MXPA98001697A - Treatment of previous coating conditioner for autodeposito, particularly overhead substrates coated with steel and zero alloys - Google Patents

Abstract

The formation of imperfections and blisters, during the self-deposition coating of non-ferrous metal surfaces, particularly galvanized steel and similar zinciferous surfaces, can be greatly reduced by the exposure of the surfaces to an aqueous solution, which inhibits imperfections, of phosphonates , preferably from an aminophosphonic acid, before the autodeposit coating

Description

PREVIOUS COATING CONDITIONER TREATMENT FOR SELF-DEPOSIT, PARTICULARLY ABOUT SUBSTRATES COATED WITH STEEL AND ZINC ALLOYS FIELD OF THE INVENTION The invention relates to the use of liquid solutions or dispersions, usually aqueous, in which the active metal surfaces of inserted objects are covered with a film of adherent polymer, which further increases the thickness of the metal object that remains in the bath, although the liquid is stable for a longer time against the spontaneous precipitation or flocculation of any solid polymer, in the absence of contact with the active metal, i.e. metal that spontaneously begins to dissolve at a substantial rate, when introduced in the liquid solution or dispersion. Such compositions and processes for forming a coating on a metal surface, using such compositions, are commonly denoted in the art and in this specification as "self-deposition" or "compositions, dispersions, emulsions, suspensions, baths, solutions, processes, methods of "autodeposit" or a similar term. The self-deposit is often contrasted with the electrodeposition, which can produce very similar adhesion films, but requires that the metal or other objects to be coated, be connected to a source of direct current electricity, for this coating to occur. No external electric current is used in the autodeposit. Self-deposition compositions, previously known in the art, are effective for coating many metals of particular interest, but it has been observed that when attempting the self-deposition coating of most zinc-rich metal surfaces, such as steel galvanized, often results in coatings with "tiny holes" or larger blisters. Such coatings are usually considered aesthetically unpleasant and often fail to provide the protection against the environment that is normally desired from self-deposit coatings. The reduction or elimination of the formation of minute holes or larger imperfections in self-deposited coatings, particularly on zinciferous surfaces, more particularly galvanized steel or some variant thereof, is the main object of this invention.

DESCRIPTION OF THE RELATED TECHNIQUE The self-deposition has been in commercial use in steel for around thirty years and its use is now well established. For details, see, for example, the patents of E. U. A., Nos. 3,592,699 of July 13, 1971, of Steinbrecher et al. , 4,108,817 of August 22, 1978 and 4,178,400 of December 11, 1979, both of Lochel; 4,242,379 of December 30, 1980 and 4,243,704 of January 6, 1981, both by Hall et al.; and 5,342,694 of August 30, 1994 from Ah ed. (The descriptions of these US patents, immediately mentioned above, except to the extent that they may be inconsistent with any explicit statement herein, are incorporated herein by reference.) However, the preparation of imperfection-free coatings in most Electrochemically active substrates, such as zinc, have continued as a challenge, especially when using a preferred chemical type of self-depositing resin, a crystalline, internally stabilized copolymer of vinylidene chloride.

DESCRIPTION OF THE INVENTION General Principles of the Description Except in the claims and in the examples of operation, or where otherwise expressly indicated, all the numerical quantities in this description indicate amounts of material or reaction conditions and / or the use thereof. will understand as modified by the word "approximately", when describing the broader scope of the invention. However, the practice within the stated numerical limits is generally preferred. Likewise, unless otherwise stated, the percentage, "parts of" and value of relationship are by weight; the term "polymer" includes the "oligomer * \", "copolymer", "terpolymer", and the like; the description of a group or class of materials, as appropriate or preferred for a given purpose in relation to the invention, implies that mixtures of any two or more of the members of the group or class are equally suitable or preferred; description of the constituents in the chemical terms refers to the constituents at the time of addition to any combination specified in the description, and does not necessarily exclude the chemical interactions between the constituents of a mixture, once mixed, the specification of materials in the The ionic form implies the presence of sufficient counter-ions to produce electrical neutrality for the composition as a whole, and any implicitly specified counter-ion is preferably selected from among other constituents explicitly specified in the ionic form, to the extent possible; way, counter-ions can be freely selected, except to avoid counter-ions that adversely affect the objects of the invention; and the term "mol" and its variations, can be applied to ionic species, chemically unstable neutrals or any other chemical species, if they are real or hypothetical, which are specified by the types of atoms present and the number of each type of atom included. in the defined unit, as well as the substances with well-defined neutral molecules.

SUMMARY OF THE INVENTION It has now been found that the contact of metal surfaces, particularly galvanized steel or zinciferous surfaces and of aluminum and its alloys, containing at least 45% aluminum, after any necessary or convenient cleaning, but before of the autodepopositive, with an aqueous solution having a surface tension value, at 30ec, not greater than 55 dynes per centimeter and consisting essentially of, or consisting preferably of, water and: (A) at least 0.008% , based on the total solution, of a component of dissolved phosphates and, optionally, one or both of the following components: (B) a component of a dissolved surfactant, excluding phosphonates and (C) a component of a mineral acid no dissolved oxidant, excluding any material that is part of component (A) or (B), is exceptionally effective in reducing the formation of minute holes or similar surface imperfections, after the subsequent self-deposit. For the purposes of this description, a "non-oxidizing mineral acid" is defined as in column a, lines 50-56, of the patent of E. U. A., No. 4,477,390, dated October 16, 1984 by Ledent et al. , and the entire specification thereof, except to the extent contrary to any explicit disclosure herein, is hereby incorporated by reference. Such metal pretreatment compositions constitute a modality of this invention. Another composition, embodiment of the invention, relates to a concentrate from which a working composition of the invention can be prepared, by means of delaying with water. In its simplest form, a process, according to this invention, comprises three steps: (i) the contact of an object with metal surface with a liquid and aqueous precoating composition, which inhibits imperfections, as described above , at a suitable temperature, for a time sufficient to produce minor imperfections in a subsequently self-deposited coating, this step is briefly denoted as "pre-coating treatment that inhibits imperfections" or "BIPT" and the aqueous liquid composition used is briefly denoted herein as "BIPTC"; (ii) remove the object with metal surface from contact with the BIPTC; and (iii) applying a self-deposited coating on the surface treated with the BIPTC in step (i).

Detailed Description of the Preferred Modes The self-deposit composition and the process by themselves and the treatments with other compositions before the BIPT and after the self-deposit, for example, the cleaning of the substrate before contact with the BIPTC, in rinses in a simple manner and / or of reagents, after self-deposition, the use of chromium containing or other known and advantageous compositions, of post-treatment, after self-depositing and rinsing, and heating or other processes, such as steam treatment to stabilize the film of the initially formed coating, are generally the same in a prolonged process according to this invention as in the prior art. The specific preferred conditions are described in the following working examples. Preferably, a process according to the invention also includes rinsing an uncured, wet, but drained coating formed in the self-depositing bath with one of the aqueous compositions often known in the art as "reactive rinses", also known simply as "rinses", particularly preferred reactive rinses are described in the E patent.

UA, No. 5,372,853 of December 13, 1994 and in the US Application, Serial No. 08 / 316,437, filed on September 30, 1994, which, except to the extent that it may be inconsistent with any explicit statement of the present, is incorporated here as a reference. Other suitable reaction rinses are described in the following U.A.A. patents, the specifications of all of which, except to the extent that they may be inconsistent with the explicit disclosure herein, are incorporated by reference: 5,432,694 of August 30, 1994; 5,428,525 of September 30, 1993 and 5,164,234 of November 17, 1992. Any cleaning of the object with zinciferous surface, which is known as necessary or convenient, prior to self-deposit coating in the self-depositor of the prior art can be advantageous and preferably be used in connection with this invention, prior to the precoat treatment which inhibits imperfections. Under certain conditions, it may be advantageous to rinse with water a substrate surface treated with a BIPTC, according to the invention, before introducing the substrate into the self-depositing bath. Such rinsing, however, is often unnecessary and when it is not necessary it is preferably avoided for economy.

The characteristic component (A) of a composition according to this invention is preferably selected from the group consisting of phosphonate ions containing at least one amino nitrogen atom, preferably a n-tertiary amino nitrogen atom, per ion. Independently, the ions of this characteristic component (A) are preferably selected from ions containing at least 2, or more preferably at least three, parts of phosphonate per ion. Also, independently, when the amino nitrogen is present, the divalent hydrocarbon portions selected from the group of methylene and polymethylene portions preferably connect the phosphorus atoms in each part of the phosphonate with an amino nitrogen atom; more preferably, these connection parts are methylene, with the methylene oligomers being increasingly less preferred, as the number of carbon atoms in these oligomers increases. For convenience and economy, the ions of component (A) are preferably added to BIPTC in the form of corresponding, commercially available phosphonic acids. The most preferred single source for the characteristic component (A) is the triamine-penta. { methylene phosphonic acid} of diethylene, with the formula estructuraL: H2P03CH2N. { (CH2) 2N- (CH2P03H2) 2.}. 3, And the second most preferred is the aminotri. { methylene phosphonic acid} with the chemical formula N- (CH2P03H2) 3. The concentration of the component (A) characteristic in the BIPTC can generally vary over a wide range without affecting the effectiveness of the inhibition of imperfections very strongly, in particular. with the most effective inhibitors. For each particular molecular type in component (A), it is expected to have a "threshold" value below which little or no inhibition will be achieved. In many cases, it is also expected to have a value usually at least two orders of magnitude above the threshold value, above which imperfections that inhibit the effectiveness of a particular molecular type diminish, perhaps because the acidity becomes too much. high. Therefore, the technically preferred concentration values of component (A) will depend in detail on the particular molecules used. In addition, the practically preferred value will depend on the economy. If the rinse solution is not recycled, as is usually more convenient, it is preferred that the point from the cost view use as little inhibitory additive as is effective suitably for the purpose. In general, from the point of view of obtaining the maximum inhibition of imperfections, the concentration of the component (A) in the treatment composition of the pre-working coating, according to the invention, is preferably, with increasing preference, in the order given, at least 0.0085, 0.0088, 0.0091, 0.0094, 0.0097 or 0.0100% and for the less preferred molecular types, more preferably it is, with increasing preference, in the given order, at mp "s of 0.020, 0.030, 0.040 or 0.080 Independently, for economic reasons, the concentration of the component (A) in a pre-treatment coating treatment composition, according to the invention, is preferably, preferably increasing in the order given, not greater than 50, 25, 10, 5, 3, 2, 1, 0.5, 0.3, 0.2, 0.10, 0.080, 0.060 or, 0.050% and for the most preferred molecules for component (A) it is more preferably, preferably increasing in the given order, not greater than 0.040, 0.020 or 0 The concentration of the phosphonate was determined by titration of a 250 milliliter sample (hereinafter abbreviated "ml") of the working composition with a 0.025N solution of thorium nitrate, after acidification of the sample with a solution of 1% nitric acid in water, to the extent necessary to make the sample pale and pale yellow and then adding 1 ml of a solution of 9.45 grams of monochloroacetic acid in a mixture of 40 ml of a solution of 5% NaOH in water and 60 ml of additional deionized water, using the alizarin indicator, to the first pink salmon endpoint that persists for at least 30 seconds. Each ml of the titration solution consumed corresponds to 12.8 parts per million phosphonates in the working composition. In general, the preferred sources of the phosphonic acid of component (A) are commercially available only in solution in combination with the non-oxidizing mineral acids which act to stabilize the acids against crystallization, as described in US Pat. No. 4,477,390 , already mentioned before. Therefore, the compositions according to the invention normally contain the optional component (C). The amount of the component (C), when composed of the hydrochloric acid, as is more generally preferred, is preferably such that the ratio of the component (C) to the component (A), the latter measured as its stoichiometric equivalent of the acids corresponding phosphonic, is at most, with increasing preference in the given order, of 0.10, 0.15, 0.20, 0.25, 0.28, 0.30 or 0.32: 1.0 and preferably, independently, not greater than, with increasing preference in the given order , of 1.0: 1.0, 0.80: 1.0, 0.70: 1.0, 0.65: 1.0, 0.60: 1.0, 0.55: 1.0, 0.50: 1.0, 0.45: 1.0, 0.40: 1.0, 0.37: 1.0, 0.35: 1.0 or 0.33: 1.0. - In order to maximize the likelihood of avoiding imperfections, the surface tension of the precoating treatment composition, according to this invention, is preferably, preferably increasing in the given order, not greater than 50, 48, 46, 44, 42, 4, 40, 39, 38, 37, 36, 35 or 34 dynes per centimeter, when measured at 302C, by the Whilr ^ and (or plate) cursor method. For details of the surface tension measurement, see A. Adamson in Physical Chemistry of Surfaces, 3 a Ed. (John Wiley & amp; amp;; Sons, New York, 1976), pages 23-25 and C. Weser, "Measurement of Interfacial Tension and Surface Tension - General Review for Practical Man", GIT Fachzeitschrift fur das Labor atorium, 24 (GIT Verlag Ernst Giebelder, Darmstadt , Germany, 1980), 642-648 and 734-742. Component (A) generally has a slight surface tension which reduces the effect on otherwise pure water, but in order to achieve more preferred values of the surface tension for a pre-coating treatment composition, in accordance with In the invention, additional surfactant is generally preferred as the component of BIPTC. Any surfactant that is (i) chemically stable in combination with component (A) and water, (ii) is effective in reducing surface tension and (iii) has no adverse effect on the coating quality subsequently. formed by the autodeposit. A group of surfactants which have been found particularly suitable and effective in economically small concentrations are the aromatic sulfonates and their salts, particularly the disulfonated derivatives of the dodecyl diphenyl ether, commercially available from Dow Chemicals Co. of Midland, Michigan. under the names of DOWFAX® 2A1 and 2A0, which are surfactants in solution. Preferred amounts of any surfactant are those required to obtain the preferred values of the surface tension indicated in detail herein. For DOWFAX® 2A1, which is usually the most preferred, the concentration in the working BIPTC is preferably, preferably increasing in the given order, at least 0.0003, 0.0006, 0.0012, 0.0015, 0.0018, 0.0021, 0.0024, 0.0027 , 0.0030, 0.0032 or 0.0034% and, primarily, for reasons of economy, independently in preferred form is, with increasing preference in the given order, not greater than 0.05, 0.03, 0.010, 0.0070, 0.0050 or 0.0040%. The contact time between the metal substrate and the BIPTC, according to this invention, and the temperature during this contact can vary within wide limits. In general, with the preferred treatment compositions, the contact time is preferably, preferably increasing in the order given, at least 5, 10, 15, 25, 35, 45, 50, 55 or 60 seconds (abbreviated below) usually as "sec") and independently, in primary form for reasons of economy, it is preferably, with increasing preference in the given order, no greater than 30, 15, 10, 5, 4, 3, 2, 1, 7, 1.5 , 1.3 or 1.1 minutes (then abbreviated usually "min"). The treatment compositions, according to the invention, are suitably effective at normal ambient temperatures of 20 to 25 ° C, and for convenience and economy are preferably used in general within such a temperature range, although they can be used at any temperature between their Freezing and boiling points. The self-depositing bath used for a process according to this invention preferably comprises, more preferably, essentially, or even more preferably consists of water and: (A) (A ') from 5 to 550, more preferably from 30 to 300, still more preferably from 40 to 120 and especially preferred from 40 to 80 grams / liter (g / l) of an organic coating resin, stably dispersed; (B) (B *) from about 0.4 to 5, more preferably from 0.5 to 4.0, and even more preferably from 1.0 to 3.0 g / l of fluorine ions (C) an amount sufficient to supply about 0.010 to 0.20, more preferably from 0.011 to 0.09, still more preferably from 0.012 to 0.045, equivalent oxidizing equivalents of an oxidizing agent, selected from the group consisting of dichromate, hydrogen peroxide, ferric ions and their mixtures; and (D) a source of hydrogen ions, in an amount sufficient to impart to the self-deposition composition a pH in the range of 1.6 to 3.8, more preferably 1.7 to 3.0 and even more preferably 1.8 to 2.5. A preferred type of coating resin for use in forming self-deposited coatings in a process, according to the present invention, comprises copolymers of vinylidene chloride, internally stabilized, or copolymers of vinylidene chloride, externally stabilized, containing more than 50 % or, more preferably, at least 80% vinylidene chloride residues of polymerization. Especially preferred, the vinylidene chloride copolymer is crystalline in nature. Exemplary crystalline resins are described in the U. U.

A., Nos. 3,922,451 and 3,617,368, whose descriptions, except any part that is inconsistent with any explicit statement hereof, are incorporated herein by reference. In general, crystalline resins containing poly (vinylidene chloride) comprise a relatively high proportion of vinylidene chloride residues, for example, at least 80% by weight thereof. A second preferred type of resin, for use in the self-deposit coating in connection with this invention, is an acrylic type, particularly acrylonitrile copolymers. Further details are given in the patent of E. U. A., No. 4,313,861 of February 2, 1982 by Bassett et al. , whose description, except any part that may be inconsistent with any statement herein, is incorporated herein by reference. Working BIPTCs can be conveniently prepared on-site, when used by concentrates diluted with water, and such concentrates are also within the scope of this invention. The concentrates normally contain, preferably, from 3 to 20 times the concentration of the components (A), (B) and (C), as described above for the working compositions.

The practice of the invention, especially in its preferred embodiments, can be appreciated in addition to the following non-limiting examples and comparison examples.

Table 1-1 STAGES OF THE PROCESS USED. GROUP 1 General Notes for Table 1-1"PLC" is an abbreviation for the "PARCO® Cleaner". PCL 1530A, with or without added PCL 1530S (see footnote below), is a conventional moderately strong alkaline cleaner, with surfactants. Footnotes for Table 1-1 1 If the substrates are not free of interruptions. When the PARCO® 153OA Cleaner is used alone, 2 g / l of the PARCO® 1530S Cleaner is also dissolved in the spray pre-cleaning and immersion cleaning fluids. 2 No PCL 1530A or S was deliberately added to this fluid, but, due to the drag of the preceding stage, it may have content as much as 10 g / l. 3 The immersion time with the solids concentration of the self-deposition composition (within the range of 6-7% specified) was adjusted to produce a dry self-deposited coating thickness of 17.8 ± microns. 4 The solute in this solution is believed to consist predominantly of cobalt fluozirconate after mixing and the evolution of gas, presumably carbon dioxide, which occurs after mixing. The solution was replaced after every 100 panels processed.

Group l Experimental General Procedure The sequence of the process used for this group of examples is shown in Table 1-1 below (Note: All products identified here by the trademarks PARCO®, RIDOLINE® and AUTOPHORETIC®, together with the directions det? "Aids for use, as described below, are commercially available from Parker Amchem Div. Of Henkel Corp., Madison Heights, Michigan. The compositions of the precoat treatment bath are shown in the following Table 1-2. The 18.5 liter preparation (hereinafter abbreviated usually as "1") of a "normal activation" autodeposit bath was achieved as follows: In a container of suitable size for the successive mixture of high density polyethylene (hereinafter referred to as in abbreviated form as "HDPE"), 3.37 kilograms (hereinafter abbreviated as "kg") was added to the AUTOPHORETIC® 866 Filler (hereinafter abbreviated usually "866 Filler" or simply "866"), which contains 37.5% solids and 12.1 kg of deionized water (hereinafter abbreviated usually as "DI"). To this first mixture, a solution, mixed separately, of 0.99 kg of initiator AUTOPHORETIC® 300 (hereinafter abbreviated usually as "Initiator 300" or "S 300") and 2.96 kg of DI water, were then added slowly with constant agitation, using a motor-driven stirrer. The addition of the initiator solution to the 866 solution took approximately 20 minutes. Then enough hydrofluoric acid was added to produce a reading of 248 microamperes (usually referred to as "μA") in a LINEGUARD® 101 fluoride activity meter (hereinafter usually termed, in abbreviated form, as "Meter 101"). This composition has a value of the oxidation-reduction potential (hereinafter usually abbreviated as "ORP") for a smooth platinum electrode submerged in the composition, compared to a standard hydrogen electrode of 375 ± 25 millivolts (abbreviated below usually as "mv"). The preparation of a "low activation" self-deposition bath was performed identically to the "normal activation" bath, except for the use of the following quantities of materials: 3.37 kg of the 866 Filler with 9.24 kg of DI water; 0.70 kg of Initiator 300 diluted with 3.12 kg of DI water and a reading of 110 μA in Meter 101. The ORP was the same as for the "normal activation" bath. The coating resin in both of these examples of self-depositing baths is a crystalline copolymer of vinylidene chloride.

Table 1-2 BATH TREATMENT BATH COMPOSITIONS PREVIOUS. GROUP 1 Notes for Table 1-2 Designation of the previous coating, DI and all other designations of the previous coating that do not begin with the letter "D", are examples of comparison, not according to the invention. "Weight-Vol%" means that the volume of the liquid solution in which the DOWFAX ™ surfactants are supplied was not measured directly; then the volume percentage corresponding to this volume with respect to the volume of the whole composition was multiplied by the weight percentage of one or more phosphonic acids in the liquid solution, to obtain the "Weight-Vol%".

During use, the self-deposit baths were maintained between 6-7% of the total solids by the addition of the 866 Filler, as needed, to compensate for the loss of the coating resin from the baths, primarily by transferring the resin in autodeposited coatings, formed during use. Oxidant AUTOPHORETIC® 24 was added to maintain the range of the ORP specified above for each bath and hydrofluoric acid was added to maintain the readings of Meter 101 of 250 ± 25 μA in the autodeposit bath in "normal activation" (usually shortened hereinafter referred to as "NA") and 110 ± 10 μA in the "low activation" bath (usually abbreviated as "LA"). A separate BIPTC was used for each type (ie NA or LA) of the self-deposit bath. All processed metal substrates were rectangular panels of 10.16 x 15.24 centimeters (usually abbreviated as "cm") in size, which were prepared by bisecting rectangular panels of a size of 10.16 cm x 30.48 cm, supplied by ACT Laboratories, Inc., of Hillsdale, Michigan. Three types of metals were used. Cold Rolled Steel (hereinafter usually abbreviated as "CRS"), Clave APR 11721, 6.6 millimeters (usually abbreviated as "mm") thick, clean, unpolished, Lot 30425414 or 31021314; Hot Dip Galvanized Steel (usually referred to hereinafter as "G60") Key APR 10260, 8.9 mm thick; and Galvano-tempered steel (usually referred to hereinafter as "A60") Clad APR 16966, 7.6 mm thick, clean, unpolished, Lot 20622416 or 20315416. The panels were submerged two at a time, using two hooks attached to the same support bar, for the process sequence. A total of 18 panels were processed for each BIPTC; six of CRS, six of G60 and six d of A60.

Physical tests included GM 9511P tests, 20-cycle mark / crust, 504 hours of salt spray (ASTM) B117-90), impact (ASTM 2794-87, except that there is no evaluation of the pattern of the coating removed by the tape), and initial adhesion (ASTM D3359-87). Table 1-3 lists the observations of the presence of tiny holes / ampoules in oven-cured coated panels initially, as well as GM 9511P test results, 20 cycle mark / coast, salt spray and adhesion initial. Coatings that have significant formation of blisters and / or minute holes after curing in the furnace were not tested further. The following conclusions were reached from the results of Table 1.3: The experimental BIPTCs found to give the best overall performance were those containing DEQUEST ™ 2060. The concentration of at least 0.02% of this material (containing only 50%) of its active ingredient phosphonic acid) seems to give the best overall results under low and normal activation conditions for the self-deposition bath. The honeycombs G60, A60 and CRS were all free of tiny holes and blisters after curing the furnace. The initial adhesion was not affected by the precoating treatment step when compared to the DI comparison precoat treatment step, but the corrosion results after the subsequent self-deposition coating were substantially better with the treatment composition., according to the invention. The differences in salt spray performance and brand / scale performance between low and normal activation baths were not significant. The coatings after the pretreatment compositions, which contain the DEQUEST ™ 2000 had a performance comparable to the salt spray and brand / scab tests to those after the DEQUEST ™ 2060. However, the treatments containing the DEQUEST ™ 2000 were less effective at preventing the formation of tiny holes on the A60 galvanized-tempered panels, under "normal activation" bath conditions (Meter reading 101 = 250 μA) and seem to require at least twice the concentration as with the compositions containing the DEQUEST ™ 2060 to provide the highest corrosion resistance in the toughest electroplated substrates.

TABLE 1-3 Results of the Zinc Alloy Steel and Steel Coating Process, Group I Coated - Types of Holes Adhesion Impact 504 HrSS Creep Minor bath / panel / initial Marks / Crusts Previous blisters Mm Table 1-3 (Continued) eros Adhesion Impact 504 HrSS Dragging Recubri TIPO / Tiny panel initial initial Marking / Creasing Ba Mm Previous blisters Table 1-3 (Continued) Coated - Types of Holes Adhesion Impact 504 HrSS Creep Minor bath / panel / initial Marks / Crusts Previous blisters Mm Table 1-3 (Continued) Coated - Types of Holes Adhesion Impact 504 HrSS Creep Minor bath / panel / initial Marks / Crusts Previous blisters Mm Notes for Table 1-3"The" Comp. A "is a comparison example in which a precoating treatment was not used and the rinse after the autodeposit was an aqueous solution of ammonium carbonate, but other stages of the process were the same as for the" normal activation "self-deposition. , according to the invention. B "is a comparison example in which the metal substrate was coated with an electrodeposited paint (Powercron ™ 500) which is generally considered to be of very high quality, rather than any self-deposited coating.

Conditioner rinses containing H3PO4 were not able to produce coatings free of tiny holes on A60 electroplated steel, at all previous coating concentrations and tested ACC-866 bath activation levels. The performance results of salt spray and brands / crusts were slightly lower than for the BIPTCs they contain. DEQUEST ™ aminophosphonic acid. Mixtures of HF-H2O2 were not effective in removing minute holes and blisters in the electroplated steel. The salt spray tests (ASTM B117-90) resulted in some field ampoules and cathodic delamination zones on both G60 panels as A60, for all precoating conditioner rinses, discussed here. Such results are always, or almost always, observed during this type of testing of samples with zinciferous surfaces, even though these surfaces are protected with coatings that are known to give excellent resistance to corrosion under practical conditions of use. However, precoating conditioning rinses do not appear to reduce the severity of field blisters and delamination, induced by salt spraying, which are much more severe for A60 panels than for G60 panels in general. Data from the GM 9511P labeling / scalation test of 20 cycles were excellent for all BIPTCs containing DEQUEST ™ aminophosphonic acid and both ACC-866 bath activation levels treated. Typical drag widths for all panels A69 and G60 were 1 mm or less in total drag. Total drag rates on the CRS were typically 2 mm, comparable with those now achieved with the best self-deposition technology of the prior art, which indicates that the self-deposit coatings applied after a BIPT, according to the invention, are less as satisfactory as other self-deposit coatings in the CRS and, therefore, can be used on composite objects containing both CRS and zinc-coated surfaces, without deterioration of the best performance, now achieved by the CRS self-deposition coating alone. The results of the impact test are somewhat erratic, as is normal for CRS substrates coated by self-deposition, but there is no evidence that the BIPT containing aminophosphonic acid affects the performance of the impact test either adversely or positively.

Group 2 A main object of this group of examples is to establish the levels of consumption of the active ingredients of the BIPTC during the prolonged use. Unless otherwise noted below, the operating conditions were the same as for Group 1. General Operating Conditions When preparing the autodeposit tanks, 0.94 rather than 0.99 kg of the AUTOPHORETIC® Primer 300 and 2.45 kg were used instead of 2.96 kg of water. The detected reading of fluoride from Meter 101 was 150 instead of 240 μAmp. A BIPTC concentrate was prepared as follows: in a properly sized HDPE jar, 54.00 ± 0.01 g of Dequest 2060, 4.41 ± 0.01 g of Dowfax 2A1 and sufficient DI water were mixed to produce a total concentrated mass of 3000 ± 1 f . To prepare a working BIPTC, 150.0 ± 0.1 g of the aforementioned BIPTC concentrate was then diluted to 3000 ± 1 g with DI water and rinsed. 1300 ± 1 g of this solution were added to a narrow stainless steel panel coating tank, designed to accommodate rectangular test panels, which are 10 x 30 cm in size, with a minimum volume of solution.

The phosphonate concentrations in the working BIPTCs were inspected and maintained at intervals after the use of the BIPTC, removing a sample of 250 ± 1 g of the BIPTC (as long as no substrate was processed) and titling this sample with a solution of thorium nitrate, as already described above. The remaining 1050 ± 1 g of the used BIPTC was then mixed with an amount of the BIPTC concentrate, described above, higher than calculated, based on the results of the titrated sample, to result in a mixture having a phosphonate concentration The original BIPTC work in a total mass of 1550 ± 1 g of the mixture and enough DI water to bring the total mass of this mixture to 1550 ± 1 g was then added and mixed well. A second sample of 250 ± 1 g was then taken from the mixture and titrated as described above, to determine if the concentration of the phosphonate in the mixture had been restored to at least the value originally present in the newly obtained BIPTC. If so, the remaining 1300 ± 1 g of the mixture was usually continued using as the BIPTC used as a filler, to treat more substrate panels, as noted in the following specific cases. The general sequence of the process used for this group is shown in the following Table 2-1. The substrate materials used, with the abbreviations for them used in the following description, shown with the reference marks in parentheses after the name of each subsequent substrate type, are as follows: Cold Rolled Steel ("CRS"), Clave APR 11721, thickness of 6.6 mm, clean, unpolished, Lot 31216414. Galvanized hot dip ("G60"), Key APR 10260, thickness of 8.9 mm, clean, unpolished, Lot 20109516. Galvano-tempered ("A60" ), Clamp APR 16966, thickness of 7.6 mm, clean, unpolished, Lot 31004416. Hot dip galvanized / Cold rolled steel, bimetallic, end to end overlap joint ("G60 / CRS"), Code 10270, Lot 21214416, Panel A: ACTCRS, Panel B: ACT G60. Galvano-tempered / Cold-rolled steel, bimetallic, end-to-end overlap joint ("A60 / CRS"), Code 10270, Item 21214416, Panel A: ACTCRS, Panel B: ACT A60. Data on the appearance of the cured coating, as a function of the substrate and the use or non-use of the subsequent acid cleaning and rinsing steps, are shown in the following Table 2-2. The "Comparison I" in this table was a commercial product, the AUTOPHORETIC® 3180 Conditioning Rinse.

Table 2-1 STAGES OF THE PROCESS USED IN THE GROUP 2 General Notes for Table 2-1"RDL" is an abbreviation of the "RIDOLINE® Cleaner"; RDL 1007 is an alkaline cleaner concentrate, strongly titrated, solid powder. "AC7150" is an abbreviation of AUTOPHORETIC® 7150 Acid Cleaner, a liquid concentrate for preparing a spray cleaning solution, designed to remove light rust and oxidation of oil and grease-free iron and steel surfaces, before Apply a self-deposit coating. Footnotes for Table 2-1 1 This stage was used only on substrates including cold-rolled steel and not on all substrates; the exceptions are noted in the following tables. 2 The immersion time, together with the solids concentration of the autodepository composition (within the specified range of 6-7%) was adjusted to produce a self-deposited coating thickness of 25.4 ± 2.5 microns. 3 The solute in this solution was created consisting predominantly of cobalt fluozirconate after mixing and evolution of gas, presumably carbon dioxide, which occurs after mixing.

The panels in this process sequence were processed one at a time, with the substrates being processed in the following sequence: First, six each type one panel of G60 / CRS and A60 / CRS were processed in alternate sequence. Second, nine CRS panels, nine A60 panels and nine G60 panels were processed, one of each type being processed before a second of any type processor, etc. Third, six G60 / CRS panels and six A60 / CRS panels were processed again in alternate sequence. Fourth, another eleven of each CRS, A60 and G60 panel were processed in the same sequence as before, followed by three of each panel G60 / CRS and A60 / CRS alternating ^ '-' with each other. Finally, control panels and other tests were processed, as necessary. Table 2-3 shows the pertinent data on the consumption of the phosphonate during a process according to the invention. 1 average consumption, calculated from the values in Tables 2-3, is 7.6 g of the BITC concentrate per square meter of substrate surface processed. The work BIPTC was analyzed for several elements at the beginning and end of use, as described above. The results are shown in Table 2-4. They indicate that zinc is the dissolved primary metal of the substrates during the BIPT of the galvanized steel, according to the invention and that the active ingredient of the phosphate was converted to some other compound with soluble phosphorus, at least part of which remains in solution in the BIPTC. The results of the physical tests for Group 2 are shown in Tables 2-5, 2-6 and 2-7 below.

Table 2-3 The results of Group 2 lead to the following conclusions: The BIPTC of type D2060 / 2A1 gave a superior appearance of the panel of coating compared with the commercial BIPTC better previous, the rinse conditioner AUTOIPHORETIC® 3180. It was observed that the treatment according to the The invention described herein gave coating are formation of blisters or tiny holes on the substrate CRS and G60, and only traces of tiny holes on galvanized steel A60. The removal of the 7150 acid cleaning step improves the coating coverage on a steel-to-steel overlap coated joint region, with the best example of a BIPT, according to the invention. The initial consumption regime of the active ingredient of the BIPTC was calculated to be 39.8 g of phosphonate per 1000 m2 of the processed substrate. The consumption regime decreased to approximately 23.7 g of phosphonate per 1000 m2 between 3.4 and 5.5 m2 of the processed substrate per liter of the starting BIPTC. This may be due to the accumulation of soluble metal phosphonate byproducts in the BIPTC used. A minimum concentration of approximately 83 ppm of phosphonate in the BIPTC is necessary so that the cured coatings have the best appearance obtained. The nature of the failure or defects depend on the amount of the substrate processed through the precoat bath. Minor phosphonate concentrations appear to be adequate to produce a cured coating with good appearance, since phosphorus-containing byproducts accumulate < = > n the BIPTC. The results of the initial adhesion and impact coating tests for coatings on substrates G60 and A60 were not affected by the amount of the substrate processed in the best BIPTC, according to the invention, up to at least about 3.7 m2 / l of the original BIPTC processed. The continued use of the BIPTC used as a filler, after the extension of the process resulted in somewhat lower adhesion and impact values. The performance of the coating for coatings on a CRS substrate does not decrease with the continued use of the used replacement BIPTC. The salt spray tests resulted in some field blisters and cathodic delamination zones for the coatings after the treatment, according to the invention, on both G60 and A60 substrates. Variable field blisters were also observed, but the size of the blisters / or the frequency did not have a consistent trend. All these results are normal for almost any organic coating on zinc-rich metal surfaces, even for known coatings that perform well in practice. The classifications showed variability without apparent tendency in the area of the processed substrate of increase. The coating performance was slightly better for the coatings on the A60 substrate than for the G60. The results of the salt spray on CRS was typically 0-1, comparable to all types of comparison examples tested, which indicate that the BIPT, according to the invention, is not detrimental to the amount of the self-deposited coatings on CRS. , which already gives only a completely satisfactory coating performance. The results of the marking / crust test were excellent for the coatings after the BIPT, according to the invention, on substrates G60 and A60. The typical total carry widths for all panels A50 and G60 were 1 mm or less. Typical tow widths over 2 mm were closely comparable to those achieved with the currently preferred commercial self-deposition of the same self-deposition compositions as those used here.

Table 2-4 Abbreviations for Table 2-4"ppm" = parts per million, "m2 / l" = square meters of substrate per liter of the BIPTC Table 2-5 Table 2-5 (Continued) Footnotes for Table 2-5 1 With the same batch of the BIPTC, except for the filling. 2 The step of acid cleaning and immediately followed by the rinsing step, were omitted for this substrate in this case. 3 Comparison example with the 3180 AUTOPHORETIC® conditioner rinse, rather than a BIPT, in accordance with this invention. 4 Comparison example without BIPT in addition to the water rinse DI..5 Comparison example without BIPT and with different reactive rinse, reaction rinse 2150, AUTOPHORETIC®, 6 comparison example with an electrophoretic paint coating rather than the self-deposited coating .

Table 2-6 Substrate m2 / l Previously Treated Test Results Marked / Scale, mm Coated portion CRS with Zn Portion Table 2-6 (Continued) Substrate m2 / l Previously Marked / Scaled Treated Test Results, mm Footnotes for Table 2-6 1 With the same batch of the BIPTC, except for the filling. 2 The acid cleaning step and immediately followed by the rinse step were omitted for this substrate in this case. 3 Comparison example with the 3180 AUTOPHORETIC® conditioner rinse, rather than a BIPT, in accordance with this invention. 4 Comparison example without BIPT in addition to the water rinse DI..5 Comparison example without BIPT and with different reactive rinse, reaction rinse 2150. AUTOPHORETIC®, 6 comparison example with a coating Table 2-7 Substrate m2 / l Treatments Value after 504 hours of Salt Spray Table 2-7 (Continued) Substrate m2 / l Treatments Value after 504 hours of Salt Spray i mind Table 2-7 (Continued) Substrate m2 / l Treatments Value after 504 hours of Salt Spray Previously Coated Portion with CRS, Zinc, Campo Field Footnotes for Table 2-7 1 With the same batch of the BIPTC, except for the filling. 2 The acid cleaning step and immediately followed by the rinse step were omitted for this substrate in this case. 3 Comparison example with the 3180 AUTOPHORETIC® conditioner rinse, rather than a BIPT, in accordance with this invention. 4 Comparison example without BIPT in addition to the water rinse DI..5 Comparison example without BIPT and with different reactive rinse, reaction rinse 2150, AUTOPHORETIC®, 6 comparison example with a coating

Claims (20)

CLAIMS 1. A process to form a protective coating on a solid metal surface, this process comprises the steps of: (I) contacting the solid metal surface with a liquid and aqueous composition, for the treatment of the previous coating, which inhibits the imperfections
1. ("BIPTC"), which has a surface tension value, at 30sc, not greater than about 55 dynes per centimeter and comprising water and at least about 0.008% dissolved phosphonate anions; (II) removing the solid metal surface from contact with the BIPTC, which was carried out in step (I), and then (III) self-depositing an organic protective coating on the solid metal surface, coming from step (II), by the contact of the surface with a self-depositing bath.
2. 2. A process, according to claim 1, wherein the BIPTC additionally comprises at least about 0.0003% of a second surfactant, in addition to the phosphonate anions, and has a surface tension no greater than about 46 dynes per centimeter.
3. 3. A process, according to claim 2, wherein the BIPTC comprises at least about 0.0009% of surfactant molecules, selected from the group consisting of aromatic sulfonates and their salts.
4. 4. A process, according to claim 3, wherein the surface tension of the BIPTC is not greater than about 40 dynes per centimeter.
5. 5. A process, according to claim 4, wherein the BIPTC contains about 0.0021 to 0.010% surfactant molecules, selected from the group consisting of the disulfonic acids of the dodecyl-diphenyl oxide and its salts.
6. 6. A process, according to claim 5, wherein the ions of component (A) are diethylenetriamine-penta (methylene phosphonic acid) ions.
7. 7. A process, according to claim 4, wherein the ions of the component (A) are selected from the group consisting of diethylenetriamine-penta (methylene phosphonic acid) ions and ions of α-nitric acid (methylene glycol). phosphonic).
8. 8. A process, according to claim 3, wherein the ions of component (A) are selected from the group consisting of ions which (a) contain (a) at least one nitrogen atom of tertiary amino and (a.2) at least three parts of phosphonate per ion and (b) contain parts of divalent hydrocarbons, selected from the group of methylene and polymethylene parts, which connect each phosphorus atom in a phosphonate part in the ion to an amino nitrogen atom in this ion.
9. 9. A process, according to claim 2, wherein the ions of the component (A) are selected from the group consisting of ions containing at least two parts of phosphonate per ion and in that, if the ions contain a nitrogen atom of amino, this atom is attached to a part of divalent hydrocarbon, which also binds to a phosphorus atom in a phosphonate part.
10. 10. A process, according to claim 1, wherein the ions of component (A) are selected from the group consisting of ions containing at least two parts of fssphonate per ion.
11. 11. An aqueous liquid composition, which, as such or after dilution with additional water, is suitable as a pre-self-depositing, pre-self-depositing, coating-inhibiting treatment composition, this aqueous liquid composition consists essentially of water and (A) at least 0.008%, based on the total composition, of a component of dissolved phosphonate anions, and, optionally, one or both of the following components: (B) a component of a dissolved surfactant, excluding the phosphonates and their counter-ions and (C) a component of a non-oxidizing mineral acid gave ?? lto, excluding any material that is part of the component (A) or (B),
12. 12. An aqueous liquid composition, according to claim 11, in which this composition includes the component (B) in an extension of at least about 0.0003% and has a surface tension no greater than about 46 dynes per centimeter.
13. 13. An aqueous liquid composition, according to claim 12, wherein the composition includes at least about 0.0009% surfactant molecules, selected from the group consisting of aromatic sulfonates and their salts.
14. 14. An aqueous liquid composition, according to claim 13, having a surface tension which is not greater than about 40 dynes per centimeter.
15. 15. An aqueous liquid composition, according to claim 14, which includes about 0.0021 to 0.010% of surfactant molecules, selected from the group consisting of the disulfonic acids of the dodecyl-diphenyl oxide, and their salts.
16. 16. An aqueous liquid composition, according to claim 15, wherein the ions of component (A) are diethylenetriamine-penta (methylene phosphonic acid) ions.
17. 17. An aqueous liquid composition according to claim 14, wherein the ions of the component (A) are selected from the group consisting of diethylenetriamine-penta (methylene phosphonic acid) ions and amino-tri ions. methylene phosphonic acid).
18. 18. An aqueous liquid composition according to claim 13, wherein the ions of component (A) are selected from the group consisting of ions which (a) contain (at) at least one nitrogen atom of tertiary amino and ( a.2) at least three parts of phosphonate per ion and (b) contains divalent hydrocarbon parts, selected from the group consisting of parts of methylene and polymethylene, which connect each phosphorus atom, in one part of phosphonate in the ion , to an amino nitrogen atom in this ion.
19. 19. An aqueous liquid composition, according to claim 12, wherein the ions of the component (A) are selected from the group consisting of ions containing at least two parts of phosphonate per ion and wherein, if the ions contain one atom of amino nitrogen, this atom is attached to a part of divalent hydrocarbon, which also binds to a phosphorus atom in a phosphonate part.
20. 20. An aqueous liquid composition, according to claim 11, wherein the ions of component (A) are selected from the group consisting of ions containing at least two parts of phosphonate per ion.