US3575898A - Polyvinyl chloride-antimony oxide flame-retardant mixtures for cellulosic spinning dopes - Google Patents

Abstract

THE PRESENT INVENTION RELATES TO CELLULOSIC COMPOSITIONS WHICH ARE CAPABLE OF BEING FORMED INTO FLAME-RETARDANT STRUCTURES, SUCH AS FIBERS, FILAMENTS, FILMS AND THE LIKE. THESE FLAME-RETARDANT CELLULOSIC COMPOSITIONS ARE PREPARED BY ADDING A FLAME-RETARDING AMOUNT OF A MIXTURE COMPRISED OF A VINYL CHLORIDE POLYMER AND AN ANTIMONY OXIDE TO CELLULOSIC SPINNING SOLUTIONS OR DOPES FOLLOWED BY THE COAGULATION OF THESE SOLUTIONS OR DOPES TO PRODUCE FLAME-RETARDANT CELLULOSIC SHAPED ARTICLES, SUCH AS FILAMENTS, FIBERS, FILMS AND THE LIKE.

Description

United States Patent O POLYVINYL CHLORIDE-ANTIMONY OXIDE FLAME-RETARDANT MIXTURES FOR 'CEL- LULOSIC SPINNING DOPES Robert L. McClure, Elizabethton, Tenn., assignor to Beaunit Corporation, New York, N.Y. No Drawing. Filed June 20, 1968, Ser. No. 738,399 Int. Cl. D01f 3/04 US. Cl. 260-174 2 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to cellulosic compositions which are capable of being formed into flame-retardant structures, such as fibers, filaments, films and the like. These flame-retardant cellulosic compositions are prepared by adding a flame-retarding amount of a mixture comprised of a vinyl chloride polymer and an antimony oxide to cellulosic spinning solutions or dopes followed by the coagulation of these solutions or dopes to produce flame-retardant cellulosic shaped articles, such as filaments, fibers, films and the like.

BACKGROUND OF THE INVENTION (1) Field of the invention This invention relates to the preparation of cellulosic shaped articles, such as filaments, fibers, films and the like having improved flame-retardant properties.

(2) Description of the prior art Cellulosic compositions, particularly fiber-forming compositions, possess a number of characteristics which render them of substantial 'value for a variety of textile and other uses. However, in order to use these cellulosic compositions in many applications it is necessary that they be modified or treated to provide them with flameretarding properties or characteristics. Conventional procedures for imparting flame-retardant properties to shaped articles, such as fibers and filaments, of cellulose or cellulose derivatives involve impregnating or coating the cellulose containing films of filaments, fibers or fabrics formed therefrom with a suitable flame-retardant composition followed by drying or curing. Such flame-retardant treatments alter the physical properties of the treated materials such as the hand or feel of the treated material. These finishes are generally easily removed by laundering, dry cleaning or leaching in water and, therefore are ineffective after short periods of normal use. For these reasons, such treated fibers, filaments, and fabrics have found only limited commercial acceptance in the textile trade.

SUMMARY OF THE INVENTION The present invention provides cellulosic articles, such as films, fibers, filaments, or fabrics therefrom, having excellent flame-retarding properties and is accomplished by the incorporation of a flame-retarding amount of a mixture comprising a vinyl chloride polymer and an antimony oxide in conventional cellulosic spinning solutions followed by the formation of shaped articles, such as filaments, fibers, films and the like from these solutions.

The cellulosic spinning solutions of this invention generally comprise a conventional cellulosic spinning solution or dope, such as a cuprammonium cellulose spinning solution or dope, a viscose spinning solution or dope, or a cellulose ester spinning solution or dope, which contains a mixture comprising a vinyl chloride polymer and an antimony oxide in an amount sufiicient to impart fireretardant properties to the structure obtained by co- Patented Apr. 20, 1971 agulating such spinning solutions or dopes in conventional coagulating baths followed by leaching and drying.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The cellulosic spinning solutions or dopes of this invention are intended to include cuprammonium and viscose spinning solutions as well as cellulose ester spinning solutions. These spinning solutions will include solutions of cellulose or the reaction products of cellulose and ammonia-copper complexes in an aqueous solution of an ammonia-copper complex as, for example, cuprammonium spinning solutions or dopes; solutions of cellulose xanthate in "Water and aqueous alkalis such as aqueous sodium hydroxide solution as, for example, viscose syrups and dopes; organic acid or anhydride derivatives of cellulose such as cellulose acetate solutions, cellulose propionate solutions or other solutions of a product obtained by reacting cellulose with an organic acid or anhydride; and the like. The preparation of the cellulosic spinning solutions of this invention are conventional to those skilled in the art. The preparation of cuprammonium spinning solutions, viscose spinning solutions, and cellulose acetate spinning solutions are described generally in The Rayon Industry (1929), published by D. Van Nostrand Company, New York, N.Y., on pages 523-543, 436-522, and 559-580 respectively and in Man-Made Fibers by R. W. Moncrief, published by John Wiley & Sons, Inc., New York, N.Y. (1966), on pages 196-203, 138-195, and 204-233 respectively. The use of the cuprammonium spinning solutions and the preparation of flameretardant cuprammonium rayon articles are preferred for the purposes of this invention. Shaped articles prepared from viscose spinning solutions are normally discolored because of side reactions which take place between the antimony oxide and the sulfur or sulfides present in the conventional cellulose xanthate or viscose spinning solutions. In addition, the normal funnel type spinning using large hole spinnerets and used in the preparation of cuprammonium rayon articles appears best suited for use in carrying out the purposes of this invention.

The spinning solution used in the preferred cuprammonium process is obtained by dissolving cellulose in a cuprammonium solvent which is essentially an aqueous solution of copper and ammonia characterized by the cuprammonium ion. This aqueous solvent must contain specific quantities or concentrations of copper in cupric form and ammonia in order for the cellulose to remain dissolved therein. These amounts will normally run from about 2 to 4 percent of copper and from about 4 to 7 percent of ammonium. It is generally recognized that the cuprammonium ion of the solvent forms a complex with the cellulose to give a soluble copper-ammonia-cellulose compound. This cuprammonium cellulose solution can then be extruded or spun, e.g., as filaments or the like into an aqueous spin bath or coagulating bath. The aqueous coagulating bath, which may be neutral or basic, essentially functions as a diluent to lower the concentration of ammonia and copper to the point where the cellulose tends to harden or coagulate in the form extruded. The spin bath may also serve to remove some of the solvent from the precipitated filaments or the like.

Although it is possible to use water alone as the coagulating bath for the spun filaments, it has been a more common procedure to employ an alkaline coagulating bath, in order to obtain a good coagulation and better qualities in the finished product. After coagulation, there is believed to be formed a copper-alkali cellulose material which can be decomposed to fully regenerate the cellulose by subsequent treatment in an acid bath. In

some cases, it has been found advisable to treat the coagulated material from the alkaline bath with water alone in order to hydrolytically decompose the copper-alkalicellulose prior to treatment with acid. The acid treatment then serves to remove copper hydroxide when taken in conjunction with subsequent washing to remove salts and adhering acid. After washing, the cellulose article is dried and stored in any suitable manner.

With respect to the production of filaments, the cuprammonium spinning solution is ordinarily extruded into a funnel or bath through which the aqueous coagulating medium is circulated, and the cellulose of the coagulated filament is then regenerated by treatment in an acid bath, Washing and drying. A portion of the ammonia and copper is removed during coagulation, essentially by dilution of the spinning solution as noted above, and the ammonia and copper remaining with the cellulose after cagulation are separated during the acid treatment and subsequent washing.

The various spinning solutions or dopes used for the purposes of the present invention may contain varying amounts of cellulose or cellulose derivatives, depending upon the particular spinning solution used and the end use of the product desired, such as in spinning filaments, preparing stable fibers, casting films and coatings, and the like. Generally, they will contain from about 2 to 40 percent by weight of cellulose or cellulose derivative. The cuprammonium and viscose spinning solutions or dopes of this invention will normally contain about 2 to percent by weight of the cellulose or cellulose derivative and the cellulose ester spinning solutions of this invention will normally contain about to percent by weight of the cellulose or cellulose derivative.

The spinning solutions or dopes described above may contain conventional additives such as delustering agents, cationic and non-ionic surface active agents, dyes, pigments, stabilizers and the like, in addition to the specific additive mixtures of this invention.

The amount of flameretarding mixture used may vary. Broadly, it has been found that about 10 to 100 parts by weight of flame-retarding mixture may be used, based on 100 parts by weight of cellulose or cellulose derivative, in the spinning solution or dope to obtain a shaped article which has sufficient strenght to be useful as a filament, fiber, or fabrics therefrom. It is preferred that about 10 to parts by weight of the flame-retarding mixture be used, based on 100 parts by weight of cellulose or cellulose derivative in the spinning solution or dope. The resulting shaped article prepared from these spinning solutions should have essentially the same weight distribution as the spinning solution with the flameretarding mixture distributed uniformly throughout the cellulosic article. It has been found that at least percent of the flame-retarding mixture is retained in the article produced. The exact amount will depend upon the solubility of the mixture in the spinning solution.

The flame-retarding mixture of this invention may be composed of from about 20 to 90 percent by weight of a vinyl chloride polymer and from about 10 to percent by weight of an antimony oxide. Preferably, the flameretarding mixture in the shaped articles will contain from about 50 to 75 percent by weight of a vinyl chloride polymer and from about 25 to 50 percent by weight of an antimony oxide. This combination of a vinyl chloride polymer and an antimony oxide produces a synergistic effect in which the total flame retardance is greater than the sum of the individual components.

The vinyl chloride polymers which form an essential part of the flame-retardant mixture of this invention include homopolymers, such as poly(vinyl chloride) and poly (vinylidene chloride), and copolymers of vinyl chloride or vinylidene chloride with other polymerizable olefinically unsaturated compounds, such as vinyl acetate, methyl acrylate, methyl methacrylate, methyl chloroacrylate, acrylonitrile, and the like, wherein the vinyl chloride or vinylidene chloride is present in amounts of at least about 50 percent by weight. Preferably, the vinyl chloride polymers used are poly(vinyl chloride), poly (vinylidene chloride), or copolymers of vinyl chloride or vinylidene chloride in which the vinyl chloride or vinylidene chloride is present in amounts of at least about percent by weight.

The antimony oxides which form an essential part of the flame-retardant mixture of this invention include antimony trioxide, antimony tetraoxide, and antimony pentoxide. Preferably, antimony trioxide will be used for the purposes of this invention.

The regenerated cellulosic structures of this invention are prepared by shaping the cellulosic spinning solutions or dopes containing the flame-retarding mixtures of this invention to the desired form and then subjecting the shaped solution or dope to a coagulating bath whereby the cellulose or cellulose derivative is precipitated. The spinning solutions or dopes containing the vinyl chloride polymer-antimony oxide mixtures of this invention coagulate and harden in the coagulating medium. The resulting article may then be washed and dried. The cuprammonium articles may be decopperized with dilute sulfuric acid solutions and washed with water. The cellulosic structures obtained have the flame-retarding mixture of this invention uniformly dispersed therein and have ex cellent flame-retarding properties after repeated washings or repeated dry cleanings.

A variety of fire-retardant articles, such as filaments, fibers, films, coatings, and the like may be prepared from the spinning solutions of this invention in any conventional manner. Preferably, filaments and fibers are prepared from the spinning solutions by extruding the cellulosic spinning solution or dope through orifices in a spinneret into a coagulating medium, such as a bath, to regenerate the cellulose or cellulose derivative in filament form, after which the filaments may be collected on spools, or in centrifugal pots, or in any well known manner. The filaments are then processed in any normal manner. It has been found that it is preferable to use conventional funnel type spinning in preparing the filaments of this invention in order to avoid any possible clogging of spinneret orifices.

The filaments, staple fibers, and the like which may be prepared from the compositions of this invention may be processed into knit or woven fabrics by conventional operations, Filaments and the like may be sized and then woven or knitted into fabrics, while the staple fibers and the like are converted into threads or yarns which then may be sized and Woven or knitted into fabrics. These fabrics have outstanding flame-retarding properties and retain these properties after repeated washings or after being subjected to repeated commercial dry cleanings. The filaments, staple fibers, and the like of this invention may also be blended with other textile yarns or fibers and knitted or Woven by conventional methods into fabrics having good flame-retarding properties.

The following examples are presented as a further disclosure and illustration of the improved products of this invention and are not intended as a limitation thereof. All parts, proportions and percentages are by weight otherwise indicated.

The flame test method used in the examples is the A.A.T.C.C. (American Association of Textile Colorists and Chemists) Test Method #34-1966 entitled Fire Resistance of Textile Fabrics.

EXAMPLE 1 A typical preparation of a flame-retarding mixture of this invention: To a stirred solution of 280 grams of high viscosity carboxymethyl cellulose a dispersing acid) and 1300 grams of octylphenoxypolyethoxyethanol (a surface active agent) in 30 liters of water, there was added 168 lbs. of a 50 percent aqueous dispersion of a vinylidene chloride-vinyl chloride copolymer containing less than about percent of vinyl chloride and of about 70 percent chloride content, 56 lbs. of a 50 percent aqueous slurry of antimony trioxide of about 1.5 micron particle size and 12 liters of a 26 percent aqueous solution of ammonium hydroxide. This mixture was then diluted to a volume of about 280 liters by the addition of water to produce a stock solution of about 182 grams per liter of solids which constains about 136 grams per liter of the vinyl chloride polymer and about 45 grams per liter of antimony trioxide.

EXAMPLE 2 The flame-retarding mixture prepared in Example 1 is added to a conventional cuprammonium spinning solution composed of about 8 /2 percent of cellulose at a ratio to produce a spinning solution comprising about 5.66 percent of cellulose and about 2.83 percent of the flame-retarding mixture. This modified spinning solution was then cast into strong, white film containing about 66 /3 parts of cellulose, about 25 parts of the vinylidene chloride-vinyl chloride copolymer and 8 /3 parts of antimony trioxide. This film was subjected to the standard A.A.T.C.C. flame test and it was observed that the afterflame time was less than one second.

Film prepared in a similar manner as above and containing about 72.8 parts of cellulose and about 27.2 parts of the vinylidene chloridelvinyl chloride copolymer was subjected to the same flame test and burned completely.

Film prepared in a similar manner as above and containing about 88 parts of cellulose and about 12 parts of antimony trioxide was subjected to the same flame test and it was observed that the afterflame time was more than two seconds as called for by this test.

EXAMPLE 3 The flame-retarding mixture prepared in Example 1 is added to a conventional cuprammonium spinning solution composed of about 8 /2 percent of cellulose at a ratio to produce a spinning solution comprising about 5.66 percent of cellulose and about 2.83 percent of the flameretarding mixture. This modified spinning solution is then extruded into a conventional coagulation bath to produce strong, white filament containing about 66% percent of cellulose and about 33 /3 percent of the flame-retarding mixture. This filament had a hand or feel substantially identical to that of unmodified cuprammonium rayon yarn.

Woven fabric prepared from the filaments prepared above was subjected to the standard A.A.T.C.C. flame test and it was observed that the afterflame time was less than one second.

A woven fabric prepared from unmodified cuprammonium rayon yarn burned completely when subjected to the above test.

EXAMPLE 4 A cuprammonium spinning solution containing about 6 percent of cellulose and about 33 percent, based on the cellulose content of the solution, of a flame-retarding mixture of about 75 percent of the vinylidene chloride-vinyl chloride copolymer of Example 1 and about 25 percent of antimony trioxide of about 1.5 micron average particle size, was extruded through a spinneret containing 225 holes, each having a diameter of about 0.8 mm., into an aqueous coagulation bath followed by an aqueous bath containing about 4 percent sulfuric acid at a rate sufficient to produce 400/225 cuprammonium rayon filament yarn. The coagulation yarn was collected on a reel, tied into a skein, and subjected to conventional washing and drying procedures. The resultant yarn which had a hand or feel substantially identical to that of unmodified cuprammonium rayon yarn was woven into a fabric and subjected to the standard A.A.T.C.C. flame test whereupon it was observed that the afterflame time was less than one second.

6 EXAMPLE 5 Following the procedure described in Example 4, a cuprammonium spinning solution containing about 6 percent of cellulose and about 25 percent, based on the cellulose content of the solution, of the flame-retarding mixture of Example 4 was spun into cuprammonium rayon yarn having a hand or feel substantially identical to that of unmodified cuprammonium rayon yarn. This yarn was woven into fabric and subjected to the standard A.T.T. C.C. flame test. It was observed that the afterflame time was less than one second.

EXAMPLE 6 Following the procedure described in Example 4, a cuprammonium spinning solution containing about 6 percent of cellulose and about 20 percent, based on the cellulose content of the solution, of the flame-retarding mixture of Example 4 was spun into cuprammonium rayon yarn having a hand or feel substantially identical to that of unmodified cuprammonium rayon yarn. This yarn was woven into fabric and subjected to the standard A.A.T. C.C. flame test. It was observed that the afterflame time was less than one second.

EXAMPLE 7 A conventional viscose spinning solution was prepared containing about 66 /3 parts of cellulose, about 25 parts of the vinylidene chloride-vinyl chloride copolymer of Example 1, and about 8 /3 parts of antimony trioxide. Film was cast from this solution in a conventional manner. This film was an orange-brown color but it was observed that the afterflame time for this film was less than one second when it was subjected to the standard A.A.T. C.C. flame test.

EXAMPLE 8 A conventional cellulose acetate spinning solution was prepared containing about 66 /3 parts of cellulose acetate, about 25 parts of the vinylidene chloride-vinyl chloride copolymer of Example 1, and about 8 /3 parts of antimony trioxide. Strong, white film was cast from this solution in a conventional manner. This film was subjected to the standard A.A.T.C.C. flame test and it was observed that the afterflame time was less than one second.

EXAMPLE 9 A modified spinning solution prepared in a manner identical to that followed in Example 3 was extruded in a regular cuprammonium funnel using a 2000 hole, 200 micron viscose spinneret to produce a 1000/2000/0 filament yarn comprising about 66 /3 parts of cellulose, 25 parts of the vinylidene chloride-vinyl chloride copo ymer of Example 1, and 8 /3 parts of antimony trioxide. Acceptable filament was obtained although some orifice clogging was observed. This filament was subjected to the standard A.A.T.C.C. flame test and it was observed that the afterflame time was less than one second.

EXAMPLE 10 A woven fabric made from rayon yarn was dipped into an aqueous dispersion comprising about grams per liter of solids of which about 75 percent is the vinylidene chloride-vinyl chloride copolymer of Example 1 and about 25 percent is antimony trioxide. The coated fabric was squeezed and dried to provide a pickup of about 10 percent of the mixture on the fabric. The coated fabric was stiff and had a hand or feel considerably less desirable than the uncoated yarn. This coated fabric was subjected to the standard A.A.T.C.C. flame test and it was observed that the afterflame time was more than two seconds as called for by this test. A

Higher concentrations of additive may be used to provide a coated fabric having improved flame-proofing properties. However, these fabrics would have a very poor hand or feel and the flame-proofing properties would deteriorate with repeated launderings or dry cleanings.

It is understood that changes and variations may be made in the present invention by one skilled in the art without departing from the spirit and scope thereof as defined in the appended claims.

What is claimed is:

1. Regenerated cellulose filaments having been coagulated from a cuprammonium cellulose spinning solution and having dispersed therein from about 10 to 100 parts, based on 100 parts of cellulose present, of a flame-retarding mixture comprised of from about 20 to 90 percent by weight of a vinyl chloride polymer selected from the group consisting of poly(vinyl chloride), poly(vinylidene chloride), and copolymers of vinyl chloride or vinylidene chloride with other polymerizable olefinically unsaturated compounds in which the vinyl chloride or vinylidene chloride is present in amounts of at least 50 percent by weight and from about 10 to 80 percent by weight an antimony oxide.

2. The regenerated cellulose filaments of c aim 1 wherein the flame-retarding mixture is comprised of from UNITED STATES PATENTS 3,235,642 2/1966 Blomberg 264182 2,591,368 4/1952 McCarthy 260-17 2,816,004 12/ 1957 Rossin et al. 264-188 3,243,391 3/1966 Wagner 260-45 3,277,226 10/1966 Bockno et al 2'6419 8 3,300,423 1/ 1967 Borown et al. 26017 WILLIAM SHORT, Primary Examiner L. M. PHYNES, Assistant Examiner Us. 01. X.R. 26017; 264-199