IL37577A - Process for the optical brightening of fibre material of cellulose,or natural or synthetic polyamide - Google Patents

Description

'a'o am irusn: mn n1? Process for the optical brightening of fibre material of cellulose, or natural or synthetic polyamxde CJ3A-GEIGY AG. , C.35649 The present invention relates to a process for the optical brightening of fibre material of cellulose, or natural or synthetic polyamide in an organic solvent mixture, and to. the fibre material brightened according to this process .

It is known that fibre material of incompletely acylated cellulose can be brightened continuously using, inter alia, optical brighteners, containing sulphonic acid groups, in the form of their sodium salts, by impregnating this fibre material with the solution of an optical brightener in a water-soluble organic solvent, such as lower alkanols, optionally mixed with a water-insoluble organic, solvent preferably boiling below 250°C, and removing the excess solvent from the material under mild conditions, preferably at temperatures between 30 and 100°C. This process is disadvantageous inasmuch as with it satisfactory · brightening effects can practically only be achieved on cellulose 2¼-acetate.

It has now been found that fibre material of cellulose or natural or synthetic polyamide can be optically brightened by the exhaustion process by treating the fibre material, using a liquor ratio of at least 1:5 in terms of parts by weight, in the solution of at least one optical brightener salt, consisting of the radical of an anionic optical brightener and the radical of an inorganic base, in a solvent mixture consisting of 50 to 99 per cent by weight of unsubstituted os halogenated hydrocarbon boiling between 50 and 150°C and of 50 to 1 per cent by weight of liquid, water-soluble organic solvent boiling below 220°C, at a temperature between room temperature and the boiling point of the solvent mixture, optionally under pressure, and finishing the brightened fibre material in the usual manner.

In comparison with the previously known continuous process, more brilliant and intense brightening effects are in particular achieved, according to the invention, on cotton and fibre material of synthetic polyamide, whilst, on the other hand, the process according to the invention is distinguished, relative to the known aqueous application from a long bath, by better development of the brightener salts (higher fluorescence counts and more intense, more brilliant white effects) at low bath temperatures (approx. 20 to 50°C).

Suitable brightener salts which can be used according to the invention are the salts of inorganic bases, preferably the alkali metal salts, such as the potassium, lithium and especially the sodium salts, or the ammonium salts of an anionic optical brightener, especially of an optical brightener containing sulphonic acid groups and/or carboxylic acid groups. The brightener salts obtained industrially can be used directly. They can also be manufactured in a manner which is in itself known, for example by neutralisation of the aqueous solution of the anionic optical brighteners in the form of their free sulphonic acids and/or carboxylic acids, with appropriate inorganic bases, such as, for example, alkali metal hydroxides, alkali metal carbonates, alkali metal bicarbonates or ammonia. The brightener salts can also be manufactured in situ, for" example by directly introducing the optical brighteners, in the form of their free sulphonic acids and/or carboxylic acids, into an alkali alcoholate solution, advantageously into a sodium me hylate solution.

- The anionic optical brighteners can belong to the most diverse classes of brighteners. Particularly brilliant brightening effects are obtained with compounds which are derived from the classes of the stilbenes and pyrazolines.

Amongst these classes, derivatives of the distyryldiphenyl-disulphonic acids, 4,4'-bis-triazinylamino-stilbene-sulphonic acids, stilbyl-naphthotriazole-carboxylic acids or -sulphonic acids, 4, '-bis-v-triazolyl-stilbene-sulphonic acids or derivatives of diarylpyrazolines and triarylpyrazolines containing carboxylic acid groups and sulphonic acid groups are preferentially used. Dibenzothiophene-dioxides containing sulphonic acid groups may be mentioned as further suitable brighteners. . .. · .

Suitable hydrocarbons boiling between 50 and 150°C are, for example, aromatic hydrocarbons, such as toluene or xylene. Preferably, however, halogenated, especially chlorinated, hydrocarbons are used, for example chlorobenzene, but above all, because of their generally greater ease of regnera-tion and non-inflammability, lower aliphatic halogenated hydrocarbons, namely chloro-, bromo-, f luoro- or fluoro-chloro-hydrocarbons, for example trichloroethylene or tetra-chloroethylene ( "perchloroethylene" ) , l,l,2-trifluoro-l,2,2-trichloroethane , dichloroethane , 1,1,1-trichloroethane, tetra-chloroethane , pentafluoroethane , dibromoethylene , tribromo-ethylene, chloroform or carbon tetrachloride. Mixtures of such solvents can also be used.

B "liquid organic solvents which are soluble in water and boil below 220°Cn there are to be understood heat-stable solvents which are soluble in water not merely to the extent of fractions of a per cent, but to the extent of several per cent. Possible examples thereof are higher alkanols such as butanols or amyl alcohols, cycloaliphatic alcohols, such as cyclohexanol, araliphatic alcohols, such as benzyl alcohol, or aliphatic or cycloaliphatic ketones, such as acetone or methyl ethyl ketone or cyclohexanone.. However, those solvents according to the definition which are miscible with water in any ratio are preferred. Examples thereof are: monovalent lower aliphatic alcohols, such as lower alkanols , for example methanol, ethanol, or n- or iso-propanol; alkylene glycol monoalkyl ethers, such as ethylene glycol monomethyl ether or monoethyl ether; also, furfuryl alcohol or tetra-hydrofurfuryl alcohol; lower cyclic ethers, such as dioxane? lower anhydrous monocarboxylic acids, such as anhydrous formic acid and above all glacial acetic acid; N,N-dialkylamides of lower monocarboxylic acids, such as dimethylformamide or dimethylacetamide; amides of carbonic acid, such as Ν,Ν,Ν',Ν'- tetramethylurea; cyclic amides, such as N-methyl-pyrrolidone , or lower carboxylic acid nitriles, such as acetonitrile , and also mixtures of such liquid, water-soluble organic solvents.

The composition of the solvent mixture depends on the solubility of the brightener salts to be used.' It should be such as to give a homogeneous and clear brightener solution.

Further, care must be taken when choosing the solvent mixture that whilst achieving an optimum white effect there should, as far as possible, be no damage to the fibre.

Preferred solvent mixtures consist of 80 to 99 per cent by weight of halogenated lower aliphatic hydrocarbon boiling between 50 and 150°C and of 20 to 1 per cent by weight of liquid, water-soluble organic solvent boiling below 220°C, but very particularly of 90 to 99 per cent by weight of trichloroethylene , perchloroethylene or trifluoro- · trichloroethane and of 10 to 1 per cent by weight of a lower alkanol, such as ethanol, n- and iso-propanol or n-butanol, and above all methanol J an N,N-dialkylamide: of a lower car- boxylic acid, such as dimethylformamide ; a lower alkylene glycol monoalkyl ether, such as ethylene monoglycol methyl ether; or a lower ketone, such as acetone; or mixtures thereof.

In this specification and the appended claims, when not expressly stated otherwise, the term "lower" in connection with "alkyl" or "alkylene" designates a radical having '· at most 4 carbon atoms.

The brightener salts which can be used according to the invention are in themselves known.

The brightener salts are advantageously predissolved in small amounts of an organic solvent according to the defini tion, such as methanol, N-methyl-pyrrolidone or dimethyl-■formamide, after which the solution obtained is combined with the remaining solvent mixture.

Appropriately, the fibre material is treated in the brightener liquor according to the definition for 5 minutes to 2 hours j above all for 15 to 45 minutes, at a liquor ratio of 1:5 to 1:300, especially 1:10 to 1:50 (relative to parts at a b and the like, as well as drying, for example in warm air.

The brightener liquor to be used according to the invention preferably contains, depending on the nature of the optical brightener, 0.01 to 2 per cent by weight, especially 0.1 to 0.5 per cent by weight, of optical brightener salt, relative to the dry weight of the fibre material to be brightened.

Suitable cellulose fibres which can be brightened according; to the process of the invention are above all cotton, but regenerated cellulose fibres are also suitable. Examples of fibre material of natural polyamides are wool and silk, and of synthetic polyamides polycaprolactam (polyamide 6) , polyhexamethylene adipamide (polyamide 6,6), polyundecanoic acid amide (polyamide 11) , polydodecanoic acid amide (polyamide 12)' and polyoenanthic acid amide (polyamide 7). The latter are in particular used in the form of filaments, and also in the form of texturised synthetic polyamide fibres, such as "Banlon" . The fibre material mentioned can be brightened, according to the invention in any desired form, for example in the form of flocks, tops, yarn or - preferably -woven fabrics, knitted fabrics and so-called "fully-fashioned1 articles .

Using the process according to the invention, very uniform and brilliant white effects or brightening effects, and optical brightenings which are fast, for example to dry cleaning and washing, are obtained on fibre material of cellulose and natural or synthetic polyamide, especially on cotton and synthetic polyamide fibre material.

The solvents used in carrying out the process indus- trially can be recovered and recycled to the brightening process so that - in contrast to the previously known processes from an aqueous medium - the problem of purification of the effluent does not apply. Furthermore, rinsing baths are dispensed with, which constitutes' a further advantage of the process according to the invention. The process according to the invention also makes it possible in a simple manner to combine the dry cleaning of textiles with an optical brightening.

The examples which follow illustrate the invention. Example 1 .250 g of the optical brightener salt of the formula are dissolved in 5 g of dimethylformamide . The resulting solution is added to 2,000 g of a solvent mixture consisting of 95 per cent by weight of perchloroethylene and 5 per cent by weight of ethanol. 100 g of polyamide-6 fabric are introduced into .the resulting clear, fluorescent solution at 60°C, and the textile material is treated for 30 minutes at this temperature, with constant agitation. Thereafter the ' brightene fabric is squeezed out and dried in warm air.

The polyamide-6 fabric thus treated shows a brilliant uniform white.

If, in the above example,a fabric of polyamide-6 , 6 or polyamide "12, or a fabric of bleached cotton or bleached cedure otherwise remaining the same, a brilliant white effect is obtained on these materials also.

Example 2 mg of the optical brightener salt of the formula are dissolved in 0.5 g of N-methyl-pyrrolidone . The resultin clear solution is added to 150 g of a solvent mixture consisting of 96 per cent by weight of perchloroethylene and 4 per cent by weight of methanol. Thereafter, the resulting brightener liquor is warmed to 40°C, 10 g of polyamide-6 fabric are introduced into the liquor at this temperature, and. the textile material is treated at constant temperature for 30 minutes, with constant agitation. Thereafter, the brightened fabric is squeezed out and dried in warm air.

The fabric treated in this way shows a high, brilliant white effect which is fast to water and to dry cleaning.

If, in the above example, a fabric of bleached wool or of bleached cotton is used, the procedure otherwise remain-ing the same, a brilliant, strong hite effect is again obtained.

If, instead of the brightener salt indicated in the above example, the same amount of one of the brightener salts listed in Table I below, column 2, is used, and in other respects the procedure indicated in the example is followed, similar brightening effects are obtained on the materials mentioned.

Ta¾le I Example No. Optical Brightener Salt Continuation of Table I Continuation of Table 1 Continuation of Table 1 Example 16 , 0 mg of the optical "brightener salt described in Example 2 are dissolved in 5 g of N-methylpyrrolidone and 90 mg are dissolved in 5 g of water. The first stock solution is mixed with 800 g (= approx. 500 ml) of a solvent mixture of 97 per cent by weight of perchloroethylene and 3 per cent by weight of methanol, whilst the aqueous stock solution is diluted with 500 g of water. Both solutions are subsequently halved, and in each of the four solutions obtained 15 g of a polyamide-6 tricot are treated for 45 minutes, one fabric being treated in the organic brightener liquor at 25°G, one in the aqueous liquor at 25°C, one in the brightener liquor at 40°C and one in the aqueous liquor at 40°C.

Thereafter, the brightened fibre material is squeezed out and dried in a warm stream of air. The brightenings obtained are rated by determining the fluorescence counts with a Harrison fluorimeter.' ' The above experiments are repeated under the same conditions, but using a bleached cotton fabric instead of polyamide-6 tricot.

The ratings with the Harrison fluorimeter give the following results: Treatment Fluorescence counts measured with the Harrison fluorimeter* Polyaciide-6 Polyamide-6 Cotton Cotton ° C 40°C 25° C 40° C aqueous application 122 173 179 178 application from solvent mixture 154 182 186 209 * Model EE-100B (manufactured "by: Engineering Equipment Co., Boynton Beach, Fla. , USA).

The above results show that as a result of the application, according to the invention, from a solvent mixture, substantially better development of the brightener salts on the substrate is achieved as compared to aqueous application. ■■ » Example 17 mg of the optical brightener salt described in Example 2 are dissolved in 0.5 g of N-methyl-pyrrolidone.

The resulting clear solution is added to 150 g of a solvent mixture consisting of 94 per cent by weight of perchloro-ethylene and 6 per cent by weight of n-butanol. Thereafter, 10 g of a bleached cotton fabric are introduced at 75°C into the brightener liquor obtained, and the fabric is treated for 30 minutes at 75°C whilst constantly circulating the liquor. Thereafter, the brightened fabric is squeezed out and dried in the usual manner.

A level, strong white effect is obtained on the treated cotton fabric.

Example 18 mg of an optical brightener of the formula are dissolved 'in 1,5 ml of methanol. The clear solution ob-teined is added to 150 g of the solvent mixture given in Example 17 and the procedure of vExample 17 is followed.

A uniform, strong white effect is obtained on the treated cotton fabric.

Example 19 ; 35 mg of the optical "brightener salt described in Example 1 are dissolved in 0.5 g of dimethylformami'de.

Thereafter, the solution obtained is added to 200 g of a solvent mixture consisting of 97 per cent by weight of tri-chloroethylene and 3 per cent by weight of methanol. 10 g of cotton poplin are then introduced into the brightener liquor obtained, at 50°C, and the textile material is treated at this temperature for one hour, whilst constantly circulating the liquor. After the usual squeezing out and drying, a uniform and strong white effect is obtained.

If, instead of cotton poplin, a woven fabric or knitted fabric of polyamide-6 or polyamide-6 ,6 is -used, similar brightening effects are obtained.

If, in the above example, the 97 parts by weight of trichloroethylene are replaced by an equal amount of one of the hydrocarbons indicated i Table II below, column 2, and in other respects the procedure indicated in the example is followed, brilliant white effects are also obtained.

Table II If, in Examples 19 to 26, the same amount of one of the solvents indicated in Table III below, column 2, is used instead of 3 per cent by weight of methanol, and in other respects the procedure noted in this example is followed, uniform and well-developed optical brightenings are also obtained. .

Table III Example No. Water-miscible solvents 27 ethanol 28 isopropanol 29 n-butanol ethylene glycol monomethyl ether 31 ethylene glycol monoethyl ether 32 tetrahydrofurfuryl alcohol Continuation of Table III.

Example No. Water-miscible solvents 33 benzyl alcohol 34 dioxane N-methylpyrrolidone 36 dimethylformamide 37 dimethylacetamide 38 acetonitrile 39' acetone 40 glacial acetic acid

Claims (8)

WHAT WE CLAIM IS:

1. A process for the optical "brightening of ( fibre material of cellulose or natural or synthetic polyamide according to the exhaustion process, characterised in that the fibre material is treated, using a liquor ratio of at least 1:5 in terms of parts by weight, in the solution of at least one optical brightener salt, consisting of the radical of an anionic optical brightener and the radical of an inorganic base? in a solvent mixture consisting of 50 to 99 per cent by weight of unsubstituted or halogenated hydrocarbon boiling between 50 and 150°C and of 50 to 1 per cent by weight of liquid, water-soluble organic solvent boiling below 220°C, at a temperature between room temperature and the boiling point of the solvent mixture, optionally under pressure, and that the brightened fibre material is finished in the usual manner.

2. A process according to Claim 1, characterised in that an alkali metal salt or ammonium salt of an optical brightener containing sulphonic acid groups and/or carboxylic acid groups is used. ■ ·

3. A process according to Claims 1 and 2, characterised by the use of derivatives of distyryldiphenyldisulphonic acids, 4,4' -bis»triazinylamino-stilbene-sulphonic acids, stilbyl-naphthotriazole-carboxylic acids or -sulphonic acids, 4,4'-bis-v-triazolyl-stilbene-sulphonic acids or of derivatives of diarylpyrazolines and triarylpyrazolines containing carboxylic acid groups and sulphonic acid groups.

4. : A Process according to Claims 1 to 3, characterised in that a solvent mixture is used which consists of 80 to 99 per cent "by weight of halogenated lower aliphatic hydrocarbon boiling between 50 and 150°C and of 20 to 1 per cent by weight of liquid, water-soluble organic solvent boiling below 220°C.

5. A process according to Claim 4, characterised in that a solvent mixture is used which consists of 90 to 99 per cent by weight of trichloroethylene , perchloroethylene or trichlorotrifluoroethane and of 10 to 1 per cent by weight of a lower alkanol, an N ,N-dialkylamide of a lower mono-carboxylic acid, a lower alk lene glycol monoalkyl ether, or a ketone, or mixtures thereof.

6. A process according to Claim 5, characterised in that a solvent mixture is used which consists of 90 to 99 per cent by weight of trichlorethylene, perchlorethylene , or trichlorotrifluorethane and 10 to 1 per cent by weight of methanol, dimethylformamide , ethylene monoglycol methyl ether and/or acetone.

7. A process according to Claims 1 to 6, characterised in that cotton or synthetic polyamide fibres are used.

8. Fibre material brightened according to the process of Claims 1 to 7.