Rubberized strength carrier for elastomeric products, especially vehicle tires, wherein the strength carrier comprises at least one yarn, method for manufacturing the rubberized strength carrier and vehicle tire comprising at least one rubberized strength carrier

Description

[0001] The invention relates to a rubberized reinforcement carrier for elastomeric products, in particular vehicle tires, wherein the reinforcement carrier comprises at least one first yarn, a method for producing the rubberized reinforcement carrier and a vehicle tire comprising at least one rubberized reinforcement carrier.

[0002] Reinforcing elements for various elastomeric products are well known. For example, it is known that vehicle tires typically contain various reinforcing elements in different components, each surrounded by a rubber compound, also called a rubber compound. These reinforcing elements are thus present in the vehicle tire as rubberized reinforcing elements.

[0003] In such components where textile reinforcement is used, polyethylene terephthalate (PET) is often used as the material of the (textile) reinforcement.

[0004] It is also known that PET with special properties can be used, such as HMLS-PET. HMLS-PET stands for High Modulus Low Shrinkage Polyethylene Terephthalate. It is used particularly in the carcass layer of pneumatic tires to optimize flat spot behavior (reversible plastic flattening in the contact patch when parked) and to prevent extensive sidewall constriction. Furthermore, efforts are being made to resolve, or at least improve, existing conflicts of objectives between sustainability and performance requirements when selecting materials for elastomeric products such as vehicle tires.

[0005] German patent DE 102010017107 A1 discloses a reinforcing cord which contains at least one yarn made from recycled PET. The recycled PET can, in particular, originate from PET beverage bottles.

[0006] CN 108 084 424 A discloses an HMLS yarn which is obtained by means of solid-phase polymerization and uses PET recycled from bottles as a starting material.

[0007] However, the use of recycled PET is limited by its properties. For example, recycled PET from bottles contains additives that impair crystallization during processing, particularly during the spinning process into industrial yarn. This results in inferior physical properties compared to traditional PET, i.e., PET that is not recycled but originally produced. This is especially relevant for PET that has high requirements regarding shrinkage, deformability, stretch, and strength.

[0008] The present invention is therefore based on the objective of providing a rubberized reinforcement carrier for elastomeric products, in particular vehicle tires, wherein the reinforcement carrier has at least one first yarn, which has high strength and high elongation and is produced in the most resource-efficient, sustainable and environmentally friendly way possible.

[0009] This problem is solved by using a yarn made of HMLS-PET, which includes recycled PET, as the first yarn.

[0010] Preferably, the first yarn contains 10 to 100% recycled PET by weight.

[0011] The first yarn made of HMLS-PET comprising recycled PET, preferably 10 to 100 wt% recycled PET, is also referred to as "the first yarn" within the scope of the present invention.

[0012] Surprisingly, a rubberized reinforcing carrier comprising at least one yarn made of PET could be provided, wherein the yarn comprises recycled PET, preferably 10 to 100 wt.%, and simultaneously exhibits a high modulus and thus high strength with low shrinkage, and can therefore be classified as HMLS-PET yarn.

[0013] The reinforcing material according to the invention has the advantages that it is produced in a more resource-efficient and environmentally friendly way than original ("virgin") PET and yet still meets the high requirements for its properties, especially for use in elastomeric products, such as in the carcass layer of vehicle tires.

[0014] The weight specifications in percent (wt%) refer to the ungummed and untreated, i.e., in particular undipped, yarn.

[0015] In the context of the present invention, "recycled PET" means PET that has been obtained from waste PET products such as PET bottles or other PET articles such as clothing.

[0016] The immediate starting material for recycled PET is not petroleum, but bottles or other items made of PET.

[0017] The preferred method for obtaining recycled PET with HMLS properties is explained in more detail below.

[0018] Further advantages and features of the reinforcing element according to the invention will become apparent from the dependent claims, which relate to advantageous embodiments of the present invention and are not to be understood as limiting. The invention also encompasses combinations of features from different dependent claims, insofar as these are technically possible, even if the dependent claims do not relate to each other or if they belong to different claim categories. This also applies to the individual features of the exemplary embodiments discussed below, insofar as these are not recognizable to a person skilled in the art as necessarily belonging together. The invention also encompasses combinations of features that are characterized as preferred, particularly preferred, etc., wherein a first feature designated as "preferred" is combined with a further second feature as, for example,"particularly preferred" can be combined unless otherwise expressly stated in terms of content or technology.

[0019] In the event that the reinforcing material comprises less than 100 wt.% recycled PET, i.e., for example, and in particular, 10 to < 100 wt.% recycled PET, the remaining proportion is virgin PET. (engl. Virgin PET), which has not undergone a recycling process and is made from petroleum-based (petrochemical) or renewable raw materials.

[0020] With a content of 10 to 100 wt% recycled PET in the first yarn, the price and CO2 emissions in the production of the rubberized reinforcement carriers and vehicle tires according to the invention can be individually adjusted.

[0021] The problem underlying the invention is particularly well solved with a higher proportion of recycled PET, but even a proportion of recycled PET of, for example, 10 wt% contributes to resource conservation and a lower CO2 footprint.

[0022] According to advantageous embodiments, the first yarn made of HMLS-PET comprises 20 to 100 wt.% recycled PET.

[0023] According to advantageous embodiments, the first yarn made of HMLS-PET comprises 30 to 100 wt.% recycled PET.

[0024] According to advantageous embodiments, the first yarn made of HMLS-PET comprises 40 to 100 wt.% recycled PET.

[0025] According to advantageous embodiments, the first yarn made of HMLS-PET comprises 50 to 100 wt.% recycled PET.

[0026] According to advantageous embodiments, the first yarn made of HMLS-PET comprises 60 to 100 wt.% recycled PET.

[0027] According to advantageous embodiments, the first yarn made of HMLS-PET comprises 70 to 100 wt.% recycled PET.

[0028] According to advantageous embodiments, the first yarn made of HMLS-PET comprises 80 to 100 wt.% recycled PET.

[0029] According to advantageous embodiments, the first yarn made of HMLS-PET comprises 90 to 100 wt.% recycled PET.

[0030] According to advantageous embodiments, the first yarn made of HMLS-PET comprises 100 wt.% recycled PET.

[0031] In particular, the yarn made of HMLS-PET preferably comprises 30 to 100 wt.%, especially preferably 50 to 100 wt.%, recycled PET.

[0032] Recycled PET differs from virgin PET in its additives, particularly its isophthalic acid (IPA) content. These additives, especially IPA, are found, for example, in PET bottles.

[0033] While virgin PET has an isophthalic acid content of 0 wt%, the IPA content in recycled PET can be up to 5 wt%.

[0034] In particular, for the recycled PET used in the context of the present invention, it amounts to, for example, and especially, 1.2 to 2.2 wt.%.

[0035] The weight specifications in percent (wt%) refer to the PET and thus, in the strength carrier according to the invention, to the ungummed and untreated, i.e., in particular, undipped, yarn.

[0036] With a proportion of 10 wt.% recycled PET and 90 wt.% virgin, petroleum-based PET, the isophthalic acid content is therefore 0.12 to 0.5 wt.%, preferably 0.12 to 0.22 wt.%.

[0037] Thus, the first yarn made of HMLS-PET preferably has an isophthalic acid (IPA) content of 0.12 to 5 wt.%, for example and preferably 0.12 to 2.2 wt.%.

[0038] An "HMLS yarn" is understood to be a yarn that has a high modulus and low shrinkage.

[0039] The first yarn made of HMLS-PET particularly and preferably has a heat shrinkage of less than 8%, especially preferably 4 to 8%, and an elongation at 45 N of less than 0.0056% / Den (percent per denier, where 1% / Den = 9% / 10dTex means), especially preferably 0.002 to 0.0056% / Den, at filament finenesses of less than 5 Den (where 1 Den = 10 / 9 dTex means), especially preferably 3 to 5 Den.

[0040] This information is particularly suitable for characterizing the first yarn made from HMLS-PET as HMLS yarn.

[0041] The first yarn of the reinforcing material according to the invention preferably has a tensile strength of 7.0 to 9.0 g / Den (grams per denier, where 1g / Den = 9g / 10dTex).

[0042] The first yarn of the reinforcing material according to the invention preferably has an elongation at break of 10.2 to 15.5%.

[0043] The first yarn is in particular and preferably an endless multifilament yarn and therefore preferably not a monofilament yarn and preferably not a staple fiber yarn.

[0044] The first yarn of the reinforcing material according to the invention preferably comprises filaments with filament fineness of less than 5 denier, i.e., each filament of the yarn is preferably finer than 5 denier. Particularly preferably, the first yarn has filament fineness of 3 to 5 denier.

[0045] Preferably, the first yarn exhibits an elongation of less than 0.0056% / den at a force of 45 N.

[0046] The tensile strength, the elongation at 45 N and the elongation at break are determined within the scope of the present invention using an Instron tensile testing device. (engl."Instron tensile tester") according to ASTM D885: Device Instron 5564, terminal (engl. "clamp"): C-clamp, 2714-004 with pneumatic activation (engl. "pneumatic activation", loading capacity 1 kN (one kilonewton), test conditions: measuring length (engl. "gauge length") 250 mm, crosshead speed (engl. "cross head speed") 300 mm / min, preload 0.05 gf / Den (Gram-force per Denier), air pressure 0.4 to 0.6 MPa, conditioning of samples before testing: 24 hours at 24 ± (plus minus) 2 °C, 55 ± 5 % humidity.

[0047] The first yarn of the reinforcing material according to the invention preferably exhibits a heat shrinkage at 177 °C of 3.2 to 5.2%.

[0048] The heat shrinkage of yarns is determined within the scope of the present invention using the hot air shrink method according to ASTM D885. The test conditions are: temperature 177°C, load 0.05g / den, duration 10 min.

[0049] Preferably, the first yarn made of HMLS-PET has a degree of crystallinity of 45 to 53.5%.

[0050] The degree of crystallinity is determined according to ASTM D1505 as follows: Using a density gradient column ( English Using the density gradient column, the yarn density is first determined. The degree of crystallinity is then calculated by interpolation based on the following literature values ​​for the density of 100% amorphous and 100% crystalline PET. The density of 100% amorphous PET is 1.333 g / cm³, while that of 100% crystalline PET is 1.455 g / cm³.

[0051] With such a degree of crystallization, the yarn and thus the reinforcing material according to the invention can be produced and simultaneously exhibits the properties necessary for the high requirements, especially when used in the carcass layer of vehicle tires, with regard to elongation and shrinkage behavior.

[0052] Preferably, the first yarn made of HMLS-PET has a fineness of 300 to 4000 denier (Den), preferably 300 to 3100 Den, particularly preferably 300 to 2000 Den, and most preferably 900 to 2000 Den.

[0053] According to a first embodiment, the first yarn is twisted and further processed as described below. In this embodiment, the reinforcing element according to the invention comprises a twisted, rubberized yarn.

[0054] According to the invention, yarns are twisted to form a cord. In each case, a first yarn as described in the invention comprises an HMLS-PET yarn, preferably 10 to 100 wt.% recycled PET.

[0055] According to a particularly preferred embodiment, at least one further (second) yarn also comprises an HMLS-PET yarn, preferably 10 to 100 wt.% recycled PET, such that, according to this embodiment, at least two of the described HMLS-PET yarns are twisted together to form a cord.

[0056] According to the invention, the first yarn is twisted into a 2-strand cord, wherein the cord has a twist factor of 150 to 250, preferably 170 to 230, and a breaking strength of at least 6.3 g / den, preferably 6.3 to 10 g / den, and an elongation at 45 N of less than 0.0056% / den, preferably 0.0005% to 0.0040% / den, and a heat shrinkage of less than 3%, preferably 1 to 3%, and particularly preferably 1.5% to 2.5%. The term "2-strand cord" means that two yarns have been twisted together.

[0057] According to the described embodiment, a first yarn - as described in the invention, an HMLS-PET yarn comprising recycled PET - is twisted together with preferably a second further HMLS-PET yarn comprising recycled PET to form a cord.

[0058] The heat shrinkage of cordent is determined according to the present invention using the hot air shrinkage method according to ASTM D885 at 180 °C. The test conditions are: temperature 180 °C, load 0.05 g / den, duration 10 min.

[0059] According to further preferred embodiments, it is also conceivable that the at least one further yarn is a different yarn, and thus the reinforcing element according to the invention is a hybrid cord comprising an HMLS-PET yarn, preferably 10 to 100 wt.% recycled PET, and at least one further yarn. Preferably, the at least one further yarn is made of a non-metallic material. The non-metallic material is preferably selected from the group consisting of polyamide (PA) and / or aramid and / or polyetherketone (PEK) and / or polyketone (POK) and / or polyethylene naphthalate (PEN) and / or rayon and / or viscose and / or natural fibers and / or glass fibers.

[0060] The described yarns and / or cords are woven into a textile layer according to preferred embodiments before being further processed by adhesion activation and gumming with a gumming mixture.

[0061] Another object of the present invention is a reinforcement layer made of a plurality of rubberized reinforcement layers according to the invention.

[0062] Another object of the present invention is a vehicle tire which has at least one rubberized reinforcing element according to the invention.

[0063] According to advantageous embodiments of the invention, the vehicle tire has a plurality of rubberized reinforcing elements according to the invention in a reinforcing element layer.

[0064] Preferably, the reinforcing layer is the carcass layer and / or a belt bandage and / or a belt layer and / or a bead reinforcement, particularly preferably at least the carcass layer.

[0065] The vehicle tire according to the invention can therefore also have the reinforcing element according to the invention in one or more components, preferably at least in the carcass layer.

[0066] According to an advantageous embodiment of the invention, the reinforcing layer is at least the carcass layer, wherein the carcass layer is wrapped once (single-layer construction) or twice (two-layer construction) around the bead as part of a layer wrap, with the end of the layer(s) lying between the core and the belt edge. This allows the vehicle tire to fulfill its required load-bearing capacity (taking into account the respective load index).

[0067] According to an advantageous further development of this embodiment, in addition to the one or two carcass layers that are guided around the bead, a further reinforcing layer comprising reinforcing elements according to the invention is arranged in the side wall up to or below the bead.

[0068] This further improves the vehicle tire's load-bearing capacity.

[0069] The following describes a particularly preferred method for obtaining the first yarn of the rubberized reinforcing material. The yarn is produced as an endless multifilament yarn, as described. Unless otherwise specified, equipment known to those skilled in the art is used in carrying out the process steps described in detail. a) Provision of PET chips comprising 100% by weight of recycled PET from PET bottles or other PET products and optionally provision of chips made from virgin ( English "virgin") PET; b) Precrystallization ( English "pre-crystallization"), crystallization and solid-state polymerization ( Englishsolid-state polymerization (SSP) of the PET chips from step a), yielding high-viscosity PET chips with an intrinsic viscosity of 0.85 to 1.15 dl / g (deciliters per gram); c) drying, optionally mixing the recycled PET chips with virgin PET chips to obtain PET chips comprising 10 to 100 wt% recycled PET chips, melting and extruding the PET chips for yarn spinning, subsequent yarn spinning using a spinneret comprising a reheater with a buffer zone, and stepwise cooling of the unstretched yarn, wherein the water content of the chips after drying is less than 30 ppm, the temperature of the reheater below the spinneret is 280 to 350 °C, and the length of the buffer zone below the reheater during stepwise cooling is 20 to 100 mm; d) Oiling, drawing, heat curing and winding after the gradual cooling in step c), resulting in an HMLS-PET yarn.

[0070] Experts are aware that recycled PET can be supplied in the form of chips. These chips can also be referred to as "granules".

[0071] "PET chips comprising 100% by weight recycled PET from PET bottles or other PET products" are also referred to here as "chips made from recycled PET".

[0072] In the present invention, the intrinsic viscosity is determined using an Ubbelohde capillary viscometer ( English "Ubbelohde Capillary Viscometer") determined according to ASTM D4603.

[0073] In the event that the yarn contains less than 100% recycled PET by weight, in particular 10% to <100% recycled PET by weight, the remaining proportion is virgin PET ( English Virgin PET), which has not undergone a recycling process and is made from petroleum-based (petrochemical) or renewable raw materials.

[0074] In this case, in an additional process step – referred to above as "optional mixing" – chips made from recycled PET and chips made from virgin PET are mixed together before the spinning process. This mixing preferably takes place in a single-screw conveyor system after the drying step.

[0075] If 100% recycled PET by weight is used, the additional mixing step is not necessary and the chips are dried and extruded directly.

[0076] Due to the additives present in recycled PET, for example alternative monomers to p Terephthalic acid, such as IPA, weakens the crystallization ability of PET during the spinning process. This makes spinning and drawing into yarn more difficult, and its properties are worse than those of yarn made from virgin PET.

[0077] Through pre-crystallization ( English"pre-crystallization"), crystallization and solid-state polymerization ( EnglishIn step b), solid-state polymerization (SSP) results in further polymerization and thus a reduction in the proportion of shorter polymer molecules, leading to molecular chain growth. This results in increased intrinsic viscosity. This improves the drawability of the material, as well as the tensile strength and modulus (stiffness) of the yarn. By combining pre-crystallization and crystallization with the post-heating temperature below the spinneret (280–350 °C) and the length of the buffer zone below the post-heating zone during the gradual cooling (20–100 mm) in step c), the crystallization rate can be adjusted to allow for high spinning speeds and high tensile strengths during the spinning process. Furthermore, the frequency of filament and yarn breakage is reduced, resulting in a yarn with high tensile strength and a high modulus.

[0078] Solid-state polymerization ( English Solid-state polymerization (SSP) is a process in which raw PET chips are placed in a reactor and heated to polymerize. This increases the molecular chain length and intrinsic viscosity. The intrinsic viscosity of recycled PET chips is 0.55 to 0.75 dl / g. The term solid-state polymerization is also referred to as solid-phase condensation in German, because condensation occurs due to the removal of water.

[0079] These relatively low-viscosity raw chips are preferably treated as follows: The raw PET chips are preferably pre-crystallized for 0.5 to 1.5 hours at a temperature of 150 to 180 °C, then crystallized for 4 to 6 hours at a temperature of 200 to 230 °C, and finally allowed to react for 30 to 35 hours in an SSP reactor at a wall temperature of 200 to 220 °C.

[0080] The entire system of devices is operated in a nitrogen atmosphere, with the oxygen content of the nitrogen being maintained at 30 to 70 ppm and the dew point preferably being lower than -70 °C (lower than minus 70 °C).

[0081] The intrinsic viscosity of the raw PET chips is increased to 0.85 to 1.15 dl / g, resulting in highly viscous chips.

[0082] Preferably, in step c) drying takes place under nitrogen, with the drying temperature preferably being 120 to 160 °C and the drying time preferably being more than 8 hours. This reduces the water content of the high-viscosity chips to less than 30 ppm.

[0083] Preferably, the melting and extrusion of the high-viscosity PET chips in step c) is carried out as a melt extrusion in a screw extruder, wherein the temperature in the feeding zone of the screw extruder is 300 to 330 °C, the temperature in the compression zone is 290 to 320 °C, and the temperature in the metering zone (discharge zone) is 280 to 310 °C, and the pressure at the extruder head is 14 to 18 MPa (megapascals). A melt is obtained from this process.

[0084] Furthermore, melt extrusion can improve the melt viscosity and fluidity of the high-viscosity chips, further reduce the negative effects caused by the IPA content, and thus further improve drawability.

[0085] In the case that highly viscous chips made from recycled PET have previously been mixed with chips made from virgin PET, the extrusion step further improves the homogeneity of the mixture of recycled and virgin PET.

[0086] Preferably, the spinning (in step c) is carried out using a spinning jet, wherein the length-diameter ratio (L / D) of the spinneret opening is 1.2 to 3.0 according to advantageous embodiments.

[0087] According to advantageous embodiments, the spinneret comprises 180 to 480 openings and a yarn with 1000 to 1500 denier is obtained.

[0088] According to further advantageous embodiments, a yarn with a denier (Den) of 300 to 4000, preferably 300 to 3100, particularly preferably 300 to 2000, and most preferably 900 to 2000, can be obtained, for example, and particularly, 500 denier, 2000 denier, or 4000 denier. If a fineness of more than 1500 denier is selected, the number of spinneret openings can exceed 480.

[0089] Preferably, a yarn with filaments having a filament fineness of less than 5 denier (den) is obtained. Particularly preferably, a yarn with a filament fineness of 3 to 5 denier is obtained.

[0090] The gradual cooling in step c) serves the purpose of solidifying the melt of the undrawn yarn.

[0091] Preferably, the stepwise cooling in step c) comprises a circular quenching system following the buffer zone, wherein cooling air is blown from the outside into the inner ring, the blowing pressure being 15 to 50 Pa and the blowing temperature being 22 to 65 °C.

[0092] This prevents adhesion of the undrawn yarn, which simplifies or at least does not complicate the subsequent drawing process in step d). The preferred parameters of blowing pressure and temperature of the blown-in air prevent excessively rapid or slow cooling, which in turn prevents adhesion of the undrawn yarn and a deterioration of its physical properties.

[0093] If the undrawn yarn cools down too quickly, drawing it during spinning becomes particularly difficult.

[0094] If the undrawn yarn is cooled too slowly, there is a particular risk of increased adhesion and deterioration of the physical properties.

[0095] For the reasons mentioned above, it is particularly advantageous if the undrawn yarn is reheated, gradually cooled by means of a circular quenching system following the buffer zone, and cooled with cooling air after melt spinning.

[0096] Oiling in step d) has the advantage of increasing the cohesion of the undrawn yarn and reducing frictional forces and static electrical charges. This also facilitates the subsequent drawing process and reduces the frequency of filament and yarn breaks. Furthermore, it is also advantageous for the subsequent processing steps to the rubberized reinforcing layer or the fabric layer, particularly for twisting and weaving, as the oiling improves the yarn's gliding properties.

[0097] Preferably, the oil is used in an emulsion and the oil absorption rate is preferably 0.3 to 0.9 wt.% based on the yarn.

[0098] Preferably, the drawing in step d) is carried out using a galette roller construction, wherein a first galette roller pair (GW1) is operated at a speed of 2700 to 3200 m / min at a temperature of 60 to 80 °C, a second galette roller pair (GW2) is operated at a speed of 3800 to 5000 m / min at a temperature of 70 to 90 °C and a third galette roller pair (GW3) is operated at a speed of 5800 to 6200 m / min at a temperature of 210 to 260 °C and the drawing rate is preferably 1.81 to 2.30%.

[0099] This allows optimal properties of the manufactured yarn to be achieved, such as optimized tensile strength and elongation at break, as well as optimized heat shrinkage and modulus.

[0100] Preferably, the heat curing that takes place after drawing is carried out by means of a fourth pair of die rollers (GW4) at a speed of 5800 to 6200 m / min at a temperature of 210 to 260 °C, a subsequent fifth pair of die rollers (GW5) at a speed of 5600 to 6200 m / min at a temperature of 210 to 260 °C and a subsequent sixth pair of die rollers (GW6) at a speed of 5450 to 6000 m / min at a temperature of 100 to 150 °C, wherein the relaxation rate is 2.5 to 6.0%.

[0101] This allows for optimal crystallization, a stable microstructure, optimal tensile strength, optimal modulus, and a reduction in heat shrinkage. The yarn is thus optimally prepared for the subsequent winding process and heat curing.

[0102] Preferably, the winding in step d) is carried out at a winding speed of 5450 to 5950 m / min.

[0103] The described process steps a) to d) yield a yarn which has a tensile strength of 7.5 to 9.0 g / d, an elongation at break of 10.2 to 15.5%, a heat shrinkage of 3.2 to 5.2%, a degree of crystallinity of 45 to 53.5% and an IPA content of 0.12 to 5 wt.%, in particular 0.12 to 2.2 wt.%.

[0104] Furthermore, the yarn can be obtained with a fineness of 300 to 4000 denier.

[0105] The resulting HMLS-PET yarn comprising 10 to 100 wt.% recycled PET is further processed, in particular and preferably, by at least the following process steps to obtain the rubberized reinforcing carrier according to the invention: e) Twisting; f) Optional weaving; g) Applying a dip for adhesion; h) Applying a rubberizing compound

[0106] According to advantageous embodiments of the invention, the yarn is first twisted itself and then twisted together with another twisted yarn to form a cord.

[0107] The yarns used in the cord can each be made up of filaments twisted in either the S or Z direction. Thus, for example, the HMLS-PET yarn can be made entirely from recycled PET twisted in either the S or Z direction.

[0108] The twisted yarns are then end-twisted in the S or Z direction to form a reinforcing cord. Advantageously, the yarns of a reinforcing cord all have the same direction of twist, i.e., they are twisted either in the S or Z direction. In this advantageous variant, the reinforcing cord has the opposite direction of twist to the individual yarns. For example, an S-twisted HMLS-PET yarn made entirely of recycled PET can be end-twisted in the Z direction with another S-twisted HMLS-PET yarn – also made entirely of recycled PET – to form a reinforcing cord.

[0109] Alternatively, a corresponding hybrid cord could be obtained, for example, by twisting an S-twisted HMLS-PET yarn made entirely of recycled PET with another yarn at its end. Exemplary and preferred materials for the additional yarn are listed above.

[0110] According to advantageous embodiments of the invention, two yarns are twisted together in a direct cabling machine to form a cord made of two yarns (x2 cord).

[0111] The number of twists per meter (tpm) of the yarns and cords is preferably 100 to 500 tpm each. Preferably, cords comprising the first yarn have a twist factor (TF) of 150 to 250. The twist factor (TF) is calculated as follows according to Formula I): TF = N * K / 9000 ∧ 0 , 5 where N is the number of twists (in tpm) and K is the cord gauge, and "^0.5" represents the square root (of the expression in parentheses), so

[0112] During weaving (step f), the following should preferably be observed: When arranging the yarn on the creel, the tension of each yarn spool is controlled by roller bearings and rubber belts to ensure consistent tension. During the weaving process, the yarn is guided through the reed, which is adapted according to specifications, and woven on an air-jet loom. The cord is then woven into raw fabric of a preset width, the weft yarn being, in particular, a yarn with an elastic core made of, for example, PET or nylon, wrapped with, for example, cotton.

[0113] The raw fabric obtained in step f) is then further processed by means of a dip in step g). This gives the reinforcing material, in particular the yarn or cord, ideal physical properties and optimized adhesion to the subsequently applied rubber compound.

[0114] In particular, the dip may include a pre-dip, as well as an RFL dip (resorcinol formaldehyde latex) known in the prior art, or an environmentally and health-friendly RFL-free alternative, as described for example in DE 102014211362 A1 or WO 2019015792 A1.

[0115] The adhesion treatment by means of a dip according to step g) can therefore include, in particular, 1-bath or 2-bath processes (pre-dip and dip) known in the prior art.

[0116] During the dipping process, devices and conditions known in the prior art, such as immersion solution tanks, tension zones, and ovens, are used successively. The fabric or cord (depending on whether weaving is carried out according to step f)) is stretched by 0 to 8%, in particular 0 to 3%.

[0117] The subsequent rubber coating in step h) is carried out in a manner known to those skilled in the art, using a rubber coating mixture and devices known to those skilled in the art. If necessary, drying takes place at high temperatures, in particular above 100 °C, prior to rubber coating.

[0118] The rubberizing compound can be any suitable rubberizing compound known to a person skilled in the art for coating reinforcing elements, in particular textile reinforcing elements.

[0119] Preferably, the rubberizing compound contains at least one diene rubber.

[0120] Diene rubbers are rubbers that are formed by polymerization or copolymerization of dienes and / or cycloalkenes and thus have C=C double bonds either in the main chain or in the side groups.

[0121] According to advantageous embodiments, the diene rubber is selected from the group consisting of natural polyisoprene (NR), synthetic polyisoprene (IR), butadiene rubber (BR), solution polymerized styrene-butadiene rubber (SSBR) and emulsion polymerized styrene-butadiene rubber (ESBR).

[0122] According to advantageous embodiments, the rubberizing mixture contains at least one carbon black as a non-polar filler.

[0123] The carbon black is preferably used in the rubber compound in amounts of 0.1 to 100 phr, particularly preferably in amounts of 40 to 100 phr, and most preferably in amounts of 40 to 80 phr. It is again particularly preferred if the rubber compound contains 57 to 67 phr of at least one type of carbon black. This results in particularly good mixing properties with regard to tear resistance.

[0124] The described method, comprising at least steps a) to h), is a further object of the present invention. The reinforcing element according to the invention is preferably produced by this method. A further object of the present invention is therefore the reinforcing element obtained by means of the described method.

[0125] The invention will now be explained in more detail using several exemplary embodiments. To this end, Table 1 first provides an overview of yarns and their manufacturing parameters, which are used as examples in the reinforcing beam according to the invention.

[0126] The above statements apply in addition to the more precisely specified parameters. In particular, for all examples E1 to E6, the procedure according to steps a) to d) was carried out, including solid-phase polymerization as described above. The raw PET chips were pre-crystallized for 0.5 to 1.5 hours at a temperature of 150 to 180 °C, then crystallized for 4 to 6 hours at a temperature of 200 to 230 °C, and finally allowed to react for 30 to 35 hours in an SSP reactor at a wall temperature of 200 to 220 °C.

[0127] The entire system of devices was operated in a nitrogen atmosphere, with the oxygen content of the nitrogen being kept at 30 to 70 ppm and the dew point preferably being lower than -70 °C (lower than minus 70 °C). Table 1 E1 E2 E3 E4 E5 E6 Source of PET chips Recycled PET Mixture of recycled PET and virgin PET Percentage of recycled PET in the raw chip (wt%) 100 10 40 60 90 80 IPA content (wt%) 1,5 0,15 0,60 0,90 1,35 1,20 Intrinsic viscosity 0,55 0,70 0,68 0,72 0,75 0,75 Procedure parameters Intrinsic viscosity of high-viscosity chips 0,85 1,05 1,00 1,05 1,15 1,12 Dry kn Temperature (°C) 140 130 120 160 150 150 Time (hour) 8,5 8,0 9,0 9,5 8,5 8,5 Mix Mixing ratio (%) 100 10 40 60 90 80 Feeding zone temperature (°C) 315 330 310 320 300 300 T Compression zone (°C) 305 320 300 310 290 290 Extrusion Metering zone (°C) 295 310 290 300 280 280 Melt temperature (°C) 285 300 280 290 270 270 Pressure at the extruder head (MPa) 16 18 15 17 14 14 DEN (D) 1500 1000 1300 1500 1500 1500 Number of openings 370 180 280 320 480 480 Spin nen L / D 2,1 3,0 1,7 2,5 1,2 1,2 Post-heating temperature (°C) 315 350 305 330 280 320 Buffer zone length (mm) 60 100 45 75 20 100 Blowing pressure (MPa) 35 50 38 26 15 30 Blowing temperature (°C) 45 65 38 52 22 65 Oil Intake rate (wt%) 0,6 0,9 0,5 0,7 0,3 0,5 GW1 Speed ​​(m / min) 2950 2700 2900 2750 3200 3180 GW1 Temp. (°C) 70 80 66 74 60 80 Pull GW2 speed (m / min) 4400 5000 4200 4600 3800 3850 GW2 Temp. (°C) 80 90 76 84 70 90 GW3 speed (m / min) 6000 6200 5950 6050 5800 5800 GR3 Temp. (°C) 235 260 220 240 210 250 Train rate 2,03 2,30 1,97 2,20 1,81 1,82 GW4 speed (m / min) 6000 6200 5850 6050 5800 5800 GW4 Temp. (°C) 235 260 220 240 210 250 Would harden GW5 speed (m / min) 6000 6200 5850 6050 5800 5600 GW5 Temp. (°C) 235 260 220 240 210 250 GW6 speed (m / min) 5800 6000 5850 5850 5600 5450 GW6 Temp. (°C) 125 150 115 135 100 120 Relaxation rate (%) 3,3 4,0 2,5 3,3 3,5 6,0 Wraps Winding speed (m / min) 5800 5950 5800 5850 5600 5450

[0128] In Fig. 1 Examples E1 to E6 – indicating the proportion of recycled PET – are plotted in a bar chart, with the height of the bars representing the CO₂ emission (kg CO₂ / kg product). The data refers to PET chip production, excluding contributions to the production of monomers such as monoethylene glycol (MEG) and PTA ( English "Purified Terephthalic Acid"). The subsequent processes, starting with yarn production, are considered independent of the PET raw material with regard to CO2 emissions.

[0129] The bar on the left represents the CO2 emission of virgin PET, while the two bars on the right represent the CO2 emission of bio-based PET (the ethylene glycol monomer was obtained from maize, so that approximately 30 wt% of the raw materials come from renewable resources) and HIPS ("high-impact polystyrene"; high-impact polystyrene).

[0130] As at Fig. 1 It is evident that the lowest CO2 emissions are achieved with PET made from 100% recycled PET by weight. The CO2 balance of the recycled material only begins after it has been used, for example, as a PET bottle.

[0131] The CO2 emissions from the different raw materials used in the "Origin PET" and "Bio PET" bars are not included. This means that these values ​​essentially represent the polycondensation to PET chips.

[0132] In the case of 100% recycled PET, the value essentially comprises the shredding and remelting into PET chips.

[0133] The values ​​in between - i.e., with 10 to 90% recycled PET - are calculated proportionally from the values ​​for "Origin PET" and 100% recycled PET.

[0134] Furthermore, additional trials were conducted, each using 100% recycled PET (like E1) by weight, but with different process steps adapted in each case.

[0135] According to the comparison experiment V2, the procedure was the same as in E1, with the difference that the entire solid-phase polymerization process was omitted.

[0136] According to the comparative experiment V3, the procedure was the same as in E1, with the difference that the solid-phase polymerization was carried out without the steps of pre-crystallization and crystallization.

[0137] According to the comparison experiment V4, the procedure was the same as in E1, with the difference that the undrawn yarn was cooled directly using cooling air after the spinning process, without reheating with a buffer zone (see step c)).

[0138] According to the comparison experiment V5, the procedure was the same as in E3, with the difference that the undrawn yarn was cooled directly after the spinning process using cooling air, without reheating with a buffer zone (see step c)).

[0139] Table 2 shows the influence of the different processing methods on the physical properties of the respective yarn.

[0140] The properties were determined using the methods described above.

[0141] Furthermore, the degree of filament breakage during the yarn manufacturing process was used as an additional criterion. For each spool (9 kg, 62 km long, 1300 denier), it was stipulated that the number of filament breaks had to be less than 10 to be classified as qualified (Q). Otherwise, the sample was rated as insufficient (NQ). Table 2 E1 E2 E3 E4 E5 E6 V2 V3 V4 V5 Denier (Den) 150 0 1000 1300 1500 1500 1500 1500 1500 1500 1500 Proportion of rPET 100 % 10% 40% 60% 90% 80% 100% 100% 100% 100% IPA content 1,50 0,15 0,60 0,90 1,35 1,20 1,50 1,50 1,50 1,50 Crystallinity (%) 48,2 53,5 51,5 50,3 49,5 45,0 45,2 48,5 48,4 47,7 Number of filaments 370 180 280 320 480 480 370 370 370 370 Filament fineness (Den) 4,1 5,6 4,6 4,7 3,1 3,1 4,1 4,1 4,1 4,1 Fracture strength t (g / Den) 7,8 9,0 8,2 8,0 7,9 7,5 5,2 7,6 7,5 7,2 Elongation at break (%) 11,9 12,1 10,2 10,8 11,5 15,5 10,2 11,5 11,0 11,2 Elongation at 45 N 3,5 5,6 4,7 3,5 3,6 3,6 5,3 3,7 4,0 4,2 Elongation at 45 N (% / D) 0,00 23 0,0056 0,0036 0,0023 0,002 4 0,002 4 0,0033 0,0025 0,0027 0,0028 Heat shrink at 177 °C (%) 4,7 4,2 5,2 4,8 4,5 3,2 2,1 4,5 5,0 4,8 Rejection rate (%) 3,3 3,5 3,2 3,2 3,6 2,8 30,5 9,7 18,2 22,4 Degree of filament breakage e Q Q Q Q Q Q NQ NQ NQ NQ

[0142] The data in Table 2 show that yarns produced by the process according to steps a) to d), comprising solid-state polymerization, spinning, cooling, and drawing, exhibit properties such as tensile strength and elongation at break that are comparable to those of traditionally produced yarns. Therefore, using the yarns according to Examples E1 to E6, rubberized reinforcement carriers and vehicle tires according to the invention can be produced efficiently with a low waste rate (< 4%), particularly in a reinforcement layer, while simultaneously meeting the corresponding requirements for use due to their high-quality properties.

[0143] Compared to V2, E1, through solid-phase polymerization, offers molecular chain growth and a reduction in additives present in recycled PET, such as alternative monomers. p-Terephthalic acid, such as IPA.

[0144] Compared to V3, E1 achieves improved quality and processability of the high-viscosity chips through pre-crystallization and crystallization as part of the solid-state polymerization process, while avoiding negative effects such as cementation and agglomeration in the SSP reactor. When these negative effects occur, they lead to irregular ejection from the SSP reactor and increased variance in the intrinsic viscosity of the high-viscosity chips. Furthermore, this results in additional negative consequences, such as a heterogeneous melting point, heterogeneous melting behavior, and a heterogeneous crystallization rate of the yarn. This increases the frequency of filament and yarn breakage and significantly complicates the overall manufacturability of the yarns.

[0145] Provided that pre-crystallization and crystallization are carried out as part of the solid-state polymerization process, the homogeneity of the viscosity, melting point and crystallization rate of the high-viscosity chips can be effectively controlled.

[0146] If the SSP process is not carried out, the tensile strength of the manufactured yarns does not meet the requirements, the frequency of filament and yarn breaks is increased, and production efficiency is reduced.

[0147] The example V4 shows that if the post-heating and buffer zone are omitted after spinning, the undrawn yarn cools down too quickly and hardens and crystallizes prematurely, leading to lower production efficiency and poorer physical properties.

[0148] The example V5 shows that if pre-crystallization and crystallization are omitted in the SSP process and post-heating and buffer zone are omitted after spinning, poor homogeneity of the high-viscosity chips, a rapid crystallization rate during spinning, poorer spinnability, and a lower degree of crystallization of the finished yarn are achieved.

[0149] Therefore, pre-crystallization and crystallization should be combined with post-heating and the buffer zone as described above to slow down the crystallization rate and increase the degree of crystallization.

[0150] From the yarns of the examples listed above, E1 to E6 and V2 to V5, cords were produced by twisting two yarns together, these were woven and dipped, resulting in a dipped fabric.

[0151] During twisting, two yarns were twisted together in a direct cabling machine to form a cord made of two yarns (x1x2 cord).

[0152] The yarns have been twisted in the S direction, while the cord is twisted in the Z direction.

[0153] The following steps were taken during weaving: When arranging the yarn on the creel, the tension of each yarn spool was controlled by roller bearings and rubber belts to ensure consistent tension. During the weaving process, the yarn was guided through the reed, which was adjusted according to specifications, and woven on an air-jet loom. The cord was then woven into raw fabric of a preset width, with the weft thread being a 22.2 tex nylon core-spun yarn (core of nylon monofilament, wrapped with staple fibers of cotton). English "core spun yarn") was.

[0154] The resulting raw fabric was then further processed using a dip. A two-bath dipping process was employed. In the first bath, an epoxy compound (trade name Grilbond® < G 1701, EMS-GRILTECH) and an isocyanate compound (trade name Grilbond® < IL-6 50% F, EMS-GRILTECH) were provided, and the yarns were dipped in this solution, thus activating their surface filaments.

[0155] In a second bath, a resorcinol-formaldehyde latex (a pre-condensed resin of resorcinol and formaldehyde in an aqueous dispersion mixed with, among other things, formaldehyde and latex) was provided, and the fabric activated by the first bath was dipped into it. During the dipping process, devices and conditions known in the prior art, such as immersion solution tanks, tension zones, and ovens, were used successively.

[0156] Furthermore, hot stretching took place, with a net stretching of 0 to 1% being achieved.

[0157] The obtained cords were examined for their properties, and the results are summarized in Table 3.

[0158] The designation 1500 / 2 should be understood as 1500 denier / 2 and means that two yarns, each with a fineness of 1500 denier, have been twisted together to form a corduroy. The same applies to the designation 1000 / 2.

[0159] The number of twists per meter, English "turns per meter" (tpm) in Table 3 refers to the respective cord.

[0160] The residual strength was determined using a Goodrich fatigue test under the following conditions: 1800 rpm (revolutions per minute), duration 24 hours, 20% compression, 6.5% tension, at room temperature. Table 3 E1 E2 E3 E4 E5 E6 V2 V3 V4 V5 Cord construction 1500 / 2 1000 / 2 1300 / 2 1500 / 2 1500 / 2 1500 / 2 1000 / 2 1500 / 2 1500 / 2 1500 / 2 Proportion of rPET 100% 10% 40% 60% 90% 80% 100% 100% 100% 100% tpm 320 430 370 320 320 320 430 320 320 320 Breaking force (N) 214,4 160,7 193,5 223,2 215,9 205,5 82,5 209,4 202,0 192,8 Elongation at break (%) 16,2 14,7 16,6 16,2 15,6 16,0 9,7 15,1 13,5 13,0 Elongation at 45N (%) 2,3 4,1 3,2 2,4 2,4 2,4 5,6 2,4 2,7 2,9 Elongation at 45 N (% / D) 0,0008 0,0021 0,0012 0,000 8 0,000 8 0,000 8 0,002 8 0,000 8 0,000 9 0,001 0 Heat shrink (%) (180°C, 2 min, 0.05 g / den) 2,3 1,8 1,7 2,2 2,1 2,4 1,3 2,4 2,2 2,4 Residual strength (%) 83,9 85,5 86,0 83,3 84,8 82,5 0 77,2 65,5 55,6

[0161] As can be seen in Table 3, cords were produced using examples E1 to E6 whose properties meet the requirements for use in a rubberized reinforcement element according to the invention, particularly for vehicle tires. In contrast, comparative examples V2 to V5 exhibit inferior properties and are therefore less suitable. In particular, the greater damage to the filaments during high-speed spinning significantly impairs the fatigue resistance of the produced cords. As can be seen from example V2, the sample broke before the fatigue test was completed.

[0162] Thus, as shown in Examples E1 to E6, it has been possible to provide a rubberized reinforcing element according to the invention for elastomeric products, in particular vehicle tires, which is manufactured in a particularly resource-efficient and environmentally friendly manner and at the same time exhibits good physical properties, so that it meets the requirements, especially in the driving operation of vehicle tires. Here, the vehicle tire according to the invention has the rubberized reinforcing element at least in the carcass layer, and in particular a plurality of the rubberized reinforcing elements in a corresponding reinforcing layer that forms the carcass layer.

[0163] An exemplary composition of a rubberizing mixture of the rubberized reinforcing carrier according to the invention is shown in Table 4. Table 4 Components Unit Crowd Polyisoprene phr 50 Polybutadien phr 20 ESBR a)< phr 41,25 Carbon black N660 phr 65 Plasticizer oil / adhesive resin phr 20,5 Anti-aging agents phr 2 Resorcinol resin phr 1,63 Hexamethoxymethylmelamine b)< phr 2 Stearic acid phr 1 zinc oxide phr 3 accelerator phr 1 Sulfur with 33% oil phr 3,8 a) < oil-diluted with 27.3% aromatic-free oil b) < 65% on an inorganic carrier

Claims

1. Rubberized strength member for elastomeric products, especially vehicle tyres, where the strength member includes at least one first yarn and one second yarn, and the first yarn is a yarn of HMLS-PET comprising recycled PET, characterized in that the first yarn is twisted with the second yarn in a x2 cord, where the cord has a twist factor of 150 to 250 and a breaking force of at least 6.3 g / den (equivalent to 5.67 g / dtex) and has an elongation at 45 N of less than 0.0056% / den (equivalent to 0.00504% / dtex) and hot shrinkage of less than 3%.

2. Rubberized strength member according to Claim 1, characterized in that the first yarn of HMLS-PET comprises 10% to 100% by weight, preferably 30% to 100% by weight, more preferably 50% to 100% by weight, of recycled PET.

3. Rubberized strength member according to either of Claims 1 and 2, characterized in that the first yarn of HMLS-PET includes 0.12% to 5% by weight, especially 0.12% to 2.2% by weight, of isophthalic acid (IPA).

4. Rubberized strength member according to any of the preceding claims, characterized in that the first yarn of HMLS-PET has a crystallization level of 45% to 53.5%.

5. Rubberized strength member according to any of the preceding claims, characterized in that the first yarn of HMLS-PET has a fineness of 300 to 4000 den (equivalent to 333.333 to 4444.444 dtex), preferably 300 to 3100 den (equivalent to 333.333 to 3444.444 dtex), more preferably 300 to 2000 den (equivalent to 333.333 to 2222.222 dtex), most preferably 900 to 2000 den (equivalent to 1000 to 2222.222 dtex).

6. Rubberized strength member according to any of the preceding claims, characterized in that the first yarn of HMLS-PET has hot shrinkage of less than 8% and an elongation at 45 N of less than 0.0056% / den (equivalent to 0.00504% / dtex) in the case of filament finenesses of less than 5 den.

7. Rubberized strength member according to any of the preceding claims, characterized in that the cord has - a twist factor of 170 to 230; and / or - a breaking force of 6.3 to 10 g / den (equivalent to 5.67 to 9 g / dtex); and / or - an elongation at 45 N of 0.0005 to 0.0040% / den (equivalent to 0.00045 to 0.0036% / dtex); and / or - hot shrinkage of 1.5 to 2.5%.

8. Process for producing the rubberized strength member according to Claim 1, comprising at least the following process steps: a) providing PET chips comprising 100% by weight of recycled PET from PET bottles or other PET products and optionally providing chips of virgin PET; b) pre-crystallization, crystallization and solid-state polymerization of the PET from step a) to give high-viscosity PET chips having an intrinsic viscosity of 0.85 to 1.15 dl / g; c) drying and optionally mixing the chips of recycled PET with chips of virgin PET to obtain PET chips comprising 10% to 100% by weight of chips of recycled PET, melting and extruding the PET chips for the yarn spinning, then yarn spinning by means of a spinneret comprising a reheater having a buffer zone for the high-viscosity PET chips from step b), and stepwise cooling of the unstretched yarn, wherein the water content of the chips after drying is less than 30 ppm, the temperature of the reheater beneath the spinneret is 280°C to 350°C and the length of the buffer zone beneath the reheater during the stepwise cooling is 20 to 100 mm; d) oiling, drawing, heat-setting and winding after the stepwise cooling in step c) to obtain an HMLS-PET yarn; e) twisting; f) optionally weaving; g) modification of adhesion with a dip; h) rubberization with a rubberization mixture.

9. Vehicle tyre including at least one rubberized strength member according to any of Claims 1 to 7.

10. Vehicle tyre according to Claim 9, characterized in that it includes a multitude of rubberized strength members according to any of Claims 1 to 7 in a strength member ply.

11. Vehicle tyre according to Claim 10, characterized in that the strength member ply is at least the carcass ply and / or a belt bandage and / or a belt ply and / or a bead reinforcement.

12. Vehicle tyre according to Claim 11, characterized in that the strength member ply is at least the carcass ply, where the carcass ply is run around the bead once (one-ply construction) or twice (two-ply construction) in a turnup, where the end of the ply / plies lies between the core and the edge of the belt.