Strengthening material and strengthening layer for elastomeric products, especially for a vehicle tire, and vehicle tire

Description

[0001] The invention relates to a reinforcement member and a reinforcement layer for elastomeric products, in particular for a vehicle tire.

[0002] Furthermore, the invention relates to a vehicle tire which has at least one reinforcement member according to the invention or at least one reinforcement layer according to the invention.

[0003] Reinforcements for elastomeric products, especially for reinforcement layers of vehicle tires, such as carcass plies, bead reinforcements, belt plies, and belt bandages, are known to those skilled in the art in a wide variety of designs and materials. The reinforcements are embedded in a rubber compound during production so that they can be used as a rubberized reinforcement layer in the elastomeric product.

[0004] To date, elastomer products, particularly carcass plies, bead reinforcements, belts or belt bandages of vehicle tires, have primarily (directly) been made from textile reinforcements based on fossil raw materials such as petroleum, such as PET (polyethylene terephthalate), aramid and nylon or hybrid cords made from their yarns.

[0005] On the other hand, it is known to use non-petroleum-based textile reinforcements made of viscose, such as rayon or lyocell.

[0006] The disadvantage of natural fibers, i.e. non-petroleum-based materials as material for textile reinforcements, is that they do not have a continuous fiber structure and their fiber quality varies greatly.

[0007] Furthermore, the lack of shrinkage makes it difficult to use rayon as a strength member in belt bandages. Another disadvantage of rayon is that it is sensitive to moisture, and its breaking strength is reduced by moisture absorption. Furthermore, rayon is expensive to purchase.

[0008] The trend is toward developing and using environmentally friendly, resource-saving elastomer products, such as vehicle tires, that do not use primary fossil raw materials, without compromising the durability of the resulting products. For example, DE 102010017107 A1 discloses hybrid cords for carcass plies that consist of at least one yarn made from recycled PET.

[0009] JP 2004 263334 A discloses a polyester condensation using a catalyst comprising a titanium compound and a phosphorus compound.

[0010] JP 2000 096370 A discloses a polyethylene terephthalate fiber produced by condensation of A) isophthalic acid and B) butylene glycol and / or propylene glycol.

[0011] The present invention is based on the object of providing a reinforcement member and a reinforcement layer—comprising at least one reinforcement member—for elastomeric products, in particular for a vehicle tire, which consists of environmentally friendly and resource-saving materials and can simultaneously be produced sustainably. Furthermore, the reinforcement cord should exhibit consistent product quality.

[0012] The task is solved by the reinforcement comprising fibers made of regenerated polyethylene terephthalate (PET).

[0013] Because the reinforcement comprises fibers made from regenerated polyethylene terephthalate (PET), it and the reinforcement layer according to the invention comprising at least one reinforcement according to the invention are produced more sustainably, and further accumulation of waste is avoided through reuse. At the same time, the reinforcement with the fibers made from regenerated polyethylene terephthalate has improved properties, particularly with regard to strength and tear properties, compared to a reinforcement comprising fibers made from recycled polyethylene terephthalate, since recycling merely involves remelting, and polymer chains are degraded by the heat input. In contrast, the regenerated polyethylene terephthalate (PET) is obtained in particular by a) depolymerizing PET waste to monomers and b) subsequent polycondensation of the monomers. Comparison of regenerated PET to recycled PET

[0014] The weight average molecular weight (M w ) of recycled PET is therefore lower than that of regenerated PET or the weight average molecular weight (M w ) of regenerated PET is higher than that of recycled PET.

[0015] The intrinsic viscosity (limiting viscosity) of the materials can also be used as an indicator of molecular weight. The higher this value, the longer the polymer chains and thus the higher the weight-average molecular weight (M w ).

[0016] PET for bottles has an intrinsic viscosity in the range of 0.70 to 0.85 dL / g, while PET for technical fibers has an intrinsic viscosity of greater than 0.82 and up to 0.98 dL / g. In the case of technical yarns, post-condensation is carried out immediately before the spinning process, further increasing the viscosity. In both bottle and fiber production, extrusion leads to a reduction in molecular weight (degradation of the polymer chains), although the higher initial value of the polymer chains in the fibers must be taken into account.

[0017] By using regenerated PET, the intrinsic viscosity is back to the level of original PET, unlike recycled bottle PET, which is not re-polycondensed.

[0018] In the production of the reinforcements according to the invention, regenerated PET is used, which has an intrinsic viscosity of 0.86 to 0.98 dL / g.

[0019] The intrinsic viscosity is measured using ASTM D4603-18 (Standard Test Method for Determining Inherent Viscosity of Poly(Ethylene Terephthalate) (PET) by Glass Capillary Viscometer). Comparison of regenerated PET to original PET

[0020] The direct starting material for regenerated PET is not petroleum, but rather bottles or other PET articles, which are not simply remelted. Due to the a) depolymerization of PET waste into monomers and b) subsequent polycondensation of the monomers obtained from a), regenerated PET has a different chemical composition than original, non-regenerated PET directly derived from petroleum. In particular, it has a higher proportion of isophthalic acid (m-phthalic acid) of 0.5 to 5 wt.% (percent by weight), preferably 0.5 to 4 wt.%, particularly preferably 0.5 to 3 wt.%, and again preferably 1 to 2 wt.%.

[0021] Thus, the fibers made of regenerated polyethylene terephthalate (PET) of the reinforcement according to the invention have a proportion of isophthalic acid (m-phthalic acid) of 0.5 to 5 wt.% (percent by weight), preferably 0.5 to 4 wt.%, particularly preferably 0.5 to 3 wt.%, again preferably 1 to 2 wt.%.

[0022] Original PET, on the other hand, has a content of 0 wt.% isophthalic acid (m-phthalic acid), which is commonly used for technical yarns, such as reinforcements in tires.

[0023] The proportion of isophthalic acid (m-phthalic acid) is determined using methods known to those skilled in the art, such as 13< C-NMR ("nuclear magnetic resonance").

[0024] According to advantageous embodiments, the reinforcement according to the invention comprises 10 to 100 wt.% of fibers made of regenerated polyethylene terephthalate (PET), wherein in the case of less than 100 wt.%, the remaining wt.% are then fibers made of other materials.

[0025] The fibers made from other materials can be any fibers for reinforcements known to the person skilled in the art.

[0026] The fibers made of additional material are preferably selected from the group consisting of polyamide (PA), aramid, polyether ketone (PEK), polyketone (POK), polyethylene naphthalate (PEN), polyethylene furanoate (PEF), rayon, viscose, natural fibers, glass fibers and fibers made of non-regenerated PET.

[0027] The polyamide is preferably selected from the group consisting of polyamide 6 (PA 6), polyamide 66 (PA 66), polyamide 12 (PA 12), polyamide 11 (PA 11), polyamide 1313 (PA 1313), polyamide 4 (PA 4), polyamide 7 (PA 7), polyamide 8 (PA 8), polyamide 9 (PA 9), polyamide 46 (PA 46), polyamide 610 (PA 610), polyamide 612 (PA 612), polyamide 69 (PA 69) and polyamide 66 / 6 (PA 66 / 6).

[0028] The use of PA 6 and / or PA 66 is preferred, the use of PA 66 (nylon) is particularly preferred.

[0029] In the context of the present invention, reinforcements are linear structures comprising fibers. The smallest linear structure in the reinforcement thus comprises fibers, which are not present in films.

[0030] The linear structures can be present individually, twisted together or within a flat structure, in particular a fabric, in the reinforcement layer according to the invention.

[0031] Films are not included in the term “fabric” in the context of the present invention.

[0032] According to a preferred embodiment of the invention, the fibers are twisted into yarns. The reinforcement according to the invention is thus a yarn according to this preferred embodiment. In the context of the present invention, a yarn, based on DIN 60900, is a linear structure consisting of individual fibers. Individual fibers are also referred to as filaments.

[0033] According to a further preferred embodiment of the invention, the reinforcement member is a cord. Cords, in the context of the present invention, are linear structures in which one yarn is twisted or two or more yarns are twisted together.

[0034] In the embodiment in which the strength member is a cord, the cord thus comprises at least one yarn comprising fibers made of regenerated polyethylene terephthalate (PET).

[0035] According to a particularly advantageous embodiment of the invention, the reinforcement according to the invention comprises 100 wt.% fibers made of regenerated polyethylene terephthalate (PET). This optimizes the reinforcement according to the invention with regard to sustainability and the elimination of original petroleum-based raw materials, while simultaneously providing good strength and good tensile properties.

[0036] According to further advantageous embodiments of the invention, the reinforcement according to the invention comprises 10 to 99 wt.% of fibers made of regenerated polyethylene terephthalate (PET), preferably 20 to 80 wt.%.

[0037] This means that the strength member is designed to be sustainable on the one hand, and on the other hand, by using one or more of the other materials mentioned above, further properties can be adjusted and optimized to suit the respective application.

[0038] In the reinforcement layer according to the invention, comprising at least one reinforcement according to the invention, the reinforcements are embedded in particular in a rubber mixture.

[0039] To ensure reliable adhesion of the reinforcements according to the invention to the rubber, it is advisable to provide the reinforcements according to the invention with an adhesive impregnation, e.g., with an RFL dip in a one- or two-bath process. Furthermore, other conventional pretreatment processes known to those skilled in the art can be carried out, such as, in particular, hot stretching of the cords.

[0040] The invention also relates to a vehicle tire which has at least one reinforcement member according to the invention and / or at least one reinforcement layer according to the invention.

[0041] The vehicle tire preferably comprises the reinforcement member according to the invention and / or the reinforcement layer according to the invention at least in the carcass ply and / or in at least one belt ply and / or as a bead reinforcement and / or in the belt bandage. Particularly preferably, the vehicle tire comprises the reinforcement member according to the invention and / or the reinforcement layer according to the invention at least in the carcass ply.

[0042] The vehicle tire according to the invention is produced sustainably while maintaining the same properties, particularly with regard to durability, driving stability and rolling resistance.

[0043] The invention also relates to a method for producing a strength member reinforced elastomeric article, in particular a vehicle tire, wherein the elastomeric article comprises strength members made of PET.

[0044] The process according to the invention is characterized in that regenerated PET is used.

[0045] Thus, the invention also relates to the use of regenerated PET for the production of elastomeric articles, in particular vehicle tires.

[0046] In the process or use according to the invention, a) PET waste is depolymerized to monomers and b) the monomers obtained from a) are subsequently polycondensed. The resulting regenerated PET is used in the form of fibers as a reinforcement, or is first spun into yarns, or the yarns are twisted into cords. Furthermore, the fibers and / or yarns and / or cords can be woven into a flat fabric.

[0047] The aforementioned forms of regenerated PET are then integrated into the green tire, for example during the tire building process, in at least one reinforcement layer using methods and devices known to those skilled in the art.

Claims

1. Strength member for elastomeric products, in particular for a vehicle tyre, characterized in that it comprises fibres of regenerated polyethylene terephthalate (PET), wherein the fibres of regenerated polyethylene terephthalate (PET) comprise a proportion of isophthalic acid (m-phthalic acid) of 0.5% to 5% by weight, and wherein the production of the strength members employs regenerated PET having an intrinsic viscosity of 0.86 to 0.98 dL / g, wherein the intrinsic viscosity is measured by means of ASTM D4603-18.

2. Strength member according to Claim 1, characterized in that the regenerated polyethylene terephthalate (PET) is obtained by a) depolymerization of PET wastes to afford monomers and b) subsequent polycondensation of the monomers.

3. Strength member according to any of the preceding claims, characterized in that it comprises 10% to 100% by weight of fibres of regenerated polyethylene terephthalate (PET).

4. Strength member according to any of Claims 1 to 3, characterized in that it is a yarn.

5. Strength member according to any of Claims 1 to 3, characterized in that it is a cord.

6. Strength member ply comprising at least one strength member according to any of the preceding claims.

7. Vehicle tyre, characterized in that it comprises at least one strength member according to any of Claims 1 to 5 and / or at least one strength member ply according to Claim 6.

8. Vehicle tyre according to Claim 7, characterized in that it comprises at least one strength member according to any of Claims 1 to 5 and / or at least one strength member ply according to Claim 6 at least in the carcass ply and / or in at least one belt ply and / or as a bead reinforcer and / or belt bandage.

9. Process for producing a strength member-reinforced elastomeric article, in particular vehicle tyre, wherein the elastomeric article comprises strength members according to any of Claims 1 to 5.