Textile finishing

Abstract

 A method finishing keratinous textile articles, for example wool fabrics, which comprises treating the articles with an anti-felt polymer for example isocyanate functional or bunte salt functional polymers, and a polymer of chlorinated ethylenically unsaturated monomer, for example polyvinyl chloride, polyvinylidene chloride, polypropylene, and dichlorobutadiene. Thereafter, the articles are treated with an anionic titanium or zirconium complex at low pH. Textiles so treated exhibit both shrink-resistant and flame-retardant properties.

Description

[0001] This invention relates to a method of finishing keratinous fibres to render textile articles made from such fibres resistant to area felting shrinkage and flame-retardant.

[0002] Keratinous fibres, e.g. wool, are naturally flame retardant, but increasing stringency of regulations in various countries has meant that certain constructions of wool fabrics, or fabrics for certain end uses, e.g. in aeroplanes, and for clothing to provide protection against heat and flames, require an additional flame retardancy treatment. The titanium and zirconium flame retardancy treatments described in our U.K. Patent Nos. 1,372,694 and 1,379,752 have proved eminently suitable for improving the flame retardancy of wool textiles to meet the standards imposed by various legislative bodies.

[0003] The above treatments are fast to machine washing but, as is well-known, wool textiles tend, according to construction, to felt when washed in a machine and hence shrink. Many methods for rendering wool textiles shrink resistant are available but are in general not compatible with the above treatments because of-curing difficulties at low pH values, or the shrink-resist polymer applied adds to the fuel contribution, i.e. increases the combustibility, of the textile, thereby at least partly negating the flame retardancy treatment. Certain shrink-resist processes involving chlorination are not incompatible with the above treatments, nor do they add significantly to the fuel value of the textilebut are generally not desirable becuase chlorination lowers the water repellency and causes difficulties with dyestuffs. There is also the disadvantage of an extra processing step involving noxious chemicals.

[0004] According to the present invention there is provided a method finishing keratinous textile articles which comprises treating the articles with an anti-felt polymer and a polymer of a chlorinated ethylenically unsaturated monomer, and thereafter treating the articles with an anionic titanium or zirconium complex at low pH.

[0005] The process is generally applicable to water-soluble curable shrink-resist polymers and prepolymers and especially those having ionic charges. Isocyanate functional polymers, and especially blocked isocyanate polymers, are preferred particularly water-soluble blocked isocyanates such as polycarbomyl sulphonates. Examples of suitable polymers include polycarbamoyl sulphonates, bunte salt polymers, the amphoteric polymers of our British Patent NO. 1,547,958, and anionic acrylate emulsions. Cationic polymers such as a polyamideephichlorhydrin polymer, or azetidinium polymers, may also be used provided they are compatible with the chlorinated polymer emulsion used, if a cationic emulsion is employed. When the preferred chlorinated polymer emulsions are used, which are anionic, it is preferred to use anionic anti-felt polymers. Especially preferred are the polycarbomyl sulphonates described in U.K. Patent No. 1,419,306. These may conveniently be prepared from polymeric di- or poly-isocyanates by treatment with sodium bisulphite.

[0006] Preferred polycarbomyl sulphonates have polyoxyalkylene, e.g. polypropylene oxide, backbones and three carbomoyl sulphonate groups. Particularly preferred compounds have the following structure:

wherein n is about 13. Such a compound is available commercially under the name "Synthaprett BAP" (Bayer).

[0007] Preferred curable polymeric materials have a polymeric chain backbone and at least two thiosulphate groups per molecule. The chain may advantageously be a polyoxyalkylene, e.g. polyoxypropylene, chain. Particularly preferred materials of this type have the following structural formula:

where n is about 13.

[0008] Prepolymers of this type are disclosed in our British Patent No. 1,423,342. A suitable compound is available commercially under the name "Lenkrolan SHR3". It has been found that this type of polymer gives a very good handle to the treated fabric, especially when used with the "Neoprene" polymer mentioned hereinafter.

[0009] The polymer of a chlorinated ethylenically unsaturated monomer combines with the anti-felt polymer to give a shrink-resist effect, and thus allows less polymer to be used than would be necessary if it were used alone. Since the chlorinated polymers in general do not add to the fuel value of the textile and may even impart a degree of flame retardance, a net lowering of the fuel ccntribution of the shrink-resist treatment can be obtained. The surprising properties of these polymers lie in their capacity both to enhance the shrink-resist qualities of other polymers, particularly polycarbomyl sulphonates and bunte salts, and enhance the flame retardant properties of the titanium and zirconium complexes.

[0010] The chlorinated polymers which may be used include in general, polyvinyl chloride, polyvinylidene chloride, polychloroprene, and dichlorobutadiene.
In general the higher the chlorine content of the polymer the better its flame retardancy characteristics, but this criterion is affected by other factors. Most of these polymers are too hard alone and therefore are available as copolymars with such monomers as acrylonitrile or methacrylic acid. The latter add to the fuel valueoΓ the copolymer and in certain cases may render the polymer unsuitable. In general most commercially available polyvinylchloride compositions are unsuitable for this reason. We have found that for augmenting the shrink-resist effect (thereby allowing the use of less anti-felt polymer) while keeping the fuel contribution as low as possible, the preferred chlorinated polymers are Polidene 33-041 (a polyvinylidene chloride copolymer - Scott Bader Co. Ltd.) and Neoprene 400 (a copolymer of polychloroprene and 2,3-dichloro-1,3-butadiene - Du Pont), especially the latter.

[0011] The treatment with titanium or zirconium may be carried as described in our above U.K. Patents. In brief the metals are applied, preferably by exhaustion as anionic complexes with flouride, citrato, or tartrato ions at a PH in the range 1 to 4. The titanium treatment is more effective, weight for weight, than the zirconium treatment but leads to a slight yellow colouration and should generally be used only with dark shades or where colouration is immaterial.

[0012] The quantities of agents may vary within wide limits subject to the desired degree of shrink-resistance, the flame retardancy required, and such factors as the substrate, coreactants, and so on. Thus in general the anti-felt prepolymer may be applied in the range 0.1 to 10% oww, preferably 0.2 to 2%, the lowest amount compatible with adequate shrink-resistance being chosen. The chlorinated polymer may be used in amounts of from 1% to 10% with 1. to.4% being preferred. The titanium or zirconium treatments may be applied in the ranges of 0.5% to 2.5% or 1% to 5% respectively (calculated as oxide) again depending on the substrate and the level of flame retardancy required.

[0013] The keratinous fibres may be for example mohair, alpaca, vicuna, angora, or especially wool, and the textile article may be in the form of loose stock, slivers, slubbings, rovings, yarns, fabrics, made-up garments or carpets, preferably fabrics.

[0014] The shrink-resist treatment may be carried out in any suitable manner e.g. exhaustion, dipping, spraying or padding, preferably the latter, and the flame retardancy treatment is preferably carried out by exhaustion from long liquor.

[0015] The invention will be illustrated further by the following examples. The test methods used were as follows:-

Felting Shrinkage

[0016] This was determined after 1 hour and 3 hours in an International Cubex Washing Machine, using a phosphate buffer at PH7 and 40°C with liquor ratio 15:1, and total load 1 kg made up with polyester makeweights. The results are expressed as percentage area felting shrinkage.

Flame-Resistance Test

[0017] This was evaluated according to Federal Aviation Regulations 25.853b, a vertical flame test with a 12 second ignition time. To meet this standard the after-burning time should not exceed is seconds and the char length should not be more than 8 inches, tested in both the warp and weft directions. Wash fastness of the flame retardancy effect is determined after 10 and 20 washes in a Kenmore Model 21900 washing machine at 40°C, liquor ratio 1:36, load 1.8 kg using 90g "Bold" washing power per 65 litres.

Examples 1 to 10

[0018] Lankrolan SHR3 and Neoprene 400 were padded onto a wool serge fabric. The fabric was dried and then cured at 150°C for 5 minutes. Zirconium flame retardant treatment was applied by immersing the fabric at 1:20 liquor ratio in'a bath containing 10% oww HC1 (37%) 4% oww citric acid and 6% oww K₂TiF₆ for 30 minutes at 60°C, liquor ratio 1:30, by rinsing and drying.

[0019] The area felting shrinkage of the fabric after 3 hours test; and the FAR 25.853B test results are given in Table 1 below for a variety of component concentrationr.

[0020] The Lankrolan SH_R3 treatment is not compatible with the titanium flame-retardant treatments (Examples Nos. 1 - 3). The addition of Neoprene 400 to the Lankrolan S_HR3 not only makes the shrink-resist treatment compatible with the flame retardant treatment but it also allows the lower concentration of Landrolan SHR3 to be used to achieve adequate shrink-resistance (Examples Nos. 4 - 10). In other words the incorporation of Neoprene 400 imparts flame-resistance to Lankrolan SHR3 and it also acts as a shrink-resist agent.

Example 11

[0021] Synthappret BAP(0.4% oww) NaHC0₃(1% oww) and Neoprene 400 (3%) were padded onto a wool serge fabric. The fabric was dried and then cured at 140°C for 5 minutes. Zirconium flame retardant treatment was applied by immersing the fabric at 1:20 liquor ratio in a bath containing 10% oww HCl (37%), 4% oww citric acid and 8% oww K₂ZrF₆ for 30 minutes at 70°C, followed. by rinsing and drying.

[0022] The area felting shrinkage of the fabric was zero after 1 hour and 2% after 3 hours test; and the fabric passed the FAR 25.853b test in both the warp and weft directions. It was also observed that the smooth drying properties of the fabric given this treatment were exceptionally good, and that the spray rating, according to B.S. 3702, was unchanged by the treatment. A similar fabric given a chlorination treatment showed a marked deterioration in spray rating.

Examples 12 to/9

[0023] In these examples the Synthappret and Polidene were applied to various fabrics by a pad-dry-cure route and the "Zirpro" zirconium flame retardant treatment was applied as in Example 11. The results are given in the Table 2 below.

Example 20

[0024] An all-wool gaberdine fabric, 270 g/m², was treated with 1.25% Synthappret BAP, 1.25% Neoprene 400 and 1% NaHCO₃ by the pad-dry-cure technique, curing being achieved by heating to 150°C for 5 minutes. Thereafter, in a separate bath, the fabric was given a _Zirpro treatment with 10% Hcl (37%), 4% citric acid, and 6% K₂ Ti F₆ for 30 minutes at 70°C at a fabric-to-liquor ratio of 1:25.

[0025] The results are given in Table 3 below.

Example 21

[0026] Example 20 was repeated with the inclusion of 3% FC214 (a fluorocarbon supplied by the 3M Company) in the Zirpro treatment.

[0027] As can be seen from Table 3 below, this resulted in a fabric which was shrink-resistant, flame retardant, and oil-and water-repellant, the first three properties being fast to severe washing at 60°C and the last fast to at least 20 washes at 40°C.

[0028] Thus it can be seen that the process of the invention enables a shrink-resistant and flame retardant finish to be applied to wool fabrics by a simple route using commercially available chemicals, without adversely affecting properties such as water-repellency.

Claims

1. A method finishing keratinous textile articles which comprises treating the articles with an anti-felt polymer and a polymer of a chlorinated ethylenically unsaturated monomer, and thereafter treating the articles with an anionic titanium or zirconium complex at low pH.

2. A method according to claim 1 in which the anti-felt polymer is an isocyanate functional polymer or a bunte salt functional polymer.

3. A method according to claim 2 in which the polymer is a polycarbomyl sulphonate

4. A method as claimed in claim 2 in which the polymer has the following structure:

OR

Wherein N is about 13.

5. A method as claimed in any one of claims 1 to 4 in which the chlorinated polymer is polyvinylchloride, polyvinylidene chloride, polychloroprene, or dichlorobutadiene.

6. A method as claimed in claim 5 in which the chlorinated polymer is a copolymer of polychloroprene and 2,3-dichloro-1,3-butadiene.

7. A method according to any one of claims 1 to 6 in which the titanium or zirconium is applied by exhaustion as an anionic complex with flouride, citrato, or tartrato ions at a pH in the range of 1 to 4.

8. A method according to any one of claims 1 to 7 in which the anti-felt polymer is present on the articles in the range 0.2 to 2%, the chlorinated polymer is present on the articles in the range 1 to 4% and the titanium or zirconium is present in the range 0.5 to 2.5% or 1% to 5% respectively (calculated as oxide).

9. A method as claimed in any one of claims 1 to 8 in which the keratinous fibres are wool fibres.

10. A method as claimed in any one of claims 1 to 9 in which the textile article is a fabric.

11. A method as claimed in any one of claims 1 to 10 in which the polymers are applied by exhaustion, dipping, spraying or padding.