Flame Retardant Textiles

Abstract

Disclosed are textile yarns comprising a plurality of antimony-containing fibers and a plurality of bromine-containing fibers. The antimony-containing fibers are formed from a polymer having an antimony-containing compound dispersed therein and the bromine-containing fibers are formed from a polyester having a bromine-containing compound dispersed therein. The textile yarns of this invention exhibit an unobvious combination of commercially acceptable mechanical properties and commercially acceptable flame retardancy. Blends of the fibers used to prepare the yarn are also disclosed. Fabrics of the yarn are also disclosed.

Description

This invention relates to a textile yarn of a plurality of antimony-containing fibers and a plurality of bromine-containing fibers. The textile yarn of this invention exhibits a combination of mechanical properties and flame retardancy necessary in a commercially acceptable textile yarn.

The use of synthetic textile yarns has increased tremendously over the last several decades. Although a synthetic textile yarn may have any number of desirable properties, every textile yarn must have a number of necessary properties to make the fiber commercially acceptable for typical applications such as wearing apparel, carpets and the like. Historically, certain mechanical properties have been necessary in order to make a yarn commercially acceptable.

One undesirable property of most synthetic yarns is a lack of flame retardancy. The growing significance of this property has now caused many textile yarns to be regarded as commercially unacceptable for many applications because of the lack of flame retardancy, even though the textile yarns exhibit the mechanical properties necessary for commercial acceptance. One particular and significant instance where textile yarns must be flame retardant is the children's sleepwear field where polyester/cotton blends enjoy popularity. Therefore, to meet current standards for many applications, the properties that have been historically necessary for commercially acceptable textile yarns must be revised to include at least a moderate degree of flame retardancy, and in some cases a substantial degree of flame retardancy.

Efforts to produce polyester yarns which will meet many of the more stringent standards of flame retardancy and still exhibit mechanical properties necessary for commercial acceptance have generally been unsatisfactory. The failure to produce the desired yarn has not generally resulted from an inability to impart flame retardancy to the yarn, but instead has resulted from an inability of the yarn to exhibit a combination of the mechanical properties historically necessary for commercial acceptance and a level of flame retardancy suitable for current commercial acceptance.

Specifically, it is well known in the art that commercially acceptable levels of flame retardancy can be achieved in a polyester yarn by dispersing a bromine-containing compound and an antimony-containing compound in the same fiber in the yarn. Representative of this art are U. S. Pat. Nos. 3,419,518; 3,285,965; 3,347,822; 2,669,521 and 2,480,298, wherein it is disclosed that a combination of antimony-containing compounds and bromine-containing compounds are suitable for imparting flame retardancy to yarns of polyesters. Commercially acceptable flame retardancy in these yarns has been regarded to be a consequence of the well-known phenomenon that when an antimony-containing compound and a bromine-containing compound are dispersed in the same ploymer they act synergistically and produce a yarn with an excellent level of flame retardancy which is greater than the level of flame retardancy that can be achieved through use of either of the compounds by themselves. Thus, the prior art teaches that the bromine-containing compound and the antimony-containing compound must be in intimate contact within the same polymer matrix in order for the synergistic effect to occur. Although polyester yarns of fibers having both an antimony-containing compound and bromine-containing compound dispersed in the same fiber exhibit excellent commercially acceptable levels of flame retardancy, the mechanical properties of the melt-spun yarns are, quite unfortunately, commercially unacceptable.

Thus, in summary, the state of the art is that yarns with commercially acceptable flame retardancy, but commercially unacceptable mechanical properties, can be prepared by dispersing in the same melt-spun polyester fiber of the yarn both an antimony-containing compound and a bromine-containing compound.

We have now discovered a textile yarn that exhibits commercially acceptable mechanical properties as well as a commercially acceptable level of flame retardancy. In broad summary we have achieved this result by forming a textile yarn of

A. a plurality of textile fibers that contain an antimony-containing compound but do not contain a bromine-containing compound, and

B. a plurality of textile fibers that contain a bromine-containing compound but do not contain an antimony-containing compound.

Stated another way, we have discovered that, entirely contrary to the teaching of the prior art, the antimony-containing compound and the bromine-containing compound do not have to be in intimate contact within a single polymer matrix for the above noted synergistic effect to occur. Stated even more simply, in our invention we put the antimony-containing compound in one fiber and the bromine-containing compound in another fiber instead of putting both compounds in one fiber as is taught by the prior art. Thus, we have at least discovered a textile yarn that exhibits not only the mechanical properties necessary for commercial acceptability, but also exhibits a commercially acceptable level of flame retardancy.

Accordingly, an advantage of the textile yarn of this invention is a commercially acceptable level of flame retardancy.

Another advantage of the textile yarn of this invention is the commercially acceptable mechanical properties.

Another advantage of the textile yarn of this invention is the combination of commercially acceptable mechanical properties and commercially acceptable flame retardancy.

Other advantages and features of this invention will be readily apparent to those skilled in the art from the following description and appended claims.

We have accomplished the remarkable objective of obtaining a textile yarn that exhibits a desirable combination of mechanical properties and flame retardancy necessary for commercial acceptance by discovering a textile yarn broadly comprising

A. a plurality of antimony-containing fibers formed from a polymer selected from the group consisting of polyesters, modacrylics, regenerated cellulose, polyamides and cellulose acetate, the fibers having uniformly dispersed through the fiber, based on the weight of the antimony-containing fibers, from 0.1-20 weight percent of an antimony-containing compound, and

B. a plurality of bromine-containing fibers formed from a polyester, the fibers having uniformly dispersed throughout the fiber, based on the weight of the bromine-containing fibers, from 1-50 weight percent of a bromine-containing compound having a molecular weight of at least 500 and containing from 40-80 weight percent bromine, based on the weight of the bromine-containing compound.

In this disclosure the term "antimony-containing fiber", and terms of similar import, is defined to mean a fiber that contains an antimony-containing compound, and optionally other materials, but does not contain a bromine-containing compound, except perhaps in very minute trace, or impurity amounts. Thus, because the antimony-containing fiber of this invention does not contain a bromine-containing compound, applicants regard the antimony-containing fiber of their invention as literally distinguishable over the prior art disclosing a single fiber that contains both an antimony-containing compound and a bromine-containing compound.

In this disclosure the term "bromine-containing fiber", and terms of similar import, is defined to mean a fiber that contains a bromine-containing compound, and optionally other materials, but does not contain an antimony-containing compound, except perhaps in very minute trace, or impurtiy amounts. Thus, because the bromine-containing fiber of this invention does not contain an antimony-containing compound, applicants regard the bromine-containing fiber of their invention as literally distinguishable over the prior art disclosing a single fiber that contains both an antimony-containing compound and a bromine-containing compound.

As noted above, one desirable characteristic of the textile yarns of this invention is their mechanical properties. More specifically, the mechanical properties of the fibers of the textile yarns of this invention, such as tenacity, elongation and modulus, are quite similar to a yarn of fibers containing no additives or only an antimony-containing compound or, alternatively, only a bromine-containing compound. In contrast however, the mechanical properties of the yarn of this invention are quite superior to a yarn wherein the fibers contain both an antimony-containing compound and a bromine-containing compound in the same fiber. In one embodiment of this invention the toughness is more than 30 percent geater, and in another embodiment is more than 50 percent greater, than a control yarn of fibers having both an antimony-containing compound and a bromine-containing compound in the same fiber.

Another desirable characteristic of the textile fibers of this invention is the excellent and commercially acceptable level of flame retardancy. Typically, the levels of flame retardancy of the yarns of this invention are equal to the levels of flame retardancy of yarns containing both a bromine-containing compound and an antimony-containing compound in the same fiber. In one embodiment of this invention textile fabrics of the yarn of this invention pass the Children's Sleepwear test (DOC FF 3-71).

According to this invention the antimony-containing fibers are formed from a polymer selected from the group consisting of polyesters, modacrylics, regenerated cellulose, polyamides and cellulose acetate. The bromine-containing fibers are formed from a polyester.

The polyesters of this invention can be prepared from one or more aliphatic, alicyclic, or aromatic diols containing from two to 40 carbon atoms and one or more aromatic, alicyclic or aliphatic dicarboxylic acids containing from two to 40 carbon atoms. In one preferred embodiment the antimony-containing fibers are formed from a polyester of a dicarboxylic acid component which is at least 80 mole percent terephthalic acid and a glycol component which is at least 80 mole percent ethylene glycol, 1,4-butanediol, or 1,4-cyclohexanedimethanol. In one especially preferred embodiment the antimony-containing fibers are formed from poly(ethylene terephthalate).

In this invention the antimony-containing fibers have uniformly dispersed throughout the fiber, based on the weight of the antimony-containing fibers, from 0.1-20 weight percent of an antimony-containing compound. Although many types of antimony-containing compounds are suitable for use in this invention, antimony trioxide is especially preferred due to its availability and effectiveness. In another embodiment, the antimony-containing fibers can contain from 0.5-5 weight percent of the antimony-containing compound, based on the weight of the antimony-containing fiber, and in one still further embodiment the antimony-containing fiber can contain 1 to 4 weight percent antimony-containing compound, based on the weight of the antimony-containing fibers.

In this invention the bromine-containing fibers have uniformly dispersed throughout the fiber, based on the weight of the bromine-containing fibers, from 1-50 percent of the bromine-containing compound which has a molecular weight of at least 500 and containing from 40-80 weight percent bromine, based on the weight of the bromine-containing compound. In another embodiment the bromine-containing fibers contain 3-30 weight percent of the bromine-containing compound.

In one still further embodiment the bromine-containing compound is an addition polymer which comprises at least 35 mole percent poly(tribromoneopentyl acrylate) having units of the structure ##SPC1##

This compound is well known in the art and described in U. S. Pat. No. 3,165,502. In another aspect of this embodiment the plurality of bromine-containing fibers are formed from poly(ethylene terephthalate) having uniformly dispersed throughout the fiber 5-12 weight percent of a bromine-containing compound selected from the group consisting of addition polymers having at least 95 mole percent units derived from poly (tribromoneopentyl acrylate) having the above noted units.

In one still further embodiment, the bromine-containing compound has a molecular weight of at least 2,000 and is a linear bromopolycarbonate wherein at least 50 percent of the recurring units in the polymer chain are connected by ##SPC2##

linkages and at least 50 percent of the recurring units include the structure ##SPC3##

In another aspect of this embodiment substantially 100 percent of the recurring units include the structure. ##SPC4##

and substantially 100 percent of the recurring units in the bromopolycarbonate chain are connected by ##SPC5##

linkages. In a specific aspect of this embodiment the plurality of bromine-containing fibers are formed from poly(ethylene terephthalate) and have uniformly dispersed throughout the fiber 5-12 weight percent of a linear bromopolycarbonate wherein substantially 100 percent of the recurring units include the structure ##SPC6##

and substantially 100 percent of the recurring units in the bromocarbonate chain are connected by ##SPC7##

linkages.

In another aspect this invention comprises a blend of the fibers used to prepare the yarns of this invention. Although the fibers of the blend can be either staple or continuous filament, staple is preferred because of the ease of blending the antimony-containing fibers and the bromine-containing fibers. In one approach the blending of the fibers can be accomplished by a producer of both the antimony-containing fiber and bromine-containing fiber and the blend can then be sold to customers of the fiber manufacturer. In another approach the customer of the fiber manufacturer can buy antimony-containing fiber and bromine-containing fiber separately and accomplish blending prior to spinning the fibers into yarn. In another aspect of this invention the blends of staple fibers are not spun into yarns but can be used in typical non-woven applications such as fiberfill for pillows and blankets and preparation of non-woven textile goods.

Textile fabrics of the yarn of this invention are also within the scope of this invention.

The antimony-containing compound and bromine-containing compound can be incorporated into the polymer melt before melt spinning by a variety of means well known to the art, such as admixing the compound with the melted polymer or slurrying a solution of the compound with polymer powder and evaporating off the solvent.

The textile fibers used to prepare the yarn of this invention can be spun by conventional spinning techniques such as melt spinning. The fibers can then be drawn, crimped, heat-set and prepared into yarn by conventional procedures. A conventional phosphorus-containing stabilizer, such as tri(2-ethylhexyl) phosphate, may be added to limit the thermal degradation of the polyester during melt spinning. To reduce the spinning temperature of high melting polyesters, a processing aid also may be blended with the bromine-containing compound and polyester if desired. The processing aid can consist of an aromatic compound which boils above 300.degree.C., preferably above 350.degree.C., and is compatible with the polyester. Examples include triphenyl phosphate, tricresyl phosphate, tri(chlorophenyl) phosphate, chlorinated biphenyls containing 35-70 percent chlorine, chlorinated diphenyl ether containing 35-70 percent chlorine, chlorinated terphenyls containing 0-70 percent chlorine, terphenyl, benzophenone, triphenylmethane, dioctyl phthalate, and diphenyl sulfone. The preferred processing aids are those which contain phosphorus or halogen atoms and, therefore, contribute to the flame resistance, e.g., triaryl phosphates and chlorinated aromatic hydrocarbons containing 35-70 percent chlorine. The polyester fibers may contain 5-30 percent by weight of the processing aid.

The polymers of this invention are well known in the art and can be formed according to conventional well known polymerization techniques.

The polyesters of this invention have an inherent viscosity of at least 0.5, measured at 25.degree.C. using 0.23 grams of polymer per 100 ml. of a solvent composed of 60 volumes of phenol and 40 volumes of tetrachloroethane.

The following examples are intended to illustrate but not limit the invention.

The children's sleepwear test referred to in these examples is carried out as described in "Standard for the Flammability of Children's Sleepwear" (DOC FF 3-71). Briefly, in the test five or more conditioned specimens, 3.5 .times. 10 in., are suspended one at a time vertically in holders in a prescribed cabinet and ignited for 3 seconds using a standard flame along their bottom edge. Each specimen contains an overlap seam (three plies) one-half in. wide which runs the length of the specimen. The overlap seam is sewed with two rows of conventional silicone lubricated polyester thread spaced three-eighths in. apart. To pass the test, no specimen shall be completely consumed, the average char length of the specimens must be less than 7.0 in., and no burning fragments from any specimen shall be present on the floor of the test cabinet more than ten seconds after the removal of the ignition flame.

The oxygen index test is described in MODERN PLASTICS, March, 1970, p. 124 and can be broadly described as the minimal volume percent of oxygen in a slowly rising oxygen/nitrogen atmosphere that will sustain the candle-like burning of the fabric when the fabric is ignited at the top. To prevent dripping, pieces of knitted fabrics are sewed with three vertical rows one-fourth in. apart of double-stitched glass threads and clamped at the edges in a frame. The oxygen index is a convenient, reproducible, numerical measure of polymer flammability.

EXAMPLE 1

This example illustrates the commercially unacceptable mechanical properties and commercially acceptable flame retardancy of yarns of poly(ethylene terephthalate) fibers of the prior art which contain both an antimony-containing compound and a bromine-containing compound intimately dispersed in the same polyester fiber.

Into a drum are placed a quantity of poly(tribromoneopentyl acrylate) I.V. 0.60, and, based on the total weight, a sufficient quantity of poly(tribromoneopentyl acrylate) to comprise 6 weight percent, and a sufficient quantity of antimony trioxide to comprise 1.5 weight percent. The drum is then placed on parallel rolls and rolled for several hours to facilitate mixing. The physical mixture is then dried in a vacuum oven at 95.degree.C. overnight and melt extruded at 273.degree.C. into one-eighth inch rods and pelletized. The pellets are then dried under vacuum at 110.degree.C. and melt spun at 280.degree.C. The fibers are too brittle to draft satisfactorily, thus indicating that the mechanical properties of the fibers are commercially unacceptable. A sock is knitted from the undrafted fibers, and scoured. When the children's sleepwear test is carried out on the sock, it passes the test.

Similar results are obtained when other bromine-containing compounds, such as brominated terphenyls, and other polyesters, such as poly (1,4-cyclohexylenedimethylene terephthalate), are used.

Thus, applicants have illustrated that yarns of polyester fibers wherein both a bromine-containing compound and an antimony-containing compound are intimately dispersed in the same fiber exhibit commercially unacceptable mechanical properties, but exhibit commercially acceptable flame retardancy.

EXAMPLE 2

This example illustrates the commercially acceptable mechanical properties and the commercially acceptable flame retardancy of yarns of this invention comprised of a plurality of poly(ethylene terephthalate) fibers having a bromine-containing compound, but no antimony-containing compound, dispersed therein, and a plurality of poly(ethylene terephthalate) fibers having an antimony-containing compound, but no bromine-containing compound, dispersed therein.

Two ends of poly(ethylene terephthalate) fibers containing 8 wt. percent poly(tribromoneopentyl acrylate) (68 filaments and 166 denier) and two ends of poly(ethylene terephthalate) fibers containing 3 wt. percent antimony trioxide (68 filaments and 162 denier) are plied to give 136 filaments and 328 denier. The resulting plied fiber contains overall 4 wt. percent poly(tribromoneopentyl acrylate) and 1.5 wt. percent antimony trioxide. The 328 denier, plied fibers are knitted into a jersey knit sock (8 oz/yd..sup.2), scoured, and tested according to the children's sleepwear test. The sock passes the test.

The fibers of the yarn have the following commercially acceptable properties: tenacity 4 g./denier, elongation 25 percent and elastic modulus of 48 g./denier.

Socks of only the poly(ethylene terephthalate) fibers containing 4 wt. percent poly(tribromoneopentyl acrylate) fail the children's sleepwear test. Socks of only the poly(ethylene terephthalate) fibers containing antimony trioxide fail the children's sleepwear test.

These results illustrate that, very surprisingly, a synergistic effect obtains between an antimony-containing compound and a bromine-containing compound in poly(ethylene terephthalate), even though the antimony-containing compound and brominated-containing compound are not present in the same fibers but are in separate fibers.

A similar synergistic effect obtains when other bromine-containing compounds, other antimony-containing compound and other polyesters, such as poly(tetramethylene terephthalate) and poly(1,4-cyclohexylenedimethylene terephthalate), are used. Also, similar synergistic results are obtained when the polymer of the antimony-containing fiber is modacrylic, regenerated cellulose, polyamide or cellulose acetate. Of course the exact levels of antimony-containing compound and bromine-containing compound necessary to achieve any specific level of flame retardancy would vary depending on the specific polymer, specific antimony-containing compound and specific bromine-containing compound selected.

Thus, applicants have demonstrated that yarns comprised of a plurality of polyester fibers having a bromine-containing compound, but no antimony-containing compound dispersed therein, and a plurality of polyester fibers having an antimony-containing compound, but no bromine-containing compound, dispersed therein, exhibit commercially acceptable mechanical properties and commercially acceptable flame retardancy.

Stated another way, applicants have demonstrated that quite unobviously, commercially acceptable flame retardancy can be achieved due to a synergistic effect that obtains when the bromine-containing compound and the antimony-containing compound are dispersed in different fibers in the same yarn.

EXAMPLE 3

This example also illustrates the commercially acceptable mechanical properties and the commercially acceptable flame retardancy of yarns of this invention.

Two ends of poly(ethylene terephthalate) fibers (68 filaments and 170 denier) containing 8 wt. percent brominated terphenyl (75 percent bromine) and two ends of poly(ethylene terephthalate) fibers (68 filaments and 162 denier) containing 3 wt. percent antimony trioxide are plied and knitted into a jersey knit sock (8 oz./yd..sup.2). Overall, the sock contains 4 wt. percent brominated terphenyl and 1.5 wt. percent antimony trioxide. The mechanical properties of the yarn are commercially acceptable. When the children's sleepwear test is carried out on the sock, it passes the test. Socks of the poly(ethylene terephthalate) fibers containing only 4 wt. percent brominated terphenyl or only antimony trioxide fail the children's sleepwear test.

These results further illustrate that, very surprisingly, a synergistic effect obtains beteen an antimony-containing compound and a bromine-containing compound in poly(ethylene terephthalate), even though the antimony-containing compound and bromine-containing compound are not present in the same fibers but are in separate fibers.

Thus, applicants have again demonstrated that yarns comprised of a plurality of polyester fibers having a bromine-containing compound, but no antimony-containing compound dispersed therein, and a plurality of polyester fibers having an antimony-containing compound, but no bromine-containing compound, dispersed therein, exhibit commercially acceptable mechanical properties and commercially acceptable flame retardancy.

EXAMPLE 4

This example also illustrates the commercially acceptable mechanical properties and the commercially acceptable flame retardancy of yarns of this invention.

Two ends (178 denier) of a poly(1,4-cyclohexylenedimethyleneterephthalate) fiber containing 15 wt. percent bis(pentabromophenyl)ether and one end (92 denier) of a poly(1,4-cyclohexylenedimethylene terephthalate) fiber containing 5 wt. percent of a fused 70/30 mixture of antimony trioxide/monosodium phosphate are plied to give 270 denier/15 filaments. The overall composition of the fibers is poly(1,4-cyclohexylenedimethylene terephthalate) containing 10 wt. percent bis(pentabromophenyl)ether and 1.7 wt. percent of the fused 70/30 mixture of antimony trioxide/monosodium phosphate. The plied fibers are then knitted into a sock, scoured, and dried. The oxygen index of the sock is 22.6. The mechanical properties of the yarn are commercially acceptable.

These results offer still further illustration that, very surprisingly, a synergistic effect obtains between an antimony-containing compound and a bromine-containing compound in poly(1,4-cyclohexylenedimethylene terephthalate) even though the antimony-containing compound and bromine-containing compound are not present in the same fibers but are in separate fibers.

EXAMPLE 5

This example further illustrates the commercially acceptable mechanical properties and the commercially acceptable flame retardancy of yarns of this invention.

One end (176 denier/30 filaments) of a poly(tetramethylene terephthalate) fiber containing 20 wt. percent tris[2,2-bis(bromomethyl)-3-bromopropyl] phosphate is plied with one end (153 den./30 filaments) of a poly(tetramethylene terephthalate) fiber containing 3 wt. percent antimony trioxide and knitted into a sock. The overall composition of the sock is poly(tetramethylene terephthalate) containing 10 wt. percent tris[2,2-bis(bromomethyl)-3-bromopropyl] phosphate and 1.5 percent antimony trioxide. The sock is scoured and its oxygen index is determined to be 25.4. The mechanical properties of the yarn are commercially acceptable.

These results offer still further illustration of the synergistic effect that obtains in the yarns of this invention.

EXAMPLE 6

This example also illustrates the commercially acceptable mechanical properties and the commercially acceptable flame retardancy of yarns of this invention.

In the compositions listed below, FR polyester is poly(ethylene terephthalate) fibers containing 12 wt. percent poly[2,2-bis(bromomethyl)trimethylene carbonate]. Using plied yarn blends, knit socks having the following compositions are prepared:

a. 50 percent viscose rayon containing 5 wt. percent antimony trioxide and 20 percent of mixed propoxyphosphazenes (preparation described in Ind. Eng. Chem. Prod. Res. Develop., 9, No. 4, 426 (1970l )). 50 percent FR polyester.

b. 35 percent cellulose acetate containing 8 percent tris(2,3-dibromopropyl) phosphate and 2 percent antimony trioxide. 65 percent FR polyester.

c. 30 percent of a modacrylic fiber containing 82.3 wt. percent of the polymer prepared from 2 moles of acrylonitrile and 1 mole of vinylidene chloride, 15.7 wt. percent poly(N-isopropyl acrylamide), and 2 wt. percent antimony trioxide. 70 percent FR polyester.

d. 20 percent nylon 6 fibers containing 3 wt. percent antimony trioxide. 80 percent FR polyester.

e. 50 percent poly(ethylene terephthalate) containing 3 wt. percent antimony trioxide. 50 percent FR polyester.

Mechanical properties of these yarns are commercially acceptable. Flammability characteristics of the yarns are similar to yarns wherein the antimony-containing compound and bromine-containing compound are in the same fiber.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

Claims

We claim:

1. A textile yarn comprising

A. a plurality of antimony-containing fibers formed from a polymer selected from the group consisting of polyesters, modacrylics, regenerated cellulose, polyamides and cellulose acetate, the fibers having uniformly dispersed throughout the fiber, based on the weight of the antimony-containing fibers, from 0.1-20 weight percent of an antimony-containing compound, and

B. a plurality of bromine-containing fibers formed from a polyester, the fibers having uniformly dispersed throughout the fiber, based on the weight of the bromine-containing fibers, from 1-50 weight percent of a bromine-containing compound having a molecular weight of at least 500 and containing from 40-80 weight percent bromine, based on the weight of the bromine-containing compound.

2. The yarn of claim 1 wherein

the antimony-containing and bromine-containing fibers are formed from a dicarboxylic acid component which is at least 80 mole percent terephthalic acid and a glycol component which is at least 80 mole percent ethylene glycol, 1,4-butanediol, or 1.4-cyclohexanedimethanol.

3. The yarn of claim 2 wherein

the antimony-containing fibers contain from 0.5-5 weight percent of the antimony-containing compound, and

the bromine-containing fibers contain 3-30 weight percent of the bromine-containing compound.

4. The yarn of claim 2 wherein

the bromine-containing compound has a molecular weight of at least 2,000 and is a linear bromopolycarbonate wherein at least 50 percent of the recurring units in the polymer chain are connected by ##SPC8##

linkages and at least 50 percent of the recurring units include the structure ##SPC9##

5. The yarn of claim 4 wherein

substantially 100 percent of said recurring units include the structure ##SPC10##

and substantially 100 percent of the recurring units in the bromopolycarbonate chain are connected by ##SPC11##

linkages.

6. The yarn of claim 1 wherein

the bromine-containing compound is an addition polymer which comprises at least 35 mole percent units of the structure ##SPC12##

7. A textile yarn comprising

A. a plurality of antimony-containing fibers formed from poly(ethylene terephthalate) having uniformly dispersed throughout the fiber from 1 to 4 weight percent antimony trioxide, based on the weight of the antimony-containing fibers, and

B. a plurality of bromine-containing fibers formed from poly(ethylene terephthalate) having uniformly dispersed throughout the fiber 5-12 weight percent of a bromine-containing compound selected from the group consisting of addition polymers having at least 95 mole percent units derived from poly(tribromoneopentyl acrylate) and linear bromopolycarbonates wherein substantially 100 percent of the recurring units include the structure ##SPC13##

and substantially 100 percent of the recurring units in the bromopolycarbonate chain are connected by ##SPC14##

linkages.

8. A fiber blend comprising

A. a plurality of antimony-containing staple fibers formed from a polymer selected from the group consisting of polyesters, modacrylics, regenerated cellulose, polyamides and cellulose acetate, the fibers having uniformly dispersed throughout the fiber, based on the weight of the antimony-containing fibers, from 0.1-20 weight percent of an antimony-containing compound, and

B. a plurality of bromine-containing staple fibers formed from a polyester, the fibers having uniformly dispersed throughout the fiber, based on the weight of the bromine-containing fibers, from 1-50 weight percent of a bromine-containing compound having a molecular weight of at least 500 and containing from 40-80 weight percent bromine, based on the weight of the bromine-containing compound.

9. The fiber blend of claim 8 wherein

the antimony-containing and bromine-containing fibers are formed from a dicarboxylic acid component which is at least 80 mole percent terephthalic acid and a glycol component which is at least 80 mole percent ethylene glycol, tetramethylene glycol or 1,4-cyclohexanedimethanol.

10. The fiber blend of claim 9 wherein

the antimony-containing fibers contain from 0.5-5 weight percent of the antimony-containing compound, and the bromine-containing fibers contain 3-30 weight percent of the bromine-containing compound.

11. The fiber blend of claim 9 wherein

the bromine-containing compound has a molecular weight of at least 2,000 and is a linear bromopolycarbonate wherein at least 50 percent of the recurring units in the polymer chain are connected by ##SPC15##

linkages and at least 50 percent of the recurring units include the structure ##SPC16##

12. The fiber blend of claim 11 wherein

the bromine-containing compound is an addition polymer which comprises at least 35 mole percent units of the structure ##SPC17##

13. The fiber blend of claim 11 wherein substantially 100 percent of said recurring units include the structure ##SPC18## and substantially 100 percent of the recurring units in the bromopolycarbonate chain are connected by ##SPC19##

linkages.

14. A fiber blend comprising

A. a plurality of antimony-containing fibers formed from poly(ethylene terephthalate) having uniformly dispersed throughout the fiber from 1 to 4 weight percent antimony trioxide, based on the weight of the antimony-containing fibers, and

B. a plurality of bromine-containing fibers formed from poly(ethylene terephthalate) having uniformly dispersed throughout the fiber 5-12 weight percent of a bromine-containing compound selected from the group consisting of addition polymers having at least 95 mole percent units derived from poly(tribromoneopentyl acrylate) and linear bromopolycarbonates wherein substantially 100 percent of the recurring units include the structure ##SPC20##

and substantially 100 percent of the recurring units in the bromopolycarbonate chain are connected by ##SPC21##

linkages.

15. A textile fabric of the yarn of claim 1.

16. A textile fabric of the yarn of claim 7.