derivative 0 minutes

Antiager, magnesiumoxide, stearic ) acid, Vaseline, one third the quantity ) 1 minute of silica )

One third the quantity of silica, half the quantity of the plasticiser, . 1 organosilane 2.5 minutes

One third the quantity of silica, half the quantity of plasticiser

Gleaning, venting 4 minutes

Discharge and cooling for 5 minutes in a water bath 5 minutes

After storage for 24 hours, the 2-mercaptoimidazoline ׳, and zinc oxide were added tothemixture in the kneader at ן a throughflow temperature of 60°C, followed by cooling for 5 minutes in a water bath.

Properties of the ur.vulcanised mixtures

<td></td><td> Mixture 1</td><td> Mixture 2</td>

Properties of the vulcanised mixtures

Vulcanisation temperature: 150°C

<td></td><td> Mixture ( i</td><td> V i TS time׳ :</td><td> M 300! BE ' PE</td><td> j E 1 SH! TPR ;</td><td> A</td>

<td></td><td> EXAMPLE</td><td> _9</td><td></td><td></td><td> י-</td>

<td></td><td> Recipe:</td><td></td><td> Mixture</td><td> 1 Mixture 2</td><td> ו</td>

<td></td><td colspan="3"> Terpolymeric ethylenepropylene rubber.׳ (Keltan 70, a product of! the . Dutch State Mines) 100</td><td> 100</td><td></td>

<td></td><td colspan="2"> Finely divided pre silica (DEGUSSA’s</td><td> cipitated EXTRUSIL)100</td><td> 100</td><td></td>

<td></td><td colspan="3"> Naphthenic hydrocarbon as plasticiser 50</td><td> 50</td><td></td>

<td></td><td colspan="2"> Titanium dioxide</td><td> 10</td><td> 10</td><td></td>

<td></td><td colspan="2"> Zinc.oxide</td><td> 5</td><td> 5</td><td></td>

<td></td><td> Stearic</td><td> acid</td><td> 1</td><td> '1</td><td></td>

<td></td><td colspan="3"> bis-[3-triethoxysilyl propyl]-tetrasulphide</td><td> ' 5</td><td></td>

<td> ו</td><td colspan="3"> Tetramethylthiuram disulphide' 0.8</td><td> 0.8,</td><td></td>

<td></td><td colspan="3"> D irae t hyl dipheny 1 thiuram, disulphide 1-5</td><td> 1.5</td><td> !</td>

<td></td><td colspan="2"> Tellurium diethyl dithiocarbamate</td><td> 0.8</td><td> 0.8</td><td></td>

<td></td><td colspan="3"> Dipentamethylene thiuram tetrasulphide 0.8</td><td> 0.8</td><td></td>

<td></td><td colspan="2"> Sulphur</td><td> 2.0</td><td> 2.0</td><td></td>

<td></td><td> Mixing</td><td> procedure</td><td></td><td></td><td></td>

<td></td><td colspan="5"> Premixing in a kneader at a throughflow temperature of 80eC.</td>

<td> Addition and handling</td><td> Over after</td>

<td> Ethylene-propylene terpolymer</td><td> 0 minutes</td>

<td> Half the quantity of silica,</td><td></td>

<td> stearic acid</td><td> 1 minute</td>

<td> Half the quantity of silica, zinc</td><td></td>

<td> oxide, organosilane, other chemicals .</td><td> 2.5 minutes</td>

<td> Cleaning, venting</td><td> 4 minutes</td>

<td> Discharge</td><td> 5 minutes</td>

After storage for 24 hours, .the mixture was completed in the kneader at a throughflow temperature of 80°C (mixing time 1.5 minutes).

Properties of the unvulcanised mixtures

<td></td><td> Mixture 1</td><td> Mixture 2</td>

<td colspan="9"> Properties of the vulcanised mixtures</td>

<td colspan="2"> Vulcanisation</td><td colspan="2"> temperature:</td><td> 160°C</td><td></td><td></td><td></td><td></td>

<td> Mixture </td><td colspan="2"> ׳V j TS time: ></td><td> ־ M 300' i</td><td> i βξ ׳; t</td><td> PE !</td><td> £ 5</td><td> SH</td><td> TPR</td>

A rubber mixture made up in accordance with the invention on the basis of a nitrile rubber containing a pure silica (DEGUSSA's AEROSIL 130 V) produced by flame hydrolysis as silicate filler, and bis-[3-triethoxysilyl propylj-tetrasulphide as organosilane reinforcing additive, was used in Example 6.

By comparison with ths organosilane-free reference mixture, the Mooney-viscosity of mixture 2 of Example 6 is distinctly reduced, which implies a lower energy requirement and, hence, reduced costs for further processing the crude mixture״ The pre-cure time t$ is only negligibly shortened. The vulcanisates of mixture 2 , are distinguished by significant improvements in regard to tensile strength, stress value and DIN-abrasion by comparison with the organosilane-free reference mixture 1.

According to Example 7, a rubber mixture made up in accordance, with the invention on the basis of butyl rubber contains a precipitated silica (DEGUSSA's ULTRASIL VN 3) as silicate filler’and bis-[3-triethoxysilyl propyl ]-tetra- \ י sulphide as organosilane reinforcing additive.( ׳, '

Addition of the organosilane to the basically already greatly accelerated reference mixture does not result in premature prevulcanisation, but surprisingly in an extension of the pre-cure time £,. Tensile strengths, stress values and permanent elongations of the vulcanisates are distinctly 20 improved by comparison with the vulcanisate obtained from the reference mixture.

Example 8 describes a rubber mixture based on a polychloroprene rubber containing a precipitated silica : (DEGUSSA's ULTRASIL VN 3) as silicate filler and, once 25 again, bis-[3-triethoxysilyl propyl]-tetrasulphide as organosilane reinforcing additive. The scorch time of mixture 2 is substantially the same as that of the reference mixture, whilst its Mooney viscosity is slightly : , more favourable. The properties of the vulcanisates 30 obtained from the rubber mixture made up in accordance with the invention'are distinctly improved by comparison with the reference mixture; the tensile strength is higher 2 by more than 40 kp/cm and the stress value (300 %) greater 2 in some cases by more than 60 kp/cm . This represents an 35 improvement of 100 % and more, based on reference mixture 1.

Example 9 relates to a rubber mixture based on an ethylene-propyler.e terpolymer with another precipitated: silica (DEGUSSA's EXTRUSIL) as silicate filler and bis[3-triethoxysilyl propyl]-tetrasulphide as organosilane. Once again, the pre-cure time t^ is surprisingly lengthened; ML 4 is reduced by 10 Mooney units, both by comparison with the organosilane-free reference mixture. The proparties of the vulcanisates, obtained from mixture 2 made up in accordance with 'the invention are distinctly superior to those of reference mixture 1 in regard to tensile strength, stress value and permanent elongation after break.

<td> EXAMPLE 10 :</td><td></td><td></td>

<td colspan="2"> Mixture for the tyre tread of a motor car</td><td></td>

<td> Recipe: '</td><td> ' Mixture 1</td><td> Mixture 1</td>

<td> Oil-extended styrene-butadiene rubber (Buna Huis 1712)</td><td> 96.5</td><td> 96.5</td>

<td> cis-1,4-polybutadiene (Buna CB 10)</td><td> 30</td><td> 30</td>

<td> Finely divided precipitated silica (DEGUSSA's ULTRASIL VK 3)</td><td> 75</td><td> 70</td>

<td> bis-[3-triethoxysilyl propyl]tetrasulphide</td><td> 5</td><td> י-</td>

<td> Mixture of equal parts of precipitated silica (ULTRASIL VN 3) and bis-[3triethoxysilyl propyl]-tetrasulphide</td><td> -</td><td> 10 '</td>

<td> Zinc oxide</td><td> 4</td><td> 4</td>

<td> Stearic acid</td><td> 1.2</td><td> 1.2 .'.</td>

<td> Plasticiser (naphthenic hydrocarbon)</td><td> י 15</td><td> 15</td>

<td> Antiager phenyl-β-naphthylamine</td><td> 1.5</td><td> 1.5 '</td>

<td> Antiager N-i s opropy 1-Ν'-pheny l-jophenylene diamine</td><td> . 1-5</td><td> 1.5 .</td>

<td> • Benzthiazolyl-2-cyclohexylsulphenamide</td><td> .1.2</td><td> 1.2 !</td>

<td> Diphenylguanidine</td><td> 3:5</td><td> 3.5</td>

<td> Sulphur Mixing procedure: Up-side-down</td><td> 1.6</td><td> T.6</td>

<td> Premixing in a kneader at a throughflow</td><td> temperature</td><td> of 80°C.</td>

<td colspan="2"> Addition and handling</td><td> over</td><td> after</td>

<td> First stage: Fillers, .chemicals, polyme</td><td> T</td><td> 0</td><td> minutes</td>

<td> Cleaning</td><td> .</td><td> 3</td><td> minutes</td>

<td> Discharge</td><td></td><td> 3.5</td><td> minutes'</td>

<td> Storage</td><td></td><td> 24</td><td> hours</td>

<td colspan="2"> Second stage: Mixing completed in a kneader at a throughflow temperature of 80°C Accelerator and sulphur are added in the kneader Mixing time</td><td> 1.5</td><td> minutes</td>

<td colspan="3"> Properties of the unvulcanised mixtures:</td><td></td>

<td></td><td> Mixture 1</td><td> Mixture</td><td> 2 </td>

<td colspan="4"> Properties of the vulcanised mixtures</td><td rowspan="2"> E i</td><td rowspan="2"> SH</td><td rowspan="2">TPS i I</td><td rowspan="2"> A</td>

<td> Vulcanisation Mixture I V | time</td><td> temperature: j TS ; M 300 i I 1 ! Ϊ I i ־</td><td> Q Ο M vO PQ</td><td> ΡΞ</td>

EXAMPLE 11

Mixture for the tyre tread of an earth mover

Recipe Mixture 1 Mixture 2

Natural rubber (Ribbed smoked sheets 1) 100 100

1. . ׳

Pentachlorothiophenyl zinc salt (Renacit IV, a product of Farbenfabriken

Bayer, Leverkusen) 0.25 0.25 ׳ carbon black ISAF-LM (DEGUSSA's

C0RAX 6 LM) ' 60. Mixture of 10 parts of bis-[3-triethoxysilyl propyl]-tetrasulphide and 100 . parts of precipitated silica (DEGUSSA’s

ULTRASIL VN 3) -66

Zinc oxide 55 .x

Stearic acid 2.52.5

Mixture 1. Mixture 2

<td> ?.nt iager pheny 1 - a- naphthyl amine</td><td> 1</td><td> 1</td>

<td> Antlager phenyl-p-naphthylamine</td><td> 1</td><td> 1</td>

<td> ?.ntiager N-isopropyl-N-phenyl-ophenylene diamine</td><td> 0.8</td><td> 0.8</td>

<td> Rubber ococerite (Protektor 3888־ a product of Luneburger Wachsbleiche GmbH) j</td><td> 0.8</td><td> 0.8.</td>

<td> Plasticiser (naphthenic hydrocarbon)</td><td> 2</td><td> י 2 ' .</td>

<td> bis-L2-ethylamino-4-dlethylamino6-triazinyl]-disulphide</td><td> 0.6</td><td> , 0.6</td>

<td> Diphenylguanidine</td><td> -</td><td> 2</td>

<td> Sulphur Mixing procedure: ’,Up-side-down</td><td> 1.2</td><td> 1.2</td>

<td colspan="3"> 1 !*remixing in a kneader at a throughflow׳ temperature of 80?C.</td>

<td> Addition and handling</td><td> « over</td><td> יי . after .</td>

<td> First stage:</td><td></td><td> *</td>

<td> Filler, chemicals, polymer</td><td> 0</td><td> minutes</td>

<td> Cleaning</td><td> 3</td><td> minutes.</td>

<td> Discharge</td><td> 3.5</td><td> minutes</td>

<td> Storage time Second stage:</td><td> 24</td><td> hours</td>

<td> Mixture completed in the kneader at a throughflow temperature of 80°C ׳</td><td></td><td></td>

<td> Accelerator and sulphur are added in the kneader.</td><td></td><td></td>

<td> Mixing time</td><td> 1.5</td><td> minutes .</td>

Properties of the unvulcanised mixtures

Mooney scorch t^ 25.4 19.9

Mooney cure t^ 28.1 . 25.3

Mooney viscosity ML 4 . 88 77

<td colspan="2"> Specific gravity Properties of the</td><td> 1.15 vulcanised mixtures</td><td colspan="3"> 1.18</td>

<td colspan="3"> Vulcanisation temperature: 145°C</td><td></td><td></td><td></td>

<td> Mixture</td><td> V I TS time!</td><td> pi 300> BE I Ξ ן I * i i</td><td> SH</td><td> ! TPR I A ί ! .</td><td> T(0.250)</td>

A recipe for the tyre tread of a motor car is disclosed and used in Example '10, whilst a recipe for the tyre tread of an earth mover is disclosed and used in Example 11. Bis[3-triethoxysilyl propyl]-tetrasulphide is used as reinforcing additive in both recipes, also in the form of a mixture with a silica in a ratio of 1 : 1 for the motor car tread and in the form of a mixture with finely divided silica in a ratio of 1 : 10 for the earth mover tread.

Example 10 shows that, within the limits of error of . the test methods used, there is no difference between using the reinforcing additive in pure form and using it in the form of a mixture with precipitated highly disperse silica.

The properties of the unvulcanised and of the vulcanise'd mixtures show the expert that, by u^ing’the ra'inforcing ' additives according to the invention, it is possible to provide the silica-reinforced car tread mixtures with properties which correspond largely to the properties of corresponding carbon black mixtures.

Accordingly, it is possible for the first time by using the polysulphide-functional organosilane reinforcing additives, without modifying the mixing and vulcanisation processes commonly used in the rubber industry, to produce silicareinforced car tread mixtures which are at least equivalent in all their service properties to corresponding carbon25 black-reinforced mixtures.

In Example 11, the reinforcing additives according to . the invention are compared in a silica-reinforced earthmover tread mixture with a conventional carbon-black• reinforced earth mover tread mixture.

It is clear from Example . 11 that the additives according to the invention provide the silica-reinforced rubber mixtures in essential aspects with properties that are superior to those of carbon-black-reinforced mixtures, for example in regard to tear propagation resistance and heat build-up (Goodrich-Flexometer . test).

EXAMPLE 12

Natural rubber mixtures (ribbed, smoked sheets I with a Defo hardness of 1000 measured after kneading with 0.25 parts by weight of zinc pentachlorothiophenate) with three silanes according to the invention and silica as a filler (mixtures 3, 4, 5) were compared with identical mixtures not containing such silanes (mixture containing a known mercaptosilane (mixture 2)

Recipe Comparison

Mixture No. 12 3

1) or

According to the invention

Natural rubber (ribbed

<td> smoked sheets I)</td><td> 100</td><td> 100</td><td> 100</td><td> 100</td><td> 100</td>

<td> Finely divided precipitated silica (ULTRASIL VN 3, a product of DEGUSSA)</td><td> 40</td><td> 40</td><td> 40</td><td>40</td><td> 40</td>

<td> Zinc oxide</td><td> 3</td><td> 3</td><td> 3</td><td> 3</td><td> 3</td>

<td> Stearic acid</td><td> 5</td><td> 5</td><td> 5</td><td> 5</td><td> 5</td>

<td> 3-Mercaptopropyltrimethoxysi1ane : .[</td><td> -</td><td> 2</td><td> -</td><td> -</td><td> -</td>

<td> 1 ־ ' Bis-[3-triethoxysilylT propyl]-tetrasulphide</td><td> -</td><td> -</td><td> 2</td><td> —</td><td> -</td>

Bis-[3-diethoxymethylsilyl-

<td> propyl]-tetrasulphide</td><td> —</td><td> -</td><td> 2</td><td> י-</td>

<td> Bis-[3-diethoxyphenylsilyl-</td><td></td><td></td><td> . . L</td><td> --</td>

<td> propyl]-tetrasulphide</td><td></td><td> —</td><td> —</td><td> 2</td>

<td> Dibenzothiazyl-</td><td></td><td></td><td> י ־־!</td><td></td>

<td> disulphide 0.8</td><td> 0.8</td><td> 0.8</td><td> 0.8</td><td> 0.8</td>

<td> Diphenylguanidine 2.0</td><td> 2.0</td><td> 2.0</td><td> 2.0</td><td> 2.0</td>

<td> Sulphur 2.5</td><td> 2.5</td><td> 2.5.</td><td> 2.5</td><td> 2.5</td>

Mixing procedure

Premixing in a kneader at a throughflow temperature of 30°C.J

<td> Addition and handling</td><td> over</td><td> after</td>

<td> Introduce natural rubber batch Add 1/3 the quantity of silica, stearic acid and zinc oxide</td><td> 1</td><td> minute</td>

<td> cut in twice right and left Add 1/3 the quantity of silica,</td><td> 4.5</td><td> minutes</td>

<td> cut in twice right and left Add 1/3 of the quantity of silica, and accelerator, cut in twice</td><td> 8.5</td><td> minutes</td>

<td> right and left</td><td> 12</td><td> minutes</td>

<td> Draw out 3 times Properties of unvulcanized mixtures</td><td> 16</td><td> minutes</td>

<td> Mixture No. 1 2 3</td><td> 4</td><td> 5</td>

<td> tc (121°C)</td><td> 13.6</td><td> could not</td><td> 12.2</td><td> 11.2</td><td> 12.6</td>

<td></td><td></td><td> be measured</td><td></td><td></td><td></td>

<td> t121°) ״C)</td><td> 16.0</td><td> on account</td><td> 14.0</td><td> 13.0</td><td> 15.1</td>

<td> כג—</td><td></td><td> of premature</td><td></td><td></td><td></td>

<td> ML 4.</td><td> 85</td><td> vulcanisation</td><td> 51</td><td> 49</td><td> 50</td>

<td> The decrease</td><td> in the</td><td> ML-4 values as</td><td> compared</td><td> with the</td><td></td>

reference mixture No. 1 is advantageous in that it facilitates the working up of the mixtures.

: Properties of the vulcanized mixtures 1 Vulcanization temperature: 145cC.

I . v

I Mixture . TS M 300 BE PE E SH TPR • Mn. uxine ״ _____________________________ ___________________________—.-----------------------------------—

43615/2

V time TS M 300 BE PE D SH TPR

: i

+) The bad properties of Mixture 2 are due to premature vulcanization.

Among others the considerable increase in the stress values (M 300) of the vulcanisates obtained from״mixtures containing the silanes according to the invention is of special advantage.

EXAMPLE 13

The following mixtures 2 to 5 contain respectively additions of two different silanes of the group of di-, tri- and tet !sulfide functional, trialkoxysilanes in a recipe for the running surface of a truck tire in which Ultrasil VN 3 was used as filler,Mixture No. 1 is a reference mixture without addition of silane.

Mixture

No.

Recipe

Oil extended styrene butadiene rubber (Buna Huis 1712)

Polybutadiene with high cis1,4 contents (Buna CB 10)

Finely divided precipitated silica (ULTRASIL VN 3, a product of DEGUSSA)

Plasticiser (naphtenic hydrocarbon)

Zinc oxide

Stearic acid

K-Isopropyl-N'-phenyl-pphenylendiamine

Phenyl-β - naph thylamine

Tert.-Butylaminobenzthiazolsulfenamide

Diphenylguanidine

I

Sulfur ί

13is-(3־tri methoxysilylpropyl)trisulfide

Bis-(3-trimethoxysilylpropyl)tetrasulfide

Bis-(3-triethoxysilylpropyl)disulfide

Bis-(3-triethoxysilylpropyl)trisulfide j .

Bis-(3־triethoxysilylpropyl)tetrasulfide 1

2 3 4 5

96,5 ’

1,2

1,5

1,2

3.0

1,6

- --

- - 33

3 -כ-

3 3 -~

Properties of vulcanized mixtures

Vulcanization tine: 30 minutes

Vulcanization temperature: 165°C

<td> Mixture No.</td><td> TS</td><td> M 300</td><td> BE</td><td> E</td><td> SH</td><td> TPR</td>

Mixtures 2 to 5 containing the additives according to the invention show a clear increase in tensile strength and especially of the Modulus 300. The improvement of the elasticity owing to the additives of the present invention is also evident.

EXAMPLE 14

Into a mixtrue of the following composition

Parts by weight

Natural rubber (BSS I, Defo 1000)100

Finely divided precipitated silica (Ultrasil VN 3 of Degussa)40

Zinc oxide3

Stearic acid5

Dibenzothiazy!disulfideθ.θ

Diphenylguanidine2.0

Sulfur2. 5 there were incorporated two parts by weight of silane.

An identical mixture without addition of silane was used for comparison.

Properties of unvulcanized mixture

<td></td><td> No silane</td><td> Bis-(3-trimethoxysilylpropyl)pentasulfide</td><td> Bis- (3-triethoxysilylpropyl)tetrasulfide</td>

Properties of the vulcanized mixture

Vulcanization was effected at 145°C during 20 minutes.

<td> Silane TS</td><td> M 300</td><td> BE</td><td> E</td><td> SH</td><td> TPR</td>

<td> Bis- (J-trimethoxysilylpropyl)pentasulfide 253</td><td> t 121</td><td> 4?0</td><td> 48</td><td> 72</td><td> 17</td>

<td> Bis- (3-trie thoxysilylpropyl)tetrasul;fide 254</td><td> 123</td><td> 500</td><td> 51</td><td> 72</td><td> 20</td>

In the preceding examples it has been shown that the bis-(triethoxysilylpropyl)-tetrasulphide is one of the most active of this,type of compounds. The figures given above show that the bis-(trimethoxysilylpropyl)-pentasulfide is nearly as effective as the above mentioned tetrasulfide and permits within the limits of error to reach the Modulus valuesi of the mixture containing the tetrasulfide.

EXAMPLE 15

Using the same recipe as in Example 14 but replacing the two last named tetrasulfide silanes with two parts by weight of bis-(3-tricyclohexo.xysilyl-propyl) tetrasulfide there were prepared four mixtures by the method described in Example 12. The properties of these mixtures are indicated below.

Properties of unvulcanized mixtures

Mixture No.

—5 (121°C) —35 (121°C)

ML 4

<td> 14.0</td><td> could not be measured</td><td> 12. 9</td><td> 14.5</td>

<td> 16.5</td><td> on account of pre-</td><td> 14.3</td><td> 17.4</td>

<td> 86</td><td> mature</td><td> 50</td><td> 65</td>

vulcanization

Reference mixture (without silane addition)

Contains 2 parts by weight of 3-mercaptopropyltrimethoxysilane

Contains 2 parts by weight of bis-[3-triethoxysilyl-propyl] tetrasulfide

Contains 2 parts by weight of bis-[3-tricyclohexoxysilyl-propyl]tetrasulfide

Mixture No. 1:

Mixture No. 2:

Mixture No. 3:

Mixture No. 4:

Properties of vulcanized mixtures

Vulacanization temperature: 145°C.

------- --------------1

Mixture V

No. time J TS M 300 BE PE E SH

LXLUie u TS M 300 BE PE E SH

No. _____________________________________

+) The bad vulcanization properties of Mixture No. 2 are due to premature vVLucanization.

H ־

By comparison with retereacemixture 1, it can oe seen that, although the .Mooney scorch and Mooney cure times are slightly shortened by using the reinforcing additive according to' ’the invention, they are still in an industrially useiul range. By comparison with tne reference mixture, the viscosity of the crude mixture actually decreases by 'll Mooney units, which can be regarded as an altogether desirable erfect because it leads to a reduction in tyre-manufacturing costs.

So־ far as the vulcanisate properties which largely correspond to those of the reference mixture are concerned, two properties of the mixture according to the invention are immediately prominent, namely the distinctly increase□ tear . propagation resistance and the reduced heat build-up. The^ tear propagation resistance is increased by 35 % in relation to the carbon-!black-reinforced reference mixture, whilst heat build-up is reduced by 31 % from S7°C to 64°C. It is important to bear in mind in assessing the absolute results of the Goodrich Flexometer test that it was carried out with a stroke of 0.250 inch, whereas ASTM prescribes a stroke of •20 0.175 inch. It is particularly remarkable that the DIN,- ., abrasions of the carbon black mixture and silica mixture, are substantially the same. !

Accordingly, it is again confirmed that, by using the organosilane reinforcing additives according to the invention, 25 it is possible for the first time ,more readily to״produce and subsequently.to vulcanise true practical mixtures with a pure silica filling which, in all.their properties, are equivalent and, in essential characteristics, even • superior, to the corresponding carbon-black-filled mixtures.

70 members in 28 offices

This recordMember, by publication datePriority claim18 more offices are in the list below

Priority claims4

Priority claims
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2255577	Germany	A	1972-11-13
2255577	Germany	A	1972-11-13
DE19722255577	–	–	–
P22555777	–	–	–

Members70

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BE787691A	Belgium	A	1973-02-19
NL7209034A	Netherlands (Kingdom of the)	A	1973-02-20
NL7209035A	Netherlands (Kingdom of the)	A	1973-02-20
DE2141159A1	Germany	A1	1973-03-01
DE2141160A1	Germany	A1	1973-03-01
FR2149339A1	France	A1	1973-03-30
JPS4829726A	Japan	A	1973-04-19
BR7205584D0	Brazil	D0	1973-07-10
DD99585A5	German Democratic Republic (until 1990)	A5	1973-08-12
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BE807222A	Belgium	A	1974-05-13
NL7315530A	Netherlands (Kingdom of the)	A	1974-05-15
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DE2141160B2	Germany	B2	1974-11-21
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AR200663A1	Argentina	A1	1974-11-29
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DE2212239C3	Germany	C3	1984-03-15

Rubber mixtures containing reinforcing additives

Abstract

Term

CH,CH,

EXAMPLE 2

EXAMPLE 4

EXAMPLE 6'

EXAMPLE 8

EXAMPLE 11

ULTRASIL VN 3) -66

EXAMPLE 12

EXAMPLE 13

I

EXAMPLE 14

EXAMPLE 15

ML 4

Priority claims4

Members70

Numbers

Titles

Classification