Tyre for vehicle wheels comprising a composite reinforcing filler

Abstract

The invention relates to a tyre (100) for vehicle wheels comprising at least one structural element comprising a vulcanized elastomeric material obtained by vulcanizing a vulcanizable elastomeric composition comprising at least one vulcanizable diene elastomeric polymer and at least one composite reinforcing filler, a process for producing a tyre (100) comprising the composite reinforcing filler, a masterbatch comprising the composite reinforcing filler and a process for producing the same, as well as a process for producing the composite reinforcing filler.

Claims

1. A tyre for vehicle wheels comprising at least one structural element comprising a vulcanized elastomeric material obtained by vulcanizing a vulcanizable elastomeric composition comprising: (a) at least one vulcanizable diene elastomeric polymer; and (b) at least one composite reinforcing filler comprising a core, and the core comprises nanocrystalline cellulose and an at least partial coating comprising silica.

2. The tyre according to claim 1, wherein the composite reinforcing filler has a core-shell structure, and the core-shell structure comprises a core comprising nanocrystalline cellulose and a shell comprising silica.

3. The tyre according to claim 1, wherein the composite reinforcing filler has a diameter ranging from 10 nm to 60 nm and a length ranging from 100 nm to 1000 nm.

4. The tyre according to claim 1, wherein the composite reinforcing filler has a degree of crystallinity ranging from 10% to 80%.

5. The tyre according to claim 1, wherein the composite reinforcing filler has a density ranging from 1.5 g/cm.sup.3 to 1.9 g/cm.sup.3.

6. The tyre according to claim 1, wherein the composite reinforcing filler has a BET total surface area ranging from 20 m.sup.2/g to 400 m.sup.2/g.

7. The tyre according to claim 1, wherein the composite reinforcing filler comprises from 20% to 80% by weight of silica with respect to the total weight of the composite reinforcing filler.

8. The tyre according to claim 1, wherein the vulcanizable elastomeric composition comprises from 0.1 phr to 40 phr of the composite reinforcing filler per 100 phr of vulcanizable diene elastomeric polymer.

9. The tyre according to claim 1, wherein the structural element is chosen from a tread band, a carcass structure, a belt structure, an underlayer, an anti-abrasive strip, a sidewall, a sidewall insert, a mini-sidewall, a flipper, a chafer, an underliner, rubber layers, a bead filling, and rubber sheets.

10. A process for producing a tyre for vehicle wheels, comprising: providing a vulcanizable elastomeric composition comprising: (a) at least one vulcanizable diene elastomeric polymer; and (b) at least one composite reinforcing filler comprising a core, and the core comprises nanocrystalline cellulose and an at least partial coating comprising silica; providing a tyre structural element comprising the vulcanizable elastomeric composition; assembling the tyre structural element in a green tyre; and vulcanizing the green tyre.

11. The process according to claim 10, wherein providing a vulcanizable elastomeric composition comprises: feeding to at least one mixing apparatus comprising at least one discontinuous mixer and at least one continuous mixer, or at least one discontinuous mixer or at least one continuous mixer:the at least one vulcanizable diene elastomeric polymer, and the at least one composite reinforcing filler; mixing and dispersing to obtain the vulcanizable elastomeric composition; and discharging the vulcanizable elastomeric composition from the at least one mixing apparatus.

12. The process according to claim 11, wherein the composite reinforcing filler is fed to the at least one mixing apparatus in the form of a masterbatch and the masterbatch comprises: at least one vulcanizable diene elastomeric polymer; and the composite reinforcing filler.

13. A masterbatch comprising: (a) at least one vulcanizable diene elastomeric polymer; and (b) at least one composite reinforcing filler comprising a core and the core comprises nanocrystalline cellulose and an at least partial coating comprising silica.

14. The masterbatch according to claim 13, wherein the composite reinforcing filler has a core-shell structure, and the core-shell structure comprises a core comprising nanocrystalline cellulose and a shell comprising silica..

15. The masterbatch according to claim 13, wherein the composite reinforcing filler is present in an amount from 5 phr to 120 phr per 100 phr of the vulcanizable diene elastomeric polymer.

16. A process for producing a masterbatch comprising: (a) at least one vulcanizable diene elastomeric polymer; and (b) at least one composite reinforcing filler comprising a core and the core comprises nanocrystalline cellulose and an at least partial coating comprising silica; wherein the process comprises: I. providing an aqueous dispersion of the composite reinforcing filler; II. adding, by mixing, the aqueous dispersion of step I. to a latex and the latex comprises the vulcanizable diene elastomeric polymer; III. coagulating the latex resulting from step II. to obtain a coagulated product comprising the composite reinforcing filler; and IV. purifying the coagulated product resulting from step III.

17. The process according to claim 16, wherein purifying the coagulated product comprises at least one operation chosen from filtering, washing, centrifuging, drying, and lyophilizing.

18. A process for producing a composite reinforcing filler comprising: (A). dispersing a nanocrystalline cellulose at a temperature ranging from 70° C. to 90° C. in an aqueous dispersing medium in the presence of at least one surfactant chosen from cationic surfactants and amphoteric surfactants to obtain an aqueous dispersion comprising nanocrystalline cellulose; (B). adding at least one silica precursor compound to the aqueous dispersion resulting from step (A); (C). depositing an at least partial coating of silica on the nanocrystalline cellulose by hydrolyzing the silica precursor compound to obtain a composite reinforcing filler comprising a core and the core comprises nanocrystalline cellulose and an at least partial coating comprising silica; and (D). purifying the composite reinforcing filler resulting from step (C).

19. The process according to claim 18, wherein the surfactant is chosen from benzalkonium chloride, cetrimonium chloride, hexadecyltrimethylammonium bromide, undecyl amido propyl trimethylammonium metasulphate, and coco alkyl trimethylammonium metasulphate.

20. The process according to claim 18, wherein the surfactant is added in an amount ranging from 10% to 20%, by weight with respect to the weight of the nanocrystalline cellulose.

21. The process according to claim 18, wherein the silica precursor compound is chosen from: I. alkaline silicates of the formula:
M.sub.2O.Math.n(SiO.sub.2)   (I) wherein M is chosen from Na, K, and Li and wherein n is ranging from 0.5 to 4, II. tetra-alkyl derivatives of silicic acid of the formula
(RO).sub.4Si   (II) wherein the R groups are the same or different from each other and represent C.sub.1-C.sub.6 alkyls, and III. halosilanes of the formula
SiX.sub.4, (RO).sub.3SiX, (RO).sub.2SiX.sub.2, or (RO)SiX.sub.3   (III) wherein the R groups are the same or different from each other and are chosen from C.sub.1-C.sub.6 alkyls, and X are the same or different from each other and are chosen from chlorine, bromine, and iodine.

22. The process according to claim 21, wherein the silica precursor compound is an alkaline silicate.

23. The process according to claim 22, wherein in step (B) the addition is carried out while keeping the aqueous dispersion in a basic medium and at a temperature ranging from 70° C. to 90° C.

24. The process according to claim 22, wherein the amount of alkaline silicate ranges from 50% to 150%, by weight with respect to the weight of the nanocrystalline cellulose.

25. The process according to claim 22, wherein step (B) further comprises adding at least one acid chosen from hydrochloric acid, phosphoric acid, nitric acid, sulphuric acid, acetic acid, and carbonic acid.

26. The process according to claim 22, wherein step (B) comprises: (B1) adding at least one first portion of alkaline silicate to the aqueous dispersion resulting from step (A), while keeping the aqueous dispersion at a pH ranging from 8.5 to 9.5; (B2) stirring the aqueous dispersion resulting from step (B1) for a time ranging from 80 minutes to 100 minutes; and (B3) adding at least one second portion of alkaline silicate to the aqueous dispersion resulting from step (B2), while keeping the aqueous dispersion at a pH ranging from 7 to 8.

27. The process according to claim 22, wherein step (C) of depositing an at least partial coating of silica on the nanocrystalline cellulose comprises hydrolyzing the alkaline silicate in the aqueous dispersion resulting from step (B) in an acidic medium to hydrolyze the alkaline silicate (I) and obtaining a composite reinforcing filler that comprises a core comprising nanocrystalline cellulose and an at least partial coating comprising silica.

28. The process according to claim 22, wherein step (C) comprises adding at least one acid chosen from hydrochloric acid, phosphoric acid, nitric acid, sulphuric acid, acetic acid, and carbonic acid.

29. The process according to claim 18, wherein purifying the composite reinforcing filler comprises at least one operation chosen from filtering, washing, centrifuging, drying, lyophilizing, and any combination thereof.

30. The process according to claim 18, wherein the composite reinforcing filler resulting from step (C) has a core-shell structure, and the core-shell structure comprises a core comprising nanocrystalline cellulose and a shell comprising silica.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) Additional features and advantages of the invention will become clearer from the following description of some preferred embodiments thereof, made hereinafter, for illustrating and not limiting purposes, with reference to the attached drawings.

(2) In the drawings:

(3) FIG. 1 illustrates a radial half-section of a tyre for vehicle wheels according to the invention;

(4) FIG. 2 illustrates a photograph carried out with a field emission scanning electron microscope (FESEM), obtained with an ULTRA PLUS instrument with Gemini lens by ZEISS, in which it is possible to see the composite reinforcing filler (b) according to Example 1. At the bottom, a reference scale is shown which allows to appreciate the dimensions of the composite reinforcing filler (b).

DETAILED DESCRIPTION OF THE CURRENTLY PREFERRED EMBODIMENTS

(5) A tyre for vehicle wheels according to a preferred embodiment of the invention is generally indicated with reference numeral 100 in FIG. 1.

(6) FIG. 1 illustrates a radial half-section of a tyre for vehicle wheels.

(7) In FIG. 1 “a” indicates an axial direction and “X” indicates a radial direction, in particular X-X indicates the line of the equatorial plane. For the sake of simplicity, FIG. 1 shows only a portion of the tyre, the remaining unrepresented portion being identical and symmetrically arranged with respect to the equatorial plane “X-X”.

(8) The tyre 100 for vehicles comprises at least one carcass structure, comprising at least one carcass layer 101 having respectively opposite end flaps engaged with respective annular anchoring structures 102, called bead cores, possibly associated to a bead filler 104.

(9) The zone of the tyre comprising the bead core 102 and the filler 104 forms a bead structure 103 intended for anchoring the tyre on a corresponding mounting rim, not illustrated.

(10) The carcass structure is usually of the radial type, i.e. the reinforcing elements of the at least one carcass layer 101 are on planes comprising the rotation axis of the tyre and substantially perpendicular to the equatorial plane of the tyre. Said reinforcing elements generally consist of textile cords, for example rayon, nylon, polyester (for example polyethylene naphthalate, PEN). Each bead structure is associated to the carcass structure by folding back of the opposite lateral edges of the at least one carcass layer 101 around the annular anchoring structure 102 so as to form the so-called flaps of the carcass 101a as illustrated in FIG. 1.

(11) In an embodiment, the coupling between the carcass structure and the bead structure can be provided by a second carcass layer (not shown in FIG. 1) applied at an axially outer position with respect to the first carcass layer.

(12) An anti-abrasive strip 105 is arranged at an outer position of each bead structure 103.

(13) The carcass structure is associated to a belt structure 106 comprising one or more belt layers 106a, 106b radially superimposed on one another and with respect to the carcass layer, having typically textile and/or metallic reinforcing cords incorporated in a layer of vulcanized elastomeric material.

(14) Such reinforcing cords can have a crossed orientation with respect to a direction of circumferential development of the tyre 100. The term “circumferential” direction is used to indicate a direction generally facing the direction of rotation of the tyre.

(15) At a radially outermost position with respect to the belt layers 106a,106b, at least one zero degrees reinforcing layer 106c may be applied, commonly known as “0° belt”, which generally incorporates a plurality of elongated reinforcement elements, typically metallic or textile cords, oriented along a substantially circumferential direction, thus forming an angle of a few degrees (for example an angle between about 0° and 6°) with respect to a direction parallel to the equatorial plane of the tyre, and coated with a vulcanized elastomeric material.

(16) At a radially outer position with respect to the belt structure 106, a tread band 109 made of vulcanized elastomeric material is applied.

(17) On the lateral surfaces of the carcass structure, each extending from one of the lateral edges of the tread band 109 up to the respective bead structure 103, respective sidewalls 108 made of vulcanized elastomeric material are also applied at an axially outer position.

(18) At a radially outer position, the tread band 109 has a rolling surface 109a intended to contact the ground. Circumferential grooves, which are connected by transversal notches (not shown in FIG. 1) so as to define a plurality of blocks of various shapes and sizes distributed on the rolling surface 109a, are generally formed in this surface 109a, which for the sake of simplicity in FIG. 1 is represented smooth.

(19) An underlayer 111 made of vulcanized elastomeric material can be arranged between the belt structure 106 and the tread band 109.

(20) A strip 110 of vulcanized elastomeric material, commonly known as “mini-sidewall”, can possibly be present in the connection zone between the sidewalls 108 and the tread band 109.

(21) This mini-sidewall 110 is generally obtained by co-extrusion with the tread band 109 and advantageously allows an improvement of the mechanical interaction between the tread band 109 and the sidewalls 108.

(22) Preferably, the end portion of the sidewall 108 (in the preferred embodiment illustrated in FIG. 1, of the mini-sidewall 110) directly covers the lateral edge of the tread band 109.

(23) In the case of tyres without an air chamber, a rubber layer 112, generally known as “liner”, which provides the necessary tightness to the inflation air of the tyre, can also be provided at a radially inner position with respect to the carcass layer 101.

(24) Between the rubber layer 112 and the carcass layer 101 it is also possible to arrange a further rubber sheet of vulcanized elastomeric material, not illustrated, also known with the name of “underliner”.

(25) The stiffness of the tyre sidewall 108 can be improved by providing the bead structure 103 with a reinforcing layer 120 generally known as “flipper” or additional strip-shaped insert.

(26) The flipper 120 is a reinforcing layer that is wound around the respective bead core 102 and the bead filling 104 so as to at least partially surround them, said reinforcing layer being arranged between the at least one carcass layer 101 and the bead structure 103.

(27) Preferably, the flipper is in contact with the aforementioned at least one carcass layer 101 and with the bead structure 103.

(28) The flipper 120 typically comprises a plurality of textile cords incorporated in a layer of vulcanized elastomeric material.

(29) The tyre bead structure 103 can comprise an additional protective layer 121, generally known with the term of “chafer” or protective strip, and which has the function of increasing the stiffness and integrity of the bead structure 103.

(30) Preferably, the protective layer 121 or “chafer” comprises a plurality of cords incorporated in a layer of vulcanized elastomeric material. Such cords can be made of textile materials (for example aramid or rayon) or of metallic materials (for example steel cords).

(31) A layer or rubber sheet of elastomeric material, not shown, can be arranged between the belt structure 106 and the carcass structure. The layer can have a uniform thickness.

(32) Alternatively, the layer can have a variable thickness along the axial direction. For example, the layer can have a greater thickness close to its axially outer edges with respect to the central (crown) zone.

(33) Advantageously, the layer or rubber sheet can extend over a surface substantially corresponding to the development surface of the belt structure 106.

(34) In a preferred embodiment, a layer or rubber sheet of elastomeric material as described above, not shown, can be arranged—alternatively or additionally to the underlayer 111—between the belt structure 106 and the tread band 109, said additional layer or rubber sheet preferably extending over a surface substantially corresponding to the development surface of the belt structure 106.

(35) The vulcanized elastomeric material obtained by vulcanizing the vulcanizable elastomeric composition comprising the composite reinforcing filler (b) according to the present invention can be advantageously incorporated in one or more of the structural elements of the tyre 100 described above.

(36) Preferably, the structural element of the tyre 100 obtained by vulcanizing the vulcanizable elastomeric composition comprising the composite reinforcing filler (b) according to the present invention can be one or more among the tread band 109, carcass structure, belt structure 106, underlayer 111, antiabrasive strip 105, sidewall 108, sidewall insert, mini-sidewall 110, flipper 120, chafer 121, underliner, rubber layers, bead filling 104 and rubber sheets of vulcanized elastomeric material.

(37) According to an embodiment which is not shown, the tyre can be a tyre for motorcycle wheels that is typically a tyre that has a cross section distinguished by a high transversal curvature.

(38) According to an embodiment which is not shown, the tyre can be a tyre for wheels for heavy transportation vehicles, such as trucks, buses, trailers, vans, and in general for vehicles in which the tyre is subjected to a high load.

(39) Preferably, such a tyre is suitable for being mounted on rims having a diameter equal to or greater than 17.5 inches for steering or trailer wheels.

(40) The invention is now illustrated by some Examples intended for illustrative and non-limiting purposes thereof.

Example 1

(41) Preparation of a Composite Reinforcing Filler

(42) Materials

(43) Nanocrystalline cellulose (aqueous dispersion at 12% by weight—commercialized by CelluloseLab—Canada) having a diameter ranging from 5 to 20 nm and a length ranging from 150 to 200 nm, density of 1.5 g/cm.sup.3, surface area of 1.45 m.sup.2/g, crystallinity degree of 70-90%);

(44) Hexadecyltrimethylammonium bromide (CTAB) (Sigma-Aldrich);

(45) Silica: Ultrasil VN3;

(46) NaOH at 98% (Sigma);

(47) Sulfuric acid (aqueous solution at 15% by weight) (obtained by dilution by the product of Sigma-Aldrich, 98%).

(48) Procedure

(49) In a laboratory flask, 7 g of silica and 2.8 g of NaOH were mixed in 60 ml of distilled water and kept under agitation at 300 rpm at 80° C. for 1 hour, obtaining a clear solution of sodium silicate, which was then brought to a final volume of 90 ml by adding further distilled water.

(50) Thereafter, in a three-necked laboratory flask 42 g of the aqueous dispersion of nanocrystalline cellulose (corresponding to 5 g of nanocrystalline cellulose) and 0.8 g of CTAB were added in 450 ml of distilled water and kept under agitation for 30 minutes at about 80° C., so as to form an aqueous dispersion of nanocrystalline cellulose.

(51) Always keeping the system at a temperature of about 80° C., the aqueous dispersion of nanocrystalline cellulose was added with a first portion of 60 ml of the sodium silicate solution over about 90 minutes. During the addition of the sodium silicate solution, sulfuric acid was also added, so as to keep the pH at a value of about 9.3.

(52) Once the addition of the first portion of sodium silicate ended, the reaction mixture was kept under agitation for additional 15 minutes at about 80° C. and, thereafter, sulfuric acid was added over 10 minutes, until a pH of about 7.5 was attained, always keeping the temperature at about 80° C.

(53) Then, a second portion of 30 ml of the sodium silicate solution was added over about 45 minutes to the aqueous dispersion thus obtained, keeping the system at the temperature of about 80° C. and at a pH value of about 7.4, by adding sulfuric acid.

(54) Once the addition of sodium silicate solution ended, the pH was brought to a value of 4 over 20 minutes by adding further sulfuric acid and by keeping the reaction mixture always at about 80° C., so as to deposit a silica coating on the nanocrystalline cellulose, thereby obtaining about 11 g of a composite reinforcing filler. The composite reinforcing filler thus obtained was then purified by means of centrifuging (1000-3000 g for 10-20 minutes), followed by washing with distilled water and lyophilization (24 hours) and subsequently characterized. Table 1 shows the characteristics of the composite reinforcing filler. FIG. 2 also shows an electron scanning microscope photograph of the composite reinforcing filler obtained.

Example 2

(55) Preparation of a Composite Reinforcing Filler

(56) Materials

(57) Nanocrystalline cellulose (aqueous dispersion at 12% by weight—commercialized by CelluloseLab—Canada) having a diameter ranging from 5 to 20 nm and a length ranging from 150 to 200 nm, density of 1.5 g/cm.sup.3, surface area of 1.45 m.sup.2/g, crystallinity degree of 70-90%);

(58) Hexadecyltrimethylammonium bromide (CTAB) (Sigma-Aldrich);

(59) Silica: Ultrasil VN3;

(60) NaOH at 98% (Sigma);

(61) Sulfuric acid: (aqueous solution at 15% by weight) (obtained by dilution by the product of Sigma-Aldrich, 98%).

(62) Procedure

(63) In a laboratory flask, 7 g of silica and 2.8 g of NaOH were mixed in 60 ml of distilled water and kept under agitation at 300 rpm at 80° C. for 1 hour, obtaining a clear solution of sodium silicate, which was then brought to a final volume of 100 ml by adding further distilled water.

(64) Thereafter, in a three-necked laboratory flask 42 g of the aqueous dispersion of nanocrystalline cellulose (corresponding to 5 g of nanocrystalline cellulose) and 0.8 g of CTAB were added in 450 ml of distilled water and kept under agitation for 30 minutes at about 80° C., so as to form an aqueous dispersion of nanocrystalline cellulose.

(65) While keeping the system at a temperature of about 80° C., the sodium silicate solution was then added to the aqueous dispersion of nanocrystalline cellulose over about 80 minutes. During the addition of the sodium silicate solution, sulfuric acid was also added, so as to keep the pH at a value of about 9.3.

(66) Once the addition of sodium silicate had ended, the reaction mixture was kept under agitation for additional 15 minutes at about 80° C. and, subsequently, the pH was brought to a value of 4 over 20 minutes by adding further sulfuric acid and while keeping the reaction mixture at about 80° C., so as to hydrolyze the sodium silicate and deposit a silica coating on the nanocrystalline cellulose, thus obtaining about 11 g of a composite reinforcing filler. The composite reinforcing filler thus obtained was then purified by means of centrifuging (2000-3000 g for 10-20 minutes), followed by washing with distilled water and lyophilization (24 hours) and subsequently characterized. Table 1 shows the characteristics of the composite reinforcing filler.

(67) TABLE-US-00001 TABLE 1 Composite reinforcing Composite reinforcing filler according to filler according to Example 1 Example 2 Length (nm) 110-220 110-220 Diameter (nm) 10-30 10-30 % silica (by weight) 57.02 56.39 Density (g/cm.sup.3) 1.8 1.8 Surface area (m.sup.2/g) 87.28 99.18 Crystallinity degree (%) 40% 40%

Example 3

(68) Preparation of Natural Rubber Masterbatches Comprising 20 Phr, 30 Phr and 40 Phr of Composite Reinforcing Fillers According to Examples 1 and 2

(69) Materials

(70) Composite reinforcing filler according to Example 1;

(71) Composite reinforcing filler according to Example 2;

(72) Natural rubber latex HA obtained by centrifuging and stabilized with ammonia (60% by weight—commercialized by Von Bundit Co. Ltd);

(73) Acetic acid (99%—Sigma).

(74) Procedure

(75) For the preparation of all of the masterbatches the same following procedure was followed, changing exclusively the amount of composite reinforcing filler incorporated in the masterbatch.

(76) For the preparation of the masterbatch comprising 20 phr of composite reinforcing filler, about 6.6 grams of the latter were suspended in 250 ml of distilled water, thus forming an aqueous dispersion of the composite reinforcing filler.

(77) The 250 ml of aqueous dispersion of the composite reinforcing filler were mixed in a container provided with a magnetic stirrer with 55 grams of natural rubber latex at 300 rpm for about 30 minutes at 25° C. Subsequently, acetic acid was added so as to bring the pH of the mixture below the value of 4 and coagulate the latex, so as to obtain a coagulated product comprising the composite reinforcing filler. The coagulated product was then purified by means of vacuum filtration, washed with distilled water to eliminate the excess acetic acid up to a pH of about 6 of the washing water and dried under vacuum at 45° C. up to constant weight.

(78) For the preparation of the masterbatches at 30 phr and 40 phr the same procedure was followed, respectively using 9.9 and 13.2 grams of composite reinforcing filler for the preparation of the aqueous dispersion.

Example 4

(79) Preparation of Vulcanizable Elastomeric Materials Comprising the Two Masterbatches According to Example 3 and of Two Vulcanizable Elastomeric Materials Comprising Silica (Comparison)

(80) The masterbatches comprising the composite reinforcing fillers according to Examples 1 and 2 were used to produce vulcanizable elastomeric materials for tyre components in amounts of 20 phr and 30 phr, materials (C) and (D) and materials (E) and (F) respectively. These elastomeric materials were compared with conventional elastomeric materials comprising conventional silica, materials (A) and (B). The elastomeric materials of these examples are based on model elastomeric compositions for tyre structural elements. Therefore, the results showed by these materials are predictive of those that can be obtained in a tyre.

(81) The following Table 2 shows the compositions in phr of the vulcanizable elastomeric materials (A), (B), (C), (D), (E) and (F).

(82) TABLE-US-00002 TABLE 2 (A) (B) (C) (D) (E) (F) compar- compar- inven- inven- inven- inven- ison ison tion tion tion tion NR 100 100 0 0 0 0 Silica 20 30 0 0 0 0 MASTER 1 0 0 120 0 0 0 MASTER 2 0 0 0 120 0 0 MASTER 3 0 0 0 0 130 0 MASTER 4 0 0 0 0 0 130 TESPT 2 2 2 2 2 2 CB N234 2 2 2 2 2 2 Soluble 2 2 2 2 2 2 Sulfur ZnO 5 5 5 5 5 5 Stearic 2 2 2 2 2 2 Acid CBS 2 2 2 2 2 2 TMQ 1 1 1 1 1 1 6 PPD 1.5 1.5 1.5 1.5 1.5 1.5
Materials

(83) MASTER 1: Natural rubber masterbatch prepared according to Example 3 comprising 20 phr of composite reinforcing filler according to Example 1;

(84) MASTER 2: Natural rubber masterbatch prepared according to Example 3 comprising 20 phr of composite reinforcing filler according to Example 2;

(85) MASTER 3: Natural rubber masterbatch prepared according to Example 3 comprising 30 phr of composite reinforcing filler according to Example 1;

(86) MASTER 4: Natural rubber masterbatch prepared according to Example 3 comprising 30 phr of composite reinforcing filler according to Example 2;

(87) NR: coagulated natural rubber, obtained by coagulation of natural rubber latex HA obtained by centrifuging and stabilized with ammonia (60% by weight—commercialized by Von Bundit Co. Ltd);

(88) Silica: Silica Ultrasil VN3, Ege Kymia;

(89) TESPT: bis(3-triethoxysilylpropyl) tetrasulfide, Si69®;

(90) CB: Carbon black N234, Cabot;

(91) Soluble Sulfur: S8 (soluble sulfur), Zolfo Industria;

(92) ZnO: Zinc Oxide, Zincol Ossidi;

(93) Stearic acid: Stearin TP8, Undesa;

(94) CBS: N-cyclohexyl-2-benzothiazolesulfenamide (Vulkacit CZ/C), Lanxess;

(95) TMQ: polymerized 2,2,4-trimethyl-1,2 dihydroquinoline, Kemai;

(96) 6PPD: N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine, Solutia Eastman.

(97) Procedure

(98) All of the components, with the exception of sulfur and the vulcanization accelerator (CBS) were mixed in an internal mixer (Brabender) for about 10 minutes (1st step).

(99) When the temperature of 135° C. was reached, the material was mixed for another minute and then was discharged. The incomplete compound was left to rest for one day and then sulfur and the accelerator (CBS) were added and the mixing was carried out in the same mixer at about 60° C. for 9 minutes (2nd step).

Example 5

(100) Characterization of the Vulcanizable Elastomeric Materials (A), (B), (C), (D), (E) and (F) after Vulcanization

(101) The vulcanizable elastomeric materials (A), (B), (C), (D), (E) and (F) were vulcanized at 151° C. for a time corresponding to the optimal value of the kinetic vulcanization curve, in order to measure the static mechanical and density properties thereof.

(102) As far as the static mechanical properties are concerned, tensile tests were in particular carried out according to the standard ISO 37-2011 at 23° C., on 5 Dumbbell specimens, measuring the tensile strength (TS), the elongation at break (Eb) and the elastic modulus at elongations of 10%, 50%, 100%, 300% (M10, M50, M100 and M300 respectively) and reporting the median value.

(103) As far as the density measurement is concerned, this was carried out on the compounds with the procedure ISO 2781, Method A, using water as reference liquid.

(104) Furthermore, the dynamic mechanical properties and the vulcanization properties of the vulcanizable elastomeric materials (A), (B), (C), (D), (E) and (F) were evaluated using a rheometer Monsanto R.P.A. 2000 according to the following method: cylindrical test samples with weights in the range from 4.5 to 5.5 g were obtained by punching the vulcanizable elastomeric composition of samples (A), (B), (C), (D), (E) and (F). The samples were vulcanized in the instrument “RPA” at 170° C. for 10 minutes and were subjected to measurement of the dynamic elastic shear modulus with a deformation amplitude of 3% (G′ (3%)) at 70° C./frequency 10 Hz, and of Tan delta with a deformation amplitude of 3% (Tan Delta (3%)) at 70° C./frequency 10 Hz. As far as the vulcanization properties are concerned, the minimum torque (ML), the maximum torque (MH), as well as the vulcanization time necessary to reach 30% and 90% of the maximum torque (T30 and T90 respectively) were measured.

(105) The following Table 3 shows the results obtained from the characterizations carried out.

(106) TABLE-US-00003 TABLE 3 (A) (B) (C) (D) (E) (F) compar- compar- inven- inven- inven- inven- ison ison tion tion tion tion Density 1.058 1.083 1.050 1.046 1.064 1.079 (g/cm.sup.3) Vulcani- 25 25 15 15 15 15 zation time at 151° C. (minutes) M10 0.32 0.35 0.38 0.4 0.49 0.52 (MPa) M50 0.94 0.94 1.14 1.23 1.30 1.55 (MPa) M100 1.6 1.53 2.14 2.27 2.33 3.02 (MPa) M300 7.77 7.65 9.98 9.61 10.6 13.78 (MPa) TS (MPa) 20.37 27.21 25.47 25.48 26.61 26.04 Eb (%) 486.89 564.92 535.3 534.94 538 487.78 ML (dNm) 0.81 1.6 0.69 0.71 1.18 1.36 MH (dNm) 11.83 12.3 12.15 13.38 12.31 13.63 T30 1.65 2.29 1.31 1.33 1.09 1.18 (minutes) T90 3.01 3.32 2 2.17 1.91 1.97 (minutes) G′ (3%) 0.69 0.78 0.73 0.81 0.88 0.92 (MPa) Tan Delta 0.064 0.075 0.089 0.086 0.107 0.095 (3%)

(107) From the analysis of the data given in Table 3 it clearly appears how the vulcanizable elastomeric materials (C) and (D) according to the present invention, whilst comprising only 20 phr of composite reinforcing filler according to the present invention, show static and dynamic mechanical properties significantly greater than those of the vulcanizable elastomeric material (A), which comprises the same amount of reinforcing filler and totally comparable to those of the vulcanizable elastomeric material (B), which on the other hand contains 30 phr of silica-based reinforcing filler, i.e. an amount greater than 50% of reinforcing filler with respect to the vulcanizable elastomeric materials (C) and (D). This shows the greater reinforcing properties of the composite reinforcing filler according to the present invention with respect to silica.

(108) Furthermore, as far as the elastomeric materials (E) and (F) are concerned, comprising 30 phr of composite reinforcing filler, it is possible to note that by increasing the content of composite reinforcing filler it is possible to obtain values of dynamic elastic shear modulus G′ and of Tan Delta, predictive of an improvement of maneuverability at high speed and in limit driving conditions, typical of high-performance tyres, for example HP and UHP tyres.

(109) In addition, it clearly appears that the vulcanizable elastomeric materials (C) and (D) have a lower density with respect to the vulcanizable elastomeric material (A) and even more lower with respect to the vulcanizable elastomeric material (B). Therefore, the data given above highlight how the vulcanizable elastomeric materials (C) and (D) allow to produce significantly lighter elastomeric materials with the same performance.

(110) Similarly, the vulcanizable elastomeric materials (E) and (F) show a lower density with respect to the vulcanizable elastomeric material (B), which comprises the same amount of filler, also in this case demonstrating an improved performance of the composite reinforcing filler according to the present invention with respect to conventional silica-based fillers, an improved performance which allows to produce significantly lighter elastomeric materials.

(111) Finally, it appears how the vulcanization behavior of the vulcanizable elastomeric materials (C), (D), (E) and (F) is analogous in terms of maximum torque MH and better in terms of vulcanization kinetics with respect to the vulcanizable elastomeric materials (A) and (B).

(112) The ML data predictive of the viscosity of the compound also indicates that this is lower for the same filler quantity.

(113) From the data given above it therefore ensues that the vulcanizable elastomeric materials (C), (D), (E) and (F) are substantially workable with improved energy costs with respect to those of the vulcanizable elastomeric materials (A) and (B), and show significantly higher vulcanization kinetics with respect to the latter, to the benefit of the productivity of the processes in which they are used.

Example 6

(114) Preparation of a SBR Masterbatch Comprising 20 Phr of the Composite Reinforcing Filler According to Example 2

(115) Materials

(116) Composite reinforcing filler according to Example 2;

(117) SBR latex in emulsion (solid content 66% by weight, Europrene Latice E-5570, Versalis);

(118) Acetic acid (99%—Sigma).

(119) Procedure

(120) For the preparation of the masterbatch the following procedure was followed.

(121) About 6.6 grams of the composite reinforcing filler were suspended in 250 ml of distilled water, thus forming an aqueous dispersion of the composite reinforcing filler.

(122) The 250 ml of aqueous dispersion of the composite reinforcing filler were mixed in a container provided with a magnetic stirrer with 50 grams of SBR latex at 300 rpm for about 30 minutes at 25° C. Thereafter, acetic acid was added so as to bring the pH of the mixture to a value below 4 and to coagulate the latex, so as to obtain a coagulated product comprising the composite reinforcing filler. The coagulated product was then purified by means of vacuum filtration, washed with distilled water to eliminate the excess acetic acid until a pH value of about 6 of the washing waters was obtained and dried under vacuum at 45° C. until constant weight.

Example 7

(123) Preparation of a Vulcanizable Elastomeric Material Comprising the Masterbatch According to Example 6 and of Three Vulcanizable Elastomeric Materials Comprising Silica (Comparison)

(124) The masterbatch according to example 6 was used to produce a vulcanizable elastomeric material for tyre components in an amount of 20 phr, material (L). This elastomeric material was compared with conventional elastomeric materials comprising 20 phr, 30 phr and 40 phr of silica, materials (G), (H) and (I) respectively. The elastomeric materials of these examples are based on model elastomeric compositions for tyre structural elements. Therefore, the results shown by these materials are predictive of those that can be obtained in a tyre.

(125) The following Table 4 shows the compositions in phr of the materials.

(126) TABLE-US-00004 TABLE 4 (G) (H) (I) (L) comparison comparison comparison invention E-SBR 80 80 80 0 NR 20 20 20 20 MASTER 5 0 0 0 100 Silica 20 30 40 0 TESPT 1.6 2.4 3.2 1.6 CB N234 1.6 2.4 3.2 1.6 Soluble Sulfur 1.63 1.63 1.63 1.63 ZnO 2.5 2.5 2.5 2.5 Stearic Acid 2.5 2.5 2.5 2.5 CBS 2.9 2.9 2.9 2.9 TMQ 1 1 1 1 6PPD 1.5 1.5 1.5 1.5
Materials

(127) MASTER 5: SBR masterbatch comprising 20 phr of composite reinforcing filler according to Example 2;

(128) E-SBR: coagulated SBR, obtained by coagulation from SBR latex in emulsion with styrene % of 26% (solid content 66% by weight, Europrene Latice® E-5570, Versalis);

(129) NR: coagulated natural rubber, obtained by coagulation of natural rubber latex HA obtained by centrifuging and stabilized with ammonia (60% by weight—commercialized by Von Bundit Co. Ltd);

(130) Silica: Silica Ultrasil VN3, Ege Kymia;

(131) TESPT: bis(3-triethoxysilylpropyl) tetrasulfide, Si69®;

(132) CB: Carbon black N234, Cabot;

(133) Soluble Sulfur: S8 (soluble sulfur), Zolfo Industria;

(134) ZnO: Zinc oxide, Zincol Ossidi;

(135) Stearic acid: Stearin TP8, Undesa;

(136) CBS: N-cyclohexyl-2-benzothiazolesulfenamide (Vulkacit CZ/C), Lanxess;

(137) TMQ: polymerized 2,2,4-trimethyl-1,2 dihydroquinoline, Kemai;

(138) 6PPD: N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine, Solutia Eastman.

(139) Procedure

(140) All the components, with the exception of the sulfur and the vulcanization accelerator (CBS) were mixed in an internal mixer (Brabender) for about 10 minutes (1st step).

(141) When the temperature of 135° C. was reached, the material was mixed for another minute and then was discharged. The incomplete compound was left to rest for a day. The sulfur and the accelerator (CBS) were then added and the mixing was carried out in the same mixer at about 60° C. for 9 minutes (2nd step).

Example 8

(142) Characterization of the Vulcanizable Elastomeric Materials (G), (H), (I) and (L) after Vulcanization

(143) The vulcanizable elastomeric materials (G), (H), (I) and (L) were subjected to characterization tests as shown in the previous Example 5.

(144) The following Table 5 shows the results obtained by the characterizations carried out.

(145) TABLE-US-00005 TABLE 5 (G) (H) (I) (L) comparison comparison comparison invention Density 1.05 1.104 1.138 1.045 (g/cm.sup.3) M10 (MPa) 0.43 0.53 0.7 0.61 M50 (MPa) 1.52 1.59 2.12 1.88 M100 (MPa) 3.19 3.14 4.45 3.67 TS (MPa) 11.02 13.25 16.93 13.30 Eb (%) 244.34 293.27 268.06 315.79 ML (dNm) 1.59 2.89 3.48 3.15 MH (dNm) 12.56 16.35 18.94 16.99 T30 (minutes) 1.47 2.25 2 1.83 T90 (minutes) 2.83 4.37 3.92 3.71 G′ (3%) (MPa) 1.05 1.36 — 1.62 Tan Delta 0.106 0.102 0.187 0.138 (3%)

(146) Similarly to what was observed from the data given in Table 3, it also clearly appears from the data reported in Table 5 how the vulcanizable elastomeric material (L) according to the present invention, whilst comprising only 20 phr of composite reinforcing filler according to the present invention, shows significantly greater static and dynamic mechanical properties than those of the vulcanizable elastomeric material (G), which comprises the same amount of reinforcing filler and intermediate between those of the vulcanizable elastomeric material (H), which contains 30 phr of silica-based reinforcing filler, and of the vulcanizable elastomeric material (I), which contains 40 phr of silica-based reinforcing filler. This shows the greater reinforcing properties of the composite reinforcing filler according to the present invention with respect to silica.

(147) In addition, it clearly appears that the vulcanizable elastomeric material (L) has a lower density with respect to the vulcanizable elastomeric material (G) and even more lower with respect to the vulcanizable elastomeric materials (H) and (I). Therefore, the data given above highlight how the vulcanizable elastomeric material (L) allows to produce significantly lighter elastomeric materials with the same performance.

(148) Finally, it appears how the vulcanization behavior of the vulcanizable elastomeric material (L) is analogous in terms of torque and is better in terms of vulcanization kinetics with respect to the materials having equal performance (H) and (I). From the data reported above, therefore, it appears that the vulcanizable elastomeric material (L) is substantially workable with energy costs analogous to those of the vulcanizable elastomeric materials (H) and (I), but shows significantly higher vulcanization kinetics with respect to the latter, to the benefit of the productivity of the processes in which they are used.

Example 9

(149) Preparation of Vulcanizable Elastomeric Materials Comprising the Natural Rubber Masterbatches According to Example 3 and of Three Vulcanizable Elastomeric Materials Comprising Silica (Comparison)

(150) Three natural rubber masterbatches respectively comprising 20 phr, 30 phr and 40 phr of composite reinforcing filler according to Example 2 were used to produce vulcanizable elastomeric materials for tyre components, (P), (Q) and (R) respectively. These elastomeric materials were compared with conventional elastomeric materials comprising conventional silica, materials (M), (N) and (O). The elastomeric materials of these examples are based on model elastomeric compositions for tyre structural elements. Therefore, the results shown by these materials are predictive of those that can be obtained in a tyre.

(151) The following Table 6 shows the compositions in phr of the vulcanizable elastomeric materials (M), (N), (O), (P), (Q) and (R).

(152) TABLE-US-00006 TABLE 6 (M) (N) (O) (P) (Q) (R) compar- compar- compar- inven- inven- inven- ison ison ison tion tion tion NR 100 100 100 0 0 0 Silica 20 30 40 0 0 0 MASTER 0 0 120 0 0 2 MASTER 0 0 0 0 130 0 4 MASTER 0 0 0 0 0 140 6 TESPT 2 2.4 3.2 2 2.4 3.2 CB 2 2.4 3.2 2 2.4 3.2 Soluble 2 2 2 2 2 2 Sulfur ZnO 5 5 5 5 5 5 Stearic 2 2 2 2 2 2 Acid CBS 2 2 2 2 2 2 TMQ 1 1 1 1 1 1 6 PPD 1.5 1.5 1.5 1.5 1.5 1.5
Materials

(153) MASTER 2: Natural rubber masterbatch prepared according to Example 3 comprising 20 phr of composite reinforcing filler according to Example 2;

(154) MASTER 4: Natural rubber masterbatch prepared according to Example 3 comprising 30 phr of composite reinforcing filler according to Example 2;

(155) MASTER 6: Natural rubber masterbatch prepared according to Example 3 comprising 40 phr of composite reinforcing filler according to Example 2;

(156) NR: coagulated natural rubber, obtained by coagulation of natural rubber latex HA obtained by centrifuging and stabilized with ammonia (60% by weight commercialized by Von Bundit Co. Ltd);

(157) Silica: Silica Ultrasil VN3, Ege Kymia;

(158) TESPT: bis(3-triethoxysilylpropyl) tetrasulfide, Si69®;

(159) CB: Carbon black N234, Cabot;

(160) Soluble Sulfur: S8 (soluble sulfur), Sulfur Industria;

(161) ZnO: Zinc oxide, Zincol Ossidi;

(162) Stearic acid: Stearin TP8, Undesa;

(163) CBS: N-cyclohexyl-2-benzothiazolesulfenamide (Vulkacit CZ/C), Lanxess;

(164) TMQ: polymerized 2,2,4-trimethyl-1,2 dihydroquinoline, Kemai;

(165) 6PPD: N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine, Solutia Eastman.

(166) Procedure

(167) All the components, with the exception of the sulfur and the vulcanization accelerator (CBS) were mixed in an internal mixer (Brabender) for about 10 minutes in total (1st step).

(168) At the end of the 9 minutes when the temperature of 135° C. was reached, the material was mixed for another minute and then was discharged. The incomplete compound was left to rest for one day. The sulfur and the accelerator (CBS) were then added and the mixing was carried out in the same mixer at about 60° C. for 9 minutes (2nd step).

Example 10

(169) Characterization of the Vulcanizable Elastomeric Materials (M), (N), (O), (P), (Q) and (R) after Vulcanization

(170) The vulcanizable elastomeric materials (M), (N), (O), (P), (Q) and (R) were subjected to characterization tests as shown in the previous Example 5.

(171) The following Table 7 show the results obtained by the characterizations carried out.

(172) TABLE-US-00007 TABLE 7 (M) (N) (O) (P) (Q) (R) compar- compar- compar- inven- inven- inven- ison ison ison tion tion tion Density 1.054 1.097 1.131 1.046 1.066 1.095 (g/cm.sup.3) M10 0.32 0.38 0.41 0.38 0.5 0.61 (MPa) M50 0.94 1.02 1.09 1.14 1.38 1.64 (MPa) M100 1.6 1.71 1.84 2.14 2.51 2.94 (MPa) M300 7.77 9.15 10.08 9.98 10.94 12.04 (MPa) TS 20.37 28.92 27.96 25.47 27.09 28.41 (MPa) Eb (%) 486.89 549.21 562 535.3 523.9 543.46 ML 0.81 1.32 1.98 0.69 0.88 2.09 (dNm) MH 11.83 13.6 16.09 12.15 14.17 19.14 (dNm) T90 3.01 3.41 3.42 2 2.43 2.72 (minutes) G′ (3%) 0.69 0.9 1.17 0.73 0.95 1.6 (MPa) Tan 0.064 0.06 0.097 0.089 0.091 0.119 Delta (3%)

(173) From the data reported in Table 7 it is possible to further confirm what emerged from the previous Examples, i.e. that the composite reinforcing filler according to the present invention has greater reinforcing properties than those of silica-based reinforcing fillers, allowing to use smaller amounts of filler to achieve the same performance.

(174) Furthermore, also from the data of Table 7 it appears that by using higher amounts of composite reinforcing filler according to the present invention, for example 30 or 40 phr, it is possible to obtain values of dynamic shear elastic modulus G′ and of Tan Delta, predictive of an improvement of maneuverability at high speed and in limit driving conditions, typical of high-performance tyres, for example HP and UHP tyres.

(175) In addition, it ensues that the vulcanizable elastomeric materials (P) (Q) and (R) always show lower density values, for the same amount of filler, with respect to vulcanizable elastomeric materials containing silica-based reinforcing fillers, materials (M), (N) and (O) respectively, thus allowing to produce significantly lighter elastomeric materials.

(176) Finally, it appears how the vulcanization behavior of the vulcanizable elastomeric materials (P) (Q) and (R) is analogous in terms of torque and better in terms of vulcanization kinetics with respect to materials (M), (N) and (O).

(177) From the data given above it therefore ensues that the vulcanizable elastomeric materials (P) (Q) and (R) are substantially workable with energy costs analogous to those of the vulcanizable elastomeric materials (M), (N) and (O), but show significantly higher vulcanization kinetics with respect to the latter, to the benefit of the productivity of the processes in which they are used.

(178) The above examples should not be considered exhaustive of the advantages of the invention, for which reason the carbon black could also be replaced with advantages by a renewable composite reinforcing filler according to the invention. In this regard, the Applicant deems that the composite reinforcing filler can prove more reinforcing with respect to carbon black due to its fibrous rather than spherical particle nature.