CA2208231C - Additive-containing polymer compositions and methods of making the same - Google Patents

Abstract

Disclosed is a polymer composition including nonaqueous additive system having dispersant-coated pigments physically dispersed in a liquid nonaqueous polymeric carrier which may be added directly to a melt flow of a polymeric host material. The additive system employed in the polymeric systems is is most preferably in the form of a particulate paste which can be added in metered amounts (dosed) to a melt flow of the polymeric host material prior to being spun into filaments. By providing a number of additive systems having a number of different additive attributes, and controllably dosing one or more into the melt flow of host polymeric material, shaped objects of the polymeric material (e. g., melt-spun filaments) having different additive attributes may be produced on a continuous basis without shutting down the shaping operation.

Description

ADDITIVE-CONTAINING POLYMER COMPOSITIONS AND METHODS
~~ MAKING THE SAME
CROSS-REFERENCE
This application is a division of application n°

2,191,990 filed on December 3, 1996.
The present invention generally relates to thermo-plastic polymeric materials containing one or more additives.
More specifically, the invention as broadly disclosed, relates to synthetic filament additives (e. g., colorants) and to methods for incorporating such additives in melt flows of filament-forming thermoplastic polymeric materials prior to melt-spinning to form synthetic filaments therefrom.
However, the invention as claimed is restricted to an additive containing polymer composition comprising an additive-containing polymer composition comprising a polymeric host material and an additive system comprising dispersant-coated pigments in a liquid nonaqueous polymeric carrier dispersed throughout the polymeric host material.
BAC~CGROUND AND SUMMARY OF THE INVENTION
The incorporation of additives in so-called "neat"
thermoplastic polymeric host materials (that is, polymeric materials containing no additives) so as to achieve desired physical properties is well known. Thus, the art has conventionally incorporated colorants, stabilizers, delusterants, flame retardants, fillers, antimicrobial agents, antistatic agents, optical brighteners, extenders, processing aids and other functional additives into polymeric host materials in an effort to "engineer" desired properties of the G:
z:esulting additive-containing polymeric host material. Such additives are typically added any time prior to shaping of the polymeric material, for example, by spinning or molding (e. g., extrusion, injection, or blow-molding) operations.
The incorporation of colorant additives in filaments formed by melt-spinning a polymeric material has presented unique challenges. For example, the amount of particulate pigment dispersed in a concentrate which is added to the polymeric material must be sufficient:Ly high. to impart satisfactory color density, but must no~v be so high as to interrupt the spinning process. One ~~rior proposal for incorporating colorant additives in thermoplastic polymeric materials is disclosed in U.S. Patent No. 5,236,645 to Frank R.
Jones on August 17, 1993 According to the Jones '645 patent, additives are introduced into a thermoplastic melt by feeding at least one additive in an aqueous vehicle containing a dispersant to form an aqueous additive stz:eam to a vented extrudE~r which is e:ctruding a thermoplastic. The aqueous portion of the aqueous additive stream is thereby volatilized within the extruder and i.~ removed therefrom via an extruder venf:. As a result, a substantially homogeneous system containing the thermoplastic, dispersant and the additive is obtained which may thereafter be spun into a filament by melt-extrusion through filament-forming orifices in a spinneret associated with a sgin pack assembly.
Although the techniques disclosed in the Jones '645 patent are entirely satisfactory, some further improvements to incorporating additives in a melt flow of thermoplastic polymeric materials would be desirable. For example, it would especially be desirable if the additive stream was non-aqueous as this would obviate the need for a vented extruder (i.e., since a volatilized aqueous portion of the additive stream would not then need to escape prior to melt-spinning).
3G Furthermore, it is entirely possible that a non-aqueous additive stream could be introduced physical7_y near or into the spin pack assembly where it can be mixed with a melt flow of the polymeric material immediately upstream of the spinneret orifices (and preferably downstream of the polymer filter section of the spin pack assembly) thereby bypassing the extruder. Such a possibility would then allow additive concentration and/or types to be changed an a continuous basis to produce sequential lengths of melt-spun filaments having desired, but different, properties and,/or characteristics.
That is, the upstream processing equipment, for example, the extruders and process piping, which supply the polymeric host material to the spin pack assembly would not necessarily need -to be shut down for purposes of cleaning. Furthermore, by :introducing a non-aqueous additive stream directly into the spin pack assembly, the flushing time woulr.~ be relatively short thereby allowing, for example, quick color changes to occur :From one filament: production batch to another. :Ct is towards providing such improvements that the invention as broadly disclosed hereinafter is directed.
The present invention is concerned with a nonaqueous additive concentrate system for thermoplastic polymeric host materials which may be added directly t:o a melt flow of the polymeric material in metered amounts.
More particular 1 y, the _i.nvernt i.c,~n as claimed is concerned with an additive-containing thermoplastic polymer composition comprising:
a) a thermo~~l.ast:.,c melt--spinable polymeric host material, and b) an additive syst=em di spersed throughout said thermoplastic melt-sp«rua~l~>. polymeri_~~ host. material, wherein said additive syastem comprising:
(:L) a disper~>ant ~:olymer, (2) pigment partic:ales coated k:.~y sold dispersant polymer so as to form a c~lispersant-c~odted ~;igments, and (3) a liquid nonaqueaus polymeric carrier in which said dispersant-coated pigments ara~ dispersed.
The additive system is most preferably in the form of a particulate paste which can be added in metered amounts (dosed) to a melts flaw of t:.he polymeric host material prior to beinu spur': into filaments. F3y providing a number of additive systems having a nmmber of different additive attributes, and controllably casing one or more into the melt flow of polymeric material, melt-spun filaments having different additive :attributes may be produced or. a continuous basis ( i . a . , wi ~:hout shutting down the spinning operation). 'The present invention is particularly advantageous to produce or; a continuous basis sequential lengths of filaments having different color, attributes.
The additive concentrate system according to the present invention includes a filament additive which is dispersed in a liquid or liquefied nonaqueous carrier. The .filament additive may, during use, be in the form of a solid particulate or a liquid. 4Jher~ a solid particulate is used, the ,additive system of this invention most preferably also includes a dispersant which coats the particulate additive. The additive concentrate system according to this invention is most preferably in the form of a flowable paste which can be added :in metered amounts (dosed) to a melt flow of the polymeric material prior to being spun into filaments, for example near or into the spin pack assembly upstream of the assembly's filament-forming spinner-et orifices.
In such a manner, therefore, synthetic filament batches having different additives may be produced sequentially on a continuous basis without costly equipment downtime. That ~-s. the same spin pack assembly may be used to produce a first batch of filaments containing one type of additive during one production interval, and then used to produce a second batch of 4a filaments containing a second type of additive during a succeeding production interval by changing the additive which _ is introduced into the filament-forming melt. Moreover, the time interval needed to change between different additives is relatively short since the additive system is. most preferably.
introduced, into the melt flow near or into the spin pack assembly which in turn reduces significantly the time needed to flush residual additive incorporated into the first batch of filaments. Production of different additive-containing to filaments (e.g., filaments containing different colorants) is now possible in a relatively: short period of time without stopping filament winding.
Another aspect of this invention relates to a method of making a dispersible additive system containing polymer compositions comprising the steps of:
(i) forming a dispersible additive system by;
(1) coating pigment particles with a dispersant so as to form a dispersant-coated pigment particles;
(2) spray-drying said dispersant-coated pigment 20 particles so as to form a spray-dried,, dispersant-coated pigment particles, and thereafter, (3) introducing a spray-dried, dispersant-coated pigment particles into a polymeric carrier; and (ii) dispersing the additive system into a thermoplastic melt-spinable polymeric host material to form an additive-containing thermoplastic composition.
Thus, another aspect of this invention involves a method of continuously producing sequential lengths of S
different additive-containing filaments by continuously supplying a melt-spinnable polymeric host material to orifices of a spinneret and, during a first time interval, controllably dosing a concentrate system having one additive into the polymeric material to form a first polymeric mixture which is extruded through the spinneret orifices. Subsequently, during a second time interval, another concentrate system containing a different additive is controllably dosed into the polymeric material without disrupting the continuous supply of polymeric material to the spinneret orifices to form a second polymeric mixture which is extruded through the spinneret orifices.
During the change of additive concentrate, an intermediate time interval will be needed in order to flush the spinneret of residual amounts of the first additive concentrate. Thus, during the intermediate time intervals, an intermediate length of filaments will be produced which will change over the filament length from containing all of the first additive concentrate to containing all of the second additive concentrate. This intermediate length of filaments produced according to the present invention will be handled separately from the first and second lengths of production filaments. However, the amount of such intermediate length of filaments will be relatively small since, as noted above, the time interval needed to flush the spinneret of residual amounts of the first additive concentrate is relatively short.
Other advantages ensue from introducing the additive concentrate system to the polymeric host material within the spin pack assembly. For example, the spin pack assembly and its associated spinneret orifices may be so designed to form melt-spun multicomponent filaments (e. g., filaments having multiple domains of different polymer blends, colorants and/or other additives) such as those filaments disclosed in U.S.
Patent No. 5,162,074 to Hills by splitting a melt-flow of polymeric host material into two or more subflows within the spin pack assembly. According to the present invention, therefore, the additive concentrate system may be introduced G
into the spin pack assembly and mixed with one or more of such subflows of polymeric host material without being mixed with other subflows so as to form multicomponent filaments.
Therefore, while the discussion which follows emphasizes the production of filaments in which the additive concentrate system is substantially homogeneously mixed through the filament cross-section, it will be understood that the present invention is likewise applicable to the formation of multicomponent filaments whereby the additive concentrate system is substantially homogeneously mixed throughout one or more multiple polymeric domains in the filament cross-section without being present in the other domains) (e. g., as in core-sheath filaments, pie wedge filaments, side-by-side filaments and the like).
As noted above, significant processing flexibility ensues according to the present invention. Processing flexibility is the result of at least two features of the present invention. First, additive concentrate systems can be mixed above the spinneret with either the entire host polymer or only a portion of the host polymer. For example, a functional additive (e. g., an antistatic agent) concentrate system might be mixed with only a third of the host polymer such that a third of the filaments spun contain the antistatic agent and the remaining two-thirds do not.
Second, two or more additive concentrate systems can be mixed with ,the host polymer above the spinneret to achieve a single attribute in the fiber that is spun. For example, a yellow additive concentrate system and a blue additive concentrate system can be concurrently mixed with host polymer above the spinneret to provide ~ green fiber when the mixture is spun. There is no theoretical limit for the number of additive concentrate systems that can be mixed with the host polymer above the spinneret. The number of additive concentrate systems is limited only by the space available to inject the systems into the line. It is contemplated that the host polymer might also contain some additive prior to mixing above the spinneret.
These two features of the present invention are not mutually exclusive and great flexibility ensues from combining them. Using color as an example, either single color or multicolor yarn can be spun using the present invention.
Single color yarn may be spun by mixing one or more color additive concentrate systems (e. g., a yellow system and blue system as exemplified above) with the entire host polymer such that a one color yarn (e. g., a multifilamentary yarn containing only green filaments) results.
Multicolor yarn (e.g., heather yarn) may be spun by selectively coloring separated portions of the host polymer and keeping each separated portion segregated until spun. For example, a portion of the host polymer might be colored with both the yellow and the blue additive systems to produce green filaments. Another portion of the host polymer might be colored with a red additive system to produce red filaments which are spun concurrently with the green filaments. The resulting multifilamentary yarn will therefore exhibit a heathered color due to the combination of individual red and green filaments present in the yarn.
The concepts above apply also to the spinning of filaments having multiple cross-sectional domains, such as core-sheath filaments, pie wedge filaments, side-by-side filaments and the like. Thus, for multidomain filaments, the additive concentrate system may be mixed with one or more split flows of the host polymer and then recombined with the remainder of the host polymer flow to achieve filaments having the additive present only in one or more of the cross-sectional domains.
When the additive is a colorant, therefore, a virtually unlimited number of multicolored, multidomain filaments can be produced. For example, only the core of a core-sheath filament may include one or more colorant additives which imparts to the fiber a color attribute that is visibly perceptible through the uncolored sheath. In this regard, it has been found that colorant additives) contained only in the core of a core-sheath multidomain filament results in a color intensity that is achieved with reduced colorant loading levels (e.g., between about 5 to about l00 less) as compared to filaments having the same colorant additives) homogeneously dispersed throughout the entire filament cross-section to achieve comparable color intensity.
Alternatively or additionally, the colorant additive may be present in the sheath of a core-sheath filament so as to achieve a color effect that is a combination of the core and sheath colors. Thus, by selectively choosing and incorporating colorants into the core and/or sheath, virtually any color attribute can be achieved for the resulting filament. some particular combinations of colorants in both the core and sheath of a core-sheath filament may not necessarily result in a "pure" color combination of such colorants being realized for the filament. That is, the additive/subtractive effects of colorants in the core and sheath of core-sheath filaments are relatively complex and sometimes cannot be predicted with absolute certainty. However, routine experimentation with colorants in the core and/or sheath of core-sheath filaments will result in virtually an unlimited number of desired filament color attributes being obtained.
Other multiple domain filament combinations are envisioned, such as side-by-side domain filaments having different color attributes in each of the sides or pie wedge filaments whereby one or more of the wedges have the same or different color attributes. Such multiple domain filaments may be usefully employed to form heather yarns since the color additive-containing domains will visually present themselves at different locations along the length of the filaments when twisted (e. g., as may occur during yarn processing).
Furthermore, the colorants and domains in which such colorants are present can be selected to achieve filaments which macroscopically appear to be uniformly colored.
Furthermore, although the additive concentrate systems of this invention may be metered (dosed) into the host polymer (whether in its entirety or in one or more of its split flows) at a substantially constant rate, periodic or continual variance of the dose rate is also envisioned. Thus, as noted briefly above, when changing from one filament recipe to another, one or more of the additive concentrates will need to be varied in order to switch filament production from a former recipe to the then current recipe. A random or constant dosage rate variance can also be practiced, however, in which case the resulting filaments will have more or less of the additive distributed along its length. When the additive is a colorant, such a technique allows filaments to be formed having a slub-like color appearance along its axial length which may be employed, for example, to produce yarns having a striated or marbled impression.
These and other aspects and advantages of this invention will become more clear after careful consideration is given to the following detailed description of the preferred exemplary embodiments thereof.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
Reference will hereinafter be made to the accompanying drawing wherein FIGURE 1 is a schematic view of a filament melt-spinning apparatus in which the additive system of this invention may be added to a melt flow of polymeric material prior to spinning.
DETAILED DESCRIPTION OF THE PREFERRED
EXEMPLARY EMBODIMENTS
To promote an understanding of the principles of the present invention, descriptions of specific embodiments of the invention follow and specific language describes the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, and that such alterations and further modifications, and such further applications of the principles of the invention as discussed are contemplated as would normally occur to one ordinarily skilled .in the art to which the invention pertains.
Thus, for example, while reference has been, and will hereinafter be, made to melt-spinning of filaments, it will be understood that other operations which serve to shape a melt of a polymeric material to a final form (e.g., extrusion or :injection molding, blow-molding or the like) are contemplated.
Furthermore, for ease of reference, the discussion which follows will emphasize the presently preferred embodiment of 10 the invention in terms of incorporating colorants into polymeric materials, but the present invention can likewise be employed to incorporate virtually any other conventional additive as may be desired. zn this regard, the term "pigment"
as used herein and in the accompanying claims is meant to refer t.o virtually any material that may be added physically to a polymer melt flow, and thus generically encompasses colorant pigments which will be emphasized in the discussion which follows. Thus, suitable pigments which may be employed in the practice of this invention include solid and liquid colorants, stabilizers, delusterants, flame rei~ardants, fillers, antimicrobial agents, antistatic agents, optical brighteners, extenders, processing aids and ether functional additives.
As used herein and in the accompanying claims, the term "color" includes Munsell Values between about 2.5/ to about 8.5/ and Munsell Chromas greater than about /0.5. (Kelly et al, The ISCC-NBS ~fethor' of Designating Colors and a Dictionary of Co3or Names, National Bureau of Standards Circular 553, pp. 1-5 and 16 (1955).
The host polymer in which the additive concentrate system of this invention may be incorporated includes any synthetic thermoplastic polymer which is melt-spinnable.
Exemplary polymers are polyamides such as poly(hexamethylene adipamide), polycaprolactam and polyamides of bis(4-amino-cyclohexyl) methane and linear aliphatic dicarboxylic acids containing 9, 10 and 12 carbon atoms; copolyamides; polyester such as poly(ethylene)terephthalic acid and copolymers thereof;
polyolefins such as polyethylene and polypropylene; and ;polyurethanes. Both heterogeneous and homogeneous mixtures of such polymers may also be used.
:I. Additive Concentrate PrP~arat.j~on As noted above, the additive concentrate system employed in the practice of the present invention is a dispersion or solution of pigment in a nonaqueous liquid or liquefied polymeric carrier. The pigment may be a solid particulate (e.g., a colorant) which is coated with a dispersant for physical dispersion in the carrier material.
Preferably, t:he method wherein the spray dried dispersant-coated pigment has an averagE= particle size of about 5 ~.m or greater prier to being blended with the thermoplastic melt-spinable polymeric. host material according to step (i.i), and wherein the dispersart-coated pigment has an average particle size of about 1 um or less after dispersion into the poiymeri.c host. material according tc step ( ii ) .
Alternatively; the pigment may be in a form which is soluble with the carrier, in which case the dispersant is not necessarily emplo=aed. Thus, the pigment may :zomogeneously be suspended and/or sclubilized in the ~~arrler.
Although a variety of pigments may be employed in the practice of the present invention, it is presently preferred i~hat the pigment is a particulate colorant pigment having a mean particle size of Less than l0 ~cm, preferably less than about 5 ~cm, and most preferably between 0.1 um to about 2 ~.m.

11a If present, the preferred dispersants which may be employed in the prac_aice of this invention are the water soluble/dispersible po:Lymer:-~ as described in IJ. S. Patent No. 3,846,507. One particularly useful dispersant in this class is a copolymer of capro:la~:t=am/hexamethylene-diamine/isophthalic acid; sodium salt of sulfoisophthalic acid having a molecu:Lar weighc~ of about 7, 000, a specific gravity (H20=1) of about ~.1, a sol.ubi~.ity in water of about 25° at 20°C. Thin. preferred water soluble/dispersible polyamide copolymer disper.sant is manuactured by BASF
Corporation and will hereinafter be referenced as "C-68".

Other useful dispersants that may be employed in the practice of this invention are water soluble/dispersible polyesters. One particularly preferred polyester which is completely dispersible in water is commercially available from Eastman Chemical Products, Inc., Kingsport, Tennessee, under the product name "LB-100". This preferred water soluble/
dispersible polyester has a specific gravity (H2o=1) of about 1.08, and is available commercially as a 30% solution of the polyester in water.
Other water soluble/dispersible polymers that may be useful in the practice of the present invention include, but are not limited to other water soluble/dispersible polyamides and copolymers thereof, water soluble/dispersible polyesters and copolymers thereof, water soluble/dispersible vinyl polymers and copolymers thereof, water soluble/ dispersible alkylene oxide polymers and copolymers thereof and water soluble/dispersible polyolefins and copolymers thereof, as well as mixtures of the same. Other dispersants, like monomeric dispersants, may be suitable for use with the present invention.
One presently preferred technique for producing the additive dispersion of this invention uses as a starting material the aqueous dispersion formed according to the above-referenced Jones '645 patent. The aqueous dispersion may then be bead-milled and subjected to a spray drying operation so as to remove the, aqueous component. The resulting dispersant-coated pigment granules (hereinafter more simply referred to as the "dispersible pigment granules") in powder form are then mixed with a nonaqueous liquid polymeric carrier material.
The carrier material can be virtually any material that is liquid at or below melt-spinning temperatures of the polymeric host material. Preferably, the carrier material is a polyamide or a polyester. The carrier material must also be compatible with the thermoplastic polymeric host material. For example, when providing an additive concentrate system for incorporation into a nylon-6 polymeric host material, the presently preferred carrier is polycaprol.actone since it is liquid at room temperatures (20°C). However, carriers that may be liquefied at elevated temperatures (a. g., les:~ than about 200°C) are also useable i.n the practice of this invention. For example, when providing an additive concentrate system for incorporation into a nyl.an-6 polymeric host material, it is also possible to use copolyamides having a melting point of less than about 200°C. One pareicularly preferred class of such copolyamides is commercially available under the trade name Vestamelt copolyamides from I-~uls America Inc. of Piscataway, *
New Jersey, with Vestamelt 722 being particularly preferred.
One alterative technique to make the additive concentrate system according to this invention involves mixing the pigment, carrier and, if present, dispersant to form a nonaqueous paste in a one-step process thex-eby eliminating the need to prepare an aqueous dispersion which is subsequently spray dried. It is preferred that the dispersant, if present, and the carrier be premixed prior to addition of the pigment.
The mixture may then be milled So as to obtain a paste which can be introduced directly into a melt flow of the polymeric host material.
The additive cancentrate system of this invention may also be prepared by combining 'the pigment and the dispersant in a high-intensity mixer (e. g., a Henschel FM* series mixer available commercially from Henschel Mixers America, Inc. of Houston, Texas) until they are intir~tately mixed. Thereafter, the shear imparted by tree mixer .is reduced, and the required mass of carrier is added to yield the additive concentrate of this invention in paste form.
The dispersants that may be employed in 'the one-step technique, in addition to those described above, include polyethylene glycol p-octyl phenyl ether (Triton X-l0o), polyoxypropylene/ethylene block copolymers (Pluronic 25R2), alkoxylated diamines (Tetronic 15oR1), sodium lauryl sulfate and cationic dispersants (VariQuat*). The d~~spersant (i.e., the non-carrier material), if present., is present in the additive * trademarks concentrate system in an amount between about 5 to about 100 wt.~ based on the weight of the pigment, and more preferably, between about 4o to about loo wt.~.
However formed, the additive concentrate system is most preferably in the form of a flowable paste having a viscosity during introduction into the polymeric host material ranging between about 500 cP to about 500,000 cP, and most preferably between about 1,500 cP to about 100,000 cP, at a temperature between about 20°C to about 200°C. The dispersible additive may be maintained to within an acceptable viscosity range by application of heat (e. g., by keeping the dispersible additive in a suitable storage vessel which is jacketed with electrical resistance heaters and/or a heat transfer medium).
The additive concentrate system preferably contains pigment in an amount between about 5 to about 7 5 wt . % , more preferably between about 10 to about 65 wt.o based on the weight of the additive concentrate system. The additive concentrate system (the dispersible additive) itself is incorporated into the polymeric host material at levels between about 0.01 to about 15 wt.~; more preferably between about 0.05 and 10.0 wt.~ based on the total weight of the polymeric host material and additive concentrate system.
II. FILAMENT PRODUCTION
Accompanying FIGURE 1 schematically depicts a filament spinning operation l0 by which additive concentrate systems may selectively be mixed with a melt flow of polymeric host material discharged from a conventional screw extruder 12 and supplied to an inlet of the'spin pack assembly 14. More specifically, the polymeric host material is introduced into the upstream polymer filter section 14a of the spin pack assembly before being extruded through orifices in the spinneret 14b to form additive-containing filaments 16. Prior to reaching the spinneret 14b, the polymeric host material may be distributed by a plurality of thin distribution plates 14c 1.5 in accordance with the above-noted U.S. Patent No. 5,162,074 to William H. Hills, which may or may not have one or more static mixing plates, for example, as disclosed in U.S. Patent No.
5,137,369 to John A. Hodan.
Batches of the additive concentrate systems in paste form are respectively held within portable tanks 18a-18d. In i~he accompanying FIGURE 1, tanks 18a-18d az°e shown supported on taheeled carts 20a-20d, respectively, so as to permit each of the tanks 18a-18d to be replaced easily with stand-by tanks containing a fresh supply of the same or. different additive ~,oncentrate system. However, other means can be employed which Billow the tanks 18a-18d to be portable, :such as in-ground ar overhead conveyance systems, cranes and the like. Preferably, t:he additive concentrate system contained in each of the tanks i8a-18d is different - - hat is, tanks 18a-18d may each contain a different pigment oz: pigment mixture so that selective incorporation of each will result in the desired properties being achieved for the f-.ilaments 16.
Specifically, the tanks i8a-18c may each respec-tively contain dispersible colorant pigments corresponding to ~~elected colors such as aqua, magenta anc~ yellow, while tank 18d may have a specially formulated tint color (e. g., white, black or the like) to achieve the desired color hue, chroma and/or intensity. The differently colored additive concen-trates held within the tanks 18a-18d may thus be volumetri-cally dosed or mixed with the polymeric host material so as to achieve a virtually unlimited number of resulting colors of the melt-spun filaments 16. In a like manner, other filament properties may be "engineered" by select.~.ve incorporation of other non-colorant pigments.
The carts 20a-2od also support a primary pump 22a-22d and a metering pump 24a-24d, respectively. The pumps 22a-22d and 24a-24d are most preferably gear-type pumps which serve to force the additive concentrate system paste through respective supply lines 26a-26d to the spin pack assembly 14. More specifically, the primary pumps 22a-22d serve to maintain a relatively constant input pressure to the immediately downstream respective metering pump 24a-24d. The primary pumps 22a-22d are therefore relatively larger capacity as compared to their respective downstream metering pump 24a-24d.
The additive concentrate system paste within each of the tanks 18a-18d is maintained under constant agitation in order to prevent sedimentation of the pigment therein. Such agitation may be accomplished by a motor-driven mixer 26a-26d and/or via recycle lines 28a-28d (and/or lines 30a-3od). Of course, if the pigment is in solution with the carrier, then such agitation may not be needed.
The metering pumps 24a-24d are variable speed so as to achieve variable volumetric outputs within their respective capacity range stated previously. The speed of the metering pumps 24a-24d is most preferably controlled by a logic programmable controller LPC. Specifically, for a given "recipe"
(for example, a desired color for the pigmented filaments 16) input into the controller LPC, appropriate outputs will be issued to one or more of the metering pumps 24a-24d to cause them to operate at a speed to achieve a desired volumetric output for their particular dispersible additive. Thus, it will be recognized that for certain desired colors, some but not all of the metering pumps 24a-24d will be supplying paste from their respective tanks 18a-18d to the spin pack assembly 14 and/or may; be operated at different speeds to achieve different volumetric outputs. Suffice it to say, that by selectively controlling the operation of the metering pumps 24a-24d and, when operated, their respective speed (and hence their respective volumetric outputs), selective volumetric paste doses can be continuously supplied to the spin pack assembly 14 where the respective additive concentrate systems will be homogeneously mixed with the melt flow of polymeric host material being fed by the extruder 12 via line 32.
The respective speed of one or more of the metering pumps 24a-24d may also be varied continually to thereby 1~
respectively vary the volumetric dose of one or more of the colorant systems aver time. Such speed (dose) variance will thereby cause more or less additive concentrate system being incorporated into the filament per unit time where results in a filament having varying amounts of the additive per unit length. In the context of color additives, such speed variance may be employed so as to form filaments having a randomly striated or marbled color appearance.
The additive concentrate pastes from lines 26a-26d are most preferably introduced directly into the spin pack assembly 14 at a location corresponding to the distribution/
mixing section 14c -- that is, at a location downstream of the polymer filter 14a, but upstream of the spinneret 14b. In this manner, a relatively quick additive change between successive batches of filaments 16 is possible (i.e., to allow for changes in additive recipe to be realized from one filament batch to another). In addition, such an inlet location for the additive concentrates also allows for a wide range of processing flexibility to be achieved. For example, the additive pastes from tanks 18a, 18b, 18c and/or 18d may be mixed with the entirety of polymeric host material supplied via line 32 so that all of the filaments 16 have the same color.
Alternatively, the distribution/mixing section 14c of the spin pack assembly 14 may be so provided to split the flow of polymeric host material with one or more of the additive concentrate pates being mixed with one or more of such split flows to achieve, for example, multiple differently colored filament groups which may remain segregated to form single color yarns or may be combined to form multicolor yarns, such as in a heather yarn. In addition, several additives may be mixed with the host polymer so that, for example, single color yarns having multiple additive concentrations therein may be produced from the same spinning equipment. Similarly, one or more additive concentrate pastes may be mixed with split flows of polymeric host material within the distribution/mixing section 14c of the spin pack assembly 14 to achieve 1g multifilamentary yarns having differently colored filaments (e. g., as may be desired to produce yarns having a heathered appearance).
Although accompanying FIGURE 1 (and the description above) shows the additive concentrate system pastes being preferably introduced into the melt flow of polymeric host material directly into the spin pack assembly 14 at a location between the polymer filter section 14a and the spinneret 14b, it will be understood that the pastes may be incorporated into the melt flow of polymeric host material at any location upstream of the spinneret 14b. Thus, for example, the additive system pastes may be incorporated into the melt flow of polymeric host material by feeding through an injection port associated with the extruder 12 and/or through a port in line 32. Thus, for example, the additive system pastes may be introduced to the polymeric host material at or downstream of the extruder throat, but upstream of the spinneret 14b.
Different batches of colored filaments 16 may thus be produced continuously by simply changing the recipe in the controller LPC and allowing a sufficient time interval to elapse to ensure that any residual amounts of the additive concentrate system pastes associated with the prior recipe have been purged from the spin pack assembly 14. While some off-specification filament will ensue during the change-over to the new recipe, its economic impact is small by comparison to complete shutdown of the spinning operation. Furthermore, since relatively small amounts of the additive concentrate system pastes will residually be present in the spin pack assembly 14 at the time of recipe change-over, only a relatively short time interval is'needed to purge the spin pack assembly of the prior additive recipe and begin producing filaments pigmented with the new recipe.
III. Examples The following nonlimiting examples will provide a further understanding of this invention.
In this regard, carpet samples formed of filaments colored in accordance with the present invention and filaments colored in accordance with conventional extruder melt-blending techniques were tested according to the following procedures and, where applicable, a subjective rating scale of between 1 to 5 was utilized (5 being the best rating):
Yarn Degradation: Data representative of yarn strength/
elongation before and after loo, 200 and 300 hours ultraviolet radiation exposure according to AATCC Test Method 16-1993, Option E.
Colorfastness: Yarn color/visual data after 100, 20o and 300 hours ultraviolet radiation exposure according to AATCC
Test Method 16-1993, Option E.
Taber Abrasion Test: ASTM D3884-92.
Crocking: AATCC Test Method 8-1989.
Exposure to 50% Bleach: Carpet samples were cut into two 4.5" x 9" squares. 25 ml of a bleach solution containing about 2.6~ sodium hypochlorite (50~ Clorox~ brand bleach and water) was poured into the center of one sample to form a test region approximately ~" in diameter. The sample was allowed to air dry for 24 hours after which it was rinsed with a hot detergent/water solution containing 12 parts water and 1 part detergent. The rinsed sample was air dried for 24 hours after which it was visually rated on a scale of 1 to 5 against the untreated sample using AATCC Gray Scale in a Macbeth light booth (daylight setting).
Visual Grades After E~oosure to Ozone: AATCC Test Method 129-1990.

Visual Grades After Exposure to N02: AATCC Test Method 164-1992.
Dry Heat Exposure: Samples are heated in a laboratory oven (1600 Watts, Model No. OV-490, Blue M. Electric Co., Blue Island, Illinois) at 280°F and 320°F and removed after ten minutes. The samples are allowed to cool and visually rated on a scale of 1 to 5 using AATCC Gray Scale.
10 Tetrapod Wear: ASTM D5251-92.
Example 1 Dispersant-coated pigment particles were prepared using the components noted in Table A below. The components were blended using a high shear dissolver type mixer. A water soluble polyamide dispersant polymer (C-68 manufactured by BASF
Corporation in accordance with U.S. Patent No. 3,846,507 except that poly(E-caprolactam) was used as a starting material 20 instead of e-caprolactam) was first dissolved in water to prepare a 25 percent stock solution. Pigment dispersions were then bead-milled with 2 mm glass beads for three passes through the mill and were thereafter spray-dried. The dispersions were spray-dried using a Niro FSD-Pilot unit, which had a 1.5 meter diameter, 0.8 meters cylinder height, 40° cone, and a fluidized bed collector ~at the bottom of the chamber. Dispersions were fed into the dryer with a two-fluid, externally-mixed nozzle.
The spray-dryer was run with 253-263°C inlet and 67-1o3°C
outlet temperatures. The spray-dried powder tended to be dusty, and thus a fluidized bed collector was used to increase agglomerate size and thereby reduce the dust.

TABLE A
% Pigment in ~ Dispersant Aqueous in Aqueous P~"~!ment Dispersion Dispersion Inorganic 32.5 13.0 Yellow Organic Blue 20.0 15.0 Organic Red 20.0 15.0 Inorganic Tan 30.0 12.0 Organic Green 25.0 12.5 Organic Black 20.0 15.0 White/Stabili 32.5 13.0 zer Exam In a 2 Example 1 was repeated except that a water-dispersible polyester (LB-100 from Eastman Chemical Products, Inc.) was used as the dispersant polymer in the amounts noted in Table B below. Unlike Example 1 above, all dispersions according to this Example 2 contained 5.0~ of a polyoxy-propylene-polyoxyethylene block copolymer surfactant (Pluronic~
2582 surfactant from BASF Corporation). Spray-dried dispersions using LB-l00 as the dispersant were not dusty, and were prepared using the Niro spray-dryer which was not equipped with a fluidized bed collector. The Niro spray dryer was run with 220°C inlet and 80-95°C outlet temperatures. These dispersions were fed into a rotary wheel type atomizer running at 18,500 rpm.

_-_ ..,____~ ____'i~~~t~ ri ._ ~_.. ~spers~nt i aqueous in Aaueo_us Pig~me..~ Di sp~~~on ~~.sp~rs'a.on Organic Blue 27.5 20.6 Organic Red 27.5 ~ 20.6 Inorganic Tan 32.5 13.0 Organic Green 32.5 24.7 Organic Black 25.0 18,7 White 40.0 16.0 White/Stabili ; 40.0 16.0 zer Example 3 The additive concentrate pastes in Table C below were prepared by first melting at 150°C 50-600 of the required copolyamide carrier polymer (Vestamelt*722 from Hiils America Lnc.). The spray-dried powders obtained according to Example 1 above were then bag-blended i.n desired ratios to achieve desired final colors and stirred into the molten carrier polymer. The balance of the carrier polymer needed was then added and stirred into the concentrate blend formulation. The ;pray-dried powders tended to form large agglomerates which did not disperse without extended agitation, Thus, the blends were ~~tirred overnight (approximately 10 to 12 hours} prior to yarn Extrusion.
The white/stabilizer pigments used in the blended pigment ratios for all final colors, except Gray and Light Gray, were not the spray dried coated pigments obtained according to Example 1. Instead, the white/stabili.zer pigments * trademark were compounded with Vest:amelt:*722 polymer using a vented twin screw compounding extruder to obtain chip concentrates having 25 wt.o of white pigment and 2.5 wt.~ stabilizer. The chip concentrates of such white/stabilizer pigments were then blended in desired ratios with certain of the spray-dried pigments obtained in Example 1 to achieve the final colors noted below in Table C.
T~,ta~,. % Pigment Final dolor in Past, Light Gray 13.9 Gray 9.3 Black 20.4 Light Green 20.0 Purple 25.3 Blue 19.0 Light Tan 19.8 Mauve 18.7 Green 19.0 Brown I 19.7 The additive concentrate pastes in Table D below were prepared following the procedures of Example 3 above, except that the spray-dried powders obtained from Example 2 were used, and the carrier was polycaprolactone. Unlike Example 3, no compounded chips of white/stabili.zer pigments were used.
* trademark TABLE D
Total % Pigment Final Color in Paste Light Gray 37.0 Gray 37.8 Black 34.0 Light Green 39.0 Purple 35.5 Blue 34.8 Light Tan 35.0 Mauve 30.5 Green 34.9 Brown 37.7 -Example 5 A Barmag 6E extruder was used for filament yarn extrusion with the additive concentrate pastes in Table C being fed downstream of the extruder at around 150°C in desired ratios to achieve the filament color noted below in Table E.
The resulting melt-spun filament yarns were 6-hole pentagonal cross-section, 715 +/- 15 denier, and 14 filaments/ end. Eight ends of these undrawn yarns were combined during draw texturing to prepare 2250/112 denier yarns which were then two-ply cable-twisted to make 4500/224 denier carpet yarns. The carpet yarns were then tufted into 1/10 gauge, 26 ounces/square yard, 3/16"
pile height level loop carpets.
The carpets were then tested to determine various physical properties using the testing methods and techniques described previously. The results of such testing are tabulated below in Tables 1-4 and are presented in comparison to carpets formed of "control" filaments of matching color. The "control"
filaments were made using conventional compounded pigment chips which were melt-blended with the polymeric host chip in an extruder, with the melt-blend then being fed to the spinneret.
Table E
Additive % Additive 10 Conce ntrate Paste concentrate Final Compo nents Other Paste in Color Than Stabilizer Fil t Light black, white, amen 1.4 Gray green, blue Gray black, white, 2.6 blue, red Black black, white 3.8 Light black, white, 1.4 Green green, tan Purple black, white, 2.6 blue, red 20 Blue black, white, 2.8 blue, red Light black, green, tan 1.7 Tan ' Mauve black, blue, red 2.8 Green black, green, blue 4.2 Brown black, white, red, 6.5 tan o m ~ m m c~ m ~ m m ~ In a~ -~ u~ ~ .~ -~ -~ ~ ~ -~
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Example 5 was repeated except that the additive concentrate pastes of Table D were fed at the extruder throat at ambient temperature (about 2o°C). The paste components and the amount of paste in the filaments are noted below in Table F. The resulting filaments were formed into carpets and tested similar to Example 5. The results appear in Tables 5-8 below.
10 Table F
Additive % Additive Conce ntrate Paste Concentrate Final Compo nents Other Paste in Color khan Stabilizer Filament Light black, white, 0.6 Gray green, blue Gray black, white, 0.7 blue, red Black black, white 2.2 20 Light black, white, 0.8 Green green, tan Purple black, white, 2.0 blue, red Blue black, white, 1.6 blue, red Light black, green, tan 1.0 Tan Mauve black, blue, red 1.9 Green black, green, blue 2.2 Brown black, white, red, 3.6 tan x m p v~ ~r~ uyn m a~ ~ c~ c~ m a~ a~ ~ ~ a~ ~ ~ -~ a~ ~ ~

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Test Samples made with LB-100 Dr Heat Ex osure500 K
in Tetra od 280 F 320 S tair End F

B

GREEN CTRL B 5 4-5 ~-3 3-4 The data in Tables 1-8 above demonstrate that the performance properties of carpet yarns made from pigmented filaments of this invention are comparable to carpet yarns which are colored according to the conventional practice of melt-blending pigmented chips with base polymer chips. It is surprising that the incorporation of the a.ow molecular-weight polymer as the carrier in the dispersible additive did not affect either the breaking strength or elongation of the pigmented filaments of this invention when compared to conventional melt-colored filaments.

A tan additive concentrate paste was formed by direct blending of 40 wt.~ tan pigment particles, 8 wt.o of polyethylene glycol p-octyl phenyl ether (Triton X-loo) dispersant, and 52 wt.~ polycaprolactone. The resulting additive concentrate paste was preheated to approximately 14o°C
and exhibited a viscosity of. between 2000 to 4000 cP. The paste was pumped directly into a spin pack assembly at a location downstream of t:he polymer filter but upstream of the spinneret orifices (58 hole asymmetrical triiobal). The additive concentrate paste was mixed with the nylon-6 polymeric most material within the spin pack assembly at a rate of between about 6.0 g/min (to obtain about o.8-1.1 wt.°s pigment in the resulting melt-spun filaments) to about 7.3 g/min (to obtain about 1.1-1.5 wt.~ pigment in the resulting melt-spun filaments). The resulting melt-spun filaments had a uniformly colored appearance along the lengthwise extent as viewed with an unaided eye. Microscopic views of filament cross-sections z:evealed that substantially homogenous to somewhat striated mixing had occurred in dependence upon the injectian rate of the additive paste.
* trademark

Claims (18)

WHAT IS CLAIMED IS:

1. An additive-containing thermoplastic polymer composition comprising:
(a) a thermoplastic melt-spinable polymeric host material, and (b) an additive system dispersed throughout said thermoplastic melt-spinable polymeric host material, wherein said additive system comprising:
(1) a dispersant polymer, (2) pigment particles coated by said dispersant polymer so as to form a dispersant-coated pigments, and (3) a liquid nonaqueous polymeric carrier in which said dispersant-coated pigments are dispersed.

2. The composition as in claim 1, wherein said thermoplastic melt-spinable polymeric host material is selected from the group consisting of polymers, copolymers and mixtures of polyamides, polyesters, polyolefins and polyurethanes.

3. The composition as claimed in claim 1 or 2, wherein the thermoplastic melt-spinable polymeric host material is nylon-6.

4. The composition of any one of claims 1 to 3, wherein the dispersant polymer is selected from the group consisting of water-soluble polyamides, polyesters, vinyl polymers, alkylene oxide polymers and polyolefins, and copolymers and mixtures thereof.

5. The composition as in claim 4, wherein the dispersant is selected from the group consisting of polyethylene glycol p-octyl phenyl ether, polyoxypropylene/
ethylene block copolymers, alkoxylated diamines sodium lauryl sulfate and cationic dispersants.

6. The composition of any once of claims 1 to 5, wherein the pigments are colorants, stabilizers, delusterants, flame retardants, fillers, antimicrobial agents, antistatic agents, optical brighteners, extenders, or processing aids.

7. The composition of any one of claims 1 to 6, wherein the pigments are colorant particles having a mean particle size of less than 10 µm.

8. The composition of claim 7, wherein the pigments have a mean particle size of about 1 µm or less.

9. The composition of any one of claims 1 to 8, wherein the pigments are present in an amount between about to about 75 % by weight of said additive system.

10. The composition of any one of claims 1 to 9, wherein the pigments are spray-dried pigments.

11. The composition as claimed in any one of claims 1 to 10, wherein the polymeric carrier is a polyamide or polyester.

12. A method of making a dispersible additive system containing polymer compositions comprising the steps of:

(i) forming a dispersible additive system by;
(1) coating pigment particles with a dispersant so as to form a dispersant-coated pigment particles;
(2) spray drying said dispersant-coated pigment particle so as to form as spray-dried, dispersant coated pigment particles; and thereafter, (3) introducing a spray-dried, dispersant-coated pigment particles into a polymeric carrier; and (ii) dispersing the additive system into a thermoplastic melt-spinable polymeric host material to form an additive-containing thermoplastic composition.

13. The method of claim 12, wherein prior to step (2) there are practiced the steps of:
(a) forming an aqueous dispersion comprised of a pigment particles and a dispersant; and then (b) spray-drying the aqueous dispersion so as to obtain the dispersant-coated pigment particles.

14. The method of claim 12 or 13, comprising mixing the spray-dried dispersant-coated pigment particles with a polymeric carrier prior to step (ii).

15. The method of claim 14, wherein the spray dried dispersant-coated pigment has an average particle size of about 5 µm or greater prior to being blended with the thermoplastic melt-spinable polymeric host material according to step (ii), and wherein the dispersant-coated pigment has an average particle size of about 1 µm or less after dispersion into the polymeric host material according to step (ii).

16. The method as claimed in any one of claims 12 to 15, wherein the pigments are colorants, stabilizers, delusterants, flame retardants, fillers, antimicrobial agents, antistatic agents, optical brighteneres, extenders, or processing aids.

17. The method as claimed in any one of claims 12 to 16, wherein the polymeric carrier is a polyamide or polyester.

18. The method of claim 17, wherein the polymeric carrier is polycaprolactone.