EP1087038A1 - Process for dyeing oxide layers on aluminum - Google Patents

Abstract

Production of colored oxide layers on aluminum or aluminum alloys comprises using a water-soluble anionic dye that is capable of forming a nickel complex with nickel ions and cold compressing using a compressing agent containing nickel ions and fluoride ions. Preferred Features: Compression is carried out in two stages: cold compressing using the compressing agent and then hot compressing using water. The dye is a sulfonic group-containing dye which contains a salicylic acid group optionally in salt form. The compressing agent is in the form of a preparation containing the compressing agent.

Description

Structures, objects or parts made of aluminum or aluminum alloys with a protective Oxide layer are provided, in particular one generated by electroplating by anodization Oxide layer, are now increasingly used in engineering and construction, e.g. as a component or / and for decorating buildings, means of transport or transportation, or for use or Works of art. For the aesthetic design of such structures, objects or parts, these or their oxide layers, often colored. It is therefore desirable that the colored layers be theirs Maintain colored design for as long as possible and consequently against the highest possible fastness environmental influences, especially against the effects of sunlight.

Dyes are used for coloring oxide layers on aluminum or aluminum alloys known different shades, and the oxide layers colored with it can on usual Compacted, e.g. with hot water. The available colors can but have very different light fastness, especially after prolonged exposure to the sun, so that - especially with multicolored objects - the least lightfast coloring Overall impression of the colored object affected. So it is desirable to get better colorings Achieve lightfastness and also the lightfastness of different colorings on an overall to bring a higher level, i.e. e.g. Dyeing with dyes that have weaker light fastness per se with regard to light fastness to bring to the level of such colorations that with Dyes are available which result in very high light fastness. By compression with certain compaction agents, e.g. nickel-based at cooking temperature, in some cases a certain improvement in light fastness can be achieved, but in many cases this is still the case is insufficient, especially for objects that are intended for exterior architecture, that is, for very are exposed to the sun for a long time.

It has now surprisingly been found that the light fastness of a number of dyes available stains can be increased very much if the stained with these dyes Layers of aluminum oxide with a specific compacting agent preparation (B) as described below be compacted cold.

The invention relates to the process for producing the colored oxide layers, the corresponding Light fastness improvers and the substrates thus colored.

A first subject of the invention is therefore a process for the production of colored oxide layers on aluminum or aluminum alloys by dyeing in an aqueous dye bath, rinsing with water and compression, which is characterized in that at least one water-soluble anionic dye (A) is used for dyeing, which is in itself capable of forming a nickel complex with nickel ions, and is compacted cold for compacting with at least one nickel compound Ni ²⁺ and fluoride ions F ^- containing compacting agent preparation (B).

The dyes (A) which can be used according to the invention generally belong to the series of those which are for the coloring of aluminum oxide layers are known or can be used therefor. They are anionic and preferably have at least one sulfo group in the molecule. They are capable of using nickel (II) ions To form complexes, especially labile nickel complexes. The dyes contain accordingly (A) advantageously suitable available electron pairs in suitable orbital configurations and / or Heteroatoms, especially those with combinations of substituents and / or components Ligand character occur. M.a.W. are advantageous in (A) substituent and / or component combinations contain with ligand character, with nickel ions to form unstable Ni complexes are capable. Such configurations are e.g. by combining appropriate metallizable Given substituents which can bind the nickel ion unstably, e.g. a hydroxy group and a vicinal carboxy group, as in salicylic acid, or heteroatomic in copper complexes Molecular parts, especially nitrogen atoms as ring members of a heterocycle, which participate in the copper complex formation are not or only partially involved, e.g. in copper phthalocyanine complexes (especially copper complexes), and / or the one in copper complexes of monoazo dyes Coupling component of the oxyquinoline or pyrazolone series contain as azo component. The Salicylic acid groups are in particular those which are in the meta position and / or para position to the carboxy group, preferably via at least one heteroatomic bridge link to the remaining part of the Dye molecule are bound. Examples of suitable dyes (A) are: Phthalocyanine copper complexes containing sulfo groups, sulfo-containing sulfo groups containing salicylic acid groups Mono- and disazo dyes, sulfo groups containing salicylic acid groups on the Azo group complexed metal complexes of monoazo dyes (e.g. 1: 1 Cu, 1: 1 or 1: 2 Cr, 1: 2 co-complexes), and sulfo-containing 1: 1 metal complexes, especially copper complexes, of Monoazo dyes as a coupling component of the oxyquinoline or pyrazolone series Azo component included.

worin

X

Wasserstoff oder eine Bindung zu FC,

m

1 oder 2,

n

eine Zahl von 1 bis zu zweimal die Gesamtzahl aromatischer Ringe im Molekül,

M

Wasserstoff oder ein nicht-chromophores Kation und

FC

den (m+n)-wertigen restlichen chromophoren Teil des Farbstoffes bedeuten,

worin R

C_1-4-Alkyl,

M

Wasserstoff oder ein nicht-chromophores Kation,

n

eine Zahl von 1 bis zu zweimal die Gesamtzahl aromatischer Ringe im Molekül und

DK

den Rest einer Diazokomponente

bedeuten, und der Ring B gegebenenfalls weitersubstituiert sein kann z.B. mit C_1-4-Alkyl, und

worin

M

Wasserstoff oder ein nicht-chromophores Kation,

n

eine Zahl von 1 bis zu zweimal die Gesamtzahl aromatischer Ringe im Molekül und

DK

den Rest einer Diazokomponente

bedeuten. eg those of the general formulas

wherein

X

Hydrogen or a bond to FC,

m

1 or 2,

n

a number from 1 to twice the total number of aromatic rings in the molecule,

M

Hydrogen or a non-chromophoric cation and

FC

mean the (m + n) -valent remaining chromophoric part of the dye,

where R

C _1-4 alkyl,

M

Hydrogen or a non-chromophoric cation,

n

a number from 1 to twice the total number of aromatic rings in the molecule and

DK

the rest of a diazo component

mean, and the ring B may optionally be further substituted, for example with C _1-4 alkyl, and

wherein

M

Hydrogen or a non-chromophoric cation,

n

a number from 1 to twice the total number of aromatic rings in the molecule and

DK

the rest of a diazo component

mean.

Other dyes (A) of the 1: 1 copper complex series containing sulfo groups can be used in the invention Procedures can also be used. In contrast, such are less suitable or not suitable Dyes that contain conjugated carbonyl groups and do not contain salicylic acid groups (e.g. Anthraquinone dyes), or 1: 2 metal complexes that do not contain salicylic acid groups. As a) especially those dyes come into question, which are colored on anodized aluminum and with boiling water compressed, colorations result, which one according to ISO regulation No. 105 B02 (USA) (by dry exposure with standard light exposure in an Atlas Weather-O-meter Ci 35 A) have certain light fastness <7, especially those whose boiling water coloration condensed have such a certain light fastness <6. Such dyes come in particular Consider, the colorations on anodized aluminum with a nickel compound hot, in particular at temperatures> 80 ° C, compressed, lightfastness according to ISO regulation No. 105 B02 (USA) <7 or <8.

The anionic dyes (A) can be in the form of the free acids or preferably in the form of water soluble salts, e.g. as alkali metal, alkaline earth metal and / or ammonium salts, especially as described below for M.

M can represent hydrogen or a non-chromophoric cation. If there are several anionic groups in the molecule, the respective M may have the same or different meanings. Hydrogen as an ion exists as a hydronium ion. Examples of suitable non-chromophoric cations are alkali metal cations, ammonium cations and alkaline earth metal cations. Calcium and magnesium, for example, are mentioned as alkaline earth metal cations. Unsubstituted ammonium or also ammonium ions of low molecular weight amines can be mentioned as ammonium cations, primarily mono-, di- or tri-C _1-2 -alkyl- and / or -β-hydroxy-C _2-3 -alkyl-ammonium, for example mono-, Di- or tri-isopropanol ammonium, mono-, di- or triethanolammonium, N-methyl-N-ethanol ammonium. Suitable alkali metal cations are customary such cations, for example lithium, sodium and / or potassium ions. Among the cations mentioned, the alkali metal cations and ammonium cations are preferred. According to one embodiment of the invention, part of the symbols M and Kat ^{+ stands} for hydrogen and the rest of them for alkali metal and / or ammonium cations.

The oxide layers to be colored are in particular artificially produced oxide layers on aluminum or aluminum alloys.

Aluminum alloys are primarily those in which the aluminum content predominates, especially alloys with magnesium, silicon, zinc and / or copper, e.g. Al / Mg, Al / Si, Al / Mg / Si, Al / Zn / Mg, Al / Cu / Mg and Al / Zn / Mg / Cu, preferably those in which the aluminum content accounts for at least 90 percent by weight; the magnesium content is preferably ≤ 6 percent by weight; the silicon content is preferably ≤ 6 percent by weight; the zinc content is preferably ≤ 10 percent by weight; the copper content is advantageously ≤ 2 percent by weight, preferably ≤ 0.2 percent by weight.

The oxide layers formed on the metallic aluminum or on the aluminum alloys can have been produced by chemical oxidation or preferably by galvanic means by anodic oxidation. The anodic oxidation of the aluminum or the aluminum alloy to passivate and form a porous layer can be carried out according to known methods, using direct current and / or alternating current, and using suitable electrolyte baths, for example with the addition of sulfuric acid, oxalic acid, chromic acid, citric acid or combinations of oxalic acid and chromic acid or sulfuric acid and oxalic acid. Such anodizing processes are known in the art, for example the GS process (direct current; sulfuric acid), the GSX process (direct current; sulfuric acid with the addition of oxalic acid), the GX process (direct current; oxalic acid), the GX process with the addition of Chromic acid, the WX process (alternating current; oxalic acid), the WX-GX process (oxalic acid; first alternating current then direct current), the WS process (alternating current; sulfuric acid) and the chromic acid process (direct current; chromic acid). The current voltages are, for example, in the range from 5 to 80 volts, preferably 8 to 50 volts; the temperatures are, for example, in the range from 5 to 50 ° C .; the current density at the anode is, for example, in the range from 0.3 to 5 A / dm ² , preferably 0.5 to 4 A / dm ² , with current densities 2 2 A / dm ² generally being suitable for forming a porous oxide layer produce; at higher voltages and current densities, e.g. in the range from 100 to 150 volts and ≥ 2 A / dm ² , especially 2 to 3 A / dm ² , and at temperatures up to 80 ° C, particularly hard and fine-pore oxide layers can be generated, e.g. "Ematal" process with oxalic acid in the presence of titanium and zirconium salts. In the production of oxide layers, which are subsequently colored electrolytically or directly by adsorption using a dye of the formula (I), the current voltage is in the range from 12 to 20 volts in accordance with a preferred method which is conventional in practice; the current density is preferably 1 to 2 A / dm ² . These anodizing processes are generally known in the art and are also described in detail in the specialist literature, for example in Ullmann's "Encyclopedia of Technical Chemistry", 4th edition, volume 12, pages 196 to 198, or in the Sandoz brochures "Sanodal®" (Sandoz AG, Basel, Switzerland, Publication No. 9083.00.89) or "Guide for the Adsorptive Coloring of Anodized Aluminum" (Sandoz, Publication No. 9122.00.80). The layer thickness of the porous oxide layer is advantageously in the range from 5 to 35 μm, preferably 20 to 30 μm, particularly 20 to 25 μm. In the case of color anodization, the thickness of the oxide layer is, for example, values in the range from 5 to 60 μm, preferably 10 to 40 μm. If the anodized aluminum or anodized aluminum alloy has been stored for a short time (e.g. 1 week or less) before coloring, it is advantageous to wet and / or activate the substrate before coloring, for example by treatment with a non-reducing, aqueous mineral acid, for example with sulfuric acid or nitric acid. If desired, the oxide layer - analogous to the known "Sandalor®" process - can first be pre-colored electrolytically, for example in a bronze color, and then over-colored with a dye (A); in this way, particularly muted colors are available, which are particularly suitable for use in exterior architecture, for example. It is also possible to over-dye pre-colored oxide layers with a dye (A) by color anodization (using the process known as integral dyeing); muted colors are also available in this way, which are particularly suitable for exterior architecture, for example.

To dye the oxide layer with the anionic dyes (A), conventional dyeing methods can be used are used, in particular adsorption methods (essentially without voltage), the dye solution e.g. can be applied to the oxide surface, for example by spraying or by application with a roller (depending on the shape of the substrate), or preferably by immersing the object to be dyed in a dyebath. According to one embodiment of the Staining method according to the invention can the anodized metal objects after the anodic Treatment and rinsing in the same vessel in which the anodization took place with the Dye bath can be treated, or, according to a further embodiment, can be dyed Items are removed from the vessel after anodic treatment and rinsing and either directly or after drying and a possible intermediate storage, in one second plant, where recommended if the items have been stored activation (e.g. by a short treatment with sulfuric acid or Nitric acid). It should be noted that temporary storage - if any done - preferably for a limited, short time, e.g. less than 1 week, especially ≤ 2 days. According to generally preferred methods, immediately after anodization and then rinsed colored.

The dyeing is advantageously carried out at temperatures below the boiling point of the liquor, advantageously at Temperatures in the range of 15 to 80 ° C, preferably in the range of 15 to 70 ° C, particularly preferably 20 to 60 ° C. The pH of the dyeing liquor is, for example, clearly acidic to weak basic range, for example in the pH range from 3 to 8, weakly acidic to almost neutral Conditions are preferred, especially in the pH range from 4 to 6. The dye concentration and the dyeing time can vary greatly depending on the substrate and the desired dyeing effect. It dye concentrations in the range from 0.01 to 20 g / l, advantageously 0.1 to, are suitable, for example 10 g / l, in particular 0.2 to 2 g / l. The dyeing time can range, for example, from 30 seconds to 1 hour, advantageously 1 to 60 minutes, preferably 5 to 40 minutes.

The dyeings thus obtained can now be compressed. Before compacting, the Colorings advantageously rinsed with water.

The densifying agents (B) to be used according to the invention advantageously contain the nickel ions and the fluoride ions in the form of nickel fluoride. If desired, the nickel fluoride can be prepared by reacting nickel acetate and an alkali metal fluoride (advantageously sodium fluoride), or (B) can consist of nickel fluoride or a mixture of nickel acetate and sodium fluoride or, in a preferred variant, (B) consists of nickel fluoride in a mixture with nickel acetate and sodium fluoride, nickel fluoride advantageously making up at least 50% by weight of the mixture, preferably at least 70% by weight, for example 70 to 95% by weight, particularly preferably at least 80% by weight; in the mixture of the Ni ²⁺ and Na ⁺ ions, the proportion of Ni ²⁺ ions is advantageously at least 50 mol%, preferably at least 70 mol%, for example 3 to 15 mol%; in the mixture of the acetate ions and fluoride ions, the proportion of fluoride ions is advantageously at least 50 mol%, preferably at least 70 mol%, for example 3 to 15 mol%. If desired, (B), for example, substrate and / or color-related compression aids, for example cobalt compounds, can be present in small proportions, for example up to 10% by weight of (B), for example 0.1 to 5% by weight of (B ). The densifying agents (B) are advantageously used in the form of (B) -containing preparations (B _P ), which can be, for example, aqueous solutions of (B) or mixtures of (B) with other auxiliaries, in particular with anionic surfactants (T), or also aqueous solutions of such mixtures. Suitable anionic surfactants (T) are known substances, in particular sulfo-containing surfactants, preferably condensation products of aromatics containing sulfo groups with formaldehyde, for example condensation products of sulfonated naphthalene and / or sulfonated phenols (which may optionally be further substituted, for example with methyl) with formaldehyde to form oligomeric condensation products surfactant character. The weight ratio of (T) to (B) is advantageously in the range from 0.1 to 20% by weight, preferably 0.2 to 15% by weight. If aqueous solutions of (B) or of mixtures of (B) and (T) are used as (Bp), the (B) content is advantageously in the range from 2 to 40, preferably 4 to 25,% by weight of the aqueous concentrated preparation. If (B) or (B _P ) is used as the dry product (eg with ≤ 10 wt .-% water content), it is advantageous to use this for easier dosing and addition or dosing with water to form an aqueous concentrated preparation formulate the concentrations given above.

Cold compression with (B) or (Bp) can take place, for example, at temperatures below 40 ° C., for example in the range from 18 to 35 ° C., preferably 20 to 30 ° C. The Ni ²⁺ concentration in the compression bath is advantageously in the range from 0.05 to 10 g / l, preferably in the range from 0.1 to 5 g / l. The pH of the compression bath is, for example, in the acidic to weakly basic range, advantageously in the pH range from 4.5 to 8. The duration of the compression can advantageously depend on the layer thickness and is, for example, 0.4 to 2, preferably 0.6 to 1.2 minutes per µm thickness of the oxide layer of the substrate, advantageously compacting for 5 to 60, preferably 10 to 30 minutes. For the preferred oxide layers of at least 20 .mu.m, preferably 20 to 30 .mu.m thick, usually 20 to 25 .mu.m, particularly suitable for exterior architecture components, compression times of 10 to 30 minutes, for example 20 minutes, are already suitable.

After the cold compression with (B), it is advantageous to carry out subsequent compression with water. That is, it is advantageous to carry out a two-stage compression, in which in the first stage with at least a compression agent (B) is cold compressed as described, and in the second stage with water is densified hot. The second stage of two-stage compression, i.e. the heat treatment with Water, advantageously takes place in the temperature range from 80 ° C. to boiling temperature, preferably at 90 up to 100 ° C, or also with steam at temperatures from 95 to 150 ° C, if necessary under pressure, e.g. at an overpressure in the range of 1 to 4 bar. The duration of the post-compression with water is for example in the range of 15 to 60 minutes.

According to the method of the invention, the lightfastness of the dyeings is surprisingly high achievable, and in particular, even for exterior architecture purposes, such dyes are used, which would otherwise not be suitable because of their insufficient light fastness. So the method according to the invention is in particular one in which dyes can be used, with which colors are available, their light fastness otherwise if they are only hot with water are compressed, are lower than those of the dyeings which are compressed according to the invention, where such dyes can be used in particular, the colorations of which are hot only with water are condensed to be 2 or more light fastness notes lower.

The light fastness can be determined according to ISO regulations, e.g. according to ISO regulation No. 2135-1984, by dry exposing a sample in exposure cycles of 200 hours of standard light exposure in an Atlas-Wcather-O-meter 65 WRC, which is equipped with a xenon arc lamp , or according to ISO regulation No. 105 B02 (USA) by dry exposure of a sample in exposure cycles of 100 hours of standard light exposure in an Atlas Weather-O-meter Ci 35 A, which is provided with a xenon arc lamp, and comparison of the exposed samples with a grading pattern e.g. the light fastness grade = 6 of the blue scale (corresponding to approx. grade 3 according to the gray scale), or directly with the blue scale grade 6 grade. If a light fastness value corresponding to grade 6 according to the blue scale is only achieved after 2 exposure cycles, the pattern is marked as rated with a light fastness rating = 7; if this point is reached only after 4 cycles, the sample is given an authenticity rating of 8, and so on, as set out in Table 2 below. Exposure cycle Exposure time Lightfastness grade 65 WRC Ci 35 A 1 200 hours 100 hours 6 2 400 hours 200 hours 7 4th 800 hours 400 hours 8th 8th 1600 hours 800 hours 9 16 3200 hours 1600 hours 10

Conversely, the sample can be compared to the blue scale after a certain exposure time and will be graded accordingly.

In the following examples, parts are parts by weight and percentages are percentages by weight; the Temperatures are given in degrees Celsius; the dyes are used in a commercially available form.

example 1

als Natriumsalz, in 1000 Teilen entionisiertem Wasser, dessen pH mit Essigsäure und Natriumacetat auf 5,5 eingestellt ist. Das gefärbte Blech wird mit Wasser gespült und dann in zwei Teile geteilt.A degreased and deoxidized sheet made of pure aluminum is in an aqueous solution containing 18-22 parts of sulfuric acid and 1.2-7.5 parts of aluminum sulfate in 100 parts, at a temperature of 18 to 20 ° C, at a voltage of 15 to 16 volts with direct current with a density of 1.5 A / dm ² , anodized for 40-50 minutes. An oxide layer of approximately 20-24 μm thick is formed. After rinsing with water, the anodized aluminum sheet is colored for 40 minutes at 60 ° C. in a solution consisting of 0.5 part of the dye of the formula

as sodium salt, in 1000 parts of deionized water, the pH of which is adjusted to 5.5 with acetic acid and sodium acetate. The colored sheet is rinsed with water and then divided into two parts.

One part is compacted for 40-50 minutes at 98 to 100 ° C in deionized water. The after of ISO regulation No. 105 B02 (USA) (by dry exposure with standard light exposure in one Atlas Weather-O-meter Ci 35 A) certain light fastness according to blue scale is 3 (after 100 Hours)

The other part is compressed for 20 minutes at 28 to 30 ° C in a 2% NiF ₂ solution in deionized water and then post-compressed in boiling deionized water for 30 minutes. The lightfastness according to the blue scale, determined according to ISO regulation No. 105 B02 (USA) (by dry exposure with standard light exposure in an Atlas Weather-O-meter Ci 35 A) is 7 ("first brake" after 200 hours)

Example 2

als Natriumsalz, verwendet wird. Das gefärbte Blech wird mit Wasser gespült und dann in zwei Teile geteilt.The procedure is as in Example 1, with the difference that instead of the dye of the formula (1), 1 part of the dye of the formula

is used as the sodium salt. The colored sheet is rinsed with water and then divided into two parts.

One part is compacted for 40-50 minutes at 98 to 100 ° C in deionized water. The after of ISO regulation No. 105 B02 (USA) (by dry exposure with standard light exposure in one Atlas Weather-O-meter Ci 35 A) certain light fastness according to blue scale is 5-6 (after 100 Hours)

The other part is compressed for 20 minutes at 28 to 30 ° C in a 2% NiF ₂ solution in deionized water and then post-compressed in boiling deionized water for 30 minutes. The lightfastness according to the blue scale, determined according to ISO regulation No. 105 B02 (USA) (by dry exposure with standard light exposure in an Atlas Weather-O-meter Ci 35 A) is 7 ("first brake" after 200 hours)

Example 3

als Natriumsalz eingesetzt werden. Das gefärbte Blech wird mit Wasser gespült und dann in zwei Teile geteilt.The procedure is as in Example 1, with the difference that, instead of the dye of the formula (1), 0.3 part of the dye of the formula

can be used as sodium salt. The colored sheet is rinsed with water and then divided into two parts.

One part is compacted for 40-50 minutes at 98 to 100 ° C in deionized water. The after of ISO regulation No. 105 B02 (USA) (by dry exposure with standard light exposure in one Atlas Weather-O-meter Ci 35 A) certain light fastness according to blue scale is 4-5 (after 100 Hours)

The other part is compressed for 20 minutes at 28 to 30 ° C in a 2% NiF ₂ solution in deionized water and then post-compressed in boiling deionized water for 30 minutes. The lightfastness according to the blue scale, determined according to ISO regulation No. 105 B02 (USA) (by dry exposure with standard light exposure in an Atlas Weather-O-meter Ci 35 A) is 9 ("first brake" after 800 hours)

Claims (11)

A process for the production of colored oxide layers on aluminum or aluminum alloys by dyeing in an aqueous dye bath, rinsing with water and compression, characterized in that at least one water-soluble anionic dye (A) is used for dyeing which is capable of forming a nickel complex with nickel ions , and for compacting with at least one nickel ion Ni ²⁺ and fluoride ion F ^- containing compacting agent (B) is cold compacted. A method according to claim 1, characterized in that a two-stage for compression Compaction is carried out, wherein in the first stage with at least one densifying agent (B) is compacted cold and hot compressed in the second stage with water. A method according to claim 1 or 2, characterized in that the dyes (A) are those with which are produced on the oxide layers, the light fastness after a Hot compression with water or with a nickel compound, according to the ISO regulation No. 105 B02 (USA) determined, corresponds to a light fastness rating below 7. Method according to one of claims 1 to 3, characterized in that (A) at least one Has substituent and / or component combination with ligand character. Method according to one of claims 1 to 4, characterized in that the dyes (A) are dyes containing sulfo groups, which may contain at least one salicylic acid group Salt form included. Process according to one of Claims 1 to 5, characterized in that (B) is used in the form of a (B) -containing compacting agent preparation (B _P ) Light fastness improver for dyeings of oxide layers on aluminum or aluminum alloys produced with anionic dyes, which is a cold compacting agent (B) as defined in claim 1 or a preparation (B _P ) thereof as defined in claim 6. Light fastness improver according to claim 7 for with anionic dyes (A) as in Claim 1 or 3-5 defined, generated colorations. The oxide layers colored by the process according to one of claims 1 to 6. Colored oxide layers according to claim 9 with a light fastness corresponding to a light fastness grade according to ISO regulation No. 105 B02 (USA) ≥ 7, preferably ≥ 8. Colored oxide layers according to claim 9 or 10 with a light fastness corresponding to one Light fastness grade according to ISO regulation No. 105 B02 (USA) by at least two grades is higher than an otherwise identical color, but which has been hot-compressed with water.