Metal treatment – Process of modifying or maintaining internal physical... – Processes of coating utilizing a reactive composition which...
Reexamination Certificate
2000-02-22
2002-03-26
Green, Anthony (Department: 1755)
Metal treatment
Process of modifying or maintaining internal physical...
Processes of coating utilizing a reactive composition which...
C106S014120, C106S014440, C148S243000, C148S258000, C148S261000, C148S264000, C148S268000, C427S384000, C427S435000, C427S419100, C427S419200
Reexamination Certificate
active
06361622
ABSTRACT:
This invention relates to processes for treating a metal surface to form a protective coating, or for treating a metal surface on which a protective coating has previously been formed and remains in place, with its protective qualities intact, on one part of the surface but is totally or partially absent from, or is present only in a damaged condition over, one or more other parts of the surface, so that its protective value in these areas of at least partial damage or absence has been diminished. (Usually the absence or damage of the initial protective coating has been unintentional and has occurred as a result of such events as imperfectly uniform formation of the initial protective coating, mechanical damage of the initial protective coating, spotty exposure of the initially coated surface to solvents for the initial protective coating, or the like. The absence or damage of the initial protective coating may be intentional, however, as when holes are drilled in a coated surface, for example, or when untreated parts are attached to and therefore become part of a previously coated surface.) Particularly if the surface in question is large and the damaged or untreated area(s) are relatively small, it is often more economical to attempt to create or restore the full protective value of the original coating primarily in only the absent or damaged areas, without completely recoating the object. Such a process is generally known in the art, and will be briefly described herein, as “touching up” the surface in question. This invention is particularly well suited to touching up surfaces in which the original protective coating is a conversion coating initially formed on a primary metal surface, more particularly a primary metal surface consisting predominantly of iron, aluminum, and/or zinc.
An alternative or concurrent object of this invention is to provide a process for protectively coating metal surfaces that were never previously coated. Other concurrent or alternative objects are to achieve at least as good protective qualities in the touched up areas as in those parts of the touched up surfaces where the initial protective coating is present and undamaged; to avoid any damage to any pre-existing protective coating from contacting it with the touching up composition; and to provide an economical touching up process. Other objects will be apparent to those skilled in the art from the description below.
Except in the claims and the operating examples, or where otherwise expressly indicated, all numerical quantities in this description indicating amounts of material or conditions of reaction and/or use are to be understood as modified by the word “about” in describing the broadest scope of the invention. Practice within the numerical limits stated is generally preferred. Also, throughout this description, unless expressly stated to the contrary: percent, “parts of”, and ratio values are by weight; the term “polymer” includes “oligomer”, “copolymer”, “terpolymer”, and the like; the description of a group or class of materials as suitable or preferred for a given purpose in connection with 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 constituents in chemical terms refers to the constituents at the time of addition to any combination specified in the description or of generation in situ by chemical reactions specified in the description, and does not necessarily preclude other chemical interactions among the constituents of a mixture once mixed; specification of materials in ionic form additionally implies the presence of sufficient counterions to produce electrical neutrality for the composition as a whole (any counterions thus implicitly 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 invention); and the term “mole” and its grammatical variations may be applied to elemental, ionic, and any other chemical species defined by number and type of atoms present, as well as to compounds with well defined molecules.
SUMMARY OF THE INVENTION
It has been found that excellent coating and/or touching up quality, particularly for corrosion resistance on previously untreated areas and corrosion resistance in combination with a conversion coating, can be achieved by:
(I) covering the areas to be touched up with a layer of a liquid composition that comprises, preferably consists essentially of, or more preferably consists of, water and:
(A) a component of fluorometallate anions, each of said anions consisting 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, aluminum, and boron; and, optionally, one or both of
(iii) at least one ionizable hydrogen atom; and
(iv) at least one oxygen atom;
(B) a component of phosphorus-containing inorganic oxyanions and/or phosphonate anions; and
(C) a component of oxidizing agent or agents that are not part of either of immediately previously recited components (A) and (B) and are not chromium(III) cations;
and, optionally, one or more of the following components:
(D) chromium(III) cations;
(E) a component of free fluoride ions that are not part of any of immediately previously recited components (A) through (D);
(F) a component of surfactant molecules that are not part of any of immediately previously recited components (A) through (E);
(G) an acidifying component that is not part of any of the immediately previously recited components (A) through (F); and
(H) a viscosity increasing component that is not part of any of the immediately previously recited components (A) through (G);
and subsequently
(II) drying into place over the surface the liquid layer formed in step (I).
It should be understood that the components listed need not necessarily all be provided by separate chemicals. For example, it is preferred that the fluorometallate anions and phosphorous-containing anions both be added in the form of the corresponding acids, thereby also providing at least some, and usually all, of optional acidifying component (G).
Various embodiments of the invention include processes for treating surfaces as described above, optionally in combination with other process steps that may be conventional per se, such as precleaning, rinsing, and subsequent further protective coatings over those formed according to the invention, compositions useful for treating surfaces as described above, and articles of manufacture including surfaces treated according to a process of the invention.
DETAILED DESCRIPTION OF THE INVENTION
For a variety of reasons, it is preferred that compositions used according to the invention as defined above should be substantially free from many ingredients used in compositions for similar purposes in the prior art. Specifically, it is increasingly preferred in the order given, independently for each preferably minimized component listed below, that these compositions, when directly contacted with metal in a process according to this invention, contain no more than 1.0, 0.35, 0.10, 0.08, 0.06, 0.04, 0.02, 0.01, 0.005, 0.002, 0.001, 0.0005, or 0.0002 percent of each of the following constituents: dispersed (in this instance not including truly dissolved) silica and/or silicates; ferricyanide; ferrocyanide; sulfates and sulfuric acid; anions containing molybdenum or tungsten; alkali metal and ammonium cations; pyrazole compounds; sugars; gluconic acid and its salts; glycerine; &agr;-glucoheptanoic acid and its salts; and myoinositol phosphate esters and salts thereof.
A working composition for use in a process according to this invention preferably has a concentration of at least, with increasing preference in the order given, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, or 4.8 millimoles of fluorometallate anions, component (A), per kilogram of total working
Lindert Andreas
McCormick David R.
Green Anthony
Harper Stephen D.
Henkel Corporation
Jaeschke Wayne C.
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