Tire of high operating properties with tread belt provided with anisotropic underlayers stable at changes of temperature

FIELD: road vehicles.

SUBSTANCE: proposed tire has radial body with one or several breaker layers on place close to outer surface, and strengthening layer with nylon cord wound in spiral over breaker. It is desirable that tread belt of tire be formed by underlayer and outer layer, one placed on the other, elasticity and/or hardness characteristics of first layer remaining stable at temperatures within 20 and 110oC.

EFFECT: improved performance characteristics of tires.

23 cl, 4 tbl, 2 dwg

 

The present invention relates to a tire with high performance characteristics, such as tires, designed for cars with large capacity, or more generally to a tire intended for use at high operating speeds.

These tires commonly referred to as the tyres with high performance and very high performance characteristics, in particular, belong to the classes of the “V” and “Z”, which are respectively designed for maximum speeds in excess of 210 and 240 km/h, in which performance is undoubtedly represent the most important characteristics.

These qualities depend on the coefficient of friction (or traction), and the reaction cross-bus voltage during rolling on the road surface.

Typically, the friction coefficient depends on the properties of the composition used for the manufacture of the tread, whereas the response to transverse tension and centrifugal force depends on the design of the tyre; for these reasons, there are structures designed compensation systems of forces, which are tires with high performance and very high operational qualities.

In one of these structures provides the so-called “0°-layer, i.e. the layer of rubber, reinforced cord threads that are about what a rule is able to shrink when heated, for example manufactured of nylon, is wound around broker bus spirally in the circumferential direction.

The angle of winding cord yarns relative to the median (or Equatorial) plane of the tire is relatively small and for this reason, the layer in which they are located, call 0°-layer; on top of this layer is the tread belt.

From the patent Canada No. 1228282 (Bridgestone) and European patent No. 592218 (Sumitomo) known the tread belt, which is usually known as the structure of the coating and the base, i.e. consisting of two layers, located on a circle on top of one another, with the inner radius of the layer forms the “base”, or sublayer, while the other, the most remote, forms the “floor” and is the layer that is suitable for rolling along the road.

In particular, in the first of these documents to improve the characteristics of control at high speeds is proposed to combine the sublayer with an outer coating having a high adhesion and a specified ratio of the modulus of elasticity of the coating to the modulus of elasticity of the sublayer.

On the other hand, in European patent No. 592218 prompted to enter the reinforcing fibers in the composition of the substrate and oriented in a certain way in order to obtain anisotropic characteristic of the sublayer with different moduli of elasticity, respectively, is the circumferential direction and in the transverse direction relative to the bus.

In this case, you can get a tire with good stability during cornering, with a high level of comfort while driving, as well as low rolling resistance tires.

In addition, in European patent application No. 494158 disclosed tyre with tread belt having a structure of type coating and the base; in this case, the layer of rubber reinforced by short fibers, having in cross section the shape of a “sea-island” and formed from at least two polymers.

Finally, European patent application No. 691218, published in 1996, it is known that it is possible to make tires with properties that are essentially equivalent properties of the tire reinforcing layer composed of nylon cord yarns angled at 0°through the creation instead of the last sublayer tread reinforced with fibers with defined size and strength.

These fibers are formed from materials such as polyamides (in particular, aromatic polyamides, for brevity called “aramids”), polyesters or polyolefins, the use of which in the manufacture of tires is already known from the prior art.

For example, as aramid fibers, their use in the tire manufacturing industry is shown in U.S. patent No. 4871004, which is incorporated into the present application by reference.

One of the reasons for the use of the above who mentioned fibers, stems from the fact that they, as a rule, allow to obtain high structural stability at low weight.

However, there are some technical features that must be considered when using this fiber.

In fact, use them instead of the traditional materials of the type used in the manufacture of tires or in combination with them, refers to the area that is currently not yet fully investigated; therefore, it is important to be able to optimize the use of fibers to achieve the desired characteristics of the tyres.

Tires with high performance and very high performance characteristics, known at the present time, are not fully acceptable from the point of view of their characteristics at high speed and during continuous operation; in the present invention proposes a solution to this problem by creating a tire with high performance characteristics with design and performance characteristics, which remain essentially unchanged during the different conditions of use.

The invention arose from the realization by the applicant that high values of modulus of elasticity and/or hardness of the material of the underlayer, as an alternative to each other or in combination with each other, must be guaranteed and p and high speeds, above, and, in particular, should not deteriorate with increasing temperature due to prolonged use at high speed, and the realization that this task can be solved using the above-mentioned fibers.

In particular, the applicant found that the problem can be solved using the tire in which the reinforcing layer cord angle of 0° superimposed tread belt type structure floor and Foundation, the sublayer which has values of hardness and/or elasticity, which largely stable between 23 and 100°C.

In fact, due to these features, guaranteed constancy of performance of the tire at high operating speeds, which can cause a significant temperature increase of the protector.

In accordance with one of several characteristic features of the invention relates to a tyre in which the hardness of the underlayer of the tread between 23 and 100°does not change by more than 5 units on the international scale degree of rubber hardness (MSTR); preferably, this change did not exceed 3 units, preferably 1 unit MSTR.

In accordance with another characteristic of the invention, the tread belt tires has a sublayer with a dynamic modulus (E’) of elasticity, which is between 70 and 100°not modified more than n is 10%, and preferably, it has changed less than 5%.

In accordance with a preferred embodiment of the invention, the sublayer also has a high ratio (more than 4) stiffness in motion direction (i.e. in the circumferential direction) to the stiffness in the perpendicular direction; this means that he has an anisotropic characteristic.

The properties of the sublayer of the tread above, can be obtained by using the composition, the reinforced fibers in quantities of preferably between 3 and 10 parts per 100 parts of rubber), and even more preferably in amounts of between 6 and 9 parts per 100 parts of rubber, in combination with the cured resins; however, it is preferable that the latter were based on resorcinol and methylene donors.

These resins may be in the form of two components or pre-gelled form, with the preferred methylene donors include hexamethoxymelamine or hexamethylenetetramine; however, the applicant has found that it is possible to use other methylene donors and cured resins of other types.

These and additional features of the invention will become clearer from the detailed description of a preferred but not exclusive variants of its implementation, which is presented below with reference to the accompanying drawings, in which:

figure 1 - section of a tire according to the invention; and

figure 2 is a partial section view of the tread of the preceding figures.

In the drawings, reference number 1 indicates a tire according to the invention.

This bus contains the frame is made in the form of at least one layer 3, with its ends connected with the respective cores 4 (commonly known as wire cores boards), each of which is embedded in the Board 5, continuing along the circular edge of the tire; the core or wire core 4 side can be performed by any means known from the prior art, for example using a metal rod or cord threads.

It is assumed that the boards 5 are based on the edge of the rim, not shown in the drawings, which set the tire 1.

Around the frame around the circumference of the imposed one or more bragarnyk layer 7, typically performed using a mesh of metal thread or cord threads embedded in rubber sheet and arranged parallel to each other in the layer and across the threads of the adjacent layer.

Over broker 7 is 0°-the layer in which a cord 8, for example made of nylon, is wound in a spiral coaxial bus; as usual, the angle of winding of the cord 8 in relation to the median plane m-m tires small and the cord is also embedded in the rubber layer, as is usually delayt the prior art (using the so-called “tape” or other decisions).

In addition, the tire 1 has a tread belt 10, which is located at a greater distance from the center around the 0°-layer; more precisely, this tread belt-type coating and the base is formed by a sub-layer 11 and outer layer 12, which is the usual way to create a tread containing indentations, or grooves 13, which set numerous grooves and blocks.

As can be seen in the drawings, in this case, the underlayer 11 of the protector 10 has a uniform thickness; preferably this thickness greater than 1 mm and even more preferably, it was between 1.5 and 2 mm

However, it should be noted that the thickness of the substrate 11 in all cases may not be uniform, and, for example, greater near the outer edges (see sections shown in figures 1 and 2) and/or in the Central zone.

The outer layer 12 of the tread belt should have a thickness at least equal to and preferably greater than the depth of the grooves 13 (usually 7-8 mm in automobile tires), so that the sublayer does not come into contact with the road when the outer layer is worn.

Preferably the basis of the composition, which produce a sublayer 11 is natural rubber, it is preferable that he was reinforced with aramid fibers, in this case made of Kevlar®, manufactured by Du Pont de Nemour; in this example, these fibers have a configuration osnovnoj the trunk, having a diameter D equal to about 10 microns, and a length L of about 200 μm, from which depart small branch or fibrils.

In this case, the fibers have a ratio L/D of sizes of the order of 20.

In particular, use of the material in which the above-mentioned fiber (commonly known as “suspension Kevlar®”) dispersed in natural rubber, resulting in a “filled rubber”, supplied by Du Font under the trade name Kevlartex®, having the composition: 23% Kevlar® and 77% of natural rubber.

The use of filled rubber instead of one fiber is preferred because it can more effectively be mixed and distributed in the elastomeric composition, which is used for manufacturing substrate 11.

The composition for substrate shown in detail in table 1, in which the various components are indicated generally accepted trade names and the abbreviated chemical names.

For example, the abbreviation EP-BSK (E-SBR) followed by a number is conventionally used to denote a type of synthetic rubber emulsion polymerization, butadiene-styrene rubber (BSC), in accordance with well-known international standards (usually American society for testing materials or the International organization for standardization (ISO) or the abbreviation consists of the letter N followed the Islom indicates the type of the carbon black in accordance with the nomenclature system of the American society for testing and materials.

The numerical values shown in table 1 are relative to the content of the rubber (100 parts rubber) and the whole composition; in any case, it should be noted that the used composition contains 39 pieces Kevlartex® per 100 parts of rubber, and in light of the composition of this filled rubber this means that essentially, 39 parts per 100 parts of rubber composed of 30 parts of natural rubber (NC) per 100 parts of rubber and 9 parts of aramid fibers per 100 parts of rubber.

Table 1
The composition for substrate
IngredientTo 100 parts of rubber%
NCNatural rubber30,0accounted for 14.45
FL-BSC 171223% of the binder of styrene diluted oil55,026,49
Carbon blackFamily N30060,028,90
Zinc oxideZnO8,003,85
Crystex® 3367% undissolved sulfur (oil)the 5.252,53
Cyrez® 963 (cured resin)Hexamethoxymelamine with filler: 65% silicon dioxide2,41
Rhenogran Resorcinol® 80 (cured resin)With filler: 80% polymer1,880,91
DCS (accelerator)N,N’-dicyclopentyl-sulphonamide1,500,72
6 PFD (antioxidant)Paraphenylenediamine2,000,96
Kevlartex®23% Kevlar®, 77% of NC39,018,78
Only207,63100

Crystex® 33 is supplied by the company FLEXIS, Cyrez® 963 company CYTEC and Rhenogran Resorcinol® 80 company RHEIN-CHEMIE.

As you can see from the table, in this example, the cured resin-based resorcinol and methylene donors (in particular, on hexamethoxymelamine), used in the form of two components.

In addition to hexamethoxymelamine preferred methylene donors include hexamethylenetetramine; however, you can use other donors, and the cured resin can be in a pre-gelled form.

Alternatively, the above-mentioned resins can be used other cured resin, such as resin-based epoxy polyols, epoxides-diamines, epoxides and dicarboxylic acids, or resins obtained by the reaction of the alcohol with a dibasic Ki is lotay (alkyd resins).

These resins can be used as a pre-gelled form and in the form of two components.

Based on General considerations, it can be argued that the number of cured resins in the composition to the substrate can be optimized depending on the mechanical properties (elastic modulus, hardness and so on)that you want to retrieve.

Therefore, when used in the present invention resin-based resorcinol and methylene donor is preferable to use pre-gelled resin in a quantity greater than 0.5 parts per 100 parts of rubber. However, in the case of two-component systems it is preferable to have resorcinol in amounts greater than 0.5 parts per 100 parts of rubber, and the methylene donor (type hexamethoxymelamine), which is to him in the relation between 0.5 and 3.

The underlayer 11, obtained using the composition according to the invention, can be manufactured by co-extrusion with the outer layer 12 or may be made separately and layers to merge later; however, joint molding may be preferable in the case of manufacturing sublayers limited thickness and, if necessary, shaping their profile complex forms.

The material of the composition indicated in the table above, were subjected to sequential mechanical tests to determine the population values of some of its characteristics, including hardness and elasticity; the results of these tests are shown below in table 2.

As for the hardness tests were performed in accordance with standard 1415 American society for testing and materials, and as for the elasticity, the purpose of the tests was to measure the dynamic modulus E’ of elasticity on cylindrical test specimens with a diameter of 12 mm and a length of 25 mm

In particular, these prototypes were created by folding strips of width, a bit larger than 25 mm (i.e. the height of prototypes)obtained by calendering and cutting strips with a thickness of 1 mm in the direction of orientation of the fibers within them; for subsequent folding strips of fiber was placed in the circumferential direction relative to the cylinder, formed the sample.

Here it is necessary to remind, that the operation of the calendering and extruding compositions create the effect of the orientation of the fibers included in the composition, along the corresponding directions, for which they carry out.

Then samples were vulcanizable for 30 min at 151°and subjected to dynamic tests (sinusoidal) frequency 100 Hz, applying first preliminary voltage, equal to 10%, then the true dynamic voltage equal 0,033; this last parameter characterizes the deformation is the situation depending on the length of the pre-deformed prototype.

When tests are taken into account additional parameters; the corresponding results are shown in table 2, including loading at 10%relative elongation in the direction of calendering (M1) and in the direction crosswise to the direction of calendering (M2).

Such loads values were obtained in accordance with the standard 412 American society for testing of materials under the effect of traction on traditional prototypes Danbulla; they provide an evaluation of the resistance to deformation of the substrate in mutually perpendicular directions. The ratio M1/M2, shown in the table describes the parameter of anisotropy of the substrate due to the presence of oriented fibers.

Finally, for a more complete assessment of the characteristics of these samples of the invention in table 2 also shows the results of comparative experiments carried out on samples of the compositions according to the already mentioned European patent No. 592218 (Sumitomo Rubber Industries) and patent in Canada, No. 1228282 (Bridgestone).

Table 2
TestInventionExample 2Example 3
Score from MSTR at 23°908977,5
Score from MSTR at 100° 898367,4
Load M1 at 10%elongation in the direction of calendering (MPa)11,77are 11.622,5
Load M2 at 10%elongation crosswise to the direction of calendering (MPa)1,231,52,05
M1/M29,6of 7.751,22
E’ at 23°With (MPa)36,7134,9111,42
E’ at 70°With (MPa)33,1820,327,16
E’ at 100°With (MPa)33,1516,67the 5.7

Table 2 shows that the material according to the invention is much more stable when the temperature changes (heat resistant)than the materials of examples 2 and 3.

In particular, the hardness is very stable between 23 and 100°With (ranging from 90 to 89 units on the international scale degree of rubber hardness); as a rule, in any case, the change in hardness in the above temperature range should not exceed 5 units on the international scale degree of rubber hardness (MSTR).

In accordance with the invention, it is preferable that the hardness of the underlayer in absolute values was greater than the hardness of the outer layer of the tread belt; more precisely, p is edocfile, to this hardness was greater than 80 units on the international scale degree of rubber hardness at 100°S, and even more preferably, it was more than 85 units on the international scale degree of rubber hardness at 100°C.

In the case of the invention modulus E’ of elasticity, and hardness, does not change significantly between 70 and 100°, which cannot be said about the materials of examples 2 and 3.

Preferably, in the above temperature range of the module E’ elasticity does not exceed 10%, and even more preferably does not exceed 5%.

In accordance with the invention, it is preferable that the absolute value of the modulus E’ of elasticity of the sublayer was greater than the elastic modulus of the outer layer of the protective layer; more specifically, this module should be preferably greater than 15 MPa at a temperature of 100°With, but more preferably, it is at this temperature was greater than 20 MPa.

The applicant represents that if the values of hardness and/or modulus E’ of elasticity above, significantly improve the qualitative characteristics of the tires of all known types, regardless of the characteristics of the outer layer of the tread belt.

Finally, from table 2 one can notice that the ratio M1/M2 for sample of the invention is greater than 9; typically, this ratio should be greater than 3.

For a fuller OPI the project now presents the composition of the sublayer, examples 2 and 3, defined on the basis of the descriptions of the above-mentioned patents (see table 3).

Table 3
IngredientExample 2Example 3
To 100 parts of rubberTo 100 parts of rubber
NC26 
FL-BSC 1712 137,5
BSC 150020 
Carbon black (N324)40 
Carbon black (N326) 90
Zinc oxide33
Sulfur1,751
Accelerators11,8
Antioxidants22
Kevlartex®74 

The results of manufacturing tires according to the invention manifest themselves in unexpectedly superior characteristics compared to the characteristics of other tires with high performance and very high performance; these results are summarized in the following table 4, reflect nominal harakteristiki scale values ranging from -2 to +2 relative to the individual behavior of the tires.

These parameters are related to the behavior during cornering (unnecessary turning and insufficient turning)traction, lateral stability, response to a lane change and continuity characteristics; this latter figure refers to the ability of a bus to save values of characteristics at high speeds and, therefore, with increasing temperature.

The tests were carried out using tyre size 225/40 R 17 installed on the rear axle of the Porsche Carrera 996.

Table 4
 InventionExample 3
Management21,2
Grip22
Lateral stability21,5
The lane change21
The constancy of characteristics21,3

As you can see, the data in table 4 confirm the results obtained above, achieved by using the invention; indeed, when using tyres achieved good results for all the considered parameters with obtaining maximum ratings in all categories, essentially accepts the descending results for bus in example 3, except for the grip.

It must be emphasized that this exception is actually further confirms the results obtained.

As you know, actually grip the tire with the road depends, in part, from material “coverage” of the tread, and not sublayer; in this case, since the same composition used for the outer layer of the tire according to the invention for the outer layer of the tire according to the example 3, the data related to the grip, consistent with the expected data.

So this confirms that the improvements achieved through the tire according to the invention for the other considered parameters, you must assign the sublayer 11 and the composition from which it is made.

Finally, it is also important to mention another beneficial side, which characterizes the composition from which made the sublayer according to the invention: good machinability.

During the experiments it was found that an excessive amount of fibers in relation to the rubber in the composition (i.e. the exceeding of the limits proposed in the invention) can adversely affect the machinability of the specified composition and create problems during subsequent manufacture of the protector with the sublayer.

On the other hand, the number of reinforcing fibers used for the invention, sposob who was the exception to these negative effects, resulting in the invention is very advantageous from the point of view of industrial production.

Obviously, you can anticipate changes invention in relation to its preferred and non-exclusive variant implementation, which is described above.

It should be noted that the used reinforcing fibers may vary from fiber type Kevlar®mentioned above; in fact, you can use other aramid fibers, for example fibers, known as Twaron®, supplied by the company Akzo Nobel; in addition, the applicant has found that it is possible to use fiber-based other polyamides or on the basis of polyesters, polyolefins, polyvinyl alcohol, nylon, glass, etc.

With regard to the design of the tire, between the amplifying 0°-layer and a sublayer of the tread you can enter the usual thin connective sheet that is already known in the prior art.

However, these changes, together with other are within the scope of the claims.

1. Tyre with high performance qualities that contains a frame, including at least one layer (3) skeleton belt placed around the circumference of the frame containing two or more layers (7) of the reinforcing cord yarns, which are parallel to each other in the layer and transversely directed in relation to the cord threads of the adjacent layer, radial the outer layer (8) of oriented along the circumference of the reinforcing cord yarns, superimposed on the belt, the tread belt (10), which contains the sublayer (11) and outer layer (12), characterized in that the underlayer (11) made of elastomeric compounds containing reinforcing fibers and a cured resin.

2. The tire according to claim 1, characterized in that the cured resin based on the components selected from one or more of the following groups: Resorcinol®donor methylene, epoxides-dicarboxylic acid, epoxides-diamines, epoxides-polyols, alcohol-dibasic acid.

3. The tire according to claim 2, characterized in that as a methylene donor used hexamethoxymelamine or hexamethoxymelamine.

4. The tire according to claim 3, characterized in that the underlayer (11) contains a cured resin-based Resorcinol® and methylene donor in a pre-gelled form in a quantity greater than 0.5 parts per 100 parts of rubber.

5. The tire according to claim 3, characterized in that the composition of the sublayer contains a cured resin on the basis of Resorcinol® and methylene donor in the form of two components, the number of Resorcinol® is more than 0.5 parts per 100 parts of rubber, and the amount of methylene donor match against Resorcinol® between 0.5 and 3.

6. Tire according to any one of claims 1 to 5, characterized in that the reinforcing fibers are selected from among polyamide, polyester, of polyolefins, carbon fibers, glass fibers and fibers of the floor is vinyl alcohol.

7. The tire according to claim 6, characterized in that the reinforcing fibers used aramid fiber.

8. The tire according to claim 7, characterized in that the composition of the sublayer (11) contains aramid fibers in a quantity in the range of 3 to 10 parts per 100 parts of rubber.

9. The tire of claim 8, characterized in that the composition of the sublayer (11) contains aramid fibers in a quantity in the range of 6 to 9 parts per 100 parts of rubber.

10. Tire according to any one of claims 1 to 9, characterized in that the underlayer (11) has a hardness that does not change by more than 5 units on the international scale degree of hardness in the temperature range between 23 and 100°C.

11. The tire of claim 10, wherein the hardness of the underlayer does not change by more than 1 unit on the international scale degree of hardness in the temperature range between 23 and 100°C.

12. The tire according to claim 11, characterized in that the hardness of the substrate (11) at 100°With more than 80 units on the international scale degree of hardness.

13. The tire according to item 12, characterized in that the hardness of the substrate (11) at 100°With more than 85 units on the international scale degree of hardness.

14. Tire according to any one of claims 1 to 13, characterized in that the underlayer (11) has modulus (E’) of elasticity, which does not change more than 10% in the temperature range between 70 and 100°C.

15. The tire 14, characterized in that the module (E’) elastic the spine sublayer (11) does not change by more than 5% in a temperature range between 70 and 100° C.

16. The tire 15, characterized in that the module (E’) elastic sublayer (11) is greater than 15 MPa at 100°C.

17. The tire according to item 16, characterized in that the module (E’) of elasticity greater than 20 MPa at 100°C.

18. The tire according to claim 1, characterized in that the underlayer (11) is the ratio of the load when the elongation of 10% in the radial direction to the load when the elongation of 10% in the transverse direction that is greater than 3.

19. Bus on p, characterized in that the underlayer (11) has a thickness in the range of 1.5 - 2 mm.

20. A method of manufacturing tires with high performance according to any one of claims 1 to 19, containing the stage of the formation of a skeleton with a layer (3) of the frame, overlapping the belt around the circumference of the frame that contains two or more layers (7) of the reinforcing cord yarns, parallel to each other in the layer and transversely directed in relation to the cord threads of the adjacent layer, overlay Brecker outer layer of oriented along the circumference of the reinforcing cord (8), overlay oriented along the circumference of the cord (8) tread belt (10), provided with an outer layer (12) and a sublayer (11), characterized in that the underlayer (11) made of a heat resistant compositions obtained with the use of reinforcing fibers and a cured resin.

21. The method according to claim 20, characterized in that use cured resin-based component selected from h is the prevalence of one or more of the following groups: Resorcinol®donor methylene, epoxides-dicarboxylic acid, epoxides-diamines, epoxides-polyols, alcohol-dibasic acid, and the fact that these reinforcing fibers are selected from among polyamide, polyester, polyolefin, carbon fibers, glass fibers and polyvinyl alcohol.

22. The method according to item 21, wherein the tread belt (10) is produced by joint extrusion of the outer layer (12) and substrate (11).

23. The method according to item 21, wherein the sublayer (11) is obtained by calendering.



 

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SUBSTANCE: proposed tire is provided with tread having two deep circular grooves separating central zone from two side shoulder zones furnished with shoulder blocks. Sum of width values of shoulder zones in tread is either equal to or less than 60% of its summary width. Width of each shoulder zone is not less than 20% of summary width. Each circular groove at side separated from central zone adjoins continuous path from which cross grooves branch to limit shoulder blocks.

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