DE102022201492A1 - Rubberized reinforcement layer and agricultural tires - Google Patents

Abstract

The invention relates to a rubberized reinforcement layer for objects made of elastomeric material, preferably for agricultural tires, the reinforcement layer having a multiplicity of parallel and spaced-apart reinforcement members, each reinforcement member being a cord which consists of two twisted multifilament yarns with a twist of 200 to 300 tpm ( twists per meter), the cord having a twist factor α (α=twist [t/m] (cord fineness [tex]/1000)1/2) of 135 to 220, with at least one of the multifilament yarns containing polyester filaments and wherein the multifilament yarns have a yarn linear density (fineness) of 1600 to 2500 dtex and an initial twist of 200 to 300 tpm. The invention also relates to an agricultural tire which has at least one such rubberized reinforcement layer. In the reinforcement layer, the cords have a density of 60-90 epdm (cords per decimeter/ends per decimeter) and a cord spacing of 0.45 to 0.9 mm arranged.

Description

The invention relates to a rubberized reinforcement layer for objects made of elastomeric material, preferably for agricultural tires, the reinforcement layer having a multiplicity of parallel and spaced-apart reinforcement members, each reinforcement member being a cord which consists of two twisted multifilament yarns with a twist of 200 to 300 tpm (Twists per meter) is finally twisted, the cord having a twist factor α (α=twist [t/m]. (Cord fineness [tex]/1000) ^1/2 ) of 135 to 220, with at least one of the multifilament yarns being polyester filaments contains and wherein the multifilament yarns have a yarn linear density (fineness) of 1600 to 2500 dtex and an initial twist of 200 to 300 tpm. The invention also relates to an agricultural tire which has at least one such rubberized reinforcement layer.

Reinforcement plies for articles of elastomeric material such as industrial rubber products and pneumatic vehicle tires are of paramount importance and are generally known to those skilled in the art. The reinforcement layers have a large number of reinforcing, thread-like elements, the so-called reinforcements. These are completely embedded in elastomeric material. The reinforcements of these reinforcement layers are, for example, in the form of woven fabrics or calendered, endlessly wound reinforcements.

The rubberized reinforcement plies of appropriate size and configuration are assembled with other components to form an engineered rubber product or a pneumatic vehicle tire. The rubberized reinforcement layers reinforce the product in question.

A wide variety of materials can be used as reinforcements for the reinforcement layers of rubber products. Are known z. B. reinforcements made of steel or textile reinforcements. Textile reinforcements are used in the rubber industry, e.g. B. Reinforcements made of polyamide, rayon or polyester are used.

In the context of this application, “multifilament yarn” is to be understood as meaning a multifilament yarn which is twisted and thus has the construction x1 as reinforcement and which has already gone through the process of hot drawing including impregnation.

In the context of this application, a cord consists of two multifilament yarns twisted together.

In pneumatic vehicle tires, cords are used as reinforcements, for example in the bead area, as carcass material, for belt layers and in belt bandages, with rayon and polyamides as well as different types of polyester being used as materials for the textile reinforcements.

wobei CT die Anzahl der Windungen pro Zoll (2,45 cm) Cordlänge und CD die Summe der Denier-Feinheiten der Garne des Cordes vor jeglicher Verdrehung ist.From the WO 9814336 A1 are heavy-duty tires, e.g. B. tractor tires are known that contain several belt layers with cords. The cords have a count of 2000 to 16000 denier, 2 to 9 yarns, a twist of 0.8 to 2.8 TPcm and a twist multiplier (twist multiplier) of 3 to 5 for high tenacity, high modulus and high dimensional stability with sufficient fatigue resistance . The twist multiplier TM is defined as follows: $$\text{TM}=0.0137\text{CT}\times {\left(\text{CD}\right)}^{1/2}$$

where CT is the number of turns per inch (2.45 cm) of cord length and CD is the sum of the deniers of the cord's yarns before any twist.

The invention is based on the object of providing a rubberized reinforcement layer which leads to good reinforcement with reduced susceptibility to cracking in the rubber products produced with these reinforcement layers.

This object is achieved according to the invention in that, in a reinforcement layer of the type mentioned at the outset, the cords are arranged at a density of 60-90 epdm (cords per decimeter/ends per decimeter) and with a cord spacing of 0.45 to 0.9 mm.

It has surprisingly turned out that the crack behavior within the rubber products can be positively influenced by these cord spacings. This results in a longer product hold ability. The cords are not as dense, thereby reducing the stress on the rubber material between the cords.

The multifilament yarns for the cords of the reinforcing layer are made by spinning a raw yarn without any twist, which is then twisted in a twisting machine.

• - der Verdrehung von zwei Multifilamentgarne zum gewünschten Cord
• - des Herstellens einer Cordlage, enthaltend den gewünschten Festigkeitsträger
• - der Gummi-Haftungsaktivierung des Cordes, beispielsweise mittels eines RFL-Dips

durchführt.The multifilament yarn is converted into a fabric suitable for calendering by following steps known to those skilled in the art:

• - the twisting of two multifilament yarns to form the desired cord
• - The production of a cord layer containing the desired reinforcement
• - the rubber adhesion activation of the cord, for example by means of an RFL dip

performs.

Filaments of different materials can be present within the yarns of a reinforcement cord, with at least one of the multifilament yarns containing polyester filaments. For example, other yarns can consist of filaments of different materials. If yarns made of different materials are present within the reinforcement cord, it is a so-called hybrid cord.

Aliphatic and aromatic polyamides such as polyamide 6, aramid, polyetherketone, polyketone, viscose, natural fibers or glass fibers can be considered as further materials for the filaments and yarns. The properties of the reinforcing cord can be adjusted in a targeted manner by selecting a suitable material.

The polyester filaments are filaments made from polymers with ester functions in their main chain, such as e.g. B. polyethylene terephthalate (PET), polybutylene terephthalate (PBT) or polyethylene naphthalate (PEN).

According to a preferred development of the invention, the multifilament yarns consist only of polyester filaments. In this way, there are advantages in the processing method and in the costs.

The multifilament yarns particularly preferably consist of PET filaments. PET is available on the market in large quantities and is characterized by a positive range of properties when using the rubberized reinforcement layer in rubber products such as tires. Yarns of this type can also be easily spun and initially twisted and finally twisted to form a cord.

In order to obtain a modulus of elasticity that is advantageous for subsequent use in the rubber product, the multifilament yarns have a yarn titre of 2100 to 2300 dtex and an initial twist of 220 to 260 tpm and the cord is twisted at the end with 220 to 260 tpm.

According to an advantageous development of the invention, the cord has a twist factor α of 150 to 200. Thereby, the fatigue resistance of the reinforcing cords can be improved with good strength. The twist factor α is calculated using the following formula: α=twist [t/m] · (fineness [tex]/1000) ^1/2 . The twist factor is a measure of the final twist per meter of cord, based on the gauge of the cord. The specified ranges for the twist factor represent an advantageous compromise between fatigue resistance and strength.

According to a preferred development of the invention, the reinforcement is a cord made of two twisted multifilament yarns made of PET filaments and the cords are arranged in the reinforcement layer with a density of 70 to 85 epdm and a cord spacing of 0.5 to 0.6 mm. In this way a particularly balanced ratio of crack resistance and reinforcement. The products have a long shelf life.

In order to ensure reliable adhesion of textile reinforcements to the rubber, it is advisable to treat the cords in the reinforcement layer with an adhesive impregnation, e.g. B. with an RFL dip in the 1- or 2-bath process.

The reinforcement layer according to the invention can be used in a wide variety of elastomeric products, such as belts, conveyor belts, hoses or air springs. The reinforcement layer according to the invention is preferably used in vehicle tires, in particular for off-road and/or heavy-duty use. It can be used as a belt ply or as a carcass ply. It can be used in both radial and cross-ply tires.

It is particularly advantageous if an agricultural tire is used as the reinforcement layer. Agricultural tires are characterized by high durability.

Preferably, the rubberized reinforcing ply is included in the belt of the agricultural tire. The belts of agricultural tires usually have six to eight belt layers in order to have sufficient durability and robustness. At least one of the belt layers is formed by a reinforcement layer according to the invention. However, several or all belt layers can also be formed by the reinforcement layer according to the invention.

In order to reduce the susceptibility to tearing in the belt of an agricultural tire and to reduce the production time and production costs, it has proven to be advantageous if the belt consists of four to six belt plies of the rubberized reinforcement ply. A lower cord thread density with a higher modulus of the cord enables this smaller number of belt layers while at the same time the belt has a high tear resistance. In addition, the rolling resistance can be reduced by the reduced number of layers.

As an alternative or in addition to using the rubberized reinforcement layer in the belt of agricultural tires, the rubberized reinforcement layer can also be contained in the carcass of agricultural tires.

All advantageous configurations, which are reflected in the patent claims, among other things, are included in the invention. In particular, the invention also includes configurations that result from a combination of different features, for example components of the rubber mixture, different gradations in the preference of these features, so that a combination of a first feature designated as “preferred” or described in the context of an advantageous embodiment Feature with another than z. B. "particularly preferred" designated feature is covered by the invention.

The invention is explained in more detail below using exemplary embodiments, but without being restricted to these.

Agricultural tires of size 710/70 R 42 were produced with a belt of eight rubberized reinforcement layers 1 (see Table 1) as comparison tires and with a belt of six rubberized reinforcement layers 2 according to the invention (see Table 1). Table 1 Characteristic Unit Position 1 (comparison) Layer 2 according to the invention material PET PET delicacy and construction dtex 1440x2 2200x2 first twist tpm 370 240 final twist tpm 370 240 twist factor α - 199 159 cord density epdm 105 78 cord spacing mm 0.32 0.55

The tire having six reinforcing plies 2 according to the present invention exhibited higher resistance to belt cracking as compared with the tire having eight reinforcing plies 1 . In addition, the tire with the six reinforcement layers 2 according to the invention could be produced faster and more cost-effectively.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• WO 9814336 A1 [0008]

Claims (10)

Rubberised reinforcement layer for articles made of elastomeric material, preferably for agricultural tires, the reinforcement layer having a multiplicity of parallel and spaced-apart reinforcement members, each reinforcement member being a cord which consists of two twisted multifilament yarns with a twist of 200 to 300 tpm (twists per meter ), end-twisted, the cord having a twist factor α (α=twist [t/m] (cord fineness [tex]/1000) ^1/2 ) of 135 to 220, with at least one of the multifilament yarns containing polyester filaments and with the multifilament yarns have a yarn linear density (fineness) of 1600 to 2500 dtex and an initial twist of 200 to 300 tpm, characterized in that the cords have a density of 60 to 90 epdm (cords per decimeter) and a cord spacing of 0.45 to 0.9 mm are arranged. Rubberized reinforcement layer after claim 1 , characterized in that the multifilament yarns consist of polyester filaments. Rubberized reinforcement layer after claim 2 , characterized in that the multifilament yarns consist of PET filaments. Rubberised reinforcement layer according to at least one of the preceding claims, characterized in that the multifilament yarns have a yarn titre of 2100 to 2300 dtex and an initial twist of 220 to 260 tpm and the cord is twisted at end with 220 to 260 tpm. Rubberized reinforcement layer according to at least one of the preceding claims, characterized in that the cord has a twist factor α of 150 to 200. Rubberized reinforcement layer according to at least one of the preceding claims, characterized in that the reinforcement is a cord made of two twisted multifilament yarns made of PET filaments and that the cords have a density of 70 to 85 epdm and a cord spacing of 0.5 to 0. 6 mm are arranged in the reinforcement layer. Agricultural tire having at least one rubberized reinforcement layer according to at least one of the preceding claims. agricultural tires claim 7 , characterized in that the rubberized reinforcement layer is included in the belt of the agricultural tire. agricultural tires claim 8 , characterized in that the belt consists of 4 to 6 belt layers of the rubberized reinforcement layer. agricultural tires claim 7 , characterized in that the rubberized reinforcing layer is contained in the carcass of the agricultural tire.