MXPA99010213A - Filling yarn and method for producing it from thermally protected polyamide 6.6 for tyre cord fabric - Google Patents

Abstract

The invention relates to a filling yarn made of a thermally protected polyamide 6.6 multifilament for tyre cord fabric with a total titer of 100-400 dtex. This filling yarn is also raw yarn, and is characterized by:a SLASE of 6 cN/tex to 12 cN/tex at 80%elongation;a maximum tensile stress strain of 150%to 300%;a strength of>14 cN/tex;a reversibility limit of 5 cN/tex to 10 cN/tex;a thermal shrinkage force of 0. 15 cN/tex to 0.8 cN/tex at 160°C;free shrinkage>1%at 160°C. The invention also relates to a method for producing a filling yarn from thermally protected polyamide 6.6 multifilament for tyre cord fabric. In this method, polyamide LOY filaments are stretched between 10 and 200%before being swirled at least 10 knots/m by a compressed gas.

Description

Weft yarn and method for manufacturing a weft yarn of a thermoprotected polyamide 66 for cover fabrics The present invention relates to a weft yarn of a thermoprotected multifilament polyamide 6.6 for cover fabrics with a total titer of 100-400 dtex, as well as to a process for manufacturing a weft yarn. Weft yarns for polyester-POY cover fabrics and processes for their manufacture are known (WO-A-96/2391). The yarns made from POY polyester filaments show a very small thermal load capacity, and no improvements with lower spinning speeds also occur. In the relaxation heater, already at 220 ° C, the strand of filament becomes brittle, losing a large part of its resistance and elongation of residual breakage. It is an object of the present invention to provide a PA 66 weft yarn for cover fabrics, which possesses high thermal stability, a defined reversibility limit, sufficient strength and slip resistance, as well as a high maximum tensile elongation. Another objective comprises providing a method for manufacturing weft yarns for cover fabrics that reveal a high maximum elongation of traction after impregnation, which guarantees the separation of the yarns from the fabric during the manufacture of the covers without occurring - • breaks in the weft threads. This objective is achieved in accordance with the present invention because the raw yarn has: - a specific LASE (SLASE) with a stretch of 80% from 6 cN / tex to 12 cN / tex, - a maximum tensile elongation of 150% to 300%, -a resistance of > 14 cN / tex, -a reversibility limit of 5 cN / tex to 10 cN / tex, -a thermal contraction force at 160 ° C from 0.15 cN / tex to 0.8 cN / tex, -a free shrink at 160 ° C > 1%. A yarn of these characteristics has the advantage that, due to its marked flow behavior in the fabric, it allows in the manufacture of the covers, a homogeneous distribution of the lattice of the fabric. It is also achieved with this thread, to provide a single-component weft yarn, which does not cause any harmful and dangerous dust formation when weaving it, as is customary when using natural fibers. On the other hand, it must withstand a high thermal load during the impregnation, show only a shrinkage in the width and make possible during the manufacture of the cover a very homogeneous expansion of the mesh fabric and be used as a mind for cover fabrics based on nylon, polyester and aramid. For a stretch of 80%, preferably 90 to 150%, a loading of 6 cN / tex to 12 cN / tex, preferably 6 to 10 cN / tex, has been shown to be convenient. Stretching forces greater than 12 cN / tex have the disadvantage of a non-homogeneous distribution of the web structure during the expansion of the radial cover in the tire making machine. Stretching forces below 6 cN / tex lead, both in the case of loads on large surfaces and on spot loads, for example in the storage of the bales of fabric, to irreversible stretches in the weft threads and consequently to a Insufficient stability as regards the parallelism of the fabric structure, resulting from there defective tire tracks, when not unusable.

A maximum tensile stretch of < 300%, preferably 180 to 200%, has been shown to be adequate. Maximum tensile stretches of more than 300% produce in the manufacture of cover fabrics with the usual loads, a very high deformation by stretching, a maximum tensile stretch of less than 150% implies, on the contrary, a reserve of insufficient elongation , which results in a low deformation of the weft, which may cause breakage of the threads in the fabric. The roof treads resulting in both cases are inhomogeneous and thus also the covers manufactured with them. It is desirable that the weft yarn has a strength of at least 14 cN / tex, so that the peaks of load generated in the different stages of the process, can not produce breaks in the threads of the weft. A reversibility limit of 5 to 10 cN / tex is particularly advantageous. A reversibility limit of less than 5 cN / tex means that the dimensional stability in the plot record can not be guaranteed, nor the stability in the width of the fabric until its conformation in the cover. With a reversibility limit greater than 10 cN / tex, the resultant vulcanization force does not reach to uniformly expand the individual yarns of the fabric. A thermal contraction force of 0.5 to 0.8 cN / tex has the advantage that the width of the fabric does not contract practically during the impregnation of the same, thus guaranteeing also here a homogeneous distribution of the threads of the fabric. fabric framing, especially in fabrics with lace edges of weft threads; With a thermal contraction force greater than 0.8 cN / tex, the yarns are shortened, in spite of the forces exerted widthwise on the weft yarns by clamping rollers during impregnation, so that it is not ensured the required homogeneity. This leads, especially at the edges of the fabric, to an undesired concentration of the weft threads. With thermal contraction forces of less than 0.15 cN / tex, an elongation of the yarns can already occur during thermal stressing (impregnation) of the tread fabric, whereby the parallelism of the yarn can no longer be guaranteed. framework of the threads. It is absolutely necessary, according to the present invention, that all the properties of the raw weft yarn be at the same time within the intended limits. It is advisable that the weft yarn after a warm air treatment for 5 minutes at 235 ° C free of filar tensile stresses present at the same time all the following properties: - a maximum tensile stretch greater than 80%, - a SLASE for an elongation of 80% from 6 cN / tex to 14 cN / tex, -a reversibility limit of 5 to 10 cN / tex, -no non-controllable longitudinal deformation during the treatment at temperature. Maximum tensile elongations above 80%, preferably above 110% are convenient. These maximum tensile elongations greater than 110% have been shown to be particularly suitable for the weft threads of the impregnated fabric, since the accidental tearing of individual weft threads during the expansion of the tread caused by the wear is prevented. own process, especially during the expansion of the raw material for the cover on the drum shaping the cover. The isolated breaks of the weft yarns cause unequal spacings between the yarns of the fabric in the tread and with it unsatisfactory rolling properties of the cover. The weft yarn also exhibits, after impregnation, an SLASE for 80% of less than 14 cN / tex, preferably less than 12 cN / tex. An SLASE for 80% 16 of more than 12 cN / tex increases the risk of uneven distribution of the truss threads by expanding the tread in order to obtain the final circumference of the roof in the manufacture of a roof. The impregnated yarn is treated - in a known manner - by immersion in RFL and then heat set at temperatures of up to 245 ° C, preferably between 210 and 235 ° C and for 45-200 s. Also after the hot air treatment the reversibility limit is less than 10 cN / tex, preferably below 6 cN / tex. This has the advantage that the expansion forces originating in the vulcanization are sufficient to deform the weft yarns in such a way as to ensure a homogeneous distribution of the tread yarns. A polyamide 6.6 LOY can be used as starting material for the raw yarn according to the process of the present invention. Instead of the pure polyamide 6.6, it is also possible to use a copolyamide with at least 85% by weight. Among the copolyamides are, for example, PA 6, PA6.10 and Aramid. The PA-6.6-LOY has been generally stretched at spinning speeds of less than 1800 m / min. The starting yarn is thermally protected with a copper additive with at least 30 ppm Cu, preferably 60-80 ppm Cu. As a particularly appropriate method has been demonstrated, in the case of the manufacture in a single stage, starting from a LOY, which consists of stretching filaments of thermally protected polyamide 6.6-LOY with at least 30 ppm of Cu between 10 and 200% , preferably between 40 and 150%, and especially between 40 and 125%, by rotating them in the form of a whirlwind next by means of a pressurized gas until obtaining at least 10 knots / m, preferably at least 15 knots / m. This procedure has the advantage, that a compact fiber composite with a relatively rough and slip resistant surface is obtained. LOY yarn stretch can be done cold or hot, with or without stretching pin. In a variant of the procedure, the LOY polyamide filaments are stretched in a first step between 10 and 200%, and then they are rotated in a vortex form at the same time or later in a second step by means of a pressurized gas until obtaining by at least 10 knots / m, relaxing them by 0-30% at a temperature between 150 and 235 ° C, preferably between 200 and 225 ° C. This has the advantage that lower contraction values and lower reference strengths (LASE) are achieved. In another variant of the process, the weft yarn is additionally fixed or post-stretched by 0 to 10% at a temperature between 150 and 235 ° C, preferably between 180 and 225 ° C. This has the advantage that an additional reduction of the shrinkage values is achieved, the shrinkage properties being adapted accordingly to the respective process conditions in the manufacture of covers. The weft yarn is used as raw weft yarn and is especially suitable for cover fabrics. Measurement methods: Realization as a general rule after 24 hours of storage of bobbins in normal climate 20 ± 2 ° C and 65 ± 2% relative humidity.

Title: Determination of the fineness of fibers and threads according to the winding procedure (DIN 53 830 Part 1). Tensile test: Single tensile test on fibers and yarns in crimped state (DIN 53 834 Part 1) -length fastened 100 mm -test speed 1000 mm / min Module: Slope of the almost linear rise in the initial KD field. Reversibility limit: Equivalent to yield point = > load, in which the transition from the area of reversible to irreversible elongation occurs. SL-ASE: Resistance resulting in cN / tex for certain elongations (2%, 5%, 10% and 80%). Free thermal contraction: (residual or permanent) Variation of permanent length in% after a hot air treatment free of tensions of 15 minutes at 160 ° C, with a subsequent cooling of 15 minutes and conditioning in normal climate. Effective shrinkage: Variation of length in% under the effect of temperature after 15 minutes of treatment at 160 ° C and with a pre-tension force of 0.1 cN / tex. Effective contraction force: Variation in force in cN / tex resulting from the hot air thermal action at 160 ° C for 15 minutes of a test piece held firmly at both ends with a tension of 0.1 cN / tex. The measurement is carried out in all cases under the action of temperature. The present invention will be more fully described by means of examples. Example 1: A polyamide 6.6 with a Cu content of 60 ppm was spun in a known manner to make a LOY, dtex 519, 34 strands, with the properties listed in the following table. This starting material was then cold-drawn at a development speed of 450 m / min (development rollers in the stretching zone) by 125%, with a stretching pin, winding it with a titre of 224 dtex. The detailed properties of the weft yarn are shown in Table 1 mentioned. Example 2: A polyamide 6.6 with a Cu content of 30 ppm was spun in a known manner to make a LOY, dtex 550, 17 strands, with the properties listed in the following table. This starting material was then stretched at 160 ° C at a development speed of 60 m / min (development rollers in the stretching zone) by 100%, without stretching pin, winding it with a titer of 290 dtex. The detailed properties of the weft yarn are shown in Table 1 mentioned. Example 3: A polyamide 6.6 with a Cu content of 60 ppm was spun in a known manner to make a LOY, dtex 252, 34 strands, with the properties listed in the following table. This starting material was then cold stretched at a development speed of 120 m / min (development rollers in the stretching zone) by 40%, with a stretching pin, winding it with a 190 dtex titer. The detailed properties of the weft yarn are shown in Table 1 mentioned. Example 4: A polyamide 6.6 with a Cu content of 60 ppm was spun in a known manner to make a LOY, dtex 252, 34 strands, with the properties listed in the following table (analogous to example 3). This starting material was then stretched cold at a development speed of 143 m / min (development rollers in the stretching zone) by 50%, with a stretching pin. In a further continuous process step, a 25% relaxation was carried out by means of a 25 cm long contact heater at a temperature of 220 ° C. The yarn title achieved by means of this treatment is 215 dtex. The detailed properties of the weft yarn are shown in Table 2 mentioned. Example 5: A polyamide 6.6 with a Cu content of 60 ppm was spun in a known manner to make a LOY, dtex 273, 34 strands, with the properties listed in the following table. This starting material was then cold stretched at a development speed of 390 m / min (development rollers in the stretch zone) by 11%, without stretching peg, winding it with a 243 dtex rating. The detailed properties of the weft yarn are shown in Table 2 mentioned. Example 6: A polyamide 6.6 with a Cu content of 60 ppm was spun in a known manner to make a LOY, dtex 252, 34 strands, with the properties listed in the following table (analogous to example 3). Then, in a first stage, this starting material (LOY) was stretched cold at a development speed of 135 m / min (development rollers in the stretch zone) by 50%, with a stretching pin. In a second continuous process step, a 25% relaxation was carried out by means of a 65 cm long convection heater at a temperature of 220 ° C. For a third stage of continuous process the material was postfixed on a contact heater 25 cm long at 210 ° C without post-deformation. After these treatments you get a thread count that is 214 dtex. The detailed properties of the weft thread can be seen in table 2 mentioned. Example 7 (Relaxation Series): A polyamide 6.6 with a Cu content of 60 ppm was spun in a known manner to make a LOY, dtex 519, 34 strands, with the properties listed in the following table (analogous to Example 1) . Then, in a first stage, this starting material (LOY) was stretched cold at a development speed of 80 m / min (development rollers in the stretch zone) in 100%, with a stretching pin. In a second step of the continuous process, three variants were manufactured with a relaxation of 5%, 15% and 25% by means of a 65 cm convection heater at a temperature of 225 ° C. The resulting filarial titres after these treatments are 283 - 349 dtex. The detailed properties of the weft yarns can be seen in table 3 mentioned. Example 8 (complementary example 7): The variant with 25% relaxation described in Example 6 was further post-fixed in a third process step in a contact heater 25 cm long at 210 ° C without post-deformation . The filarial title obtained after this treatment is 343 dtex. The detailed properties of the weft yarn are shown in Table 3.

Examples for the manufacture of weft yarns for cover fabrics Table 1 Table 2 ro Table 3?

Claims (5)

1. CLAIMS Having thus specially described and determined the nature of the present invention and the way it has to be put into practice, it is claimed to claim as property and exclusive right: 1. Weft thread of a polyamide 6.6 thermoprotected multifilament for fabrics of covers with a total title of 100-400 dtex, characterized in that the raw fiber presents at the same time: - a specific resistance for 80% of stretch (SLASE) of 6 cN / tex to 12 cN / tex, - an elongation of Maximum traction of 150% to 300%, -a resistance of > 14 cN / tex, -a reversibility limit of 5 cN / tex to 10 cN / tex, -a thermal contraction force at 160 ° C from 0.15 cN / tex to 0.8 cN / tex,
2. -a free shrink at 160 ° C > 1%. A weft yarn according to claim 1, characterized in that the weft yarn after a treatment with hot air free of filar tensile stresses for 5 minutes at 235 ° C presents at the same time: - a maximum tensile elongation greater than 80%, -an 80% SLASE of 6 cN / tex a14 cN / tex, -a reversibility limit of less than 10 cN / tex, -no length increase during the temperature treatment.
3. 3. Process for the manufacture of a weft yarn of a polyamide 6.6 thermoprotected multifilament for cover fabrics with a total title of 100-400 dtex, characterized in that the LOY polyamide filaments are stretched between 10 and 200%, and they spin in a vortex shape by means of a pressurized gas until at least 10 knots / m are obtained.
4. 4. Process according to claim 3, characterized in that the LOY polyamide filaments are stretched between 10 and 200% in a first stage of the process, by rotating them in the form of a whirlwind, then in a second process step by means of a pressurized gas until getting at least 10 knots / m, being relaxed between 0 and 30% at a temperature between 150 and 235 ° C. Method according to claim 4, characterized in that the LOY polyamide filaments are additionally post-stretched between 0 and 10% at 180-230 ° C.