Search

US-12624197-B2 - Rubber composition for an inner liner for pneumatic vehicle tyres

US12624197B2US 12624197 B2US12624197 B2US 12624197B2US-12624197-B2

Abstract

The invention relates to a rubber composition comprising a rubber component that comprises at least one halobutyl rubber selected from the group consisting of bromobutyl rubber and chlorobutyl rubber; and a filler component that comprises at least one filler F1 which has a 14 C content in the range of 0.20 to 0.45 Bq/g of carbon; a carbon content in the range of 60 wt. % to 85 wt. % relative to the ash-free and water-free filler; an STSA surface area in the range of 10 m 2 /g of filler to 50 m 2 /g of filler; and acidic hydroxyl groups on its surface; and wherein the proportion of halobutyl rubber in the rubber composition is 70 to 100 phr. The invention further relates to a vulcanisable and a vulcanised rubber composition based on the aforementioned rubber composition, a kit of parts for preparing the vulcanisable rubber composition, and methods for preparing the rubber composition and the vulcanisable rubber composition. Furthermore, the invention relates to a method for further processing the vulcanisable rubber composition, wherein webs are formed which are suitable, when cut to size, for use as inner liners in a method for manufacturing a pneumatic tyre. The invention also relates to the use of the aforementioned hydrothermally carbonised lignin for the preparation of rubber compositions for inner liners.

Inventors

  • Bernhard Schwaiger
  • Tobias Wittmann
  • Jacob Podschun
  • Alexander Stücker

Assignees

  • SUNCOAL INDUSTRIES GMBH

Dates

Publication Date
20260512
Application Date
20210922
Priority Date
20200923

Claims (19)

  1. 1 . A rubber composition comprising: a rubber component, which comprises at least one halobutyl rubber selected from the group consisting of bromobutyl rubber and chlorobutyl rubber; and a filler component which comprises at least one filler F1 that has: a 14 C content in a range of 0.20 to 0.45 Bq/g of carbon; a carbon content in a range of 60 wt. % to 85 wt. % relative to ash-free and water-free filler; an oxygen content in a range of 15 wt. % to 30 wt. % relative to ash-free and water-free filler; a statistical thickness surface area (STSA) in a range of 10 m 2 /g of the filler F1 to 50 m 2 /g of the filler F1; and acidic hydroxyl groups on a surface of the filler F1, the acidic hydroxyl groups available on the surface according to Sipponen in a range of 0.05 mmol/g to 40 mmol/g; wherein a proportion of the halobutyl rubber in the rubber composition is 70 to 100 phr.
  2. 2 . The rubber composition according to claim 1 , wherein the filler component comprises 50 to 90 phr of the filler F1.
  3. 3 . The rubber composition according to claim 1 , comprising one or more further constituents selected from the group consisting of: (i) rubbers that differ from the halobutyl rubbers, (ii) fillers F2 that differ from the filler F1, (iii) softening agents, (iv) adhesion-enhancing resins, and (v) additives promoting vulcanization.
  4. 4 . The rubber composition according to claim 3 , wherein: (i) the rubbers that differ from the halobutyl rubbers are selected from the group consisting of: natural rubber, butyl rubber and styrene-butadiene rubber, and/or (ii) the fillers F2 that differ from the filler F1 are selected from the group consisting of: carbon blacks and phyllosilicates, and/or (iii) the softening agents are selected from the group consisting of: esters of aliphatic dicarboxylic acids, paraffinic oils, and naphthenic oils, and/or (iv) the adhesion-enhancing resins are selected from the group consisting of: aliphatic hydrocarbon resins, aromatic hydrocarbon resins, phenolic resins, phenol formaldehyde resins, and phenol acetylene resins; and/or (v) the additives promoting vulcanization are selected from the group consisting of: saturated fatty acids with 12 to 24 carbon atoms and thiazoles.
  5. 5 . The rubber composition according to claim 3 , wherein: (i) a proportion of the rubbers that differ from the halobutyl rubbers in the rubber composition is 0 to 30 phr, and/or (ii) a proportion of the fillers F2 that differ from the filler F1 in the rubber composition is 0 to 40 phr, and/or (iii) a proportion of the softening agents in the rubber composition is 0 to 15 phr, and/or (iv) a proportion of the adhesion-enhancing resins in the rubber composition is 0 to 15 phr; and/or (v) a proportion of the additives promoting vulcanization in the rubber composition is 0 to 5 phr.
  6. 6 . The rubber composition according to claim 1 , wherein the filler F1 is a lignin-based filler.
  7. 7 . The rubber composition according to claim 1 , wherein the filler F1 is a hydrothermally carbonised lignin.
  8. 8 . A vulcanisable rubber composition comprising a rubber composition according to claim 1 , and a vulcanization system comprising zinc oxide and/or sulfur.
  9. 9 . The vulcanisable rubber composition according to claim 8 , wherein the vulcanization system comprises the zinc oxide, and one of the following: (a) at least one saturated fatty acid having 12 to 24 carbon atoms; (b) at least one thiuram and/or dithiocarbamate, and preferably no sulfur; (c) at least one alkyl phenoldisulfide; (d) at least polymethylolphenol resin or a halogenated polymethylolphenol resin, and preferably no sulfur and no sulfur-containing compounds; (e) sulfur and at least one thiazole and/or sulfenamide; or (f) sulfur, at least one thiazole and/or sulfenamide, and at least one saturated fatty acid having 12 to 24 carbon atoms.
  10. 10 . A kit of parts comprising, in spatially separated form, a rubber composition (A) according to claim 1 , and a vulcanization system (B) comprising zinc oxide and/or sulfur.
  11. 11 . A method for preparing a rubber composition comprising: mixing a rubber component comprising at least one halobutyl rubber selected from the group consisting of bromobutyl rubber and chlorobutyl rubber; and a filler component comprising at least one filler F1 that has: a 14 C content in a range of 0.20 to 0.45 Bq/g of carbon, a carbon content in a range of 60 wt. % to 85 wt. % relative to ash-free and water-free filler, an oxygen content in a range of 15 wt. % to 30 wt. % relative to the ash-free and water-free filler; a statistical thickness surface area (STSA) in a range of 10 m 2 /g of the filler F1 to 50 m 2 /g of the filler F1, and acidic hydroxyl groups on a surface of the filler F1, the acidic hydroxyl groups available on the surface according to Sipponen in a range of 0.05 mmol/g to 40 mmol/g, wherein a proportion of the halobutyl rubber in the rubber composition is 70 to 100 phr; and optionally further incorporation one or more softening agents, adhesion-enhancing resins, and additives promoting vulcanization therein.
  12. 12 . A method for preparing a vulcanisable rubber composition comprising: performing, in a first stage, according to the method of claim 11 to prepare the rubber composition, and subsequently, in a second stage, admixing a vulcanization system comprising zinc oxide and/or sulfur with the rubber composition to prepare the vulcanisable rubber composition.
  13. 13 . The method according to claim 12 further comprising: forming the vulcanisable rubber composition into a web by calendering, extrusion, or in a roller head process.
  14. 14 . The method according to claim 13 , wherein the web has a thickness in the range of 0.3 to 5 mm.
  15. 15 . The method of claim 13 further comprising: preparing an inner liner of a pneumatic tyre by cutting to size the web, and subsequently vulcanising the inner liner together with a carcass of a pneumatic tyre.
  16. 16 . The method of claim 11 , wherein the rubber composition is suitable for an inner liner of a pneumatic tyre, and wherein the filler F1 is defined by one or more of the following: the filler F1 is a lignin-based filler; the filler F1 is a hydrothermally carbonised lignin.
  17. 17 . A vulcanised rubber composition, obtained by vulcanising the vulcanisable rubber composition according to claim 8 .
  18. 18 . The vulcanised rubber composition according to claim 17 comprising: (a) a Shore A hardness according to ISO 7619-1 in the range of more than 50 to less than 70, and/or (b) a modulus 300 according to ISO 37 of 3.8 MPa to 10 MPa; and/or (c) a density at 23° C. according to DIN EN ISO 1183-1:2018-04 of 0.950 g/cm 3 to 1.120 g/cm 3 ; and/or (d) a gas permeability at 70° C. for air according to ISO 15105 of less than 3.9×10 −17 m 2 /Pas.
  19. 19 . The vulcanised rubber composition according to claim 17 , wherein it is an inner liner of a pneumatic tyre.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is the National Stage entry of PCT/EP2021/076086, filed on Sep. 22, 2021, which claims priority to European Application. Ser. No. 20/197,864.0, filed Sep. 23, 2020, the entire disclosures of which are hereby incorporated by reference herein. FIELD OF THE INVENTION The invention relates to rubber compositions, more particularly to vulcanisable and vulcanised rubber compositions for inner liners of pneumatic vehicle tyres. The invention further relates to a kit of parts for the manufacture thereof and methods for the manufacture and further processing thereof, as well as a method for manufacturing of pneumatic tyres. The invention further relates to the use of special fillers made of regrowing raw materials for the preparation of the rubber compositions, in particular for inner liners. BACKGROUND OF THE INVENTION Pneumatic vehicle tyres have a complex structure. Correspondingly, the demands placed on them are diverse. On the one hand, short braking distances must be ensured on dry and wet roads, and they must have good abrasion properties and low rolling resistance on the other hand. In addition, the vehicle tyres must comply with the requirements of the legislator. To ensure such a diverse performance profile, the individual tyre components are specialised and consist of a plurality of different materials, such as metals, polymer textile materials and various rubber-based components. Depending on the design of the pneumatic tyres, a distinction is made between radial tyres, cross-ply tyres and bias-ply tyres or bias-belted tyres. A typical pneumatic tyre, as an example a radial-ply belted tyre, comprises at least a belt, a belt cover, a tread, reinforcing strips, sidewalls, bead fillers, bead wires, an inner liner and a carcass. The belt usually consists of layers of stranded steel wire that are rubber-coated and angularly disposed. Its main purpose is to provide structural strength to the tyre in its air-filled state. The belt further provides for driving stability during acceleration, braking and cornering. It influences the rolling resistance and significantly contributes to the tyre's mileage. The belt overlay located between the tread and the upper belt serves for improving high-speed performance and limits the tyre diameter at increasing speed. The tread is essentially responsible for the driving characteristics. The rubber compound of the treads determines the abrasion characteristics and the dynamic driving characteristics in different weather conditions (on wet and dry roads, in cold and warm weather, on ice and snow). The design of the tread pattern, in turn, is largely responsible for the tyre's behaviour in case of aquaplaning and wet conditions as well as on snow, and also determines its noise behaviour. Reinforcing strips are optionally used in the region of the bead filler to further improve the strength of the tyre as well as the driving characteristics. The sidewall protects the carcass against lateral damage and atmospheric influences. The rubber compound for the sidewall is flexible and abrasion-resistant and contains relatively large quantities of aggregates for protection against aging and ozone. The bead filler rides on the bead wire/bead core. Its form and configuration provide driving stability and have an influence on the steering precision and the suspension comfort. Rubber compounds for bead fillers are typically very strong and relatively hard, which is ensured, among other things, by a high degree of crosslinking using highly dosed vulcanisation systems and by the selection of the fillers. The bead wire is the inner part of the tyre bead and consists of stranded steel wires coated with rubber that are annularly coiled and hold the tyre stably on the rim. In the common tubeless configuration, the tyre bead (also called tyre base or foot) presses against the rim flange and closes the tyre in an airtight manner. The steel cords and wires in the bead core, the tread or in the carcass of the full steel tyre must firmly connect with the surrounding rubber compound in order to act as a composite. For that purpose, the steel wires are often coated with brass or bronze. Only thereafter they are formed, using a wire bonding compound, into tyre building parts which in turn are assembled to form a tyre blank. Wire bonding compounds are relatively strong, tear resistant due to their high proportion of natural rubber and achieve a strong connection to the brass or bronze coating, for example by special resin additives and a high sulfur content. The permanent connection is formed during vulcanisation. The carcass forms the basic structure of the tyre and consists of one or more textile fabric layers (Rayon, Nylon, polyester, aramid) or steel cord layers (for trucks) that are embedded in rubber. The carcass is put under tension by means of the tyre air pressure and is therefore substantially responsible for the transmission of forces, betw