EP1743964A1 - Cord - Google Patents

Abstract

The cord has a core containing high module fibers, which are embedded in a matrix and predominantly coated with fibers forming a mantel. The fibers forming the mantel is a multifilament yarn wounded at the core. The matrix of the core is a thermoplastic e.g. thermoplastic polyurethane, polyester, polyphenylene sulphide, polyethylene and polyamide, having a melting point and/or melting point range between 180 and 260 degree centigrade. Independent claims are also included for the following: (1) a v-belt containing a cord (2) a toothed belt containing a cord.

Description

The invention relates to a cord consisting of a core and a sheath.

Such a cord is for example in EP 1 411 159 described in which the core is made of glass fibers and the sheath of aramid yarns. This cord serves to reinforce elastomeric materials such as tires or belts.

There is still the desire to develop such cords, which are at least comparable or better in their properties with the known cords. In particular, such cords should ensure the longest possible service life of composite materials reinforced with such cords. When using such cords in belts, it is also important that the cords are resistant to oil and / or hydrolysis resistant.

The object of the present invention is to provide further cords which are suitable for reinforcing elastomeric materials. In particular, the cords should ensure a long service life of the elastomeric material reinforced with such cords. In addition, cords are to be provided with a good resistance to hydrolysis. Also, a cord is to be provided, which is inexpensive to produce.

The object of the invention is achieved by a cord, consisting of a core and a sheath, wherein the core contains embedded in a matrix high modulus fibers, which is at least predominantly coated with the sheath-forming fibers.

Here, the core serves as a strength carrier, which is characterized in particular by high dimensional stability.

Such a cord can be produced for example in such a way that the high modulus fibers are impregnated with the matrix material. Thereafter, the core is wrapped, for example, with staple fibers, after which then the staple fibers form the sheath.

At least one multifilament yarn is preferred as the fibers forming the sheath, which is wound around the core. The wrapping is preferably carried out such that after wrapping the core covered as well as possible, that is as possible no longer visible. If several multifilament yarns are used to produce the jacket, they can be wound in the same direction and / or in opposite directions around the core. Also, multiple multifilament yarns may be braided into a sheath.

It has turned out to be particularly favorable when the matrix of the core of the cord according to the invention is a thermoplastic.

In addition to the usual impregnation method for introducing the matrix into the high-modulus fibers, in this case thermoplastic fibers can be mixed with the high-modulus fibers, wherein this mixture is heated in a later step so that the thermoplastic fibers melt and become the matrix in which the high-modulus fibers are embedded. Here, the high modulus fibers can be present as continuous fibers, for example as multifilament yarn, and the thermoplastic fibers with the high modulus fibers For example, be well mixed by air known per se swirling. However, finite fibers, for example staple fibers or fibers which have been produced by stretch breaking, can also be used for the high-modulus fibers. It is advisable to use thermoplastic fibers, which are also staple fibers or stretch-broken fibers. In stretch breaking of fibers, the broken fibers have different lengths, and the average length and length distribution of the fibers can be influenced to some extent. For the high modulus fibers in the core of the cord invention, an average length of 70 to 170 mm, preferably from 110 to 130 mm and in particular about 120 mm and a length distribution of 40 to 230 cm has been well proven. Such fibers can then be mixed in a manner known per se and used without twisting or in the form of a yarn as a core around which the mutifilament yarn forming the sheath is wound. In this case, the mixed, consisting of high-modulus fibers and thermoplastic fibers yarn can be heated either before the sheath with the multifilament yarn so that melt the thermoplastic fibers and embedding the Hochmodulfasern as a matrix.

It is particularly favorable first to wrap the mixture of high-modulus fibers and thermoplastic fibers with at least one multifilament yarn. Since an adhesion promoter, preferably an RFL (resorcinol-formaldehyde-latex) adhesion promoter, which is crosslinked under the action of temperature, is usually applied to the cords before embedding in the elastomeric material, the temperature treatment required for crosslinking the adhesion promoter can also be used can be used to melt the thermoplastic fibers and convert them into matrix material.

In this case, it has proven particularly useful if the matrix of the core of the cord according to the invention is a thermoplastic which has a melting point or melting point range between 150 and 420 ° C., preferably between 180 and 260 ° C. A melting point or melting range for the thermoplastic between 200 and 230 ° C has proven to be particularly useful here. As thermoplastic material for the matrix of the core, virtually all materials which can be spinned into fibers by melt spinning are suitable, in particular thermoplastic polyurethanes (TPU), polyesters (PET), polyphenylene sulfides (PPS), polyethylenes (PE) or polyamides (PA). In the case of polyamides, in particular PA 4, PA 4.6, PA 6, PA 6.6, PA 6.10, PA 10 or PA 12 have proven to be particularly favorable.

The cord according to the invention is characterized in particular by the fact that the core contains 15 to 50% by volume, preferably 25 to 40% by volume, based on the core without sheath, of matrix. It has been found that it is not absolutely necessary on the one hand that the high modulus fibers are completely embedded in matrix material, but on the other hand it is advantageous if the core has as little excess matrix material as possible when embedding the cord in the elastomeric material Material applied heat would embed a considerable proportion of filaments of the sheath-forming multifilament yarn. In the same way, it has turned out to be an advantage if the matrix material is distributed as evenly as possible in the core.

Furthermore, the cord according to the invention is characterized in that the high modulus fibers in the core have a modulus of 200 to 550 GPa, preferably 200 to 350 GPa, more preferably 200 to 250 GPa. Carbon fibers are best suited for this purpose.

Also, it has been found to be advantageous if the multifilament yarn or the multifilament yarns have a lower modulus than the modulus of the high modulus fibers of the core. In particular, multifilament yarns with a modulus of from 70 to 150 GPa, in particular from 70 to 120 GPA, have proven to be very useful. As a particularly suitable multifilament yarn for the sheath of the Kernes of the cord according to the invention, a multifilament yarn of aramid has proven itself.

The cord according to the invention is ideally suited for the production of fiber-reinforced elastomeric materials.

In this respect, the subject of vorfiegenden invention is a V-belt as well as a toothed belt, which contains a cord according to the invention.

The invention will be explained in more detail with reference to the following example.

• Garn 1: Kohlenstofffasern der Firma Toho Tenax Europe GmbH mit der Bezeichnung Tenax STS 5411, dessen Einzelfilamente einen Titer von 0,67 dtex und eine Faserdichte von 1,76 g/cm³ aufweisen.
• Garn 2: Thermoplastische Fasern aus Polyamid 6 (PA6) Multifilamentgarn der Firma Rhodia, dessen Einzelfilamente einen Titer von 6,9 dtex und eine Faserdichte von 1,14 g/cm³ aufweisen. Dieses Multifilamentgarn weist einen Schmelzbereich von 215 bis 220 °C auf.
• Garn 3: Twaron 1.100 dtex f 1000 von Teijin Twaron b.v.

The following yarns were used to produce a cord according to the invention:

• Yarn 1: Carbon fibers from Toho Tenax Europe GmbH with the name Tenax STS 5411, whose individual filaments have a titer of 0.67 dtex and a fiber density of 1.76 g / cm ³ .
• Yarn 2: Thermoplastic fibers of polyamide 6 (PA6) multifilament yarn from Rhodia, whose individual filaments have a linear density of 6.9 dtex and a fiber density of 1.14 g / cm ³ . This multifilament yarn has a melting range of 215 to 220 ° C.
• Yarn 3: Twaron 1.100 dtex f 1000 from Teijin Twaron bv

First, 12,000 filaments of Yarn 1 and 300 filaments of Yarn 2 were stretch-broken and then thoroughly mixed to form a strand of 10,100 dtex containing filaments having an average length of 120 mm, the lengths of the filaments varying between 40 and 230 mm, had. The core component with a titre of 10,100 dtex was produced from this strand by means of a worsted spinning process. So this core component contained 80 % By weight of carbon fibers (Yarn 1) and 20% by weight of polyamide 6 fibers (Yarn 2). This core component was wound with 2 yarns 3 in opposite directions, each with 250 turns per meter (1 yarn with 250 turns per meter in the Z direction and a yarn with 250 turns per meter in the S direction), resulting in an untreated cord, which in the core component contained the filaments of yarns 1 and 2. This cord was provided with an RFL dip in two stages in the following manner. In the first step, the cord surface (essentially the filaments of the yarn 3) was epoxidized in a surface treatment. In the second step, the cord was dipped in aqueous RFL and cured at 235 ° C with the filaments of yarn 2 melting and becoming the matrix for the filaments of yarn 1.

The following properties were found: untreated corduroy dipped corduroy thickness mm 1.47 ± 0.08 BS N 680 ± 44 1293 ± 49 EAB % 1.56 ± 0.08 1.6 ± 0.07 CHAMFER 0.3 N 70.1 ± 1.4 167.9 ± 5.2 CHAMFER 0.5 N 124.5 ± 3.3 312 ± 9 CHAMFER 1 N 350 ± 9 731 ± 20 CM mN / tex 45100 ± 600

Where:

BS:

Breaking strength

EAB:

Elongation at break

CHAMFER:

Force at specific elongation at 0.3, 0.5 and 1.0% elongation

CM

Module (Cord Modulus)

The obtained dipped cord was embedded in hydrogenated nitrile rubber. Further, two commercial cords Glass A and Glass B, which contained glass filaments in the core, were dipped in the same manner and embedded in hydrogenated nitrile rubber.

Cord A is made by NGF Europe Ltd. under the designation "Type EC9, 34, 3/11 80S, black dipped", while Cord B is sold and sold by Sovoutri as a reinforcing cord.

On all three cords the properties relevant to the bond strength between cord and rubber were measured. They are summarized in the table below. Cord according to the invention Glass A (dipped) Glass B (dipped) Unit X ± ci x ± ci x ± ci BS N 1314 ± 53 968 ± 34 1044 ± 37 EAB % 1.55 ± 0.031 3.53 ± 0.11 2.63 ± 0.1 CHAMFER 0.3 N 174 ± 9 81.1 ± 1.8 126.1 ± 1.9 CHAMFER 0.5 N 323 ± 13 129.9 ± 2.9 198.1 ± 2.5 CHAMFER 1 N 760 ± 22 262.5 ± 4.8 394.3 ± 3.8 SPAF N / 2cm 231 ± 31 263 ± 11 147 ± 53

Here, SPAF (strap peel adhesion force) means the force necessary to pull the cord out of the composite, a 2 cm wide strip. This force is determined according to ASTM D 4393 - 00.

These values clearly show that the cord according to the invention has significantly higher values with regard to the breaking strength and the force at the measured strains than conventional cords which have glass fibers in their core. Also, the cord according to the invention is characterized by lower elongation at break. With regard to the adhesion in rubber, the cord according to the invention has comparable properties to those of today's cords. In this respect, the cord according to the invention can be regarded as a significant improvement.

Claims (19)

Cord consisting of a core and a sheath, wherein the core contains embedded in a matrix high modulus fibers, which is at least predominantly coated with the sheath-forming fibers. Cord according to claim 1, characterized in that the fibers forming the sheath are at least one multifilament yarn which is wound around the core. Cord according to claim 1 or 2, characterized in that the matrix of the core is a thermoplastic. Cord according to claim 3, characterized in that the matrix of the core is a thermoplastic having a melting point or melting point range between 100 and 420 ° C, in particular between 180 and 260 ° C. Cord according to claim 4, characterized in that the matrix of the core is a thermoplastic having a melting point or melting range between 200 and 230 ° C. Cord according to claim 3 to 5, characterized in that the matrix in the core is a polyamide, in particular PA 4, PA 4.6, PA 6, PA 6.6, PA 6.10, PA 10 or PA 12. Cord according to one of claims 1 to 6, characterized in that the core contains 15 to 50 vol.%, Based on the core without shell, of matrix. Cord according to one or more of claims 1 to 7, characterized in that the high modulus fibers in the core have a modulus of 200 to 550 GPa. Cord according to claim 8, characterized in that the high modulus fibers in the core have a modulus of 200 to 350 GPa, in particular of 200 to 250 GPa. Cord according to one or more of Claims 1 to 9, characterized in that the multifilament yarn of the sheath has a modulus of 70 to 150 GPa, preferably of 70 to 120 GPa. Cord according to one or more of claims 1 to 10, characterized in that the high modulus fibers in the core are carbon fibers. Cord according to one or more of claims 1 to 11, characterized in that the high modulus fibers have finite length in the core. Cord according to claim 12, characterized in that the high modulus fibers in the core are break-broken high modulus fibers. Cord according to claim 12 or 13, characterized in that the high modulus fibers in the core have an average length of 70 to 170 mm. Cord according to claim 12 to 14, characterized in that the high modulus fibers in the core have different lengths in the range of 40 to 230 mm. Cord according to one or more of Claims 1 to 15, characterized in that the multifilament yarn of the sheath is an aramid yarn. Use of a cord according to one or more of claims 1 to 16 for the production of fiber-reinforced elastomeric materials. V-belt comprising at least one cord according to one or more of claims 1 to 16. Timing belt comprising at least one cord according to one or more of claims 1 to 16.