Preparation Of Cellulose N,n-dimethylformimidate Chloride In Textile Form, And Conversion To Halogenodeoxycelluloses And Cellulose Formate

Abstract

The preparation in textile form of a new, flame resistant, chemically reactive cellulose derivative, cellulose N,N-dimethylformimidate chloride, is accomplished by reacting chlorodimethylformiminium chloride in N,N-dimethylformamide at 20.degree.-30.degree.C with cellulosic yarn or fabric preswollen in N,N-dimethylformamide. At a reaction temperature of 50.degree.-110.degree.C, the product is chlorodeoxycellulose. Conversion of cellulose N,N-dimethylformimidate chloride to iododeoxycellulose is accomplished by reaction of the former with an alkali metal iodide at 60.degree.-150.degree.C in N,N-dimethylformamide. Conversion of the cellulose N,N-dimethylformimidate chloride to cellulose formate occurs by contact with water at 20.degree.-30.degree.C. The chlorodeoxycellulose and iododeoxycellulose possess rot resistance and flame resistance. Cellulose formate has altered dyeability.

Government Interests

A non-exclusive, irrevocable, royalty-free license in the invention herein described, throughout the world for all purposes of the United States Government, with the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

Description

GENERAL FEATURES

This invention relates to a new cellulose derivative, its preparation in yarn and fabric form, and its conversion to other cellulose derivatives having useful textile properties. More specifically, the invention relates to the preparation, properties and reactions of cellulose N,N-dimethylformimidate chloride, which possesses the chemical structure ##SPC1##

Wherein Cell represents a portion of a cellulose molecular chain. Alternative names for this cellulose derivative are (celluloseoxymethylene) dimethylammonium chloride and cellulose N-methylformimidate methochloride. Also embodied in the present invention is the conversion of the above specified cellulose N,N-dimethylformimidate chloride to chlorodeoxycelluloses, iododeoxycelluloses, cellulose formate, and other useful cellulose derivatives in textile form.

OBJECTS OF THE INVENTION

The main object of the present invention is the preparation of a new and highly reactive cellulose derivative, cellulose N,N-dimethylformimidate chloride, having utility as an intermediate in the preparation of a variety of other cellulose derivatives.

A second object is to provide a means of reducing the flammability of cellulosic textiles.

A third object of the present invention is to provide a means of rendering cellulosic textiles resistant to rotting by microorganisms.

A fourth object is to provide a means of introducing halogen substituents into cellulose to yield chlorodeoxycellulose and iododeoxycellulose in textile form, while retaining the fiber structure, whiteness, and most of the tensile strength of the original cellulose.

A fifth object is to provide a means of introducing halogen subtituents into cellulose without prior application of alkali-swelling or solvent-exchange pretreatments to the cellulose. Other objects of the present invention will become evident in the description which follows.

COMPARISONS WITH PRIOR ART

The prior literature contains several studies on the preparation of chlorodeoxycellulose. Boehm, J. Organic Chem. 23, 1716-1720 (1958), added thionyl chloride to a mixture of alkaliswollen, solvent-exchanged cotton linters and pyridine. A strong degrading action on the cellulose was stated to occur as evidenced by the low viscosity of solutions of the product in cuprammonium hydroxide. The product also showed a dark discoloration.

Polyakov and Rogovin, J. Polymer Sci. (U.S.S.R.) 4 (4) 610-618 (1963), prepared chlorodeoxycellulose by reacting alkali-swollen, solvent-exchanged cotton linters at 60.degree.-98.degree.C with thionyl chloride in N,N-dimethylformamide. A yellow discoloration was noted in the product. The swollen linters required for this process were prepared by steeping the cotton in 18 percent aqueous sodium hydroxide, followed by washing with water, methanol, and then benzene. Subsequently, Vigo and Welch, Textile Research J. 40, 109-115 (1970), found that in the treatment of cotton yarn by the process of Polyakov and Rogovin, yellowing and tendering could be avoided by the use of lower reaction temperatures (25.degree.-30.degree.C), but no method was found of avoiding the laborious and expensive alkali-swelling and solvent-exchange steps required to activate the cotton cellulose.

In a subsequent patent application (Ser. No. 109,964), now U.S. Patent 3,698,857, it was disclosed by Vigo, Margavio, and Welch that the preswelling of cellulose, as required in the Polyakov and Rogovin process, can be carried out with water in place of aqueous alkali, if only a moderate chlorine content in the product is needed, but this process still necessitates solvent-exchange treatments to displace the water in the cellulose with an aprotic solvent inert to thionyl chloride. Moreover, the chlorine content obtainable in the product is less than 1 percent by this method.

The present invention makes it possible for the first time to prepare chlorodeoxycellulose in yarn and fabric form without prior application of alkali- or water-swelling treatments to the cellulose. The processes to be disclosed eliminate the need for solvent-exchange treatments prior to reaction. Moreover, the present invention permits the use of elevated reaction temperatures without cellulose discoloration or tendering, thus permitting higher chlorine contents to be introduced into the cellulose than are possible in processes conducted at room temperature. The processes of this invention are applicable to celluloses derived from cotton and wood pulp, which celluloses may be native, mercerized or regenerated, and which may be in the form of loose fibers, sliver, yarn or fabric.

DESCRIPTION OF THE INVENTION

The above advantages of the present invention are unexpectedly obtained by use of chlorodimethylformiminium chloride in place of thionyl chloride as the reagent employed to introduce the desired substituents into the cellulose. Chlorodimethylformiminium chloride, hereafter referred to as DMFCl.sub.2 for brevity, is readily prepared from thionyl chloride and N,N-dimethylformamide by the method of Bosshard et al., Helv. Chim. Acta 42, 1653-1658 (1959), and is known to possess the structure ClCH=N.sup.+(CH.sub.3).sub.2 Cl.sup.-.

DMFCl.sub.2 undergoes two types of reaction with cellulose. The low-temperature reaction, conducted at 20.degree.-30.degree.C, yields cellulose N,N-dimethylformimidate chloride:

1. Cell--OH + ClCH=N.sup.+(CH.sub.3).sub.2 Cl.sup.- .fwdarw. HCl + Cell-OCH=N.sup.+(CH.sub.3).sub.2 Cl.sup.-. The high temperature reaction of DMFCl.sub.2 with cellulose is conducted at 50.degree.-110.degree.C, and produces mainly chlorodeoxycellulose:

2. Cell--OH + ClCH=N.sup.+(CH.sub.3).sub.2 Cl.sup.- .fwdarw. HCl + Cell-Cl + O=CH-N(CH.sub.3).sub.2.

Thus the means are now available for the direct preparation of cellulose N,N-dimethylformimidate chloride and also of chlorodeoxycellulose.

Moreover, the cellulose N,N-dimethylformimidate chloride is highly reactive, and can be converted to iododeoxycellulose by treatment with an alkali metal iodide in N,N-dimethylformamide at 60.degree.-150.degree.C, as follows:

3. Cell--OCH=N.sup.+(CH.sub.3).sub.2 Cl.sup.- + KI .fwdarw. Cell-I + KCl + O=CH-N(CH.sub.3).sub.2.

Alternatively, the cellulose N,N-dimethylformimidate chloride can be reacted with water to yield cellulose formate:

4. Cell--OCH=N.sup.+(CH.sub.3).sub.2 Cl.sup.- + H.sub.2 O -- Cell-OCH=O + (CH.sub.3).sub.2 N.sup.+H.sub.2 Cl.sup.-.

Not only are chlorodeoxycellulose, iododeoxycellulose, and cellulose formate readily obtainable by the processes of this invention, but mixed derivatives of cellulose containing iodo and formyl substituents, chloro and formyl substituents, iodo and chloro substituents, or iodo, chloro, and formyl substituents on the same cellulose chains, are readily prepared by the proper sequence of treatments and choice of reaction temperatures and times.

Preparation of Cellulose N,N-Dimethylformimidate Chloride

The preparation of cellulose N,N-dimethylformimidate chloride by the present invention comprises the following steps:

a. immersing air-equilibrated, fibrous cellulose in textile form in N,N-dimethylformamide at a temperature of about from 20.degree.C to 30.degree.C for a period of from 1 to 60 minutes to swell the fibers,

b. removing excess N,N-dimethylformamide by wringing,

c. immersing the cellulosic textile in a mixture of about from 3 to 15 percent by weight DMFCl.sub.2 in N,N-dimethylformamide at a temperature of from 20.degree.C to 30.degree.C for about from 3 minutes to 180 minutes, in order to react the cellulose with the DMFCl.sub.2,

d. washing the cellulosic textile with N,N,dimethylformamide to remove excess DMFCl.sub.2,

e. washing the cellulosic textile with an inert, volatile, aprotic solvent miscible with N,N-dimethylformamide, and

f. drying the celulosic textile.

Immersing the cellulose in N,N-dimethylformamide prior to treatment with DMFCl.sub.2 solution, as specified in step (a) above, is critical to the process, in that this step swells the cellulose fibers and greatly increases the rate of subsequent reaction of the cellulose with the DMFCl.sub.2. The magnitude of this effect is surprising inasmuch as N,N-dimethylformamide is also present during the reaction and would be expected to exert the same effect then. The cellulose to be used in this process should be at equilibrium with the atmosphere at ordinary humidity so that the moisture content of the cellulose is of the order of 2-12 percent. The presence of this moisture renders the fibers much more accessible to swelling by N,N-dimethylformamide and to the subsequent reaction with DMFCl.sub.2. The cellulose should not be subjected to any deswelling treatment such as oven-drying, prior to immersion in the N,N-dimethyl formamide.

Removing excess N,N-dimethylformamide, in step (b) above may be accomplished by ordinary mechanical methods of wringing, such as passing the fabric through squeeze rolls, centrifugation, draining, or by pressing the cellulose against a filter.

The reaction of the cellulosic textile with DMFCl.sub.2, as specified in step (c) above, is preferably carried out in N,N-dimethylformamide as the reaction medium since this solvent maintains the cellulose in a swollen state, and also the DMFCl.sub.2 has considerable solubility in this medium. The weight ratio of DMFCl.sub.2 to cellulose which may be used can be varied over a wide range. The most practical ratio to use depends to some extent on whether the cellulose is in the form of loose fibers, sliver, yarn, or fabric, since the wet pickup of DMFCl.sub.2 -dimethylformamide mixture of the cellulose varies with the form of cellulose being treated. The preferred ratio also varies with the degree of cellulose substitution desired, but usually is in excess of 1 part by weight of DMFCl.sub.2 to 4 parts by weight of cellulose. The ratio of DMFCl.sub.2 to N,N-dimethylformamide also may be varied considerably but below a weight ratio of 0.03 of DMFCl.sub.2 / solvent, the reaction with cellulose becomes very slow, and above a weight ratio of 0.15 the solubility limit of DMFCl.sub.2 is exceeded to the extent that little practical benefit results from still higher ratios.

By adjusting the DMFCl.sub.2 concentration and the reaction time, the degree of cellulose substitution obtained can be varied considerably so that the chlorine content of the product is in the range of about 0.5 to 6 percent and the nitrogen content is in the range of 0.2 to 2.4 percent.

The washing step (d) listed above is preferably carried out using N,N-dimethylformamide as the solvent to remove excess DMFCl.sub.2, and must be done under anhydrous conditions. The presence of water causes immediate hydrolysis of cellulose N,N-dimethylformimidate chloride to yield cellulose formate.

The washing step (e) above is preferred in order to remove N,N-dimethylformamide, since the latter solvent is high boiling and is difficult to remove by heat drying. Solvents suitable for this washing are those solvents whose boiling points are less than 100.degree.C at 1 atmosphere pressure, are miscible with N,N-dimethylformamide, and are inert to DMFCl.sub.2. Examples of suitable solvents are benzene, carbon tetrachloride, chloroform, and ethylene chloride, with benzene being preferred because of its low cost.

The drying step, listed as (f) above, removes the solvent used in washing step (e) and may be carried out at any temperature below about 50.degree.C. At higher temperatures there is some tendency for chlorodeoxycellulose formation. Drying may be conducted with a stream of dry air, by vacuum, or by mild heating. The washing step (e) and drying step (f) may be omitted if the cellulose N,N-dimethylformimidate chloride is to be converted immediately to other cellulose derivatives.

PREPARATION OF IODODEOXYCELLULOSE

The preparation of iododeoxycellulose by the present invention comprises the following steps:

a. immersing air-equilibrated, fibrous cellulose in textile form in N,N-dimethylformamide at a temperature of about from 20.degree.C to 30.degree.C for a period of from 1 to 60 minutes to swell the fibers,

b. removing excess N,N-dimethylformamide,

c. immersing the cellulosic textile in a mixture of about from 3 to 15 percent by weight DMFCl.sub.2 in N,N-dimethylformamide at a temperature of from 20.degree.C to 30.degree.C for about from 3 minutes to 180 minutes in order to react the cellulose with the DMFCl.sub.2,

d. washing the cellulosic textile with N,N-dimethylformamide to remove excess DMFCl.sub.2,

e. immersing the cellulosic textile in a solution of an alkali metal iodide in N,N-dimethylformamide for a period of from 0.25 hour to 2 hours at a temperature of about from 60.degree.C to 150.degree.C, the concentration of the alkali metal iodide being about from 5 to 25 percent by weight in the N,N-dimethylformamide in order to react the cellulose N,N-dimethylformimidate chloride with the alkali metal iodide,

f. washing the cellulosic textile at 20.degree.C to 30.degree.C with N,N-dimethylformamide to remove excess alkali metal iodide and traces of DMFCl.sub.2,

g. washing the cellulosic textile with ice water and then with water at 20.degree. to 30.degree.C to remove N,N-dimethylformamide and further traces of alkali iodide, and

h. drying the cellulosic textile.

Steps (a) through (d) are the same as for the preparation of cellulose N,N-dimethylformimidate chloride. Step (e), the reaction of this derivative with an alkali metal iodide, is preferably carried out in N,N-dimethylformamide as the reaction medium since several of the alkali iodides have high solubility in this medium which also maintains the cellulosic fibers in a swollen and accessible condition. Of the alkali metal iodides, sodium iodide and potassium iodide are preferred as having the optimum compromise between low cost, high ionic character and reactivity and high solubility in N,N-dimethylformamide. Potassium iodide is particularly preferred in these respects.

Steps (f) and (g) remove unreacted iodide and DMFCl.sub.2. If the DMFCl.sub.2 used for step (c) contains some thionyl chloride as an impurity, the iododeoxycellulose formed will also have present appreciable amounts of sulfur-containing cellulose derivatives such as cellulose sulfite. The sulfites may be decomposed by washing the product with 2-5 percent aqueous ammonia followed by water washing. The ammonia wash also removes any formate ester groups present.

The drying step (h) may be carried out at any temperature below 90.degree.C but preferably at 20.degree.C to 40.degree.C since organic iodides such as iododeoxycellulose tend to undergo dehydrohalogenation and other side reactions with unusual ease.

PREPARATION OF CELLULOSE FORMATE

The preparation of cellulose formate by the present invention comprises the following steps:

a. immersing air-equilibrated, fibrous cellulose in textile form in N,N-dimethylformamide at a temperature of about from 20.degree.C to 30.degree.C for a period of from 1 to 60 minutes to swell the fibers,

b. removing excess N,N-dimethylformamide,

c. immersing the cellulosic textile in a mixture of about from 3 to 15 percent by weight DMFCl.sub.2 in N,N-dimethylformamide at a temperature of from 20.degree.C to 30.degree.C for about 3 minutes to 180 minutes, in order to react the cellulose with the DMFCl.sub.2,

d. washing the cellulosic textile with N,N-dimethylformamide to remove excess DMFCl.sub.2,

e. washing the cellulosic textile with ice water and then with water at 20.degree.C to 30.degree.C for 5 minutes to 60 minutes to hydrolyze the cellulose N,N-dimethylformimidate chloride to cellulose formate, and

f. drying the textile.

Steps (a) through (d) are the same as for the preparation of cellulose N,N-dimethylformimidate chloride.

PREPARATION OF CHLORODEOXYCELLULOSE

The preparation of chlorodeoxycellulose by the present invention comprises the following steps:

a. immersion of air-equilibrated fibrous cellulose in textile form in N,N-dimethylformamide at a temperature of about from 20.degree.C to 30.degree.C for a period of from 1 to 60 minutes to swell the fibers,

b. removing excess N,N-dimethylformamide,

c. immersing the cellulosic textile in a mixture of about from 3 to 15 percent by weight chlorodimethylformiminium chloride in N,N-dimethylformamide at a temperature of from 50.degree.C to 110.degree.C for about from 0.25 hour to 2 hours in order to react the cellulose with the DMFCl.sub.2,

d. washing the cellulosic textile with N,N-dimethylformamide to remove excess DMFCl.sub.2,

e. washing the cellulosic textile with ice water and then with water at 20.degree.C to 30.degree.C to remove N,N-dimethylformamide and further traces of DMFCl.sub.2, and

f. drying the textile.

Steps (a) and (b) are the same as for the preparation of cellulose N,N-dimethylformimidate, while step (c) differs primarily in the use of a higher reaction temperature. Step (d) also is the same as for preparing cellulose N,N-dimethylformimidate. Step (e) can be modified to include a wash with 2-5 percent aqueous ammonia if needed to remove sulfur-containing impurities in the product. The ammonia wash also removes any formate ester groups present. The sulfur-containing impurities arise if the DMFCl.sub.2 employed contains appreciable amounts of thionyl chloride. Drying (step f) is preferably done at moderate temperatures not exceeding 80.degree.C in order to avoid dehydrochlorination.

SPECIAL FEATURES AND UTILITY

It is evident that DMFCl.sub.2 undergoes only single-ended attachment to cellulose as a result of the present processes, since the cellulose N,N-dimethylformimidate produced is completely soluble in 0.5 M cupriethylenediamine and no crosslinking of cellulose can be detected. A solution of purified DMFCl.sub.2 in N,N-dimethylformamide differs in composition from a solution of thionyl chloride in N,N-dimethylformamide. The latter solution appears to be an equilibrium mixture of thionyl chloride, N,N-dimethylformamide, a 1:1 addition complex of thionyl chloride and the amide, as well as sulfur dioxide and some DMFCl.sub.2. The presence of the 1:1 complex having the structure [(CH.sub.3).sub.2 N.sup.+ = CHOSOCl] Cl.sup.- has been discussed by Bosshard et al, as cited above, who found it necessary to remove the sulfur dioxide under vacuum in order to shift the equilibrium towards formation of DMFCl.sub.2. As already indicated above, the use of thionyl chloride to treat cellulose always gives rise to sulfur-containing cellulose derivatives as byproducts, whereas highly purified DMFCl.sub.2, when reacted with cellulose, yields a sulfur-free product.

The celluose N,N-dimethylformimidate chloride prepared from DMFCl.sub.2 and cellulose is found to have appreciable flame resistance. This is unexpected since the product contains neither phosphorus nor bromine, the two most common elements in flame retardant finishes.

Chlorodeoxycellylose and iododeoxycellulose produced by the present processes exhibit increased flame resistance also, as well as rot resistance. Cellulose formate exhibits enhanced dyeability by disperse dyes.

METHODS OF TEXTILE EVALUATION

In the examples that follow, yarn breaking strength was measured by the procedure of ASTM-D1682-64, using an Instron tester. Fabric breaking strength was measured by the strip method (ASTM D39-49). Flame resistance was measured by determining the maximum angle from the vertical that a sample could be positioned, such that when ignited from the lower end by a match, the flame was self-extinguising after the match was withdrawn (Reeves, McMillan and Guthrie, Textile Research J. 23, 527-532 (1953) ). Rot resistance was determined by burial of the samples in inoculated soil (AATCC 30-1957T). Formyl content of cellulose format was determined by modified Eberstadt titration (ASTM D-871-63). The infrared spectra of cellulose formate samples was recorded on a Perkin-Elmer Model 137B Infracord spectrophotometer for pellets of the powdered samples pressed into potassium bromide discs.

In all cases the yarns or fabrics to be used in the following examples were stored in air at 30-80 percent relative humidity prior to use and contained the equilibrium amount of regain moisture.

In the examples, all parts and percentages given are by weight. The term D.S. refers to the degree of cellulose substitution, i.e., the number of substituent groups introduced per anhydroglucose unit of cellulose.

EXAMPLE 1

Preparation of Cellulose N,N-dimethylformimidate chloride from Cellulose Yarn

Kiered, 12/3 cotton yarn was immersed in excess N,N-dimethylformamide for 30 minutes at 25 .degree.C, then excess N,N-dimethylformamide was removed from the yarn by centrifugation at 2850 rpm for 1 minute. The yarn was subsequently reacted for 5 minutes at 25.degree.C with 6 percent chlorodimethylformiminium chloride (DMFCl.sub.2) in N,N-dimethylformamide in a stoppered flask with agitation, utilizing 40 grams of solution per gram of cotton. The yarn was then subsequently washed three times with excess N,N-dimethylformamide, three times with excess benzene, centrifuged for 1 minute at 2850 rpm, and allowed to air-dry to constant weight. The resultant yarn had only trace amounts of sulfur and a chlorine content of 3.34 percent and a nitrogen content of 1.36 percent. The chlorine/nitrogen atomic ratio was 1.0 as required for the structure Cell--O--CH=N.sup.+(CH.sub.3).sub.2 Cl.sup.- , cellulose N,N-dimethylformimidate chloride. This cellulose derivative had a breaking strength of 5.6 lbs. compared to 5.2 lbs. for untreated, native cotton yarn and also had a match angle test value of 60.degree. compared to 0.degree. for native cotton yarn.

Conducting the reaction for a longer time (3 hours) with all other conditions comparable to those described above, produced the cellulose N,N-dimethylformimidate chloride yarn having only trace amounts of sulfur, a chlorine content of 5.10 percent, and a nitrogen content of 2.24 percent. The resultant cellulose derivative had a breaking strength of 4.7 lbs. compared to 5.2 lbs. for untreated, native cotton yarn; it also had a match angle test value of 120.degree. compared to 0.degree. for native cotton yarn.

EXAMPLE 2

Reaction of DMFCl.sub.2 with Cotton Yarn in Absence of Preswelling Step

Kiered 12/3 cotton yarn was immersed in a 6 percent solution of DMFCl.sub.2 in N,N-dimethylformamide at 25.degree.C for 5 minutes in a stoppered, mechanically agitated flask, utilizing 40 grams of solution per gram of cotton. The yarn was subsequently washed three times with excess N,N-dimethylformamide, three times with benzene, was centrifuged for 1 minute at 2850 rpm, and allowed to air-dry to constant weight. The resultant yarn contained only 0.46 percent chlorine, 0.12 percent nitrogen and no sulfur. By comparison, yarn which was first preswollen in N,N-dimethylformamide, and then was reacted with 6 percent DMFCl.sub.2, followed by washing and drying, contained 3.34 percent chlorine and 1.36 percent nitrogen, as shown in Example 1.

The results show that the yarn given the preswelling treatment in N,N-dimethylformamide, prior to treatment with DMFCl.sub.2 reacted more than 7 times as fast as did the yarn not given the preswelling treatment. Even if a reaction time of 1 hour were allowed for yarn not preswollen, a chlorine content of only 2.45 percent and a nitrogen content of only 0.51 percent were reached, which values are less than those reached in 5 minutes with the preswollen yarn.

EXAMPLE 3

Preparation of Cellulose Formate by Reaction of Cotton Yarn with DMFCl.sub.2 at 25.degree.C

Kiered, 12/3 cotton yarn was immersed in excess N,N-dimethylformamide for 10 minutes, then excess N,N-dimethylformamide was removed from the yarn by centrifugation for 1 minute at 2850 rpm. The yarn was subsequently reacted for 1 hour at 25.degree.C (in a stoppered flask with agitation) with 6 percent DMFCl.sub.2 in N,N-dimethylformamide, using a bath ratio of 40 grams of solution per gram of cotton. The yarn was subsequently washed with ice water, then with tap water for 30 minutes, and air-dried to produce cellulose formate (D.S. of 0.16) having only trace amounts of sulfur (0.25 percent) and chlorine (0.19 percent). The resultant yarn had a breaking strength of 4.4 lbs. compared to native cotton yarn which had a breaking strength of 5.2 lbs. The presence of formate ester groups in the treated yarns was demonstrated by an intense absorption peak at 5.8-5.9 millimicrons in the infrared spectrum of the treated yarn. This peak, which is absent for untreated yarns, has been assigned to the carbonyl stretching frequency characteristic of the formyl groups. The same spectrum was obtained in yarn esterified with 90 percent formic acid. If the cotton yarn were treated under the same conditions, with the exception that it was not preswollen in N,N-dimethylformamide prior to reaction, the resultant D.S. with respect to formate ester groups was only 0.04, with the yarn having a breaking strength of 4.8 lbs. compared to 5.2 lbs. for untreated cotton yarn.

EXAMPLE 4

Preparation of Chlorodeoxycellulose Yarn from Cellulose and Excess DMFCl.sub.2

Kiered, 12/3 cotton yarn was immersed in excess N,N-dimethylformamide for 30 minutes at 25.degree.C and excess N,N-dimethylformamide was then removed from the yarn by centrifugation at 2850 rpm for 1 minute. The yarn was subsequently reacted with 6 percent DMFCl.sub.2 in N,N-dimethylformamide for 1 hour at 50.degree.C in a tube immersed in a constant temperature bath, utilizing 40 grams of solution per gram of cotton. After cooling to room temperature, the yarn was washed with N,N-dimethylformamide until the washings were colorless. The yarn was subsequently washed with ice water and then tap water in excess for 30 minutes, and allowed to air-dry. The resultant chlorodeoxycellulose yarn had a D.S. of 0.05 (1.05 percent Cl), a sulfur content of 0.77 percent, and a D.S. of 0.28 with respect to formate ester groups. The yarn had a breking strength of 3.8 lbs. compared to 5.2 lbs. for untreated cotton yarn.

In another experiment, the reaction was conducted under the same experimental conditions, but the wash procedure was modified. After an initial tap water wash for 15 minutes, the yarn was washed with excess 3 ammonium hydroxide, and then tap water for another 15 minutes prior to air-drying. The resultant chlorodeoxy cellulose yarn had a D.S. of 0.04 (percent Cl = 0.97), a sulfur content of 0.39 percent, a D.S. of only 0.01 with respect to formate ester groups, and a breaking strength of 4.0 lbs.

Conducting the reaction for the same time and concentration of DMFCl.sub.2 at 75.degree.C with only a water wash, produced a chlorodeoxycellulose yarn having a D.S. of 0.25 (5.27 percent Cl), a sulfur content of 1.33 percent, and a D.S. of 0.31 with respect to formate ester groups. If an ammonia wash were utilized, the resultant chlorodeoxycellulose yarn had a D.S. of 0.26 (5.55 percent Cl), a sulfur content of 0.88, and a D.S. of only 0.08 with respect to formate ester groups introduced. The breaking strengths of the chlorodeoxycellulose yarns with and without the ammonia wash were, respectively, 3.3 and 3.1 lbs.

When the reaction was conducted at 100.degree.C under otherwise comparable experimental conditions, the resultant chlorodeoxycellulose yarn (with a water wash only) possessed 6.53 percent Cl (D.S. of 0.31), a sulfur content of 0.97, and a D.S. of 0.18 with respect to formate ester groups introduced. Utilizing an ammonia wash produced a chlorodeoxycellulose yarn with a D.S. of 0.34 (7.13 percent Cl), a sulfur content of 0.71 and a D.S. of only 0.04 with respect to formate ester groups. The breaking strengths of the resultant yarns with and without the ammonia wash were 1.8 and 1.6 lbs., respectively.

EXAMPLE 5

Reaction of Cellulose Yarn without Utilizing Excess DMFCl.sub.2

Kiered, 12/3 cotton yarn was immersed in excess N,N-dimethylformamide for 30 minutes at 25.degree.C, and then excess N,N-dimethylformamide was removed from the yarn by centrifugation at 2850 rpm for 1 minute. The yarn was subsequently reacted with 6 percent DMFCl.sub.2 in N,N-dimethylformamide for 1 hr. at 25.degree.C with shaking in a stoppered flask, utilizing 40 grams of solution per gram of cotton. Excess DMFCl.sub.2 was removed from the cotton yarn by washing with N,N-dimethylformamide, and then the yarn was subsequently centrifuged for 1 minute at 2850 rpm to remove excess solvent. The yarn was then heated for 1 hour at 100.degree.C in a tube containing N,N-dimethylformamide with the bath ratio being 40 grams of solvent per gram of cotton. After cooling to room temperature, the yarn was washed with water only as described in the first part of Example 1. The resultant yarn had only 0.21 percent Cl, representing a D.S. of 0.01, but also contained 0.24 percent S and had a D.S. of 0.13 with respect to formate ester groups. The breaking strength was 4.0 lbs.

EXAMPLE 6

Preparation of Chlorodeoxycellulose Fabric Utilizing Excess DMFCl.sub.2

Desized, scoured and bleached 80 .times. 80 cotton printcloth was immersed in excess N,N-dimethylformamide at 25.degree.C for 30 minutes, put through laboratory wringers to remove excess N,N-dimethylformamide, and then reacted for 1 hour at 75.degree.C with 6 percent DMFCl.sub.2 in N,N-dimethylformamide under the same experimental conditions described for the cotton yarn in Example 1. Utilizing the water-wash-only procedure, the resultant chlorodeoxycellulose fabric had 6.0 percent Cl (D.S. - 0.28), and a sulfur content of 3.13 percent; the fabric had a warp breaking strength of 25.2 lbs. compared to 49.7 lbs. for untreated printcloth. After two weeks of the soil burial test, the untreated printcloth had disappeared, whereas the chlorodeoxycellulose printcloth had a breaking strength of 22.1 lbs. After four weeks of the soil burial test, the chlorodeoxycellulose printcloth still had a breaking strength of 22.9 lbs.

EXAMPLE 7

Preparation of Iododeoxycellulose Utilizing DMFCl.sub.2 and Iodide Ion

Kiered, 12/3 cotton yarn was immersed at 25.degree.C for 10 minutes in N,N-dimethylformamide and then the excess N,N-dimethylformamide was removed by centrifugation for 1 minute at 2850 rpm. The yarn was reacted for 1 hour in a stoppered flask with shaking at 25.degree.C with 6 percent DMFCl.sub.2 in N,N-dimethylformamide, utilizing a bath ratio of 40 grams of solution per gram of cotton. Subsequently, the yarn was washed with N,N-dimethylformamide to remove excess DMFCl.sub.2, centrifuged for 1 minute at 2850 rpm, and then reacted in a constant temperature bath for 1 hour at 100.degree.C with 12 percent potassium iodide in N,N-dimethylformamide. The bath ratio was 40 to 1. The yarn was then cooled to room temperature, washed with N,N-dimethylformamide, washed with ice water, excess tap water for 30 minutes, and was air-dried. The resultant iododeoxycellulose yarn had an iodine content of 2.12 percent (D.S. of 0.03), 0.10 percent Cl, 0.16 percent S, and a D.S. of only 0.19 with respect to formate ester groups. The yarn had a breaking strength of 4.7 lbs. and a match test angle of 15.degree. with a black residue. Untreated yarn leaves no residue.

When 20 percent potassium iodide in N,N-dimethylformamide was utilized at 100.degree.C by the above procedure, the resultant yarn possessed 1.88 percent I (D.S. of 0.02), 0.93 percent Cl, 0.29 percent S, and a D.S. of 0.15 with respect to formate ester groups. The breaking strength of the yarn was 4.9 lbs. and it had a match test angle of 45.degree. and left a black residue. When an ammonia wash was used, the iododeoxycellulose yarn had 2.34 percent I, 0.30 percent Cl, 0.19 percent S, and a D.S. of only 0.02 with respect to formate ester groups. The yarn had a match test angle of 60.degree. and a breaking strength of 5.0 lbs.

When 20 percent potassium iodide in N,N-dimethylformamide was utilized at 125.degree.C by the above procedure, followed by the water wash, the resultant yarn had 3.86 percent I, (D.S. of 0.05), 0.53 percent Cl, 0.13 percent S, and a D.S. of 0.13 with respect to formate ester groups; utilizing the ammonia wash produced a yarn containing 3.54 percent I (D.S. of 0.05), 0.28 percent Cl, 0.07 percent S, and a D.S. of only 0.05 in formate ester groups. The breaking strengths, respectively, of the yarns with and without the ammonia wash, were 4.0 and 4.3 lbs; match tests, respectively, were 90.degree. and 60.degree..

EXAMPLE 8

Preparation of Iododeoxycellulose Fabric Utilizing DMFCl.sub.2 and Iodide Ion

Desized, scoured and bleached 80 .times. 80 cotton printcloth was immersed in excess N,N-dimethylformamide at 25.degree.C for 30 minutes, put through laboratory wringers to remove excess N,N-dimethylformamide, and then shaken in a stoppered flask for 1 hour at 25.degree.C with 10 percent DMFCl.sub.2 in N,N-dimethylformamide, using a bath ratio of 40 grams of solution per gram of cotton. The fabric was washed free of excess DMFCl.sub.2 with N,N-dimethylformamide, put through wringers again to remove excess N,N-dimethylformamide, and then reacted in a constant temperature bath at 125.degree.C for 1 hour with 20 percent potassium iodide in N,N-dimethylformamide (bath ratio of 40 grams of solution per gram of cotton). After cooling to room temperature, the fabric was given the conventional water wash and air-drying. The resultant fabric had an iodine content of 7.56 percent (D.S. of 0.10), 14 percent Cl, and 0.53 percent S. The fabric had a warp breaking strength of 35.8 lbs. compared to 49.7 lbs. for untreated cotton printcloth. After two weeks of the soil burial test, the untreated printcloth disappeared whereas the iododeoxycellulose fabric had a breaking strength of 32.9 lbs. The resultant fabric also had a match test angle of 75.degree. and gave a black residue.

Claims

We claim:

1. As a textile material, fibrous cellulose N,N-dimethylformimidate chloride possessing the structure Cell--O--CH=N.sup.+(CH.sub.3).sub.2 Cl.sup.-, wherein Cell represents a portion of a cellulose molecular chain, said material comprising a chlorine content of from 0.5 to 6 percent as well as a nitrogen content of from 0.2 to 2.4 percent, the ratio of chlorine atoms to nitrogen atoms being 1:1 and the formimidate groups being characterized by rapid hydrolysis to formate groups on contact with water, said textile material also being characterized by increased flame resistance relative to the original untreated textile.

2. A process for preparing a fibrous cellulose N,N-dimethylformimidate chloride in textile form which process comprises:

a. immersing air-equilibrated fibrous cellulose in textile form in N,N-dimethylformamide at a temperature of about from 20.degree.C to 30.degree.C for a period of from 1 to 60 minutes to swell the fibers,

b. removing excess N,N-dimethylformamide,

c. immersing the cellulosic textile in a mixture of about from 3 to 15 percent by weight of chlorodimethylformiminium chloride in N,N-dimethylformamide at a temperature of from 20.degree.C to 30.degree.C for about from 3 minutes to 180 minutes, in order to react the cellulose with the chlorodimethylformiminium chloride,

d. washing the cellulosic textile with N,N-dimethylformamide to remove excess chlorodimethylformiminium chloride,

e. washing the cellulosic textile with an inert, volatile, aprotic solvent miscible with N,N-dimethylformamide, and

f. drying the cellulosic textile.

3. The process of claim 2 where the textile form is a yarn.

4. The process of claim 2 where the textile form is a fabric.

5. The process of claim 2 where the inert, volatile, aprotic solvent is benzene.

6. A process for preparing a fibrous iododeoxycellulose in textile form, which process comprises:

a. immersing air-equilibrated fibrous cellulose in textile form in N,N-dimethylformamide at a temperature of about from 20.degree.C to 30.degree.C for a period of from 1 to 60 minutes to swell the fibers,

b. removing excess N,N-dimethylformamide,

c. immersing the cellulosic textile in a mixture of about from 3 to 15 percent by weight of chlorodimethylformiminium chloride in N,N-dimethylformamide at a temperature of from 20.degree.C to 30.degree.C for about from 3 minutes to 180 minutes, in order to react the cellulose with the chlorodimethylformiminium chloride,

d. washing the cellulosic textile with N,N-dimethylformamide to remove excess chlorodimethylformiminium chloride,

e. immersing the cellulosic textile in a solution of an alkali metal iodide in N,N-dimethylformamide for a period of from 0.25 hour to 2 hours at a temperature of about from 60.degree.C to 150.degree.C, the concentration of the alkali metal iodide being about from 5 to 25 percent by weight in the N,N-dimethylformamide, in order to react the cellulose N,N-dimethylformimidate chloride with the alkali metal iodide,

f. washing the cellulosic textile from 20.degree.C to 30.degree.C with N,N-dimethylformamide to remove excess alkali metal iodide,

g. washing the cellulosic textile with ice water and then with water at 20.degree.C to 30.degree.C to remove N,N-dimethylformamide and further traces of alkali metal iodide, and

h. drying the cellulosic textile.

7. The process of claim 6 where the textile form is a yarn.

8. The process of claim 6 where the textile form is a fabric.

9. The process of claim 6 where the alkali metal iodide is sodium iodide.

10. The process of claim 6 where the alkali metal iodide is potassium iodide.

11. A process for preparing a fibrous cellulose formate in textile form, which process comprises:

a. immersing air-equilibrated fibrous cellulose in textile form in N,N-dimethylformamide at a temperature of about from 20.degree.C to 30.degree.C for a period of from 1 to 60 minutes to swell the fibers,

b. removing excess N,N-dimethylformamide,

c. immersing the cellulosic textile in a mixture of about from 3 to 15 percent by weight of chlorodimethylformiminium chloride in N,N-dimethylformamide at a temperature of from 20.degree.C to 30.degree.C for about from 3 minutes to 180 minutes, in order to react the cellulose with the chlorodimethylformiminium chloride,

d. washing the cellulosic textile with N,N-dimethylformamide to remove excess chlorodimethylformiminium chloride,

e. washing the cellulosic textile with ice water and then with water at 20.degree. to 30.degree.C, for from 5 minutes to 60 minutes, to hydrolyze the cellulose N,N-dimethylformimidate chloride to cellulose formate, and

f. drying the cellulosic textile.

12. A process for preparing a fibrous chlorodeoxycellulose in textile form, which process comprises:

a. immersing air-equilibrated fibrous cellulose in textile form in N,N-dimethylformamide at a temperature of about from 20.degree.C to 30.degree.C for a period of from 1 to 60 minutes to swell the fibers,

b. removing excess N,N-dimethylformamide,

c. immersing the cellulosic textile in a mixture of about from 3 to 15 percent by weight of chlorodimethylformiminium chloride in N,N-dimethylformamide at a temperature of from 50.degree. to 110.degree.C for about 0.25 hour to 2 hours in order to react the cellulose with the chlorodimethylformiminium chloride,

d. washing the cellulosic textile with N,N-dimethylformamide to remove excess chlorodimethylformiminium chloride,

e. washing the cellulosic textile with ice water and then with water at 20.degree.C to 30.degree.C to remove N,N-dimethylformamide and further traces of chlorodimethylformiminium chloride,

f. drying the cellulosic textile.

13. The process of claim 12 where the textile form is a yarn.

14. The process of claim 12 where the textile form is a fabric.