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CN-121986028-A - Sulfur-crosslinkable rubber mixtures and vehicle tires

CN121986028ACN 121986028 ACN121986028 ACN 121986028ACN-121986028-A

Abstract

The invention relates to a sulfur-crosslinkable rubber mixture, in particular for a vehicle tire, comprising a) one or more solid diene rubbers, b) one or more liquid styrene-butadiene polymers (LSBR) having a weight average molecular weight (M) of 4000 to 30,000 g/mol according to GPC and a polymer backbone modified by means of substituents, c) one or more fillers comprising at least 50 phr or more silica fillers, and d) one or more plasticizers, wherein the one or more liquid styrene-butadiene polymers according to b) have an average degree of modification of 4 to 30 substituents per 100 monomers. The invention also relates to a corresponding use and a vehicle tyre.

Inventors

  • CHRISTIAN WEBER
  • KENDZIORRA NORBERT
  • Julian strommer
  • David Raphael Doyle

Assignees

  • 大陆轮胎德国有限公司

Dates

Publication Date
20260505
Application Date
20241021
Priority Date
20231019

Claims (15)

  1. 1. A sulfur-crosslinkable rubber mixture comprising a sulfur-crosslinkable rubber, the sulfur-crosslinkable rubber mixture comprises: a) One or more than one solid diene rubber; b) One or more than one liquid styrene-butadiene polymer (LSBR) having a weight average molecular weight M w of 4000 to 30 000 g/mol by GPC and having a polymer backbone modified by means of substituents; c) One or more than one filler comprising at least 50 phr or more silica fillers, and D) One or more plasticizers; Wherein the one or more than one liquid styrene-butadiene polymer according to b) has a corresponding average degree of modification of 4 to 30 substituents per 100 monomers.
  2. 2. The sulfur-crosslinkable rubber mixture of claim 1 comprising two, three or more than three solid diene rubbers in a).
  3. 3. The sulfur-crosslinkable rubber mixture of claim 1 or 2, wherein the one or more diene rubbers according to a) are selected from the group consisting of natural polyisoprene (NR), synthetic polyisoprene (IR), epoxidized polyisoprene (ENR), butadiene Rubber (BR), butadiene-isoprene rubber, solution-polymerized styrene-butadiene rubber (SSBR), emulsion-polymerized styrene-butadiene rubber (ESBR) and hydrogenated styrene-butadiene rubber.
  4. 4. The sulfur-crosslinkable rubber mixture of any one of claims 1 and 2, wherein the one or more solid diene rubbers according to a) comprise natural polyisoprene (NR), solution-polymerized styrene-butadiene rubber (SSBR), emulsion-polymerized styrene-butadiene rubber (ESBR) and/or hydrogenated styrene-butadiene rubber.
  5. 5. The sulfur-crosslinkable rubber mixture of any one of claims 1 to 4, wherein the one or more than one liquid styrene-butadiene polymer according to b) has a weight average molecular weight M w of 5000 to 25 000 g/mol, preferably 6000 to 21 000 g/mol, further preferably 7000 to 18 000 g/mol, more preferably 8000 to 15 000 g/mol, most preferably 9000 to 12 000 g/mol.
  6. 6. The sulfur-crosslinkable rubber mixture of any one of claims 1 to 5, wherein the one or more than one liquid styrene-butadiene polymer according to b) has a respective average degree of modification of 4.3 to 27, preferably 4.5 to 24, further preferably 4.7 to 21, more preferably 4.9 to 18, even more preferably 5.1 to 15, most preferably 5.3 to 12.
  7. 7. The sulfur-crosslinkable rubber mixture of any one of claims 1 to 6, wherein some or all, preferably all, of the substituents are silicone substituents.
  8. 8. The sulfur-crosslinkable rubber mixture of claim 7, wherein the silicone substituent has a structure according to formula (I): (R 1 R 2 R 3 )Si-X- (I), Wherein, in each case independently of one another, -R 1 、R 2 and R 3 are selected from the group consisting of methoxy, ethoxy, phenoxy, methyl, ethyl and phenyl, wherein at least one of these radicals R 1 、R 2 and R 3 is methoxy, ethoxy or phenoxy, and X is a divalent alkylene group of from C 1 to C 18 , preferably from C 1 to C 14 , further preferably from C 1 to C 10 , more preferably from C 1 to C 7 , further preferably from C 1 to C 5 , most preferably from C 2 to C 4 , most particularly preferably propylene.
  9. 9. The sulfur-crosslinkable rubber mixture of any one of claims 1 to 8, wherein the one or more liquid styrene-butadiene polymers according to b) are present in a total amount of 1 to 25 phr, preferably 3 to 22 phr, further preferably 5 to 20 phr, particularly preferably 7 to 18 phr, further particularly preferably 9 to 15 phr.
  10. 10. The sulfur-crosslinkable rubber mixture of any one of claims 1 to 9, wherein the one or more solid diene rubbers according to a) comprise 40 phr or more at least one solution-polymerized styrene-butadiene rubber (SSBR) having a glass transition temperature T g in the range of-55 ℃ to-75 ℃.
  11. 11. The sulfur-crosslinkable rubber mixture of any one of claims 1 to 10, wherein the silica filler according to c) comprises a blocked mercaptosilane, preferably a blocked mercaptosilane comprising octanoyl groups.
  12. 12. The sulfur-crosslinkable rubber mixture of any one of claims 1 to 11, wherein the silica filler according to c) does not exceed a total amount of 140 phr, preferably 135 phr.
  13. 13. Use of liquid styrene-butadiene polymers (LSBR) as stiffness additives in sulfur-crosslinkable rubber mixtures Having a weight average molecular weight M w of 4000 to 30,000 g/mol by GPC, and -Having a polymer backbone modified by means of substituents with an average degree of modification of 4 to 30 substituents per 100 monomers.
  14. 14. A vehicle tyre, preferably a pneumatic vehicle tyre, comprising one or more than one component of a sulfur-vulcanized rubber mixture as defined in any one of claims 1 to 12.
  15. 15. The vehicle tire of claim 14, wherein, The component has a shore a hardness at 25 ℃ in the range of 64 to 75, preferably 66 to 73, And/or The component is a tread or a part of a tread.

Description

Sulfur-crosslinkable rubber mixtures and vehicle tires Technical Field The present invention relates to a sulfur-crosslinkable rubber mixture, in particular for a vehicle tire, comprising one or more than one liquid styrene-butadiene polymer with specific modifications as further set forth in the text below, and to a corresponding use and a corresponding vehicle tire. Background The running characteristics of tires, particularly pneumatic vehicle tires, depend to a significant extent on the rubber mixtures of the individual components. Thus, stringent requirements are imposed on the composition of these mixtures. Accordingly, different attempts have been made to positively influence the properties of the tire by variations in the polymer components, fillers and other adjuvants in the mixture. In this case, it must be kept in mind that an improvement in one tire characteristic generally results in a deterioration of the other (target conflict). For example, improvement in wear characteristics typically results in degradation of braking characteristics on dry running surfaces. Certain parts of the tire require, for example, a high degree of rigidity to improve handling, examples being apex or tread. The high degree of stiffness also improves durability, such as the durability of the rubber coating of the belt (belt). Typically, higher stiffness is achieved in particular by increasing the filler content or by decreasing the plasticizer content. This is often associated with negative effects on other important tire characteristics due to the above-mentioned objective conflicts. An increase in filler content generally results in an increase in rolling resistance (i.e., degradation) and an associated increase in heat generation. In order to reduce the energy consumption of the tire, measures are generally sought to further minimize the rolling resistance of the tire components. Reducing the plasticizer content is generally no longer practically possible, since it is already relatively low and is generally hardly reduced further without, for example, losing the required grip of the tire component (e.g. tread) or causing disadvantageous viscosities in the corresponding rubber mixtures. For example, it has been known that modified rubbers (or polymers), including liquid rubbers, can significantly alter the characteristics of tire components. Different microstructures are generally used here. The diene rubber may also be modified by performing end group modification, coupling or hydrogenation. For example, WO 2016/198177 A1 discloses rubber mixtures for tire treads in which liquid polybutadiene is used which is terminally silicone-modified and has a weight average molecular weight M w of 500 to 12,000 g/mol by GPC. WO 2022/262914 A1 discloses a sulfur-crosslinkable rubber mixture in which at least one liquid modified diene polymer a is used which has a weight average molecular weight M w of 500 to 50 g/mol by GPC, wherein the modification enables interaction with the polar filler and is present along the polymer backbone. A similar disclosure exists in EP 3 785 929 A1. Disclosure of Invention It is an object of the present invention to provide a sulfur-crosslinkable rubber mixture which leads to a further increased stiffness in the corresponding component in order to achieve improved handling without significantly increasing the rolling resistance. This allows to further reduce/resolve the above-mentioned drawbacks/target conflicts at a higher level. According to the invention, this object is achieved by a sulfur-crosslinkable rubber mixture, preferably for a vehicle tire, comprising: a) One or more than one solid diene rubber; b) One or more than one liquid styrene-butadiene polymer (LSBR) having a weight average molecular weight M w of 4000 to 30 000 g/mol by GPC and having a polymer backbone modified by means of substituents; c) One or more than one filler comprising at least 50 phr or more silica fillers, and D) One or more plasticizers; wherein one or more than one liquid styrene-butadiene polymer according to b) has a corresponding average degree of modification of 4 to 30 substituents per 100 monomers. In internal testing, it has been unexpectedly shown that a specially modified liquid styrene-butadiene polymer (LSBR) as described above and below results in a significant increase in stiffness, but not in rolling resistance (see examples below). This relates to rubber mixtures according to the invention which further comprise one or more solid diene rubbers. It is particularly surprising that in addition to the increase in stiffness there is actually a decrease in rolling resistance. In the present context, the degree of modification is generally the number of substituents per 100 monomers of the corresponding polymer. The entire polymer is considered here to produce an average degree of modification. In the context of the present invention, the liquid styrene-butadiene polymer (LSBR) according to b) generally