RUBBER COMPOSITION AND A RUBBER PRODUCT

Abstract

The present invention is directed to a rubber composition comprising 100 phr of one or more diene-based elastomers, 30 phr to 200 phr of a filler, and a benzoxazine which is the reaction of (i) a diphenol comprising two phenol groups and a bridge covalently connecting the two phenol groups, (ii) an aldehyde derivative, and (iii) an amine, wherein the bridge is connected to at least one of the phenol groups at a meta position of said at least one phenol group. The present invention is also directed to a rubber product comprising such a rubber composition and the use of such rubber products in tire components.

Claims

1. A rubber composition comprising: 100 phr of one or more diene-based elastomers; 30 phr to 200 phr of a filler; and a benzoxazine which is the reaction product of (i) a diphenol comprising two phenol groups and a bridge covalently connecting the two phenol groups, (ii) an aldehyde derivative, and (iii) an amine, wherein the bridge is connected to at least one of the phenol groups at a meta position of said at least one phenol group.

2. The rubber composition of claim 1 wherein the amine is a primary amine.

3. The rubber composition of claim 2 wherein the primary amine is selected from a group of aromatic amines, aliphatic amines, cycloaliphatic amines, and heterocyclic amines.

4. The rubber composition of claim 2 wherein the primary amine is selected from the group of ethanolamine, allylamine, methylamine, ethylamine, propylamine, butylamine, isopropylamine, hexylamine, cyclohexylamine, 2-aminofluorene, aminophenyl acetylene, propargyl ether aniline, 4-aminobenzonitrile, furfurylamine, and aniline.

5. The rubber composition of claim 3 wherein the amine is an aliphatic amine which is comprised of a carbon chain having less than 18 carbon atoms.

6. The rubber composition of claim 1 wherein the aldehyde derivative is selected from a group of formaldehyde, paraformaldehyde, polyoxymethylene, and aldehydes having the formula RCHO, wherein R is a substituted or unsubstituted aliphatic alkyl group containing from 1 to 20 carbon atoms which can optionally contain heteroatoms.

7. The rubber composition of claim 1 wherein the bridge comprises one of an aromatic group, an aliphatic group, a cycloaliphatic group, a heterocyclic group, a hexafluoropropane group, a monosulfide, an oxygen group, a sulfone group, and a disulfide.

8. The rubber composition of claim 1 wherein the diphenol is selected from the group consisting of 3,4′-dihydroxydiphenyl disulfide and 3,3′-dihydroxydiphenyl disulfide.

9. The rubber composition of claim 1 wherein the benzoxazine has at least one of the following structures: ##STR00010## wherein R.sub.1 and R.sub.2 are selected from aromatic groups, aliphatic groups, cycloaliphatic groups and heterocyclic groups, and wherein R.sub.3 is an aromatic group, aliphatic group, cycloaliphatic group, heterocyclic group, hexafluoropropane, monosulfide, or disulfide.

10. The rubber composition of claim 9 wherein R.sub.1 and R.sub.2 are selected from the group consisting of allyl groups, methyl groups, ethyl groups, normal-propyl groups, isopropyl groups, hexyl groups, cyclohexyl groups, fluorine groups, phenyl acetylene groups, propargyl ether benzyl groups, benzonitrile groups, furfuryl groups, and benzyl groups.

11. The rubber composition of claim 9 wherein R.sub.3 is a disulfide.

12. The rubber composition of claim 1 wherein the rubber composition is a sulfur vulcanizable rubber composition comprising a sulfur donor.

13. The rubber composition of claim 1 wherein the filler is comprised of one or more members selected from the group consisting of silica, carbon black, aluminum hydroxide, ultra-high molecular weight polyethylene, and syndiotactic polybutadiene.

14. The rubber composition of claim 1 wherein the rubber composition is a sulfur vulcanizable rubber composition comprising less than 2 phr of a methylene donor and less than 5 phr of a methylene acceptor.

15. The rubber composition of claim 1 further comprising at least one second benzoxazine which is the reaction of a phenol and a primary amine.

16. The rubber composition of claim 15 wherein the second benzoxazine is one at least one member selected from the group consisting of monofunctional benzoxazine and a main-chain benzoxazine.

17. The rubber composition of claim 1 wherein the rubber composition comprises 5 phr to 40 phr of the benzoxazine.

18. A rubber product comprising the rubber composition of claim 1.

19. The rubber product of claim 18, wherein the rubber product is selected from the group consisting of tires, power transmission belts, hoses, tracks, air sleeves, and conveyor belts.

20. The rubber product of claim 18 wherein the rubber product is a tire, comprising one or more rubber components selected from a tread, a shearband, rubber spokes, an undertread, a sidewall, an apex, a flipper, a chipper, a chafer, a carcass, a belt, an overlay, wherein one or more of the rubber components comprise the rubber composition.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0067] The structure, operation, and advantages of the invention will become more apparent upon contemplation of the following description taken in conjunction with the accompanying drawings, wherein

[0068] FIG. 1 is a schematic cross section of a tire comprising a rubber component with the rubber composition in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0069] FIG. 1 is a schematic cross-section of a tire 1 according to an embodiment of the invention. The tire 1 has a plurality of tire components such as a tread 10, an innerliner 13, a belt comprising four belt plies 11, a carcass ply 9, two sidewalls 2, and two bead regions 3, 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 which are also considered as tire components. As shown in FIG. 1, the example tread 10 may have circumferential grooves 20, each groove 20 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. Moreover, the grooves 20, in particular the bottoms and/or sidewalls of the grooves 20 could be reinforced by a rubber compound having a higher hardness and/or stiffness than the remaining tread compound. Such a reinforcement may be referred to herein as a groove reinforcement.

[0070] 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 and further 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 a different number of grooves 20, e.g. less than four grooves.

[0071] One or more of the above tire components are made of a rubber composition in accordance with an embodiment of the present invention which comprises a benzoxazine which is the reaction product of (i) a diphenol comprising two phenol groups and a bridge covalently connecting the two phenol groups, (ii) an aldehyde derivative, and (iii) an amine, wherein the bridge is connected to at least one of the phenol groups at a meta position of said at least one phenol group.

[0072] In a first embodiment, such a rubber composition can comprise 3,3′-dihydroxy diphenyl disulfide-furfuryl amine having the following structure:

##STR00005##

[0073] In this molecule according to structure (I), a disulfide bridge is linking both phenyl groups at a meta position, leaving the respective para positions free.

[0074] In another preferred embodiment, the benzoxazine is 3,3′-dihydroxydiphenyl disulfide ethanol amine is as shown in below structure II:

##STR00006##

[0075] In structure II, the sulfur bridge is connected to the phenyl groups at the meta position as well.

[0076] In yet another embodiment, the benzoxazine is 3,3′-dihydroxydiphenyl disulfide aniline, as shown in below structure III:

##STR00007##

[0077] Multiple tests of the inventors have shown that 4,4′-benzoxazine configurations, providing the bridge at the para position of the phenyl groups, result in a weaker reinforcement than in the case of linking the bridge to at least one of the phenyl groups in meta position.

[0078] For instance, the inventors have also tested below structures (IV), (V) which are not in accordance with the present invention.

##STR00008##

[0079] Structure IV, not in accordance with the present invention, represents Bis (4-hydroxyphenyl disulfide furfuryl amine), in which a disulfide bridges both phenyl groups in para position.

##STR00009##

[0080] Above structure V, also not in accordance with the present invention, is bisphenol A furfuryl amine, in which a bridge (i.e. dimethyl methane) is coupled also in para position of the phenyl groups.

[0081] Table 1 below shows examples of diene-based rubber compositions having different reinforcement agents, including amongst others the structures I, II, II, IV, V. Control Sample 1 is essentially reinforced by carbon black only. Control Sample 2 is reinforced by carbon black and a reactive resin system including a phenolic resin and hexamethylenetetramine. Inventive Examples 1-3 are reinforced by 3,3′-dihydroxy diphenyl disulfide-furfuryl amine (also referred to as 3DPDS fa herein) corresponding to above shown structure I. In particular, Inventive Example 1 comprises 15 phr 3DPDS fa (which corresponds to an equimolar amount to the resin content in Control Sample 2), Inventive Example 2 comprises 10 phr 3DPDS fa and Inventive Example 3 comprises 20 phr 3DPDS fa.

TABLE-US-00001 TABLE 1 Parts by weight (phr) Control Control Inventive Inventive Inventive Sample Sample Example Example Example Material 1 2 1 2 3 Polyisoprene 100  100  100  100  100  Zinc Oxide 5 5 5 5 5 Sulfur   5.5   5.5   5.5   5.5   5.5 Stearic Acid 2 2 2 2 2 TDAE Oil 5 5 5 5 5 DCBS.sup.1 3 3 3 3 3 Benzoxazine 0 0 15  10  20  3DPDS fa.sup.2 Benzoxazine 0 0 0 0 0 3DPDS ea.sup.3 Benzoxazine 0 0 0 0 0 3DPDS a.sup.4 Benzoxazine 0 0 0 0 0 4DPDS fa.sup.5 Benzoxazine 0 0 0 0 0 BA fa.sup.6 Phenolic resin.sup.7 0 7 0 0 0 Carbon Black 80  80  80  80  80  HMTA.sup.8 0   1.5 0 0 0 .sup.1Sulfenamide Accelerator .sup.23,3′-dihydroxy diphenyl disulfide-furfuryl amine .sup.33,3′-dihydroxydiphenyl disulfide ethanol amine .sup.43,3′-dihydroxydiphenyl disulfide aniline .sup.5Bis (4-hydroxyphenyl disulfide furfuryl amine) .sup.6bisphenol A furfuryl amine .sup.7as Phenolic Novolac (TP), DUREZ 31459, SBHPP .sup.8Hexamethylenetetramine

[0082] Table 2 lists further Control Samples and Inventive Samples. In particular, Control Sample 3 is reinforced with bis (4-hydroxyphenyl disulfide furfuryl amine) which is also referred to herein as 4DPDS fa. This benzoxazine corresponds to above structure IV and has both phenyl groups bridged in para positions. Control Sample 4 is reinforced by bisphenol A furfuryl amine (mentioned herein also as BA fa) which is also comprising a bridge connected at para positions of the phenyl groups (see also structure V). In contrast, Inventive Examples 4 and 5 comprise benzoxazines bridged again at meta positions of the respective phenyl groups wherein Inventive Example 4 comprises 3′-dihydroxydiphenyl disulfide ethanol amine (3DPDS ea, also shown in structure II) and Inventive Example 5 comprises 3,3′-dihydroxydiphenyl disulfide ethanol aniline (3DPDS, as shown in structure III).

TABLE-US-00002 TABLE 2 Parts by weight (phr) Control Control Inventive Inventive Sample Sample Example Example Material 3 4 4 5 Polyisoprene 100  100  100  100  Zinc Oxide 5 5 5 5 Sulfur   5.5   5.5   5.5   5.5 Stearic Acid 2 2 2 2 TDAE Oil 5 5 5 5 DCBS.sup.1 3 3 3 3 Benzoxazine 0 0 0 0 3DPDS fa.sup.2 Benzoxazine 0 0 15  0 3DPDS ea.sup.3 Benzoxazine 0 0 0 15  3DPDS a.sup.4 Benzoxazine 15  0 0 0 4DPDS fa.sup.5 Benzoxazine 0 15  0 0 BA fa.sup.6 Phenolic resin.sup.7 0 0 0 0 Carbon Black 80  80  80  80  HMTA.sup.8 0 0 0 0 .sup.1Sulfenamide Accelerator .sup.23,3′-dihydroxy diphenyl disulfide-furfuryl amine .sup.33,3′-dihydroxydiphenyl disulfide ethanol amine .sup.43,3′-dihydroxydiphenyl disulfide aniline .sup.5Bis (4-hydroxyphenyl disulfide furfuryl amine) .sup.6bisphenol A furfuryl amine .sup.7as Phenolic Novolac (TP), DUREZ 31459, SBHPP .sup.8Hexamethylenetetramine

[0083] Table 3 shows measurements of the Young Modulus E, which is an indicator for the stiffness, for Controls Samples 1 to 4 and Inventive Examples 1 to 5 corresponding to the above Tables 1 and 2. Control Sample 1 having only a carbon black reinforcement has the lowest stiffness. Control Samples 3 and 4 reinforced with benzoxazines having phenyl groups coupled in para position show higher stiffness than control sample 1 but lower stiffness than (equimolar) reactive resin reinforced Control Sample 2. As further shown in Table 3, Inventive Examples 1 to 5 have each a higher stiffness than any Control Samples and are, for instance, considered as a valuable replacement for the reactive resin system of Control Sample 2. Young Modulus as shown in Table 3 was determined according to DIN 53504 on an INSTRON 5967 electro-mechanical testing machine using type S2 dumbbell specimens with 75 mm length. Young Modulus was determined up to 1.5% strain.

TABLE-US-00003 TABLE 3 Control Samples 1 to 4 Inventive Examples 1 to 5 Property 1 2 3 4 1 2 3 4 5 Young 0.3 0.6 0.5 0.5 0.8 0.7 1.0 0.8 1.0 Modulus E [MPa]

[0084] 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.