US3724038A

US3724038A - Continuous process for relaxing heat treatment and apparatus therefor

Info

Publication number: US3724038A
Application number: US00155722A
Authority: US
Inventors: R Nakazono; T Mukai; K Chimura; T Kaneko; A Nakazima; K Sakunaga
Original assignee: Mitsubishi Rayon Co Ltd
Current assignee: Mitsubishi Rayon Co Ltd
Priority date: 1970-07-04
Filing date: 1971-06-23
Publication date: 1973-04-03
Anticipated expiration: 1990-04-03
Also published as: DE2132826A1; NL7109278A; NL146549B; FR2100179A5; GB1365732A

Abstract

An improvement in a continuous process for the relaxing heat treatment of crimpable filaments, particularly potentially crimpable filaments which comprises passing the filaments overfed from a filament charging apparatus through an ejecter, wherein a heated fluid is ejected, to subject the filaments to pre-heating and fiber separation, spraying a heated fluid onto the filaments at right angles from their circumference in a low tension zone under a tension as low as 1 mg/denier or less to subject the filaments to relaxing heat treatment, and then passing the treated filaments through a heat treatment chamber to subject the filaments to thermal setting, and an apparatus therefor.

Description

United States Patent [191 Chimura et al.

[111 3,724,038 1 Apr. 3, 1973 [54] CONTINUOUS PROCESS FOR RELAXING HEAT TREATMENT AND APPARATUS THEREFOR [73] Assignee: Mitsubishi Rayon Co., Ltd., Tokyo,

Japan 22 Filed: June23, 1971 21 Appl.No.:155,72 2

[30] Foreign Application Priority Data [58] Field of Search ..28/l.2, 1.4, 72 HR, 72.1, 72.12

[56] References Cited UNITED STATES PATENTS 3,425,107 2/1969 Matsui et al 3,558,760 l/l97l Olson 3,644,968 2/1972 Elliott et a]. ..28/l.4 X

Primary ExaminerLouis K. Rimrodt Attorney-James E. Armstrong et al.

[57] ABSTRACT An improvement in a continuous process for the relaxing heat treatment of crimpable filaments, particularly potentially crimpable filaments which comprises passing the filaments overfed from a filament charging apparatus through an ejecter, wherein a heated fluid is ejected, to subject the filaments to pre-heating and fiber separation, spraying a heated fluid onto the filaments at right angles from their circumference in a low tension zone under a tension as low as l mg/denier or less to subject the filaments to relaxing heat treatment, and then passing the treated filaments through a heat treatment chamber to subject the filaments to thermal setting, and an apparatus therefor.

5 Claims, 4 Drawing Figures CONTINUOUS PROCESS FOR RELAXING HEAT TREATMENT AND APPARATUS THEREFOR The present invention relates to an improvement in a continuous process for the relaxing heat treatment of crimpable filaments, particularly filaments having potential crimpability, and an apparatus therefor.

In general, so-called potentially crimpable filaments produced by subjecting two or more polymer components to composite spinning or by carrying out partial heating or cooling during the spinning of one polymer are very weak in crimp developing power. Therefore, it is necessary for obtaining uniform crimped yarn having a high bulkiness to subject filaments to heat treatment under a tension as small as possible. If the heat treatment is carried out at a high speed to increase productivity, the constraining force exerted on the filaments is increased by frictional resistance to air with increasing speed and thereby the development of crimps is remarkably obstructed. Therefore, the resulting crimped filaments have poor bulkiness. As a means for solving such a problem, there is proposed in Japanese Pat. publication No. 15,582/ 1968 an apparatus for subjecting filaments to heat treatment in a tensionless state in a heating cylinder wherein ejectors are provided oppositely at its inlet and outlet.

However, in such an apparatus, when the filaments running at a high speed pass through the outlet side ejector, the filaments are again subjected to high tension in a heated state. Therefore, the developed crimps are straightened and the level of crimp developing of the filaments in a heated state is subject to wide fluctuations according to a slight disturbance of the heated fluid circulating through the outlet side ejector. It causes uneveness of crimp and streakiness of dyed fabric. Further, it is very difficult to pass filaments through the opposite ejectors before the start of the operation. Thus, such an apparatus presents various problems in commercial operation.

It is therefore the principal object of the present invention to avoid the difficulties heretofore encountered in the high speed relaxing heat treatment of filaments and to remove defects of prior art processes.

It is a further object to provide crimped filaments having a high bulkiness, crimp uniformity and excellent dye-eveness.

Another object of the present invention is to provide an improved process for the continuous relaxing heat treatment of filaments and an improved apparatus for practising the process.

These and other objects and advantages of the invention will appear from the following description of the invention.

More particularly, the present invention is directed to a process for the continuous relaxing heat treatment of filaments characterized in that the filaments overfed from a filament charging apparatus are passed through an ejector to subject the filaments to preheating and fiber separation, and a heated fluid isthen sprayed onto the filaments at right angles from their circumference in a low tension zone under a tension as low as l mg/denier or less to subject the filaments to relaxing heat treatment, and the treated filaments are then passed through a heat treatment chamber to subject the filaments to thermal setting.

Further, the present invention provides an apparatus for the continuous relaxing heat treatment of filaments characterized in that an ejector is provided on the inlet side of a heat treatment chamber and a spray means is provided between said ejector and said heat treatment chamber for spraying heated fluid onto the filaments at right angles from their circumference.

The present invention will be explained in detail referring to the accompanying drawings in which:

FIG. 1 is an axial cross sectional view of an embodiment of the apparatus of the present invention;

FIG. 2 is a sectional plan view of a spray means (ring) used in the apparatus of FIG. 1;

FIG. 3 is a graph showing the tension distribution in the running filaments in the apparatus of FIG. 1; and

FIG. 4 is a graph showing the temperature distribution in the apparatus of FIG. 1 and (1) shows the temperature distribution in the direction of the central axis while (2) the temperature distribution in the radial direction.

In FIG. 1, a heat treatment apparatus 1 consists of an ejector 3, a heat treatment chamber 5 having a heater (not shown) at its circumference and a hot gas spray ring 4 as coaxially provided between the ejector and the heat treatment chamber. Above said heat treatment apparatus 1, there are provided a pair of supply rollers 2 and 2', while a pair of take-up rollers 7 and 7 are provided below the heat treatment apparatus.

Further, a cover plate 6 having a guide opening 17 at its center is provided between the heat treatment apparatus 1 and the take-up rollers 7 and 7 The cover plate 6 serves for preventing the take-up rollers 7 and 7' from being heated by the hot fluid flowing out from the heat treatment chamber 5. Said

supply rollers

2 and 2 are rotated at higher speed than the take-up rollers 7 and 7 to overfeed the filament 9 in the heat treatment apparatus 1.

As is shown in FIG. 2, said spray ring 4 is made up of an outer ring 11 and a porous metal inner ring 14, with these two rings being coaxially provided. Two separators 12 and 12' serve for coupling these rings 11 and 14 and for separating an annular space between the rings into two pressure chambers 13 and 13'. In the outer ring 11, there are provided ducts l0 and 10' for introducing a heated fluid, which lead to the pressure chambers 13 and 13', respectively. The heated fluid blown into the pressure chambers 13 and 13' through said ducts l0 and 10' is pressurized in these chambers and is then uniformly sprayed toward the central axis through the inner ring 14 as is shown by arrows in FIG. 2. The inner ring 14 may be of any type so long as the heated fluid can be uniformly sprayed through it. However, a 150 mesh porous metal ring is the most preferable.

In the apparatus of FIG. 1, stretched filament 9 having potential crimpability is overfed in an appointed amount and runs between the supply rollers 2 and 2' and the take-up rollers 7 and 7'. The filament leaving the

supply rollers

2 and 2 is first swallowed up into an ejector 3. The filament 9 is subjected to thorough fiber separation and preheating by a hot jet stream flowing through the ejector 3. The temperature of this jet stream is preferably about C for polyamide, about C for polyester and about C for polyacrylonitrile fiber. If the temperature is too low,

preheating can not be sufficient and subsequent development of crimps and thermal fixing will not become satisfactory. Also, if the temperature is too high, the filament 9 is subjected to heat relaxing at the throat 15 of the ejector under a high tension and crimp developing ability is undesirably reduced.

The filament 9, which has been subjected to separating and preheating, then enters a low tension zone C formed on the boundary between a zone A wherein the speed of the ject stream is higher than that of the filament 9 and a zone B wherein the speed of the jet stream is lower than that of the filament, as shown in FIG. 3. This low tension zone C has now been found by the present inventors as a result of their diverse study.

The tension in the zone A is due to the speed difference between the running filament 9 and the jet stream in the ejector 3. The tension distribution in the zone A was obtained by blowing a jet stream into the zone from the ejector 3 and measuring the frictional force exerted on the filament 9 while the filament is at a stand-still. The tension distribution in the zone B was obtained based on the analysis by a wind tunnel test of the phenomenon that a frictional force generated by the relative velocity between the filament 9 and the atmosphere exerts on the filament 9 as a tension. FIG. 3 has been obtained by linking these two tension distributions to each other and shows the tension distribution of the filament 9 between the supply rollers 2 and 2' the heat treatment apparatus 1 the take-up rollers 7 and 7'.

The term, low tension zone C, used herein means a zone wherein the potentially crimpable filament is under a critical tension required for the filament to develop crimps, that is, a tension of l mg/denier or less.

If the filament 9 enters said low tension zone C, the cold air layer which lies between or around the constituent single fibers is destroyed by the heated fluid sprayed from the spray ring 4 as provided in said zone C and is replaced by the heated fluid. Thus, the temperature of the atmosphere is kept high to effect heat exchange with the filament 9. Heat is rapidly transferred to the filament 9 and the temperature of the filament 9 is readily increased because the heated fluid flows at right angles to the filament 9. Therefore, the

filament 9 may develop crimps sufficiently and uniformly.

The filament 9 then develops further crimp uniformly and is subjected to thermal setting in the heat treatment chamber 5. The temperature in the heat treatment chamber 5 is made almost uniform both in the direction of the central axis 1 and in the radial direction 2 by the action of the heated fluid from said spray ring 4, as is shown in FIG. 4. Therefore, even if the filament 9 swings in the heat treatment chamber, dyeing streakiness is not generated by a variation in heat history. Also, FIG. 4 shows the temperature distribution at the jet stream in the ejector 150C, a temperature of the heated fluid in the spray ring 300C and a temperature of the wall of the heat treatment chamber 300C.

The filament 9 leaving the heat treatment chamber is then taken up by a bobbin 16 through the guide opening 17 of a cover plate 6, take-up rollers 7 and 7' and a guide 8.

As described above, according to the present invention, filaments having self-crimpable potential are first passed through an ejector to effect preheating and fiber separation and are then subjected to relaxing heat treatment in a specific low tension zone by spraying a heated fluid onto the filaments at right angles from the circumference under a tension of l mg/denier or less. Therefore, even if the running speed of the filaments is remarkably high, the filaments can develop crimps uniformly and sufficiently. Also, the temperature distribution in the heat treatment apparatus is made quite uniform by the action of said heated fluid. Therefore, the streakiness caused by a variation in heat history can be prevented and thorough thermal fixing can be effected.

Further, the apparatus of the present invention has many commercial advantages, for example, in that it is simple in structure and is very easy to operate.

It will be clear that the present invention can be applied to not only the crimp development of potentially crimpable fibers but also the thermal fixing of the other crimped yarns.

The following examples will serve to illustrate the practice of the present invention in more detail. The terms, relaxation percantage, thermal shrinkage percentage, number of crimps and crimp percentage used in these examples have the following definitions, respectively:

Relaxation percentage: A numerical value calculated according to the formula,

wherein V The circumferential speed of the supply rollers 2 and 2' V The circumferential speed of the take-up rollers 7 and 7' Thermal shrinkage percentage:

A numerical value calculated according to the formula,

(l -1 H X wherein l,,: The length of the crimp developed yarn under a load of 0.2 g/denier I The length of the said yarn under said load after the yarn was subjected to dry heat treatment at C for 20 minutes Number of crimps: Number of crimps/25 mm of the single fiber under a load of 2 mg/denier Crimp percentage: A numerical value calculated according to the formula,

wherein a: The length of the single fiber under a load of 2 mg/denier b: The length of said single fiber which has been further subjected to a load of 0.2 g/denier EXAMPLE 1 Two hundred seventy Denier/36 filament unstretched yarn obtained by composite spinning at 290C of two polyethylene terephthalate polymers having intrinsic viscosity [1;] of 0.53 and 0.75, respectively, as measured in a 50 2 50 mixture of dichloroethane and phenol at 35C was stretched to 3.85 times the original length and was then subjected to continuous relaxing heat treatment using the apparatus of FIG. 1 at a supply speed of 600 m/min, a relaxation percentage of 20 a temperature of the air jet stream in the ejector of 150C and the temperature'of the heated fluid in the spray ring of 250C and the wall of the heat treatment chamber of 250C. The obtained crimped yarn was 75 denier/36 filaments and had very high bulkiness and excellent thermal stability and a number of crimps of 31.8 per 25 mm and a thermal shrinkage percentage of 1.8

Said crimped yarn was then knitted into a 18 gauge plain knitted fabric. The obtained fabric was dyed with a disperse dye, Duranol Red GN (C.I. No. 60505). Thus, a dyed fabric having high bulkiness and a uniform surface of knitted fabric was obtained and no streakiness was observed therein.

EXAMPLE 2 Stretched 75 denier/34 filaments yarn obtained by subjecting two polycapramides having relative viscosity of 2.2 and 3.9, respectively, in sulfuric acid to composite spinning and then cold stretching to 3.2 times the original length was subjected to continuous relaxing heat treatment using the apparatus of FIG. 1 at a speed of the supply rollers of 600 m/min, a relaxation percentage of 32 percent, a temperature of air jet stream in the ejector of 100C, a temperature of heated fluid (superheated stream) in the spray ring of 112C and a temperature of the wall of the heat treatment chamber of 100C. Thus, crimped yarn having a number of crimps of 52 per.25 mm, a crimp percentage of 50 percent and a shrinkage percentage after treatment in boiling water of 2.6 percent was obtained.

The crimped yarn was then knitted into a 18 gauge plain knitted fabric. The obtained fabric was dyed with Cibacet Blue F3R (C.I. No. 61505). Thus, a dyed fabric having high bulkiness and a uniform surface of knitted fabric was obtained and no streakiness was observed therein.

COMPARATIVE EXAMPLE The same unstretched yarn as in Example 1 was stretched 3.85 times theoriginal length and was then subjected to relaxing heat treatment using a known heat treatment apparatus, wherein two ejectors are provided against the inlet and outlet for the filament running through the heat treatment chamber and an outlet for exhausting the heated fluid is provided at the side wall of said heat treatment chamber, at a speed of the supply rollers of 600 m/min, a relaxation percentage of 20 percent, a temperature of air jet stream in the upper and lower ejectors of C and a temperature of the wall of the heat treatment chamber of 250C. The resulting crimped yarn showed a number of crimps of 20.2 per 25 mm and a thermal shrinkage percentage of 2.2 percent. Said crimped yarn was then knitted and dyed in the same manner as in Example 1. The obtained dyed fabric was remarkably inferior to that obtained according to the present invention in bulkiness and uniformity of knitted fabric and slightly inferior in dye-eveness. Further, the above-mentioned conditions may be changed, but such good crimped yarn as that of the present invention could not be obtained.

What is claimed is:

l. A process for the continuous relaxing heat treatment of filaments which comprises passing the filaments overfed from a filament charging apparatus through an ejector, wherein a heated fluid is ejected, to subject the filaments to preheating and fiber separation, spraying a heated fluid onto the filaments at right angles from their circumference in a low tension zone under a tension as low as 1 mg/denier or less to subject the filaments to relaxing heat treatment, and then passing the treated filaments through a heat treatment chamber to subject the filaments to thermal fixing of the fiber structure.

2. A process according to claim 1 wherein polyester filaments having self-crimpable potential are subjected to heat treatment.

3. A process according to claim 1 wherein polyamide filaments having self-crimpable potential are subjected to heat treatment.

4. An apparatus for the continuous relaxing heat treatment of filaments characterized in that an ejector is provided on the inlet side of a heat treatment chamber and a spray means is provided between said ejector and said heat treatment chamber for spraying a heated fluid onto the filaments at right angles from their circumference, supply rollers located sequentially prior to the ejector, take-up rollers located sequentially after the heat treating chamber and at least one cover plate located between the chamber and take-up rollers.

5. An apparatus according to claim 4 wherein said spray means consists of an outer ring and a porous metal inner ring, as arranged so that an annular space may be formed been the two rings, as well as a heated fluid spray duct provided at the side wall of said outer ring, and separators coupling the said inner and outer rings.

Claims

2. A process according to claim 1 wherein polyester filaments having self-crimpable potential are subjected to heat treatment.
3. A process according to claim 1 wherein polyamide filaments having self-crimpable potential are subjected to heat treatment.
4. An apparatus for the continuous relaxing heat treatment of filaments characterized in that an ejector is provided on the inlet side of a heat treatment chamber and a spray means is provided between said ejector and said heat treatment chamber for spraying a heated fluid onto the filaments at right angles from their circumference, supply rollers located sequentially prior to the ejector, take-up rollers located sequentially after the heat treating chamber and at least one cover plate located between the chamber and take-up rollers.
5. An apparatus according to claim 4 wherein said spray means consists of an outer ring and a porous metal inner ring, as arranged so that an annular space may be formed been the two rings, as well as a heated fluid spray duct provided at the side wall of said outer ring, and separators coupling the said inner and outer rings.