US3488251A

US3488251A - Side-by-side self-crimping conjugate filaments

Info

Publication number: US3488251A
Application number: US615325A
Authority: US
Inventors: Sylvia Etchells; Antoni Harcolinski; Clifton Douglas Cowell
Original assignee: Imperial Chemical Industries Ltd
Current assignee: Imperial Chemical Industries Ltd
Priority date: 1966-02-24
Filing date: 1967-02-13
Publication date: 1970-01-06
Anticipated expiration: 1987-01-06
Also published as: GB1169782A; BE694635A; FR1512294A; NL6702479A; CH487271A; LU53058A1; DE1669461A1

Description

United States Patent ABSTRACT OF THE DISCLOSURE A side-by-side conjugate filament is disclosed in which one of the components is a fibre-forming polyamide or polyester and the other component is a fibre-forming polyamide/polyester mixture. The mixture is such that one polymer forms a continuous phase with the other polymer dispersed therein in the form of fine fibrils.

13 Claims The present invention is concerned with improvements in or relating to conjugate filaments and is especially concerned with conjugate filaments in which one component is a polyester of a polyamide and the other component is a polyamide/polyester mixture.

By the term conjugate filament is meant a unitary filament consisting of at least two polymeric fibre-forming components extending continuously along the length thereof in an adhering sheath/ core or side-by-side relationship.

It has been proposed in British patent specification No. 805,033 to produce conjugate filaments in which one component is a polyamide and the other component a polyester, such filaments having a high potential crimp and good crimp retention. However such filaments formed from these components in a side-by-side arrangement tend to fibrillate, that is separate into two unitary filaments, during drawing and hence they have only limited commercial application. This problem can be alleviated by forming the conjugate filament with the components in a sheath and core arrangement thus effectively preventing fibrillation, however, the production of this type of conjugate filament is technically less attractive than the side-by-side type.

We have now found that a conjugate filament, in which the components exist in a side-by-side relationship, having high crimp and good crimp permanence and substantially free from fibrillation can be obtained using a polyamide and a polyamide/ polyester mixture as the two components. To obtain maximum adhesion it is preferable the polyamide/polyester mixture should consist of a matrix of the polyamide having the polyester dispersed therein in the form of long fine fibrils to obtain maximum adhesion between the two components. It has been found that the polyester fibrils exert a disproportionately large effect on the physical characteristics of the mixture in filament form, thus the initial modulus is increased by an amount which is greater than would be expected from the percentage of polyester present and the filaments exhibit a spontaneous crimp when the two polyamide components are the same. Surprisingly good adhesion between the components is obtained when the polyamide is the dispersed phase, it being thought that this may be the result of the polyamide fibrils diffusing into the wholly polyamide component and thereby forming anchor points which prevent fibrillation. Conjugate filaments of this type normally have a higher crimp than those in which the polyamide is the continuous phase.

We have also found non-fibrillated conjugate filaments 3,488,251 Patented Jan. 6, 1970 are obtained when one component is a polyester and the other component is a poly/polyamide mixture in which the polyester is the disperse phase.

The present invention does not include those conjugate filaments in which a polyester forms one component and a polyester forms the continuous phase of the other component, since the dispersed polyamide fibrils add nothing the ability of the filament to crimp or to the adhesion between the components.

The conjugate filaments of this invention crimp spontaneously when held in a relaxed condition after drawing. Subsequent heat relaxation treatments further increase the crimp and, surprisingly, it has been found that improved crimp is obtained when the filaments are fatigued, that is repeatedly stretched and relaxed under ambient conditions.

Accordingly therefore from one aspect the present invention provides a drawn molecularly oriented spontaneously conjugate filament containing two components one of which components is a fibre-forming polyamide or polyester and the other of which componets is a fibreforming polyamide/polyester mixture. Preferably the components exist in a side-by-side relationship.

It is preferred that the percentage of polymer constituting the disperse phase in the mixture be not less than 20% and more preferably not less than 25% of the combined weight of the polymers in the mixture.

It is also preferred that in the polyamide/polyester mixture the polyamide is the continuous phase and the polyester is dispersed therein in the form of fibrils having a length of not less than microns.

The polyamide/polyester component should preferably have an initial modulus of at least 50 gm. per denier per of extension, measured at 2% extension when in the form of a unitary filament, and a glass/rubber transition temperature measured in the dry state of not less than 100 C.

In order to avoid fibrillation it is preferred that the heterofilaments are drawn immediately after spinning, or are stored at a relative humidity of at least 65% and a temperature of 7173 F. before drawing if there is a time lag between spinning and drawing.

From another aspect therefore the present invention provides a process for the manufacture of a heterofilament as hereinbefore defined comprising simultaneously extruding the components through the same extrusion orifices in a side-by-side relationship, solidifying and winding up the filament onto a package and storing the package at a relative humidity of at least 65% and a temperature of 71-73 F. before drawing or drawing immediately after completion of winding the filament onto the package, drawing the filament by at least three times its original length and relaxing to allow the crimp to develop.

Drawing may be carried out by passing the filament between a first and second set of rotating rolls, the second set rotating at a greater peripheral speed than the first, there being, preferably, a snubbing pin positioned between the sets of rolls to locate the point of draw of the filament. For best results the filaments should be heated during drawing by passage over a heated plate or by use of a heated snubbing pin, the temperature of the plate or pin preferably being above 100 C.

Care must be taken in the preparation and spinning of polyamide/polyesters polymers to avoid hydrolytic degradation of the polyester by the action of water on the polyester linkages and to avoid interaction between the polyamide and polyester components. Suitable polyester/ polyamide mixture may be prepared and spun as one component of the heterofilament by the process described in our copending patent application No. 46,796/ 65.

The polyamides, when used as one component, may be homopolymers or copolymers. Suitable polyamides are polyhexamethylene adipamide and polyepsilon captolactam and copolymers thereof, especially the 80/20 polyhexamethylene adipamide/polyepsilon caprolactam copolymer.

tensile tester, extended at a rate of 100 cm./min. to a draw ratio of 4.1 and the load released at the same speed: the distance apart of the jaws when the load became zero was used as a means of filament length with the crimp removed (L The test was carried out at normal tem- Polyethylene terephthalate is a suitable polyester to use 5 P atl a t. a t v h mid y 0f Th6 c i p as one component. characteristics were as shown in Table 1.

The polyamide/polyester mixture may consist of poly- TABLE 1 hexameth'ylene adipamide or polyepsilon caprolactam admixed with polyethylene terephthalate or the polyester Mlmmum Maxlmum Mean formed from ethylene glycol and 4/4' dicarboxy ph n Xy gg g gg'g ethane. Either the polyamide or the polyester may con CF (per stitute the continuous phase, the disperse phase being dis- 5 8' 8 2 8%; tributed therethrough in the form of fine fibrils. For the 6 1111111511: is 1 .9 2.8 purposes of the present invention polyesters include co- ,Meanono tesw polyesters. +Mean of 6 tests.

The following examples illustrate but do not limit the Reversal Frequency (RF) the number of crimp mvenuonreversals per cm. is calculated from the expression:

Example 1 i RF :r/ a A conjugate filament was obtamed by the extruslon of where r-number of crimp reversals per crimped length a polyhexamethylene adipamide (PHA) and a mlxture of Grim; Permanence (CP) is calculated from the polyhexamethylene adipamide and polyethylene terephs thalate (PET) (75:25 parts by weight) in a side-by-side pm S1 arrangement at a temperature of 285 C. The solidified filament was wound up and stored at a temperature of L a about 72 and a relatlve immidlty of about and where L and a have the same significance as above, and subsequently drawn at a feedlng speed of 50 ft./m1n. and of crimped filament after placing the crimped g ffi f e g g hot g at 2 Wlthout filament under a load of 0.3 g./d. for one minute and r1 ation. e ament ad a enier o .1 a tenacity then relaxin in th tns-on d stat f0 on t of 7.2 g./d. and an extension to break of 18.5%. A fine g 6 un e 1 e e r e mmu e. helical crimp having good crimp permanence was ob- Examp tamed f the j j filament was relaxed at amblent A series of drawn unfibrillated conjugate filament yarns atmOSPheI'lC Conditions and there was Complete absence containing ix filaments were prepared in the manner deof fib1'111at10ndescribed in Example 1. Details of the polymer com- After relaxing in water at near boiling point for one ponents, spinning and drawing temperatures and yarn mlnute and then further relaxing for one minute out properties are given in Table 2 below.

TABLE 2 Drawing Yam physical properties Conditions Polymer Components Spinning Hotplate Ext. to Example Homotemp., temp., Draw Tenacity break, No. Mixture polymer 0. 0. ratio Denier g./d. percent 2 PET/FHA (75/25)-.- PHA 292 140 5.0 13.7 5.8 14.5 3 PET/FHA (75 25) FHA- 292 20 4.5 9.8 4.5 36.9 4 PET/PHA (25/75) PET 290 140 5.0 13.3 5.1 16.7

of water the conjugate filament had the following crimp The spun filaments in the above examples were cooled characteristics: and wound up and drawn immediately or held at a temture of about 72 F. and a relatively humidity of Crlmp ratio (CR): 33% Pm Crimp frequency (CF): 3 m about 67% for several hours before drawlng. Under these conditions separation of the components was not en- Hellx diameter (d). 2.0 mm. t d d d A fi h 1 h Crimp ratio was calculated from the expression: coun urmg rawmg e lea cnmp avmg good crimp permanence was obtained when the drawn yarn was relaxed at ambient atmospheric conditions. C'.R.= L0 X100 After relaxing in water at near boiling point for one minute and then further relaxing for one minute out of Crimp frequency f the expression water, the filaments had the following characteristics:

CF=n/a (crimps/cm.)

Where CR, percent CF/cm. dmrn. L0=length of uncrimped filament Example No; a=1ength of crimped filament under zero tension 2 28 2 H n=number of loops in crimped length a of the filament. 58

The spontaneous crimp developed by the filaments obtained in this example were characterised in the following experiment. A 10 cm. length of undrawn filaments ob- The spontaneous crimp developed by the filaments of tained above was inserted between the jaws of an instron Examples 2 and 4 was characterised in the manner used in Example 1 at a draw ratio of 4.5, the crimp characteristics are shown in Table 3.

amide/polyester mixture in which the polyester is the continuous phase and the polyamide is dispersed therein TABLE 3 03*, Denier* percent CF" .per cm RF*. per cm. OP+ d. mm.

Ex. N:

{ll/linimum... 10.2 27 2 0.25 0. 33 1.1 2 Maximum 18.0 34 4 0.40 0. 52 2.3 Mean 15.1 31 a 0. 33 0. 41 1.0 {MinimunLu 9.2 27 4 0. 20 0. 44 0.0 4 Maximum. 13.7 30 5 0. 45 0. 80 1.4 Mean 11.4 32 4 0. 31 0. 02 1.2

*Mean of ten tests. +Mean of six tests.

A series of other combinations of polymers was rod in the form of fine fibrils. spun as monofilaments at a rate of extrusion of 1.3 g./ min. 9. A filament according to claim 8 wherein the polyand a wind up speed of 600 ft./min. The undrawn filaments amide is polyhexamethylene adipamide and the polywere drawn over a heated plate immediately after extruamide/ polyester component is polyepsilon caprolactam/ sion and subsequently relaxed in water at near boiling polyethylene terephthalate in which the polyepsilon capropoint for one minute and then further relaxed for one lactam is the disperse phase and constitutes 25% by weight minute out of the water and the crimp characteristics of the mixture.

determined. Details of spinning and drawing and crimp characteristics are given in Table 4.

10. A filament according to claim 8 wherein the polyamide is polyepsilon caprolactam and the polyamide/ TABLE 4 Components Spinning Draw Plate 0 R C F, Polyarnide Mixture temp. 0. ratio temp, 0. percent per cm. d. mm

6 FHA/PEG (80/20) FHA/PET (20, 80) 288 5 140 74 22 0.8 7 PHA PET/PHA (40/60). 275 4. 5 135 61 3. 5 1. 6 270 4. 5 135 37 2.0 1. 8 275 4. 0 135 61 4. 7 1. 6 296 4. 0 150 03 7. l l. 0

*PEC polyepsilon caprolactam. +CPE.2G=polyester prepared from ethylene glycol and 4,4 dicarboxyplienoxycthane.

There was no evidence of fibrillation during drawing in any of the above experiments.

What we claim is:

1. A drawn molecularly oriented spontaneously crimping conjugate filament containing at least two components existing in a side-by-side relationship, one of which components is a fibre-forming polyamide or polyester and the other of which components is a fibre-forming polyamide/ polyester mixture.

2. A filament according to claim 1 wherein the poly amide/polyester mixture contains not less than 20% by weight of the disperse phase.

3. A filament according to claim 2 wherein the polyamide/polyester mixture contains not less than by weight of the disperse phase.

4. A filament according to claim 2 wherein one component is a polyamide and the other component is a polyamide/ polyester mixture in which the polyamide is the continuous phase and the polyester is dispersed therein in the form of fibrils having a length of not less than 80 microns.

5. A filament according to claim 4 wherein the polyamide/polyester component has an initial modulus of at least 50 g. per denier per 100% extension, measured at 2% extension, and a glass-rubber transition temperature of not less than 100 C. when measured in the dry state.

6. A filament according to claim 5 wherein the polyamide is polyhexamethylene adipamide and the polyamide/ polyester mixture is polyhexamethylene adipamide/ polyethylene terephthalate.

7. A filament according to claim 2 wherein the polyamide is polyhexamethylene adipamide and the polyamide/polyester component is a mixture of polyhexamethylene adipamide/ and a polyester formed from ethylene glycol and 4,4 carboxy phenoxy ethane in equal proportions by weight.

8. A filament according to claim 2 wherein one component is a polyamide and the other component is a polypolyester component is polyepsilon caprolactam/polyethylene terephthalate in which the polyepsilon caprolactam is the disperse phase and constitutes 25 by weight of the mixture.

11. A filament according to claim 8 wherein the polyamide is polyhex'amethylene adipamide and the polyamide/ polyester mixture is polyhexamethylene adipamide/ polyethylene terephthalate in which the polyhexamethylene adipamide is the disperse phase and constitutes 25% by weight of the mixture.

12. A filament according to claim 2 wherein one component is a copolymer polyhexamethylene adipamide and polyepsilon caprolactam containing 20% by weight of the polyepsilon caprolactam and the other component is polyhexamethylene adipamide/ polyethylene terephthalate containing 20% by weight of polyhexamethylene adipamide.

13. A filament according to claim 2 wherein one component is a polyester namely polyethylene terephthalate and the polyamide/ polyester component is polyhexamethylene adipamide/ polyethylene terephthalate containing by weight of the polyamide as the continuous phase and the polyester dispersed therein in the form of fibrils having a length of not less than microns.

References Cited UNITED STATES PATENTS 3,118,011 1/1964 Breen 264--l68 3,382,305 5/1968 Breen 26417l 3,402,752 9/1968 Beringer.

ROBERT F. BURNETT, Primary Examiner LINDA M. CARLIN, Assistant Examiner US. Cl. X.R. 161173; 264-l7l