A PLIED TWISTED CAP PLY REINFORCEMENT HYBRID YARN

Abstract

The present invention relates to a cap ply reinforcement hybrid yarn (1) which is located between the tread and the belt package especially in radial passenger vehicle tires, which improves the high speed durability of the tire by using polyamide (N)/polyester (P) yarns, and which provides fuel saving by decreasing the rolling resistance.

Claims

1. A cap ply reinforcement layer located between at least one tread and one belt package layer of a pneumatic radial tire, comprising at least two types of plied twisted yarns obtained by combining two non-twist yarns with each other in one direction, wherein a first type of the two types of the plied twisted yarns is aliphatic polyamide yarn, and a second type of the two types of the plied twisted is polyester yarn, and a ratio of polyester in the polyester yarn is minimum 90% by weight, and a ratio of aliphatic polyamide in the aliphatic polyamide yarn is minimum 90% by weight.

2. A cap ply reinforcement layer according to claim 1, wherein the aliphatic polyamide yarn is nylon, and the polyester yarn is polyethylene terephthalate.

3. (canceled)

4. A cap ply reinforcement layer according to claim 2, wherein the aliphatic polyamide yarn is nylon 6.

5. A cap ply reinforcement layer according to claim 2, wherein a content of the aliphatic polyamide yarn is comprised of a blend of nylon 6.6 and nylon 6.

6. A cap ply reinforcement layer according to claim 1, wherein linear density of each one of the aliphatic polyamide yarn and the polyester yarns are is in a range of 200-3000 dtex.

7. A cap ply reinforcement layer according to claim 1, wherein a difference between the linear densities of the aliphatic polyamide yarn and the polyester yarns is maximum 20%

8. A cap ply reinforcement layer according to claim 1, wherein both the aliphatic polyamide yarn and the polyester yarn have a pre-twisting level value of zero.

9. (canceled)

10. (canceled)

11. A cap ply reinforcement layer according to claim 1, wherein a piled twisting level of the aliphatic polyamide yarn and the polyester yarns is in a range of 100-500 tpm.

12. A cap ply reinforcement layer according to claim 1, wherein a piled twisting level of the aliphatic polyamide yarn and the polyester yarn is in a range of 150-250 tpm.

13. A cap ply reinforcement layer according to claim 1, wherein a plied twisting direction of the aliphatic polyamide yarn and the polyester yarn is Z when the aliphatic polyamide yarn and the polyester yarn twisted together.

14. A cap ply reinforcement layer according to claim 1, wherein a plied twisting direction of the aliphatic polyamide yarn and the polyester yarns is S when the aliphatic polyamide yarn and the polyester yarn twisted together.

Description

SUMMARY OF THE INVENTION

[0020] The objective of the present invention is to provide a cap ply reinforcement hybrid plied yarn which forms the layer located between the tread and the belt package in radial tires used in motor vehicles, and which is obtained by plied twisting at least two different yarns together.

DETAILED DESCRIPTION OF THE INVENTION

[0021] A cap ply reinforcement hybrid yarn developed to fulfill the objectives of the present invention is illustrated in the accompanying FIGURE, in which:

[0022] FIG. 1 is the view of the plied twisted hybrid yarn used in the inventive cap ply reinforcement hybrid yarn.

[0023] The components shown in the figures are each given reference numbers as follows:

[0024] 1. Cap ply reinforcement hybrid yarn

[0025] N. Aliphatic Polyamide

[0026] P. Polyester

[0027] The textile reinforcement layer located between the upper layer of the belt package and the tread is called as cap ply reinforcement layer. The advantages and disadvantages of the applications used for this layer in the previous technique are explained. In our invention, the negative aspects caused by the reinforcements used in cap ply layer applications are solved by the reinforcing plied twisted hybrid yarn formed by twisting the yarns having different characteristics together.

[0028] You can find the definitions of several terms used in the description while disclosing the invention.

[0029] Polyester (P) is a class of polymers or in details they are the condensation polymers comprising ester functional groups in polyester main bonds. Even though the polyesters are available in nature, the polyester generally expresses a wide range of products belonging to synthetic polyesters (P) comprising all polyethylene terephthalate and polycarbonate. Polyethylene terephthalate (PET) is the most commonly used polyester type in tire industry.

[0030] Polyamide is also known as nylon, and it refers to the most commonly known nylon fiber. The most commonly known and used three main molecule compositions are nylon 6, nylon 6.6, and nylon 4.6. Polyamide is flexible, and for this reason it is more resistant to fatigue. Polyester is less flexible, and its modulus is higher than the said nylon types.

[0031] Dtex refers to the weight of a yarn in length of 10.000 as gram. It is the unit of the yarn thickness, in other words it is the unit of its linear density.

[0032] Carcass enables the pressurized air carrying the load in the tire to be kept inside the tire. The carcass is obtained by placing textile or steel cords into rubber matrix. The cords forming the carcass provides coupling with the bead by being wrapped around the bead wire.

[0033] Bead enables the tire to contact and connect to the wheel rim, it is manufactured from steel wires and it has an annular structure.

[0034] The part of the tire contacting the road is called as tread.

[0035] Belt is the structure on the body layers extending with 90 angle from bead to bead, making acute angle with the equatorial plane present only on the tread area, and comprised of steel cords parallel to each other formed of generally two layers. The belt package formed of two layers on the tread area and the carcass is around the tire as ring. The parallel cords on the belt layer can be woven or non-woven, and it is inclined relative to the equatorial plane of the tire.

[0036] Equatorial plane is the plane vertical to the rotational axis of the tire and passing through the center of the tire tread.

[0037] Twist can be defined as bending the yarn around its own axis or the number of helix spirals in a certain length on the yarn. The number of twists in the yarn influences the yarn characteristics such as elasticity and fatigue resistance. The twist level is expressed with the number of rounds per meter, and it is shown as tpm.

[0038] Plied twisting is defined as twisting more than one yarns which have no pre-twisting. The plied twisted yarn is obtained by combining yarns (non twisted yarns) with each other which are not twisted separately and then the said non twisted and combined yarns are twisted together in one direction. The twisting direction may be S or Z.

[0039] Pre-twisting is the protective twist given to the yarn in yarn production. The yarn producers generally do not apply twisting process on the said yarn.

[0040] The present invention relates to obtaining a plied twisted hybrid yarn having optimal characteristics which form the cap ply reinforcement layer located between the tread and belt package for the radial passenger vehicle tires.

[0041] In the inventive cap ply reinforcement hybrid yarn (1), aliphatic polyamide (N) and polyester (P) are twisted together, and thus plied twisted hybrid yarn is obtained and the cap ply reinforcement layer is obtained from this yarn. In one embodiment of the invention, nylon 6.6 can be given as example for aliphatic polyamide (N), and polyethylene terephthalate (PET) can be given as example for polyester (P) yarn. The invention cannot be limited to the abovementioned examples, and it is mainly as it is described in the claims.

[0042] In the inventive cap ply reinforcement hybrid yarn (1), plied twisted hybrid yarn is obtained by twisting aliphatic polyamide (N) and polyester yarns together, one the said yarns is aliphatic polyamide (N) and the other one is polyester (P); and the ratio of the polyester (P) in the said polyester (P) yarn is minimum 90% by weight, and the ratio of aliphatic polyamide (N) in the said aliphatic polyamide (N) yarn is minimum 90% by weight.

[0043] In the current technique, only polyester (P) cord or hybrid yarn or cord use is seen. In this invention, two different yarns are subjected to plied twisting process together. By this means, the possible disadvantages occurring while they are being used on their own are eliminated, and the advantages are combined and the production of tire providing high speed performance is aimed. The effective modulus (elasticity) of the nylon/PET hybrid yarn is much higher than the hybrid cords comprising nylon and PET yarn in equal dtex value and in the same helix angle. The effective modulus being high allows the use of thinner yarns on the cap ply reinforcement layer, thereby reducing the amount of the rubber on the cap ply and reducing the rolling resistance and heating of the tire. Under dynamic conditions, the temperature being lower on the belt package, especially at the edge of the belt package delays the separation from the cap edge, and enables the tire life to increase.

[0044] In the inventive cap ply reinforcement hybrid yarn (1), since twisting process is applied on nylon 6.6/PET (aliphatic polyamide (N)/polyester (P)) hybrid yarns at once, energy required for twisting process is saved. There is no need to apply twisting process on the yarns again.

[0045] In a preferred embodiment of the invention, nylon 6.6 and PET yarns are connected/plied parallel to each other, and they are subjected to twisting process together. Single twisted yarn is obtained after twisting process, and it is called as plied twisted hybrid yarn.

[0046] NY940/PET1100, NY1400/PET1440, NY1880/PET1670 and NY2100/PET2200 can be given as examples for plied twisted hybrid yarn constructions to be used for this aim. The invention cannot be limited to the above mentioned examples, and it is mainly as it is described in the claims.

[0047] In one embodiment of the invention, yarn comprised of filaments obtained from the mixture of nylon 6.6 and nylon 6 polymers can be given as example for aliphatic polyamide (N) yarn.

[0048] The linear densities of each one of the aliphatic polyamide (N) and polyester (P) yarns forming the said cap ply reinforcement hybrid yarn (1) can vary between 200-3000 dtex values.

[0049] The difference between linear densities of each one of the aliphatic polyamide (N) and polyester (P) yarns forming the inventive cap ply reinforcement hybrid yarn (1) is maximum 20%. In one embodiment of the invention, the linear density difference between nylon 6.6 and PET should not exceed the ratio of 20%. In case the said difference is bigger, at the end of the thermal treatment applied during production, the diameter growth is experienced due to the asymmetry increasing in the yarn diameter, and this situation causes quality errors.

[0050] In the inventive cap ply reinforcement hybrid yarn (1), the plied twisting levels of the plied twisted hybrid yarns formed by twisting the aliphatic polyamide (N) and polyester (P) together can vary in range of 100 to 500 tpm. The best result is obtained in range of 150-250 tpm.

[0051] In one embodiment of the cap ply reinforcement hybrid yarn (1), nylon and PET yarns are twisted together, and thus plied twisted hybrid yarn is obtained. In yarn twisting applications, the twisting direction of yarns used in cord production and other textile yarns are expressed with S and Z letters. When the yarn is twisted in S direction, and the yarn is held vertically; a spiral is twisted in same direction with the middle part of letter S around the middle axis curve of the yarn. When the yarn is twisted in Z direction, the yarn twist direction shows inclination towards the middle part of letter Z.

[0052] In our invention, if pre-twisting process is applied on the said yarns before aliphatic polyamide (N) and polyester (P) yarns twisted together; the pre-twisting directions of the yarns are similar, in any one of Z or S directions. When the said yarns are twisted together, again the twisting directions are same, in any one of Z or S directions. In other words, the plied twisting direction of the yarns is same as the pre-twisting direction.

[0053] In the preferred embodiment of the invention, generally there is no pre-twisting of polyamide and polyester yarns in hybrid yarns. If the yarns are pre-twisted, the twist level is maximum 100 tpm. As the pre-twist level increases, the characteristic of the yarn changes, its elasticity reduces and it elongates. In a preferred embodiment of the invention, the pre-twisting levels of the yarns are zero, in other words pre-twisting is not applied.

[0054] In one embodiment of the invention, adhesive is used in order to enable the hybrid yarns to be adhered to the rubber. The said adhesives are preferred to be RFL (resorcinol, formaldehyde, and latex) based or adhesives that do not comprise resorcinol or formaldehyde (for example comprising acrylic resin instead of RF) in range of 2% to 10% on plied twisted hybrid yarn surfaces.