A PROCESS OF DYEING AND FLAME RETARDING AN ARAMID FIBRE OR FABRIC

Abstract: A process of simultaneously dyeing and flame retarding an aramid fibre, comprises the steps of: (1) contacting dyeable poly(m-phenylene isophthalamide) fibres or fabric with a solution consisting essentially of a flame-retarding amount of a cyclic phosphonate ester flame retardant represented by the formulae: where a is 0 or 1; b is 0, 1 or 2, c is 1, 2 or 3 and a+b+c is 3; R and R¹ are the same or different and are alkyl (C₁-C₈), phenyl halophenyl, hydroxyphenyl, tolyl, xylyl, benzyl, phenethyl, hydroxyethyl, phenoxyethyl, or dibromophenoxymethyl; R² is alkyl (C₁­ -C₄); and R³ is lower alkyl (C₁-C₄) or hydroxyalkyl (C₁­ -C₄); or where d is 0, 1 or 2; e is 1, 2 or 3; R² is alkyl (C₁-C₄­ ); R³ is lower alkyl (C₁-C₄) or hydroxyalkyl (C₁-C₄); R⁴ is alkyl (C₁-C₄) phenyl, halophenyl, hydroxyphenyl, hydroxyethyl, phenoxyethyl, dibromophenoxyethyl, tolyl, xylyl, benzyl, or phenethyl; and R⁵ is monovalent alkyl (C₁-C₆), chlorophenyl, bromophenyl, dibromophenyl, tribromophenyl, hydroxyphenyl, naphthyl, tolyl, xylyl, benzyl, or phenethyl; divalent alkylene (C₁-C₆), vinylene, o-phenylene, m-phenylene, p-phenylene, tetrachlorophenylene (o, m, or p), or tetra­ bromophenylene (o, m, or p); or trivalent phenenyl and a disperse dyestuff, an acid dyestuff or both; and (2) heating the aramid fibre treated in step (1) to fix said dye to said fibre.

Description: This invention relates to processes of dyeing and flame retarding aramid fibres and fabrics with cyclic phosphate ester flame retardants. These flame retardants serve to swell the aramid fibres and allow for introduction of dyestuff into the fibres. The aramid fibre Nomex (a registered trademark of duPont) has several interesting and indeed unique properties that make it highly desirable for specific applications. As an example, the fibre is inherently flame retardant, and thus lends itself to applications in which such flame retardant properties are desirable. Aramid fibres are extremely hard to dye, due, in part, to the crystallinity of the fibre. Solution-dyed aramid fibres are available but only in limited colors as selected by the fibre manufacturer. Frequently dye carriers such as acetophenone have been used to effectively dye such fibres. However, these carriers may themselves be flammable or detract from the otherwise good inherently flame retardant properties of the fibre. In addition, acetophenone dyed products have rather characteristic odor that is not well accepted. Dyes introduced into the fibre and/or topical finishes and chemicals applied to the fibre affect the flame retardant characteristics of the final product. Observations with respect to the flame retardant properties, or lack thereof, for aramid fibres are similar to those noted in the dyeing and finishing of glass fabrics. While glass fibres will not themselves support combustion, the pigments, dyes or other finishes applied to glass fabrics will burn. Glass fabric forms a convenient matrix to support the pigments, dyes or finish, and this matrix provides a relatively large surface area and allows flames to propagate. A similar situation occurs with Nomex fabrics and thus, as with glass fabrics, it is sometimes necessary to add an auxiliary flame retardant chemical to the finish to improve the overall flame retardant characteristics of the final aramid product. The present invention seeks to both dye and flame retard aramid fibres, specifically poly(m-phenyleneisophthalamide) or Nomex, in a single step and to provide a product that has flame retardant qualities that are at least as good as, if not better than, the corresponding undyed, greige aramid fabric. According to one aspect of the present invention there is provided a process of simultaneously dyeing and flame retarding an aramid fibre, characterised by comprising the steps of: (1) contacting dyeable poly(m-phenyleisophthalamide) fibres or fabric with a solution consisting essentially of a fibre swelling flame-retarding amount of a cyclic phosphonate ester flame retardant which forms the sole fibre-swelling and flame-retarding agent and which is represented by the formulae: where a is 0 or 1; b is 0, 1 or 2, c is 1, 2 or 3 and a+b+c is 3; R and R¹ are the same or different and are alkyl (C₁-C₈), phenyl, halophenyl, hydroxyphenyl, tolyl, xylyl, benzyl, phenethyl, hydroxyethyl, phenoxyethyl, or dibromophenoxymethyl; R² is alkyl (C₁-C₄); and R³ is lower alkyl (C₁-C₄) or hydroxyalkyl (C₁-C₄); or where d is 0, 1 or 2; e is 1, 2 or 3; R² is alkyl (C₁-C₄); R³ is lower alkyl (C₁-C₄) or hydroxyalkyl (C₁-C₄); R⁴ is alkyl (C₁-C₄) phenyl, halophenyl, hydroxyphenyl, hydroxyethyl, phenoxyethyl, dibromophenoxyethyl, tolyl, xylyl, benzyl, or phenethyl; and R⁵ is monovalent alkyl (C₁-C₆), chlorophenyl, bromophenyl, dibromophenyl, tribromophenyl, hydroxyphenyl, naphthyl, tolyl, xylyl, benzyl, or phenethyl; divalent alkylene (C₁-C₆), vinylene, o-phenylene, m-phenylene, p-phenylene, tetrachlorophenylene (o, m, or p), or tetrabromophenylene (o, m, or p); or trivalent phenenyl and a disperse dyestuff, an acid dyestuff or both; and (2) heating the aramid fibre treated in step (1) to fix said dye to said fibre. The solution may be applied by padding onto an aramid fabric. Alternatively, the flame retardant and dyestuff may be applied as a print paste. Preferably the fibre or fabric is heated in step (2) at a temperature in the range of about 177°C (350° F) to about 204°C (400°F). According to another aspect of the present invention, there is provided a process of dyeing and imparting a flame retardant treatment to a dyeable aramid fibre, characterised by comprising the successive steps of: (1) contacting a dyeable poly(m-phenyleneisophthalamide) fibre with a solution consisting essentially of a fibre swelling flame-retarding amount of a cyclic phosphonate ester flame retardant which forms the sole fibre-swelling and fibre-retarding agent and which is represented by the formulae: where a is 0 or 1; b is 0, 1 or 2, c is 1, 2 or 3 and a+b+c is 3; R and R' are the same or different and are alkyl (C₁-C₈), phenyl, halophenyl, hydroxyphenyl, tolyl, xylyl, benzyl, phenethyl, hydroxyethyl, phenoxyethyl, or dibromophenoxymethyl; R² is alkyl (C₁-C₄); and R³ is lower alkyl (C₁-C₄) or hydroxyalkyl (C₁-C₄); or where d is 0, 1 or 2; e is 1, 2 or 3; R² is alkyl (C₁-C₄); R³ is lower alkyl (C₁-C₄) or hydroxyalkyl (C₁-C₄); R⁴ is alkyl (C₁-C₄) phenyl, halophenyl, hydroxyphenyl, hydroxyethyl, phenoxyethyl, dibromophenoxyethyl, tolyl, xylyl, benzyl, or phenethyl; and R⁵ is monovalent alkyl (C₁-C₆), chlorophenyl, bromophenyl, dibromophenyl, tribromophenyl, hydroxyphenyl, naphthyl, tolyl, xylyl, benzyl, or phenethyl; divalent alkylene (C₁-C₆), vinylene, o-phenylene, m-phenylene, p-phenylene, tetrachlorophenylene (o, m, or p), or tetrabromophenylene (o, m, or p); or trivalent phenenyl and a disperse dyestuff, an acid dyestuff or both, the solution being maintained at a temperature of from about 149°C (300°F) to a temperature not greater than the boiling point of the solution; (2) allowing the fibre to remain in contact with the solution until the dye is fixed to the fibre; and (3) removing and drying the dyed and flame-retardant-treated fibre. The solution may be maintained at a temperature in the range of about 177°C (350°F) to about 204°C (400°F). EP-A-0,246,083 to Burlington Industries was published after the filing date of the present application and it describes a process for dyeing or dyeing and optionally flame retarding poly(m-phenyleneisophthalamide) fibres. The dyeing medium is an organic swelling agent selected from the group consisting of N-methylpyrrolidone, dimethylsulfoxide and dimethylacetamide, none of which has flame retardant properties. The bath preferably contains a diluent to control fibre damage. If flame resistance is desired, a flame retardant is added to the dye bath as an additional ingredient. When dyeing or dyeing/flame retarding is complete, the organic swelling agent is completely washed from the fibre, while in the process of the present invention a portion of the solvent remains within the fibre to impart flame resistance. EP-A-0,246,084 to Burlington Industries was also published after the filing date of the present invention and it describes a process for printing or printing and optionally flame retarding poly(m-phenyleneisophthalamide) fabrics. The printing paste contains, in addition to dye, a highly polar solvent which is a swelling agent for the aramid fibres, and which is selected from the group consisting of N-methylpyrrolidone, dimethylsulfoxide and dimethylacetamide. Additional ingredients include a print paste thickening agent, water and optionally a flame retardant. Thus this printing medium differs from the dyeing medium of the present invention. The printing process is performed at a relatively low temperature and fixation is conducted at an elevated temperature. This procedure further distinguishes the process of EP-A-0,246,084 from the present invention. Candidate fibres for the dyeing and flame retardant process of this invention are known generally as aromatic polyamides or "aramids". This class includes a wide variety of polymers as disclosed in US-A-4,324,706. Experience indicates that for some reason not fully understood, not all types of aramid fibres can be reproducibly treated by this process; those fibres that are not suited do not allow the disperse or acid dye to enter the fibre and are only surface stained. Thus, a fibre amenable to the process of this invention is selected from the class of aramids suitable for dyeing and flame retarding. Such fibres are referred to here as treatable, i.e., dyeable and flame-retardant treatable aramids and are known chemically as poly(m-phenyleneisophthalamide), i.e., the meta isomer which is the poly condensation product of m -phenylenediamine and isophthalic acid. Below is a listing of fibres now commercially available identified by fibre name (usually a trademark) and producer: Selection of a suitable aramid amenable to the continuous dyeing and flame retarding process of the present invention can be conveniently made by subjecting a fibre sample to an abbreviated test to determine fibre acceptability. Experience indicates that fibres of the para isomer, poly(p-phenyleneterephthalamide), represented commercially by duPont's Kevlar and Enka-Glanzstoff's Arenka, as well as Rhone-Poulenc's Kermel and polybenzimidazole (PBI), are merely stained or changed in color but are not dyed by the process of the present invention. Accordingly, as used in the text of this application and in the claims that follow, the expressions "aramid" and "aromatic polyamide fibre", when pertaining to the process of the present invention, will signify the meta isomer. Blends of poly(m-phenyleneisophthalamide) fibres with other fibres, including fibres of the para isomer, may be subjected to the dyeing process in which case only the meta isomer fibres will be dyed. The flame retardant materials used in the process of the present invention do not degrade and successfully withstand heat treatment at temperatures over 149°C (300°F), and area typically liquid at such temperatures. Among the types of materials that may be employed, preferred are the cyclic phosphonate esters described, for instance, in one or more of US-A-3,894,386, US-A-3,149,476, US-A-3,991,019 and US-A-3,511,857. The flame retardant materials used in accordance with the present invention are thermally stable cyclic phosphonate esters prepared by reacting alkyl-halogen-free esters with a bicyclic phosphite. As a class these cyclic phosphonate esters are represented by one of the formulae: where a is 0 or 1; b is 0, 1 or 2, c is 1, 2 or 3 and a+b+c is 3; R and R' are the same or different and are alkyl (C₁-C₈), phenyl, halophenyl, hydroxyphenyl, tolyl, xylyl, benzyl, phenethyl, hydroxyethyl, phenoxyethyl, or dibromophenoxymethyl; R² is alkyl (C₁-C₄); and R³ is lower alkyl (C₁-C₄) or hydroxyalkyl (C₁-C₄) or where d is 0, 1 or 2; e is 1, 2 or 3; R² is alkyl (C₁-C₄); R³ is lower alkyl (C₁-C₄) or hydroxyalkyl (C₁-C₄) or hydroxyalkyl (C₁-C₄); R⁴ is alkyl (C₁-C₄) phenyl, halophenyl, hydroxyphenyl, hydroxyethyl, phenoxyethyl, dibromophenoxyethyl, tolyl, xylyl, benzyl, or phenethyl; and R⁵ is monovalent alkyl (C₁-C₆), chlorophenyl, bromophenyl, dibromophenyl, tribromophenyl, hydroxyphenyl, naphthyl, tolyl, xylyl, benzyl, or phenethyl; divalent alkylene (C₁-C₆), vinylene, o-phenylene, m-phenylene, p-phenylene, tetrachlorophenylene (o, m, or p), or tetrabromophenylene (o, m, or p); or trivalent phenenyl. The preferred compounds are represented by the formula: in which x is 0 or 1, usually a 50:50 mixture of the mono and di-esters. The preparation of these cyclic phosphonate esters and their use as flame retardants are described in US-A-3,789,091 and US-A-3,849,368, The 50:50 mixture of these esters is available as Antiblaze 19 (sometimes AB 19 herein) from Albright & Wilson, Inc., of Richmond, Virginia. Also available is Antiblaze 19T, a low viscosity grade flame retardant containing 93% active ingredient and formulated especially for textile treating requirements. As described by the supplier, Antiblaze 19 has a flash point of 240°C (464°F) and 19T a flash point of 237°C (459°F) by the Cleveland open cup method; both are suited for application at high temperatures. An essential part of the present invention is heating the fibres in the presence of both the dyestuff (disperse or acidic) plus the flame retardant liquid. Treatment temperatures in the range of 149 - 316°C (300 - 600°F) are contemplated. However, higher and lower temperatures may be employed depending upon the specific heat characteristics of the aromatic polyamide fibre being treated, heat tolerance of the dyestuff itself, and the nature of the flame retardant liquid. Heating is generally in the range of about 177°C (350°F) to about 199°C (390°F) and for a period of time sufficient to impart the desired flame retardant characteristics to the fibre as well as to introduce a sufficient quantity of dyestuff into the fibre. Exposure times range from periods as short as 10 seconds up to 2 minutes or longer, depending upon the processing conditions and the equipment employed. Dyestuff-containing compositions and flame-retardant treatments are detailed below. The pad/thermosol process . A solution of "neat" (undiluted) flame retardant containing the desired quantity of disperse or acid dye is padded onto the fibres at ambient temperatures, then heat treated in order to "fix" the dyestuff to the fibre and provide the required flame-retardant treatment. Following this, the fibres are washed with an aqueous detergent (scoured) then given a rinse in a halogenated hydrocarbon, for instance perchloroethylene. Print pastes . A paste of disperse dyestuff is made with the liquid flame-retardant material, and this water-free paste is then applied to the aramid fabrics to be treated either in a uniform manner, such as with a doctor knife, nip roll or the like, or in a predetermined pattern on a printing machine. Heat is applied in order to fix the dyestuff to the fibre and accomplish the required flame retardant treatment, and this is followed by an aqueous detergent scour and a rinse in a halogenated hydrocarbon. Immersion in hot fluid . Successful dyeing and flame retardant treatment may be accomplished by immersing the fibres, typically in fabric form, into a bath containing the flame retardant material in which the requisite quantity of disperse or acid dye has been dissolved. When Antiblaze 19 is used as the flame retardant liquid, the dyestuff solution is maintained at a temperature in the range of about 177° to 193°C (350°F to 380°F), and the fibres are exposed to the heated solution for various periods of time ranging from as little as 15 seconds up to about 2 minutes. This immersion is followed by an aqueous detergent scour and then rinsing with a halogenated hydrocarbon. While not wishing to be bound by any theory or mode of operation, it would appear that a suitable flame retardant acts both as a solvent or a vehicle for dyeing the fibre and causing the fibre itself to swell, thus allowing the disperse or acid dye to enter into the fibres. In addition, it appears that the dyeing mechanism is an equilibrium condition between the fibre and the flame-retardant fluid -- the greater the solubility of the dye in the flame-retardant liquid, the less the "solubility" of the dye in the fibre. The dye yield thus depends upon solubility of the dye in the flame retardant fluid. The process of the present invention makes it possible to both dye and improve the flame retardant characteristics of aramid fibres using either acid dyes or disperse dyes with the minimum number of steps, at a rapid rate of treatment and on existing equipment. The dyes can be applied by a pad/thermosol process, immersion in the hot flame-retardant fluid containing the dye, or by incorporating the flame-retardant fluid into a print paste and printing the fabric. Flame Retardancy Tests The processes of the present invention are capable of imparting desirable flame-retardant properties to the material being treated so that the fabric will at least meet the standards established by the requisite review or governmental authority. A host of such tests are given in US-A- 4,120,798. However, those more specific to aramid fibres, and in particular Nomex, are NFPA 701, FTM 5903 and FTM 5905. Significant is the fact that the product produced by the process of this invention does not exhibit afterglow following exposure to open flame. By contrast, most aramid fibres have an afterglow of about 12 seconds following exposure to open flame. This afterglow is a critical factor because it will support combustion if combustible gases are also present. In addition, Nomex fabrics treated in accordance with the present invention perform better in most tests than the undyed (greige) fabrics. Treated fabrics submitted to testing exhibit a minimum shrinkage when exposed to open flame, do not support combustion when removed from the open flame and do not exhibit afterglow. By contrast, unfinished Nomex fabrics continue to burn for several seconds after being removed from flame and there is some afterglow present; unfinished Nomex samples also shrink considerably. Flame retardancy testing procedures and methods are explained in more detail below. From these tests it will be apparent that the simultaneous dyeing and flame-retardant treatment of the present invention improves the burning characteristics of aramid fibres, specifically Nomex fabric. In addition, testing indicates that the finish is durable, many samples retaining desirable properties after the equivalent of 50 home launderings in a washing machine. One specific test of importance is the Limiting Oxygen Index (LOI), determined according to ASTM Method D-2863-77, which is an expression of the percent of oxygen needed to support combustion on a sample (see below). For greige Nomex fabric, the LOI value is 26.6%. The same Nomex fabric but dyed and flame retardant treated in accordance with the process of the current invention has a LOI value of 39% for oxygen. Untreated PBI (another fibre that is inherently flame retardant) exhibits a LOI of 41%. FR Federal Test Method 5903 is intended for use in determining the resistance of cloth to flame and glow propagation and tendency to char. A rectangular cloth test specimen (70mm x 120mm) with long dimension parallel to the warp for fill direction is placed in a holder and suspended vertically in a cabinet with the lower end 1.9cm (3/4 inch) above the top of a Fisher gas burner. A synthetic gas mixture consisting primarily of hydrogen and methane is supplied to the burner. After the specimen is mounted in the cabinet and the door closed, the burner flame is applied vertically at the middle of the lower edge of the specimen for 12 seconds. The specimen continues to flame after the burner is extinguished. The time in seconds the specimen continues to glow after the specimen has ceased to flame is reported as afterglow time; if the specimen glows for more than 30 seconds, it is removed from the test cabinet, taking care not to fan the flame, and suspended in a draft-free area in the same vertical position as in the test cabinet. Char length, the distance (in mm(in.)) from the end of the specimen which was exposed to the flame, to the end of a lengthwise tear through the center of the charred area to the highest peak in the charred area, is also measured and the results averaged. FR Federal Test Method 5905, flame contact test is a measurement of the resistance of textiles and other materials to flame propagation that exposes the specimen to the flame source for a longer period of time than test method 5903. A test specimen the same size as in the above method is exposed to a high temperature butane gas flame 7.6cm (3 inch) in height by vertical suspension in the flame for 12 seconds, the low+est part of the specimen always 3.8cm (1.5 inch) above the center of the burner. At the end of 12 seconds, the specimen is withdrawn from the flame slowly, and any afterflaming timed. The specimen is then re-introduced into the flame and again slowly withdrawn after 12 seconds and any afterflame timed. For each 12-second exposure the results are reported as: ignites, propagates flame; ignites but is self-extinguishing; is ignition resistant; melts; shrinks away from the flame; or drops flaming pieces. Limiting Oxygen Index (LOI) is a method of measuring the minimum oxygen concentration needed to support candle-like combustion of a sample according to ASTM D-2863-77. A test specimen is placed vertically in a glass cylinder, ignited, and a mixture of oxygen and nitrogen is flowed upwardly through the column. An initial oxygen concentration is selected, the specimen ignited from the top and the length of burning and the time are noted. The oxygen concentration is adjusted, the specimen is re-ignited (or a new specimen inserted), and the test is repeated until the lowest concentration of oxygen needed to support burning is reached. The invention will be further explained with reference to the following examples in which all parts and percentages are by weight. Example I A pad bath, consisting of Antiblaze 19 in which 3% Disperse Red 90 (C.I. 11117) was dissolved, was padded onto Nomex fabric at ambient temperature, then heat treated at 199°C (390°F) for 60 seconds using a Benz oven. Following heat treatment, the dyed Nomex fabric was scoured with an aqueous detergent, then rinsed with perchloroethylene. Color retention was good and the dyeing was level when the fabric was examined for side-to-side and end-to-end dyeing. Example II A print paste was made of Disperse Red 90 (3%) and Antiblaze 19; no other ingredients were added. The dry paste that resulted was printed onto Nomex fabric and heat treated in the same manner as in Example I at 193°C (380°F) for 60 seconds. After scouring and rinsing, also as in Example I, the dye appeared to be well fixed onto the Nomex fabric. Example III Example II was repeated, this time using Disperse Blue 56 (CI-63285), and similar results were obtained. Example IV In the manner of Example I, a pad bath was prepared containing Acid Blue 171 (Acid Blue 3GL-200) and this was padded onto samples of Nomex 455 fabric which was then heat treated at 193°C (380°F) for 90 seconds followed by an aqueous detergent scour and rinse. The procedure was repeated using Acid Green 70 (Acid Olive 3BL-131). The samples thus prepared appeared to have the dyestuff suitably fixed to the fibre. However, the yield was not as great as with the disperse dyes. It is believed that the yield is a function of the solubility of the dye in the flame retardant fluid and that the dyeing mechanism is an equilibrium between the fibre and the flame retardant fluid. Example V An equal mixture containing 0.33% of Disperse Red 60, 0.33% of Disperse Yellow 54 and 0.33% of Disperse Blue 56 was dissolved in neat Antiblaze 19. The solution was heated to a temperature in the range of 177-193°C (350-380°F) and samples of Nomex fabric were immersed in the dye solution for periods of from 15 seconds to 2 minutes. The samples were then scoured with an aqueous detergent solution and then rinsed in perchloroethylene. Analysis of the samples indicates that color yield is improved at higher temperatures and with higher dwell times in the heated fluid. The process of the invention provides a convenient way to dye aramid fibres susceptible to treatment, particularly Nomex fibres, and to impart improved flame-retardancy properties over and above those of the undyed fabric. Example VI Nomex (T-455) fabric was continuously FR finished and dyed be immersion of the fabric through a hot fluid bath containing neat (undiluted) Antiblaze 19 (AB19) and a disperse dyestuff. The hot neat AB19 and 0.5% of Altasol Blue 3N (Disperse Blue 14, CI-61500, 12.5mg) were dissolved in the bath (2.5g). The bath was heated to 191°C (375°F) in an indirect (oil) heated through and the Nomex fabric was passed through the hot fluid with dyestuff having a dwell time of two minutes in the hot fluid. The fabric was squeezed through the nip of two rubber rolls to approximately 110% wet pickup. The fabric was then thoroughly scoured with hot water (60°C (140°F)) and detergent (approximately 0.05% non-ionic detergent). The color yield was observed to be good. Based on phosphorus analysis, the final finished and dyed sample had 3.5% AB19 fixed in the fibre. The fabric was then examined for its flammability properties and the following data were collected: The average percent consumed was 16.7% As reflected by the above data, the flammability characteristics were very good with an average char length of only 3.3cm (1.3 inch) using the FTM-5903 test method. There was no afterglow on the samples which compares to the controls. The consumption in FTM-5905 was only 16.7%. This compares to 25% to 35% for normal Nomex fabrics. As a control, undyed Nomex fabric (T-455) was examined for flammability and the following results noted: Example VII Acid dyes were applied via undiluted flame retardant. Solutions of Acid Blue 3GL 200 (Acid Blue 171) and Acid Olive 3BL 131 (Acid Green 70), both 1%, in AB19 were padded onto T-455 Nomex and heated in a Benz oven at 193°C (380°F) for 60 seconds. The samples were then given a hot water scouring. The dyed samples appeared to have good color retention. Example VIII Disperse Dyes applied via undiluted flame retardant. In a manner similar to Example 1, for comparison, a Nomex sample was also treated with only a 1% solution of Dispersed Dye Red 90 using the same conditions as discussed above. The color retention after scouring was good. Example IX Acid Dyes. In the manner of Example IV, 3% baths of Acid Blue 171 and Acid Green 70 in AB19 were prepared and heated to 104°C (220°F) to insure good dye solubility. The hot dye solutions were applied to the Nomex samples and then passed through a Benz oven at 193°C (380°F) for 90 seconds. The samples were given a hot detergent scour and dried. The dyed samples had good color retention. Example X Application of Acid Dyes via a Flame Retardant. Samples of Nomex were dyed with baths having a dye (2.5% Acid Blue 3GL-200) dissolved in 90/10, 50/50, and 25/75 AB19/water mixtures. All samples were heated in a Benz oven at 177°C (350°F) for either 60 or 120 seconds and at 193°C (380°F) for either 60 or 120 seconds. The samples were given a hot water scour at 60°C (140°F) and then given a process wash in a washing machine. Only the dyed samples which were heated to 204°C (400°F) had good color retention. The surface appearance and hand of the normal processed Nomex fabric is somewhat harsh. It was noted that the treatment with the flame-retardant/solvent system greatly improved the touch of the final finished Nomex fabric. Grab tensile strengths were obtained to determine the potential strength loss of the fabrics which were dyed and finished, and lightfastness for certain samples were also obtained. The results are reported below: Example XI Application of Acid Dyes Using production Type Equipment. A dye formulation was developed for application from a flame-retardant/water mixture that would match the Sage Green shade for the military apparel. This formulation was applied to a plain weave and a twill fabric. The formulation consisted of: 2.00% Irgalan Olive Green 2BC 0.20% Nylanthrene Yellow SL2007 (Yellow 198) 0.20% Irgalan Orange P-2R (Acid Orange 154) dissolved in a 80/20 mixture of AB19/water. The mixture was applied and heated in the manner of Example X; the wet pickup was about 60%. The treated sample was run through the tenter frame at 193°C (380°F) for a dwell time of three minutes. Approximately 10 yards of fabric was dyed. After the heat treatment, the fabrics were scoured in 0.5% nonionic detergent and 0.5% soda ash at 82°C (180°F) and then hot water rinsed. The following data were collected: The shade was very close to the standard Military Sage Green. The fixation was very good based on observation and crocking and the IIIA Washing Test.

Claims: A process of simultaneously dyeing and flame retarding an aramid fibre, characterised by comprising the steps of: (1) contacting dyeable poly(m-phenyleneisophthalamide) fibres or fabric with a solution consisting essentially of a fibre swelling flame-retarding amount of a cyclic phosphonate ester flame retardant which forms the sole fibre-swelling and flame-retarding agent which is represented by the formulae: where a is 0 or 1; b is 0, 1 or 2, c is 1, 2 or 3 and a+b+c is 3; R and R' are the same or different and are alkyl (C₁-C₈), phenyl, halophenyl, hydroxyphenyl, tolyl, xylyl, benzyl, phenethyl, hydroxyethyl, phenoxyethyl, or dibromophenoxymethyl; R² is alkyl (C₁-C₄); and R³ is lower alkyl (C₁-C₄) or hydroxyalkyl (C₁-C₄); -C₄); or where d is 0, 1 or 2; e is 1, 2 or 3; R² is alkyl (C₁-C₄); R³ is lower alkyl (C₁-C₄) or hydroxyalkyl (C₁-C₄); R⁴ is alkyl (C₁-C₄) phenyl, halophenyl, hydroxyphenyl, hydroxyethyl, phenoxyethyl, dibromophenoxyethyl, tolyl, xylyl, benzyl, or phenethyl; and R⁵ is monovalent alkyl (C₁-C₆), chlorophenyl, bromophenyl, dibromophenyl, tribromophenyl, hydroxyphenyl, naphthyl, tolyl, xylyl, benzyl, or phenethyl; divalent alkylene (C₁-C₆), vinylene, o-phenylene, m-phenylene, p-phenylene, tetrachlorophenylene (o, m, or p), or tetrabromophenylene (o, m, or p); of trivalent phenenyl and a disperse dyestuff, an acid dyestuff or both; and (2) heating the aramid fibre treated in step (1) to fix said dye to said fibre. A process as claimed in claim 1 characterised in that the solution is applied by padding onto an aramid fabric. A process as claimed in claim 1 characterised in that the flame retardant and dyestuff are applied as a print paste. A process as claimed in any preceding claim characterised in that the fibre or fabric is heated in step (2) at a temperature in the range of about 177°C (350°F) to about 204°C (400°F). A process as claimed in any preceding claim characterised in that the fibre or fabric is heated in step (2) for a period of from about 30 seconds to about 2 minutes. A process of dyeing and imparting a flame retardant treatment to a dyeable aramid fibre, characterised by comprising the successive steps of: (1) contacting a dyeable poly(m-phenyleneisophthalamide) fibre with a solution consisting essentially of a fibre swelling flame-retarding amount of cyclic phosphonate ester flame retardant which forms the sole fibre-swelling and flame retarding agent and which is represented by the formulae: where a is 0 or 1; b is 0, 1 or 2, c is 1, 2 or 3 and a+b+c is 3; R and R' are the same or different and are alkyl (C₁-C₈), phenyl, halophenyl, hydroxyphenyl, tolyl, xylyl, benzyl, phenethyl, hydroxyethyl, phenoxyethyl, or dibromophenoxymethyl; R² is alkyl (C₁-C₄); and R³ is lower alkyl (C₁-C₄) or hydroxyalkyl (C₁-C₄); or where d is 0, 1 or 2; e is 1, 2 or 3; R² is alkyl (C₁-C₄); R³ is lower alkyl (C₁-C₄) or hydroxyalkyl (C₁-C₄); R⁴ is alkyl (C₁-C₄) phenyl, halophenyl, hydroxyphenyl, hydroxyethyl, phenoxyethyl, dibromophenoxyethyl, tolyl, xylyl, benzyl, or phenethyl; and R⁵ is monovalent alkyl (C₁-C₆), chlorophenyl, bromophenyl, dibromophenyl, tribromophenyl, hydroxyphenyl, naphthyl, tolyl, xylyl, benzyl, or phenethyl; divalent alkylene (C₁-C₆), vinylene, o-phenylene, m-phenylene, p-phenylene, tetrachlorophenylene (o, m, or p) or tetrachlorophenylene (o, m, or p), or tetrabromophenylene (o, m, or p); or trivalent phenenyl and a disperse dyestuff, an acid dyestuff or both, the solution being maintained at a temperature of from about 149°C (300°F) to a temperature not greater than the boiling point of the solution; (2) allowing the fibre to remain in contact with the solution until the dye is fixed to the fibre; and (3) removing and drying the dyed and flame-retardant-treated fibre. A process as claimed in claim 6 characterised in that the solution is maintained at a temperature in the range of about 177°C (350°F) to about 204°C (400° F). A process as claimed in claim 6 or 7 characterised in that the fibre is in contact with the heated solution for from about 15 seconds to about 2 minutes. A process as claimed in any preceding claim characterised in that the solution contains a tinctorial amount of a disperse dye or an acid dye.

Inventors: JOHNSON, JAMES R.
Applicants: BURLINGTON INDUSTRIES, INC.
Application year: 1987
Main classification: D06P3
IPC codes: D06M101, D06P3, C09K21, D06M13, D06P1