A novel polyethylene terephthalate carcass and cap ply reinforcement

Abstract

This invention is related to a novel polyethylene terephthalate carcass and cap ply reinforcement, which has high tenacity, and high Initial-Low final Modulus (LASE) PET and a manufacturing process thereof.

Description

[0001] A NOVEL POLYETHYLENE TEREPHTHALATE CARCASS AND CAP PLY REINFORCEMENT

[0002] Field of the Invention

[0003] This invention is related to a novel polyethylene terephthalate carcass and cap ply reinforcement, which has high tenacity, and high Initial-Low final Modulus (LASE) PET and a manufacturing process thereof.

[0004] Background Art

[0005] The most common tires such as ones used for passenger cars and light commercial vehicles are in the trend of change, because of environmental concerns, governmental and government initiatives, on emission, fuel economy and noise, or directly the cost of the material. The regulations demanding higher fuel economy are possibly the most immediate and important driver of change. Furthermore, tires are subject to a different working kinetics in in case of long periods of inactivity. Flat spot stands out as one of the main problem that tire manufacturers observe in overseas shipments. As a raw material of tire, polyethylene terephthalate yams should be tougher to keep tire uniform for less fuel consumption and emission release, increase burst performance. In addition, the fatigue performance of tire should be improved for longer tire lifetime.

[0006] The carcass is one of the most important parts of a radial tire and it transfers all forces from the road surface to the rim, interact with the belt package and provide flexible sidewalls. As the carcass greatly influences handling, comfort and safety, its reinforcement plays an essential role with respect to the quality of the tire and thus to its performance and durability. The tire manufacturers intend to reduce reinforcement material in tire weight by using lower denier yarns, high tenacity and load at specific elongation PET, High Initial-Low final Modulus (LASE) PET materials.

[0007] Despite recent substantial increases in the cost of starting materials of many organic fibers, the cost of starting materials of polyethylene terephthalates (especially polyethylene terephthalate) has been lower and this stable price of polyethylene terephthalates is expected to be sustained in the future.

[0008] The United States patent application No. US6887414 B2 known in the art discloses the high tenacity polyethylene terephthalate filaments, which are useful in industrial applications, such as a tire cord for reinforcing rubber, a seat belt, a V-belt, and a hose. According to the document, efforts have been made to improve physical properties of a high tenacity industrial yam, in particular, a toughness of a treated cord and a dimensional stability, useful as a fiber reinforcement in a rubber tire. A method for producing high strength and low shrinkage polyethylene terephthalate fibers with a uniform fineness and physical properties are stated in this patent.

[0009] The United States patent application No. US4827999 A known in the art discloses a polyethylene terephthalate fiber having excellent thermal dimensional stability, chemical stability, as well as high tenacity, and to a process for the production thereof. In spite of recent significant increases in the cost of the starting materials of organic fibers, for example nylon 6, the cost of the starting materials of polyethylene terephthalates (particularly of polyethylene terephthalate), has increased less and it is expected that this stable cost of polyethylene terephthalates will be maintained in future. This fact may promote enlarged demand for polyethylene terephthalate high tenacity yarns. A polyethylene terephthalate fibre having excellent thermal dimensional stability and chemical stability as well as high tenacity, which is a drawn yam produced by melt-spinning a polyethylene terephthalate comprising predominantly polyethylene terephthalate, solidifying the spun yarn and then drawing the yam. The polyethylene terephthalate has specified properties such as intrinsic viscosity, diethylene glycol content, and carboxyl group content. The yarn has specified properties such as average birefringence; yam tenacity and difference of average birefringence between surface and center of monofilament, and further low dry heat shrink and work loss when heat-treated. The spinning and drawing are conducted under specified conditions. The resultant polyethylene terephthalate fiber is useful as a reinforcement for rubber goods, specifically as a tire cord. The European patent application No. EP0080906 Bl known in the art discloses a usege of a polyethylene terephthalate tire cord fiber which has specified properties such as intrinsic viscosity, diethylene glycol content, and carboxyl group content, and the yarn has specified properties such as average birefringence, yam tenacity and difference of average birefringence between surface and center of monofilament, and further low dry heat shrink and work loss when heat-treated.

[0010] The United States patent application No. US6828021 B2 known in the art discloses a polyethylene terephthalate multifilament yarn with high modulus and low shrinkage particularly useful for the textile reinforcement of tires. The yam of the invention provides high tenacity while maintaining or increasing dimensional stability with amorphous orientation function of less than about 0.75. The described polyethylene terephthalate fiber of this invention is produced with drawing under heated conditions has higher crystalline and amorphous orientation, in other words higher birefringence than that of conventional tire grade PET fibers.

[0011] Summary of the Invention

[0012] The objective of this invention is to obtain a novel polyethylene terephthalate carcass and cap ply reinforcement, which has high tenacity, and high Initial-Low final Modulus (LASE) PET.

[0013] Detailed Description of the Invention

[0014] The ‘M Novel Polyethylene Terephthalate Carcass and Cap Ply Reinforcement” developed to fulfill the objectives of the present invention is clarified such that there is no limiting effect for the sake of better understanding.

[0015] The present invention relates to a novel polyethylene terephthalate tire cord reinforcement which has high tenacity tensile properties, comprises cord plies that have drawn polyethylene terephthalate yams comprising at least 90 mol percent polyethylene terephthalate with minimum 7.0g / dtex tenacity has an initial 3% LASE / final 3% LASE ratio which is greater than 1,5 and linear density of said yarn is minimum 300 dtex and maximum 4600 dtex. LASE (Load At Specified Elongation) is a feature of cord that represents resistance against elongation. The value of 3% LASE / final 3% LASE ratio being grater than 1,5 shows dimensional stability of cord and higher impact resistance and fatigue resistance.

[0016] In one of the embodiment of the invention, the said drawn polyethylene terephthalate has an initial 3% LASE / final 3% LASE ratio which is greater than 1,5. In one of the embodiment of the invention, the ratio of the initial 3% LASE / final 3% LASE is preferably greater than 2,0.

[0017] In one of the embodiment of the invention, the two or three ply twisted cords made of the said polyethylene terephthalate yams as dipped and heat-set have an initial 3% LASE / final 3%LASE ratio which is greater than 1,5, preferably greater than 2,0.

[0018] In one of the embodiment of the invention, the said novel polyethylene terephthalate tire cord reinforcements are used for reinforcement in pneumatic tires as carcass.

[0019] In one of the embodiment of the invention, the said novel polyethylene terephthalate tire cord reinforcements are used for reinforcement in pneumatic tires as cap ply.

[0020] The following technical results have been found in line with the parameters of the polyethylene terephthalate tire cord reinforcement obtained within the scope of the invention, High Tenacity -Low final Modulus PET.

[0021] A multifil polyethylene terephthalate multifilament yarn comprising at least 90 mol percent polyethylene terephthalate with minimum 7.0g / dtex tenacity has an initial 3% LASE / final 3% LASE ratio which is greater than 1,5. The ratio of the initial 3% LASE / final 3% LASE of this invention is preferably greater than 2,0. The two or three ply twisted cords made of the said polyethylene terephthalate yams in part a as dipped and heat-set have an initial 3% LASE / final 3%LASE ratio which is greater than 1,5, preferably greater than 2,0. The present invention relates to a process for manufacturing a novel polyethylene terephthalate tire cord reinforcement which has high tenacity tensile properties. For the production of high tenacity fibers, high purity chips are subjected to a solid phase polymerization to obtain chips which has an intrinsic viscosity (IV) of 0.96 to 1.2. In the next step, these chips reach to extruder having temperature controllable zones which have set values between 230 and 320 °C to enable spinnability with production speed up to 6500 m / min. The next step is melt zone, manifold and spinpack, which kept under constant temperature by secondary heating medium around 260 to 330C. Properly controlled melt polymer is pumped by gear pumps through the spinneret with certain number of holes between 120 to 1100 depending on product type. After generating filaments by using spinneret, the quench zone starts. The starting part of the quench zone is kept heated with electrical heaters between 180 and 400 °C. With the help of this higher temperature quench zone, the spun yarn finds residence area for slow cooling and avoids rapid quenching. After heated- quench zone, the spun yarn enters into a quenching area that cool down the fibers with forced air supply. Spun filament yam delivered is firstly wrapped to feed roll. The drawing of yam occurs in two different sections, and the draw ratio of first and second zones are 1.1 to 3.0, and 1.4 to 5.0 respectively. Each of the roll-sets, except first - feed roll, are heated to specific temperature. As a next step, the drawn filament yarn coming from the last drawing roll is feed to the relaxing section with relax percentage of 0 % to 20% on rolls with temperature control system. Finally, the drawn yarn winded at a speed of 3500 to 7500 m / min.

Claims

CLAIMS1. A novel polyethylene terephthalate tire cord reinforcement which has enhanced tensile properties, comprises cord plies that have drawn polyethylene terephthalate yams comprising at least 90 mol percent polyethylene terephthalate with minimum 7.0g / dtex tenacity has an initial 3% LASE / final 3% LASE ratio which is greater than 1,5.

2. The novel polyethylene terephthalate tire cord reinforcement according to claim 1, characterized in that linear density of the said drawn polyethylene terephthalate yam is minimum 300 dtex and maximum 4600 dtex.

3. The novel polyethylene terephthalate tire cord reinforcement according to claim 1, characterized in that the said drawn polyethylene terephthalate has an initial 3% LASE / final 3% LASE ratio which is greater than 2.

4. The novel polyethylene terephthalate tire cord reinforcement according to claim 1, characterized in that the two or three ply twisted cords made of the said polyethylene terephthalate yams as dipped and heat-set have an initial 3% LASE / final 3%LASE ratio which is greater than 1,5, preferably greater than 2,0.

5. The novel polyethylene terephthalate tire cord reinforcement according to claim 1, characterized in that the said polyethylene terephthalate tire cord reinforcements are used for reinforcement in pneumatic tires as carcass.

6. The novel polyethylene terephthalate tire cord reinforcement according to claim 1, characterized in that the said polyethylene terephthalate tire cord reinforcements are used for reinforcement in pneumatic tires as cap ply.