US2875077A - Composition for and method of pigmenting viscose - Google Patents

Description

Feb. 24, 1959 K. M. MPLELLAN 2,875,977

COMPOSITION FOR AND METHOD OF PIGMENTING VISCOSE Filed April 2 1954 INVENQTOR KENNETH M. M LELLAN Viscose SUPPLY ATTORNE into colored yarn and tion, has been delivered from. a spinning machine.

United States Patent COMPOSITIONFOR AND METHOD OF .PIGMENTING VISCOSE Kenneth M. McLellan, Cleveland, Ohio, .assignor toIndustnal Rayon Corporation, Cleveland, Ohio, a corporation of Delaware Application April 2, 1954, Serial No. 420,678 4 Claims. (GLIDE- 165) This invention relates to Vi$coseadapted for extrusion ,the like. In particular, this invent on relates to pigment colored viscose spinning solut o jMo par cula y, thi inv n n r s to a unproved composition for. pigmenting viscose and to ,a method of pigmenting ripened viscosewith the improved composition for extrusion intocolored yarn and the like.

, Colored viscose yarns and the like maybe prepared with improved fastness tolight and to washing, and with other desirable. characteristics by incorporating the coloring matter in the spinningsolution prior to extrusion. Viscose so produced, and also yarns from other fiber forming materials, are known as being spun-dyed or solution-dyed yarns. In the production of spundyed colored yarn and the like from viscose ;it;has been found advantageous to continuously admin andblend coloring matter into the ripened viscose prior to extrusion and after the ripened viscose, ina spinnable condistorage or spin tanks to In this way, the necessity andinconvenience of color blending the ripened viscose .spinning solution in batches prior to delivery to the spinning machine for extrusion may be eliminated. Thus, substantial economies may be trealized -in- -maintenance and cleaning of=equipment, and also-in possible losses due to miscolored viscose wheneveriit may bedesired to alter or change the color of yarn being spun. However, in order that consistentlysimiiar colored yarn products may be. produced from day to day when :viscose is being continuously blended with coloring matter, it is important that constant unit proportions of anyparticular coloring matter be continuously and; consistently introduced and blended into unit volumes of the viscose spinning solution during unittperiods ofiextrusion. This is especially important when the viscose being. colored is being supplied for continuous extrusion through a plurality of spinning positions, and position'to-position as .well, as day-to-day variations ,injthe colored yarn product are to be avoided.

, Among thevarious coloring-matter which maybe employed for coloring viscose;spin ning solutions, pigments are known to be especially desirable. It is advantageous to employ coloring pigmentsin the ,form of aqueous pigment dispersions in order to circumvent the difliculty with which dry pigments of generallyfine particle size may be thoroughly blended directly into .viscose, in order to ,attain an intimate, uniform mixture having suitable homogeneity. Generally, aqueouspigment dispersions, sometimesreferred :to as pigment pastes, are thin, watery fluids of relativelylow viscosity and may havecvariousasolids contents. However, when attempts are made .withconventional metering devices, such as gearpumps, to continuously and directlyinject a pigment .paste for blending into a ripened viscose spinning solution which is flowing underpressure, difficulties are encountered in admixing constant pigment paste intotheviscose.

proportions of the fluid .stantially constant rate with "2 The simplest and mostgenerally employed metering devices for delivering constant volumes of viscous liquids over unitperiods of time are gear pumps. Gear pumps, forexample, are commonly preferred to extrude viscose and other;relativelyyiscous. spinning solutions for spinning since they are adapted to deliver liquids at a subpulsations in the flow of only relatively minor magnitude. However, due to the slight clearances between the rotors and the casing in a gear pump, they are not well adapted ,for metering relatively low viscosity or thin fluids againstsubstantial back pressures since considerable slippage of a thinner fluid may occur through the clearance between the rotors and the casing. This is especially so when there is a substantial pressure diiferential across thepump from its inlet or feed side to its ,outlet or delivery side. It has been .found troublesome, therefore,,to, employ gear pumps for ing underpressure, especially-when there is an appreciable fluctuating, or even static, variation between the feed pressure of the pigmentpaste at the pump inlet and the delivery pressure at the pump outlet. Such variations frequently occur over a range of as much as 40 pounds per square inch (p. s. i.), or greater, when pigmentpaste is injected .into a, viscose feed line, due to the manner in which viscose is conventionally handled. Obviously, the injection pressure of the pigment paste must meet orexceed the pressure under which the viscose is being handled. When gear pumps are used for this purpose, difficulty in keeping adesired volumetric ratio of pigment paste within tolerant consistent limits in a viscose spinning solution may be experienced dueto the heretofore mentioned deficiencies of gear pumps in such situations. Variations of more than about 5% in the pigment content of viscose are knownto be visually discernible in co or vampr c s p od se v fro A a 0 sequence, variations grcater than about this. amount of the pigment content. of viscose result in objectionable spinning position-to-position and day-to-day shade differences in the colored yarnproduct.

Although it is known to" pro-blend and disperse pig- 'ments in viscose for subsequent ,admixtureand blending with viscose spinning solutions,, such a practice is not alwayssatisfactory in that great care must be exerted to avoid the settingeup oithe viscose used' for dispersing the pigment due to prolonged standing or exposure to elevated temperatures or both. When this occurs undesirable-consequences such as a waste andpossible equip.- me or P o sin a toppasesm ye expe n d- F r this reasom no more of the pre -blended pigmentgdispersed in. viscose can be prepared in advance than an amount which maybe used withina reasonablyshort t m e tw e th p sme dt pe siqn a p using relatively unripeued or green viscose which may take longer to set-up, Hence, larger quantities of pigment dispersed in viscose which might' be sufficient for ex.- .tended periods of spinning, may; not conveniently be prepared in advance. In addition any excess or unused amounto f pigment dispersed inv iscose which may occur may not readily be stored for later use-due to the tendency of viscose to set-upupon"standing.

The present invention providesj-for an improved pigment mixture whichwtnay readily beprecisely and continuously introduced with. ,a; constant delivery device, such as :a gear pump, intoripened viscose under pressure, priorto extrusion, to producecolored yarns and the like. The improved pigment mixture ofthe present invention maybe prepared and stored-forconsiderable periods extending over several months in advance of requirements without harmful consequences. Excess prepared amounts sure'to a plurality of spinning positions.

may likewise be saved until their later use is occasioned.

vides for an improved method of continuously pigmenting ripened viscose spinning solutions flowing under pres- The method minimizes spinning position-to-position shade difierences in the colored yarn product and'colored yarn having substantially consistent color characteristics may be" spun over substantial periods or time from a plurality of spinning positions.

The composition for pigmenting viscose in accordance with the present invention comprises a yarn coloring pigment homogeneously dispersed in a stable, viscous liquid, miscible and compatible with viscose, which advantageously may be a glucose containing syrup, forexample,

a syrup resulting from the hydrolysis of starch, such as corn syrup. The pigment, in a finely divided state, is initially prepared in an aqueous dispersion or pigment paste. The pigment paste is then homogeneously mixed with suflicient'amounts of a glucose containing syrup to attain a stable, homogeneous, non-setting mixture having a constant consistency and which is adapted to be metered from a constant delivery device, such as a gear pump,

with not more than about volumetric variation in delivery over a unit period'of time when pumping against delivery pressures at thepump outlet varying over a range of at least about 40 p. s. i. from the pressures at the pump feed or inlet. Viscose flowing under pressure may be continuously and consistently pigmented in accordance with Y the present invention by injecting from a constant delivery gear pump suflicient coloring amounts of the pigment paste/ syrup composition of the present invention into the viscose and subsequently physically blending the viscose with the paste/ syrup composition. Viscose spinning solutions. thus pigmented may subsequently be extruded through a plurality of spinning positions over extended periods of time into colored yarn products having minimized day-to-day and spinning position-to-position shade differences.

Other additional objects and advantages of the present invention will be apparent in the following description and the drawing which schematically represents the method of the present invention for blending a viscose spinning solution with the improved pigmenting composition for extrusion into colored yarn and the like.

With reference to the drawing, a finely ground coloring pigment, prepared in aqueous dispersion, may be stored in a tank 1 as pigment paste. The glucose containing syrup, which advantageously may be a corn syrup of at least about 38 B., may be stored in a similar tank ,5. To prepare the pigment paste/syrup composition, a measured amount of pigment paste is delivered by a pump 4 through a conduit 2, valve 3 and conduit 9 into a mixing tank 10. A quantity of syrup is likewise withdrawn from the tank 5 through a conduit ,6 and valve 7 by a pump 8 and is transmitted through the conduit 9 to the mixing tank. The quantity of syrup is determined by the amount and character of pigment paste being used and the nature of the syrup being employed in order to obtain a paste/syrup composition having the desired characteristicsand consistency. For example, when a corn syrup having a concentration of at least about 38 B., is employed, especially when the concentration is about 42 B., a satisfactory paste/syrup composition can usually be prepared by mixing at least about 2% parts by volume of the syrup with each part by volume of the pigment paste. In the mixing tank 10 the pigment paste and syrup are homogeneously mixed by a mixer 11 which may be of any conventional type suited for the purpose. The resulting stable, homogeneous paste-syrup composition, containing uniformly dispersed pigment, is passed through a conduit 12 by a pump 14 into a storage tank 16 where it is stored at a room temperature between about 60 and about 80 F. ready for use. A-valve 13 may be positioned in the conduit 12'and a filter 15 may be employed to filter the 'In addition, the present invention advantageously propaste/syrup mixture passing through the conduit 12 be fore it is collected in the storage tank 16. If desired, filtration may be else where performed, as for example, upon withdrawal from the storage tank, or it may not be nec essary.

As mentioned, the paste/syrup composition is so proportioned that it may be delivered at a room temperature from a constant delivery gear pump, adapted for metering viscous liquids, with not more than about 5% variation in volumetric delivery with pressures at the pump outlet varying over a range of at least about 40 p. s. i. from those at the pump inlet. Such a range, for example, would be experienced when delivering a paste/ syrup composition under delivery pressures, or back pressures, at the pump outlet varying between about 1 and about 41 p. s. i. after the composition has been fed to the pump inlet under a pressure of about 1 p. s. i. The paste/syrup composition maintained at a room temperature and without requiring agitation to keep the pigment dispersed, may be fed by gravity from the storage tank 16 through a conduit 17 and valve 18 to a constant delivery gear pump 19. The gear pump 19, operating at a desired rate, consistently meters and a valve 21 by a metering gear pump 22 in desired proportionate volumes. If desired, the paste/ syrup composition may be injected into the viscose ahead'of the meter- .ing pump 22 in the conduit 20. The viscose containing the paste/syrup composition is blended in a blender 23 which may be of any suitable type, for example, the disc blender 23 which intimately combines the material be tween'closely spaced rotating discs. After blending, the pigmented viscose passes through a conduit 24 and a valve 25 to a spinning solution supply manifold .28 from which it is delivered through a plurality of conduits 29 to be extruded at a plurality of spinning positions (not shown).

,A portion of the pigmented viscose, after. blending, may be diverted from the conduit 24 through a conduit 26 and a valve 27 to be fed back and recirculated with fresh viscose from the supply source. The feed-back ratio of the blended viscose may advantageously be at about 50% although any desired portion of the blended viscose, or

none at all, may be fed back for recirculation. Viscose.

spinning solution may be continuously pigmented according to this method to produce consistently colored yarn and the like.

' The glucose containing syrups in which the pigment may be dispersed for blending with ripened viscose spinning solution in accordance with the present invention are those whichare sufficiently viscous to produce a pigment composition which may successfully be handled at about room temperature by a constant delivery gear pump as heretofore explained. Although syrups of varying consistency may be employed in suitable paste/syrup compositions, it is generally advantageous to use syrups having a concentration of at least about 38 Be., according to the method for determining the Baum equivalent of a liquid which is commonly employed in the syrup industry. When syrups of such a concentration are employed the ratio of syrup to pigment paste required is not generally high, and consequently the volumes of a paste/ syrup composition which must be injected into viscose for solution dyeing are not excessively large because of there being a relatively low pigment content in the pastel syrup composition. Generally, a ratio in the approximate neighborhood of about three parts by volume of syrup to about each part of volume of pigment paste is found to be desirable. The syrups are generally water-including complex carbohydrate materials which may contain other mono-saccharides, di-saccharides, higher saccharides or other carbohymolasses,

dr'ates in: addition to glucoseil Advantageously; a syrup product resulting from the partialor"incomplete-hydrolysisof starch is employed; Preferably, hydrolyzed it corn starch, known as corn syrup,is-employed althoughsyrups from other starches including ipot'ato starch and other grain and vegetable starches also may be suitable. These syrups are frequently generally known as-:glucosesyrups. Corn syrup, which contains 1 some-water: in: addition to glucose, maltose, dextrins and-other constituentsfis available as a crystal clear, uncr'ystalli zable liquidoverarange of relatively high-concentrations and viscosit-i'es which are particularly useful in accordance with the' presenr inven tion. In many cases, however;less'highly' refined corn syrups which are clear but not colorless rnay be satis factorily utilized. A corn syrup having a concentration of at least about 38- B., and 'a dextrose equiva'lent (D. 'E.) of between about 35 and about oomay, forexa'mple, be advantageously employed; As it is commonly u'nderstood, the dextrose equivalent"of a syrup' product resulting froma' partial orlincor nplet'e hydrolysis of a starch, for example corn syrup"from corn starch, is 'a measure-ofthe 1 degree of conversion ofi th'e starch -tosugar or; ex plained. otherwise, the extent of hydrolysis which the starch has undergone.- The dext'rose'equivalent is ordi narilydefined as the percentage' of reducing sugarsubstances in the syrup calculated as dextrose on the dry weight basis. It may beexpres'sed nur'nericallyas percentage D. E. or D. E. Ordinarily' starch syrups of lower conversion, having a D. E. beneath abous'35, while'probably not entirely useless; are not considered to'be as desirablefor the purposes :of this invention as are th'e 'more highly convertedsyrups: Lower I conversion 5 products which have a greater content ofincompletely"hydrolyzed" and higher molecular-weight starch constituents"generally appear to be not as suitable -as the higher conve'rs'ion syrups. Starchsyrups";having a D1 greater than about" 60 may be'con'sider'ed as'sugars and often have: a tendency to crystallizep This behavior renders them not always suitable for preparing paste/syrup?compositions due to the possibilityof plugging spinnerettes with crystallized particles. about 40 and about 45 and a concentration of at least about 41 B. and advantageously-at-about 42B. is especially desirable. having a D. E. of about 43 and a concentration of about 42 B. and which may contain various sugars' in 'an approximate amount of about 55% byweight, of which approximately 34% by' wei'gh't =isgl1icose; and Water in an amount not inexcess ofeapproximatelyw about 20% by weight. Other glucose containing. syrups may be also employed besides those which arestarch'hydrolysis products. For example; syrups having 21 based inv'ert sugar, which may result 'from the' hydrolysisof a di-saccharide such as, sucrose, may beernployed. Accordingly,honey, sugar-beet syrup, sugar-cane syrup and. like syrups may be useful 'with"the'presentinvention as are other glucose containing "syrups 'havingsufiiciently. high relative viscosityto thicken pigmentpaste sufficientlyin the heretofore explained-manner. Frequently, as is the case with corn syrup, an increasing specific gravity of the syrup above that of water -and-fa higher concentration as evidenced by its Baum -equivalent-'are characteristics which often reliably signify anincreasingglucosecontent along with an associated higher viscosity. As mentioned, syrups having a concentration of at least about 38 B. are usually more desirable. Generally, thicker syrups produce satisfactory compositions with lower syrup to paste ratios. However, thinner syrups may also be employed if it is suitable to operate with a relatively higher syrup to paste ratio. Syrups concentrated much above 43 B. may be diificult to handle at room temperatures due to their extremely viscous nature. However, they may be satisfactorily employed for paste/syrup compositions if suitable means are available for handling them. Oftentimes, for example, thicker syrups may be heated during A cornsyrup havinga D. E. between Particularly enseful is a "corn syrup' 6 handlingwhile being mixedwvith the pigment paste toproduce arcomposition manageable at a 1 room temperature inthe usual manner.

The employment of glucose containing syrups to thicken the pigment pastes in accordance with the present inventionis highly advantageous in many particulars. Many syrups, inaddition to corn syrup, are obtainable which are clear or colorless, if desired. Theyare also available free of included particles of a nature which could not be toleratedlin the manufacture of viscose yarn. They present no specialfiltration diificulties and, inaddition, the commonlyava'ilable glucose containing syrups are inert to viscoseand are'completely "miscible and compatible there with. Hence, they may be incorporated in a viscose spinning solution without fear ofharmful results. They are generally stable and inert upon standing to any changes in viscosity or composition because of intrinsic physical or chemical activity} Furthermore, the pigment compositions of the present invention composed with glucose containing. syrups are stable, homogeneous, and have little tendencyto settle on standing: Generally, they do not require agitation during u'se to maintain thepigment dispersion. Also, these compositions may more advantageously be handled by constant delivery gear pumps because they retain their consistency and exhbit a true viscosity without tending to assume thixotropicpecularities. Many thickeningagents may be deficient in these respects. For example,carboxymethylcellulose type materials, which are often used' for thickening purposes, are not completely satisfactory for thickening'pigment paste. They not only filterwith difiiculty and may contain particles of undissolved' fiber and the like which tend'to clog spinnerettes, but Ipigrnents dispersed in carboxymethylcellulosic cornpositions seem to possess a static viscosity and thin out to anundes'irable degree-uponbeing handled under pressure.

The pigments whichmay' be blended into viscose in accordance with the present invention are those commonly employed for spun-dyed or solution dyed viscose and other spinning solutions. They may be inorganic or organic in nature or may be organic salts and the like and also may'bemixtrires of various pigment, or other coloring, compounds. These pigments are used in a finely divided state in order to facilitate their being passed. through the small orifices of spinnerettes and'Tsimilar yarn extruding devices. Ordinarily, for example, about 99% of the particles'in these pigments may-havea size not in excess of aboutonemicron withthe balance of the particles being not in excess of about fivemicrons in size.- As mentioned, the pigment may be 'dispersed in water, or other fluids, to form pigment paste possibly with the aid of a dispersing agent. A pigment paste may contain, for example, about 20%by weight of dispersedsolids although varying solids contents may be effected Viscose spinningsolutions which may be pigmented in accordance with theapresent invention may be of any spinnable type desired. For'example, regular bright, dull delustered or -"partially delustered 'viscose mented for extrusion into colored yarn and the like. As mentioned, the viscose'tobe pigmented is advantageously at a desired level of ripeness and ready forspinning in order to be pigmented in accordance with the present inventioni In order to further illustrate the invention but without being limited thereto the following example is given:

Example About one part by volume of a pigment paste contain ing about 20% by weight of dry copper phthalocyanine (Monastral Blue) pigment in aqueous dispersion was homogeneously mixed with about three parts by volume of about 42 B. corn syrup having a D. E. of about 43 and containing about 55% by weight of various sugars, of which about 34% by weight were glucose, and about 20% by Weight of water to form a stable paste/syrup haying varying, contents of cellulose and other ingredients may be pig-' composition that would not separate on standing. The composition was filtered through cotton batting and muslin and was tested for deliverycharaeteristics using a gear type metering pump (such as a commercially available Zenith pump). When feeding the paste/syrup composition to the pump by gravity, it was found possible to deliver a substantially constant volume per unit time of the composition from they gear pump against delivery pressures at the pump outlet ranging between about 20 and about 60 p. s. i. The variation in volumetric delivery per unit time under such conditions was not more than about 1% by volume. The paste/syrup composition, needing no agitation to retain the pigment in homogeneous dispersion, was fed by gravity to a gear type metering pump for injection into a flow of ripened viscose spinning solution being transmitted in a feed line under about 80 p. s. i. average pressure. About one part by volume of the paste/ syrup composition was consistently and continuously metered into about every 250 parts by volume of fresh viscose from a viscose supply source. After injection, the paste/ syrup composition and the viscose were intimately blended using a disc type blender. About 50% by volume of the pigment blended viscose was fed back to the fresh viscose spinning solution being supplied and recirculated therewith. The unrecircul'ated pigment blended viscose was supplied to a plurality of spinning positions for extrusion. A plurality of colored yarns were thus spun over an extended period of time. The colored yarn thereby produced was commercially acceptable. Spinning position-to-position shade differences were negligible and there were no visually noticeable day-to-day differences between the shade of yarn from any position spun at the beginning of the period from that of yarn spun at its conclusion.

The amount of pigment employed for blending with the viscose spinning solution depends, of course, upon the particular pigment being employed and the depth to which it is desired to color the resulting yarn product. Likewise, the proportions necessary to compound the pigmenting compositions in accordance with the present invention vary with the type of pigment and pigment paste being employed, the particular glucose containing syrup being utilized and the ultimate characteristics which are desired in the colored yarn product. Generally, by experimentation, a particular pigment paste/syrup composition is empirically compounded in order to be adapted for satisfactory delivery from a metering device as heretofore explained. Due to the varying nature of the ingredients and the multiple influences which may come into play, it is often difficult to accurately predict suitable generalized formulations for paste/syrup pigm'enting compositions in accordance with the present invention.-

Since certain changes in practicing the invention may be made without departing from its spirit or scope, it is to be understood that all the foregoing description be in'' terpreted as merely illustrative and in no sense limiting of the invention, as particularly pointed out and defined in the appended claims.

What is claimed is:

1. Pigmenting composition for viscose spinning solu tion for subsequent extrusion into colored yarn and the like consisting essentially of not more than about one part by volume of an aqueous yarn coloring pigment dis- 8 persion containing not more than about 20% by weight of dispersed solids homogeneously mixed with at least about 2% partsby volume of an uncrystallizable liquid corn syrup havinga concentration of at least about 38 Baum and a dextrose equivalent between about 35 and about 60. l

2. Pigmenting composition for viscose spinning solutions for subsequent extrusion into colored yarn and the like consisting essentially of about one part by volume of an aqueous yarn coloring pigment dispersion containing no more than about 20% by weight of dispersed solids mixed with about 3 parts by volume of an uncrystallizable liquid corn syrup having a concentration of about 42 Baum and a dextrose equivalent between about 40 and about 45.

3. Method for pigmenting a ripened viscose spinning solution flowing under pressure for subsequent extrusion into colored yarn and the like comprising homogeneously mixing not more than about one part by volume of an aqueous yarn coloring pigment dispersion containing no more than about 20% by weight of dispersed solids with at least about 2% parts by volume of a corn syrup having a concentration of at least about 38 Baum and a dextrose equivalent between about 35 and about 60 to produce a mixture adapted to be delivered from a constant delivery gear pump with not more than about 5% volumetric variation per unit time when being pumped against delivery pressures at the pump outlet varying over a range of at least about 40 p. s. i. from pressures at the pump inlet; injecting the mixed pigment syrup with a constant delivery gear pump into said ripened viscose spinning solution flowing under pressure; then blending the mixed pigment syrup and viscose prior to extrusion. 4. Method for pigmenting a ripened viscose spinning solution flowing under pressure for subsequent extrusion into colored yarn and the like comprising homogeneously mixing about one part by volume of an aqueous yarn coloring pigment dispersion containing no more than about 20% by weight of dispersed solids with about 3 parts by volume of a corn syrup having a concentration of about 42 Baum and a dextrose equivalent between about 40 and about 45; injecting the mixed pigment syrup with a constant delivery gear pump into said ripened viscose spinning solution flowing under pressure; then blending the mixed pigment syrup and viscose prior to extrusion.

References Cited in the file of this patent UNITED STATES PATENTS

Claims (1)

1. PIGMENTING COMPOSITION FOR VISCOSE SPINNING SOLUTION FOR SUBSEQUENT EXTRUSION INTO COLORED YARN AND THE LIKE CONSISTING ESSENTIALLY OF NOT MORE THAN ABOUT ONE PART BY VOLUME OF AN AQUEOUS YARN COLORING PIGMENT DISPERSION CONTAINING NOT MORE THAN ABOUT 20% BY WEIGHT OF DISPOSED SOLIDS HOMOGENEOUSLY MIXED WITH AT LEAST ABOUT 2 1/2 PARTS BY VOLUME OF AN UNCRYSTALLIZABLE LIQUID CORN SYRUP HAVING A CONCENTRATION OF AT LEAST ABOUT 38* BAUME AND A DEXTROSE EQUIVALENT BETWEEN ABOUT 35 AND ABOUT 60.

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