JPH0327650B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Technical Field> The present invention relates to weft yarns for tire cord blind fabrics.

<Prior art> In general, tire reinforcing blind fabrics using extensible threads as wefts stretch as the space between the cords increases when formed into a circular shape in the tire forming process, so the warp cord spacing increases. It has the effect of maintaining uniformity and making the tire molding even.

As such a stretchable yarn, a core yarn has been proposed in which an undrawn yarn such as polyester is used as a core yarn and the core yarn is covered with a spun. When this core yarn is used for the weft of tire cord blind fabric, it effectively holds the warp cord in the proper position,
It has the effect of stabilizing the texture of the fabric during handling and weaving.

However, the production of such extensible core yarns requires special core yarn spinning equipment and has the disadvantage of high production costs.

In addition, it has been proposed to use stretchable bulky yarn, which is obtained by applying air jet bulking to undrawn polyamide yarn to form a large number of filament loops on the surface of the yarn, as the weft of tire cord blind fabrics (Japanese Patent Application Laid-Open No. 58-2011). -104238, JP-A-60-110943). Although 6-nylon and 6,6-nylon are used here, 6-nylon has poor heat resistance and cannot be used as the weft of polyester tire cord blind fabrics that require heat treatment at high temperatures. In addition, 6,6-nylon has a higher production cost than polyester and cannot be used industrially.

<Object of the invention> The object of the invention is to provide a weft for tire cord blind fabrics made of polyester, which has high extensibility, stably has a large number of loops and slacks, and is easy to handle during weaving. This is what I am trying to do.

<Structure of the Invention> The present invention is a fluid-jet processed yarn that is composed of a core yarn and a sheath yarn made of polyester and has loops and slack, and (a) the entanglement coefficient K between the core yarn and the sheath yarn is 0.65 to 0.65. 1.3 [However, K = (Elongation at break of raw yarn for core yarn) / (Elongation at break of Taslan yarn)] (b) Elongation at the primary yield point is 6% or less (c) Elongation of the core yarn at the primary yield point The pull-out resistance value A is
0.57 g/de or more [However, A = (load at primary yield point - 18.2 g) / (core yarn fineness de)] (d) Breaking elongation is 100% or more (e) Dry heat shrinkage rate is 3% or less This relates to a weft for tire cord blind fabrics that satisfies all of the following.

The polyester referred to in the present invention is a polyester whose main constituent unit is ethylene terephthalate, and even if it is a polyester in which a part of the terephthalic acid component is replaced with another dicarboxylic acid component,
It may also be a polyester in which part of the ethylene glycol component is replaced with another diol component. Its degree of polymerization is usually in the range of 100-110.

The Taslan yarn, which is the weft of the present invention, must have an entanglement coefficient K of the core yarn and sheath yarn constituting it in a range of 0.65 to 1.3. However, K=(Elongation at break of core yarn)/(Elongation at break of Taslan yarn). If this K does not reach 0.65, it is difficult (i.e.,
Taslan yarn has a low degree of entanglement) and has a high breaking elongation, but the large loop form of Taslan yarn makes it difficult to handle in subsequent processes, and the function of holding the warp of the woven bamboo blind in the appropriate position is poor. Not fully demonstrated. Furthermore, if K is greater than 1.3, the stiffness becomes strong and the size of the loop becomes small, making it impossible to obtain the necessary elongation at break. In this way, the entanglement coefficient K defines the relationship between the breaking elongation of the core yarn and the breaking elongation of the taslan yarn, which is influenced by the degree of twisting of the core yarn and sheath yarn.

Furthermore, in the present invention, the elongation of the Taslan yarn at the primary yield point must be 6% or less. When this elongation is greater than 6%, the weavability and handling properties of the blind will deteriorate.

Further, it is necessary that the pull-out resistance value A of the core yarn at the primary yield point of the Taslan yarn is 0.57 g/de or more. However, A = (Load (stress) at primary yield point -
18.2g)/(core yarn fineness de). When A does not reach 0.57, the weaving properties and handling properties of the bamboo blinds are poor.

In the Taslan yarn of the present invention, a yarn having the entanglement coefficient K shown in (a) is created by fluid jet processing, and then heat-treated to obtain a yarn having the physical properties of (b) to (e). At this time, the sheath threads entwined around the core thread shrink. Due to this contraction effect, the load (stress) at the primary yield point of the Taslan yarn itself increases due to the frictional force between the single fibers that make up the core yarn, and its value mainly depends on the fineness de of the core yarn. It is calculated as the pull-out resistance value A of the core yarn when corrected by the fineness de of the yarn.

Furthermore, the Taslan yarn must have an elongation at break of 100% or more and a dry heat shrinkage rate of 3% or less when heat treated in a free state at 150° C. for 30 minutes. When the elongation at break and the dry heat shrinkage rate are out of this range, the workability during tire fabrication using blinds and the uniformity of the resulting tire will deteriorate.

The fineness ratio of the core yarn to the sheath yarn in the weft of the present invention can vary over a wide range, but is preferably in the range of 1:1 to 6:1. In addition, the total fineness of this weft is 130 ~
A range of 270 de is preferred.

The polyester yarn used to manufacture the above Taslan yarn must have a breaking elongation of 120% or more, such as
It can be obtained through a method of high speed spinning at a spinning speed of 2500 to 6000 m/min, or a method of drawing an undrawn yarn spun at a spinning speed of 800 to 1500 m/min at a low ratio using a conventional method.

The yarn obtained by the above method has a dry heat shrinkage rate (150℃
×30 minutes measurement condition) is large and dimensional stability is poor. In order to improve this and further increase the elongation at break, the core yarn is heated under normal pressure boiling water or
Heat treatment is performed by passing through hot air at 120℃ or higher to reduce the dry heat shrinkage rate to 10% or less and increase the elongation at break by at least 10%. An appropriate overfeed rate at this time is 8 to 40%. If it exceeds 40%, the Young's modulus decreases, making it difficult to handle in subsequent steps, which is not preferable. Overfeed rate is 8%
If the dry heat temperature is less than 120℃, the specified dry heat shrinkage rate cannot be obtained and the elongation at break is 10%.
It will not increase more than that.

The yarn that has undergone the above process is used as the core yarn, and the polyester yarn that has not been heat treated and has a breaking elongation of 120% or more is used as the sheath yarn.
(Fluid injection processing of feed). At this time, if the degree of entanglement becomes too large, a high elongation and bulky textured yarn having a breaking elongation of 100% or more cannot be obtained. Therefore, conditions are set so that the overfeed rate of the core yarn is 5% or less and the entanglement coefficient K of the core yarn and sheath yarn is 0.65 to 1.3. In addition, the overfeed rate of the sheath yarn needs to be 50% or more to stabilize the weave of the fabric, and the difference in the overfeed rate of the sheath yarn and core yarn affects the elongation at break.
In order to make it more than 100% and to stabilize the weave of the fabric, it is better to make it more than 48%.

The yarn that has undergone the above process has large loops and is difficult to handle in subsequent processes, so it is subjected to dry heat treatment. At this time, the sheath yarn, which has a high dry heat shrinkage rate, mainly shrinks and the loop becomes smaller, which greatly improves the ease of handling in the subsequent process.
At this time, the appropriate overfeed rate is -10 to 30%, and the dry heat treatment temperature is 100 to 230°C. When the overfeed rate is -20% or less, the elongation at break decreases,
When the processing temperature is below 100°C, the effect of reducing the loop size is small, and when the overfeed rate is higher than 30% or the processing temperature is higher than 230°C, the entanglement between filaments becomes too good, resulting in high elongation and bulky processed yarn. It is difficult for the elongation at break to exceed 100%.

These conditions are appropriately adjusted depending on the strength and elongation of the yarn used, the primary yield point, the number of filaments, the single yarn de, and the configuration of its core effect. Further, if the dry heat shrinkage rate of the wound yarn is still high and the drawing resistance value A is low, there is also a method of heat-treating the wound yarn as it is or after being rewound. In this process, the loops and slack of the high elongation bulky yarn are restrained by the winding layer.
The shrinkage of the slack yarn is relatively small, and the yarn as a whole has a low dry heat shrinkage rate and a high drawing resistance value A. Heat treatment temperature is 80 to 140℃ with moist heat, temporary heat
110-230°C is suitable. Moist heat below 80℃ or dry heat
If the temperature is less than 110℃, there is little effect; with moist heat, 140℃
Higher temperatures or dry heat temperatures higher than 230°C are not appropriate because the elongation at break decreases.

If the breaking elongation of the weft yarn of the present invention is less than 100%, the desired uniform tire cannot be obtained due to insufficient elongation of the weft yarn during tire formation. In addition, if the dry heat shrinkage rate of the weft becomes too large, the dimensional stability of the fabric against heat will deteriorate, making it difficult to obtain a tire as designed. Therefore, the dry heat shrinkage rate should be 3% or less. It is.

<Examples> The present invention will be explained in detail below using examples.
In the following examples, the apparatus shown in FIG. 1 was used.

FIG. 1 shows an example of an apparatus suitable for manufacturing the weft yarn of the present invention, in which 1 is a core yarn package, 2 is a sheath yarn package, 3 is a core yarn supply port roller, and 4 is a sheath yarn package. 5 is a heater, 5 is a supply roller for core yarn after heat treatment, 6 is a supply roller for sheath yarn, 7 is an air jet nozzle, 8 is a take-up roller (also serves as a supply roller to the heater at the same time), 9 is a heater, 10 is a The take-up roller 11 is a winding machine.

Example 1 Melt-spun as a core yarn at a winding speed of 4000 m/min, elongation at break 122%, strength at break 332 gr, fineness 165 de, 24
Using filament polyethylene terephthalate undrawn yarn, length 1.00 m, temperature 163°C heater fed yarn speed 149 m/min, overfeed rate 20%
It was passed through and heat treated. The elongation at break after heat treatment is
164%, an increase of 24%.

This heat-treated yarn is used as a core yarn, and the winding speed is
Air jet bulking processing (fluid jet processing) was performed using a polyethylene terephthalate undrawn yarn with a breaking elongation of 118%, a breaking strength of 88 gr, a fineness of 45 DE, and 12 filaments, which was melt-spun at 3800 m/min. The processing conditions are: core yarn overfeed rate 1%, sheath yarn overfeed rate 100%, fluid air pressure 4.0Kg/cm ² G, feeding speed core yarn 124.2m/min, sheath yarn 246m/min, feed yarn after processing. The speed was 123 m/min, and the core and sheath yarns were not soaked with water before the air jet nozzle in order to weaken the entanglement between the core and sheath yarns. As a method of weakening entanglement, the fluid air pressure may be lowered, or the processing yarn speed may be increased.

The above air jet bulky yarn was used at a yarn speed of 123.
After heat treatment by passing through a heater at a temperature of 160° C. at an overfeed rate of 0%, the yarn was wound at a yarn speed of 123 m/min. The elongation at break of the obtained fluid jet processed yarn was 151%, and the drawing resistance value A [A=(load at primary yield point - 18.2 gr)/fineness of elongation] was 0.65 g/de. Furthermore, the above thread was set under moist heat at 105°C for 30 minutes.

The obtained yarn has a fineness of 300 de and a core:sheath fineness ratio of 2.22:
1. Breaking elongation is 149% and pull-out resistance value A is 0.87 g/de,
The dry heat shrinkage rate was 2%, the entanglement coefficient K = 0.82, and the elongation at primary yield point was 3.8%. This thread is used as the weft thread, and the warp thread is polyethylene terephthalate tire cord.
1000de x 2 pieces are used, and the density is 49.4 pieces/5cm.
A fabric for the carcass of a radial tire was woven.

A resorcinol formaldehyde solution with a composition that bonds polyester with gum was applied to this fabric and heated to 150°C.
for 4 minutes, and then heat treated at 240°C for 2 minutes.
The strength after heat treatment of the weft is 421g, and the elongation at break is 117%.
It was hot.

165 using this blind fabric for tire cord
-SR-B size radial tires were molded.
When a green tire is molded, the weft yarns follow the increasing spacing of the warp yarns during the process of expanding the molded carcass, and the warp yarns are arranged uniformly. In this case, the tire uniformity level (radial force variation) level is 8.5Kg,
No unevenness was observed in the sidewall portion, and very good results were obtained.

Example 2 In place of the yarn used as the core yarn in Example 1, an undrawn polyethylene terephthalate yarn with a breaking elongation of 122.0%, a breaking strength of 252 gr, a fineness of 125 de, and 36 filaments was melt-spun at a winding speed of 3900 m/min. The other steps were carried out under the same conditions as in Example 1.

The obtained yarn has a fineness of 2600 de, and a core:sheath fineness ratio of 1.68:
1. Breaking elongation is 156% and pull-out resistance value A is 0.72 g/de,
The dry heat shrinkage rate was 2.1%, the entanglement coefficient K = 0.78, and the elongation at primary yield point was 5.0%. Furthermore, a fabric for a radial tire was manufactured using the above-mentioned yarn in place of the yarn used as the weft in Example 1, and the other steps were the same as in Example 1. The elongation at break of the fabric after heat treatment at 240°C was 115%.

Comparative Example 1 In the yarn processing of Example 1, the core yarn was soaked with water before the taslan processing, and the other conditions were the same. The obtained yarn had a fineness of 303 de and a breaking elongation of 97%, and this processed yarn was used as a weft, and a fabric for a carcass of a radial tire was woven in the same process as in Example 1 except for using this processed yarn as a weft. Since this weft yarn had insufficient elongation at break, a uniform tire could not be obtained.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of an apparatus suitable for manufacturing the weft yarn of the present invention. In the figure, 1 is a core yarn package, 2 is a sheath yarn package, 3 is a core yarn supply roller, 4 is a heater, and 5 is a core yarn package.
6 is a supply roller for the core yarn after heat treatment, 6 is a supply roller for sheath yarn, 7 is an air jet, 8 is a take-off roller (also serves as a supply roller to the heater at the same time), 9 is a heater, 10 is a take-off roller, 11 is a winding roller. It is a tori machine.

Claims (1)

[Scope of Claims] 1. A tire cord blind fabric that is a fluid-jet processed yarn that is composed of a core yarn and a sheath yarn made of polyester, has loops and slack, and satisfies the following conditions (a) to (e). Weft for use. (a) The entanglement coefficient K between the core yarn and sheath yarn is 0.65 to 1.3 [However, K = (Elongation at break of the raw yarn for core yarn) / (Elongation at break)] (b) Elongation at the primary yield point is 6% or less (c) The pull-out resistance value A of the core yarn at the primary yield point is
0.57g/de or more [However, A = (load at primary yield point - 18.2g) / (core yarn fineness de)] (d) Breaking elongation is 100% or more (e) Dry heat shrinkage rate is 3% or less 2. The weft yarn for tire cord blind fabrics according to claim 1, wherein the fineness ratio of the core yarn to the sheath yarn is 1:1 to 6:1.