JPH04352812A - Polyester yarn as-spun having small crystal size and high orientation - Google Patents

Abstract

PURPOSE: To obtain the subject polyester yarn having a specific crystal size, a specific optical birefringence, a specific amorphous birefringence and a specific long period spacing, excellent in strength and stability and useful for a tire cord, or the like. CONSTITUTION: This polyester yarn has <=55 Angstroms crystal size, >=0.090 optical birefringence, >=0.060 amorphous birefringence and <=300 Angstroms long period spacing and is obtained by, for example, spinning a polyethylene terephthalate having 0.60-0.87 intrinsic viscosity from an extruder, passing through a slender column 18 of 5-9 m length and winding by a strength- controlled winder 24 at 3,200-4,100 mpm winding speed.

Description

[Detailed description of the invention]

The present invention relates to as-spun polyester yarns having small crystals and high orientation.

Since the development of fibre-forming, melt-spun synthetic polymers, textile manufacturers have undertaken extensive research to find ways to increase the strength and stability of fibers made from these polymers. Ta. In order to open up applications other than textiles to these articles, it is necessary to further increase the strength and stability of the fibers. Such non-textile applications (also known as “industrial applications”) include tire cord; sewing thread; canvas; fabrics, webs, or mats used in roadbed structures; industrial belts; Material; Fabric for building materials; Reinforcement material for hose; Fabric laminate;
and rope; etc. Initially, rayon was used for some of these industrial applications. Later, nylon replaced rayon. In the 1970s, polyesters such as polyethylene terephthalate were introduced as competitors to nylon. Then, around 1985, polyesters with higher performance (ie, higher strength and stability) were developed.

A cursory review of the prior art from several patents reveals that three general areas are being considered as possible ways to increase the strength and stability of synthetic fibers, as discussed below. These general areas are processes related to drawing; processes related to polymers; and processes related to spinning. Hereinafter, the term "drawing" shall refer to the heating and stretching applied to the as-spun yarn. "Treatment to the polymer" shall refer to the treatment applied to the polymer prior to the spinning process. "spinning"
shall refer to the process for forming filaments from polymers (excluding drawing).

The process related to stretching is as follows. No. 3,090,997 discloses multi-stage stretching of polyamide for use as tire cord. The fiber (nylon) is melt spun according to conventional methods. The spun fibers are then drawn in a three-step process (drawing, then heating, then drawing again), resulting in 10.4-11.1 g/denier (gra
m perdenier; gpd) tenacity, 1
2.9-17.1% elongation and 48-71 gpd/1
00% initial modulus
lus;I. M. ) is obtained. No. 3,303,169 discloses a single drawing process for polyamides to obtain high modulus, high tenacity, low shrinkage polyamide yarns. When the spun polyamide is drawn and heated to at least 115°C, it has a tenacity of 5 to 8.7 gpd, an elongation of 16.2 to 30.3%, and an elongation of 28 to 59 gpd.
A yarn with an initial modulus of /100% and a shrinkage of 3.5-15% is obtained.

[0005] US Pat. No. 3,966,867 discloses a two-stage stretching process to obtain polyethylene terephthalate with a relative viscosity of 1.5 to 1.7. In the first stage, the temperature of 70-100℃ and 3.8
Process the fibers with a draw ratio of ~4.2. In the second stage, 2
The fibers are processed at a temperature of 10 to 250<0>C and a draw ratio of 5.6 to 6.1 for the combined first and second draw ratios. The drawn yarn thus obtained is 7.5 to 9.5 gpd
tenacity, about 2-5% elongation at 5gpd load,
It has an elongation at break of 9-15% and a shrinkage rate of 1-4%. In U.S. Pat. No. 4,003,974, yarns (24-
75-250°C while stretching (having an HRV of 28)
, passed over heated take-up rolls, and finally stress-relaxed. This drawn yarn is 7.5-9 gpd
tenacity, about 4% shrinkage, 12-20% elongation at break, and 3-5 gpd yield strength at 7% elongation.

The process for improving yarn properties by treating polymers is as follows. According to U.S. Pat. Nos. 4,690,866 and 4,867,963, the intrinsic viscosity (I.V.
) is greater than 0.90. U.S. Patent No. 4,690,86
According to No. 8, the properties of the as-spun (undrawn) fiber are as follows: elongation at break, 52-193%; birefringence, 0.0626-0.136; crystallinity, 19. 3～3
6.8%. The properties of the drawn fibers are as follows: tenacity, 5.9-8.3 gpd; elongation, 10.1-24.
．． 4%; drying shrinkage rate (210°C), 0.5-10.3%
. According to U.S. Pat. No. 4,867,936, the properties of the drawn fibers are as follows: Tenacity, approximately 8.5 g
pd; elongation at break, approximately 9.9%; shrinkage rate (177°C),
Approximately 5.7%.

The process involved in spinning is as follows. According to U.S. Pat. No. 3,053,611, polyethylene terephthalate after leaving the spinneret has a length of 2 m.
The spinning shaft is heated to 220°C. The fibers are then sprayed with cold water in another shaft. The fibers are wound at a speed of 1,600 meters per minute (mpm) and subsequently drawn to obtain a tenacity of 3.5 gpd.

According to US Pat. No. 3,291,880, polyamide is spun from a spinneret and then heated at about 15°C.
The fibers are then sprayed with live steam. As-spun fibers have low orientation and low birefringence. In US Pat. No. 3,361,859, organic synthetic polymers are spun into fibers. Once the fibers exit the spinneret, they are subjected to "controlled delayed cooling." This cooling is done for the first 7 inches from the spinneret. The temperature at the top (ie, adjacent to the spinneret) is 300°C, and the temperature at the bottom (ie, approximately 7 inches from the spinneret) is 132°C. The as-spun yarn has a small birefringence value (11-35×1
0-3), the properties of the drawn yarn are as follows: tenacity, 6.9-9.4 gpd; initial modulus, 1
07~140gpd/100%; Elongation at break, 7.7~
9.9%.

US Pat. Nos. 3,936,253 and 3
, 969,462, a shroud (0.5 to 2 feet long) heated at a temperature of about 115 to 460°C.
Discloses the use of. In the case of the former patent, the temperature at the top of the shroud is higher than the temperature at the bottom. The properties of the drawn yarn in the former patent are as follows: tenacity, 9.25 gpd; elongation, about 13.5%; shrinkage, about 9.5%. For the latter patent, the temperature in the shroud is constant and the properties of the drawn yarn are as follows: tenacity, 8-11 gpd; elongation at break, 12.5-13.
2%. According to US Pat. No. 3,946,100, fibers are spun from a spinneret and solidified at temperatures below 80°C. The solidified fibers are then reheated to a temperature between the glass transition temperature (Tg) of the polymer and the melting point of the polymer. This heated fiber is heated at 1,000 to 6 per minute.
000 meters are removed from the heating zone. The properties of the spun yarn are as follows: tenacity;
3.7-4.0gpd; initial modulus, 70-76g
pd/100%; birefringence, 0.1188-0.1240
.

According to US Pat. No. 4,491,657, a polyester multifilament yarn is melt spun at high speed and consolidated. Solidification takes place in a zone that includes a heating zone and a cooling zone in succession. The heating zone is a barrel-shaped heater (temperature varies from the melting point of the polymer to 400 °C), whose length is 0
．． It is 2 to 1.0 meters. In the cooling zone, it is cooled to 10 to 40°C by air. The drawn yarn made by the process has the following properties: initial modulus, 90-130 gpd; shrinkage (at 150°C), less than 8.7%. According to US Pat. No. 4,702,871, fibers are spun into a chamber under reduced pressure. The properties of the spun yarn are as follows: strength, 3.7
~4.4gpd; Birefringence, 104.4~125.8(×
10-3); Dry heat shrinkage at 160°C for 15 minutes 4.2
~5.9%.

According to US Pat. No. 4,869,958, fibers are spun and wound without the application of heat. At this point, the fibers have low crystallinity but are highly oriented. The fibers are then heat treated. The properties of the drawn fibers are as follows: Tenacity, 4.9-5.
2gpd; initial modulus, 92.5-96.6gpd
/100%; elongation, 28.5-32.5%.

As can be seen from a consideration of the above patents, although some of the fibers obtained by these various processes have high strength and low shrinkage, none of the above patents provide high tenacity, high initial modulus, and No process is disclosed for producing drawn yarns with low shrinkage. The closest patents disclosing such drawn yarns are U.S. Pat.
No. 95,052, these patents are related patents assigned to the assignee of the present invention. In these patents, polyester filaments (0.5 to 2.0 dl
A polymer having an intrinsic viscosity of /g) is melt spun from a spinneret. The molten filament is passed through a solidification zone,
There, it is uniformly cooled and becomes a solid fiber. This solid fiber is produced under substantial stress (0.015 to 0.15
gpd) stretched from the solidification zone. These as-spun solid fibers have a relatively high birefringence (approximately 9-70 x 10
-3) is shown. The as-spun fibers are then drawn and subsequently subjected to heat treatment. The properties of the drawn filament are as follows: tenacity, 7.5-10 gpd; initial modulus, 110-150 gpd/100%; shrinkage, less than 8.5% in air at 175°C.

The present invention relates to as-spun polyester yarns having small crystals and high orientation. The as-spun polyester yarn of the present invention comprises (a) 55 Å
and (b) an optical birefringence of 0.090 or more, or an amorphous birefringence of 0.060 or more, or 30
It is characterized by having a long period spacing of 0 Å or less.

High tenacity, high initial modulus, low shrinkage drawn yarns, as-spun yarns from which such drawn yarns are made, and processes for spinning such yarns are described below. "Yarn,""filament," or "fiber" shall mean any fiber made from a melt-spuntable organic synthetic polymer. Such polymers include, but are not limited to, polyester and polyamide. However, the present invention is particularly concerned with polyesters such as, for example, polyethylene terephthalate (PET), blends of PET and polybutylene terephthalate (PBT), and PET crosslinked with polyfunctional monomers (eg, pentaerythritol). Any of the above polymers may also contain conventional additives. The intrinsic viscosity of the yarn (for PET-based polymers) is from 0.60 to
It is 0.87. However, the present invention is not concerned with the intrinsic viscosity (I.V.) of the polymer.

Referring to FIG. 1, a spinning apparatus 10 is shown. A conventional extruder 12 for melting the polymer chips is in fluid communication with a conventional spinning beam 14. A conventional spinning pack (spinni) is installed in the spinning beam 14.
ng pack) 16. Puck 16 may be of annular design and filters the polymer by passing it through a layer of fine particles according to methods known in the art. A conventional spinneret (not shown) is incorporated as part of pack 16. The flow rate of polymer through the pack is
It varies from about 10 to 55 pounds/hour. The 55 pound upper limit is dictated solely by the physical dimensions of the pack 16, with larger packs providing more flow. The span denier per filament (dpf) ranges from 3 to 20, with optimal mechanical properties for the yarn appearing between 5 and 13 dpf.

[0016] When the fibers leave the spinneret, they may optionally be cooled with a hot inert gas (eg, air). See US Pat. No. 4,378,325. Typically the gas temperature is 230°C and about 6 standard ft3/
minutes (scfm). If the temperature of the air is too high (ie, above 260° C.), the properties of the spun yarn are significantly reduced. An elongated column 18 connects the spinning beam 1
It is installed in an airtight state just below 4. This column contains an insulated tube with a length of more than 5 m. Column lengths will be discussed in more detail later. The inner diameter of the tube is large enough (eg, 12 inches) to allow all filaments from the spinneret to pass through the length of the tube without any hitch. The column is fitted with multiple conventional band heaters so that the temperature within the tube can be adjusted along its length. The column temperature will be described in detail later. To enable better temperature control, the column is preferably divided into several individual temperature zones. A total of 4 to 7 zones are used. Column 18 is optionally equipped with an air sparger used to regulate the temperature within the column.
sparger) 17. Air sparger 17 is designed to evenly distribute inert gas around the column.

Within the lowermost end of the column 18 is a perforated truncated cone 19 (ie a means for reducing air turbulence).
is attached. Perforated truncated cone 19 (3 feet long, having a diameter equal to the diameter of the tube at its uppermost end and approximately 1 diameter of the tube at its lowermost end)
/2 diameter) is provided with a valved outlet 21 from the lowest end of the tube so that movement in the thread line due to air turbulence is substantially reduced or completely eliminated. used to exhaust air through. The thread lines converge below the bottom of the column. This convergence is achieved by the finish applicator 2
This can be done by 0. The applicator 20 is
It is the first point of contact that the yarn encounters after leaving the spinneret.

The length of the column, the nonconvergence of the individual filaments, and the temperature distribution of the air within the column are of particular importance to the present invention. The temperature distribution is selected such that the fiber is maintained above its Tg over a significant length of the column (eg, at least 3 meters). This temperature can also be maintained over the entire length of the column, but in this case the filament being wound becomes unstable. For practical reasons, therefore, the temperature in the column is lowered to below Tg so that the filament does not undergo further crystal structure changes before being wound up. Preferably, the temperature distribution is selected to represent the temperature distribution that would be obtained within the tube if no external heat was applied. However, the "no external heat applied" situation is impractical due to the large number of variables that affect column temperature. Therefore, the temperature distribution is preferably adjusted in a linear manner to eliminate temperature as a variable in the process.

The air temperature within the column is controlled by using a band heater. Preferably, the column is divided into a plurality of sections, and the air temperature in each section is controlled to a predetermined value. In this way, the temperature within the column can be varied over the length of the column. The temperature in the column can vary from as high as the spinning temperature of the polymer to below the glass transition temperature (Tg) of the polymer (Tg for polyester is about 80°C). The spinning temperature of the polymer is observed near the spinneret, ie, when the molten polymer leaves the spinneret. Preferably, however, the air temperature within the column can be controlled from about 155°C to about 50°C. For winding speeds of 14,000 feet per minute or less, the first section adjacent to the spinneret is adjusted to a temperature of about 155°C and the section furthest from the spinneret is adjusted to a temperature of about 50°C. is preferable.

However, a linear temperature distribution is not the only temperature pattern that provides the beneficial results disclosed herein. At winding speeds above 14,000 fpm (4,300 mpm), the temperature profile (if the column is divided into four separate zones) is as follows: (downwards from the spinneret) zone 1; - Approximately 105-110°C; Second zone - Approximately 110-115
C; third zone - about 125-130C; and fourth zone - about 115-120C. Regarding column length, a column length of at least 5 m (for at least 3 m, the column temperature is above the Tg of the polymer) appears to be necessary for the present invention. Column lengths of 5 to 9 m are suitable for the present invention. A practical upper limit is 9 meters, but it can be increased further if there is enough room in the room. A column length of about 7 m is preferred for optimum tenacity properties.

After exiting column 18, the fibers are converged. This convergence can be achieved by using a finish applicator. After the first application of finish (ie, at finish applicator 20), the yarn is wound onto a pair of godet rolls 22. A second application of finish (i.e., with finish applicator 23) is then applied. The first finish application is performed to reduce static electricity buildup on the fibers. However, this finish often flakes off as the fibers pass through the godet rolls. The finish is therefore reapplied after passing through the godet rolls. The fibers are then passed through a conventional tension controlled winder 24. The winding speed is usually over 3,000 mpm (9,800 fpm), with a maximum speed of 5,800 mpm (19,000 fpm).
pm). A suitable range is approximately 10,500 to 13,
500 fpm (approximately 3,200 to 4,100 mpm). The most preferred range is about 3200-3800 mpm
(10,500 to 12,500 fpm). If the winding speed is less than 9,800 fpm (3,000 mpm), the uniformity of the yarn will decrease.

The as-spun polyester yarn obtained by the above process is generally characterized by having relatively small crystals and having a relatively high degree of orientation. It is believed that these properties of the as-spun yarn enable the achievement of the unique drawn yarn properties described below. To quantify the general properties of as-spun polyester yarns, small crystals are defined in terms of their crystal size (measured in Å) and in terms of orientation: optical birefringence; amorphous birefringence; or crystal birefringence. Additionally, crystal size and long period spacing (long p
The spun polyester yarns are characterized in terms of spacing (distance between crystals). In a broad sense, as-spun polyester yarn is
as having a crystal size of less than 55 Å; and 0.
can be characterized as having optical birefringence greater than 0.090, or amorphous birefringence greater than 0.060, or long period spacing less than 300 Å. More preferably, the as-spun polyester yarn has a crystalline size of about 20 to 55 Å; and an optical birefringence of about 0.090 to 0.140, or an optical birefringence of about 0.060 to 0.100. It can be characterized as having crystalline birefringence, or long period spacing of about 100-250 Å. Most preferably, the as-spun polyester yarn has a crystalline size of about 43-54 Å; and an optical birefringence of about 0.100-0.130, or 0.06
Amorphous birefringence of 0-0.085, or about 140-200
can be characterized as having long period spacing of Å;

As is readily apparent to those skilled in the art,
The crystal size of the spun yarn is approximately 1/3 that of conventional yarn in the optimum winding speed range. Although the crystal size increases with increasing winding speed, it still remains at a small level. The amorphous orientation of spun polyester yarns is considerably higher, about twice as high. This spun yarn has a very high degree of orientation and low shrinkage, so
It could be used without stretching. In addition, the spun polyester yarn has the following properties: a crystalline content (i.e., crystallinity obtained by density measurements) of 10-43%; a spun tenacity of approximately 1.7-5.0 gpd. );1
spun modulus ranging from 0 to 140 gpd/100%; hot air shrinkage from about 5 to 45%; elongation from 50 to 160%.

Next, the spun yarn is drawn (see FIG. 2).
). Either one-stage or two-stage stretching operations can be used. However, two-stage stretching operations have been found to offer little or no advantage. It is possible to couple the spinning operation directly to the drawing operation (ie a spinning/drawing process). As-spun yarn is fed from creel 30 to supply roll 34. The supply roll 34 can be heated from ambient temperature to about 150°C. The fibers are then sent to a take-off roll 38 that can be heated from ambient temperature to about 255°C. If a heating roll is not available, use the hot plate 36 (1
(can be heated from 80°C to 245°C) can be used. A hot plate 36 (with a 6 inch curved contact surface) is located in the drawing zone (ie, between supply roll 34 and take-off roll 38). The take-off speed is in the range 75-300 m/min. A typical draw ratio is about 1.65 (for spun yarn made at about 3,800 m/min). The optimum feed roll temperature (resulting in the highest tensile strength) was found to be about 90°C. The optimum temperature for the take-off roll is approximately 245°C. If a hot plate is used, the optimum temperature is approximately 240-245
It is ℃. Shrinkage caused by high-temperature air can be suppressed to some extent by the temperature of the take-up roll. In general, it is desirable to have little shrinkage. This is because it provides the best stability rating for the processed code. However, at least one end use (eg canvas) requires higher shrinkage of the drawn yarn, and these can be controlled by using lower take-up roll temperatures.

Based on the above explanation, the properties of the drawn fibers can be adjusted as follows: tenacity, 4.
0-10.8 gpd; Elongation, 7-80%; Initial secant modulus, 60-170 gpd/100%; Hot air shrinkage (at 177°C), 6-15%; Denier of 5 bundles, 1
25-1100 (the latter value is obtained by twisting the tows together); denier per filament, 1.5-6 dpf. Such yarns can be used as fiber reinforcement in rubber tires. Polyester (ie, PET) drawn yarns made according to the above process can obtain initial secant moduli greater than 150 gpd/100%. moreover,
These yarns have a shrinkage of less than 8% or a tenacity of greater than 7.5 gpd.

Other preferred embodiments of the drawn polyester yarn are characterized as follows: tenacity, at least 8.5 gpd; initial modulus, at least 15 gpd;
0 gpd/100%; and shrinkage less than 6%. Yet another preferred embodiment of the drawn polyester yarn is characterized as follows: tenacity of at least 10 gp.
d; initial modulus, at least 120 gpd/100
%; and shrinkage rate, less than 6%. Yet another preferred embodiment of the drawn polyester yarn is characterized as follows: tenacity, about 9-9.5 gpd; initial modulus, about 150-158 gpd/100%; and shrinkage, 7.
．． Less than 5%. Any drawn yarn made according to the above process can be used in end uses such as: That is, tire cords; sewing threads; canvas; cloth, webs, or mats used for roadbed structures, etc.; industrial belts; composite materials; fabrics for building materials; reinforcement materials for hoses; fabric laminates; and ropes; etc. There is.

The tests used to illustrate the invention and the examples were conducted as follows. Tenacity is ASTM
Represents "fracture tenacity" as defined in D-2256-80. The initial modulus (or “initial secant modulus”) is determined by ASTM D-2256-80,
Defined by Section 10.3. However, the line indicating the initial linear portion of the stress-strain curve is a secant line that passes through the 0.5% elongation point and the 1.0% elongation point on the stress-strain curve. All other tensile properties are ASTM D-2
256-80. The shrinkage rate (HAS) is
Defined as linear shrinkage in a hot air environment held at 177±1° C. according to ASTM D-885-85.

The density, crystal size, long period spacing, crystal birefringence, and amorphous birefringence are the same as described in US Pat. No. 4,134,882. Specifically, in U.S. Pat. No. 4,134,882, density - column 8, line 60; crystal size - column 9, line 6.
Line; Long Period Spacing - Column 7, Line 62;
Crystal birefringence - column 11, line 12; and amorphous birefringence - 1st
Column 1, line 27; etc. Birefringence (optical birefringence or Δn
) of U.S. Pat. No. 4,101,525, column 5, 4-4.
This is as stated in line 6. “BiCV” is 1
This is the coefficient of variation of optical birefringence between filaments calculated from actual measurements for 0 filaments. Other tests described herein are performed according to conventional methods. The present invention will be explained in more detail with reference to Examples below.

Example 1 In the following series of experiments, a conventional polyester polymer (PET, IV-0.63) was spun. The spinning temperature was increased from 12,500 fpm to 19,000 fpm. The length of the column was 6.4 m and was divided into four temperature controlled zones. Temperature was controlled by measuring the temperature of the air close to the wall at the center of each zone. at a temperature of 285°C and a spinneret with 40 holes (
The polymer was extruded from the spinning beam at a rate of 22.9 lbs/hr using a hole size of 0.009 inches x 0.013 inches. No cooling of the fibers was performed. The spun fibers were heat set without being stretched. The results obtained are shown in Table 1.

[0030]

[Table 1]

Example 2 In the following series of experiments, conventional polyester (P
ET, IV-0.63) was spun. The column temperature was varied as shown in Table 2 (air temperature, center of zone). The length of the column is 6.4 m. A spinneret with 72 holes was used (hole size 0.009 inch x 0.0
The polymer was extruded from the spinning beam at a rate of 23.1 lb/hr at 300° C. (12 in.). The fibers were not cooled. The spun fibers were subsequently drawn as specified in Table 2. The results obtained are shown in Table 2.

[0032]

[Table 2]

In the above series of experiments (ie, the experiments listed in Table 2), No. 4, 5, 6, and 7 represent the invention.

Example 3 In the following series of experiments, conventional polyester (P
ET, IV-0.63) was spun. 10,50 fiber
It was wound up at a rate of 0 fpm. A spinneret with 72 holes was used (hole size was 0.009 inches x 0.01
The polymer was extruded from the spinning beam at a rate of 19.5 lb/hr at 300° C. (2 in.). 6.5 scfm
The fibers were cooled with air at 232°C. The length of the column is 6.4 m and it is divided into four sections, with the following air temperature distribution in descending order: 135 °C in the center of each zone; 111 °C; 9
2°C; and 83°C. The spun yarn has the following properties: denier - 334; tenacity - 4.
09gpd; elongation -71.7%; initial modulus -55
．． 0gpd/100%; Shrinkage rate due to high temperature air -350
11.8% at °F; Uster -1.1
0;I. V. -0.647; FOY - 0.35%; birefringence - 110 x 10-3; and crystallinity - 21.6%. Table 3A shows the effect of draw ratio on the properties of the drawn yarn.

[0035]

[Table 3] A

Table 3B shows the effect of heating method during drawing (draw ratio was 1.65 and the yarn was not stress relaxed).

[0037]

[Table 3] B

Table 3C shows the effect of higher draw temperatures and draw ratios (supply roll temperature is ambient and take-off roll temperature is 240°C).

[0039]

[Table 3]C

Example 4 In the following series of experiments, conventional polyester (P
ET, IV-0.92) was spun. Experiment No. 1-5
So, U.S. Patent Nos. 4,101,525 and 4,195
The fibers were spun and drawn according to the method described in , No. 052. Experiment No. Tests 6 to 9 were carried out as follows. I. V.
PE having a molecular weight of 0.92
The T was dried to a moisture level below 0.001%. The polymer was heated and melted in an extruder to 295° C. and subsequently fed into the spinning pack by means of a metering pump. The spinning pack is an annular design that filters the polymer by passing it through a layer of fine metal particles. After filtration, the polymer was extruded through a spinneret with 80 holes. Each spinneret hole has a circular cross-section, its diameter is 0.457 mm, and the capillary length is 0.610 mm.

A 9 m long insulated heated tube is suitably installed below the spinning pack and the multifilament spinning thread line is threaded through the entire length of this tube and then converged or attached to the guiding surface. come into contact with. For temperature control, the tube was divided into seven zones along its length. Separate controllers were used to set the air temperature in the center of each zone. Using a combination of process heat and external heaters around the tube, individual controller settings were selected to provide a uniform air temperature distribution over the vertical distance down the tube. In a typical situation, the air temperature is 155° C. in the top zone of the tube and decreases in temperature with a nearly uniform gradient to 50° C. in the bottom zone.

Approximately 10 cm below the tube, the thread line contacts the finish applicator. The finish applicator acts as a focusing guide and as the first contact point where the yarns meet. At the exit of the tube, the cross-section of the unconverged yarn is guided by a finishing guide (fini
It is quite small due to its proximity to the sh guide. This allowed the use of extremely small openings, thus minimizing the amount of hot air lost from the tube. After applying the spin finish, the yarn was wound onto a pair of godet rolls and then into a tension controlled winder. The winding speed was typically 3200-4100 mpm.

Drawing of the yarn was carried out in a separate step, in which the as-spun yarn was passed through a set of pretension rolls and into heated feed rolls maintained at a temperature of 80-150°C. The yarn was then drawn between these rolls and a set of take-off rolls held at a set temperature in the range of 180-255°C. A typical draw ratio for spun yarns made at 3800 mpm was 1.65, with samples spun at higher speeds requiring lower draw ratios and lower speeds requiring higher draw ratios, respectively. The results obtained are shown in Table 4.

[0044]

[Table 4]

Example 5 I. V. A polyester having a molecular weight characterized by a molecular weight of 0.92 was dried to a moisture level of less than 0.001%. The polymer was heated and melted in an extruder to 295° C. and subsequently fed into the spinning pack by means of a metering pump. After filtering the polymer through a layer of fine metal particles, 80
The polymer was extruded through a spinneret with 5 holes. The diameter of each hole in the spinneret is 0.457 mm, and the length of the capillary is 0.610 mm. During extrusion, the actual measured I. V. was 0.84. The extruded polymer was spun into a 9 m long heated cylindrical cavity. A nearly linear temperature distribution (gradient) was maintained throughout the length of the tube. The temperature of the air in the center of the top zone was 155°C and the temperature of the air in the center of the bottom zone was 50°C. The bundle of multifilament yarns was not converged until it was in contact with the finishing guide just below the heated tube outlet. From this point, the yarn was fed to a tension controlled winder by a pair of godet rolls. Under these conditions, a series of four spun yarns were prepared at different spinning (winding) speeds. These yarns are listed in Examples A-D in Table 5A.
This is shown in .

In another series of experiments, the heating tube was shortened by removing some of the removable sections. Examples E and F in Table 5A were spun using a 7 m column and a 5 m column. Other polymers with different molecular weights (different I.V.) were also spun according to this system to give Examples G and H. Table 5A
Example I shows the use of lower column temperatures. In this case, from 125℃ to 50℃ toward the bottom of the column.
It has a linear temperature gradient up to ℃. Examples A-I using a supply roll at ambient temperature and a take-off roll at 245°C.
All spun yarns were drawn by a single-stage process. In yet another series of tests, the same spun yarn described in Example A was drawn using different feed roll temperatures. The results obtained by testing these yarns are shown in Examples A, J, and K in Table 5B.

[0047]

[Table 5] A

[0048]

[Table 5] B

Example 6 In the following prison run, a conventional polymer (nylon) was spun according to the process of the present invention and compared to that made by the conventional process. Nylon produced by the process of the present invention was spun under the following conditions:
Throughput - 37 lb/hr; Spinning speed - 2,362 fpm
Denier - 3500; Number of filaments - 68; Relative viscosity of spinning solution - 3.21 (H2SO4) or 68.4 (H
COOH equivalent); cooling air - 72 scfm; winding tension - 80 g; column length - 24 feet; top column temperature - 240°C; bottom column temperature - 48°C. The as-spun properties of this yarn are: Tenacity - 0
．． 95gpd; Elongation -235%; TE1/2-14.6
. The yarn was then drawn under the following conditions: draw ratio -3.03; drawing temperature ~90<0>C. The properties of the drawn yarn are as follows: tenacity - 6.2 gpd; elongation - 70%; TE 1/2 - 52; 10% modulus - 0.
87 gpd; 400°F hot air shrinkage (HAS
) -1.4%.

One comparative nylon was spun under the following conventional conditions: throughput - 23.4 lb/hr; spinning speed - 843 fpm; denier - 5556; number of filaments - 180; Viscosity -3.3 (H2SO
4) or 72.1 (HCOOH equivalent); cooling air -15
0scfm. The yarn was then drawn under the following conditions: draw ratio -2.01; draw temperature 90<0>C. The properties of the drawn yarn are as follows: Tenacity - 3.8g
pd; elongation - 89%; TE1/2-33; 10% modulus - 0.55 gpd. Additional comparative yarns were spun under conventional conditions as follows: throughput - 57.5 lb/hr; spinning speed - 1048 fpm; denier - 1240
0; Number of filaments - 240; Relative viscosity of spinning solution - 42
(HCOOH equivalent); Cooling air - 150 scfm. The yarn was then drawn under the following conditions: draw ratio -3.60; draw temperature 110<0>C. The properties of the drawn yarn are as follows: Tenacity - 3.6 gpd; Elongation - 7
0%; TE1/2-30.1; 10% modulus-0.
8 gpd; HAS (400°F) -2.0%.

Example 7 In the following experiments, low I. V. (For example, 0.63
) and high I. V. (eg, 0.92) was compared to the spun yarn described in US Pat. No. 4,134,882. Examples 1-8 are low I. V. It is polyester (PET) and was produced by the method described in Example 1. Example 9~
11 is a high I. V. It is polyester (PET) and was produced by the method described in Example 5. Examples 12-17
Examples 1, 5, 12 of U.S. Pat. No. 4,134,882
, 17, 36, and 20. For each example, spinning speed (fpm), density (gms/cc), crystal size (Å, 010), long period spacing (L
PS), birefringence, crystalline birefringence, and amorphous birefringence are shown. The results obtained are shown in Table 7.

[0052]

[Table 7]

Although the preferred embodiment of the invention has been described in detail, it will be appreciated by those skilled in the art that various modifications may be made thereto without departing from the spirit and scope of the invention.

[Brief explanation of the drawing]

FIG. 1 is a schematic elevational view showing the spinning process of the present invention.

FIG. 2 is a schematic elevational view showing the drawing process of the present invention.

[Explanation of symbols]

12 Extruder 14 Spinning beam 16 Spinning pack 17 Air sparger 18 Long and narrow column 19 Perforated truncated cone 20, 23 Finishing agent applicator 21 Exhaust port with valve 22 Godet roll 24 Tension control winder

Claims (9)

[Claims] Claim 1: (a) Crystal size of 55 Å or less;
and (b) an optical birefringence of 0.090 or more. 2. (a) a crystal size of about 20-55 Å; and (b) an optical birefringence of about 0.090-0.140;
The as-spun polyester yarn of claim 1 further characterized in that the as-spun polyester yarn comprises: 3. (a) crystal size of about 43-54 Å; and (b) optical birefringence of about 0.100-0.130;
3. The as-spun polyester yarn of claim 2 further comprising: Claim 4: (a) Crystal size of 55 Å or less;
and (b) an amorphous birefringence of 0.060 or more. 5. (a) a crystalline size of about 20-55 Å; and (b) an amorphous birefringence of about 0.060-0.100;
5. The as-spun polyester yarn of claim 4 further characterized in that it has: 6. (a) a crystalline size of about 43-54 Å; and (b) an amorphous birefringence of about 0.060-0.085;
6. The as-spun polyester yarn of claim 5 further comprising: Claim 7: (a) Crystal size of 55 Å or less;
and (b) a long period spacing of 300 Å or less. 8. The as-spun product of claim 7 further characterized in that it has: (a) a crystal size of about 20-55 Å; and (b) a long period spacing of about 100-250 Å. Polyester yarn. 9. The as-spun product of claim 8, further characterized in that it has: (a) a crystal size of about 43-54 Å; and (b) a long period spacing of about 140-200 Å. Polyester yarn.