US2457838A - Fluorescent cellulose acetate filaments - Google Patents

Description

Patented Jan. 4, 1949 OFFICE- 2,457,838 FLUORESCENT CELLULOSE ACETATE FILAMENTS Richard R. Sitzler ind George E. Dennison, Cumberland, Md., assignors to Celanese Corporation of America, a corporation of Delaware Serial No. 667,499

No Drawing. Application May 4, 1946,

1 2 Claims.

This invention relates to the preparation of colored fabrics, and relates more particularly to the production of fabrics woven of continuous or staple lengths of artificial filamentary materials such as, for example, regenerated cellulose. cellulose acetate, or other organic derivative of cellulose, dyed in shades which are extremely fast to light and which, in addition, exhibit a pronounced fluorescence under the excitation of ultra-violet light.

An object of this invention is the provision of colored fabrics made of or containing artificial filamentary materials which are dyed in shades fast to light and capable of fluorescence under the excitation of ultra-violet light in a color substantially identical with that of the fabric under visible light.

Another object of this invention is to provide colored fabrics of artificial filamentary materials containing fluorescent pigments and dyed in shades fast to light whereby the respective colorations produced will not interfere with each other, the fabric obtained being of the same color whether viewed by visible light or under ultraviolet light.

Other objects of this invention will appear from the following detailed description.

Artificial filaments or fibers which have been dyed with fluorescent dyestuffs so that they may glow under ultra-violet light have found some use in the arts. Thus, they may be employed in the manufacture of cloth for use in making uniforms and garments for show girls to produce spectacular stage effects. Also, they may be used in the manufacture of floor coverings in apartment buildings or in theatres, and the like, for indicating the presence of aisles, steps, etc. Usually, the fluorescent filaments or fibers are woven into the floor covering in a predetermined pattern. However, since the fluorescent dyestuffs may be entirely colorless when the ultra-violet source is withdrawn the pattern is no longer visible when illuminated by ordinary light. Furthermore, even when such portions of the floor covering which are also dyed with a dyestuif visible under ordinary illumination, as well aswith a fluorescent dyestuff, are exposed to ultra-violet light so as to bring out the desired fluorescence, the ultra-violet light has an undesirable eifect on the visible dyestuff, frequently causing fading, or even a complete change in shade on com 2 subjected to continued exposure to sunlight as during daylight hours when the sunlight reaches the fioor coverings through windows. 7

We have now found that artificial filamentary materials exhibiting the identical color under both daylight ,and the excitation of ultra-violet light may be obtained by incorporating a finelydivided fluorescent pigment in the spinning solution from which the artificial filaments are spun and then dyeing the filaments obtained in hank, bobbin or. fabric form with a dyestuff highly resistant to changes in shade on continued exposure to ultra-violet light. The fluorescent pigment and the dyestufi to be employed therewith must be such that together they yield a color which does not vary appreciably when viewed by visible light or under ultra-violet light. Thus, various fabric materials may be formed wherein a decorative or identifying colored pattern is present in a color which is substantially identical regardless of whether the dyed materials are viewed by daylight or are illuminated by invisible, ultra-violet light.

The colored fluorescent filaments prepared in accordance with the process of our invention may have a basis of any suitable filament-forming -material. The filamentsmay be formed by extruding a solution of the desired filament-forming material-containing the desired finely-divided fluorescent pigment through a spinning jet containing a plurality of orifices into a medium adapted to effect the formation or solidification of the filaments. 7 Thus, for example, thefilaments may have a basis of regenerated cellulose which may be made by the viscose, cuprammonium, nitro cellulose, or any other process adapted for the production of said regenerated cellulose filaments. They may also have a basis of a synthetic linear polyamide condensation product or other suitable polymeric material such as polyvinyl chloride, polymerized vinylidene chloride, or a co-bolymer of vinyl chloride and viny tinued exposure, which shade may be undesirable.

derivative of cellulose may be prepared by dismamas a 3 solving the organic derivative of cellulose in a suitable volatile solvent, such as acetone, and extruding such solution, after the desired amount of finely-divided fluorescent pigment has been added thereto, through an orifice or plurality of orifices into an evaporative atmosphere as in the dry spinning method or into a liquid coagulating medium as in the wet spinning method, which spinning methods are well known in the art.

Prior to incorporation in the spinning solution, the fluorescent pigment-is reduced to a very finely-divided form by a suitable treatment which may comprise grinding the pigment in a ball mill, colloid mill or the like, adapted to reduce the pigment to the desired finely-divided form.

Preferably, the particles are reduced in size to a diameter of from less than 0.1 up to about 5 microns. The amount of pigment added will vary depending upon the particular shade which is desired in thefilaments and the nature of the pigment employed. A satisfactory color of high intensity and brilliance under both daylight and ultra-violet light may beobtained by adding to the spinning solution an amount of fluorescent pigment of from about 0.01% to about 5 to by weight, based on the amount of the filamentforming material present in the spinning solution.

The finely-divided colored fluorescent pigment may be added at any point in the manufacture of the filaments prior to extrusion. Thus, for

example, a spinning solution may be prepared with the desired amount of fluorescent pigment incorporated therein and the pigmented spinning solution thus obtained then extruded through orifices to form filaments in the manner well known to the art. Most advantageously, however, the pigments may be added to the spinning dope at a point near the spinning jet or orifices through which it is extruded so that the system employed for spinning the filaments will not be contaminated with any particular color. This avoids extensive and time-consuming cleaning operations if it is desired'to spin filaments in various other colors. 4

Because of the extremely flne particle size of the fluorescent pigments, the filaments obtained possess substantially the same tenacity and elongation characteristics as filaments which do not contain a finely-divided pigment. Consequently, the pigmented filaments prepared in accordance with my invention may be employed satisfactorily y in any application where substantial tenacity and elongation characteristics are necessary.

As examples of fluorescent pigments which may be employed to impart the desired brilliant fluorescent color to the filaments, the following may be mentioned. For a yellow fluorescent color specially prepared mixtures of zinc sulfide and cadmium sulfide, or cadmium tungstate are satisfactory. For a red fluorescent color, specially prepared zinc sulfide, or mercuric oxide, potassium dichromate, magnesium dichromate,.barium chromate, thorium dichromate, rhodium thiocyanate, as well as Rhodamine BX tungstate lake and Barium red lakeC toner, are suitable. For a blue fluorescent color, we may employ pigments,v such as specially prepared zinc sulfide of a blue fluorescent color, Peacock blue lake or certain blue dyestufl's in substance such as Milling Blue BC;

Alizarine Blue SE. For a green fluorescent color, I have found that the addition of specially prepared zinc' sulfide of a green daylight color as well as a green fluorescent color is suitable, as well as other pigments such as brilliant Green tungstate or Auramine 00 tungstate lake or Malaobtain any other colors, the fluorescent pigments may be mixed as is well understood in the art.

The artificial filamentary materials containing the above finely-divided fluorescent pigments are then dyed with a suitable dyestufl resistant to the detrimental eflects of ultra-violet light. The filaments may be dyed in hankor in bobbin form or they may be woven in the desired fabric form and the fabric obtained then dyed in the piece. The dyestufl's preferably employed in dyeing pigmented cellulose acetate or other pigmented organic derivative of cellulose filaments comprise acid dyestuffs, such as those normally employed in the dyeing of wool, and those dyestuffs which are applied in dispersed form in the dyeing of cellulose acetate or other organic derivative of cellulose materials. Examples of said acid dyestufls are Brilliant Sulfanine Red B, Artol Blue GL, Artol Yellow SG, Xylene Brilliant Cyanine G and. Fast Red A, whileexamples of satisfactory dyestuffs applied in dispersed form are 1,4-dimethylaminoanthraquinone, the azo dyestuif obtained by coupling p-aminoiacetanilide with p-cresol, and the azo dyestufl. obtained by conpling p-nitro-analine and dihydroxyethyl-m-tolyarns having a basis of cellulose acetate, or other organic acid ester of cellulose, to a stretching operation whereby the filaments are stretched to 200, 300, 500 or even 1000, to 2000% of their original length. The yarns may be stretched to the desired degree when they are in a somewhat softened condition, which condition may be obtained by treating the fluorescent pigmented cellulose acetate yarns, or other organic ester of cellulose yarns, with organic solvents, latent sol-' vents, or swelling agents therefor, or by subjecting the yarns to the action of hot water or steam at elevated temperature 'or pressure. The stretching of the yarns may be effected during, continuously with, or after their formation and the stretched yarns may then be taken up in suitable package form. The stretching operation causes cellulose acetate yarns to acquire a relatively high tenacity and this increased tenacity may be enhanced by subjecting the stretched cellulose acetate or other organic acid ester of cellulose yarns to saponification with a suitable alkaline medium.

The saponifying agent employed may be inorganic, such as, for example, sodium hydroxide, potassium hydroxide, ammonium hydroxide or other organic basic agent, or may be an organic saponifying agent, such as, methyl amine, ethylene diamine, triethanolamine, or other organic base. The saponifying agents may be employed in varying concentrations in aqueous, alcoholic or aqueous/alcoholic solutions and saponification may be effected satisfactorily at temperatures of 20 to C. I The stretched cellulose acetate or' other organic acid ester of cellulose yarns containing a fluorescent pigment may be dyed after stretching with any of the dyestufls heretofore mentioned or the stretched yam may be dyed, after saponification, with suitable dyestuffs resistant to light and having an affinity for the regenerated cellulose material formed by saponification. The finelydivided fluorescent pigment contained therein does not afiect the tenacity of the stretched and saponifled yarns and they may be employed wherever such dyed, fluorescent yarns of high tenacity characteristics are desired.

In order further to illustrate our invention, but without being limited thereto, the following examples are given:

Example I Cellulose acetate filaments containing a finelydivided fluorescent pigment are prepared by adding 1 part'by weight of specially prepared zinc sulfide, fluorescent in a red color, to 400 parts by weight of a 25% solution of cellulose acetate in acetone and then extruding the mixture obtained through a spinning jet into an evaporative atmosphere where-the volatile solvent is removed and the desired pigmented filaments are formed. The yarn obtained is then dyed in hank form by padding the hank of yarn with an aqueous dyebath comprising 0.5 part by weight of p-nitrobenzene-azo-4-methyl-2-di-hydroxyethyl amino-benzene on the weight of the yarn dispersed in 30 parts by weight of water, on the weight of the yarn, with the aid of sulfonated ricinoleic acid. Dyeing is effected at a temperature of 180 F. After being rinsed and dried, the yarn obtained is dyed in a bright red color and is fluorescent under ultra-violet light in a bright red color substantially identical with that under daylight. The yarn may also be dyed by padding the hank with 0.5 part by weight of Fast Red A (Color Index No. 176) on the weight of the yarn dispersed in 30 parts by weight of a 25% aqueous solution of ethyl alcohol containing 2% of sodium thiocyanate at 68 F. The yarn isdyed a bright color red and is fluorescent under ultraviolet light in a bright red color substantially I identical with that under daylight.

Example If Pigmented cellulose acetate fllaments fluorescent in a yellow color are prepared by adding 1 part by weight of a mixture of specially prepared zinc sulfide and cadmium sulfide, fluorescent in a yellow color. to 400 parts by weight of a 25% solution of cellulose acetate in acetone and then'extruding the mixture obtained through a maintained at F. during dyeing. The hanks of yarn are rinsed and dried. The yarns are dyed a bright yellow shade and exhibit a bright yellow fluorescence under ultra-violet light. The yarns may also be dyed a yellow color substantially identical with the yellow fluorescent color under ultra-violet light employing a dyebath containing 0.5 part by weight of Artol Yellow SG on the weight of the yarn being dyed dissolved in 30 parts by weight of a 25% aqueous solution of ethyl alcohol containing 2% of sodium thiocyanate. The dyeing is carried out by padding with the dyebath at 68 C.

It is to be understood that the foregoing detailed description is given merely by way of illustration and that many variations may be made therein without departing from the spirit of our invention.

Having described our invention, what we desire to secure by Letters Patent is:

1( In a process for the production of colored, fluorescent cellulose acetate filamentary materials exhibiting substantially the same color under visible as well as ultra-violet illumination, the step of dyeing the cellulose acetate textile material having incorporated therein a finely divided pigment consisting of zinc sulfide fluorescent in a red color with a dyebath comprising p-nitro-benzene-azo-4-methyl-2-di hydroxyethyl aminobenzene, water and sulfonated ricinoleic acid.

2. Colored, fluorescent cellulose acetate filamentary materials exhibiting substantially the same color under visible as well as ultra-violet illumination having a finely divided pigment consisting of zinc sulfide fluorescent in a red color incorporated therein and colored with a fluorescent dyestufl' consisting of p-nitro-benzene-azo- 4-methyl-2-di-hydroxyethy1-amino-benzene.

RICHARD R. SITZLER, GEORGE E. DENNISON.

REFERENCES arm!) The following references are of record in the file of this patent:

UNITED STATES PATENTS Great Britain Oct. 31, 1929