Process of making flame retardant cellulosic man-made fibers

Patent metadata

Field	Value
Publication number	US-9988743-B2
Application number	US-201113993718-A
Country	US
Kind code	B2
Filing date	Dec 9, 2011
Priority date	Dec 20, 2010
Publication date	Jun 5, 2018
Grant date	Jun 5, 2018

Abstract

The invention relates to flame-retardant cellulosic man-made fibers containing a flame-retardant substance in the form of an oxidized condensate of a tetrakis hydroxyalkyl phosphonium salt with ammonia and/or a nitrogenous compound which contains one or several amine groups whereby the fiber has a tenacity of more than 18 cN/tex in a conditioned state. Production process and the use of the fibers according to the invention are further objects of the invention.

First claim

The invention claimed is:

1. A process for the production of flame-retardant cellulosic man-made fibers from a spinning mass comprising the following steps:
(a) producing a viscose of cellulose xanthogenate from a pulp with an R-18 content of 93-98%, wherein the viscose has a cellulose content of between 4 and 7%, an alkali ratio of between 0.7 and 1.5, and a carbon disulphide content of between 36 and 42 weight percent in relation to cellulose;
(b) adding between 1 and 5 weight percent of a modification agent, in relation to cellulose;
(c) adding 5 to 50 weight percent of a flame-retardant agent in relation to the cellulose in the form of a aqueous dispersion of the flame retardant agent, wherein the flame retardant agent consists of an oxidized condensate of a tetrakis hydroxyalkyl phosphonium salt with ammonia;
(d) spinning of spinning mass through a spinneret into a spinning bath, wherein the spinning mass has a spinning gamma value of between 50 and 68 and a die spinning viscosity of between 50 and 120 falling ball seconds, wherein the spinning bath has a temperature of between 34 and 48° C., wherein the spinning bath contains 68-90 g/l H 2 SO 4 , 90-160 g/l Na 2 SO 4 , and 30-65 g/l ZnSO 4 ; and wherein a final drawing-off from the spinning bath is performed at a speed of between 15 and 60 m/min;
(e) stretching of precipitated filaments;
(f) providing after-treatment via washing, bleaching, and finishing; and
(g) cutting to staple fibers having a strength of more than 18 cN/tex in the conditioned state.

2. A process for the production of flame-retardant cellulosic man-made fibers comprising adding a flame-retardant agent prior to extrusion of a spinning mass, wherein the flame-retardant agent consists of an oxidized condensate of a tetrakis hydroxyalkyl phosphonium salt with ammonia, wherein a share of flame-retardant agent in the cellulose fiber equals 5 weight percent to 50 weight percent, wherein said fiber is produced according to a lyocell process, wherein said fiber has a strength of more than 18 cN/tex in the conditioned state.

3. The process according to claim 2 , wherein the flame-retardant agent is washed with acid and finally with water in order to produce a dispersion thereof before adding the dispersion to the spinning mass.

4. The process for the production of flame-retardant cellulosic man-made fibers according to claim 1 , wherein the spinning gamma value is between 55 and 58.

5. The process according to claim 2 , wherein the share of flame-retardant substance in the cellulose fiber is between 10 and 30 weight percent.

6. The process according to claim 2 , wherein the share of flame-retardant substance in the cellulose fiber is between 15 and 25 weight percent.

7. The process according to claim 1 , wherein the flame-retardant agent is washed with acid and finally with water before adding to the spinning mass before producing the dispersion thereof.

8. A process for the production of flame-retardant cellulosic man-made fibers from a spinning mass comprising the following steps:
(a) producing a viscose of cellulose xanthogenate from a pulp with an R-18 content of 93-98%, wherein the viscose has a cellulose content of between 4 and 7%, an alkali ratio of between 0.7 and 1.5, and a carbon disulphide content of between 36 and 42 weight percent in relation to cellulose;
(b) adding between 1 and 5 weight percent of a modification agent, in relation to cellulose;
(c) adding 5 to 50 weight percent of a flame-retardant agent in relation to the cellulose in the form of a aqueous dispersion of the flame retardant agent, wherein the flame retardant agent consists of an oxidized condensate of a tetrakis hydroxyalkyl phosphonium salt with ammonia and a nitrogenous compound which contains one or several groups of amine groups;
(d) spinning of spinning mass through a spinneret into a spinning bath, wherein the spinning mass has a spinning gamma value of between 50 and 68 and a die spinning viscosity of between 50 and 120 falling ball seconds, wherein the spinning bath has a temperature of between 34 and 48° C., wherein the spinning bath contains 68-90 g/l H 2 SO 4 , 90-160 g/l Na 2 SO 4 , and 30-65 g/l ZnSO 4 ; and wherein a final drawing-off from the spinning bath is performed at a speed of between 15 and 60 m/min;
(e) stretching of precipitated filaments;
(f) providing after-treatment via washing, bleaching, and finishing; and
(g) cutting to staple fibers having a strength of more than 18 cN/tex in the conditioned state.

9. A process for the production of flame-retardant cellulosic man-made fibers comprising adding a flame-retardant agent prior to extrusion of a spinning mass, wherein the flame-retardant agent consists of an oxidized condensate of a tetrakis hydroxyalkyl phosphonium salt with ammonia and a nitrogenous compound which contains one or several groups of amine groups, wherein a share of flame-retardant agent in the cellulose fiber equals 5 weight percent to 50 weight percent, wherein said fiber is produced according to a lyocell process, wherein said fiber has a strength of more than 18 cN/tex in the conditioned state.

Assignees

• Ruef Hartmut
• Bisjack Clemens
• Kroner Gert
• Chemiefaser Lenzing Ag

Inventors

• RÜF Hartmut
• Bisjack Clemens
• Kroner Gert

Classifications

• C09K21/12

  containing phosphorus · CPC title

• Y10T428/249921

  Web or sheet containing structurally defined element or component · CPC title

• D01F2/00

  Monocomponent artificial filaments or the like of cellulose or cellulose derivatives; Manufacture thereof · CPC title

• D01F1/07

  for making fire- or flame-proof filaments · CPC title

• D01D5/06

  Wet spinning methods {(D01D5/0046 takes precedence)} · CPC title