WO1998005806A1

WO1998005806A1 - Electrolytic process for the coloration of anodized aluminium by modification and control of the anodic film transmission colour

Info

Publication number: WO1998005806A1
Application number: PCT/ES1997/000202
Authority: WO
Inventors: Dionisio Rodriguez Martinez
Original assignee: Dionisio Rodriguez Martinez
Priority date: 1996-08-02
Filing date: 1997-07-31
Publication date: 1998-02-12
Also published as: ES2110372B1; ES2110372A1; AU3696597A

Abstract

The disclosed process enables to repeat in an industrial and controllable way the electrolytic coloration of anodized aluminium, by differentiated and independent control of the colorimetric coordinates of the colour, i.e. the saturation, tonality and luminosity. The saturation control is obtained by carrying out the anodizing of aluminium to the prior anodized aluminium, whereby a mass-gel of alumina with high mobility is obtained. Said mass-gel is subjected to a current which causes the formation of micropores in the base of which is formed a mass-gel having a spherical shape and actuating as microlenses. The final colour control is performed by applying a pulsed direct current, the application time being the factor which will mark the colour on the obtained visible spectrum. The control of luminosity is obtained by electrodeposition of metal particles.

Description

ELECTROLYTIC COLORATION PROCEDURE OF

ANODIZED ALUMINUM, BY MODIFICATION AND

MOVIE TRANSMISSION COLOR CONTROL

ANODIC

OBJECT OF THE INVENTION

The object of the present invention relates to an electrolytic system for coloring the previously anodized aluminum, by modifying and controlling the transmission color of the previously produced anodic metal oxide film, which allows millions of colors to be obtained by modifying of the transmission color of the anodic film.

The first and fundamental characteristic of this procedure is based on the fact that it allows to obtain an industrially repetitive and controllable process of the electrolytic coloration of anodized aluminum.

One of the fundamental characteristics of this procedure that have allowed it to be industrially repetitive and controllable lies in the fact of being able to control separately the colorimetric characteristics of any color, such as saturation, hue and luminosity.

Another of the fundamental characteristics of this invention is to have avoided the dependence of this coloring system on the previous anodizing treatments, which prevented the colorimetric coordinates from being controlled afterwards and made the aluminum coloring procedures industrializable. BACKGROUND OF THE INVENTION

It was at the end of the 60s when electrolytic coloration appeared for the first time in Europe, creating a great expectation as to the possibility of obtaining a multitude of perfectly stable colors in aluminum, that is, being able to make colored aluminum. At that time the coloration of the aluminum was justified because when applying an alternating current on previously anodized aluminum, using an electrolyte with metal salts, the following phenomena that led to the coloring of the same occurred:

- In the negative half-cycle of the applied current, with respect to aluminum, metal particles were deposited at the bottom of the pores of the anodic film,

- In the opposite half cycle the metal particles oxidized, producing the color of the corresponding metal oxide.

Based on these considerations, it was thought that with the electrolytic coloration many colors could be obtained, depending on the deposited metal. Unfortunately, it was soon found that with the electrolytic coloration the oxides of the deposited metals were not produced, since all the deposited metals, with the exception of copper, produced a range of somewhat muted yellowish colors, which were called bronze; and that could be darkening, prolonging the duration of the process, until reaching a practically black color.

Copper gave a really more intense range of colors, but its use was not recommended due to possible internal corrosion problems. This discovery ended all the initial expectations that the electrolytic coloration seemed to offer, although due to its light fastness they ensured the continuity in the application of this procedure.

The "Electrolytic coloration system by light transmission" was discovered in 1970, in the Spanish company LONGRAF, in a casual and accidental way, since by doing color tests in the laboratory, by forgetting and accident, an anodized piece was left in a bath of coloration, connected to a transformer and at a low voltage of

AC. After a while, obviously not controlled, the piece acquired a beautiful blue color. The voluntary repetition of this process took several months, but once achieved, more colors were obtained (green, violet, red, ..., etc.), which the knowledge of the electrolytic coloration of the time foresaw as impossible, as indicated above. In 1972, on this first rudimentary industrial process a patent application was made in Spain, to which the number 400189 corresponded, a patent application that was withdrawn before its publication.

After the discovery, the LONGRAF firm came to work with this process on an industrial scale, encompassing it in electrolytic coloring technology with the trade name of IONKOL. Proof of the industrialization of this process is in its commercial launch of the new aluminum colors achieved with the new technology, which was carried out at the EXPAL-72 Fair in Valladolid. For this, a monographic stand was presented with the new finishes, in which a blue window was exhibited, manufactured by the company PREFABRICADOS METÁLICOS UMARAN, as well as a multitude of colored profiles in a variety of shades. After several months of industrial operation, the process was abandoned due to its enormous control and repetitive difficulties, and at the same time the patent was withdrawn, as has been previously reflected, because the process lacks commercial value.

In 1973, the operating conditions of the first industrial process of coloring by light transmission, once abandoned by LONGRAF, were communicated by its inventor to the signatures PECHINEY and ALCAN, through Messrs. Legrand and Sheasby

The first surprising assessment, by the laboratories of PECHINEY, was that no tin particles were detected in the pores of the colored parts by the new system, despite the fact that at one stage of the process the piece was subjected to a treatment of tin electrolytic coloring

On the part of the laboratories of ALCAN the illogical production of colors was justified, in an electrolytic coloration process with non-colored metallic particles, associating it with a phenomenon of optical interference by "thin layer" which resulted in a patent that has formed the basis fundamental for the interpretation of the electrolytic coloration of aluminum

DESCRIPTION OF THE INVENTION

Before entering into the explanation of the fundamental content of the invention, a reminder should be made about the fundamental concepts applied by it, that is to say the light transmission, the main characteristics of the color, as well as the production of colors by synthesis, concepts that will serve basis for the understanding of the present invention First, it is called light transmission of a medium to the capacity that it has to allow a beam of light to pass through. This capacity can be expressed by the transmission ratio, (l / l ₀ ), which represents the relationship between the intensity of light after and before crossing the glass When a material "transmits" all wavelengths of visible, or white, light is said to have a "general transmission" When a material only transmits a certain range of wavelengths of the white light is said to have a "selective or specific transmission", produces by transparency the corresponding "transmission color"

Another characteristic of the crystals is that the transmission ratio, (l / l ₀ ), decreases with increasing thickness and vice versa

- A crystal that transmits a certain color, by significantly reducing its thickness, tends to become colorless and more transparent.

- A crystal that transmits a certain color, when its thickness increases significantly, tends to become gray-black and opaque

Under conventional anodizing conditions for architectural or decorative uses, the anodic film behaves like a crystal with a transmission ratio close to 1, in the entire frequency band of the visible spectrum, that is colorless and very transparent

In different anodizing conditions. as hard anodized or in oxalic medium, the anodic film tends to transmit the yellow color

It is obviously logical that, by increasing the thickness sensibly, the yellow color darkens and tends to gray-black and opaque, which is precisely the evolution of the color of the film in hard anodizing and in some integral coloring systems

The same tendency of the anodic film to transmit the yellow color is repeated in the anodized in sulfuric medium with alternating comment and in the conventional electrolytic coloration with salts of non-colored metals (nickel, tin, cobalt, etc.)

Probably the yellow transmission color, produced during conventional electrolytic coloration, is simply due to the application of alternating current during electrodeposition.

Actually the deposition of the metallic particles in the pores does not produce any color. The only effect it produces is to reduce the luminosity of the yellow transmission color, produced simultaneously to the deposition.

The possibility of modification of the yellow transmission color, characteristic of the anodic film, on the other of the spectrum constitutes the basis of the Electrolytic coloration system by light transmission

Color, in general, is an extraordinarily complex matter, since when we talk about colors we are trying to subjective interpretations of the human brain before the stimuli produced in the eye by light

However, considering the incorporation of new coloring technologies, it is necessary to begin to familiarize yourself with the most fundamental concepts of color, as well as with the quantitative identification of its main characteristics The main characteristics of a color are.

- Hue - Saturation

- Brightness and brightness

- Hue:

It refers to the sensation of color that is perceived when the visible light decomposes. It is designated by different names

When the rainbow is observed, the 7 colors are not appreciated, but are passed from one to the next in a gradual way. That is why the limits given for each color are a bit arbitrary.

When light of all wavelengths reaches the human eye simultaneously (from 3800 A to 7800 A), the brain interprets this light as "white light"

When light from a narrow range of wavelengths reaches the human eye simultaneously, the brain interprets this light as "monochromatic light." The narrower the interval, the more monochromatic is the light.

- Saturation:

It refers to the intensity of a color It varies between zero saturation, (lack of color intensity), and which the brain interprets as "gray", at maximum or spectral saturation When a color is poorly saturated we say that it is a grayish or dead color. On the other hand, when it is very saturated we say that it is a bright color.

- Brightness and brightness:

The luminosity represents the amount of energy of the visible light that reaches the eye, by reflection or by direct transmission through a transparent body, and depending on which colors are better or worse.

When the brightness is maximum, colors cannot be produced. The eye receives only white light. White light becomes white when the perception is diffuse; that is, when no image is appreciated.

When the brightness is zero, colors cannot occur. The eye receives no light. The lack of light converts all colors to black.

The brightness is a subjective response of the eye and the brain to the luminosity, it is to some extent related to the density of light energy that affects the eye. It is closely related to the way light is reflected on the surface of the aluminum, after passing through the anodic film the first time.

When the surface of the aluminum is perfectly smooth and shiny,

(mechanical polishing + chemical polishing), the light is reflected perfectly neatly, in a specific direction; The amount of energy that reaches the eye is maximum. In this case the brightness is maximum or

"specular brightness". When the surface of the aluminum becomes more rough,

(mechanical or chemical satin), the light is reflected in a disorderly and diffuse way, the amount of energy that reaches the eye is minimal In this case the brightness decreases, to the same extent that the surface roughness varies

For the quantitative identification of colors, the most commonly used system is CIELAB. Colors are identified by a point in space, inside a sphere, by means of the coordinates L * a * b *

The coordinate L * represents the luminosity, which varies from 0, (black), to 100, (white) The coordinates a * and b * represent the chromatic coordinates A plane perpendicular to the axis L * determines a circle called the chromatic diagram, a * b * The coordinates a * and b * delimit the quadrants of the color circle A point in this circle is defined by the values of a * and b * The saturation value is linked to the value of the distance to the center of the circle The colors become gray when approaching the center and moving away increase its saturation

Consequently, in the "north pole" and in the "south pole" of the sphere the saturation becomes zero

Starting from the "north pole", so that a color can be seen, the luminosity must be reduced Saturation acquires the maximum value in "the equator" and descends to the "south pole", where it becomes null again

On the axis of the sphere we have the entire gray range, depending on the luminosity, which goes from zero brightness, (black), to maximum, (white) For this reason, the "normalized gray scale" was used to determine, by contrast, the brightness of a color

When we reduce color saturation on a color TV screen, what we really do is convert each colored point of the image into a gray point of equal brightness

There are two ways to produce colors

Additive Synthesis:

By mixing 2 monochromatic lights with the primary colors BLUE, GREEN and RED, the colors cyano, yellow and magenta are obtained by addition

When mixing 3 monochrome lights with the primary colors blue, green and red, the color WHITE is obtained by addition

Playing with the mix of monochrome lights, with the 3 primary colors and with different degrees of saturation, you can get a virtually unlimited number of colors This is based on obtaining color images on a TV screen, or on a monitor computer Each point of the image is unfolded in 3 points with the 3 primary colors, which represent as 3 small spotlights of color These 3 small spotlights are activated separately, with greater or lesser intensity or saturation, to produce the desired color

Although the 3 foci are really separated, the eye, by their resolution power, sees them mixed, producing the corresponding color. This way millions of colors are obtained I 1

(Currently 16.7 million colors are obtained on computer screens)

- Subtractive Synthesis:

By mixing 2 pigments with the primary colors MAGENTA, CIANO and YELLOW, the colors blue, green and red are obtained by subtraction

By mixing 3 pigments with the magenta, cyano and yellow primary colors, the BLACK color is obtained by subtraction

By superimposing 2 optical filters with the primary transmission colors MAGENTA, CIANO and YELLOW, and projecting white light on them, the blue, green and red colors are produced by subtractive transmission

By superimposing 3 optical filters with the primary colors of magenta, cyano and yellow transmission, and projecting white light on them, the color BLACK is produced by subtractive transmission

Playing with the mixture of pigments, with the 3 primary colors MAGENTA, CIANO and YELLOW, in different proportions, you can get a virtually unlimited number of colors This is based on the operation of photocopiers or color printers

Indeed, in these teams only 3 pigments are used, with the primary colors magenta, cyano and yellow, as well as black, which is the mixture of the 3

Starting from these considerations and basic teachings for the understanding of the invention, the following will be carried out description of the aluminum coloring process as proposed in the invention

First of all it should be noted that with the process described in this invention the industrial repeatability of the coloration is achieved, since this was the great defect of the current processes, through which it was known as coloring the electrolytic aluminum, but the coloring process could not be controlled in any way, so that neither colors nor shades given to that aluminum could be repeated over time

With this process the great advance achieved is to have controlled in a differentiated and independent way the three fundamental characteristics of the colors or coloπmetπcas coordinates, such as saturation, hue and luminosity

The process of coloring the aluminum starts from an aluminum that is previously anodized, in which the classic micropores have been produced on its surface and under them an alumina layer This phase is the traditional one of anodizing and it is the same a previous step, necessary, but whose result will not influence for the development of the chlorines, since from this the mentioned process will be elaborated

To this anodized aluminum and from which the invention starts, it is subjected to a subsequent anodizing, by introducing it in an electrolytic bath of low dissolution power, helping to achieve this low dissolution power being at a low temperature, lower than 20 ° C A preferred temperature at which the electrolyte should be found ranges between 10 ° C and 18 ° C π

The dissolving power of this electrolytic bath is included in margins lower than that of a traditional electrolytic bath, being able to be encrypted in a margin between an equivalent solution of sulfuric acid between 3 gr / l and 25 gr / la 20 ° C As it has been said the dissolving power of the electrolyte can be controlled by means of temperature, so at lower temperatures the dissolution power is lower than at high temperatures, whereby the same electrolytic bath can be used for various electrolysis in which there is What to do with electrolytes of different dissolution powers

This new electrolytic bath produces a more voluminous new alumina gel mass below the pores due to the fact that it has just been produced. This alumina gel mass is produced with a continuous and pulsating comment with a voltage peak higher than the previous anodization, this voltage oscillating between 15 and 60 volts, although the most suitable or preferred voltage is between 15 and 60 volts

With this new treatment, as already mentioned, a great mobility of the alumina gel mass produced must be achieved, mobility that will be in line with the specific weight of the same, with which a mass of a weight must be achieved specific small and therefore high mobility The pulsed direct current applied must vary between 1 to 5 resting half cycles and the current passing between 1 and 10, with its preferred or more appropriate value between 1 and 3 resting half cycles and between 1 and 5 current flow

This gel mass formed is what will allow independent control of color coloometric constants such as saturation, hue and luminosity Then, once this new gel mass is produced, new micro-pores are produced in that gel mass, by applying a pulsating alternating current, at voltages that produce at least 7 micro-pores made by means of a central pore and six in an orbit distributed in an imaginary hexagonal grid, these micro-pores being distributed in the gel mass formed in the lower part of the pores made in the previous anodizing The separation and diameter of these newly formed micro-pores in the gel mass they are proportional to the peak voltage of the applied positive half-cycle and its maximum value would be that which produces 7 micro-pores that occupy the total surface This peak voltage of the applied positive half-cycle ranges between 1 and 10 volts, although its preferential value ranges between 2 and 8 volts

With these formed micro-pores, the saturation of the final color of the anodized is controlled, which is influenced by the number of micro-pores produced that varies according to the applied peak voltage, so that the micro-pores increase according to the voltage applied be smaller

On the bottom of these micro-pores they are formed in the process of obtaining them a new spherical alumina gel mass that acts as true microlenses, which can be varied in size by applying a continuous and pulsating comment that increase that gel mass formed under each micro-pore and thereby achieve a larger or smaller size of these microlenses thus constituted. The peak voltage applied in this modification of the microlens size ranges between 1 and 20 volts and With it the size is graduated until the ideal one for the application is achieved. The cycles of this continuous and pulsating comment can vary between 1 and 5 for the resting half cycles and from 1 to 10 for the current passing, 1 * 5 being the preferred number of 1 to 3 resting half cycles and 1 to 5 in the current passing half cycles

With these premises, that is, with the production of micro-pores in the gel mass and the modification of the size of the microlenses formed under each micro-pore, it is possible to perfectly control the color saturation that anodized aluminum will offer

On the background of the micro-pores obtained, other smaller micro-pores can be made and so on, so that the process followed would increase the number of microlenses formed but would result in them being smaller

To control the hue of the final color of anodized aluminum, it is carried out by modifying the transmission color of the micro-lenses, applying a continuous and pulsating current in such a way that the application time of this continuous and pulsating current will define the different shades of the visible spectrum achieved, appearing all the colors of the visible spectrum in a sequential manner in reverse order of their wavelengths This sequence of modification of the hue varies between 1 and 30 minutes, although its value may preferably be between 1 and 20 minutes, during which time all colors of the visible spectrum appear on the anodized aluminum part

Finally, the third characteristic to control color is the luminosity, which is controlled by electrodeposition of non-colored particles, this electrodeposition process is carried out in a third independent electrolytic bath. The value of the luminosity obtained in the piece is inversely proportional function of the duration of the electrodeposition process, so that for a longer and longer quantity of deposited particles is linked to a lower luminosity of the piece and vice versa, that is to say a smaller number of deposited particles joins a greater luminosity of the same

This description made for the process of anodizing aluminum could be made for any other metal that can be anodized, varying the conditions under which the oxide gel mass of the metal formed, the micro-pores that are formed and the size are produced and shape of the microlenses thus made, each of the metals having differential conditions, although the process followed is performed in the same way

DETAILED DESCRIPTION OF THE DRAWINGS

To carry out a detailed description of the invention, we proceed to provide a series of figures with which we will attempt to detail in a clearer way the said invention

Figure 1 represents the classic light transmission curves

Figure 2 represents the graph of the additive color synthesis

Figure 3 represents the graph of subtractive color synthesis

Figure 4 represents a plan view of an anodic film on aluminum, made by a traditional process

Figure 5 represents a cross section of this same film shown in Figure 4 Figure 6 represents a plan view of the distribution of the micropores in hexagonal form formed on the gel mass made in the second electrolytic bath.

Figures 7 to 9 represent different shapes and sizes of the micro-pores formed on the gel mass that will result in a control of the saturation of the color of the aluminum.

DETAILED DESCRIPTION OF THE DRAWINGS

Figure 1 shows the light transmission curves for colorless and transparent plates, glass (A), red glass (B) and almost opaque dark gray glass (C), where its horizontal axis or abscissa represents the wavelength values, with values expressed in Amstrongs (Á), while the vertical or ordinate axis expresses the transmission ratio (l / l ₀ ).

Figures 2 and e represent respectively the graphs of additive and subtractive color synthesis.

- Additive Synthesis:

By mixing 2 monochromatic lights with the primary colors BLUE, GREEN and RED, the colors cyano, yellow and magenta are obtained by addition.

By mixing 3 monochrome lights with the primary colors blue, green and red, the color WHITE is obtained in addition.

Playing with the mix of monochrome lights, with the 3 primary colors and with different degrees of saturation, a virtually unlimited number of colors can be obtained. This is based on obtaining color images on a TV screen, or on a computer monitor. Each point of the image is divided into 3 points with the 3 primary colors, which represent 3 small colored spotlights. These 3 small bulbs are activated separately, with greater or lesser intensity or saturation, to produce the desired color

Although the 3 foci really are separated, the eye, by their resolution power, sees them mixed, producing the corresponding color. In this way millions of colors are obtained

(Currently 16.7 million colors are obtained on computer screens)

- Subtractive Synthesis:

By mixing 2 pigments with the primary colors MAGENTA, CIANO and YELLOW, the colors blue, green and red are obtained by subtraction.

By superimposing 2 optical filters with the primary transmission colors MAGENTA, CIANO and YELLOW, and projecting white light on them, the blue, green and red colors are produced by subtractive transmission.

By superimposing 3 optical filters with the primary colors of magenta, cyano and yellow transmission, and projecting white light on them, the BLACK color is produced by subtractive transmission. Figure 4 represents a plan view of the structure of an anodic film on aluminum Each hexagon of this structure represents a cell and in the center of each one a pore (1) can be seen, at the bottom of which is the aluminum oxide gel mass The rest of the cell is occupied by solidified aluminum oxide, which originally came from a gel mass In the growth process of the anodic film, the gel mass is displaced and accumulated in the edges of the area bounded by two spherical caps This illustration has been taken from the book "THE SURFACE

TREATMENT AND FINISHING OF ALUMINUM AND ITS ALLOYS, S. Wernick, R. Pinner and P.G. Sheasby, Chap. 6 Cell dimensions. The Manchester School, direct observation of pores and barrier layers ".

Figure 5 represents a cross-section of the structure of an anodic film on aluminum. At the bottom of each pore (1) of the anodic film, the barrier film (3) formed between the pore and the metal (2), constituted by this barrier film (3) by an area of aluminum oxide formed as a result of its electrolytic oxidation In the form of each pore (1), the barrier film adopts a spherical double cap shape essentially constituted by gel-shaped aluminum oxide

In order to carry out the process of the invention, it is based on an anodic film as shown in these figures 4 and 5, and then proceeds to place the piece in a second electrolytic bath of low dissolving power, helping to achieve this low dissolution power being at a low temperature, below 20 ° C A preferred temperature at which the electrolyte should be found ranges between 10 ° C and 18 ° C The dissolving power of this electrolytic bath is in a range lower than that of a traditional electrolytic bath, being able to be encrypted in a range between an equivalent solution of sulfuric acid between 3 gr / l and 25 gr / la 20 ° C.

This new electrolytic bath produces a more voluminous new alumina gel mass under the pores and is highly mobile because it has just been produced. This alumina gel mass is produced with a continuous and pulsating comment with a peak voltage higher than the previous anodization, this voltage oscillating between the

15 and 60 volts, although the most suitable or preferred voltage is between 15 and 60 volts

This gel-formed mass is what will allow independent control of the colonmetric constants of color such as saturation, hue and luminosity

Then, once this new gel mass has been produced, new micro-pores are produced in that gel mass, by applying a pulsating alternating comment, at voltages that produce at least 7 micro-pores made by means of a central pore and six in an orbit distributed in an imaginary hexagonal grid, these micro-pores being distributed in the gel mass formed in the lower part of the pores made in the previous anodizing The separation and diameter of these newly formed micro-pores in the gel mass are proportional to the peak voltage of the applied positive half cycle and its maximum value would be one that produces 7 micro-pores that occupy the total surface. This peak voltage of the applied positive half cycle varies between 1 and 10 volts, although its preferential value ranges between 2 and 8 volts

Figures 6 to 9 allow us to observe plan views of the distribution of the micro-pores with different sizes and separations, with which the size and number of the microlenses are used. Figure 9 shows the distribution of the micropores in two orbits on a central pore, the first or closest to the central pore with 6 micropores and the second or more external with 12 micropores

On the bottom of these micro-pores they are formed in the process of obtaining them a new spherical alumina gel mass that acts as true microlenses, which can be varied in size by applying a continuous and pulsating comment that increase that gel mass formed under each micro-pore and thereby achieve a larger or smaller size of these microlenses thus constituted. The peak voltage applied in this modification of the microlens size ranges between 1 and 20 volts and with it the size is graduated until it is suitable for the application Figures 6 to 9 allow us to observe the different results obtained by modifying the applied peak voltages. The cycles of this continuous and pulsing current can vary between 1 and 5 for the rest half cycles and 1 to 10 for the current pass cycles, the preferred number being 1 to 3 rest half cycles and 1 to 5 in the half cycles. of current flow.

On the background of the micro-pores obtained, other smaller micro-pores can be made and so on, so that the process followed would increase the number of microlenses formed but would result in them being smaller.

To control the hue of the final color of the anodized aluminum, it is carried out by modifying the transmission color of the micro-lenses, applying a continuous and pulsating current in such a way that the application time of this continuous and pulsating current will define the different shades of the visible spectrum achieved, appearing all the colors of the visible spectrum in a sequential manner in reverse order of their wavelengths. This sequence of modification of the hue varies between 1 and 30 minutes, although its value may be preferably between 1 and 20 minutes, during which time all colors of the visible spectrum appear on the anodized aluminum part.

Finally, the third characteristic to control color is the luminosity, which is controlled by electrodeposition of Uncolored particles, performed this electrodeposition process in a third independent electrolytic bath. The value of the luminosity obtained in the piece is an inversely proportional function of the duration of the electrodeposition process, so that at a greater time and greater amount of deposited particles a lower luminosity of the piece is joined and vice versa, that is to say at a lower number of deposited particles binds a greater luminosity thereof.

Claims

1 ^a - Electrolytic process of coloring anodized aluminum, by modifying and controlling the transmission color of the anodic film, characterized in that the coloπmétπcas coordinates, such as saturation, are controlled in a differentiated way to achieve industrial color repeatability. the hue and brightness of the color to be obtained on the surface of the aluminum, by modifying the transmission color of the aluminum oxide produced under the bottom of each pore of the previously formed anodic film

2 - Electrolytic Process for dyeing anodized aluminum according to claim 1, characterized in that for industrial repeatability of colors with the corresponding independent control of the saturation, hue and brightness, is to produce a new oxide gel mass under the bottom of each pore of the anodic film, this oxide being produced in a second electrolytic bath of low dissolution power, different from that of the previous anodizing, under differential conditions and by applying preferably continuous and pulsating currents

3 - Electrolytic Process for dyeing anodized aluminum on, according to claim 2, characterized in that the dissolving power of the electrolyte varies between approximately equivalent values with respect to a solution of sulfuric acid in water between 3 g / l and

25 gr / l at 20 ° C

4 - Electrolytic Process for coloring aluminum anodizing according to claims 1 to 3, characterized in that for independent control of the saturation, hue 2 * 5 and the luminosity, it is necessary to minimize the negative effect due to the dissolution power of the second electrolyte, working for it at temperatures below 20 ° C

5 ^a - Electrolytic process of coloring anodized aluminum according to claim 4 ^a , characterized in that the temperature of the second electrolyte preferably ranges between 10 ° C and 18 ° C

6 ^a - Electrolytic process of coloring anodized aluminum, according to claims 1 ^to 3 ^a , characterized in that in order to achieve the best independent control of saturation, hue and luminosity, it is necessary to produce a large volume of gel mass and that this has the greatest possible mobility, which is achieved by applying a comment, preferably continuous and pulsating, with a peak voltage higher than the previous anodizing, ranging between 15 and 60 volts, and more preferably between 25 and 40 volts

7 ^a - Electrolytic method of coloring anodized aluminum, according to claims 1 ^to 3 ^a , characterized in that in order to achieve the best independent control of saturation, hue and luminosity, it is necessary to favor the mobility of the gel mass produced in the second electrolytic bath, preventing it from increasing the specific weight of the same, applying a continuous and pulsating comment, being able to vary the pulses by combining a certain number of resting half-cycles with another determined pitch step

8 ^a - Electrolytic process of coloring the anodized aluminum according to claim 7 ^a , characterized in that the number of resting half cycles of the pulsed direct current intended to favor the mobility of the gel mass can vary from 1 to 5 and that of current passing from 1 to 10, preferably the number of resting half cycles ranges from 1 to 3 and the 1 to 5 current flow

9 ^a - Electrolytic process of coloring the anodized aluminum according to claims 1 ^to 3 ^a , characterized in that to control the saturation of the final color, micro-lenses are produced at the bottom of new micro-pores produced in the dough- gel formed in the second electrolytic bath, these micro-pores being produced by applying a current, preferably pulsating alternating, at voltages such that at least 7 new micro-pores are distributed in an exagonal manner on the surface occupied by the mass -gel, being the diameter and the separation between the micro-pores proportional to the peak voltage of the positive semi-cycle applied and its maximum value which would produce 7 micro-pores that occupy the total surface

10 - Process for dyeing electrolytic anodizing aluminum, according to claim 9, wherein the value of the peak voltage of the positive half cycle applied vain between 1 and 10 and preferably between 2 volts and 8 volts

11 ^a - Electrolytic process of coloring the anodized aluminum, according to claims 9 ^a and 10 ^a , characterized in that to control the saturation of the final color the number of micro-pores produced is regulated, according to an exagonal distribution, thereby varying the voltage of peak of the positive semi-cycle applied, so that the number of micropores increases as the voltage decreases

12 - Electrolytic Process for coloring aluminum anodizing according to claims 1 to 3, characterized in that controlling the saturation of the final color, the size of the micro-lenses formed at the bottom of the new micro-pores produced in the gel mass formed in the second electrolytic bath can also be modified, by applying a current, preferably continuous and pulsating

13 ^a - Electrolytic process of coloring the anodized aluminum according to claim 12 ^a , characterized in that the peak voltage applied in the modification of the size of the micro-lenses varies between 1 and 20 volts

14 ^a - Electrolytic process of coloring the anodized aluminum according to claims 12 ^a and 13 ^a , characterized in that the number of resting half cycles of the pulsing direct current intended to modify the size of the micro-lenses can vary from 1 to

5 and the one of step of comment of 1 to 10, preferably the number of half-cycles of rest vain of 1 to 3 and the number of passage of current of 1 to 5

15 ^a - Electrolytic process of coloring the anodized aluminum according to claims 1 ^to 3 ^a , characterized in that to control the hue of the final color, the transmission color of the micro-lenses is modified by providing current with the conditions of peak voltage established according to claim 12 ^a , depending on the amount of current of the application time thereof, so that with the increase thereof the different shades of the visible spectrum are produced, in sequential order inverse to their wavelengths

16 ^a - Electrolytic process of coloring the anodized aluminum according to claim 15 ^a , characterized in that the duration of the entire sequence of modification of the transmission color of the micro-lenses ranges between 0 and 30 minutes and preferably between 1 and 20 minutes,

17 .- Electrolytic Process for dyeing anodized aluminum, according to claim 1 to 3, characterized in that to control the brightness of the final color, a process of electrodeposiciόn metal particles uncoloured is performed in an independent third electrolytic bath, being the value of the luminosity obtained function inversely proportional to the duration of the electrodeposition process.