DE2100497A1 - Process for the electrophoretic application of paints on ferrous surfaces - Google Patents

Description

PATENT ADVERTISERS-; * ' _%

DR. ING. A. VAN DER WERTH DR, FRANZ LEDERER

31 HAMBURG 90 'B MÖNCHEN 80

WlLtTO (FIIt »Τ«, at - TEL. (0411) 770 * 41 LUCILI-CRAHN-ST ». 13 - TIl. (Ο · ΙΙΙ 44 0 * 46

Munich, January 6, 1997? L / B

Applicant's Atachem Products? Inc " _c Brook" id "Avenue" Ambler, Pennsylvania "US, A _O

Method of electrophoretic application of Colors on ferrous surfaces

The invention relates to an improved method asu "electrophoretic application of colors to iron-containing surfaces _o In particular, it relates to the formation of faultless electrophoretically depressed films brighter colors on phosphatttberzogenen ferrous metal surfaces"

The electrophoretic * deposition technique for applying paints to metal surfaces has been widespread for the last few years because it offers numerous advantages ο For example, the thickness of the paint film applied to the surface by electrophoretic deposition can even be sharp and sharp Control edges precisely. By a electrophoretic deposition, cheeses _p depressions _B bulges or tears in the color film can be avoided. This deposition also enables depressions or cavities in the surface to be provided with color, which is difficult to achieve in any other way. The efficiency of electrophoretic deposition is high because

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Ultimately, nearly $ 100 of the paint can be consumed. Compared to other paint application techniques, the elec> trophoretic separation has relatively little risk of toxic fumes or fire «, Furthermore the electrophoretically generated, wet-deposited paint films are only slightly sticky, which is what the subsequent handling of the colored objects. The consequence is an electrophoretic deposition of colors for use in automated Installations particularly suitable «

On the other hand, the electrophoretical application of colors to metal surfaces is not free from certain disadvantages to improve both the corrosion resistance of Uterfläche ale also the adhesion de * applied to it. '''arbfilcis has been applied _o even codifications as the ftltverwendung of at least 0.1 g / l of fluoride ions in the used standard Zinkphosphatübersugslösungen, can "inev improvement in terms of resistance to corrosion after an eltktrophoretic “paint application on an iron or ethereal surface, especially if the phosphate coating has been rinsed with an aqueous _{solution containing 9} hexavalent chromium compounds” before the paint application been developed beyond sxnd electrodepositable colors that films with high Korrosionsbeständlgksit and paint adhesion form Using this new electrophoretically abscheidbartn colors seems to be hosphatiegewonnen l-only either dmr corrosion resistance or the Färbhaftfestigkeit from modifications in the usual.

However, another, much more difficult and serious problem exists with the electrophoretic deposition of bright colored rims or other bright ones; Colors deposited electrophoretically on an iron or steel surface tend to _p

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blurry in color, dirty white or even yellowish too This unwanted discoloration can be the entire stained Cover the surface evenly or only appear in certain areas »The spotty surface obtained in the last case is particularly ugly because it contains blotches of a fuzzy, off-white, or yellowish color · This problem a uniform or uneven discoloration occurs epga-r when the improved electrophoresis inks are used, the corrosion resistance and the paint adhesion strength improve :; «, Sin related problem occurs whenever a white © represents another light color electrophoretically on one iron-containing metal surface is applied with so-called "Sohautastoffe", for example oil, fat and / or carbonaceous Materials that are contaminated »Such contaminants tend to migrate to the surface of the color film, if it is upset and cause blemishes, dl « stand out particularly in light colors. Although of course dl « Surface before a paint application with sisalictar security is cleaned, the resin adheres to the metal surface and often denies "in the" Jint £ ermmgev® ^ feiis "n"> In fact, he can even evade discovery, dft dtfa To the unarmed eye the surface defies the active presence seems to be clean of some dirt even if maa hopes To produce a flawless, light-colored, electrophoretically deposited paint film on ferrous metals, nut the Surface first subjected to the strictest cleaning conditions which are both time consuming and costly.

Eb must be emphasized that djtese problems caused by discoloration and / or blemishes caused by pollutants are not only of an aesthetic nature They also affect the Albodo, i.e. the light reflection, of the color film is disadvantageous, which in the case of brightly colored white objects, for example light fittings, for their own can make borrowed purpose unsuitable =, where for the albedo uee If a certain standard is prescribed for the paint film, the electrophoretic paint application process * sometimes not used satisfactorily *

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Attempts have been made to address the problems of discoloration and / or blemishes caused by contaminants elektrophoretiechen application is formed, an electrically conductive primer coat on the ferrous surfaces from one with "barrels verdiiönbaren color that an electrically conductive Pi-g ~ [ 'ent, such as carbon black, or ülruß, and a water-dispersible ^ Ears, such as a? henol ~ Alkydhars, or melamine-alkyd resin, contains "JJiβ white or other light electrophoretic paint can then be safely applied to this base coat". However, although this method can remove the probable discoloration and / or blemishes caused by raw materials * it increases the cost of the paint application process considerably, since additional materials used to form the primer coat are expensive, and additional gate directions and monitoring damage the primer coat Apply electrophoresis *

It has now been found that the problem of discoloration of light colored, electrophoretically on ferrous surfaces deposited color films can be solved in an economical manner can if the surface apply "copper-plated" is. It was also found that This "technique" strongly reduces the damaging effects of so-skin "substances which inadvertently decreases prior to electrophoretic deposition got onto the surface. That way you can get a usually satisfactory result without extraordinary strong shine obtained. It should also be emphasized that these caused discoloration and / or contamination problems Damage does not occur if the electrophoretic «paint application is dark in color, for example black, or bright, for example red, 1st, but only with pastel and similar light shades, such as ivory, eggshell-colored, oyster white or cream color £., and of course especially with white, where the problem is most serious

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Solve the problem of color irregularity, whatever it is occurs, eliminated, the term "light colored paint" used in the description and claims refers both white and any other light colored paint that has problems of discoloration and / or damage caused by pollutants,

According to the present invention, therefore, a method of application is provided light colored paints by means of an electrophoresis Deposition technique on the surface or on a formed one Substrate made of essentially ferrous metal is available placed, in which in a first stage the surface with a ^ Solution treated is at least a sufficient amount ™ Contains copper in a soluble form in order to avoid color irregularities in the subsequently deposited color «»

The treatment of the ferrous surface with a copper-containing solution (which for simplicity can be referred to as ^M copper solution *) prior to subsequent electrophoretic deposition can be carried out in a simple and economical manner, as will be described in detail below, and gives highly satisfactory results. Iron-containing surfaces that are treated in this way and then colored by electrophoretic deposition of a white or other light color are - as has been found - free of color irregularities, such as yellowish9 dirty-white or blurred spots. They are also free from soiling caused stains provided that the surface is fairly clean, although it need not be exceptionally clean. With the method of the present invention, the problems previously associated with electrophoretically deposited white or other light colored films can be eliminated or at least for the most part reduced deposited film of a white or other light color with an improved albedo. " As already said, the inventive method creates

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drive an effective way to deal with the aforementioned problems without the expense of the paint application process rens to increase significantly «Furthermore, as will be described below, it can be easily converted into the usual» Surface pretreatment systems applied to ferrous surfaces be incorporated before the surface is colored.

Although the invention is in no way limited by any theoretical considerations, it is believed that the effectiveness of the Yerkupferungsverfahrens to eliminate dbr above problems at least partially can be explained as follows · When elektrophoretisehen deposition of colors is the au. coloring metal surface normally switched mostly as an anode and the metal, the color-containing vessel as a cathode _"t During the Farbauf ~ bringing the anode is immersed in the dyeing bath, and a voltage" wipe the electrode set, flow around the electrical current through the dyebath au "The outer surface" of the color film consists of the color particles which are first deposited on the surface. Consequently, the outer visible surface of the deposited paint film consists of the first deposited dye particles. Incidentally, this "wrong" formation of the paint film is peculiar to the electrophoretic paint application process. However, the metallic iron is oxidized to ions at the anode, which leads to the formation of iron hydroxides leads »These are likely to be stored in the color film when it forms, and repelled from the surface again.« In this way, you get to the sweeter surface of the color film yourself. Since these iron hydroxides themselves are dark in color, they tend to discolor the applied color film. If the color film is further hardened by heating, the iron hydroxides split off water and form dark-colored iron oxides, which also change the appearance

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of the cured color films deteriorate because they result in the irregular discoloration mentioned above

However, if the surface of the present invention ¹ kupfert been ', it is believed that during the subsequent electrophoretically "η Farbabsoheldung the copper also *., At the anode to form copper (II) ions oxidizes wftrA and that this calibration KupferCII ) ions with certain stock-ji * share in the paint to form a united Kateriale · dat the color of iron hydroxides and iron oxides' aasklert **. For copper (II) flores, each sun example combines with an amino compound to form a copper complex β (theoretically Cu (NE ₅ ) ^ ⁺ *) sn, which is blue. In the case of electrophoretic paints, amino compounds are used as a solvent. It is established that such a blue complex is formed, so that the function is incorporated into the paint filament when it forms, and black and white in the same way as the iron hydroxides a lifting * or nasklereaa of the undesirable «n colors of the egg hydroxide and iron oxide! expect».

It does not matter whether this explanation is complete or even correct * because the fact has been established that the "copper plating" of the surface eliminates the color irregularities in the color files and leads to an improvement in the albedo of white colors and also leads to a reduction in the harmful effects of the emollients * "Of course, it is clear that although extremely vigorous cleaning of the surface is not required when using the method of the present invention, the surface does not need to be cleaned, among other things oxide residues and> corrosion products su remove. Έ% η such prior cleaning may customary Bitteis, dea Sfachaann known processes are performed.

It must be noted that a certain amount of hiniaa is copper

on the surface is needed to achieve the improvements according to the invention, but this measure differs ajLch

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according to a number of variables both in the pretreatment and in the coloring stages of the process. These variables include the individual bright electrophoretic colors used _? the conditions under which the electrophoresis is carried out, the thickness in which the paint film is applied, the type of ferrous metal surface to be colored and the method chosen for treating the surface with the copper-containing solution ”. The amount of copper required for a given layer can, however, be determined empirically very easily, taking into account the following conditions. The first and most important condition is that the amount of copper is insufficient if the color film has color irregularities * such as a blurry, dirty-white • yellowish color , either as a whole or distributed according to flaws, or as a blemish of a kind caused by sedimentation of substances. Second, as the amount of copper is increased, in general the hue of the light color film will become more bluish while all other variables are held constant; consequently, the amount of copper is too high if the color film turns out to be more bluish than desired. Thirdly, it follows that the color film produced has the purest white color if smaller amounts of copper are used, which are sufficient to avoid color irregularities but not so high that they have a evoke distinctly blue tint »Although it is difficult to distinguish the whiter tint from the blue and white tint ait the naked eye, they can be easily distinguished by comparing the colored surfaces with a white standard, since the albedo of the whiter tint is higher than that of one blue and white tint. Fourth, however, the whiter tints are not necessarily the most desirable except when the albedo of the color film is of fundamental importance o Since it is known that in general the eye prefers a blue-white surface to a pure white surface (although even a blue-white tint has a lower albedo as pure white), it is preferred for most purposes to use a solution containing copper which is sufficient

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Contains copper to produce a bluish tint in the electrophoretically deposited color film »Ein waitersr The advantage of the method of the present invention is that such a bluish tint in the white application without the incorporation of pigments, such as ultramarine blue, can be formed, and it may be noted, incidentally, that the incorporation of such pigments into electrophoretic whites Colors does not avoid the color irregularities discussed above «,

1 » V.

The treatment with the copper-containing solution can take place in various ways. " The simplest way is to simply bring the bare iron-containing metal surface into contact with a simple aqueous solution of a copper salt before the step of the electrophoretic color deposition." However, the iron-containing metal surface is preferred the color deposition is provided with a phosphate layer, and then the treatment with the copper-containing solution can take place before, during or after the phosphating. In fact, it is generally most advantageous to treat the copper-containing solution at the same time as the phosphating using a copper-containing one To carry out phosphating solution, not only because it saves an operation, but also because it controls the amount of copper deposited on the surface and thus the correct shade of the% subsequently applied color film lms with high accuracy,

Therefore, there is a preferred embodiment of the invention Method in that the subject to the treatment Surface is a clean, bare ferrous metal, which can be simultaneously brought into contact with an aqueous, acid phosphating solution containing a copper salt is copper-plated and phosphated in order to form a phosphate coating on it *

The applied "irh''3phat-e *." £ 3lößuni "can be the most advantageous

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210049?

a so-called «coating-forming phosphate» «solution, i.e.» one on zinc phosphate either with or without calcium phosphate based solution »In this case, the required! tight copper, to ensure the whiteness of the electrophoretically deposited color film, is generally applied, when the copper ion concentration in the phosphating solution within the range of 0.5 to 90 parts per million and a typical dwell time of about 15 seconds to 2 minutes is used. The copper ion concentration in the thosphating solution is * rarely 5 parts per million over * rise and generally no more than 2.5 parts per million However, if it is desired to produce a bluish tint in the electrodeposited paint, so then the copper ion concentration in the phosphating solution generally be at the upper limit of the range, and thus greater than 10 parts per million and preferably in the range of 20 to 50 parts per million «.

As is the case with phosphating solutions of the coating-forming phosphate type is common, it is desirable that the acidity is properly controlled, and it is therefore recommended that that the phosphate solution has a pH value within the range from 1.8 to 3.5, a free acidity within the range 0.3 to 10, and an overall acidity within the Range from 5 to 100 must have the "free acidity * of the Solution is defined as the number of milliliters of a 0.1 N sodium hydroxide solution used to neutralize a 10 ml sample of the solution is required using bromophenol blue as an indicator. The "total acidity" of the solution is defined as the number of milliliters of a 0.1 N sodium hydroxide solution, for neutralizing a 10 ml trobe of the Solution using ihenolphthalein as an indicator is required iSt O

Again, it is common practice in phosphating the coating solution is also desirable. essentially free from To keep iron (II) ions, since if you remove the iron (II) ions * Concentrate can be formed in the solution that is produced

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Copper-containing PhosphatierungslQsungen both of about £ ^w ugblldenden Phosphaf-type and the "non-coating-forming phosphate * ¥ ~ ype can be applied to the eisenhaltigenüetalloberfläohen in any way. For

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Phosphate coatings are very loose, powdery and unsuitable »To avoid the formation of ElsanCII) ions, It is therefore usually advantageous for the phosphate solution to that it also contains an oxidizing agent which Εΐ8βη (II) ions oxidized to Eisea (III) ions.

According to another common practice, it is recommended that the surface after contact with the copper containing Phosphating solution before the electrophoresis chen application the paint is rinsed »You can rinse first or only with Water would be carried out, but preferably the last aqueous Nachapülldsung used trivalent and / or six-valued chromium ions contain »

B -

The "copper-containing Phosphatlerung & solution used is preferably a coating forming the aforementioned" phosphate ** "type _t dia imparted the surface corrosion resistance is very good. However, if the corrosion resistance of 1st most important factor, but still a more economical phosphate coating & 1 &'ine basis to speed good paint adhesion is required »the phosphating solution used can be of the so-called" non-coating-forming phosphate * type, ie a solution based on alkali metal and / or «or Asnoniusphoephatea»

The phosphating solution is preferably based on this Fall for sodium phosphate «™

The concentration of the cononatrium phosphate is usually in the range from 2 to 20 g / 11 and the phosphating oil may also contain an accelerator which can advantageously be sodium molybdate, which may optionally be in a concentration within the range of O ₁ O? up to 0 _P 5 g / l can be present. >

For example, the following techniques are suggested as they are likely to give satisfactory results:

(«) Spraying the copper-containing phosphating solution onto the metal surface for one to two minutes at a temperature of 60-7O ⁰ C or

(b) immersing the metal surface in the copper hai ent * tend phosphating solution for two to five Hi "utes at a temperature of 65-76 ⁰ C.

At these parts it can be pointed out that certain Phosphating solutions containing copper are known as such and have long been used to apply corrosion-resistant and color-fast adhering coatings to metal surfaces. The copper can in such solutions in any shape can be introduced that does not have a detrimental effect on it and functions as an accelerator therein, d, b> that its presence is the weight of the on the metal surface Phosphate coatings deposited within a given period of time are increased. However, the known copper-containing Phosphate unsolutions according to our knowledge up to not yet to form a phosphate coating on iron-containing Metal surfaces have been used that are anechillic have received a bright color film electrophoretically deposited thereon. This is not surprising given the usage of copper-containing phosphating solutions for the production of a basic shift for colors are disadvantageous due to the fact is that - as was found · when high levels of copper are present in the phosphating solutions and if the received Phosphate coating by a non-electrophoretic process is colored, the color film only poorly on the surface " adheres, the corrosion resistance of which is also rather poor. Ules poses exactly the opposite of that represents what according to the invention is the case when the color film is electrophoresed is deposited. In the method of the present invention, if the older type of lighter electrophoretic paints is used, the corrosion resistance and / or " cause problems with adhesion, but don't *

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Partly, a zinc alkali phosphating solution containing copper to use the copper in a higher range of Contains 10 to 50 parts per million, preferably from 20 to 50 parts per million, as this is not just about looks but also the corrosion resistance and the color adhesion ~ Strength properties of the colored surface improved.

However, the method according to the invention can also be brought into contact the surface with an aqueous solution containing dissolved copper, regardless of one or even without a phosphating treatment o '

It is therefore another feature of the invention that it is bare ferrous metal surface of a treatment by contacting with an aqueous solution containing a dissolved copper salt

The solution used need not contain solubles other than a soluble copper salt, but it is It is desirable that the copper concentration in the aqueous solution be within a range of 100 to 10,000 parts each Million lies. The contact time between the ferrous metal surface and the solution can in general Range from 1 to 10 manifest «

after the bare iron-containing metal surface has been copper-plated by means of the aqueous copper-containing solution, it can, if necessary, be electrophoresed before the "!!" Parba applications can be phosphated by contacting them with a phoaphatizing solution of either the "coating-forming phosphate * type or of the" never-coating-forming η phosphate ¹¹ type. The phosphating solution used is preferably of the "coating-forming phosphate * ¹ type, which is based on zinc or zinc / galloiua and which are the same in every respect except their copper content", as described above.

If necessary, the surface to be subjected to the treatment can an already phosphated iron-containing metal surface

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be flat, which then touch a old an aqueous solution old a hold on a dissolved one Copper Sala is subjected to o

The previous Phoaphatierung treatment can be done again can be carried out in the same way, except for the omission of the copper, as described above. They are subjected to the treatment of the aqueous solution containing copper Phosphated iron-containing metal surface is preferably one by contacting with an aqueous acidic phosphate solution of so-called "coating forming phosphate" type based on 2inc phosphate either kit or without calcium phosphate previously phosphated surface »

However £ s BUD noted that "when an aqueous copper-containing solution applied to a previously phosphated ferrous metal surface," will be taken to ensure Bttß _t deteriorating or detachment of the phosphate coating of the metal surface vemelden au. The aqueous solutions containing copper that are commonly used are acidic; if they are acidic, they can damage the phoepnateo layer or even remove the iron-containing metal surface. This cannot affect the deposition of copper on the surface, but it can have a very detrimental effect on the desired properties of the phosphate oversug. Therefore, the pH value of the solution containing copper must be carefully controlled. Xin a given case depends on the most favorable. pH range depending on the type of phosphate coating present - aa best eapirisen can be determined «»

A solution containing copper can be obtained by spraying, aittels Orphans, by dipping the surface in the copper-containing solution or by any other suitable method . be applied.

From the most advantageous it is Ib general to use the aqueous copper-containing solution as a Mach rinse to remove excess * phosphating solution from the phosphated iron *

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to rinse off containing metal surface »

8 pounds doesn't matter if the copper is ferrous Metal surface is deposited by means of a simple aqueous solution or by means of a phosphating solution «Ac It is generally the simplest to use the copper of the aqueous solution in the form of copper nitrate and / or copper acetate und.'oder To add copper chloride «»

However, if the copper containing solution on the metal surface is applied, care must be taken north, the copper ion concentration to be kept at the desired level in the solution. The solution containing copper must therefore be continuous or continuously analyzed / among other things to determine the copper content ,, Then a source of copper ions must be used Solution to be added so that the copper concentration in it remains within the desired limits.

A suitable method for determining the copper concentration is dia colorimetric analysis using the example "Neoouproine" (2 ₉ 9-Mnsti ^ l-1,10-pnenanthroline) as colorimetric gown. However, the copper concentration of the solution is preferably measured using a Xupfer (II) ion activity electrode, which has the further advantage that the potential difference between the copper (II) ion activity electrode and a noraal electrode, usually | a calomel electrode, can be used to operate a supply means such as a pump for supplying a copper ion source to the solution. The source of copper ions can be, for example, a concentrated solution of a suitable copper salt.

With regard to the final stages in the process according to the invention, namely the electrophoretic deposition in a light colored film and its hardening, it can be used instead of using the usual techniques any conventional, in _m '■ contain water soluble or dispersible · "resins. The for

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Use in the electrophoretic paints used preferred resins in the process of the present invention are methacrylic acid - acrylic acid, alkyd, melamine and epoxy resin * or their mixtures o Oa in the electrophoresis ^ deposition of the iron-containing metal surface, generally connected as an anode, it is desirable It is also advantageous that the electrophoretic paint used was based on an anionic resin. It is also advantageous that the paint has a solids content within the range γοη 8-17 % by weight and a pH value within the range from 7.5 to 9.5 “Electrophoretic paint application is best accomplished using a potential difference within the range of 50 to 450 volts. The current density is within the range from 1.08 to 108 A / m, at a temperature within the range from 15-36 ° C and for a period of time generally in the range from 30 seconds to 5 minutes «

After the electrophoretic deposition of the color film, the colored surface is preferably rinsed, if necessary with water. The paint film is then cured by means of a heat treatment, which preferably takes place at a temperature within the range of 148 * 205 ^° G for a period of 20-30 minutes.

It is believed that based on the above those who are familiar with electrophoretic color deposition on ferrous metal surfaces, no difficulty in carrying out the level steps in the • procedure according to the invention, but if further information is available Desired that deal with this part of the procedure will refer to the following as an example Publications referenced:

a) Bogart, Harold H., G.Lo Burnside and George E, Fo Br * who, "The Concept of Development of the Ford Electric Costing System, "Society of Automotive Engineers (preprint 998A for International Automotive Engineering Congress, Detroit, Michigan, January 11-15, 1965);

b) Burden J.F. and V.H. Guy, "The Development and Evaluation *

of Paints for Electrophoretic Deposition **, (Transactions

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of the Institute of Metal Finishing, Volume 40, 1963)? o) Gloyer SoW ₈ , Donald to Hart and Hobert E. Cutforth, "Eleotrodeposition Theory and Practice", Official Digest, February 196 $ (publication of the Federation of Societies for Faint Technology) j

d) Hutchinson O ₉ O "Some Aspects of Electrodeposited Organic Coatings ¹¹ (Products Finishing, December 1965)"

e) Hutohinson G ₀ O ₀ , "Some Aspects of Electro-Deposited Organic Coatings" (Society of Automotive Engineers Reprint 650511) "Chicago, Illinois, 17.-21." May 1965) i

f) LeBras, Louis Rn, "Electrodeposition Theory and Mechanisms * (Journal of faint Technology, Volume 38, No. 493), February 1966, and

g) "New Process Electrode poeit 3 taint ¹ ·, iroduats Finishing Staff fieport (Products Finishing, June 1964) 0

It is of course clear that the present invention also extends to objects with a ferrous metal surface, which by means of the method described here are electrophoretically colored with a light color.

In order that the invention may be more easily understood, are in the following only examples are given as explanatory awe token, su »own the invention from several sides.

Example 1,

The example shows the effect of applying copper a ferrous metal surface of coating-forming phosphating solutions on uatis from zinc or ο Zlnk / Caldum and the subsequent electrophoretical coloring of the copper-containing phosphate surface with a white color Compared to surfaces that have been treated in a similar way, except that the rhoephating solutions used does not contain copper »

Steel plates are treated as follows!

a) A first set of flats is cleaned with alkali · with water rinsed, treated with a zinc phosphating solution, rinsed with water and, finally dried,

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b) A swelter bats Flatten is banded exactly as in a),
but with the exception that the zinc phosphate solution contains 20 parts per million copper ions.

β) A third öats plate is modified exactly as in a),
however, with the exception that the zinc phosphating solution is replaced by a zinc / calcium phosphating solution

d) SIn tierte data plates are treated exactly as in c),
but with the exception that the zinc / calcium phosphating solution used contains 20 parts per Hillion of copper ions.

All four plate sets are then colored with a white enamel paint ("Ölidden 65197 tfhite Electrocoat Enamel", sold by Ölidden Company Limited, Cleveland, Ohio, V ₀ Ot ₀ AO for two minutes using a potential difference of 200 volts. BIe are then with rinsed with distilled water. Finally, the colors are hardened by heating them to around 1 ?? ° C for 20 ml.

The white of all plates is then assessed visually. The results are summarized in Table I below. In this Table I, a pure white color is rated as 1,
death is very dirty white, yellowish or light brown
Color · is rated as 10.

TABLE I
Approximately degree of whiteness

a) 10

b) 1
o) 5
d) 1

Dl · · «Results« peculiarly that the color of the produced Well colored film is far better when copper is on the beta surface according to the present invention has been deposited, compared to those obtained by prior known methods o It does not matter whether dl use \ Phosphating solution contains only zinc or zinc and Oaloiua.

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If the four sets of plates is sprayed later (sold "öherwin-Williams Kem-Faat tfhlte Baked Enamel F73W2" by the company The öherwin-Williams _Company's Chicago, Illinois, VoStoAo) with a white Einbrennemaille, the white surfaces produced are identical in appearance and there is no discernible difference in the color shade «.

Beis piele 2-8 "

These examples illustrate various methods that can be used to apply copper to a ferrous metal surface. Comparative examples are also carried out for comparative purposes Panels are pretreated by washing them in an alkaline solution and rinsing with water. In the case of Examples 2 ·· 6, in which the panels are to be treated with a phosphating solution, they are treated with a grain refiner after rinsing with water and rinsed again with barrels The electrophoretic white paint used in all Examples 2-8 is "Powercron White 20020 * from P ₀ Pd (Jc Industries Incorporated"). After electrophoretic coloring, the plates are rinsed with water in each case and finally heated to harden the paint of the electrophoretically applied color film is i In each case within the range of υ.025 - 0.033 mm _Ω

Example 2 _O

The pretreated steel plates are 1 minute with a phosphate ication solution of the following composition sprayed:

Monosodium phosphate 6.5 g / l

Sodium molybdate 0.16 gA

non-ionic wetting agent 0.64 g / l

Oxalic acid 0.32 g / 1

Sodium fluoride 0.4 g / l

Water ad 1000 cm '

pH of the solution 3 | 7 «

The electrophoresis generated on the plates phosphated in this way

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reticulate color film is yellowish-white with distinct yellowish Fleoken along the edges and yellow spots on the rest of the surface.

Example 5.

The pretreated steel plates are sprayed for 1 minute with a phosphating solution similar to that in Example 2, with the exception that the solution contains sufficient copper nitrate to provide a copper concentration of 50% per million .

The electrophoresis generated on the jtla-tten phosphated in this way The color film is bluish-white and does not show any stains

Example 4 »

The gate-treated steel plates are sprayed for 1 minute with a similar hoephatierungsiesttng as in Example 2, however «It is the exception, since sufficient copper nitrate is added, to provide a copper concentration of 10 parts per million.

The electrophoresis generated on the sheets phosphated in this way Color film is uniformly blue-white, but its bluish tom is not as pronounced as in the example 3 "-Er has no fleoken.

Example 5.

Up to the gate-treated steel plates are 1 minute with a zinc » sprayed phosphating solution of the following composition: Sink 1.5 gA

»Atrium chlorate 0.61 g / l

Sodium nitrite 0.24 g / l

* i ⁴ * 0.15 gA

Water ad 1 liter

The electrophoretic color film produced on the sheets phosphated in this way is similar to that in Example 2, although the bright white color is somewhat lighter and less fleece on the *

Surface are.

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Example 6 *

The pretreated steel plates are phosphated in exactly the same way as in Example 5, but they are then rinsed with an aqueous solution containing copper sulfate in a _{concentration of 1%} so that the solution contains 500 parts per million of copper.

The one on the phosphated in this way and by means of this process after-rinsed had electrophoretically generated · color film 1st evenly bluish-white, although a little bluish than that Late Sr produced in example 3 does not show any stains,

Example 7 »

The pre-treated steel plates for 10 seconds simply immersed in an aqueous solution of M containing copper sulphate in a concentration such that the solution of 1000 parts of copper per million ent holds ο

The electrophoretic one produced on the plates "copper-plated" in this way Color film has an appearance similar to that produced according to Example 6.

Example B ₀

The pretreated steel plates are first in the for 10 seconds in Example 7 used aqueous solution containing copper and then in the zinc phosphating solution used in Example 5 for 1 minute submerged.

The flattened on the so "coppered" and phosphated he « The color film produced has an appearance similar to that Color film produced according to Example 6.

To show that the effect of copper is peculiar to this metal and, for example, not shared by other metals of the same kind will, some pre-treated steel plate will be 1 minute with a zinc phosphating solution similar to that in Example 5 applied sprayed, but with the exception «· that they 25 part« per million silver contains "The one on which phosphated in this way ·" Plates produced «electrophoretically · Color film aside Jedooh Λη ·

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mottled surface and an appearance similar to that after Example 5 produced color film *

According to the results of Examples 2–8, it can be concluded that if the surface is not "copper-plated" before the electrophoretic paint application (as in Examples 2 and 5), the white paint films obtained have a very unsatisfactory appearance. On the other hand, when the surface before painting "coppers ¹¹ is _f, it does not Bolle, if the copper from a Fhosphatierungslösung (as in Examples 5, 4 and 6) or from a simple aqueous copper-containing solution (as in Example 7)" optionally with subsequent phosphating (as in Example 8), because the electrophoretically applied white paint film is then much better in its appearance, namely uniform in color and without any spots. As Examples 3 and 6 show, the correct paint film is the paler, the higher the amount of copper deposited on the metal surface.

Examples 9 - 15 »

These examples show the effect of zinc phosphating solutions used, the different amounts of copper contained. In each case, the flats used are standard steel plates. The order of the 12 work stages 1st as follows

1) Heinigen ait tinea strong alkaline none,

2) rinse old tap water,

3) rinsing old a »usual grain refiner,

4) one minute immersion at a temperature iron about 94.4 ⁰ C in a Pbospnatierungslöeung the following JSueajuneneetzungx

Zinc 1.5 g / l

HgPO ^ ions 7.5 «Λ Sodium chloride 0.61 gA

- Vatricity rate 0.24 s / l

Wed ⁺ * 0.15 «Λ

Copper (eieh · table II) ' Water ad 1 liter,

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5) rinse with water,

6) rinsing with chroic acid solution,

7) rinsing with demineralised water,

8) drying old prceel air,

9) Electrophoretically "staining old an electrophonic Color (»!» Owerorön fiiite .97675 *) ♦

10) rinse old tap water,

11) Rinse old water and entaineralisitrtea

12) Erhitsen, including the color is hardened.

The thickness of the applied color file is in any case within the range of 0.033-0.038 am Results are summarized in Table II below. ·

Copper length in
Example of the Phosphatie Auesehen dee Parbfilae

9 0 ppa β 1 *>, old Turkish yellow plecken

10 1 ppa eleiotaeäBie white, without spots

or other defects

11 3 ppa As in Example 10, each

but ait a bluish Ieloht tint

similar to Example 11, but about · etärker bläulioh \ y similar, Je-ite in Beiapiel 12 something otHrker bluish ähnlieh in Beiapiel 13, 4 × - dooh something bluish similar yet etärker In Example 14, yes * dooh bluish.

These examples 9-15 are convincing that they treated an electrophoretic dye with copper Plates a flawless Karbfila iron very pleasing » Look aside, while the nloht so bad

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12th 5 ppa 15th 10 ppa U 15 ppa 15th 20 ppa

acted in an unsightly, blotchy paint film In addition, Examples 9-15 also show that the blueness of the white paint film increases steadily when see the copper concentration in the phosphating solution elevated.

Example 16.

Among other things, to illustrate the invention further, a plate from commercial steel using a zinc / calcium phosphate solution containing copper and phosphated subsequently electrophoretically colored. The sequence of the working stages is as follows

1) cleaning with a strong alkaline cleaner,

2) rinse old water,

3) Kinminutiges spraying at a temperature of about 70 ⁰ C nit a zinc / Calcluaphosphatlerungslösung the following composition:

Calcium 1.0 g / l

Zinc 2.0 g / 1

HgPO ^ ions 7.0 g / l

! Titrations 4 »2 g / l

Copper (II) ions * 0.005 g / l Water ad 1 liter, A) ₉ rinsing with tap water,

5) rinse with auric acid solution,

6) rinsing with demineralized water,

7) IrooÄen with compressed air, _g Θ) JElektropboretisches staining with a white electrophoretic dye ("Poweroron White 97675") »

9) rinsing with tap water,

10) Rinse with demineralized water and

11) Keep until the paint is hardened.

The thickness of the applied color film is approximately 0.5-0.17 mm. The color film is evenly bluish-white and has no color Defectsc However, if a similar plate made of commercially available Stahl is subjected to the same procedure, but with Mer Exception that the Zlok / calcium phosphate solution does not

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Contains copper, the color film is yellowish and contains spots of darker yellow color ”. This yellow Karbe is not quite as pronounced as in Example 9 "but she eats nonetheless clear to the eye even when superficial Viewing recognizable max% Hence the appearance of the panel overall very unsightly *

Claims

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Claims (1)

Claims H)) method for the electrophoretic application of colors, especially light colors, on ferrous metal surfaces, characterized in that in a first stage the surface is treated with a solution which Contains at least a sufficient amount of copper in a soluble fora, including color irregularities in the subsequent to avoid deposited paint " 2) Method according to claim 1, characterized in that one Use a copper-containing solution in the treatment, which contains enough copper to give it a bluish tint on the other hand, to produce white flawless (spotless) color film. 3) Method according to claims 1 or 2, characterized in that that the iron-containing metal surfaces to be subjected to the treatment with an aqueous, acidic phosphating solution brings into contact, which contains a copper salt, ■ o because a phosphate coating is formed on the surface 4) Method according to claim 3 »characterized in that a so-called" coating-forming phosphate "solution is used as the phosphating solution based on zinc phosphate either with or without Galoiuiuphosphat used 5) Method according to claims 3 or 4, characterized in that the aan only evoke a white "in the electrophoretic deposited paint with a JPJiosphatierungelöeung a copper ion concentration in the range of 0.5 to 50 parts per million used. 6) Method according to claims 5-5, thereby gekennzelch ~ It is not possible to use a phosphate solution in which the Copper ion concentration does not exceed 5! Ropes per million 7) Process according to claims 3 - 6, characterized in that a used aan ^ hosphatierungslösung wherein the 109838/1505 ι * a Copper-iron concentration does not exceed 2.5 parts j. Million ", 8) Method according to claims 3 - 5 »characterized in that the nan to produce a bluish tint in the electrophoretically deposited paint a thosphating » solution is used, which has a copper ion concentration i »range of 10 to 50 parts per Killion» 9) Method according to claim 8, characterized in that one a phosphating solution with a copper ion concentration used from 20 to 50 parts per million » 10) Method according to claims 3 - 9t characterized thereby, that aan on the oxidation of iron (II) ions to iron (III) ions a phosphating solution containing a Oxidizing agents used 11) Method according to one of claims 5-10, characterized in that that the surface is exposed after contact with the tho8phatieruneelÖeung and before the deposition of the electrophoretic Color washes. Contains 12) The method of claim 11, characterized in that rinsing the surface with an aqueous rinse solution used _for the trivalent and / or hexavalent chromium ions, 13) Method according to claim 3, characterized in that one a so-called "non-coating-forming solution" is used as the phosphating solution rhosphate * ~ solution based on monosodium phosphate is used 14-) Method according to claim 13, characterized! '«Indicates that monosodium phosphate is used in a concentration in the range of 2-20 g / l. 15) Method according to claim H, characterized in that A phosphating solution containing an accelerator is used 16) Method according to claim 15, characterized gektnnseiohnet that, to use as an accelerator sodium molybdate in a? concentration 109838/1505 used in the range from 0.05 - 0.5 gA «, 17) Process according to claims 1 or 2, characterized in that the ferrous metal surface with a aqueous solution containing a dissolved copper corn in £ e ~ moves < 18) Method according to claim 17 »characterized in that a solution with a copper ion concentration in the range used from 100 to 10,000 parts per million, 19) Process according to claims 1 or 2, characterized in that a phosphated β iron-containing metal surface is used as the iron-containing metal surface and this brings into contact with an aqueous solution containing a dissolved copper corn. 20) Method according to claim 19? characterized in that before treatment with the aqueous, copper-containing solution, the iron-containing metal surface is brought ^{into contact with an aqueous, acidic phosphating solution of the "over-forming phosphate 1} * -" type based on zinc either with or without calcium "," 21) Process according to claims 19 or 20, characterized in that the aqueous, copper-containing solution for Rinse off excess phosphating solution from the phosphated ferrous metal surface used 22) Method according to one of the preceding claims, characterized in that aan as a solution containing copper
Aqueous solution uses the copper (IX) filtrate and / or copper (II) acetate and / or dissolved as Kuj> ferionsnguell *
Contains copper (II) chloride. 25) method nmoh claim 22, characterized in that- «On the determination of the copper age the copper keeping up with Solution continuously or discontinuously- analyzed and * to maintain the lupf concentration on a g · - 10S838 / 1505 desired height, a copper ion source ”added 24) Method according to claim 23, characterized in that the copper analysis is carried out colox-imetrically using "Neocuproine" (2 _T 9 ~ Mmethyl ~ 1 _e 10-phenanthroline) as a colorimetric coat * 25) Method according to claim 23, characterized in that the cupi'eranaXyee is carried out using a copper (II) ion activity electrode " 26) Method according to claim 2J>, characterized in that the potential difference between the copper (CII) ion activity electrode and a normal electrode is used and, on the basis of this JDiff, a device for adding copper ions to the solution is put into operation » 2?) Method according to one of the preceding claims, characterized characterized that nan as electrophoretic colors such used on methacrylic acid », acrylic acid, alkyd« ,. UeIaain- and / or based on epoxy resins » 28) Method according to one of the preceding claims, characterized characterized in that the electrophoretic paints used are those based on anionic resin " 29) method na ^ h one of the preceding claims, characterized characterized that one electro ^ theoretical colors with a Pesticide content in the range of 8-17 weight percent used., . 30) Method according to one of the preceding claims, characterized in that one electrophoretically ^ colors with a pH value in the range from 7.5 to 9 »5 used 31) Method according to one of the preceding claims, characterized in that the application of the slektrophoretisohsn paint is carried out using a potential difference "in the range of 50-450 volts " 109838/1505 32) Method according to the preceding claims »characterized in that the electrophoretically * deposition of the color is carried out at a current density in the range from 1.08 to 106 A / m ² « 33) Method according to one of the preceding claims, characterized in that the electrophoretic deposition of the paint is carried out at a temperature in the range of 15-35 6 ^° C. 34) Method according to one of the preceding claims, characterized characterized in that the electrophoretic deposition of the dye is carried out in a time of 30 seconds to 5 minutes., 35) Method according to one of the preceding claims, characterized in that the colored surface is rinsed after the electrophoretic deposition of the paint « 36) Method according to one of the preceding claims, characterized in that the DMR by elektrophoretisohen deposition color subjecting the colored surface to cure the color of a heat treatment " 37) Method according to claim 36, characterized in that the heat treatment is carried out at a temperature in the range of ^{148-205 0} O for a period of 20-30 minutes. 109838/1505