Wrapped cord for reinforcing rubber products

Abstract

The cord for reinforcing rubber products includes a core (9) and at least one thread (8) wound around the core, the core including at least one strand of filament, and the linear density of the core is greater than the linear density of the thread.

Description

[Technical Field]

[0001] The present invention relates to a reinforcing cord for rubber products, a method for manufacturing the reinforcing cord, and a rubber product including the reinforcing cord, the cord including a central core wound with at least one thread, the core having a linear density greater than the linear density of the thread. [Background technology]

[0002] Typically, reinforcing cords are used to impart linear stiffness, strength, and durability to rubber products such as rubber belts used to drive camshafts in internal combustion engines, to drive auxiliary units such as injection pumps or power transmissions in industrial machinery, or in high-pressure rubber hoses used in airplanes. Rubber belts typically have a rubber portion with one or more reinforcing cords embedded in the rubber portion. The reinforcing cords add strength, stiffness, and longitudinal stability to the rubber belt. Summary of the Invention [Problem to be solved by the invention]

[0003] Good performance in rubber products can be achieved by using rubber-impregnated glass cords. Here, the glass cords contain, for example, E-glass fibers with a density of 2.5 g / ml, a tensile modulus of approximately 70–80 GPa, and an elongation at break of 4%. The rubber reinforcement can be significantly enhanced by using cords containing carbon fibers with a density of 1.8 g / ml, a tensile modulus of approximately 250 GPa, and an elongation at break of approximately 2%. However, while the use of carbon fiber can achieve increased stiffness (as measured by tensile modulus) and reduced weight, these benefits must be balanced against the low elongation at break (2%). In use, a rubber belt passes around pulleys. The pulleys bend the belt and the reinforcing cords within the belt. This applies a tensile bending strain to the outside of the cord and a compressive bending strain to the inside of the cord. This compressive strain can deform some of the cord fibers and potentially displace some of the cord fibers from their positions within the cord. When a fiber bends sharply due to deformation, it is called a crimp. In three-point bending, a carbon cord is observed to bend smoothly until a critical point is reached, at which point the cord crimps, or bends at a sharp angle. This is shown in Figure 1. Once crimped, the fiber undergoes further fatigue and then breaks relatively quickly. A cord made of 12K (12,000 filaments) carbon fiber typically has a diameter of just over 1 mm. When such a cord is bent with a radius of curvature of 50 mm, the bending strain at the outermost portion of the cord is typically 1.0%. Therefore, the outermost portion of the cord is at 50% of its elongation at break, and a bending strain increase to 2% will cause the outermost portion of the cord to break. This is a disadvantage for carbon fiber applications that involve bending, such as rubber belt reinforcement.

[0004] In particular, there is a need to increase the fatigue life of carbon by increasing its resistance to crimping and bending fatigue (induced by repeated bending stresses).

[0005] Furthermore, crimping of carbon fibers within rubber belts under bending stress is also problematic at low temperatures because stiffness increases dramatically as the enclosed rubber approaches its glass transition temperature. This increases localized bending of the cord. There is a need to provide new reinforcing cords suitable for use at low temperatures.

[0006] The size of the reinforcing cords used in a rubber product affects the number of cords that can be used in the rubber product and the size of the rubber product. For example, if smaller cords can provide the required reinforcing stiffness, the reinforced rubber product can be made smaller. Using smaller rubber belts in engine vehicles improves fuel efficiency (narrower rubber belts require narrower pulleys, resulting in lighter vehicle weight). It also has efficiency benefits in the manufacturing cost of the rubber product (less rubber is required). Furthermore, under the same bending stress, smaller diameter cords experience less bending strain than larger diameter cords.

[0007] There is a need to provide new cords for reinforcing rubber articles, such as rubber timing belts. There is a need to provide new cords for reinforcing rubber articles that have good resistance to bending fatigue. There is a need to provide cords for reinforcing rubber articles that have improved bending performance (e.g., compared to known carbon fiber cords) while maintaining the linear stiffness and low density associated with carbon fiber. Improved bending performance can, for example, reduce or eliminate the tendency of the cord to crimp.

[0008] The present invention aims to meet some or all of these needs and to solve some or all of the problems identified above. [Means for solving the problem]

[0009] In a first aspect, the present invention provides a cord for reinforcing rubber products, comprising a core and at least one thread wound around the core, the core including at least one strand of filament, and the core having a linear density greater than the linear density of the thread.

[0010] The cords of the present invention have been found to have improved resistance to crimping. It is believed that the yarn wound around the core holds the filaments in place, limiting their ability to move, deform, and crimp. Particularly when the core comprises carbon filaments, the reinforced cords of the present invention containing carbon filaments have excellent stiffness, are lightweight, and have excellent resistance to crimping under bending stress.

[0011] In another aspect, the present invention provides a method of making a rubber article reinforcing cord, comprising winding a yarn around a core, the core comprising at least one strand of filament, which method can be used to make the reinforcing cord of the first aspect of the present invention.

[0012] In another aspect, the present invention provides a method for increasing the bending elasticity of a core, said core comprising at least one strand of filament, said method comprising winding a yarn around the core, wherein the core and yarn may be as defined for the first aspect of the invention.

[0013] In another aspect, the present invention comprises a rubber composition and at least one reinforcing cord according to the first aspect embedded in the rubber composition. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 shows the typical behavior of a carbon cord in a three-point test: (a) before bending, (b) during smooth bending, and (c) when crimped at an acute angle. [Figure 2] FIG. 2 is a schematic diagram of the machine used to make the cords of the invention in the Examples section, where 1 is the bobbin holder, 2 is the core strand supply, 3 is the yarn to be wound, 4 is the capstan, 5 is the traverse needle, 6 is the take-up tube, and 7 is the take-up drive. [Figure 3]FIG. 3 is a graph showing the increase in cord stiffness with the number of yarn winding turns per meter, i.e., bending of a wrapped carbon fiber cord sample with bending represented by bending stress at a maximum bending strain of 1%. [Figure 4] FIG. 4 is a diagram of a wound cord according to the invention, where 8 is the winding thread and 9 is the large central core. DETAILED DESCRIPTION OF THE INVENTION

[0015] In a first aspect, the present invention provides a cord for reinforcing rubber products, comprising a core and at least one thread wound around the core, the core including at least one strand of filament, and the core having a linear density greater than the linear density of the thread.

[0016] In the cord of the present invention, the core has a greater linear density than the yarn wound therearound. Linear density is the mass per unit length (in units of kg / m or g / m) and can be determined, for example, by measuring the length of the material and weighing it. It has been found that the cord of the present invention has good resistance to crimping due to bending and therefore finds application in extending the flexural fatigue life of rubber products. Advantageously, this can be achieved using relatively lightweight and non-bulky materials due to the cord design. The cord is particularly useful for reinforcing rubber products such as rubber tires, rubber timing belts, and other power transmission belts. The cord of the present invention can function as a relatively small and lightweight reinforcing system for rubber products. This can result in, for example, the production of narrower rubber timing belts with improved manufacturing efficiency. Preferably, the cord is metal-free, i.e., the core is metal-free and the yarn is metal-free.

[0017] Typically, the core has a linear density of at least 200 g / km, preferably from 200 to 8000 g / km, from 400 to 1200 g / km, or from 400 to 800 g / km.

[0018] Typically the yarn has a linear density of 50 g / km or less, preferably 10 g / km or less, or preferably between 3 and 8 g / km.

[0019] The core can have a linear density of at least 200 g / km, preferably 200 to 8000 g / km, 400 to 1200 g / km, or 400 to 800 g / km, and the yarn can have a linear density of 50 g / km or less. The core can have a linear density of at least 200 g / km, preferably 200 to 8000 g / km, 400 to 1200 g / km, or 400 to 800 g / km, and the yarn can have a linear density of 20 g / km or less. The core can have a linear density of at least 200 g / km, and the yarn can have a linear density of 10 g / km or less or a linear density of 3 to 8 g / km. The core can have a linear density of 200 g / km to 8000 g / km, and the yarn can have a linear density of 10 g / km or less or a linear density of 3 to 8 g / km. The core can have a linear density of 400 g / km to 1200 g / km, and the yarn can have a linear density of 10 g / km or less or a linear density of 3 to 8 g / km.The core can have a linear density of 400 g / km to 800 g / km, and the yarn can have a linear density of 10 g / km or less or a linear density of 3 to 8 g / km.

[0020] The core can have a twist of 0 (zero) or greater than 0. For example, the core can have a twist greater than 0 tpm up to 240 tpm. This is the twist of the core, which is also referred to herein as the core twist. The core includes at least one strand of filament, which is also referred to herein as the strand. The core can include one strand, or it can include two or more strands, for example, two, three, or four strands. A strand can be twisted with itself, and the resulting twist is referred to herein as the primary twist. When two or more strands are twisted together, the resulting twist is referred to herein as the secondary twist. The primary twist and primary twist can be in the same twist direction or in opposite twist directions. When the core includes one strand with a primary twist greater than 0, the primary twist is referred to herein as the core twist. When the core comprises two or more strands twisted together to impart a ply twist greater than zero, the ply twist is referred to herein as the twist of the core.

[0021] Typically, the cord of the present invention includes a core having a twist greater than 0, and the yarn is wound around the core at a number of turns per meter that is at least 50% greater than the twist (number of turns per meter) of the core. In this embodiment, the yarn can be wound around the core at a number of turns per meter that is 1.5 to 150 times the twist of the core. The core can have a twist of greater than 0 tpm and less than or equal to 240 tpm, greater than 0 tpm and less than or equal to 200 tpm, or greater than or equal to 40 tpm and less than or equal to 120 tpm, and the yarn can be wound around the core at a number of turns per meter that is 1.5 to 150 times the twist of the core. The core can have a twist of greater than 0 tpm and less than or equal to 240 tpm, greater than 0 tpm and less than or equal to 200 tpm, or greater than or equal to 40 tpm and less than or equal to 120 tpm, and the yarn can be wound around the core at a number of turns per meter that is 500 to 8000. The core can have a twist of greater than 0 tpm and less than or equal to 240 tpm, greater than 0 tpm and less than or equal to 200 tpm, or greater than or equal to 40 tpm and less than or equal to 120 tpm, and the yarn can be wound around the core at a number of turns per meter of 1,000 to 5,000. The wound yarn may or may not be twisted itself.

[0022] The cord of the present invention includes a core, which includes at least one strand of filaments. A strand is effectively a bundle of filaments. Thus, a strand includes multiple filaments. As used herein, the term "filament" is interchangeable with the term "fiber." The filament can be any suitable material, such as carbon, glass, basalt, or aramid, and / or a mixture thereof. The filament can be a single material, for example, a carbon, glass, basalt, or aramid filament. Alternatively, the filament can be a composite of two or more materials, such as two or more of carbon, glass, basalt, and aramid. In one embodiment, the filament is not an aramid filament; for example, the filament can be carbon, glass, or basalt, and / or a mixture thereof. Also, for example, the filament can be such that it does not include aramid, i.e., the filament can be a composite of two or more materials without including aramid. The filament can be a composite of two or more materials, such as a carbon, glass, and basalt filament. The filaments may have a diameter of 5 to 20 μm. The filaments may be, for example, carbon filaments, each having a diameter of 5 to 20 μm, 4 to 12 μm, 5 to 8 μm, or 5 to 7 μm. The filament bundle may contain 1,000 to 24,000 or 6,000 to 12,000 filaments. For example, the filament bundle may be a carbon filament bundle having a diameter of 5 to 20 microns and containing 1,000 to 24,000 or 6,000 to 12,000 filaments.

[0023] The filament strands can be embedded in a polymer, such as rubber latex. This can be achieved by impregnating the filament strands with an impregnation liquid. The impregnation liquid is typically a polymer dispersed in water, such as a rubber latex or a mixture of rubber latexes dispersed in water. Suitable aqueous rubber dispersions (latexes) include, among others, polybutadiene (BR), styrene butadiene (SBR), acrylonitrile butadiene (NBR), hydrogenated acrylonitrile butadiene (HNBR), chloroprene (CR), chlorosulfonated polyethylene (CSM), acrylic (ACM), and vinylpyridine / SBR / BR (VP). Thermoplastic polymers dispersed in water can also be used. The impregnation liquid can also be applied so that each filament is coated with the impregnation liquid. The impregnation liquid can also contain a crosslinking agent that acts to crosslink the polymer. These crosslinking agents can react immediately or, for example, can react in a delayed manner so that crosslinking within the core occurs during vulcanization of the rubber belt. Thus, the strands can comprise bundles of filaments impregnated with a polymer. In one embodiment, the core comprises at least one strand impregnated with a polymer / aqueous rubber dispersion. The core can comprise one strand impregnated with a polymer / aqueous rubber dispersion. The core can comprise two or more strands impregnated with a polymer. Preferably, each strand of the core is impregnated with the polymer / aqueous rubber dispersion. These are also referred to herein as impregnated cores. The process of impregnation is well known in the industry and is described, for example, in "Reinforcement of Rubber by Reactive Impregnation Glass Cords," CA Stevens, PJ Martin, and M Akiyama, Paper No. 85, presented at the 170th Fall Technical Meeting of the American Chemical Society, Rubber Division, Cincinnati, Ohio, October 10-12, 2006, ISSN: 1547-1977. Another example of impregnating strands with a rubber composition is described in US Pat. No. 5,368,928A (Okamura et al.).

[0024] The strands can have a twist of 0 or can themselves have a twist greater than 0 tpm, for example, up to 240 tpm. To obtain impregnated strands with a (primary) twist greater than 0, the strands of filaments are preferably impregnated with the impregnating liquid and then twisted, i.e., after the strands are impregnated with the impregnating liquid, the strands are twisted.

[0025] When the core includes two or more strands, the strands can be twisted together (ply twist). In this embodiment, preferably, each strand is impregnated with an impregnation liquid, twisted as needed (ply twist), and then twisted together (ply twist). The ply twist and ply twist can be in the same twist direction or in opposite twist directions.

[0026] Typically, when the core includes two or more strands, all of the strands are twisted together simultaneously (ply twisted) to form the core, with each strand having the same ply twist.

[0027] The cord comprises at least one thread wound around a core. The thread can be of any suitable material, such as nylon, polyester, acrylic, elastic polyurethane (Lycra, Elastane, Spandex, etc.), polyphenylene sulfide (PPS), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), or aramid. The thread can have a diameter of 0.005 to 0.50 mm, preferably 0.02 to 0.20 mm. The thread has a linear density of 50 g / km or less, preferably 10 g / km or less, preferably 3 to 8 g / km. The thread can have a linear density of 30 g / km or less.

[0028] A cord can include one thread wound around a core. Figure 4 shows a diagram of such a cord. Alternatively, a cord can include two or more threads wound around a core. A cord can include two, three, or four threads wound around a core.

[0029] The yarn is wound onto the core at 500 to 8000 tpm, preferably 1000 to 5000 tpm. The yarn can be wound onto the core at a number of turns per meter that is at least 50% of the twist rate of the core, or at a number of turns per meter that is 1.5 to 150 times the twist rate of the core.

[0030] The thread can be wound around the core so that the thread forms one or less layers on the core. The thread can also be wound around the core so that the thread forms more than one layer on the core, for example, two or more layers. Also, for example, the thread can form a partial second layer or can be double wrapped to form two layers. Preferably, the thread is wrapped around the cord so that the thread does not form more than a single layer. One thread can be wrapped around the core. Multiple threads can be wrapped around the core. When multiple threads are present, the threads can be twisted around the core in the same or opposite directions. For example, two threads can be wound in opposite directions, forming a cross pattern around the core. When three or more threads are used, a combination of twist directions can be used.

[0031] The threads wound around the core are relatively lightweight and much less bulky than the core. Typically, each core and each thread has a substantially circular cross section. Typically, the core diameter is 0.5 to 2.5 mm, and the thread diameter is 0.005 to 0.50 mm, preferably 0.02 to 0.20 mm. In one embodiment, the diameter of the core plus the diameter of the two threads is 3.0 mm or less. For example, if a core with a diameter of 2.0 mm has one layer of thread winding, the maximum cord diameter is 3.0 mm.

[0032] The yarn can have twist or zero twist. The yarn can be a monofilament. The yarn can be a bundle of filaments.

[0033] Typically, the cross-sectional area of ​​the core is at least 40% of the cross-sectional area of ​​the cord, and preferably greater than 80%. Typically, the cross-sectional area of ​​the yarn is 0.04 to 25% of the cross-sectional area of ​​the core. Preferably, the cross-sectional area of ​​the yarn is 0.1 to 20% of the cross-sectional area of ​​the core.

[0034] Typically, the modulus of the core is greater than the modulus of the yarn. For example, the modulus of the core can be two or five times greater than the modulus of the yarn. When a cord includes one or two yarns wound around it, the core typically has a greater modulus than each of the yarns. Thus, a cord can include one or more relatively flexible yarns wound around a stiffer core. Modulus of elasticity is also referred to herein as tensile modulus. Tensile modulus is a property of the material being tested that is independent of the sample's geometry. Tensile modulus is defined as the slope of the stress-strain relationship. Tensile modulus can be measured using known methods. For example, ISO-527-1 and 527-2 can be used to measure the modulus of plastics, and ISO 1156 CF test can be used to measure the modulus of higher modulus materials such as carbon, glass, and aramid. Alternatively, the modulus can be measured using a force-displacement tensile tester using the following procedure. To test bundles of filaments, yarn cord-specific grips or bollard grips are required. These grips feature reduced tension at the gripping point, making breakage within the grip unlikely. A 750 mm gauge length (free length under tension) is used. The grips are separated at a constant rate of 10 mm / min (slightly more than 1% strain per minute). Strain is calculated as the change in displacement divided by the gauge length. The testing machine measures the force as the displacement increases. Stress is the measured force divided by the area of ​​the sample. For bundles of concentrated filaments, the area in the measurement is the linear density (mass per length) divided by the density (mass per volume). The relationship between stress and strain is not necessarily linear. Therefore, the cord modulus is used to obtain the slope of the change in stress divided by the change in strain between strain levels of 0.1% and 0.6%. Using this test, example values ​​of the tensile modulus of a fiber bundle were obtained. High strength U(S2) glass: 103 GPa, Technora copolymer aramid: 85 GPa, and Toray T700S carbon fiber: 228 GPa.

[0035] Typical values ​​for the modulus of elasticity of materials suitable for use in the cords of the present invention are shown in the table below (obtained from https: / / omnexus.specialchem.com).

[0036] [Table 1]

[0037] The core and the yarn wrapped around it can have an adhesive coating. The wrapped core can have an overcoat of adhesive, if necessary, to penetrate the yarn and form a good bond between the core and the yarn (and the rubber in the rubber product in which the cord is later placed). Suitable overcoat adhesives include those suitable for adhesion to rubber compositions primarily used in rubber belts, but are not limited to HNBR, EP type (EPM, EPDM), or CR rubber. EP = ethylene propylene-based rubber, EPM = ethylene propylene monomer-based rubber, EPDM = ethylene propylene monomer-based rubber with diene monomer.

[0038] The adhesive can be solvent-based or water-based. Adhesive overcoat processes are well understood in the industry. An example is provided on the website www.ngfglasscord.com. An example of impregnating strands with a rubber composition is described in U.S. Pat. No. 5,368,928 A (Okamura et al.).

[0039] An embodiment of the code of the present invention includes the following:

[0040] The code described above, the core comprises a single strand of carbon filament impregnated in a polymer; The linear density of the core is 300 to 1000 g / km, The linear density of the yarn is 2 to 8 g / km, The yarn is wound around the core with a twist of 1000 to 5000 tpm. code.

[0041] The code described above, The core contains one strand of 6,000 carbon filaments, The linear density of the core is 400 g / km; The core is wound with polyester or nylon thread having a linear density of 4 to 6 g / km. code.

[0042] The code described above, The core comprises one strand containing 6000 carbon filaments, pre-twisted at 80 tpm; The linear density of the core is 400 g / km; The core is wound at 1000 tpm with polyester or nylon yarn having a linear density of 4-6 g / km. code.

[0043] The code described above, The core is impregnated with a polymer and comprises one strand of filaments that has been impregnated and then twisted (primary twisted), or the core comprises two or more strands of filaments that have been impregnated and twisted (primary twisted) and then twisted together (primary twisted), Optionally, the wound core has an overcoat that penetrates the yarn and forms a good bond between the wound core and the yarn (and the rubber of the rubber product into which the cord is later placed). code.

[0044] The code described above, The core includes one strand of 6,000 carbon filaments, and the core is impregnated with HNBR latex rubber and a crosslinking agent that reacts during vulcanization of the rubber belt; The core is wound with polyester or nylon thread having a linear density of 4 to 6 g / km; The optionally wound core has an adhesive overcoat, which is suitable for adhesion to rubber compositions of HNBR or EP type (EPM, EPDM) used in rubber belts. code.

[0045] The code described above, The core contains one strand containing a bundle of 12,000 carbon filaments pre-twisted at 40 tpm. The linear density of the core is 800g / km, The core is wound with nylon thread having a linear density of 4-6g / km at 1000-5000tpm. code.

[0046] In another aspect, the present invention provides a method for making the cord of the present invention. The method comprises obtaining a core comprising at least one strand of filament and winding at least one thread around the core. That is, the present invention provides a cord for reinforcing rubber articles, comprising winding a thread around a core, the core comprising at least one strand of filament. The cord, i.e., the core and the thread, are as described above. This method can therefore be used to make the reinforcing cord of the first aspect of the present invention. By winding, it is meant that the thread is outside the core, e.g., the thread and core are not entangled or twisted together.

[0047] The core can be obtained by means known in the art. First, a plurality of filaments are bundled together to form a bundle of filaments. This bundle of filaments forms a strand. The strand of filaments is optionally impregnated with the impregnation liquid defined above. The strand (impregnated or not) can be twisted in one direction to form a pre-twist. The core can be formed from one such strand. Alternatively, two or more strands (impregnated or not), typically twisted in the same direction, form the core. Once the core is formed, at least one thread is wound around the core at a desired number of turns per meter. Optionally, an adhesive coating can be applied to the wound core.

[0048] In another aspect, the present invention provides a method for increasing the bending elasticity of a core, wherein the core comprises at least one strand of filament, the method comprising winding at least one thread around the core, the core being as described herein for other aspects of the invention.

[0049] In another aspect, the present invention provides a rubber product comprising a rubber composition and at least one reinforcing cord according to the first aspect of the present invention embedded in the rubber composition. The rubber product is reinforced with the reinforcing cord of the present invention. The rubber product is not particularly limited. Examples of the rubber product of the present invention include automobile and bicycle tires and transmission belts. Examples of transmission belts include synchronous transmission belts and friction transmission belts. Examples of synchronous transmission belts include toothed belts, such as automotive timing belts. Examples of friction transmission belts include flat belts, round belts, V-belts, and V-ribbed belts. That is, the rubber product of the present invention can be a toothed belt, flat belt, round belt, V-belt, or V-ribbed belt.

[0050] The rubber product of the present invention is formed by embedding the reinforcing cord of the present invention in a rubber composition (matrix rubber). The method for embedding the reinforcing cord in the matrix rubber is not particularly limited, and any known method can be used. The reinforcing cord of the present invention is embedded in the rubber product of the present invention (e.g., a rubber belt). Therefore, the rubber product of the present invention has high flexural fatigue resistance. Therefore, the rubber product of the present invention is particularly suitable for use as a timing belt for a vehicle engine. Such a belt may include one or more other components, such as a fabric layer, a low-friction coating, an adhesive treatment, or an internal filler for the rubber compound.

[0051] The rubber of the rubber composition in which the reinforcing cord of the present invention is embedded is not particularly limited. The rubber may be chloroprene rubber, chlorosulfonated polyethylene rubber, ethylene propylene rubber, hydrogenated nitrile rubber, etc. The hydrogenated nitrile rubber may be hydrogenated nitrile rubber containing a zinc acrylate derivative (e.g., zinc methacrylate) dispersed therein. From the viewpoint of water resistance and oil resistance, at least one rubber selected from hydrogenated nitrile rubber and hydrogenated nitrile rubber containing a zinc acrylate derivative dispersed therein is preferred. The matrix rubber may further contain carboxyl-modified hydrogenated nitrile rubber. From the viewpoint of adhesion, it is preferable that the adhesive coating layer on the reinforcing cord and the rubber composition of the rubber product are compatible for good adhesion, and they may contain or consist of the same type of rubber.

[0052] As used herein, the term "comprising," which is inclusive or open-ended and does not exclude additional, unrecited elements or method steps, is intended to encompass, as alternative embodiments, the phrases "consisting essentially of" and "consisting of." "Consisting of" excludes unspecified elements or steps, while "consisting essentially" permits the inclusion of additional, unrecited elements or steps that do not materially affect the essential or basic and novel characteristics of the composition or method under consideration.

[0053] Embodiments of the present invention are described in the following numbered clauses:

[0054] 1. A fiber optic cable comprising a core and at least one yarn wound around the core, the core comprising at least one strand of filament, the core having a linear density greater than the linear density of the yarn; Cord for reinforcing rubber products.

[0055] 2. The core has a linear density of at least 200 g / km and the yarn has a linear density of 50 g / km or less. Code as described in clause 1.

[0056] 3. The core has a linear density of 200 to 8000 g / km, and the yarn has a linear density of 10 g / km or less. Code as set out in clause 2.

[0057] 4. The core has a twist greater than 0, and the yarn is wound around the core at a number of turns per meter that is 1.5 to 150 times the twist of the core, wherein: (i) the core comprises one strand having a ply twist greater than zero, and the ply twist is the twist of the core; or (ii) the core comprises two or more strands twisted together to impart a final twist greater than zero, and the final twist is the twist of the core; The code described in any one of clauses 1 to 3.

[0058] 5. The twist of the core is greater than 0 tpm and less than or equal to 240 tpm, and the yarn is wound around the core at 500 to 8000 tpm; Code as set out in clause 4.

[0059] 6. The or each strand of filaments is impregnated with a polymer (or an aqueous polymer dispersion); The code described in any one of clauses 1 to 5.

[0060] 7. The core comprises one strand; A code as set forth in any one of clauses 1 to 6.

[0061] 8. The core comprises two or more strands; A code as set forth in any one of clauses 1 to 7.

[0062] 9. The core and the thread wound around the core are covered with an adhesive layer. A code as set forth in any one of clauses 1 to 8.

[0063] 10. The core is wound with a single thread; A code as set forth in any one of clauses 1 to 9.

[0064] 11. The core is wound with two or more threads; A code as set forth in any one of clauses 1 to 10.

[0065] 12. The cross-sectional area of ​​the core is at least 40% of the cross-sectional area of ​​the cord. A code as set forth in any one of clauses 1 to 11.

[0066] 13. The cross-sectional area of ​​the core is at least 80% of the cross-sectional area of ​​the cord. Code as set out in clause 12.

[0067] 14. The core has a diameter in the range of 0.5 to 2.5 mm, preferably in the range of 0.5 to 1.2 mm; A code as set forth in any one of clauses 1 to 13.

[0068] 15. The diameter of the core is 0.5 to 2.5 mm or 0.5 to 1.2 mm, and the diameter of the thread is 0.005 to 0.5 mm. A code as set forth in any one of clauses 1 to 14.

[0069] 16. The diameter of the core plus the diameter of the thread (or the diameters of two threads) is 3.0 mm or less; A code as set forth in any one of clauses 1 to 15.

[0070] 17. The filaments are carbon, glass, basalt, and / or aramid filaments, or a combination of materials; A code as set forth in any one of clauses 1 to 16.

[0071] 18. The yarn is any of nylon, polyester, acrylic, elastomeric polyurethane, PPS, PEEK, PEKK, or aramid; A code as set forth in any one of clauses 1 to 17.

[0072] 19. A method for producing a cord according to any one of clauses 1 to 18, comprising: obtaining a core comprising at least one strand of filament; and winding at least one thread around the core; method.

[0073] 20. A method for increasing the bending elasticity of a core, said core comprising at least one strand of filament, said method comprising winding at least one thread around said core. method.

[0074] 21. A tire comprising a rubber composition and at least one cord according to any one of clauses 1 to 18 embedded in the rubber composition. Rubber products.

[0075] 22. The rubber product is a tire, a timing belt, or another power transmission belt. 2. Rubber products as defined in clause 21.

[0076] The invention is illustrated by the following non-limiting examples. [Example]

[0077] The cords shown in the table below were made. The cord of Comparative Example 1 was used as the central core of the wound samples. The cord of Comparative Example 1 included one strand, which was a bundle of 12,000 carbon fibers impregnated with polyurethane latex. The strand had a linear density of 800 g / km, and the carbon fiber bundle had a twist of 40 turns per meter (tpm).

[0078] [Table 2]

[0079] The wrapped cords in Examples 1 to 3 were produced using a covering machine similar to the OMM SP-R (http: / / www.rattiluino.com / en / prodotto / sp-r / ) manufactured by Ratti Luino. The layout of this covering machine is shown schematically in Figure 2. The core was pulled through the covering machine at speeds varying between 1 and 10 m / min. A single covering yarn was used, rotating around the core at speeds between 3,000 and 15,000 rpm. The covering yarn itself was not pre-twisted; that is, the covering yarn itself was not ply-twisted. The throughput and rotation speed were varied to change the number of rotations per meter of the covering yarn wound around the core (revolutions per meter = rotation speed divided by the core throughput speed). The equipment used was designed to cover low-tex yarns consisting of one or two low-tex yarns (Tex = grams per 1,000 m of yarn length). The equipment was not designed with the heavier materials of the present invention in mind, and parts had to be rotated by hand or kept under tension by hand to avoid slippage during sample preparation.

[0080] Samples of the wrapped cord were tested in a tensile tester using three-point bending in compression. The layout is shown in Figure 1 and is described in ISO 178 (Plastics - Determination of flexural properties). The contact point was a 10 mm diameter rod. The distance between the two support rods was 30 mm. A speed of 5 mm / min was used for the bending test. The test output was the bending stress at the maximum bending strain due to displacement. The flexural modulus (ratio of stress to strain) was taken as the stress measured when the maximum bending strain reached 1%. The flexural modulus indicates the tendency of a material to resist bending. The higher the flexural modulus, the more resistant it is to bending under bending stress.

[0081] Each cord sample was tested five times and the average results of the five tests for each cord sample are shown in the table below.

[0082] [Table 3]

[0083] The results show that the example cords with yarn wraps greater than 1000 tpm exhibited significantly higher stress at 1% strain, i.e., significantly higher flexural modulus, than the current cords without yarn wraps. Thus, the wrapped cords of the present invention have higher stiffness than the unwrapped cords of the comparative examples. This increased stiffness reduces the cord's tendency to crimp at high twists. A logarithmic dependence of stiffness (expressed as bending stress at a maximum bending strain of 1%) was observed versus the number of wraps per meter, as shown in Figure 3. The results indicate that the presence of the wrapped yarn strengthens the carbon central core and can prevent crimping.

Claims

1. The core and at least one thread wound around the core; Including, the core comprises at least one strand of filament; the core has a linear density of at least 200 g / km and the yarn has a linear density of less than 30 g / km; the core has a twist greater than zero; the yarn is wound around the core at a number of turns per meter that is 1.5 to 150 times the number of twists of the core; (i) the core comprises one strand having a ply twist greater than zero, and the ply twist is the twist of the core; or (ii) the core comprises two or more strands twisted together to impart a ply twist greater than zero, and the ply twist is the twist of the core; The twist of the core is greater than 0 tpm and less than or equal to 240 tpm; The yarn is wound around the core at more than 1000 tpm and less than or equal to 8000 tpm. Cord for reinforcing rubber products.

2. The core has a linear density of 200 to 8000 g / km, and the yarn has a linear density of 20 g / km or less. The code of claim 1.

3. the or each strand of filaments is impregnated with a polymer (or an aqueous polymer dispersion), 3. The cord according to claim 1 or 2.

4. The core comprises one strand. The cord according to any one of claims 1 to 3.

5. The core comprises two or more strands. The cord according to any one of claims 1 to 4.

6. The core and the thread wound around the core are covered with an adhesive layer. The cord according to any one of claims 1 to 5.

7. The yarn is a bundle of filaments. The cord according to any one of claims 1 to 6.

8. The core is wound with a single thread. The cord according to any one of claims 1 to 7.

9. The core is wound with two or more threads. The cord according to any one of claims 1 to 8.

10. The cross-sectional area of ​​the core is at least 40% of the cross-sectional area of ​​the cord. The cord according to any one of claims 1 to 9.

11. The cross-sectional area of ​​the core is at least 80% of the cross-sectional area of ​​the cord. The code according to claim 10.

12. The core has a diameter in the range of 0.5 to 2.5 mm. The cord according to any one of claims 1 to 11.

13. The diameter of the core is 0.5 to 2.5 mm, and the diameter of the thread is 0.005 to 0.5 mm. The cord according to any one of claims 1 to 12.

14. The diameter of the core plus the diameter of the thread (or the diameters of two threads) is 3.0 mm or less; 14. The cord according to claim 12 or 13.

15. the filaments of the core are carbon, glass, basalt, and / or aramid filaments, or a combination of materials; or the filaments of the core are carbon, glass, and / or basalt filaments, or a combination of materials; The cord according to any one of claims 1 to 14.

16. The yarn is any of nylon, polyester, acrylic, elastomeric polyurethane, PPS, PEEK, PEKK, or aramid. The cord according to any one of claims 1 to 15.

17. The elastic modulus of the core is greater than the elastic modulus of the yarn. The cord according to any one of claims 1 to 16.

18. the modulus of elasticity of the core is at least twice as great as the modulus of elasticity of the yarn; 18. The cord of claim 17.

19. the modulus of elasticity of the core is at least 5 times greater than the modulus of elasticity of the yarn; 18. The cord of claim 17.

20. The cord is metal-free. A cord according to any one of claims 1 to 19.

21. The yarn is wound around the core at 1670 tpm or more. The cord according to any one of claims 1 to 20.

22. A method for producing a cord according to any one of claims 1 to 21, comprising the steps of: obtaining a core comprising at least one strand of filament; winding at least one thread around the core; A method comprising:

23. A tire comprising a rubber composition and at least one cord according to any one of claims 1 to 21 embedded in the rubber composition. Rubber products.

24. The rubber product is a tire, a timing belt, or another power transmission belt. The rubber product of claim 23.

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