US2520103A

US2520103A - Method of treating fibrous cellulosic materials to impart flame resistance thereto, compositions therefor, and products thereof

Info

Publication number: US2520103A
Application number: US76644A
Authority: US
Inventors: Loukomsky Anne Macmillan; Roy H Kienle; Theodore F Cooke
Original assignee: American Cyanamid Co
Current assignee: Wyeth Holdings LLC
Priority date: 1949-02-15
Filing date: 1949-02-15
Publication date: 1950-08-22
Anticipated expiration: 1967-08-22

Description

Patented Aug. 22, 1950 METHOD or TREATING muons omn- LOSIC mrnams 'ro man-r FLAME RESISTANCE THERETO, COMPOSITIONS THEREFOR, AND PRODUCTS THEREOF Anne MacMillan Loukomaky, North Plainfield,

Roy H. Kienle, Bound Brook, and Theodore F. Cooke, Martinsville, N. J assignors to American Cyanamid Company, New York, N. Y., a corporation of Maine No Drawing. Application February 15, 1949, Serial No. 76,644

This invention relates to a method of impart- 17 Claims. (01. 117-137) ing flame resistance to a cellulosic material, more v particularly acellulosic material of the class consisting of natural and regenerated celluloses and mixtures thereof, and specifically to a textile comprising fibers of such cellulosic materials, as well ascompositions used in such treatments and to the flame-resistant cellulosic products thereof.

Various compounds and compositions have been used or suggested for use as agents for treating fibrous cellulosic and other normally flammable organic materials in order to render them resistant to flame. such compounds and compositions see the book entitled "Flameproofing Textile Fabrics, edited by Robert W. Little and published in 1947 by Reinhold Publishing Corporation, New York, N. Y., and the references cited therein. Reference also is made to the copending application of one of use (formerly Anne MacMillan, now Anne MacMillan Loukomsky) Serial No. 691,866, filed August 20, .1946, now abandoned, wherein is disclosed and claimed a method of imparting flame resistance to cellulosic textiles which comprises impregnating such textiles with a phosphate of an acyclic amidine, specifically monoguanidine phosphate, and a member of the group consisting of urea, biuret, ammonium cyanate, cyanamide and dicyandiamide in amounts sufllcient to impart flame resistance thereto upon subsequent heating, and then heating the impregnated textiles at a temperature of at least 135 C. to form a washfast, flame-resistant finish therein and thereon.

Agents or treatments for imparting flame resistance to normally flammable organic materials properly may be classified as (1) temporary, (2) semi-durable and (3) permanent or durable, based on their durability in providing continued resistance of the treated textile or other material to flame during use. See page 6 of the aforementioned book by Little for a more complete description of these classes. The present invention is concerned primarily with certain new and useful improvements in the permanent or durable agents or treatments of the kind aforementioned.

The durable treatments heretofore used or suggested have been of three general kinds or types:

1. Urea-phosphate type. 2. Double-bath precipitation type. 3. Metallic oxide-chlorinated body type.

See Littles book, supra, pages 179-284, for a complete description and discussion of each of these types. One of the main objections to the For a description of urea-phosphate type of treatment is the tendering effect of the treatment on the cellulosic material whereby its tensile strength is reduced considerably. The double-bath precipitation and the metallic oxide-chlorinated body types of treatments generally yield cellulosic textiles having a harsh or stiff hand, so that the treated textile has a limited field of utility.

The present invention is based on our discovery that fibrous cellulosic materials including those composed solely or comprised mainly (that is, preponderantly by weight) of fibers of natural cellulose (that is, cellulosic materials of natural origin), regenerated cellulose (more particularly viscose rayons) and mixtures thereof can be rendered substantiall permanently resistant to flame by suitably treating them with compositions of the kind hereinafter described. Our treated fibrous cellulosic textiles in thread, yarn, fabric or other form are unique in that they are characterized not only by their substantially permanent flame resistance but also by their improved hand or feeling to the touch as compared with the hand of textiles that have been given a double-bath precipitation or a metallic oxidechlorinated body type of treatment, thereby increasing the field of utility of flame-resistant textiles. Furthermore, these properties are obtained without excessive tendering of the textile, .the'

treated textile in general having a tensile strength (average of the sum of the tensile strength of the warp and filling) of at least of that of the untreated textile when similarly tested for tensile strength, and in many cases a tensile strength which is even higher than that of the untreated textile.

More particularly we have discovered that flame-resistant, fibrous, cellulosic textile materials comprising or composed of fibers of natural cellulose, regenerated cellulose or a mixture thereof and which have a good hand, that is, a.

hand or feeling to the touch which meets the requirements of the trade, and good tensile strength characteristics are produced by impreghatin the normally flammable cellulosic textile with certain materials in particular proportions or ranges of proportions which are critical in carrying the invention into effect. A substantial proportion of the impregnant initially applied is fixedly held by the cellulosic textile after subsequent heat treatment and washing; hence the flame-resistant textiles of our invention properly may be designated as being of the durable type or kind.

When the flame-resistant cellulosic textiles of our invention are tested for flame resistance using a vertical flame test, such as is described hereinafter, the char length" (charred length) ordinarily is not more than about 6 inches, e. g., from 3 to inches, when the textile material (e. g., cotton cloth or viscose rayon fabric) which has been treated and then subjected to 5 Washes in neutral soap solution is one weighing 4 ounces or more per square yard, and not more than about 8 inches, e. g., from 3 to 7 /2 inches, when the fabric which has been treated weighs substantially less than 4 ounces, e. g., 2 or 3 ounces per square yard.

In practicing our invention a cellulosic material, more particularly a fibrous cellulosic material of the kind defined in the first paragraph of this specification, is impregnated with ingredients comprising (1) a finely divided oxide of antimony, specifically antimony trioxide, and (2) a thermally unstable, halogen-containing thermoplastic substance, more particularly a thermoplastic substance containing at least by weight of combined halogen and capable of rupturing under heat at carbon-halogen bonds, the ingredients of (1) and (2),.which together are designated hereinafter as (A), being employed in a weight ratio of 1 part of the former to from 0.6 to 20 parts, more particularly from 0.8 to 4 parts, of the latter. Examples of the thermoplastic substances of (2) that may be employed, alone or in the form of mixtures thereof, are halogencontainlng vinyl resins in which not less than 20% by weight of combined halogen is present, for instance, polyvinyl halides (e. g., polyvinyl chloride, polyvinyl bromide, etc.), polyvinylidene halides (e. g., polyvinylidene chloride, polyvinylidene bromide, etc.) copolymers of a vinyl halide and a vinylidene halide (e. g., a copolymer of vinyl chloride and vinylidene chloride), copolymers of a vinyl halide and an acrylic ester (for instance, a copolymer of vinyl chloride and an alkyl acrylate (e. g., methyl, ethyl, propyl, butyl, etc, acrylates), halogenated (e. g., chlorinated) paraiilns containing not less than 20% by weight of combined halogen, more particularly from about or up to or by weight of combined chlorine, bromine, or other halogen, etc. In addition to the ingredients of (1) and (2), other ingredients with which the cellulosic material is impregnated are (3) a water-soluble salt (or mixtures thereof) of an oxygen-containing acid of phosphorus wherein the phosphorus atom has a valence of 5, e. g., a guanidine phosphate, a diguanidine pyrophosphate, diammonium hydrogen phosphate, sodium polyphosphate, ammonium metaphosphate, the mono-, diand trialkylamine pyrophosphates, etc., and (4) a water-soluble nitrogenous substance of the group consisting of cyanamide, dicyandiamide and mixtures thereof. The ingredients of (3) and (4), which together are designated hereinafter as (B) are employed in a weight ratio of 1 part of the former calculated as phosphoric acid (HJPOO to from 0.2 to 5.5 parts, more particularly from 0.3 to 4.5 parts and preferably from 0.5 to 2 parts of the latter, while the ingredients of (A) and (B) are employed in a weight ratio of 1 part of the former to from 0.2 to 8 parts, more particularly from 1 to 3 parts, of the latter, The present invention differs from the invention disclosed and claimed in our copending application Serial No. 64,416, filed December 9, 1948, in that in the invention of the earlier filed application the finely divided metallic oxide is selected from the group consisting of tin, titanium, antimony and bismuth oxides and mixtures thereof, whereas in the present invention it is an oxide of antimony, specifically antimony trioxide; and the water-soluble nitrogenous substance in the earlier case is selected from the group consisting of urea, biuret, ammonium cyanate, ammonium dicyanimide and mixtures thereof, while in the present case it is selected from the group consisting of cyanamide, dicyandiamide, and mixtures thereof. Furthermore, in the invention of our earlier filed application the water-soluble nitrogenous substance is employed in a weight ratio of from 1 to 20 parts thereof for each part, calculated as HaPO4, of the oxygencontaining acid of phosphorus, whereas in the present invention the water-soluble nitrogenous substance is used in a weight ratio of from 0.2 to 5.5 parts thereof for each part, calculated as HaPO4, of the oxygen-containing acid of phosphotos.

The fibrous cellulosic material may be impregnated with th aforementioned ingredients in one or more steps or stages. Thus, it may be impregnated with a dispersion, more particularly an aqueous dispersion, containing the ingredients mentioned in the preceding paragraph within the ranges of proportions therein specified. The treated cellulosic material is dried at a suitable temperature, e. g., at 40 or 50 to or C., and then heated at a higher temperature within the range of C. (about 135 C.) to 200 C. (about 200 0.). During this latter heat treatment a complex reaction takes place with the result that the finished cellulosic textile in thread, yarn, fabric, felted or other form is rendered substantially permanently resistant to flame, that is to say, the finished textile is resistant to flame even after numerous laundering or dry-cleaning operations. After the heat treatment, the impregnated cellulosic material is washed, e. g., with water, to remove water-soluble substances which are usually present therein.

Alternatively, the fibrous cellulosic material may be impregnated first with an aqueous solution containing a guanidine phosphate or other water-soluble salt of an oxygen-containing acid of phosphorus wherein the phosphorus atom has a valence of 5 (or a mixture of such salts) and cyanamide, dicyandiamide or a mixture thereof. The water-soluble salt of the acid of phosphorus and the water-soluble nitrogenous substance (cyanamide, dicyandiamide or a mixture thereof), which together are designated herein as (B), are employed in ratios by weight within the ranges mentioned hereinbefore. The impregnated fibrous material is dried, heated and washed as described in the preceding paragraph with reference to the one-step process. Thereafter it is treated, as by immersion in a bath containing the same, with a liquid dispersion, more particularly an aqueous liquid dispersion, containing a finely divided oxide of antimony, more particularly finely divided antimony, trioxide, and, also, a thermally unstable, thermoplastic substance containing at least 20%. pr ferably at least 40%, of combined chlorine or other halogen and which is capable of rupturing under heat at carbonhalogen bonds, e. g., polymers and copolymers of vinyl chloride. It'is important that the antimony oxide and the halogen-containing thermoplastic substance or substances, which together are designated herein as (A), also be employed in weight ratios within the ranges hereinbefore mentioned. After this second treatment the treated cellulosic material is dried, e. g., by allowing it to stand at Mm temperature or by heating it at an elevated temperature such, for instance, as atatemperature within the range of 40 or 50 C. up to 100 or 105 C.

From the foregoing description it will be noted that the ingredients of (A) and (B) may be applied to the cellulosic material in one stage (i. e., a one-bath system) or in two stages (i. e., a twobath system); or, in other words, in the form of at least one and not more than two aqueous liquid compositions containing the same. It is important that the aqueous composition containmg the ingredients of (B) have a pH of from about 3 to about 7, more particularly a pH within the range of about 3 /2 or 4 to about 5 or 6, since at the lower pH values (below about 3) the tensile strength losses in the treated goods are excessive while at the higher pH values (above about 7) the treated textiles have much poorer fire resistance.

Regardless of the method of impregnation of the fibrous cellulosic material with the aforementioned ingredients, it is important that the ingredients of (A) and (B) be employed in a weight ratio of 1 part of the former to from 0.2 to 8 parts, e. g., from 0.5 to 6 parts, of the latter. In all cases the total amount of the ingredients of (A) and (B) with which the cellulosic material, e. g., a cotton or viscose rayon textile material, initially is impregnated is suiiicient to impart flame resistance thereto upon heating within the range of 135 C. to 200 C. and thereafter washing to remove any residual water-soluble substances. 'Thus, the total amount of the ingredients of (A) and (B) with which the cellulosic material is impregnated advantageously is such that the finished flame-resistant textile contains from about 10% to about 50% by we=ght (which in some cases may be as high as about 75% by weight when the matter of the hand of the treated material is relatively unimportant), based on the ner similar to that described in the copending application of Maurice R. Burnell and William J. Van Loo, Jr., Serial No. 64,418, filed December 9, 1948, with particular reference to compositions wherein the ingredients are of the kind and are used in the proportions set forth in our aforementioned copending application Serial No. 64,416.

When a two-bath system of applying the ingredients is employed, the first bath is prepared by dissolving in water the proper proportions of (1) guanidine phosphate or other water-soluble salt of an oxygen-containing acid of phosphorus in which the phosphorus atom has a valence of 5 and (2) cyanamide, dicyandiamide or a mixture thereof. This bath should be within a pH range of from about 3 to about '7. The bath also may contain a small amount, advantageously not over 7% by weight of the ingredients of (l) and (2), of a polyalkylene polyamine, preferably such a polyamine which is normally a solid or which has a boiling point substantially above 200 C., e. g., triethylene tetramine, tetraethylene pentamine, hexamethylene tetramine, etc. The ingredients are dissolved in water merely by stirring and heating at a suitable temperature, e. g., at 40 C. to 70 C. or higher. The concentration of ingredients in the aqueous bath may be varied as desired or as conditions may require, but usually they constitute from about 30% to about 50% by weight of the aqueous solution. The composition of a typical bath is as follows:

Approximate per cent by weight Monoguanidine phosphate.. 29.0 Cyanamide 14.5 Hexamethylene tetramine 2.0 Water 54.5

salt of a condensation product of an aldehyde,

specifically formaldehyde, and a naphthalene sulfonic acid. This dispersion is passed through a colloid mill in order to reduce the particle size to one micron. To the resulting dispersion is then added a dispersion of a polyvinyl halide polymerization product, more particularly a polyvinyl chloride polymerization product, e. g., polyvinyl chloride itself or a vinyl chloride copolymer comprising mainly vinyl chloride, for instance a copolymer of, by weight, 80 to 99% of vinyl chloride (in the copolymer molecule) and 20 to 1% of vinylidene chloride, a lower alkyl acrylate (e. g., methyl, ethyl, etc., acrylates) or a vinyl ester of an aliphatic monocarboxylic acid (e. g., vinyl acetate, vinyl propionate, etc.) or other thermoplastic substance containing at least 20% by weight of combined halogen and capable of rupturing under heat at carbon-halogen bonds. The mixture is thoroughly agitated until a homogeneous liquid composition or dispersion is obtained. The concentration of solids in this dispersion may be varied as desired or as conditions may require, but usually they constitute from about 10% to about 30% by weight thereof.

Anysuitable apparatus may be employed in applying the treating composition (used in a onebath process) or compositions (used in a two-bath process) to the cellulosic material. For example, the dry or substantially dry cellulosic textile to be treated may be immersed in the aqueous composition or compositions and then passed through pressure rolls, mangles or centrifugal extractors to secure uniform impregnation and a controlled said agent is applied in one or two distinct steps or stages, is adjusted so that the finished textile captains from about 10% to about usually from 10% to 50% by weight, based on the dry weight of the untreated textile, of washfast impregnant. As has been indicated hereinbefore, when the matter of hand of the finished textile is important, it generally contains not more than about 50%, e. g., from 10 or 15% to 30 or 40%,

the textile un-- 7 based on the dry weight of the untreated textile. of washfast impregnant.

After impregnating the cellulosic textile with an aqueous dispersion containing the ingredients of both (A) and (B) or with a solution containing the ingredients of (B) only, the treated material is dried to remove most or substantially all of the liquid present therein, after which it is heated at a higher temperature of the order of about 135' C. to about 200' C. During this latter heat treatment a substantial loss of solids takes place, which may be as much as one-half to two-thirds of the total weight of the ingredients of (B) with which the cellulosic material initially was impresnlted. Hence, inordertoobtainafinished textilecontaining from 10to or,inthose cases where desired, up to 85 or by weight, based on the dry weight of the untreated textile, of washfast impregnant, the amount of solids in the textile as initially impregnated should be suillcient'ly high to allow for this weight loss of solids during the heat-treating and washing steps.

Inorderthatthoseskilledintheartbettermay understand how the prwent invention may be carried into eii'ect, the following examples are given by way of illustration and not by way of limitation. All'parts and percentages are by weight.

This example illustrates the preparation and use of a single-bath or "pad liquor" in carrying the present invention into effect.

Preparation of a dispersion of antimony trioride A small amount of dispersing agent, more particularly 13 parts of the sodium salt of a condensation product of formaldehyde and a naphthalene sulfonic acid (Tamol P) is dissolved in 57'! parts of water. Under rapid stirring with a homogenizing type of mixer, 410 parts of finely divided antimony trioxide is added to the solution. The resulting dispersion is then passed through a colloid mill to reduce the average particle size to 1 micron or less.

' Preparation of pad liquor A typical formula for the preparation of the pad liquor is as follows:

Park Monoguanidine phosphate 290 Cyanamide 145 Hexamethylene tetramine 20 Water 31s Antimony oxide dispersion (prepared as described above) 136 Aqueous dispersion containing 5546%, by

weight of an unplasticined vinyl chloride copolymer containing between and by weight of vinyl chloride in the copolymer 91 The monoguanidine phosphate, cyanamide and hexamethylene tetramine are added to the water met-Dd about 20% toabout5%, e. 3., about 15% to 10%, of an alkyl acrylate, more particularly a lower alkyl acrylate such, for instance, as

methyl, ethyl, propyl or butyl acrylate.

Treatment of fabrics A cellulosic fabric such, for example, as cotton clothoravlseoserayonfabricisimmersedinthe pad liquor and immediately passed through two rubber squeeze rolls, the presure being adjusted so that the so-called fwet pick-up" of pad liquor bythefahrieha %hyweightof the dry, imtreated fabric. After drying the untreated fabric, e. g., by heating at 60'-70 C., the dried fabric is heated at 100' C. for from 10 to 15 minutes. Thereafter the fabric is rinsed well in water to remove residual water-soluble substances therefrom, and again is dried (for instance at about co -w- (2.).

Iightysqmreeottonfabrictreatedasabove dcscribedhadadryadd-onof32% byweight oi the dry, untreated fabric. The results of verticaliiametestsofthisfahricwereasfollows: 3 inchcharlength after1and5washes,respectively,and0and4secondsafter-3lowafter land 5 washes, respecflvely.

This example illustrates the preparation and 03: two baths in carrying our invention into Bath 1 Parts Honoguanidine phosphate 290 Cyanamide Hexamethylenetetramine 20 Water 545 The above-named solid ingredients are dissolvedinthewaterbystirringandheatingat 0'-50C. Thepllofahathpreparedinthis manner-was.

Aqueous dkpersion containing 55-56% by weight of a vinyl chloride copolymer such as described under Example 1.- 199 Finely divided antimony trioxide 58 Dispersing agent, more particularly the sodium salt of a eondemation product of formaldehyde and naphthalene sulfonic acid (Tamol P) 2 Water 741 Treatment of fabrics Thesameprocedueisfollowedintreatinga eellulosic fabricwiththeingredientsofBath 1 asisdeseribedanderlxamplel. Thedryadd-on for 80 square cotton fabric that had been thusly treated was 19%. The treated, rinsed and dried fabric is then immersed in Bath 2 and immediately passed through rubber squeeze rolls, the pressure of which is adjusted so that the wet pick-up of the dispersion by the fabric is approximately 100% by weight of the dry fabric resulting from the initial treatment. The wet fabric is dried at a suitable temperature, e. g., by heating at 60-70 C. The additional dry add-on for the aforementioned 80 square cotton fabric was 12.6%. The subsequent heat treatment that was applied to the dried fabric was the same as in Example 1. The flame resistance of the final, treated 80 square cotton fabric was as follows: Vertical flame test-2% inches and 3%, inches char length and 1 second and 6 seconds afte.- low after 1 and washes, respectively.

The following examples are illustrative of further variations in the ingredients and proportions thereof that may be used in the preparation of the treating compositions of our invention and of their use in imparting flame-resisting characteristics to cellulosic materials of the kind described in the first paragraph of this specification, more particularly cotton cloth, using both one-bath and two-bath processes. The procedure, in general, was as follows:

Preparation of pad liquor A. FOB ONE-BATH PROCESS A dispersion of finely divided antimony trioxide was prepared as follows:

The dispersing agent was dissolved in the water, and the finely divided metallic oxide was incorporated slowly therein under high-speed stirring. After all the metallic oxide had been dispersed, the dispersion was passed through a. colloid mill (clearance: 0.002 inch). The particle size of the dispersed solid was, for the most part, one micron or less. Aggregates having a particle size up to 3 microns may be present in the dispersion.

The water-soluble salt of the oxygen-containing acid of phosphorus and the water-soluble nitrogenous substance, which ingredients are more specifically identified in the various tables which follow, were dissolved in water, using heat if necessary to effect solution. The above dispersion of the finely divided antimony trioxide and a dispersion of a thermally unstable thermoplastic substance containing at least 20% of combined halogen and capable of rupturing under heat at carbon-halogen bonds, e. g., a vinyl chloride polymerization product, more particularly a vinyl chloride copolymer of the kind described under Example 1, were then added to the solution of the other two ingredients, and the resulting mixture was thoroughly agitated to obtain a substantially homogeneous aqueous dispersion.

B. FOR TWO-BATH PROCESS The first bath comprises an aqueous solution of the water-soluble nitrogenous substance (cyanamide, dicyandiamide or a mixture thereof) and the water-soluble salt of the oxygen-containing acid of phosphorus. The second bath contains the dispersion of the finely divided antimony trioxide and of the halogen-containing thermoplastic substance.

Application to fabrics A. USING ONE-BATH PBocEss Weighed strips of the cotton fabric were impregnated with the pad liquor and passed between rubber squeeze rolls. The pressure on the rolls was adjusted so that a wet pick-up of not less than 110% was obtained; that is, the weight of the aqueous dispersion picked up, expressed as a percentage of the weight of the dry fabric, was not less than 110%. The treated fabrics were dried at 60-80 C. and then heated at a higher temperature in a forced-draft oven. The heated fabrics were thoroughly rinsed for 10 minutes in a container into which water was running. The fabric was dried at 60-80 C. and again weighed after allowing it to'stand for at least one hour in free contact with the atmosphere. The per cent add-on was determined by subtracting the initial dry weight from the final dry weight after rinsing, and dividing the difference by the initial dry weight and multiplying the quotient by 100.

B. USING TWO-BATH PROCESS The pad liquor or the first bath was applied to the fabric in exactly the same manner as inthe one-bath process.

The pad liquor of the second bath was applied to the fabric (pretreated as described above), using a wet pick-up of -125% and drying at 6080 C.

Washing procedure Flame tests Flame tests were made using a, specially constructed apparatus and a procedure which followed in general that given in ASTM Tentative Specifications Designation: D626-41T, issued 1941. Samples 2 /2 inches by 10 inches were cut with the long dimension parallel to the warp and others parallel to the fill. The apparatus consisted of a hood, a shield around the test piece, a Bunsen burner and a holder for the sample. The fabric to be tested was suspended vertically in the shield, which was placed in a hood with the fan off, the fabric being suspended in the shield by means of a clamp at the top and bottom. The door of the hood was then closed. The burner had previously been regulated to a luminous flame 1 inches high, and was placed under the suspended sample so that the end of the sample extended =54 inch into the fiame. The flame was held under the sample for 12 seconds and then extinguished. The duration of after-flaming of the sample was measured by means of a stop watch. And tendency of the sample to after-glow or smoke was noted and timed if possible. The total length of char in inches was measured by the tear length produced with a tearing weight equal to approximately 10% of the tearing strength of the unburned fabric.

The pH of the bath of pad liquor (pH of Bath 1 in the case of a two-bath process) as well as the pH of rinsings from the treated fabric after In this example the water-soluble salt of the oxygen-containing acid of phosphorus was either monoguanidine phosphate o monosodium phosphate. The water-soluble nitrogenous substance was cyanamide, the finely divided metallic oxide was finely divided antimony trioxide and the halogen-containing thermoplastic substance was a vinyl chloride copolymer such as that described under Examples 1 and 2, more particularly an unplasticised copolymer of, by weight, about 85% of vinyl chloride and about of an albl acrylate. The ingredients were applied by a twobath process, the second bath being an aqueous dispersion containing, by weight, 5.8% of antimony trioxide and 11% of the aforementioned copolymer. Further information on the treatment of 80 square cotton fabric and on the results I 12 square cotton fabric was 129 and 125, respectively; the dry add-on of the treated fabric was 3.1 and 16.1 from Baths 1 and 2, respectively. The results of the vertical fiame tests of theflltnl-I treated fabric were as follows: ff- Char length, 3 and 3% inches and after-glow. 1 and 9 seconds after 1- and 5 washes, respectively.

EXAMPLE8 In this example the water-soluble salt of the oxygen-containing acid of phosphorus was monoguanidine phosphate and the water-soluble nitrogenous substance was dicyandiamide. The ingredients which are given below in percentages by weight of the pad bath were applied by a onebath process to 80 square cotton fabric.

Ingredients: Percent by weight Water (including that introduced with the NH: as NHaOH) Remainder The pH of the pad bath was 7.2; the wet pickup of the treated fabricwas 117% and the dry obtained appear inTable I. add-on, 15.5%. Results of vertical fiame tests Table I w i m Ratio r Tm 3 Percent Total PM We Used flfifii i Add'on gff gf Vertical Charred Time After-Glow,

P I am in Length, Inches Sec.

Such HIPOI Bath 1 Bath 2 1 Wash 5 Washes 1 Wash 5 Washes Monoguanidlne hosphatm--. 1.0 use 1s 1s m as 4 e o 25 130.-.- p 1:7 l:4.4 l4 l8 5;: 5 4 21 Do 1:5 1:3. 1 l5 l6 4 6 Do 1:2 1:1.2 ll 17 3 3X Do 2:1 3.2:1 Z 18 6.6 7.4 4;: 4 5 2 Monoeodlum phosphate 1:1.2 1:1 16 19 4.3 5. 7 3 4 0 5 EXALIPLE 4 In this example the water-soluble salt of the were 3% and 4 inches char length and 1 and 5 seconds after-glowafter l and 5 washes, respectively.

EXAMPLE 7 Same as Example 2 with the exception that 145 parts of dicyandiamide was used in place of 145 parts of cyanamide, hexamethylene tetramine was omitted from the formulation, and the material which was treated was viscose rayon fabric weighing three and one-third ounces per square yard. The pH of Bath 1 was 4.2. The wet pickups of Baths 1 and 2 were 131 and respectively. The dry add-ons from Baths 1 and 2 were 13.1 and 18.5. respectively. The treated fabric had a char length, after a vertical flame test, of 3 inches and an after-glow of 5 seconds after 1 appear in Table II. 60 wash.

Table II Per Cent Dry Vertical Charred Tim. After-Glow, Total Add-On rial? pH Length, Inches Sec.

Bath mum's Bath 1 Bath 2 1 Wash owns 1 Wash 5 Washes 1s 1a 4.0 0-4 ex 4% s 5 EXAMPLE 5 10 It will be understood. of course. by those skilled Same as Example 2 with the exception that parts of dicyandiamide was used in place of 145 parts of cyanamide. The pH of Bath 1 was 4.6;

in the art that our invention is not limited to the particular ingredients, proportions thereof and application methods described in the above illus trative examples. As has been mentioned hereinthe percent wet pick-up of Baths 1 and 2 on 80 15 before, the water-soluble nitrogenous substance 13 i may be cyanamide, dicyandiamide, or any mi rture thereof, that is, mixtures of these substances in any proportions. We prefer to use cyanamide alone as the water-soluble nitrogenous substance.

Any water-soluble salt of an oxygen-containing acid of phosphorus wherein the phosphorus atom has a valence of 5, numerous examples of which have been given earlier herein and, also, in our aforementioned copending application maybe used, for instance:

Diguanidine polyphosphate Guanylurea phosphate Biguanide phosphate sodium dihydrogen phosphate Disodium hydrogen phosphate Dipotassium hydrogen phosphate Ammonium polyphosphate Ethylene diamine phosphate Ethylene diamine polyphosphate Primary cyclohexylamine phosphate Primary morpholine phosphate Secondary pyridine phosphate Mixtures of such salts may be employed as well as salts of mixtures of such acids which include orthophosphoric acid, metaphosphoric acid and pyrophosphoric acid, the mixed acids being sometimes collectively designated as polyphosphoric acid.

The oxide of antimony, more particularly antimony in'oxide, is an essential ingredient of the treating agents used in practicing our invention. It may act catalytically to accelerate dehalogenation of the thermally unstable, halogen-containing thermoplastic substance and to promote more rapid hydrohalide (i. e., hydrogen halide) is resistant to flame even after numerous laundering or dry-cleaning operationa, Furthermore, by using the ingredients within the proportions stated hereinbefore, a flame-resistant textile having a good hand or feeling to the touch and without excessive tendering (in many cases without any tendering) of the textile is obtained. As will be readily appreciated by those skilled in the textile art, the matter of hand or feeling to the touch is, for most applications, of considerable importance from both saleability and utility standpoints.

The fundamental treating compositions of this invention may be modified by incorporating formation at temperatures near that at which thermal decomposition of the cellulosic material occurs.

The thermoplastic substance may be any thermoplastic material (e. g., a vinyl resin, more particularly a vinyl halide polymerization product) containing at least 20%, more particularly at least 80% and preferably at least by weight of combined halogen (e. g., chlorine, bromine, etc.) and which is capable of rupturing under heat at carbon-halogen bonds, numerous examples of which materials have been given hereinbefore. Additional examples include the halogenated diphenyls (e. g., pentachlorodiphenyl, pentabromodiphenyl, etc.) and the halogenated (e. g., chlorinated, brominated, etc.) naphthalenes, which compounds contain at least 20% by weight of combined chlorine, bromine or other halogen. We prefer to use polyvinyl chloride or a vinyl chloride copolymer containing at least 80% by weight of combined (i. e., combined in the copolymer molecule) vinyl chloride, more particularly a copolymer of, by weight, from about 80% to about 99% of vinyl chloride and therein various modifying agents which aid in further improving the flame-resistant characteristics of the treated cellulosic material or which facilitate the technique of application. For instance, the compositions may also contain minor amounts (e. g., from 1 to 30% by weight of the total solids content) of such g ow retardants as the glow-retarding borates, phosphates. Pyrophosphates, etc., e. g., zinc borate, zinc phosphate, zinc ammonium phosphate, stannic phosphate, phenyl diamido phospate, melamine pyrophosphate, etc. Agents which have a buffering effect on the composition after being applied to the fabric or other textile, e. g., calcium carbonate, magnesium oxide, hexamethylene tetramine and other polyalkylene polyamines, etc., may be incorporated into the treating compositions as desired or as conditions may require.

The pH of the bath containing the ingredients of (B) in a two-bath process or the bath containing all of the ingredients in a one-bath process should be adjusted to a pH (glass electrode pH) within the range of from about 3 to about 7, e. g., a pH of from about 3 /2 or 4 to about 5 or 6, if the pH of the aqueou composition containing these ingredients (water-soluble salt of the oxygen-containing acid of phosphorus and water-soluble nitrogenous substance) is not initially within a pH range of from about 3 to about 7. Preferably the pH of the aqueous composition containing the ingredients of (B) is between 4 and 6, e. g., about 5.

The present invention is applicable to the production of a wide variety of flame-resistant cellulosic materials, e, g., wearing apparel of all kinds, especially children's clothes and clothing used by the armed forces, curtains, draperies, sheeting, furniture coverings, linings for electric blankets, net fabrics, non-woven fabrics, chenilles, etc., and which are made of cellulosic materials such as are described in the first paragraph of this specification and elsewhere herein. Other applications of the flame-resistant products of our invention include those described in Chapters VII and VIII of the aforementioned from about 20% to about 1% of an acrylic ester, 1

book, edited by Little, entitled Flameproofing Textile Fabrics.

The terms flame resistance and flame-resistant as used herein and in the appended claims with reference to cellulosic materials. specifically cellulosic textiles, are used generically to include within their meanings treated cellulosic materials (e. g., treated fabrics) which, after ignition, will continue to burn at a relatively slow rate as well as those which, after ignition, will burn over only a limited area beyond that directly exposed to the source of ignition and which may be specifically designated as fire-resistan cellulosic materials. It will be apparent from the examples herein given that most of the products of our invention properly fall within the specific 15 classiflcatimi of fire-resistant cellulosic materials.

The terms "textile" and "textile material as used generically herein and in the appended claims include withintheir meanings filaments, flbers, rovings, slivers, threads, yarns, twisted yarns, etc., as such or in woven, felted or otherwise formed fabrics, sheets, cloths and the like.

We claim: I

1. The method of imparting flame resistance to a cellulosic textile material of the class consisting of natural celluloses, regenerated celluloses. and mixmres thereof, said method comprising impregnating said material with an association of (1) an aqueous liquid composition having a pfloffromabout3toabout'landcontaining (6) ingredients initially in the form of a watersoluble salt of an oxygen-containing acid of phosphorus wherein the phosphorus atom has a valence of and a water-soluble nitrogenous substance of the group consisting of cyanamide, dicyandiamide and mixtures thereof, said salt of an oxygen-containing acid of phosphorus and said nitrogenous substance being employed in a weight ratio of 1 part of the former calculated asHsPQtoirom02to55partsofthelatter, and (2) an aqueous liquid composition containing (b) ingredients comprisin a finely divided oxide of antimony and a thermoplastic halogencontaining, organic substance having at least 20% by weight of combined halogen and capable of rupturing under heat at carbon-halogen bonds, said finely divided oxide of antimony and said thermoplastic substance being emplwed in a weight ratio of 1 part of the former to from 0.8 to 20 parts of the latter, and the said ingredients of (a) and (b) being employed in a weight ratio of 1 part of the latter to form 0.2 to 8 parts of the former; heatin the textile material after it has been impregnated with a composition comprising the aqueous liquid composition of (1) at a temperature within the range of about 135' C. to about 200 C. and washing the resulting material to remove any residual water-soluble substances therefrom, the total amount of the compositions of (1) and (2) with which the cellulosic material initially is impregnated being such that the finished fiame-resistanttextlle contains from about 10% to about 75% by weight, based on the dry weight of the untreated textile, of washfast impregnant.

2. A method as in claim 1 wherein the aqueous composition of 1) and the aqueous composition of (2) are applied simultaneously in a single bath.

3. A method as in claim 1 wherein the cellulosic textile material is a cotton textile material.

4. A method as in claim 1 wherein the cellulosic textile material is a viscose rayon textile material.

5. A flame-resistant cellulosic material of the class comisting of natural celluloses. regenerated celluloses and mixtures thereof, said material resulting from the method of claim 1.

6. An aqueous dispersion, suitable for us in imparting flame resistance to cellulosic textile materials selected from the group consisting of natural celluloses, regenerated celluloses and mixtures thereof, having a pH of from about 3 to about 'I and comprising (1) a finely divided oxide of antimony and (2) a thermoplastiehalogen-containing organic substance containing at least by weight of combined halogen and capable of rupturing under heat at carbon-halogen bonds, the ingredients of (1) and (2) which together are designated hereinafter as (A),being 18 employedinaw'eightratioofl partoftheformer tofrom0.6to20partsofthelatterandbeingdispersed in water containing ingredients initially in the form of (3) a water-soluble salt of an oxygencontaining acid of phosphorus wherein the phosphorus atom has a valence of 5 and (4) a watersoluble nitrogenous substance of the group consisting of cyanamide, dicyandiamide and mixtures thereof, the ingredients of (3) and (4) which together are designated hereinafter as (B), being employed in a weight ratio of 1 part of the former calculated as HsPOi to from 0.2 to 5.5 parts of the latter, and the ingredients of (A) and (B) being employed in a weight ratio of 1 part of the former to from 0.2 to 8 parts of the latter.

'1. An aqueous dispersion as in claim 8 wherein the finely divided oxide of antimony is antimony trioxide, the thermoplastic halogen-containing organic substance is a vinyl chloride polymerization product, the water-soluble salt or an oxygenccntaining acid of phosphorus is monoguanidine phosphate and the water-soluble nitrogenous substance is cyanamide.

8. A method of imparting flame resistance to a textile material comprising fibers of a cellulosic material of the class consisting of natural celluloses, regenerated celluloses, and mixtures thereof, said method comprising impregnating saidtextile material with the composition of claim 6, drying the impregnated material, heating the dried material at a temperature within the range of 135 C. to 200 C. and washing the resulting mata'ial to remove any residual water-soluble substances therefrom, the total amount or said ingredients of (A) and (B) with which the cellulosic textile material initially is impregnated being such that the finished flame-resistant textile contains from about 10% to about 50% by weight,

based on the dry weight of the untreated textile, of washfast impregnant.

9. A method of imparting flame resistance to a textile comprising fibers of a cellulosic material of the class consisting of natural celluloses, regenerated celluloses and mixtures thereof, said method comprising impregnating said textile with an aqueous dispersion having a pH of from about 3 to about 7 and comprising (1) a finely divided antimony trioxide and (2) a thermoplastic vinyl chloride polymerization product containing at least 40% by weight of combined chlorine, the ingredients of (1) and (2), which together are designated hereinafter as (A), being employed in a weight ratio of 1 part of the former to from 0.6 to 20 parts of the latter and being dispersed in water containing ingredients initially in the form of (3) a water-soluble guanidine phosphate and (4) cyanamide, the ingredients of (3) and (4), which together are designated hereinafter as (B), being employed in a weight ratio of 1 part of the former calculated as HJPO to from 0.3 to 4.5 parts of the latter, and the ingredients of (A) and (B) being employed in a weight ratio of 1 part of the former to from 0.2 to 8 parts of the latter. drying the impregnated material, heating the dried material at a temperature within the range or 135 C. to 200 C., and washing the resulting material to remove any residual watersoluble substances therefrom, the total amount of the ingredients of (A) and (B) with which the cellulosic textile material initially is impr gnated being such that the finished flame-resistant textile contains from about 10% to about by weight, based on the dry weight of the untreated textile, of washfast imp'regnant.

10. A method as in claim 9 wherein the water- 17 soluble guanidine phosphate of (3) is monoguanidine phosphate.

11. A method as in claim 9 wherein the aqueous dispersion also contains a small amount, not exceeding about 7% by weight of the ingredients of (B), of a polyalkylene polyamine having a boiling point substantially above 200 C.

12. A flame-resistant textile material of the class consisting of natural celluloses, regenerated celluloses and mixtures thereof, and which results from the method of claim 9.

13. A method of imparting flame resistance to a textile comprising fibers of a cellulosic material of the class consisting of natural celluloses, regenerated celluloses and mixtures thereof, said method comprising impregnating said textile with an aqueous solution having a pH within the range of from about 3 to about 7 and containing ingredients initially in the form of (1) a watersoluble salt of an oxygen-containing acid of phosphorus wherein the phosphorus atom has a valence of 5 and (2) a water-soluble nitrogenous substance of the group consisting of cyanamide, dicyandiamide and mixtures thereof, the ingreclients of (1) and (2), which together are designated hereinafter as (B), being employed in a weight ratio of 1 part of the former calculated as H3PC-i to form 0.2 to 5.5 parts of the latter; heating the impregnated textile at a temperature within the range of 135 C. to 200 0.; washing flle of this patent:

0.6 to 20 parts of the latter, the ingredients of (A) and (B) being employed in a weight ratio of 1 part of the former to from 0.2 to 8 parts of the latter and the total amount of the ingredients of (A) and (B) with which the said textile is impregnated being such that the finished flameresistant textile contains from about 10% to about 75% by weight, based on the dry Weight of the untreated textile, of washfast impregnant.

14. A flame-resistant cellulosic textile material of the class consisting of natural celluloses, regenerated celluloses and mixtures thereof, and which results from the method of claim 13.

15. A method as in claim 13 wherein the watersoluble salt of an oxygen-containing acid of phosphorus is a guanidine phosphate, the watersoluble nitrogenous substance is cyanamide, the finely divided oxide of antimony is antimony trioxide and the thermoplastic halogen-containing substance is a vinyl resin containing at least 40% by weight of combined chlorine.

16. A method as in claim 15 wherein the textile is a, cotton fabric material.

17. A method as in claim 15 wherein the watersoluble guanidine phosphate is monoguanidine phosphate.

ANNE MACNIILLAN LOUKOMSKY. ROY H. KIENLE. THEODORE F. COOKE.

REFERENCES CITED The following references are of record in the UNITED STATES PATENTS Number Name Date 2,178,625 Clayton et al Nov. 7, 1939 2,286,308 Rosser June 16, 1942 2,413,163 Bacon Dec. 24, 1946 2,427,997 White Sept. 23, 1947 Certificate of Correction Patent No. 2,520,103 August 22, 1950 ANNE MACMILLAN LOUKOMSKY ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 1, line 20, for the word use read us; column 10 line 66, for And read Any; column 14, line 25, for phospate read phosphate; column 15, line 38, and column 17 line 28, for form read from; and that the said Letters Patent should be read as corrected above, so that the same may conform to the record of the case in the Patent Oflice. Signed and sealed this 2nd day of January, A. D. 1951.

THOMAS F. MURPHY,

Assistant Uommz'ssz'oner of Patents.

Claims

1. THE METHOD OF IMPARTING FLAME RESISTANCE TO A CELLULOSIC TEXTILE MATERIAL OF THE CLASS CONSISTING OF NATURAL CELLULOSES, REGENERATED CELLULOSES AND MIXTURES THEREOF, SAID METHOD COMPRISING IMPREGNATING SAID MATERIAL WITH AN ASSOCIATION OF (1) AN AQUEOUS LIQUID COMPOSITION HAVING A PH OF FROM ABOUT 3 TO ABOUT 7 AND CONTAINING (A) INGREDIENTS INITIALLY IN THE FORM OF A WATERSOLUBLE SALT OF AN OXYGEN-CONTAINING ACID OF PHOSPHORUS WHEREIN THE PHOSPHORUS ATOM HAS A VALENCE OF 5 AND A WATER-SOLUBLE NITROGENOUS SUBSTANCE OF THE GROUP CONSISTING OF CYANAMIDE, DICYANDIAMIDE AND MIXTURES THEREOF, SAID SALT OF AN OXYGEN-CONTAINING ACID OF PHOSPHORUS AND SAID NITROGENOUS SUBSTANCE BEING EMPLOYED IN A WEIGHT RATIO OF 1 PART OF THE FORMER CALCULATED AS H3PO4 TO FROM 0.2 TO 5.5 PARTS OF THE LATTER, AND (2) AN AQUEOUS LIQUID COMPOSITION CONTAINING (B) INGREDIENTS COMPRISING A FINELY DIVIDED OXIDE OF ANTIMONY AND A THERMOPLASTIC HALOGENCONTAINING, ORGANIC SUBSTANCE HAVING AT LEAST 20% BY WEIGHT OF COMBINED HALOGEN AND CAPABLE OF RUPTURING UNDER HEAT AT CARBON-HALOGEN BONDS, SAID FINELY DIVIDED OXIDE OF ANTIMONY AND SAID THERMOPLASTIC SUBSTANCE BEING EMPLOYED IN A WEIGHT RATIO OF 1 PART OF THE FORMER TO FROM 0.6 TO 20 PARTS OF THE LATTER, AND THE SAID INGREDIENTS OF (A) AND (B) BEING EMPLOYED IN A WEIGHT RATIO OF 1 PART OF THE LATTER TO FORM 0.2 TO 8 PARTS OF THE FORMER; HEATING THE TEXTILE MATERIAL AFTER IT HAS BEEN IMPREGNATED WITH A COMPOSITION COMPRISING THE AQUEOUS LIQUID COMPOSITION OF (1) AT A TEMPERATURE WITHIN THE RANGE OF ABOUT 135*C. TO ABOUT 200*C.; AND WASHING THE RESULTING MATERIAL TO REMOVE ANY RESIDUAL WATER-SOLUBLE SUBSTANCES THEREFROM, THE TOTAL AMOUNT OF THE COMPOSITIONS OF (1) AND (2) WITH WHICH THE CELLULOSIC MATERIAL INITIALLY IS IMPREGNANTED BEING SUCH THAT THE FINISHED FLAME-RESISTANT TEXTILE CONTAINS FROM ABOUT 10% TO ABOUT 75% BY WEIGHT, BASED ON THE DRY WEIGHT OF THE UNTREATED TEXTILE, OF WASHFAST IMPREGNANT.