KR20050016438A - Method and Apparatus for Producing Polyamide Filaments of High Tensile Strength by High Speed Spinning - Google Patents

Abstract

The present invention relates to a method and apparatus for the production of high tensile strength polyamide filaments, such as nylon 6,6 at high speed. The invention also relates to yarns and other articles formed from such filaments. The present invention is particularly useful for providing at high spinning process speeds filament yarns having a specific strength equal to or better than the prior art while maintaining the ability to stretch the yarn. The present invention also relates to the provision of filament yarns extruded from deglossed or colored polyamide polymers.

Description

Method and apparatus for manufacturing high tensile strength polyamide filament by high speed spinning {Method and Apparatus for Producing Polyamide Filaments of High Tensile Strength by High Speed Spinning}

The present invention relates to a method and apparatus for the production of high tensile strength polyamide filaments, such as nylon 6,6 at high speed. The invention also relates to yarns and other articles formed from such filaments.

Various synthetic polymer filaments, such as polyamides, are extruded from melt spinning, ie, heated polymer melts. Melt-spun polymer filaments are prepared by extruding a molten polymer through a spinneret having a plurality of capillaries. The filament usually exits the spinneret and is then cooled in the quench zone. Details of the quenching and subsequent solidification of the molten polymer can have a significant impact on the quality of the spun filament.

Quenching methods include cross-flow quenching, radial quenching and pneumatic quenching. Cross-flow quenching is often used in the production of high strength polyamide fibers, and involves cooling the cooling gas across from one side of the membrane extruded filament rows. In crossflow quenching, the airflow is generally directed at right angles to the direction of movement of the membrane extruded filaments.

In radial quenching, the cooling gas is directed into the interior of the quench screen system surrounding the filament rows just extruded. Such cooling gas generally passes down with the filament and exits the quench system by exiting it.

Both cross-flow quenching and radial quenching are limited to relatively low velocity fiber production of about 2,800-3,000 meters / minute for high specific strength applications. Higher production rates increase the number of fracture filaments in the draw step. Fractured filaments interfere with the continuity of the process and reduce production yields.

In the 1980s, Vassilatos and Sze made significant improvements in the high-speed spinning of polymer filaments, particularly polyester filaments. This improvement is disclosed in US Pat. Nos. 4,687,610, 4,691,003 and 5,034,182.

The patents disclose a gas conditioning technique that allows the gas to surround the membrane extruded filament and adjust its temperature and damping profile. Quench systems and methods of this kind are known as air quench or air spinning systems. Other air quenching methods include those described in US Pat. No. 5,976,431 and US Pat. No. 5,824,248.

The air quench spinning process provides the advantage that the filament and subsequent thread tension during spinning are reduced. In general, this reduced yarn tension provides higher productivity through higher spinning speeds at reduced filament breaks, and advantageous processability in wound yarns. In general, air quenching involves supplying a volume of cooling gas to cool the polymer filaments. Any gas can be used as the cooling medium. The cooling gas is preferably readily available air. If desired due to the sensitive nature of the polymer filaments, especially when the polymer filaments are hot and membrane extruded, other gases may be used, for example inert gases such as water vapor or nitrogen.

In air spinning, the cooling gas and the filaments move substantially side by side in the same direction along the conduit, where the speed is controlled by the speed of the roll assembly means. Tension and temperature are controlled by the gas flow rate, the diameter or cross section of the conduit (which controls the gas velocity) and the length of the conduit. The gas may be introduced at one or more locations along the conduit. Air spinning enables spinning speeds greater than 5,000 meters / minute

Tenacity is the main fiber property of industrial fibers. Specific strength is obtained by stretching the quenched fibers step by step. This stepwise stretching works well in existing commercially available low speed crossflows. One example of a known cross-flow quench and coupled spin-drawing apparatus is shown in FIG. 1. In this apparatus, the molten polyamide is introduced at 10 into the spin pack 20. The polymer is extruded from the spin pack having an orifice designed to impart the desired cross section as the unstretched filament 30. After the filament exits the capillary of the spinning pack, the fiber is cooled by quenching with cross-flow cooling air in FIG. These filaments converge into the seal 60 while applying a conventional finish lubricant at 50 and are transferred by the feed roll assembly 70. Subsequently, the yarn is supplied to the first stretching roll pair 80, and then the second stretching roll pair 100 is supplied. The hot tube 90 or stretching aid may be used to facilitate the second stage of the stretching process. The thread is decelerated in the puller rolls 110 and 120. Roll 110, also known as a reduction roll, can be driven at a lower speed than stretch roll assembly 100 to control the shrinkage of the yarn. Roll 120, also known as a let-down roll, relaxes the tension of the thread so that the thread is wound to a lower tension than experienced during stretching. The guide 130 seats the thread in the seal package 140 to be wound up.

A known melt extrusion and coupled multistage drawing assembly using a crossflow quench system is shown in FIG. 2. The device of FIG. 2 is similar to the device of FIG. 1, but does not include the hot tube of FIG. 1 because the hot tube can damage the fibers. In FIG. 2, stretching is achieved through rolls instead of hot tubes. In this apparatus, the molten polyamide is introduced at 200 into the spin pack 210. The polymer is extruded from the spin pack having an orifice designed to impart the desired cross section as the unstretched filament 22. After the filament exits the capillary of the spin pack, it is quenched by a cross flow cooling gas at 230 in FIG. 2 to cool the fiber. This filament converges into the bundle of yarns shown at 250 while applying a conventional finish lubricant at 240 and is transferred by feed roll assembly 260. The yarn is then fed to the first stage stretching roll pair 270 and then to the second stretching roll pair 275. Optional third draw roll assembly 280 may be used to further stretch the fibers. The thread is decelerated on the deceleration roll 285. Guide 290 seats the thread in a seal package 295 that is rotated by the winder chuck to be wound.

It is not possible to achieve higher spinning rates while using crossflow quench to increase productivity in the crossflow quench systems of FIGS. 1 and 2. The ability to stretch the yarn is significantly reduced by the use of cross flow to reduce the specific strength of the final yarn. Moreover, it is important that the resulting polyamide yarns have at least the same properties as those obtained at slower speeds. In particular, it is desirable to maintain the desired specific strength, elongation at break and uniformity of the yarn produced. Thus, there is a need in the art for high speed yarn spinning methods and apparatus that maintain these properties.

The difficulty of using high speed spinning rates is especially evident in nylon yarns that are colored or polished. Such yarns are extruded from nylon polymers containing pigments that provide a variety of color ranges. Nylon yarn polymers are often polished by the addition of titanium dioxide or zinc sulfide. Typically, deglossed and / or colored nylons cause problems in melt extrusion due in part to different melt flow behavior, microstructure development and heat loss properties compared to unpigmented or unmatted nylon. Increased filament break levels when using deglossed or colored polymers are an old problem. Attempts to increase the extrusion rate are known to exacerbate the filament break problem. It would therefore be particularly desirable to provide a high speed spinning process for producing colored polyamide yarns without causing filament breakage.

Summary of the Invention

In the present invention, high specific strength yarns are produced at a spinning speed (defined as the surface speed of the fastest stretching roll) in the range of about 2500 meters / minute to more than about 5000 meters / minute at commercially desired levels of elongation at break and shrinkage. Manufacture. In contrast, yarns produced by conventional methods using conventional crossflow quenching are accompanied by a loss of specific strength and elongation as the spinning speed increases. The shrinkage of the fibers produced by these conventional methods is also undesirably high. A good balance of these properties is required to meet the requirements of specialty polyamide fibers used in applications such as automotive air bags, reinforcement seals (e.g., tire seals) in hardened rubber, protective clothing, soft luggage. In addition, low strength in combination with low elongation at break and shrinkage mean that the process is typically rough and of less than commercial quality.

It is therefore also an object of the present invention to provide increased filament extrusion rates while simultaneously improving the productivity and yarn properties of high strength nylon yarns and pigment containing high strength nylon yarns.

Providing a fast spinning and coupled drawing process that provides (optionally colored) polyamide filaments, yarns and articles having the desired properties, such as at least the same properties as those obtained in products made in conventional crossflow quenching processes. It is also another object of the present invention. It is another object of the present invention to provide yarns and articles having improved specific strength.

In accordance with this object, the present invention comprises the steps of extruding a polymer melt through a spin pack to form one or more filaments; Cooling and solidifying the filament by passing the filament through an air quench chamber in which quench air is provided to the filament and the quench gas moves in the same direction as the filament; Provided is a method for producing a polyamide yarn comprising passing the filament through a mechanical stretching step and stretching the filament and extending the length to form a yarn. When the yarn is a multifilament yarn, one or more filaments comprise a plurality of filaments, the plurality of filaments converge into the multifilament yarn, and the yarn is stretched and lengthened through a mechanical stretching step. If the yarn is a monofilament yarn, the one or more filaments comprise one filament per yarn.

Further objects, features and advantages of the invention will be apparent from the following detailed description.

1 is a schematic cross-sectional view of a conventional filament quench and coupled spin-drawing apparatus using a hot tube for stretching.

2 is a schematic cross-sectional view of another conventional filament quenched and coupled spin-drawing apparatus that uses rolls instead of hot tubes for stretching.

3 is a schematic cross-sectional view of an air filament quenching apparatus according to the present invention.

4 is a schematic cross-sectional view of a filament air quenching and coupled spin-drawing apparatus in accordance with different embodiments of the present invention.

5 is a schematic cross-sectional view of a filament air quenching and coupled spin-drawing apparatus according to another embodiment of the present invention.

6 is a graph comparing the maximum draw ratio achievable in the present invention and the prior art as a function of spinning speed.

7 is a graph comparing the specific intensity measured for filaments spun in accordance with the present invention and the prior art as a function of spinning speed.

According to the present invention, a process for producing monofilament and multifilament polyamide yarns is provided. Generally, monofilament yarns consist of one filament per yarn, while multifilament yarns consist of a plurality of monofilaments. The term “filament” is generally used herein and includes discontinuous fibers known as staples in the art. Polyamide filaments formed by melt spinning, extrusion through a die or spinneret capillary, are initially produced in the form of continuous filaments. The filaments thus produced have any desired cross-sectional shape, determined according to the cross-sectional shape of the capillary, and may include round, oval, trilobed, multilobed, ribbon and dog bone types. have.

Any meltspun polyamide can be used to make the filaments of the present invention. The polyamide may be a homopolymer, copolymer or terpolymer, or a mixture of polymers. Exemplary polyamides include polyhexamethylene adipamide (nylon 6,6); Polycaproamide (nylon 6); Polyenanthamide (nylon 7); Nylon 10; Polydodecanolactam (nylon 12); Polytetramethyleneadipamide (nylon 4,6); Polyhexamethylene sebacamide homopolymer (nylon 6,10); polyamides of n-dodecanediic acid and hexamethylenediamine homopolymers (nylon 6,12); And polyamides (nylon 12,12) of dodecamethylenediamine and n-dodecanediic acid. Methods of preparing polyamides for use in the present invention are known in the art and include the use of catalysts, promoters and chain branching agents to form polymers, as is known in the art. Preferably, the polymer is nylon 6, nylon 6,6 or a combination thereof. Most preferably, the polyamide is nylon 6,6.

In the process of the invention, the polymer melt is extruded through a spin pack to form one or more filaments. The spin pack may comprise spinneret plates with one, two or a plurality of holes (capillaries) per known art for forming one or more filaments. In a monofilament yarn embodiment, a single or monofilament forms a monofilament yarn, and in a multifilament yarn embodiment, a plurality of monofilaments form a multifilament yarn.

Examples of suitable air spinning methods and systems that can be used are described in US Pat. No. 5,824,248 and US Patent Application 09 / 547,854, filed Apr. 12, 2000. Any pneumatic method described above may also be used. A preferred filament air quench system for use in the present invention is shown schematically in FIG. 3. The assembly of FIG. 3 can be used as the quench chamber of FIG. 4 or 5. In FIG. 3, the polymer melt 300 is extruded through a filament spinning pack 305 and at least one, and preferably a spinneret plate 310 having a plurality of capillaries, to at least one, and preferably a plurality of filaments ( 315). One or more filaments pass through an air quench chamber 320 that is part of the air quench assembly. The air quench assembly comprises a heated or unheated quench delay section of height A; Quench screen section 345 of height B and diameter D ₁ ; Quench connection tube 355 of height C ₁ and diameter D ₂ ; Connecting taper 325 of height C ₂ ; And a quench tube of height C ₃ and diameter D ₃ . In the gas chamber, a quench gas is provided at 340 to cool and solidify the filament. Preferably, the filament passes through the quench chamber at a rate of less than 1500 meters / minute. The quench screen 345 surrounds the filaments in the quench chamber, and a perforated quench screen 350 can optionally be positioned next to the quench screen of the quench chamber. Filament and quench gas exit the quench chamber through quench tube 330. The just quenched yarn is indicated by 355.

At certain polymerization conditions, the filament size and throughput, the distance between the spinneret plate and the connecting taper, determine the location on the filament where the gas is accelerated and provides a quenching effect by air. The quench gas is moved in the same direction as that of the filament, as indicated by the arrow in FIG. 3. The quench gas velocity is adjusted relative to the filament velocity, which minimizes the aerodynamic drag force of the quench gas on the filament. This force generally acts more prominently at higher spinning speeds to dampen the filaments and impart undesirable early orientation to the membrane spun filaments. Filament orientation in the quench portion of the spinning process is undesirable because this orientation limits the final mechanical stretching of the available filaments. The decrease in aerodynamic drag experienced by the filament in the spinning process, which is quenched by gas, leads to lower orientation (measured by the birefringence of the filament).

The formation of polyamide yarn from filaments made according to the method of the invention is illustrated in FIGS. 4 and 5. As shown in FIG. 4, the polymer melt 400 is extruded through the spin pack 410 to form one or more and preferably a plurality of filaments 420. The spin pack 410 contains filtration media and multiple capillary spinneret plates. The membrane-extruded filament 420 is quenched by introducing quench air 440 into the quench chamber 430 in an air quench chamber 430 of the kind shown in FIG. The quench screen 435 surrounds the filament in FIG. 4.

In a multifilament yarn embodiment, the method of the present invention also includes converging the solidified filament into a multifilament yarn. The filament 420 exiting the quench chamber 430 converges into the seal 460 by a peak tail guide 455 located downstream of the filament finish application roll 450. Finish roll 450 is used to apply emulsions or other types of finishes known in the art.

The process of the present invention also includes passing the yarn through a mechanical drawing step in the case of a filament or multifilament yarn embodiment, and stretching and stretching the filament or yarn. The filaments are stretched in one or more, and generally in a number of stretching stages. This step is performed by the first draw roll pair 470 and the second draw roll pair 480 in the embodiment of FIG. 4. The feed roll assembly 465 transfers the treated seal 460 to a first draw roll pair 470 that is heated and driven at a higher speed than the feed roll 465 in the space between the rolls 465 and 470. Stretch the thread. The second heated draw roll pair 480 is driven at a higher surface speed than the roll 470 and further draws the yarn on the heated draw pin assembly or hot tube 475 as disclosed in US Pat. No. 4,880,961. do. Preferably, the filament or yarn passes the final stretching step at a speed of greater than about 2600 meters / minute, and even more preferably greater than about 4500 meters / minute. The draw ratio, defined as the ratio of roll surface speed (fastest roll / lowest speed roll), provides the polymer chain alignment (orientation) necessary to achieve high yarn strength or specific strength. Preferably, the filaments or yarns are drawn at a draw ratio of about 3 to about 6. The heat of the heated roll surfaces 470, 480 and the draw pin assembly 475 stabilizes the stretched (oriented) structure of the multifilament yarn. The yarn is decelerated between the rolls 480 and 482 and 485 to adjust the final yarn shrinkage.

The method of the present invention may also include winding the filament or yarn into a package. In the embodiment of FIG. 4, the yarn fully drawn to have the desired specific strength, shrinkage and other properties is wound on the package 495 which is rotated by the chuck of the winder not shown in FIG. 4. Guide 490 is used to adjust the thread path. Although not shown, a broken yarn detector is often used at this position to stop the winder in the event of yarn breakage. Optionally, a break filament detector is installed between the rolls 482 and 485 to signal the presence of undesired levels of filament breaks. If desired, it may be further applied prior to winding the second finish emulsion.

According to the invention, stretching may comprise stretching the filament in two or more steps. This embodiment is illustrated in FIG. 5. As shown in FIG. 5, the polymer melt 500 is extruded through the spin pack 510 to form one or more, and preferably a plurality of filaments 515. The spin pack 510 includes a filtration medium and multiple capillary spinneret plates. Membrane extruded filament 515 passes through air quench chamber 520 as shown, for example, in FIG. The membrane-extruded filament 515 is quenched by introducing a quench gas 525 into the quench chamber 520 in an air quench chamber 520 of the kind shown in FIG. 3. The filament 515 exiting the quench chamber 520 converges to the multifilament yarns by a guide 535 located downstream of the finish roll 530. A finish roll 530 is used to apply a finish emulsion of known type to the multifilament yarns. The feed roll assembly 540 transfers the treated multifilament yarn to a first draw roll pair 545 that is heated and driven at a higher speed than the feed roll 540 in the space between the roll 540 and the roll 545. Stretch the multifilament yarns. The second heated draw roll pair 550, driven at a higher surface speed than the roll 545, after the structure has stabilized on the heated surface of the draw roll, is used to provide sufficient orientation of the polymer molecules and to give strength to the seal. It extends further. An optional third draw roll pair 555 can further stretch the multifilament to further increase specific strength. This yarn is slowed in speed between the stretching roll 555 and the roll 560 to adjust the final yarn shrinkage. Often, quality is measured using a broken filament detector placed between rolls 555 and 560. The fully drawn yarn is wound on the package 570 to have the desired specific strength, shrinkage and other properties. Guide 565 is used to adjust the thread path. Although not shown, a broken yarn detector is often used at this position to stop the winder in the event of yarn breakage. Optionally, a break filament detector is used in this position to stop the thread break generator winder. If desired, it may be further applied prior to winding the second finish emulsion.

In the monofilament perspective embodiment, there is no step of converging the filaments into multifilaments as described above. Instead, the filaments in the form of monofilaments go directly to a coupled mechanical drawing step such as illustrated in FIG. 4 or 5. As a result, the monofilament is drawn, lengthened and oriented. The monofilament is then wound into a package as illustrated in FIG. 4 or 5.

The filaments made according to the invention are for example greater than 2,000 meters / minute, preferably greater than about 3,000 meters / minute, more preferably greater than about 4,000 meters / minute, most preferably greater than about 5,000 meters / minute, about It can radiate at a rate of up to 10,000 meters / minute. Herein, the spinning speed is defined as the surface speed of the fastest moving stretching roll relative to the surface speed of the stretching roll that the yarn contacts before winding up. At spinning speeds of about 2660 to about 5000 meters / minute, the rate ratio of the cooling gas at the outlet of the quench chamber to the first roll pulling the filament is about 0.6 to about 2.0. The first roll that pulls the filament is a supply roll, that is, roll set 465 of FIG. 4 or roll set 540 of FIG. 5. Preferably, the actual winding is performed at a winding speed reduced from the spinning speed by an amount of 0.1% to about 7% of the spinning speed.

In the present invention, high specific strength yarns are produced at high spinning rates at commercially desirable levels of elongation at break and shrinkage. In contrast, yarns made by methods using conventional methods using conventional crossflow quenching are accompanied by a loss of specific strength and elongation as the spinning speed increases. The shrinkage of the fibers produced by these conventional methods is also undesirably high. This is illustrated in FIG. 6, which shows that the maximum draw ratio achievable in conventional processes is lowered. This is because the number of filament breaks increases, and the process cannot be controlled. This also causes a decrease in specific intensity as illustrated in FIG. 7. The specific strength of the yarn is the result of the yarn's highly stretching. Thus, the maximum specific strength achieved in the prior art is low and uncontrollable at low spinning speeds (about 4000 meters / minute). 7 shows that about 10.8 g / denier yarns are obtained spun at 5500 meters / minute by the quenching means of the present invention, while in the prior art quench means the same yarn of 10.8 g / denier is obtained at only 3000 meters / minute. Shows. In this example the method of the present invention is 1.8 times more productive (5500/3000) than the prior art. The data in FIGS. 6 and 7 were obtained using the prior art of FIG. 1 without the hot tube 90. Instead, the yarn was moved from roll 80 to 100 without passing 90 which is not actually present. The rest of the real path is shown in FIG. 1.

Thus, at spinning rates ranging from about 2600 meters / minute to more than about 5000 meters / minute, the specific strength of the fully drawn yarns of the present invention is at least 5 grams / denier (4.5 cN / decectex), preferably about 5.7 grams. / Denier (5.0 cN / decitex), more preferably greater than about 7.9 grams / denier (7.0 cN / decitex), more preferably about 11.3 grams / denier (10 cN / decitex). .

In addition, the yarns of the present invention preferably have balanced properties such as elongation at break (15 to 22%) and hot air shrinkage (less than 10%, preferably less than 6%). In addition, the yarn of this invention has a denier distribution of less than 3.7%. In contrast, a yarn made by conventional methods using conventional cross flow quench involves loss of specific strength and elongation when seeking to increase the spinning speed. The shrinkage of the fibers produced by these conventional methods is also undesirably high. A good balance of these properties is required to meet the requirements of special polyamide fibers used in applications such as automotive air bags, reinforcement seals (e.g. tire seals) in hardened rubber, protective clothing, soft bags. In addition, low strength in combination with low elongation at break and high shrinkage means that the process is typically crude and of less than commercial quality.

Moreover, the filaments of the present invention may have a decitex (dtex / fil), for example 0.1 to about 20 dtex / fil, per any desired filament. Industrial filaments such as air bags and sewing threads are typically about 2.5 to about 9 dtex / fil. For apparel, the range of dtex / fil is typically 0.1 to 4, and for other applications (eg carpet), higher dtex / fil, for example about 5 to about 18 dtex / fil, is often useful. Do.

Prior to any mechanical stretching, the birefringence of the filaments of the present invention is from 0.002 to 0.012. As is known to those skilled in the art, filament birefringence indicates the relative degree of orientation of the polymer chains in the filament. This birefringence range achieved in the feed roll assembly with the air quench means of the present invention indicates that the molecular orientation is lower than the molecular orientation achieved using the cross-flow quench means of the prior art. This low orientation in the feed roll assembly enables even higher draw ratios without the occurrence of excessive filament breaks.

The filaments of the present invention are preferably polyamides formed from multifilament yarns, woven fabrics, staple fibers, textile molded articles, continuous filament tows and continuous filament yarns. Fabrics containing the filaments of the invention include industrial fabrics, carpets, garments, air bags, or other articles containing at least some polyamides used in sails and parachutes. When making a fabric, any known suitable method for making a fabric can be used. For example, weaving, warp knitting, circular knitting, hosiery knitting, and lamination of staple products into nonwovens are suitable for fabric production.

Polyamide filament yarns of the present invention can typically be used alone after spinning and stretching, or other polymeric synthetic fibers such as spandex, polyester and natural fibers such as cotton, silk, wool or other typical companion fibers to nylon and any purpose You can mix in an amount to say.

Yarns made according to the method of the present invention may have any desired filament count and total decitex. Yarns formed from the filaments of the present invention typically have a total decitex of about 10 decitex to about 990 decitex, preferably about 16 decitex to about 460 decitex. Moreover, the yarns of the present invention may also be formed from a plurality of different filaments that differ in dtex / fil range, cross section and / or other features per filament.

The polymer melts used in the process of the invention, and the resulting filaments, yarns and articles, may include conventional additives that may be added during the polymerization process or added to the formed polymer or article and contribute to improving polymer or fiber properties. Examples of such additives include antistatic agents, antioxidants, antibacterial agents, flame retardants, colored pigments, light stabilizers, polymerization catalysts and auxiliaries, adhesion promoters, deglossing particles such as titanium dioxide, matting agents, organic phosphates and their There is a blend of. Particularly preferred additives to the polymer melts of the present invention are depigmented particles and colored pigment particles such as titanium dioxide or zinc sulfide. Preferably, the polymer melt contains about 0.01 to about 1.2 weight percent colored or deglossed particles.

Other additives that may be applied on the fibers during the spinning and / or stretching process include antistatic agents, slickening agents, adhesion promoters, antioxidants, antibacterial agents, flame retardants, lubricants, and combinations thereof. Such additional additives may be added during various stages of the process as is known in the art.

The invention is further illustrated by the following non-limiting examples.

Test Methods

The properties used to characterize the filaments of the invention were measured in the following manner.

Specific strength was measured with an Instron Tensile Tester (ASTM D76) equipped with two grips that hold a thread at a gauge length of 10 inches (25.4 cm). After twisting the sample three times per inch (1.2 twists per cm), the yarn was pulled at a strain rate of 10 inches / minute (25.4 c meter / minute). The load cell recorded the data and a stress-strain curve was obtained. Specific strength is the break load divided by the real denier and is expressed in grams / denier or cN / dtex (cN / dtex = grams / denier × (100/102) × (9/10)). Elongation at break, expressed as a percentage, is the change in sample length at break divided by its original length. Instron measurements were performed at 21 ° C. (± 1 ° C.) and 65% relative humidity. Denier is the linear density of the sample obtained by measuring the weight in grams over 9000 m length (decetitex is the denier multiplied by a factor 10/9). Specific strength and elongation measurement methods were generally in accordance with ASTM D2256.

The uniformity of yarn linear density (expressed in denier or decitex) was determined by repeatedly measuring the weight of the yarn of a particular length and comparing the representative number of samples. The linear density of the yarn was measured by the "cut and weigh" method known to those skilled in the art. In this method, a yarn of a certain length (L), for example 30 meters of yarn, was cut from the yarn package and its weight was measured. The weight (W) of the real sample is expressed in grams. The weight-to-length ratio (W / L) was multiplied by 9000 meters of yarn, expressed as denier. Alternatively, W / L was multiplied by 10,000 meters of yarn, expressed in decitex. The process of cleavage and weighing was typically repeated eight times. The average value of eight measurements from a single yarn package is expressed as "single yarn" denier uniformity. An automatic test device ACW400 / DVA was obtained from Lenzing Technology (LENZING TECHNIK, GmbH & Co. KG, Austria) for this measurement. The ACW400 / DVA instrument was a fully automatic measurement system for filament yarn uniformity and denier / dtex according to cutting and gravimetric methods. Lenzing Tech's ACW400 / DVA instrument included a Denier Deviation Accessory (DVA) that automatically measures denier deviations, known in the art as "denier spread." Denier distribution measurements herein are based entirely on the method provided by Lenzing Technician for the Denier Deviation accessory module for ACW400.

The polymer relative viscosity (RV), melting point, and water content in the formic acid solution were measured using a standard method according to ASTM D789.

ASTM test method D5104-96 was the standard method for single filament shrinkage (single fiber test) used herein.

The birefringence of the individual filaments was measured using polarization microscopy and tilt compensator techniques. Equation 1 defines birefringence.

The thickness of the fibers was measured using a Watson Image Sheering Eyepiece and a microscope. Images of the measured fibers were sheared from one side to the other and tested for thickness. Retardation was measured by cutting a 45 ° wedge at one end of the fiber. The degree of interference or retardation bands was counted as they propagate from the thinnest end of the wedge to the thickest part of the wedge or the center of the fiber. Measurements were made in a cross polarizer with a quarter wave plate inserted in the optical path such that the fibers were aligned vertically with respect to the retardation direction of the quarter wave plate (one quarter of the 546 nanometer wavelength). When counting each phase difference band, part of the band appearing in the center of the fiber had to be corrected using an analyzer. The analyzer was rotated and the angle recorded until the center band was calibrated. The angle (less than 180 °) represents part of the phase difference band (at 546 nanometers). The total number of phase difference bands and the last portion measured with the analyzer were converted to path difference (nm).

Alternatively, the same birefringence data can be obtained using the Senarmont compensation method described in detail in columns 5 and 6 starting from column 5, line 23 of US Pat. No. 5,141,700 (Sze). there was. In essence, the birefringence method required the measurement of the path difference between two wavelengths of polarization associated with the birefringent filaments. This path difference divided by the filament diameter (micrometer) is the definition of birefringence.

Comparative Example A

Nylon 6,6 polymer flakes (relative viscosity 38) commercially available from DuPont (Canada) were polymerized in solid phase in dry nitrogen in the absence of oxygen to increase polymer molecular weight. The polymer was transferred to a screw-melt and extruded. The molten polymer was then introduced into a filament spinning pack, filtered and extruded into a spinning die (or spinneret) with 34 capillaries. The spinneret allowed the formation of 34 individual filaments. These filaments were quenched in air using the crossflow quench and coupled spin-drawing apparatus shown in FIG. 1. The filaments converged into one yarn and applied with a conventional finish lubricant and then transferred to a feed roll assembly 70 having a roll surface speed of 651 meters / minute and a roll surface temperature of 50 ° C. The yarn was then fed to a first stretched roll pair 80 with a roll surface temperature of 170 ° C. and a surface speed of 2.6 times the feed roll speed. The yarn was then fed to a second draw roll pair 100, which had a surface temperature of 215 ° C. and provided an overall speed of 2800 meters / minute corresponding to a draw ratio of 4.3 times the feed roll speed. The hot tube 90 was not used in this comparative example. The speed of 34-filament yarn was slowed 7.1% on the puller rolls 110 and 120 and then wound up into the seal package 140 at a rate of 2587 meters / minute. The resulting 110-denier yarn (34 filaments) had a specific strength of 8.8 grams / denier (7.8 cN / dtex), an elongation at break of 18%, and a hot air shrinkage of 6.6%. The relative viscosity (RV) of the measured yarn was 70.

Example 1

The same nylon 6,6 polymer flakes as used in Comparative Example A were melt extruded and processed in the same manner as Comparative Example A before entering the spin pack 400 shown in FIG. The polymer was extruded through the spinneret to form 34 filaments. The membrane extruded filaments were quenched in air using the air quench apparatus shown in FIG. 3 and the coupled multistage stretch roll assembly shown in FIG. 4. Hot tube 475 (FIG. 4) was not used.

Referring to FIG. 3, the quench screen 345 had a diameter (D ₁ ) of 4.0 inches (10.2 cm) and a quench screen length (B) of 6.5 inches (16.5 cm); The quench delay height (A) was 6.6 inches (16.8 cm); The quench connection tube 355 height (C ₁ ) was 5.0 inches (12.7 cm); The quench connection tube diameter (D ₂ ) was 1.5 inches (3.8 cm); The connection taper 325 height (C ₂ ) was 4.8 inches (12.2 cm); Tube 330 height (C ₃ ) was 15 inches (38 cm).

The ratio of air velocity to feed roll 465 (FIG. 4) velocity, obtained from Equation 2, was 1.02 feet / minute (31 cm / minute).

Here, the tube 330 (FIG. 3) the air velocity at the outlet is the same as that obtained by dividing the measured volumetric air flow rate to the tube 330, or the cross-sectional area ^{_{π (D 3) 2/4}} . This ratio is then corrected for the decrease in air density with rising bulk air temperature in the air quench apparatus.

The finish is applied at 450 (FIG. 4) and the filaments are converged into the yarns using a pigtail guide 455 located downstream of the finish roll 450. This yarn was transferred to the first draw roll pair 470 by the feed roll assembly 465. The feed roll assembly 465 had a surface speed of 1087 meters / minute and a surface temperature of 50 ° C. The first stretch roll pair 470 had a roll surface temperature of 170 ° C. The surface speed was 3.2 times the feed roll speed.

The filament was then moved to the second draw roll pair 480 via a hot tube 475 not used in this example. The stretching roll 480 provided a total draw ratio of 4.6 at a surface temperature of 212 ° C. and a surface speed of 5000 meters / minute. The total draw ratio is calculated by dividing the draw roll 480 surface speed by the feed roll 465 surface speed. The speed of 34-filament yarn was slowed down to 7.4% at 485 and wound up at a speed of 4600 meters / minute. The obtained 110-denier yarn had a specific strength of 9.1 g / denier (8.0 cN / dex), an elongation at break of 20.6%, and a hot air shrinkage rate of 6.7%. The measured RV of the yarn was 70.

Example 2

Using the spinning machine arrangement of FIG. 4, the same nylon 6,6 polymer flakes as used in Comparative Example A were processed, melt extruded, transferred to a spinning pack 410 and extruded through a spinneret to form 34 filaments. . The membrane extruded filament 420 was quenched in air according to the present invention using the air quench apparatus shown in FIG. The coupled multi-step stretch roll assembly and hot tube 475 process shown in FIG. 4 was used. Referring to Figure 3, the quench screen 345 was 4.0 inches (10.2 cm) in diameter and the quench screen length (B) was 8.1 inches (20.6 cm); The quench delay height (A) was 6.6 inches (16.8 cm); The height C ₁ of the quench connection tube 355 was 5.0 inches (12.7 cm); The connecting tube 355 diameter D ₂ was 1.5 inches (3.8 cm); The connection taper 325 height (C ₂ ) was 4.8 inches (12.2 cm); The tube height (C ₃ ) of the quench tube 330 was 15 inches (38 cm); The ratio of air velocity to the feed roll assembly was 1.05. The filaments converged into the yarn at 455 while applying the finish lubricant at 450. This yarn 460 was transferred by the feed roll assembly 465 to the first draw roll pair 470. The feed roll assembly 465 had a surface speed of 1064 meters / minute and a surface temperature of 50 ° C. The first stretch roll pair 470 had a roll surface at ambient temperature, and the surface speed was 2.7 times the feed roll speed.

The filaments were then contacted with the same hot tube 475 as the hot tube disclosed in US Pat. No. 4,880,961. The yarn was spirally transferred into frictional contact with the hot tube by wrapping around 1½ around the internally heated hot tube. The surface temperature of the hot tube 475, the stretching aid element, was 181 ° C. The yarn was then transferred to a second stretched roll pair 480 having a roll surface temperature of 215 ° C. The total draw ratio was 4.7 times the feed roll 465 speed, and the second draw roll assembly 480 had a surface speed of 5000 meters / minute. The speed of the filament yarn was reduced by 7.0% in the reduction roll assembly 485 and wound into the seal package 495 at a speed of 4615 meters / minute. The drawn 110 denier (122 dtex-34 filament) yarn had a specific strength of 9.8 g / denier (8.6 cN / dtex), an elongation at break of 16.3%, and a hot air shrinkage of 7.3%. The measured RV in the formic acid of the yarn was 70.

Example 3

Titanium dioxide (HOMBITAN® LO-CR-SM, Sachtleben Chemie GmbH, Duisburg, Germany) containing 1% by weight of anatase form RV nylon 6,6 polymer flakes were melt extruded and processed in the same manner as in Example 2 using the coupled extrusion and stretching apparatus shown in FIG. 4. 34 filaments were formed using the same spin pack and spinneret. The membrane-extruded filaments were quenched in air using the air quenching device shown in FIG. The dimensions of the air quenching device were the same as in Example 2. The ratio of the air velocity in the tube 330 to the feed roll assembly 465 velocity was 1.1. As in the foregoing embodiment, the filaments were converged to the yarns by the guide 455 while applying the finish lubricant at 450. The feed roll assembly 465 transferred the yarn to the first draw roll pair 470. Feed roll 465 had a surface speed of 1087 meters / minute and a roll surface temperature of 50 ° C. The first stretch roll pair 470 had a roll surface at ambient temperature and a surface speed of 2.7 times the feed roll speed. The yarn was transferred to a hot tube as in Example 2. The yarn was spirally transferred into frictional contact with the hot tube by wrapping around 1½ around the internally heated hot tube. The surface temperature of the hot tube 475, the stretching aid element, was 181 ° C. The yarn was then advanced to a second draw roll pair 480 having a roll surface temperature of 215 ° C. and a surface speed of 5000 meters / minute, giving a total draw ratio of 4.6 times the feed roll speed. The speed of the 34 filament yarns was reduced by 6.5% using the reduction roll assembly 485 and wound up at a rate of 4645 meters / minute to form a package 495. The resulting 110 denier (122 dtex-34 filament) yarn had a specific strength of 8.7 g / denier (7.7 cN / dtex), an elongation at break of 17.6%, and a hot air shrinkage of 7.1%. The measured RV in the formic acid of the yarn was 78.

Comparative Example B

The same 38 RV nylon 6,6 polymer flakes as used in Example 1 were melt extruded using the coupled spinning and multistage stretching apparatus of FIG. 1. The spinning pack 20 had a spinneret with 34 capillaries and spun 34 filaments. The fineness of each filament was 6 denier (6.6 dtex) after multi-step stretching. The filament (30 in FIG. 1) was cooled and solidified using a cross flow of quench air 40 according to known methods of the prior art. The filaments converged into the yarn while applying the finish lubricant at (50). The yarn 60 was transferred to the first draw roll pair 80 by a feed roll assembly 70 having a roll surface temperature of 50 ° C. and a circumferential speed of 560 meters / minute. The first stretch roll pair 80 had a roll surface temperature of 170 ° C. and a surface speed of 3.0 times the feed roll speed. Hot tube 90 was not used. The yarn was then fed to a second draw roll pair 100 having a roll surface temperature of 215 ° C. to provide a total draw ratio of 2800 meters / minute or five times the feed roll speed. The speed of the 34 filament yarns was reduced by 8.0% and wound up at a speed of 2562 meters / minute. The stretched 210 denier (233 dtex) yarn had a specific strength of 9.4 g / denier (8.3 cN / dtex), an elongation at break of 17.5%, and a hot air shrinkage of 6.7%. The formic acid RV of the measured yarn was 70.

Example 4

Using a coupled spinning and stretching device (without hot tube 475) quenched with air of FIG. 4, the nylon 6,6 polymer was processed in the same manner as Comparative Example A before the spinning pack and melted through the spinneret. Extruded to form 34 filaments. The membrane extruded filaments were quenched in air using the air quench apparatus of the present invention shown in FIG. 3 and the coupled multistage stretching roll assembly shown in FIG. 4.

Referring to FIG. 3, the quench screen 345 was 4.0 inches (10.2 cm) in diameter and the quench height (B) was 6.5 inches (16.5 cm); The quench delay height (A) was 6.6 inches (16.8 cm); The height C ₁ of the quench connection tube 355 was 12.5 inches (31.7 cm); The connecting tube had a diameter (D ₂ ) of 1.5 inches (3.8 cm); The height C ₂ of the connection taper 325 was 4.8 inches (12.2 cm); The height C ₃ of the quench tube 330 was 15 inches (38 cm). The ratio of air velocity in the quench tube 330 to the feed roll assembly 465 was 0.87.

The filament 420 converged to the yarn at 455 while applying the finish lubricant at 450. The yarn 460 was transferred by the feed roll 465 to the first draw roll pair 470. The feed roll had a roll surface temperature of 50 ° C. and a circumferential speed of 1042 meters / minute. The first stretch roll pair 470 had a roll surface temperature of 170 ° C. and a surface speed of 2.8 times the feed roll speed. The yarn was then fed to a second stretched roll pair 480 having a roll surface temperature of 220 ° C. via hot tube 475. The second draw roll 480 provided a total draw ratio of 5000 meters / minute or 4.8 times the feed roll speed. The speed of the 34-filament yarn was reduced by 7.0% by the reduction roll assembly 485 and wound up at a speed of 4620 meters / minute. After stretching, the 210-denier (233 dtex-34 filament) yarn had a specific strength of 10.0 g / denier (8.8 cN / dex), an elongation at break of 17.9%, and a hot air shrinkage of 6.8%. The measured RV in the formic acid of the yarn was 70.

Example 5

Using the air quenched coupled spinning and stretching device of FIG. 4 with a hot tube (stretch aid element 475), the nylon 6,6 polymer was processed in the same manner as in Comparative Example A before the spinning pack, Melt extrusion through the spinneret formed 34 filaments. The membrane extruded filaments were quenched in air using the inventive air quench apparatus shown in FIG. 3 and the coupled multistage stretch roll assembly shown in FIG. 4.

Referring to FIG. 3, the quench screen 345 was 4.0 inches (10.2 cm) in diameter and the quench height (B) was 6.5 inches (16.5 cm); The quench delay height (A) was 6.6 inches (16.8 cm); The height C ₁ of the quench connection tube 355 was 12.5 inches (31.7 cm); The connecting tube had a diameter (D ₂ ) of 1.5 inches (3.8 cm); The height C ₂ of the connection taper 325 was 4.8 inches (12.2 cm); The height C ₃ of the quench tube 330 was 15 inches (38 cm). The ratio of air velocity in the quench tube 330 to the feed roll assembly 465 was 1.12.

While applying the finish lubricant at 450, the filaments converged to the yarns at the guide 455. The yarn was transferred to the first draw roll pair 470 by the feed roll assembly 465 and then to the draw aid element 475. The feed roll assembly 465 had a roll surface temperature of 50 ° C. and a circumferential speed of 1087 meters / minute. The first stretch roll pair 470 had a roll surface at ambient temperature and a surface speed of 2.8 times the feed roll speed. The yarn was then spirally transferred into frictional contact with the draw aid element 475 wrapped in an internally heated hot tube. The surface temperature of the stretching aid element 475 was 181 ° C.

The yarn was then transferred to a second draw roll pair 480 with a roll surface temperature of 215 ° C. to provide a total draw ratio of about 5000 meters / minute or five times the feed roll speed. The speed of the 34-filament yarn was reduced by 6.5% with the reduction roll assembly 485 and wound up into the seal package 495 at a speed of 4630 meters / minute. After stretching, the resulting 210-denier (233 dtex-34 filament) yarn had a specific strength of 9.9 g / denier (8.7 cN / dex), an elongation at break of 18%, and a hot air shrinkage of 7.9%. The measured RV in the formic acid of the yarn was 70.

Comparative Example C

60 RV nylon 6,6 polymer flakes containing about 0.1% copper iodide (Source: EIdu Pont de Nemours, Waynesboro, Va.) Were dried as in Comparative Example A. And melt extrusion was carried out. In this comparative example, a melt extrusion and coupled multi-stage stretching assembly using a cross-flow quench system (230 of FIG. 2) of the prior art was used. The spinning die (containing the spinning pack 210) had 34 capillaries. 34 filament multi-filament yarns were prepared. The yarns were tanned at 240, converged to the yarns and transferred by feed roll 260 with a surface temperature of 60 ° C. The first stage stretching roll pair 270 surface temperature was 170 ° C. The second stage stretching roll pair 275 surface temperature was 215 ° C. The optional stretch roll assembly 280 of FIG. 2 was not used. The yarn spinning speed was determined by the surface speed of the roll assembly 275. 6 nominal denier (6.7 dtex) / filament yarns are produced at three different spinning speeds, and three maximum draw ratios (roll (275) speed divided by roll (260) speed) and the rate of deceleration of the associated spinning speed Provided by a roll assembly 285 and a winder 295. The measured formic acid RV was 60. Table 1 shows the specific strength and elongation at break in each spinning rate experiment.

These values in Table 1 correspond to the limitations of prior art cross flow quenching. It is well illustrated that the maximum draw ratio available is reduced without major process interruptions, for example, high rates of filament breakage as the spinning speed increases. Since high draw ratios cannot be used, the specific strength of the achievable yarn is lowered as the spinning speed increases.

Comparative Example C Spinning Speed (Surface Speed of Roll 275 in Figure 2; Meter / Min) 2660 3660 4655 Draw ratio (speed of (275) / speed of (260)) 5.5 4.5 2.5 Specific strength, g / denier (cN / dtex) 8.9 (7.8) 8.5 (7.5) 6.6 (5.8) Elongation at Break,% 15.0 14.9 19.6 Deceleration of Roll 285,% 6.6 5.2 0.1

Example 6

60 RV nylon 6,6 polymer flakes containing about 0.1% copper iodide (Source: EIdu Pont de Nemours, Waynesboro, Va.) Were dried as in Comparative Example A. And melt extrusion was carried out. The filament of 34 filaments was spun and stretched using the melt extrusion and coupled multistage stretch assembly of FIG. 5 using the air quench system illustrated in FIG. 3. The spinning die included in the spinning pack 510 had 34 capillaries. An air quench assembly with the dimensions given in Table 2 was used (Figure 3). After air quenching the filaments were tanned at 530 and converged into multi-filament yarns in the pigtail guide 535. The yarn was passed through a two stage stretch roll assembly by a feed roll assembly 540 having a surface temperature of 60 ° C. The first stage stretching roll 545 surface temperature was 170 ° C, and the second stage stretching roll 550 surface temperature was 215 ° C. 210-denier (233 dtex-34 filament) yarns were prepared using three different spinning speeds. The total draw ratio was the same as the speed of the roll 550 divided by the speed of the roll 540, and the deceleration rate of the speed in the winder is shown in Table 2. The measured RV in the formic acid of the yarn was 60.

Table 2 shows the specific strength and elongation at break of each spinning rate test. As in Comparative Example C, the draw ratio is the maximum draw ratio allowed by process continuity, eg, excessive filament break.

Example 6 Spinning Speed (Roll Assembly 550 of Figure 5) 2660 m / min 3660 m / min 4660 m / min A, quench delay height 20.3 cm 20.3 cm 20.3 cm B, quench screen height 15.2 cm 15.2 cm 15.2 cm C ₁ , connecting tube height 20.3 cm 20.3 cm 20.3 cm C ₂ , connection taper height 12.2 cm 12.2 cm 12.2 cm C ₃ , tube height 38.1 cm 38.1 cm 38.1 cm D ₁ , quench screen diameter 10.2 cm 10.2 cm 10.2 cm D ₃ , tube diameter of 1.5 inches (3.8 cm) 3.8 cm 3.8 cm 3.8 cm Ratio of air speed to feed roll 540 speed (Equation 1) 0.97 1.1 0.88 Draw Ratio Roll (550) Speed / Roll (540) Speed 5.8 5.5 4.7 Specific strength, g / denier (cN / dtex) 9.5 (8.4) 9.3 (8.2) 8.6 (7.6) Elongation at break,% 16.2 15.2 17.3 Deceleration, Speed Change% of Roll 560 from Roll 550 6.4 5.5 0.9

Example 6, an air quenched coupled spin-stretch system for producing highly drawn yarns, dramatically demonstrates the effect of the air quench spinning process on the prior art of cross-flow quenching of Comparative Example C. At the two lowest spinning speeds used, 2660 and 3660 m / min, the actual specific strength and elongation at break in cross-flow quench (Table 1) and air quench (Table 2) are different. This difference is due to the fact that the air quenched yarn is drawn to a higher draw ratio without filament spin rupture, ie loss of process continuity.

The crossflow quenched yarn (Table 1) could be stretched to a lower degree at 3660 m / min, because filament breaks interfered with spin continuity. Compared at the maximum spinning speed of 4660 m / min (see Tables 1 and 2), higher draw ratios without filament breakage could be used for air quenching. This draw ratio made it possible to produce high specific strength yarns as compared to yarn spinning using a crossflow quench assembly.

Comparative Example D

Dry a piece of 60 RV nylon 6,6 polymer of IAI DuPont Di Nemoir & Campani, Waynesboro, Va., Containing about 0.1% copper iodide antioxidant and use a cross-flow quench system of the prior art Melt extrusion was performed using a spinner as shown in FIG. 2. The spin pack 210 included a spinneret with 34 holes. The feed roll 260 surface temperature was as ambient. The first stage stretching roll 270 and the second stage stretching roll 275 were not used. Seals were collected from feed roll assembly 260 immediately after transfer. Four yarns were made using four different feed roll spinning rates and four different mass flow throughputs per spin orifice per minute. Their production kept the filament denier at the feed roll constant at all speed and throughput combinations. Did not stretch the thread. The RV in formic acid of the measured measured yarn spun was 60. The birefringence was measured on the yarn sample.

Example 7

The same polymer as Comparative Example D was extruded with the coupled spin-stretched filament spinner of the present invention as shown in FIG. 5. The experimental conditions of Comparative Example D were used except that the quench means was changed from cross flow to air quench (as in FIG. 3). The air quenched 34 filament yarns were collected immediately after the feed roll assembly 540. The birefringence of the yarn produced under four conditions of the same feed roll speed and mass throughput per spinning orifice as used in Comparative Example D was measured. This result is provided in Table 3.

The results provided in Table 3 comparing Example 7 of the present invention to Comparative Example D clearly demonstrate the advantage of filament air quenching over the cross-flow quench system of the prior art. In Comparative Example D, the birefringence of the filaments measured at the feed roll is higher for each rate and polymer throughput than the birefringence measured for air quench under the same conditions. The birefringence of the air quenched yarn indicates less oriented polymers, ie polymers that can be stretched and more highly oriented. Stretched yarns of more highly oriented polymers may have higher specific strength and lower elongation at break than stretched yarns of less oriented polymers. The air quenched filaments collected at the feed rolls have a consistently lower birefringence than the cross flow quenched filaments. In fact, the air quenched filaments collected at the highest spinning speed have only about 18% higher birefringence than the birefringence of the crossflow quenched yarn collected at the lowest spinning speed. Since the air quenched filaments are less oriented in the quench process, higher productivity spinning and mechanical stretching processes may be possible using air quench even at high spinning speeds.

Throughput Per Orifice (g / min) Feed roll speed (m / min) Comparative Example D Birefringence for Cross Flow Quenching Example 7 Birefringence for Air Quenching 1.69 532 0.00975 0.00211 2.32 732 0.01323 0.00448 3.05 960 0.01688 0.01027 3.81 1200 0.01982 0.01152

Comparative Example E

Dry a piece of 60 RV nylon 6,6 polymer from IAI DuPont D. Nemoir & Co., Waynesboro, VA, USA, containing about 0.1% copper iodide antioxidant, It was melt extruded as in the previous example with a spinner having two combined drawing stages as shown in FIG. 2. The cross-flow quench means of the prior art was used. The spin pack included a spinneret with 34 holes and made 34 filament yarns. The yarn 250 was transferred to a feed roll 260 having a surface temperature of 60 ° C. The surface temperature of the first stage stretching roll 270 was 170 ° C, and the surface temperature of the second stage stretching roll 275 was 215 ° C. Nominal denier of 210 (233 dtex-34 filaments) using three different spinning speeds (speed of draw roll assembly 275) and total draw ratio (ratio of roll 275 divided by speed of feed roll 260) ) Yarns were prepared. The measured RV in the formic acid of the yarn was 60. Actual specific strengths for each spin rate test are provided in Table 4.

Comparative Example F

The same 60 RV nylon 6,6 polymer pieces as in Comparative Example E were dried and melt extruded with a spinning machine having three combined draw steps as shown in FIG. 2. The same prior art cross flow quench system was used. The surface temperature of the feed roll 260 was 60 degreeC. The surface temperatures of the first stage stretching roll 270, the second stage stretching roll 275, and the third stage stretching roll 280 were 170 ° C., 230 ° C., and 230 ° C., respectively. The spinning die contained in the spinning pack 210 has 34 holes, with three different spinning speeds (maximum speed of the draw roll 280) and total draw ratio (speed of the roll 280 at the speed of the feed roll 260). 34 filament yarn (210 denier or 233 dtex-34 filament) was made using the divided ratio. The measured RV in the formic acid of the yarn was 60. Actual specific strengths for each spin rate test are provided in Table 4.

Spinning speed2660 m / min Specific strength g / denier (cN / dtex) Spinning speed3660 m / min Specific strength g / denier (cN / dtex) Spinning speed4660 m / min Specific strength g / denier (cN / dtex) Comparative Example E Cross Flow; Stretch in Two Steps Elongation Ratio = 5.5 9.5 (8.4) Elongation Ratio = 4.3 8.6 (7.6) Elongation Ratio = 2.6 6.0 (5.3) Comparative Example F Cross Flow; Three Stages of Stretching Elongation Ratio = 5.5 9.5 (8.4) Elongation Ratio = 4.7 8.8 (7.8) Elongation Ratio = 3.0 7.7 (6.8)

Example 8

In this embodiment of the invention, the same 60 RV nylon 6,6 polymer piece as used in Comparative Examples E and F is dried and the air quench illustrated in FIG. 3 with the coupled spin-stretch machine illustrated in FIG. The melt extrusion was carried out using the system. Only two stretching steps were used, and roll assembly 555 was bypassed. The spinning die included in the spinning pack 510 had 34 holes. Filament 515 was emulsified in fiber finish roll 530 and converged to 34 filament yarns in pigtail guide 535. This yarn was transferred to a pair of drawing stages joined by a feed roll 540 operating at a surface temperature of 60 ° C. The surface temperatures of the first stage stretching roll 545 and the second stage stretching roll 550 were 170 ° C and 215 ° C, respectively. Three 210 denier 233 at three different spinning speeds (spinning speed is the speed of roll assembly 550) and total draw ratio (total draw ratio divided by the speed of roll 550 by the speed of feed roll 540) dtex-34 filament) yarn was prepared. The yarn was slowed down at the same rate as the speed difference between the roll assemblies 560 and 550 divided by the speed of the roll assembly 550. The RV in the formic acid of the measured yarn was 60.

Physical properties for each spinning speed test are provided in Table 5.

Example 9

Example 8 was repeated using the apparatus of FIG. 5 and the draw roll in three stages (including roll assembly 555), using the same polymer and spinning die. The surface temperatures of the first stage stretching roll 545, the second stage stretching roll 550, and the third stage stretching roll 555 were 170 ° C., 230 ° C., and 230 ° C., respectively. Three 210 denier (233 dtex) at three different spinning speeds (spinning speed is the speed of roll assembly 550) and total draw ratio (total draw ratio divided by the speed of roll 555 by the speed of roll 540) 34 filament) yarn was prepared. The yarn was decelerated at the same speed as the speed difference between the roll assemblies 560 and 555 divided by the speed of the roll assembly 555. The measured RV in the formic acid of the yarn was 60.

Physical properties for each spinning speed test are provided in Table 5.

Spinning speed2660 m / min Specific strength g / denier (cN / dtex) Spinning speed3660 m / min Specific strength g / denier (cN / dtex) Spinning speed4660 m / min Specific strength g / denier (cN / dtex) Comparative Example E Cross Flow; Stretch in Two Steps Elongation Ratio = 6.0 9.6 (8.5) Elongation Ratio = 5.2 9.2 (8.1) Elongation Ratio = 4.8 8.3 (7.3) Comparative Example F Cross Flow; Three Stages of Stretching Elongation Ratio = 6.4 10.7 (9.4) Elongation Ratio = 5.8 9.9 (8.7) Elongation Ratio = 5.2 9.3 (8.2)

The data in Tables 4 and 5 show the better productivity achievable with air quench systems and coupled spin-stretch means compared to prior art cross-flow quench systems with coupled spin-stretch processes. As a result, to produce high strength polyamide filament yarns, crossflow quenching, regardless of the number of stretching stages, allows the use of faster overall spinning speeds with a total draw ratio that was impossible due to an increase in the number of broken filaments.

Example 10

The coupled spin-drawing apparatus of FIG. 4 used a draw roll in two steps in this example and no hot tube 475. DuPont Canada's 70RV nylon 6,6 polymer was melt extruded into a spin pack 410 with 34 capillary spinneret plates. 34 filaments were quenched with air by the apparatus schematically shown in FIG. 3. These filaments were tanned at 450 and collected into 34 filament yarns at the pigtail guide 455. This filament yarn was transferred by a feed roll assembly 465 to two stages of coupled stretching using the draw roll assemblies 470 and 480 and passing through the hot tube 475. Spinning speed (speed of spinning roll assembly 480 at the highest speed) was varied from 2660 meters / minute to 6000 meters / minute as shown in Table 6. The temperature of the feed roll assembly 465, the 1st draw roll 470, and the 2nd draw roll 480 was 50 degreeC, 170 degreeC, and 215 degreeC, respectively. The draw ratio was the ratio of the surface speed of the roll assembly 480 to the surface speed of the roll assembly 465. The reduction amount was calculated by dividing the surface speed difference between the roll assemblies 480 and 485 by the surface speed of the roll assembly 480. Tried at reduced polymer throughput at 5000 meters / minute and 6000 meters / minute to provide 110 deniers (122 dtex-34 filaments) instead of 210 deniers (233 dtex-34 filaments) provided at low spinning speeds. The yarn was decelerated (decelerated) by the roll assembly 485 before winding onto the seal package 495. An exception to the yarn package winding was the yarn spinning at 6000 meters / minute. These yarns were aspirated into a known yarn stirring mechanism without being wound up.

Table 6 summarizes the properties of the five air quenched and drawn yarn samples produced.

In a comparative example performed with the same polymer used in Example 10 of the present invention, the drawn yarn was passed through a hot tube 90 using a prior art cross-flow quench means having a coupled two-stage stretching roll assembly shown in FIG. It was prepared by. The spinning die has 34 holes as before. The filaments were tanned at 50 and gathered into 34 filament yarns. This yarn was transferred by the feed roll assembly 70 to the two stages of coupled stretching using the draw roll assemblies 80 and 100 and through the hot tube 90. Spinning speed (speed of the maximum speed stretching roll assembly 100) was varied from 2660 meters / minute to 4200 meters / minute as shown in Table 6. The draw ratio was the ratio of the surface speed of the draw roll assembly 100 to the surface speed of the feed roll assembly 70. The temperature of the feed roll assembly 70, the 1st stage stretching roll 80, and the 2nd stage stretching roll 100 was 50 degreeC, 170 degreeC, and 215 degreeC, respectively. The deceleration amount was calculated by dividing the difference between the roll assemblies 120 and 100 by the speed of the assembly 100. After the speed was reduced using the roll assembly 120, 210 denier (233 dtex) yarn was wound around the seal package 140.

Table 6 summarizes the characteristics of the three crossflow quenched and drawn yarn samples produced.

Quenching gas means Spinning Speed (m / min) Ratio of air speed to feed roll speed (Equation 1) Thread denier after stretching (34 filaments) Specific strength g / denier (cN / dtex) and elongation at break Stretch ratio (maximum) Deceleration at let down roll 120 Cross flow 2660 ... 210 10.6 (9.3) 15.1% 5.6 6.5% Cross flow 3660 ... 210 9.6 (8.5) 17.5% 4.8 3.3% Cross flow 4200 ... 210 8.8 (7.8) 19.9% 3.6 2.6% air 2660 ^* 1.20 210 10.4 (9.2) 17.3% 6.0 6.5% air 3660 ^* 1.00 210 11.2 (9.9) 15.0% 6.0 4.4% air 4200 ^* 1.05 210 10.6 (9.4) 16.3% 5.6 2.6% air 5000 ^** 0.88 110 10.2 (9.0) 12.9% 5.6 3.4% air 6000 ^** 1.12 110 ... 5.6 ...

^* Here, quenching the screen is the height (B) 6.5 inchi (16.5 cm)), the diameter (D ₁₎ is 4 inches (10.2 cm), and; Quench connection height (A) is 6 inches (15.2 cm); Quench connection tube height C ₁ is 12.5 inches (31.8 cm); The connecting tube diameter (D ₃ ) is 1.5 inches (3.8 cm) and the connecting taper height (C ₂ ) is 4.8 inches (12.2 cm); Tube height C ₃ is 15 inches (38 cm).

^{** All} these variables are the same except in these two cases that the quench connection tube height C ₁ is 5 inches (12.7 cm).

These results in Table 6 show that the process of the present invention can be used at spinning speeds of about 6000 meters / minute. Prior art coupled spin-drawing processes using cross-flow quench means, at only about 4200 meters / minute, had excessive spinning failures, which did not provide good spinning continuity. At a spinning rate of 5000 meters / min, the air quench coupled spin-drawing process provided a high strength (9.0 cN / dtex) seal using a mechanical elongation of only 5.6. Prior art means could provide a yarn of approximately the same strength at a spinning speed of 2660 meters / minute, but the maximum total draw ratio required was 6.6. These 233 dtex, 34 filament yarns are substantially uniform and even in properties. However, the coupled spin-drawing process of the present invention provided yarn with about 88% improved productivity. This productivity improvement is obviously a commercial advantage and is superior to prior art processes. These embodiments provide higher spinning speeds and higher total draw ratios, while air quench means combined with coupled multi-stage stretching processes retain the high strength and elongation at break characteristics of the seals that cannot be achieved using cross-flow quench means. To enable it.

Comparative Example G

In another comparative experiment conducted with the same polymer used in Example 10 of the present invention, the drawn yarn was made using prior art cross-flow quench means with the two stage coupled draw roll assembly of FIG. 1.

The hot tubes 90 were passed through here and were drawn in two stages of coupled stretching using the roll assemblies 80 and 100. Spinning speed (surface speed of roll 100) was 2800 meters / minute and total draw ratio (rate ratio of roll 100 to roll 70) was 4.1. The resulting 110 denier (122 dtex-34 filament) yarn after stretching had a specific strength of 8.3 g / denier (7.3 cN / dtex) and an elongation at break of 14%. Denier uniformity ("in the terminal direction") in the longitudinal direction of each produced yarn sample was 3.7%.

Example 11

In the embodiment of the present invention using the same polymer used in Example 10, without using a hot tube 475, using the air quench means illustrated in FIG. 3 and the two stage coupled draw roll assembly shown in FIG. The drawn yarn was made. The quench screen has (B) 6.5 inches (16.5 cm) and diameter (D ₁ ) 4.0 inches (10.1 cm); Quench connection height (A) is 6.6 inches (16.8 cm); Quench connection tube height C ₁ is 12.5 inches (31.8 cm); The connecting tube diameter (D ₃ ) is 1.5 inches (3.8 cm) and the connecting taper height (C ₂ ) is 4.8 inches (12.2 cm); Tube height (C ₃ ) was 15 inches (38 cm). The ratio of airflow speed to feed roll assembly speed given by Equation 1 was 1.02. The spinning die had 34 holes. Spinning speed (surface speed of roll assembly 480) was 5000 meters / minute and total draw ratio (rate ratio of roll 480 to roll 465) was 4.6. The resulting 110 denier (122 dtex-34 filament) yarn had a specific strength of 8.4 g / denier (7.4 cN / dtex) and an elongation at break of 22%. Denier uniformity ("in the terminal direction") in the longitudinal direction of each of the prepared yarn samples was 1.1%.

When comparing Example 11 of the present invention to Comparative Example G, better denier uniformity in the direction of the ends was obtained using an air quench means with a coupled spin-stretch process operating at high speed. The 122 dtex-34 filament yarn was substantially the same in specific strength, but a highly uniform air quenched yarn was produced with a yarn productivity 1.7 times greater than the yarn produced by prior art quench means.

While the invention is illustrated by reference to specific and preferred embodiments, those skilled in the art will recognize that modifications and variations can be made through routine experimentation and practice of the invention. Accordingly, the invention is not limited by the above description but is defined by the appended claims and their equivalents.

Claims (22)

Extruding the polymer melt through a spin pack to form one or more filaments; Cooling and solidifying the filament by passing the filament through a pneumatic quench chamber in which quench air is provided to the filament and the quench gas moves in the same direction as the filament; Passing at least one filament through a mechanical stretching step to stretch the filament and lengthen to form a yarn. The method of claim 1, wherein the at least one filament comprises a plurality of filaments, converging the plurality of filaments into a multifilament yarn, and passing the yarn through a mechanical drawing step to draw and stretch the yarn. The method of claim 1, wherein the one or more filaments comprise one filament per yarn and the yarn is a monofilament yarn. The method of claim 1, wherein the filaments are drawn at a draw ratio of about 3 to about 6. 6. The method of claim 1 wherein the filament is passed through the quench chamber at a rate of less than 1500 meters / minute. The method of claim 1 wherein the filament is passed through at least one drawing step and the speed of the filament passing through the final drawing step is greater than about 2600 meters / minute. The method of claim 6, wherein the filament passes the final stretching step at a rate greater than about 4500 g / min. The method of claim 1, wherein at a spinning speed of about 2600 to about 5000 meters / minute, the rate ratio of the cooling gas at the outlet of the quench chamber to the first roll speed that pulls the filament is about 0.6 to about 2.0. The method of claim 1, wherein the filaments are wound into the package at a winding speed reduced from the spinning speed by an amount of about 0.1% to about 7% of the spinning speed. The method of claim 1 wherein the stretching step comprises stretching on a hot tube. The method of claim 1 wherein the dtex per filament of the filament is about 2.5 to 9. 9. The method of claim 1 wherein the birefringence of the filament before the filament is drawn is from 0.002 to 0.012. The method of claim 1 wherein the polymer melt contains colored particles or deglossed particles. The method of claim 13 wherein the particles are selected from the group consisting of titanium dioxide, zinc sulfide and colored pigments. The method of claim 13, wherein the polymer melt contains about 0.01 to about 1.2 weight percent colored particles or deglossing particles. A yarn made by the method of claim 1. A fully drawn yarn made by the method of claim 1. 18. The yarn of claim 17, wherein the specific strength is at least about 5 g / denier (4.5 cN / dtex). 19. The yarn of claim 18, wherein the specific strength is from about 7 to about 10 cN / dtex (7.9 to 11.3 g / denier) at spinning speeds greater than about 2600 meters / minute to about 5,000 meters / minute. 19. The yarn of claim 18, wherein the elongation at break is from about 15% to about 22%. 17. The yarn of claim 16, wherein the denier spread is less than 3.7%. 17. The yarn of claim 16, wherein the hot air shrinkage is less than 10%.