DE1621486A1 - Process for coloring anodically oxidized metals - Google Patents

Description

FOR !! 'WORK OF ANODIC OXIDIZED METALS

The present invention relates to the dyeing of anodic oxidized aluminum and in particular the production of a black one Paint on anodized aluminum.

There are already a number of processes for the production of colored anodically oxidized metals, in particular those colored black Aluminum, known. These processes are generally carried out by two different methods. After, the first can be a dye into the pores of the oxide layer on the surface of a anodized aluminum using one or more dyes from either an aqueous bath or an organic solvent be applied. In the second method, a colored precipitate is formed in the pores of the oxide layer. Such a colored precipitate is often a metal sulfide and is formed in particular by a stoichiometric reaction, wherein a metal ion is absorbed in the pores of the oxide layer of the anodized, oxidized metal and then incorporated therein Sulfide ion is absorbed. -

109818/1592

BATH ORIGINAL

The known methods described above have certain disadvantages. With a few exceptions, the organic ones fade Colorings under the influence of light, oxidation and the like very difficult to get a uniform color in a reasonable time. Because the depth of the hue depends on the relative Depending on the completeness of the diffusion, the cell must often up to '/, Li amount to one hour so that the diffusion can take place, This arises from the fact that niobium is a solid, i. E. the sulphide precipitation, in narrow pores of an anodically oxidized layer forms while the diffusion increases the rate at which the filch of Forms dye, reduces. In view of this, it is difficult an even and deeply colored aluminum through the ordinary stoichlometric reactions proposed so far have been to receive. As far as is known, none is yet economical portable process has been developed that did not show the ones listed above! laughed

Ea has now been found that with the help of a new combination of components using a new type of application in an economical, satisfactory manner, deep black Stains on anodically oxidized yeast call can be produced.

The advantages of the present invention are illustrated by the following description in conjunction with the drawing, which schematically reproduces a process for anodic oxidation and coloring according to the invention, clearly »

109818/1592 bad original

16 * 1486

The present invention relates to a method for producing a color on anodized metal. It is essentially characterized by _f that a porous layer formed on said metal by anodic oxidation is treated with a stable aqueous solution containing a donor for the precipitating ion and an ion of a metal which is capable of forming a colored precipitate with the precipitating ion to form, and then the oxidation layer is heated to a temperature which causes the {[formation of the colored precipitate.

The precipitating ion can be obtained from a compound which is capable of a precipitating ion (e.g. sulfide ion) at temperatures

approximately
above / 93.5 ° 0 and which are stable in aqueous solution at temperatures below about 38 ^{0 O.} In general, the impregnated anodically oxidized surface is heated to a temperature above 121 ⁰ G for at least 1 to 2 minutes, is colored so that the anodically oxidized film. The latency times can be increased as required and basically depend on the temperature. At lower temperatures, longer ones will lead to. higher shorter times are used.

_ ,. The present invention also relates to dyeing the Imc £> impregnating agent in the form of a composition of matter for dyeing

- * anodized metals. She. consists according to the invention from

cr> "■ · - ■ -

fine aqueous solution »which contains metal ions, which with the

Sulfide react a colored ,, insoluble in water sulfide to form at least one j SuIiidionen donor, the OCE in Jlinie -ist-, ,. unto * - the Jleaktio.nsliGdbedingungen an aiiareiohoude

BATH ORIGINAL

To release amount of sulfide ions, which react with the metal ion, a thickening agent in an amount sufficient to give the aqueous solution a viscosity in which it is mixed with the means with which the coloring impregnation on the anodic, oxidized metal is applied, is workable, and one Stabilizers. Additionally, the aqueous solution can contain a finely divided insoluble substance which is referred to herein as a brightener.

In the dyeing method according to the present invention is called the ion that will react with the precipitating sulfide ion can, at least one ion of the metals listed below used: cobalt, copper, antimony, nickel, molybdenum, bison and bismuth .. To ensure a stable black color in the oxide layer Obtain, are preferably cobalt, Mckel or iron ions used. It is still worth noting that this is used in solution Ion not just a simple hydrated ion of one of the

' ^a

may be called metals, but also / complex ion, which contains an ion of the metals mentioned as a constituent. When an iron complex is used, it is necessary that the complex ion is capable of thermal decomposition at a temperature below the temperature to which it is heated. The use of the term "precipitating ion ^11" in this specification and in the claims is not used in the sense that the color formation is a precipitate in the usual manner but not necessarily

must be formed in the presence of water. ^8AD

109818/1592

The Sulfiddonator is preferably a substance which is capable of sulfide ions at iDemperaturen above to give 93.5 ⁰ G and / is stable under 28 ⁰ G in aqueous solution at Temperatureq; sodium ibiosulfate is preferably used as the sulfide donor. The sulfide donor is usually a sulfur-containing substance that is soluble in water to such an extent that at least about 0.1 # sulfur is available for reaction. Suitable sulfide donors are, for. B. Ammonium Tbiosulphate, Potassium | Thiosulfate, thiourea and substituted thioureas except sodium TblOsulfate.

The thickeners which can be used in the process according to the invention comprise a colloidal suspension of boehmite-type aluminum oxide, known under the trade name "Baymal", soluble starches such as Arrowroot Starch., Hydroxy-alkyl geiluloses (ζ. B. Hydroxy-Xtbyleelluloses), polyvinyl alcohol , Polyacrylamide, Meth.ylvinylatb.er copolymerized with maleic anhydride, available under the trade name "Gantrey AN ' ^1. , Polyvinylpyrrolidone and an ethylene oxide polymer, which is under the name" Polyox WSR Resin ". Such thickeners are used in amounts of about 0, 1 to about 20 or even 50 and more parts by weight to 100 parts by weight ₉ parts of water are used i © r required viscosity is necessary, not including the character and amount of each type of ion which SiB present in the Imprägai @ mie @ h.img of the present invention d ₅ to k @ tm @ n ₀ Man

109818/1592

however, will find that there is a lot of thickener in the Weight range, as indicated above, is usually sufficient to achieve the required viscosity.

The use of a stabilizing agent in the dye solutions of the present invention which contain sodium thiosulfate is of great advantage and in some cases important if one wants to be sure that the dye bath will remain stable for equally short periods of time. It is possible that non-stabilized solutions will persist for a measurable period of time without suIfid medication occurring. Such Lösnagen can z. B. used in spray devices in which they are mixed immediately before spraying. In some cases, where the bath does not need to last longer than 15 to 30 minutes, uiaatabilized baths can be used, namely if the impregnation is applied by dipping, rolling or the like, but normally it is extremely advantageous if one Add at least 0.1 Sew .- ^ sodium or potassium bisulfite to the bath as a stabilizing agent. It's even better to have at least $ 0.3 of such a stabilizer

to add to the bath. Formally, more than 1 i> stabilization and more

medium necessary, you can, but up to. 5 Sew .-? £ / use if desired is. In the case of sodium thiosulphate solutions which Containing oupro ion as the only precipitating ion is practically the Presence of at least 0.3% by weight of stabilizing agent required, since such solutions can be destroyed in a very short time by the formation of a song oblage. All of the invention Sodium thiosulphate solutions, with the exception of molybdenum solutions, see

10 0818/1181 ^{BAD 0R! GiNÄL}

to be stable at the pH that is formed by the components of the solution and is normally in the weakly acidic range (e.g. pH four to six), the pH of solutions containing molybdenum must be set to at least 1 present invention containing thiourea appear to be shelf stable for at least a few months without the need to add a stabilizer.

Optionally, which is even of great advantage, a leveling agent (flattening agent) can be added in amounts of up to 50% by weight (based on the weight of the solution, excluding the leveling agent itself). A leveling agent for the purposes of this invention is a finely divided, substantially inert substance such as e.g. B. Sitandioxyd (Pigmeat), Bisenoxydrot, finely ground mica, finely divided, formerly, stabilized Eon and the like. When dipping or spraying is carried out, it is very advantageous to use a leveling agent in an amount within the range given above and expediently in the range from 5 to 20% by weight, well distributed in the mixing solution. The leveling agent improves the evenness of the coating on the metal to be colored and generally improves the workability of the paint solutions.

I ^{1 For} every! Expert it is obvious that the impregnation solution is additional. Ions to balance. which contains the color-generating ions in stoichiometric amounts, so that an electrical equilibrium is established in the aqueous impregnation solution

109818/1592 _8ftD

1b7ΊΑ86

can adjust. These additional ions are usually those that, together with the metal-supplying ions, form a Form water-soluble compounds that are stable in aqueous solution. Where mixtures of different substances are used, it is necessary to avoid ions that do not interact with each other. So you could z. B. cobalt sulfate and lead acetate do not use together in the same aqueous solution, as the equation for this Pail indicates that undesirable, lead sulfate, which is largely insoluble in water, would be formed. Similarly, are too. Salts such as cobalt chloride and Silver sulphate in aqueous solution not stable next to each other.

The parent metal according to the present invention is dyed is generally aluminum, including anodically oxidizable alloys with a content of more than 80 i "of aluminum, but can also be another anodically oxidizable metal, eg. B. titanium. In order to prepare the aluminum for the dyeing process according to the invention it is usually necessary to anodize it anodically so that an anodized layer of a thickness of. at least 0.0025 mm is formed. Pur Baeweeke it is advantageous that the oxide layer is at least about 0.013 mm, e.g. B. 0, 018 ram is strong. Anyone skilled in the art knows that such films formed by anodic oxidation can be produced in the most varied of ways. However, in order to describe the invention in as much detail as possible, the following table I gives the information with which satisfactory anodic oxidations in

have aqueous acidic baths carried out. _SAD original

1098 18/1592

'Ib ^' I486

TABEL

general conditions "preferred conditions

Type d. Electrolytes

Concentration of
Electrolytes

Density of
Anode current

!Temperature

4th to ί 'Ο ^GeW - " ^{O / o} . 15th Weight, .- * 2. 1 to ρ
108 m amp / cm 10 .8 m Amp / cm O. 5 to 90 minutes 40 Minutes -4 ⁰ G b Is 38 ⁰ G 22nd ⁰ G

It should be noted that those listed under the heading "Preferred Conditions" in Table I are the conditions under which a satisfactory oxide layer approximately 0.018 mm thick can be produced on an aluminum alloy known as 6063 and nominally about 0.45 to about 0.90 weight percent magnesium, about 0.2 to 0.6 weight percent silicon, not more than about 0.35 percent by weight iron and of copper, manganese, chromium, zinc and titanium each contain 0.1% per cent in addition to aluminum.As anyone skilled in the art knows, every aluminum alloy requires particularly precisely set conditions for the anodic oxidation within the general range given in Table I. Since it is also possible, equivalent

10 9 8 18/1592 _BAD original

- ro -

To apply coatings in a way other than electrolytic, includes the term "anodically oxidized" as it is used here, also all other processes after which a porous adhesive Surface coating at least about 0.0025 mm thick can be generated that largely equal the Beschichbungen

under
is that with the in the table! / "general conditions"

specified conditions are generated.

When the anodic oxidation has ended, the anodized, oxidized object is rinsed and dried at about room temperature. The thickened solution of the carb impregnation of the present invention is then applied to the anodized surface. Although the thickened solution can be applied in any manner that will produce an evenly distributed moist coating, it has been found that it is particularly advantageous to spray the thickened solution onto the horizontally held surface. It is possible, and sometimes advantageous, to do some things, such as thickening the solution, immediately before and at the same time as spraying. In this case it is possible to use thickeners which, after a certain period of time, become unstable in the ionic solution present. When the freshly anodized surface has been sprayed with the thickened solution, it is immediately thereafter ^{heated to a temperature of about 121 to about 593 0} O for two to sixty minutes. In general, it is advantageous to heat to Elne temperature in the range of about 149-315 ⁰ O, with the greatest degree of control and FlexLbilät is obtained when the heating at temperatures ranging from 177 to 232 ⁰ G

- 1 0 9 81 8/159 2 ' _BAD original

is made. ISs have been found satisfactory to heat to a temperature of about 205 ^Q G for about 15 minutes. The heating may be by means of a furnace, heat flow, or any other heating method known in the art "which does not destroy the treated surface of the anodized metal. In connection with the heat treatment it is to be understood that when it says that the treated surface is heated to a temperature of about 205 ⁰ G 15 min *, this process is carried out so that a hot treated sheet is placed in an oven at a temperature of 205 ⁰ G i 5 ⁰ G. It must be taken into account that upon reaching the furnace temperature of an object by introducing occurs a delay, especially if the surface of the article is moistened with an aqueous -Dösung. Per is pet to take into account that the mass of the introduced into the furnace object determines, in part _r 1st speed at which the Object reaches oven temperature. Accordingly, for the purpose of this description, tempera Doors and ducts are given which refer to treated metal sheets, wherein the furnace or other heating means has a sufficient "capacity to heat a metal sheet without significant loss of temperature. As any Each _man: immediately recognizes the time and temperature ranges can be changed when the conditions or situations others are as described herein above, ifech heating, the pores of the anodically oxidized aluminum and colored-sealing by a

- ■ 1098 18/1 592

•. ■■ '. "■' ■ ': -."■'."'-:. .. ■■ ^; - - ^: -'...;." BATH. 'ORIGINAL

1ÖZU86

Treatment closed, usually, according to ASTM Bye Test Designation B-136-63T - "Resistance of Änodically Coated Aluminum to Staining by Dyes ¹¹ -." In some cases, such as the 1100 alloy, only a partial seal is achieved., '

For further protection against corrosion, the anodic, oxidized and colored aluminum still with polar aliphatic compounds, P varnishes j waxes, boiling water, hot aqueous metal salt baths such as sodium dichromate, nickel acetate, etc. are treated. Treatment with boiling water gives black-colored aluminum a velvety appearance, which in some cases is desirable can be.

In the practical implementation of the invention, the concentration of the various reactants (coloring metal salt and precipitant) and the additives can vary widely. For example, this can be color. giving salt can be used in a concentration of 1 $ to thickening, preferably at about 5 to 15 ° . The sulfide donor can be used in a concentration of $ 1 to saturation, usually about 15 to 30 ⁰ Jo , the stabilizing agent can be used in a concentration of 0.1 to about 3 $ *, preferably about 0.75 to about 1 , 25 i ° can be used. The leveling agent can be added in a concentration of 1 to 50 ^ and above. Usually 2 to 8 % flow agent is sufficient. The concentration of the thickener is determined by the influence of the ions on the viscosity of a colloidal suspension. TJo can be the thickener in some cases

1,098 18/159 2 _ _{; BÄD 0RlGINÄL}

be present in small amounts, in others in such concentrations that a very viscous solution is formed. A particularly favorable concentration range for Bayjnal aluminum oxide is 1 to 10 #, e.g. B. '2 to 4 - #. ~ _; " ^: -

In practicing the invention, it is advantageous. as blackening impregnation listed below

To use aqueous composition: f

Substance *: ' amount in wt .- ^ *

Cobalt chloride hexahydrate; 4 to 15, .- \ Sodium thiosulfate pentahydrate 12 to 30;

Hodium ibisulfate 0.5 to 1.25

Red (Se ₂ O ₅ ) * 2 to 8

»Baymal» "'''' ^m * ^& . T to 4,

Water ^; "" ^r / · / -Rest ' ä

The black coloring is performed, in the impregnating an anodically oxidized AluminiumoberfIache lCobaltenthaltenden with the ingredient and then 15 min. Is heat-treated in a gebaltenä-en 205 ⁰ C oven.

To the person skilled in the ^v the invention enefits better to lead prior Äugen, the following specific examples are given.

s * a / α f> s «- BAD 0BIG5NAL

Bets ρ IeI I

A sheet of aluminum alloy 6063, containing no aluminum about 0.45 to 0,90J ^ magnesium and about 0.20 to 0.60 ° / o silicon, wurde.in a bath consisting of 15% aqueous sulfuric acid at 22 ⁰ G anodically oxidized for sixty minutes, with an oxide film about 0.018 mm thick. The surface-oxidized alloy was then ^{dried in air at room temperature (about 22 0} O) and then sprayed with an impregnation solution of the following composition:

Stock solution. 250 g ITa ₂ S ₂ Q ₃

10 g NaH SO ₃

100 g Op-Ol ₂ ... 6H ₂ O

Spray solution

^{"Mix in a} high-speed mixer 300 ml stock solution 20 g red (Fe ₂ O ₅ ) 100 ml 10 a ß> " Baymal "in water

These substances are put into 700 ml of distilled water and after they are dissolved, is diluted to 1 liter with water.

The impregnated, anodically: oxidized sheet was then in one. Oven heated at 205 ^° C. for about 15 minutes. To. When the excess material was washed away, the anodically oxidized surface was coal black.

109 8 18/1592

BAD ORlGlMAL

A86

This in. this procedure and in the following examples is shown schematically in the accompanying drawing. Under Reference to this should be noted that the two-step process of this invention, the coating with impregnating agent (generally speaking impregnation) and heating includes., the usual anodic oxidation precedes it and any the usual cleaning and pore closing ^ methods.

For example 1 Il ~ .—

The aluminum alloy 6065 is anodized as in Example I. Mn Ilust er äer, .a ■ nQdls.c ■ h ·; Ό.xyÄi ■ erten ^ Iιegi ■ ieΓutι: g '. ■ ^; w ^: ird, ■. ■ - ■ by dipping into an ear solution and pulling it out with a tone of about 7.6 cm per back. impregnated. The solution has the following composition:

100 g Go Gl ₂ . 6ii ₂ O '.._': ■ / '■ -. '.

100 g (HH ₂ ) ₂ GS (thiourea)>

3 1 ° Arrowroot strength / l ^: - ". '

Dissolve the salts listed above in approx. 700 ml 3% aqueous Arrowroot starch solution. If resolved to 1 1 with strength chopping dilute.

Heating the aluminum sheet after impregnation as in Example I.; ^%:: V: ■. :

109818/1592: ΐ: BW OHBIMW.

■ B ei g pl e 1 III - ■

A polished sheet of "aluminum alloy 545?" the non-aluminum about 0.30 $ to 1.20 magnesium, about 0.15 to 0.45 ° f manganese and about 0.20 fo copper, iron and 0.10 $ 0.08 $ contains silicon, was dissolved in a 15 ^ söhwefelBäüre containing aqueous bath of 22 ⁰ O about 40 min. anodically oxidized, whereby an oxide film with a thickness of about 0.013 mm formed. The anodically oxidized alloy

was divided into iswei file, at room temperature at the IUFD getrooknet, behändölt as in Examples I and Il and 15 mini long to 205 ⁰ G erhitato The excess salts were removed "by washing with water was obtained a glossy jet-black surface. ,

A sheet made of the aluminum alloy 6063, which had been anodically oxidized according to Example I, was sprayed with an impregnation solution which had the following composition: stock solution

250 g Ha ₂ S ₂ O ₃ . 5n ₂ O

10 g ITaH SO ₃

50 g Cu Oil

solve the liav> SoÖ "c 5iioS ₉ 0" and Mail SO ^ in about 700 ml iipO.

1098 18 / 1S92

• ^; - ^ - V , u ■ ■ - '. -λζ ^ l . ·,.: ■■■ ■: ■: -; ■; ..;,: ■ "■. BADORIQiNAL ■.

16ZH8B

When dissolved, add Cu Gl and when dissolved, dilute to 1 liter. Spray solution

mix in a high-speed mixer

300 ml stock solution

20 g red (Pe ₂ O ₅ )

200 ml $ 10 "Baymal". '

ITaoh heating and cleaning as described in example I, became a dark green color Ia of the anodic, oxidized layer obtain.

B e i s ρ i e 1 V

A sheet from which aluminum alloy 6063 was made, as in

• Hx & tl fl ·: - v. . - '■ /: ------ -': -

Example Γ described, anodically oxidized and sprayed with an impregnating i nierlösung, which was prepared as follows:

Stock solution ", -." ■ - .. '

250 g Wa ₂ S ₂ O ₃ . 5H ₂ O

10 g flail SO ₅

100 g Cd Cl ₂ . 2-1 / 2 H ₂ O _{Λ; ä>} _ '^ _f _ BADORIG ^ AL

dissolve the salts listed above in approx. 700 ml of distilled

1098 18/1592

Water. If dissolved, dilute to 1 liter with water. Spray solution ,

mix in a high speed mixer
400 ml stock solution
20 g red (Fe ₂ O ₅ )
150 ml of 10 ° / o "Bayraal"

lach, after heating and cleaning as described in Example I, it showed a bright yellow earbe in the. anodically oxidized layer. -

Example YI .

A sheet of aluminum alloy 6063 was made as in Example I. anodically oxidized. The anodized alloy was then with an impregnation solution, as described below was made, sprayed: - .. ^: ''

Stock solution

10 g Mali SQ,

25 g ^ _;

109818/1592

cn rr ( Λ

T S ß Γ;

Γ. V-

A 9 -

dissolve the first two salines in approx Water. If solved * then the third and then the fourth Dissolve salt »Immediately nacir & ^^.

set and dilute to 1 l with water.

Spray solution

mix in a tendon mixer

350 ral Stamra solution 20 g hot (^ e ₂ O ₅ ) 100 ml; 10 ■ ':'&."Bayraal"

Do heating and cleaning,% iö; in example I beschrietjenj showed the anodically oxidized layer is a reddish-brown color.

Further examples j in which anodically oxidized alloys according to of the present invention "are set out in the following Table listed with details of the colors obtained,

Alloy titanium

Al alloy 1100

Al-Legislation 7075

7ll Legislation ₇₀₇₅ ■ -; ■■ -

solution

of Ex. I.

from Ex. IT from Ex. I. vonBeiSp * IT

Heating He.it -. " Par be received ⁰ O 15 min. Black '

205

205 "■ '[■"-'

205 ^: ' ; 8 18/1592

dark green

yellow
BATH

-. =. 10 * 1486

Colored anodically oxidized metal, e.g. ± S. Aluminum produced according to this invention is particularly suitable for building purposes, for building facades and other places that are strongly exposed to sunlight. resistant. _R be used for many other uses may include aluminum which has been colored by the inventive process. So can

z. B. attractive effects are caused by combination of the colorations produced by the present invention with others Metal treatment, such as anodic pre-oxidizing, texturing, partially masking the surface during impregnation with the Mrb solution of the present invention and the like; these .

. Effects can be applied where decorated metal is desired

tinter
will. The inventive

Processes are used to create surfaces

absorb or emit light and thus purposefully bind as well as bring aesthetic effects.

BATH ORIGINAL

109818/1592

Claims (9)

P A T, E -BT IA- Ή S P R ti G Ii S. 1. Method of dyeing anodic. oxidized metal, thereby. marked that. a porous layer formed on the metal by anödische oxidation is treated with a stable aqueous solution _for which a donor for the precipitating ion and an ion containing a metal which is capable of forming a colored precipitate with the precipitating ion, and then the The oxide layer impregnated in this way is heated to a temperature which causes the colored iridescence to merge. 2. go to. Claim 1, characterized in that the. The donor for the precipitating ion is a sulfide and the precipitating ion is a sulfide ion. 3. The method according to claim 2, dadürcb. characterized in that the sulfide donor is sodium ^r ühlosulfat, potassium thio sulfate, ammonium thiosulfate, i'hiourea or a substituted thiourea. V 109818/1592 ■■ - ft - ιχ 4. The method according to claim 1, 2 or 3 » characterized in that the metal ion is a cobalt, copper, antimony, nickel, molybdenum, bis- or bismuth ion, 5. The method according to claim 4 » characterized in that the metal ion is a cobalt, nickel or iron ion. 6. The method according to any one of the preceding claims, characterized in that the stable aqueous solution contains at least 0.1 wt .- $, preferably at least 0 _y 5 wt .- ^, sodium or potassium bisulfite. 7. The method according to any one of the preceding claims, characterized in that the stable aqueous solution contains a leveling agent dispersed, preferably in an amount of up to 50 wt .- ^. 8. The method according to any one of the preceding claims, " characterized in that the porous anodically oxidized, impregnated layer is heated to a temperature above 120 ° 0 for at least 1 minute, preferably to a temperature of about 205 ° for about 15 minutes. 9. Aqueous solution for carrying out the method according to claims 1 to 8, characterized in that it contains at least one. Ion of the metals cobalt, copper, antimony, nickel, molybdenum, iron or bismuth, as sulfide donatur sodium thiosulfate, potassium thiosulfate, - ammonium-'ihiosulfat, .urea or a substituted urea and a thickener 1098 18/159 2 bath original γ ν '- ■ -: * .- ■ ·;:; ■ 162H86 medium, and, if copper ions are the only metallic ions and if sulphate is the sulphide donor, then there is a need for about 3 Gewr- ^ ifattiuni «ode ^ Ea * lium ^ bisulphite ^ Uj? solution contains' · to. Solution according to Inspieueh ■% thereby; jg ^ kenttzeictoetr that they disperse ventilating agent efitttält, in intermittent amounts up to about 50 10 9818/159 2 Blank page