FR2794476A1 - USE OF POLYALCOXYL TERPENIC DERIVATIVES IN THE TREATMENT OF TEXTILE FIBERS - Google Patents

Abstract

The invention concerns the use, during the treatment of textile fibres, of polyalkoxylated terpene derivatives of formula: Zi - X - [CH(R<3>) CH(R<4>)-O]n A; wherein Zi represents a bicyclo[a,b,c]heptenyl or bicyclo[a,b,c]heptyl radical, optionally substituted by at least a C1-C6 alkyl radical; a, b, and c being such that a + b + c = 5, a = 2, 3 or 4, b = 1 or 2, c = 0 or 1; X represents -CH2-C(R<1>)(R<2>)-O- or -O-CH(R'<1>)-CH(R'<2>)-O- wherein the radicals R<i> represent hydrogen or a hydrocarbon radical; R<3> and R<4> represent hydrogen or an alkyl or alkenyl group; n is a mean value ranging between 1 and 200; A represents hydrogen, an alkyl, (alkyl)aryl radical, a halogen, -CH2-CH(OH)R<5>, -SO3M, -OPO3(M)2, -(CH2)a-COOM, -(CH2)b-SO3M, or a mixture of said compounds. The use of said compound is particularly advantageous in dyeing operations.

Description

<B> USE OF </B> POLYALCOXYL TERPENIC DERIVATIVES <B> IN THE </B> TREATMENT <B> OF </B> FIBERS <B> TEXTILES </B> The present invention relates to the use, during the treatment of textile fibers, of derivatives of polyalkoxylated terpene compounds, and more particularly during dyeing operations.

First of all, it is specified that in what follows, only textile fibers will be referred to, knowing that this term will designate <B> to </B> both fibers, threads, knits, fabrics and nonwovens. In addition, the present invention applies just as well to the treatment of natural textile fibers (natural and regenerated cellulose fibers (cotton), wool) as to synthetic fibers (polyester, polyamide (nylon), polyacrylonitrile (acrylic).

The treatment of textile fibers comprises various stages, such as, among others, roasting, desizing, cleaning, bleaching, mercerization, <B> q </B> stages of dyeing, finishing. And during these steps, it is necessary to use wetting and / or penetrating agents so as to make the agent used during the step concerned effective. Conventionally, ethoxylated nonylphenols are used. They are very effective agents, but they have the drawback of producing a large quantity of foam. <B> It </B> can be used in combination with <B> </B> an anti- agent. foam, such as, for example, <B> based </B> anti-foaming products based on silicone emulsions. Unfortunately, under very high shear conditions, as can be encountered during dyeing operations, the anti-foaming agents are often destabilized and a silicone gel forms which is deposited on the fibers, resulting in the appearance of permanent stains on the fabric.

The object of the present invention is therefore to propose the use of a wetting / penetrating agent which is as effective as the compounds usually employed in the stages of the treatment of textile fibers, but which does not have the drawbacks due to <B> to </B> the appearance of foam.

X représente -CH2-C(Rl)(R2)-O- <B>OU</B> -0-CH(R'l)-CH(R'2)-O- dans lesquelles<B>:</B> R' et R2, identiques ou différents, représentent l'hydrogène ou un radical hydrocarboné, saturé ou non, linéaire, ramifié ou cyclique, en CII-C6, RI et R2, identiques ou différents, représentent l'hydrogène ou un radical hydrocarboné, saturé ou non, linéaire, ramifié ou cyclique, en Cl-C22, <B>3</B> 4 R et R identiques ou différents, représentent un atome d'hydrogène ou un groupement (cyclo)alkyle ou (cyclo)alcényle linéaire ou ramifié en Cl-C22, <B>-</B> n est une valeur moyenne comprise entre<B>1</B> et 200 <B>- A</B> représente un atome d'hydrogène, un radical alkyle en Cl-C6, un radical aryle ou <B>5 5</B> alkylaryle, un atome d'halogène, un groupement -CH2-CH(OH)R # où R représente un radical alkyle linéaire ou ramifié ou cyclique en Cl-C22 ou aryle, ou un groupement choisi parmi -S03M, -OP03(M)2, -(CH2),,-COOM, -(CH2)b-SO3M <B>,</B> avec a et<B>b</B> allant de<B>1</B> <B>à 6,</B> M représentant H, Na, K, Li, N(R4)' où les radicaux R, identiques ou différents, représentent un atome d'hydrogène ou un radical alkyle linéaire ou ramifié ou cyclique en Cl-C22 éventuellement hydroxylé, ou un mélange de ces composés. Thus, the present invention relates to a process for treating textile fibers comprising at least one of the following steps <B>: </B> (a) scorching, <B> (b) </B> desizing, (c ) cleaning, <B> (d) </B> bleaching, (e) mercerization, (f) dyeing steps, <B> (g) </B> finishing, in which at least the one of the above steps, a compound of formula (1) Zi <B> - </B> X <B> - </B> [CH (R <B> 3 </B> CH (R ') -Ciln <B> - A; </B> Formula in which <B>: </B><B> - </B> Zi represents a bicyclo [a, b, c] heptenyl or bicyclo [a, b, c] radical heptyl, optionally substituted by at least one C 1 -C 6 alkyl radical, preferably methyl, a, <B> b </B> and c being such that a <B> b </B> + c <B≥ 5, </B> a 2, <B> 3 </B> or 4, <B> b 1 </B> or 2, <B> c 0 or 1, </B> and comprising a backbone chosen from those indicated below (Zl <B> to </B> Z7), as well as among their corresponding heptyl without double bond <B>: </B>

X represents -CH2-C (R1) (R2) -O- <B> OR </B> -0-CH (R'l) -CH (R'2) -O- in which <B>: </ B> R 'and R2, identical or different, represent hydrogen or a hydrocarbon radical, saturated or not, linear, branched or cyclic, CII-C6, RI and R2, identical or different, represent hydrogen or a radical hydrocarbon-based, saturated or not, linear, branched or cyclic, C 1 -C 22, <B> 3 </B> 4 R and R identical or different, represent a hydrogen atom or a (cyclo) alkyl or (cyclo) group linear or branched C1-C22 alkenyl, <B> - </B> n is an average value between <B> 1 </B> and 200 <B> - A </B> represents a hydrogen atom, a C1-C6 alkyl radical, an aryl or <B> 5 </B> alkylaryl radical, a halogen atom, a -CH2-CH (OH) R # group where R represents a linear or branched alkyl radical or cyclic in C1-C22 or aryl, or a group selected from -S03M, -OP03 (M) 2, - (CH2) ,, - COOM, - (CH2) b-SO3M <B>, </B> with a and <B> b </B> ranging from <B> 1 </B><B> to 6, </B> M representing H, Na, K, Li, N (R4) 'where the radicals R, identical or different, represent a hydrogen atom or a linear or branched or cyclic C1-C22 alkyl radical optionally hydroxylated, or a mixture of these compounds .

The compounds (hereinafter called terpene compounds) used will first of all be described. As has been indicated previously, the derivatives of terpene compounds used in the process according to the invention correspond <B> to </B> the formula mentioned above.

In this a formula, the radical Zi is preferably attached to the rest of the chain via any one of its carbon atoms numbered <B> 1 to 6. </B> According to a more particular embodiment, the radical Zi is attached to the rest of the chain through the intermediary of carbon atoms <B> 1, 5 </B> and <B> 6. </B>

According to an advantageous variant of the invention, the compounds are such that the Zi radical is substituted on at least one of its carbon atoms, by at least two C1-C6 alkyl groups, preferably by two methyl radicals. More particularly, the substituents are located on the carbon atom <B> 7. </B>

A first family of compounds corresponds <B> to </B> that in which X represents -CH2-C (R1) (R2) -O-. In such a case, the 4- radicals correspond more especially to the Z3 <B> to </B> Z7 radicals. In addition, the rings contain ethylenic unsaturation. In addition, they bear two substituents, preferably methyl, on the <B> 7 carbon atom. </B> Preferred compounds are defined by the radicals Z4 and Z5, bearing two methyls on the <B> 7 carbon. </B>

A second family of compounds corresponds <B> to </B> that in which X represents -0-CH (R'l) -CH (R'2) -O-, More particularly, the rings do not contain any unsaturation ethylenic and are represented by the radical Z3. Note that in the case of this family, it is expected that at least R'l or R '2 is not hydrogen.

Thus, a preferred embodiment consists of compounds in which R'1 or R'2 is a methyl radical. According to another particular characteristic of this family of compounds, the carbon atom <B> 7 </B> carries two methyl substituents as well as a C1-C6 alkyl substituent, preferably a methyl, located on the atom of carbon 2 or the carbon atom <B> 5. </B>

With regard to the reasons <B> - </B> [CH (R <B> 3) - </B> CH (R ') <B> -01 -, </B> it was specified that R <B> 3 </B> and 4 R # which are identical or different, represent a hydrogen atom or a linear or branched (cyclo) alkyl or (cyclo) alkenyl group in C1-C22, preferably in C1-C6. <B> 3 </B> 4 More particularly, the radicals R and R #, which may or may not be identical, represent a hydrogen atom, a methyl radical or an ethyl radical. If the <B> - </B> [CH (R ') <B> - </B> CH (R') <B> -01 - </B> patterns are different, their distribution is statistical or sequenced. According to this last possibility, it is possible to envisage having two different blocks, or more.

A type of sequenced compounds which may be suitable <B> for </B> the implementation of the invention are those having the following sequence <B>: </B> <B> - </B> [CH (R <B> 3) - </B> CH (R ') -O] p - [CH2 <B> - </B> CH2 <B> -01, </B> - [CH (R <B> 3 ) _ </B> CH (R ') -0], - sequence in which R <B> 3 </B> or R 4 is different from hydrogen, and n <B≥ p </B> + < B> q + </B> r.

According to a particular embodiment, said units correspond to <B> to </B> oxyethylenated units and / or <B> to </B> oxypropylenated units.

n is an average value between <B> 1 </B> and 200. <B> It </B> corresponds <B> to </B> the total sum of the patterns - [CH (R ') <B> - </B> CH (R4) -01-.

Preferably, the number of oxyethylenated units is between <B> 1 </B> and 200, preferably between <B> 1 </B> and <B> 50, </B> and even more particularly, between <B> 1 </B> and 20.

As regards the number of oxypropylene units, their average number is between <B> 0 </B> and 20, more particularly between <B> 1 </B> and <B> 10, </B> preferably between <B> 1 </B> and 4.

<B> It </B> can be very advantageous to have available a terpene compound corresponding <B> to </B> a mixture of compounds of formula <B> (1) </B> in which at least the one of them is such that it exhibits the sequence mentioned above.

These compounds, as well as their method of preparation are described in particular in international applications WO 96/01245 and WO <B> 98/28249. </B> Reference may therefore be made to them for what relates to <B> to </B> to the definition and obtaining of said compounds.

The process according to the invention therefore consists <B> in </B> using the compounds which have just been described, in one or more stages carried out during the treatment of textile fibers.

It has in fact been observed that said compounds have properties for wetting textile fibers which are quite advantageous, thereby promoting the penetration of the textile fibers by the treating reagent.

In addition, the compounds used in the invention exhibit good resistance under the often very harsh conditions encountered during the treatment of fibers. Indeed, many steps are carried out in a very alkaline medium.

In addition, the compounds according to the invention have the advantage of having their structure adapted according to the requirements of the operation in which they are used. Thus, on a common basis, it is possible to have an effective nonionic or ionic compound, compatible with the various compounds present in the solution intended for the treatment of the fibers.

The textile fibers which are the subject of the treatments include residual additives, originating from the previous stages, such as lubricants (sizing additives (lubricants for sectors in the case of synthetic fibers), polyvinyl alcohol, carboxymethylcellulose), cohesion of fibers (starch), film-forming agents (hydrocolloids). <B> It </B> is necessary to rid the fibers of these compounds. This operation is carried out during a step called desizing (step <B> (b. </B>

The desizing operation can be carried out enzymatically (aiming <B> to </B> depolymerize the starch, if it is present) and / or by chemical oxidation. In the latter case, the oxidation reaction is carried out with an oxidizing agent chosen from hydrogen peroxide, persulphates and perborates, for example. It is also used in an alkaline medium. Alkali metal hydroxides (such as sodium hydroxide) but also alkali metal carbonate and bicarbonate can be used <B>; </B>, sodium hydroxide being preferred. Usually the concentration of alkaline agent is of the order of 2 <B> to 5 </B> gA, so as <B> to </B> obtain a <B> pH </B> of between <B> 10 </B> and 12.

This step is carried out in a solution comprising <B> 70 to 80% </B> water.

In addition, it is carried out <B> at </B> hot. Thus temperatures above <B> to </B> 50 * C are conventional.

In addition, the desizing can be carried out in the presence of the terpene compound described, the use of which is the subject of the invention.

The content of this compound in the desizing bath varies more particularly between <B> 1 </B> and <B> 5 </B> gA.

Generally, the textile fibers are impregnated in the solution, either continuously (steam cabin) or discontinuously (rotating rollers). This step can take place in one or more passes.

Depending on the nature of the textile fiber, it may be necessary or simply advantageous to carry out a preliminary step, called a scorching step (step (a. This step aims to give a smoother surface <B> to </ B> the textile fiber, because it consists of <B> </B> burning the fibers that protrude from the surface of the latter.

Note that the implementation of this toasting step does not facilitate that of the desizing step. Indeed, the textile fiber having undergone such a treatment is overdried and consequently, it is necessary to be able to have a solution having a high wetting power if one wants to maintain a good efficiency <B> to </B> the desizing step.

Once the desizing step has been carried out, a cleaning step can be implemented (step (c. This step is more generally used when the textile fibers comprise cotton. Indeed, this operation aims to eliminate the fibers). compounds naturally present on cotton fibers, such as for example cellulose residues (hemicellulose, immature cellulose), natural oils or waxes which are the cause of heterogeneities in the final fabric, whether or not dyed.

This cleaning operation is carried out in a strongly alkaline environment. Conventionally, the concentration of alkaline agent in the bath is from 20 <B> to </B> 40 <B> g / l. </B> Advantageously, sodium hydroxide is used.

The medium can likewise comprise the terpene compound. The content of this compound can advantageously be between <B> 1 </B> and <B> 5 g / 1. </B>

The step is more particularly carried out <B> at </B> a temperature of the order of <B> 60- </B> <B> 80 ". </B>

This step is generally carried out in a <B> steam </B> cabin.

<B> A </B> after this operation, the textile fibers can be dyed directly as soon as the colors are dark.

But conventionally, the textile fiber treatment process continues with a bleaching step (step <B> (d. </B>

The operation takes place by means of an oxidant which is more particularly hydrogen peroxide.

<B> It </B> may be advantageous to use a stabilizer, such as silicates, hypochlorites, polyphosphonic acid.

The bleaching step is carried out <B> at </B> high temperatures, of the order of <B> 70 </B> <B> to </B> 80OC.

<B> A </B> the end of the bleaching step, one can optionally implement a step called mercerization or caustization (step <B> (d. </B>

This step consists of soaking the textile fibers in an alkaline solution <B>; </B> the textile fibers being possibly subjected, during this step, <B> </B> to a mechanical -tension. The purpose of this operation is to improve the efficiency of the operation of dyeing the fibers, as well as their resistance to tearing.

Several possibilities are possible for this operation.

According to a first possibility, the soaking is carried out with a solution having an alkaline agent concentration of the order of 200 <B> to 300 </B> gA. The step, according to this variant, is carried out <B> at </B> a temperature of the order of <B> 15 to 25 OC. </B>

According to another variant, it is possible to carry out the soaking with a solution whose alkaline agent concentration is approximately 200 <B> g / 1, </B> knowing that the operation is carried out <B> at </ B> a temperature between <B> 55 </B> and 70OC, followed by a cooling step and a rifflge <B> to </B> room temperature, by exerting tension on the textile fibers. <B> It </B> is also possible to carry out this step with a solution with an alkaline agent content of <B> 100 -160 g / 1, </B> by not exerting tension on the textile fibers, and <B> at </B> a temperature between about 20 and 40OC. In such a case, we no longer speak of "mercerization" but of "caustization".

The alkaline solution may likewise comprise the terpene compound, with a concentration varying more particularly between <B> 1 </B> and <B> 5 g / 1. </B> The textile fibers are subsequently dyed, in a series of steps (e). These steps are well known in the field.

So-called "dispersed" dyes can be used, that is to say using pigments that are insoluble in water, or else called "reactive" dyes, that is to say using pigments. water-soluble pigments but attaching to reactive sites present on the fibers. <B> A </B> by way of example, and when the fibers are a mixture of synthetic fibers <B> / </B> natural fibers (e.g. polyester / cotton), the dyeing may include the following steps <B >: </B> coloring of synthetic fibers (step (e1, fixing of these pigments (step (e2, release of unbound pigments (step (e3, coloring of natural fibers (step (e4, washing of unbound pigments (step (e5.

When the fibers comprise only one or the other of the types of fibers, then the specific steps <B> to </B> this type of fibers are only implemented.

Preferably, the dyeing operations are carried out <B> at </B> a <B> pH </B> of at least <B> 7, </B> preferably of at least <B> 8. </B>

Such <B> pH </B> are obtained by <B> </B> the use of alkaline compounds such as alkali metal hydroxides.

The solutions or dispersions used are aqueous.

Besides the pigments or dyes, the solutions or dispersions comprise various surfactants, which are preferably anionic or nonionic. For example, it is possible to use ether sulfates of fatty alcohols, optionally alkoxylated (ethoxylated and / or propoxylated), optionally alkoxylated phosphoric acid esters, mono- and dialkylsulfosuccinates, polyalkoxylated fatty alcohols, lignosulfonates. , the condensation products of formaidehyde and aromatic sulfonic acids (naphthalene sulfonic acid for example), etc.

It is also possible to use, as additives to dye baths, colloids such as polysulfonates, polycarboxylates (polyacrylate, acrylic acid / maleic acid copolymer), polyvinylsulfonates, alginates, polysaccharides, cellulose derivatives. The role of these surfactants and colloids is to stabilize the dispersion but also to prevent impurities from precipitating or agglomerating in the bath. The solutions or dispersions can also comprise terpene compounds. They are preferably of the nonionic type.

The use of terpene compounds as defined above is very advantageous in the context of the dyeing steps. In fact, they have very little or no foaming or even defoaming, even under dyeing conditions, in which the shear is very high. Thus, the use of the aforementioned terpene compounds no longer makes the presence of large amounts of antifoaming agent necessary. <B> It </B> may even be possible to dispense with the use of such agents.

The content of these terpene compounds advantageously varies between <B> 1 </B> and <B> 5 g / 1. </B>

The actual dyeing operations are carried out in a conventional manner, and more particularly in a closed loop (jet type, in üigger cassette.

They can be carried out continuously, or discontinuously, preferably.

The dyeing is generally carried out <B> at </B> hot, that is to say <B> at </B> temperatures between <B> 50 </B> and 90 ° C. Higher temperatures are possible if the operation is carried out under pressure.

In continuous processes, the textile fibers are first impregnated in the dye bath and then passed through rollers to remove excess bath. The fibers can go through several passes before seeing their dyes fixed. It is more particularly during the impregnation steps that one finds oneself in the presence of significant shearing conditions, which are the cause of the appearance of foam. In batch processes implemented in a cassette (jigger), the fabric is unwound from one cassette <B> to </B> the other with, in the meantime, immersion in the bath. In this case, the agitation is average. As a result, the levels of foam created are also average. However, it can happen that the foam settles on the textile fibers and is the cause of the appearance of stains.

In batch type jet processes, the appearance of foam is very important. Indeed, the fabric is driven by water jets. However, under these conditions where centrifugal pumps are used, the shear is very high and the stirring is very strong. Conventional, mandatory anti-foam agents can be destabilized and cause deposition of said agent on the fabric, resulting in the appearance of stains.

Once the impregnations have been carried out, the dyes are fixed on the textile fibers under the action of heat.

When the textile fibers are dyed, a finishing step can be carried out, with the aim of giving the textiles particular properties according to the end use for which they are intended.

Thus, textile fibers can be treated with softeners (anionic, cationic, silicone), agents making the fabric more or less stiff (resins), anti-stain agents (fluorocarbons), agents making it possible to transform the appearance of the fabric. fabric (polyurethanes on which flocs can be applied in order to obtain a velvet appearance, for example).

Claims (1)

<B> CLAIMS </B> <B> 1. </B> A method of treating textile fibers comprising at least one of the following steps <B>: </B> (a) roasting, <B> (b ) </B> desizing, (c) cleaning, <B> (d) </B> bleaching, (e) mercerization, (f) dyeing steps, <B> (g) </B> finishing, characterized in which is implemented in at least one of the aforementioned steps, a compound of formula <B> (1) </B> Zi -X <B> - </B> [CH (R <B> 3) - </B> CH (R) -Oln <B> - A; </B> Formula in which: <B> - </B> Zi represents a bicyclo [a, b, c] heptenyl or bicyclo radical [a, b, c] heptyl, optionally substituted by at least one C 1 -C 6 alkyl radical, preferably methyl, a, <B> b </B> and c being such that a + <B> b + </ B> c <B≥ 5, </B> a <B≥ </B> 2, <B> 3 </B> or 4, * b = <B> 1 </B> ou2, * c = 00U <B> 1, </B> and comprising a backbone chosen from those indicated below (Zl <B> to </B> Z7), as well as from their corresponding heptyl without double bond <B>: </B>

<B> - </B> X represents -CH2-C (Rl) (R2) -O- <B> OR </B> -0-CH (Rl) -CH (R'2) -O- in which : R1 and R2, identical or different, represent hydrogen or a hydrocarbon radical, saturated or not, linear, branched or cyclic, in C1-C6, RI and R'2, identical or different, represent hydrogen or a radical hydrocarbon-based, saturated or not, linear, branched or cyclic, C1-C22, <B> 3 </B> 4 <B> - </B> R and R #, which may be identical or different, represent a hydrogen atom or a linear or branched (cyclo) alkyl or (cyclo) alkenyl group in C1-C22, <B> - </B> n is an average value between <B> 1 </B> and 200 <B> - A </ B> represents a hydrogen atom, a C1-C6 alkyl radical, an aryl or alkylaryl radical, a halogen atom, a -CH2-CH (OH) R 5 # group where R, 5 represents a linear alkyl radical or branched or cyclic in C1-C22 or aryl, or a group selected from -S03M, -OP03 (M) 2, - (CH2) ,, - COOM, - (CH2) b-SO3M <B>, </B> with a and <B> there </B> going from <B> 1 </B> <B> to 6, </ B> M representing H, Na, K, Li, N (R4) 1 where the radicals R, identical or different, represent a hydrogen atom or a linear or branched or cyclic C1-C22 alkyl radical optionally hydroxylated, or the mixture of these compounds. 2. Method according to the preceding claim, characterized in that one uses a compound of formula <B> (1) </B> in which the radical Zi is preferably attached to the rest of the chain via any one of its carbon atoms numbered <B> 1 to 6, </B> and more particularly through carbon atoms <B> 1, 5 </B> and <B> 6. </ B> <B> 3. </B> Process according to any one of the preceding claims, characterized in that the compound is such that in the formula <B> (1), </B> the radical Z is by two C 1 -C 6 <B>, </B> alkyl groups on at least one of its carbon atoms, more particularly, on the carbon atom <B> 7. </B> 4. Process according to any one of the preceding claims, characterized in that a <B> compound </B> of formula <B> (1) </B> is used in which X represents -CH2-C (Rl) (R2 ) -O- and the Zi radicals correspond to the Z3 <B> to </B> Z7 radicals, preferably to the Z4 and Z5 radicals. <B> 5. </B> Process according to any one of the preceding claims, characterized in that a compound of formula <B> (1) </B> is used in which X represents -0 -CH (R'l) -CH (R'2) -O-, the radical Zi corresponds to the radical Z3 not comprising ethylenic unsaturation. <B> 6. </B> Process according to the preceding claim, characterized in that the compound is such that in the formula <B> (1), </B> the radical Z is substituted by a C1- alkyl radical C6, preferably a methyl radical on carbon 2 or <B> 5 </B> of the bicycle. <B> 7. </B> Process according to any one of the preceding claims, characterized in that a mixture of compounds of formula <B> (1) </B> is used in which at least l 'one of them is such that the grouping [CH (R <B> 3) - </B> CH (R 4) <B> -0] </B> corresponds <B> to </B> the following sequence: <B> - </B> [CH (R <B> 3) - </B> CH (R 4) -Olp - [CH2 <B> - </B> CH2 -Olq - [CH ( R <B> 3) _ </B> CH (R 4) -O] r- sequence in which R <B> 3 </B> or R 4 is different from hydrogen and n <B≥ </ B > p + <B> q + </B> r. <B> 8. </B> Process according to any one of the preceding claims, characterized in that the compound of formula <B> (1) </B> is used during the dyeing steps (e ). <B> 9. </B> Process according to any one of the preceding claims, characterized in that the compound of formula <B> (1) </B> is used with a concentration between <B > 1 </B> and <B> 5 </B> g / l.