US3681124A

US3681124A - Process for preparing durable flame-retardant synthetic-cellulosic fabric blends

Info

Publication number: US3681124A
Authority: US
Inventors: Stephen B Sello; Paul H Egrie
Original assignee: JP Stevens and Co Inc
Current assignee: JP Stevens and Co Inc
Priority date: 1970-02-02
Filing date: 1970-02-02
Publication date: 1972-08-01
Anticipated expiration: 1989-08-01
Also published as: DE2104823A1; CH546854A; GB1326288A; CA931437A; CH149271A4

Abstract

FABRIC BLENDS OF CELLULOSIC AND POLYESTER FIBERS ARE RENDERED DURABLY FLAME-RETARDANT BY IMPREGNATING WITH

(A) TETRAKIS(HYDROXYMETHYL)PHOSPHONIUM CHLORIDE AND UREA (OR A PRECONDENSATE OF THESE REACTANTS), (B) A REACTION PRODUCT OF MELAMINE WITH EITHER FORMALDEHYDE OR FORMALDEHYDE AND METHANOL, AND (C) A FATTY ACID ESTER OF POLYETHYLENE GLYCOL, AND FORMING INSOLUBLE REACTION PRODUCTS ON SAID FABRIC THE FATTY ACID ESTER OF POLYETHYLENE GLYCOL SERVES BOTH TO SOFTEN THE FABRIC AND TO CARRY FIREPROFFING REACTION PRODUCTS ONTO THE POLYESTER COMPONENT.

Description

United States Patent 3,681,124 PROCESS FOR PREPARING DURABLE FLAME- RETARDANT SYNTHETIC-CELLULOSIC FABRIC BLENDS Stephen B. Sello, Cedar Grove, N.J., and Paul H. Egrie, New York, N.Y., assignors to J. P. Stevens & Co., Inc., New York, N.Y. No Drawing. Filed Feb. 2, 1970, Ser. No. 8,031 Int. Cl. C09]; 3/28; C09d /18 US. Cl. 117-136 11 Claims ABSTRACT OF THE DISCLOSURE Fabric blends of cellulosic and polyester fibers are rendered durably flame-retardant by impregnating with (A) tetrakis(hydroxymethyl)phosphonium chloride and urea (or a precondensate of these reactants),

(B) a reaction product of melamine with either formaldehyde or formaldehyde and methanol, and

(C) a fatty acid ester of polyethylene glycol,

and forming insoluble reaction products on said fabric. The fatty acid ester of polyethylene glycol serves both to soften the fabric and to carry fireproofing reaction products onto the polyester component.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to an improved process for treating textile materials which are blends of cellulosic and polyester fibers so as to cause fibers of both those classifications to be flame retardant concurrently.

Description of the prior art Although polyester-cotton blends are one of the more common types of fabrics in current use, there is a paucity in the art of conferring fire resistance to such blends.

The situation regarding blended polyester-cotton is unusual, inasmuch as fabrics solely of polyester fiber normally meet specifications for flame retardancy, such as the Vertical Test of the American Association of Textile Chemists and Colorists, AATCC 34-1966, without the addition of a fire retardant finish. However, when only the cotton fibers of a blended fabric are rendered flame retardant, the resulting product is quite flammable and does not meet flame retardancy specifications. This is due to the fact that when 100 percent polyester fabric is exposed to a flame, the polyester melts and drips away largely unburned, while on exposure of a blended fabric of polyester and flame-resistant cotton to a flame, the cotton prevents the polyester from dripping away.

Satisfactory flame retardancy is obtained only when both polyester fibers and cotton fibers are rendered individually flame retardant. Heretofore, one proposal for rendering both types of fibers individually flame retardant in a blended fabric has been to combine two treatments, one designed to treat polyester and the other cotton fibers. In work described in American Dyestulf Reporter, vol. 57, page 373 (May 6, 1968), samples of blended fabric were treated with compositions containing tetrakis(hydroxymethyl)phosphonium chloride, a known fire retardant for cellulosic fabric and then other samples were treated with tetrakis(hydroxymethyl)phosphonium chloride formulations plus tris(2,3-dibromopropyl) phosphate, a known polyester fire retardant. Only one of the treating procedures, which did not include tris(2,3-dibromopropyl) phosphate, gave satisfactory flame retardancy. In this procedure, the fabric was padded at 80 F. with a formulation containing tetrakis(hydroxymethyDphosphoninm chloride, trimethylolmelamine, urea, sodium hydrox- 3,681,124 Patented Aug. 1, 1972 ice SUMMARY OF THE INVENTION In accordance with the present invention, excellent flame retardancy of cellulosic-polyester blends is obtained without the necessity of applying a separate, polyester flame retardant such as tris(2,3-dibromopropyl) phos phate and without unduly deteriorating physical properties or imparting objectionable stiifness. The cellulosic-polyester blended fabrics are rendered durably flame retardant by impregnating with (A) tetrakis(hydroxymethyl)phosphonium chloride and urea or a precondensate of these reactants,

(C) a fatty acid ester of polyethylene glycol and forming insoluble reaction products on said fabric. It is essential that the reaction product containing melamine be insolubilized in the presence of moisture such as by steam curing.

DETAILED DESCRIPTION OF THE INVENTION This invention provides a method of rendering a polyester cellulosic blend fabric flame retardant by impregnating the fabric with the following chemical systems:

System A: Tetrakis (hydroxymethyl)phosphonium chloride and urea or a precondensate of these reactants, System B: Melamine-formaldehyde reaction product or a melamine-formaldehyde-methanol reaction product, and System C: An ester derived from polyethylene glycol and a higher aliphatic carboxylic acid,

ing insoluble products to the polyester component and also prevents the insoluble products from making the fabric unduly stitf.

All of the components of Chemical Systems A, B and C can be applied and then the desired insoluble products formed simultaneously, thus, for instance, all of the chemicals can be applied from a single bath such as by padding from an aqueous dispersion, and then the desired insoluble products formed simultaneously in a single curing step. Alternatively, the polyethylene glycol ester of System C can be added to the fabric, along with the chemicals of System B, an insoluble product formed by curing and then the chemicals of System A added and insolubilized. Additionally, the chemicals of System A can be added and insolubilized and then the polyethylene glycol ester of System C can be added to the fabric along with the chemicals of System B, and insoluble products formed by curing.

The compounds of System A form an insoluble product containing bound phosphorus and bound nitrogen. The insoluble product can be formed by the reaction on the fabric of tetrakis(hydroxymethyl)phosphonium chloride and urea. Alternatively, there can be applied to the fabric a precondensate of tetrakis (hydroxymethyl)phosphonium chloride and urea which is subsequently further reacted. Procedures for preparing such precondensates are described by Reeves et al. US. Pat. 2,812,311 and Coates U.S. Pat. 2,983,623. The following equation illustrates the formation of a suitable precondensate:

2(H1N-)2C=O (H CHz-)4P C1- (urea) tetrakis(hydroxymethyl)phosphonium chloride The use of a precondensate minimizes objectionable odor during formation of an insoluble product on the fabric. The compounds of System A can be reacted to form an insoluble product by heating at a temperature of about 60250 C. or by the wet fixation procedures described below.

The component of System B is an N-methylol derivative of melamine having from two to six methylol groups or a methyl ether derived from such an N-methylol compound wherein the sum of CH OH groups and -CH OCH groups is from two to six. The N-methylol compounds can be prepared by reacting melamine with two or more moles of formaldehyde according to known procedures. The methyl ethers can be prepared by known procedures by reacting the N-methylol compounds with methanol or coreacting melamine, formaldehyde and methanol.

To avoid unduly deteriorating the physical strength of the fabrics, the components of System B cannot be insolubilized by dry heat, but rather wet fixation procedures must be used. In such wet fixation, the components of System B are formed into an insoluble product while the moisture content of said fabric is at least 20 percent based on the weight of the fabric. Wet fixation is preferably accomplished by contacting the impregnated fabric with steam. Alternatively, wet fixation can be carried out at lower temperatures by maintaining the fabric in a moist environment at a temperature and for a period of time sufiicient to form an insoluble product. For instance, the fabric can be impregnated with an aqueous solution of N-methylolmelamine, the fabric wrapped in polyethylene while a substantial amount of water remains in the fabric, and the wrapped fabric stored at a temperature of at least 20 C. until the desired degree of insolubilization is reached. Use of wet fixation, rather than dry curing, greatly reduces the amount of crosslinking of the N-methylol-type compound with cellulose, thus eliminating undue loss of fabric strength.

System C represents a critical feature of the invention, and stems from the discovery that a particular type of adjunct makes it possible to impart flame retardancy simultaneously to both cellulosic and polyester fibers without causing objectionable stiffness of the treated fabric, the adjunct being a higher aliphatic carboxylic ester derived from polyethylene glycol.

Suitable polyethylene glycol esters have the formula A(OCH CH OA' wherein A is an acyl group derived from a saturated or unsaturated aliphatic monocarboxylic acid of 8-24 carbon atoms;

A is hydrogen or an acyl group derived from a saturated or unsaturated aliphatic monocarboxylic acid of 63-24 carbon atoms, and

m is an integer of from about 4 to 80.

Oleic acid is the preferred acid for making the esters, which include both di-esters as well as mono-esters. Particularly outstanding results are obtained with polyethylene glycol monooleate. Illustrative of other suitable acids are palmitoleic, lauric, myristic, palm'itic, stearic, and arachidic acids.

Useful polyethylene glycols for making the esters have the formula wherein m is 4 to 80.

A conventional way in which various commercial compositions of closely related polyethylene glycols are named is by appending to the term polyethylene glycol a round number approximately the average molecular weight. This is illustrated in Table A.

TABLE A.-ILLUSTRATIVE POLYETHYLENE GLYCOLS Blends of two or more of such products as are illustrated in Table A may be used in making the ester which is to serve in System C of the process of this invention. For instance, a blend of equal parts of polyethylene glycols 300 and 1540 is particularly useful. Major species in that particular blend (conventionally designated as polyethylene glycol 1500) are An important feature of the present invention is that the nonreactive fatty esters of polyethylene glycol are key factors in accomplishing the following two crucial objectives:

(1) They make possible the flame retardancy of the synthetic fiber component of the fabric blend (and with the same agents which are effective in imparting flame retardancy to the cellulosic fiber component).

(2) They keep fabric stiffness at an acceptably low level for a flame-resistant fabric.

Hence, incorporation of the soluble ester composition of this invention into a pad bath of one or more of the flame-retardant ingredients, and the subsequent formation of the flame-retardant finish, provides an effective durable flame-retardant treatment for blends without the problem of excessive stiffness. The nonreactive fatty esters of polyethylene glycol make it possible to attain desirably high add-ons of bound nitrogen (4 to 7 percent) and phosphorus (2 to 4 percent) with a balanced distribution on both cellulosic and noncellulosic components of the synthetic-cellulosic fabric blend.

Heretofore, the high add-ons of the composition supplying bound nitrogen which were required to attain a practical degree of flame retardancy in conjunction with a compound of phosphorus characteristically resulted in too much stififening. That was even the situation when nitrogen-rich compositions, such as melamine-formaldehyde addition reaction products were used.

Not only do the nonreactive esters of polyethylene gly col improve flame retardancy of fabric blends, but stiffness is kept at a level which is but a fraction of the stiffness which normally would result with blends which are otherwise difiicult to make flame retardant.

Another surprising aspect of the nonreactive esters of polyethylene glycol is that they are quite specific in bringing about the beneficial effects discussed above. Closely related derivatives, such as polyethylene glycols or their monoesters, having a methoxy group in place of a terminal hydroxy group are hardly effective in meaningful control of stiffness.

The results obtained are particularly remarkable in view of the fact that the nonreactive fatty esters of polyethylene glycol which make possible the improved process of this invention are not per se durable additives. On the contrary, they are water-soluble, and are substantially removed in the rinsing operations of the process, their beneficial effect on flame retardancy being unexpected.

The present invention can be used with cellulose-polyester blended fabrics containing from to 90 percent cellulose and from about 90 to 10 percent polyester.

Illustrative of suitable commercial blended fabrics are: polyester 20% and cotton 80%, polyester 35% and cotton 65%, polyester 50% and cotton 50%, polyester 65% and cotton 35%, polyester 80% and cotton 20%, and polyester 65% and regenerated cellulose (as viscose rayon) 35%. The invention is applicable likewise to other ratios, and to blends having fiber types in addition to cellulosic and polyester types, such as the blend consisting of polyester 37%, cotton 35%, and spandex 28%. Cellulose fibers include those made from (a) seed hairs, e.g., cotton, (b) bast fibers such as flax (linen), and (c) rayon and modified rayons.

The following examples are given to further illustrate the invention, but it is to be understood that the invention is not to be limited in any way by the details described therein. Examples 1-3 illustrate the ability of the polyethylene glycol esters employed in the present invention to prevent undue stiffening of the treated cellulosepolyester blended fabrics, while the remaining examples illustrate the methods of the present invention for rendering such blended fabrics flame retardant. In the examples percents and parts are by weight unless otherwise specified.

Analytical and test methods employed in the examples Bound Nitrogen, N: Determined Kjeldahl digestion followed by titration of distilled ammonia.

Bound Phosphorus, P: Determined by Kjeldahl digestion followed by colorimetric analysis employing acetonewasher, 5-pound load, full cycle, 60 C., synthetic detergent; tumble drying.

Stiifness (Cantilever), in mg.-cm.: ASTM D 1388-64.

Tear Strength (Elmendorf), in pounds: ASTM D 1424- 59.

Whitness Rating: AATCC 110-19-64T.

Abbreviations used in the examples OWB: On the weight of the bath used for padding, in

percent.

OWF: On the weight of the fabric, in percent.

Wet pickup (in percent) times OWB/ 100% =OWF.

PEG: Polyethylene glycol.

THPC: Tetrakis(hydroxymethyl)phosphonium chloride,

.(HOCH -PCl.

TMM: Trimethylolmelamine, (s-triazine 2,4,6 triyltriimino trimethanol.

EXAMPLE 1 This example provides a comparison of the extents to which various additives derived from polyethylene glycols aflFect stiffness of a polyester-cellulose blend on which trimethylolmelamine is insolubilized by steaming.

The substrate fabric was -50 polyester-cotton poplin suiting weighing 6.24 ounces per square yard, and having a thread count (warp by filling) of 129 by 49 per inch. Its stiffness was 550 milligram-centimeters in the warp direction. Samples were padded with an aqueous solution of trimethylolmelamine (28% hydrogen peroxide (0.3%), and an additive (polyethylene glycol derivative) present in the percentage shown in the accompanying table. (For the control sample, only the additive Was omitted.) The wet pickup was 72-81%. Then the samples were dried at room temperature (approximately 21 C.) to a moisture content of 20%. While on a frame, samples were steamed for 8 minutes. They were then washed in warm water, framed to original dimensions, dried in an oven at 105 C., and reweighed. Results of observations and calculations are shown in the accompanying table.

TABLE FOR EXAMPLE 1 Weight gain Stiffness,

Major Percent percent on mg.-em

values in pad poplin (ward Polyethylene gylcol derivative X X of 'm. bath suiting direction) Control (no additive) None None None None 19. 3 10, 000 Methoxy PE G 750 H CH3- 16 7. 5 21. 5 10, 000 Methoxy PE G 750 monooleate Ha-- 16 10.1 19. 9 7, 000 PE G 1500 dioleate leoyl 6: 35 10. 7 22. 9 6, 750 PE G 1000 monoostearate Stearoly H 22 12. 6 21. 1 3, 800 PEG 1500 monooleate- Oleoyl H 6:35 4.0 19.6 2,060 PE G 1500 monooleate .d0-- H 6 :35 8.1 19.6 1, 050

Blank (untreated poplin suiting) Not even treated with TMM None None 550 By comparing the weight gains with that of the control (19.3%), it is evident that insolubilization of trimethylolmelamine on the fabric blend was not impaired by the presence of any of the additives. Note that the additives were derived in a variety of ways from polyethylene glycols of representative molecular-weight ranges.

EXAMPLE 2 This is a variation of Example 1 using less trimethylolmelamine.

The procedure of Example 1 was repeated, but trimethylolmelamine was applied from a 20% solution (instead of 28%). Results of measurements are shown in the accompanying table.

TABLE FOR EXAMPLE 1 Additive (PE G derivative): X(O CHzCHz-) mOX Weight gain Stifiness,

Major Percent; percent on mg.em.

values 11 pa poplin (Warp Polyethylene gylcol derivative X X of m bath suiting direction) Control (no additive) None N one None None 13. 4 8,000 Methoxy PE G H 3--. 16 7.5 15. 8 10, Methoxy PE G 750 monooleate- Oleoyl CH -n. 16 10.1 16. 4 4, PE G 1500 dioleate d0 Oleoyl 6: 35 10.7 19. 6 3, 500 PE G 1000 monostearate Stearoly H 22 12. 6 16. 8 1, 430 PE G 1500 monooleate leoyl 6:35 4. 0 13. 8 1, 650 PE G 1500 monooleate .do... 6:35 8. 1 16. 7 850 Blank (untreated poplin suiting) Not even treated with TMM None None 540 Conclusions are similar to those of Example 1. In addition, stiffness was less because less trimethylolmelamine had been applied to the fabric blend from the more dilute pad bath.

EXAMPLE 3 with the average value of n being about 10). Next, the samples were rinsed for minutes in water at 90 C. Then the samples were dried on frames at 105 C. Results, both prior to laundering and after numerous cycles of laundering and drying, are in the accompanying table.

5 TABLE B FOR EXAMPLE 4 This example provides evidence that significant amounts Pad bath H of trimethylolmelamine are insolubilized on polyester m fibers, a that -p y s reduce stiffness of those 21 THPOzUm precondemmpmem OWF 252 230 synthetic fibers. Weight gain, percent, after rinsing and drying 13. 1 12. 2 In order to show the magnitude of the effectiveness of i g g g g after and drymg but beam 2 37 2 0 both insolubilized trimethylolmelamine and esterpoly- Bound N, percent, after rinsing and drying but before laundering 4. 46 ethers nvwfically on synthetlc dlstmswshegi from Cm length, inches (Wm-QM flame test) 1 2 cellulosic) fibers, the following procedure was carried out. stinne s, m n i. (warp direction) 44 50 Be ore aun ering 1, 0 1,1 Taffeta samples of 100% polyester, having a stiffness of Am laundering 960 1,080 600 milligram-centimeters, were padded with an aque- Bouxg h o s ihori er eentz 2 7 6 0118 Solution of trimethylolamine (34%), hydrogen lei?5efining:1:312:33:11133311311333: e: 27 iie Xi Bound nitrogen percen n an addltive (p y y e glycol de Afimslaufidmngs M1 M rivative) present in the percentage shown 1n the accom- After 50]aundefi(ngs t l h t 3 g() Char length, inches veri ame es panying table. The wet pickup was 37 Then the sam After 10 1mm n gs 5 5 ples were processed 111 the manner described in Example After 251aunderlngs 7.3 7.2 1. Results are shown in the accompanying table. laundenngs 3 TABLE FOR EXAMPLE 3 Additi PEG derivative :X OCH2CH2-) OX v8 m Weight gain, Stiffness, Percent; percent ton mg.-cm. in pa )0 yes er (warp Polyethylene glycol derivative Formula of major species in closely related series bath taffeta direction) Control (no additive) Omitted None 11. 8 Methoxy PEG 750 acetatecH3oo(o0HiGHe-)ie0om 3. 9 12.2 1, 410 D CH3CO(-O CH2CHz-) 00 7. 9 12.6 1, 160 PEG 1000 d1oleate C Ha CO(O CH2CH2)22OCOC11H3I 1 .7 11. 1 720 PEG 1500 monooleate Oi H OO(O CHzCHz-)0OH and Ci1HaeCO(OC 2 2)s.-, H 4. O 8.0 330 D0 C17H33CO(-O CH3CH2)5OH and CIIHUOO('"OCHZCH2)EBOH 8- 1 5. 1 310 Blank (untreated polyester taffeta) Not even treated with TMM- None None 600 EXAMPLE 4 EXAMPLE 5 The fabric used was 5050 polyester-cotton sheeting in a plain weave, weighing 3.56 ounces per square yard, and having a thread count (warp by filling) of 102 by 80 per inch. Its stiffness was 84 milligram-centimeters in the warp direction. The fabric was padded with an aqueous solution of trimethylolamine (20%), hydrogen peroxide (0.3%), and polyethylene glycol 1500 monooleate (8.0%), C H CO(OCH CH OH having 6 and 35 as major values of m.

The pressure of the pad rolls was adjusted to give a wet pickup of 71 to 74% The padded fabric was partially dried in air to a moisture content of (25 i5 Then it was wrapped in polyethylene foil to prevent loss of moisture, and stored at 41 C. for 72 hours to effect wet fixation. Next, the fabric was rinsed in hot water, then in cold water, and dried in a forced-air oven at 105 C. Results are in the accompanying table.

TABLE A FOR EXAMPLE 4 Samples of the fabric pretreated with trimethylohnelamine were padded with a precondensate of tetrakis(hydroxymethyDphosphonium chloride and urea (2:1 ratio by moles). (In one instance, pH was left at 2.8, and in another series, pH was raised to 6.1 by N,N',N"-nitrilotriethanol, commonly called triethanolamine. See the accompanying table.) The samples were dried on frames at 82 C., and cured at 163 C. for 5 minutes in a forced-air oven. The cured samples were rinsed in 2.8% ammonium hydroxide solution for 5 minutes at approximately 21 C., and then for 5 minutes at 50 C. in an aqueous solution containing 0.06% hydrogen peroxide and 0.5% of a nonionic detergent (a mixture of closely related compounds having the formula This example describes the single-step process with a 30-second steaming period to impart durable flame retardance to a synthetic-cellulosic fabric blend.

The fabric used was 50-50 polyester cotton suiting in a plain weave, weighing 6.71 ounces per square yard, and having a thread count (warp by filling) of 74 by 37 per inch. It was padded (to a wet pickup of 78%) using an aqueous pad bath having respectively 14.4%, 7.0%, and 28.9% of each of the following components: trimethylolmelamine, polyethylene glycol 1500 monoleate, and (ureylenedimethylene)bis[tris(hydroxymethyl)phosphonium] dichloride. The latter compound had been made by a condensation reaction involving tetrakis(hydroxymethyl)phosphonium chloride (2 moles) and urea (1 mole). Prior to padding, the pH of the pad bath had been raised to 6 by the addition of a relatively small quantity of N,N',N"-nitrilotriethanol.

The fabric was dried at approximately 71 C. on a pin frame. Then the pin frame with the fabric on it was placed horizontally in a chamber designed for steaming. Steam at approximately 102 C. was introduced, and the fabric was exposed to it for 30 seconds. Next, the fabric was rinsed according to the rinsing procedure described in Example 4. Then the treated fa-bric blend was dried on a frame at 105 C. Data in the accompanying table demonstrate that this suiting fabric had durable flame retardance. Note that the fabric had been impregnated with (ureylenedimethylene)bis[tris(hydroxymethyl)phosphoniu-m] dichloride, trimethylolmelamine, and polyethylene glycol monooleate in the relative amounts by weight of approximately 4, 2, and '1, respectively.

TABLE FOR EXAMPLE 5 Trimethylolmelamine, percent OWF 11.2 PEG 1500 monooleate, percent OWF 5.45 2:1 THPSzurea precondensate, percent OWF 22.4

9 TABLE FOR EXAMPIJE Continued Weight gain, percent, after rinsing and drying 25.3 Char length, inches (Vertical Flame Test):

Before laundering 4.3 \After launderings 4.5 After 25 launderings 5.0

EXAMPLE 6 This example consists of a variation of Example 4.

The steps of Example 4 were applied to 50-50 polyester-cotton sheeting in a plain weave and Weighing 3.67 ounces per square yard. The warp-by-filling count was 101 by 81 threads per inch. In the first step, a sample was padded with an aqueous solution of tn'methylolmelamine (20%), hydrogen peroxide (0.3%), and polyethylene glycol 1500 monooleate (8.0%), and processed by wet fixation as in Example 4. In the second step, the same precondensate as in Example 4 was used (the pad bath having been adjusted to pH 6 by a relatively small quantity of N,N',N-nitrilotriethanol). The sample was processed as in Example 4. Results are in the accompanying table.

TABLE =FOR EXAMPLE 6 EXAMPLE 7 In this example the order of the two steps of Example 6 is reversed.

Another portion of the synthetic-cellulosic blend fabric used as the substrate in Example -6 was processed with the ingredients of that example, but the order of the two steps was reversed. That is, this time Step 1 consisted of padding on the precondensate of Example 4 (after the pad bath had been adjusted to pH 6 by addition of N,N, N"-nitrilotriethanol), followed by curing as in Example 4. This time, Step 2 consisted of padding with an aqueous solution of trimethylolmelamine (20%), hydrogen peroxide (0.3%), and polyethylene glycol 1500 monooleate (8.0% and processing by wet fixation as in Example 4. Results are in the accompanying table.

TABLE FOR EXAMPLE 7 Percent P:

Before laundering After 10 launderings 10 TABLE FOR EXAMPLE 7Continued Percent N:

Before laundering 4.8

After 10 launderings 4.5 Char length, inches:

Before laundering 7.0

After 10 launderings 7.9

EXAMPLE 8 TABLE FOR EXAMPLE 8 N, percent from TMM pretreatment 5.2 2:125 THPC:urea precondensate, percent OWF 23.6 Weight gain, percent, after curing, washing and drying 13.9 Char length, inches (Vertical Flame Test):

Before laundering 5.0 After 10 launderings 5.1 After 25 launderings 5.1 After 50' launderings 5.5

EXAMPLE 9 This example provides a comparison of the relative effectiveness of polyethylene glycol monooleate and tris- (2,3-dibromopropyl)phosphate in the single-step process involving brief steaming to impart durable flame retardance on a synthetic cellulosic blend.

The single-step padding process was applied to the 50-50 polyester-cotton suiting described in Example 5. The compositions of the pad baths (and other variables) are shown in the accompanying table. Tris(2,3-dibromopropyl)phosphate was in emulsified form. Prior to padding, the pH of each pad bath was raised to 5 by the addition of a relatively small quantity of N,N',N"-nitrilotriethanol. The wet pickup of the ingredients was 70 to 73%. The padded samples were dried at approximately 71 C. on a pin frame and then the pin frame with the fabric on it was placed horizontally in a chamber designed for steaming. Steam at approximately 102 C. was introduced, and the fabric was exposed to it for 4 minutes. Next, the fabric was rinsed according to the rinsing procedure described in Example 4 and then dried on a frame at 105 C. Data in the accompanying table demonstrate that this suiting fabric had durable flame retardance.

Percent OWB 3. 3 None Percent OWF 2. 3 None 'lris(2,3-dibromopropyl) phosphate:

Percent OWB None 6. 7

Percent OWF- None 4. 9 Tnmethylohnelarm Percent OWB 14. 7 14. 7

Percent OWF l0. 3 10. 7 2:1 THPC: urea precondensate:

Percent OWB 29. 4 29. 4

Percent OWF 20. 6 20. 6 Weight gain, percent, after rinsing and drying 18. 8 23. 0 Char length, inches (vertical flame test):

Before laundering- 4. 5 3. 3

After 10 launderings 4. 5 3. 0

After 25 launderings 4. 5 4. 5

Based on char lengths in the vertical flame tests, particularly after numerous launderings, polyethylene glycol monooleate is comparable in effectiveness with tris(2,3- dibromopropyl) phosphate, a commonly used brominated additive to augment the flame retardancy of such blends. Moreover, when polyethylene glycol 1500 monooleate was used, the weight gain (after rinsing and drying) was 18.8%, definitely less than the weight gain of 23.0% when tris(2,3-dibromopropyl) phosphate was used. Inasmuch as polyethylene glycol 1500 monooleate is a nonreactive additive, it is not insolubilized on the fibers.

It will be apparent that many modifications and variations may be effected without departing from the scope of the novel concepts of the present invention, and the illustrative details disclosed are not to be construed as Nevertheless it significantly assists in rendering both fiber imposing undue limitations on the invention. components flame retardant in the fabric. We claim: 1

1. A process for treating cellulose-p0 yester blended EXAMPLE fabric to render said fabric flame retardant, said process This example illustrates wet fixation of bound nitrogen in the pretreatment step, and insolubilization of bound 10 (a) ilepregnatmg, said fabnc with componel, A phosphorus-nitrogen by ammonia in the next step. Rnsmg 'elkls(hydroxymethyl)phosphomum chlo- The fabric used was 50-50 polyester-cotton sheeting in nde and ,urea or 9 of these Feactams a plain Weave Weighing 357 Ounces per Square yard, and forming on said fabric an insoluble reaction prodand having a thread count (warp by filling) of 101 by form coqlponeflt A; 81 per inch. Samples were padded with an aqueous soluunpregnatmg sald fflbnc wlthfi f' f denva' tion of trimethylolmelamine (28% hydrogen peroxide five Prepared by reactmg melamme wlth form (0.3%), and polyethylene glycol 1500 monooleate aIdFhYde P fiormalqehyde and j p Sald The pressure of the pad rolls was adjusted to amine derivative having attached to its mtrogen atoms give a wet pickup of 71 to 74%. The padded sample was from to 6 Substltuents of the formula CH2OZ partially dried and subjected to wet fixation as described wherem in Example 4. Next, another step was carried out to add Z 15 hydrogen CH3 bound Phosphorus and additional bound nitrogen I11 and forming an insoluble product on the fabric from Order to accomplish this. the sample Was padded with a said melamine derivative while maintaining the mois- Precondensate 0f tetlakis y y y )P osphonium ture content of said fabric at a minimum of 2 0% by Chloride and urea ratio y moles), namfily y weight based on the weight of said fabric, and dimethylene)bis[iris(hydroxymethyl)PhOSPhOIIiI-Im] (0) impregnating said fabric with a polyethylene glychloride. (The pad bath was at pH 2.2.) The sample was 1 ester of h formula A( CH CH QA' partially dried and then exposed to ammonia vapor for h i 10 minutes at PP y NeXt, the Sample was A is an acyl group derived from an aliphatic monorinsed by the multiple IlIlSlIlg PIOCfidllI described ill carboxylic acid of from 8 24 carbon atoms; Example 4. Results are in the accompanying table. A is hydrogen or an acyl group derived from an TABLE FOR EXAMP 1 aliphatic monocarboxylic acid of from 8-24 carbon atoms, and m is an integer of from 4 to 80, percent from TMM Pretreatment said polyethylene glycol ester being impregnated into said 2:1.THPQmma precondsnsate Percent E fabric prior to the insolubilization of said melamine WFIght Percent after.was.hlng and drymg 109 derivative, in an amount sufficient to reduce the stiffness stlflness 'f (warp ,ilrectlon) 890 of the treated fabric and said fabric being dried after the Char length Inches (Vemcal Flama Test): insolubilization of the melamine derivative in the presence Before laundering 4.4 40 of moisture After 10 laundemfgs 2. A process as claimed in claim 1 wherein said compo- ,A 25 laundermgs nent A and said melamine derivative are simultaneously Semlclrcular Flame Seconds (angle): 0 insolubilized while maintaining the moisture content of Before laundermg 5 (30 said fabric at a minimum of 20 percent by weight based After 10 launderings 5 (30:) on the Weight of said fabric. After 25 laundenngs 25 (20 3. A process as claimed in claim 1 wherein said component A is insolubilized on said fabric prior to impregnat- EXAMPLE 11 ing said fabric with said melamine derivative and said This is a variation of Example 5 in which the reactive polyfifllylene glycol @8023 derivative of melamine is different. A pr s d clam r sald Example 5 is epeatgd with the exception that trimethamine der vative is insolubilized on said fabric in the pres ylolmelamine is replaced by a melamine-formaldehyde @Ilce Q saldpolyethylene glycol P to lmpregnat' reaction product made from substantially 6 moles of form- 3 Sald fabrlc Wlth Q P Q aldehyde and 3 moles of methanol per mole of melamine. A Pf as clalmed 111 01mm 1 f Sald p The result is that a desirable degree of durable flame renent A a precofldensate 0f y y y tardance is imparted to the suiting fabric. Phosphomum chlondefmd urea- 6. A process as claimed in cla1m 1 wherein said mel- EXAMPLE 12 amine derivative is trimethylolmelamine.

7. A process as claimed in claim 1 wherein said poly- The procedure of Example 5 was repeated using as the ethylene glycol ester is polyethylene glycol monooleate. fabric a series of polyester-cotton sheet fabrics having 8. A process as claimed in claim 1 wherein said meldifferent polyester to cotton ratios. The results are given amine derivative is insolubilized on said fabric by conin the following table. i tacting the fabric with steam.

TABLE FOR EXAMPLE 12 THPC: Urea TMM, PEG 1500 Percent Oharlength Polyester-cotton precondensate, percent monooleate, Weight sheeting percent OWF OWF percent OWF gain Orig. 10L 25L After rinsing and drying.

9. A process as claimed in claim 1 wherein said component A is a precondensate of tetrakis (hydroxymethyl) phosphonium chloride and urea, said methylol derivative is trimethylolmelamine and said polyethylene glycol ester is polyethylene glycol monooleate.

10. A process as claimed in claim 8 wherein said component A is a precondensate of tetrakis(hydroxymethyl) phosphonium chloride and urea, said methylol derivative is trimethylolmelamine and said polyethylene glycol ester is polyethylene glycol monooleate.

11. A flame retardant cellulose-polyester blended fabric produced by the process of claim 1.

References Cited UNITED STATES PATENTS 3,268,915 8/1966 WarnOck et al. 117-143 UX 14 3,059,990 10/1962 Koenig et al. 117-63 UX 2,774,687 12/1956 Nottebohm et al. 117-120 3,310,420 3/1967 Wagner 117-136 X 2,812,311 11/1957 Reeves et a1 17-136 X 3,101,278 8/1963 Wagner et al 117-136 X 3,247,015 4/1966 Zimmerman et al. 117-136 X OTHER REFERENCES Barber et al., American Dyestuff Reporter, A Study of Fire Retardancy pp. 40-44, vol. 57, May 1968.

WILLIAM D. MARTIN, Primary Examiner H. I. GWINNELL, Assistant Examiner US. Cl. X.R.

117-62, 138.8 F, 139.5 A, 143 A