NO138701B - PROCEDURES FOR AA IMPROVE THE FLAME RESISTANCE OF NATURAL AND! SYNTHETIC POLYAMIDE FIBERS - Google Patents

Description

The present invention relates to textile finishing and more

in particular improving the flame resistance properties of natural and synthetic polyamide fibres.

Naturally occurring polyamide fibres, for example sheep's wool, exhibit a high degree of natural flame resistance due to their relatively high nitrogen and moisture content, high ignition temperature (570-600°C), low heat of combustion, low flame temperature and a high limiting oxygen index.

The performance characteristics of woolen toys in various test methods that are currently used depend on the particular test method and toy—

construction. A horizontal test method is much less demanding than a 1+5° or a vertical test. Most wool piles will pass a horizontal test, but will not pass a horizontal or vertical test. The influence of the toy construction is also very important, as the denser and heavier the pile is, the lower the flammability. For example, a conventional wool floor covering with tufted fluff passes the American "Tablet test" (DOC FF 1-70.-, DOC FF 2-70), while a floor covering in the same material but with a fluff or longer fluff will fail the same test.

It follows that wool in some cases needs a flame resistance treatment to pass a special flammability specification and test method. Curtains and wall coverings in public buildings, aircraft covers and carpets, covers and curtains in general transport, protective clothing and floor carpets with coarse pile construction and low density are products that may require treatment.

It has previously been proposed to apply titanium compounds to textile fibers as flame retardants. Such compounds are not always suitable when wool fibers are used, because they cause yellowing.

Although the process can be satisfactory for many purposes, it is also not entirely suitable for the production of bleached wool items.

The present invention provides a method for improving the flame resistance properties of natural or synthetic polyamide fibers by applying a zirconium compound, which method is characterized in that the fibers are treated at a pH in the range 0.5 - ^ with an aqueous solution containing an anionic complex of zirconium with an organic chelating agent or fluorolons.

To obtain satisfactory results is usually applied

0.5 - 5% zirconium, calculated as Zr02, on the weight of wool (o.w.w.).

It is preferred that the zirconium is in the form of an anionic complex, and the preferred pH range for applying the zirconium solutions is 0.5 to ht preferably approx. 2. The complex is applied from aqueous solution, and can be pre-formed or can be formed in situ in solution. or on the fibers.

Zirconium compounds which can be used as starting materials include any water-soluble zirconium compound such as zirconium acetate, zirconium oxychloride (zirconyl chloride), zirconium sulfate, and potassium zirconium fluoride. The complexing agents which can be used if the zirconium is not already in the form of a complex include, in addition to fluoride and other halide ions, fluoroborate ions (which act as a source of fluoroions), citric acid, oxalic acid and tartaric acid. When the complexing agent is fluoride ions, it can also be advantageous to add an organic complexing agent, e.g. citrates. The zirconium compound can be in the complexed state before it is applied to the fibers, or alternatively the complex can be formed in situ.

A group of complex <zirconium compounds which can be used with particular advantage are alkali metal or ammonium fluorozirconates. These compounds are applied directly to wool as aqueous solutions, preferably in a concentration range of 2 - 15% o.w.w. and more specifically approx. 5$. The preferred compound is potassium zirconium fluoride.

The zirconium in the treatment solution is preferably stabilized as a water-soluble complex, otherwise polymerization and/or precipitation of zirconium dioxide can occur, either at room temperature or by boiling. When organic complexing agents are used, the zirconium is preferably applied to the fibers at or near boiling. When fluorolons are present, the zirconium can be applied at temperatures in the range 10 - 60°C, especially approx. 50°C. Both polymerization and folding can lead to an ineffective flame retardant treatment. Since aqueous solutions of zirconium compounds precipitate zirconium dioxide in the presence of a base, the solution applied to wool is acidic.

Although the invention does not depend on any particular theory as to its mode of operation, it is believed that the application of zirconium in the form of a complex enables the zirconium to penetrate into the interior of the fibers, especially when wool fibers are used, which is preferred, where it can react with e.g. amino groups inside the fibers and become chemically bound to these. Furthermore, at the acidic pH values used, wool is in a positively charged state, and a more satisfactory depletion of the zirconium is achieved when it is applied in the form of anionic complexions such as ZrClg<2>-, ZrFg<2-> , ZrF, -,3- and (Zr(C2<0>lf)i+<*f>~. In the case of synthetic polyamide fibers such as nylon 6, nylon 66 or nylon 10, the complexed zirconium compound can react either inside the fiber or on the fiber surface.

The zirconium compound can be applied to the fibers by which

any conventional method, including foulard-dry, foulard-batch, shower-roll-dry, and pull-out methods are preferred.

The term "foulard-dry" is used to denote the application of a liquid or paste to the fibers to be treated by foulard treatment followed by drying. The term "shower-roller-dry" means spraying a liquid onto the fibers to be treated, feeding them between two rollers, with subsequent drying. The term "extraction" means treating the fibers in a bath with a dissolution of the active material until it is practically completely absorbed, with subsequent drying of the fibers.

Conventional machines for treating textiles and garments with liquid can be used, including string washing machines, winches, warp dyeing equipment, packing machines, hemp dyeing machines, top dyeing machines, side paddle dyeing machines, washing equipment and dry cleaning machines for batch treatment and including foulard rollers, "lick-rollers", shower units, continuous toy washing units, post-washing machines and solvent washing machines for continuous and semi-continuous treatment.

The invention can be used to treat synthetic polyamide fibres, e.g. nylon, but is particularly valuable when processing natural polyamide fibres. The fibers are preferably of sheep's wool, but they can also be of alpaca, cashmere wool, mohair, vicuña wool, guanaco, camel hair, silk and llama wool or mixtures of these materials with sheep's wool. Toys consisting of a mixture containing a larger proportion of wool and a smaller proportion, generally 20% or less, of synthetic fibers or natural cellulose fibers which do not themselves have a high degree of flame resistance, e.g. polyamide, polyester or cotton fibres? can also be treated. It is also possible to treat mixtures containing less than 80% wool, where the remainder is a flame-resistant synthetic fiber, e.g. aromatic polyamide fibers (NOMEX"), polybenzimidazole fibers, cross-linked phenolic fibers ("Kynol"), polyvinyl chloride fibers, polyvinylidene chloride fibers, modacrylic fibers and flame-resistant treated rayon fibers. The treatment can be carried out on the fibers at any desired step during the textile manufacture, and the fibers can e.g. e.g. be in the form of fur, top carding tape, noils, yarn, threads, woven or knitted toys, "non-woven" toys, polo toys, clothing or sauce skins. Preferably, the material to be treated is washed to a residual methylene chloride extract of no more than 0.8$ to remove spinning additives or natural waxes that may contribute to the flammability of the product.

The fibers can also be treated with other known substances that impart flame-resistant properties. Such substances include

includes antimony compounds, especially antimony trifluoride or antimony potassium tartrate, and aluminum compounds, especially aluminum sulfate (Al2(S0^)2'16H20) or aluminum chloride. A summary of the principle methods for treating the fibers is described below.

(a) The extraction method

The fibers are treated with an aqueous solution of a zirconium compound ice at a pH of 0.5 to 3, and at a liquid ratio of approx.

1 to 20, preferably no more than approx. 1 to 30. The extraction of the zirconium compound is usually complete after a boiling time of

from 30 minutes to 2 hours, generally approx. 1 hour. The zirconium complex is preferably present in a concentration of from 1% to 3% by weight of the fiber weight, calculated as ZrO 2 » When using zirconium oxychloride solutions, stabilization, e.g. with fluoride or citrate, be incomplete, and some finening of zirconium dioxide may occur during longer boiling. Nevertheless, a flame retardant effect can be achieved with this compound. However, it is preferred to use solid zirconium oxychloride, or potassium zirconium fluoride, which is easily stabilized in dilute solution with ammonium bifluoride, is very stable, and is stable against hydrolysis.

The extraction of zirconium from the treatment solution can be followed by measuring the fluorescence of "M0RIN" (3,<l>f,7,2<1><l>f<1->pentahydroxy-flavone) when exposed to ultraviolet radiation. 3 ml of a 5% solution of "MORIN" in ethanol is added to a 10 ml sample of the treatment solution. After the extraction is complete, only a very faint green fluorescence is observed. The amount of zirconium extracted at

the wool during the flame resistance treatment can be calculated as ash content (metal oxide). As wool always contains some inorganic material, the increase in ash content due to pickling should always be calculated as the difference between the ash content of flame-resistance-treated and untreated wool during treatment. This method is

particularly useful when the flame retardancy treatment is carried out simultaneously with staining, in which case the dyes may fluoresce and interfere with the "MORIN" fluorescence sample.

The present method can be carried out simultaneously with dyeing provided that the dye can be extracted on wool at a pH below 5. Such dyes are generally water-soluble and contain anionic dissolving groups. Acid equalization, 1:1 premetallized and certain reactive dyes can be applied at the same time as the zirconium treatment and there is no need for further addition of formic acid or sulfuric acid which is conventional with these dyes as the pH of the dye bath is already sufficiently low. Glauber's salt and sulfuric acid are preferably not added to the solution as they interfere with the extraction of the zirconium complex, but organic non-ionic leveling agents, e.g. those sold under the trademarks "Avolan SC" or "Albegal B" can be used. When acid calendering or 1:2 premetallized dye is used, the dye can first be extracted by boiling, the temperatures of the dye bath are reduced to 70°C, the complex formed zirconium compound ice is then added and the bath is then heated further until the zirconium complex has been extracted on the wool. When dyeing with chrome dyes, the dye operation must be carried out after the zirconium treatment, otherwise complex formation between the titanium in solution and the dye may lead to a dye treatment.

The zirconium treatment is very advantageous in that it does not lead to a yellow discoloration of the wool and does not promote yellowing when exposed to light, and pastel colors do not change particularly during the treatment. When no dye is added, the product has the natural color of the wool, and can, if desired, be bleached by treatment with a hydrogen peroxide bleach or a reducing bleach such as sodium hydrosulphite or bisulphite. Bleaching can, when necessary, be carried out after the zirconium treatment, or before the treatment provided that the temperatures used in the zirconium treatment do not approach boiling.

Reductive bleaching can be carried out by heating the wool with a stabilized hydrosulphite at a concentration of approx. 5 g/l at a temperature of 50 - 70°C for 1 - 2 hours. A milder reducing bleaching can be obtained by boiling with sodium bisulphite (approx. 5 g/D at 50°C

for 1 hour. Bleaching can be carried out using 3 - 7 g/l hydrogen peroxide solution, and it is preferred to include a stabilizer based on silicates, e.g. 3-5 g/l sodium silicate, or to hold

the bath temperature at 50°C for 1 - 2 hours. If the wool has previously been damaged, e.g. of the weather, can h% formaldehyde h0% o.w.w. is added to the zirconium treatment bath to protect the wool during cooking.

(b) The Foulard rate method

The zirconium compound can be applied to the fibers by treatment in a foulard. The fibers can be dyed for treatment. A suitable treatment preparation comprises an aqueous solution of zirconium oxychloride, ammonium bifluoride and formic acid. After treatment, the fibers are wound on

a coil and stored in the presence of moisture for approx. 1 hour, rinse with water and dry. The Foulard batch treatment is particularly useful when treating colored toys in which the dye is not stable to boiling at pH 0.5 - 3.

The treatment according to the invention has a further advantage

that it is compatible with fluorocarbon oil and water-repellent treatments for furniture covers, e.g. for use on aircraft seats. Fluorocarbon resins, e.g. FC-21^, FC-208, FC-218, which are manufactured by the 3M company, can be applied preferably in the presence of an extender, e.g. "Phobotex FTN". The zirconium and fluorocarbon can be applied simultaneously by foulard treatment followed by drying at a temperature of at least 100°C, further heating for a sufficient time and at a sufficient temperature to harden the resin, followed by washing and drying. The zirconium treatment can also be applied by any other of the methods described above, or after the water- and oil-repellent treatment.

(c) The shower-roll-dry method

A suitable preparation for applying to toys, especially floor toys, when showering comprises an aqueous solution of zirconium oxychloride and ammonium bifluoride, and such a preparation is particularly useful for treating finished carpets.

The invention is illustrated by the following examples. (The term "o.w.w." means on the weight of wool).

(d) Flame resistance

The flame resistance of textiles can be measured by the "Vertical Flame Test" (A.A.T.C. Test Method 3^-1969, Fire Resistance of Textile Fabrics) which involves hanging a conditioned (65% relative humidity) strip of the toy to be treated in a flame from a Bunsen burner for 12 seconds and determine the length of the charred part of the toy and the burning time. The flame resistance of carpets can be measured by the "Tablet Test", which involves drying a sample of the carpet at 105°C for 2 hours, lighting a standard time-burning "Methanamine" (hexamethylenetetramine) tablet on the surface of the carpet, and observing the spread of the flame over the surface of the carpet. It is an aim of the present invention to provide textile materials that pass these tests, hereinafter referred to as "Vertical Flame Test" and "Tablet Test".

Example 1

Undyed wool yarn was treated by extraction with the following solution:

The solution was boiled in contact with the yarn for ^5 minutes after which the zirconium was practically completely extracted on the yarn,

as only a weak green fluorescence could be observed with "Morin". The treated yarn was then rinsed, centrifuged and dried. The yarn was used to produce a woven toy which easily passed the "Vertical Flame Test". The treatment was resistant to at least 10 washes (1+5°C, 15 minutes, 1:20 Phillips automatic washing machine) and 10 torrents (25°C, 15 minutes, 1:20 "Perklene", launderometer).

The manufactured toy had a very satisfactory natural color which could be compared very favorably with the color for treatment. The whiteness was further improved by treating the toy with a solution containing: Hydrogen peroxide 0.6$

Sodium silicate 5 g/l

The treatment was carried out for 1 hour at 50°C and a liquid ratio of 1:20, and the treated toy was again rinsed, centrifuged and dried. The product was a bleached wool toy that easily passed the "Vertical Flame Test" and was resistant to washing and dry cleaning like lining.

Example 2

Samples of the zirconium-treated wool yarn from Example 1 were formed into a coarse pile carpet using a tufting machine. The carpet had a pile length of approx. 5.0 cm. It easily passed the "Tablet Test". Other samples of the yarn were bleached for nubbing using the solution and conditions described in Example 1. The nubbed carpet produced from the bleached yarn again easily passed the "Tablet Test".

Example 3

The following preparation was applied to a knitted woolen jersey tby:

The solution was extracted on the toy by boiling for 60 minutes at a liquid ratio of 1:20, after which both the dye and the zirconium were found to be extracted on the wool city. A bright yellow product was obtained which was centrifuged and dried. It easily passed the "Vertical Flame Test".

Example h

The following preparation was applied to a knitted woolen jersey tby:

The solution was extracted on the toy at 50°C for 60 minutes at a liquid ratio of 1:20. The treated toy was then centrifuged and dried. The product was a wool city that passed the "Vertical Flame Test".

Example 5

A wool ball was treated with the following aqueous solution using a foulard.

"Tergitol Speedwet" is a non-ionic wetting agent. The toy was then dried, rinsed with water in a winch at 20°C and a liquid ratio of 1:20, and again dried. The dry toy passed the "Vertical Flame Test".

Example 6

To improve the whiteness and flame resistance of

a zirconium-treated wool yarn, it was bleached with hydrogen peroxide and sodium silicate in a liquid of the following composition:

The wool was bleached for 1 hour at 50°C, a liquid ratio of 1:20,

and the wool was rinsed, centrifuged and dried. A coarse-pile floor carpet with 6.0 cm pile length made from the flame-resistant treated yarn easily passed the "Tablet Test" and the whiteness was 20$ higher than with the untreated yarn.

A knitted jersey wool toy that was flame retardant-treated and bleached passed the "Vertical Flame Test" and the whiteness was further improved compared to the untreated toy.

Example 7

To correct a slight yellowing of wool due to boiling, a reducing bleach ("Lufibrol FW") was added to a heat resistance treatment bath according to Example 1 at a concentration of 1% o.w.w. and the extraction method was used exactly as in Example 1. A toy made from the flame retardant-treated yarn passed the "Vertical Flame Test" and the original whiteness of the yarn was restored after the flame retardant treatment without any bleaching aftertreatment.

Example 8

A long-pile wool carpet was sprayed with the following solution:

Poland's admission was 60$. After spraying, the carpet was passed between two rollers to ensure proper treatment and penetration of the flame-resistant solution into the wool fibres, and finally the carpet was dried at 110°C. The treated carpet easily passed the "Tablet Test".

Example 9

An undyed New Zealand carpet wool in hasper was subjected to flame retardancy treatment as follows: 5% potassium fluorozirconate o.w.w. and 5% o.w.w. 37$-ig salt- . acid was dissolved in water and added to the treatment bath at 20°C. The bath was heated to 50°C at a rate of ^-°C/min in the presence of the wool and held at this temperature for 1+5 minutes at a liquid ratio of 1:25 and 85% of the zirconium was then extracted onto the wool. After the wool had been rinsed, centrifuged and dyed, a long-pile floor carpet was produced (pile height 5 cm, cut pile weighing 950 g/m). The carpet easily passed the "Tablet Test" and the treatment withstood at least 10 washes (15 minutes, 60°C, 1:20, 2 g/l soap). The natural white color of the yarn was not damaged by the zirconium flame retardant treatment.

Example 10

A woven wool curtain fabric was treated on foulard rolls with the following aqueous solution:

"Tergitol Speedwet" is a commercially available surfactant. The wet absorption of the treated toy was 75-80$. The toy was then stored for 1 hour on a rotating roll with a polyethylene foil cover to allow the zirconium to penetrate the fibers, and was then cleaned in a winch with water at 18°C for 10 minutes with a liquid:product ratio of 1: 20. The dry toy passed the "Vertical Flame Test"

(U.S. Federal Specification C.C.C.T 19 lb. 1951 method 5902) in its original condition and after 10 washings.

Example 11

This example describes the flame retardancy treatment of sheepskin which was treated/"side-paddle" machine at 50°C for h5 minutes at a liquid ratio of 1:20 with the following chemicals:

After treatment, the sheepskins were rinsed well with water and dried at 50° to preserve the leather's naturally soft grip. The wool on the treated sheepskin did not change its natural white color and soft grip and easily passed the "American Tablet Test" Federal Specification DOC FF 2-70, while the same untreated sheepskin did not pass the same test.

Example 12

This example describes the continuous flame retardant treatment of loose wool in the last container of a raw wool washing set. The concentration of the chemicals in the last container was as follows:

60 g/l zirconium oxychloride

30 g/l ammonium bifluoride

20 g/l of hydrofluoric acid

The temperature of the bath was <1>+5°C and the loose wool passed continuously through the container for h minutes, was squeezed to 35% moisture content, dried and passed through a mechanical shaker to remove residual chemicals on the surface of the fibers. The grip and color of the treated wool was unchanged and when it was made into a long-pile floor rug, it easily passed the "Tablet Test".

Example 13

This example describes the simultaneous flame retardant treatment and dyeing of a wool/nylon 80/20 yarn that was processed in a hemp dyeing machine with the following recipe:

The material was kept on boiling for *+5 minutes at a liquid:product ratio of 20:1. The dye, which is of the acid leveling type, was extracted onto the wool and a loose long pile carpet made from the treated yarn was tested according to Federal Specification DOC FF 1-70 ("Tablet Test"). Although the flame spread was more noticeable than with an all-wool carpet of similar construction, the carpet made from the wool/nylon blend passed the specification.

Example 1*+

This example describes the flame retardancy treatment by the low temperature method for a woolen carpet containing 15% cotton in the warp direction. The carpet was first dyed in a winch to a light blue color with fiber-reactive dyes in a known manner and was then heat-resistant treated as follows:

The materials were held for *+5 minutes at a temperature of 50°C at a liquid:product ratio of 20:1. The original color was not changed by the treatment, and the carpet easily passed the "Vertical Flame Test".

Example 15

A blended toy consisting of 60$ wool and 0% "Nomex" (a flame resistant synthetic aromatic polyamide fiber) was treated as described in Example l^f, and the treated toy had better textile properties and better flame resistance than a pure "Nomex" toy of corresponding weight and construction.

Example 16

This example describes the flame retardant treatment of a toy containing 50% wool and 50% modacrylic fiber ("Teklan"), which is a flame retardant synthetic fiber. The treatment was carried out as in Example l*f. The treated toy had better grip, lower rok development and better flame resistance than pure "Teklan" toy.

Example 17

This example describes the flame retardancy treatment of a mixture containing court log 60 of a permanent flame retardant rayon ('PFR Rayon'). The flame retardancy treatment was carried out as in Example 1k. The flame retardancy treated toy had better textile properties (tensile-

heat, elongation at break, abrasion resistance, etc.) grip and flame resistance than pure "PFR Rayon" toy.

Claims (7)

1. Method for improving flame resistance the properties of natural or synthetic polyamide fibers when applying a zirconium binding agent, characterized in that the fibers are treated at a pH in the range of 0.5 - h with an aqueous solution containing an anionic complex of zirconium with an organic chelating agent or fluorolons. 2. Method according to claim 1, characterized in that an amount of zirconium complex of 0.5 - 5% calculated as Zr02«3 is applied. Method according to claim 1 or 2, characterized in that the anionic organic zirconium complex is applied to wool at the boiling point. U-. Method according to claim 1 or 2, characterized in that the anionic fluorine complex of zirconium is applied at a temperature of 10 - 60°C. 5. Method according to claim 1 - ^, characterized in that a dye is applied to the fibers simultaneously with or from the same bath as the zirconium compound. 6. Method according to claim 5" characterized in that a water-soluble dye which is able to be extracted on wool at a pH below 5 is applied to the wool at the same time as the zirconium treatment. 7. Method according to claim 5" characterized in that an aqueous solution of an acid bleaching or 1:2 pre-metallized dye is applied to the fibers during extraction by boiling, that the dye bath temperature reduced to approx. 70°C, the zirconium compound and complexing agent or agents are added, and the dye bath temperature is raised to boiling to effect extraction of the zirconium complex.