EP0350803B1 - Process for the pigmentation of leather in a bath - Google Patents

Description

The invention relates to a pigment dyeing process which can be applied to chrome-moist leather (wet blue) or intermediate-dried (crusted) leather and to leather of all animal species.

Pigment dyeings of leather have been known for a long time. The first such dyeings were obtained by rubbing insoluble colored pigment particles (marble dust, soot, clay) into the leather. Pigment dyeings are still of interest today, e.g. Titanium dioxide is used to enhance the tanning of white after retanning or after the leather has dried. Soot is also occasionally used to deepen the shade.

The deficient bond of the pigment to the leather has a disadvantageous effect in the pigment dyeings common today. This results in insufficient fixation and poor wet and dry abrasion values. A leather treated with pigments is usually not completely colored.

The dyeing of leather with soluble dyes also has some disadvantages. Depending on the dye, lower light, sweat or migration fastness values are obtained. Problems with insufficient fastness to wet and / or dry rubbing are also known here.

These disadvantages can be avoided with the pigment coloring described below.

For some years now, there has been a trend towards all types of leather, especially those that are not or barely finished (Clothing leather, furniture leather, full-grain upper leather), to make them more lightfast with the help of pigments. The range should also be improved by covering small scar defects with pigments. However, the pigments used in the leather industry today are characterized, as described, by inadequate binding, unegality and, in part, by unsightliness due to the encrustation of the pigments on the leather surface.

It has now been found that these disadvantages can be avoided by using extremely finely divided pigments. The leather can be dyed through, the lightfastness values of the leather are better than those of the leather dyed with dyes. The fastness to wet and dry rubbing is impeccable, the fastness to migration is good (no migration), the fastness to sweat is excellent, minor grain defects of the leather can be covered, the leather is colored regardless and does not change its grip. The working methods correspond to the usual dyeing methods, so that no major changes in the operational sequence are necessary for the implementation of this method.

enthalten, in welcher

Ar

Benzol der Naphthalin,

X

-CH₂-CH₂- und/oder -CH₂-CH(CH₃)-,

0 bis (m-1)

der Reste A Wasserstoff,

1 bis m

der Reste A Benzoyl und/oder Naphthoyl,

1 bis m

der Reste A -CO-CH=CH-COOM und/oder -CO-CH₂-CH(SO₃M)-COOM sind, wobei M für ein Kation steht,

R¹,R² und R³

Wasserstoff oder Alkyl mit 1 bis 14 C-Atomen,

R

Wasserstoff und/oder Alkyl mit 1 bis 9 C-Atomen,

n

eine Zahl von 1 bis 150 und

m

eine Zahl von 2 bis 12 bedeuten,

und worin das Pigment eine durchschnittliche Korngröße von bis 500, vorzugsweise 80 bis 300 nm aufweist.The invention thus relates to a process for the bath pigmentation of leather, in which the leather is dyed with pigment dispersions which comprise a compound of the formula (I)

included in which

Ar

Benzene the naphthalene,

X

-CH₂-CH₂- and / or -CH₂-CH (CH₃) -,

0 to (m-1)

the radicals A are hydrogen,

1 to m

the residues A benzoyl and / or naphthoyl,

1 to m

the radicals A are -CO-CH = CH-COOM and / or -CO-CH₂-CH (SO₃M) -COOM, where M represents a cation,

R¹, R² and R³

Hydrogen or alkyl having 1 to 14 carbon atoms,

R

Hydrogen and / or alkyl having 1 to 9 carbon atoms,

n

a number from 1 to 150 and

m

represent a number from 2 to 12,

and wherein the pigment has an average grain size of up to 500, preferably 80 to 300 nm.

The compounds mentioned above and the preparation of pigment dispersions with the aid of these compounds are described in DE-A-31 20 697. Preferred compounds of the above formula are those in which R1 is hydrogen, R2 and R3 are hydrogen or alkyl having 1 to 12 carbon atoms, advantageously 1 to 9 carbon atoms, R hydrogen and / or alkyl having 1 to 4 carbon atoms, advantageously hydrogen , n is a number from 2 to 20, suitably 8 to 20, m is a number from 4 to 10, suitably 4 to 8, M is hydrogen, an alkali metal, suitably sodium, an equivalent of alkaline earth metal and / or an ammonium group which can be substituted by lower alkyl and / or lower hydroxyalkyl can be substituted, as well as an ammonium group obtained from ammonia or lower alkylamines by addition of up to 150, advantageously from 5 to 30, ethylene oxide and / or propylene oxide units.

These compounds are prepared by using novolak oxalkylates of the formula I, in which A is hydrogen and Ar, X, R 1, R 2, R 3, R, n and m have the meaning given above, with 1 to m mol of a benzoyl and / or O-acylating compound introducing naphthoyl and treated with 1 to m mol of maleic anhydride and optionally 1 to m mol of sulfite or hydrogen sulfite or 0.5 to 0.5 m mol of disulfite and, if appropriate, neutralizing free acid groups with a base introducing the rest of M.

In addition to the compounds of the formula I mentioned above, the pigment dispersions can also contain lecithin as a further dispersant.

With these dispersants, aqueous pigment dispersions can be prepared in a known manner by the pigments, e.g. Azo pigments, lacquered azo pigments, triphenylmethane pigments, thioindigo pigments, perylene tetracarboxylic acid pigments, dioxazine pigments, quinacridone pigments, phthalocyanine pigments or inorganic pigments with these dispersants with the addition of ethylene glycol, water and, if appropriate, small quantities of other dispersing agents, a dispersing agent, a dispersing agent, for example, a dispersing agent, such as a dispersing agent . The ratio of distribution agents to pigment powder can vary within wide limits and is generally 0.1 to 0.2 parts by weight of dispersant to one part of dry pigment powder. In addition to being a dispersant, the compounds of the formula (I) mentioned can also be used as coupling aids. The amount of lecithin is 0.05 to 0.25% by weight, based on the pigment powder. The dispersions of pigment powder and compounds of the formula 1 were prepared in the presence of water and are obtained in the form of doughs which can be used in this form in the process according to the invention. However, these water-containing dispersions can also be dried. The powder thus obtained is also suitable for dyeing leather in the process according to the invention. The term dispersion here and below includes both the water-based dispersions and the water-free powders.

To prepare for the process according to the invention, the leather is first broached by conventional methods, for example with about 2% conc. Ammonia solution and 0.1 to 2, preferably 0.2 to 0.5% of a wetting agent, based on the dry weight of the leather. Suitable wetting agents for this stage are, for example, polyethylene glycols with a molecular weight of 100 to 2000, preferably from 200 to 1000, esters of the formula R₁-COO- (CH₂) _n -SO₃Na, where R₁ is C₈-C₂₅-, preferably C₁₂-C₁₈-alkyl and n are numbers from 1 to 12, preferably 2 to 5, or ethoxylated fatty alcohols, fatty acids, fatty acid amides, sec. Alkanesulfonates, phenol, naphthol and alkylphenols containing 1 to 100, preferably 3 to 20, oxyethylene units.

After the brochure, the leather is rinsed and placed in a fresh ammoniacal liquor. This is followed by a treatment that serves to introduce substances into the leather that fix the subsequent pigmentation. This treatment is called "pre-fixation" below.

Water-soluble polyurethanes and condensation products of formaldehyde with melamine (molar ratio 3: 1 to 12: 1, preferably 4: 1 to 6: 1), dicyandiamide (molar ratio 1: 1 to 3: 1), urea (molar ratio 1: 1) are suitable for pre-fixing to 3: 1, preferably 1.5: 1 to 2.8: 1), phenol (molar ratio 0.5: 1 to 2: 1), naphthol (molar ratio 0.5: 1 to 2: 1) and aromatic sulfonic acids, preferably naphthalenesulfonic acid (molar ratio 3: 1 to 12: 1, preferably 5: 1 to 8: 1).

Likewise, these condensation products in their sulfonated form are suitable for pre-fixing. The amount of such condensation products is about 0.2 to 4, preferably 1.5 to 2.5%, based on the shaved weight of the leather and about 0.3 to 5, preferably 1 to 3%, based on the dry weight of the leather .

After the pre-fixation, the actual pigment coloring takes place in the same liquor. This step requires the use of substances that allow the pigments to be evenly applied to the leather (leveling agent).

Possible wetting agents are the wetting agents previously described for the brochure and also lecithin and condensation products from protein hydrolyzates with a molecular weight of approximately 100 to 10,000, preferably 300 to 3000 and C₆-C₃₀-, preferably C₈-C₁₈ fatty acids. These leveling agents are used in amounts of 0.1 to 3%, preferably 0.8 to 1.2%, based on the shaved weight of the leather and 0.5 to 2, preferably 0.8 to 1.5, based on the dry weight of the leather used.

In addition to these leveling agents, the liquor also contains the pigment which has been treated with the dispersants described at the outset and in which the pigment is present in an average particle size of 50 to 500, preferably 80 to 300 nm. The amount of pigment dispersion is 0.5 to 3, preferably 1 to 2%, based on both the shaved weight and the dry weight of the leather. In order to avoid uneven pigment coloring due to the pigments being drawn up too quickly, a short liquor (approx. 30 to 300%) and temperatures of 20 to 40 ° C are used.

When selecting the pigments, it is advisable to use only those pigments that have good fat resistance. Trichromatic pigmentation in particular poses a risk of the individual components being drawn up unevenly.

In the case of a planned gloss surge finish, care must also be taken that only pigments are used which have sufficient temperature resistance. This avoids changes in color when glossing. Even if bath pigmented leather is processed untreated in ironing machines with temperatures above 120 ° C, the temperature resistance of the pigments should be checked. This also applies to any vulcanization in shoe manufacture.

The leather thus dyed can then be greased using known methods. After the oiling or immediately after pigment coloring, the pigments are fixed and refixed. Both fixation as Post-fixation is also carried out by treating the leather by known methods with an organic acid, for example with formic acid or acetic acid or glycol formate. The amount of these acids is approximately 2 to 5%, preferably 2 to 4%, based on the shaved weight of the leather or 5 to 8%, preferably 4 to 6%, based on the dry weight of the leather.

It is also possible to subject the leather to additional pigmentation. In this post-pigmentation, only the pigments should be superficially deposited in order to cover the defects in the grain of the leather and thus improve the leather quality. This post-pigmentation is carried out either with conventional coarse-particle pigments or also with the fine-particle pigments, as were previously used for the first pigment coloring.

If the finely divided pigments are used for post-pigmentation, special pretreatment of the leather is required before use (primer). Polyurethanes or polymers that can be polymerized in various proportions from the following monomers are suitable for this pretreatment:
Acrylic acid and its methyl, ethyl, propyl, butyl, hexyl, methylhexyl, octadecyl ester; Methacrylic acid and its methyl, ethyl, propyl, butyl, hexyl, methylhexyl, Ocatdecylester; Acrylamide, acrylonitrile, vinyl acetate, ethylene, styrene, maleic anhydride, maleic acid, maleic acid mono- and diesters, N-vinyl-N-methylacetamide, acrylamidomethylene propyl sulfonate, vinyl formamide, glycidyl methacrylate, diallyldimethylammonium chloride.

The molecular weights of these polymers are in the range from 100 to 10,000, preferably from 150 to 3000. Polymers made from vinyl acetate (50-80%) and ethylene (20-50%) or styrene (30-60%) and maleic anhydride (40-70 %) or hydroxystyrene. The amount of these auxiliaries is 1 to 4, preferably 1.5 to 2.5%, based on the shaved weight of the leather or 1 to 6, preferably 2 to 3%, based on the dry weight of the leather. The actual post-pigmentation is carried out in the same way as the first pigmentation described above with 0.5 to 4, preferably 1.5 to 3% pigment, based on the shaved weight of the leather, or with 1 to 4, preferably 1.5 to 3% on the dry weight of the leather. The same leveling agents are also used in this postpigmentation in the same amount as before in the first pigmentation. After post-pigmentation is fixed and post-fixed, as described above.

The previously described workflow relates to intermediate-dried leather. The brochure is not required for the bath pigmentation of folded leather. Instead, the leather is rinsed, neutralized and rinsed again before the bath pigmentation. After the bath pigmentation, but before any greasing, the leather is retanned. In all processes, it is also possible to additionally dye the leather with soluble dyes by known methods. This can be done before the bath pigmentation, after the bath pigmentation or after the fixation.

example 1

Material:

Zwischengetrocknetes Rindleder (crusted)

Bath pigmentation of furniture leather.

Material:

Intermediate dried cowhide (crusted)

The leathers are finished in the normal way.

Example 2

Material:

Zwischengetrocknetes Rindleder (crusted).

Bath pigmentation of furniture leather.

Material:

Intermediate dried cowhide (crusted).

The leathers are finished in the normal way.

Example 3

Material:

Chromfeuchtes, gefalztes Rindleder (wetblue).

Bath pigmentation of upper leather

Material:

Chrome-dampened, folded cowhide (wet blue).

The leathers are finished in the normal way.

Example 4

Material:

Chromfeuchtes, gefalztes Rindleder (wetblue).

Bath pigmentation of upper leather

Material:

Chrome-dampened, folded cowhide (wet blue).

The leathers are finished in the normal way.

Example 5

Material:

Zwischengetrocknetes, stark synthetisch/vegetabil nachgegerbtes Wildkrokoleder, vorgesehen für eine Glanzstoßzurichtung.

Bath pigmentation of wild crocodile leather

Material:

Intermediate dried, highly synthetic / vegetable retanned wild crocodile leather, intended for a gloss finish.

The leathers are finished in the normal way

Example 6

Material:

crusted Rindleder.

kurz kalt spülen, betriebsüblich fertigstellen.Bath pigmentation of clothing leather

Material:

crusted cowhide.

briefly rinse cold, finish as usual.

I

47 % Pigment Red 112
50 % Pigment Yellow 83
3 % Pigment Blue 15:3

II

40 % Pigment Red 184
50 % Pigment Yellow 83
10 % Pigment Black 7

III

40 % Pigment Red 184
50 % Pigment Yellow 83
10 % Pigment Black 7

IV

100 % Pigment Red 101

V

40 % Pigment Red 184
50 % Pigment Yellow 83
5 % Pigment Blue 15:3
5 % Pigment Black 7

VI

47 % Pigment Red 112
50 % Pigment Yellow 83
3 % Pigment Black 7

VII

66,7 % Pigment Red 101
20 % Pigment Yellow 42
13,3 % Pigment Black 11

VIII

100 % Pigment Brown 1

Die Pigmente bzw. Pigmentmischungen I, II, III, V, VI und VIII enthalten die Pigmente in äußerst feinteiliger Form gemäß der vorliegenden Erfindung; sie sind mit der in Beispiel 3.5.1. der DE-OS 31 20 697 beschriebenen Verbindung behandelt. Die Pigmente und Pigmentmischungen IV bzw. VII enthalten die Pigmente in der üblichen gröberteiligen Form.The following pigments or pigment mixtures were used in Examples 1 to 6:

I.

47% Pigment Red 112
50% Pigment Yellow 83
3% Pigment Blue 15: 3

II

40% Pigment Red 184
50% Pigment Yellow 83
10% pigment black 7

III

40% Pigment Red 184
50% Pigment Yellow 83
10% pigment black 7

IV

100% Pigment Red 101

V

40% Pigment Red 184
50% Pigment Yellow 83
5% Pigment Blue 15: 3
5% pigment black 7

VI

47% Pigment Red 112
50% Pigment Yellow 83
3% pigment black 7

VII

66.7% Pigment Red 101
20% Pigment Yellow 42
13.3% pigment black 11

VIII

100% pigment brown 1

The pigments or pigment mixtures I, II, III, V, VI and VIII contain the pigments in extremely fine-particle form according to the present invention; they are the same as in Example 3.5.1. DE-OS 31 20 697 treated compound. The pigments and pigment mixtures IV and VII contain the pigments in the usual coarser form.

Claims (8)

1. A process for the bath pigmentation of leather, which comprises dyeing the leather with pigment dispersions which contain a compound of the formula (I)

   

   where

   Ar   is benzene or naphthalene,

   X   is -CH₂-CH₂- and/or -CH₂-CH(CH₃)-,

   0 to (m-1)   of the radicals A are hydrogen,

   1 to m   of the radicals A are benzoyl and/or naphthoyl,

   1 to m   of the radicals A are -CO-CH=CH-COOM and/or -CO-CH₂-CH(SO₃M)-COOM, where M is a cation,

   R¹, R² and R³   are hydrogen or alkyl of 1 to 14 carbon atoms,

   R   is hydrogen and/or alkyl of 1 to 9 carbon atoms,

   n   is a number from 1 to 150 and

   m   is a number from 2 to 12,

   and in which the pigment has an average particle size of 50 to 500, preferably 80 to 300, nm.
2. The process as claimed in claim 1, wherein the leather is dyed with pigment dispersions which contain a compound of the formula (I) where

   R¹   is hydrogen,

   R² and R³   are hydrogen or alkyl of 1 to 12 carbon atoms,

   R   is hydrogen and/or alkyl of 1 to 4 carbon atoms,

   n   is a number from 2 to 20,

   m   is a number from 4 to 10,

   M is hydrogen, an alkali metal, one equivalent of an alkaline earth metal and/or an ammonium group which can be substituted by lower alkyl and/or lower hydroxyalkyl, and an ammonium group obtained from ammonia or lower alkylamines by addition of up to 150 ethylene oxide and/or propylene oxide units.
3. The process as claimed in claim 1, wherein the leather is dyed with pigment dispersions which contain a compound of the formula (I) where

   R   is hydrogen,

   M is hydrogen, sodium and/or an ammonium group which can be substituted by lower alkyl and/or hydroxyalkyl, and an ammonium group obtained from ammonia or lower alkylamines by addition of 5 to 30 ethylene oxide and/or propylene oxide units.
4. The process as claimed in claim 1, wherein the leather is dyed with pigment dispersions which contain a compound of the formula (I) where

   Ar   is benzene,

   R² and R³   are hydrogen or alkyl of 1 to 9 carbon atoms,

   n   is a number from 8 to 20 and

   m   is a number from 4 to 8.
5. The process as claimed in claim 1, wherein the leather is dyed with pigment dispersions which contain a compound of the formula (I) where

   Ar   is naphthalene,

   R² and R³   are hydrogen or alkyl of 1 to 9 carbon atoms,

   n   is a number from 8 to 20 and

   m   is a number from 4 to 8.
6. The process as claimed in any one of claims 1 to 5, wherein the leather is dyed with pigment dispersions which contain the pigment in an average particle size of 50 to 500 nm.
7. The process as claimed in any one of claims 1 to 6, wherein the leather is dyed with 0.5 to 2% by weight of the pigment preparation, based on the weight of the leather.
8. The use of pigment dispersions which contain a compound of the formula (I)

   

   where

   Ar   is benzene or naphthalene,

   X   is -CH₂-CH₂- and/or -CH₂-CH(CH₃)-,

   0 to (m-1)   of the radicals A are hydrogen,

   1 to m   of the radicals A are benzoyl and/or naphthoyl,

   1 to m   of the radicals A are -CO-CH=CH-COOM and/or -CO-CH₂-CH(SO₃M)-COOM, where M is a cation,

   R¹, R² and R³   are hydrogen or alkyl of 1 to 14 carbon atoms,

   R   is hydrogen and/or alkyl of 1 to 9 carbon atoms,

   n   is a number from 1 to 150 and

   m   is a number from 2 to 12,

   and in which the pigment has an average particle size of 50 to 500, preferably 80 to 300, nm for the bath pigmentation of leather.