US3421923A - Process for flame-proofing of cellulose-containing textiles - Google Patents

Description

United States Patent 3,421,923 PROCESS FOR FLAME-PROOFING OF CELLULOSE-CONTAINING TEXTILES Christian Goth, Basel, Switzerland, assignor t0 'Ciba Limited, Basel, Switzerland, a Swiss company No Drawing. Filed June 22, 1965, Ser. No. 466,117 Claims priority, application Switzerland, July 10, 1964,

9,064/64 U.S. Cl. 11762.2 7 Claims Int. Cl. D06m 13/54 ABSTRACT OF THE DISCLOSURE The present invention concerns the treatment of cellulose-containing textiles with a tetrakis-(hydroxymethyl)- phosphonium salt, preferably with tetrakis-(hydroxymethyl)-phosphonium chloride, which is abbreviated in what follows as THPC, or with tris-(hydroxymethyl)' phosphine oxide.

The use of THPC for the flame-proofing of cellulose textiles is known. Eight development stages can be dis tinguished. To begin with, it was recommended to impregnate aminated cellulose with THPC as such or in admixture with melamine or methylolmelamine and then to carry out the fixation by heat treatment, cf. US. Patent 2,668,096, patented Feb. 2, 1954, to Wilson A. Reeves and John D. Guthrie, New Orleans, U.S.A. Further development was represented by the proposal to use polymerisable precondensates of THPC with urea, melamine or formaldehyde condensation products of amides such as urea or melamine. The process was now recommended also for mercerized cotton or for viscose, cf. British Patents 740,269 to Albright & Wilson Limited, Oldbury, Warwickshire, England, published Nov. 9, 1955; and 761,985 to Albright & Wilson Limited, Oldbury, Warwickshire, England, published Nov. 21, 1956. As the thermo-fixation of THPC or of THPC precondensates was not satisfactory, a third stage in the development was proposed, namely the treatment of the impregnation agents with gaseous ammonia or with aqueous ammonia. This treatment brought about a certain degree of improvement but the fixation was still too slow, of. U8. Patent- 2,772,188 and British Patent 882,993 to Albright & Wilson Limited, Oldbury, Warwickshire, England, published Nov. 22, 1961. As a result an attempt was made to expedite the ammonia fixation by the addition of sodium hydroxide or sulfite. A further proposal was to treat the cellulose textiles with aqueous emulsions of an aminoplast-THPC-precondensate and dispersions of hardened THPC-precondensates. The sixth development stage concerns the proposal to treat the cellulose textiles first of all with an aminoplast with dry hardening and then with a THPC-precondensate. The treatment with the aminoplast consists in impregnation with an aqueous solution 3,421,923 Patented Jan. 14, 1969 followed by hardening of the aminoplast, preferably by heat treatment. The fixation of the subsequently applied THPC-precondensate was brought about by thermo-fixation, cw. British Patent 884,785 to Bradford Dyers Association Limited, Bradford 1, Yorkshire, England, and Albright & Wilson Limited, Oldbury, Birmingham, Warwickshire, England, published Dec. 20, 1961. Further progress was brought about by the seventh development stage which recommended the fixation of the THPC-precondensates applied to the fibres, not with ammonia gas or ammonium hydroxide but with ammonia gas and ammonium hydroxide cf. US. Patent 2,983,623, patented May 9, 1961 to Harold Coates, Wombourn, England, and British Patent 906,314 to Albright & Wilson Limited, Oldbury, Warwickshire, England, published Sept. 19, 1962. The last proposal returns to the treatment of cellulose textiles with THPC alone which is applied in a bath at a pH of 3 to 9.5. The THPC is fixed on the fabric by heat treatment after which an after-treatment with gaseous ammonia or with ammonium hydroxide is carried out, cf. British Patent 938,990.

All the processes mentioned so far have certain disadvantages. Of these it is worth mentioning in particular the occurrence of a stiffening effect, an insufficient washfastness and therefore loss of the fl'ameresisting effect as well as especially a considerable reduction in the tensile strength and tear strength of the treated textiles. A disadvantage occurs in the use of precondensates because these are largely unstable condensation products. For example not more than 16 parts urea may be added to 63 parts THPC otherwise polymerisation occurs, cf. British Patent 906,314 to Albright & Wilson Limited, Oldbury, Warwickshire, England, published Sept. 19, 1962.

It has now been found that cellulose-containing textiles can be flame-proofed without the above mentioned various disadvantages occurring. The process consists in that a cellulose fabric treated with an aminoplast, in which the hardening of the aminoplast is brought about by a special process, is padded with an aqueous solution of THPC, dried and then after-treated with gaseous and/or aqueous ammonia. The essential features of the process are that the aminoplast is not hardened by drying and/ or heating but wet in the presence of the impregnation liquid, that THPC as such is used that the latter is not thermo-fixed. It is particularly surprising that no washfast fixation of the THPC is obtained by thermofixation of the aminoplast for 5 minutes at C. and subsequent THPC treatment, but that wash-fast fixation occurs with a fabric on which the aminoplast has been hardened in the presence of the impregnation liquid.

The object of the present invention is thus a process for the flameproofing of cellulose-containing textiles wherein the textile material is impregnated in a first stage with a water soluble hardenable aminoplast, the hardening of the aminoplast is carried out in the presence of impregnation liquid on the textile material, dried if desired, and the textile material impregnated in a second stage in an aqueous bath which contains a tetrakis-(hydroxymethyl) -phosp'h0nium halide or tris-(hydroxymethyl)-phosphine oxide, dried and after-treated with gaseous and/or aqueous ammonia.

The superiority of the process according to the present invention with regard to wash-fast flame-proofing, unaltered hand of the material and excellent tensile strength and tear strength is shown in comparison to the previous processes in the following Tables I and II.

TABLE I B.P. 761,985, B.P. 882, 993, B1. 882, 993, 13.1 884, 785, B.P. 884.785, 13.1. 906, 314, Example 1 oi the Example 22 Example 2 Example 4 Example 1 Example 9 Example 1 application THPC amount (g./l) 250 150 330 230 260 410 300. Squeeze-off eiIect per- 80 85 80 85 76 78....

cen Calculated P-content 2.8 1.6 3.4 2.5 2.5 4.6...

on the fabric (percent). Wcightincrcase (percent). 15 1 10 24 Hand of fabric Very stifi Unaltered Unaltercd V Flamle resistance as suc Burning time (see)- 0.. Glow time (sec.). 0.. 0........-..

Char length (cm.).. 7. do 8 Burning time (see)- ..do........... 0 ..do ..do 0 0. Glow time (sec.)--.. 0.. .do. 0. ..do..- 0. Char length ..do 4 ..do ..do 5 5.

Burning time (sec.). 0 ..do...... 0. Glow time (sec.)- 0..-. .do..- 0... ..do.. 0. Length (cm.)-- 1O ..do 8 ..do ..d 10.

Process Mixture of Mixture of THPC-urea (1) Aminoplast (1) Ami THP rea (1) Amlnoplast THPC-i-Ami- THPC+Amipreconden- (urea) ther- (melamine) condensate wet fixing noplast thernoplast with sate with mofixing. dry fixing. with NHa-i- (2) THPC as mofixing. NH;OH fix- NHiOH fix- (2) THPC+ (2) THPC-aml- NHiOH fixsuch with tag. ing. nminoplast noplast thering. N HiOH fixing.

thermofixing. mofixing.

Assessment Very good Notieme re- Very good No flame re- Very good Very good flame flame resistslstance, no flame proofing, Initial fiamesistance. flame resistresistance, once, but still fixing. good hand, proofness, no once but still good hand. hand. unstable permanence. hand.

precondensate.

Standard of the Schweizerischer Normeuverband". B.P.=British Patent.

The mechanical testing of the treated fabric gave the The amount of the aminoplast to be applied to the fibres following results: amounts to 2 to 10, preferably 4 to 6%, based upon the Material.-(a) Cotton fabric; (b) Cellulose fabric. weight of the fabric. The concentration of THPC amounts Tests-(I) Tensile strength in accordance with SNV to 150 to 400, preferably 200 to 350 g. per liter. For neu- Standard of the Schwcizerischer Normcnverband) tralisation of the THPC to 70, preferably to g. 98461; (11) Tear strength in accordance with Elmendorf. 40 triethanolamine per liter is added to the bath. After impregnation in the THPC bath the fabric is dried, pref- TABLE erably at the temperatures of 60 to C. The fixing of ifgfi lggf gig Eggs the THPC is carried out for instance by padding in a bath containing 50 to 500, preferably 100 to 300 g. 25%

Warp Warp ammonia per litre. The application of gaseous ammonia 1) Cotton fabric untreated..... 38.6 36.2 1.82 1. 59 proved to be especially favorable in this case. The add-on gig i318 123 31% Withihe aminoplast bath and the THPC bath varies ac- 4) 12.1 88299313: 2..-. 36.0 31.0 1.80 1.54 COldll'lg to the type of fabric. It amounts as a rule to 50 g? i 7,12 ,22 E8 to 150%, for cotton 70 to and for cellulose to 1 B.P.884,785Ex.9---. 30.4 22.3 0 9o 0. 77 120%. After treatment with ammonia the fabric is ad- Eg; g2 tg gig 53:3 28 {3 r vantageously left in the air for 1 to 15 minutes and then 00 treated in a boiling bath which contams sodium carbonate BPFBmEh Patent if desired; also a wetting agent and hydrogen peroxide.

The testing of the flame resistance in accordance with A l d ti d, i t t t th usual h d Table I is carried out by the vertical method of DIN ing f th i l t, hi h i ll d dry h d i o 6 tSChe Industrie Norm) 53906 as Such and y thermo-fixing, the hardening used in the present process, 5 XSNV (=SChWB1ZeFl5CheT The 55 Which occurs in the presence of water, is called wet fixing.

arrangement of the test is as follows: The wet fixing is carried out in such a way that the An ordinary Bunsen burner is used, the l ngth f the fabric, after impregnation in a bath which contains the luminous flame of which is adjusted to 4 cm. water soluble aminoplast as well as a suitable reaction The fabric 7 x 15 cm., tak n in he Wa p an Weft accelerator, is treated, without preliminary drying, at nordifection, is hung in the flame 50 that it p 2 into 60 mal or raised temperature. It is advantageous to carry out After a Certain test time, Whhih depfihded Oh the Weight the fixing at raised temperature and as principal source of thfi fabric, the flame is removed- The flaming time of heat, direct steam, if desired under pressure, is used. (sec.) and the glow time (560.) as Well as the C ar The fixing of the aminoplast fabric can be completely length are measured. achieved without previous drying of the impregnatcd Test time: fabric or with partial drying before or during the fixing Weight of fabric up 4 pr p e a h drying p d unlformly Weight of fabric from 1O0 200 gI/m; 6 without d1sturb1ng m1grat1o n of the hardening products. Weight of fabric from 200-300 g./rn. 8 The simplest process consists in storing for a lengthy Weight of fabric from 300 500 gjmg 10 P t me the fabr c which has been impregnated with a solu- Weight of fabric from 500750 -g./m. 12 i0 tron or emuls on after squeezing out or centrrf ug ng, 1 .e., Weight of fabric from 750 100O 14 after mechanical removal of the excess bath liquid without drying steps and with avoidance of premature drying In assessing the flame resistan on aft r-fla time 05 out. The time during which the material should be stored 1-2 seconds represents a very good degree of protection. varies between a few minutes and several days. It is dependent on the one hand on the aminoplasts and reaction The fabric must not after-glow.

accelerators employed and on the other hand on the storage temperature. The storage can be carried out at normal or raised temperature, e.g., at 80 C. It has proved advantageous to store the impregnated fibre in a closed vessel, since by this means premature drying out is avoided. After fixing of the resin the fabric is dried. As stated above a partial drying, in accordance with the process of the invention, can also be carried out before or during the fixing of the resin. In this case care should be taken that no excessive drying of individual parts of the treated textile material occurs and no migration of the unfixed resin during the drying, as otherwise the success of the treatment can be unfavorably affected. Uniform drying can, for example, be achieved by storing the impregnated fabric in a drying chamber through which a stream of air, with a controlled relative humidity, is passed. The fabric can then only give up so much moisture until it reaches the degree of humidity of the air passing over it.

How far this drying can go, cannot in general be stated because various factors such as the storage and activity of the hardening catalysts must be taken into account.

In accordance with a particularly advantageous method of carrying out the invention the wet fixing can be brought about simply and quickly if instead of hot air containing more or less water vapor, steam is used as the source of heat. By the use of saturated water vapor no danger of local drying-out can arise. By working at raised temperatures, e.g., at 110 to 120 C. under pressure, the fixing time can be considerably reduced so that the whole process, including time for heating up, can be concluded in 1 to 2 hours or even considerably less.

Care must be taken that, in heating up the wet fabric, water formed from the vapor is removed without it causing the impregnating solution to flow. This can best be achieved by through removal of the excess impregnating solution by pressing centrifuging or sucking off.

The present process can be employed with all cellulosecontaining fabrics made from fibers such as cotton, regenerated cellulose, jute, manila hemp, sisal and ramie. It is especially useful for the treatment of cotton fabrics for clothing materials such as well as for tents or awning materials. In general the process of the invention is advantageous in cases where cellulose-containing materials are exposed to the danger of fire and where, besides good flamer resistance, optimum mechanical strength after repeated washing is required. A particular advantage of the process of the invention is that the textile material also acquires good resistance to rotting.

By the term water soluble, hardenable aminoplasts which can be used for the present process there are to be understood primarily hardenable aminotriazine resins that are soluble in water or are of limited solubility in water and which may be etherified; they are obtained by known methods by condensation of formaldehyde with melamine, acetoguanamine, benzoguanamine or formo guanamine. Mixtures of such condensation products are also suitable. Particularly good results are obtained with water-soluble condensation products of 2 to 3 mols of formaldehyde with 1 mol of melamine.

By condensation products of limited water-solubility are to be understood as usually those colloidal intermediate products which are first produced on further condensation beyond the crystalline methylol stage. They are formic acid, are used; alternatively, salts of strong acids with weak bases e.g. ammonium salts of strong inorganic or organic acids, such as ammonium chloride, ammonium sulfate, ammonium nitrate, ammonium oxalate and ammonium lactate, can be employed. When using solutions of aminoplasts to which acids have been added care must be taken that the solutions are freshly prepared as owing to certain changes to the solutions on standing their suitability for the purposes of the present invention are adversely affected.

It is advantageous to use as catalyst an oxidising agent, dispersible in water, which in aqueous phase possesses neither strong alkali-binding properties nor strong acidbinding properties and which, after application of the impregnating liquid to the fabric, has an accelerating effect on the hardening of the aminoplast owing to the formation of oxidation products.

As an oxidizing agent possessing sufiicient oxidizing power to oxidize formaldehyde to formic acid at elevated temperature or during long storage of the treated fabric, hydrogen peroxide is suitable as are addition products of hydrogen peroxide to certain inorganic or organic compound, such as for example perborate NaBO .H O or the addition compound of hydrogen peroxide and urea. Another suitable oxidizing agent is chlorine dioxide or its stable addition products especially the addition product of C10 to pyridine.

The salts of peroxymonosulfuric acid, H 50 and the peroxydisulfuric acid, H S O e.g. its alkali salts, especially H S O are also suitable for use as oxidizing agents.

The impregnation can be carried out by the usual processes and by mean of the usual equipment. Flame-proofing can also be combined with hydrophobation, e.g. with hydrophobing agents known per se.

EXAMPLE 1 A cotton fabric is padded in a bath which contains:

Water soluble condensation product of 1 mol melamine and 2 to 3 mols of formaldehyde g./l 75 H 0 (35%) ml./l 10 The weight increases amounts to 70%. The fabric is rolled up in polyethylene sheet, wet-fixed 24 hours at 40 C. and then dried at 60 to 70 C.

The padding is carried out in a bath containing:

G./l. THPC 300 Triethanolamine 60 (liquid uptake 70%) and the fabric then dried in a box at 60 to 70 C. It is then padded again in a bath containing:

Ml./l. NH OH (25%) 250 The treatment lasts 5 to 10 minutes at 80 to C. and the fabric is then rinsed and dried.

Percent Calculated phosporous content on the fibre 2.7 Weight increase l5 EXAMPLE 2 A cotton fabric is padded in a bath which contains:

Water-soluble condensation product of 1 mol melamine and 2 to 3 mols of formaldehyde g./l H 0 (35%) 'ml./l 10 7 The liquid uptake amounts to 75%. The fabric is rolled up in a polyethylene sheet, stored for days at to C. and then dried at to C.

The fabric so finished is padded in a bath containing: G./l. THPC 300 Triethanolamine 60 and then dried at 60 to 70 C.

(III) It is then fixed in a dry jigger equipped with a hood by gaseous ammonia during 4 passages.

To eliminate the THPC-odor, the subsequent washing is carried out in a bath containing:

Anhydrous sodium carbonate g./1 2 H 0 (35%) ml./l 10 The treatment lasts 10 minutes at boiling temperature and the fabric is then rinsed and dried.

EXAMPLE 3 By an additional treatment with a hydrophobing agent, the cotton-fabric is given a hydrophobic dressing in addition to the mold-resisting, rot-proofing, and flame-proofing finishes.

(I, II)

The cotton-fabric treated according to Example 2, (I) is padded at 60 to 80 C. in a bath containing:

300 g./l. THPC (80%) neutralized with 30 ml./l. sodium hydroxide (40%) to a pH of about 6, g./l. of an emulsion containing- 22 /2 block-parafiin with a melting point of 60 C. 22 /2% of a condensation product obtained from 2 mols of stearic acid, 1 mol of hexamethylolmelaminepentamethyl-ether 3% of emulsifier obtained by reacting 1 mole of a high molecular alkylamine with 30 mols of ethylene oxide and quaternized with dimethylsulfate 1% of polyvinyl alcohol /2% of triethanolamine 50/2% of water 20 g./l. of a catalyst consisting of- 24% of aluminium-triglycolate 8% of glycolic acid 68% of water Fixation by gaseous ammonium during 4 passages follows in a dry jigger equipped with a hood.

The fabric is kept at C. for 5 minutes to fix the hydrophobic finish.

In the same manner as in Example 2(IV) the fabric is washed, rinsed and dried.

Test-results Flame-resistance of the fabrics treated according to Examples 1 to 3:

Untreated Totally burnt. With flame-proofing finish Very good. With flame-proofing finish and washed 5 times SNV4 Very good.

Water-repellency of the fabric treated according to Example 3: The fabric is sprinkled with water and shows the following water'eontent in percent:

Untreated With flame-proofing finish 4 With flame-proofing finish and washed 5 times SNV-4 9.5

What is claimed is:

1. Process for the fiame-proofing of cellulose-containing textile material, which comprises in a first stage impregnating the material with a water-soluble hardenable aminoplast and hardening the aminoplast in the presence of the impregnating liquid present on the textile material, and in a second stage impregnating the material in an aqueous bath containing tetrakis-(hydroxymethyl)-phosphonium chloride, drying it and after-treating it with ammonia.

2. Process for the flame-proofing of cellulose-containing textile material, which comprises in a first stage impregnating the material with a water soluble, hardenable aminoplast and hardening the aminoplast in the presence of the impregnating liquid present on the textile material, and in a second stage impregnating the material in an aqueous bath containing tetrakis-(hydroxymethyl)-phosphonium chloride, drying it and after-treating it with gaseous ammonia.

3. Process for the flame-proofing of cellulose-contain ing material, which comprises in a first stage impregnating the material with a water soluble, condensation product of melamine and formaldehyde and hardening the melamine-formaldehyde condensation product in the presence of the impregnating liquid present on the textile material, and in a second stage impregnating the material in an aqueous bath containing tetrakis-(hydroxymethyl)-phosphonium chloride, drying it and after-treating it with gaseous ammonia.

4. Process for the flame-proofing of cellulose-containing itextile material, which comprises in a first stage impregnating the material with a water soluble, condensation product of 1 mol of melamine and 3 mols of formaldehyde and hardening the melamine-formaldehyde condensation product in the presence of the impregnating, liquid present on the textile material, and in a second stage impregnating the material in an aqueous bath containing tetrakis-(hydroxymethyl)-phosph0nium chloride, drying it and after-treating it with gaseous ammonia.

5. Process for the flame-proofing of cellulose-containing textile material, which comprises in a first stage impregnating the material with a water soluble, condensation product of 1 mol of melamine and 3 mols of formaldehyde and hardening the melamine-formaldehyde condensation product in the presence of the impregnating liquid present on the textile material, and drying the material and in a second stage impregnating the material in an aqueous bath containing tetrakis-(hydroxymethyl)- phosphonium chloride, drying it and after-treating it with gaseous ammonia.

6. Process for the flame-proofing of cellulose-containing textile material, which comprises in a first stage impregnating the material with a water soluble condensation product of 1 mol of melamine and 3 mols of formaldehyde and hardening the melamine-formaldehyde condensation product in the presence of the impregnating liquid present on the textile material, and hydrogen peroxide and drying the material, and in a second stage impregnating the material in an aqueous bath containing tetrakis-(hydroxymethyl)-phosphonium chloride, drying it and after-treating it with gaseous ammonia.

7. Process for the flame-proofing of cellulose-containing textile material, which comprises in a first stage impregnating the material with a water soluble condensation product of 1 mol of melamine and 3 mols of formaldehyde, hardening the melamineformaldehyde condensation product in the presence of the impregnating liquid present on the textile material and hydrogen peroxide 9 1O storing the material in the moist state and drying it, 2,772,188 11/1956 Reeves et a1 117-136 and in a second stage impregnating the material in an 2,809,941 10/1957 Reeves et a1. aqueous bath containing tetrakis-(hydroxymethyl)-ph0s- 3,309,165 3/1967 Rogers et a1 117*1394 X phonium chloride, drying it and after-treating it with gas- 3,323,939 6/1967 Van Loo 117139.4 X eous ammonia. 5

References Cited WILLIAM D. MARTIN, Primary Examiner. UNITED STATES PATENTS H. I. GWINNELL, Assistant Examiner.

2,416,447 2/1947 Laughlin et a1 2528.1 X 2,464,342 3/1949 Pollack et a1.

2,763,574 9/1956 Ruperti 117138.5 10 117439143