阅读说明：本技术 高性能聚酯轮胎帘线 (High performance polyester tire cord ) 是由 S路璐逛腹 S·费丹 于 2018-11-28 设计创作，主要内容包括：本发明涉及两股或三股聚酯帘线,其具有帘线中的合股纱线中的残余捻度,该帘线被用作乘用车和轻型卡车轮胎中的胎体增强件。(The present invention relates to two or three ply polyester cords having residual twist in the ply yarn in the cord used as carcass reinforcement in passenger and light truck tires.)

1. A two-or three-ply high performance polyester tire cord characterized in that,

the residual ply yarn twist in the cord is above 30 tpm and below 120 tpm,

and the cord twist in the opposite direction of the residual twist is higher than 200 tpm and less than 400 tpm.

2. The two or three ply high performance polyester tire cord according to claim 1 wherein the total nominal linear density of the cord is above 1500 dtex and less than 8000 dtex.

3. The two or three high performance polyester tire cords of claim 1, wherein the maximum linear density difference between the plied yarns is less than 10%.

4. The two or three ply high performance polyester tire cord according to claim 1 wherein the plied yarns in the cord are PET.

5. The two or three high performance polyester tire cords of claim 1, wherein the plied yarns in the cord are PEN.

6. The two or three ply high performance polyester tire cord according to claim 1 wherein the cord is used as carcass reinforcement in passenger vehicle tires.

7. The two or three ply high performance polyester tire cord according to claim 1 wherein the cord is used as carcass reinforcement in light truck tires.

Technical Field

The present invention relates to two or three ply (ply) polyester textile (multifilament) cords having residual twist in ply yarns (ply yarns) in the cord, which are used as reinforcement in radial passenger and light truck tires.

Background

Conventional textile tire reinforcement cords consist of yarns (strands) pre-twisted in one direction (Z or S), which are again twisted together in the opposite direction (cable or cord twist in the S or Z direction). Typically, those cords have a balanced twist construction, with yarn or strand twist equal to the cable or cord twist.

In such cord constructions, the residual or synthetic yarn twist in the cord becomes zero due to untwisting during twisting of the cord or cable in the opposite direction. The zero twist or untwisted plied yarns in the cord have loose parallel bundles of filaments with an open structure.

The main advantages of this cord construction are its simple production, and its high breaking strength (due to the parallel filaments in the cord plies). The breaking strength advantage is only valid for greige or unbleached (undipped) cords. After the dipping process, such cords undergo a significant reduction in breaking strength due to the dipping penetration of the adhesive between the interstices (void channels) of the filament bundles.

According to US 4,877,073, two strands of nylon 6.6 cord, in which the first and second strands (yarns) have mutually different twists, have been proposed as low angle overlays (cap ply), which improve uniformity due to their high initial ductility (low modulus). Such cords achieve a high process expansion during moulding and curing without forming excessively compact cords, but are not very effective in preventing growth (growth) of the tyre under high speed conditions, due to their low modulus. In addition, such cords have an asymmetric structure, resulting in uneven stress distribution (load sharing) between the cord strands, and also have a tendency to buckle under axial compression, resulting in early cord failure.

According to US 6,959,534, to reduce twisting costs, the yarns (strands) are twisted at a lower level than the cord twist (resulting in internal cord torque), and it has been proposed to alternate S and Z twisted cords in tire cord fabrics to address curling or end lift issues in calendered fabrics. Based on this patent, the yarn twist is always less than the cord twist, and the residual yarn (strand) twist is in the same direction as the cord twist, resulting in high torsional instability. In the present invention, the yarn twist is always higher than the cord twist.

Disclosure of Invention

Conventional textile cords with balanced strand and cord twists (with hundreds of individual parallel filaments) for use as tire reinforcements have an open strand structure in the form of a greige prior to the dipping process.

As previously mentioned, during dipping in an adhesive (RFL or prepreg) solution, such cords are subject to high levels of dip (adhesive) penetration in the interstices between the filaments in each strand of the cord, even under high cord tensions applied to the cord.

Two major drawbacks of such high dip penetration cords are their high bending stiffness and reduced breaking strength after dip and hot drawing processes. Under cyclic tension and compression, cords with higher bending stiffness are subject to filament damage, which results in reduced retained (retained) strength. On the other hand, lower initial cord strength requires higher cord density (epdm) or thicker cords in the carcass layer in order to provide sufficient burst strength in the tire. A higher cord density (epdm) means a lower cord-to-cord distance in the tire (narrow rivet point (rivet) area), which has a high crack initiation potential between the cords due to high shear stress under dynamic conditions. On the other hand, thicker cords require higher rubber gauge, resulting in increased rolling resistance in the tire.

The High Performance (HP) textile cord structure according to the invention includes a sufficient level of residual ply twist in the opposite direction of the cord twist. In other words, in the preparation step, the strand (yarn) twist is higher than the cord twist but in the opposite direction. The main conventional carcass reinforcement in passenger car and light truck tires is polyester cord (e.g. PET, PEN).

According to the invention, the filament bundles in the polyester cord strand are not open (zero twist), but are tight at the residual twist and have a closed bundle structure.

Detailed description of the invention

During the dipping process of such a greige cord with tight and closed filament bundles as the strands in the cord, the adhesive dip (RFL or prepreg) cannot penetrate into the depth of the cord strand but accumulates on the cord surface, which results in a low bending stiffness after drying and heat-setting steps, which is important for improved fatigue resistance and breaking strength retention.

The residual twist levels in the strands of the textile cord according to the invention are equal to each other, but in the opposite direction of the cord twist (fig. 1 and 2).

The strands of the high performance textile cord according to the present invention have a circular (9 and 10 in fig. 3, 19, 20 and 21 in fig. 5) or elliptical (12 and 13 in fig. 4, 23, 24 and 25 in fig. 6) cross-section instead of the crescent (6 and 7 in fig. 3 and 4) or triangular cross-section of the 2 and 3 conventional cords.

As can be seen from fig. 3, 4, 5 and 6, the circumference of the high performance cord is much higher than that of the conventional cord. In other words, the high performance cord has a much higher contact surface (adhesion interface) with the rubber matrix in the tire than the conventional cord having the same total cord dtex and strand count. This increase in contact surface achieves more efficient stress transfer between the cord strands and the rubber matrix under dynamic conditions, resulting in improved tire durability.

The strands of high performance cord with residual twist become more closed and tight during the heat-setting process due to their heat shrinkage in the transverse direction, which improves strand stability.

Drawings

Illustrating the cord construction and its strand composition according to the present invention. In the drawings, wherein:

FIG. 1 is a comparison of prior art and S-twisted cords according to the invention, wherein

Detailed Description

Definition of

Cord (Cord): a reinforcing element formed by twisting together two or more plied yarns.

Cord strand (Cord ply): the basic yarn composition of the cord.

Dtex (Dtex): grammage of a yarn of 10000 meters in length.

Linear density (Linear density): the weight per unit length is given in units of g/dtex or g/d (denier).

PET: polyethylene terephthalate.

PEN: polyethylene naphthalate.

Residual twist (Residual twist): the resultant twist of the plied wires of the cord (strand twist-cord twist).

Bus density (Total linear density): the sum of the nominal linear densities of the 5 plied yarns of the cord.

2 ply cord (Two-ply cord): a cord prepared by twisting two plied yarns together.

3 ply cord (Three-ply cord): a cord prepared by twisting three plied yarns together.

Twist (Twist): number of turns per meter (t/m or tpm)

The residual twist can be calculated according to the following formula:

residual twist (tpm) = (strand twist-cord twist) (1)

The high performance cord according to the invention has a total linear density of more than 1500 dtex and less than 8000 dtex.

The linear density of the cord plies according to the invention is equal.

The maximum difference in linear density between the strands of the cord according to the invention is less than 10%.

The ply in the high performance cord according to the invention is PET.

The plied yarn in the high performance cord according to the invention is PEN.

The high performance cords according to the invention are used as carcass reinforcement in passenger car and light truck tires.