Metal treatment – Process of modifying or maintaining internal physical... – Processes of coating utilizing a reactive composition which...
Reexamination Certificate
2002-07-26
2003-10-28
Green, Anthony J. (Department: 1755)
Metal treatment
Process of modifying or maintaining internal physical...
Processes of coating utilizing a reactive composition which...
C106S014120, C106S014440, C148S256000, C148S257000, C148S259000, C148S260000, C156S297000
Reexamination Certificate
active
06638370
ABSTRACT:
FIELD AND BACKGROUND OF THE INVENTION
This invention relates to compositions and processes for depositing a manganese-containing phosphate conversion coating on metal surfaces, particularly the surfaces of ferrous metals. The invention particularly relates to such compositions and processes that produce, at a temperature not more than 80° C., a conversion coating which is at least one of: (i) suitable, optionally and usually after being lubricated, as a high quality surface that is resistant to wear in sliding contact with other surfaces; and (ii) suitable for forming a strong adhesive bond to rubber, using adhesives established commercially as suitable for this purpose.
The use of manganese phosphate conversion coating to produce wear-resistant surfaces on ferriferous metals is well known in the art. See, e.g., Guy Lorin,
Phosphating of Metals
(Finishing Publications Ltd., Hampton Hill, Middlesex, England, 1974) pp. 193-202. Prior art phosphating compositions for this purpose have been used in practice only at relatively high temperatures, almost always above 80° C. and more often above 90° C., and processes at such high temperatures generally produce copious amounts of undesired sludge. Additionally, such high temperature processes consume more energy than processes operated at relatively low temperatures. However, known low temperature manganese phosphate conversion coating processes provide coatings having inferior properties (particularly wear-resistance). See, for example, id. at 196.
Various alternative and/or concurrent objects of this invention are: (i) to provide a composition and process for phosphating that will provide a high quality wear-resistant coating, optionally after lubrication, at a phosphating temperature that is not more than 80° C.; (ii) to provide relatively economical phosphate conversion coating compositions and processes that will provide as good quality a wear-resistant coating, optionally after lubrication, as currently conventional high temperature processes, by reducing the amount of sludge generated; and (iii) to produce a surface suitable for strong adhesive bonding of the underlying metal substrate to rubber or other elastomers in a composite article. Other more detailed alternative and/or concurrent objects will be apparent 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, however. Also, unless expressly stated to the contrary: percent, “parts of”, and ratio values are by weight; 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, and does not necessarily preclude chemical interactions among the constituents of a mixture once mixed; specification of materials in ionic form 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; the terms “molecule” and “mole” and their grammatical variations may be applied to ionic, elemental, or any other type of chemical entities defined by the number of atoms of each type present therein, as well as to substances with well-defined neutral molecules, and “mole” means specifically “gram mole”; the first definition of an acronym or other abbreviation applies to all subsequent uses herein of the same abbreviation; and the term “polymer” includes “oligomer”, “homopolymer”, “copolymer”, “terpolymer”, and the like.
BRIEF SUMMARY OF THE INVENTION
It has been found that one or more of the objects stated above for the invention can be achieved by the use of a conversion coating forming aqueous liquid composition that has a pH of at least 2.0 and comprises water and the following components:
(A) dissolved divalent manganese cations;
(B) dissolved phosphate anions;
(C) dissolved nitrate anions;
(D) at least one dissolved source of hydroxylamine; and, optionally, one or more of the following components:
(E) a component of surfactant molecules that are not part of any of the immediately previously recited components (A) through (D);
(F) buffering agents that are not part of any of the immediately previously recited components (A) through (E);
(G) a component of dissolved iron cations;
(H) a component of dissolved alkali metal and ammonium cations that are not part of any of immediately previously recited components (A) through (G). The term “optionally” is not meant to imply that components other than (A)-(H) can not or should not be present in the aqueous liquid composition.
Various embodiments of the invention include working compositions for direct use in treating metals, make-up concentrates from which such working compositions can be prepared by dilution with water, replenisher concentrates suitable for maintaining optimum performance of working compositions according to the invention, processes for treating metals with a composition according to the invention, and extended processes including additional steps that are conventional per se, such as acid pickling and/or other chemical cleaning, activation with titanium-containing sols (Jernstedt salts) or manganese phosphate sols, rinsing, and subsequent oiling or provision of other lubricant that at least adheres to and preferably is absorbed into the phosphate coating formed. Articles of manufacture including surfaces treated according to a process of the invention are also within the scope of the invention.
DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS
For a variety of reasons, it is sometimes preferred that compositions 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, when maximum storage stability of a concentrate, avoidance of possibly troublesome anions, and/or minimization of pollution potential is desired, it is preferred, with increasing preference in the order given, independently for each preferably minimized component listed below, that these compositions contain no more than 25, 15, 9, 5, 3, 1.0, 0.35, 0.10, 0.08, 0.04, 0.02, 0.01, 0.001, or 0.0002, percent of each of the following constituents: nitrite; halates and perhalates (i.e., perchlorate, chlorate, iodate, etc.); chloride; bromide; iodide; organic compounds containing nitro groups; organic molecules each of which contains at least two moieties selected from the group consisting of carboxyl, carboxylate, hydroxyl, peroxy, keto, aldehydo, amino, amido, substituted amido, nitrile, substituted amino, thio, ether, thioether, phosphino, and substituted phosphino moieties; hexavalent chromium; manganese in a valence state of four or greater; metal cations, other than manganese and iron, with a valence of two or more; ferricyanide; ferrocyanide; and pyrazole compounds. Furthermore, even though components such as these may not be harmful in some cases, they have not been found to be needed or advantageous in compositions according to this invention, and their minimization may therefore be preferred for economic reasons.
The dissolved divalent manganese cations required for component (A) may be obtained from any soluble manganese salt or from manganese metal itself or any manganese containing compound that reacts with aqueous acid to form dissolv
Cameron Mary K.
Green Anthony J.
Harper Stephen D.
Henkel Kommanditgesellschaft auf Aktien
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