UVA Formulation

The present invention relates to a water-dispersible formulation in powder form comprising a UV absorber (UVA) and a dispersant, to a process for the preparation of that formulation and to a method of dyeing textile material.

The disperse dyes applied in the dyeing or printing of textile fibre materials, especially synthetic textile fibre materials, are in some cases substantially damaged when subject to the action of light, especially when simultaneously subject to the action of heat. In order to avoid such damage, UV absorbers (UVAs) are added to the dyeing liquors and printing pastes when dyeing fibres used in the automotive or swimwear sectors or in so-called "outdoor" articles.

EP-A 0 468 921 describes aqueous dispersions comprising a hydroxyphenyl-s-triazine as UVA and also an anionic and/or non-ionic dispersant, which are suitable as light stabilisers for textile fibres and which are distinguished by good transport and storage stability. For economic and ecological reasons, however, there is a need for commercial forms that are in powder form.

However, formulations in powder form comprising UVAs, for example benzotriazoles, substituted benzotriazoles, triazines or benzophenones, generally have poor storage stability, that is to say they have a tendency towards agglomeration during storage.

It has now been found that formulations in powder form comprising a hydroxyphenyl-s- triazine in combination with specific, sulfo-group-containing, anionic dispersants have a high degree of storage stability and are suitable as light stabilisers for textile fibre materials.

The present invention relates to a water-dispersible formulation in powder form comprising (A) from 5 to 50 % by weight, based on the sum of components A + B, of a compound of formula (1 )

wherein R is Ci-C ₈ alkyl, d-C ₈ alkoxy, halogen or hydroxy,

n is 0, 1 or 2, and

R ₁ and R ₂ are each independently of the other C-ι-C ₁₈ alkyl which is unsubstituted or substituted by hydroxy, CrC ₈ alkoxy, CrC ₈ alkylthio, amino, (Ci-C ₈ )alkylamino or by di(Ci-C8)alkylamino, or phenyl which is unsubstituted or substituted by hydroxy, chlorine, Ci-C ₈ alkyl or by Ci-C ₈ alkoxy, with the proviso that if R ₁ and R ₂ are substituted phenyl the compound has fewer than two alkoxy radicals; and (B) from 50 to 95 % by weight, based on the sum of components A + B, of a condensation product prepared from an aromatic sulfonic acid and formaldehyde.

Alkyl and alkoxy groups as the radical R, R ₁ or R ₂ may be linear or branched.

Examples of alkyl groups are methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, isobutyl, n-pentyl, neopentyl, n-hexyl, 2-ethylhexyl, n-octyl and isooctyl.

Suitable alkoxy groups are, for example, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, tert-butoxy, isobutoxy, n-pentyloxy, neopentyloxy, n-hexyloxy, 2-ethylhexyloxy, n-octyloxy and isooctyloxy.

Halogen is, for example, fluorine, bromine or, preferably, chlorine.

As component A preference is given to a compound of formula (1 a)

wherein R ₁ and R ₂ are as defined hereinbefore.

R ₁ and R ₂ in formula (1a) preferably are phenyl which is unsubstituted or substituted by hydroxy, chlorine, CrC ₈ alkyl or by CrC ₈ alkoxy.

As component A special preference is given to the compound of formula (1 b)

The compounds of formula (1 ) are known and are described, for example, in EP-A 0 468 921.

Products that are suitable as component B are known, for example, from US Patent 5,009,669.

The formulation according to the invention preferably comprises as component B a condensation product of formaldehyde with sulfonated naphthalene, sulfonated CrC ₄ alkyl- naphthalene, sulfonated biphenyl, sulfonated diphenyl ether, sulfonated ditolyl ether, sulfonated phenol, sulfonated toluene, sulfonated xylene or sulfonated mesitylene.

As component B special preference is given to a condensation product of formaldehyde with sulfonated ditolyl ether or a condensation product of formaldehyde with sulfonated di(2- naphthyl)methane.

The ratio of amounts of components A and B in the formulations according to the invention can vary within wide ranges.

The formulations according to the invention preferably comprise from 3 to 30 % by weight, especially from 5 to 15 % by weight, of component A and from 70 to 97 % by weight, especially from 85 to 95 % by weight, of component B.

In addition to components A and B, the formulations according to the invention can comprise further customary additives, for example stabilisers, complexing agents, thickeners, dust- binding agents, anionic or non-ionic dispersants, separating agents, frost protection agents, antifoams, preservatives and bactericides.

- A -

Suitable stabilisers and thickeners are, for example, polyurethanes (PUR) or carboxyl-group- containing polymers which can be prepared by polymerisation of ethylenically unsaturated mono- or di-carboxylic acids having from 3 to 5 carbon atoms and which polymers generally have molecular weights of from 500,000 to 6,000,000.

Examples thereof include polyacrylic acid, polymerised methacrylic acid, crotonic acid, itaconic acid, citraconic acid, maleic acid, fumaric acid and mesaconic acid, and copolymers of olefins, e.g. ethylene and propylene, diketenes, acrylic acid esters, methacrylic acid esters and acrylamides, with suitable monomers, e.g. acrylic acid, methacrylic acid, methacrylonitrile, vinylphosphonic acid or with maleic acid/styrene copolymers or maleic acid/vinyl acetate copolymers.

Suitable PUR thickeners are, for example, Bermodol ^® PUR 2102, Bermodol ^® PUR 2110, Bermodol ^® PUR 2130 and Bermodol ^® PUR 2150 (Akzo Nobel).

Further suitable thickeners are polysaccharides, e.g. carboxymethyl cellulose, methyl cellulose, methyl hydroxyethyl cellulose, dextrin, locust bean flour, alginates, polyethylene glycols, polyvinyl alcohols, finely divided silica and phyllosilicates, e.g. bentonites, smectites and montmorillonites.

Especially suitable thickeners are acrylic polymers, e.g. polyacrylic acid, and copolymers of acrylic acid and acrylamide having molecular weights of from 500,000 to 6,000,000.

Further especially suitable thickeners are heteropolysaccharides formed from the monosaccharides glucose, mannose and glucuronic acid, e.g. xanthan.

The formulation according to the invention advantageously comprises one or more dispersants.

Examples of suitable dispersants include vinyl polymers, e.g. polyvinyl alcohol, and polyaddition products of from 2 to 80 mol of alkylene oxide, especially ethylene oxide or propylene oxide, with 1 mol of a phenol, of an unsaturated or saturated alcohol, of a fatty acid, fatty amine or fatty amide having from 8 to 22 carbon atoms.

The dispersant is preferably used in an amount of from 1 to 15 % by weight, especially from 2 to 10 % by weight, based on the sum of components A + B (= 100 % by weight).

The formulations in powder form according to the invention can be prepared in a manner known per se using various processes.

Advantageously, an aqueous suspension containing the above-defined components A and B is prepared first. Size reduction of the agglomerates thereby obtained can be carried out by re-precipitation or by grinding of the aqueous suspension in the presence of dispersants and, where appropriate, further additional adjuvants, e.g. protective colloids, wetting agents and the like.

Size reduction (dispersal) is generally carried out in known size reduction machines, e.g. ball mills, high-speed mills, e.g. attrition mills, sand or powder mills, which contain glass, porcelain or steel balls, quartz sand or plastics beads as grinding elements. The grinding procedure is carried out until components A and B have the desired fine distribution. Alternatively, by adding an amine, e.g. diethylamine, triethylamine, n-butylamine, tri-n- butylamine, ethylenediamine or 2-ethanolamine, a solution of the corresponding ammonium salt can be prepared first. By addition of acid, e.g. hydrochloric acid, sulfuric aid, nitric acid, phosphoric acid, formic acid, acetic acid, oxalic acid etc., a finely dispersed suspension is obtained; the grinding procedure can be dispensed with in this process variant.

Thereafter the aqueous suspension is converted to the dry state using known processes, e.g. by means of spray drying. The fine distribution obtained on drying is preserved for a long time and the formulation in powder form has a high degree of storage stability, that is to say the finely dispersed particles have no substantial tendency to agglomerate.

The invention relates also to a process for the preparation of a water-dispersible formulation in powder form comprising the above-defined components A and B, wherein an aqueous suspension comprising the above-defined components A and B is converted to the dry state by means of spray drying.

Preferred formulations according to the invention additionally comprise (C) a granulation aid.

In that case, any excipient customarily used in wet granulation methods can be used. Examples of granulation aids include carboxymethyl cellulose, citric acid, water glass, polyvinylpyrrolidone (PVP) and ethanolammonium salts.

Preference is given to using polyvinylpyrrolidone (PVP) as component C in the formulations according to the invention.

The formulation according to the invention can advantageously be used in customary dyeing processes for textile materials, especially textile materials comprising synthetic fibres. For the purpose there is first prepared an aqueous dispersion containing from 0.1 to 30.0 % by weight, preferably from 0.2 to 20.0 % by weight, especially from 0.5 to 15.0 % by weight, of the formulation according to the invention, for example by stirring the powder-form formulation comprising components A and B, where appropriate in combination with further additives, e.g. dispersants, thickeners or granulation aids, together with the appropriate amount of water in a mixing apparatus until a homogeneous dispersion is obtained. The dispersion is slowly introduced, with stirring, into an aqueous bath, the dye is added and the dyeing liquor is ready for the dyeing process.

The amount in which the aqueous dispersion comprising the formulation according to the invention is used is generally from 0.5 % by weight to 10.0 % by weight, preferably from 1.0 to 5.0 % by weight, based on the weight of the fibres.

The fibre material which can be dyed in the presence of the formulation according to the invention consists of, for example, cellulose ester fibres, polyamide fibres or, preferably, polyester fibres.

The dyeings are advantageously carried out by the exhaust method using an aqueous liquor. The liquor ratio is preferably from 1 :3 to 1 :50, especially from 1 :5 to 1 :30. The liquor temperature during dyeing is preferably from 70 ⁰ C to 140 ⁰ C, especially from 80°C to 135°C.

The dyeing liquor comprising the formulation according to the invention, the dye and, where appropriate, further adjuvants is advantageously adjusted to a pH of from 4.5 to 5.5. The exhaust temperature is increased at a rate of 2°C/min from 30 ⁰ C to 135°C and is held at that value for from 15 to 90 min.

The dyeing liquor is then cooled to from 60 to 80 ⁰ C. The fibre material is washed with water and, if necessary, subjected to a reduction clear in an alkaline medium. Afterwards the dyed fibres are rinsed again and dried.

The addition of particular dyes, UVAs or other adjuvants to the dyeing bath often gives rise to a pressure difference when dyeing using a cheese or beam. That pressure difference is to be understood as the difference between the pressure produced by the dyeing apparatus pump under normal conditions before addition of the dye and adjuvants compared to the corresponding pressure after the addition of the dye and adjuvants. Increasing the bath temperature results in an increase in the pressure difference until the exhaust temperature has been reached and the dyes and chemicals are transferred to the fibre. This pressure increase causes uneven circulation of the liquor and, as a result, uneven distribution of the dye and the adjuvants on the fibre.

It has now been found, surprisingly, that the pressure difference can be substantially reduced as a result of use of the formulations according to the invention comprising components A and B.

The following Examples illustrate the invention.

Example 1

200 g of a presscake of 2,4-bis(2,4-dihydroxyphenyl)-6-(4-methoxyphenyl)-s-triazine are dispersed in an aqueous solution of 400 g of naphthalenesulfonic acid/formaldehyde polycondensate (sodium salt) and 400 g of dextrin. The dispersion is subjected to wet grinding and is then atomised in a spray dryer.

1000 g of the powder contain the following constituents:

100 g 2,4-bis(2,4-dihydroxyphenyl)-6-(4-methoxyphenyl)-s-triazine

400 g naphthalenesulfonic acid/formaldehyde polycondensate (sodium salt) 400 g dextrin

80 g water

20 g NaCI

The resulting powder has a high degree of storage stability. After storage for 3 months at 60 ⁰ C, neither yellowing nor agglomeration can be detected.

When the powder is employed in a dyeing process (exhaust method) for textile materials, only a very small pressure difference of 0.4 bar arises.

Example 2

200 g of a presscake of 2,4-bis(2,4-dihydroxyphenyl)-6-(4-methoxyphenyl)-s-triazine are dispersed in an aqueous solution of 390 g of naphthalenesulfonic acid/formaldehyde polycondensate (sodium salt) and 35 g of polyvinylpyrrolidone (K 15, International Specialty Products, MW 9500) and dissolved by addition of monoethanolamine. The pH is from 10 to 11 and is lowered to 6 by addition of sulfuric acid/acetic acid. The resulting fine dispersion is atomised in a spray dryer. 1000 g of the powder contain the following constituents:

100 g 2,4-bis(2,4-dihydroxyphenyl)-6-(4-methoxyphenyl)-s-triazine

390 g naphthalenesulfonic acid/formaldehyde polycondensate (sodium salt)

375 g ethanolammonium sulfate/acetate

35 g polyvinylpyrrolidone

80 g water 20 g NaCI

The resulting powder has a high degree of storage stability. After storage for 3 months at 40 ⁰ C, no agglomeration and only slight yellowing can be detected. When the powder is employed in a dyeing process (exhaust method) for textile materials, only a very small pressure difference of 0.4 bar arises.