阅读说明：本技术 高性能尼龙轮胎帘线 (High-performance nylon 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尼龙织物(复丝)帘线,该帘线在帘线中的合股纱线中具有残余捻度,该帘线用作斜交和子午线飞行器以及越野轮胎中的增强件。(The present invention relates to a two or three ply nylon textile (multifilament) cord having residual twist in the ply yarn in the cord for use as reinforcement in bias and radial aircraft and off-road tires.)

1. A two-or three-ply high performance nylon 6.6 tire cord characterized in that,

-the residual ply yarn twist in the cord is higher than 30 tpm and lower than 120 tpm,

-and the cord twist opposite to said residual twist direction is higher than 200 tpm and lower than 400 tpm.

2. The two or three ply high performance nylon 6.6 tire cord according to claim 1 wherein the total nominal linear density of the cord is above 2500 dtex and below 9000 dtex.

3. The two or three high performance nylon 6.6 tire cord 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 nylon 6.6 tire cord of claim 1 wherein the ply yarn in the cord is nylon 6.

5. The two or three ply high performance nylon 6.6 tire cord of claim 1 wherein the ply yarn in the cord is nylon 4.6.

6. The two or three ply high performance nylon 6.6 tire cord according to claim 1, wherein the cord is used as carcass reinforcement in bias and radial aircraft tires.

7. The two or three ply high performance nylon 6.6 tire cord of claim 1 wherein the cord is used as carcass reinforcement in bias and radial off-road 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 cords used as reinforcement in bias and radial aircraft and off-road 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 filament bundles 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 passages) 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 a twist different from each other, 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 our 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) 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 highly dip-penetrated cords are their high bending stiffness and reduced breaking strength after the dipping 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 yarn twist in the opposite direction of the cord twist. In other words, in the preparation step, the strand (yarn) twist is always higher than the cord twist but in the opposite direction. The primary carcass reinforcements in aircraft and off-road tires are nylon cords (e.g., nylon 6 and nylon 6.6).

According to the invention, the filament bundles in such nylon cord strands are not open (zero twist), but are tight at 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) 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 maximum residual twist difference between the cord plies is less than 15%.

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

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 a 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

1-prior art S-twisted cord (balanced twist, Z twist of plied yarn equal to S twist of cord);

2-S-twisted cord with residual Z-twist according to the invention (unbalanced twist, Z-twist of plied yarn is greater than S-twist of cord).

FIG. 2 is a comparison of prior art and Z-twisted cords according to the invention, wherein

3-prior art Z-twisted cord (balanced twist, S twist of plied yarn equal to Z twist of cord);

4-Z-twisted cord with residual S twist according to the invention (unbalanced twist, S twist of plied yarn is greater than Z twist of cord).

Fig. 3 is a cross-sectional view of a 2-ply cord, wherein,

5-2 strands of prior art cord with balanced twist having a circular shape;

6 and 7 are crescent-shaped cord strands;

8-a cross-sectional view of a 2-ply cord according to the invention;

9 and 10-strands with a circular cross section with residual twist in the cord according to the invention.

Fig. 4 is a cross-sectional view of a 2-ply cord, wherein,

11-cross-section view of a 2-ply cord according to the invention (treated under high tension);

12 and 13-strands with an elliptical cross-section with residual twist in the cord according to the invention.

FIG. 5 is a cross-sectional view of a 3 ply cord wherein:

14-3 ply prior art cord with balanced twist with round shape;

15. 16 and 17-triangular shaped strands of prior art cord;

18-cross-section of a 3-ply cord according to the invention;

19. 20 and 21-strands with a circular cross section with residual twist in the cord according to the invention.

FIG. 6 is a cross-sectional view of a 3 ply cord wherein;

22 is a cross-sectional view of a 3-ply cord according to the invention (treated under high tension),

23. 24 and 25 are strands with an elliptical cross-section with residual twist in the cord according to the invention.

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).

6.6 parts of nylon: polyhexamethylene adipamide.

Nylon 6: polycaprolactam.

Nylon 4.6: polytetramethylene adipamide.

Residual twist (Residual twist): the resultant twist of the yarns of the ply yarn of the cord (strand twist-cord twist).

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

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 overall linear density of the high performance cord according to the invention is more than 2500 dtex and less than 9000 dtex in the opposite direction of the cord twisting direction.

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

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

The plied yarns in the high performance cord according to the invention consist of nylon 6.6, nylon 6, nylon 4.6 or mixtures thereof.

The high performance cord according to the invention is used as carcass reinforcement in radial and bias aircraft and off-road tires.