US3679541A - Sheath/core bicomponent filaments and process of preparing same - Google Patents

Abstract

SHEATH/CORE BICOMPONENT FILAMENTS HAVING A CORE DERIVED FROM A FIBRE-FORMING LINEAR POLYAMIDE OR COPOLYAMIDE AND A SHEATH DERIVED FROM A COPOLYESTER OR COPOLYAMIDE CONTAINING POLY (ALKYLENE OXIDE) RADICALS.

Description

AVAILABLE COPY vniwdsw s s 679 541 SHEATH/CORE mcorrroNEN'r FILAMENTS AND PROCESS on PREPARING SAME, Anthony Charles Davis, Pontypool, and Ian Stuart Fisher,

Harrogate, England, assignors to Imperial Chemical Industries Limited, London, England I No Drawing. Filed July 20, 1970, Ser. No. 56,667

Claims priority, applicaigr; 1 Britain, July 28, 1969,

Int. Cl. D0111; 5/28 us. CI. 161- -175 I r a Claims ABSTRACT on THE DISCLOSURE,

This invention relates to bicomponentfilaments having soil-release, anti-soil redeposition and antistatic properties, these properties being durable throughout conventional textile processing and subsequent use.

Processes for improving the hydrophilic propertiesv of polyamide textile materials are well known. For example, surface treatments by hydrophilic coatings have been proposed; however, none of these have been entirely satisfactory since they have either lacked durability or have adversely affected fabric handle.

Homofilaments comprising copolymers containing hydrophilic components have also been suggested. In most cases, the introduction of the'hydrophilic component has adversely alfec ted'the tensile properties or decreased the resistance to degradation by heat and light..

In yet another. priorart method, filaments have been produced from polyamide polymers having hydrophilic additives dispersed therein. The hydrophilic properties of such filaments, although good initially; deteriorate with treatments such as repeated washing due to leaching out ofthe additive. v T I ,We now provide a process by means of which filaments may be produced having adequate tensile properties and resistance to degradation for all normal fibre uses and at the same time having good antistatic and soil-release properties which remain throughout conventional textile processing treatments and subsequent use including repeated washing and cleaning treatments. M

According to the present invention we provide a process for the preparation of a bicomponent filament by the extrusion of two streams of different molten polymers in sheath/core relationship, the core being derived from a fibre iforming linear polyamide or copolyamide and the. sheathbeing derived essentiallyfrom a-copolyesteror copolyamide containing poly (alkylene oxide) radicals in an amount such as would result from the reaction of not less than 5 parts by weight of poly (alkylene oxide) per 100 parts by" weight of the'final'copolyester or copolyamide, allowing the conjugate stream to solidify to form a filament and subsequently drawing. Our invention also in- Q I latented July 25, 1972 Examples of simple glycols are those of the form HO(CH OH, wherein n is not less than 2 and not greater than 10, and 1:4-bis (hydroxymethyl) cyclohexane. In the term simple glycol we also include more than one simple glycol.

Examples of suitable dicarboxylic acids on which the copolyesters of the sheat may be based are terephthalic, naphthalene-2:o-dicarboxylic and l':2 -diphenoxyethane- 4:4'-dicarboxylic acids. We also include the use of more than one dicarboxylic acid. Suitable second dicarboxylic acids are, for example, adipic, isophthalic and sulphoisophthalic acids. The poly (alkylene oxide) should preferably be poly (ethylene oxide) or poly (propylene oxide), having an average molecular weight not less than 1,000 and not greater than 20,000. Preferably the average molecular weight should be not greater than 6,000. The average molecular weight in question is that for distribution of molecular weight of poly (alkylene oxide) as manufactured. It is convenient and preferred to use a poly (alkylene oxide) glycol in the preparation of the copolyester.

When the sheath is a copolyester, it is most practicable to use a copolyester of ethylene terephthalate and poly (oxyethylene) terephthalate.

Copolyamides suitable for the sheath component are based, on aliphatic a,w-dicarboxylic acid and a poly (alkylene oxide) diamine with an aliphatic a,w-diamine or an aliphatic w-amino-carboxylic acid or with both.

Examples of aliphatic dicarboxylic acids on which the sheath may be based are adipic acid, pimelic acid and sebacic acid.

Examples of suitable aliphatic diamines are those of the form H 'N(CH ),,NH wherein n is not less than 4 and not greater than 10.

The amino-carboxylic acid may be in the form of its l-act-am such as, for example, epsilon-caprolactam.

The proportion of structural units of the sheath component which are derived from poly (alkylene oxide) should not exceed that which would result from the reaction of 60 parts, preferably 40 parts, by weight of poly (alkylene oxide) in the formation of parts by weight of the final copolyester or copolyamide.

.In order to avoid spun yarn stickiness, which leads to difiiculty in unwinding packages of spun yarn during drawing, it is preferable that the proportion of structural units of the sheath component which are derived from poly (alkylene oxide) is not excessive. This proportion may be greater in the case of a higher molecular weight poly (alkylene oxide) than in the case of a lower molecular weight poly (alkylene oxide).

We have found particularly advantageous the use of sheath component of a copolyester or copolyamide which is fibre-forming and which has an efiective melting point not less than 200 C. These conditions favor successful extrusion to form filaments and successful orientation by cold drawing.

v The proportion of the conjugate filament cross-section which is composed of the sheath component should be sutlicient such that the sheath comprises a major proportion of the filament surface. It may provide an entire sheath about the core, on the other hand such proportions should not be so great that the dye-fastness and light resistance properties are adversely affected. After subjecting the sheath/ core filaments of our invention to a dyeing procedure, the resultant filaments may be reduction cleared, according to known techniques. This treatment results in removal of the dyestutf from the sheath of the filaments so that the lack of dye-fastness and the lack of light resistance normally associated with the presence of dyestuff in the material of which the sheath is composed is no longer a problem. On the other hand, the presence of dyestulf in the core of the filaments ensures the desirable coloured gfiltflam coin pea ance o the fi am n mi d th as ut in. t e. sets section. Any convenient method maybe used for the formation of the sheath/core filaments of thepresent invention, J A The filaments manufactured according to the process of our invention may be produced by the use of a multi-hole spinneret toform a yarn. which may be oriented by colddrawing according to methods known in the art.

g The sheath" and core may optionally contain additives commonly present, and in the amounts commonly used to produce, desired effects, for example colouring materials; delustrants, 'dyeing'additives and stabilizers. Such effects may be confined to the sheath or to the core. I k The filaments of our invention may be used in all tex-- tile uses, as continuous filament or staple fibre alone or in admixture with other filaments or fibres particularlywhere soil redeposition, antisoiling and antistatic vproperties are important.

, EXAMPLE 1 f A core/sheath bicomponent yarn was melt-spun at 27 5 C. from a laboratory twin barrel hydraulic extruderl The core polymer'was 6.6 nylon containing 0.3% TiO and having a relative viscosity of 37 and the sheath mer was a copolyester formed from a mixture of equal weights of poly '(oxyethylene) glycols of 4000 6000 mol. wt. (19% by wt. of copolyester), ethylene glycol, and

terephthalic acid, containing 0.5% TiO, and having an inherent viscosity of r68and containing as antioxidants 0.09% of 2,4-dimethyl-6-methylcyclohexylphenol, 0.09 of triphenyl phosphite. A S-filament yarn in 'whichthe core occupied 40% of the cross-sectional area was wound up'at 400 'ftJinin. and subsequently drawn toa'ratio of :1 usinga' snubber pin at 70 C. and a hot-plate at 175? C. The drawn yarn had a denier of 37.3, tenacity 2.5 g./ denier and extensibility 11.6%. A control'S-fiIanient yarn spun at 275 C. from the nylon polymer only and drawnunder the same conditions had a denierf of 35l0; bi .detftiiei'ffv 201, havi ng a f .7 .gJdenienand an tenacity 5.3gJ/denier and extensibility 20.1%. Each drawn yarn was four-folded and converted to a weft-knitted fabric sample. The fabrics were washedltn remove spinning finish and tested as follows: p (a) Samples of fabric'were rinsed in 0.15% aqueous potassium bromide solution and-dried; and the electrical resistance of a square of the fabric was measured after conditioning to a relative humidity of 65. Results were as I follows: bicomponent fabric-8X10" ohms; nylon control fabric-above 10 ohms. Y

(b) Samples of fabricwere impregnated with %of their weight of dibutyl phthalate and given washing treatments of different intensity. The percentage-of-theoriginal oilapplied remaining on the fabric sample were as follows:

Percent oil retained after- 6'min.in' 7' l 2hrs..ln 0.07% 1'hr.'in 0.07% 0.07% aqueous aqueous aqueous commercial commercial m soap detergent soap solution solution Sample at 60 C. at 60C. at 60 Q.

Bicomponent-l'abric 12.0 10.9 i 1o.'2 Nylon control fabric 52. 5 29. V EXAMPLEZ I, f

' A525 denier yarn consisting of 40 core/sheath bi' component filaments was spun and wound up'at 1718-fill min.-using the apparatus described in British patent cification No. l,100,430. The volume ratio of-co re to sheath was 80/20. The "core component awas 6.6' nylon :centric conformation and of circular or non-circular crosshate w s econtalnmg 0.3% TiO,

Example 1. The yarn was cold-drawn to'a ratio of 3.21 giving an oriented yarn of'i'denier 209 with a tenacity of 3.3 gJdenier and extensibility 41%. A control yarn was spun from a standard nylon .melt-spinning unit at 1718 ftJmim, using the. same ny1on polymen: and ::dr;awn toa ratio of 3.21to an oriented yarn of denier 208, tenacity 3.75 g./denier and extensibility 47%. Each yarn was 'converted to woven-fabric and the fabrics were scoured in a detergent/sodium carbonate I solution at, C. One portionof ach fabric was rinsed in distilled -water*andf'" other in 0. 15 %-p otassiiim bromidesolutioiii Both fabrics were dried and conditionedin air of known relative humidity, and the fabric electrical resistance was .measured; with the' fabric sample resting on an insulating" sheet, the DC. resistance was "measuredbetween concentric circular metaltelectrodes,resting on the upper surface of the fabric and of such dimensions that theannular gap had an inner diameter of50.'8' mmla d an outer diameterof 58.8 mm; Results were asfollowsi H Bicomponent yarn Control nylon yarn Water I KBr Water KBr rlnse H rinse rinse v r 1 rinse 6X10 5x16 4.6X10 1.2xi6 'i polyether glycols was increased to 25% of the total weight e ac ete- 11 We a .d weare 's bbst pin .at.90? C..to a ratio of. 3 .49 t gi an oriented yarn extensibility of 56%. A'con tr'ol' 'y'arn was spun and. ewn. m the ny a o a eonly. wi thcj'same pm es' f n i ic siti a drewnyau c' 1 d ie h s a' tenacity of 4.4.Yg./,de nier and aii e xtensibilit y of. 60%. The two yarns werescp ately converted to woven r s wh h .iwq e e a e ec r c esi n e measurement by scouring and .rinsingas in Example ,2,

The tendency of the scoured fabrics to, cling due to electro:

static charge was, assessed comparatively by. frictional. electrification against (ethylene terephthalate) fabric; the electrified sampleswere allowed to cling to an earthe'd metal plate at 7O It'o.the horizontal and the timefor which clinging continued was measured. "Measurements were m d We. new 3' and having relative viscosity of .42.,.and..the. heat po ymer. w s.. hecppqlmtetusciiu R.H. of 38%.

BET AVAILABLE COPY orders (depending on .the ionic content of theyarn ,ples) below that of controlnylonyarmand to have no fiction No. 1,100,430. Thevolume ratio of core to sheath was 80/20. The core component was 6.6 nylon containing 0.2% TiO, and' having a relative viscosity of 45, and

-the sheath co'mponent was the-copolyester used in'Example l." The spun'yarn was two-folded and drawn and ci-imped in one operation, giving a bulky yarn containing l38 filaments havinga denier of 2334, tenacity'2.34

'gJdenier and extensibility 41%. The yarn was used 'to construct a loop pilecarpet bytufting into a hessian backing. An adjoining section. of carpet was tufted with a standard crimped carpet 'yarn of the same 'nylon polymer 1 of 2450 denier. Separate lengthsof carpet each incorporating both types of yarn were finished (a) by. a detergent/sodium carbonate scour and water rinse, and (b) by dyeing with Duranol blue BN 300 (1% on weight of carpet).

The carpet pieces after drying were given a secondary bessian backing with a latex adhesive and their electrical properties were assessed under defined humidity conditions by resistance testing and static charge generation measurement. Electrical resistance was measured as in Example 2. Static charging propensity was assessed by measuring the body voltage acquired by a person walking on the carpets with shoe soles of either leather or a composition material, and the time for the voltage to decay to half its value was recorded. Results were as iz'or the copolyamide. Each yarn was cold-drawn to a ratio-=ofr. 4.0, giving oriented yarns with the following physical properties:

Tenacity Extensibility p I Denier (gJdenier) (percent) Bicomponent yarns 26. 8 3. 5 43. 8 copolyamide yarn 35. 9 3. 2 39. 2 Nylon 6.6 yarn 35. 9 5. 2 69. 6

Each' yarnwas knitted into a hose-leg panel, which "measured after conditioning was scoured in detergent/sodium carbonate solution to remove spinning finish. Tests to determine the electrical and hydrophilic properties were made as follows:

* (a) The electrical resistance of a square of fabric was in an atmosphere of relativeihumidity 31 or 60. *(b) *Squares of fabric were electrified by friction against talc and allowedjto cling against a vertical electrically'e'arthed metal surface in an atmosphere at relative humidity-30. The time until the'sample dropped away was measured.

E (excellent)--oil collects into drops which float off the fabric in under one minute VG (very good)oil droplets released slowly during 5 minutes G (good)oil collects into droplets which cling to the follows: fabric Carpet resistance (ohms) Static charge in walking at 40% RH.

Maximum voltage (kv.) Decay time (see) Composi- Leather Composi- Leather Yarn type R.H. 65% RH. 40% tion sole sole tion sole sole Bi-com orient..." 6. 1X10 11 2Xl0 3 1.5 20 20 Contzo nylon 1. 1X10 2X10 4 2.5 25 30 The results showed that the electrical resistance of the bicomponent filament carpet was less than that of a normal nylon carpet, and that static charges generated were smaller and decayed more rapidly, thus lessening the risk of an unpleasant electric shock.

EXAMPLE 5 A S-filament core/sheath bicomponent yarn was melt- M (moderate)-oily area contracts but does not all collect into droplets P (poor)oily areas unchanged or widening.

Fabrics were tested for oil-release properties in the scoured state and after 1 hour or 3 hours of washing in 0.4% Persil at C.

Test results are shown in the following table.

Electrical resistance Hydrophilie properties (ohms) Duration-- of cling Washed Washed 60%R.H. 31% RH. (sec.) Secured 1hr. 3hrs.

Bicomponent yarn 2.5Xl0 7.0X10 81 VG G-VG G-VG copolyamide yarn 2.9Xl0 7.0Xl0 115 VG- VG G-VG Nylon6.6.yarn 6.5)(10 1.0)(10 300 M P P spun at 310 C. using the apparatus of Example 1 and wound up at 400 ft./min. The core polymer was 6.6 nylon containing no additives and having a relative viscosity of 45. The sheath polymer was a copolyamide prepared from hexamethylenediamine, adipic acid and a diamine prepared from polyoxyethylene glycol of molecular weight 1540 by reaction with thioryl chloride followed by ammonia, substantially as described in British patent specification No. 948,507. The weight proportion of the polyether diamine in the copolyamide was 15%, and the sheath occupied 40% of the cross-sectional area. Control 5-filament yarns were spun using a single-barrel extruder from the separate polymers alone, with a melt temperature of 3. A sheath/core bicomponent filament according to 292 C. for the 6.6 nylon homopolymer and 290 C. claim 1 in which the poly (alkylene oxide) is poly (ethylene oxide) having an avgfage molecular. weight in the 'nge'-1,000"t020;000 inclusive. f 1* 4; LA: sheatli lcorerrbicpmponent 'filament-"l'aiccordin'g :to claim 1 in which the copolyester of lthejhe'at hcontains ;b ;.;w s t q P971)! (alisyly smsisle). 2st 09. art e y dieifilit of the;,;s a id copolyester. I a"; 1,5. A sheath/core bicqmponent filament aeeordingfto vizlaimd in'which .zthe Sheathecomprises oascopolyesterof .my

I oxlqe) per 100 ggrtshy veight of sgigleopplyester.

iziEld Boil NEH, Pmnar time;

component occupies no leg; than 5% and no greater than 33%offlthe cross-sectional area-of the filament: 1 1+ 8; :A process according-to c1aimi6- in which the copoly- =estenfof thesheatheontains poly (alkyleneroxide-yradiczils in an amount such as would result from ,tliereactionzof not more than 40 paitsfby wweight of poly (alkylene LlhlK ERg lm, Examiner I f U.S.'Cl. X.R.e V