US3920391A - Flame-retardant textiles by reaction of cellulose with the adduct of phosphorus trichloride and N,N-dimethylformamide - Google Patents

Abstract

The preparation in textile form of a cellulose N,Ndimethylorthoformamoylphosphorochloridite ester possessing flame and wrinkle resistance is described. The preparation is accomplished by preswelling the cellulose for 1 to 60 minutes in N,N-dimethylformamide, followed by reaction of the cellulose with 1-30% concentrations of phosphorus trichloride-N,Ndimethylformamide adduct in excess N,N-dimethylformamide as solvent, with or without an inert diluent, at 20-60* C for 1 to 180 minutes. After the reaction has been carried out to the desired extent of completion the modified cellulose is washed with an inert solvent. The modified cellulose contains nitrogen, phosphorus, and chlorine in a ratio of 1:1:1. If desired, the product can be freed of chlorine by subsequent washing in ice water, or may be used directly as an intermediate for further modification.

Description

v United States Patent [191 Vigo et a1.

[4 1 Nov. 18,1975

[75] Inventors: Tyrone L. Vigo, Kenner; Clark M.

Welch, Metairie, both of La.; Anna M. Collins, College Park, Ga.

[73] Assignee: The United States of America as represented by the Secretary of Agriculture, Washington, DC.

[22] Filed: Jan. 28, 1974 [21] Appl. No.: 437,096

[52] US. Cl. 8/188; 8/116 P; 260/219 [51] Int. Cl. D06M 13/46 [58] Field of Search 8/116 P, 188

Vigo et a1., -Reaction of Cellulose with PCL DMF Adduct, Journal of Applied Polymer Science, Vol. 17, No. 2, pp. 571-584 (1973), registered publication date of Mar. 13, 1973.

Primary Examiner-Murray Tillman Assistant Examiner-Arthur H. Koeckert Attorney, Agent, or FirmM. Howard Silverstein; Max D. Hensley ABSIRACT The preparation in textile form of a cellulose N,N- dimethylorthoformamoylphosphorochloridite ester possessing flame and wrinkle resistance is described. The preparation is accomplished by preswelling the cellulose for 1 to 60 minutes in N,N-dimethylformamide, followed by reaction of the cellulose with l-30% concentrations of phosphorus trichloride-N,N-dimethylformamide adduct in excess N,N-dimethylformamide as solvent, with or without an inert diluent, at 20-60C for 1 to 180 minutes. After the reaction has been carried out to the desired extent of completion the modified cellulose is washed with an inert solvent. The modified cellulose contains nitrogen, phosphorus, and chlorine in a ratio of 11111. If desired, the product can be freed of chlorine by subsequent washing in ice water, or may be used directly as an intermediate for further modification.

8 Claims, No Drawings FLAME-RETARDANT TEXTILES BY REACTION OF CELLULOSE WITH THE ADDUCT F PHOSPI-IORUS TRICI-ILORIDE AND N,N-DlMETI-IYLFORMAMIDE This invention relates to a method of imparting flame and wrinkle resistance to cellulosic textile materials by reaction of the cellulose with anadduct which phosphorus trichloride forms with N,N-dimethylformamide.

More specifically, the present inventionrelates to the conversion of fibrous cellulose in the form of yarn or.

fabric into phosphorus-, nitrogen-, and halogen-containing cellulosic textiles having flame resistance and improved wrinkle recovery, by reaction of the cellulose with phosphorus trichloride-N,N-dimethylformamide adduct in aprotic solvents.

The main object of the present invention is to impart flame resistance to cellulosic textiles by chemical modification of the cellulose by means of a phosphorus trichloride adduct with N,N-dimethylformamide.

A second object of the present invention is to provide a means of introducing a limited degree of cellulose crosslinking in cellulosic fabrics, so as to impart increased wrinkle resistance in the wet and dry states.

A third object of the present invention is to :provide ameans of introducing phosphorus,- and nitrogen-containing substituents, as well as chlorine, into fibrous.

of the original un-- of the prior processes depend for their effectiveness on:

bringing the cellulose derivative into solution so as to facilitate reaction with phosphorus trichloride. For example, in U.S. Pat. No. 2,489,225 (Nov. 22,

1949), phosphorus trichloride is reaotedwith soluble cellulose ether orester derivatives: The degree of;'sub-- stitution of the modified cellulose ether or ester isthat I necessary to render the cellulosic material. soluble in organic solvents or in phosphorus trichloride. Such a.

process is not suitable for treatment of native cellulose when it is .desired to retain the fiber, yarn of fabric structure which the cellulose originally possesses. Likewise, recent work by Dimitrov, et al. (Cellulose Chem.

Technol, 1968, 2(4), 375-389) describes the reaction of phosphorus trichloride with a cellulosic derivative (5,6-celluloseen) in which'an olefinic group must be present in order for the cellulose to react with the phosphorus trichloride. The phosphorus halide adds across the olefinic double bond in this instance.

The present invention makes it possible for the first time to react phosphorus trichloride with unsubstituted permits retention of the original fiber, yarn and fabric structure by the cellulosic textile.

Another major advantage ofthe present process over prior art is that it simultaneously introduces, in a onestep process, nitrogen as well as phosphorus into the cellulose, and in doing so, produces a product having high flame resistance as well as improved wrinkle recovery It is well known that nitrogen and phosphorus have a synergistic effect in imparting flame retardancy to cellulose.

A further advantage of the present process is that pretreatment of the cellulose with 'N,Ndimethylformamide activates the cellulose, and greatly increases its rate' of reaction towards the phosphorus trichloride- N;N-dimethylformamide adduct. Such an increase is essential to obtain the high phosphorus and nitrogen contents necessary in the cellulosic product for adequate flame and. wrinkle resistance. Other advantages will becomeapparent inthe description that follows.

The processes of this invention are applicable to cellulosederived from cotton or wood pulp, whieh cellulose may benative, mercerized, or regenerated, and which may be in the form of loose fibers, silver. yarn or fabric.

The above advantages of the present invention are unexpectedly obtained by .using a phosphorus trichloride adduct with.N,N-dirnethylformamide in the treatment of cellulose.

The phosphorus-trichloride adduct with'N,N-dimethylformamide is formed by reaction of phosphorus trichloride with -N,N-dimethylformamide at O30C in the absence of air and moisture. The reaction is nearly instantaneous, andzmay becarried out using excess 1 N,N-dimethylformamide as both'reactant and solvent,

or may beJcarried outas described in the literature IT. D. Smith, J. Chem.'.Soc.,'841 (1966)] using an inert diluent such as carbon tetrachloride. The mole ratio of phosphorus trichloride to N,N-dimethylformamide in the adduct is known to be 1:2. The structure of the adduct has previously been established by Smith as Cl-F'.[.OClrl=l I(Cl'l 2C1.

lncarrying out the processes of the present inven tion, the l:2 adduct of phosphorus trichloride with dimethylformamide does not need to be isolated or purified, but can be used directly as formed in solution in excess dimethylformamide, with or without other diluents present. The presence of excess dimethylformamide minimizes cellulose degradation and tendering during reaction of the adduct with the cellulose, and is therefore preferred. The reaction between cellulose and the adduct is thought to proceedas follows:

-continued C1 C1 O-Cell where Cell-OH is a portion ofa molecular chain of celdrying, prior to immersion in the N,N-dimethylforma lulose and R is a methyl group. The product, herein remide. ferred to as a cellulose N,N-dimethylorthoformamoyl- Removal of excess N,N-dimethylformamide or other phosphorochloriditc ester, is found to contain phostertiary amides in step (b) above, may be accomplished phorus, nitrogen, and chlorine in an atomic ratio of by ordinary mechanical methods of wringing, such as 111:]. Subsequent treatment with water produces the passing the fabric through squeeze rolls, centrifugation, following reactions: draining, or by pressing the cellulose against a filter.

The relative proportions of nitrogen and chlorine lost The reaction of the cellulosic textile with the adduct depends on the relative extent to which these hydroof phosphorus trichloride and N,N-dimethylformamide lytic reactions are carried to completion. Formation of 25 as specified in step (0) above, in preferably carried out a labile formate derivative during hydrolysis is indiin N,N-dimethylformamide as the reaction solvent, cated by increased infrared absorption at 5.75-5.85 since this solvent maintains the cellulose in a swollen mp characteristic of the carbonyl group in formates. state; and since the above adduct has considerably sol- The treatment of cellulose by the processes of the ubility in this medium. At concentrations above by present invention comprises the following steps: 30 weight of N,N-dimethylformamide-phosphorus trichloa. immersion of air-equilibrated, fibrous cellulose in ride adduct, it is necessary to use an inert diluent such textile form in N,N-dimethylformamide at a temperaas chloroform, methylene chloride, carbon tetrachloture of about from C to C for a period of from I ride, or perchloroethylene, as part of the solvent system minute to 60 minutes to swell the fibers, to insure solubility of the adduct before it is reacted b. removal of excess N,N-dimethylformamide from with the cellulose. the swollen cellulose. The weight ratio of the phosphorus trichloride-amide c. immersion of the cellulosic textile in a solution adduct to cellulose which may be used can be varied containing about from 1% to 30% by weight of the 1:2 over a wide range. The most practical ratio to use deadduct of phosphorus trichloride with N,N-dimethylpends to some extent on whether the cellulose is in the formamide together with an inert aprotic diluent seform of loose fibers, silver, yarn or fabric, since the relected from the class consisting of chloroform, carbon activity of the cellulose varies with the form of cellulose tetrachloride, methylene chloride and perchloroethylbeing treated. The preferred ratio also varies with the ene at a temperature of from 20C to 60C for about degree of flame resistance and improvement in wrinkle from 1 minute to 180 minutes, in order to obtain reacrecovery desired in the cellulose, but usually is in extion of the cellulose with the adduct, ce ss of 1 part by weight of the adduct to 5 parts by d. washing the cellulosic textile with N,N-dimethylweight of the cellulose. The concentration of the phosformamide to remove unreacted adduct, phorus trichloride-amide adduct may be varied conside. washing the cellulosic textile with an 'inert solvent erably, but above a concentration of 30% by weight, selected from the group consisting of benzene and the reactions with cellulose slows down considerably, chloroform, to remove N,N-dimethylformamide, and little practical benefit results from the use of higher f. washing the cellulosic textile with ice water. and ratios. then washing at room temperature with water contain- By adjusting the phosphorus trichloride-amide ading 0-10% acetic acid, to remove traces of combined duct concentration and the reaction time, the extent of chlorine and reagent and solvents, and reaction of the adduct with the cellulose can be varied g. drying the textile. considerably, so that the phosphorus contentobtained The immersion of the cellulose in N,N-dimethylforin the modified cellulose is in the range of 0.6% to 6%, mamide, as specified in step (a) above, is critical to the the nitrogen content is in the range of 0.1% to 2.5%, process, in that this step swells the cellulose fibers and and the chlorine content is in the range of 0.1% to 6%. greatly increases the rate of subsequent reaction of the Step (d) removes the unreacted phosphorus tricellulose with the adduct of phosphorus trichloride and chlorideamide adduct. Step (e) removes N,N-dimethyl- N,N-dimethylformamide. The cellulose to be used in formamide. Step (e) can be omitted when the modified this process should be at equilibrium with the atmocellulose is to be water-washed as in step (j). Washing sphere at ordinary humidity so that the moisture constep (j) is omitted when it is desired to maintain the tent causes the fibers to be much more accessible to PCl bond in the modified cellulose for further reacswelling by N,Ndimethylformarnide and to subsequent tion with other substrates. The cellulose N,N-dimereaction with the adduct of phosphorus trichloride and thylorthoformamoylphosphorochloridite ester ob- N,N-dimethylformamide. The cellulose should not be tained can be reacted with active hydrogen compounds subjected to any deswelling treatment such as ovensuch as amines, alcohols, and mercaptans to yield other derivatives of cellulose in textile forma During the wash with ice water, partial hydrolysis occurs as already indicated in the above equations, and most of the combined chlorine in the product is removed. A portion of the combined nitrogen in the product is also lost in this washing step. The wash with ice water is preferably followed by a wash with l aqueous acetic acid when the adduct concentration used in treating the cellulose is 10% or less. The acetic acid decreases the binding of metal ions present in the wash water by the substituted cellulose, and thus renders the flame retardancy more durableto washing.

1n the examples that follow, fabric breaking strength (strip method) was determined by the procedure of ASTM-Dl682-64, using a Scott tester. Wrinkle recovery was determined by the Monsanto method (ASTM D-l295-67). Flame resistance was measured by the standard vertical flame test described in US. Federal Supply Service, Textile Test Methods,.F'ederal Test Method Std. No. 191, Method 5903.1, and by the match or clock test described by Reeves, et al. [Text. Res. J. 23, 527-532 (1953)]. Durability to laundering of the treated fabrics was determined by repeated washing and drying in an agitator-type washer and a tumble dryer under normal conditions for cotton (10 minutes hot water wash, 30 minutes high temperature drying) using a commercial phosphate detergent. All parts and percentages are by weight. The phosphorus trichloride-amide adduct concentrations specified are based on the 1:2 adduct of phosphorus trichloride with the amide, and in the cases where N,N-dimethylformamide is the amide used, the adduct concentration specified is 2.07 times the percentage by weight of phosphorus trichloride added in making up the treating solution. The cotton cloth used for fabric treatments was desized, scoured, and bleached sateen weighing 8 oz. per sq. yd. N,N-dimethylformamide is hereafter abbreviated DMF.

EXAMPLE 1 Reaction of Cotton Fabric with Phosphorus Trichloride-DMF Adduct in DMF at Low Adduct Concentrations Desized, scoured, and bleached 8 oz./yd. cotton sateen fabric was immersed in excess N,N-dimethylformamide (DMF) for 30 minutes at 25C, put through laboratory wringers to remove excess DMF, and then reacted for minutes at 25C with 5% phosphorus trichloride-DMF adduct in DMF in a stoppered flask with agitation, utilizing 40 grams of solution per gram of cotton. This solution was prepared by adding 2.4 parts of phosphorus trichloride to 97.6 parts by weight of DMF. The fabric was subsequently washed three times with excess DMF, then with ice water, immersed in 5% aqueous acetic acid for 10 minutes, washed with tap water for 1 minute, and allowed to air-dry to constant weight. The resultant fabric had an add-on of 9.8%, and the following elemental composition: %P, 1.8; %N, 0.6; %Cl, 0.02; %Ca, 0.02. The fabric had a char length of 3.75 inches as measured by the standard vertical flame test and possessed no afterglow; untreated sateen fabric had extensive afterglow, very little char, and burned the entire fabric length (10 inches) under comparable test conditions. The breaking strength of the treated fabric was 90 lbs. while that of the untreated fabric was 137 lbs. The conditioned and wet wrinkle recoveries (warp fill) of the treated fabric were respectively 215 and 222, while those of the untreated fabric were respectively 183 and 168. Fibers of the treated fabric were insoluble in 0.5 M aqueous cupriethylenediamine solution, even after 10 minutes standing, whereas fibers of untreated fabric dissolved within 15-30 seconds. This shows that the treated cotton cellulose was highly crosslinked. The cellulose crosslinking imparted by the process of this invention was responsible for the wrinkle resistance imparted.

EXAMPLE 2 Reaction of Cotton Fabric with Phosphorus Trichloride-DMF in DMF at Intermediate Adduct Concentrations Cotton sateen fabric was immersed in excess DMF for 30 minutes at 25C, put through laboratory wringers to remove excess DMF, then reacted for 15 minutes at 25C with 15% phosphorus trichloride-DMF adduct in DMF in a stoppered flask with agitation, utilizing 40 grams of solution per'gram of cotton. This solution was prepared by adding 7.2 parts of phosphorus trichloride to 92.8 parts of DMF. The fabric was then washed three times with excess DMF, once with chloroform, and allowed to air-dry to constant weight. The resultant fabric had an add-on of 19.0%, a match test angle of 180, and the following elemental composition: %P, 2.8; %N, 1.1; Cl, 25; Ca, 0.01, and was suitable for further reaction utilizing the reactive PCl linkage. The atomic ratio of phosphorus, nitrogen, and chlorine in this product was 1.3: 1.1:1.0, or approximately 111:].

EXAMPLE 3 Reaction of Cotton Fabric with Phosphorus Trichloride-DMF in DMFCHCI at High Adduct Concentrations Cotton sateen fabric was immersed in excess DMF for 30 minutes at 25C, put through laboratory wringers to remove excess 'DMF, then reacted for 1 hour at 25C with 25% phosphorus trichloride-DMF adduct- 59% DMF-16% chloroform in a stoppered flask with agitation, utilizing. 40 grams of solution per gram of cotton. This solution was prepared by adding 12.1 parts of phosphorus trichloride to 87.9 parts of a 3.7:] mixture by weight of DMF and chloroform. The fabric was then washed with excess DMF, ice water, and tap water in excess for 30 minutes, and allowed to air-dry overnight. The resultant fabric possessed 3.9% P, 0.6% N, 0.3% Ca, and 0.4% Cl, and had a char length of 2.5 inches. Fibers of the treated fabrics were insoluble in 0.5 M cupriethylenediamine solution indicating the cellulose was highly crosslinked. After 20 standard home launderings (wash and tumble dry cycles) using a commercial phosphate detergent in the wash cycle, the fabric possessed 5.2% P, 0.3% N, 1.2% Ca, and 0.8% Cl, and still passed the standard vertical flame test with a char length of 3.5 inches.

EXAMPLE 4 Reaction of Cotton Fabric with Phosphorus Trichloride-DMF Adduct in DMF with Omission of Preswelling Step.

Cotton sateen fabric was immersed in 5% phosphorus trichloride-DMF in DMF for 15 minutes at 25C with agitation, utilizing 40 grams of solution per gram of cotton. This solution was prepared by adding 2.4 parts of phosphorus trichloride to 97.6 parts of DMF. The fabric was then washed with DMF, ice water, aqueous acetic acid for minutes, tap water for 1 minute, and allowed to air-dry. The resultant fabric had a weight gain of only 0.7%. and only 0.1% P, 0.05% N, with trace amounts of chlorine and calcium. Although the fabric possessed no afterglow, it had a 0 angle by the match test, and was therefore unsuitable for testing by the standard vertical flame test method. The results show that it is necessary to preswell the cellulose in DMF to obtain a useful degree of reaction by the processes of the present invention.

EXAMPLE 5 Reaction of Cotton Fabric with the Phosphorus Trichloride Adduct ofN,N-dimethylacetamide in DMF Cotton sateen fabric was immersed for 30 minutes in excess DMF, then put through wringers to remove excess DMF, then reacted with agitation in a stoppered flask containing 5% phosphorus trichloride-N,N-dimethylacetamide adduct dissolved in DMF, there being 40 grams of solution per gram of cotton. This reaction was run at C for 1 hr. The solution was prepared by adding 2.2 parts of phosphorus trichloride to 2.8 parts of N.N-dimethylacetamide with cooling to maintain a temperature not exceeding 50C. The resulting solution was dissolved in 95 parts of DMF. The resultant fabric was washed with DMF, ice water, tap water for minutes, and allowed to air-dry. The fabric, although having no afterglow when ignited, had a match test angle of 0, and was therefore not acceptable for further flammability testing. Elemental analysis of the fabric gave the following results: P--0.1, %N-0.15, Cl0.03, Ca-0.l3. Conducting the reaction using N,N-dimethylacetamide as the preswelling agent, and dissolving the adduct in N,N-dimethylacetamide gave comparable results. This example proves that N,N- dimethylacetamide cannot be used in place of DMF in the processes of the present invention.

EXAMPLE 6 Reaction of Cotton Fabric with Phosphorus Trichloride-N-Methylpyrrolidone Adduct in DMF Cotton sateen fabric was immersed for 30 minutes in excess DMF. and was then put through wringers to remove excess DMF. The fabric was immersed with agitation in a stoppered flask containing 5.9%- phosphorus trichloride-N-methylpyrrolidone adduct dissolved in DMF, there being grams of solution per gram of cotton. The reaction was run at 25C for 1 hr. The solution was prepared by adding 3.5 parts N-methylpyrrolidone to 2.4 parts of phosphorus trichloride with cooling, and later adding 94.1 parts of DMF. The resultant fabric was washed as in Example 1, and possessed only 0.1% phosphorus, and trace amounts of nitrogen, chlorine, and calcium. It had a match test angle of 0 and was therefore unacceptable for use as a flame-retardant fabric. Repeating the reaction using N-methylpyrrolidone in the preswelling step as' well as in the reaction gave comparable results. This example shows that N- methylpyrrolidone cannot be used in place of DMF in the processes of the present invention.

EXAMPLE 7 Reaction of Cotton Fabric with Phosphorus Tribromide-N,N-Dimethylformamide Adduct in DMF Cotton sateen fabric was immersed for 30 minutes in excess DMF, then put through wringers to remove excess DMF, and reacted with agitation in a stoppered flask containing 5% phosphorus tribromide-N,N-dimethylformamide adduct dissolved in DMF utilizing 40 grams of solution per gram of cotton. This solution was prepared by adding 3.2 parts of phosphorus tribromide to 96.8 parts of DMF. The reaction was run for 1 hr. at 25C. The resultant fabric was washed as in Example 1, and possessed 0.5% P, 0.2% N, 0.1% Br, and trace amounts of calcium. lt had a match test angle of 45, and therefore possessed some flame resistance, but not enough to be of practical benefit. The results show that phosphorus tribromide cannot be substituted for phosphorus trichloride in the processes of our invention.

EXAMPLE 8 Reaction of Cotton Yarn with Phosphorus Trichloride-N,N-Dimethylformamide Adduct in DMF Kiered 12/3 cotton yarn was immersed for 30 minutes in excess DMF, then centrifuged to remove excess DMF, and reacted with agitation in a stoppered flask containing 15% phosphorus trichloride-N.N-dimethylformamide adduct in DMF utilizing 40 grams of solution per gram of cotton. The reaction was run at 25C for 1 hr. This solution was prepared by adding 7.2'parts of phosphorus trichloride to 92.8 parts of DMF. The resultant yarn was washed as in Example 2, and possessed 3.9% P, 0.2% N, and 0.5% Cl. It had a match test angle of quite acceptable for a flame resistant cotton textile.

We claim:

1. A process for preparing a fibrous crosslinked N,N- dimethylorthoformamoylphosphorochloridite ester of cellulose in textile form, which ester is characterized by its containing nitrogen, phosphorus, and chlorine in a 1:1:1 atomic ratio, said process comprising:

a. immersion of a fibrous cellulose textile in N,N-

dimethylformamide at a temperature of about from 20C to 30C for a period of from 1 minute to 60 minutes to swell the fibers,

b. removal of excess N,N-dimethylformamide from the swollen cellulose,

c. immersion of the cellulosic textile in a solution containing about from 1% to 30% by weight of the 1:2 adduct of phosphorus trichloride with N,N- dimethylformamide, in a solvent containing 50%l00% N,N-dimethylformamide together with an inert aprotic diluent selected from the class consisting of chloroform, methylene chloride, carbon tetrachloride and perchloroethylene, at a temperature of from 20C to 60C for about from 1 minute to minutes, in order to obtain reaction of the cellulose with the aforesaid adduct,

d. washing the cellulosic textile with N,N-dimethylformamide to remove unreacted adduct,

e. washing the cellulosic textile with a solvent selected from the group consisting of benzene and chloroform, to remove the N,N-dimethylforma mide, and

f. drying the textile.

2. The process of claim 1 wherein the textile is in the form of a yarn.

3. The process of claim 1 wherein the textile is in the form of a fabric.

4. As a textile material, the fibrous crosslinked N,N- dimethylorthoformamoylphosphorochloridite ester of cellulose produced by the process of claim 1.

5. A process for preparing a fibrous, crosslinked, partially hydrolyzed N,N-dimethylorthoformamoylphosphite ester of cellulose in textile form, which ester is characterized by its nitrogen and phosphorus content, the absence of combined chlorine, and by its flame resistance and wrinkle resistance, said process comprising:

a. immersion of a fibrous cellulose textile in N,N-

dimethylformamide at a temperature of about from 20C to 30C for a period of from 1 minute to 60 minutes to swell the fibers,

b. removal of excess N,N-dimethylformamide from the swollen cellulose,

c. immersion of the cellulosic textile in a solution containing about from 1% to 30% by weight of the 1:2 adduct of phosphorus trichloride with N,N- dimethylformamide, in a solvent containing 50%l N,N-dimethylformamidetogether with an inert aprotic diluent selected from the class consisting of chloroform, methylene chloride, carbon tetrachloride, and perchloroethylene, at a tempe rature of from 20C to 60C for about from 1 minute to minutes, in order to obtain reaction of the cellulose with the aforesaid adduct,

d. washing the cellulosic textile with N,N-dimethylformamide to remove unreacted adduct.

e. washing the cellulosic textile with ice water and then washing at room temperature with water containing 040% acetic acid, to remove traces of reagents and solvents and combined chlorine, and

f. drying the textile.

6. The process of claim 5 wherein the textile is in the form of a yarn.

7. The process of claim 5 wherein the textile is in the form of a fabric.

8. As a textile material, the fibrous crosslinked partially hydrolyzed N,N-dimethylorthoformamoylphosphite ester of cellulose produced by the process of

Claims (8)

1. A PROCESS FOR PREPARING A FIBROUS CROSSLINKED N,N-DIMETHYLORTHOFORMAMOYLPHOSPHOROCHLORIDITE ESTER OF CELLULOSE IN TEXTILE FORM, WHICH ESTER IS CHARACTERIZED BY ITS CONTAINING NITROGEN, PHOSPHORUS, AND CHLORINE IN A 1:1:1 ATOMIC RATIO, SAID PROCESS COMPRISING: A. IMMERSION OF FIBROUS CELLULOSE TEXTTILE IN N,N-DIMETHYLFORMAMIDE AT A TEMPERATURE OF ABOUT FROM 20*C TO 30*C FOR A PERIOD OF FROM 1 MINUTE TO 60 MINUTES TI SWELL THE FIBERS, B. REMOVAL OF EXCESS N,N-DIMETHYLFORMAMIDE FROM THE SWOLLEN CELLULOSE, C. IMMERSION OF THE CELLULOSIC TEXTILE IN A SOLUTION CONTAINING ABOUT FROM 1% TO 30% BY WEIGHT OF THE 1:2 ADDUCT OF PHOSPHORUS TRICHLORIDE WITH N,N-DIMETHYLFORMAMIDE, IN A SOLVENT CONTAINING 50%-100% N,N-DIMETHYLFORMAMIDE TOGETHER WITH AN INERT APROTIC DILUENT SELECTED FROM THE CLASS CONSISTING OF CHLOROFORM, METHYLENE CHLORIDE, CARBON TETRACHLORIDE AND PERCHLOROETHYLENE, AT A TEMPERATURE OF FROM 20*C TO 60*C FOR ABOUT FROM 1 MINUTE TO 180 MINUTES, IN ORDER TO OBTAIN REACTION OF THE CELLULOSE WITH THE AFORESAID ADDUCT, D. WASHING THE CELLULOSIC TEXTILE WITH N,N-DIMETHYLFORMAMIDE TO REMOVE UNREACTED ADDUCT, E. WASHING THE CELLULOSIC TEXTILE WITH A SOLVENT SELECTED FROM THE GROUP CONSISTING OF BENZENE AND CHLOROFORM, TO REMOVE THE N,N-DIMETHYLFORMAMIDE, AND F. DRYING THE TEXTILE.

2. The process of claim 1 wherein the textile is in the form of a yarn.

3. The process of claim 1 wherein the textile is in the form of a fabric.

4. As a textile material, the fibrous crosslinked N,N-dimethylorthoformamoylphosphorochloridite ester of cellulose produced by the process of claim 1.

5. A process for preparing a fibrous, crosslinked, partially hydrolyzed N,N-dimethylorthoformamoylphosphite ester of cellulose in textile form, which ester is characterized by its nitrogen and phosphorus content, the absence of combined chlorine, and by its flame resistance and wrinkle resistance, said process comprising: a. immersion of a fibrous cellulose textile in N,N-dimethylformamide at a temperature of about from 20*C to 30*C for a period of from 1 minute to 60 minutes to swell the fibers, b. removal of excess N,N-dimethylformamide from the swollen cellulose, c. immersion of the cellulosic textile in a solution containing about from 1% to 30% by weight of the 1:2 adduct of phosphorus trichloride with N,N-dimethylformamide, in a solvent containing 50%-100%, N,N-dimethylformamide together with an inert aprotic diluent selected from the class consisting of chloroform, methylene chloride, carbon tetrachloride, and perchloroethylene, at a temperature of from 20*C to 60*C for about from 1 minute to 180 minutes, in order to obtain reaction of the cellulose with the aforesaid adduct, d. washing the cellulosic textile with N,N-dimethylformamide to remove unreacted adduct, e. washing the cellulosic textile with ice water and then washing at room temperature with water containing 0-10% acetic acid, to remove traces of reagents and solvents and combined chlorine, and f. drying the textile.

6. The process of claim 5 wherein the textile is in the form of a yarn.

7. The process of claim 5 wherein the textile is in the form of a fabric.

8. As a textile material, the fibrous crosslinked partially hydrolyzed N,N-dimethylorthoformamoylphosphite ester of cellulose produced by the process of claim 5.