ES2243474T3 - PRODUCTION OF TEXTILE FIBERS CUT FROM POLI (TRIMETHYLENE TEREFTALATE). - Google Patents

Abstract

A process for manufacturing textile fiber cut from poly (trimethylene terephthalate) (PTT), which has an intrinsic viscosity of 0.55 to 1.0, in the existing equipment for manufacturing textile fiber cut from poly (ethylene terephthalate) (PET), comprising: (a) melt extruding the PTT polymer at 245 to 253 ° C, (b) spinning the PTT extruded into thread using at least one row, (c) moving the spun yarn to a first roll of pick-up where the distance from the row to the first pickup roller is 4, 88 - 6, 10 m (16 to 20 feet), (d) cool the spun yarn to less than 31 ° C before it reaches the first pickup roller, (e) optionally, store the spun yarn at a temperature of not more than 31 ° C, (f) before the stretching process, precondition the tensioned yarn at a temperature of at least 60 ° C, (g) stretch the yarn at a temperature of at least 60 ° C, (h) optionally, allow the stretched wire to relax at a temperature of up to 190 ° C, and (i) curl the stretched thread at a temperature of 70 to 120 ° C and decrease the denier of the stretched wire fed by 10 to 60 percent per denier, of the denier of the fed stretched thread used to produce a comparable PET.

Description

Production of textile fibers cut from of poly (trimethylene terephthalate).

Field of the Invention

Poly (Terephthalate) polymer trimethylene) is a new polyester resin suitable for use in carpets, textile materials, and other resin applications thermoplastic (see for example the document EP-0349363A). The poly (terephthalate of trimethylene) (abbreviated PTT) is chemically a resin of aromatic polyester manufactured by the condensation of 1,3-propanediol (PDO) and terephthalic acid. The Textile fiber production from PTT is possible in a wide variety of commercial process equipment.

Background of the invention

The production of PTT synthetic cut fiber is often unfolded in a two-stage process. The first stage involves the extrusion of unstretched thread, which is stored for the stretching process in the second stage. There are two main types of stretching processes used in the production of cut fiber, stretching relaxation (called Draw Relax ) and stretching annealing (called English ( Draw Anneal ). The fundamental difference between these two processes is how it is controlled the shrinkage of the fiber In the production of fiber cut by stretching with stretching the shrinking strategy is to pre-shrink the fibers in an oven after curling to obtain the desired performance and properties In the production of fiber cut annealed with stretching, The shrinking strategy is to heat the fibers allowing crystallization at a constant length before curling.

Cut fiber of polyethylene terephthalate (abbreviated PET by the English expression polyethylene terephthalate ) has been produced and there are well established processes to do so. It would be desirable to be able to produce PTT cut fiber in existing equipment. However, there are many differences between the two polymers which make it difficult or improbable to produce commercially useful PTT cut fiber in existing fiber production equipment. To understand how to produce PTT cut fiber in existing equipment it is necessary to ask several questions of the process:

How to characterize the behavior in thread stretching not stretched? How to make the behavior in stretching the unstretched thread change over time ?. How answering these questions is described in Example 2 and in the Figure 3

How to control thread properties not stretched during extrusion ?, How to answer this question is described in Example 2.

What is the typical stretch rendering for the thread not stretched ?. How to answer this question is described in Example 1 and Example 2.

How to control fiber shrinkage during the production and storage of unstretched thread ?. How answering this question is described in Example 2 and Figure 5.

How to control fiber shrinkage during fiber stretching and fiber products late? How to answer this question is described in the Example 3.

How to curl the fiber to provide the texture and cohesion in the commercial processes carried out downstream in the Production line for spun yarns of textile cut fiber and nonwoven materials? How to answer this question is described in Example 3.

How to heat stabilize and control the module Young and the stretch properties of the cut fiber ?. How the properties of the cut fiber influence the properties of the spun threads? How to answer this question is described in the Example 3

What is a basic process to produce fiber in existing equipment that responds to the interdependent nature of the first six questions of the process raised above ?. Such a process is provided by the present invention.

Summary of the invention

The present invention describes a process of Fiber production cut in two stages using PTT. The first stage is the extrusion of unstretched thread (abbreviated as far as successive HNE). HNE becomes a cut fiber product in the second stage of production with stretching.

In accordance with the present invention, provides a process for manufacturing textile fiber cut from of poly (trimethylene terephthalate) (PTT) in the equipment existing manufacturing of PET textile cut fiber, which it comprises: (a) melt extruding the PTT polymer at 245 a 253 ° C, preferably 245 to 250 ° C, (b) spin the extruded PTT into thread using at least one row, (c) move the yarn thread to a first pickup roller, where the distance from the row to the First pickup roller is 4.88 to 6.10 m (16 to 20 feet), (d) cool the spun yarn to less than 31 ° C, preferably less than 25 ° C, more preferably less than 20 ° C, before it reaches the first pick roller, (e) optionally, store the thread spinning in a temperature-controlled climate enclosure not exceeding 31ºC (both this stage and the previous stage are performed to minimize the premature shrinking of the unstretched thread prior to the process of stretching), (f) before the stretching process, pre-condition the thread under tension to a temperature of at least 60 ° C, preferably 60 to 100 ° C, (g) stretch the wire at a temperature of at least 60 ° C, preferably 60 to 100 ° C, with a second preferred optional stretch, in where most total stretching occurs in the first stretching, more preferably 80 to 85% of the total stretch, and where the second and subsequent stretches are performed at a temperature above the temperature of the first stretching to a practical maximum of the melting point of the thread, preferably 60 to 160 ° C, more preferably at a temperature from 80 to 100 ° C, (h) allow the stretched thread to relax at a temperature up to 190 ° C, preferably 100 to 140 ° C (the relaxation can be 2 to 25% or possibly more but it is preferably 2 to 10%) to achieve an increase in the modulus of Young initial of the stretched thread, and (i) curl the stretched thread to a temperature of 70 to 120 ° C, preferably 80 to 120 ° C if the relaxation stage and 70 to 100 ° C if not used, and decrease the stretched thread denier fed to {} \ hskip0.2cm in 10 to 60 denier percent, preferably 40 to 60 percent, of denier of the fed stretched thread used to make fiber PET comparable in existing equipment. In addition, alternatively or in combination, the volume of the curling iron can be increased by 10 to 50,  preferably 20 to 35 percent more than the curling iron volume used to make PET in existing equipment. Preferably, the choice of conditions is based on the particular equipment and the desired performance

Brief description of the drawings

The present invention will be described in by way of example with reference to the drawings that are accompany, in which:

Figure 1 is an outline of the stages of the process from resin to the packed fiber from which They will describe their critical elements.

Figure 2 is the equilibrium curve of tenacity versus elongation useful to help determine the possible range of properties of the cut fiber for the PTT

Figure 3 shows a typical curve of tension / deformation for spun yarn bundles.

Figure 4 shows the effect of temperature Extrusion in fiber stretch.

Figure 5 shows the shrinkage of the thread no stretched in water of different temperatures depending on the thread spinning conditions not stretched.

Figure 6 shows the schematic orientation which describes the effect of fiber shrinkage.

Figure 7 shows the effect of temperature of the stretch bath and the total orientation parameter on shrinkage by cooking cleaning.

Figure 8 shows the effect of temperature of the stretch bath and the total orientation parameter on Dry heat shrinkage at 125 ° C.

Figure 9 shows the effect of temperature of the stretch bath and the total orientation parameter on shrinkage by dry heat at 140 ° C.

Figure 10 shows the effect of temperature of the stretch bath and the total orientation parameter on shrinkage by dry heat at 175 ° C.

Figure 11 shows the effect of temperature of the stretch bath and the total orientation parameter on shrinkage by dry heat at 197 ° C.

Figure 12 shows the effect of the ratio of stretching and stretching bath temperature over the relaxation factor of the stretching process.

Figure 13 shows heat shrinkage dry predicted depending on the temperature of the dryer oven (relaxer) for the total orientation parameter of 1.4 exempt from relaxation and stretching bath temperature 75ºC.

Figure 14 shows the effect of temperature of the furnace of the relaxer and the stretching of the thread applied on the Dry heat shrink at 175 ° C for 100% PTT threads.

Figure 15 shows the effect of temperature of the furnace of the relaxer and the stretching of the thread applied on the Dry heat shrink at 175 ° C for 100% PET threads.

Figure 16 shows the comparison of Dry heat shrink at 175 ° C of PTT and PET spun yarn at two thermosetting temperatures of the wire.

Figure 17 shows the effect of temperature of the furnace of the relaxer and the stretching of the thread applied on the Dry heat shrink at 175 ° C for PTT threads: cotton 50:50

Figure 18 shows the comparison of shrinkage by cooking cleaning of the spun yarn of PTT and PET a two thermostabilization temperatures.

Figure 19 shows the load comparison of PTT and PET spun yarn at 5% deformation at two temperatures of thermostabilization of the thread.

Figure 20 shows the comparison of the decrease of the percentage tension in 2 minutes of the spun yarn PTT and PET at two thermosetting temperatures of the wire yarn.

Figure 21 shows the comparison of PTT spun yarn strain recovery percentage and PET (2 minute extension) at two temperatures of thermostabilization of spun yarn.

Detailed description of the invention

Polymer textile cut fiber is feasible using existing facilities. Since the equipment used by Different companies vary greatly, there will be differences in How the processes are performed. Once the fiber producer adapt your settings to the unique properties of PTT, it is possible produce a wide variety of fiber products suitable for Use in spun yarn and nonwoven textile materials. The fiber Textile produced from PTT offers excellent character and draped that provide softness, volume, compatibility in mixtures, easy care, and retention of the form in products textiles

1.0 Polymer Fusion 1.1 Resin transfer and drying

Low air transport systems energy minimizes the formation of dust when the resin is transfers from shipping containers, process equipment and storage facilities Before extrusion, the resin of PTT must be dried at a constant humidity level of 50 ppm or less. This moisture specification minimizes the impact of the degradation of the resin by hydrolysis during mass spinning cast. Many types of commercial dryers that use air desiccated have satisfied this requirement. Dryers equipped with molecular sieves (13X & 4A), vacuum systems, and desiccants of lithium chloride have met the moisture requirements in the commercial production When possible, it is preferable to dry the polymer using dried air with 13X molecular sieve (point of dew of -40ºC or less) heated to 130ºC with 4-6 hours of drying time. Using dry air when transferring the Dry resin from the dryer to the extruder is essential to minimize hydrolysis during spinning of the melt.

In large commercial dryers you can question the drying of the PTT at speeds that can maintain the Air passage with the extrusion production capacity. In this situation may require higher temperatures in the dryer. PTT dryer air temperature should not exceed 165 ° C. The residence time in the dryer must not exceed 4 hours when using air at 165 ° C.

1.2 Extrusion of unstretched thread (HNE)

A typical melt preparation system Includes an extruder, spinner, melt pump and spinning package The key is to establish a mass viscosity Optimal and uniform polymer melt minimizing the time of Residence and melt spinning process temperature. Commercial production of PTT HNE with both extruders of Twin spindles as single spindle is direct. In extruders twin spindles it may be necessary to reduce the pressure of the melt in the extruder as much as 25-50% (of PET conditions) to avoid excessive degradation by shear of polymer melt. The production commercial of PTT HNE uses melt temperatures in the extruder varying from 245ºC to 270ºC. Care must be taken when PTT HNE is produced at melt temperatures between 260 to 270 ° C, to avoid excessive degradation of the melt of polymer and the properties of the subsequent HNE. Temperature Optimal melt in fiber extrusion for PTT is 245 at 253 ° C, preferably 245 at 250 ° C. Future PTT resins with lower intrinsic viscosity will probably require lower temperatures Figure 4 shows that the best stretchability is obtained when the polymer is extruded at 250 ° C in place at 240ºC or 260ºC.

2.0 Yarn thread not stretched (HNE) 2.1 Packages, pumps, and spinners

Tests that use extrusion systems mono-components and bi-components To produce PTT fiber HNE were satisfactory. The speed and volume control systems of the spinning pump Sized for PET usually meet the requirements of Lower production capacity per position for PTT fiber. The filtration media must have a minimum pore size of 30 micrometers Often commercial spinning packages use a minimum amount of filtration media. In the early stages of the development of a PTT fiber production process, it is it is preferable to use a standard sand filtration depth of medium / thick size (90/120 mesh). The uniformity assessment of filament diameter will help determine if you need optimization of the spinning pack filtration or the pressure of the melt in the extrusion system.

Fiber extrusion systems are designed for a specific range of resin viscosity, ability to production, melt temperature, and residence time. In general, the production capacity per hole needed to manufacturing PTT fiber is usually 20-30% lower to comparable denier PET products. This increases essentially the residence time for the extruded material of PTT with PET fiber production equipment. The rise of residence time of the melt can lead to the degradation if melt temperatures are higher than 260 ° C. The heating systems of the spinner and transfer pipe should have, if possible, the same temperature than the polymer at the exit of the extruder.

2.2 Rows

The row selection depends on the denier of the product to be obtained and determined by limiting the capacity Production per hole per minute for melt spinning stable. In general, PTT fiber can use row designs PET standard for similar products. However, the fiber of PTT generally requires smaller capillary diameters to low denier products when compared to the production of PET fiber PTT resins have a regime limit of upper shear of 7500-9000 seconds reciprocals for round cross sections that depend on the melt extrusion conditions.

The row selection based on the denier of the Desired fiber product is shown in Table I.

TABLE I Row Selection Data

Fine denier range at 1100 m / minute 1.0 - 1.3 dpf 1.30 - 1.75 dpf 1.40 - 1.85 dpf Row Diameter, (mm) 0.23 0.25 0.35 row l / d 1.85 1.85 1.85 - 2.0 Limiting production capacity by hole 0.32 0.41 0.45

It is important that a long fiber culmination zone (the distance from the row to the pickup roller) be used. This means that the area should be from 4.88 to 6.10 m (16 to 20 feet) instead of the standard 2.44 to 3.66 m (8 to 12 feet) for PET. In the process the shrinkage of the PTT HNE is relatively high so that the process must allow a stable molecular structure to be established in the fiber before all the filaments meet in a thread
Long fed to the stretching process. In the production of PET fiber this is not a significant problem. The PTT has a more elastic crystalline morphology so that the union of the culmination of the longer fiber helps to stabilize the yarn allowing manufacturing that avoids the additional costs of air conditioning.

2.3 Rapid cooling

Tests that use cooling systems Fast radial and cross flow were satisfactory. The systems of rapid radial cooling with both outside air flow to interior as interior to exterior have been used satisfactorily. The fiber bundle should cool quickly and evenly to prevent HNE shrinkage in the boats yarn supply Cooling temperatures have been used rapidly varying from 8 to 35 ° C, although temperatures of 8-25 ° C. In general, the air flow rates of rapid cooling are limited by the operability of the HNE strand path. The number of filaments per position It has varied from 350 to 3500 filaments per position. In the Fine denier fiber production may be possible values higher than 6250 filaments per position with modern systems Radial rapid cooling. The optimization of the systems of rapid cooling involves determining what conditions the maximum operability and percentage elongation performance plus high for the properties of the fillet of the desired HNE.

2.4 Wire finishing

In this specification all coatings applied to PTT fiber during the production of fiber extrusion and stretch production are defined as spinning finishes. Yarn finishes are coatings of fiber that provide lubrication, cohesion, and protection with PTT fiber additives during fiber production and the downstream treatment in the production line. In the production PTT fiber have been used successfully both finishes based on multi-component phosphate as an oil mineral. The application methods and chemicals of finish that have proven suitable for PET spinning are Satisfactory for initial PTT fiber products. The Application methods and thread finishing formulations can be change then based on customer feedback on the fiber treatment

2.5 Collection

For the commercial production of PTT HNE they have used collection speeds ranging from 900 to 1250 meters per minute. In the research team, the collection speeds for the HNE they have varied from 500 to 2250 meters per minute. It is useful use controlled relaxation between winch rollers Pickup and sunflower wheel before inserting the filament in the can of the filament beam. Cool all filaments in a unique position at less than 25-30 ° C is necessary to minimize the shrinkage of the HNE in the boat of the beam filaments

3.0 Stretching and finishing filament beam 3.1 HNE storage

Under normal storage conditions, the PTT HNE completes more than 90% of its aging process within 8 hours from extrusion. The properties of HNE stretching will stabilize within 24 hours and will not observe any significant change in the properties of stretching after 2-4 months of storage at a constant temperature The PTT HNE has the potential to shrink more easily and at lower temperatures than PET HNE. Warmer storage conditions than 25-30 ° C because they cause shrinkage of the HNE. Ideally, the PTT HNE fillet is stored in a Air conditioning environment to help prevent shrinkage. The exact temperature that causes the PTT HNE shrinkage Depends on extrusion conditions, fast cooling, pickup and storage of the HNE. Even if the PTT HNE shrinks it is possible to convert this HNE into a commercial fiber product of first quality during the stretching process with less impact on product quality.

3.2 Filet size

The size of the PTT fiber fillet is determined by the size of the production curling iron. In general, the Fillet size for PTT fiber is about 60% of the corresponding to an equivalent PET fiber product due to the higher volume of PTT fibers. A bundle of filaments stretched 600,000 denier will successfully feed a curling iron 110 mm wide by 20 mm high. This can change when the size of the curling iron increases and / or the speeds of stretch production above 100-130 meters per minute. Since most production lines stretching have a maximum linear speed of 250-300 m / min, increase the chamber volume of curly, is another way to improve the productivity of the line of stretching.

3.3 Preparation of the fillet and the filament bundle

Avoid heating the HNE PTT above 25 ° C until the HNE filament beam is under tension of uniform roller This will minimize the shrinkage of the PTT that feeds the stretching process and maintains a uniform tension fiber at all points in the cross section of the beam of filaments during stretching. If shrinkage is allowed uncontrolled and non-uniform HNE, the orientation variation of Boat by boat will limit the uniformity of the stretching process.

Baths are preferred pre-wetting before stretching, but the temperature should not exceed 25 ° C unless provided control and pressure rollers to minimize tension in the feeding section for stretching. If the drive rollers they are not available, the bathroom must be at a uniform temperature lowest possible.

3.4 Stretching process

PTT fiber has been manufactured in relaxation process configurations with stretching and Annealing with stretching. In the process of relaxing with stretch the fiber is treated with heat and dries under zero tension to reduce shrinkage. This process produces a fiber of Low module suitable for PTT spun yarns and fiber blends Low modulus of wool and acrylic. The annealing process with stretching heat treats the bundle of low roller filaments high tension and produces a more suitable upper module fiber for mixing with secondary amounts of rayon, cotton or other upper module fibers.

The initial stretch point of the beam HNE filaments in the first stage of stretching should occur under water heated to a minimum of 60 ° C, preferably 60 to 100 ° C. Keeping the stretch point warm improves the stretching process operation reducing significantly the impact of extrusion conditions on production stretch ratios. If desired, the second stretch stage is hotter than the first stage of stretching to a practical maximum of the melting point of the thread, preferably from 60 to 160 ° C, more preferably 80-100 ° C. Unlike PET, PTT will not become rough in hot stretch baths. Stretch zones additional are optional and usually extend slightly Total stretch ratio of the machine. The relationship of Main stretching should be performed in the first stage.

Annealing or relaxing the filament bundle PTT fiber with a 3% roll relaxation through a setting of the calendering rollers at 100-130ºC increases the initial module of the final PTT fiber by 12-14% This process produces a high fiber module suitable for PTT spun yarns and fiber blends High module like cotton, rayon and PET. The initial module increases approximately 4% for every 10 ° C from 130-150 ° C when the relaxation through Roller assembly is maintained at 3%. The annealing of the beam of PTT filaments above 150 ° C may require increasing the relaxation through the calendering rollers to avoid Excessive filament breakage. The finishing of threads frequently it is applied to compensate for the loss of the finishing of threads in the stretching process using a dip bath or application of the front / rear friction roller only before the stage of curly.

3.5 Curly

The PTT filament beam curves very easily compared to the PET filament beam given its low bending module This low module also provides excellent touch and softness to PTT. Additionally, the PTT is very much more bulky than PET. The low curvature module and the high volume require the following changes in the conditions of curly:

?

The dancing roller is reduced and the curling roller to provide more control of the geometry of curly.

?

The denier of the filament beam fed should be decreased or the volume of the curling iron due to the higher volume of the PTT. The increase in volume of PTT can be explained by the decrease in the amount of denier of the filament beam that is fed to the curling iron, in a proportion more preferably 10 to 60 percent, preferably 40 to 60 percent, all for denier. Another way is to increase the volume of curling iron at 10 to 50 percent, preferably 20 to 35 percent, All by volume. Also, a combination of these can be used. Two methods

?

Ideally, the curling iron should be equipped with water vapor injection and thread finish to better control the temperature of the curling chamber.

?

It may be necessary to improve the pressure and temperature control accuracy in the chamber curly.

Curl stability and pickup improve significantly when the curling chamber is at least 85 ° C and at 300 kPa (3 bar) of gate pressure. The frequency of curly can be greater and the amplitude of curly less than those of comparable PET fiber. Ripple stability and collection they improve as the curling temperature increases. Curling iron it should not get too hot because, as the curly stability, the same does fiber cohesion, what which can increase carding defects.

3.6 Drying, cutting, and packaging

The relaxation (drying) of the PTT fiber in Conventional endless belt ovens, it's simple. But nevertheless, both the curl geometry and the characteristics of shrinkage change when the oven temperature rises by above the hottest temperature in the stretching process preceding. In the production of relaxed stretched fiber decrease both the cut fiber and the dry heat shrinkage of the thread subsequent spinning as the temperature of the dryer.

In the production of stretched annealed fiber the Relaxation oven is used as a dryer. The air flow rates are relatively high and relatively low air temperature (75-90ºC) to facilitate drying of the beam of filaments These conditions are not hot enough to allow the relaxation of the cut fiber or the change in the curly geometry The fiber filament beam has been cut in Commercial production using both converter type cutters Rotating as peaceful without modification. Both the packers of Gravity-transported and airborne fiber have PTT fiber packaged in commercial tests.

4.0 Generic recipes for 1,7, 2,5 and 3,33 DTEX fibers (1.5, 2.25, Y 3 DPF)

Stretch recipes for three products Typical fiber are briefly described in the following table. Every Fiber production facility is different. They will usually be done 2-3 attempts in a commercial line to identify The commercial process for PTT fiber. These recipes are They developed in a small commercial production team. The they may change slightly when processes are increased of scale for larger equipment and higher production rates. HNE is produced using a melt temperature of 253 ° C at 1100 m / min. To achieve these stretching relationships you require uniform extrusion conditions, such that the coefficient of variation of the diameter of the filament is between 3-5% in all spinning positions. Additionally these stretch ratios are obtained in Modern process equipment very well controlled. It is not unusual for an older team achieve only 75-85% of These stretching relationships.

The recipes in Table II also describe a high and low shrinkage recipe for each fiber denier wanted. The amount of shrinkage in the production of stretching decreases significantly when the First stage stretch bath temperature above of 60 ° C. Additionally, the amount of shrinkage in the Stretch production decreases slightly as Stretch ratio increases. Finally the shrinkage in Stretch production in the curling iron and dryer are reduced additionally when calendering rollers are used to anneal the fiber. Commercial production speeds of product stretch of 100-130 meters per minute and development stretch speeds as high as 225 m / min The commercial process of relaxation with stretching, typically uses a first stretch at 70 ° C and a second stretching at 100 ° C. The commercial process of annealed fiber typically uses a first stretch at 70 ° C, a second stretching at 100ºC, and calendering rollers at 130ºC with a relaxation of 0.95.

TABLE II Recipes in draft for fiber 1,5, 2,25 and 3,0 dpf

one

4.1 Fiber properties

This analysis of tensile properties assumes that the raw material of the fillet is stretched to a value of 90% of filament beam breakage. A typical fiber cut from PTT of relaxation with stretching, usually will have a toughness of 2.7-3.0 cN / dTex and an elongation between 80-90% An annealed commercial fiber with Stretching will have 3.4-3.5 cN / dTex and a elongation between 60-65%. Balance curve elongation versus toughness that can be seen in Figure 2 it is useful in to help determine the possible range of fiber properties for PTT. It is a challenge to produce PTT fiber Low elongation and high tenacity due to rapid relaxation of the PTT filament beam under the curling conditions. The single filament test results in research team and development (R&D) indicate such high fiber toughness as 4 cN / Tex with 45% elongation. Fiber could be produced PTT with strengths greater than 3.5 cN / Tex in a process of Stretch with highly optimized annealing. In this effort The control of curly conditions will be critical.

Example 1 Controlled shrinkage of unstretched thread during extrusion and storage

Evaluation of shrinkage of unstretched thread PTT HNE yarn spun at two different locations under a wide variety of different conditions. The results test indicate that it is better to store the PTT HNE below 31 ° C to avoid excessive shrinkage greater than 2-3%, as shown in Figure 5. This graph shows the shrinkage percentage in unstretched thread submerged in water baths at various temperatures: 30ºC, 31ºC, 32ºC and 35ºC. The spinning conditions covered a denier interval by filament (dpf) of the stretched product that varied from 0.8 to 4.5 dpf and the operating range of the production capacity and the pickup speed for fiber production lines different development in location A and another in location B. This graph also shows that the shrinkage of the PTT HNE it is more a function of spinning conditions than of temperature of fast cooling air. Location A uses air from rapid cooling at 25 ° C and location B uses air from rapid cooling at 16 ° C.

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The excessive shrinking of the unstretched thread is undesirable because it can increase product variability of fiber if not properly controlled.

Example 2 Shrinking PTT tapes of the stretching process of the fiber Summary and conclusions

Stretching in baths at 60 ° C or higher eliminates any spin-induced structure effect as shrinkage of the stretched fiber.

Shrinkage of stretched fiber decreases with the rise in the temperature of the stretch bath, but the effect is clearly less at temperatures below 60 ° C. He shrinkage also decreases with increasing orientation total (Stretch Ratio), but the effect is much less than higher temperatures of the stretch bath. When he Stretch shrinkage is insensitive to spinning adjustments and stretching, the curly becomes more stable, and the product less variable Stretching at temperatures is recommended higher than 60 ° C that the curling operation must provide stable.

From the shrinkage data it they obtained the relaxation factors predicted for curling and drying / relaxing depending on the temperature of the dryer / relaxer Although the shape of the curve is correct and it can use for extrapolation of known data, the magnitude of the factor seems too high.

It seems unlikely that the shrinkage of product depending on the temperature of the dryer and the relaxer can predict from the shrink data for PTT.

Introduction

The spinning conditions intervals examined in the pilot stretch line used herein invention was:

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Block temperature: 240 a 260 ° C.

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Production: 0.432 to 0.865 g / hole per minute (0.4 mm capillaries)

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Spinning speed: 1000 to 2000 m / min

These supplies were stretched at three speeds stretching:

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Stretch Ratio with break (RER) minus 0.1

?

RER - 0.2

?

RER - 0.4

These conditions coupled with great variation in the orientation of the yarn they give a large orientation range of yarn.

Three bath temperatures were used fiber stretch:

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40 ° C

?

55 ° C

?

70ºC

This was the maximum and practical range operable for the team

The stretched ribbons were characterized completely. Shrink results are analyzed. later.

Unlike tenacity and elongation, the which in PTT, PET and other melt spun polymers, They are mainly function of total orientation, shrinkage it is a much more sophisticated property of the fiber structure, and is affected by the orientation and, more importantly, by the crystallinity

The objective of this part of the experiments is To answer the following shrinkage questions, the which are presented in their order of importance for the design of the process.

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one.

The differences in the structure of the spun yarn persist through the stretching, or does the stretching process erase them? This has important implications in the design of the processes and methods of yarn.

2.

How Does the temperature of the stretch bath affect shrinkage? He residual shrinkage after stretching is a factor main that affects the way a fiber can be curled easily. In general, high shrinkage fibers curl easily. If shrinkage is a function strongly dependent on the temperature of the stretch bath and the orientation, the curling iron must be rebalanced frequently to reflect the change in stretching conditions, and curly It is less uniform.

3.

How much shrinkage will occur when a fiber is stretched and curly and how it is affected by spinning and stretching conditions? This information is used to Calculate the relaxation factor in the spinning model.

Four.

That additional shrinkage of the product will exist at temperatures superior when fiber is freely relaxed in an oven to a given temperature?

A model that has proven useful for PET It has the following premises:

When heats above the glass transition temperature, unless that is restricted, a fiber will shrink until it has disoriented the entire amorphous zone.

When the temperature rises above the glass transition, additional oriented amorphous areas They appear as a melt of crystals. These amorphous areas recently created are disoriented later, providing the additional shrinkage So, in general, how much higher is the temperature, the higher the shrinkage.

Several definitions are required, which are somewhat circular in nature. Transition temperature Vitreous is defined as the temperature at which the amorphous chains Unrestricted are free passes disorienting, as required by the second law of thermodynamics. The amorphous zones are those that are not crystalline. The crystalline areas are the ones Don't get disoriented at this temperature. There are a number of modes of define the crystalline regions in terms of TGA curves, behavior against x-rays, density etc, and all give more or less different answers, but related, in terms % crystallinity For the purposes of this analysis will be defined the crystals in terms of their ability to retain the temperature orientation.

Inherent in this model is the assumption that the heat treatment of a string results in fusion only crystalline and disorientation of the fibers. This model too works well for relaxed PET threads in short processes residence times It works quite well for the processes of fibers that involve residence times of several minutes, but before this work its validity for PTT was unknown.

The length, in the orientation diagram, of the Figure 6, can be used to illustrate the process. This diagram represents what happens when a fiber is stretched from its Zero birefringence length to fiber length of sample, l_ {f}. When this fiber is heated to temperature T_ {1}, loses length to l_ {1}, because they become disoriented all amorphous zones and all crystals that are not stable T_ {1} merge and also disorient

The fiber is not completely disoriented due to that there are still crystals that are stable at T1. When the temperature rises to T2, more crystals melt, it becomes amorphous, disoriented and the length decreases more. It could be thought that it would be possible to shrink completely to zero birefringence the stretch ratio 1.0, but in practice there are some crystals that are stable at the melting point and beyond thereof, (which causes problems in the polymerization of PET). These are not disoriented and such reorientation can never be complete.

Taking into account the previous introduction, it is now possible to ask the experimental questions. The differences in the structure of the spun yarn they persist through the stretching?

You might expect the shrinkage to be strong function of the stretch ratio, because It provides the guidance that is lost. With PET, this is up to true point, but the effect is excessively overshadowed because of the fact that as the orientation increases, what it makes the ability to form crystalline zones, which is therefore opposite effects of increased orientation. Also in PET, to high temperatures of the stretch bath erases all the spinning memory, as far as shrinkage is concerned. The orientation can be approximated as the parameter of total orientation (POT) (Stretch ratio of denier / natural stretch ratio).

To calculate the stretch ratio natural, it is necessary to determine the appropriate strain rate for the specialized laboratory and labor team that would give The reproducible results. A single tube yarn at 40 # / hour, 240 ° C, and 1500 m / min, underwent deformation rates of 200 to 800% per minute Three measurements were made in duplicate with the curves plotted on a single graph. The results were quite reproducible at all deformation rates, which indicated Good specialized workforce and good laboratory equipment. All the determinations provided the characteristic curve illustrated in Figure 3. The natural stretch ratio (REN) It can be easily calculated from these graphs as follow:

(1) REN = 1+ (S_ {n} / 100)

in where:

S_ {n} is% deformation in deformation by natural stretch

This is equivalent to the classic definition of NDR, which is:

(2) REN = l_ {d} / l_ {s}

in where:

l_ {d} is the length at the point of inflection of natural stretching

l_ {s} is the length of the spun sample.

The first stage is to establish which variables are statistically significant in predicting shrinkage at a given temperature The method consisted of using regression with progressive introduction of variables and elimination progressive variables in the Sigma Stat 2.0 computer program with F to enter> 4.0 and P to reject <0.05.

The results summarized in Table III indicate:

?

Both results in general they agreed.

?

At stretching temperatures 60 ° C or higher, spinning variables do not play a significant function in fiber shrinkage stretched out

?

The orientation parameter total and, surprisingly, the temperature of the block, were Significantly weak factors in shrinkage at 45 ° C as stretching temperature

It is concluded that they should be used stretching temperatures of 60 ° C or higher to eliminate any spinning effect on the shrinkage of the product. These data support the hypothesis that, as in PET, the structure of spinning is eliminated if a stretching temperature is used significantly higher than T_ {g}. Regression equations for correlations with R2> 0.5, they are described in the Table next. Note that they do not exist for T> = 60 ° C.

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(Table goes to page next)

TABLE III Shrinkage Regression Analysis of headband

2

How does shrinkage affect Stretch bath temperature ?. Figures 7 through 11 are graphs of shrinkage by cooking cleaning, and shrinkage by dry heat at 125, 140, 175 and 197 ° C, for all three temperatures of the used stretch bath. It is clear that there is a change of large mechanism between 45 and 60 ° C, the next higher temperature analyzed. At temperatures above 60 ° C, the shrinkage is almost independent of orientation, and relatively insensitive to temperature of bathroom.

Higher bath temperatures decrease shrinkage potential a small amount, but not significant in terms of the potential for curling or rendering (yield) likely of the product.

The orientation at temperatures of 60 ° C or upper is recommended because the orientation of the curling iron It is very simplified. No curling iron adjustments are required in these conditions, except to compensate for denier density in the curling iron (denier / inch linear curling iron, dtex / cm curling iron linear).

How does the temperature of the spinning bath and stretching affect the relaxation factor? Figures 7 to 11, and the analysis of variance, indicate that the shrinkage potential of the stretched rope is independent of the spinning conditions and only weakly dependent on the orientation, except for the lowest temperature examined,
45 ° C

Figure 12 shows the relationship between oven temperature and chord relaxation factor stretched. At stretching bath temperatures above 60 ° C, a line through the grouping of the upper part of The data points should approximate the relaxation factor. This It is a good starting point, but the value can also be high (shrinkage too low), because the shrinkage method use a small weight on the sample, so that it is not completely free to relax as you would in a dryer / relaxer of a typical plant.

However, the curve must have the form correct and therefore be good enough to extrapolate the temperature effect when more specific data are obtained from machine.

Can the product shrinkage be predicted relaxed tape shrink data?

With reference to Figure 3 and the model of simple shrinkage for PET, it is found that if a fiber to l_ {f} is put in an oven at T_ {1}, it will lose orientation amorphous and some of the crystals will melt and disorient and your length will decrease to length l_ {1}. Similarly, if a sample of length l_ {f} is placed in an oven a T_ {2}, which is greater than T_ {1}, will shrink more because more of the crystalline material will melt at the higher temperature and will shrink to length l_ {2}.

Mathematically, shrinkage can be expressed in the following way:

We have:

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(1) \ Phi_ {1} =% shrink @ T_ {1} / 100

(2) \ Phi_ {2} =% shrink @ T_ {2} / 100

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So, from the definition of dry heat shrink:

(3) Ph1 = (l_ {f} / l_ {1}) / l_ {f} = l - l_ {1} / l_ {f}

(4) Ph2 = l - l_ {2} / l_ {f}

What would happen if the sample Relaxed free at T_ {1} is tested for shrinkage to T_ {2} ?. If there is no crystalline growth or change other than fusion and disorientation during the first process of shrink, should shrink to l_ {2}.

So what the fiber experiences is the first shrink in the relaxer, and the second shrink is the residual shrinkage in the relaxed product. It is possible that in some degree that PET follow these assumptions to estimate the product shrinkage relaxed from shrinkage by dry heat of the stretched ribbons.

To do this, what must be calculated is the shrinkage when the product shrunk to T_ {1} is shrunk a second time to T_ {2}. This can be done using the definition of shrinkage and Figure 3 as follows:

(5) \ Phi ps = (\ text {% shrinkage of the sample shrunk to} \ T_ {1} \ \ text {when shrinking to} \ T_ {2}) / 100

(6) \ Phi ps = (l_ {1} - l_ {2}) / l_ {1} = l - l_ {2} / l_ {1}

If equations 3 and 4 are used to eliminate l_ {1} and l_ {2} in terms of shrinkage by dry heat measured at the two different temperatures, this leads to:

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(7) \ Phi ps = l - (l - \ Phi2) / (l - \ Phi _{one})

From this and the shrinks measured, the expected shrinkage of the product at T2 can be calculated after an oven relaxation at T_ {1}.

Figure 13 is a shrink diagram Predicted for the useful technical case of high orientation high, and high bath temperature It seems that fiber shrinks predicted after a relaxation given in the oven, they are also very low. This indicates that a change occurs in the dryer / relaxer significant crystalline in addition to simple disorientation.

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Example 3 Evaluation of thermostabilization in PTT cut fiber on the properties in PTT spun yarns, under conditions of hot deformation: the threads evaluated include PTT, Mixture PTT / PET, PTT / Cotton Blend, and PET (Table IV)

Filament rupture during extrusion of PTT synthetic fibers severely limit the productivity of Production and product quality. PTT resins with a VI (intrinsic viscosity) in the range of 0.55-1.0, are preferred, more preferably those with a VI the range 0.675-0.92, and more preferably those that they have a VI in the range 0.72-0.82. Produce synthetic PTT fibers with an intrinsic viscosity range of 0.72-0.82, helps to improve the operability of Synthetic fiber production and product quality without a significant reduction of the properties of the final fiber.

Reducing the intrinsic viscosity of PTT helps to:

one.

Reduce the amount of change in chip viscosity compared to the viscosity of the fiber subjected to extrusion.

2.

Improve dough homogeneity polymer melt in the spinning package. PTT resin with VI 0.92 requires more spinning packet filtration systems severe to maintain marginal returns in extrusion.

3.

Improve production operability decreasing the number of broken filaments during the production.

Four.

Allow to move the product with colder extrusion temperatures for extruded filaments which have less than 2 denier per filament. It is known that the PTT is degrades at a melt extrusion temperature above 260 ° C. When synthetic thin denier filament is produced (filaments with less than 2 dpf), using 0.92 VI resin, you have that increase the melt extrusion temperature to reduce the melting viscosity enough to avoid excessive turbulence of melt flow and degradation of the melt that causes the filaments to break during the extrusion.

5.

Reduce the amount of shrinkage in the fiber of the product making the stretching process easier and / or winding in stable yarn packages.

The fiber threads manufactured from PTT are surprisingly elastic having recoverable elasticity when They extend up to 15-25% of the original length of the thread This elasticity is also present in the threads of fiber produced from mixtures of intimate fibers and not intimate, where PTT is the main fiber component by weight and / or length. In addition, this elasticity is recoverable after Several hundred cycles. The elasticity is enough to improve the shape retention characteristics of textile fabrics Produced from PTT fiber threads and fiber threads cut mixed. Properly constructed and finished fabrics containing a majority of PTT fiber spun yarns (by weight of the percentage of length), can have an elastic recovery surprisingly superior in knitted and knitted fabrics (submitted to tests for 500 manual and 200 instrumental cycles). The The present invention covers the formation of fiber spun yarns cut by fiber conversion into a thread structure twisted by any method. Spun yarn can be obtained manually, by spinning wheel, ring spinning, spinning open ends, air jet spinning or other types of fiber for the thread conversion equipment.

The cut fiber threads made of cotton, Wool, acrylics, PET, are not elastic. In order to produce threads  of fiber cut from these fibers that are elastic, in the industry has commonly added a continuous elastic filament internally to the thread or fabric to give elastic properties of the final textile product. These solutions are more expensive than a Basic cut fiber spun yarn made of PTT. The value of the present invention is that people who have technologies of basic fiber spun yarn can produce a spun yarn elastic of commercial value without investing in more expensive equipment for core spun yarn, or incorporate continuous filaments elastic in fabric structures, which then complicates  the way the fabric is dyed and finished.

An effort has been made to characterize briefly as the fiber thermostabilization properties cut influence the behavior of threads made of PTT fiber and PTT fiber mixed with cotton, and PTT fiber mixed with PET fiber. As indicated in Table IV, PET and the cotton and PET blending threads were prepared from Various supplies of PTP fiber produced with different temperature of the relaxer and they have curly significantly different. Thus, the effect of mixing with other fibers, not It can definitely be determined. Care must be taken, so therefore, in inferring the effects of precise level of mixing to From these experiments. This experiment refers to each one of the threads of the example in terms of shrinkage, modulus, decreased tension and recovery. These factors are generally independent and were studied separately in this work.

TABLE IV Fiber properties

3

Summary and conclusions For dry heat shrinking of spun yarn at 75 ° C

?

Shrinkage by dry heat of the spun yarn decreased with oven temperature for all the mixtures tested (100% PTT, 100% PET, PTT / PET 50/50, and PTT / 50/50 cotton).

?

Shrinkage by dry heat increases approximately ½% for every% of stretch applied (or relaxation) for all mixtures tested.

?

The shrinkage of the spinning thread PTT was 2 to 2½% less than for PET threads.

?

PTT data follow closely the amorphous disorientation model for shrinkage.

For shrinkage by spinning yarn cooking

?

The shrinkage by cleaning by cooking decreased with oven temperature for all mixtures tested.

?

The shrinkage by cleaning by cooking increases approximately 0.4% for every 1% stretch applied for all mixtures tested.

?

The spun threads were approximately 1% lower than PET threads in shrinkage by cooking cleaning, because they were manufactured by the process of relaxation with stretching, while the PET sample was Annealing with stretching.

For yarn thread loads with 5% deformation (stretching)

The fabrics were perceived as "stretchable" when too little force is required to change your Length in a significant magnitude. In this series of essays, we chose to characterize the stretch by observing the force required to deform the fabric 5%. Stretching was applied to the main variable that affects all mixtures subjected to test. The oven temperatures were much less important, This evaluation indicates that:

?

The PTT presented 3-4 times less force to lengthen 5% (greater stretching) than PET.

?

The magnitude of stretching of PTT that decreases with the stretching applied is 1/10 of that of PET (increase of 0.01 gpd / 1% stretch versus 0.1). Therefore the applied stretching can be used to modify in the PTT the thread properties without a large stretch penalty of thread.

?

100% thread stretch PTT was relatively insensitive to the conditions of thermostabilization

Thread yarn tension decrease

How much thread or fabric will be recovered after being subjected to a given deformation for a length of given time depends on two factors:

one.

How much tension decrease occurs while maintaining deformation.

2.

The amount of recovery after the deformation.

These factors are generally independent and They were studied separately in this work:

?

The decrease in tension of PTT was independent of the thermostabilization temperature and decreased linearly with the increase in applied stretch (0.5% reduction in tension reduction / 1% of stretching applied in thermostabilization).

?

Deformation decrease of PET decreased with increasing oven temperature and linearly with the increased stretch applied. The effect of applied stretching is considerably stronger than with PTT (-0.9% per% stretch applied).

?

PTT and PET presented approximately the same amount of decrease in tension.

?

PTT / PET mixing threads they behaved about halfway between the threads Corresponding cigars with a decrease of -0.7% by% of stretching applied.

?

The decrease in tension of PTT / cotton blend yarn was independent of the conditions of thermostabilization

Spinning Yarn Recovery

Recovery for threads from this sample set was much smaller than that observed for the sample of newly tested pre-commercial thread that I had 98% recovery. The cause for this may be the oven   100 ° C dryer used in fiber processing. The main thermostabilization variable that affects the recovery for all samples tested was the applied stretch, with increased applied stretch and increasing recovery:

?

PTT recovery increases 0.9% for 1% of applied stretch.

?

The PTT generally had 5 to 10% recovery greater than PET.

?

The mix data of PTT / cotton were very erratic, but presented the same general trends than pure threads.

Fundamental principles of shrinkage

In a polymer fiber semi-crystalline with significant orientation, the orientation resides in two zones, the crystalline zones and the zones Amorphous that connect the crystalline domains. There is usually a range of crystal sizes, and orientation may vary of the crystalline regions.

When a fiber is exposed to temperatures by Below the glass transition temperature, the change in length It is very slow and is called elastic yield (or deformation progressive). In general, useful textile fibers have all low rates (proportions) of elastic yield in the absence of load. When the fiber is heated to temperatures above the Tg, amorphous zones become mobile and in the absence of a restraining force, they disorient as closely as they can to the isotropic state (non-preferential orientation). The state Isotropic is favored by the second law of thermodynamics. This usually results in shrinkage, but in cases rare, the crystalline regions collapse on themselves and there is "negative" orientation so that the fiber grows. Such Fibers are called self-lengthening. It is not known if They can be manufactured from PTT. The crystalline regions are not mobile, And don't get disoriented.

As the temperature continues to rise of the fiber, the smaller crystals fuse and their domain arrives To be amorphous The fibers at this time become disoriented and a additional shrinkage This is why shrinkage increases usually with the temperature for a polymer semi-crystalline So, there are two strategies for reduce fiber shrinkage:

one.

Pre-shrink the temperature that the fiber is desired to be stable.

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2.

Crystallize under heat and tension at a temperature that provides temperature stable crystals at which is not wanted to shrink the fiber.

For the PET fiber article, where Parameters are spinning and weaving efficiency, and resistance of the thread the second strategy is used exclusively, because as it will be seen later, the pre-shrinkage reduces the fiber module. Specialty fibers, particularly for wool blends, use the first strategy because the stretching and the module are not important parameters, but the best staining ability offered by strategy 1 is a advantage. At this juncture, it is not clear which is the best PTT strategy.

If a fiber is stretched, it increases its orientation amorphous, and therefore the shrinkage. In non-twisted PET continuous, the filament of thread that exists is often of a correspondence of almost 1 to 1 (at 5% stretch increases correspond increases of 5% shrinkage).

So far we have analyzed non-curly fibers alone The situation for spinning yarn is more complex, due to that:

?

The fibers are twisted to a propeller angle which reduces the shrinkage effect of the fiber in the thread.

?

The fibers migrate from outside towards the center of the thread.

?

The fibers can slide in the thread.

?

The presence of mixed fibers with different shrinkages you can change the shrinkage of the set.

Even with these complexities, we can use the Unique fiber model to predict responses of a spun yarn in thermostabilization conditions:

one.

If he thread is heated and allowed to relax freely, should be disoriented and the crystallinity must increase. Both factors decrease the shrinkage. At a constant oven temperature, the decrease Shrinkage should be linear with relaxation. He shrinkage should decrease with increasing temperature of the oven.

2.

If a thread is heated and kept at a constant length, there is no disorientation. Shrinkage decreases with increasing oven temperature provided the oven temperature of thread treatment is superior to that experienced by fiber during the free relaxation stage in the manufacture of the fiber.

3.

If a thread is heated and stretched, the orientation increases and therefore, must shrink. The shrinkage should increase linearly with the applied stretching, and decrease with increasing temperature of the oven, with the condition that it is higher than the view during Fiber processing

Taking into account the fundamentals above, we are ready to analyze the effect of the conditions of thermostabilization in the shrinkage of the thread.

Dry heat shrinkage of the spun yarn at 175 ° C

As illustrated in Figure 14, the PTT is a wonderful substrate that follows all the rules of the model of total orientation

At 0% stretch applied, the control that is relaxed at 100 ° C, it has exactly the same shrinkage as the thread treated at 100 ° C. When it comes to higher temperatures, still at constant length, shrinkage decreases.

As the length is changed by the applied stretch, or shrinkage, shrinkage increases linearly with the stretch applied, and the slopes are approximately constant with the oven temperature. To one given oven temperature, 176 ° C, shrinkage by dry heat increases approximately 0.46% for 1% of applied stretch.

PET behaves in a similar way, Figure 15. Because it is an annealed fiber and not a relaxed fiber, the shrinkage of the control wire decreases with increasing oven temperature even at 100 ° C. Because of this high module, to high stretch and low oven temperature, the fibers are not they stretch, but they slide on the threads so that the increase in Shrinkage is not so big as for PTT. For temperatures from the oven pro above 130ºC, the dry heat shrinkage of PET  increases approximately 0.55% for 1% of applied stretch. This is somewhat higher than for the PTT, but a good criterion Practical for both is ½% shrinkage increase for each% of stretching.

Figure 16 compares the shrinkage of the thread of PTT and PET for the highest thermostabilization temperatures and lower. PTT has approximately 2 to 2½% of dry heat shrink less than PET for conditions oven equivalents. As mentioned earlier, they have about the same increase in shrinkage with stretch applied.

The PTT / cotton blend is similar to the mix PET (Figure 17) with increased shrinkage with temperature of the decreased oven and increased stretch applied. The increase with applied stretch is quite linear and shrinkage increases approximately 0.47% for 1% of applied stretch. He Shrinkage of cotton blends is approximately 1% lower than that of the PET mixture for similar conditions. For this sample series, a good practical criterion is that 1% of Applied stretching increases ½% shrinkage by dry heat.

Shrinkage by spinning yarn cooking

The shrinkage by cooking cleaning is behaves in the same way as that produced by dry heat, except that the available amorphous orientation is what is present in the fiber plus all crystals that melt between the temperature of glass transition and 100 ° C, so that it is much smaller than the dry heat shrink. In some fibers where the effect of water plasticization is high, this shrinkage can be considerable. The fibers produced by a relaxation process with stretching with relaxing temperatures above 100 ° C, generally they have very low shrinkage by cooking. The annealed fibers generally have shrinkage by cleaning by relatively high cooking, because they are heated under tension and amorphous orientation is always present.

These samples generally followed these beginning. All mixtures behaved in a similar way to dry heat shrinkage with shrinkage decrease with increases in oven temperature, and increase with stretching applied.

PTT control thread had a shrink of 2% even when the fibers that entered it relaxed in the oven at 100 ° C. This indicates that some cold stretching occurred in the processing, probably during carding. This is not unexpected, given the low PTT modules. Thread shrinkage PTT increased approximately 0.38% for 1% stretch applied. The control PET thread had a shrink considerably higher than the PTT (4.5 vs. 2%), due to which is produced by the annealing process. Thread shrinkage increased 0.47% for 1% of applied stretch. In general, the PTT threads have approximately 1% less heat shrinkage dry than PET threads given the similar conditions of wire thermostabilization (Figure 18).

The threads of the PTT / PET mixture had an increase 0.44% shrinkage for 1% applied stretch, and thread PTT / cotton had an increase of 0.417. A good practical criterion for shrinkage by cooking cleaning is that it increases approximately 0.4% for 1% stretch applied in all conditions tested.

For 100% PTT spun yarns, the load at 5% deformation is almost dependent on oven temperature and is linearly related to the increased stretch applied 0.01 gpd for 1% increase in applied stretch. This means that the stretching of the thread decreases as the Thread is stretched during thermostabilization. It warns for PTT data than the control thread, which was produced from of 100% relaxed fibers, has essentially the same load at 5% of deformation that the thermostabilization at 0 stretch and 100 ° C

PET threads behaved in a way Similary. In this case, there was a considerable change for the threads of control against thermostabilization of the wire at 100ºC and 0 stretching applied because the fed fibers were overcooked, not relaxed. PET load at 5% deformation, increases an order of magnitude greater than that of the PTT with applied stretch, 0.1 gpd / 1% applied stretch.

Figure 19 compares the behavior of PTT and PET, and the advantage of PTT stretching is surprisingly evident. Not only is the force required for 5% deformation a lower factor of 3 without stretching applied, but the applied stretch response is much lower, which means that the applied stretch can be used in PTT threads thermostabilization without paying an excessive stretch price of the thread It's interesting that the PTT article with the stretch higher applied (7.5%), requires 45% less force at a 5% strain than the PTT sample that is 7.5% relaxed.

Thread yarn tension decrease

How much deformation a thread or fabric will recover after being deformed and kept at constant length for a Period of time, depends on two factors:

How much decrease in tension occurs while Which sample is kept at a constant length? If extreme, if all tension is lost, recovery will be zero.

How much deformation is recovered after trial time period ?.

This stress reduction experiment of Spun yarn involved a 5% deformation of the yarn, keeping then the yarn spun in its length for 2 minutes and allowing to the thread recover to zero tension. The decrease in tension is calculated manually from the test graphs and it's something less accurate than the quantities calculated by machine by methods of computer analysis The decrease in tension and recovery are two separate phenomena and are analyzed by separated.

The decrease in thread tension 100% of PTT, was independent of the oven temperature and decreased linearly with the stretch applied. Although intuitively, it believes that the decrease in tension should increase with stretching applied, the R2 for this correlation is quite high. The PTT voltage decrease decreases approximately 0.5% by% of stretching applied. PET thread behaved in a way similar although there is a definite effect of oven temperature, and the decrease per unit of stretching applied (decrease in 0.9% / 1% stretch applied) is almost double that of PTT. Figure 20 compares the decrease in PTT and PET tension. In In general, PET is superior to low stretch applied, and lower than PTT at high oven temperature and stretching applied. The behavior of the PTT / PET mixture is half between the two pure fibers with less temperature sensitivity of the furnace and 0.7% tension decrease by 1% stretch applied. Tension decreases for PTT / cotton blends, They are independent of thermostabilization conditions.

Spinning Yarn Recovery

PTT recovery was not affected by the oven temperature and increased linearly with increasing applied stretch (0.9% recovery for 1% stretch applied). PET recovery increased marginally with increase in the oven temperature, but the main effect was the stretching applied. Your answer is much more pronounced than for PTT with a 2.2% increase in recovery for every 1% of stretching applied. As indicated in Figure 21, the PTT generally has a 5-10% higher recovery than PET, except when PET has had high levels of stretching applied in a high temperature oven. The thread of the PTT / PET mixture responded as pure PTT without dependence on the oven temperature and apply a strong response to stretching (1.7% increase in recovery for every 1% stretch applied). The results of the PTT / cotton blend were erratic both with the upper oven temperature and with the stretching applied that increases recovery.

Change of properties in the thermostabilization of the thread yarn

One of the main reasons to do this job is to answer the question: "If the thermostabilization of the thread reduces its shrinkage, then how much the stretching, recovery and decreased tension? " To answer this question for this data series it is necessary graphically represent these variables against each other. Since all variables are dependent variables, the relationships are true only for this data set and others in which the dependent variables were changed from it way we did it here. With this warning let us observe the answers:

For him Stretch / change shrinkage by dry heat, increase the stretching (decreases the load to 5% deformation) as decreases shrinkage by dry heat. This is a change favorable since there is no stretch penalty to pay by reducing shrinkage allowing the shrinkage to shrink thread. Although R2 is quite low at 0.47, considering that each point is included, this data is probably a guide to the Pretty reliable trend. The load at 5% decreases 0.01 gpd for every 1% reduction in shrinkage.

The relationship recovery / change of shrinkage by dry heat is unfavorable. Recovery decreases 1.3% for every 1% reduction in dry heat shrink. R2 for this data was a respectable 0.64.

The reduction Voltage / shrinkage change by dry heat is unfavorable with voltage decreases that increase 0.9% for every 1% reduction in shrinkage by dry heat. It is believed that this increase in voltage decrease is responsible for the duration in the Recovery. In any case the shrinkage by dry heat must be reduced only the minimum amount required by the user final.

Example 4 The decrease in intrinsic viscosity (VI) of PTT from 0.92 to 0.82 provides improved extrusion reliability in the PTT fiber production

Filament rupture during extrusion of PTT synthetic fibers severely limits the productivity of Production and product quality. Produce synthetic fibers of PTT with an intrinsic viscosity in the range of 0.72-0.82 helps improve the operability of synthetic fiber production and product quality without a significant reduction in final properties of the fiber.

Reducing the intrinsic viscosity of PTT helps reduce the amount of change in chip viscosity compared to the viscosity of the extruded fiber. It also improves the homogeneity of the polymer melt in the package of yarn. PTT resin with a VI of 0.92 requires systems of more severe spinning package filtration to maintain marginal yields in extrusion. It also helps improve production operability decreasing the number of filaments Broken during production. Such reduction allows the product travel with cooler extrusion temperatures for extruded filaments that have less than 2 denier per filament. Be knows that PTT degrades at mass extrusion temperatures melted above 260 ° C. When synthetic filament of fine denier (filaments with less than 2 dpf) using a VI resin from 0.91 the extrusion temperature of the dough should be increased melt to reduce the viscosity of the melt sufficiently to avoid excessive turbulence of the melt flow and the degradation of the melt which as a result causes the Filaments break during extrusion. Said increase of temperature also reduces the amount of shrinkage in the fiber produced making it easier for the stretching process and / or wound in the bobbins of stable yarn.

Claims (9)

1. A process for manufacturing cut textile fiber from poly (trimethylene terephthalate) (PTT), which has an intrinsic viscosity of 0.55 to 1.0, in the existing equipment for manufacture textile fiber cut from poly (ethylene terephthalate)  (PET), which comprises:

(to)

melt the polymer from PTT at 245 to 253 ° C,

(b)

spin the extruded PTT on thread using at least one row,

(C)

move the spun yarn to a first pickup roller where the distance from the row to the first pickup roller is 4.88 - 6.10 m (16 to 20 feet),

(d)

cool the spun yarn to less than 31 ° C before it reaches the first pickup roller,

(and)

optionally store the thread spinning at a temperature of not more than 31 ° C,

(F)

before the stretching process, precondition the thread under tension at a temperature of at least 60 ° C,

(g)

stretch the thread at a temperature of at least 60 ° C,

(h)

optionally allow the thread stretched relax at a temperature of up to 190 ° C, and

(i)

curl the thread stretched to a temperature from 70 to 120ºC and decrease the denier of the stretched thread fed in 10 to 60 percent per denier, of the denier of the thread fed stretcher used to produce a comparable PET.

2. The process in accordance with the claim 1, wherein the intrinsic viscosity of the PTT is of 0.72 to 0.82. 3. The process in accordance with the claim 1 or 2, wherein the spun yarn is cooled to less than 25 ° C before it reaches the first pickup roller. 4. The compliance process with any of the preceding claims, wherein the step of Relaxation and curly temperature is 70 to 100 ° C. 5. The compliance process with any one of claims 1 to 3, wherein the step of using Relaxation and curly temperature is from 80 to 120ºC. 6. The compliance process with any of the preceding claims, wherein step (i) comprises also use a curling iron volume of 10 to 50 percent more than the volume of the curling iron used to produce comparable PET. 7. The compliance process with any one of the preceding claims, wherein the thread denier Stretched fed is decreased by 40 to 60 percent. 8. A process for manufacturing cut textile fiber from poly (trimethylene terephthalate) (PTT), which has an intrinsic viscosity of 0.55 to 1.0 in existing equipment for manufacture textile fiber cut from poly (ethylene terephthalate) (PET), which comprises:

(to)

melt the polymer from PTT at 245-253 ° C,

(b)

spin the extruded PTT on thread using at least one row,

(C)

move the spun yarn to a first pickup roller where the distance from the row to the first Pickup roller is 4.88 to 61.0 m (16 to 20 feet),

(d)

cool the spun yarn to less than 31 ° C before it reaches the first pickup roller,

(and)

optionally store the thread spinning at a temperature of no more than 31 ° C,

(F)

before the stretching process, precondition the thread under tension at a temperature of at least 60 ° C,

(g)

stretch the thread at a temperature of at least 60 ° C,

(h)

optionally allow the thread stretched relax at a temperature of up to 190 ° C, and

(i)

curl the thread stretched to a temperature from 70 to 120 ° C and use a curling iron volume of 10 to 50 percent more than the volume of the curling iron used to produce PET comparable.

9. The process of compliance with any one of the preceding claims, wherein step (g) implies at least two stretches, the first performed at at least 60 ° C and the second and subsequent stretches, if any, made to a temperature higher than the first to the melting point of the thread