Reinforcing structure

Abstract

The application pertains to a reinforcing structure comprising a monofilament of thermoplastic material as a core component, at least one linear element wrapped around the core component as a single layer, wherein the single layer of the at least one linear element covers at least 90% of the surface area of the thermoplastic monofilament and wherein the reinforcing structure has a residual torsion of at most ±0.6 torsions per meter, measured according to ASTM D2969- 02.

Description

[0001] Reinforcing structure

[0002] Description:

[0003] The present application pertains to a reinforcing structure which may be used for embedding in polymeric and especially elastomeric items.

[0004] Reinforced polymeric materials have developed to industrial standard during the 20th century for a lot of applications. In such materials, the merits of different kinds of materials can be combined with polymeric materials providing e.g. elasticity, a homogenic surface and stiffness while reinforcing materials such as fibers, wires, rods, grids, nets or fabrics to provide strength against e.g. pulling and / or pushing forces. In order to achieve combined properties, it is essential that there is good adhesion between the polymeric material and the reinforcing material.

[0005] An important product of reinforced polymeric materials are tires which are an essential component of nearly all road vehicles and airplanes. For more than half a century such tires are much more than inflatable balloons of rubber. Tires are complex structures including sophisticated rubber blends and several entities of fiber reinforcements of different materials.

[0006] A typical tire comprises at least five different kinds of reinforcements. The bead area is reinforced by a bead reinforcement usually made of steel wire or steel cord. Directly underneath the tread there is located the so-called cap-ply. The tire belt is located underneath the cap-ply. Typically, the belt is a structure of steel cords and the backbone structure of the tire is formed by the so-called carcass which is usually a woven structure of textile cords. The fifth component is the reinforcing fabric that embeds the bead and the bead filler, known to the skilled person as flipper (in case it is made of textile) or chafer (in case it is made of steel cord).

[0007] Thus, apart from rubber, a traditional tire comprises a large amount of steel and a large amount of fibers.

[0008] Although it is a very economical material with high tenacity, there is a tendency to reduce the use of steel in tires due to the high weight gain that steel provides to vehicles which results in a high fuel consumption and thus high CO2 emissions. Up to now, the development has reached a point where the amount of steel still used in tires can no longer be reduced significantly, however it is still desirable to reduce the weight of tires due to the dramatic increase of fuel prices which put a pressure on manufacturers to provide fuel-saving vehicles with lower CO2 emissions.

[0009] It is thus the object of the present invention to provide a reinforcing structure for tires and other polymeric items that has the same mechanical properties, i.e. the same flexural stiffness and the same tenacity, as the materials of the prior art but at a lower weight.

[0010] In order to keep the mechanical properties not only of the reinforcing structure but also of the reinforced product it is furthermore necessary that the reinforcing structure shows an adhesion to rubber which is at least the same as the one of reinforcing structures of the prior art.

[0011] The objects of the present application are solved by a reinforcing structure comprising a monofilament of thermoplastic material as a core component, at least one linear element wrapped around the core component as a single layer, wherein the single layer of the at least one linear element covers at least 90% of the surface area of the thermoplastic monofilament and wherein the reinforcing structure has a residual torsion of at most ±0.6 torsions per meter, measured according to ASTM D2969-02.

[0012] A reinforcing structure according to the present application is a member which is able to absorb pulling, pushing or rotational forces. As such, a reinforcing structure according to the present application may be a linear element that is either rigid such as a rod or flexible such as a rope, a yarn, a cord or a fiber. Linear elements according to the present application are all elements which have a first dimension which is at least 100 times larger than both dimensions which are perpendicular to the first dimension.

[0013] A reinforcing structure according to the present application may also be a two- or three-dimensional element such as a grid, a net, a web, a fabric, a knitted fabric, a scrim, a rack, a carcass or a structure produced from webs, fabrics or scrims by techniques like sewing. Two- or three-dimensional reinforcing structures are typically open structures with a large amount of open space between the linear and / or two-dimensional elements forming them in order to allow the polymeric material or a precursor for the polymeric material to flow into the open space of the reinforcing structure in order to embed it into the polymeric material.

[0014] A filament according to the present invention is a monolithic linear structure which has a length that is essentially infinite compared to its thickness. Following this definition, a filament may be several hundred meters or even several kilometers long. It is e.g. possible that the whole content of a yarn bobbin is one filament.

[0015] A monofilament according to the present application is a filament that is handled, transported and processed on its own in such a way that there are no other filaments which are running in parallel to it. Typical monofilaments have a thickness of at least 0.1 millimeters, 0.2 millimeters, 0.5 millimeters, 0.8 millimeters, 1 millimeter, 2 millimeters, 3 millimeters or 5 millimeters.

[0016] Typical monofilaments have a thickness of at most 0.2 millimeters, 0.5 millimeters, 0.8 millimeters, 1 millimeter, 2 millimeters, 3 millimeters, 5 millimeters ot 7 millimeters. The skilled person knows that any lower boundary and every upper boundary can be combined.

[0017] As opposite to a monofilament, a multifilament is a bundle of filaments that are essentially parallel and which are produced, transported and / or handled as a bundle. Multifilaments may be connected by adhesive agents, punctual tangling or by twisting. In general, multifilaments which are connected in any manner are also called “multifilament yarns”. In the present application, the expressions “multifilament” and “multifilament yarn” are used as synonyms if not otherwise stated.

[0018] The term “monolithic” according to the present application is to be understood in such a way that it describes the outer shape of a structure. A monolithic structure according to the present application appears to a user to be one single structure such as e.g. one rod, one fiber or one filament which is not composed of several subunits or which at least cannot be separated into several subunits without being irreversibly destroyed. As the term “monolithic” only refers to the outer shape, a monolithic structure according to the present application may well comprise several components, however, these components must be covered or concealed in such a way that they cannot be recognized from the outside or they must be connected to each other in such a manner that they are not separable e.g. by glueing or embedding into a polymeric material. If the monolithic structure is e.g. a monofilament with fibers embedded therein, then the fibers are embedded in such a manner that they cannot be noticed from the outer shape of the monolithic monofilament or they at least cannot be separated from each other without destroying the monolithic monofilament.

[0019] A thermoplastic material according to the present application is any polymeric material that melts and / or softens at elevated temperature. High-melting inorganic materials such as metals, glass or basalt are not considered to be thermoplastic according to the present application.

[0020] Typical thermoplastic polymers are e.g. polyolefins such as polyethylene, polypropylene, any blends thereof and any copolymers based on ethylene and propylene as monomers. Thermoplastic polymers can also be polyamides such as polyamide-6, polyam ide-6,6, polyam ide-4, 10, polyamide-10 or polyamide-11. Thermoplastic polymers can also be polyesters such as polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polylactide or polycaprolactone. Furthermore, the thermoplastic polymer can be acryl nitrile-styrene-butadiene copolymer (ABS), polyurethanes, polyether ether ketones, polyphenylene sulfide, polyvinyl alcohol, polyvinyl acetate or polyvinyl chloride. The thermoplastic polymer may in part or in total be of recycled and / or biological origin.

[0021] The monofilament may be treated with an adhesion promoting agent known to the person skilled in the art such as the well-known RFL dip or any other adhesion promoting agent which may e.g. be acrylic polymers, isocyanates, epoxides, polyols or other agents known to the person skilled in the art.

[0022] The linear element according to the application can be any linear element that is flexible enough to be wrapped around the thermoplastic monofilament in such a manner that an essentially closed layer may be obtained. Typically, the linear element can be a thread, a yarn, a filament, a monofilament, a multifilament yam or a fiber. In a multifilament yam, the filaments may be essentially parallel and not or only negligibly twisted. Furthermore, the linear element may be a twisted yam or a cord. The linear element may comprise glass, carbon fibers, steel wire, aluminum wire or basalt.

[0023] Possible organic polymers that may be comprised in the linear element are thermoplastic and / or thermosetting polymers such as polyesters (polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polyethylene furanoate (PEF), and the like), aromatic polyesters, aliphatic polyamides (such as polyamide-5, polyamide-6, polyamide-6,6, polyamide-5,6, polyamide-4,10, polyam ide-6, 10, polyamide-6, 8, polyamide-10 or polyamide-11), aromatic polyamides such as aramids (para-polyphenylene terephthalamide, metapolyphenylene isophthalamide), polyvinyl alcohol, polyvinyl acetate, polyphenylene benzobisoxazole (PBO), polybenzimidazole (PBI), polyetheretherketone (PEEK), ultra-high molecular weight polyethylene (UHMWPE), polyurethane (PUR) or copolymers comprising monomers of said materials or mixtures or blends of said materials but is not limited to this selection.

[0024] The material of the linear element may have elastomeric properties, namely thermoplastic elastomeric properties which means that it is formed from molecular chains which are interconnected by non-bonding interactions at room temperature, providing them with elastomeric properties. Typical thermoplastic elastomers are polyurethanes with long polyol chain contributions or thermoplastic elastomers of the polyester-ester or the polyether-ether type. Typical product names are Elasthan, Spandex and Lycra®.

[0025] The material of the linear element may in part or completely be of biological origin. The material of the linear element may thus also be cellulosic or proteinic fibers such as cotton fibers, viscose fibers, lyocell fibers, linen fibers, hemp fibers, abace fibers, sisal fibers, wool fibers of sheep, goats or any other mammals or silk fibers from the cocoons of the species Bombyx mori or from any other insects that produces suitable fibers. The material of the linear element may in part or completely be made from recycled plastics. Materials of biological and recycling sources may be combined.

[0026] In an embodiment, the linear element may comprise a nucleating agent. Said nucleating agent may be talc or a similar inorganic filler, sodium benzoate, sodium stearate, sodium-ion ionomers, a sulfonamide compound metal salt or a sulfonimide compound metal salt, mono sodium salt of dicarboxylic acid, and mixtures thereof, as known in the art.

[0027] The linear element may furthermore comprise an adhesion promotion agent. The skilled person knows this also under the term “dip” or “dipping”. Said adhesion promotion agent may e.g. be the so-called RFL-dip comprising resorcinol, formaldehyde and latex or any other adhesion promoting agent which may e.g. be acrylic polymers, isocyanates, epoxides, polyols or other agents known to the person skilled in the art.

[0028] It is understood that concerning the linear element the features of all embodiments named may be combined with each other. In an embodiment, a monofilament of polyethylene terephthalate comprising embedded filaments of polyamide-66 and a wrapping with a linear element of polyamide-66 is useful for cap-ply applications in a tire.

[0029] In an embodiment, a monofilament of co-polyester with embedded filaments of polyphenylene terephthalamide and a wrapping with a linear element of polyamide-66 is useful for cap-ply applications in a tire. In an embodiment, a monofilament of co-polyester comprising embedded filaments of rayon and provided with a wrapping with a linear element of polyethylene terephthalate is useful for carcass applications in a tire.

[0030] In an embodiment, a monofilament of co-polyamide with embedded filaments of polyethylene terephthalate and provided with a wrapping with a linear element of polyethylene terephthalate is useful for carcass applications in a tire.

[0031] Wrapping around the monofilament means that the at least one linear element is arranged around the monofilament in such a manner that the linear element or each linear element forms a helix which is wound around the monofilament.

[0032] According to the present application, “a single layer” means that the linear element overlaps with itself by at most 30%.

[0033] It is pointed out that it is necessary that the linear element or the linear elements form a single layer around the monofilament and that there are no further layers of wrapped linear elements on top of said single layer.

[0034] The main effect of using just a single layer of wrapped linear elements is that the weight of further layers of wrapped linear elements can be saved.

[0035] The single layer of wrapped linear elements covers at least 90% of the surface of the thermoplastic monofilament which means that the thermoplastic monofilament is essentially completely covered and concealed by the linear element. This level of coverage can be achieved by wrapping one linear element around the monofilament in an extremely tight manner or by wrapping several linear elements around the monofilament in such a manner that they form directly adjacent helices. The effect of the coverage of at least 90% of the surface area is that only by this coverage, the reinforcing structure can get a roughness which is large enough to provide good adhesion to polymeric materials into which the reinforcing structure according to the present application has to be embedded. Adhesion is especially problematic in the case of rubber as used for tires as many polymers show very poor adhesion properties to rubber. In an embodiment, the coverage of the monofilament by the linear element is 95%, 98%, 99% or 100%. The coverage improves the interaction between the reinforcing structure and the material to be reinforced (e.g. rubber) as it improves the chemical interaction between the reinforcing structure and the material to be reinforced.

[0036] The linear elements form an angle with a line perpendicular to the monofilament. This angle is called the “wrapping angle”. According to the application, the wrapping angle is positive if it describes a clockwise rotation from the linear element to the monofilament and it is negative if it describes a counterclockwise rotation from the linear element to the multifilament.

[0037] Every linear element forms a wrapping angle of at least ±15 degrees. In an embodiment, the wrapping angle is at least ±23 degrees. In an embodiment, the wrapping angle is at least ±30 degrees. In an embodiment, the wrapping angle is at least ±40 degrees.

[0038] Every linear element forms a wrapping angle of at most ±85 degrees. In an embodiment, the wrapping angle is at most ±70 degrees. In an embodiment, the wrapping angle is at most ±60 degrees. In an embodiment, the wrapping angle is at most ±50 degrees.

[0039] In an embodiment, the linear elements are wrapped around the monofilament in at least 70 turns per meter (tpm). In an embodiment, the linear elements are wrapped around the monofilament in at least 270 tpm. In an embodiment, the linear elements are wrapped around the monofilament in at least 1000 tpm. In an embodiment, the linear elements are wrapped around the monofilament in at least 5000 tpm. In an embodiment, the linear elements are wrapped around the monofilament in at least 7000 tpm. In an embodiment, the linear elements are wrapped around the monofilament in at least 10000 tpm.

[0040] In an embodiment, the linear elements are wrapped around the monofilament in at most 1000 tpm. In an embodiment, the linear elements are wrapped around the monofilament in at most 5000 tpm. In an embodiment, the linear elements are wrapped around the monofilament in at most 7000 tpm. In an embodiment, the linear elements are wrapped around the monofilament in at most 9000 tpm. In an embodiment, the linear elements are wrapped around the monofilament in at most 13000 tpm. The number of turns n in the wrapping is directly connected to both the wrapping angle a and the diameter d in meters of the monofilament by the following formula:

[0041] In an embodiment, wrapping of the linear elements around the monofilament is carried out by cord twisting. In an embodiment, wrapping of the linear elements around the monofilament is carried out by cabling or any other technique known to the person skilled in the art. One possible device to produce a reinforcing structure according to the present application is disclosed in European Patent Application 23181456.

[0042] The residual torsion of the reinforcing element according to the present application is at most ±0.6 turns per meter, measured according to ASTM D2969-02 which is incorporated herein in in its entirety by reference. It is noted that ASTM D2969-02 refers to steel cord, however it is used mutatis mutandis also for the reinforcing elements according to the present application. It is noted that in ASTM D2969-02 the residual torsion is given per six meter of the reinforcing element. In the present application “turns per meter” has been used for compatibility with Sl-units. The quantity in “turns per six meters” can be obtained from the values named here by multiplying with 6.

[0043] In an embodiment, the residual torsion is at most ±0.4 turns per meter, ±0.3 turns per meter or ±0.2 turns per meter.

[0044] The residual torsion of the reinforcing structure is a property that has major influence mainly on the processability of the reinforcing structure during e.g. tire production. Thus, tire producers have high requirements concerning residual torsion that reinforcing structures have to fulfill.

[0045] In an embodiment, the reinforcing structure is provided with an adhesionpromoting agent. The function of such agent is to improve the adhesion between the reinforcing structure and the material into which it is embedded. The necessity and choice of the adhesion promoting agent depends on the material of the reinforcing structure and the material into which the reinforcing structure is to be embedded. A commonly used adhesion promoting agent is the so-called RFL dip which comprises resorcinol, formaldehyde and latex and which is commonly used e.g. to treat polymer surfaces to improve adhesion to rubber. Due to health and environmental issues, efforts are put in the development of alternatives to the RFL dip based on e.g. acrylic polymers which are free of resorcinol and / or formaldehyde. Other so-called RFL free dips may comprise latex together with other components such as isocyanates, epoxy resins, polyamines such as polyether amines (e.g. “Jeffamines”®), piperazine or other polyamines or polyphenols in various combinations. The skilled person knows that many dip combinations comprise monomer combinations of typical thermosetting resins. The residual torsion of the reinforcing structure is a composed quantity which comprises contributions from the linear element as well as from the wrapping. In general, the residual torsion RT in units of turns per meter (tpm) can be described by the following formula:

[0046] RT (reinforcing structure) — RT (mono filament) < ± 0.6 tpm

[0047] This means that according to the present application, it is possible to adjust the residual torsion of the reinforcing structure by providing acting on the wrapping in order to compensate the residual torsion that may be present in the monofilament obtaining a final residual torsion of the reinforcing structure that is closer to zero than the residual torsion of the monofilament. According to the present application, it is possible to modify the residual torsion of the monofilament by ±1 turn per meter by the wrapping procedure.

[0048] In an embodiment, the monofilament of the core component comprises at least one filament which is embedded in the monofilament. The filament may be a single filament which is comprised in the monofilament in a similar manner as a spaghetto can be stuck into a bucatino. The filament comprised in the monofilament may be a single filament or a multifilament. A multifilament may be connected by an adhesive agent either at connection points or by full impregnation. As an alternative or in addition, the multifilament may be tangled or twisted.

[0049] In any case the filament or multifilament is comprised within the monofilament. In an embodiment, the smoothness of the surface of the monofilament is not influenced. In this case, the material of the monofilament covers the filament and / or multifilament entirely in such a manner that surface irregularities caused by the filament and especially the multifilament are completely compensated. The monofilament according to the present application has a homogeneous surface no matter whether it comprises a filament, a multifilament or none of these.

[0050] A possible function of the filament and / or multifilament is to provide further reinforcement to the reinforcing structure. The filament and / or multifilament may thus be of high-tenacity or comprise high-tenacity fibers which will improve the strength properties of the reinforcing structure.

[0051] In another embodiment, the filament or multifilament is covered by a very thin layer of thermoplastic material which does not compensate the surface irregularities but kind of replicates the structure of the filament or monofilament just smoothing it up slightly. Such thin layer still precludes that the filament or multifilament can still be separated into several elements e.g. by spreading or by counter-twisting without irreversibly destroying the monofilament.

[0052] The material of the filament and / or multifilament can be chosen from glass, carbon fibers, steel wire, aluminum wire, polyethylene terephthalate (PET) or organic polymers. Possible organic polymers that may be comprised in the filament and / or multifilament are thermoplastic and / or thermosetting polymers such as polyesters (polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polyethylene furanoate (PEF), and the like), aromatic polyesters, aliphatic polyamides (such as polyamide-5, polyamide-6, polyamide-6,6, polyamide-5,6, polyamide-4,10, polyam ide-6, 10, polyamide-6, 8, polyamide-10 or polyamide-11), aromatic polyamides such as aramids (para-polyphenylene terephthalamide, metapolyphenylene isophthalamide), polyvinyl alcohol, polyvinyl acetate, polyphenylene benzobisoxazole (PBO), polybenzimidazole (PBI), polyetheretherketone (PEEK), ultra-high molecular weight polyethylene (UHMWPE), polyurethane (PUR) or copolymers comprising monomers of said materials or mixtures or blends of said materials but is not limited to this selection.

[0053] The material of the filament and / or multifilament may have elastomeric properties, namely thermoplastic elastomeric properties which means that it is formed from molecular chains which are interconnected by non-bonding interactions at room temperature, providing them with elastomeric properties. Typical thermoplastic elastomers are polyurethanes with long polyol chain contributions or thermoplastic elastomers of the polyester-ester or the polyether-ether type. Typical product names are Elastane, Spandex and Lycra®.

[0054] The material of the filament and / or multifilament may in part or completely be of biological origin. The material of the filament and / or multifilament may thus also be cellulosic or proteinic fibers such as cotton fibers, viscose fibers, lyocell fibers, linen fibers, hemp fibers, abaca fibers, sisal fibers, wool fibers of sheep, goats or any other mammals or silk fibers from the cocoons of the species Bombyx mori or from any other insects that produces suitable fibers. The material of the filament and / or multifilament may in part or completely be made from recycled plastics. Materials of biological and recycling sources may be combined.

[0055] In an embodiment, the filament and / or multifilament may comprise a nucleating agent. Said nucleating agent may be talc or a similar inorganic filler, sodium benzoate, sodium stearate, sodium-ion ionomers, a sulfonamide compound metal salt or a sulfonimide compound metal salt, mono sodium salt of dicarboxylic acid, and mixtures thereof, as known in the art.

[0056] The filament and / or multifilament may furthermore comprise an adhesion promotion agent. The skilled person knows this also under the term “dip” or “dipping”. Said adhesion promotion agent may e.g. be the so-called RFL-dip comprising resorcinol, formaldehyde and latex or any other adhesion promoting agent which may e.g. be acrylic polymers, isocyanates, epoxides, polyols or other agents known to the person skilled in the art. It is important to notice that the possible material of the monofilament and the filament and / or multifilament have some overlaps but that the monofilament and the filament and / or multifilament may also comprise different materials.

[0057] A possible process to produce the monofilament comprising a filament and / or multifilament is co-extrusion where the filament and / or multifilament is guided through an extrusion die through which, at the same time, molten polymer is pressed which impregnates, surrounds and conceals the filament and / or monofilament. In such case, the filament and / or multifilament has a melting point that is higher than the melting point of the monofilament.

[0058] The application further pertains to a process of making a reinforcing structure according to the present application comprising the steps of providing a monofilament of a thermoplastic material and wrapping the monofilament with at least one linear structure in such a manner that the surface of the monofilament is covered by at least 90 %.

[0059] The application further pertains to a tire comprising a reinforcing structure according to the present application. Said tire may be any vehicle tire such as a tire for a private car, a truck, a motorcycle, an agricultural, construction or mining vehicle or a self-moving machine such as a bagger, a crane or a harvester. Furthermore, the tire may be a tire for an airplane which may be a private, a commercial or a military aircraft. The reinforcing structure according to the present application may further be used for other elastomeric articles such as skirts for hovercrafts, transmission belts, conveyor belts or air bumpers.

[0060] The reinforcing structure according to the present application may be comprised in the in the reinforcement belt, in the bead reinforcement, in the reinforcement carcass or in the cap-ply of the tire or any other reinforcing element inside a tire known to the person skilled in the art. Examples

[0061] Example 1

[0062] A yarn for a cap-ply of a tire was formed using a monofilament of polyethylene terephthalate with a thickness of 0.45 mm and with a twisted polyamide-66 multifilament yam (Enka® Nylon 140 HRT, 210 filaments) of 100 turns per meter (tpm) and a linear density of 1440 dtex embedded to it. Said monofilament was wrapped with a single layer of untwisted polyamide-66 multifilament yam (Enka® Nylon 140 HRT, 280 filaments) with a linear density of 1880 dtex. Wrapping was carried out with a pitch of 3.8 mm.

[0063] Example 2

[0064] A yam for a cap-ply of a tire was formed using a monofilament of ether-ester elastomer (Hytrel® available from Dupont) with a thickness of 0.4 mm with a twisted polyphenylene terephthalamide multifilament yam (TEIJIN TWARON® type 840, 500 filaments) with 100 tpm and 840 dtx embedded to it. Said monofilament was wrapped with a single layer of untwisted polyamide-66 multifilament yam (Enka® Nylon 140 HRT, 280 filaments) with a linear density of 1880 dtex. Wrapping was carried out with a pitch of 3.6 mm.

[0065] Example 3

[0066] A yam for a carcass of a tire was formed using a monofilament of ether-ester elastomer (Hytrel® available from Dupont) with a thickness of 0.5 mm with an embedded twisted rayon cord (VISCORD® RAYON CS3, 1000 filaments) with 200 tpm and 1840 dtex. Said monofilament was wrapped with a single layer of untwisted PET multifilament yam (DSP® HMLS, 480 filaments) with 1670 dtex. Wrapping was carried out with a pitch of 2.3 mm.

[0067] Example 4

[0068] A yam for a carcass of a tire was formed using a monofilament of co-polyamide (Ultramide® of BASF) with a thickness of 0.42 mm with an embedded twisted multifilament PET yarn (DSP® HMLS, 320 filaments) with 150 tpm and a linear density of 1100 dtex. Said monofilament was wrapped with a single layer of untwisted PET multifilament yam (DSP® HMLS, 782 filaments) with a linear density of 2200 dtex. Wrapping was carried out with a pitch of 4.2 mm.

[0069] Example 5

[0070] A series of yams was produced comprising a steel wire core co-extruded with a PET layer which layer was produced from HMLS-PET. Said core was wrapped with a flat textile yam of either Nylon (NY), PET or polyphenylene terephthalamide (aramide, AR) either in S or Z direction. The members of the series are listed in the table below.

[0071] Linear

[0072] Total core Diameter of density of diameter steel wire Wrapping wrapping [mm] [mm] material [dtex] pitch direction Example 6

[0073] A series of yams was produced comprising a core of flat textile yam of either polyphenylene terephthalamide (aramide, AR) or rayon (RY) co-extruded with a

[0074] PET layer which layer was produced from HMLS-PET. Said core was wrapped with a flat textile yam of PET either in S or Z direction. The members of the series are listed in the table below.

[0075] Linear Linear density of density of

[0076] Total core core wrapping diameter Material of material material [mm] core [dtex] [dtex] pitch direction

[0077] Example 7

[0078] A series of yams was produced comprising a core of thermoplastic monofilament of either PET or Nylon (NY). Said core was wrapped with a flat textile yam of PET either in S or Z direction. The members of the series are listed in the table below.

[0079] Linear density of

[0080] Core wrapping

[0081] Core diameter material material [mm] [dtex] pitch direction

Claims

Reinforcing structureClaims:1 . A reinforcing structure comprising• a monofilament of thermoplastic material forming the core component,• one single linear element wrapped around the core component as a single layer, wherein the single layer of the at least one linear element covers at least 90% of the surface area of the thermoplastic monofilament and wherein the reinforcing structure has a residual torsion of at most ±0.6 torsions per meter, measured according to ASTM D2969-02.

2. The reinforcing structure of claim 1 wherein the reinforcing structure is provided with an adhesion promoting agent such as an RFL dip or an acrylic dip.

3. The reinforcing structure of claim 1 or 2 wherein the residual torsion RT of the reinforcing structure follows the equation RT(reinforcing structure) - RT(thermoplastic monofilament) < ±0.6.

4. The reinforcing structure of any one or more of the previous claims wherein the monofilament of thermoplastic material comprises at least one embedded filament, preferably several filaments, most preferably of a different material embedded therein.

5. The reinforcing structure of claim 4 wherein the at least one filament comprises glass, carbon fibers, steel wire, aluminum wire, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyvinyl acetate(PVA), cellulose filaments, polyvinyl alcohol, polyvinyl acetate, polyamide-5, polyam ide-6, polyam ide-5,6, polyamide-5, 10, polyam ide-6,6, polyam ide- 4,10, polyam ide-6, 10, polyamide-6,8, polyamide-10 or polyamide-11 , proteinous fibers, aromatic polyamides, polyphenylene benzobisoxazole (PBO), ultra high molecular weight polyethylene (UHMWPE) or aromatic polyesters or copolymers comprising monomers of said materials or mixtures of said materials.

6. The reinforcing structure of claims 5 or 6 wherein the at least one filament is embedded in the monofilament by co-extrusion.

7. The reinforcing structure of any one or more of the previous claims wherein the linear element comprises glass, carbon fibers, steel wire, aluminum wire, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyvinyl acetate (PVA), cellulose filaments, polyvinyl alcohol, polyvinyl acetate, polyamide-5, polyam ide-6, polyam ide-5,6, polyam ide-5, 10, polyamide-6,6, polyam ide-4, 10, polyam ide-6, 10, polyamide-6,8, polyamide- 10 or polyamide-11 , proteinous fibers, aromatic polyamides, polyphenylene benzobisoxazole (PBO), ultra high molecular weight polyethylene (UHMWPE) or aromatic polyesters or copolymers comprising monomers of said materials or mixtures of said materials.

8. The reinforcing structure of any one or more of the previous claims wherein the thermoplastic monofilament comprises polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN) aromatic polyesters, aromatic polyamides such as polyvinyl alcohol, polyvinyl acetate, polyphenylene benzobisoxazole (PBO), polyamide-5, polyamide-6, polyamide-6,6, polyamide-5, 6, polyam ide-4, 10, polyam ide-6, 10, polyamide-6,8, polyamide- 10 or polyamide-11 , ultra high molecular weight polyethylene (UHMWPE), polyurethane (PUR) or polyetheretherketone (PEEK), copolymers comprising monomers of said materials or mixtures of said materials.

9. The reinforcing structure of any one or more of the previous claims wherein the residual torsion of the reinforcing structure is at most ±0.5 turns permeter, preferably at most ±0.4 turns per meter, more preferably at most ±0.3 turns per meter and most preferably at most ±0.2 turns per meter.

10. Process of making a reinforcing structure according to any one or more of claims 1 to 9 comprising the steps of • Providing a monofilament of a thermoplastic material,• Wrapping the monofilament with at least one linear structure in such a manner that the surface of the monofilament is covered by at least 90 %.11 .A tire comprising at least one reinforcing structure according to any one or more of claims 1 to 9.

12. The tire according to claim 11 , wherein the reinforcing structure is comprised in the reinforcement belt, in the bead reinforcement, in the reinforcement carcass or in the cap-ply.

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