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EP0783379A1 - Traitement destine a l'amelioration de la resistance a la corrosion des revetements autodeposes sur des surfaces metalliques - Google Patents

Traitement destine a l'amelioration de la resistance a la corrosion des revetements autodeposes sur des surfaces metalliques

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Publication number
EP0783379A1
EP0783379A1 EP95933063A EP95933063A EP0783379A1 EP 0783379 A1 EP0783379 A1 EP 0783379A1 EP 95933063 A EP95933063 A EP 95933063A EP 95933063 A EP95933063 A EP 95933063A EP 0783379 A1 EP0783379 A1 EP 0783379A1
Authority
EP
European Patent Office
Prior art keywords
group
vinyl
total weight
weight percent
symbol
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP95933063A
Other languages
German (de)
English (en)
Other versions
EP0783379A4 (fr
Inventor
Oscar E. Roberto
Shawn E. Dolan
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Henkel Corp
Original Assignee
Henkel Corp
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Filing date
Publication date
Application filed by Henkel Corp filed Critical Henkel Corp
Publication of EP0783379A1 publication Critical patent/EP0783379A1/fr
Publication of EP0783379A4 publication Critical patent/EP0783379A4/fr
Withdrawn legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
    • B05D7/14—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to metal, e.g. car bodies
    • B05D7/142—Auto-deposited coatings, i.e. autophoretic coatings
    • B05D7/144—After-treatment of auto-deposited coatings

Definitions

  • Tnis invenuon relates to the treatment of autodeposited coatings in order to retain longer or to enhance the corrosion resistance provided by the coatings on metallic sur ⁇ faces, particularly ferriferrous articles, including zinc coated (also called “galvanized”) steel.
  • Autodeposition is a generic term used to describe the deposition of a subs t antially uniform organic binder containing film on a metal surface, generally preferably pre- cleaned, without the use of externally imposed electric current in the deposition process
  • Autodeposition involves the use of an aqueous coating composition containing dispersed
  • organic resin usually at relatively low solids concentration such as 5 to 12 %, normally less than 10 %, to form a coating of relatively high solids concentration, usually greater than 10 %, on a metallic surface immersed therein, with the coating increasing in thick ⁇ ness and mass the longer the time that the metallic surface is immersed in the coating composition. Because the autodeposition process is driven chemically, rather than elec-
  • autodepositing compositions are aqueous acid solutions having solid resin particles dispersed therein in very finely divided form.
  • the coating formed while the metal substrate used is immersed in the bath is generally wet and fairly weak, although sufficiently strong to maintain itself against gravity and moderate spraying forces. In this state the coating is described as "uncured”.
  • the uncured coating is dried, usually with the aid of heat. The coating is then described as "cured”.
  • Basic constituents of an autodepositing composition are water, resin solids dis ⁇ persed in the aqueous medium of the composition, and activator, that is, an ingredient or ingredients which convert the composition into one which will form on a metallic surface a resinous coating which increases in thickness or areal density as long as the surface is immersed in the composition.
  • activator that is, an ingredient or ingredients which convert the composition into one which will form on a metallic surface a resinous coating which increases in thickness or areal density as long as the surface is immersed in the composition.
  • activator that is, an ingredient or ingredients which convert the composition into one which will form on a metallic surface a resinous coating which increases in thickness or areal density as long as the surface is immersed in the composition.
  • the activating system generally comprises an acidic oxidizing system, for example: hydrogen peroxide and HF; HN0 3 ; a ferric ion containing compound and HF; and other combinations of (i) soluble metal containing compounds such as, for example, silver fluoride, ferrous oxide, cupric sulfate, cobaltous nitrate, silver acetate, ferrous phosphate, chromium fluoride, cadmium fluoride, stannous fluoride, lead dioxide, and silver nitrate, in an amount between about 0.025 and about 50 grams per liter (hereinafter often abbreviated as "g L"), with (ii) one or more acids such as hydrofluoric, sulfuric, hydrochloric, nitric, and phosphoric acids and organic acids such as, for example, acetic, chloroacetic, and trichloroacetic acids.
  • an acidic oxidizing system for example: hydrogen peroxide and HF; HN0 3 ; a
  • Autodeposition composition can be used to form coatings which have good aes ⁇ thetic properties and which protect the underlying metallic substrate from being degrad ⁇ ed, e.g., corroded by water. Many applications however require the autodeposited coat ⁇ ing have particularly good properties for use.
  • Various means have been developed to i - prove the properties of autodeposited coatings including:
  • chromium containing compounds in post-treatment raises a disposal and environmental problem or disadvantage because the chromium must first be removed or otherwise treated before disposal to waste.
  • One object of the present invention is to provide a process which includes a reaction rinse which will retain, or improve, the corrosion resistance properties of the autodeposited coating while employing non-chromium containing materials which are environmentally acceptable, raising no disposal problems,
  • a further object of the present invention is to provide a single reaction rinse for coatings on a variety of metal substrates, paricularly on both cold rolled steel and galva ⁇ nized steel. In this way a single reaction rinse may be used for composite objects that contain two or more distinct types of metal surface areas and autodeposited coatings thereon, so that simultaneous processing of such composite objects can be more efficient - ly carried out.
  • percent, "parts of, and ratio values are by weight;
  • the term “polymer” includes “oligomer”, “copoly- mer”, “terpolymer”, and the like;
  • the description of a group or class of materials as suit- able or preferred for a given purpose in connection with the invention implies that mix ⁇ tures of any two or more of the members of the group or class are equally suitable or pre ⁇ ferred;
  • description of constituents in chemical terms refers to the constituents at the time of addition to any combination specified in the description, and does not necessarily preclude chemical interactions among the constituents of a mixture once mixed;
  • speci ⁇ fication of materials in ionic form implies the presence of sufficient counterions to produce electrical neutrality for the composition as a whole (any counterions thus impli- citly specified should preferably be selected from among other constituents explicitly specified in ionic form, to the extent possible; otherwise such counterions may be freely selected, except for avoiding counterions that act adversely to the objects of the inven ⁇ tion); and the
  • the corrosion resistance of a metal substrate coated with a dried and optionally cured autodeposited coating is improved from the level that would be achieved by rinsing the wet, uncured autodeposited coating with plain water, by treating the uncured coating on the metallic substrate with an aqueous rinse so ⁇ lution that comprises, preferably consists essentially of, or still more preferably consists of, water and anions that consist of (i) at least four fluorine atoms and (ii) at least one atom of an element selected from the group consisting of titanium, zirconium, hafnium, silicon, and boron and, optionally, (iii) one or more oxygen atoms; the rinse solution may also contain other ingredients, for such purposes as pH adjustment, or in general any other ingredients that do not act adversely to the objects of the invention.
  • the anions may be introduced into the rinse solution by addition of the corresponding acids or of salts including the anions; in either case, the stoichiometric equivalent as the specified anions is considered for the purposes of this description to be present when any such ma- terial is dissolved in a treatment rinse solution, irrespective of the actual degree of ioni- zation in the solution.
  • a process according to this invention preferably is like those of prior art autodeposition processes.
  • the metal substrate is prefer ⁇ ably cleaned, generally using an alkaline, commercially available cleaner.
  • the cleaning is carried out by spraying, immersion or any other effective method or combination of methods, after which the coated workpiece preferably is rinsed with water to remove any residual cleaning solution, prior to deposition of the coating.
  • the autodeposited film is preferably applied by immersion of the substrate into a coating bath containing the desired polymer latex, emulsion or dispersion for a time sufficient to coat the substrate with a wet film thickness that preferably is, with increasing preference in the order given, at least 2, 4, 5, 6.0, 6.5, 6.8, 7.1, 7.4, 8.0, 9.0, 10, 11, 12, 13, 14, or 15 micrometers (here ⁇ inafter often abbreviated " ⁇ ") and independently preferably is, with increasing preference in the order given, not more than 50, 40, 30, 28, 27, 26, or 25 ⁇ .
  • the time and tem ⁇ perature during autodeposition will vary depending on the nature of the particular resins in the coating.
  • a reaction rinse is applied in the present invention to improve the corrosion resistance of the later formed cured coating.
  • the chemical composition of the autodeposition bath may be selected without limit from all the compositions that produce coatings useful for any purpose, in particular including those compositions taught in U. S. Patents 3,585,084, 3,709,743, 3,776,848, 4,180,603, 4,191,676, 4,313,861, 4,347, 172, 4,366, 195, 4,657,788, all of which, to the extent that they describe compostions suitable for autodeposition baths and are not incon ⁇ sistent with any explicit statement herein are hereby incorporated herein by reference.
  • Preferred coatings which are treated according to the process of the present inven ⁇ tion are formed from an autodepositing composition in which particles of resin are dis- persed in an aqueous acidic solution which is prepared by combining hydrofluoric acid and a soluble ferric iron-containing ingredient, most preferable ferric fluoride.
  • U.S. Patent Nos. 4,347,172 and 4,411,937 which disclose the preferred activating system disclose the optional use in the composition of an oxidizing agent in an amount to provide from about 0.01 to about 0.2 oxidizing equivalent per liter of composition.
  • suitable oxidizing agents are hydrogen peroxide, dichromate, permanganate, nitrate, persulfate, perborate, p-benzoquinone and p-nitrophenol. Hydrogen peroxide is most prefe ed.
  • one preferred class can be prepared by copolymerizing (A) vinyli- dene chloride monomer with (B) monomers such as methacrylic acid, methyl methacryl- ate, acrylonitrile, and vinyl chloride and (C) a water soluble ionic material such as sodi ⁇ um sulfoethyl methacrylate.
  • A vinyli- dene chloride monomer
  • B monomers such as methacrylic acid, methyl methacryl- ate, acrylonitrile, and vinyl chloride
  • C a water soluble ionic material such as sodi ⁇ um sulfoethyl methacrylate.
  • R-Z-Q-(S0 3 )-NT wherein the moiety "R” is selected from the group consisting of vinyl and substi ⁇ tuted vinyl, for example, alkyl-substituted vinyl; the symbol “Z” represents a di- functional linking group which will activate the double bond in the vinyl group; -Q- is a divalent hydrocarbon moiety having its valence bonds on different carbon atoms; and the symbol “rVT” represents a cation. Examples of resins prepared from such monomers are disclosed in U.S. Patent No.
  • the relatively hydrophilic monomers of (2) above include those materials which are readily copolymerizable with (1) in aqueous dispersion, that is, which copolymerize within a period of about 40 hours at a temperature ranging from the freezing point of the monomeric serum up to about 100 ° C, and which have a solubility in both the water and the oil phase of the polymer latex of at least 1 weight percent at the temperature of po ⁇ lymerization.
  • Exemplary of preferred materials, particularly when used in conjunction with monomeric vinylidene chloride, are methacrylic acid and methyl methacrylate.
  • Oth ⁇ er monomers which may be advantageously employed include the hydroxyethyl and propyl acrylates, hydroxyethylmethacrylate, ethyl hexylacrylate, acrylic acid, acryloni- trile, methacrylonitrile, acrylamide, and the lower alkyl and dialkylacrylamides, acrolein, methyl vinyl ketone, and vinyl acetate.
  • These monomers which can be employed in amounts of from 0.5 to 30 weight percent, based on the total weight of the nonionic monomers used, provide for the neces ⁇ sary reactivity with the copolymerizable ionic material of (3) and also provide for the re ⁇ quired water solubility of the interpolymer in water. Thus, such materials may be re- ferred to as "go-between" monomers. It is to be understood that the optimum amount of such relatively hydrophilic monomers may vary somewhat within the prescribed range depending upon the amount of hydrophobic monomer used in preparing the resin, as well as upon the amount and type of the copolymerizable ionic monomer used.
  • the copolymerizable ionic monomers used in preparing the aforementioned type resins are those monomeric materials which contain in their structure both an ionizable group and a reactive double bond, are significantly soluble in water, are copolymerizable with the hydrophilic monomer constituent (2) and in which the substituent on the double bond is chemically stable under the conditions normally encountered in emulsion polym ⁇ erization,
  • Examples of the aforementioned divalent hydrocarbon moiety Q having its val ⁇ ence bonds on different carbon atoms include alkylene and arylene divalent hydrocarbon moieties.
  • the alkylene group can contain up to about 20 carbon atoms, it pref ⁇ erably has 1 to about 8 carbon atoms.
  • the solubility of the defined copolymerizable ionic material as described herein is strongly influenced by the cation M * .
  • Exemplary cations are the hydrated protons characterstic of aqueous free acids, alkali metal ions, ammonium, sulfonium and substi ⁇ tuted ammonium and sulfonium ions, including quaternary ammonium ions
  • Preferred are the free acids, alkali metals, particularly sodium and potassium, and ammonium.
  • the solubility of the monomer depends on Q.
  • this group can be either aliphatic or aromatic and its size will determine the hydrophilic/ hydrophobic balance in the molecule, that is, if Q is relatively small, the monomer is water soluble, but as Q be ⁇ comes progressively larger, the surface activity of such monomer increases until it be ⁇ comes a soap and ultimately a water insoluble wax.
  • the limiting size of Q depends on R, Z, and NT.
  • sodium sulfoethyl methacrylate is a highly acceptable copolymerizable ionic material for use in the present invention. Further, the selection of R and Z is governed by the reactivity needed, and the se ⁇ lection of Q is usually determined by the reaction used to attach the sulfonic acid to the base monomer (or vice versa).
  • Latexes are known, such latexes being commercially available and being referred to herein as "self- stabilizing latexes", that is, latexes, the polymeric particles of which contain in the poly ⁇ mer molecule functional groups that are effective in maintaining the polymeric particles dispersed in the aqueous phase of the latex.
  • self- stabilizing latexes that is, latexes, the polymeric particles of which contain in the poly ⁇ mer molecule functional groups that are effective in maintaining the polymeric particles dispersed in the aqueous phase of the latex.
  • such latexes do not re ⁇ quire the presence of an external surfactant to maintain the particles in their dispersed state.
  • Latexes of this type generally have a surface tension very close to that of water (about 72 dynes/cm). It has been observed that autodepositing compositions containing such latexes form coatings which build up at a relatively fast rate.
  • An exemplary method for preparing such latexes involves preparation of an aque ⁇ ous dispersion by an essentially continuous, carefully controlled addition of the requisite polymerization constituents (including polymerization initiator systems, if desired) to the aqueous medium having the desired pH value, followed by the subsequent addition of the necessary polymerization initiator, to form a polymeric seed latex in order to aid in the control of particle size.
  • the requisite polymerization constituents including polymerization initiator systems, if desired
  • very small amounts of conventional surfactants such as alkali soaps or the like, may be incorporated in the aqueous medium to further aid in the attainment of particles of desired size.
  • Such latexes com ⁇ bine the highly beneficial properties of optimum colloidal stability, reduced viscosities at relatively high polymer solids content, low foaming tendencies, and excellent product uniformity and reproducibility.
  • Such highly stable latexes which are internally stabilized are disclosed, for example, in U.S. Patent No. 3,617,368.
  • One preferred embodiment of this invention comprises the use of vinylidene chloride-containing latexes in which a water soluble ionic material such as, for example, sodium sulfoethyl methacrylate is copolymerized with the comonomers comprising the copolymer.
  • a water soluble ionic material such as, for example, sodium sulfoethyl methacrylate
  • Sodium sulfoethyl methacrylate is particularly effective for use with mono ⁇ meric vinylidene chloride and the relatively hydrophilic monomers methyl methacrylate or methacrylic acid when used in the amounts and in the manner called for by the present invention.
  • Latexes for use in this invention are latexes with about 35 to about 60 weight % solids comprising a polymeric composition prepared by emulsion polymerization of vinylidene chloride with one or more comonomers selected from the group consisting of vinyl chloride, acrylic acid, a lower alkyl acrylate (such as methyl acrylate, ethyl acrylate, butyl acrylate), methacrylic acid, methyl methacrylate, acryloni- true, methacrylonitrile, acrylamide, and methacrylamide and stabilized with sulfonic acid or sulfonic acid salt of the formula R-Z-(CH 2 ) n -(SO 3 ) " M * , wherein R represents vinyl or lower alkyl-substituted vinyl, Z represents one of the difunctional groups: O O O O O
  • T represents hydrogen or an alkyl group
  • n is an integer from l to 20, preferably l to 6
  • M * is hydrogen or an alkali metal cation, preferably sodium or potassium.
  • One subgroup of preferred polymers are those having at least 50 % by weight of vinylidene chloride, but less than 70 % , 5 to 35 % vinyl chloride, and 5 to 20 % of a vinyl compound selected from the group consisting of acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, methacrylic acid, methyl methacrylate, acrylonitrile, methacrylo ⁇ nitrile, acrylamide and methacrylamide, and combinations thereof, and 1 to 3 % by weight of sulfoethyl methacrylate.
  • Latexes are latexes containing about 30 to about 70 % of solids formed by emulsion polymerization of about 50 to about 99
  • % more preferably at least 80 %, of vinylidene chloride, based on total weight of poly ⁇ mer, and about 0.1 to about 5 % by weight of sulfoethyl methacrylate, with optionally other comonomers selected from the group consisting of vinyl chloride, acrylic and methacrylic monomers such as acrylonitriles, acrylamides, methacrylamides and mixtures thereof in amounts between about 5 and about 50 % by weight, and substantially free of unpolymerized surfactant or protective colloid.
  • the vinylidene chloride copolymer is crystalline in nature. Exemplary crystalline resins are described in U.S. Patent No. 3,922,451 and aforementioned U.S. Patent No. 3,617,368 In general, crystalline vinylidene chloride-containing resins have a relatively high pro ⁇ portion of vinylidene chloride, for example, at least about 80 % thereof.
  • Internally stabilized polymers or resins include as part of their chemical structure a surfactant group which functions to maintain polymer particles or resin solids in a dis- persed state in an aqueous medium, this being the function also performed by an "extern ⁇ al surfactant", that is, by a material which has surface-active properties and which is ab ⁇ sorbed on the surface of resin solids, such as those in colloidal dispersion.
  • an external surfactant tends to increase the water sensitivity of coatings formed from aqueous resin dispersions containing the same and to adversely affect de- sired properties of the coatings.
  • an undue amount of surfactant in autodepositing compositions can deter the build-up of resin particles on the metallic surface being coated.
  • the presence of undue amounts of surfactant can also adversely affect desired coating properties, for example, corrosion resistant properties.
  • An advantage of internally stabilized vinylidene chloride- containing polymers is that stable aqueous dispersions, including acidic aqueous disper ⁇ sions of the type needed for autodepositing compositions, can be prepared without utiliz ⁇ ing external surfactants.
  • surfactant is intended to be synonymous with the aforementioned.
  • Various types of internally stabilized vinylidene chloride-containing polymers are known and species thereof are available commercially.
  • examples of such latexes are the SARANTM latexes such as, for example, SARANTM 143 and SARANTM 1 12 available from Hampshire Chemical Corp., Lexington, Massachusetts, USA and the SERFENETM latexes available from Morton Chemical.
  • SARANTM latexes such as, for example, SARANTM 143 and SARANTM 1 12 available from Hampshire Chemical Corp., Lexington, Massachusetts, USA and the SERFENETM latexes available from Morton Chemical.
  • these commercial latexes can be used to excellent advantage, and internally stabilized latexes in general are preferred.
  • Various surfactants which function to maintain polymeric particles in dispersed state in aqueous medium include organic compounds which contain ionizable groups in which the anionic group is bound to the principal organic moiety of the compound, with the cationic group being a constituent such as, for example, hydrogen, an alkali metal, and ammonium.
  • exemplary anionic groups of widely used surfact ⁇ ants contain sulfur or phosphorous, for example, in the form of sulfates, thiosulfates, sul- fonates, sulfinates, sulfaminates, phosphates, pyrophosphates and phosphonates.
  • Such surfactants comprise inorganic ionizable groups linked to an organic moiety.
  • the most widely used method for preparing such resins will involve reacting vinylidene chloride with a monomeric surfactant and optionally one or more other monomers.
  • the monomeric surfactant comprises a material which is polymerizable with monomeric vi ⁇ nylidene chloride or with a monomeric material which is polymerizable with monomeric vinylidene chloride and which is ionizable in the reaction mixture and in the acidic aque ⁇ ous medium comprising an autodepositing composition.
  • resin for use in this invention are: disper- sions of copolymers of 50 to 90 % of butyl acrylate and 1 to 2 % by weight of sulfoethyl methacrylate based on the total weight of polymer; latexes of vinylidene chloride-con ⁇ taining polymers internally stabilized with sulfoethyl methacrylate and free of other surfactant, and including optionally vinyl chloride and one or more acrylic comonomers; vinylidene chloride-containing copolymer having 15 to 20 % of vinyl chloride, 2 to 5 % butyl acrylate, 3 to 10 weight % acrylonitrile, and 1 to 2 % of sulfoethyl methacrylate.
  • This particular copolymer will have less than 70 % by weight of vinylidene chloride copolymer based upon total weight of comonomers (including the sulfoethyl methacryl ⁇ ate) used in the emulsion polymerization.
  • the concentration of the resin in the coating composition can vary over a wide range.
  • the lower concentration limit of the resin particles in the composition is dictated by the amount of resin needed to provide sufficient material to form a resinous coating.
  • the upper limit is dictated by the amount of resin particles which can be dispersed in the acidic aqueous composition. In general, the higher the amount of resin particles in the composition, the heavier the coating formed, other factors being the same.
  • coating compositions can be formulated with a range of about 5 to about 550 grams per liter (hereinafter often abbreviated "g/L") of resin solids, the amount of the resin solids will tend to vary depending on the other ingredients comprising the composition and also on the specific latex or resin used.
  • the concentration of binder resin solids in an autodeposition composition or bath used as part of a process according to this in ⁇ vention preferably is, with increasing preference in the order given, at lease 0.5, 1.0, 2.0, 3.0, 3.5, 4.0, 4.5, 4.7, or 4.9 % and indenpendently preferably is, with increasing prefer- ence in the order given, not more than 40, 30, 20, 17, 14, 12, 11, 10.5, or 10.0 %.
  • Optional ingredients can be added to the composition as desired.
  • suit ⁇ able pigments can be included in the composition.
  • pigments that can be used are carbon black, phthalocyanine blue, phthalocyanine green, quinacridone red, ben- zidene yellow, and titanium dioxide.
  • the pigment should be added to the composition in an amount which imparts to the coating the desired color and/or the desired depth or degree of hue. It should be understood that the specific amount used will be governed by the specific pigment used and the color of coating desired. Excellent results have been achieved by using the aqueous dispersion in an amount such that the composition contains about 0.2 to about 3 g of furnace black/100 g of resin solids.
  • pigments are available in aqueous dispersions which may include surfact ⁇ ants or dispersing agents for maintaining the pigment particles in dispersed state
  • surfact ⁇ ants or dispersing agents for maintaining the pigment particles in dispersed state
  • they should be selected so that the surfactant concen- tration in the aqueous phase of the composition is below the critical micelle concentration ("CMC"), preferably below the surfactant concentration which corresponds to the inflec ⁇ tion point on a graph of surface tension versus the logarithm of surfactant concentration in the composition.
  • CMC critical micelle concentration
  • a suitable pigmented composition is illustrated in examples herein.
  • Colored coatings can be produced also by the use of dyes, examples of which in- elude rhodamine derived dyes, methyl violet, safranine, anthraquinone derived dyes, nig- rosine, and alizarin cyanine green. These are but a few examples of dyes that can be used.
  • dyes examples of which in- elude rhodamine derived dyes, methyl violet, safranine, anthraquinone derived dyes, nig- rosine, and alizarin cyanine green.
  • additives that may be used in the autodepositing composition are those generally known to be used in formulating paint compositions, for example, UV stabilizers, viscosity modifiers, etc.
  • the total amount of sur ⁇ factant in the aqueous phase of the composition should be maintained below the CMC.
  • the aqueous phase of the composition contains little or no surfactant.
  • the preferred surfactants are anionic.
  • suitable anionic surfactants are the alkyl, alkyl/aryl or naphthalene sul- fonates, for example, sodium dioctylsuifosuccinate and sodium dodecylbenzene sulfon- ate.
  • the constituents thereof can be ad ⁇ mixed in any suitable way, for example, as described in U. S. Patent No. 4,191,676.
  • the bath be prepared by admixing:
  • an aqueous concentrate comprising about 350 to about 550 g/l of resin particles, preferable the aforementioned vinylidene chloride-containing resin particles, and about 10 to about 550 g/l of pigment;
  • aqueous concentrate prepared from about 0.4 to about 210 g/l of HF and a water soluble ferric-containing compound in an amount equivalent to about 1 to about 100 g/l of ferric iron.
  • the bath can be prepared by stirring water into concentrate (A) and thereafter admixing therewith the required amount of concentrate (B) with stirring to provide a homogenous composition.
  • the complex fluoride anions required in a reaction rinse according to the inven ⁇ tion are preferably added to the treatment solution in the form of nickel, ferric, or cobalt salts, more preferably cobalt salts, and the anions themselves are preferably fluoborate (i.e., BF 4 ), fluosilicate (i.e., SiF 2 ), fluotitanate (i.e., TiF 6 "2 ), or fluozirconate (i.e., ZrF 6 -2 ) with the latter most preferred.
  • fluoborate i.e., BF 4
  • fluosilicate i.e., SiF 2
  • fluotitanate i.e., TiF 6 "2
  • fluozirconate i.e., ZrF 6 -2
  • the concentration of the total of the complex fluoride anions present in the aque ⁇ ous liquid rinse composition used according to the invention preferably is, with increas ⁇ ing preference in the order given, at least 0.002, 0.004, 0.008, 0.016, 0.023, 0.033, 0.040, 0.047, 0.054, 0.061, or 0.068 moles per liter ("M") and independently preferably is, with increasing preference in the order given, not more than 1.0, 0.7, 0.4, 0.20, 0.15, 0.100, 0.090, 0.080, 0.075, or 0.072 M.
  • the pH of the rinse soluition used according to this in ⁇ vention preferably is, with increasing preference in the order given, not less than 1.0, 1.5, 1.8, 2.0, 2.5, 3.0, 3.1, 3.2, 3.3, 3.4, or 3.5 and independently preferably is, with increasing preference in the order given, not more than 9, 8, 7.0, 6.5, 6.0, 5.8, 5.6, 5.4, 5.2, 5.0, 4.9, 4.8, 4.7, 4.6, or 4.5.
  • the rinse solution may be contacted, according to the invention, with a wet un ⁇ cured autodeposited coating by any convenient method or combination of methods, such as spraying, curtain coating, or immersion, with the latter normally preferred.
  • a wet un ⁇ cured autodeposited coating by any convenient method or combination of methods, such as spraying, curtain coating, or immersion, with the latter normally preferred.
  • the time of contact between the rinse solution and the wet uncured autodepositied coating is, with increasing preference in the order given, not less than 5, 10, 20, 30, 40, 45, 50, 55, or 60 seconds (hereinafter often abbreviated "sec") and independently preferably is, with increasing preference in the order given, not more than 600, 400, 200, 120, 110, 100, 95, or 90 sec.
  • the temperature of the rinse solution during contact with a wet un ⁇ cured autodeposited coating may be any temperature at which the rinse solution is liquid but normally preferably is, with increasing preference in the order given, not less than JO, 15, 18, or 20 ° C and independently preferably is, with increasing preference in the order given, not more than 60, 45, 35, 30, 27, 25, or 23 ° C.
  • the wet autodeposited coating as modified by contact with the reaction rinse is sometimes rinsed again with water, preferably deionized water if any, before being dried and, if desired as is usually preferred, cured by heatingat an elevated temperature so selected that the protective properties of the coating are fully developed but not adversely affected.
  • the temperature and time of treatment will depend on the nature of the particular resin in the autodeposited coating and the thickness of the coating.
  • the autodeposited coatings preferably are heated to a temperature that is, with increasing preference in the order given, at least 22, 30, 40, 50, 60, 70, 80, 90, 100, 1 10, or 120 ° C and independently preferably is, with increasing preference in the order given, not more than 200, 180, 160, 150, 140, 135, 130, 128, or 126 ° C.
  • Times of heating for cur ⁇ ing preferably range from 5 seconds up to 30 minutes, dependent on the mass of the coat- ed article.
  • the coating is heated for a period of time until the metallic sub ⁇ strate has reached the temperature of the heated environment, typically in a forced air baking oven.
  • the dried, cured coated articles are found to have excellent corrosion resistance when tested in soak tests or the neutral salt spray ("NSS") test, such as ASTM B- 1 17 and scab corrosion cycles.
  • NSS neutral salt spray
  • Autodeposited coatings treated according to the present invention are particularly effective on both cold rolled steel and galvanized steel, thereby allowing the two types to be processed together.
  • Example I This example illustrates the preparation of a metallic surface having an autode- posited resinous coating.
  • the metallic surface comprised steel panels, both cold rolled steel (CRS) and zinc galvanized steel (GS) panels, which were cleaned with a conven ⁇ tional alkaline cleaner composition and rinsed with water prior to being coated by immer ⁇ sion in the autodepositing composition at ambient temperature (about 21 ° C) for about 90 seconds.
  • the autodepositing immersion bath had the following composition: 60 grams per liter (hereinafter abbreviated as "g/L") of internally stabilized copolymer of vinylidene chloride, 2.5 g/L of carbon black, 0.4 g L of HF, 1.5 g/L of ferric iron, and the balance water.
  • g/L 60 grams per liter
  • Example 2 the uncured coated panels from example 1 are treated with a re- action rinse immersion bath after first being rinsed with water.
  • the reaction rinse with ⁇ out cobalt cations contained 0.5 % by weight of H j ZrFg and was adjusted to the pH shown in the following tables with ammonia if needed.
  • the concentration is shown in the tables below; the pH was 3.5 for all the concentrations shown.
  • the panels were then rinsed with water (deionized) and the panels were then cured for 20 minutes in an oven at a temperature of 105° C.
  • Example 3 This example illustrates the results of corrosion resistance testing of various pan ⁇ els.
  • Table 1 below illustrates salt spray performance and cyclic scab performance on galvanized steel, and Tables 2 - 7 indicate performance on other tests as noted.
  • the letters "GM” and the numbers and letters immediately following these letters in the headings of Tables 2 - 7 refer respectively to the General Motors Corporation and to various specific corrosion tests that are part of performance specifications at that company. Test details are readily available from General Motors. Briefly, the tests reported here are described as follows: 1. Cyclic Corrosion - GM 951 IP
  • the samples are treated at 25°C. and 50 % RH environment for 8 hours, including 4 sprays at 90 minutes intervals with a solution containing 0.9 % NaCl, 0.1 % CaCl f c and 0.25 % NaHCO 3 in deionized water.
  • the samples are then sub ⁇ jected to an 8 hour fog, 100 % RH at 40° C, followed by 8 hours at 60° C and less than 20 % RH.
  • the entire treatment is repeated for the desired number of cycles, usually 40 cycles.
  • the samples are (1) held in a freezer at -30° C for 2 hours, fol ⁇ lowed by ambient conditions for 2 hours and subsequently (2) in an oven at 70° C for 2 hours.
  • the samples are then (3) subjected to a 5 % NaCl solution salt spray for 2 hours and then (4) held in a humidity chamber at 38° C and 95 % RH for 64 hours.
  • the sam ⁇ ples are then (5) held in an oven at 60° C for 1 hour followed by (6) a freezer at -30° C for 30 minutes.

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Wood Science & Technology (AREA)
  • Paints Or Removers (AREA)
  • Physical Vapour Deposition (AREA)
  • Chemical Treatment Of Metals (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
  • Paper (AREA)

Abstract

Procédé d'amélioration de la résistance à la corrosion des revêtements autodéposés sur les surfaces métalliques, consistant à mettre le revêtement non durci appliqué sur la surface métallique en contact avec une solution de rinçage de réaction renfermant des anions de fluorure complexes. Selon le procédé de réalisation préférentiel, du fait que les propriétés protectrices des revêtements autodéposés sont améliorées aussi bien pour l'acier laminé à froid que pour l'acier galvanisé, l'un et l'autre peuvent être traités simultanément, ce qui comporte des avantages sur les plans pratique et économique.
EP95933063A 1994-09-30 1995-09-18 Traitement destine a l'amelioration de la resistance a la corrosion des revetements autodeposes sur des surfaces metalliques Withdrawn EP0783379A4 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US31643794A 1994-09-30 1994-09-30
US316437 1994-09-30
PCT/US1995/011404 WO1996010461A1 (fr) 1994-09-30 1995-09-18 Traitement destine a l'amelioration de la resistance a la corrosion des revetements autodeposes sur des surfaces metalliques

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EP0783379A1 true EP0783379A1 (fr) 1997-07-16
EP0783379A4 EP0783379A4 (fr) 2000-02-16

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EP (1) EP0783379A4 (fr)
JP (1) JPH08173901A (fr)
CN (1) CN1159775A (fr)
AU (1) AU691668B2 (fr)
BR (1) BR9509053A (fr)
CA (1) CA2199983A1 (fr)
MX (1) MX9702065A (fr)
TW (1) TW308611B (fr)
WO (1) WO1996010461A1 (fr)
ZA (1) ZA958251B (fr)

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DE19635616C1 (de) * 1996-09-03 1997-09-18 Herberts Gmbh Verfahren zur Mehrschichtlackierung
DE19635615C1 (de) * 1996-09-03 1997-09-18 Herberts Gmbh Verfahren zur Mehrschichtlackierung
DE102005023728A1 (de) 2005-05-23 2006-11-30 Basf Coatings Ag Lackschichtbildendes Korrosionsschutzmittel und Verfahren zu dessen stromfreier Applikation
JP5176337B2 (ja) * 2006-05-12 2013-04-03 株式会社デンソー 皮膜構造及びその形成方法
DE102006053291A1 (de) * 2006-11-13 2008-05-15 Basf Coatings Ag Lackschichtbildendes Korrosionsschutzmittel mit guter Haftung und Verfahren zu dessen stromfreier Applikation
DE102007012406A1 (de) 2007-03-15 2008-09-18 Basf Coatings Ag Verfahren zur Korrosionsschutzausrüstung metallischer Substrate
DE102009007633B4 (de) 2009-02-05 2013-09-26 Basf Coatings Ag Mehrstufiges Verfahren zur Lackierung metallischer Substrate
DE102009007632A1 (de) 2009-02-05 2010-08-12 Basf Coatings Ag Beschichtungsmittel für korrosionsstabile Lackierungen
DE102009029334A1 (de) * 2009-09-10 2011-03-24 Henkel Ag & Co. Kgaa Zweistufiges Verfahren zur korrosionsschützenden Behandlung von Metalloberflächen
WO2011061784A1 (fr) * 2009-11-17 2011-05-26 日本パーカライジング株式会社 Liquide de traitement de surface pour revêtement par autodéposition d'un matériau à base de fer et/ou à base de zinc et procédé de traitement de surface
DE102010019245A1 (de) 2010-05-03 2012-01-19 Basf Coatings Gmbh Verfahren zur autophoretischen Beschichtung, Beschichtungsmittel und Mehrschichtlackierung
EP4310223A1 (fr) 2022-07-18 2024-01-24 Henkel AG & Co. KGaA Rinçage par réaction alcaline pour revêtements autophorétiques décoratifs

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US4030945A (en) * 1966-06-01 1977-06-21 Amchem Products, Inc. Rinsing coated metallic surfaces
US4800106A (en) * 1987-06-19 1989-01-24 Amchem Products, Inc. Gloss enhancement of autodeposited coatings
EP0825280A3 (fr) * 1991-08-30 1998-04-01 Henkel Corporation Procédé de traitement de métaux à l'aide d'une composition aqueuse acide pratiquement exempte de chrome (VI)

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Title
No further relevant documents disclosed *
See also references of WO9610461A1 *

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BR9509053A (pt) 1997-09-30
CA2199983A1 (fr) 1996-04-11
MX9702065A (es) 1997-06-28
AU691668B2 (en) 1998-05-21
JPH08173901A (ja) 1996-07-09
EP0783379A4 (fr) 2000-02-16
TW308611B (fr) 1997-06-21
AU3585695A (en) 1996-04-26
ZA958251B (en) 1996-04-24
CN1159775A (zh) 1997-09-17
WO1996010461A1 (fr) 1996-04-11

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