AU603391B2

AU603391B2 - Flame-resistant cotton blend fabrics

Info

Publication number: AU603391B2
Application number: AU80716/87A
Authority: AU
Inventors: John H. Hansen; Peter J. Hauser; James R. Johnson; Chumpon Sujarit; Benny L. Triplett
Original assignee: Burlington Industries Inc
Current assignee: Burlington Industries Inc
Priority date: 1986-09-26
Filing date: 1987-09-25
Publication date: 1990-11-15
Anticipated expiration: 2007-09-25
Also published as: EP0325610A4; DK289288A; NO882310D0; NO882310L; WO1988002283A1; DE3789553D1; EP0325610A1; AU8071687A; NO173790C; JPH02500454A; EP0325610B1; DK289288D0; NO173790B

Description

a AU-AI 8 0716 8 7 Pr WORLD INTELLECTUAL PROPERTY ORGANIZATION International Bureau INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) (51) International Patent Cassification 4 (11) International Publication Number: WO 88/ 02283 3/02 Al (43) International Publication Date: 7 April 1988 (07.04.88) (21) International Application Number: PCT/US87/02432 (22) International Filing Date: 25 September 1987 (25.09.87) (31) Priority Application Numbers: 911,720 923,965 (32) Priority Dates: (33) Priority Country: 26 September 1986 (26.09.86) 28 October 1986 (28.10.86) (71) Applicant: BURLINGTON INDUSTRIES, INC. [US/ US]; 3330 West Friendly Avenue, Greensboro, NC 27420 (US).

(72) Inventors: HAUSER, Peter, J. 4 Holly Crest Court, Greensboro, NC 27410 TRIPLETT, Benny, L. 2416 Carlford Road, Pleasant Garden, NC 27313 SUJARIT, Chumpon 1202 Arrowhead Court, High Point, NC 27260 HANSEN, John, H. 5520 Guida Drive, Greensboro, NC 20410 (US).

JOHNSON, James, R. 1315 Easthurst Road, McLeansville, NC 27310 (US).

(74) Agent: CRAWFORD, Arthur, Nixon Vanderhye, 2000 N. 15th St. Suite 409, Arlington, VA 22201 (US).

(81) Designated States: AT (European patent), AU, BE (European patent), CH (European patent), DE (European patent), DK, FR (European patent), GB (European patent), IT (European patent), JP, LU (European patent), NL (European patent), NO, SE (European patent).

Published With international search report.

p. 9 MAY

AUSTRALIAN

2 1 APR1988 PATENT OFFICE (54) Title: FLAME-RESISTANT COTTON BLEND FABRICS (57) Abstract Polyester/cotton and nylon/cotton blends are rendered flame-resistant in single or a two step process in which a THP salt/prepolymer condensate of urea is applied, exposed to ammonia, then oxidized to form a polymer network in the cotton fibers, and a cyclic phosphonate ester or hexabromocyclododecane is applied to impart flame resistance to the nylon or polyester fibers. Flame-resistant cotton/synthetic blended fabrics having excellent hand and washfastness result.

This document contans the amendments made under Section 49 and is correct for printing.

p0 5 9, I PCT/US87102432 -14- WO 88/02283 SWO 88/02283 PCT/US87/02432 FLAME-RESISTANT COTTON BLEND FABRICS This invention relates to a process for imparting flame-retardant properties to cotton/synthetic fiber blends, specifically polyester/cotton and nylon/cotton blended fabrics, using two flame-r.tardant chemicals or flame-retardant systems, one specific to the synthetic component and the other specific to the cotton component.

BACKGROUND OF THE INVENTION Prior attempts to achieve acceptable flame-resistant polyester/cotton or nylon/cotton blends have not met with commercial success. None of the treatments is practical from the consumer point of view, producing fabrics that have a very stiff hand.

This is because in order to achieve the requisite flame-resistant properties, a high chemical add-on is required. This add-on makes the fabric stiff, masks the color of the underlying fabric, and often imparts an acrid or unacceptable odor to the fabric. In addition, the performance of the flame-resistant fabrics is often unreliable.

Most of the previous work conducted on flame-resistant polyester/cotton or nylon/cotton blends used a single chemical system that was targeted for the cotton component of the blend. The approach was to "load" the fabrics with a flame retardant specific for cotton, for instance THPS [tetrakis-(hydroxymethyl)phosphonium sulfate]. It was not unusual with these earlier products to use from 30 to 35% of fixed i WO 88/02283

-IS-

PCT/US87/02432 WO 88/02283 PCT/US87/02432 chemical add-on in order for the polyester/cotton or nylon/cotton blend ,fabric to" pass a -bottom vertical flame test. Regrettably, however, the aesthetics of the finished fabrics were poor, as they has a very stiff hand and the appearance of a coated fabric. The add-ons used for these product.s were far in excess of the theoretically required amounts.

When THPS is applied to a polyester/cotton or nylon/cotton blend, a degree of flame resistance results, but it remains stiff and generally unacceptable. Since the THPS is specific to cotton, it :doe.s not react with the polyester or nyl.on content of the fabric but simply physically coats the synthetic component. As a result, after multiple launderings, that portion of the flame retardant surrounding the polyester or nylon fiber is partially lost. In consequence, it was not unusual to use as much as phosphorus add-on for a polyester/cotton blend, at least initially, in order to result in the target 3% of fixed.phosphorus after 50 launderings in hot water.

In the 1970's, polyester/cotton blends were flame retarded using tris-2,3-dibromopropyl phosphate ("Tris") in combination with THPS. However, "Tris" was found to be a carcinogen and was withdrawn from the market, so that there is no predominantly-polyester blend 'of polyester and -cotton sold todaytthat 'has been treated with flame-retardant chemicals. An object of the present invention is to produce acceptable flame-resistant polyester/cotton and nylon/cotton blends using multiple flame-retardant chemicals or ,chemical systems, and .to .emp ly processing conditions i Ir I; I i' WO 88/02283 PCT/US87/02432 or adjuvants that produce a commercially acceptable, attractive product having good color and acceptable hand.

BRIEF DESCRIPTION OF THE INVENTION The process of the present invention employs two flame-retardant (FR) systems, one specific to the synthetic component and the other specific to the cotton component of the synthetic/cotton blends being flame-retarded. With this approach, the amount of flame retardant, such as THPS, required to satisfy flame-resistance standards can be reduced significantly and the resulting fabrics have not only better flame resistance, but also better aesthetics. In the processes disclosed in more detail below, different flame-retardant chemicals are applied together in a single step, or in separate processing steps.

Processing conditions, espec.ally temperatures and humidities, are carefully controlled in order to optimize the use of the flame-retardant chemicals and to ensure good fixation to the synthetic/cotton blends, even after several launderings.

The polyester/cotton blends treated in accordance with the present invention contain between 35% and of polyester, the balance being cotton. The nylon/cotton blends contain between 10% and 65% nylon or, when a single treatment step is used, from 3% to nylon, preferably frcn 35 to 55% nylon.

The term "polyester" is used in its usual sense to mean highly polymeric, essentially linear polyester WO 88/02283 PCT/US87/02432 resins made by the reaction of a dicarboxylic acid or ester with a diol din the presence of: an esterification or ester interchange catalyst. Illustrative dicarboxylic acids are malonic, succinic, adipic, azelaic, maleic, fumaric, hydromuconic, isophthalic, terephthalic, and cyclohexane-dicarboxylic acids.

Representative diols are ethylene glycol, propylene glycol, butylene glycol and 1,6-hexanediol. See U.S.

2,465,319 and U.S. 2,901,446. The common commercial polyester resins are polyethylene terephthalate and polyethylene terephthalate modified by inclusion of minor proportions of'a different glycol or dicarboxylic aci.d ,during the .polyesterificat.ion .process. The polyester used in the working examples that follow was polyethylene terephthalate.

As used in this specification, the term "nylon" is used to describe a manufactured fiber in which the fiber-forming substances are long-chain synthetic polyamides having recurring polyamide groups (-CONH-) as an integral part of the polymer chain. These polyamides .are formed from vari.ous conibinations kof diacids, diamines and amino acids. See generally Kirk-Othmer Encyclopedia of Chemical Technology, Vol.

16 (Interscience, New York, 2nd. ed., 1968) pp. 1-105.

The polyester/cotton and nylon/cotton fibrous 'materiaIs which'can.b.e;,proVi.jded with ,a flame-retardant finish according to the invention can be in any desired stage oIf processing, they can be treated as woven or knitted fabrics, dyed or undyed, or as textiles which have already been further processed.

r WO 88/02283 PCT/US87/02432 DETAILED DESCRIPTION OF THE .INVENTION Flame-resistant properties are imparted to the fabric in two distinct steps, one for the cotton component and the other for the synthetic (polyester or nylon) component. The order in which these steps are conducted is not critical; good results can be obtained when the cotton component of the blend is treated either first or second. .Alternatively, a mixture of two or more flame retardants is applied, one specific for the synthetic component of the blend and the other specific for the cotton component of the blend, in a single bath or processing step. With this in mind, the specific procedures of this process are now described.

I. Treating the Cotton Component of the Synthetic/Cotton Blend. Flame-resistant properties are imparted to the cotton component of the synthetic/cotton blend by impregnating the fabric with an aqueous solution containing a pre-condensate of a carefully measured quantity of urea [NH 2

CONH

2 and a tetrakis-(hydroxymethyl)phosphonium salt, referred to as THP, as THPS when the salt is the sulfate

[(HOCH

2 4 P 2SO 4 or THPC when the salt is the chloride; the oxalate and phosphate salts are also known. The THP salt/urea precondensate is applied to the fabric and dried to a specific moisture level. It is then reacted on the fabric with ammonia, usually ammonia gas, under controlled conditions to form an ammoniated flame retardant which, in turn, is oxidized, usually with hydrogen peroxide, to form a three-dimensional flame retardant polymer network within the cotton fiber structure. This process WO 88/022833 -6" PCT/US87/02432 results in a fabric having a softer hand than other treatments, such as THPS/urea, .which tends to stay on the outside of the fibers and stiffen the fibers and is more susceptible to removal by repeated laundering.

Currently there are two THP-based flame retardant systems marketed for this typesof treatment. Pyroset TPO is a THPS/urea precondensate of tetrakis-(hydroxymethyl)phosphonium sulfate and urea available from American Cyanamid Co., while Retardol AC is a THPC/urea prepolymer condensate of tetrakis-(hydroxymethyl)phosphonium chloride and urea .avai.able from AlIbright lson.

The process of imparting flame resistance to 100% cotton fabrics using THPC/urea (Retardol AC) is known as the PROBAN process as licensed by Albright Wilson.

The THP salt/urea precondensate process itself is described in the following U.S. patents: 4,078,101; 4,145,463; 4,311,855 and 4,494,951, all to Albright Wilson. This process is considered effective and is 'widely promoted ;by 'at -ea:st -two *.companies .for imparting flame resistance to 100% cotton fabrics; it is not promoted nor advertised for polyester/cotton blends or nylon/cotton blends. The THP salt/urea precondensate process by itself is ineffective to adequately protect polyester/cotton blends containing 'more than .about -35 to 40% polyester.

II. Flame Retardant Treatments for Polyester and Nylon. One of the following flame retardants may be used for the polyester or nylon component of the blend. 'Hexabromocyclododecant is available as

I-.

r. WO 88/02283 PCT/US87/02432 from Great Lakes Chemical and as Saytex HBCD from the Ethyl Corporation. It is sold primarily for use as a flame retardant for plastics, in part because of its poor solubility in solvents commonly used for textile processing. Hexabromocyclododecane melts at about 182 0 C (3600 and, when applied as a dispersion to a polyester/cotton or nylon/cotton fabric at elevated temperatures above its melting point, then cooled, hexabromocyclododecane fuses to the fiber, imparting the requisite flame-resistant properties to the fibers of the polyester or nylon.

Another flame retardant material used in accordance with the present invention specific for the polyester or nylon component of the fabric is a thermally stable cyclic phosphonate ester prepared by reacting alkyl-halogen-free esters with a bicyclic phosphite. As a class, these cyclic phosphonate esters are represented by one of the formulas: O0 RCH 0 P OCH C "P-R where a is 0 or 1; b is O, 1 or 2, c is 1, 2 or 3 and a+b+c is 3; R and R' are the same or different and are alkyl (C 1 -C phenyl, halophenyl, hydroxyphenyl, tolyl, xylyl, benzyl, phenethyl, hydroxyethyl, phenoxyethyl, or dibromophenoxymethyl;

R

2 is alkyl (C and R 3 is lower alkyl (C 1

-C

4 or hydroxyalkyl

(C

1

-C

4 or WO098/02283 PCT/US87/02432 2 4 0 0 C H0~ 3 RB) 0CL R COC2

PR

(B d 2 CH 0 2 where d is 0, 1 or 2; e is 1, 2 or 3; R2 is alkyl 3 (C C4)R is lower alkyl (C 1

C

4 or hydroxyalkyl (C C),R 4 is alkyl (C C) phenyl, halophenyl, hydroxypheny'l, hydroxyethyl, phenoxyethyl, dibromophenoxymethyl, tolyl, xylyl, benzyl or phenethyl; and R5is monovalent alkyl (C I- C 6 chiorophenyl, bromophenyl, dibromophenyl, tribromophenyl, hydroxyphenyl, naphthyl, tolyl, xylyl, benzyl, or phenethyl; divalent alkylene (C 1 -C 6 viny1ene, ,.-o-phenylene,, !mI-phe~ny~lene,, p-phenylene, tetrachiorophenylene m, or tetrabromophenylene m, or or trivalent phenyl.

The preferred compounds are represented by the formula: CH CH 1 2 3 (C H 0) P-(QCH 2 C PCH 3 3 2-X i-CH 3 ClH 2 0 in which X is 0 or 1, and usually a 50:50 mixture of the mono- and di-esters. The preparation of these cyclic phosphonate esters and their use as flame retardants are described in U.S. 3,789,091 and 3,849,368, the disclosures of which are hereby incorporated- byre-ference.

111. Single Step Flamne Retardant Treatments.

A mixture of flame retardanits is applied, one member of the mixture specifi~c for cotton and the other -for ny'lon, ;after.-the f abric"I "The. -s'ame bath is WO 88/02283 PCT/US87/02432 used to apply a mixture of two (or more) flame-retardant chemicals, such as by padding onto the fabric with a fixed add-on typically in the range of 20-25% by weight. This combination pad bath is most effective for nylon/cotton blends containing from about to about 55% nylon and is not recommended for fabrics dyed with direct dyes or reactive dyes as they tend to change color. However, naphthols, acid dyes and cationic dyes are fully acceptable. The hand of fabrics so treated is substantially superior to the hand of any flame-resistant nylon/cotton fabrics heretofore known to the art. The hand can be further improved by the use of a softener such as Aerotex H Softener, a cationic product with nonionic and anionic moieties, manufactured by American Cyanamid Co.

The hand of the treated fabrics can be still further improved by conducting the curing operation in a moist, high-humidity environment.

Antiblaze 19T, as described by the supplier Albright Wilson Inc., of Richmond, Virginia, U.S.A., is a cyclic phosphonate ester, available as an odorless viscous liquid (viscosity 250 Pa.s) with a flashpoint of 171 0 C (340 0 F) (ASTM D-93).

Hexabromocyclododecane, as described by its supplier Great Lakes Chemical Corporation of West Lafayette, Indiana, is a cyclic alkyl bromide, empirical formula C 12

H

18 Br 6 CAS registry number 25637-99-4, composed of hexabromocyclododecane and related bromocycloalkanes. It is an odorless, water-insoluble, off-white powder having a melting

I

i_ WO 88/02283: -10- PCT/US87/02432 point range of 142-182 0 C (288-360 0 F) and is preferably used in the process ofthis invention as a dispersion in water or an aqueous pad bath system.

Tetrakis-(hydroxymethyl)phosphonium chloride/urea prepolymer condensate (THPC/urea) is available from Albright Wilson, Inc., under the name Retardol AC. A related chemical, THPS/urea prepolymer condensate, is available from American Cyanamid Co., under the name of Pyroset TPO.

Aerotex H is described by its supplier, American Cyanamid Co., as :a cationic -product with 'nonionic and anionic moieties, and is included in the pad bath formulation as a softener.

is ethoxylated 2,6,8-trimethylnonanol, commercially available from Union Carbide Corporation.

Flame Resistance Testing Methods the following testing procedure was used: FR Federal Test Method 5903 is intended for use in determining the resistance of cloth to flame and glow propagation and tendency to char. A rectangular cloth test specimen (70mm x 120mm) with the long dimension parallel to the warp or fill direction is placed in a holder and suspended vertica'ly. in a cabinet with the lower end 1.9 cm above the top of a Fisher gas burner.

A synthetic gas mixture consisting primarily of hydrogen and methane is supplied to the burner. After the specimen is mounted in the cabinet and the door closed, the burner flame is applied vertically at the d PC~/U~7tO243j 0 a1~ 2 WO 88/02283 -11middle of the lower edge of the specimen for 12 seconds. The specimen continues to flame after thburner is extinguished. The time in seconds the specimen continues to glow after the specimen ha$ ceased to flame is reported as afterglow time; if the specimen glows for more than 30 seconds, it is removed from the test cabinet, taking care not to fan the glow, and suspended in a draft-free area in the same vertical position as in the test cabinet. Char length, the distance (in centimeters) from the end of the specimen, which was exposed to the flame, to the end of a lengthwise tear through the center of the charred area to the highest peak in the charred area, is also measured. Five specimens from each sample are usually measured and the results averaged.

As used throughout this specification and the claims that follow, all parts and percentages are expressed by weight and all temperatures reported in degrees C, unless otherwise indicated. The inventio will be furhter illustrated with reference to the following examples: z 0 0

J

U

y ff o

II

P

4 WO 88/02283 -12- PCT/US87/02432 Example 1A Fabric style 9886 (50/50 nylon/cotton) was. padded to a wet pickup of 61% with Pyroset TPO (THPS-urea precondensate from American Cyanamid; see bath formula), and heated at 54 0 C for 48 seconds. The moisture content was found to be 15.5-16% as measured with a Mahlo meter. The fabric was equilibrated in a plastic bag for 1-2 hours. The fabric was then exposed to ammonia gas at 6:1 ammonia: phosphorus mole ratio.

Oxidation of the fabric by a hydrogen peroxide/sodium silicate solution followed. The amount of peroxide used was 5% on the weight of fabric. The sodium silic'ate wes-used 'to 'maintain a pH of 9-9.5. The fabric was rinsed and tumble dried.

Bath formula: Water 30.6% Aerosol C 61 wetting agent 0.2% Sodium acetate Pyroset TPO .68.7% The TPO/ammonia-treated style 9886 fabric was subsequently padded with a 15% Antiblaze 19 (Albright Wilson) solution, heated in an oven at 193 0 C for seconds and tested for flame resistance as prepared and ,after 25 -launderings.

FTM 5903 (Char Length) Fabric 0 Laund. 25 Laund.

.9886+,TP.O/ammonia+AB19 5 cm 11.4 cm 1 1 1..

9 i WO 88/02283 -13- PCT/US87/02432 Example 1B The TPO/ammonia-treated style 9886 fabric of Example 1A was also subsequently padded with a 15% dispersion of hexabromocyclododecane (HBCD), heated at 182 0 C (360 0

F)

for 45 seconds, and tested for flame resistance as prepared and after 25 launderings.

FTM 5903 (Char Length) Fabric O Laund. 25 Laund.

9886+TPO/ammonia+HBCD 7 cm. 7-7.6 cm.

None of the treated fabrics of Example 1A or 1B exhibited either afterflame or afterglow. The results show a high level of flame resistance, and the treated fabrics had satisfactory aesthetic properties.

Example 2 In experiments similar to Example 1, 65/35 polyester/cotton fabric, style 9798, and 40/60 polyester/cotton fabric, style 9496, were padded with Pyroset TPO; see bath formula. The fabrics were dried to 16-16.5% moisture content, as measured with a Mahlo meter. The fabrics were then exposed to ammonia gas at a >6:1 ammonia:phosphorus mole ratio. Oxidation of the fabric by a hydrogen peroxide/sodium silicate solution followed. The amount of peroxide used was 5% on the weight of fabric. The sodium silicate was used to maintain a pH of 9-9.5. The fabric was rinsed and tumble dried.

WO 88/02283 -14- WO 8802283-14-PCT/US87/02432 Bath Formula: Water Aerosol C '61 wett4,ng agent Aerotex H softener Sodium acetate Pyroset TPO 52 0.2% 0.3% 45 .0% Fabric 9798 9496 Wet Pick up 6 1% 63% Both TPO/amxnonia-treated fabrics were subsequently padded with a 15% dispersion of hexabromocyclododecane (HBCD), heated at 182 0 C (360 0 F) for 45 seconds, and tested for flame resistance as prepared and after launderings.

FTM 5903 (Char Length 0 Laund. 25 Laund. Fabric 9798+TPO/ammoni a+HBCD 9494+TPO/ammoni a+HBCD 6.3 cm.

5. 0 cm.

5. 6 cm.

5. 0 cm.

None of the samples tested exhibited either afterf lame or afterglow, and the low char lengths indicate a high level. of if lame !,residtancae. 7The ,t-.reated X-Ab.rIc. had a satisfactory hand and appearance.

Example '3

I

.7

I

f WO 88/02283 -15- PCT/US87/02432 A bath containing 50% of a tetrakis- (hydroxymethyl) phosphonium sulfate preparation (Retardol S from Albright Wilson), 15.7% urea, 9.3% cyclic phosphonateate ester (Antiblaze 19 from Albright Wilson), 2% disodium phosphate, 2% fabric softener (Aerotex H from American Cyanamid) and 0.1% nonionic surfactant was prepared. This bath was padded onto a dyed and printed nylon/cotton twill (ca. 55% nylon, 264 g/m2 Wet pickup was 61.5%. The fabric was dried and cured for 90 seconds in an oven at 182 0 C. The treated fabric was oxidized in a solution contaiing hydrogen peroxide and sodium hydroxide, rinsed well and dried.

Four samples of the fabric were tested in the manner described in Federal Test Method 5903. Average char length was 5.7 cm; none of the samples exhibited either afterflame or afterglow. Similar testing after the fabric had been subjected to 10 home launderings gave an average char length of 6.35 cm with no afterflame or afterglow. These results indicate that the treatment was highly effective in imparting flame resistance to the nylon/cotton fabric.

Example 4 In similar trials, two baths described as A and B below were padded onto dyed and printed nylon/cotton twill (55.8% nylon). The fabric samples were dried and cured for 75 seconds in an oven at 188°C. Oxidation and testing were done as described in the previous example.

I~

I

WO 88/02283 -16- PCT/US87/02432 THPS (Retardol S) 55.0 55.0 Urea 14.85 12.1 Antiblaze 19 9.3 9.3 Aerotex H 2.0 Surfactant 0.1 0.1 Wet Pick-up 63.4 62.4 Average Char Length As-finished 5.0 cm 4.8 cm 4Laundered 2.5 times .5.0 cm 5.3 cm The results show that the flame-retardant treatments were very effective, and the hand of the fabric was quite acceptable.

Example In similar trials, the baths described below were :padded onto two ,nylon/cotton fabrics. 'Eabri'c Awa s ,a 2 ripstop weave, 210 g/m 2.8% nylon. Fabric B was a twill, 179 g/m 2 53.1% nylon. The fabric samples were dried and cured for 60 seconds in an oven at 182 0

C.

Oxidation and testing were done as described in the previous example. Char is reported in cm, fails as the fraction of the number that failed over th- umbier of samples tested.

i 11 WO 88/02283 -17-" PCT/US87/02432 Bath .1 Retardol S urea Antiblaze 19 disodiun, phosphate Aerotex H surfactant (TMN-10) 30.0% 7.5 9.3 2.0 2.0 0.2 Bnth 40.0 10.0 9.3 2.0 2.0 0.2 B3a th 50.0 12.5 9.3 2.0 2.0 0.2 Bath 60.0 15.0 9.3 0.2 As -Finished Laundered 25 Times TM 5903 %Phos- Char Fails phorus Fabric Bath TM 5903 %Phos- Char Fails phorus 6.6 4.1 4.1 6.1 5.3 5.8 The treated fabric containing at least of phosphorus had excellent flame resistance and good aesthetic properties.

Claims

2. A process of imparting flame-resistance to a nylon/cotton blend fabric containing between 3% to nylon, the balance cotton, comprising the steps of: applying to a nylon/cotton blend fabric, at least 3% by weight of which is nylon, balance cotton, a flame retarding amount of cyclic phosphonate ester flame retardant that fixes onto nylon fibers together with a flame retarding amount of a tetrakis-(hydroxymethyl)phosphonium salt and urea that fixes onto cotton fibers, the flame retardant chemicals applied to the fabric simultaneously; and curing the fabric at elevated temperatures to N T Nt s'< 7 I 19 S a St 0 5* S. S -V fix the flame retardants to the nylon and to the cotton, oxidizing the fabric, rinsing it and drying it.
3. The process of claim 1, in which step is conducted prior to step
4. The process of claim 1, in which step is conducted prior to step The process of claim 1 or 2, in which the tetrakis-(hydroxymethyl)phosphonium salt is the chloride salt.
6. The process of claim 1 or 2, in which the tetrakis-(hydroxymethyl)phosphonium salt is the sulfate salt.
7. The process of claim 1 or 2, in which the tetrakis-(hydroxymethyl)phosphonium salt is the oxalate salt.
8. The process of claim 1 or 2, in which the tetrakis-(hydroxymethyl)phosphonium salt is the phosphate salt.
9. The process of claim 1 or 2, in which the cyclic phosphonate ester is represented by the formula: CH 2 CH 3 O CH20 0 SII 11 (CH 3 0)xP-(OCH 2 C PCH 3 2 .x CH 3 CH 2 O in which x is 0 or 1. The process of claim 1, in which the flame retardant in step is hexabromocyclododecane.
11. The process of claim 10, in which the hexabromocyclododecane is applied as an aqueous dispersion and is cured at a temperature of at least 182 0 C (360 0 F) to melt and fuse the hexabromocyclododecane to the polyester or nylon fibers.
12. The process of claim 1, in which the fabric is a polyester/cotton blend. i ""t"i I 20
13. The process of claim 11, in which the blend contains from 35% to 80% polyester, the balance being substantially cotton.
14. The process of claim 1 or 2, in which the fabric is a nylon/cotton blend. The process of claim 14, in which the blend contains from 10% to 65% nylon, the balance being substantially cotton.
16. The process of claim 15, in which the blend contains from 35% to 55% nylon, the balance being substantially S cotton. *17. The flame-resistant nylon/cotton blend fabric produced by the process of claim 1 or 2.
18. The flame-resistant polyester/cotton blend fabric produced by the process of claim 1. 0 1 0- *f* *I s ;i 1: -L= -3 INTERNATIONAL SEARCH REPORT International Application NoPCT US87 02 432 I. CLASSIFICATION OF SUBJECT MATTER (II several classification symbols apply, indicate all) Accoratig to International Patent Classification (IPC) or to both National Classificalion and IPC IPC 4 B05D 3/02 427/393.3,337,341; 8/195 II. FIELDS SEARCHED Minimum Documentation Searched Classification System j Classification Symbols U.S. 427/393.3, 337, 341; 8/195 Documentation Searched other than Minimum Documentation to the Extent that such Documents are Included in the Fields Searched a III. DOCUMENTS CONSIDERED TO SE RELEVANT 1i Category Citation of Document, I with indication, where appropriate, of the relevant passages I I Relevant to Claim No. 4 A US, A 4,166,897 PUBLISHED 04 SEPTEMBER 1979 (UMETANI ET AL) SEE ABSTRACT A US, A 4,448,817 PUBLISHED 15 MAY 1984 (BENISEK) A US, A 4,494,951 PUBLISHED 22 JANUARY 1985 (COLE ET AL) A US, A 3,974,310 PUBLISHED 10 AUGUST 1976 A US, A 3,897,584 PUBLISHED 29 JULY 1975 (SWIDLER) Special categoriea of cited documents: 14 later document published after the international filing date document defining the general state of the art hich is not or priority date and not in conflict with the application but considered to be of particular relevance cited to understand the principle or theory underlying the invention f"E" ier 'd umen but published on or after the nternatonl document of particular relevance; the claimed invention cannot be considered novel or cannot be considered to document which may throw doubts on priority claim(s) or involve an inventive step which Is cited to establsh the publication date of another document of particular relevance: the claimed nvention citation or other special rleson (As Specified) document of particular relevance; the claimed invention citon or oer special reon pcd) cannot be considered to involve an inventive step when the document referring to an oral disclosure, use, exhibition or document is combined with one or more other such docu. other means ments, such combination being obvious to a person skilled document published prior to the international filing date but in th art. inter than the priority date claimed document member of the same patent family IV. CERTIFICATION Date of the Actual Completion of the International Search 1 04 NOVEMBER 1987 Date of Mailing of this International Search Report I 0 4 DEC 1987 International Searching Authority i ISA/US Signature of Authorized Officer so LEON R. HORNE Form PCT/ISA/210 (econd shaet) (May 196)