JP2622674B2 - Industrial polyester yarns and cords made therefrom - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to substantially polyester multifilament yarns of the type intended for industrial use and having a strength of at least 500 mN / tex and cords made therefrom. Extruding a stream of polymer through a number of spinning orifices, cooling the spun filament bundle, optionally drawing the filaments, and finally collecting them;
With a spinning speed of 00 m / min, the relative viscosity of the polymer stream in each of the spinning orifices in the core zone is higher than in the sheath zone surrounding the core zone.

[0002]

Processes of the type described above are known. In practice, the industrial yarns referred to herein are used on a large scale for various purposes such as reinforcement of elastics, including pneumatic tires and conveyor belts for vehicles, transmission belts, ropes, sewing threads, and the like. Multifilament yarns always have a large number, e.g.
000 filaments. Although each of these filaments has high strength, each of them has low elongation at break because of their small thickness or low individual linear density. High total linear density eg decitex 30
Because of 0 to 2,500, the multifilament bundle or multifilament yarn has a sufficiently high breaking strength.
Thus, the practical use of multifilament yarns for the industrial applications described above is limited to those forms in which sufficiently high coherence is provided to the yarn, in particular by twisting or entanglement. Also, generally two or more twisted yarns are further joined together to form a cord or skein.

[0003] Common to all of the above applications is that the filaments contained therein are fairly strongly bent. As is normal in the case of bicomponent filaments subjected to bending loads, the outermost "fibers" in the sheath (outer) zone of the filament are subjected to the maximum bending force,
The filaments in the core (center) zone are subjected to relatively much lower bending forces. The difference between the loads applied to the filament core and the sheath is more important in practice when dynamic or strongly fluctuating bending loads often occur instead of static bending loads, for example in the case of reinforced cords for automotive tires and transmission belts. become.

The physical properties measured over the cross section of each filament can be different, for example even at moderate spinning speeds of about 1,500 m / min, but especially at high spinning speeds, in the case of multifilament yarns. Because, as a result of the relatively fast cooling of the filaments outside the filaments, the orientation of the molecules outside each filament is greater than in their nuclei.
Over the cross section of each filament, the birefringence in the sheath zone is greater than in the core zone. Then, across the length of each filament, the birefringence gradually decreases to its lowest value in the core of the filament. actually,
Filaments may therefore be underloaded in their cores and overloaded in their sheaths. This can be further accentuated when the filament is subjected to bending loads. Thus, the practically favorable properties of the yarn are not fully utilized. As is generally known,
This in effect results in damage to the cord during the twisting process, limiting the performance of the cord, resulting in damage during rope manufacturing and limiting the cord's resistance to fluctuating loads.
“Mallory Tube Fatigu”
e Test). These disadvantages of multifilament yarns for industrial use have not yet been completely overcome, and the situation has room for improvement. Also, for industrial polyester yarns, for several years, conventional spinning speeds from 500-900 m / min to 1600-2,000 m / min.
It tends to increase by minutes or more, resulting in a more or less pre-oriented yarn. The spinning and drawing processes are then combined into an integrated spin drawing process. In the process of spinning polyester yarns for textile applications such as clothing, 1,60
Conversion to higher spinning speeds from 0 to 5,000 m / min has already been implemented on a large scale. With regard to yarns for textile applications, in particular the total linear density of the filament yarns is relatively low, for example decitex 50-150,
Also the relative viscosity of the resulting yarn is low, for example η _rel
= 1.580, the use of a high spinning speed does not cause many major problems. Furthermore, due to the lower total linear density of the yarns, the conversion to higher spinning speeds has to be more or less converted in the production of polyester yarns for textile applications in view of higher production per spinning unit for economic reasons. .

[0005] It is known that in melt spun yarns, molecular orientation must occur in order to obtain a yarn suitable for a particular application.

At a low spinning speed of, for example, 700 m / min, the orientation is effected mainly by drawing the yarn.
Fiber yarns obtained at low spinning speeds can generally be drawn at low ratios, such as 3-4, while having higher relative viscosities (η _{rel for} polyethylene terephthalate).
= 1.880) must be drawn in a ratio of 5 to 6 in order to obtain the physical properties actually desired, such as strength, 5% LASE value or elongation at break. The higher the spinning speed, the higher the degree of molecular orientation of the resulting yarn. To obtain the desired physical properties, the yarn obtained at a high spinning speed can be drawn at a much lower ratio, for example 2 or 3. For a detailed discussion of the effect of spinning speed on the physical properties of polyethylene terephthalate yarn, see M. Heuvel and R.A. Fissman
(Huisman), “High speed fiber spinning. Science and Eng.
gineering Aspects), Andrezeiabiki (Andrze)
j ziabicki) and Hiromichi Kawai (ed.)
1985, Wheely & Sons, New York,
Pages 295-331.

The production of light-textile yarns pre-oriented during spinning, used for garments and subjected to a weaving process, at spinning speeds of up to 6000 m / min has been carried out on an industrial scale for quite a long time. Given what has been done,
The conversion to spinning speeds of up to 6000 m / min in the case of heavier industrial yarns of the type used for reinforcing vehicle tires is in principle evident. However, when these spinning speeds are used in industrial yarns, the finished yarn, which can be post-drawn if desired in a particularly desired ratio, may have some disadvantages in the physical properties of the yarn made at conventional speeds and in some respects. Exhibits quite different physical properties. For example,
16 of finished stretched polyester industrial yarn
Shrinkage, measured in hot air at 0 ° C., decreases with increasing spinning speed to 6000 m / min. But this happens to be a special advantage. Because, cords made from these yarns and generally dipped to promote adhesion to elastic materials have relatively low shrinkage. In the case of cords from industrial yarns made at high speeds, it is particularly important that the lowest possible shrinkage be obtained with the same high modulus. A high modulus / shrinkage ratio (also called high dimensional stability) is crucial for the application of reinforced cords in vehicle tires and plays an important role in the tire manufacturing process and on the quality and behavior of the tires on the road. . The most suitable high speed spun or spun drawn polyester tire yarns in view of these last mentioned properties are of the HMLS type (high modulus, low shrinkage). However, industrial polyester filament yarns such as 1600-6000
Known processes of spin drawing or high speed spinning at m / min include:
It has the disadvantage that the breaking strength of the yarn and of the dipped cord falls significantly below that of the yarn obtained at low spinning speeds and that of the cord made therefrom. Since the practical use of these industrial yarns is largely based on their high strength, the phenomenon of reduced breaking strength, and also reduced strength of drawn yarns and cords made therefrom, is presently not known for polyester industrial yarns. It forms a considerable disadvantage to the practical use of high spinning speeds in the production of yarn.

[0008]

SUMMARY OF THE INVENTION The present invention provides a method of the type described above for the production of polyester multifilament yarns for industrial use. The method no longer shows the disadvantages mentioned above, such as undesired changes in molecular orientation over each cross section of the filament and consequent loss of strength. Also, the preferred high modulus and low hot air shrinkage and thus high modulus / shrinkage ratio are retained. According to the present invention, a method of the type described above is, first of all,
The difference in relative viscosity (measured in the spun product) between the core zone and the sheath zone in each spun orifice is 0.1
00 and 0.003 or more, more preferably 0.080 to 0.003, more preferably about 0.03.
40 to 0.003 or 0.040 to 0.010. Surprisingly, it has been found that with an increase in the spinning speed, a distinct decrease in the loss of strength occurs. In addition, higher spinning speeds are associated with reduced differences in molecular orientation between the core and the sheath in each of the filaments. According to the invention, the spinning speed is in the range from 1600 to 6000 m / min, preferably about 4000 m / min. As used herein, the term spinning speed is to be understood as the peripheral speed of the first driven yarn advance roll located downstream of the spinning device. However, if the yarn advance roll driven between the winding unit and the spinneret is not used in spinning, the winding speed is taken as the spinning speed. The process for the production of yarns according to the invention is particularly advantageous if the polyester used is between 1.700 and 2.400, preferably about 1.900.
Of polyethylene terephthalate having a relative viscosity of (as measured in the spun product). Furthermore, the method is characterized in that the polyester materials used in the core zone and the sheath zone consist of substantially the same structural units. The term yarn formed substantially from polyester should be understood to refer to a yarn comprising more than 85% by weight of ethylene terephthalate units herein.

In a preferred embodiment according to the invention, the core zone and the sheath zone in the polymer stream at each spinning orifice are concentric at a specific radial distance and the core zone extends radially outward from the center in the polymer stream. ,
The sheath zone is characterized by extending radially inward from the outer periphery of the polymer stream.

A simple embodiment of the method according to the invention is characterized in that, at each orifice, the relative viscosity of the molten polymer decreases in one or more steps from the center of the polymer stream to its periphery.

An advantageous embodiment in which a stream of molten polymer of one particular relative viscosity is used is one in which the polymer stream is divided into two or more substreams, which are, for example, exposed to heating and / or residence times. It is characterized in accordance with the invention that it is subjected to different treatments which lead to a difference in the relative viscosities between the partial streams. If a stream of molten polymer of the same particular relative viscosity is used, the process according to the invention also advantageously divides the polymer stream into two or more sub-streams, wherein at least one sub-stream contains some additive For example, they are provided with polyglycols, which are characterized by a relative viscosity difference between one partial stream and the other polymer stream. Under certain circumstances, the method according to the invention also provides that if the difference in relative viscosity in the polymer stream in each of the spinning orifices is substantially the same, but different, for polymers fed to the spinning apparatus from separate extruders, respectively. If characterized by the merging of two or more polymer streams of different relative viscosities, it can be realized in a simple manner.

The process according to the invention can be realized in a particularly practical manner by causing the above difference in relative viscosity in a heated spinning device. According to the present invention, the method comprises:
The residence time and / or temperature of a portion of the polymer stream that forms a core zone having a relatively high relative viscosity of the polymer flowing through the spinning device may be different from that of the polymer stream that forms a sheath zone having a lower relative viscosity. It is advantageously carried out differently from the residence time and / or the temperature of the other parts. Here also, an apparatus for performing the method according to the invention is disclosed. With the spinning device shown in FIG. 2, the above method can be realized in a very simple manner.

[0013] A relatively high relative viscosity portion of the polymer stream is used to form a filament core using a spinning apparatus that is at least partially composed of a type for spinning multifilament bicomponent yarns of the sheath-core type. The spinning process is carried out by feeding a portion of the lower relative viscosity polymer stream through a channel for forming a filament sheath, fed into the center of each spinning orifice through Particularly good results have been obtained with the use.

After the filament bundle has passed through the spinning orifice, it is optionally passed through a hot tube.

The present invention relates to a multifilament yarn obtained according to the above method, preferably formed from polyethylene terephthalate, wherein the yarn has at least 15 yarns.
The finished drawn multifilament comprising filaments, preferably 15 to 1000 filaments, has a linear density of at least 70 decitex (decitex), preferably 300 to 2500 decitex, and has the following properties: strength of 700 to 1000 mN / tex; 375-600mN / tex
5% LASE, 5-20%, especially 7-17%, preferably about 9.5% breaking strength, hot air shrinkage of 0.5% or more and less than 3.7% measured at 160 ° C. 1 It is characterized by having an average relative viscosity of the spun filament of from .700 to 2.200, preferably about 1.900.

The process according to the invention is preferably such that before drawing the yarn, it is treated with an agent for promoting adhesion to the elastic material, such as an epoxy-containing compound or a protected isocyanate- and hydroxyl-containing compound. It is characterized by being processed. According to the invention, the process is preferably carried out such that the carboxyl end group content of the drawn yarn is less than 18 meq / kg of yarn, especially 3-8 meq / kg.

An advantageous embodiment of the process according to the invention is that the polymeric material for forming the relatively high relative viscosity core zone in each of the spinning orifices comprises 50 to 90% by volume, preferably about 75% by volume, 50 to 10% by volume of polymer material forming a lower relative viscosity sheath zone
Is characterized by the following.

The invention also includes, in particular, a cord consisting of two or more multifilament yarns according to the invention twisted with each other. The invention particularly encompasses substantially polyester cords of the type used for the reinforcement of elastic and other objects such as pneumatic tires for vehicles, transmission belts, hoses, conveyor belts, etc., which cords are preferably polyethylene. Made of terephthalate, after the treatment of the cord by immersion and dtex 1100 (Z393) × 2 (S
393), the cord strength is 560-8
It is in the range of 50 mN / tex and the elongation at break of the cord is 8-25.
%, Especially in the range of 10-20%, and the code ratio 5% L
ASE is in the range of 215 to 350 mN / tex, 180 ° C
Hot air shrinkage measured in the range of 0.5% or more to less than 3.4%, and a Mallory tube fatigue value of 115 to 100
It is characterized by being in the range of 0.

The present invention also includes a molded elastomer, such as a pneumatic vehicle tire, the object of which is reinforced with a yarn or cord according to the present invention. The invention furthermore comprises a pneumatic tire of the vehicle type, in particular a passenger vehicle, of the radial cell ply type, characterized in that the tire comprises a carcass substantially formed from a cord according to the invention. The invention furthermore relates to a network made from a cord according to the invention.
(tow). The yarns according to the invention can be advantageously used as sutures or in the manufacture of seat belts, especially if they consist of polyethylene terephthalate.

[0020]

As mentioned above, especially in high speed spinning of polyester yarns, when the method according to the invention is used, the reduction in the breaking strength of the yarn is less than that of the high speed yarn obtained in a conventional manner; It has been surprisingly found that low hot air shrinkage is retained at high spinning speeds, for example 4000 m / min. Dipped polyester cords made from the yarns of the present invention are particularly preferred due to the high modulus / shrinkage ratio of the combination of high modulus value and low hot air shrinkage value of about 2.5% and Mallory tube fatigue value of about 175. .

Although the surprising effect of the method according to the invention cannot be completely explained, this effect depends in particular on the lower value of the relative viscosity in the sheath zone of the filaments and, consequently, on this sheath at higher spinning speeds. It is believed that faster cooling in the zones causes no or little difference in orientation between the sheath and core zones of the filament. Generally, in the drawing operation following spinning, the molecular orientation across the entire cross-section of the filament is optimal and can be comparable in the sheath and core zones. In essence, the method according to the present invention recognizes that by presetting the degree of relative viscosity difference between the core polymer and the sheath polymer in the filament, the change in molecular orientation across the cross section of the spun filament can be affected. Show. Even at high polymer throughputs per spinning orifice, for example above 3.5 g / min, the principles of the present invention, that is, controlling the change in molecular orientation across the cross section of the filament, have been found to still be valid. Depending on the intended yarn properties, the method according to the invention may be such that the birefringence across the cross section of the filament shows a deep dent (birefringence at the core is lower than that at the sheath) or a substantially straight line Can be implemented.
Alternatively, the method according to the invention can be such that the birefringence across the cross-section of the filament shows a reverse dent (birefringence at the core is higher than at the sheath).

The method according to the invention will be further described with reference to FIGS. These are schematic representations on an enlarged scale of the orientation distribution in one spun filament 43. FIG. 6 shows a conventional filament obtained by high speed spinning, wherein core zones and sheath zones of different relative viscosities are not used in the spinning orifice. The filament 43 shown in FIG. 6 is obtained, for example, by high speed spinning at 4000 m / min, and the birefringence over the cross section of the filament shows a depression 44 with a rather deep depression on the centerline 45 of the filament. The molecular orientation, where birefringence is a measure, will show the same subsidence across the cross section of the filament. In the outer zone of the filament according to FIG. 6, the molecular orientation is therefore much higher than in the core of the filament.

FIG. 7 shows one filament 4 according to the invention.
3 is also a schematic representation of, for example, 4000 m
/ Min spinning speed. In accordance with the present invention, it includes a core zone 46 designated C, where the relative viscosity is higher than in a sheath zone 47 designated S. The theoretical birefringence across the cross section and thus the molecular orientation is shown by the solid line 48. From the shape of the line 48, after the original dip in the core zone 46 of the filament, the birefringence and thus the molecular orientation drops sharply at the border of the relatively low-viscosity sheath zone 47, after which they reappear towards the outside of the filament. It is clear that it gradually increases. Compared to FIG. 6, the line shape in FIG. 7 shows that the difference in birefringence and molecular orientation across the cross section of the filament has been significantly reduced by using the method according to the invention. Dotted line 4 in FIG.
9 also shows the approximate tendency of birefringence when the method according to the invention was not applied.

FIG. 8 again shows one filament 43 spun according to the conventional method, wherein core and sheath zones of different relative viscosities are not used in the spinning orifice. The filament 43 of FIG. 8 is obtained at a relatively moderate spinning speed, for example, 800 m / min. At such moderate spinning speeds, cooling involves a slight temperature gradient from the core to the sheath of the filament. Thus, the birefringence and molecular orientation show a virtually linear trend 50 across the cross section of the filament, as is evident from line 50 in FIG.

FIG. 9 is a schematic representation of one filament 43 of the yarn, also obtained at a spinning speed of 800 m / min. A higher relative viscosity core zone 51 (C) and a lower relative viscosity sheath zone 52 (S) are provided.
This method therefore shows a tendency 53 in which the birefringence and the molecular orientation are in principle increased over the cross section of the filament. Such a tendency of the molecular orientation across the cross-section in principle results in a higher resistance of the yarn to bending loads and fatigue, so that damage to the cord is reduced, higher knot strength is obtained and the effectiveness of the cord is reduced. Can be improved.

In the process according to the invention, special substances can optionally be added to the sheath and / or the core of the filament. In this regard, the use of substances that provide adhesion to the elastic body, hydrolytic stability and light stability is conceivable.

With respect to the prior art, the following must be stated.

EP 0,080,906 describes a process for producing polyethylene terephthalate multifilament yarns for technical applications such as reinforcement of elastics such as vehicle tires, V-belts and conveyor belts. It also proposes the use of higher spinning speeds, ie, 2000, 2500 and 3500 m / min, in the production of polyester industrial yarn. European Patent No. 0,080,906 discloses that the temperature ranges from 35 to 80.degree.
It is proposed to improve the quality of the yarn spun at high speeds by using different methods, including delaying the cooling of the filament bundle by blowing hot air at 0-80 ° C. This treatment is also aimed at reducing the birefringence difference between the core and the sheath of the filament. Cooling with heated air is a useful process as such under certain conditions that can result in improved yarn quality. However, this process is only applicable to a limited extent. Because cooling with hot air is only effective if the production per spinning orifice is relatively small,
It is not effective when the productivity is higher than 3.5 g / min. In that case, at a spinning speed of 4000 m / min, clearly the use of the method of EP 0,080,906 results in an unduly large difference in the birefringence across the cross-section of each filament, and therefore in industrial yarns The desired high strength, high modulus and low shrinkage cannot be achieved. This also means
It is also recognized in EP 0,080,906 (see page 15, lines 23-27, page 16, line 106). The present invention provides another method whereby high tenacity, high modulus and low shrinkage can be achieved at spinning speeds of about 4000 m / min and even output per spinning orifice of, for example, 4.17 g / min.

Japanese Patent Application No. 56-30559 (publication No. 57-149513) discloses a sheath-core type two-component polyethylene terephthalate (petp) intended for textile use, that is, outer garments, and industrial use such as tire cord. Related to multifilament yarn. There, the core of the filament consists of petp type A, which has a higher intrinsic viscosity and therefore a higher relative viscosity than the sheathing petp type B. This publication is based on the idea of combining the high intrinsic viscosity petp with that of the low intrinsic viscosity to benefit from the advantageous properties of the two polymers. Because petp with a relatively high intrinsic viscosity has higher strength than itself, but a relatively low modulus /
Has a shrinkage ratio. Relatively low or moderately high intrinsic viscosity
petp has a better modulus / shrinkage ratio than itself, but has a relatively low strength. Although the basic idea of this Japanese patent application may yield favorable results for certain applications and specific spinning conditions, this known method satisfies the requirements of industrial yarn for its strength and modulus / shrinkage ratio. Not expected to bring yarn. This means
Significant differences in intrinsic viscosity between the core and the sheath (0.10 <
η _A −η _B <0.60).
This would be the case at relatively high spinning speeds of 0-4000 m / min. The difference between the intrinsic viscosities expressed in relative viscosities is about 0.
It has to be added that 108 <η _A −η _B <0.648. According to the description, this Japanese patent application publication relates to a spinning speed of 100-1500 m / min.

Just like Japanese Patent Application No. 56-30559, Japanese Patent Application No. 56-220226 (Japanese Patent Application No. 58-104221) discloses a high and low viscosity petpA in the production of bicomponent filaments, respectively. And B, based on the idea of combining the two types of advantages. It proposes to arrange the two petp types A and B in a multilayer structure, for example, in petals. This last-mentioned construction is considered less suitable for industrial applications such as tire yarns.

Two of the above-mentioned Japanese Patent Application Publications (1983)
It has to be added that the purpose intended by 149513 and 58-104221) is quite different from the purpose of the present invention. These two Japanese patent applications relate to blending properties such as strength and modulus / shrinkage of two types of polyesters with relatively large differences in intrinsic or relative viscosity.

German Patent 2,747,803 describes a method for producing petp multifilament yarns intended for industrial applications such as automotive tires. It is 500 ~
It is proposed to use a spinning speed of 3000 m / min, in which the extruded filaments are immediately below the die.
It is solidified by blowing cooling air in the feed direction and countercurrent of the moving filaments, resulting in a fairly high draw tension and thus a high molecular orientation. This publication also describes post-drawing the spun yarn in combination with a special heat treatment. Under certain conditions, this known method provides several improvements, but this method very often has a relatively large difference between the inside and outside of the filament, and thus optimizes especially the yarn and cord strength. It is thought that it has a disadvantage that it cannot be obtained.

US Pat. No. 3,963,678 describes a process for producing polyester monofilaments for use in tire, V-belt reinforcement and other industrial applications. Melt spinning is performed in a conventional manner for monofilaments by spinning into an air gap and then cooling in a water bath. In order to obtain a filament with improved loop strength and lower birefringence in the filament sheath, a special two-stage drawing method has been proposed in combination with a heat treatment in a furnace at a temperature of about 500-600 ° C. As a result, the outside of the monofilament will have a much higher temperature than the core. US Patent 3,963,678
The method according to No. 1 is not suitable for use in multifilament yarns, since the filaments adhere to one another, which is unacceptable.

US Pat. Nos. 4,195,051 and 4,1
No. 34,882 relates to high speed spinning of polyester multifilament yarns at a speed of about 5000 to 7500 m / min, with a small difference in birefringence being provided between the sheath and core of each filament. A small difference in birefringence can be caused by making the temperature of the polymer at the wall of each spin orifice at least 5 ° C. higher than the average temperature of the polymer in the spin orifice. This method is used for the production of multifilament yarns for textile applications, and obviously has the purpose of improving the dyeability of textile yarns. This known method also provides a good starting yarn for the texturing process often applied to textile yarns.

European Patent 0,056,667 describes that
A method for the production of bicomponent multifilament yarns for technical applications such as nets and fishnets is described. It relates primarily to the production of black yarn, where the black pigment is present in the form of insoluble carbon black particles. To prevent excessive wear of expensive mechanical parts as a result of the presence of these pigments in the filament plane, a pigment-free sheath is provided around the pigment-containing core of each filament, which is particularly advantageous in the case of spin draw. It is. European Patent 0,
In the method according to 056,667, the intended purpose is quite different from that of the present invention. The resulting yarn consists of filaments with different pigment contents in the core and the sheath. Also, 4
A relatively low spinning speed of 00 m / min is used. Note that this publication happens to include one example (Table 1, Test 6) describing a filament having a petp black pigment-containing core and pigment-free sheath of relative viscosities of 1.89 and 1.85, respectively. I have to.

[0036] Dutch Patent 6,817,305 describes that
The present invention relates to a method for producing multifilament polyester yarn for textile applications. The polymer is split into two substreams, and a special liquid, for example, polyglycol, is added to one of the substreams, which reacts with the polymer and changes its intrinsic viscosity. The partial streams are then combined again and spun into a bicomponent multifilament yarn consisting of filaments of the side-by-side or sheath-core type as in Example IX. In the only example (IX) describing a sheath-core type filament, a relatively low intrinsic viscosity
The petp is in the core and the relatively high intrinsic viscosity of the petp is in the sheath, a situation exactly opposite to that of the present invention. Also,
Dutch Patent 6,817,305 discloses low intrinsic viscosity values, i.e. 0.50 to 0.61 (1.50 to 1.6 each).
1, which corresponds to a relative viscosity of 1).

Japanese Patent Application No. 41-61912 (publication 44-21170) relates to a sheath-core type polyester bicomponent yarn in which the sheath and core can be petp. The filament sheath is at least 0.1 mm less than the core.
It has a small intrinsic viscosity of 05. The method of this patent discloses, for that purpose, subjecting the low-viscosity sheath to super-stretching, i.e., orientationless stretching, so that the sheaths of the individual filaments adhere to one another, so that the multifilament yarn is woven or knitted. It can be processed as a monofilament. In the fabric, the low viscosity sheath of the filaments is again separated and the multifilament is formed again. In the examples, only low intrinsic viscosities of 0.60 to 0.66 are mentioned, which are unsuitable for industrial yarns such as tire yarns.

Japanese Patent Application No. 51-4575 (Publication No. 52-88678) describes a petp yarn having a low-viscosity sheath and a high-viscosity core for the production of a nonwoven fabric of bonded filaments. Using a relatively low viscosity in the sheath will result in the low viscosity sheath in the laminated web melting and sticking together at the processing temperature, while the core does not melt. The aim is to cause the maximum possible difference in orientation between the sheath and the core in order to achieve a melting point difference between the sheath and the core. This is because the present invention, ie, to eliminate the difference in orientation between the sheath and the core during melt spinning and to give the sheath a relatively somewhat lower molecular orientation at low speed spinning, e.g. This is exactly the opposite of the intended result by using a low viscosity polymer. The examples give very large birefringence differences, which are unacceptable for the production of the industrial multifilaments of the invention.

Japanese Patent Application No. 57-173798 (Publication No. 59-66507) discloses a petp textile yarn in which the intrinsic viscosity of the skin (0.45-0.55) is lower than that of the core (0.60). Describe the ultra-high-speed spinning method that makes. A spinning speed higher than 6000 m / min is used, and the yarn is wound within a distance of 1 m below the die. The purpose is an ultra-high speed production of textile yarns having approximately the same yarn properties as low speed spun and drawn yarns. Under the spinning conditions described in this document,
It is not possible to process high viscosity polymers into industrial yarns.

Japanese Patent Application No. 57-173799 (Publication No. 59-66508) discloses a low-viscosity polymer (η _inh =
0.63) at high spinning speeds (> 3000 m / min) into textile yarns. By heating the die to a temperature about 100 ° C. above the temperature of the polymer, the difference in orientation between the sheath and the core can be reduced and the spinning can be performed without post-drawing, with the same properties as low-speed spinning and subsequently drawn textile yarns Can be carried out at such a high speed that a textile yarn is obtained. This well-known method does not mention any difference in intrinsic or relative viscosity between the filament sheath and the core, regardless of the production of industrial yarns of the high intrinsic or relative viscosity type.

Japanese Patent Application No. 58-15784 (published application No. 59-144615) describes a method for improving the line strength and knot strength of thick polyamide monofilaments used for fishing lines and fishnets. When spinning thick polyamide monofilaments, which are cooled in a water bath, there will be a large difference in molecular orientation between the sheath and the core. By using a relatively low viscosity polymer for the polymer sheath, a more uniform molecular orientation will be obtained and thus higher tensile and knot strength. This publication makes no mention of the method according to the invention for spinning polyester multifilaments.

Dutch Patent 6,502,107 describes a method for spinning crimpable filament yarns such as polyamides, polyesters and the like. The molten polymer is split into two substreams, after which one of the substreams is given a speed 1.5 to 4 times faster than the speed of the other substream. The partial streams are combined again and spun into a two-component yarn. Differences in the flow rate of the spinning material within one and the same spinning orifice will result in differences in the pre-orientation of the components while the filament is drawn. This known method is directed to textile applications such as the production of crimped yarn.

Dutch Patent 6,910,882 relates to the production of crimped staple fibers of polyamide-6. The melt is split into two substreams, one of which is subjected to a vacuum treatment, resulting in a change in relative viscosity. The partial streams are combined again and spun into a two-component yarn. This method is directed to textile applications such as the production of crimped staple fibers.

Dutch Patent 6,512,920 describes a sheath-core type two-component tire yarn, in which the core and the sheath consist of chemically different polymers. The core is polyester and the sheath is nylon. In this known method, the spinning speed is as low as 300 m / min.

German Patent 1,288,734 describes a method for melt spinning petp filament yarns intended for industrial applications, such as for reinforcing elastomers. In this publication (col. 4, lines 33-64), it is proposed that the yarn bundle is subjected to slow cooling by suitable heating means, such as a hot tube, just below the spinneret. This publication is 50
For spinning speeds below 0 m / min.

No. 1,803,435 in West Germany, No. 6,807,158 in the Netherlands, No. 1,157,433 in the UK and Japanese Patent Application No. 41-64837 (publication No. 44-25)
04) describes a method for producing crimped textile yarn from polyester. In each spinning orifice, a polyester of different relative or intrinsic viscosity is spun according to a two-component system. The resulting filaments are of the eccentric sheath-core or side-by-side type.

DE 32 26 346 gives a description of polyester tire cords and refers to the cord properties after vulcanization in tires. It is clear from the description that the cord is made from conventional high speed spun polyester yarn spun at a speed higher than 2000 m / min. It does not disclose the use of a difference in viscosity between the sheath and the core. In the production of a cord according to the method of the invention, the resulting cord properties are in some respects more favorable than those obtained according to DE 32 26 346.

DE-A-3207826 is directed to protecting pneumatic tires in which the carcass is reinforced with polyester cord. Various properties of cord and yarn filaments are set forth in the specification. In particular,
In the polyester filament, the ratio of the birefringence of the sheath and the core is 1.03: 1 in order to obtain the desired tire cord characteristics.
And between 1.15: 1 and therefore exhibit a dimple-shaped profile. The present invention contemplates using a higher viscosity in the core than in the sheath to reduce the birefringence ratio described in German Patent 3,207,826 below 1.03.

EP 0,056,963 states that
Birefringence difference between the sheath and the core is 100-800 × 10 ^-4 ,
Particularly, polyester yarns described in the range of 100 to 400 × 10 ⁻⁴ are described. Application of the method according to the invention with the difference in viscosity between the sheath and the core of the filament results in this difference in birefringence between the sheath and the core being less than 100 × 10 ⁻⁴ . According to the present invention, the difference in birefringence between the sheath and the core within the filament is preferably somewhat negative (birefringence across the cross section of the filament exhibits a reverse dent (convex)), which is more convenient. Yes, resulting in better code characteristics. EP 0,056,963 further states that the peak temperature of the tangent to the loss angle for the yarn should be between 85 and 100 ° C., which is desirable in the case of high speed spun yarn for textile applications. It is said. In a yarn according to the invention intended for industrial use, this peak temperature is around 115 ° C. Also, European Patent 0,056,9
In No. 63, the maximum loss tangent must be between 0.115 and 0.135, which is required for textile yarns. In an industrial yarn according to the invention, the maximum of this loss tangent is less than 0.100.

The present invention will be further described with reference to the accompanying drawings.

FIG. 1 is a simplified schematic representation of a method for melt spinning a multifilament yarn according to the present invention. The molten polymer is supplied to the heating chamber 1 under high pressure through an extruder (not shown). It contains a spinning device 2 consisting of several parts and is shown on an enlarged scale in FIG. The molten polymer is forced through a number of spinning orifices 4 in a base 3 which is rectangular when viewed from below. The filament comes out of the base 3 as a bundle 5. The filament bundle 5 is passed through a blow box 6 shown schematically, where the bundle is cooled with room temperature air. Air is blown onto the filament in the direction indicated by arrow 7, transverse to the direction of movement of the bundle. The filament bundle 5 is then contacted with a finish metering unit 8, where a suitable lubricant is applied to the filaments of the bundle in a conventional manner. The multifilament bundle then first reaches a set of precursor rolls 9 and 10 to give the yarn bundle the correct speed. The peripheral speed of the driven roll 9 determines the speed at which the filament is spun and is therefore called the spinning speed. The spun multifilament yarn is roll 10
, It is wound into a package 11. The speed at which the yarn is wound is approximately equal to the spinning speed. After the yarn has been wound, it is drawn on another machine (not shown) at the desired ratio. However, in principle, the drawing can also be carried out in a spinning machine in a continuous spin drawing process. If a spinning process known per se is used, a drawing tool (not shown) consisting of one or more driven rolls is provided between the first driven roll 9 and the winding bobbin.

The spinning device 2 shown in FIG.
2, consisting essentially of an intermediate plate 13 and a base plate 3. In the space between the intermediate plate 13 and the base plate 3, there are partitions 14 and 15. Various parts 12, 13, 1
4 and 15 are clamping walls 16 provided with lower and upper grooves 17 and 18 for making a dovetail with corresponding grooves in the base plate 3 and the upper block 12.
Are held together. During operation of the spinning apparatus, the various parts are fastened tightly and held together by a high pressure, for example 200 bar, exerted by the molten polymer. The device is suitably sealed with a packing material. Filtration of the polymer in the spinning device takes place through a parallel filter 19. The parallel filter 19 consists essentially of an alternating stack of coarse support meshes 20 and filter mesh packs 21, shown by serpentine lines. The support mesh is alternately sealed on its outer circumference and its inner circumference. The construction and operation of parallel filters are known per se and are disclosed in US Pat.
No. 61,489.

The upper block 12 of the spinning device 2 is supplied with a single molten polymer, for example of polyethylene terephthalate, in the direction indicated by arrow 22 to an inlet channel 23. The polymer then flows to the upper plate 24, which overlies the parallel filter 19, and exerts the desired axial pressure on the parallel filter via the constriction. Then the polymer
It flows in the space between the outer periphery of the filter and the upper block 12 downwardly and simultaneously through the support net 20 horizontally and then through the filter net pack 21 as indicated by the arrows.

In a particular method aspect according to the invention,
The parallel filter 19 is divided into two parts 26 and 27. The polymer, indicated by the letter S, filtered through the upper portion 26 of the parallel filter, passes through the central channel 28 through the path indicated by the arrow, through the upper partition 14 and the lower partition 15.
To the space 29 between the two. Via the constriction 30, the polymer S flows over the upper end of the partition 15 into a channel 31 which is collinear with the spinning orifice 4 in the base plate 3. The polymer, indicated by the letter C, filtered through the lower portion 27 of the parallel filter, flows downward through the channels 32 and 33, as indicated by the arrows, and flows such that the polymer stream C flows exactly into the center of the channel 31. . That is, the polymer streams S and C flow into the channel 31 in a concentric sheath (S) -core (C) arrangement.

Via the auxiliary net 34, the concentric polymer stream of the channel 31 proceeds to the widened inlet channel 35 of the spinning orifice 4 ending at the lower end of the base plate, after which the polymer stream exits in the form of a thread 36. Forced to. After the filaments 36 have cooled, they form a filament yarn bundle 5. In accordance with the present invention, the polymer stream C that has reached the spinning orifice 4 has a shorter residence time than the sheath polymer S that has been filtered through the upper portion 26 of the parallel filter, as the copolymer C filtered through the lower portion 27 of the parallel filter. It will have a higher relative viscosity than the polymer stream S. Eventually, at each spinning orifice 4, one polymer stream, in particular of polyethylene terephthalate, is formed, which consists of two concentric zones, a sheath (S) zone and a core (C).
Indicating the zones, the relative viscosity of the core zone is higher than that of the sheath zone. A cross section of the polymer stream at the position of the spinning orifice 4 is shown in FIG. The boundary between the core zone (C) having a relatively high relative viscosity and the sheath zone (S) having a relatively low relative viscosity is indicated by a dashed line.

The difference in the relative viscosities of the sheath and core polymer streams is:
One filament can be measured in a simple manner in principle by spinning two filaments, all consisting of the polymer stream S, and the other filament consisting entirely of the polymer stream C. This can be achieved by closing the channel 33 at one location and closing the recess 30 around another channel at another location. Thus, the relative viscosities of each of the two filaments, one from the sheath polymer stream S and one from the core polymer stream C, can be measured separately.

FIG. 4 is an enlarged scale view of a cord 37 made from two or more multifilament yarns according to the present invention. In the case of two multifilament yarn cords, each of these yarns has hundreds of high Z twists per meter. The code is two Z
It is made from such yarns by twisting the twisted yarns equally, but in opposite directions (S). A general type of code is dtex 1100 (Z393) × 2 (S39
This is a code called 3). This type of code
It is formed from two multifilament yarns each having a linear density of decitex 1100 and 393 Z twists per meter. The two Z twist yarns are twisted with each other in the S direction,
The cord has 393 twists per hit.

The cord 37 can be used in an adapted configuration or in the form of a cloth to reinforce an elastic body, such as a vehicle tire 37, the details of which are shown in FIG. The cord can be incorporated into the carcass (in which case it comprises one layer 39) and / or into one of the two belt strips 40 and 41 under the tread 42 of the tire 38.

The above-mentioned birefringence over the cross section of the filament is measured by an Interphako interference microscope. The measurement of birefringence, a measure of molecular orientation, is described in Handbuch der Mikro
Skopie), Beyer, VEB Verlag Technik, Berlin, 1973.

The characteristic values described herein, such as the linear density, strength, breaking strength of yarns and cords, 5% LASE (stress at specified elongation) and the ratio 5% L of yarns and cords
The ASE, the elongation at break of the yarn and cord, and the hot air shrinkage of the yarn and cord at 160 ° C. and 180 ° C. respectively,
Measured according to ASTM D885M-1979. Deviating from these test specifications, the hot air shrinkage is 1N / tex
At 180 ° C. with a pretension of. Mallory tube fatigue values were measured according to ASTM D855-1967. In this Mallory tube fatigue test, the yarns according to the invention or not (Tables 1 and 2, Example 1, Experiments B, C and D and Example 2, Experiments F, G and H)
And commercially available polyester yarn Diolen ™
The average elapsed time to break was measured for both 2000 (Table 1, Experiment A) and Diolen 2200T (Table 2, Experiment E) test specimens. Assuming that the measured elapsed time to break of a standard Diolen 2000 sample is x ₀ and the measured elapsed time to break of a yarn according to the invention or not according to the invention is x _n ,

[0061]

The result of x _n / x ₀ × 100 is defined as the Mallory tube fatigue value.

In the present specification, the modulus is mN / tex
5% LASE calibrated for the total linear density of the yarn or cord represented by. This calibrated 5% LASE
Is referred to as the 5% LASE ratio.

As used herein, the relative viscosity (also referred to as viscosity ratio or solution viscosity, indicated by η _rel ) of a polyester is to be understood as the relative viscosity measured on the spun product. What is a spun product?
Immediately extruded, undrawn, totally untreated filaments (no finish). For this spun product, the relative viscosity is measured according to the following procedure: 1 g of spun product is stirred with meta-cresol (purity 99.5%).
(Super) dissolves in 100 g at 125 ° C. within 40 minutes.
The viscosity of the obtained solution, that is, the outflow time t ₁ (second) is set to 1.2
25 ° C using an Ubbelohde viscometer with a capillary tube of 5 mm inside diameter
And compared with the effluent time (sec) of the pure solvent measured with the same instrument. The relative viscosity is given by the following formula:

[0064]

## EQU2 ## It can be calculated by η _rel = t ₁ / t ₀ .

If the spun product is 40 ° C. at 125 ° C.
If it is crystalline so as not to dissolve in meta-cresol after minutes, a mixture of 2,4,6-trichlorophenol and phenol (ratio of about 7:10, density d ₂₅ = 1.236 ±
0.001) (referred to as TCFF). T
CFF viscosity is measured as described above. The TCFF viscosity thus obtained is given by the following formula:

[0066]

Using η _rel = 0.808 · x + 0.198 (x is the measured TCFF viscosity), it is converted to the relative viscosity measured in meta-cresol.

The standard deviation of the η _rel measurement with meta-cresol is 0.002.

The standard deviation of η _rel obtained with the TCFF mixture as solvent is 0.004.

To show a very small difference in relative viscosities,
Several measurements were taken and the average of these measurements was η
By calculating _rel , the standard deviation can be converted if desired.

[0070]

The present invention is further illustrated by the following examples. Example 1 Polyethylene terephthalate is spun on a machine for making bicomponent yarns. Two extruders, each fed with the same type of granules of the same relative viscosity (η _rel = 2.05 as measured on granules) are used. The as-spun filament passes through a separation zone before being cooled by blowing air at the same temperature as the ambient temperature. The yarn then passes through two godets and is wound. Other spinning data are shown in Table 1. In experiments B, C and D, the yarn is collected in duplicate and then subjected to a two-stage drawing. The first stretching stage is 80 ° C. with 7 pins 21 cm in diameter
Done in The yarn is then subjected to a second draw at a steam temperature of 256 ° C. in a 10 m long steam draw frame and wound at 226 m / min. Experiments A, B,
Other data of the drawing process in C and D and the properties of the drawn yarns are shown in Table 1. The drawn yarn is twisted and dtex 1100 (Z393) × 2 (S393)
The tire cord was configured as follows. To improve adhesion to the elastic material, the green cord is subjected to a two-stage dipping process. The properties of the immersed cords are shown in Table 1. The two-stage immersion treatment of the cord according to the present invention is performed using the following procedure known per se. In a continuous process, dtex 110
The 0 (Z393) x 2 (S393) type cord is passed through a first bath and pre-soaked therein, and then passed through a second bath where the cord undergoes a main soak. Between the first bath and the second bath, the cord is dried at a temperature of 240 ° C. under a tension of 10 N for 60 seconds. After the main dip had been applied, the cord leaving the second bath was heated at 220 ° C. under 4.5 N tension for 1 hour.
Dry again for 02 seconds.

The first immersion bath at a temperature of about 20 ° C. to give a pre-soak (type D417) has a solids content of 5% by weight and the composition of the first immersion bath is as follows: 876.4 parts by weight of oxidized water tragacanth gum (2% by weight solution in water) 20.0 parts by weight 4,4'-diphenylmethane diisocyanate protected with phenol (90.0 parts by weight of 40% by weight dispersion in water) Diglycidyl ether of glycerol (commercially available from Nagase as NER-010A 13.6 parts by weight) 1000.0 parts by weight The amount of presoak present on the finished two-stage soaked cord after immersion is 0.5-1% by weight.

The second bath (at a temperature of about 20 ° C.) for providing the main immersion (type RFL-D5A) has a solids content of 20% by weight and the composition of the second immersion bath is as follows: Resorcinol formaldehyde resin precondensed in resin group (75% by weight solution in water) 28.6 parts by weight Sodium hydroxide (5% by weight solution in water) 12.0 parts by weight Formalin (37% by weight solution in water) 20.8 parts by weight Mineral water 370.0 parts by weight Latex group vinyl-pyridine latex (40% by weight dispersion in water) (commercially available from General Tire Company and Goodear 415.4 parts by weight as Gentec VP latex) Ammonium hydroxide (25 in water) 25.0 parts by weight Demineralized water 128.2 parts by weight 1000.0 parts by weight The amount of main soak present on the finished two-stage soaked cord after soaking is 3-4% by weight. For Experiment A, the spinning and drawing conditions and properties are for a low speed, conventionally (mono) spun yarn. That is, there is no difference in relative viscosity between the filament sheath and the core. Experiment B is an example of low spinning speed and experiment C
And D were made in accordance with the present invention. That is, the sheath and the core have different relative viscosities, and the spinning speed is 500, 2 respectively.
000 and 4000 m / min.

In experiments B, C and D, the relative viscosity of the core polymer measured on the spun product was 0.010-0.030 higher than that of the sheath polymer. Experiment B
In C and C, the relative viscosities set forth in Table 1 are the average viscosities of the sheath and core polymers in the filament, also measured on the spun product.

The most striking is the properties of the dipped cord of Experiment D. In accordance with the present invention, the same strength, improved modulus or ratio of 5% LASE and much lower shrinkage (ie, excellent modulus / shrinkage ratio), and improved fatigue resistance (Mallory tube fatigue), as obtained at low speeds A soaked cord with was obtained.

[0075]

[Table 1] Example 2 Polyethylene terephthalate is spun on a machine for making bicomponent yarns and then stretched under the conditions described in Example 1. However, in experiments F, G and H, the volume ratio core / sheath is 60/40. All other spinning, drawing and cording conditions are the same as those of Example 1. Experiment E
Does not comply with the present invention and therefore there is no difference in viscosity between the sheath and the core. In low spinning speed experiment F, and in experiments G and H according to the present invention, the relative viscosity of the polymer in the core in the spinning orifice measured on the spun product is only 0.010-0.030 than that of the polymer in the sheath. high. In experiments F, G and H, the relative viscosities set forth in Table 2 are the average viscosities of the sheath and core polymers in the filament, also measured in the spun product.

Most notable is the favorable properties obtained in Experiment H; ie high spinning speeds (4000 m / m
Despite this, the resulting product has a combination of low loss of cord strength and high ratio LASE-5% (246 mN / tex), very low shrinkage (2.3%) and excellent Mallory tube fatigue values (2.3%). 185).

[0077]

[Table 2]

[Brief description of the drawings]

FIG. 1 shows a melt spinning apparatus.

FIG. 2 shows a spinning device on an enlarged scale.

FIG. 3 is a cross-sectional view of a polymer stream in one spinning orifice.

FIG. 4 shows a code.

FIG. 5 shows details of a pneumatic tire for a vehicle.

FIG. 6 shows the birefringence over the cross section of one filament on a greatly enlarged scale.

FIG. 7 shows the birefringence across the cross section of one filament on a greatly enlarged scale.

FIG. 8 shows the birefringence over the cross section of one filament on a greatly enlarged scale.

FIG. 9 shows the birefringence across the cross section of one filament on a greatly expanded scale.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location D01F 6/62 302 D01F 6/62 302A 8/14 8/14 B D06M 15/693 D06M 15/693

Claims (4)

(57) [Claims] 1. A method according to claim 1, intended for industrial use and comprising at least 500
A substantially polyester multifilament yarn of the type having a strength of mN / tex, wherein a molten polymer stream is extruded from multiple spinning orifices, cooling the spun filament bundle, optionally drawing the filament Using a spinning speed of 1600 m / min to 6000 m / min, and the relative viscosity of the polymer stream in the core zone at each of the spinning orifices is that of the sheath zone surrounding the core zone The relative viscosity difference between the core zone and the sheath zone is less than 0.100 and 0.00
A finished stretched multifilament yarn made of at least 15 filaments, having a linear density of at least 70 dtex, having a strength of 700 to 1000 mN / tex, a ratio of 375 to 600 mN / tex, made to be at least 3 % LASE, hot air shrinkage from 0.5% to less than 3.7% measured at 160 ° C., 1.700 to 2.200 average relative viscosity of spun filaments, 5 to 20% elongation at break Yarn. 2. At least 500
A substantially polyester multifilament yarn of the type having a strength of mN / tex, wherein a molten polymer stream is extruded from multiple spinning orifices, cooling the spun filament bundle, optionally drawing the filament Using a spinning speed of 1600 m / min to 6000 m / min, and the relative viscosity of the polymer stream in the core zone at each of the spinning orifices is that of the sheath zone surrounding the core zone The relative viscosity difference between the core zone and the sheath zone is less than 0.100 and 0.00
A finished stretched multifilament yarn made of at least 15 filaments, having a linear density of at least 70 dtex, having a strength of 700 to 1000 mN / tex, a ratio of 375 to 600 mN / tex, made to be at least 3 % LASE, hot air shrinkage of 0.5% or more and less than 3.7% measured at 160 ° C., average relative viscosity of spun filament of 1.700-2.200, mulch with elongation at break of 5-20% A cord comprising two or more twisted filament yarns composed of filament yarns. 3. A cord of the type used for strengthening a material, wherein after treating the cord by a two-stage immersion treatment to improve the adhesion to the material, the dtex
With respect to the 1100 (Z393) x 2 (S393) type cord, the cord strength is in the range of 560 to 850 mN / tex, and the 5% LASE of the cord is 215 to 350 mN / tex.
The hot air shrinkage measured at 180 ° C. is 0.5% or more and 3.4.
The cord according to claim 2, wherein the cord has a Mallory tube fatigue value in a range of 115 to 1000, and a breaking elongation of the cord in a range of 8 to 25%. 4. The method according to claim 1, having a strength higher than 580 mN / tex, a 5% LASE higher than 230 mN / tex, a hot air shrinkage measured at 180 ° C. lower than 2.6%, and a Mallory tube fatigue value higher than 150. Code according to range 3,