IL27128A - Surface modified nylon fibers - Google Patents

Description

■j g □ Patents Form No. 3 PATENTS AND DESIGNS ORDINANCE.

SPECIFICATIO .

•'SURFACE MODIFIED NYLON FIBERS" wn3 oiras 3»t^ p »»a »a»o» I / WE - and. existing under 1^ Sta s Pf America,..^ ..L.oui. ..^ do hereby declare the nature of this invention and in what manner the same is to be performed, to be particularly described aud ascertained in and by the following statement : - This invention relates to novel synthetic textile fibers of nylon and to the processes for their manufacture.

An object of this invention is to provide novel nylon textile fibers having improved properties which fibers are useful in the manufacture of yarns and fabrics.

Another object of this invention is the provision of a modified nylon fiber wherein said modification occurs without substantially degrading the bulk tensile properties of the fiber. Still a further object of the invention is to provide a continuous process for modification of nylon fibers which can be adapted to commercial manufacture of nylon fibers without disruption of the continuity of the overall manufacturing process .

It has been discovered that the surface properties of nylon fibers can be significantly modified by rapid halogenation of a preformed fiber of a nylon polymer such that the concentration of halogen attached to the surface of this resulting fiber ranges from about 50 to about 5*000 parts by weight per million parts of fiber. In accordance with this invention the concentration halogen bound to the fiber is essentially limited to the surface of the fiber or to the fiber skin so that the bulk tensile properties of tenacity and elongation are not substantially modified. Useful products are obtained where the halogen is chemically bonded to the nylon molecules occurring on the surface of the fiber in the form of covalent bonds, i.e., halogen substitution on carbon; coordinate bonds, i.e., where a diatomic halogen-amide group adduct or a change transfer complex is formed, and both covalent and coordinated bonds in the sense above described.

One method employed for nylon fiber modification comprises passing the fiber through a halogen atmosphere in the absence of an initiator in such a manner that the concentration of halogen and period of residence does not allow diffusion of the halogen into the core of the fiber, but rather limits the reaction to the surface of the fiber. This process results in a modified fiber wherein the halogen is bondei to the surface or skin of the fiber predominantly in the form of a halogen-amide group adduct which may otherwise be described as a change transfer complex. Exposure of the product formed by the above described procedure to ultraviolet or other energy source results in rearrangement of the halogen atoms such that a portion of the coordinate bonded halogen atoms substitute on the surface molecules in the form of a covalently bonded halogen.

Another method for forming the surface modified fibers of this invention wherein halogen is found bonded both in the form of a substituent and as an adduct resides in simultaneously subjecting the preformed nylon fiber to the action of halogen and an initiator for halogenation, such as ultraviolet light.

The lieht accelerates the formation of the diatomic chlorine-amido adduct as woll as forms chlorine atoms which react with the hydrocarbon portion of the chain to substitute chlorine on the carbons and j& to the amide nitrogen. These conclusions are verified on the NMR spectra of chlorinated and photo-chlorinated Ν,Ν'-dipropyl succin amide which was used as a model compound.

While it has been determined that the covalently bonded halogen atoms are permanent in the sense that they are not removed by washing, laundering and other conventional textile treatment, it has been discovered that the halogen present on the surface of the fiber in the form of a halogen-amide group adduot can readily be removed by washing with water, or by extraction with polar organic solvents, such as methanol. Reversibility of the adduct formation provides a route for temporary disruption of the physical state of the surface layers of nylon fibers.

The modification of nylon fibers occasioned by the presence of halogen bound to the polymer molecules results in increased wettability of the fiber surface.

This property is beneficial in several respects in that wearing apparel which cannot adequately transfer moisture and/or moisture vapor away from the body is uncomfortable, etc. Increased wettability of the fibers of this invention results in a more silk-like feel to the wearer.

Moreover, this property is permanently built into the fiber and does not suffer diminution upon ordinary laundering as do many hydrophilic finishes.

Another benefit derived from the modified fiber of the invention based on increased wettability resides in the enhanced adherence to the fiber surface of amine and other types of finishes.

Another and distinctly different benefit derived from the product of this invention is that the chemically bonded halogen atoms on the surface of the fiber represent sites for secondary reactions involving further fiber modification. Thus, primary and secondary, mono and pol amines may be reacted with the chlorine atom substituted on the surface of the fiber to further substitute or modify the chemistry of the fiber surface. Amines so substituted have been quaternized to enhance to anti-static properties of the filament in a manner similar to conventional anti-stat finishes. In the instant invention the molecular groups which provide anti-static properties to the fiber are permanently and chemically bonded to the fiber whereas prior art antistatic agents generally have been applied as coatings which are subject to removal in ordinary use.

While modifications of surface properties occur over a broad range of halogen concentrations on the fiber surface, changes become more pronounced in the higher ranges. Moreover, secondary reactions occur with greater ease where the occurrence of halogen reaction sites is greater. This is not to say, however, that beneficial properties are not observed at levels of halogen which are quite low. The limiting factor with respect to the level of halogen appears to be the highest concentration possible without serious degradation of the bulk tensile properties of the fiber and this may be governed by the particular use intended for the fiber.

The materials used to form the fibers having a modified surface structure according to this invention are conventional nylon or linear polyamide materials such as those described in United States Patents 2,071,230, 2,071, 253 and 2, 130, 948. These materials are well known in the art and are usually formed by reaction of suitable dicarboxylic acids with suitable diamines or by polycondensation of suitable monoamino monocarboxylic acids or derivatives thereof. Methods for the formation of fibers, yarns, knitted fabrics and woven or non-woven fabrics from nylon polymers are well known in the art and are not a part of this invention. It is intended, however, that fiber modification may occur according to the practice of this invention at any stage in the processing of the fibers to form fabrics or on the fabric itself.

The terms fibers and filaments are used interchangeably herein to connote staple length or continuous filamentary structures of nylon polymers useful for textile or other applications.

The preferred process for the surface modification of nylon fibers according to this invention involves photo-halogenation wherein the fiber is subjected to halogen in the presence of ultraviolet light for a period of less than about two seconds. The halogen may be present in an illuminated chamber through which the fiber, yarn or other fiber containing article is continuously passed. The halogen may be diluted, if desired, by nitrogen or other inert gas. The light source may be other than ultraviolet providing the intensity is adequate to affect photochemical halogenation.

Generally speaking, bulbs emitting light having wave lengths in the range between 3300 and 1+800 Angstroms are suitable. The essential feature of the process is that the conditions be so correllated that the reaction occurs only on the surface or skin of the fiber* The halogen should not be allowed td diffuse into the core of the fiber because interior penetration is likely to degrade the bulk tensile properties of the fiber and thereby offset the beneficial aspects of surface modification.

The term halogen as herein used is intended to include those halogens having an atomic number between 17 and 53. Thus, chlorine, bromine, iodine and mixtures thereof, such as a mixture of chlorine and bromine are useful in the preparation of the modified halogenated products of this invention.

Example I Polymerization About 17!? grams hexamethylene ammonium adipate and 58 ml. water are charged to a high pressure stainless steel autoclave and purged with nitrogen.

The contents are heated to 2i.3°C while maintaining a pressure of 17.58 Kg/cm gauge. During this period the reaction mixture is continuously agitated by means of a stirrer. The pressure is reduced to atmospheric over a 2 minute period while the temperature of the reaction mixture approaches 275°C. The polymer melt is allowed to equilibrate for 30 minutes at 275°-280°C and then spun through a four-hole spinnerette.

Chl rination The apparatus used for chlorination consisted of a 8.89 cm x 55.88 cm Vycor glass tube with a 19.05 cm open end metal extension at the bottom.

Extending laterally from the extension is a 10.16 cm flexible exhaust tube leading to the laboratory hood.

A mixture of and Cl^ is metered through a polyethylene tube situated so that it lies vertically on the inside glass wall with the exit about 7.62 cm from the spinnerette face. At about 22.86 cm from the side of the glass tube is placed an 8 watt ultraviolet lamp whose major wave length is 3660 Angstroms.

Chlorine and nitrogen are introduced at rates of 9.9 x 10"^" and 7.9 x 10"^ m -Vmin. > respectively, so that the atmosphere inside the tube is replaced every minute and 57 seconds. The fiber is ordinarily taken on bobbins at a rate of 1+7.73 m min. or a residence time of 0.1+8 second inside the chlorination tube.

Control filament was spun in an identical manner in the absence of chlorine and ultraviolet light.

Properties of Control and Chlorinated Samples Draw Ratio Elongation Tenacity Modulus ½C1 Control No. 5 78114.-1 5.75 19.9 5.8 3 Too low to detect Chlorinated No. 512728 1+.65 32.9 3.5 27 0.21 The % chlorine figure is equivalent to 2100 parts per million. In similar examples chlorination levels reached I4.OOO ppm, but filament physical properties are not available for these samples.

Tenacity reduction is obviously appreciable. However, tenacities of 3-5 gpd are still adequate for most uses; and, if desired, one can hold chlorination to a lower level, holding tenacity loss also to a lower level and still get reasonably significant surface effects and a reasonable concentration of sites for secondary reaction.

Example II A polymer of nylon 66 having a relative viscosity of 50.7, 52. - x 10"^ eq./gm. of carboxyl end groups and 59.3 x 10"^ eq./gm. of amine end groups was spun into monofilament and then drawn without application of finish. Several samples of the filament were passed through a glass tube having an atmosphere rich with gaseous chlorine and exposed as indicated to the light of a I . watt black light lamp emitting light having wave lengths ranging from 3000 to lj.000 Angstroms. The results of the several runs where determined are indicated in the following table.

TABLE Sample Exposure Cl Plow Rate Cl Analysis Den C?2COndLight CC SeC After H20 Extraction « lk$ 0.6 0.6 550 15. liOl- 0.9 0.9 250 15. 3 k 0.9 0.9 250 169 1.2 1.2 250 I80 11+. 332 7.0 7.0 0 68 1+12 7.0 0 250 0 333 12 12 250 ll+.

ND-2* 0 0 0 0 U4..

^Control, not chlorinated or exposed to light

Claims (8)

t # HAVING NOW particularly described and ascer ain d the nature of our said invention ana in what manner the same is to be performed, we declare that what we claim is $ amssxBsasKxsii

1. A halogen modified nylon fiber characterized in that said halogen is attached to polyamide molecules essentially on the skin or surface of the fiber in amounts ranging from about 50 to about 5* 000 parts by weight per million parts of fiber, said halogen having an atomic number between 17 and 53·

2. The fiber of Claim 1, characterized in that the halogen is chlorine.

3. The fiber of Claim 2, characterized in that the chlorine atoms are chemically attached to the fiber surface by a bond selected from the group consisting of covalent bonds, coordinate bonds on change transfer complexes and both covalent and coordinate bonds .

4. The fiber of Claim 3, characterized in that the chlorine is attached to the fiber surface by covalent bonds .

5. The fiber of Claim 3, characterized in that the chlorine is attached to the fiber surface by coordinate bonds .

6. The fiber of Claim 3, characterized in that said chlorine is attached to the fiber surface by both covalent and coordinate bonds .

7. The fiber of Claim 1, characterized in that the halogen is bromine.

8. The fiber of Claim 1, characterized in that the halogen is a mixture of chlorine and bromine. Dated this Twenty-first day of December 1 66 ' f) I A«E, ULPORD