USE OF A SILYLATED AROMATIC POLYPHENOL DERIVATIVE FOR THE PRODUCTION OF A PHENOL-ALDEHYDE RESIN FOR REINFORCEMENT OF A RUBBER COMPOSITION

Abstract

An aromatic polyphenol derivative comprising at least one aromatic ring bearing at least two OZ groups in the meta position relative to one another, the two positions ortho to at least one of the OZ groups being unsubstituted, is used for the manufacture of a phenol-aldehyde resin for reinforcing a rubber composition. Each OZ group represents an OSi(R.sub.1R.sub.2R.sub.3) group with R.sub.1, R.sub.2, R.sub.3 representing, independently of one another, a hydrocarbon-based radical or a substituted hydrocarbon-based radical.

Claims

1.-17. (canceled)

18. A method for the manufacture of a phenol-aldehyde resin for reinforcing a rubber composition comprising the step of: using an aromatic polyphenol derivative comprising at least one aromatic ring bearing at least two OZ groups in the meta position relative to one another, the two positions ortho to at least one of the OZ groups being unsubstituted, and in which each OZ group represents an OSi(R.sub.1R.sub.2R.sub.3) group with R.sub.1, R.sub.2, R.sub.3 representing, independently of one another, a hydrocarbon-based radical or a substituted hydrocarbon-based radical.

19. The method according to claim 18, wherein using the aromatic polyphenol derivative generates a delay phase during crosslinking of the phenol-aldehyde resin based on the aromatic polyphenol derivative and on an aldehyde.

20. The method according to claim 18, wherein using the aromatic polyphenol derivative in a phenol-aldehyde resin maintains stiffness of a rubber composition with an increase in temperature.

21. The method according to claim 19, wherein the aldehyde is an aromatic aldehyde.

22. The method according to claim 21, wherein the aromatic aldehyde is selected from the group consisting of 1,3-benzenedicarboxaldehyde, 1,4-benzenedicarboxaldehyde and an aldehyde of formula ##STR00025## in which comprises N, S or O; R represents H or CHO, and mixtures thereof.

23. The method according to claim 21, wherein the aromatic aldehyde is selected from the group consisting of 1,4-benzenedicarboxaldehyde, furfuraldehyde, 2,5-furandicarboxaldehyde and mixtures thereof.

24. The method according to claim 18, wherein each R.sub.1, R.sub.2, R.sub.3 group represents, independently of one another, a radical selected from the group consisting of alkyl, aryl, arylalkyl, alkylaryl, cycloalkyl and alkenyl radicals.

25. The method according to claim 18, wherein each R.sub.1, R.sub.2, R.sub.3 group represents, independently of one another, a radical selected from the group consisting of methyl, ethyl, propyl, phenyl, allyl and vinyl radicals.

26. The method according to claim 18, wherein each R.sub.1, R.sub.2, R.sub.3 group represents, independently of one another, a radical selected from the group consisting of methyl, ethyl, propyl, butyl, allyl and vinyl radicals.

27. The method according to claim 18, wherein the at least one aromatic ring bears three OZ groups in the meta position relative to one another.

28. The method according to claim 18, wherein the two positions ortho to each OZ group are unsubstituted.

29. The method according to claim 18, wherein the remainder of the at least one aromatic ring is unsubstituted.

30. The method according to claim 18, wherein the aromatic polyphenol derivative comprises several aromatic rings, at least two of these each bearing at least two OZ groups in the meta position relative to one another, the two positions ortho to at least one of the OZ groups of at least one aromatic ring being unsubstituted.

31. The method according to claim 18, wherein the, or each, aromatic ring is a benzene ring.

32. The method according to claim 18, wherein the aromatic polyphenol derivative is selected from the group consisting of the aromatic polyphenol derivatives (I), (II), (IV) and (V), and mixtures thereof: ##STR00026##

33. The method according to claim 18, wherein the aromatic polyphenol derivative is a pre-condensed resin based: on at least one aromatic polyphenol comprising at least one aromatic ring bearing at least two hydroxyl functions in the meta position relative to one another, the two positions ortho to at least one of the hydroxyl functions being unsubstituted; and on at least one compound comprising at least one aldehyde function, wherein the hydroxyl functions of the pre-condensed resin that remained reactive at the end of the condensation of the pre-condensed resin are substituted by OZ groups.

34. The method according to claim 33, wherein the compound comprising at least one aldehyde function is selected from the group consisting of formaldehyde, benzaldehyde, furfuraldehyde, 2,5-furandicarboxaldehyde, 1,4-benzenedicarboxaldehyde, 1,3-benzenedicarboxaldehyde, 1,2-benzenedicarboxaldehyde and mixtures thereof.

Description

EXEMPLARY EMBODIMENTS OF THE INVENTION AND COMPARATIVE TESTS

[0218] These tests demonstrate that:

[0219] the stiffness of the rubber composition comprising a phenol-aldehyde resin based on an aromatic polyphenol derivative according to the invention is greatly increased compared to a rubber composition devoid of reinforcing resin;

[0220] the stiffness of the rubber composition comprising a phenol-aldehyde resin based on an aromatic polyphenol derivative according to the invention may be improved compared to a rubber composition using a conventional reinforcing resin based on a methylene acceptor with HMT or H3M as methylene donor;

[0221] the stiffness retention of the rubber composition according to the invention at high temperatures, in particular for temperatures ranging up to 150 C., is greater than that of the rubber compositions devoid of reinforcing resin and equivalent to, or even greater than, in certain embodiments, that of the conventional rubber compositions that comprise HMT or H3M methylene donors;

[0222] there is a delay phase during the crosslinking of the phenol-aldehyde resin based on an aromatic polyphenol derivative according to the invention making it possible to avoid the premature crosslinking of the resin relative to a phenol-aldehyde resin crosslinked directly starting from the aromatic polyphenol and the aldehyde;

[0223] the phenol-aldehyde resin based on an aromatic polyphenol derivative according to the invention and on a preferentially aromatic aldehyde is devoid of formaldehyde and does not generate any formaldehyde during its formation.

[0224] For this purpose, several rubber compositions, denoted hereinafter T0, T1 and T2 and I1 to I3 were prepared as indicated above and are summarized in the appended Table 1 below.

[0225] All the compositions T0 to T2 and I1 to I3 have the following shared portion in their formulations (expressed in phr, parts by weight per hundred parts of elastomer): 100 phr of natural rubber, 75 phr of carbon black N326, 1.5 phr of N-(1,3-dimethylbutyl)-N-phenyl-para-phenylenediamine, 1.5 phr of stearic acid, 5 phr of ZnO, 1 phr of N-(tert-butyl)-2-benzothiazolesulfamide and 2.5 phr of insoluble sulfur 20H.

[0226] The composition T0 does not comprise any reinforcing resin added to this shared portion.

[0227] In addition to the shared portion, the composition T1 comprises a reinforcing resin based on hexamethylenetetramine (1.6 phr) and on a pre-condensed phenolic resin (4 phr). The composition T1 represents a conventional composition of the prior art, having greater stiffness than that of the composition T0.

[0228] In addition to the shared portion, the composition T2 comprises a phenol-aldehyde resin based on phloroglucinol and on 1,4-benzenedicarboxaldehyde. The composition T2 comprises 7 phr of phloroglucinol and 14 phr of 1,4-benzenedicarboxaldehyde.

[0229] In addition to the shared portion, each composition I1 to I3 comprises a phenol-aldehyde resin based on an aromatic polyphenol derivative according to the invention and on an aldehyde, preferably an aromatic aldehyde, which are indicated in Table 1 in 1 (aromatic polyphenol derivative according to the invention)/2 (aldehyde) molar proportions, and with, in each composition I1 to I3, I4 phr of the aldehyde.

[0230] Each aromatic polyphenol derivative according to the invention in each composition I1 to I3 comprises at least one aromatic ring bearing at least two OZ groups in the meta position relative to one another, the two positions ortho to at least one of the OZ groups being unsubstituted, and in which each OZ group represents an OSi(R.sub.1R.sub.2R.sub.3) group with R.sub.1, R.sub.2, R.sub.3 representing, independently of one another, a hydrocarbon-based radical or a substituted hydrocarbon-based radical.

[0231] Aromatic Polyphenol Derivatives of Compositions I1 to I3

[0232] Each aromatic polyphenol derivative according to the invention of the resin of each composition I1 to I3 is selected from the group consisting of the aromatic polyphenol derivatives of formulae (I), (II), (IV) and (V) described above and the mixtures of these aromatic polyphenol derivatives.

[0233] Each aromatic polyphenol derivative according to the invention of each composition I1 to I3 comprises a single aromatic ring, in this case a benzene ring, bearing three, and only three, OZ groups in the meta position relative to one another.

[0234] For the aromatic polyphenol derivatives according to the invention of each composition I1 to I3, the remainder of the aromatic ring is unsubstituted. In particular, the two positions ortho to each OZ group are unsubstituted. In the case in point, these are aromatic polyphenol derivatives of general formula (II) obtained from phloroglucinol.

[0235] Each aromatic polyphenol derivative according to the invention of each composition I1 to I3 has OZ groups that each represent an OSi(R.sub.1R.sub.2R.sub.3) group with R.sub.1, R.sub.2, R.sub.3 representing, independently of one another, a radical selected from the group consisting of alkyl, aryl, arylalkyl, alkylaryl, cycloalkyl and alkenyl radicals. Preferably, each R.sub.1, R.sub.2, R.sub.3 group represents, independently of one another, a radical selected from the group consisting of methyl, ethyl, propyl, phenyl, allyl and vinyl radicals and more preferentially still a radical selected from the group consisting of methyl, ethyl, propyl, butyl, allyl and vinyl radicals.

[0236] The aromatic polyphenol derivative according to the invention of composition I1 is such that R.sub.1R.sub.2R.sub.3CH.sub.3 and has the following formula (5):

##STR00021##

[0237] The aromatic polyphenol derivative (5) is prepared from phloroglucinol (CAS 108-73-6) and from trimethylsilyl chloride (CAS 75-77-4) (LG-Si(R.sub.1R.sub.2R.sub.3) with LG=Cl and R.sub.1R.sub.2R.sub.3=methyl) in the presence of an organic base. Thus, for example, 40 g of phloroglucinol are dissolved in 800 ml of chloroform. Next, 109 g of triethylamine are then added. Next, 107 g of trimethylsilyl chloride ClSi(CH.sub.3).sub.3 are added dropwise to the reaction medium at ambient temperature. Everything is left stirring at ambient temperature for 3 hours. Next, the reaction mixture is acidified with a 37% aqueous solution of hydrochloric acid. Next, it is washed twice with water. The final product is finally recovered after drying over anhydrous sodium sulfate, filtration and evaporation of the solvent. 150 g of the aromatic polyphenol derivative (5) are obtained in the form of a brown liquid. The .sup.1H NMR spectrum of the aromatic polyphenol derivative (5) is represented in FIG. 2A (.sup.1H NMR (CDCl.sub.3, 300 MHz): 6.03 (3H, s), 0.27 (27H, s)).

[0238] The aromatic polyphenol derivative of composition I2 is such that R.sub.1R.sub.2CH.sub.3, R.sub.3CHCH.sub.2 and has the following formula (6):

##STR00022##

[0239] The aromatic polyphenol derivative (6) is prepared in a similar manner to the aromatic polyphenol derivative (5) from phloroglucinol (CAS 108-73-6) and from dimethylvinylsilyl chloride (CAS 1719-58-0) (LG-Si(R.sub.1R.sub.2R.sub.3) with LG=Cl and R.sub.1R.sub.2=methyl and R.sub.3CHCH.sub.2). The .sup.1H NMR spectrum of the aromatic polyphenol derivative (6) is represented in FIG. 3A (.sup.1H NMR (CDCl.sub.3, 300 MHz): 6.15-5.60 (9H, m), 5.89 (3H, s), 0.15 (18H, s)).

[0240] The aromatic polyphenol derivative of composition I3 is such that R.sub.1CH.sub.3, R.sub.2R.sub.3C.sub.6H.sub.6 and has the following formula (7):

##STR00023##

[0241] The aromatic polyphenol derivative (7) is prepared in a similar manner to the aromatic polyphenol derivative (5) from phloroglucinol (CAS 108-73-6) and from methyldiphenylsilyl chloride (CAS 144-79-6) (LG-Si(R.sub.1R.sub.2R.sub.3) with LG=Cl and R.sub.1=methyl and R.sub.2R.sub.3C.sub.6H.sub.5). The .sup.1H NMR spectrum of the aromatic polyphenol derivative (7) is represented in FIG. 4A (.sup.1H NMR (CDCl.sub.3, 300 MHz): 7.70-7.30 (30H, m), 6.03 (3H, s), 0.59 (9H, s)).

[0242] Aldehyde of Compositions I1 to I3

[0243] Each aldehyde of each composition I1 to I3 is a preferentially aromatic aldehyde and is selected from the group consisting of 1,3-benzenedicarboxaldehyde, 1,4-benzenedicarboxaldehyde and an aldehyde of formula (A):

##STR00024##

in which:
X comprises N, S or O,
R represents H or CHO,
and the mixtures of these compounds.

[0244] In this case, the aldehyde is selected from the group consisting of 1,4-benzenedicarboxaldehyde, furfuraldehyde, 2,5-furandicarboxaldehyde and the mixtures of these compounds. Here, the aldehyde of each composition I1 to I3 is 1,4-benzenedicarboxaldehyde.

[0245] Comparative Tests

[0246] In a first step, the reinforcing filler was incorporated into an elastomer, everything being kneaded thermomechanically until a maximum temperature of between 110 C. and 190 C. was reached. Then the combined mixture was cooled to a temperature below 110 C. Next, during a second step, the crosslinking system, the phenol, the aromatic polyphenol or the aromatic polyphenol derivative according to the invention and the aldehyde were incorporated. At the end of this second step, the mixture was heated to 150 C. until the maximum rheometric torque was obtained in order to vulcanize the composition and crosslink the phenol-aldehyde resin. Next, the stiffness at 23 C. of the composition was characterized during a tensile test.

[0247] Characterization of the Delay Phase and of the Stiffness at High Temperature-Maximum Rheometric Torque

[0248] The measurements are carried out at 150 C. with an oscillating disc rheometer, according to standard DIN 53529-Part 3 (June 1983). The change in the rheometric torque as a function of the time describes the change in the stiffening of the composition following vulcanization and crosslinking of the phenol-aldehyde resin. From the change in the rheometric torque, the presence of a delay phase is determined when the increase in the rheometric torque, over 10 minutes, of the composition tested is lower than the increase in the rheometric torque, over 10 minutes, of a control composition comprising the corresponding aromatic polyphenol and the same aldehyde, here the composition T2. The presence of such a delay phase is indicated in Table 1. Each curve that represents the change in the rheometric torque respectively of compositions I1 to I3 and also those that represent the change in the rheometric torque of compositions T0, T1 and T2 have been represented in FIGS. 2B to 4B.

[0249] The higher the maximum rheometric torque Cmax, the more the composition has a stiffness which can be maintained at high temperature.

[0250] Characterization of the Stiffness at 23 C.Tensile Test

[0251] These tests make it possible to determine the elasticity stresses and the properties at break. Unless indicated otherwise, they are carried out in accordance with standard ASTM D 412, 1998 (test specimen C). The nominal secant moduli (or apparent stresses, in MPa) at 10% elongation (denoted MA10) are measured in second elongation (i.e., after an accommodation cycle). All these tensile measurements are carried out under normal temperature and relative humidity conditions, according to standard ASTM D 1349, 1999, and are reported in Table 1.

[0252] Firstly, the results from Table 1 show that the use of an aromatic polyphenol and of an aldehyde in the control composition T2 makes it possible to obtain a stiffness at 23 C. that is much higher than that of a composition devoid of reinforcing resin (T0) but also than that of a composition comprising a reinforcing resin of the prior art (T1). However, the composition T2 has no delay phase so that the phenol-aldehyde resin of the composition T2 crosslinks prematurely.

[0253] In addition to its delay phase, each composition according to the invention I1 to I3 has a stiffness at 23 C. that is equivalent to or even greater than that of the composition T1. Furthermore, unlike T1, none of the compositions I1 to I3 produces formaldehyde during the vulcanization thereof.

[0254] Each composition I1 to I3 has a delay phase and a stiffness which, although lower than that of the composition T2 in certain examples described, is sufficient to enable a reinforcement of the rubber composition. Moreover, this stiffness may be increased by modifying other parameters such as the contents of aromatic polyphenol derivative according to the invention and aldehyde used.

[0255] Each composition I1 to I3 has an improved stiffness retention at high temperatures (Cmax) compared to the retention of composition T0. Furthermore, the compositions I1 to I3 have a stiffness retention at high temperatures (Cmax) that is at least equal to (I2) or even significantly higher than (I1 and I3) that of the composition T1.

[0256] It will also be noted that the delay phase and the stiffness at 23 C. may be selected as a function of the application by varying the OZ group and in particular the R.sub.1, R.sub.2 and R.sub.3 groups.

[0257] The invention is not limited to the embodiments described above.

[0258] In other embodiments not present in Table 1, aromatic polyphenol derivatives comprising several aromatic rings, for example benzene rings, could be envisaged, at least two of these rings each bearing at least two OZ groups in the meta position relative to one another. The two positions ortho to at least one of the OZ groups of each aromatic ring are unsubstituted.

[0259] Use could be made of an aromatic polyphenol derivative comprising at least one aromatic ring bearing at least two OZ groups in the meta position relative to one another, the two positions ortho to at least one of the OZ groups being unsubstituted, and in which each OZ group represents an OSi(R.sub.1R.sub.2R.sub.3) group with R.sub.1, R.sub.2, R.sub.3 representing, independently of one another, a hydrocarbon-based radical or a substituted hydrocarbon-based radical by using it to generate a delay phase during the crosslinking of a phenol-aldehyde resin based on the aromatic polyphenol derivative and on an aldehyde, independently of the use thereof for the manufacture of a phenol-aldehyde resin for reinforcing a rubber composition.

[0260] The characteristics of the aromatic polyphenol derivative and of the aldehyde described above also apply to this use for generating a delay phase during the crosslinking of the phenol-aldehyde resin.

[0261] Use could be made, in certain embodiments, of an aromatic polyphenol derivative comprising at least one aromatic ring bearing at least two OZ groups in the meta position relative to one another, the two positions ortho to at least one of the OZ groups being unsubstituted, and in which each OZ group represents an OSi(R.sub.1R.sub.2R.sub.3) group with R.sub.1, R.sub.2, R.sub.3 representing, independently of one another, a hydrocarbon-based radical or a substituted hydrocarbon-based radical by using it in a phenol-aldehyde resin to maintain the stiffness of a rubber composition with the increase in the temperature, independently of the use thereof for the manufacture of a phenol-aldehyde resin for reinforcing a rubber composition.

[0262] The characteristics of the aromatic polyphenol derivative and of the aldehyde described above also apply to this use in a phenol-aldehyde resin for maintaining the stiffness of the rubber composition with the increase in the temperature.

TABLE-US-00001 TABLE 1 Delay MA10 Cmax Composition Phenol Methylene donor phase (MPa) (dN .Math. m) T0 / / / 7.4 16 T1 SRF resin (1) Hexamethylenetetramine (2) No 16.5 43 Delay MA10 Cmax Composition Aromatic polyphenol Aldehyde phase (MPa) (dN .Math. m) T2 Phloroglucinol (3) 1,4-Benzenedicarboxaldehyde (4) No 33.5 46 Aromatic polyphenol derivative Delay MA10 Cmax Composition ZSi(R.sub.1R.sub.2R.sub.3) Aldehyde phase (MPa) (dN .Math. m) I1 R.sub.1R.sub.2R.sub.3CH.sub.3 (5) 1,4-Benzenedicarboxaldehyde (4) Yes 24.9 65 I2 R.sub.1R.sub.2CH.sub.3, R.sub.3CHCH.sub.2 (6) 1,4-Benzenedicarboxaldehyde (4) Yes 23.8 43 I3 R.sub.1CH.sub.3,R.sub.2R.sub.3C.sub.6H.sub.5 (7) 1,4-Benzenedicarboxaldehyde (4) Yes 16.6 50 (1) Hexamethylenetetramine (from Sigma-Aldrich; purity of 99%); (2) Pre-condensed resin SRF 1524 (from Schenectady; diluted to 75%); (3) Phloroglucinol (from Alfa Aesar; purity of 99%); (4) 1,4-Benzenedicarboxaldehyde (from ABCR; purity of 98%).