FLAME RETARDANT CELLULOSIC MAN-MADE FIBERS

Abstract

A process for the production of an oxidized polymer from a tetrakis hydroxyalkyl phosphonium compound comprising NH.sub.3 or at least one nitrogen compound comprising at least one NH.sub.2 or at least two NH groups, or NH.sub.3, comprising the steps of: (a) reacting at least one tetrakis hydroxyalkyl phosphonium compound with NH.sub.3 or at least one nitrogen compound in order to obtain a precondensate, wherein the molar ratio of the tetrakis hydroxyakyl phosphonium compound to the nitrogen compound is in the range of 1:(0.05 to 2.0), preferably in the range of 1:(0.5 to 1.5), particularly preferably in the range of 1:(0.65 to 1.2), (b) crosslinking the precondensate obtained in process step (a) with the aid of ammonia to form a crosslinked polymer, (c) oxidizing the crosslinked polymer obtained in step (b) by adding an oxidizing agent to the oxidized polymer, wherein, in step (b), the precondensate from step (a) and the ammonia are each injected by means of a nozzle into a reactor space enclosed by a reactor housing onto a common collision point.

Claims

1. A process for the production of an oxidized polymer from a tetrakis hydroxyalkyl phosphonium compound comprising NH.sub.3 or at least one nitrogen compound comprising at least one NH.sub.2 or at least two NH groups, or NH.sub.3, comprising the steps of: (a) reacting at least one tetrakis hydroxyalkyl phosphonium compound with NH.sub.3 or at least one nitrogen compound in order to obtain a precondensate, wherein the molar ratio of the tetrakis hydroxyalkyl phosphonium compound to the nitrogen compound is in the range of 1:(0.05 to 2.0), (b) crosslinking the precondensate obtained in process step (a) with the aid of ammonia to form a crosslinked polymer, (c) oxidizing the crosslinked polymer obtained in step (b) by adding an oxidizing agent to the oxidized polymer wherein, in step (b), the precondensate from step (a) and the ammonia are each injected by means of a nozzle into a reactor space enclosed by a reactor housing onto a common collision point.

2. The process according to claim 1, wherein, in step (b), the precondensate from step (a) and the ammonia are each injected by means of a nozzle into a reactor space enclosed by a reactor housing onto a common collision point, wherein the resulting products are removed from the reactor housing through an opening by means of negative pressure on the product and gas outlet side.

3. The process according to claim 1, wherein, in step (b), the precondensate from step (a) and the ammonia are each injected by means of a nozzle into a reactor space enclosed by a reactor housing onto a common collision point, wherein a gas, an evaporating liquid, a cooling liquid or a cooling gas is introduced via an opening into the reactor space for maintaining the gas atmosphere in the interior of the reactor, in particular at the collision point of the jets of liquid, or, respectively, for cooling the resulting products, wherein the resulting products and excess gas are removed from the reactor housing through another opening by means of overpressure on the gas inlet side.

4. The process according to claim 1, wherein the nitrogen compound is selected from the group of urea, thiourea, biuret, melamine, ethylene urea, guanidine and dicyandiamide.

5. The process according to claim 1, wherein, in step (b), on the one hand, the precondensate and, on the other hand, ammonia are provided as liquid media and sprayed onto the collision point.

6. The process according to claim 5, wherein, in the case of the precondensate, the liquid medium is an aqueous solution, and, in the case of ammonia, the liquid medium is an aqueous solution.

7. The process according to claim 1, wherein soluble reaction products are separated after the oxidation according to step (c).

8. The process according to claim 1, wherein the alkyl radical of the tetrakis hydroxyalkyl phosphonium compound comprises methyl, ethyl, propyl or butyl.

9. A process for the production of flame retardant cellulosic man-made products from a spinning dope, comprising: providing a polymer from a tetrakis hydroxyalkyl phosphonium compound produced according to claim 1, mixing it with a cellulose-based spinning dope, wherein the polymer comprises a tetrakis hydroxyalkyl phosphonium compound in the form of an aqueous dispersion in an amount of 5% by weight to 50% by weight, based on the cellulose, and spinning the spinning dope through a spinneret into a spinning bath.

10. The process according to claim 9, wherein the man-made products are man-made fibers, wherein filaments are formed as the spinning dope is being spun through a spinneret into a spinning bath, whereupon the filaments are drawn and precipitated, wherein, subsequently, an aftertreatment by washing, bleaching, finishing is provided.

11. The process according to claim 9, wherein the spinning dope is a solution of cellulose in an aqueous tertiary amine oxide.

12. The process according to claim 9, wherein the spinning dope is a solution of cellulose in the form of a cellulose xanthogenate.

13. The process according to claim 9, wherein the spinning dope is an ammoniacal solution of cellulose in tetraamine copper(II) hydroxide.

14. The process according to claim 9, wherein the spinning dope is a solution of cellulose in an ionic liquid.

15. A cellulosic man-made product, comprising a flame retardant comprising an oxidized polymer from a tetrakis hydroxyalkyl phosphonium compound with at least one nitrogen compound comprising at least one NH.sub.2 or at least two NH groups or NH.sub.3 with a particle size d.sub.99 of <1.8 m.

16. The cellulosic man-made product according to claim 15, where it is a textile fiber having a fineness of >=0.9 dtex up to <=3 dtex.

17. The cellulosic man-made product according to claim 15, wherein the proportion of the flame retardant is between 5% by weight and 50% by weight.

18. The cellulosic man-made product according to claim 15, wherein the strength ranges from 18 cN/tex to 50 cN/tex.

19. The process according to claim 1, wherein the molar ratio of the tetrakis hydroxyalkyl phosphonium compound to the nitrogen compound is in the range of 1:(0.5 to 1.5).

20. The process according to claim 19, wherein the molar ratio of the tetrakis hydroxyalkyl phosphonium compound to the nitrogen compound is in the range of 1:(0.65 to 1.2).

21. The process according to claim 7, wherein the soluble reaction products are separated after the oxidation according to step (c) by means of tangential flow filtration.

22. The cellulosic man-made product of claim 15, wherein the particle size d.sub.99 is <1.7 m.

23. The cellulosic man-made product of claim 22, wherein the particle size d.sub.99 is <1 m.

24. The cellulosic man-made product according to claim 17, wherein the proportion of the flame retardant is between 10% by weight and 30% by weight.

25. The cellulosic man-made product according to claim 24, wherein the proportion of the flame retardant is between 15% by weight and 25% by weight

Description

[0057] FIG. 1 schematically shows step (b) of the process in a reactor.

[0058] FIG. 2 schematically shows step (d) of the process.

[0059] In FIG. 1, a reactor housing with a reactor space is shown, wherein the precondensate R1 from step (a) is introduced laterally into the reactor space. Ammonia R2 is also introduced into the reactor space, whereby the precondensate R1 and the ammonia R2 meet at a collision point. For discharging the reaction products, a gas can be introduced via an opening 1, which exits with the reaction product on the gas outlet side 2. It has also been shown that the precondensate R1 and the ammonia R2 are brought to a collision point without a carrier gas being introduced via the opening 1. In such a configuration, the reactor housing can be operated for gas with the reactor space and a closed opening 1. The reaction product can then be removed via the gas outlet side 2 by means of negative pressure.

[0060] FIG. 2 shows the purification step (d), wherein, initially, the reaction product from step (c) is introduced as a feed 11 into a storage tank 12. Via the pump 16, it is purified across a membrane 14, e.g., by tangential flow filtration. The retentate 13 is returned into the storage tank 12. The permeate 15 is discharged.

EXAMPLE 1

Production of a Flame Retardant Dispersion Using a Microjet Reactor (MJR) and Subsequent Spinning of Flame Retardant Fibers According to the Viscose Process

[0061] The production of the precondensate is performed analogously to AT 510 909 A1, wherein tetrakis hydroxymethyl phosphonium chloride (THPC) is used as the starting component for the reaction with urea instead of tetrakis hydroxymethyl phosphonium sulfate.

[0062] The crosslinking of the obtained precondensate with ammonia is subsequently carried out in a microjet reactor. To this end, the obtained precondensate as a 10 wt % solution is continuously metered as a precondensate stream onto position R1 of the MJR at a pressure of 11 bar, upon addition of 12% by weight of polyvinylpyrrolidone (Duralkan INK 30), based on the precondensate. As an ammonia stream, an ammonia solution of 1.5% by weight is continuously metered at position R2 at a pressure of 11 bar. The reaction product emerging at the product or, respectively, gas outlet side 2 is collected, mixed with H.sub.2O.sub.2 and stirred for 30 min at a temperature not higher than 40 C., wherein the molar ratio between the precursor of the flame retardant (precondensate) and the oxidizing agent is 1:1. A suspension with a solids content of oxidized, crosslinked precondensate of 4.9% is obtained. The particle size d.sub.99 is 1.79 m.

[0063] The oxidized, crosslinked precondensate is subsequently purified by tangential flow filtration (FIG. 2) and concentrated. For this purpose, 12.3 kg of suspension is filled into the storage tank and processed for 4 cycles across a polyethersulfone membrane (150 kDa and 0.6 m.sup.2 filter area) at a pressure of 2 bar. After cycles 1 to 3, it is, in each case, diluted with deionized water so that the initial weight in the storage tank is 12.3 kg. After 4 cycles over a total duration of 2.5 hours, 4.3 kg of suspension with a solids content of 14.7% is obtained.

[0064] The suspension produced is particularly suitable for the production of flame retardant cellulosic moulded bodies.

[0065] The proportion of the flame retardant in the cellulosic man-made fiber, in the form of a viscose or Lyocell fiber, can be between 5% by weight and 50% by weight, preferably between 10% by weight and 30% by weight, particularly preferably between 15% by weight and 25% by weight, based on the fiber. If the proportion is too low, the flame-retardant effect will be insufficient, and if the proportions exceed a recommended limit, the mechanical properties of the fiber will deteriorate excessively. With those proportions, a flame retardant cellulosic man- made fiber can be obtained which is characterized in that the strength in the conditioned state ranges from 18 cN/tex to 50 cN/tex.

[0066] From a beech pulp (R18=97.5%), a viscose having the composition 6.0% cellulose/6.5% NaOH was produced, wherein 40% of CS2 was used. A modifier (2% dimethylamine and 1% polyethylene glycol 2000, in each case based on cellulose) and 22%, based on cellulose, of the flame retardant in the form of the 14.7% dispersion were added to the viscose with a spinning gamma value of 62 and a viscosity of 120 falling ball seconds. The mixed viscose was spun into a spinning bath having the composition 72 g/l sulfuric acid, 120 g/l sodium sulfate and 60 g/l zinc sulfate at a temperature of 38 C. with 60 m nozzles, was drawn to 120% in a secondary bath (water at 95 C.) and was pulled off with 42 m/min. The aftertreatment (hot diluted H.sub.2SO.sub.4/water/desulphurisation/water/bleaching/water/finishing) was performed according to known methods. A fiber with a titre of 2.19 dtex, a strength (conditioned) of 21.2 cN/tex and a maximum tensile elongation (conditioned) of 12.4% was obtained.

EXAMPLE 2

Production of a Flame Retardant Dispersion Using a Microjet Reactor (MJR) and Subsequent Spinning of Flame Retardant Fibers According to the Lyocell Process

[0067] The production of the precondensate is performed analogously to AT 510 909 A1, wherein tetrakis hydroxymethyl phosphonium chloride (THPC) is used as the starting component for the reaction with urea instead of tetrakis hydroxymethyl phosphonium sulfate.

[0068] The crosslinking of the obtained precondensate with ammonia is subsequently carried out in a microjet reactor. To this end, the obtained precondensate as a 10 wt % solution is continuously metered as a precondensate stream onto position R1 of the MJR at a pressure of 11 bar, upon addition of 5% by weight of an esterified polycarboxylate (Viscocrete P-510), based on the precondensate. As an ammonia stream, an ammonia solution of 1.5% by weight is continuously metered at position R2 at a pressure of 11 bar. The reaction product emerging at the product or, respectively, gas outlet side 2 is collected, mixed with H.sub.2O.sub.2 and stirred for 30 min at a temperature not higher than 40 C., wherein the molar ratio between the precursor of the flame retardant (precondensate) and the oxidizing agent is 1:1. A suspension with a solids content of oxidized, crosslinked precondensate of 5.3% is obtained. The particle size d.sub.99 is 1.71 m.

[0069] The oxidized, crosslinked precondensate is subsequently purified by tangential flow filtration (FIG. 2) and concentrated. For this purpose, 12.3 kg of suspension is filled into the storage tank and processed for 4 cycles across a polyethersulfone membrane (150 kDa and 0.6 m.sup.2 filter area) at a pressure of 2 bar. After cycles 1 to 3, it is, in each case, diluted with deionized water so that the initial weight in the storage tank is 12.3 kg. After 4 cycles over a total duration of 2.5 hours, 4.3 kg of suspension with a solids content of 16% is obtained.

[0070] The suspension produced is particularly suitable for the production of flame retardant cellulosic moulded bodies.

[0071] The proportion of the flame retardant in the cellulosic man-made fiber, in the form of a viscose or Lyocell fiber, can be between 5% by weight and 50% by weight, preferably between 10% by weight and 30% by weight, particularly preferably between 15% by weight and 25% by weight, based on the fiber. If the proportion is too low, the flame-retardant effect will be insufficient, and if the proportions exceed a recommended limit, the mechanical properties of the fiber will deteriorate excessively. With those proportions, a flame retardant cellulosic man-made fiber can be obtained which is characterized in that the strength in the conditioned state ranges from 18 cN/tex to 50 cN/tex. 22%, based on cellulose, of the flame retardant in the form of the 16% dispersion was added to the slurry (mixture of pulp/aqueous NMMO) and water was evaporated to produce a fiber-free spinning solution having the composition 12% cellulose/77% NMMO/11% water. A sulphate high-alpha pulp was used as the pulp.

[0072] According to the established wet-dry spinning process, the spinning dope was spun at a spinning temperature of 110 C. into a spinning bath containing 25% NMMO having a temperature of 20 C. to form 2.2 dtex fibers, with the aid of a 100 m nozzle. Fibers with a strength (conditioned) of 35.0 cN/tex and a maximum tensile elongation (conditioned) of 13.3% were obtained.