CA1147917A - Process for improving the elastic recovery of a polyethylene terephthalate fibrous material - Google Patents
Process for improving the elastic recovery of a polyethylene terephthalate fibrous materialInfo
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- CA1147917A CA1147917A CA000359499A CA359499A CA1147917A CA 1147917 A CA1147917 A CA 1147917A CA 000359499 A CA000359499 A CA 000359499A CA 359499 A CA359499 A CA 359499A CA 1147917 A CA1147917 A CA 1147917A
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- fibrous material
- elastic recovery
- annealed
- polyethylene terephthalate
- temperature
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Abstract
Abstract of the Disclosure A process is provided for improving the elastic recovery of a previously oriented fibrous material comprising at least 85 mole percent polyethylene terephthalate by annealing the fibrous material at a temperature of about 180 to about 210°C for a period of about 1 to about 30 minutes, while controlling the length of the fibrous material in a manner sufficient to prevent a longitudinal shrinkage or extension of greater than about 5%. The resulting annealed fiber is then preferably crimped.
Description
~79~
Background of the Invention Historically, the end use performance of carpets provided from Nylon, such as Nylon 6, 6 has been observed to be superior in some respects than carpets provided from polyethyiene terephthalate. A substantial contributing factor to this observed performance differential is believed to be the poor crush resistance of polyethylene terephthalate fibers. Efforts to overcome this de~iciency have been hindered by the lack of clear relationships between crush resistance and material properties such as fiber structure, crimp geometry, and mode of deformation. One of the measurable property differences which is believed to affect the crush resistance of polyethylene terephthalate carpet staple is its elastic recovery, i.e., its length of recovery from moderate strain. The elastic recovery of polyethylene terephthalate fibers tends to be poor particularly when these fibers are subjected to texturizing procedures such as stuffer box crimping and heat setting.
Various methods of improving the elastic recovery of fibers prepared from polymers other than polyethylene terephthalate are illustrated by U.S. Patents Nos. 3,377,415;
3,608,044; 3,330,897 and 3,323,190, and British Patent No.
1,148,022.
Typical heat treatments which have been applied to fibrous materials in the past are illustrated by U.S. Patents Nos. 3,739,056; 3,634,580; 3,595,952; 3,584,103; 3,562,382;
3,562,199; 3,558,761; 3,551,363; 3,546,329; 3,527,862;
3,471,608, and 3,469,001.
11479~7 None o. the above cited patents, however, appears to disclose an acceptable method for improving the elastic recovery of polyethylene terephthalate fibers and products prepared therefrom. Thus, the search has continued for ways to obtain a polyethylene terephthalate fiber having superior elastic recovery properties. The present application is a result of this search.
It is accordingly an object of the present invention to provide a process for preparing an oriented polyethylene terephthalate fibrous material having improved elastic recovery.
These and other objects as well as the scope, nature and utilization of the invention will be apparent to those skilled in the art from the following description and appended claims.
~47~17 Summary of the Invention In one aspect of the present invention, there is provided a process for improving the elastic recovery of a previously oriented fibrous material having a birefringence of at least 0.10 and comprising~at least 85 mole percent polyethylene terephthalate which comprises annealing said fibrous material at a temperature o~ about 180 to about 210C for a period of time of about 1 to about 30 minutes while controlling the length thereof in a manner sufficient to prevent a longitudinal shrinkage or extension of said fibrous material greater than about 5%, said annealed fibrous material having an elastic recovery at 3 minute recovery time of a least 70~ when stretched to about 8~ of its original length.
In another aspect of the present invention, the above described process contains the additional step of crimping and heat setting the annealed fibrous material.
~47~17 Description of the Preferred Embodiments The elastic recovery (ER) of a previously oriented fibrous material is improved by annealing said fibrous material at a specifically defined temperature while under a specifically defined strain for`a specifically defined length of time.
More specifically, the fibrous material utilized in accordance with the process of the present invention is provided from a polymer comprising at least 85 mole percent, preferably about 90 to 100 mole percent polyethylene tereph-thalate. Thus, although it is preferred that the fibrous material constitute a homopolyester wherein the acid component is derived from terephthalic acid and the glycol component is derived from ethylene glycol, co-polyesters wherein the glycol component further includes minor amounts of other glycols such as diethylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, etc., and the acid component further includes minor amounts of other dicarboxylic acids such as isophthalic acid, hexahydro-terephthalic acid, bibenzoic acid, adipic acid, sebacic acid, azelaic acid, etc., may also be employed.
The molecular weight of the polyethylene tereph-thalate should be such that the polymer can be melt spun.
Thus, the inherent viscosity as determined from a .1%,by solution weight,of a solution of the polymer in orthochloro-phenol at 25C, should not be less than about 0.6 deciliters per gram (dl/gm) and can vary from about0.6 to about 0.95 dl/gm.
~7~3~7 The fiber forming polymer (e.g., polyethylene terephthalate) used to prepare the fibrous material is provided in a fibrous configuration by mel~ spinning the polymer in accordance with any of the accepted melt spinning techniques known in the art.
The "orientation" possessed by the fibrous material before undergoing the controlled anneal treatment of the present invention is characterized in terms of birefringence and is herein defined to be that which is sufficient to impart a birefringence to said fibrous material of at least 0.10, preferably from about 0.16 to about 0.20, and most preferably from about 0.17 to about 0.18.
The birefringence of the fibrous material is determined in accordance with the procedures outlined in U. S. Patent No. 3,681,188.
Typically, the required degree of orientation may be achieved by any method known to those skilled in the art, depending on the manner in which the fibrous material is prepared.
Thus, for example, in accordance with known proce-dures of the prior art, filaments may be melt spun under low stress conditions wherein the molten polyester is extruded through the orifices of a spinneret to form filaments which are initially taken up while exerting a relatively low stress on the same. The as-spun fibers typically possess a very low birefringence, typically about .001 to .005.
The as-spun fibers are then commonly subjected to a subsequent hot drawing step which may or may not be carried 7~7 out in-line to achieve the desired degree of orientation suitable for the purposes of the present invention. Thus, typical drawing temperatures employed in the separate hot drawing step will generally not be below the glass transition temperature of the polymer and commonly may range ~rom ahout 70 to about 180C, preferably from about 80 to about 110C.
The draw ratio generally employed during the separate hot drawing step on a filament having a denier per filament (dpf) of about 1 to about 30 typically can vary from about 3:1 to about 5:1, and preferably from about 4:1 to about 5:1. Such hot drawing of as-spun polyethylene terephthalate filaments is commonly conducted upon contact with an appropriate heating device, heated gaseous atmosphere, or heated liquid medium.
In certain other instances, it may be desirable to achieve orientation by melt extruding the polyester through the orifices of a spinneret to form filaments which are initially taken up at a relatively high stress induced by a high take-up speed, e.g., 1000 to 6000 meters per minute, as illustrated by ~.S. Patent No. 3,946,100. This procedure eliminates the necessity for an additional drawing step to achieve orientation of the type described herein.
Regardless of the method adopted for achieving orientation, it is well within the skill of the art to adjust spinning variables, such as the viscosity of the polymer melt as extruded through the spinneret hole, the viscosity of the filament as it changes from molten to solid state in the thread line, temperature regulation, rate of .. .. . ..
extrusion, and windup speed, under any one set of conditions of polymer type, and geometry of the spinneret, in a manner sufficient to achieve the orientation possessed by the fibrous material employed in the present invention.
Typically, the oriented fibrous material will possess a denier per filament of about 1 to about 30, prefer-ably from about 6 to about 20, and most preferably from about 10 to about 16.
The temperature at which the previously oriented fibrous material is annealed can vary from about 180 to about 210C, preferably from about 190 to about 205C, and most preferably from about 195 to about 202C. When the temperature employed is below about 180C the improvement in elastic recovery, if any, is negligible.
If the annealing temperature exceeds about 210C, the fibers will lose orientation to some extent.
The annealing procedure may be carried out, for example, in an oven heated to the appropriate temperature.
Alternatively, the annealing may be achieved by a continuous run of the yarn or bundle of filaments. Such heat treatment may be by means of hot fluid heat transfer medium, such as superheated steam, nitrogen, carbon dioxide, air and the like and mixtures thereof (e.g., using a jacketed tube or shroud), by infrared rays, by dielectric heating or by direct contact of the running yarn or bundle with a heated metal surface, preferably curved to make good contact.
The duration of exposure to the annealing tempera-tures can vary from about 1 to about 30 minutes ~e.g., 5 to about 30 minutes), preferably from about 10 to about 25 minutes, and most preferably from about 18 to about 22 minutes depending on efficiency of the heat transfer media.
When the previously oriented fibrous material is subjected to the annealing procedures outlined above, it will have a propensity to shrink or collapse in the direction of its length. It has been found that in order to achieve the improvements in elastic recovery, the length of the fibrous material during the annealing procedure must be controlled in a manner sufficient to prevent a longitudinal shrinkage or extension of greater than about 5%, based on the original length of the fibrous material prior to annealing. Preferably the fibrous material is maintained at constant length.
The required control of length of the fibrous material exercised during the annealing process necessary to achieve the improvement in elastic recovery may be achieved by any means known to those skilled in the art.
Thus, the previously oriented fibrous material can be conveyed in the direction of its length from a first stress isolation device through an annealing zone where it is annealed in the manner described to a second stress isolation device located at the exit of the annealing zone.
Each stress isolation device may conveniently take the form of a pair of skewed rolls.
Accordingly, the previously oriented fibrous material may be wound several times about the first pair of skewed rolls, passed through the annealing zone and wound several times about the second pair of skewed rolls. This arrangement permits isolation and control of the stress induced by shrinkage between the two pairs of rolls, of the fibrous material as it undergoes the anneal treatment.
~47917 Consequently, by manipulating the speed ratio, i.e., the differential ratio of the surface speed of the rollers at the exit of the annealing zone to the surface speed of the rollers at the entrance of the annealing zone, the length of the fibrous material can be controlled in the manner required.
Thus, with a speed ratio of 1.0, the surface speeds of the two sets of rollers are equivalent, and the fibrous mateFial will be maintained at constant length (i.e., 0% shrinkage). When the speed ratio is less than 1.0, the fibrous material will undergo relaxation to some degree depending on how low the speed ratio is set. Conversely, if the speed ratio is greater than 1.0 the fibrous material will be stretched during passage through the annealing zone.
In order to ohtain the proper control of shrinkage of the fibrous material during annealing, the speed ratio thereof as it passes through the annealing zone can vary from about .95 to about 1.05, preferably from about .97 to about 1.02 and most preferably about 1Ø
It is appropriate to mention that when speed ratios of less than 1 are employed the specific speed ratio is selected so that the propensity of the fibrous material to shrink is always greater than the degree of relaxation permitted. Consequently at speed ratios of 1 or less, although no direct or active tension is applied to the fibrous material, such materials may be said to be under a passive tension which is exerted by the internal stress of restrained shrinkage of the fibrous material itself.
~ ~7~7 If the degree of shrinkage of the fibrous material exceeds about 5% the fibrous material will lose some of its orientation and will become progressively more brittle.
If the fibrous material is stretched under tension beyond 5% of its original length, such extension can have the effect of redrawing the fibrous material and thereby enhance the sensitivity thereof to variations in dye uptake induced by false twist texturing.
The term "fiber" as used in this specification includes continuous filaments, yarns made from the latter materials and tows.
Elastic recovery is a criterion for characterizing the ability of a fiber to return to its original length when it is relaxed after being subjected to cyclic or repeated strain of the original length of the fiber. The elastic recovery value of a fiber can be determined in a conventional manner with the use of an Instron Tensile Tester at a strain rate of 10 percent/minute.
Accordingly, a fiber having a given length, e.g.,
Background of the Invention Historically, the end use performance of carpets provided from Nylon, such as Nylon 6, 6 has been observed to be superior in some respects than carpets provided from polyethyiene terephthalate. A substantial contributing factor to this observed performance differential is believed to be the poor crush resistance of polyethylene terephthalate fibers. Efforts to overcome this de~iciency have been hindered by the lack of clear relationships between crush resistance and material properties such as fiber structure, crimp geometry, and mode of deformation. One of the measurable property differences which is believed to affect the crush resistance of polyethylene terephthalate carpet staple is its elastic recovery, i.e., its length of recovery from moderate strain. The elastic recovery of polyethylene terephthalate fibers tends to be poor particularly when these fibers are subjected to texturizing procedures such as stuffer box crimping and heat setting.
Various methods of improving the elastic recovery of fibers prepared from polymers other than polyethylene terephthalate are illustrated by U.S. Patents Nos. 3,377,415;
3,608,044; 3,330,897 and 3,323,190, and British Patent No.
1,148,022.
Typical heat treatments which have been applied to fibrous materials in the past are illustrated by U.S. Patents Nos. 3,739,056; 3,634,580; 3,595,952; 3,584,103; 3,562,382;
3,562,199; 3,558,761; 3,551,363; 3,546,329; 3,527,862;
3,471,608, and 3,469,001.
11479~7 None o. the above cited patents, however, appears to disclose an acceptable method for improving the elastic recovery of polyethylene terephthalate fibers and products prepared therefrom. Thus, the search has continued for ways to obtain a polyethylene terephthalate fiber having superior elastic recovery properties. The present application is a result of this search.
It is accordingly an object of the present invention to provide a process for preparing an oriented polyethylene terephthalate fibrous material having improved elastic recovery.
These and other objects as well as the scope, nature and utilization of the invention will be apparent to those skilled in the art from the following description and appended claims.
~47~17 Summary of the Invention In one aspect of the present invention, there is provided a process for improving the elastic recovery of a previously oriented fibrous material having a birefringence of at least 0.10 and comprising~at least 85 mole percent polyethylene terephthalate which comprises annealing said fibrous material at a temperature o~ about 180 to about 210C for a period of time of about 1 to about 30 minutes while controlling the length thereof in a manner sufficient to prevent a longitudinal shrinkage or extension of said fibrous material greater than about 5%, said annealed fibrous material having an elastic recovery at 3 minute recovery time of a least 70~ when stretched to about 8~ of its original length.
In another aspect of the present invention, the above described process contains the additional step of crimping and heat setting the annealed fibrous material.
~47~17 Description of the Preferred Embodiments The elastic recovery (ER) of a previously oriented fibrous material is improved by annealing said fibrous material at a specifically defined temperature while under a specifically defined strain for`a specifically defined length of time.
More specifically, the fibrous material utilized in accordance with the process of the present invention is provided from a polymer comprising at least 85 mole percent, preferably about 90 to 100 mole percent polyethylene tereph-thalate. Thus, although it is preferred that the fibrous material constitute a homopolyester wherein the acid component is derived from terephthalic acid and the glycol component is derived from ethylene glycol, co-polyesters wherein the glycol component further includes minor amounts of other glycols such as diethylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, etc., and the acid component further includes minor amounts of other dicarboxylic acids such as isophthalic acid, hexahydro-terephthalic acid, bibenzoic acid, adipic acid, sebacic acid, azelaic acid, etc., may also be employed.
The molecular weight of the polyethylene tereph-thalate should be such that the polymer can be melt spun.
Thus, the inherent viscosity as determined from a .1%,by solution weight,of a solution of the polymer in orthochloro-phenol at 25C, should not be less than about 0.6 deciliters per gram (dl/gm) and can vary from about0.6 to about 0.95 dl/gm.
~7~3~7 The fiber forming polymer (e.g., polyethylene terephthalate) used to prepare the fibrous material is provided in a fibrous configuration by mel~ spinning the polymer in accordance with any of the accepted melt spinning techniques known in the art.
The "orientation" possessed by the fibrous material before undergoing the controlled anneal treatment of the present invention is characterized in terms of birefringence and is herein defined to be that which is sufficient to impart a birefringence to said fibrous material of at least 0.10, preferably from about 0.16 to about 0.20, and most preferably from about 0.17 to about 0.18.
The birefringence of the fibrous material is determined in accordance with the procedures outlined in U. S. Patent No. 3,681,188.
Typically, the required degree of orientation may be achieved by any method known to those skilled in the art, depending on the manner in which the fibrous material is prepared.
Thus, for example, in accordance with known proce-dures of the prior art, filaments may be melt spun under low stress conditions wherein the molten polyester is extruded through the orifices of a spinneret to form filaments which are initially taken up while exerting a relatively low stress on the same. The as-spun fibers typically possess a very low birefringence, typically about .001 to .005.
The as-spun fibers are then commonly subjected to a subsequent hot drawing step which may or may not be carried 7~7 out in-line to achieve the desired degree of orientation suitable for the purposes of the present invention. Thus, typical drawing temperatures employed in the separate hot drawing step will generally not be below the glass transition temperature of the polymer and commonly may range ~rom ahout 70 to about 180C, preferably from about 80 to about 110C.
The draw ratio generally employed during the separate hot drawing step on a filament having a denier per filament (dpf) of about 1 to about 30 typically can vary from about 3:1 to about 5:1, and preferably from about 4:1 to about 5:1. Such hot drawing of as-spun polyethylene terephthalate filaments is commonly conducted upon contact with an appropriate heating device, heated gaseous atmosphere, or heated liquid medium.
In certain other instances, it may be desirable to achieve orientation by melt extruding the polyester through the orifices of a spinneret to form filaments which are initially taken up at a relatively high stress induced by a high take-up speed, e.g., 1000 to 6000 meters per minute, as illustrated by ~.S. Patent No. 3,946,100. This procedure eliminates the necessity for an additional drawing step to achieve orientation of the type described herein.
Regardless of the method adopted for achieving orientation, it is well within the skill of the art to adjust spinning variables, such as the viscosity of the polymer melt as extruded through the spinneret hole, the viscosity of the filament as it changes from molten to solid state in the thread line, temperature regulation, rate of .. .. . ..
extrusion, and windup speed, under any one set of conditions of polymer type, and geometry of the spinneret, in a manner sufficient to achieve the orientation possessed by the fibrous material employed in the present invention.
Typically, the oriented fibrous material will possess a denier per filament of about 1 to about 30, prefer-ably from about 6 to about 20, and most preferably from about 10 to about 16.
The temperature at which the previously oriented fibrous material is annealed can vary from about 180 to about 210C, preferably from about 190 to about 205C, and most preferably from about 195 to about 202C. When the temperature employed is below about 180C the improvement in elastic recovery, if any, is negligible.
If the annealing temperature exceeds about 210C, the fibers will lose orientation to some extent.
The annealing procedure may be carried out, for example, in an oven heated to the appropriate temperature.
Alternatively, the annealing may be achieved by a continuous run of the yarn or bundle of filaments. Such heat treatment may be by means of hot fluid heat transfer medium, such as superheated steam, nitrogen, carbon dioxide, air and the like and mixtures thereof (e.g., using a jacketed tube or shroud), by infrared rays, by dielectric heating or by direct contact of the running yarn or bundle with a heated metal surface, preferably curved to make good contact.
The duration of exposure to the annealing tempera-tures can vary from about 1 to about 30 minutes ~e.g., 5 to about 30 minutes), preferably from about 10 to about 25 minutes, and most preferably from about 18 to about 22 minutes depending on efficiency of the heat transfer media.
When the previously oriented fibrous material is subjected to the annealing procedures outlined above, it will have a propensity to shrink or collapse in the direction of its length. It has been found that in order to achieve the improvements in elastic recovery, the length of the fibrous material during the annealing procedure must be controlled in a manner sufficient to prevent a longitudinal shrinkage or extension of greater than about 5%, based on the original length of the fibrous material prior to annealing. Preferably the fibrous material is maintained at constant length.
The required control of length of the fibrous material exercised during the annealing process necessary to achieve the improvement in elastic recovery may be achieved by any means known to those skilled in the art.
Thus, the previously oriented fibrous material can be conveyed in the direction of its length from a first stress isolation device through an annealing zone where it is annealed in the manner described to a second stress isolation device located at the exit of the annealing zone.
Each stress isolation device may conveniently take the form of a pair of skewed rolls.
Accordingly, the previously oriented fibrous material may be wound several times about the first pair of skewed rolls, passed through the annealing zone and wound several times about the second pair of skewed rolls. This arrangement permits isolation and control of the stress induced by shrinkage between the two pairs of rolls, of the fibrous material as it undergoes the anneal treatment.
~47917 Consequently, by manipulating the speed ratio, i.e., the differential ratio of the surface speed of the rollers at the exit of the annealing zone to the surface speed of the rollers at the entrance of the annealing zone, the length of the fibrous material can be controlled in the manner required.
Thus, with a speed ratio of 1.0, the surface speeds of the two sets of rollers are equivalent, and the fibrous mateFial will be maintained at constant length (i.e., 0% shrinkage). When the speed ratio is less than 1.0, the fibrous material will undergo relaxation to some degree depending on how low the speed ratio is set. Conversely, if the speed ratio is greater than 1.0 the fibrous material will be stretched during passage through the annealing zone.
In order to ohtain the proper control of shrinkage of the fibrous material during annealing, the speed ratio thereof as it passes through the annealing zone can vary from about .95 to about 1.05, preferably from about .97 to about 1.02 and most preferably about 1Ø
It is appropriate to mention that when speed ratios of less than 1 are employed the specific speed ratio is selected so that the propensity of the fibrous material to shrink is always greater than the degree of relaxation permitted. Consequently at speed ratios of 1 or less, although no direct or active tension is applied to the fibrous material, such materials may be said to be under a passive tension which is exerted by the internal stress of restrained shrinkage of the fibrous material itself.
~ ~7~7 If the degree of shrinkage of the fibrous material exceeds about 5% the fibrous material will lose some of its orientation and will become progressively more brittle.
If the fibrous material is stretched under tension beyond 5% of its original length, such extension can have the effect of redrawing the fibrous material and thereby enhance the sensitivity thereof to variations in dye uptake induced by false twist texturing.
The term "fiber" as used in this specification includes continuous filaments, yarns made from the latter materials and tows.
Elastic recovery is a criterion for characterizing the ability of a fiber to return to its original length when it is relaxed after being subjected to cyclic or repeated strain of the original length of the fiber. The elastic recovery value of a fiber can be determined in a conventional manner with the use of an Instron Tensile Tester at a strain rate of 10 percent/minute.
Accordingly, a fiber having a given length, e.g.,
2", is placed between the stationary jaw and the moveable cross-head of the Instron. The distance between the stationary jaw and the cross-head at this point is referred to as the original fiber length or Eo~ The cross-head then stretches the fiber at a constant rate (i.e., 10~/min.) to a given stress, i.e., 8% extension, based on the initial fiber length and the fiber is maintained at this extension for one minute. The distance between the stationary jaw and the cross-head at this point is referred to as El. The cross-head is then moved in the opposite direction at the same ~1~79~7 rate as the extension rate until the distance between the stationary jaw and the cross-head is the same as at the start of the test i.e., Eo~ Since the fiber will generally be irreversibly stretched to a certain extent the fiber will not return to its initial length and the fiber will be slack and under no stress. The extent to which the fiber is irreversibly stretched is referred to as the "length added"
or E2. The "length added" is determined by waiting three minutes after the cross-head has returned to its Eo position and extending the fiber again at the same constant rate to the initial extension i.e., E2. As the cross-head is extended in this manner the slack in the fiber will be taken up and the stress on the fiber will begin to increase from zero up to some finite number. The distance between the cross-head and the stationary jaw at the point at which the stress upon re-extension increases above zero is referred to as E3 and the difference between E3 and Eo is identified as the length added or E2. The elastic recovery is then determined from the equation:
(E1 - Eo) - E
Elastic Recovery = (E1 - Eo) x loo Measurements with the Instron are made at room temperature (i.e., 25C) and are carried out in air at 65 percent relative humidity.
The oriented fibrous material which has been annealed in accordance with the process of the present invention exhibits an elastic recovery after a 3 minute recovery time, when stretched up to 8~ of its original length, of at least 70%, typically from about 75% to about - :~ ~5 ,. . r .
~1~7~7 90%, and preferably from about 75 to 85%, and most preferably from about 77 to about 82%.
The process of the present invention is particularly applicable to fibers which are subsequently texturized such as by crimping and heat setting. Typically such procedures adversely affect the elastic re~overy of polyethylene tereph-thalate fibers. The particular texturizing technique will generally depend on the ultimate use for which the fibers will eventually be employed.
Fibers intended for use in carpets are generally provided with a random crimp and subsequently heat set in any manner known to be acceptable in the art.
Thus, the crimping process can preferably be achieved by feeding the fibers into a stuffer box faster than they are removed. This allows the fibers to relax.
The geometry of the stuffer box, the crimp temperature, and degree of overfeed generally determines the degree of deformation.
While the fibers are in a relaxed stage in the stuffer box they are subjected to elevated temperatures of about 85 to 110C, preferably from about 90 to about 105C, and most preferably from about 95 to about 100C for a period of at least 0.2 seconds, preferably from about 0.4 to about 1.5 seconds, and most preferably from about 0.5 to about 0.8 seconds.
The fibers are heated to the desired temperature by contacting them with a fluid heat transfer medium, which is chemically unreactive toward the fibers at the temperature employed, such as saturated steam. Other suitable heat -~L~
~147917 transfer mediums include air, nitrogen, carbon dioxide and the like and mixtures thereof. Steam is the preferred heat transfer medium since it is an efficient conductor of heat.
In certain other instances, (e.g., fiber utility other than carpet yarn) the crimping may be achieved by false twisting which is a technique well known in the art.
The fibers are then removed from the stuffer box and heat set by drying them while in a relaxed condition with a suitable heat transfer medium at temperatures of about 140 to about 200C, preferably from about 150 to about 190C, and most preferably from about 155 to about 165C.
Thus, the heat employed during the heat set procedure is dry heat. Heat setting helps to insure a uniform fiber structure and improves subsequent processing operations.
Suitable heat transfer fluids utilized during heat setting include dry inert gases such as air, carbon dioxide, nitrogen and the like or mixtures thereof.
The annealed fibrous material which is subsequently crimped (i.e., stuffer box) and heat set in the manner described above, although evidencing a slight drop in elastic recovery, will still exhibit an elastic recovery at three minutes recovery time when stretched up to 8~ of its original length, of at least about 70~, typically from about 72~ to about 85~, preferably from about 73 to about 78%, and most preferably from about 75 to about 77~.
The polyethylene terephthalate fibers having improved elastic recovery which are prepared in accordance with the present invention have utility as yarns in carpets, V-belts, sewing thread and textile apparels, e.g., hosiery foundation.
-.. ....
~79~7 The invention is additionally illustrated in connection with the following Examples, which are to considered as illustrative of the present invention. It should be understood, however, that the invention is not limited to the specific details of the Examples.
Unless otherwise indi`cated, all percentages or proportions of materials mentioned in the specification and appended claims are by weight.
,: ~ ~
11479~7 Polyethylene terephthalate having an intrinsic viscosity (I.V.) of 0.67 dl/gm is selected as the starting material. The instrinsic viscosity is determined from a solution of 0.1 gram of the polymer in 100 ml. of ortho-chlorophenol at 25C.
The polyethylene terephthalate is melt extruded through a spinneret having 20 extrusion holes each having a diameter of 20 mils. The molten polyethylene terephthalate is at a temperature of about 300C when extruded through the spinneret. The resulting extruded polyethylene terephthalate is passed directly through a solidification zone having a length of about 6 feet and a vertical disposition for a residence ~ime of about 0.045 seconds. While passing through the solidification zone the extruded polyethylene terephthalate is uniformly quenched with air at room temperature (e.g., about 25) which is continuously introduced and withdrawn from said solidification zone. The polyethylene terephthalate is thereby transformed into a continuous length of as-spun polyethylene terephthalate yarn. The resulting polyethylene terephthalate yarn is under constant tension following extrusion and is withdrawn from the solidification zone at a rate of about 3000 meters per minute (m/m) while under a stress of about 0.2 grams per denier. The extruded filamentary material is drawn down at a ratio of about 100:1. The resulting polyethylene terephthalate yarn exhibits a denier per filament (dpf) of 8 with each filament having a birefrin-gence of about 0.05.
~ ~ ~79~7 ~ ecause the yarn possesses a birefringence below n. lo it must undergo an additional orientation step. Thus, the polyethylene terephthalate yarn is subsequently drawn at a temperature of about 125C at a draw ratio of about 2:1.
The resulting oriented polyethylene terephthalate yarn exhibits a birefringence of about 0.16.
The resulting polyethylene terephthalate yarn is passed at constant length through a steam chamber having an outer jacket or pipe and an inner tube with a plurality of openings along the length of the latter. The fibrous material is maintained at constant length by passing the yarn over and about a first pair of skewed rolls located at the entrance to the steam chamber, through the steam chamber and over and about a second pair of skewed rolls located at the exit of the steam chamber. The speed ratio of the first and second pair of rolls is 1Ø Steam is passed into the space between the outer pipe and the inner tube and through the openings of the inner tube thereby impinging on the yarn which con-tinuously enters and exits the inner tube. The steam in the steam chamber is provided at a pressure sufficient to maintain the temperature of the steam as it impinges on or contacts the yarn at about 200C. The residence time during which the yarn is in contact with the superheated steam is 15 minutes.
The resulting annealed yarn is then tested for elastic recovery in the manner described above and the result is provided at Table I.
~, ~1~7~7 Example 1 is repeated with the exception that the as-spun yarn is withdrawn from the solidification zone at a rate of about 1000 meters per minute while under a low stress of about 0.02 grams per `denier and drawn down at a ratio of about 1.5:1.
Consequently, as a result of the low draw ratio the yarn must undergo an additional orientation step. Thus, the polyethylene terephthalate yarn is subsequently drawn at a temperature of about 90C at a draw ratio of about 4:1.
The resulting oriented polyethylene terephthalate yarn exhibits a denier per filament of about 5 with each filament having a birefringence of about 0.17.
The elastic recovery of the yarn is tested in accordance with the procedure outlined above and the result is provided at Table I.
~1~L79~7 Example 1 is repeated with the exception that upon being withdrawn from the solidification zone the continuous length of polyethylene terephthalate yarn is immediately passed through a vertically disposed conditioning zone having a length of about 12 feet. In accordance with the procedures outlined in U.S. Patent No. 3,946,100 a static air atmosphere is maintained in the conditioning zone at a temperature of about 120C by ~he aid of a band heater which surrounds the walls of the same. The poIyethylene tereph-thalate yarn is present in the conditioning zone for a residence time of about 0.001 second. The polyethylene terephthalate yarn is under constant tension following extrusion and is withdrawn from the conditioning zone at a rate of 30G0 meters per minute while under a stress of about 0.2 gram per denier. Upon withdrawal from the conditioning zone the polyethylene terephthalate yarn is drawn down at a ratio of about 1400:1. The resulting polyethylene tereph-thalate yarn exhibits a denier per filament of 7.5 with each filament having a birefringence of about 0.11.
The elastic recovery of the yarn is tested in accordance with the procedures outlined above and the result is provided at Table I.
~147~17 EXAMPLES 4, 5 AND 6 ExaQples 1,-2 and 3 are repeated and the respective yarn samples resulting therefrom are crimped in a stuffer box in a completely relaxed state (i.e., free to shrink) for a period of about 10 seconds while in contact with steam maintained at a temperature of about 100C. Each yarn sample is then heat set at a temperature between 150 and 170C for a period of about 20 minutes. The resulting crimped and heat set yarn samples originally prepared in accordance with Examples 1, 2 and 3 are designated Examples 4, 5 and 6, respectively, and are tested for elastic recovery at 3 minutes recovery time when stretched to 8% of their original length. The results of the elastic recovery tests are summarized in Table II.
' ' 5`~
~.~47~
COMPARATIVE EXAMPLES 1, 2 AND 3 __ Examples 1, 2 and 3 are repeated and designated Comparative Examples 1, 2 and 3, respectively, with the exception that the yarn is free to shrink as it is passed through the steam chamber. The~respective elastic recovery values o~ the respective yarns are summarized at Table I.
~ ?
~147~17 COMPARATIVE EXAMPLES 4, 5 AND 6 Exa~ples 1, 2 and 3 are repeated and designated Comparative Examples 4, 5 and 6, respectively, with the exception that the respective yarns are not annealed in the steam chamber under controlled length conditions and are tested for elastic recovery as they exist just prior to passing into the steam chamber. The results of elastic recovery are summarized at Table I.
As may be seen from the data provided at Table I, the fibers annealed under controlled length conditions exhibit an elastic recovery which is substantially improved over their counterpart samples used in Comparative Examples 1 to 6.
.
~' ~
~1479~
COMPARATIVE EXAMPLES 7, 8 AND 9 -Examples 4, 5 and 6 are repeated and designated Comparative Examples 7, 8 and 9, respectively, Wit]l the exception that the respective yarns are not annealed under controlled length conditions in~a steam chamber but are immediately crimped and heat set after the orientation and are tested for elastic recovery at 3 minute recovery time when stretched to 8% of the original length. The results of elastic recovery are summarized at Table II.
As may be seen from the data of Table II the elastic recovery of the samples annealed under conditions of controlled length is substantially improved over the counter-part samples which have not been annealed.
1~47917 TABLE I
EFFECT OF CONTROLLED ANNEAL TREATMENT
(200C 15 MINUTES) ON ELASTIC RECOVERY
OF POLYETHYLENE TEREPHTIIALATE YARNS
Examples Elastic Recovery Tension 1 70 CL*
2 81 CL*
or E2. The "length added" is determined by waiting three minutes after the cross-head has returned to its Eo position and extending the fiber again at the same constant rate to the initial extension i.e., E2. As the cross-head is extended in this manner the slack in the fiber will be taken up and the stress on the fiber will begin to increase from zero up to some finite number. The distance between the cross-head and the stationary jaw at the point at which the stress upon re-extension increases above zero is referred to as E3 and the difference between E3 and Eo is identified as the length added or E2. The elastic recovery is then determined from the equation:
(E1 - Eo) - E
Elastic Recovery = (E1 - Eo) x loo Measurements with the Instron are made at room temperature (i.e., 25C) and are carried out in air at 65 percent relative humidity.
The oriented fibrous material which has been annealed in accordance with the process of the present invention exhibits an elastic recovery after a 3 minute recovery time, when stretched up to 8~ of its original length, of at least 70%, typically from about 75% to about - :~ ~5 ,. . r .
~1~7~7 90%, and preferably from about 75 to 85%, and most preferably from about 77 to about 82%.
The process of the present invention is particularly applicable to fibers which are subsequently texturized such as by crimping and heat setting. Typically such procedures adversely affect the elastic re~overy of polyethylene tereph-thalate fibers. The particular texturizing technique will generally depend on the ultimate use for which the fibers will eventually be employed.
Fibers intended for use in carpets are generally provided with a random crimp and subsequently heat set in any manner known to be acceptable in the art.
Thus, the crimping process can preferably be achieved by feeding the fibers into a stuffer box faster than they are removed. This allows the fibers to relax.
The geometry of the stuffer box, the crimp temperature, and degree of overfeed generally determines the degree of deformation.
While the fibers are in a relaxed stage in the stuffer box they are subjected to elevated temperatures of about 85 to 110C, preferably from about 90 to about 105C, and most preferably from about 95 to about 100C for a period of at least 0.2 seconds, preferably from about 0.4 to about 1.5 seconds, and most preferably from about 0.5 to about 0.8 seconds.
The fibers are heated to the desired temperature by contacting them with a fluid heat transfer medium, which is chemically unreactive toward the fibers at the temperature employed, such as saturated steam. Other suitable heat -~L~
~147917 transfer mediums include air, nitrogen, carbon dioxide and the like and mixtures thereof. Steam is the preferred heat transfer medium since it is an efficient conductor of heat.
In certain other instances, (e.g., fiber utility other than carpet yarn) the crimping may be achieved by false twisting which is a technique well known in the art.
The fibers are then removed from the stuffer box and heat set by drying them while in a relaxed condition with a suitable heat transfer medium at temperatures of about 140 to about 200C, preferably from about 150 to about 190C, and most preferably from about 155 to about 165C.
Thus, the heat employed during the heat set procedure is dry heat. Heat setting helps to insure a uniform fiber structure and improves subsequent processing operations.
Suitable heat transfer fluids utilized during heat setting include dry inert gases such as air, carbon dioxide, nitrogen and the like or mixtures thereof.
The annealed fibrous material which is subsequently crimped (i.e., stuffer box) and heat set in the manner described above, although evidencing a slight drop in elastic recovery, will still exhibit an elastic recovery at three minutes recovery time when stretched up to 8~ of its original length, of at least about 70~, typically from about 72~ to about 85~, preferably from about 73 to about 78%, and most preferably from about 75 to about 77~.
The polyethylene terephthalate fibers having improved elastic recovery which are prepared in accordance with the present invention have utility as yarns in carpets, V-belts, sewing thread and textile apparels, e.g., hosiery foundation.
-.. ....
~79~7 The invention is additionally illustrated in connection with the following Examples, which are to considered as illustrative of the present invention. It should be understood, however, that the invention is not limited to the specific details of the Examples.
Unless otherwise indi`cated, all percentages or proportions of materials mentioned in the specification and appended claims are by weight.
,: ~ ~
11479~7 Polyethylene terephthalate having an intrinsic viscosity (I.V.) of 0.67 dl/gm is selected as the starting material. The instrinsic viscosity is determined from a solution of 0.1 gram of the polymer in 100 ml. of ortho-chlorophenol at 25C.
The polyethylene terephthalate is melt extruded through a spinneret having 20 extrusion holes each having a diameter of 20 mils. The molten polyethylene terephthalate is at a temperature of about 300C when extruded through the spinneret. The resulting extruded polyethylene terephthalate is passed directly through a solidification zone having a length of about 6 feet and a vertical disposition for a residence ~ime of about 0.045 seconds. While passing through the solidification zone the extruded polyethylene terephthalate is uniformly quenched with air at room temperature (e.g., about 25) which is continuously introduced and withdrawn from said solidification zone. The polyethylene terephthalate is thereby transformed into a continuous length of as-spun polyethylene terephthalate yarn. The resulting polyethylene terephthalate yarn is under constant tension following extrusion and is withdrawn from the solidification zone at a rate of about 3000 meters per minute (m/m) while under a stress of about 0.2 grams per denier. The extruded filamentary material is drawn down at a ratio of about 100:1. The resulting polyethylene terephthalate yarn exhibits a denier per filament (dpf) of 8 with each filament having a birefrin-gence of about 0.05.
~ ~ ~79~7 ~ ecause the yarn possesses a birefringence below n. lo it must undergo an additional orientation step. Thus, the polyethylene terephthalate yarn is subsequently drawn at a temperature of about 125C at a draw ratio of about 2:1.
The resulting oriented polyethylene terephthalate yarn exhibits a birefringence of about 0.16.
The resulting polyethylene terephthalate yarn is passed at constant length through a steam chamber having an outer jacket or pipe and an inner tube with a plurality of openings along the length of the latter. The fibrous material is maintained at constant length by passing the yarn over and about a first pair of skewed rolls located at the entrance to the steam chamber, through the steam chamber and over and about a second pair of skewed rolls located at the exit of the steam chamber. The speed ratio of the first and second pair of rolls is 1Ø Steam is passed into the space between the outer pipe and the inner tube and through the openings of the inner tube thereby impinging on the yarn which con-tinuously enters and exits the inner tube. The steam in the steam chamber is provided at a pressure sufficient to maintain the temperature of the steam as it impinges on or contacts the yarn at about 200C. The residence time during which the yarn is in contact with the superheated steam is 15 minutes.
The resulting annealed yarn is then tested for elastic recovery in the manner described above and the result is provided at Table I.
~, ~1~7~7 Example 1 is repeated with the exception that the as-spun yarn is withdrawn from the solidification zone at a rate of about 1000 meters per minute while under a low stress of about 0.02 grams per `denier and drawn down at a ratio of about 1.5:1.
Consequently, as a result of the low draw ratio the yarn must undergo an additional orientation step. Thus, the polyethylene terephthalate yarn is subsequently drawn at a temperature of about 90C at a draw ratio of about 4:1.
The resulting oriented polyethylene terephthalate yarn exhibits a denier per filament of about 5 with each filament having a birefringence of about 0.17.
The elastic recovery of the yarn is tested in accordance with the procedure outlined above and the result is provided at Table I.
~1~L79~7 Example 1 is repeated with the exception that upon being withdrawn from the solidification zone the continuous length of polyethylene terephthalate yarn is immediately passed through a vertically disposed conditioning zone having a length of about 12 feet. In accordance with the procedures outlined in U.S. Patent No. 3,946,100 a static air atmosphere is maintained in the conditioning zone at a temperature of about 120C by ~he aid of a band heater which surrounds the walls of the same. The poIyethylene tereph-thalate yarn is present in the conditioning zone for a residence time of about 0.001 second. The polyethylene terephthalate yarn is under constant tension following extrusion and is withdrawn from the conditioning zone at a rate of 30G0 meters per minute while under a stress of about 0.2 gram per denier. Upon withdrawal from the conditioning zone the polyethylene terephthalate yarn is drawn down at a ratio of about 1400:1. The resulting polyethylene tereph-thalate yarn exhibits a denier per filament of 7.5 with each filament having a birefringence of about 0.11.
The elastic recovery of the yarn is tested in accordance with the procedures outlined above and the result is provided at Table I.
~147~17 EXAMPLES 4, 5 AND 6 ExaQples 1,-2 and 3 are repeated and the respective yarn samples resulting therefrom are crimped in a stuffer box in a completely relaxed state (i.e., free to shrink) for a period of about 10 seconds while in contact with steam maintained at a temperature of about 100C. Each yarn sample is then heat set at a temperature between 150 and 170C for a period of about 20 minutes. The resulting crimped and heat set yarn samples originally prepared in accordance with Examples 1, 2 and 3 are designated Examples 4, 5 and 6, respectively, and are tested for elastic recovery at 3 minutes recovery time when stretched to 8% of their original length. The results of the elastic recovery tests are summarized in Table II.
' ' 5`~
~.~47~
COMPARATIVE EXAMPLES 1, 2 AND 3 __ Examples 1, 2 and 3 are repeated and designated Comparative Examples 1, 2 and 3, respectively, with the exception that the yarn is free to shrink as it is passed through the steam chamber. The~respective elastic recovery values o~ the respective yarns are summarized at Table I.
~ ?
~147~17 COMPARATIVE EXAMPLES 4, 5 AND 6 Exa~ples 1, 2 and 3 are repeated and designated Comparative Examples 4, 5 and 6, respectively, with the exception that the respective yarns are not annealed in the steam chamber under controlled length conditions and are tested for elastic recovery as they exist just prior to passing into the steam chamber. The results of elastic recovery are summarized at Table I.
As may be seen from the data provided at Table I, the fibers annealed under controlled length conditions exhibit an elastic recovery which is substantially improved over their counterpart samples used in Comparative Examples 1 to 6.
.
~' ~
~1479~
COMPARATIVE EXAMPLES 7, 8 AND 9 -Examples 4, 5 and 6 are repeated and designated Comparative Examples 7, 8 and 9, respectively, Wit]l the exception that the respective yarns are not annealed under controlled length conditions in~a steam chamber but are immediately crimped and heat set after the orientation and are tested for elastic recovery at 3 minute recovery time when stretched to 8% of the original length. The results of elastic recovery are summarized at Table II.
As may be seen from the data of Table II the elastic recovery of the samples annealed under conditions of controlled length is substantially improved over the counter-part samples which have not been annealed.
1~47917 TABLE I
EFFECT OF CONTROLLED ANNEAL TREATMENT
(200C 15 MINUTES) ON ELASTIC RECOVERY
OF POLYETHYLENE TEREPHTIIALATE YARNS
Examples Elastic Recovery Tension 1 70 CL*
2 81 CL*
3 82 CL*
Comparative Examples Elastic Recovery Tension 1 63 FTS**
2 60 FTS**
3 62 FTS**
Comparative Examples Elastic Recovery Tension 1 63 FTS**
2 60 FTS**
3 62 FTS**
4 46 As-Is***
63 As-Is***
6 70 As-Is***
* = Yarn passed at constant length through steam chamber ** = Yarn free to shrink while passing through steam chamber *** = Yarn is tested just prior to passing through steam chamber ... ........ ...... . . . ...
11~7~17 TABLE II
EFFECT OF CONTROLLED ANNEAL TREATMENT
(200C 15 MINUTES) AND
SUBSEQUENT CRIMPING AND HEAT SETTING (150C 20 MINUTES) ON ELASTIC RECOVERY
ON POLYETHYLENE TEREPHTHALATE YARNS
Examples Elastic Recovery Tension CL*
72 CL*
CL*
Comparative Examples Elastic Recovery Tension 7 64. As-Is**
a 59 As-Is**
9 62 As-Is**
* = Yarn passed at constant length through steam chamber ** = Yarn crimped and heat set just after orientation and before being tension annealed ~4791.7 The principles, preferred embodiment and modes of operation of the present invention have been described in the foregoing specification. The invention which is intended to be protected herein, however, is not to be construed as limited to the particular forms disclosed, since these are to be regarded as illustrative rather than restrictive.
Variations and changes may be made by those skilled in the art without departing from the spirit of the invention.
-
63 As-Is***
6 70 As-Is***
* = Yarn passed at constant length through steam chamber ** = Yarn free to shrink while passing through steam chamber *** = Yarn is tested just prior to passing through steam chamber ... ........ ...... . . . ...
11~7~17 TABLE II
EFFECT OF CONTROLLED ANNEAL TREATMENT
(200C 15 MINUTES) AND
SUBSEQUENT CRIMPING AND HEAT SETTING (150C 20 MINUTES) ON ELASTIC RECOVERY
ON POLYETHYLENE TEREPHTHALATE YARNS
Examples Elastic Recovery Tension CL*
72 CL*
CL*
Comparative Examples Elastic Recovery Tension 7 64. As-Is**
a 59 As-Is**
9 62 As-Is**
* = Yarn passed at constant length through steam chamber ** = Yarn crimped and heat set just after orientation and before being tension annealed ~4791.7 The principles, preferred embodiment and modes of operation of the present invention have been described in the foregoing specification. The invention which is intended to be protected herein, however, is not to be construed as limited to the particular forms disclosed, since these are to be regarded as illustrative rather than restrictive.
Variations and changes may be made by those skilled in the art without departing from the spirit of the invention.
-
Claims (15)
1. A process for improving the elastic recovery of a previously oriented fibrous material having a birefrin-gence of at least 0.10 and comprising at least 85 mole percent polyethylene terephthalate which comprises annealing said fibrous material at a temperature of about 180 to about 210°C for a period of time of about 1 to about 30 minutes while controlling the length thereof in a manner sufficient to prevent a longitudinal shrinkage or extension of said fibrous material greater than about 5%, said annealed fibrous material having an elastic recovery at 3 minute recovery time of at least 70% when stretched to about 8% of its original length.
2. The process of claim 1 wherein the fibrous material has a birefringence of about 0.16 to about 0.20;
the fibrous material is annealed at a temperature of about 190 to about 205°C for a period of about 10 to about 25 minutes; and the elastic recovery of said fibrous material is about 72 to about 80% at 3 minute recovery time when stretched to about 8% of its original length.
the fibrous material is annealed at a temperature of about 190 to about 205°C for a period of about 10 to about 25 minutes; and the elastic recovery of said fibrous material is about 72 to about 80% at 3 minute recovery time when stretched to about 8% of its original length.
3. The process of claim 1 wherein said fibrous material is substantially all polyethylene terephthalate.
4. The process of claim 1 wherein the fibrous material is annealed at a temperature of about 195 to about 202°C for a period of about 18 to about 22 minutes.
5. The process of claim 1 wherein the fibrous material is annealed by contact with steam.
6. The process of claim 1 wherein the annealed fibrous material is provided with a random crimp and heat set at a temperature of about 150 to about 200°C.
7. The process of claim 6 wherein the crimped fibrous material has an elastic recovery of about 72 to about 80% at 3 minute recovery time when stretched to about 8% of its original length.
8. The process of claim 1 wherein the fibrous material is annealed while maintaining the fiber at substan-tially constant length.
9. A process for improving the elastic recovery of a previously oriented fibrous material having a birefrin-gence of about 0.16 to about 0.20 comprising at least 85 mole percent polyethylene terephthalate which comprises:
(a) annealing said previously oriented fibrous material at a temperature of about 180 to about 220°C for a period of time of about 1 to about 30 minutes while con-trolling the length thereof in a manner sufficient to prevent a longitudinal shrinkage or extension of said fibrous material greater than about 5%;
(b) crimping and heat setting the annealed fibrous material, said crimped and heat set fibrous material having an elastic recovery at 3 minute recovery time of at least 70% when stretched to about 8% of its original length.
(a) annealing said previously oriented fibrous material at a temperature of about 180 to about 220°C for a period of time of about 1 to about 30 minutes while con-trolling the length thereof in a manner sufficient to prevent a longitudinal shrinkage or extension of said fibrous material greater than about 5%;
(b) crimping and heat setting the annealed fibrous material, said crimped and heat set fibrous material having an elastic recovery at 3 minute recovery time of at least 70% when stretched to about 8% of its original length.
10. The process of claim 9 wherein the fibrous material is substantially all polyethylene terephthalate.
11. The process of claim 9 wherein the fibrous material is annealed at a temperature of about 190 to about 205°C for a period of about 10 to about 25 minutes.
12. The process of claim 9 wherein the oriented fibrous material is annealed at a temperature of about 195 to about 202°C for a period of about 18 to about 22 minutes.
13. The process of claim 9 wherein the fibrous material is annealed by contact with steam while maintained at substantially constant length.
14. The process of claim 9 wherein the fibrous material is crimped in a manner sufficient to impart a random crimp thereto and is heat set at a temperature of about 140 to about 200°C.
15. The process of claim 9 wherein the crimped fibrous material has an elastic recovery of about 72 to about 80% at 3 minutes recovery time when stretched to about 8% of its original length.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US7164779A | 1979-09-04 | 1979-09-04 | |
| US071,647 | 1979-09-04 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1147917A true CA1147917A (en) | 1983-06-14 |
Family
ID=22102676
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000359499A Expired CA1147917A (en) | 1979-09-04 | 1980-09-03 | Process for improving the elastic recovery of a polyethylene terephthalate fibrous material |
Country Status (2)
| Country | Link |
|---|---|
| BR (1) | BR8005583A (en) |
| CA (1) | CA1147917A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4639347A (en) * | 1983-05-04 | 1987-01-27 | E. I. Du Pont De Nemours And Company | Process of making crimped, annealed polyester filaments |
-
1980
- 1980-09-02 BR BR8005583A patent/BR8005583A/en unknown
- 1980-09-03 CA CA000359499A patent/CA1147917A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4639347A (en) * | 1983-05-04 | 1987-01-27 | E. I. Du Pont De Nemours And Company | Process of making crimped, annealed polyester filaments |
Also Published As
| Publication number | Publication date |
|---|---|
| BR8005583A (en) | 1981-03-17 |
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