WO2013093295A1

WO2013093295A1 - Method for producing a composition for the production of a tyre

Info

Publication number: WO2013093295A1
Application number: PCT/FR2012/052890
Authority: WO
Inventors: Quentin URBAIN; Sylvain GOUTEYRON
Original assignee: Compagnie Generale Des Etablissements Michelin; Michelin Recherche Et Technique S.A.
Priority date: 2011-12-20
Filing date: 2012-12-12
Publication date: 2013-06-27
Also published as: FR2984206B1; FR2984206A1

Abstract

In the method for producing a composition for the production of a tyre for a wheel, while a rubber-based composition (18) flows in the air gap of a calender comprising at least two cylinders (6, 8), at least one vulcanising agent (22) in liquid form is applied to at least one of the cylinders (8) such that the agent solidifies on said cylinder, and is then incorporated into the composition.

Description

Process for producing a composition for manufacturing a tire

[1] The invention relates to the manufacture of wheel tires and in particular the production of a composition for the manufacture of the tire.

[2] The tire gum composition generally comprises natural elastomer, synthetic elastomer, carbon black, silica, oil and vulcanizing agents such as sulfur. In practice, the constituents are first mixed with heat without incorporating the vulcanizing agents therein because they would then prematurely trigger the latter. So we first obtain a composition, which we call here primary composition or "masterbach", which is cooled. And it is only in a final mixing stage that the vulcanizing products are incorporated, either in powder form or in the form of blocks formed of an elastomeric matrix containing the vulcanizing products, with the primary composition to obtain a secondary composition which is then cooled so as to be used for the manufacture of the tire.

[3] This procedure is relatively long and complicated because it requires one or more additional manufacturing steps.

[4] An object of the invention is to facilitate obtaining the secondary composition.

[5] For this purpose, there is provided according to the invention a method of producing a composition for the manufacture of a wheel tire, wherein, while circulating a composition based on rubber in the air gap of a calender comprising at least two cylinders, at least one vulcanizing agent in liquid form is applied to at least one of the rolls so that the agent solidifies on said cylinder and then becomes incorporated into the composition.

[6] Thus, the vulcanizing agent or agents, initially in molten form, solidify as soon as they come into contact with the cylinder and then are incorporated into the composition during its circulation for mixing or cooling. Therefore, it is not necessary to provide a separate step in which, as in the prior art, there is provided a block incorporating the vulcanizing agent (s) for mixing with the primary composition. By avoiding this step, one simplifies and accelerates the realization of the composition. Moreover, the application of the agent (s) in liquid form can be carried out continuously, which makes it easier to assay for a better respect of the proportion of vulcanizing agent in the final mixture. [7] Preferably, prior to application, the or each vulcanizing agent is melted.

[8] Advantageously, during application, at least two vulcanizing agents and / or at least one non-vulcanizing product are applied.

[9] Preferably, the application is made simultaneously in several parts of the cylinder remote from each other in a direction parallel to an axis of the cylinder.

[10] Thus, a large amount of vulcanizing agent can be applied to the cylinder without threatening its integral solidification prior to incorporation into the composition.

[1 1] It can be provided that the or each cylinder has a temperature between 5 ° C and 100 ° C and preferably between 20 and 80 ° C.

[12] Preferably, the cylinder being a first cylinder and the other cylinder of the calender being a second cylinder arranged so that the composition is compressed by the two cylinders passing between them, it implements the method of so that the first cylinder has an outer surface less hot than an outer surface of the second cylinder.

[13] Indeed, it is known that the gum mixture adheres more or less spontaneously to one of the two cylinders depending on the temperature difference between these two cylinders. By applying the vulcanizing agent (s) to the other cylinder, the cylinder is selected which is free of gum and on which the agent (s) can easily solidify.

[14] Also provided according to the invention is a method of manufacturing a vehicle wheel tire, in which a method according to the invention is implemented.

[15] According to the invention there is further provided an installation for producing a composition based on gum, which comprises:

means for circulating a composition based on gum,

means for feeding the circulation means with such a composition, and

- Means for applying to a cylinder a liquid product hotter than an outer face of the cylinder, the cylinder being arranged so that the product once solidified is incorporated in the composition flowing in the circulation means.

[16] Such an installation allows the implementation of the method of the invention.

[17] Advantageously, the application means comprise at least a buzzard.

[18] Preferably, the application means comprise a ramp carrying at least two nozzles.

[19] We will now present an embodiment of the invention and an alternative with reference to the accompanying drawings in which:

- Figure 1 is a schematic view of an installation according to the invention;

FIG. 2 is a perspective view of part of the installation of FIG. 1; and

- Figure 3 is a view of an installation according to an alternative embodiment of the invention.

[20] FIGS. 1 and 2 illustrate an installation 2 for producing a composition for the manufacture of a land vehicle wheel tire.

[21] We will first present the installation 2 and then describe a mode of implementation of the method according to the invention by means thereof. The installation comprises means for mixing an eraser composition comprising in particular a shell 4 which comprises two cylinders 6 and 8 respectively illustrated on the left and on the right in FIGS. 1 and 2. The two cylinders are in this case identical to one another. one to another. They have two respective axes 10 parallel and inscribed in the same horizontal plane. Each cylinder has a circular section in a plane perpendicular to its axis. The cylinders are arranged so as to provide a narrow space between them for mixing the products to be mixed. The cylinders are each rotatably mounted about their axis. The installation 2 comprises means 12 for motorizing the cylinders able to rotate them in opposite directions from one another in order to pass between them falling products between the cylinders. The installation comprises control means 14 ensuring the control of its various organs. Cooling means 7 and 9 of the cylinders make it possible to maintain them at the respective desired temperatures.

[22] The plant 2 also comprises an internal mixer 16 adapted to receive different constituents of a primary composition of gum to ensure their hot mixing and form a primary composition of gum or "masterbach" 18. The installation 2 comprises by example a conveyor 21 suitable for carrying this composition from a lower outlet of the internal mixer to the calender to make it fall between the cylinders.

[23] The installation further comprises a member 20 for melting and mixing various products 22 among which one or more agents vulcanizing. This member comprises in particular heating means 23 for melting these products and is equipped with means 24 for regulating its temperature.

[24] The installation also comprises a ramp 26 elongated in a direction parallel to the axes 10. The ramp 26 is equipped with nozzles 28 and communicates via a conduit 30 with the member 20 to supply the nozzles 28 with the liquid hot. The nozzles are disposed above the cylinder 8 so as to project the liquid 31 on the cylindrical outer surface of the cylinder, on the portion of this surface which is in the upper part and before it comes opposite the other cylinder because of the rotation. The installation comprises a flowmeter 32 interposed on the conduit 30 between the member 20 and the ramp 26 in order to make it possible to regulate the flow of liquid provided by the nozzles 28.

[25] The installation, and in particular its control means, are arranged to implement the method of the invention as follows.

[26] The primary composition is produced in the mixer 16 by hot mixing including natural rubber, synthetic rubber, carbon black and oils.

[27] Separately, various products 22 intended to constitute the liquid 31 are melted in the member 20. These products include vulcanizing agents which can be chosen according to the following cases (this list not being limiting):

CBS: N-cyclohexyl-2-benzothiazyl sulfenamide. This is for example the product "Santocure CBS" Flexsys company.

DCBS: N, N-dicyclohexyl-2-benzothiazyl sulfenamide,

- DOTG: diorthotolylguanidine,

DPG: diphenylguanidine,

H3M: hexa (methoxymethyl) melamine,

- HMT: hexamethylene tetramine,

- MBT: 2-methylbenzothiazole,

MBTS: 2-mercaptobenzothiazyl

- peconal,

- suffers,

TBBS: N-tert-butyl-2-benzothiazylsulfenamide,

TBSI: N-tert-butyl-2-benzothiazylsulfenimide,

- TBZTD: tetrabenzylthiuram disulfide,

- ZBEC: zinc dibenzyldithiocarbamate, and

- ZEH: 2 ethyl hexanoate zinc. [28] Other products which are not in themselves vulcanizing agents, for example the following ones, may be added to this mixture (this list not being limiting):

- stearic acid,

- paraffin,

TMQ: 2,2,4-trimethyl-1,2-dihydroquinoline,

6-PPD: N-1,3 dimethylbutyl N-phenylparaphenylenediamine,

or alternatively IPPD: N'-isopropyl-N'-phenyl-para-phenylenediamine.

[29] The vulcanizing agents and the other products are chosen according to the type of gum composition that is to be made and the type of tire to be produced by means of it. The mixing of these products takes place at a sufficiently high temperature to ensure their melting and low enough not to degrade them. Indeed, these products should not stay too long at an excessive temperature compared to their melting point. For example, a temperature of 100 ° C. or 140 ° C. is chosen.

[30] Once the mixing of the primary composition has been carried out, the mixed mass falls on the conveyor 21 out of the mixer 16 and is then conveyed to the calender 4 where it falls between the rolls 6 and 8 to be pressed and kneaded between those -this. The mixture can be kneaded by adjusting the distance between the two rolls. For example, it will be possible for the primary composition to be cooled for two minutes while circulating in the shell before starting the feed with the liquid.

[31] At the end of a fixed period, the nozzles 28 are fed by means of the liquid 31. The nozzles thus water the upper part of the cylinder 8 with this liquid. The latter solidifies as soon as it comes into contact with the cylinder and then mixes continuously with the primary composition because of the rotation of the two cylinders. The crystals thus formed come into contact with the composition at the bead 34 formed by a fraction of the latter accumulated above the air gap. The crystals remelt in contact with the bead and are incorporated in the composition, which ensures a rapid and homogeneous diffusion of vulcanizing agents in the mixture.

[32] The cylinders are maintained at a temperature between 5 ° C and 100 ° C, and preferably between 20 and 80 ° C, which is lower than the solidification temperature of the products 22, in particular the vulcanizing agents. The quantity of liquid poured in order to water the cylinder must be chosen so that all the molten liquid solidifies on the cylinder. No fraction of liquid should remain liquid in contact with the cylinder, or pour on the sides of the shell. In particular, the maximum thickness of liquid to be applied to the cylinder depends on the nature of its constituents and their melting temperature as well as the temperature of the cylinders.

[33] Once the secondary composition thus obtained, it is evacuated for use in the manufacture of a tire. By means of this composition, rubber elements are produced for constructing a blank of raw rubber equipped with reinforcements. The blank is then fired to effect the vulcanization of the gum.

[34] Knowing that it is not necessary to separately make a block comprising the vulcanizing agents in solid form and intended to be subsequently incorporated in the masterbach, the cycle time and the manufacture of the gum composition used to accelerate it are accelerated. manufacture of tires. The dosage of vulcanizing products is also facilitated.

[35] In an alternative embodiment, the installation comprises a device 40 for cooling the primary composition and whose calender 4 forms only a part. The gum mixture at the outlet of the air gap is deposited on a horizontal conveyor 44 which in this case moves the gum mat to the left. The device may then comprise an inclined conveyor in the form of an elevator 46 which retrieves this web to transport it here to the right to make it fall back into the calender. This device makes it possible to follow the mixture out of the calender a longer path and can be equipped with cooling or cutting means promoting the mixing and cooling of the composition. This path of the gum mixture has been illustrated in dashed lines in FIG.

[36] After circulating the primary composition within this circuit for cooling, the cylinder 8 of liquid is sprayed as before to incorporate the vulcanizing agent (s) while the composition continues to circulate in this device 40.

[37] For example, the invention can be implemented as follows.

[38] A primary composition consisting of a KM / PL type mixture is used. "KM / PL" means a mixture intended for the production of a tire tread fitted to a vehicle of the heavy vehicle type. The composition circulates on the rolls of the calender having a temperature of between 100 and 140 ° C. The cylinders are cooled by means of an internal circulation of water at 8 ° C. Each cylinder has a diameter of 700 mm. Cylinders 6 and 8 rotate at different speeds of 20 and 24 rpm respectively. Their gap is varied from 4 to 2 mm. [39] In a first example, 2.370 kg of melted sulfur with a temperature of 130 ° C. are projected onto the rear cylinder. In a second example, it is 0.950 kg of molten CBS having a temperature of 110 ° C.

[40] Each time, the primary composition is circulated between 3 and 5 minutes after projection to incorporate the vulcanizer. The mass of the final composition is 250 kg.

[41] Of course, we can bring to the invention many changes without departing from the scope thereof.

[42] In the variant of Figure 3, the cylinder 6 is free of rubber on a portion of its circumference during the implementation of the method. It can therefore be added a ramp of nozzles fed from the member 20 to project on this cylinder also the liquid comprising the vulcanizing agents or agents. Thus, the two cylinders 6, 8 are simultaneously watered in order to solidify the vulcanizing agent and incorporate it into the composition in greater quantity per unit of time.

Claims

claims

A method for producing a composition for the manufacture of a wheel tire, characterized in that, while a compound (18) based on rubber is circulating in the air gap of a calender comprising at least two cylinders ( 6, 8), at least one vulcanizing agent (22) is applied in liquid form to at least one of the rolls (8) so that the agent solidifies on said cylinder and then becomes incorporated into the composition.

2. Method according to the preceding claim wherein, prior to application, is melted or each vulcanizing agent (22).

3. Method according to at least one of the preceding claims wherein, during the application, at least two vulcanizing agents (22) are applied.

4. Method according to at least one of the preceding claims wherein, during the application, at least one non-vulcanizing product (22) is applied.

5. Method according to at least one of the preceding claims wherein the application is carried out simultaneously in several places of the cylinder distant from each other in a direction parallel to an axis (10) of the cylinder.

6. Process according to at least one of the preceding claims, in which the cylinder (8) has a temperature of between 5 and 100 ° C and preferably between 20 and 80 ° C.

7. Method according to at least one of the preceding claims wherein, the cylinder (8) being a first cylinder and the other cylinder of the calender being a second cylinder (6) arranged so that the composition is compressed by the two cylinders passing between them, the method is implemented so that the first cylinder has an outer surface less hot than an outer surface of the second cylinder.

8. A method of manufacturing a vehicle wheel tire, characterized in that it implements a method according to at least one of the preceding claims.

9. Installation (2) for producing a composition based on gum, characterized in that it comprises:

means (4; 40) for circulating a composition based on gum; means (16, 20) for feeding the circulation means with such a composition, and means (26, 28) for applying to a cylinder (8) a liquid product which is hotter than an external face of the cylinder, the cylinder being arranged so that the product once solidified is incorporated in the composition circulating in the means of circulation.

10. Installation according to the preceding claim wherein the application means comprise at least one nozzle (28).

11. Installation according to at least one of claims 9 to 10 wherein the application means comprise a ramp (26) carrying at least two nozzles.