US3855288A - Methylolphosphoric triamides - Google Patents

Methylolphosphoric triamides Download PDF

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US3855288A
US3855288A US00261813A US26181372A US3855288A US 3855288 A US3855288 A US 3855288A US 00261813 A US00261813 A US 00261813A US 26181372 A US26181372 A US 26181372A US 3855288 A US3855288 A US 3855288A
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triamide
fabric
methylolphosphoric
fabrics
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P Burke
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EIDP Inc
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EI Du Pont de Nemours and Co
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    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
    • D06M15/00—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment
    • D06M15/19—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment with synthetic macromolecular compounds
    • D06M15/37—Macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
    • D06M15/39—Aldehyde resins; Ketone resins; Polyacetals
    • D06M15/423—Amino-aldehyde resins
    • D06M15/43—Amino-aldehyde resins modified by phosphorus compounds
    • D06M15/433—Amino-aldehyde resins modified by phosphorus compounds by phosphoric acids
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
    • C07F9/00—Compounds containing elements of Groups 5 or 15 of the Periodic Table
    • C07F9/02—Phosphorus compounds
    • C07F9/06—Phosphorus compounds without P—C bonds
    • C07F9/22—Amides of acids of phosphorus
    • C07F9/224—Phosphorus triamides
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/49—Phosphorus-containing compounds
    • C08K5/51—Phosphorus bound to oxygen
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L1/00—Compositions of cellulose, modified cellulose or cellulose derivatives
    • C08L1/02—Cellulose; Modified cellulose
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L61/00—Compositions of condensation polymers of aldehydes or ketones; Compositions of derivatives of such polymers
    • C08L61/20—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen
    • C08L61/26—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen of aldehydes with heterocyclic compounds
    • C08L61/28—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen of aldehydes with heterocyclic compounds with melamine
    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
    • D06M13/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment
    • D06M13/244—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment with compounds containing sulfur or phosphorus
    • D06M13/282—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment with compounds containing sulfur or phosphorus with compounds containing phosphorus
    • D06M13/292—Mono-, di- or triesters of phosphoric or phosphorous acids; Salts thereof

Definitions

  • ABSTRACT Methylolphosphoric triamides for examples, hexamethylolphosphoric triamide, useful for rendering combustible cellulosic fabrics flame resistant.
  • Phosphorus-containing compounds are well known for their ability to impart flame resistance to fabrics.
  • Compounds which are known for this purpose include tetra(hydroxymethyl)-phosphonium chlorides, aziridinyl phosphine oxides and the methylol amide of the dimethyl ester of bis(carboxyethyl)-phosphonic acid.
  • Many of the prior art compounds may be undesirable as flame retardants for fabrics because they stiffen the fabric, because of their toxicity, because they must be employed in large quantities to impart any significant flame resistance to the fabric, or because they are readily removable by laundering.
  • German Pat. No. 1,009,629 discloses flame retarding phosphorus compounds which are obtained by treating phosphoric triamide with formaldehyde and methanol.
  • the product which includes phosphorus esters and hexamethylenetetramine, appears to lack durability to laundering.
  • British Pat. No. 1,222,885 discloses as flame retardants for cellulosic materials, compounds or combinations of compounds which contain nitrogen and phosphorus. It further discloses that fabrics treated with such a compound or combination of compounds have a good degree of flame resistance if the nitrogen content is equal to or greater than 6 minus 4 times the phosphorus content and, preferably, is at least 2.5 times the phosphorus content, with the preferred amounts of nitrogen and phosphorus totaling at least 3.5 percent, based on the weight of fabric.
  • Exemplary of compounds containing both nitrogen and phosphorus are phosphoric triamides (phosphoramides) having the formula i wherein R is substituted or unsubstituted C alkyl, with hydroxyalkyl being a preferred substituted alkyl group.
  • US. Pat. No. 2,661,342 discloses that combustible cellulosic materials can be rendered flame resistant with a resinous aminoplast condensation product in combination with the reaction product of phosphorus oxychloride and ammonia, the reaction product having a nitrogen to phosphorus atomic ratio of 2.1 to 2.3 and a molecular weight of 180 to 300.
  • Aminoplast condensation products are defined therein as resins derived from amino (including imino) or amido (including imido)) compounds, a typical example being a ureaformaldehyde resin (Modern Plastics 17, 433, 1939). Other aminoplast resins are described by C. Ellis in Chemistry of Synthetic Resins," Chapter 26, Reinhold Publishing Co., 1935.
  • the present invention resides in the discovery of methylolphosphoric triamides which are useful for imparting flame resistance to combustible cellulosic materials, the triamides having the formula wherein at least one of the six R groups is Cl-l Ol-l and the remainder if any are 1-1, said triamide being characterized by the presence in its P,31 nuclear magnetic resonance (NMR) spectrum of a band in the range 15-20 ppm. downfield from percent aqueous phosphoric acid as external standard.
  • the invention includes the process of applying such triamides to combustible cellulosic materials and, also, the materials which are made flame resistant with such triamides.
  • methylolphosphoric triamides as defined above are more effective than prior art compounds of similar structure in imparting flame resistance to combustible cellulosic materials, such as fabrics, and that fabrics can be treated with such methylolphosphoric triamides without substantial alteration of their physical characteristics, such as stiffness or hand.
  • the methylolphosphoric triamides of this invention contain one to six methylol substituents (designated as R in the formula). The remaining nitrogen substituents if any (also designated as R in the formula) are hydrogen.
  • n methylol groups the number of methylol groups in the compound of the above formula
  • n the value 1 to 6.
  • 6-n the number of hydrogen atoms in the compound of the above formula
  • the compounds of this invention are all water soluble. As the number n of methylol groups increases, the compounds become more hygroscopic. Analyses of the compounds of this invention by nuclear magnetic resonance show that when the three nitrogen atoms are less than completely substituted with methylol groups, that is, n is less than 6, the compounds are actually mixtures of compounds. It is to be understood, therefore, that the n values reported for such mixtures represent average values, and further, that n need not be a whole number. When the nitrogen atoms are completely substituted with methylol groups (n is 6), the triamide exhibits a single P-3l NMR peak at 16.9 ppm.
  • the triamide When n is 1 but less than 6, the triamide exhibits a P-31 NMR peak in the range 15-20 ppm. When n is about 3, there is an unsymmetrical peak at about 18.3 ppm. At higher values of n this peak shifts in its center to a lower resonance value; at lower values of n, to a higher resonance value.
  • the compounds of this invention can be prepared by reacting phosphoric triamide and formaldehyde, for example, as a 37 weight percent aqueous solution, in an aqueous medium having a pH of 7-1 1, preferably 9.5-10.5, obtained by the addition of a base, until the P-31 NMR spectrum of the reaction mixture downfield from 85 percent phosphoric acid as the external standard shows peaks in a band at -20 ppm.
  • the signal at 22.5 ppm. indicating unreacted phosphoric triamide disappears; normally, this occurs when n exceeds about 1.5.
  • the reaction proceeds readily at 5-50C., preferably at -25C., and phosphoric triamide readily binds as many as 6 molar equivalents of formaldehyde.
  • the reaction is completed in 1.5-2 hours.
  • the NMR spectrum after 15 minutes exhibits two signals in a band at 15-20 ppm. and after about 90 minutes exhibits a peak in this range, the peak being centered according to the value of n.
  • the P-3l NMR spectrum provides a ready means of monitoring the reaction.
  • the pH is decreased, for example, by the addition of hydrochloric acid, to 6.5-7.5, preferably to 6.9-7.3.
  • a curing catalyst and/or an aminoplast resin precondensate can be added at this stage, either immediately or after the reaction mixture is diluted with water to the desired methylolphosphoric triamide concentration.
  • the compounds of this invention can be isolated by neutralizing the reaction mixture after completion of the reaction, for example, by adjusting the pH to 7.1-7.5, and the vacuum stripping off the solvent at a solution temperature not in excess of 50C.
  • the isolated compounds are solids or viscous liquids which can be redissolved in aqueous media, from which the compounds can be applied to the combustible cellulosic material which is to be rendered flame resistant.
  • n is less than 6
  • aqueous solutions generally should be employed within about 4 hours of preparation in order to impart durable flame resistance.
  • the instability of such aqueous solutions is evident from a study of the P-31 NMR spectrum.
  • the P-31 NMR spectrum becomes more complex and there may be noted a decrease in the amount of material having peaks in the 15-20 ppm. range.
  • the flame resistance imparted to combustible cellulosic materials with such aged aqueous solutions is less fast to laundering.
  • the efflciency, on a weight basis, of the compounds of this invention varies with the value of n.
  • Combustible cellulosic materials are most efficiently rendered flame resistant by the (monoto tri-lmethylol compounds, less efficiently by the (tetrato hexa-)methy1ol compounds.
  • Preferred are the (diand tri-)methylol compounds. Only slight loss of hand accompanies treatment of fabrics with the (monoto tri-)methylol compounds while a greater loss of hand accompanies the use of the (tetrato hexa-)methylol compounds.
  • the flame resistance imparted to combustible cellulosic materials by the compounds of this invention is made durable to laundering by curing the compounds after they have been applied to the substrates from an aqueous solution.
  • the material is dried by heating at a temperature up to C, preferably at 100-115C.
  • Curing is effected by heating the dried material at -190C., preferably at -170C., in the presence of an acidic curing catalyst for 2-10 minutes, preferably 2-4 minutes.
  • the cat- 1 alyst usually is dissolved in the aqueous solution of methylolphosphoric triamide before the latter is applied to the material being treated.
  • the catalyst usually is added to such aqueous solution, such as a padbath, in an amount which is 0.5-5 weight percent, preferably 1-2.5 percent, based on the weight of the solution.
  • aqueous solution such as a padbath
  • the drying and curing steps can be carried out at the curing temperature.
  • Preferred curing catalysts are acids which are relatively nonvolatile at curing temperatures and latent acid compounds.
  • acids include oxalic, glycolic, lactic, malic, tartaric, succinic and citric acids, ammonium chloride, ammonium sulfates, ammonium phosphates, such as diammonium acid phosphate, acid salts of organic amines, such as 2-methyl-2- aminopropanol-l hydrochloride and tris(2-hydroxyethyl)amine hydrochloride, and salts of weakly basic metals and strong acids, such as zinc nitrate, zinc chloride, zinc fluoborate, magnesium chloride and magnesium nitrate.
  • the compounds of this invention impart flame resistance to'combustible cellulosic materials by their application to or incorporation into the material in amounts of 10-60 weight percent, based on the dry weight of the material being treated. Generally, the amount added is 14-50 percent, preferably 14-25 percent.
  • the compounds can be applied or incorporated in any suitable fashion. Conveniently, they are applied as 5-65 weight percent aqueous solutions by a padding operation; preferably, the aqueous solution contains 15-50 percent of a methylolphosphoric triamide of this invention.
  • the aqueous solution of methylolphosphoric triamide can contain wetting agents, for example, non-ionic wetting agents, to facilitate wetting of the cellulosic material being treated. Included among such wetting agents are polyethylene oxides obtained by reacting a phenol or a monohydric or polyhydric aliphatic alcohol with ethylene oxide. Such wetting agents generally are added so as to comprise 0.01-0.15 weight percent of the aqueous triamide solution.
  • wetting agents for example, non-ionic wetting agents, to facilitate wetting of the cellulosic material being treated.
  • wetting agents include polyethylene oxides obtained by reacting a phenol or a monohydric or polyhydric aliphatic alcohol with ethylene oxide.
  • Such wetting agents generally are added so as to comprise 0.01-0.15 weight percent of the aqueous triamide solution.
  • the padbath for example, the preparative reactive mixture described above, at a pH of 6.5-7.5, is padded onto the substrate to the extent of 50-120 percent, based on the dry weight of substrate, preferably to the extent of 60-90 percent.
  • Padding can be effected by soaking the fabric in the padbath and squeezing out the excess solution, thus providing control of the net amount of solution applied to or picked up by the fabric, The fractions of the solutions retained by and squeezed out of the fabric are of essentially the same composition.
  • the curing catalyst is incorporated into the padbath. Drying and curing are carried out as previously described. Conveniently, continuously circulating hot air can be employed as a heat source, especially for the drying operation.
  • the solutions of the compounds of this invention can be sprayed, in controlled amounts, onto moving fabrics.
  • the compounds of this invention can be employed in combination with well-known aminoplast resin condensates which, in some instances, improve the effectiveness of the compounds of this invention in rendering cellulosic materials flame resistant. It also has been discovered that the aminoplast resins, in some instances, improve the durability of the compounds of this invention when both have been coapplied to the substrate.
  • Aminoplast resins are well known in the art and have been discussed hereinabove. Many such resins are known to impart flame resistance to cellulosic materials. They often are applied as water soluble precondensate compounds. When such precondensates are employed herein, they are dissolved in the freshly prepared solution of the methylolphosphoric triamide, which solution then is preferably used promptly to treat the fabric, for example, within about 4 hours.
  • a methylolphosphoric triamide of this invention When a methylolphosphoric triamide of this invention is employed in combination with a water soluble aminoplast resin precondensate, less than the previously recited amounts of the triamide are necessary to impart the desired flame resistant characteristics to the cellulosic material being treated.
  • the methylolphosphoric triamide When used in such a combination, the methylolphosphoric triamide is incorporated into or applied to the material in amounts 7-15 weight percent, preferably 8-l2 percent, based on the dry weight of material being treated.
  • the amount of aminoplast precondensate added in combination with the trimethylolphosphoric triamide is known from the art.
  • the aminoplast resin precondensate is a hydroxymethylmelamine, a convenient amount is 7-13 weight percent, based on the dry weight of material being treated, preferably 7-10 percent.
  • Water soluble aminoplast resin precondensate compounds useful with the compounds of this invention include those containing at least two moles of condensed formaldehyde, as N-hydroxymethyl or N-alkoxymethyl groups wherein the alkoxy group contains 1-4 carbon atoms.
  • Precondensate compounds include polymethylol derivatives, as well as their partial or complete ethers, of amides such as urea, thiourea, guanidine and dicyandiamide, for example, dimethylolurea, tetramethylol urea, di(methoxymethyl)urea, dimethylolquanidine, trimethylol quanidine and dimethyloldicyandiamide.
  • Precondensate compounds of substituted ureas can also be used, such as formaldehyde condensates, and their ethers, of ethylene urea.
  • Particular examples of these include dimethylolethyleneurea, dimethylolmethyleneurea, tetramethylolacetylenediurea, trimethylolbiuret, di(methoxymethyl)uron and di(methoxymethyl) triazone.
  • Still other precondensate compounds include the reaction products of formaldehyde and triazines such as melamine, diaminotriazine, formoguanamine and 2-chloro-4,6-diaminotriazine.
  • Preferred examples of such precondensates include diand trimethylolmelamine, optionally partially methylated, hexa(methoxymethyl)melamine, tetramethyloldiaminotriazine and tetramethylol-2-chloro-4,6-diaminotriazine.
  • Diazines and azoles are also useful aminoplast resin precondensate compounds. Typical of these are precondensates based on 2,4-diamino-l,3-diazine, guanazole and diaminopyrrole.
  • the compounds of this invention and their combinations with aminoplast resin precondensate compounds are particularly effective on combustible cellulosic materials of a fibrous nature.
  • this includes cotton, the preferred fiber, linen, viscose rayon, cuprammonium rayon, jute, hemp and ramie.
  • Such cellulosic material can be treated in the form of raw fiber, carded stock, rovings, thread, yarn and felts as well as inthe form of knitted and woven fabrics.
  • the cellulosic material need not be fibrous to be rendered fire resistant with the compounds of this invention; any cellulosic material can be treated if it can be penetrated or swollen by water, thus permitting penetration by the aqueous medium containing the methylolphosphoric triamide. Fibrous cellulosic material can be rendered flame resistant with the compounds of this invention even though it is blended with other fibers, for example, natural animal fibers such as wool and synthetic fibers such as linear polyamide, linear polyester and polyacrylic fibers.
  • Cellulosic materials which have been rendered flame resistant with the compounds of this invention are especially useful in tents, stage scenery, upholstery fabrics, slipcovers, draperies, wearing apparel for personnel in close contact with fire or heat, bedding, nightclothes, tarpaulins, insulation, padding, rope, string and twine. Fabrics which have been treated with the compounds of this invention are flame resistant throughout, not just on their surfaces.
  • Hand the softness of a treated fabric relative to untreated fabric as the control. It is graded subjectively here on a scale of l to 5 in which 5 signifies a softness and flexibility virtually indistinguishable from the control and l signifies great stiffness relative to the control
  • Padding wetting the fabric with the aqueous triamide solution and then running the wet fabric between rollers to squeeze out liquid which is in excess of the desired pickup on the fabric.
  • Laundering also expressed as home washing (HW): exposing the fabric to a standard laundering cycle, employing a washing solution of 100 grams of a commercial detergent (Tide) per 15 gallons of water, and tumble drying the washed fabric.
  • HW home washing
  • Limiting Oxygen lndex determined with a -inch by 2-inch piece of fabric spread lengthwise in a vertical plane and supported along its vertical edges.
  • the spread fabric is positioned inside a transparent circular (cylindrical) column open only at the top.
  • the top of the column is one or more inches above the spread fabric.
  • the interior of the column is provided with an upward flow, from its base, of a gaseous mixture of pure oxygen and pure nitrogen.
  • the volume flow rate of each gas making up the mixture is instrumented and manually adjustable.
  • the spread fabric is ignited from the top while gas mixture flows up the column. The flow rates of the nitrogen and oxygen are adjusted until the flame on the ignited fabric just goes out.
  • the ratio of the volume flow of oxygen to the sum of the volume flows of oxygen and nitrogen is then calculated.
  • This value called the Limiting Oxygen Index or LOl, is the average of two determinations.
  • untreated 8-oz. cotton twill used in the following examples to test the effectiveness of the compounds of this invention has an LOI value of 0. 1 80fl).002 and is completely burned up in the vertical flame test. Air contains about 21 mole percent oxygen; therefore, fabrics with LOl values below about 0.210 can be expected to burn freely in a candlelike manner (from the top to the bottom) in air. For commercial applications, an LOI value of at least about 0.260-0.270 is considered acceptable.
  • a 2.75- inch by -inch fabric sample is held in the specimen holder by its vertical edges and the specimen holder is hung centrally by the holder brackets.
  • the igniting flame is applied so that 0.75 inch of the lower end of the fabric is in the flame. This exposure is continued for 3.0 seconds and the flame is removed. After the flame has extinguished itself, the sample is removed from the holder.
  • a hook with an attached weight is inserted into the sample on one side of the charred area 0.25 inch from the outside edge and 0.25 inch from the lower edge. For 2.0 to 6.0-oz. per square yard fabric, the attached weight is 0.25 pound; for over 6.0 and up to and including 15-oz. per square yard fabric, a 0.50 pound weight is used.
  • EXAMPLE 1 Trimethylolphosphoric Triamide Preparation 9.5 Parts (0.1 mole) of phosphoric triamide, prepared according to Klement and Koch, Berichte 87, 338 (1954) and 25 parts of 37 percent aqueous formaldehyde (0.3 mole) were mixed at 20C. and the pH of the resulting solution was adjusted to 10.3 with 20 percent aqueous sodium hydroxide. The solution was allowed to stand for 2.5 hours, after which time the pH of the solution had dropped to 9.9 and the P-3 1 NMR spectrum showed a band between 15 and 20 ppm. with an unsymmetrical peak centered at 18.3 ppm.; the spectrum was free of a signal at 22.5 ppm.
  • PTA phosphoric triamide
  • curing agent 0.5 weight percent ammonium chloride
  • TMM trimethylolmelamine
  • EXAMPLE 5 8.7 7 0.293 Dimethylolphosphoric Triamide/Trimethylolmela- 0 0-243 19.5 0 0.290 mine Treatment of Cotton Blend Fabrics 241 0 197 Dimethylolphosphoric triamide was prepared in solution from phosphoric triamide (PTA) according to the EXAMPLE 7 procedure of Example 1 except that 16.7 parts, instead of 25 parts, of aqueous formaldehyde were employed.
  • PTA phosphoric triamide
  • Trlmethylolphosphorlc TrldlKile/Ammoplast Resm Six padbaths were prepared from the solution, each Treatment of Cotton FaPnc neutralized to pH 7.2 and containing trimethylolmela- SlX aqueous padbaths (designated A through were mine (TMM) and .05 w i h percent f ammonium prepared so as to contain, per 100 parts of solution, 12 chloride (curing agent). The padbaths were padded Parts of lrlmethylolphosphonc trlamlde; 1 P of onto commercial lightweight, 2.8-oz. and 53-02.
  • trimeangdglolldtiiae t D 5 31 thylolphosphoric triam de was prepared from phosgfi fi phoric triamide according to the procedure described 3-pi g -5. 17 in Example 1.
  • Padbaths were prepared in a manner mazme- W 87 79 77 70 56 70 similar to that described in Example 5.
  • the impregam nated fabrics (8-ounce cotton twill fabric) were dried at 115C., cured at 165-l75C. and given one home wash.

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  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
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  • Polymers & Plastics (AREA)
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  • Treatments For Attaching Organic Compounds To Fibrous Goods (AREA)

Abstract

Methylolphosphoric triamides, for examples, hexamethylolphosphoric triamide, useful for rendering combustible cellulosic fabrics flame resistant.

Description

United States Patent [191 Burke Dec. 17, 1974 METHYLOLPHOSPl-IORIC TRIAMIDES [75] Inventor: Patrick Michael Burke, Wilmington,
Del.
[73] Assignee: E. I. du Pont de Nemours and Company, Wilmington, Del.
22 Filed: I June 12,1972
21 Appl.No.: 261,813
FOREIGN PATENTS OR APPLICATIONS OTHER PUBLICATIONS Hellmann, Newer Method of Preparative Organic Chemistry, Vol. II, p 278-79 (Edited by Foerst) (Academic Press, NY.) (1963).
Primary E.\'aminerHarry l. Moatz [57] ABSTRACT Methylolphosphoric triamides, for examples, hexamethylolphosphoric triamide, useful for rendering combustible cellulosic fabrics flame resistant.
6 Claims, N0 Drawings Great Britain 260/551 METHYLOLPHOSPHORIC TRIAMIDES BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to methylolphosphoric triamidcs.
2. Description of the Prior Art Phosphorus-containing compounds are well known for their ability to impart flame resistance to fabrics. Compounds which are known for this purpose include tetra(hydroxymethyl)-phosphonium chlorides, aziridinyl phosphine oxides and the methylol amide of the dimethyl ester of bis(carboxyethyl)-phosphonic acid. Many of the prior art compounds may be undesirable as flame retardants for fabrics because they stiffen the fabric, because of their toxicity, because they must be employed in large quantities to impart any significant flame resistance to the fabric, or because they are readily removable by laundering.
German Pat. No. 1,009,629 discloses flame retarding phosphorus compounds which are obtained by treating phosphoric triamide with formaldehyde and methanol. The product, which includes phosphorus esters and hexamethylenetetramine, appears to lack durability to laundering.
British Pat. No. 1,222,885 discloses as flame retardants for cellulosic materials, compounds or combinations of compounds which contain nitrogen and phosphorus. It further discloses that fabrics treated with such a compound or combination of compounds have a good degree of flame resistance if the nitrogen content is equal to or greater than 6 minus 4 times the phosphorus content and, preferably, is at least 2.5 times the phosphorus content, with the preferred amounts of nitrogen and phosphorus totaling at least 3.5 percent, based on the weight of fabric. Exemplary of compounds containing both nitrogen and phosphorus are phosphoric triamides (phosphoramides) having the formula i wherein R is substituted or unsubstituted C alkyl, with hydroxyalkyl being a preferred substituted alkyl group.
US. Pat. No. 2,661,342 discloses that combustible cellulosic materials can be rendered flame resistant with a resinous aminoplast condensation product in combination with the reaction product of phosphorus oxychloride and ammonia, the reaction product having a nitrogen to phosphorus atomic ratio of 2.1 to 2.3 and a molecular weight of 180 to 300. Aminoplast condensation products are defined therein as resins derived from amino (including imino) or amido (including imido)) compounds, a typical example being a ureaformaldehyde resin (Modern Plastics 17, 433, 1939). Other aminoplast resins are described by C. Ellis in Chemistry of Synthetic Resins," Chapter 26, Reinhold Publishing Co., 1935.
SUMMARY OF THE INVENTION It is an object of this invention to provide compositions which are highly effective in imparting flame resistance to combustible cellulosic materials. Another object is to provide phosphorus-containing compositions which impart flame resistance to such cellulosic materials. Still another object is to provide flame resis' tant cellulosic materials. A further object is to provide such flame resistant materials which are durable to laundering. Still another object is to provide a method for imparting flame resistance to combustible cellulosic materials, which method employs aqueous solutions of phosphorus-containing compounds.
In summary, the present invention resides in the discovery of methylolphosphoric triamides which are useful for imparting flame resistance to combustible cellulosic materials, the triamides having the formula wherein at least one of the six R groups is Cl-l Ol-l and the remainder if any are 1-1, said triamide being characterized by the presence in its P,31 nuclear magnetic resonance (NMR) spectrum of a band in the range 15-20 ppm. downfield from percent aqueous phosphoric acid as external standard. The invention includes the process of applying such triamides to combustible cellulosic materials and, also, the materials which are made flame resistant with such triamides.
DETAILED DESCRIPTION OF THE INVENTION This invention is based upon the discovery that the methylolphosphoric triamides as defined above are more effective than prior art compounds of similar structure in imparting flame resistance to combustible cellulosic materials, such as fabrics, and that fabrics can be treated with such methylolphosphoric triamides without substantial alteration of their physical characteristics, such as stiffness or hand. As noted above, the methylolphosphoric triamides of this invention contain one to six methylol substituents (designated as R in the formula). The remaining nitrogen substituents if any (also designated as R in the formula) are hydrogen. In order to simplify the following discussion, the number of methylol groups in the compound of the above formula will be designated as n methylol groups, with n having the value 1 to 6. correspondingly, the number of hydrogen atoms in the compound of the above formula will be designated 6-n.
The compounds of this invention are all water soluble. As the number n of methylol groups increases, the compounds become more hygroscopic. Analyses of the compounds of this invention by nuclear magnetic resonance show that when the three nitrogen atoms are less than completely substituted with methylol groups, that is, n is less than 6, the compounds are actually mixtures of compounds. It is to be understood, therefore, that the n values reported for such mixtures represent average values, and further, that n need not be a whole number. When the nitrogen atoms are completely substituted with methylol groups (n is 6), the triamide exhibits a single P-3l NMR peak at 16.9 ppm. When n is 1 but less than 6, the triamide exhibits a P-31 NMR peak in the range 15-20 ppm. When n is about 3, there is an unsymmetrical peak at about 18.3 ppm. At higher values of n this peak shifts in its center to a lower resonance value; at lower values of n, to a higher resonance value.
The compounds of this invention can be prepared by reacting phosphoric triamide and formaldehyde, for example, as a 37 weight percent aqueous solution, in an aqueous medium having a pH of 7-1 1, preferably 9.5-10.5, obtained by the addition of a base, until the P-31 NMR spectrum of the reaction mixture downfield from 85 percent phosphoric acid as the external standard shows peaks in a band at -20 ppm. Preferably, the signal at 22.5 ppm. indicating unreacted phosphoric triamide disappears; normally, this occurs when n exceeds about 1.5. The reaction proceeds readily at 5-50C., preferably at -25C., and phosphoric triamide readily binds as many as 6 molar equivalents of formaldehyde. Under the preferred conditions the reaction is completed in 1.5-2 hours. The NMR spectrum after 15 minutes exhibits two signals in a band at 15-20 ppm. and after about 90 minutes exhibits a peak in this range, the peak being centered according to the value of n. The P-3l NMR spectrum provides a ready means of monitoring the reaction. After completion of the reaction, the pH is decreased, for example, by the addition of hydrochloric acid, to 6.5-7.5, preferably to 6.9-7.3. A curing catalyst and/or an aminoplast resin precondensate (both discussed hereinafter) can be added at this stage, either immediately or after the reaction mixture is diluted with water to the desired methylolphosphoric triamide concentration.
Although it is preferred to use the compounds of this invention directly as formed in solution in the reaction mixture, they can be isolated by neutralizing the reaction mixture after completion of the reaction, for example, by adjusting the pH to 7.1-7.5, and the vacuum stripping off the solvent at a solution temperature not in excess of 50C. The isolated compounds are solids or viscous liquids which can be redissolved in aqueous media, from which the compounds can be applied to the combustible cellulosic material which is to be rendered flame resistant.
The compounds of this invention wherein n is less than 6 have limited storage stability in aqueous solution. Such aqueous solutions generally should be employed within about 4 hours of preparation in order to impart durable flame resistance. The instability of such aqueous solutions is evident from a study of the P-31 NMR spectrum. Upon aging. the aqueous solution becomes acid, the P-31 NMR spectrum becomes more complex and there may be noted a decrease in the amount of material having peaks in the 15-20 ppm. range. Correspondingly, the flame resistance imparted to combustible cellulosic materials with such aged aqueous solutions is less fast to laundering.
The efflciency, on a weight basis, of the compounds of this invention varies with the value of n. Combustible cellulosic materials are most efficiently rendered flame resistant by the (monoto tri-lmethylol compounds, less efficiently by the (tetrato hexa-)methy1ol compounds. Preferred are the (diand tri-)methylol compounds. Only slight loss of hand accompanies treatment of fabrics with the (monoto tri-)methylol compounds while a greater loss of hand accompanies the use of the (tetrato hexa-)methylol compounds.
The flame resistance imparted to combustible cellulosic materials by the compounds of this invention is made durable to laundering by curing the compounds after they have been applied to the substrates from an aqueous solution. After application the material is dried by heating at a temperature up to C, preferably at 100-115C. Curing is effected by heating the dried material at -190C., preferably at -170C., in the presence of an acidic curing catalyst for 2-10 minutes, preferably 2-4 minutes. The cat- 1 alyst usually is dissolved in the aqueous solution of methylolphosphoric triamide before the latter is applied to the material being treated. The catalyst usually is added to such aqueous solution, such as a padbath, in an amount which is 0.5-5 weight percent, preferably 1-2.5 percent, based on the weight of the solution. Optionally, the drying and curing steps can be carried out at the curing temperature.
1n the cured condition, fabrics treated with methylolphosphoric triamides of this invention lose very little flame resistance after the first laundering; fabrics which have been treated with the diand higher methylol phosphoric triamides retain their flame resistance even after being subjected to multiple launderings. During the curing step, the compounds of this invention are converted to insoluble polymeric materials, thus rendering them durable to laundering. This explanation of durability is not intended as limiting since it is recognized that an entirely different mechanism or a combination of mechanisms may be involved in the flxing operation. For example, it is recognized that durability, in part, may be the result of chemical bonding between the compounds of this invention and the substrate cellulosic material. 1
Preferred curing catalysts are acids which are relatively nonvolatile at curing temperatures and latent acid compounds. Examples of these include oxalic, glycolic, lactic, malic, tartaric, succinic and citric acids, ammonium chloride, ammonium sulfates, ammonium phosphates, such as diammonium acid phosphate, acid salts of organic amines, such as 2-methyl-2- aminopropanol-l hydrochloride and tris(2-hydroxyethyl)amine hydrochloride, and salts of weakly basic metals and strong acids, such as zinc nitrate, zinc chloride, zinc fluoborate, magnesium chloride and magnesium nitrate.
The compounds of this invention impart flame resistance to'combustible cellulosic materials by their application to or incorporation into the material in amounts of 10-60 weight percent, based on the dry weight of the material being treated. Generally, the amount added is 14-50 percent, preferably 14-25 percent. The compounds can be applied or incorporated in any suitable fashion. Conveniently, they are applied as 5-65 weight percent aqueous solutions by a padding operation; preferably, the aqueous solution contains 15-50 percent of a methylolphosphoric triamide of this invention.
The aqueous solution of methylolphosphoric triamide can contain wetting agents, for example, non-ionic wetting agents, to facilitate wetting of the cellulosic material being treated. Included among such wetting agents are polyethylene oxides obtained by reacting a phenol or a monohydric or polyhydric aliphatic alcohol with ethylene oxide. Such wetting agents generally are added so as to comprise 0.01-0.15 weight percent of the aqueous triamide solution.
If the aqueous padbath method of application is employed, the padbath, for example, the preparative reactive mixture described above, at a pH of 6.5-7.5, is padded onto the substrate to the extent of 50-120 percent, based on the dry weight of substrate, preferably to the extent of 60-90 percent. Padding can be effected by soaking the fabric in the padbath and squeezing out the excess solution, thus providing control of the net amount of solution applied to or picked up by the fabric, The fractions of the solutions retained by and squeezed out of the fabric are of essentially the same composition. Preferably, the curing catalyst is incorporated into the padbath. Drying and curing are carried out as previously described. Conveniently, continuously circulating hot air can be employed as a heat source, especially for the drying operation.
Instead of padding the solution onto the fabric which is to be treated, other convenient means of application can be employed. For example, the solutions of the compounds of this invention can be sprayed, in controlled amounts, onto moving fabrics.
The compounds of this invention can be employed in combination with well-known aminoplast resin condensates which, in some instances, improve the effectiveness of the compounds of this invention in rendering cellulosic materials flame resistant. It also has been discovered that the aminoplast resins, in some instances, improve the durability of the compounds of this invention when both have been coapplied to the substrate. Aminoplast resins are well known in the art and have been discussed hereinabove. Many such resins are known to impart flame resistance to cellulosic materials. They often are applied as water soluble precondensate compounds. When such precondensates are employed herein, they are dissolved in the freshly prepared solution of the methylolphosphoric triamide, which solution then is preferably used promptly to treat the fabric, for example, within about 4 hours.
When a methylolphosphoric triamide of this invention is employed in combination with a water soluble aminoplast resin precondensate, less than the previously recited amounts of the triamide are necessary to impart the desired flame resistant characteristics to the cellulosic material being treated. When used in such a combination, the methylolphosphoric triamide is incorporated into or applied to the material in amounts 7-15 weight percent, preferably 8-l2 percent, based on the dry weight of material being treated. The amount of aminoplast precondensate added in combination with the trimethylolphosphoric triamide is known from the art. When the aminoplast resin precondensate is a hydroxymethylmelamine, a convenient amount is 7-13 weight percent, based on the dry weight of material being treated, preferably 7-10 percent.
Water soluble aminoplast resin precondensate compounds useful with the compounds of this invention include those containing at least two moles of condensed formaldehyde, as N-hydroxymethyl or N-alkoxymethyl groups wherein the alkoxy group contains 1-4 carbon atoms. Precondensate compounds include polymethylol derivatives, as well as their partial or complete ethers, of amides such as urea, thiourea, guanidine and dicyandiamide, for example, dimethylolurea, tetramethylol urea, di(methoxymethyl)urea, dimethylolquanidine, trimethylol quanidine and dimethyloldicyandiamide. Precondensate compounds of substituted ureas can also be used, such as formaldehyde condensates, and their ethers, of ethylene urea. methyleneurea. acetylenediurea, biuret, oxydimethyleneurea (uron) and iminodimethyleneurea (triazone). Particular examples of these include dimethylolethyleneurea, dimethylolmethyleneurea, tetramethylolacetylenediurea, trimethylolbiuret, di(methoxymethyl)uron and di(methoxymethyl) triazone.
Still other precondensate compounds include the reaction products of formaldehyde and triazines such as melamine, diaminotriazine, formoguanamine and 2-chloro-4,6-diaminotriazine. Preferred examples of such precondensates include diand trimethylolmelamine, optionally partially methylated, hexa(methoxymethyl)melamine, tetramethyloldiaminotriazine and tetramethylol-2-chloro-4,6-diaminotriazine. Diazines and azoles are also useful aminoplast resin precondensate compounds. Typical of these are precondensates based on 2,4-diamino-l,3-diazine, guanazole and diaminopyrrole.
As previously indicated, fabricswhich are treated with the compounds of this invention substantially retain their original physical characteristics, such as soft ness and hand. Even when the compounds of this invention are employed in combination witha aminoplast resin precondensates, because of the small quantity of each compound required, the properties of the fabric are altered only slightly, especially with the preferred aminoplast resin precondensates and the preferred methylolphosphoric triamides.
The compounds of this invention and their combinations with aminoplast resin precondensate compounds are particularly effective on combustible cellulosic materials of a fibrous nature. In the textile field, this includes cotton, the preferred fiber, linen, viscose rayon, cuprammonium rayon, jute, hemp and ramie. Such cellulosic material can be treated in the form of raw fiber, carded stock, rovings, thread, yarn and felts as well as inthe form of knitted and woven fabrics. However, the cellulosic material need not be fibrous to be rendered fire resistant with the compounds of this invention; any cellulosic material can be treated if it can be penetrated or swollen by water, thus permitting penetration by the aqueous medium containing the methylolphosphoric triamide. Fibrous cellulosic material can be rendered flame resistant with the compounds of this invention even though it is blended with other fibers, for example, natural animal fibers such as wool and synthetic fibers such as linear polyamide, linear polyester and polyacrylic fibers.
Cellulosic materials which have been rendered flame resistant with the compounds of this invention are especially useful in tents, stage scenery, upholstery fabrics, slipcovers, draperies, wearing apparel for personnel in close contact with fire or heat, bedding, nightclothes, tarpaulins, insulation, padding, rope, string and twine. Fabrics which have been treated with the compounds of this invention are flame resistant throughout, not just on their surfaces.
In the following examples, parts are parts by weight except where otherwise specified. The terms hand, padding, laundering, limiting oxygen index (LOl), vertical flame test (VFT) and char length refer to the following:
Hand: the softness of a treated fabric relative to untreated fabric as the control. It is graded subjectively here on a scale of l to 5 in which 5 signifies a softness and flexibility virtually indistinguishable from the control and l signifies great stiffness relative to the control Padding: wetting the fabric with the aqueous triamide solution and then running the wet fabric between rollers to squeeze out liquid which is in excess of the desired pickup on the fabric.
Laundering, also expressed as home washing (HW): exposing the fabric to a standard laundering cycle, employing a washing solution of 100 grams of a commercial detergent (Tide) per 15 gallons of water, and tumble drying the washed fabric.
Limiting Oxygen lndex: determined with a -inch by 2-inch piece of fabric spread lengthwise in a vertical plane and supported along its vertical edges. The spread fabric is positioned inside a transparent circular (cylindrical) column open only at the top. The top of the column is one or more inches above the spread fabric. The interior of the column is provided with an upward flow, from its base, of a gaseous mixture of pure oxygen and pure nitrogen. The volume flow rate of each gas making up the mixture is instrumented and manually adjustable. To test fabric in this apparatus, the spread fabric is ignited from the top while gas mixture flows up the column. The flow rates of the nitrogen and oxygen are adjusted until the flame on the ignited fabric just goes out. The ratio of the volume flow of oxygen to the sum of the volume flows of oxygen and nitrogen is then calculated. This value, called the Limiting Oxygen Index or LOl, is the average of two determinations. As a standard of reference, untreated 8-oz. cotton twill used in the following examples to test the effectiveness of the compounds of this invention has an LOI value of 0. 1 80fl).002 and is completely burned up in the vertical flame test. Air contains about 21 mole percent oxygen; therefore, fabrics with LOl values below about 0.210 can be expected to burn freely in a candlelike manner (from the top to the bottom) in air. For commercial applications, an LOI value of at least about 0.260-0.270 is considered acceptable.
Vertical Flame Test and Char Length: carried out in a 12-inch by 12-inch cabinet 30 inches high and having a glass front. Gas circulation is provided by a 4-inch high opening beneath the glass front and a 6-inch diameter baffled hole at the top of the cabinet. It is provided with holder brackets on which a specimen holder is hung. The specimen holder provides a 2-inch wide by 14-inch high vertical open space and vertical side clips to hold edges of fabric which span this open space. Samples are ignited by a 6-inch high Bunsen burner having a 0.375-inch inside diameter tube and a luminous flame 1.5 inches long. To conduct the test, a 2.75- inch by -inch fabric sample is held in the specimen holder by its vertical edges and the specimen holder is hung centrally by the holder brackets. The igniting flame is applied so that 0.75 inch of the lower end of the fabric is in the flame. This exposure is continued for 3.0 seconds and the flame is removed. After the flame has extinguished itself, the sample is removed from the holder. A hook with an attached weight is inserted into the sample on one side of the charred area 0.25 inch from the outside edge and 0.25 inch from the lower edge. For 2.0 to 6.0-oz. per square yard fabric, the attached weight is 0.25 pound; for over 6.0 and up to and including 15-oz. per square yard fabric, a 0.50 pound weight is used. The corner of the cloth at the opposite edge of the char from the load is gently raised until the sample and weight are clear of supporting surface. The length of the tear which occurs is measured (in inches) and reported as char length. Where char length is reported below, it is understood to have been determined by this procedure and to be an average value of 2 or 4 determinations.
EXAMPLE 1 Trimethylolphosphoric Triamide Preparation 9.5 Parts (0.1 mole) of phosphoric triamide, prepared according to Klement and Koch, Berichte 87, 338 (1954) and 25 parts of 37 percent aqueous formaldehyde (0.3 mole) were mixed at 20C. and the pH of the resulting solution was adjusted to 10.3 with 20 percent aqueous sodium hydroxide. The solution was allowed to stand for 2.5 hours, after which time the pH of the solution had dropped to 9.9 and the P-3 1 NMR spectrum showed a band between 15 and 20 ppm. with an unsymmetrical peak centered at 18.3 ppm.; the spectrum was free of a signal at 22.5 ppm. The pH of the solution was then adjusted to 7.6 with 10 percent hydrochloric acid. Water was rapidly stripped from the solution at 20 mm. of Hg pressure and 50C. (using a Rotovac still). 20.2 Parts of residue (theoretical: 18.5 parts) were obtained as an extremely viscous mass which, on standing, became a soft transparent solid. This solid was chemically analyzed. Calcd for C H O N P: C, 19.5; H, 6.5; N, 22,7; P, 16.8; Atomic N/P ratio, 3.0. Found: C, 19.8; H, 6.6; N, 21.1; P, 15.9; Atomic N/P ratio, 2.9.
EXAMPLE 2 Hexamethylolphosphoric Triamide Preparation 0.1 Mole of phosphoric triamide and 0.72 mole of formaldehyde (37 percent aqueous solution) were reacted at a pH of 10.2 as described in Example 1. There was no drop in pH of the solution after standing. The product in solution showed a single P-3l NMR peak versus percent phosphoric acid at 16.9 ppm. Adjustment of the pH to 7.6 with 10 percent hydrochloric acid followed by stripping of water at 50C. and 20 mm. of Hg pressure provided 32.0 parts (theoretical: 27.5 parts) of a colorless viscous liquid residue which was analyzed by chemical analysis. Calcd for C H O N P: C, 26.2; H, 6.6; N, 15.3; P, 11,3. Found: C, 33.5; H, 7.6; N, 13.0; P, 9.6. Since the 37 percent aqueous formaldehyde solution employed in this experiment had been stabilized with 10-15 percent methanol, it is believed that etherification of the methylol groups may have occurred during stripping. The P-31 NMR spectrum of the product redissolved in water showed peaks at 16.9 ppm. (for the hexaformaldehyde adduct) and at 1 1.3 ppm. (believed to correspond to methoxymethyl derivatives of phosphoric triamide). The analytical results confirm the presence of almost three methoxy groups in the product (replacing almost three hydroxy groups of the hexamethylolphosphoric triamide). Calcd. for C H O N P: C, 34.0; H, 7.6; N, 13.2; P, 9.8.
EXAMPLE 3 Methylolphosphoric Triamide/Trimethylolmelamine Treatment of Cotton Fabric Seven padbaths were prepared so as to contain equal amounts of phosphoric triamide (PTA), 0.5 weight percent ammonium chloride (curing agent) and trimethylolmelamine (TMM) in an amount 1.67 times the PTA. To six of the baths were added 1, 2, 3, 4, 5 and 6 molar equivalents. respectively, of formaldehyde, as a 37 percent aqueous solution. The formaldehyde and PTA were allowed to react at a pH of 10 at 20C. for 2 hours, after which the pH was adjusted to 7.5.
Eight-ounce cotton twill fabrics were impregnated in the padbaths and squeezed to a net pickup on the fabrics approximating 6.6% PTA and 11.0% TMM. The fabrics were heated at 100C. until dry to the touch and then cured at 170C. for 4 minutes. They were chemically analyzed as cured, tested for L01, laundered once (one home wash) and rate for hand, laundered 19 more times (total, 20 home washes) and then chemically analyzed and tested for L01. The results are summarized in the following table.
Mole Ratio CH QI PTA Analysis After Cure P 2.03 1.84 1.81 1.84 1.90 1.84 2.01 Z N 6.46 5.96 6.40 6.39 6.29 6.34 6.52 7r PTA (on 7.3 6.6 6.6 6.6 6.8 6.6 7.2
wt. 0 fiber) 7v Methylol 8.7 11.8 12.9 15.4 17 20.9
Compound %TMM 12.2 11.0 11.0 11.0 11.3 11.0 12.0
L01 As Cured 0.444 0.377 0.356 0.331 0.324 0.316 0.302 Aegt erhl Home 0.308 0.352 0.372 0.342 0.318 0.326 0.305
as After 20 0.223 0.341 0.375 0.348 0.333 0.334 0.312
Home Washes After 20 Home Washes P 0.99 1.28 1.60 1.98 1.64 1.82 1.82 N 1.51 4.69 5.81 6.11 5.99 6.45 6.25 of lnitial 49 70 88 107 86 99 91 P Retained t 1 Hand after 1 Home Wash 5 4-5 4 4 4-3 3 2 These results show the superiority of methylolphosphoric triamide/trimethylolmelamine compositions over phosphoric triamide/trimethylolmelamine compositions for imparting flame resistance. Further, they show that the flame resistance imparted by the diand higher formaldehyde adducts improves with launderings. They also demonstrate the minimal loss of hand in cellulosic fabrics treated with the compositions conded onto 8-oz. cotton twill fabric samples to net solution pickups of about 87 percent. The padded fabrics were dried at 115C. and then cured for 4 minutes at 165C. The cured fabrics were laundered 20 times. Elemental chemical analyses of the fabric samples as cured (before laundering) and after 20 launderings were made. LOl tests for flame resistance were made cured, after one laundering and after 20 launderings.
taining (monoto tri-)methylolphosphoric triamides. 50 The following table summarizes the results.
% Trimethylol PTA (on weight of fiber) Found P Re- Trimethylol (from P,N LOl tained Atomic Ratio N/P PTA in Bath Calcd analyses) Initial 1 HW 20 HW (20 HW) Initial 20 HW These results show the efficiency of trimethylolphosphoric triamide in imparting flame resistance to cotton Wt. Additive on Fabric fabric and the durability of that effect even after re- Trimethy'ol PTA TMM peated laundering. 20 0.204
EXAMPLE 5 8.7 7 0.293 Dimethylolphosphoric Triamide/Trimethylolmela- 0 0-243 19.5 0 0.290 mine Treatment of Cotton Blend Fabrics 241 0 197 Dimethylolphosphoric triamide was prepared in solution from phosphoric triamide (PTA) according to the EXAMPLE 7 procedure of Example 1 except that 16.7 parts, instead of 25 parts, of aqueous formaldehyde were employed. Trlmethylolphosphorlc TrldlKile/Ammoplast Resm Six padbaths were prepared from the solution, each Treatment of Cotton FaPnc neutralized to pH 7.2 and containing trimethylolmela- SlX aqueous padbaths (designated A through were mine (TMM) and .05 w i h percent f ammonium prepared so as to contain, per 100 parts of solution, 12 chloride (curing agent). The padbaths were padded Parts of lrlmethylolphosphonc trlamlde; 1 P of onto commercial lightweight, 2.8-oz. and 53-02. 50/50 y i i hydrochlqnde (curing polyester/cotton a d 35- 50/50 rayon/cotton b1 d agent) and a water soluble ammoplast resin precondenfabrics, the fabrics were dried, and curing was carried Sate Shown in the following table are the preconden' out in a manner similar to the procedures previously sates a the a ou which e added l g with described. The following table summarizes the results the triamide and curing agent) to the padbaths to P of the evaluations of the treated fabrics. i e equivalen nitrogen c n nts.
Wt. 7r Dimethylol PTA Wt.% L01 Fabric (on weight of fiber) TMM Initial l HW 20 HW Hand 2.8 oz. polyester/cotton I 1.3 7.0 0.236 0.237 0.234 4 2.8 oz. polyester/cotton 18.3 7.0 0.244 0.247 0.245 3-4 5.3 oz. polyester/cotton 13.1 7.7 0.251 0.249 0.244 3 5.3 oz. polyester/cotton 21.6 7.7 0.257 0.259 0.259 2 3.6 oz. rayon/cotton 9.6 8.0 0.276 0.276 0.284 4 3.6 oz. rayon/cotton 16.6 8.0 0.277 0.294 0.300 3-4 EXAMPLE 6 A B C D E F Trimethylolphosphoric Triamide Treatment of Cot- Trimethylolphosphoric 12 12 12 12 12 12 Fabrics c ll r i i l f ent l 1 l l l l Thisexample shows the beneficial effect that can be Trimgthy oimeiamine 8 realized through use of the combination of trimethylol- Fi g g i l0 phosphoric triamide and trimethylolmelamine (TMM) 1,3455 hydroxymethylyz 17 in imparting flame resistance to fabrics. The trimeangdglolldtiiae t D 5 31 thylolphosphoric triam de was prepared from phosgfi fi phoric triamide according to the procedure described 3-pi g -5. 17 in Example 1. Padbaths were prepared in a manner mazme- W 87 79 77 70 56 70 similar to that described in Example 5. The impregam nated fabrics (8-ounce cotton twill fabric) were dried at 115C., cured at 165-l75C. and given one home wash. The following table summarizes the results of the evalumlons of the treated fabncsr The padbaths were padded (at 87 percent add-on) unto mercerized bleached cotton twill 8-oz fabrics (also des- Wt, '7 Additi m Fubri. ignated A through F to correspond to padbaths A k L through F). The padded fabrics were dried at 100C. Trimelhylol PTA TMM L01 for 10 minutes, then cured at 165C. for 4 minutes. The
0 8 0189 following table summarizes the results of the evalua- 0 16 0.195 tions of the treated fabrics.
A B C D E F 2 lnitial 0.251 0.295 0.263 0.244 0.261 0.233 After 1 home wash 0.245 0.296 0.270 0.250 0.254 0.239 After 20 home washes 0.229 0.302 0.276 0.248 0.206 0.233
VFT (in inches) lnlthl 4.8 0.75 1.4 4.1 2. 4.0 After 20 home washes BEL 1.3 0.6 4.5 BEL 3.3
Wt. P on Fabric lnitial 1.41 1.35 1.36 1.35 1.28 1.31
% of lnitial P Retained Afier 20 home washes 87 49 88 The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
1. Methylolphosphoric triamide having the formula Milt :r
1 wherein at least one of the six R groups is CH OH and wherein 1-5 of the six R groups are CH OH and the remainder are H, said triamide being characterized by the presence in its P-3l nuclear magnetic resonance spectrum of a band in the range 15-20 ppm. downfield from O percent aqueous phosphoric acid as external standard, which process comprises reacting phosphoric triamide and at least one molar equivalent of formaldehyde in an aqueous medium at a pH of 7-1 1 until the reaction mixture shows said band in its nuclear magnetic resonance spectrum.
5. The process of claim 4 wherein 2-3 molar equivalents of formaldehyde are reacted with the phosphoric triamide.
6. The process of claim 4 wherein the reaction is carried out at a pH of 9.5l0.5.

Claims (6)

1. METHYLOPHOSPHORIC TRIAMIDE HAVING THE FORMULA
2. The triamide of claim 1 wherein the number of CH2OH groups is 2-3 and the P-31 spectrum is free of a band at 22.5 ppm.
3. The triamide of claim 2 wherein the number of CH2OH groups is three.
4. Process for preparing a methylolphosphoric triamide having the formula
5. The process of claim 4 wherein 2-3 molar equivalents of formaldehyde are reacted with the phosphoric triamide.
6. The process of claim 4 wherein the reaction is carried out at a pH of 9.5-10.5.
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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1222885A (en) * 1966-09-28 1971-02-17 Stevens & Co Inc J P Flame-retardant treatments for cellulose
US3711542A (en) * 1969-12-18 1973-01-16 Moleculon Res Corp N-methylol phosphazene compounds

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1222885A (en) * 1966-09-28 1971-02-17 Stevens & Co Inc J P Flame-retardant treatments for cellulose
US3711542A (en) * 1969-12-18 1973-01-16 Moleculon Res Corp N-methylol phosphazene compounds

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Hellmann, Newer Method of Preparative Organic Chemistry, Vol. II, p. 278 79 (Edited by Foerst) (Academic Press, N.Y.) (1963). *

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