SK280774B6 - Apparatus and process for processing cellulosic textile material into flame retardant textiles - Google Patents

Abstract

Apparatus for the effective flame-retardant treatment of textiles includes a chamber (1), entry (12) and exit (13) points for the fabric, a duct (13) located within the chamber (1) for the passage of a gas including ammonia through the textile, recycling means (6, 7, 8) to remove at least some of the gas and return it to the chamber, together with sampling means (15) to monitor the ammonia level within the chamber. Preferably, the fabric passes, in a serpentine manner, over a plurality of rollers (4) within the chamber (1). The chamber may also have a sloping roof (5) to prevent condensed liquid from dripping on to the fabric and a gully (10) to collect the condensed liquid. The initial concentration of ammonia is set at between 70 % and 90 % in order to provide a reservoir of ammonia to compensate for higher ammonia take-up by the fabric at lower temperature.

Description

Technical field

The invention relates to a process for processing cellulosic textile materials into flame-resistant textile materials and to an apparatus used to carry out the process.

BACKGROUND OF THE INVENTION

In a conventional prior art, cellulosic textile materials are converted to flame-retardant materials by impregnating with an aqueous solution of a tetrakis (hydroxyorgano) phosphonium mixture, respectively. composition (hereinafter the abbreviation THP of the composition). The THP mixture may be a THP salt, a partially neutralized derivative of the compound, or a condensate with a nitrogen-containing compound such as urea. Impregnation of the cellulosic material with a THP composition is followed by drying and curing the material with gaseous ammonia to give a cured, water-insoluble polymer that is bonded to the fabric. The ammonia gas can be introduced directly into the chamber through which the textile material is guided, or in a preferred embodiment of the process it is forced to direct the stream of ammonia gas to the substance to be treated and allowed to pass through the substance inside the chamber.

Previous United Kingdom Patents Nos. A-1439608 and A-1439609, where the applicants are the same as in the present invention, a preferred embodiment of a device that is used for this purpose is disclosed, the device comprising a closed chamber having a sealed graft and an outlet for feeding and discharging the processed fabric. further comprising a passageway in said chamber having one or more apertures through which ammonia gas is directed, the ammonia gas being forcedly directed to and processed through the material along said apertures, and further having said chamber provided means for preventing condensation water from dripping onto the treated fabric.

These prior art devices have several drawbacks, in particular, they are unable to provide a sufficient degree of cure of the treated fabric at operating speeds above about 20 meters / minute; the degree of curing is sometimes lower than the required appropriate curing level, so in these cases it is sometimes necessary to reprocess the fabric and, furthermore, due to the use of large volumes of ammonia, the ammonia gas is lost to the ambient atmosphere and polluted.

SUMMARY OF THE INVENTION

According to the present invention, an apparatus capable of processing textiles into flame resistant textiles at higher operating speeds has been developed, and a correspondingly high cure level of the textiles can be achieved in the apparatus, while achieving this high cure level is not susceptible and sensitive to in connection with changes in operating parameters such as fabric speed, moisture content of the fabric being treated, ammonia concentration and curing temperature, and in this apparatus according to the invention optimum utilization of the ammonia volume present is achieved to achieve the desired cure. considerably smaller than in prior art devices, and environmental pollution is also greatly minimized.

The apparatus for treating a cellulosic fabric into a flame-resistant fabric in accordance with the present invention, in which the fabric is subjected to an ammonia-containing gas, comprises a chamber having an inlet and an outlet for introducing and discharging the fabric into and out of the device; at least one passageway is provided within said chamber and the passageway has at least one or all of the apertures disposed along the entire width of the fabric to be processed, the apparatus having means for guiding the fabric to contact the fabric and contacting it the fabric moves over the orifice (s), the means for measuring the amount of ammonia introduced into the chamber, the recycling means adapted to remove at least a portion of said gas from the chamber and to re-introduce the gas into said chamber means for analyzing the ammonia content of the gas and means for measuring the temperature inside the chamber. The present invention also includes a method for processing a cellulosic fabric into a flame-resistant fabric by impregnating the fabric with an aqueous solution of tetrakis (hydroxyorgan a phosphonium composition (THP mixture), followed by at least partial drying of the impregnated fabric so obtained, and then treating the fabric with an ammonia-containing gas in said apparatus, wherein said fabric is passed through said apparatus and from said apparatus wherein at least a portion of said gas is removed and then recycled back to the device in carrying out the process.

The present invention also encompasses a fabric treated by the process and in the apparatus of the present invention which has been made into a flame-resistant fabric by the process and in the apparatus described above.

An essential feature of the process of the present invention is that the amount of ammonia supplied relative to the amount of fabric to be treated can be accurately controlled, and that the chamber in which the curing process takes place is pre-filled with ammonia to form supply of ammonia and allow a slight variation in ammonia utilization relative to the ammonia feed. Under these conditions, the temperature in the chamber gradually increases and the ammonia concentration in the chamber gradually decreases until both parameters reach equilibrium conditions. Once this equilibrium has been reached, the utilization of ammonia is in equilibrium and the amount of ammonia fed has been adjusted to achieve complete polymerization of the THP compound with the minimum amount of unreacted ammonia required.

In carrying out the process of the invention, it is not essential to control the exact ammonia concentration or chamber temperature under equilibrium conditions. By always starting from lower temperatures and using higher concentrations of ammonia, they are ensured under equilibrium conditions, i. j. on reaching a stable equilibrium, so that curing is complete, although these conditions mean that some residual ammonia is removed from the process.

Both the point of introduction of the fabric into the device and the point of removal of the fabric from the device is

In a preferred embodiment of the invention, it is sealed, in a substantially gas-tight manner, by means of flexible seals (e.g. rubber) or flaps. At least one passageway is provided in the chamber for introducing ammonia gas into the chamber, the passageway having at least one opening or perforation through which the ammonia gas flows into the atmosphere inside the chamber while the fabric moves above the opening or perforation. Each perforation may be circular, square, rectangular or elliptical in shape and may be, for example, a series of holes or may be a single slot. In a preferred embodiment of the invention said apertures are arranged substantially across the entire width of the fabric to be treated, with substantially all of the ammonia flowing through the fabric.

In order to be able to process fabrics of varying widths by this process, it is advantageous to have suitable plates or covers to close or cover those portions of the opening set which are not covered by the narrower fabrics. The chamber may have one to four passages, each of which passages may comprise one or more orifices from which ammonia is directed towards and through the fabric to be treated. In a preferred embodiment of the invention, means are provided in the device to ensure that the contact angle between the fabric being processed and the opening is maintained at least 60 °. Although the passage (s) can be arranged anywhere in the chamber, the passage (s) in a preferred embodiment of the invention are arranged in such a way that ammonia is directed to pass through the fabric shortly after the fabric has been introduced into the chamber. At the same time as the treatment of the fabric with ammonia, which is directed to guide the fabric to be processed and through the fabric at the passageway, the fabric is preferably passed through the atmosphere of gaseous ammonia and water vapor present in the chamber. The chamber is preferably provided with a series of rollers which can be driven or run freely so that the fabric to be processed can be guided through the serpentine arrangement through the rollers. After the treated fabric is passed through the atmosphere in the chamber, the cured processed fabric is discharged from the chamber at the exit point.

The fabric that enters the chamber typically contains some moisture, which also produces some water as a byproduct of the reaction when curing, and that water, along with the water supplied with the fabric to be treated, is vaporized in the chamber as water vapor. due to the heat generated during the curing reaction. The vapor concentration in the chamber is preferably kept to a minimum, which can be achieved by allowing condensation of the water vapor on the inner walls of said chamber, which is preferably coupled with the use of a condensation preventing agent condensed water for fabric to be processed. These means to prevent the condensation water from dripping onto the fabric to be treated may be a sloping inclined vault of the chamber together with means for collecting the condensation water at the bottom of the chamber so as not to contact the condensation water with the fabric to be treated, such as a peripheral groove or drain. The condensed water may be collected in the chamber, but is preferably continuously discharged from the chamber. The gases present in the chamber, which are made up of ammonia and water vapor, may be vented outside the chamber by means of an exhaust duct, and thereafter the gases may be returned to the chamber at a location remote from the exhaust duct. according to the invention at the lower space of the chamber. The returning of this gas may be effected by introducing it into a perforated passage over which the fabric to be processed is guided, but in a preferred embodiment of the invention the returning of this gas is effected by introducing it into a perforated tube from which the gas exits into the atmosphere in the chamber. In a preferred embodiment of the invention said exhaust duct is located in the chamber at a location near one or more passages in which openings are provided through which fresh ammonia flows into and through the fabric to be treated, as this is where the maximum heat and vapor is generated. .

The ammonia feed passage and the exhaust duct are preferably located in the upper part of the chamber, while the recycle duct is preferably located in the lower part of the chamber. In an alternative embodiment of the device according to the invention, the ammonia supply passage or the exhaust duct may be located at the bottom of the chamber. The system for withdrawing gases from the chamber and for recycling these gases back to the chamber may be coupled to means for condensing water in the chamber, and in addition to this solution (or, alternatively) the withdrawn gases may be fed to a cooling device to reduce the water content of these the gases before they are recycled back into the chamber. The gas recycled to the chamber may be at about the same temperature as the gas that is discharged through the exhaust duct from the chamber, although in a preferred embodiment of the invention the gas is cooler. If the exhaust gases are cooled externally, i.e. inside said apparatus, the chamber is provided with a heating jacket to reduce condensation in the chamber.

A cooling jacket can also be used to increase the condensed fraction on the walls of the chamber, reducing or eliminating the need for external condensing means. True, in this embodiment too, an exhaust and gas return line or a recycle system for conducting ammonia is used, the purpose of using the recycle system being to obtain a more uniform ammonia concentration within the chamber. The apparatus of the present invention also includes means for taking samples of the atmosphere from inside the chamber, and by analyzing the samples taken, adjusting the feed rate into the chamber is appropriately adjusted, thereby maintaining an equilibrium stable ammonia concentration within the chamber.

The chamber is preferably mounted on a base forming the lower chamber, the lower chamber being connected to the actual chamber by a textile supply and textile discharge point, and at these locations both chambers are in gas-tight contact. In this lower chamber are also provided places for feeding the treated fabric into the device and for discharging the processed fabric from the device, as well as an external gas withdrawal chamber, which is preferably under reduced pressure, which is achieved by coupling and an external exhaust fan.

SK 280774-6

By using this device, the pre-treated cellulose fabric is first impregnated with a tetrakis (hydroxyorganophosphonium blend). fibers are preferably polyester fibers or polyamide fibers, but acrylic fibers (especially modacrylic fibers) may also be used These polyamide fibers may be aliphatic, such as copolymers of alkylenediamines and alkylenedicarboxylic acids (such as nylon 66) or polylactams (e.g. such as nylon 6) or may be aromatic fibers such as aramid fibers based on aromatic dicarboxylic acids and phenylenediamines.

The fabric to be treated may comprise at least 30% cellulosic fibers and up to 70% blendable fibers (such as 10 to 70% and especially 25 to 60% blended fibers), the blended fibers being, for example, polyamide fibers. Particularly important are blended fabrics that contain cellulose fibers and polyester fibers. These blended fabrics preferably contain up to 70% polyester fibers (such as up to 60% polyester fibers) and from 30% cellulose fibers, such as 40% cellulose fibers and more. Examples are blended fabrics containing 1 to 70% or 1 to 60% polyester fibers, such as 15% to 60%, in particular 22% to 38% or 38% to 60% of these fibers, and 30 to 99% cellulose fibers or 40% up to 99% of such fibers, such as 40% to 85%, in particular 62% to 78% or 40% to 62% of cellulose fibers.

In a preferred embodiment of the present invention, mixed fabrics are used which comprise 40% to 78% cellulose fibers and 22% to 60% polyester fibers or 30% to 62% cellulose fibers and 38% to 70% polyester fibers. These cellulose fibers are preferably natural cotton fibers, although ramie, flax or regenerated fibers such as viscose fibers or cuprammonium fibers may also be used. The polyester material may be a condensation product comprising structural units derived from an aliphatic alcohol (such as a dihydric alcohol such as ethylene glycol) and the aromatic dicarbonate. The fabric may be a nonwoven fabric, but preferably a woven fabric is used. The cellulosic fibers in admixture with the other fibers may be in the form of a blend or an imperfect blend, preferably the fibers are in the form of a blend of cellulose fibers and other fibers (such as polyester fibers) as in a co-blend such as for example cotton / polyester staple. Alternatively, the yarns may be wound on a core, the core being, for example, a polyester fiber that is coated with a cotton fiber. In tissues, in a preferred embodiment, the warp thread and the weft thread are the same, but may also be different, such as one thread may be a cotton thread and the other thread is a polyester / cotton thread. In the description of the present invention, a mixed fabric is also meant to include fabrics of two or more materials and mixtures of these fabrics, as well as fibers wound onto a core fiber. Said fabric is preferably a fabric having a weight ranging from 100 to 100

1000 g / m ² , such as a fabric weighing between 150 and 400 g / m ² , which may be, for example, a cotton polyester shirt fabric or a flint fabric or a curtain fabric.

In said tetrakis (hydroxyorgano) phosphonium compound, preferably each hydroxyorgano group is an alpha-hydroxyorgano group having 1 to 9 carbon atoms, in particular a group of the formula:

HOC (R * R ² ), wherein the substituents R ¹ and R ² , which may be the same or different, represent a hydrogen atom or a C 1 -C 4 alkyl group such as a methyl or ethyl group. In a preferred embodiment of the invention, the substituent R ¹ is hydrogen, and in particular it is preferred that both R and R ¹ R ² are hydrogen, for example tetrakis (hydroxymethyl) phosphonium compounds.

The use of said tetrakis (hydroxyorgano) phosphonium compounds generally will be illustrated in the following with the tetrakis (hydroxymethyl) phosphonium compounds (THP compounds), but it is understood that corresponding molar amounts of other tetrakis (hydroxyorgano) phosphonium compounds may also be used.

In a preferred embodiment, the THP composition is a THP salt mixed with a nitrogen-containing compound that is condensable with said THP salt, such as melamine, monomethylated melamine or urea, or may be a precondensate of said THP salt, and said nitrogen-containing compound, or it may be a THP salt or at least partially neutralized a THP-salt, such as a ΊΉΡ-hydroxide, with or without said nitrogen-containing compound.

Preferably, the THP agent is a precondensate of a THP salt (such as ΊΉΡ-chloride or THP-sulfate) and urea in a molar ratio of urea to THP compound in the range of 0.05 to 0.8: 1, such as a ratio of 0.05 to 0.6: 1, for example a ratio of 0.05 to 0.35: 1 or 0.35 to 0.6: 1, and the composition is in the form of an aqueous solution, usually having a pH in from 4 to 6.5, such as from 4 to 5.

The concentration of said organophosphorous compound in the aqueous impregnating solution may range from 5% to 50% by weight (expressed as weight of THP ⁺ ion), such as from 15% to 35% by weight, in particular from 15% to 25% by weight. % by weight. If desired, the solution may contain a wetting agent, such as a nonionic or anionic wetting agent.

In the treatment process of the present invention, the fabric is impregnated with a THP solution, which is then compressed so that the amount of moisture retained is between 30% and 130%, such as between 60% and 100% (based on the original weight) fabrics). Typically less than 40% by weight of the organophosphorus compound, such as 10% to 30% by weight (e.g. 15% to 30% and especially 15% to 25% by weight in the form of THP ⁺ ion) is retained in the fabric after impregnation, based on the original fabric weight .

The impregnated fabric thus obtained is then dried, for example, to a moisture content of from 0% to 20%, such as 5% to 15%, such as about 10%, wherein

The percentage quoted is calculated from the weight gain of the fabric and the weight of the impregnated chemical compounds. The drying is carried out in a tensioning frame or heating drum furnace, such as a steam drum, which can be used to heat the fabric to a temperature of 80 to 120 ° C for 10 minutes to 1 minute.

The dried fabric thus obtained is then introduced into the apparatus of the present invention where it is subjected to curing using ammonia. In a preferred embodiment of the invention, the fabric is introduced into the lower chamber at the point of entry of the fabric into the chamber, then guided through the lower chamber and finally discharged into the actual chamber through the point of entry of the fabric into the chamber. The fabric is then passed over the ammonia feed openings formed in the ammonia inlet passage and the ammonia is forced through the fabric and the fabric.

Subsequently, the fabric is passed through an atmosphere containing ammonia and water vapor formed in the chamber, and then exits the chamber through a fabric discharge point therefrom and then through the lower chamber (if such a lower chamber is used) and exiting the device from the exit point for discharging the treated fabric from the lower chamber.

At the beginning of the process, the chamber is filled with ammonia, which expels air from the chamber through the fabric inlet and outlet points of the chamber and also through additional withdrawals at the base of the chamber which can be adapted for this purpose. This is carried out until the ammonia concentration is at least 40% by volume (as determined by the sampling point and the connected analyzer). The initial ammonia concentration at the start of the process is preferably adjusted to a high level (e.g., 70% to 90%) to produce a certain ammonia stock that is used to compensate for the higher scale ammonia consumption during the initial warm-up period.

The fabric thus prepared is then passed through the chamber, the ammonia supply being calculated in such a way as to ensure that sufficient ammonia is present in the chamber to carry out the chemical reaction to the maximum degree possible and to this amount a certain residual amount is added. unreacted ammonia. The relative molar ratio between the amount of ammonia and phosphorus fed in the THP composition on the fabric ranges from at least 1.2: 1 to higher, and preferably from 1.7:: 1 to 2.2: 1 (when the THP agent is a condensate of a THP salt and a nitrogen-containing compound such as urea) or is at least 1.7: 1, and preferably in the range of 2, 2: 1 to 2.7: 1 (when the THP agent is a THP salt per se or is a partially neutralized derivative of the compound).

During the initial curing stage, the ammonia consumption is slightly higher than the amount of ammonia introduced, and the cured fabric carries residual amounts of unreacted ammonia from said chamber. This means that during this initial stage the ammonia concentration in the chamber decreases, but assuming that the time when the treated fabric is exposed to the atmosphere and the ammonia concentration remains sufficiently high does not mean a reduction in the amount of ammonia trapped on the tissue. During the reaction, heat and steam are generated, with the temperature inside the chamber rising. Ammonia consumption as a result of the reaction with the treated fabric decreases with increasing temperature, whereby an equilibrium state is eventually reached under stable conditions.

Under equilibrium conditions, the ammonia concentration and the chamber temperature remain substantially constant, with the ammonia consumption being in equilibrium with the ammonia feed rate. The ammonia feed rate selected determines the ammonia consumption, which is independent of the ammonia concentration.

Typically, 1 to 20 meters (such as 10 to 20 meters) of fabric is present in said curing chamber at a speed in the range of 5 to 100 meters per minute (such as in the range of 30 to 100 meters per minute) and especially speed ranging from 50 to 80 meters per minute). Sufficient fabric is present in the curing chamber to achieve a contact time between the fabric to be treated and the atmosphere in the chamber of at least 4 seconds, and preferably 10 seconds at the desired fabric speed. The volume of the curing chamber is at least 1.5 times the maximum volume of ammonia that is fed into the chamber per minute. Fresh ammonia gas is preferably not diluted, but can be diluted with up to 30% vapor or air by volume. The ammonia gas flowing through the apertures formed in the passageway to the chamber has a heat in the range of 10 to 120 ° C, but preferably the temperature of the ammonia gas is less than 100 ° C, for example in the range of 10 to 30 ° C.

After the cured fabric thus obtained has been removed from the curing device, the fabric is preferably treated with an oxidizing agent to convert at least some of the trivalent phosphorus contained in the THP composition to the pentavalent phosphorus in the cured polymer, then in a preferred embodiment. neutralizing with an aqueous solution of the base and washing the fabric so treated with water. The oxidizing agent is preferably a peroxy compound, such as an aqueous solution of hydrogen peroxide. In an alternative embodiment of the process of the present invention, the oxidation may be carried out with a gas containing molecular oxygen (such as air), and it is particularly preferred that the gas is drawn or blown through the fabric. In this embodiment, the fabric to be processed is passed through a vacuum slit or perforated tube through which the oxidizing gas is passed and the gas is blown or passed through the fabric.

Overview of the figures in the drawing

A preferred embodiment of the device according to the invention is illustrated in the accompanying drawing, which embodiment is exemplary only. The apparatus of this figure will be described in detail below. The illustration is a schematic vertical cross-section of the device.

SK 280774-6

DETAILED DESCRIPTION OF THE INVENTION

The device according to the invention consists of a chamber 1 having its lower part 2. Inside this chamber 1 there is a gas supply tube 3 which is perforated (not shown) and further there are arranged rollers, with the reference numeral 4 denoting one of these rollers. The chamber 1 further has a sloping inclined vault 5 (or a roof vault), with an exhaust duct 6 located in the upper space of this inclined vault, which is led from the upper chamber 1 to a condenser (not shown) and continues to the exhaust fan 7 wherein a recycle line 8 is discharged from the exhaust fan and is returned to the chamber. The chamber 1 has a cup-shaped tray 9 and an annular or peripheral groove 10 formed along the wall 11 of the chamber 1 in the interior space. On both sides of the cup-shaped tray 9, slots are provided at the feed point 12 to feed the material to be fed into the chamber. 13 for discharging the material to be processed from the chamber, the slots being substantially sealed with rubber flaps 14. The ammonia removal slot 15 is located at the top of the chamber 1.

In the wall 11, at the bottom 2 of the chamber there is a slot 16 for feeding the material to be introduced into the chamber and a slot 17 for removing the material to be processed from the chamber, and a gas outlet slot 18 is provided near the material. The rollers 4 are also arranged in the lower part 2 of the chamber.

In a preferred embodiment of the invention, the chambers 1 also comprise one or more sealed removable panels (not shown) which may be removed, thereby allowing access to the gas supply tube and the rollers. In an alternative embodiment, the chamber may be formed of two portions, one of which is removable, respectively. removable, which also allows access to the interior.

In practical use of the apparatus, the impregnated process material enters the apparatus through the slot 16, then leads to the bottom 2 of the chamber, continues to the slot 12 for introducing the material into the chamber itself, and then passes through the chamber 1. The treated material is passed through a gas supply tube 3 which is perforated and ammonia flows through these openings behind the material to be treated and the material. This material is then passed through a system of rollers 4 through an atmosphere of ammonia and steam formed in the interior of the chamber 1 and then discharged from the chamber 1 through the slot 13 into the bottom 2 of the chamber and into the slot 17 and processed material removed from the equipment. The ammonia vapors are exhausted from the chamber 1, if necessary, by means of recycling means 6, 7, 8, which include an exhaust duct, an exhaust fan and a recycle duct. If necessary, the water is allowed to condense in the condenser (not shown) before re-introducing this gas portion back into chamber 1 by means of the recycled means. All the condensed portion is discharged via a condensation line (not shown).

The steam condenses on the walls 11 of the apparatus, and this condensed steam is collected in a trough 10 from which it is periodically withdrawn (by means not shown). All remainder of the ammonia, together with entrained air and residual water vapor, is removed from chamber 1 via slots 12 and 13 for feeding the material to and from the chamber and together with entrained air and ammonia coming from the discharged process material this portion is aspirated from the bottom 2 of the chamber by a slot 18.

The process of processing cellulosic textile materials into flame-retardant materials and the apparatus for carrying out the process will be explained in more detail below with reference to specific embodiments, which are illustrative only and not limiting.

Example 1

Tetrakis (hydroxymethyl) phosphonium chloride (THPC) and urea precondensate were first prepared, with a molar ratio of urea to THPC of 0.5: 1.0 in this product. The precondensate was then diluted with water to give a solution containing an equivalent amount of 25% THP ⁺ ion. The bleached white cotton pulp weighing 280 grams / m ^{2 was then} soaked in a conduit with this solution to collect approximately 80% moisture. The fabric was dried for 1 minute at 100 ° C. The fabric was then cured on a reduced scale in which 1.2 meters of 0.45 meters wide fabric were present, using a 1.7: 1 ammonia to phosphorus feed rate of ammonia feed and the contact time of the curing atmosphere with the fabric was 14.4 seconds. The ammonia concentration in the apparatus was adjusted to various values before curing began. The cured fabric was then washed on a shaking frame with a cold solution containing 55 grams / liter of hydrogen peroxide, and then washed with a solution containing 2 grams / liter of sodium carbonate at 60 ° C, and finally with cold water and dried. .

After curing and final drying, individual samples were taken and analyzed for phosphorus and nitrogen content. The results obtained are shown in the following Table. First

Table 1

Ammonia concentration in% Increase in N / P ratio during curing P-úännorfv% 40 1.66 91.7 50 1.64 92.3 55 1.64 91.4 65 1.69 92.3 75 1.67 91.7

Example 2

The 5 meter long drell fabric was treated in the same manner as in Example 1, except that a bath containing an equivalent amount of 22.5% THP ⁺ ion was used in this embodiment, the exposure time of the treated fabric to the chamber atmosphere was 24 seconds and the initial ammonia concentration was 80%. The ammonia feed rate was either a 1.7: 1 ammonia to phosphorus ratio or a 2.2: 1 ammonia to phosphorus ratio. When using a feed rate corresponding to a ratio of 1.7:: 1 of ammonia to phosphorus, the ammonia concentration decreased to 69%, but using a feed rate corresponding to an input ratio of 2.2; 1 ammonia to phosphorus remained

2806 the ammonia concentration is constant, that is to say 80%. Samples were taken from both ends of each fabric, and the results are shown in Table 2 below. Second

Table 2

Ammonia / P ratio Ammonia concentration Increase in N / P ratio at cure P-rate in% 1.7 (start) 80 1.85 93.6 1.7 (end) 69 1.84 89.9 2.2 (beginning) 80 1.85 91.9 2.2 (end) 80 1.83 93

Example 3

The precondensate, as in Example 1, was diluted to 27.7% THP ⁺ ions. Thereafter, 1000 meters of dyed cotton drell weighing 266 grams / m ² and 1.52 meters wide was soaked with the solution so that the fabric was pulled through the solution and soaked, the amount of moisture retained by the fabric being 70.3%. The fabric was then dried in a four-part stretcher to a moisture content of about 12%. The fabric was then cured in a curing apparatus of the present invention (this apparatus could receive 13 meters of fabric so treated). At the start of the process, the ammonia concentration was 76%, the speed was adjusted to 32 meters per minute and the ammonia feed rate was 2.2 NH ₃ / P. During this step, the temperature rose to 60 ° C and the ammonia concentration dropped to 67%, then rose to 69%.

Thereafter, the fabric processing speed was increased to 39 meters / minute, the relative amount of ammonia introduced being reduced to a ratio of 1.8 NH ₃ / P. The temperature of the reaction continuously increased to 77 ° C and the ammonia concentration first decreased to 68% and then increased to 83%.

The fabric was then washed with hydrogen peroxide, then with sodium carbonate and water in a continuous rinse and finally dried.

During this procedure, 13 samples were taken at regular intervals. All these samples met the requirements of BS 6249 B both before and after 50 washes at 93 ° C, as specified in DIN 53920 clause 4.1. The mean phosphorus content of the samples thus treated was 2.92%, with a coefficient of variation of only 5.3%.

Example 4

According to this example, 1000 meters of drell fabric was treated in the same manner as in Example 1, but using a bath containing 27.0% THP ⁺ ions, the amount of moisture trapped being 74.2%. Curing was carried out at an ammonia concentration of 68% and a fabric speed of 40 meters per minute, the ammonia feed rate corresponding to a ratio of 1.8 NH ₃ / P. The curing temperature rose to 73 ° C and the ammonia concentration dropped to 36%, after which it increased again to 53%.

During this procedure, 17 samples were taken. All samples met the requirements of BS 6249 Class B, both before and after washing at 93 ° C and the number of washes was 50, as specified in DIN 53920 Clause 4.1. The average phosphorus content of the samples thus treated was 2.67%, with a coefficient of variation of only 3.3%.

Example 5

In the procedure of this example, 500 meters of white cotton sheet having a weight of 178 grams / m ² and a width of 1.52 meters was treated in the same manner as in Example 4, the amount of moisture trapped being 92.9%. The curing was carried out immediately after the procedure of Example 4, the starting conditions being: ammonia concentration of 53%, temperature of 73 ° C, fabric speed of 40 meters / minute and ammonia feed rate of 2.16 NH ₃ / P. The temperature remained stable at 73-74 ° C, but the ammonia concentration rose to 82%.

During this procedure, 10 samples were taken, all of them meeting the requirements of BS 6249 Class B both before and after the wash at 93 ° C and 50 washes as specified in DIN 53920 Clause 4.1. The average phosphorus content of the samples thus treated was 2.83%, with a coefficient of variation of only 2.5%.

Example 6

1000 meters of drell fabric was treated in the same manner as in Example 4, except that cooling of the recirculated gases was performed. The cloth soaking bath contained 26.2% THP ⁺ ions and the amount of moisture trapped was 84%. The initial ammonia concentration in this embodiment was 82%, with a cure rate of 48 meters / minute and an ammonia feed rate of 1.7 NH ₃ / P. The temperature in this process rose to 67 ° C and the ammonia concentration dropped first to 52% and then rose to 55%.

During this procedure, 8 samples were taken. All of these samples met the requirements of BS 6249 Class B both before and after the wash at 93 ° C and the number of washes was 50 as specified in DIN 53920 clause 4.1. The mean phosphorus content of the treated samples was 2.85%, with a deviation coefficient of only 4.7%.

Example 7

A narrow width, 3500 meter long cotton sheet having a weight of 178 grams / m ² and a width of 0.96 meters was treated in the same manner as in Example 6, but according to this example. In an embodiment, a bath containing 30.2% THP ⁺ ions was used and the amount of trapped moisture was 68%. The initial ammonia concentration was 78%, with a curing rate of 52 meters / minute and an ammonia feed rate of 2.1 NH ₃ / P. The processing temperature first increased to 58 ° C while the ammonia concentration dropped to 37% and then rose to 43%.

During this procedure, 11 samples were taken. All these samples met the requirements of the standard

BS 6249 Class B, both before and after the wash at 74 ° C and 50 washes as specified in BS 5651:

6.5.3. These washed samples were also 7

Evaluated as non-inflammatory using the BS 7175 Section 3: Ignitability of individual Bedcovers test when ignition sources 0, 1 and 5 were used. The average phosphorus content of the treated samples was 2.79% with a deviation coefficient of 9 , 2%.

Example 8

A narrow width of 9000 meters of cotton sheet was treated in the same manner as in Example 7, but using a bath containing 21.7% THP ⁺ ions and the amount of moisture trapped. was 81%. The curing was carried out in the form of three batches, with a curing rate of 53 meters / minute and an ammonia feed rate of 2.1 NH ₃ / P. For all three batches, the temperature rose to an equilibrium value in the range of 58 to 60 ° C while the ammonia concentration fell to a range of 45 to 50%.

During the processing of this treatment, 13 samples were taken. All samples met the requirements of BS 6249 Class B both before and after the wash at 74 ° C and the number of washes was 3, as specified in BS 5651: 1989 clause 6.5.3. The average phosphorus content of the samples thus treated was 2.54%, with a coefficient of variation of only 3.8%.

Claims (13)

PATENT CLAIMS A method of processing cellulosic textile materials into flame-retardant materials, comprising the steps of: (I) impregnating the textile material with an aqueous solution of a tetrakis (hydroxyorgano) phosphonium composition (THP), the aqueous solution comprising 5% to 50% by weight of THP ions, in particular 15% to 25% by weight of said ions, and at least partially drying the impregnated textile material (II) treating said impregnated textile material with an ammonia-containing gas in a chamber apparatus wherein the initial ammonia concentration in said gas is between 70% and 90% and the ratio of ammonia in the gas to the THP composition is at least 1.2: 1, ( III) discharging the treated textile material from the apparatus together with at least a portion of the ammonia-containing gas, which gas is recycled back to the apparatus during the process. Method according to claim 1, characterized in that the treated textile material consists essentially of cellulose fibers selected from the group consisting of natural cotton fibers, ramie fibers, flax fibers or regenerated fibers. Method according to claims 1 or 2, characterized in that the textile material comprises a mixture of cellulosic fibers and other fibers intertwined or spinnable with these cellulosic fibers, such as polyester fibers, such as copolymers of alkylenediamines and alkylenedicarboxylic acids, polyamide fibers, polylactam fibers and aramid fibers. The method according to claim 3, characterized in that said textile material comprises up to 30% by weight of cellulose fibers and a corresponding proportion of up to 70% by weight of polyster fibers. A method according to any one of claims 1 to 4, characterized in that the textile material is a woven fabric or the textile material comprises a gimped core yarn. Process according to one of Claims 1 to 5, characterized in that the tetrakis (hydroxyorganophosphonium composition (THP)) comprises hydroxyorgano groups of the general formula: HOC (R'R ² ), wherein R ¹ and R ² , which may be the same or different, represent substituents selected from the group consisting of hydrogen and C 1 -C 4 alkyl groups such as methyl or ethyl. The method of claim 6, wherein the THP composition is a THP salt, such as a chloride or sulfate, a partially neutralized THP salt derivative, and a mixture of a THP salt and a nitrogen-containing compound such as urea, melamine or monomethylated melamine, or a precondensate of a THP salt and a nitrogen-containing compound. Process according to one of Claims 1 to 7, characterized in that the ratio of ammonia to the THP composition is in the range from 1.7 to 2.2: 1, expressed as NH ₃ : P, when the THP is the composition is a precondensate mixture and the ratio is in the range of 2.2 to 2.7: 1, expressed as the NH ₃ : P ratio when the THP composition is a THP salt. Method according to one of Claims 1 to 8, characterized in that after the textile material has been removed from the apparatus, the textile material is treated with an oxidizing agent, such as an aqueous solution of hydrogen peroxide or a gas containing molecular oxygen. 10. The method of claim 9, wherein after oxidation, the textile material is neutralized with an aqueous solution of a base such as sodium carbonate. 11. The method of claim 10 wherein after neutralizing the textile material, the textile material is washed with water and dried. Device for carrying out the method according to any one of claims 1 to 11, characterized in that it comprises a chamber (1) with a textile supply point (12) and a textile supply point (13) from the chamber (1), sealed in conjunction with the chamber in a gas-tight manner, the apparatus further having at least one tube (3) disposed within the chamber (1) having at least one opening which is situated or spaced along the entire width of the fabric to be processed, means for closing all parts said openings not covered by said material and means for contacting said textile material with said tube (3) and along said openings, further means for recycling said gas (6, 7, 8) to remove at least a portion of said ammonia gas from said chamber (1); for returning to said chamber, and means (15) for analyzing the ammonia content of the gas, means for measuring the amount of ammonia introduced into the chamber (1) and means for measuring the temperature inside the chamber (1). Apparatus according to claim 12, characterized in that it comprises means for maintaining an angle of contact between the textile material and the opening of less than 60 ° C.