WO2014106580A1 - Rubber mixture - Google Patents

Abstract

The invention relates to a rubber mixture, in particular for vehicle air-inflated tires, seatbelts, belts and hoses. Said rubber mixture contains the following components: at least one diene rubber and at least one silcic acid and at least one oligo-(n-(n'-trialkoxysilyl-alkyl)cycloalkane-n'',n'''-diyl)bis-oligosulphide and/or oligo-(n-(n'-trialkoxysilyl-alkyl)cycloalkane-n''-yl)oligosulphide as silane, wherein n, n', n'', n''' can have, independently from each other, values of between 1 and 10, and additional additives.

Description

 description

rubber compound

The invention relates to a rubber compound, in particular for pneumatic vehicle tires, straps, belts and hoses.

The rubber composition of the tread highly determines the ride characteristics of a tire, especially a pneumatic vehicle tire. Likewise, the rubber compounds found in belts, hoses and straps, especially in the mechanically heavily stressed areas, are essentially responsible for the stability and longevity of these rubber articles. Therefore, to this

Rubber compounds for pneumatic vehicle tires, belts, belts and hoses very high demands.

 By partially or completely replacing the filler carbon black with silica in rubber compounds, e.g. Overall, the driving characteristics of a tire have been raised to a higher level in recent years. The well-known

Zielkonfiikte the oppositely behaving tire properties, however, continue to exist even with siliceous tread compounds. Thus, an improvement in the wet grip and the dry braking further tends to result in a deterioration of the rolling resistance and the abrasion behavior. These properties are also an important quality criterion for technical rubber articles such as straps, belts and hoses.

In order to solve these goal confiicts, various approaches have already been pursued. For example, the most varied and modified polymers, plasticizers and finely divided fillers for rubber compounds have been used, and attempts have been made to influence the vulcanizate properties by modifying the preparation of the mixture.

In silicic acid-containing rubber mixtures, organosilanes are used to hydrophobize the silica and to form the bond between filler and polymer. Polysulfidic organosilanes) are attached to the polymer. However, different silanes have different effects on the physical properties of the rubber compound. For example, it is known from WO2008083242A1 that the "silated core polysulfides" (SCP) described there, ie silanes with cyclic units, improve the abrasion behavior but have no influence on the rolling resistance behavior

Although bis (triethoxysilylpropyl) disulfide (TESPD) and bis (triethoxysilylpropyl) tetrasulfide (TESPT), monomeric silanes such as mercaptosilanes improve rolling resistance performance, they do so with a greatly deteriorated one

Processability and reduced wet grip behavior and greater abrasion loss. Protected mercaptosilanes, i. Mercaptosilanes in which the mercapto group is blocked only improve the rolling resistance slightly at the expense of the wet grip and abrasion, however, the rigidity, i. the handling potential, sinks. The invention is therefore based on the object to provide a rubber mixture, which in particular contains silica as a filler, which shows a significantly improved rolling resistance behavior, while at the same time

Wet grip behavior remains at the same level. As a result, the conflict of objectives between rolling resistance versus wet grip is resolved or at least mitigated.

This object is achieved by the provision of a rubber mixture which comprises at least one diene rubber and at least one silica and at least one oligo- (n- (n'-trialkoxysilyl-alkyl) cycloalkane-n ", n'-diyl) bis-oligosulfide and / or or at least one 01igo- (n- (n'-trialkoxysilyl-alkyl) cycloalkane-n "-yl) oligosulfide as silane, where n, n ', n" and n' "independently of one another can assume values between 1 and 10.

Surprisingly, it has been found that such a rubber mixture has an optimized rolling resistance behavior, without adversely affecting the wet grip behavior.

The rubber mixture contains at least one diene rubber. Preferably, this is selected from the group consisting of natural

Polyisoprene and / or synthetic polyisoprene and / or butadiene rubber and / or styrene-butadiene rubber and / or solution-polymerized

 Styrene-butadiene rubber and / or emulsion-polymerized styrene-butadiene rubber, with particularly good properties being achieved when using at least one natural polyisoprene.

 The solution-polymerized styrene-butadiene rubber may be used in a particular

Embodiment be hydrogenated and / or with hydroxyl groups and / or

Epoxy groups and / or siloxane groups and / or amino groups and / or

Aminosiloxan and / or carboxyl groups and / or Phtalocyaningruppen be modified. But there are also others known to the expert,

Modifications, also referred to as functionalizations, in question

The diene rubber is preferably used in amounts of from 10 to 100 phr, particularly preferably in amounts of from 30 to 100 phr, very particularly preferably in amounts of from 50 to 100 phr.

 Particularly good properties with regard to the rolling resistance behavior are exhibited when the rubber mixture contains at least 5 phr, preferably 5 to 50 phr, particularly preferably 5 to 30 phr, of at least one natural and / or synthetic

Polyisoprene contains.

In the rubber mixture, however, it is also possible for further polar or nonpolar rubbers to be present, for example liquid rubbers and / or

Halobutyl rubber and / or polynorbornene and / or isoprene-isobutylene copolymer and / or ethylene-propylene-diene rubber and / or nitrile rubber and / or chloroprene rubber and / or acrylate rubber and / or

 Fluororubber and / or silicone rubber and / or polysulfide rubber and / or epichlorohydrin rubber and / or styrene-isoprene-butadiene terpolymer and / or hydrogenated acrylonitrile-butadiene rubber and / or isoprene-butadiene copolymer and / or hydrogenated styrene-butadiene rubber.

In particular nitrile rubber, hydrogenated acrylonitrile-butadiene rubber,

Chloroprene rubber, butyl rubber, halobutyl rubber or ethylene-propylene Diene rubber is used in the manufacture of technical rubber articles such as straps, belts and hoses.

The other rubber may preferably be used in amounts of 0 to 20 phr, especially in amounts of 0 to 10 phr.

The term phr used in this document (parts per hundred parts of rubber by weight) is the usual quantity in the rubber industry for

Mix recipes. The dosage of the parts by weight of the individual substances is always 100 parts by weight of the total mass of all in the mixture

related rubbers.

The rubber mixture of the invention contains at least one silica, which is often referred to as a light filler.

The silicas used in the rubber industry are generally precipitated silicas, which are characterized in particular according to their surface. For characterization, the nitrogen surface area (BET) according to DIN 66131 and DIN 66132 as a measure of the inner and outer filler surface in m ² / g and the CTAB surface according to ASTM D 3765 as a measure of the outer surface, often as the rubber surface, in m ² / g. According to the invention, silicas having a nitrogen surface area of greater than or equal to 50 m ² / g, preferably between 50 and 320 m ² / g, more preferably between 100 and 250 m ² / g, and a CTAB surface area between 50 and 300 m ² / g, preferably between 50 and 250 m ² / g and particularly preferably between 80 and 250 m ² / g used.

Particularly good results can be achieved if the CTAB surface area of the silica is between 150 and 250 m ² / g.

The amount of silicic acid is preferably 1 to 300 phr, more preferably 5 to 250 phr and most preferably 10 to 200 phr. The rubber mixture of the invention may further contain at least one dark filler. The total amount of filler can thus consist only of light filler or a combination of light and dark fillers. The carbon black is in a preferred embodiment in amounts of 0 to 100 phr, more preferably in amounts of 0 to 80 phr, most preferably in amounts of 0 to 60 phr, preferably at least in amounts of 0.1 phr, more preferably at least but in amounts of 0.5 phr, used. In a particularly preferred embodiment, the carbon black has an iodine value, according to ASTM D 1510, which is also referred to as iodine adsorption number, greater than or equal to 20 g / kg, preferably greater than or equal to 35 g / kg, particularly preferably greater than or equal to 50 g / kg, most preferably greater than or equal to 75 g / kg and a DBP number greater than or equal to 60 cm ³ / 100g, preferably greater than or equal to 80 cm ³ / 100g. The DBP number according to ASTM D 2414 determines the specific adsorption volume of a carbon black or a light filler by means of dibutyl phthalate.

In addition to silica and carbon black, the rubber mixture may also contain further fillers such as aluminum hydroxide, layered silicates, lime, chalk, starch, magnesium oxide, titanium dioxide, rubber gels, short fibers, etc. in any desired combinations.

It is essential to the invention that the rubber mixture comprises at least one

01igo- (n- (n'-trialkoxysilyl-alkyl) -cycloalkane-n ", n" '- diyl) bis-oligosulfide and / or at least one 01igo- (n- (n'-trialkoxysilyl-alkyl) -cycloalkane-n "- yl) contains oligosulfide as silane Only then do the advantages regarding the rolling resistance behavior become apparent without disadvantages in wet grip behavior.

The preparation of such oligo (n- (n'-trialkoxysilyl-alkyl) cycloalkane n ", n"'- diyl) bis-oligosulfides and / or oligo (n- (n'-trialkoxysilyl-alkyl) cycloalkane-n " -yl) oligosulfides are described, for example, in particular in EP4660661A1, but also in WO96 / 10604 A1, where n, n ', n "and n'" can independently of one another assume values between 1 and 10. It is preferred for n, n ', n "and n'" by the integer values 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10, more preferably 1, 2, 3, and 4. The silanes mentioned are multimeric sulfur-bridged silanes which have a cyclohexyl spacer group (cyclohexyl spacer). In the following, therefore, these silanes are referred to as cyclohexylspacersilanes.

The cyclohexylspacersilan is preferably used in amounts of from 0.1 to 25 phr, particularly preferably in amounts of from 0.1 to 20 phr, very particularly preferably from 3 to 15 phr.

 The quantity refers to the total amount of

01igo- (n- (n'-trialkoxysilyl-alkyl) -cycloalkane-n ", n" -diyl) bis-oligosulfide and / or oligo-n- (n'-trialkoxysilyl-alkyl) -cycloalkane-n "-yl) oligosulfide.

It is quite possible that in the rubber mixture according to the invention further silanes, as described above, are included. Preferably, however, the rubber composition is free of other silanes, i. the amount of other silanes is 0 phr.

There may be present in the rubber mixture 0.1 to 150 phr, preferably 1 to 80 phr, more preferably 10 to 80 phr, most preferably 20 to 60 phr, of at least one plasticizer. This plasticizer is preferably selected from the group consisting of mineral oils and / or synthetic plasticizers and / or fatty acids and / or fatty acid derivatives and / or resins and / or ingredients and / or glycerides and / or liquid polymers having a molecular weight of less than or equal to 2000 g / mol and / or terpenes and / or vegetable oils and / or biomass-to-liquid oils and / or rubber-to-liquid oils. Furthermore, the rubber mixture contains other additives.

 Further additives essentially include the crosslinking system (crosslinker, sulfur donor and / or elemental sulfur, accelerator and retarder), antiozonants, anti-aging agents, masticating agents and others

Activators.

The proportion of the total amount of further additives is 3 to 150 phr, preferably 3 to 100 phr and more preferably 5 to 80 phr. The vulcanization of the rubber compound is intended for use in

Pneumatic vehicle preferably performed in the presence of elemental sulfur or sulfur donors, with some sulfur donors at the same time as

Vulkanisationsbeschleuniger can act. Elemental sulfur and / or

Sulfur donors are added in the last mixing step in the amounts customary by the skilled person (0.1 to 10 phr, wherein elemental sulfur is preferably contained in amounts of 0 to 6 phr, more preferably in amounts of 0.1 to 4 phr) of the rubber mixture , To control the required time and / or temperature of the vulcanization and to improve the vulcanizate properties, the rubber mixture vulkanisationsbeeinflussende substances such as

 Vulcanization accelerators, cure retarders, and cure activators contained in the additives described above.

It is advantageous if the rubber mixture according to the invention contains 0.1 to 6 phr, preferably 1 to 5 phr, of at least one vulcanization accelerator.

The vulcanization accelerator is preferably selected from the group of sulfenamide accelerators and / or thiazole accelerators and / or

Thiuram accelerator and / or mercapto accelerator and / or

Dithiocarbamatebeschleumger and / or amine accelerators and / or dithiophosphates and / or thioureas, with sulfenamide accelerators are preferred.

The preferred sulfenamide accelerator is benzothiazyl-2-cyclohexylsulfenamide (CBS).

The preparation of the rubber mixture according to the invention is usually carried out according to the usual method in the rubber industry, in which first in one or more mixing stages, a base mixture with all components except the

 Vulkanisationssystem (for example, sulfur and vulcanization-influencing substances) is produced. By adding the vulcanization system in a final mixing stage, the finished mixture is produced. The ready mix is e.g. through a

Extrusion process further processed and brought into the appropriate form.

The invention is further based on the object, as described above

Rubber compound, for the manufacture of tires, in particular for the production of tires Tread of a tire and / or a body mixture of a tire and to use for the production of belts, straps and hoses.

 The tire may be a truck tire, a car tire or a two-wheeled tire. However, the use of the

rubber composition according to the invention in a passenger tire and there preferably as a rubber mixture for the tread.

The body mix of a tire is essentially the sidewall, innerliner, apex, belt, shoulder, belt profile, squeegee, carcass, bead enhancer and / or bandage rubber compounds.

For use in pneumatic vehicle tires, the mixture is preferably made in the form of a tread and applied as known in the manufacture of the vehicle tire blank. The tread may also be in the form of a narrow

Rubber mix strip are wound onto a green tire. If the tread, as described above, two-piece or multi-part, so the rubber mixture is preferably used as a mixture for the cap.

The preparation of the rubber mixture according to the invention for use as a body mixture in vehicle tires is carried out as already described for the tread. The difference lies in the shape after the extrusion process. The thus obtained forms of the rubber mixture according to the invention for one or more different body mixtures then serve to build up a green tire. In order to use the rubber composition of the invention in belts and straps, especially in conveyor belts, the extruded mixture is shaped into the appropriate shape and often or subsequently with reinforcing materials, e.g. synthetic fibers or steel cords. In most cases, this results in a multi-layered structure, consisting of one and / or several layers of rubber mixture, one and / or more layers of identical and / or different reinforcement and one and / or several other layers of the like and / or another rubber mixture.

For use of the rubber mixture according to the invention in hoses, peroxide crosslinking is often preferred. The production of the hoses takes place mostly in the same way as in the handbook of rubber technology, Dr. med. Gupta Verlag, 2001, Chapter 13.4.

The invention will now be explained in more detail by means of comparison and exemplary embodiments, which are summarized in Tables la and lb. The mixtures marked with "E" here are mixtures according to the invention, while the mixtures marked with "V" are comparative mixtures. The table marked "a" represents the mixture composition, while the table marked "b" illustrates the corresponding corresponding physical properties.

For all mixing examples contained in the table, the quantities given are parts by weight based on 100 parts by weight of total rubber (phr).

Mixture preparation was carried out under customary conditions in several stages in a laboratory tangential mixer. From all mixtures test specimens were prepared by vulcanization and determined with these specimens typical for the rubber industry material properties. For the tests described above

Test specimens were subjected to the following test procedures:

 • Rebound resilience at room temperature and 70 ° C according to DIN 53 512

 • Shore A hardness at room temperature according to DIN 53 505

 • Voltage value at 50% and at 200% elongation at room temperature according to DIN 53 504

 • Elongation at room temperature according to DIN 53 504

 Tensile strength at room temperature in accordance with DIN 53 504

 • Loss factor tan d, synonymous with tan δ, at 55 ° C from dynamic-mechanical

Measurement according to DIN 53 513

· Dynamic storage modulus E 'at 55 ° C according to DIN 53 513 at 8% elongation The following silanes were used in the tables:

Silane: TESPD

 Silane 2: blocked mercaptosilane, NXT lowV, from Momentive Performance Materials Inc.

Silane 3: 3-mercaptopropyltriethoxysilane, Si 363, Evonik

Silane 4: cyclohexylspacersilane

Table la

 a NR, TSR

 b BR, Nd-BR, Fa. Lanxess

 C SSBR, NS116, Zeon

d Zeosil 1165MP, Rhodia, CTAB 155m ² / g, BET 160 m ² / g

 e TDAE

 6PPD, antiozonant wax, stearic acid

 g CBS

h DPG Table lb

It can be seen from Tables la and lb that the rubber mixtures E1 to E2 according to the invention have a distinct advantage with regard to the conflict of objectives

Rolling resistance versus wet grip offer.

The rolling resistance behavior is represented by the rebound resilience at 70 ° C, with higher values representing an improvement. Wet grip behavior is illustrated by room temperature rebound resilience, with lower values being an improvement. Delta rebound, in turn, indicates the difference between the two rebound values, increasing this difference im means that the target conflict between rolling resistance and wet grip is better resolved, and the value for tan d also shows improved rolling resistance behavior, with lower values each indicating the improvement At the same time, it can be seen from the value for E '(8%) that the dynamic stiffness improves, which has a positive effect on the handling behavior, resulting in a hitherto unknown property profile due to the rubber mixture according to the invention Rolling resistance with simultaneous increase in stiffness without losses in wet braking The specific advantages of the used

Cyclohexylspacersilan when used in rubber mixtures, inter alia, also result from the interaction with the rubbers and rubber mixtures used here. Thus, the Cyclohexylspacersilan shows in particular in Interplay with a natural polyisoprene (NR) the described property picture of improved hysteresis properties and high rigidity. Specifically, the improvement in hysteresis properties is enhanced at elevated NR content.

Claims

claims 1. rubber mixture, characterized in that they  at least one diene rubber and  - At least one silica and  at least one 01igo- (n- (n'-trialkoxysilyl-alkyl) cycloalkane-n ", n" '-diyl) bis-oligosulfide and / or at least one 01igo- (n- (n'-trialkoxysilylalkyl) -cycloalkane n "-yl) oligosulfide as silane, where n, η ', n", n' "independently of one another can assume values between 1 and 10, and  - contains other additives. 2. Rubber mixture according to claim 1, characterized in that it contains at least 5 phr of at least one natural polyisoprene. 3. Rubber mixture according to claim 1 or 2, characterized in that it contains 5 to 50 phr of at least one natural polyisoprene. 4. Rubber mixture according to one of claims 1 to 3, characterized  characterized in that the silane is used in amounts of 0, 1 to 25 phr. 5. Rubber mixture according to one of claims 1 to 4, characterized  characterized in that it contains 1 to 300 phr of at least one silica. 6. rubber mixture according to claim 5, characterized in that the Silica has a CTAB surface area between 20 and 250 m ² / g. 7. Rubber mixture according to one of claims 1 to 6, characterized  characterized in that it contains at least one sulfenamide accelerator. 8. Use of a rubber mixture according to any one of claims 1 to 7 for the preparation of a tire. 9. Use of a rubber mixture according to claim 8 for the preparation of the tread and / or a body mixture of a tire.  10. Use of a rubber mixture according to one of claims 1 to 7 for the production of a belt, belt or hose.