US3651195A

US3651195A - Process for producing composite filaments

Info

Publication number: US3651195A
Application number: US733090A
Authority: US
Inventors: Ole-Bendt Rasmussen
Original assignee: Individual
Current assignee: Individual
Priority date: 1967-05-30
Filing date: 1968-05-29
Publication date: 1972-03-21
Anticipated expiration: 1989-03-21
Also published as: GB1230991A; DK117312B; FR1568499A; DE1760518A1

Abstract

A FILAMENT MATERIAL COMPRISES A CORE CONSISTING OF A SUBSTANTIALLY HOMOGENEOUS POLYMER MATERIAL (A) AND A COAT CONSISTING OF TWO MUTUALLY INCOMPATIBLE POLYMER MATERIALS (B) AND (C) WHERE (B) IS COMPATIBLE WITH (A) AND FORM A SUBSTANTIALLY HELICAL FIBROUS STRUCTURE ON THE SURFACE OF (A) AND (C) IS EASILY REMOVABLE. TO MAKE THE FILAMENT MATERIAL, A DISPERSION OF (B) AND (C) IS

APPLIED TO THE SURFACE OF (A) WHILE THIS IS BEING EXTRUDED WHEREAFTER THE EXTRUDED STRAND IS SUBJECTED TO STRETCHING AND TWISTING.

Description

March 21, 1972 oLE-BENDT RAsMussEN 3,651,195

PROCESS FOR PRODUCING COMPOSITE FILAMENT Filed May 29, 1968 ;U.s.,cl. A2154-171 .K

United States Patent O Y Y 3,651,195 lPROCESS FOR PRODUCING COMPOSITE FILAMENTS Ole-Bendt Rasmussen, 7 Topstykket, 3460'Birkerod, Denmark Filed May 29, 1968, Ser. No. 733,990 Claims priority, application Great Britain, May 30, 1967, 24,836/ 67 Int. Cl. B29f 3/10 9 Claims ABSTRACT OF THE DISCLOSURE A filament material comprises a core consisting of a substantially homogeneous polymer material (A) and a coat consisting of two mutually incompatible polymer materials (B) and (C) where (B) is compatible with (A) and form a substantially helical fibrous structure on the surface of (A) and (C) is easily removable. To make the filament material, a dispersion of (B) and (C) is applied to the surface of (A) while this is being extruded whereafter the extruded strand is subjected to stretching and twisting.

BACKGROUND OF THE INVENTION The present invention relates to a composite filament material capable of forming a textile yarn by removal of a protective polymer contained therein.

It is known that polymer/polymer dispersions which have been effectively -stretched before solidification form a yarn-like structure when one of the polymers is removed by dissolving. The said known yarn-like structure generally has the character of being a stretched sponge or network.

In experiments preceding the present invention it was found that the individual fibres of such yarn could be produced in a surprising fnene-ss hereby yielding an extremely soft and fluffy yarn having a higher total surface area, improved dyeability and improved ability for transport of moisture. These improvements were in particular found when a relatively high amount of protective polymer was admixed and again removed. However, the above advantages Were obtained at the expense of tensile strength.

SUMMARY OF THE INVENTION The filament according to the present invention comprises, as core material, a substantially homogeneous polymer material (A) and, as a coat, a fine dispersion in stretched state of at least two mutually incompatible polymer materials (B) and (C), (B) being compatible with (A) and at the interphase between the coat and the core being in adhesive connection with the latter, (C) being easily removable, (B) forming a fibrous structure having an average fibre diameter about or below 10p, the fibres on the average being arranged around the core according to a helical orientation.

The said filament or removal of the protective polymer yields a yarn having at its surface the above-mentioned improved properties, and getting from its core part, where such properties are of less importance, a tensile strength almost at the same level as that of a monofilament. The surface part and the core part will be in relatively strong connection partly because of the above-mentioned compatibility, and partly because of the helical arrangement of the orientation, the abrasion resistance of the yarn thus being suitable. The structure according to the invention thus presents a surprising combination of desirable yarn properties.

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The word compatibility as used above is to indicate a mutual solubility being sufficient for the formation of an adhesive bond. The expression on the average being arranged around the core according to a helical orientation is to indicate that the meshes of the said network or sponge may be strongly opened, although on the average the said fibres follow a helical orientation. The word orientation is not meant to indicate any orientation of molecules which will be optional, but indicates the arrangement of the direction of the fibre.

The components B and C are preferably selected in such a manner that B will be in the form of crystal whiskers in the filament according to the invention. Suitable conditions for producing oriented polymer whiskers for use in connection with yarn production appear in my copending application S.N. 528,916, now U.S. Pat. No. 3,499,822 issued Mar. 10, 1970. Such Iwhiskers as disclosed in the said patent are normally mutually connected through intercrystalline links having cross dimensions far below l/i. The said structure is advantageous in the present invention, as the whiskers are relatively regular and in relatively good adhesive connection through the said links.

In a preferred embodiment of the present invention, the said component B has a higher melting point or melting range than component A. During extrusion of the composite structure according to the invention, B will thlus solidify while A will sti-ll be elongated in fluid state, the result being that the relatively solid Ifibrous B material will split-up during the drawing-down of the core material A. The said splitting up increases the fluiness of the surface material formed when the protective (C) has been removed.

In another embodiment of the present invention, B has a higher module of elasticity than A. The said selection is based on the observation that the best results are obtained when the surface consists of fibres being extremely fine and simultaneously stiff, that however the core having much bigger diameter than the libres at the surface, preferably should be made from a substantially softer polymer. Thus, the core may with advantage be produced from an elastomer.

In order to obtain the above-mentioned combinations of properties in the core and surface, the polymer A may with advantage be selected as a copolymer containing a high amount of the segments from which B is formed.

The invention also provides a suitable process for producing a composite filament material of the character re ferred to. According to the invention said process comprises the steps of extruding a continuous strand of a filament forming polymer material (A), applying to the surface of said strand, while this is being extruded, a coating material consisting of a fine dispersion of at least two mutually incompatible polymer materials (B) and (C), (B) being compatible with (A) and capable of adhering thereto, (C) being easily removable, and subjecting said strand, While still in a fluid or semi-fluid state, to simultaneous stretching and twisting.

In a preferred mode of carrying out the process, this comprises the steps of mixing B and C at random to a fine dispersion, extruding said dispersion through one channel system and A through another channel system, uniting the two polymer streams in a rotating nozzle adapted to apply the dispersion as coat on A, hauling off the composite filament by means not following the rotation of said nozzle, and cooling the filament to solidification.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 shows the structure of a yarn formed from the composite filament by removal of C, and

FIG. 2 shows a nozzle system suitable for producing the composite filament.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows the fibrous sponge or network formed material B being twisted around the core material A. The meshes of the network or sponge formed by- B may be very open because of the drawing-down of the core A.

In FIG. 2, 1 is the rotating nozzle part, 2 the steady part for feeding of polymer A, and 3 is the steady inlet part for the polymer dispersion (B-l-C). The bearings and transmission means for 1 are not shown. Polymer A is fed through a channel 4, which is connected to one extruder, whereas the polymer dispersion is fed through channel 5 connected to another extruder. Channel 5 widens out to a ring-formed chamber 6, which is in connection with a series of channels 7 arranged in star-form in the rotating part. The dispersion is thus coated upon the core material in the chamber 8.

During the passage through channels 5, 6, 7 and 8, the dispersion will be strongly drawn and thus acquire a fibrelike structure in melted state.

The filament is hauled olf from the nozzle by rollers which do not follow the rotation of 1, thus the structure of the stretched dispersion will be arranged helically. Air cooling is applied to solidify the component B of the dispersion immediately after the extrusion, and the cooling eiect is so controlled that the crystallization of B takes place when A has onlyl been stretched to a very small extent, whereas a deep draw-down of the core A should be allowed after the crystallization of B.

i EXAMPLE A is a copolymer between polyhexamine-adipamide and polycaprolactam in a copolymerisation ratio of 40/ 60 (trade name Nylon 6A). B is polycaprolactam homopolymer, and C is polyethylene. The melt index of the copolymer is 2 according to ASTM No. 1238-57T condition K. The melt index of the homopolymer is 0.3 according to the same testing method, and the melt index of the polyethylene is 20 (same ASTM No. but Condition E).

The contents of polymer B is 30% of polymer A. The contents of polymer C in the dispersion with A is 40% of the total amount of dispersion.

B and C are first dry-blended, then thoroughly mixed in a so-called planetary screw extruder from which the dispersion is directly fed to the device shown in FIG. 2. The component A is fed to the dye by means of a normal extruder.

The diameter of the orifices of the extruder is 0.5 mm. and the filament is drawn down to a ydiameter of 0.08 mm., while the copolymer is still melted. The final product has a twist of about one rotation per cm.

The present invention can furthermore with advantage be carried out on other polymer combinations, e.g. with as the A component of polyurethane copolymer of elastomer character, and as the B component a compatible polyurethane homopolymer.

I claim:

1. A process for producing a composite filament material comprising the steps of providing a continuous strand of a filament forming polymer material (A), applying to the surface of said strand a substantially continuous layer of a coating material consisting essentially of a fine dispersion of at least two mutually incompatible fusable polymer materials (B) and (C) in fused condition, said material (B) being compatible with said material (A) and capable of adhering thereto, said material (C) being easily removable from admixture with said material (B),

and subjecting said strand, while the coating material is still in a fused state, to simultaneous stretching and twisting, and thereafter solidifying the composite filament maf terial.

2. A process as in claim 1, in which the polymer materials (B) and (C) are so selected that (B) is capable of forming crystal whiskers.

3. A process as in claim 1, in which component (B) has a higher modulus of elasticity than component (A).

4. A process as in claim 1, in which said material (A) is a polyurethane copolymer of elastomerY character and said material (B) is a compatible polyurethane homopolymer. u

5. The process of claim 1, wherein said filament forming polymer material (A) is fusable and is extruded in fused condition to form said continuous strand, said layer of said coating material is applied while said strand is being extruded, and both said strand and said layer of said coating material are subjected to simultaneous stretching and twisting while in said fused condition.

6. The process of claim 5, wherein the polymer material (A) has a lower melt temperature than said polymer material (B) and after said material (B) is solidified but while said material (A) remains substantially in said fused condition, said composite filament material is strongly stretched.

7. The process of claim 1 wherein the solidified composite filament material is treated to remove said polymer material (C) therefrom.

8. The process of claim 1 wherein said polymeric ma terial (A) is an elastomer.

9. The process of claim 1 wherein the diameter of said core is substantially greater than the thickness of said layer applied thereto.

References Cited UNITED STATES PATENTS l 2,171,095 8/ 1939 Orsini 264-75 X 2,174,779 10/ 1939 Delorme 264-75 lX 3,180,912 4/1965 Rowe 264-75 X 3,279,501 10/ 1966 Donald 264--209 X 3,281,897 11/1966 Mercer 264-209 X 3,415,919 12/1968 Kippan 264-174 X 3,461,197 8/1969 Lemelson 264-174X 3,439,491 4/1969 Scruggs 57-144 X 3,446,002 5/1969 Kippan -..1.--- 57-144 X 2,904,846 9/ 195 9 Smith 264-174 3,310,505 3/1967 Parker et a1 26o-2.5 3,316,336 4/ 1967 Smith 264-171 3,382,305 5/1968 Breen 264-171 3,416,982 12/ 1968 Petzetakis 264-171 3,455,773 7 1969 Tessier 264-49 3,475,898 11/1969 Magat et al. 161-180 3,479,419 1 l/ 1969 Hochhauser 264-174 3,498,873 3/ 1970 Schrenk 264-171 3,565,985 3/1970 Schrenk 264-171 JAY H. WOO, Primary Examiner U.S. Cl. X.R.