The skin-damaging effect of UV radiation is well known. Protection from strong sunlight is usually sought by applying a sun cream, a composition that contains a UV absorber, directly to the skin. In particularly sunny regions, for example in Australia or America, however, the rate of skin damage due to UV radiation has recently been increasing dramatically.

Accordingly, more attention is paid in these countries to protecting the skin from solar irradiation.

It has therefore been proposed that the skin should be protected not just directly, but also to reduce the UV transmissibility of the clothing and also of other sun protection articles, such as awnings or parasols. Especially cellulosic fibre materials are at least partially transparent to UV radiation, so that the mere wearing of clothing does not offer adequate protection to the skin from damage due to UV radiation. A remedy is possible here by incorporating UV absorbers into the fibre material.

However, hitherto the results achieved in respect of the protection from UV radiation in the area of cellulosic fibre materials, in particular textile materials have not been satisfactory and there therefore continues to be a need for improving the sun protection factor of these materials. Despite the fact that this is a general problem, one specific aspect has been found especially problematic. In the case of cellulosic fibre materials treated with fluorescent whitening agents (FWA's), incorporation of UV absorbers has been found to result in loss of the whitening effect, thus leading to an undesirable yellowing of the fibres.

Surprisingly, it has now been found that a particular class of UV absorber not only provides excellent sun protection factors for cellulosic fibre materials in general, but also, in combination with materials treated with FWA's, results in little or no observable reduction of the degrees of whiteness of the so-treated materials. Correspondingly, the present invention provides a process for improving the sun protection factor (SPF) of cellulosic fibre materials and blends thereof, which comprises contacting said materials with at least one compound of the formula : whereby R, represents hydrogen or C,-C4alkyl ; R2 represents hydrogen, C,-C4alkyl, C,-C4alkoxy, halogen or SO3M, M being hydrogen or an alkali or alkaline earth metal ; X, is chlorine, fluorine, NR3R4, OR3 or SR3, wherein R3 represents hydrogen, C,-C4alkyl or C,-C4alkoxy, which are unsubstituted or substituted by one or more S03M, OS03M, COOM or OH groups, C2-C4hydroxyalkoxy, C,- C4alkoxy-C,-C4alkoxy or phenyl, which is unsubstituted or substituted by one or more SO3M, COOM, OH, halogen or C,-C4alkyl groups and R4 represents hydrogen, C,-C4alkyl, C2-C4hydroxyalkoxy, C,-C4alkoxoxy-C,-C4alkoxy or phenyl, or R3 and R4, together with the nitrogen atom, form a pyrrolidine, piperidine or morpholine ring; X2 is chlorine, when X, is chlorine, or X2 is fluorine, when X, is, NR3R4, OR3 or SR3 and Z is a fibre-reactive group.

A fibre-reactive group is to be understood as meaning such a group which is capable of reacting with the hydroxyl groups of the cellulosic fibre or with the amino groups of polyamide fibre materials to form covalent chemical bonds. Many such reactive groups are known, in particular from the chemistry of the so-called"reactive dyes". However, within the scope of the present invention, preferred fibre-reactive groups Z are those in which Z is a radical of the formula : -SO2-Y (2), -S02NH-Y (3), -NHCO (CH2) 3S02-Y (4), -CONH (CH2) 2S02-Y (5) or -NHCO-Y (6), Y representing vinyl, ß-sulphatoethyl,. P-thiosulphatoethyl, ß-phosphatoethyl, ß-acyloxyethyl or ß-haloethyl, especially those in which Z is a radical of formula (2) and Y represents- CH2CH20SO3M, M being as defined previously.

Within the scope of compounds of formula (1), the groups R 1 and R2 preferably represent hydrogen and a further preferred embodiment is represented by formula (1), wherein X, and X2 both represent chlorine or X, represents NR3R4 and X2 represents fluorine, R3 and R4 being as previously defined.

Most preferably, the reactive UV absorber utilized in the process of the invention is of the formula Within the definition of the substituents in compound (1), C,-C4alkyl may be methyl, ethyl, n- or isopropyl or n-, sec.-or t-butyl, C,-C4alkoxy may be methoxy, ethoxy, n-or isopropoxy or n-, sec.-or t-butoxy, C2-C4-hydroxyalkyl may be hydroxyethyl, hydroxypropyl or hydroxybutyl, whilst halogen may be fluorine, chlorine, bromine or iodine, preferably chlorine and M is Na, K, Ca or Mg, preferably Na.

The quantities of compound (1) to be applied to the cellulosic material according to the process of the invention may vary over a wide range. However, when used in amounts of between 0.5 and 10% by weight, based on the weight of the fibre material, useful effects may be obtained. Preferably, however, the amount of the compound of formula (1) used is from 3 to 10% and especially from 4 to 7% by weight, based on the weight of the fibre material. Cellulosic fibre materials are to be understood as meaning, for example, the natural cellulose fibre, such as cotton, linen and hemp, and also cellulose pulp and regenerated cellulose.

The process of the invention is also suitable for treating hydroxyl-containing fibres present in blend fabrics, for example, blends of cotton with polyester fibres or polyamide fibres.

The fibre materials used have a density of between 30 and 200g/m2, preferably between 100 and 150g/m2, the porosity of the material lying in the range of 0.1 to 3%, preferably 0.1 to 1.5%.

Preferably, the cellulosic fibre material used is cotton or a cotton blend.

The fibres mentioned may be present in various forms, for example, as staple or yarns or as wovens or knits.

A further aspect of the invention, as previously mentioned, is to provide excellent sun protection factors for cellulosic fibre materials in combination with fluorescent whitening agents (FWA's), whereby little or no observable reduction of the degrees of whiteness of the so-treated materials results.

For this purpose, application of the UV absorber (1) may be performed before, during or after treatment of the material with the FWA.

Any FWA suitable for whitening cellulosic fibre materials may be applied for this purpose.

However, suitable FWA's are, in general, those derived from triazinylaminostilbenes, naphtho-or v-triazolylamino stilbenes, distyryl biphenyls, diphenyl pyrazolines, benzoxazoles, coumarin or carbostyryl compounds, whereby these derivatives preferably contain sulphonic acid groups.

Specific examples of suitable FWA's are: whereby the invention is not to be regarded as being restricted solely to the use of these FWA's.

The application of the UV absorbers and also, when desired, the FWA's, can take place by an exhaust or continuous process.

In the exhaust process the liquor ratio can be chosen within a wide range, for example, from 3: 1 to 200: 1, preferably from 10: 1 to 40: 1. It is advantageous to operate at a temperature of 20 to 120°C, preferably 40 to 110°C, advantageously in the presence of acid-binding agents, for example, sodium hydroxide, sodium carbonate, sodium bicarbonate, sodium formate, potassium carbonate, sodium silicate, sodium trichloroacetate or sodium triphosphate, in the presence or absence of neutral salts, for example, sodium sulphate or sodium chloride.

In the continuous process, the liquor add-on is advantageously 40-700, preferably 40-500, % by weight. The fibre material is then subjected to a heat treatment process to fix the applied UV absorbers. This fixing can also be effected by the cold batching method.

The heat treatment preferably takes the form of a steaming process in a steamer with ordinary or superheated steam at a temperature of 98 to 105°C for, for example, l-7, preferably 1-5 minutes. The fixing of the UV absorber by the cold batching process can be effected by storing the impregnated and preferably rolled-up material at room temperature (15 to 30°C) for 3 to 24 hours, for example, the cold batching time being known to depend on the UV absorber.

On completion of the application process and fixation, the treated materials are conventionally rinsed, soaped, for example, for 20 minutes at 90°C with a solution containing 1g/l. of calcined sodium carbonate, and dried.

The treatment bath may optionally contain other customary auxiliaries, for example, levelling, wetting deaerating and antifoaming agents, penetration accelerants or crease resisting agents.

The cellulose fibre materials treated by the process of the present invention possess high sun protection factors. The sun protection factor is defined as the ratio of the harmful dose of UV energy on protected skin to the harmful dose of UV energy on unprotected skin.

Accordingly, a sun protection factor is also a measure of the transmissivity of fibre materials untreated and of those treated with reactive UV absorbers described in this invention.

The sun protection factor can be determined, for example, by the method described by B. L. Diffey and J. Robson in J. Soc. Cosmet. Chem., 40,127-133 (1989).

The UV absorbers of formula (1) are known or may be prepared by known methods.

The examples which follow illustrate the invention; parts and percentages are by weight unless otherwise stated.

Example 1 Four samples each of 10g. of a pre-washed cellulose fabric having a weight of 140g/m2 and a porosity of 0.9% are treated in an AHIBAO dyeing machine at a liquor ratio of 1: 20 in four different liquors.

Liquor 1 contains 5g/l. of a commercial crease inhibitor (Cibafluid CTM), 30g/i Glauber's salt, 15g/l. calcined sodium carbonate and 2ml/l. 30% sodium hydroxide solution Liquor 2 corresponds to Liquor 1, but additionally contains 3% of the UV absorber of formula (7), based on the weight of the fabric.

Liquor 3 corresponds to Liquor 1, but additionally contains 5% of the UV absorber of formula (7), based on the weight of the fabric.

Liquor 4 corresponds to Liquor 1, but additionally contains 10% of the UV absorber of formula (7), based on the weight of the fabric.

The fabric samples are added to the application liquor containing crease inhibitor and Glauber's salt, which is previously heated to 60°C. After 5 minutes the UV absorber, previously emulsified in 15ml. of the appropriate liquor, is added at pH 7. After 20 minutes 15g/l. of calcined sodium carbonate is added in 3 portions of 5g/l over 15 minutes followed, after 50 minutes, by 2ml/l of 30% sodium hydroxide solution. Following a total application time of 60 minutes, the samples are removed, rinsed in the overflow for 10 minutes at 70°C, then for a further 10 minutes at 50°C and, finally neutralised with acetic acid and dried at room temperature.

The determined sun protection factors of the four specimens are depicted in Table 1: Table 1 Liquor No. % Compound (7) Sun Protection Factor 1 None 8. 1 2 3 28. 2 3 5 39. 9 4 10 53. 5 The above results clearly demonstrate the substantial improvement in sun protection factor attained by the use of compound (7).

Example 2 Four samples each of 10g. of a pre-bleached (hydrogen peroxide) cotton-poplin fabric having a weight of 110g/m2 and a porosity of 0.4-0.5% are treated in a ZELTEXO dyeing machine at a liquor ratio of 1: 30 in four different liquors.

Liquor 1 contains 30g/l. Glauber's salt, 15g/l. calcined sodium carbonate and 0.8g/1.36°Be sodium hydroxide solution.

Liquor 2 corresponds to Liquor 1, but additionally contains 1 % of the UV absorber of formula (7), based on the weight of the fabric.

Liquor 3 corresponds to Liquor 1, but additionally contains 2.5% of the UV absorber of formula (7), based on the weight of the fabric.

Liquor 4 corresponds to Liquor 1, but additionally contains 5% of the UV absorber of formula (7), based on the weight of the fabric.

The fabric samples are added to the application liquor containing the Glauber's salt, which is previously heated to 60°C. After 15 minutes the UV absorber is added (except for Liquor 1) at pH 7. After 30 minutes 15g/l. of calcined sodium carbonate is added in 3 portions of 5g/1 over 15 minutes followed, after 15 minutes, by 0.8g/l. of 36°Be sodium hydroxide solution.

Following a total application time of 70 minutes, the samples are removed, rinsed in the overflow for 10 minutes at 70°C, then for a further 10 minutes at 50°C and, finally neutralised with acetic acid.

Subsequently, the samples prepared above are treated with an optical whitening either by the exhaust process or by padding as follows : a) the samples are treated with 0.13% of FWA (9) and with 3g/L. of stabilized sodium dithionite by the exhaust process at 95°C for 60 minutes, the liquor ratio being 1: 30. b) the samples are subjected to a reductive bleach with 3g/l. of stabilized sodium dithionite for 60 minutes at 95°C and a liquor ratio of 1: 30 and, subsequently treated with 3.6g/L. of FWA (8) by the padding process, the picik-up being 65%, and dried at 70°C.

The degrees of whiteness, determined according to the method of Ganz, and the sun protection factors, according to AS/NZS 4399/1996, of the samples are then measured, the results being summarized in Table 2 below : Table 2 Sample containing. Sun Protection Factor Degree of Whiteness Liquor 1 + FWA (9) 26 221 Liquor 2 + FWA (9) 52 216 Liquor 3 + FWA (9) 64 212 Liquor 4 + FWA (9) 71 205 Liquor 1 + FWA (8) 45 234 Liquor 2 + FWA (8) 66 225 Liquor 3 + FWA (8) 90 219 Liquor 4 + FWA (8) 105 212 The above results clearly demonstrate the substantial improvement in sun protection factor attained by the use of compound (7), whilst the degree of whiteness of the treated fabrics is not dramatically reduced.