LU100829B1 - SUMMIT FLAT STRIP COMPRISING DIFFERENT NYLON REINFORCEMENT CONSTRUCTIONS 6,6 - Google Patents

Abstract

A strip of cord or woven fabric for a pneumatic tire made from alternately arranged PA66 / nylon 6.6 twisted filamentary reinforcing elements having different constructions with respect to their level of torsional structure is revealed. Such a cable strand or such a woven fabric improves high-speed durability and tread separation resistance when used in the form of a spirally wound crown ply at an angle of 0 degrees on the belt package in pneumatic tires of the radial web type.

Description

SUMMIT FLAT STRIP COMPRISING DIFFERENT NYLON REINFORCEMENT CONSTRUCTIONS 6,6

DESCRIPTION

FIELD OF THE INVENTION

The present invention relates to a novel cable stripe or a new woven fabric for a pneumatic tire made from alternating nylon cords having different constructions. A new cable stripe or new woven fabric of this type for a tire improves the high-speed durability and tread separation resistance when used in the form of a web. of spirally wound vertex forming an angle equal to zero degrees on a belt package in pneumatic tires of the radial web type.

BASIS OF THE INVENTION

In high speed conditions, the outer diameter of the tire increases under the influence of the centrifugal forces generated by the tread and the bundle of belts formed by steel cords. Such an increase in the diameter or such expansion of the tire increases the pantographic movements of the cords at the edges of the belts, which gives rise to crack initiation, crack propagation and separations of the terminal edges to the belts.

On the other hand, raising the temperature at the belt edges under high speed conditions can trigger a degradation of the local adhesion of the textile crown ply strip and give rise to local separations between the tread and the summit plies, which can ultimately result in belt edge separations in a very short time based on non-uniform distributions of constraints.

The crown ply layer which wraps circumferentially around the belt package prevents excessive expansion of the tire under high speed conditions by exerting compressive forces (restriction forces) on a thick belt package consisting of layers of diagonal-ply type steel cords. In order to increase the force of restriction, webs of crowns having cords of the type with a high number of cords (high epdm value) (such as nylon, 1400 × 2, 110 epdm or nylon 1400x1, 140 epdm, etc.). At present, the most widely used materials for crown plies are multi-ply type nylon 6,6 plies or single-ply hybrid cords (e.g., hybrid aramid / nylon cords) that come into use. spiraling a package of belts at angles of 0 to 5 degrees to the equatorial plane of the tire.

Nylon cords have excellent fatigue resistance when subjected to axial flexion and compression, as well as bielastic tensile strength characteristics, making it easy to handle during the course of the process. making the tire. In addition, the generation of a thermal shrinkage force as a result of a rise in operating temperature under high speed conditions improves the resistance to belt edge separation, as well as the high speed durability.

It is well known that hybrid cords comprising high modulus and low modulus yarns having a bielastic tensile strength behavior are also used to act as crown plies in high velocity tires. The low modulus component of the hybrid cable allows for easy lifting of the belt package in the absence of excessive formation of tightly bound cords due to its high extensibility and the high modulus component proves effective under service conditions. When using hybrid cords to act as a crown ply, the total thickness of the crown ply layer as well as the rubber content can be reduced, and the high modulus component of the hybrid cord can increase the thickness of the crown ply. Restricting force and improve high speed durability.

U.S. Patent 4,284,117 discloses a nylon crown ply which is formed from individual yarns rather than from cords. The crown ply is thinner than conventional crown plies in that it has superior flexibility characteristics and superior heat dissipation.

U.S. Patent No. 5,115,853 discloses a radial ply type tire having a crown ply structure which is radially disposed outside of the belt reinforcing structure. The crown ply structure comprises side-by-side 420x2 nylon cords having a cord twist of not more than 280 rpm.

U.S. Patent No. 2006/0237113 discloses a zero degree angle belt reinforcing layer consisting of at least a first elongated member which represents a hybrid cord including at least one filament yarn. high elastic modulus and at least one filament with low elastic modulus, twisted to one another and which are arranged alternately. The elastic modulus of said at least one second elongated element is smaller than the elastic modulus of said at least one first elongated element.

In U.S. Patent 6,799,618 there is disclosed a textile crown ply structure which is superimposed radially outwardly of the belt assembly and which is reinforced with cords which are consisting of materials, including nylon and aramid. At the initial cord lengthening, the wires that support the primary load are nylon yarns and after appreciable elongation, the yarns that support the primary load are aramid yarns.

SUMMARY OF THE INVENTION

The present invention relates to a novel cord web or a new tire cord fabric comprising alternately arranged nylon 6,6 yarns having different constructions, more specifically, first yarns having two-web type constructions or three-ply and second-wired type in the form of twisted single-ply type yarns. A new strip of such woven fabric combines the high impact energy absorption properties exhibited by two-ply or three-ply-type cords and the superior initial nylon 6 twisted yarn modulus. 6 of the single-sheet type.

A new strand of cable or a new woven fabric of this type for a pneumatic tire can improve high-speed durability, tread separation resistance and impact resistance when used under the shape of a spirally wound crown ply forming a zero-degree angle on the belt package in radial-ply type pneumatic tires.

As is well known, nylon 6,6 has excellent fatigue resistance and a bielastic tensile strength, which makes possible the lifting process in the absence of tightly formed cords and which makes it possible to obtain a sufficient restriction force under high speed conditions. However, because of the low initial modulus of the nylon 6,6 cords, it is necessary to use bands or fabrics with a high epdm value (high number of cords per decimeter) in order to obtain the restraining force. sufficient for the package of belts (as can be seen in Figure 1). On the other hand, the distance from cord to rivet in such strips or fabrics is too narrow, which makes it difficult for the rubber to penetrate between the cords without premature vulcanization. In addition, cracks in the rubber can easily be triggered between cords having a narrow rivet under dynamic conditions based on high shear stresses.

In accordance with the invention, the nylon 6,6 cords having different constructions in crown ply strips have different moduli (or different LASE values) and different values of thermal shrinkage. During uplift (during expansion) during the vulcanization process, single-ply nylon 6,6-type twisted yarns (high modulus, poorly extensible cords) are subjected to a load far greater than that of wired high torsion type two or three layers (low modulus, wired highly extensible). In addition to superior cable tensile strength, the single-ply, low-twist, low-tensile nylon-type twisted yarns subjected to higher loads generate a higher thermal shrinkage force (greater contraction force) than the vulcanization temperature. Based on superior cable load and superior thermal shrinkage, single-ply nylon 6,6 twisted yarns penetrate better than two-ply or three-ply type twisted cords through the compound serving as a scrub layer.

On the basis of the difference in penetration (H) of the single-ply type twisted yarns and the two-ply or three-ply type twisted cords in the scrubbing-layer compound, the crown-type layer of the type a single sheet is transformed into a top band partly of bilayer type (corrugated) (as can be seen in Figure 2).

DEFINITIONS Wired: reinforcing element obtained by reciprocal twisting of wires of the type with two or more layers.

Denier: the weight in grams of a thread with a length of 9000 m.

Dtex: the weight in grams of a thread with a length of 10,000 m. LASE: the load at a specified elongation. LASE 7%: the load at an elongation of 7% in the load / elongation curve.

Linear density: the weight per unit length expressed in g / dtex or g / d (denier).

Restriction force: The force exerted by the crown ply on the belt pack when driving to prevent expansion of the tire.

Total Linear Density: The sum of the nominal linear densities of the strand wires of the cord. Wired type of two layers: wired that is prepared by reciprocal twisting son of two-ply type. Wired three-ply type: wired that is prepared by reciprocal twisting son of three-ply type.

Twist: the number of turns per meter (t / m or rpm).

Coefficient of torsion: rpm x dtex1 / 2.

Chain: The group of threads or cords in all woven fabrics, which extend longitudinally and parallel to the selvedge and intertwine with the filling material.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a cross-sectional view of a conventional nylon crown ply (of the prior art) on a bundle of belts made of diagonal-ply type steel cords after the vulcanization process. a represents a bundle of belts constituted by steel cords of the diagonal web type; b represents a conventional crown ply on a package of belts; c represents a tread.

FIG. 2 is a cross-sectional view of a nylon crown ply according to the invention on a bundle of belts made of diagonal-ply type steel cords, after the vulcanization process, a represents a bundle of belts. consisting of diagonal-ply type steel cords; b represents a crown ply on a pack of belts according to the invention; c represents a tread.

FIG. 3 is a cross-sectional view of nylon crown ply cords and yarn arrangements according to the invention on a bundle of diagonal web type steel cord belts, (1) before vulcanization process; (2) after the vulcanization process. A: represents a two-ply nylon 6.6 cord having a high torsion coefficient, low modulus and superior extensibility; B: represents a single-ply nylon 6.6 twisted yarn having a low coefficient of torsion, a high modulus and a lower extensibility; H: represents the difference in penetration of A and B in a rubber matrix.

Figure 4 shows the changes in the distance between one cord and another cord (rivet area, gap) after the vulcanization process; (1) before the vulcanization process; (2) after the vulcanization process: 51: cable to cable distance between A and B before the expansion and vulcanization process; 52: cable to cable distance between A and B after the expansion and vulcanization process; 53: cable to cable distance between A and A after the expansion and vulcanization process; 54: cable distance to wired between B and B after the expansion and vulcanization process;

FIGS. 5 and 6 are similar to FIGS. 3 and 4, but with single-ply nylon 6.6 twisted yarns having a lower dtex value; (1) before the vulcanization process; (2) after the vulcanization process.

Figure 7 shows 1 + 2 + 1 arrangements of yarns and cords of crown plies; (1) before the vulcanization process; (2) after the vulcanization process: (1) arrangement of cords A + B + B + A + B + B + A + ... before the expansion and vulcanization process; (2) arrangement of cords A + B + B + A + B + B + A + ... after the expansion and vulcanization process.

Figure 8 shows 2 + 1 + 2 arrangements of yarns and cords of crown plies; (1) before the vulcanization process; (2) after the vulcanization process: (1) arrangement of cords A + A + B + A + A + B + A + A + ... before the expansion and vulcanization process; (2) arrangement of cords A + A + B + A + A + B + A + A + ... after the expansion and vulcanization process.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with the invention, crown ply webs or crown ply fabrics spirally wound on circumferentially-radial-ply tire-type tire belt packages having nylon 6,6 cords and yarns. 6-ply, single-ply type, as a warp: improve high-speed durability based on the medium-to-high modulus of the web and on the basis of longer distances from cord to wire and from wire to wire ( by decreasing the shear stresses) because of vertical shifting of the yarns (formation of two layers or zigzag pattern, as can be seen in Figures 3, 4, 5 and 6); improve the shock resistance of the belt package on the basis of superior energy absorption by high torsion-type and highly extensible nylon cords (higher-level cords are more impact-sensitive and hard-wired lower level are more sensitive to the expansion of the tire); and also improve the separation resistance between the tread and the crown plies by virtue of the corrugated surface structure of the crown ply. The zigzag configuration of the surface also improves the mechanical bond between the crown ply compound and the tread compound.

The nylon 6,6 cords have two-ply or three-ply type cord constructions. The son arranged alternately represent twisted son of the single-sheet type. The angle formed by the strips of crown plies spirally wound with respect to the medial circumferential line (or with respect to the equatorial plane of the tire) rises from 0 to 5 °.

In order to achieve the advantages mentioned above, the torsion coefficient of the nylon cords 6.6 determined in accordance with the formula (1a) shown below amounts to at least 10,000. and up to 15,000.

Coefficient of torsion = twist of the cord (rpm) x (total linear density of the cord expressed in dtex) 1/2 (1a)

According to the similar formula given below (1b), the twist coefficient of the single-ply type twisted wire is at least 5000 and at most 8000.

Coefficient of torsion = yarn twist of yarn (rpm) x (linear density of yarn expressed in dtex) 1/2 (1b).

In accordance with the invention, the torsional coefficient of the single-ply type nylon 6,6 twisted yarn is at least 5,000 units less than the twisting coefficient of the cord in the same crown ply web (for example). example 1400x2, 250/250 rpm and 1400x1, 180 rpm).

When the torsional coefficient difference is less than 5000 units, the corrugated crown sheet surface can not be obtained on the tire belt package.

According to the invention, the total linear density of the cord is at least 700 dtex and at most 5000 dtex and the total linear density of the single-ply type twisted wire is at least 350 dtex and maximum at 3000 dtex. These linear density limits prevent excessive cuts of rubber and excessively high thicknesses of the rubber. Excessive cuts in the rubber may give rise to contact between the crown ply cords and the yarns on the one hand, and the steel cords of the belt layers on the other, as well as to ruptures induced by the cords. abrasion. Too high a rubber thickness in the crown area results in high heat build-up and greater rolling resistance.

The linear density of single-ply type twisted wires is at most 50% less than the total linear density of the cord.

According to the invention, the sequence of cords and yarns which are parallel to each other in a crown ply band, represents an alternate form as follows: A + B + A + B + A + B +. etc., in which A is a double-ply or three-ply-type nylon 6.6 cord and B is a single-ply type nylon 6,6 twisted yarn (as can be seen from FIG. in Figures 3, 4, 5 and 6). Such a web of crown ply makes it possible to obtain a uniform corrugated surface after the vulcanization process, which strongly binds to the tread compound by improving the resistance to the separation of the tread under conditions of great speed.

In accordance with the invention, the sequence of cords and yarns, which are parallel to each other in a crown ply band, represents an alternate form as follows: A + B + B + A + B + B + A + B + B + ... etc., wherein A is a two-ply or three-ply type 6.6 nylon cord and B is a single-ply type nylon 6.6 twisted cord. tablecloth (as can be seen in Figure 7).

According to the invention, the sequence of cords and yarns, which are parallel to each other in a crown ply band, represents an alternate form as follows: A + A + B + A + A + B + A + A + B + ... etc., wherein A is a two-ply or three-ply type nylon 6,6 and B is a single-ply type nylon 6,6 twisted yarn tablecloth (as can be seen in Figure 8).

According to the invention, the number of cable ends in the strip amounts to at least 70 epdm (ends per decimeter). In the case of numbers of cable ends with a value of less than 70 epdm, the effectiveness of the surface corrugation is not sufficient to obtain a mechanical connection to the tread.

According to the invention, the width of the strips of crown plies is between 8 and 25 mm, preferably between 10 and 15 mm.

Claims (13)

1. A crown ply web made from nylon 6,6 cords and alternately woven single-ply nylon 6,6 twisted yarns which wrap circumferentially around a package of belt of a pneumatic tire of radial ply type, characterized in that the torsion coefficient of said nylon cords 6.6, which is determined according to the formula shown below: torsion coefficient = twist of the cord (rpm) x (total linear density of the cord expressed in dtex) 1/2 is at least 10,000 and at most 15,000; the torsion coefficient of said single-ply type nylon 6,6 twisted yarn is at least 5,000 units less than the torsion coefficient of said nylon cord 6,6 in the same crown ply band The crown ply web of claim 1, wherein said nylon strands 6,6 are two-ply type cords. The crown ply web of claim 1, wherein said nylon 6,6 cords are three-ply type cords. The crown ply web of claim 1, wherein the torsion coefficient of said single ply nylon 6.6 twisted yarn, which is determined according to the formula shown below: torsion coefficient = yarn count twist (rpm) x (linear yarn density expressed in dtex) 1/2; is at least 5000 and at most 8000. The crown ply web of claim 1, wherein the linear density of said nylon 6,6 cords is at least 700 dtex and at most 5,000 dtex. The crown ply web of claim 1, wherein the linear density of said single-ply nylon 6,6 twisted yarn is at least 350 dtex and at most 3000 dtex. The crown ply web of claim 1, wherein the linear density of said single-ply type nylon 6,6 twisted yarn is not less than 50% of the total linear density of said nylon cord 6. 6. A crown ply web according to claim 1, wherein the arrangement of said nylon strands 6,6 (A) and said single ply nylon (6,6) twisted yarns in said web is such as indicated below A + B + A + B + A + B, etc. The crown ply web of claim 1, wherein the arrangement of said nylon strands 6,6 (A) and said single ply nylon (6,6) twisted yarns in said web is such as indicated below A + B + B + A + B + B + A + B + B + A, etc. A crown ply web according to claim 1, wherein the arrangement of said nylon strands 6,6 (A) and said single-ply type nylon (6,6) twisted yarns in said web is such as indicated below A + A + B + A + A + B + A + A + B, etc. The crown ply web of claim 1, wherein the number of cords ends in said web is at least 70 epdm (ends per decimeter). The crown ply web of claim 1 wherein the width of said crown ply web is at least 8 mm and at most 25 mm. The crown ply web of claim 1 wherein the width of said crown ply web is at least 10 mm and at most 15 mm.