DIENE-BASED ELASTOMER AND A RUBBER COMPOSITION

Abstract

The present invention is directed to a benzoxazine-functionalized diene-based elastomer comprising polymer chains including repeat units which include conjugated diolefin monomers, such as 1,3-butadiene and isoprene. Additionally, said elastomer comprises at least one benzoxazine connected to a polymer chain via a spacer, wherein the spacer has a length ranging from 3 to 8 atoms. A further aspect of the present invention is directed to a rubber composition comprising such an elastomer, an article of manufacture comprising this rubber composition, and a method of making said benzoxazine-functionalized diene-based elastomer.

Claims

1. A benzoxazine-functionalized diene-based elastomer comprising: polymer chains having repeat units which include conjugated diolefin monomers, and at least one benzoxazine connected to the polymer chains via a spacer, wherein the spacer has a length ranging from 3 to 8 atoms.

2. The benzoxazine-functionalized diene-based elastomer of claim 1 wherein the benzoxazine is connected to the spacer through a nitrogen atom in its ring structure.

3. The benzoxazine-functionalized diene-based elastomer of claim 1 wherein said repeat units further include residues of vinyl aromatic monomers.

4. The benzoxazine-functionalized diene-based elastomer of claim 1 wherein the benzoxazine has the following structure: ##STR00012## wherein: R.sub.1 is one of: a hydrogen atom, a hydrocarbon group, a cyclic hydrocarbon; R.sub.2 is one of: a hydrogen atom, a hydrocarbon group, a cyclic hydrocarbon; R.sub.3 is one of: a hydrogen atom, a hydrocarbon group, a cyclic hydrocarbon; R.sub.4 is one of: a hydrogen atom, a hydrocarbon group, a cyclic hydrocarbon, and wherein N is a nitrogen atom covalently bound to the polymer chain through the spacer.

5. The benzoxazine-functionalized diene-based elastomer of claim 4 wherein at least one of R.sub.1 and R.sub.2 is a hydrogen atom.

6. The benzoxazine-functionalized diene-based elastomer of claim 4 wherein R.sub.1 and R.sub.3 are both hydrogen atoms.

7. The benzoxazine-functionalized diene-based elastomer of claim 4 wherein the benzoxazine has one of the following structures: ##STR00013##

8. The benzoxazine-functionalized diene-based elastomer of claim 4 wherein the benzoxazine-functionalized diene-based elastomer comprises the following structure: ##STR00014## wherein: R.sub.5 is the spacer; Pol is the polymer chain; and R.sub.6 is one of a hydrogen atom and a functional group.

9. The benzoxazine-functionalized diene-based elastomer of claim 1 wherein the polymer chain has one or more of: i) between 15 and 25,000 repeat units; or ii) a weight average molecular weight which is within a range of 1000 g/mol to 1,500,000 g/mol.

10. The benzoxazine-functionalized diene-based elastomer of claim 4 wherein the benzoxazine-functionalized diene-based elastomer comprises the following structure: ##STR00015## wherein: R.sub.5 is the spacer x, y, z are integers or zero, and wherein at most two of x, y, z may be zero; and R.sub.6 is a hydrogen atom or a functional group.

11. The benzoxazine-functionalized diene-based elastomer of claim 8 wherein R.sub.6 is a functional group selected from the group consisting of: silane containing groups, siloxane containing groups, secondary amine groups, and silicon tetrachloride derivatives.

12. The benzoxazine-functionalized diene-based elastomer of claim 1 wherein the majority of bonds along the spacer are single bonds.

13. The benzoxazine-functionalized diene-based elastomer of claim 1 wherein the spacer comprises along its length at least one alkylene group, with or without one or more hetero atoms.

14. The benzoxazine-functionalized diene-based elastomer of claim 1 wherein the spacer comprises a silyl group.

15. The benzoxazine-functionalized diene-based elastomer of claim 1 wherein the spacer comprises a silyl group and the polymer chain is coupled to the silyl group via an oxygen atom of the silyl group.

16. The benzoxazine-functionalized diene-based elastomer of claim 1 wherein the spacer has the following structure ##STR00016## wherein R.sub.7 represents an ethylene group, a propylene group, a butylene group, a pentylene group, and a hexylene group; and wherein O is an oxygen atom covalently bound to the polymer chain.

17. The benzoxazine-functionalized diene-based elastomer of claim 1 wherein the spacer is an alkylene group.

18. The benzoxazine-functionalized diene-based elastomer of claim 1 wherein the conjugated diolefin monomer is selected from the group consisting of 1,3-butadiene, isoprene, 1,3-pentadiene, 1,3-hexadiene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, 2-methyl-1,3-pentadiene, 3-methyl-1,3-pentadiene, 4-methyl-1,3-pentadiene, and 2,4-hexadiene.

19. A rubber composition comprising: 30 to 200 phr of a filler; and 10 to 100 phr of the benzoxazine-functionalized diene-based elastomer according to claim 1.

20. An article of manufacture selected from a tire, a power transmission belt, a hose, a track, an air sleeve, and a conveyor belt, comprising the rubber composition according to claim 19.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0091] The invention will be described by way of example and with reference to the accompanying drawings in which:

[0092] FIG. 1 is a schematic cross section of a tire which comprises a benzoxazine-functionalized elastomer according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0093] FIG. 1 is a schematic cross-section of a tire 1. The tire 1 has a tread 10, an inner liner 13, a belt structure comprising four belt plies 11, a carcass ply 9, two sidewalls 2, and two bead regions 3 comprising bead filler apexes 5 and beads 4. The example tire 1 is suitable, for example, for mounting on a rim of a vehicle, e.g. a truck or a passenger car. As shown in FIG. 1, the belt plies 11 may be covered by an overlay ply 12 and/or may include one or more breaker plies. The carcass ply 9 includes a pair of axially opposite end portions 6, each of which is associated with a respective one of the beads 4. Each axial end portion 6 of the carcass ply 9 may be turned up and around the respective bead 4 to a position to anchor each axial end portion 6. The turned-up portions 6 of the carcass ply 9 may engage the axial outer surfaces of two flippers 8 and axial inner surfaces of two chippers 7. As shown in FIG. 1, the example tread 10 may have four circumferential grooves, each groove essentially defining a U-shaped opening in the tread 10. The main portion of the tread 10 may be formed of one or more tread compounds, which may be any suitable tread compound or compounds.

[0094] While the embodiment of FIG. 1 suggests a plurality of tire components including for instance apexes 5, chippers 7, flippers 8 and overlay 12, such components are not mandatory for the invention. Also, the turned-up end of the carcass ply 9 is not necessary for the invention or may pass on the opposite side of the bead area 3 and end on the axially inner side of the bead 4 instead of the axially outer side of the bead 4. The tire could also have for instance more or less than four grooves.

[0095] In the embodiment of FIG. 1, one or more rubber components, in particular, the tread 10 comprise a benzoxazine-functionalized elastomer. In principle, also other rubber components, such as a coating compound of the carcass ply 9, a coating compound of the overlay ply 12, the apexes 5 or other rubber components of the tire 1 can comprise such an elastomer. The elastomer may be blended with other elastomers, for instance with one or more solution polymerized styrene-butadiene rubbers, polybutadiene or polyisoprene rubber.

[0096] In a non-limiting embodiment, a benzoxazine-functionalized elastomer is manufactured as shown herein below:

##STR00010##

[0097] Thus, the elastomer having a polymer chain R (such as a polybutadiene or a styrene-butadiene) is end-functionalized with an amine group NH.sub.2 which is bound to the elastomer R via the depicted spacer. This elastomer is reacted in the present example with guaiacol (a monophenol) and formaldehyde. At elevated temperatures, it reacts to a benzoxazine end-functionalized elastomer. Such a benzoxazine structure can further react as reinforcing agent in a rubber network. In particular, it can further react with other benzoxazines to form a reinforcing benzoxazine network.

[0098] In a further non-limiting embodiment, another benzoxazine-functionalized elastomer is manufactured as shown below:

##STR00011##

[0099] Thus, an elastomer having a polymer chain R (such as polybutadiene or a solution polymerized styrene-butadiene rubber) is again end-functionalized with an amine group (NH.sub.2) which is bound to the elastomer R via the depicted spacer (a propylene spacer in the reaction depicted above). This elastomer is reacted in the present example with bisphenol A and formaldehyde. After being heated to an elevated temperature, it reacts to a benzoxazine (end-) functionalized elastomer. In the present specific example, two polymer chains have been connected at their ends to a respective phenyl group of bisphenol A based benzoxazine. Such a benzoxazine structure can also react as reinforcing agent in a rubber network. In particular, it can further react with other benzoxazines to form a reinforcing benzoxazine network.

[0100] The above reaction is carried out in an inert organic solvent, such as a halogenated organic solvent (for example chloroform). However, as explained herein other inert solvents can also be utilized.

[0101] In the present example, the reaction was conducted at a temperature of 70° C. and the reaction was carried out for a period of about 48 hours.

[0102] In a preferred embodiment of this invention, the spacer starts with an atom directly bonded to the nitrogen atom of the benzoxazine ring (or ring structure) and ends with an atom directly bonded to a repeat unit of the polymer.

[0103] While the present embodiments suggest a specific spacer in combination with styrene butadiene rubber and polybutadiene, other spacers and polymers are possible within the scope of the present invention. Formaldehyde is a preferred but non-limiting example of an aldehyde derivative for a benzoxazine reaction in accordance with the present invention.

[0104] Variations in the present invention are possible in light of the description of it provided herein. While certain representative embodiments and details have been shown for the purpose of illustrating the subject invention, it will be apparent to those skilled in this art that various changes and modifications can be made therein without departing from the scope of the subject invention. It is, therefore, to be understood that changes can be made in the particular embodiments described which will be within the full intended scope of the invention as defined by the following appended claims.