Cleaning and liquid contact with solids – Processes – For metallic – siliceous – or calcareous basework – including...
Reexamination Certificate
2000-04-26
2002-07-30
Carrillo, Sharidan (Department: 1746)
Cleaning and liquid contact with solids
Processes
For metallic, siliceous, or calcareous basework, including...
C134S010000, C134S013000, C134S026000, C134S029000, C510S248000, C510S252000
Reexamination Certificate
active
06425955
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to management of a cleaning process that removes metal salts of intermediate length carboxylic acids, i.e., fatty acids with from 10 to 22 carbon atoms per molecule, from surfaces where such salts are present over an underlying solid, water resistant substrate, particularly a metal substrate. The remainder of this description will be in terms of metal substrates, but it should be understood that the invention is equally applicable, mutatis mutandis, to cleaning from any solid substrate that is not damaged by contact with water and the other constituents of the cleaning compositions described below. The metal substrate may or may not have other surface layers such as phosphate conversion coatings; anodized coatings; complex oxide layers such as those that can be formed with a commercially available product named BONDERITE® 770X from the Henkel Surface Technologies Div. of Henkel Corp., Madison Heights, Mich.; or the like underlying the coating of metal intermediate length carboxylate salt(s). Such metal salts, particularly water-insoluble ones, are widely used as lubricants for cold drawing of steel and other metals, usually over a phosphate or other conversion coating that is believed to act as a “carrier” for the lubricative metal intermediate length carboxylate salt(s). After cold drawing has been completed, in most instances the metal intermediate length carboxylate salt(s) and any underlying conversion coating need to be removed before further processing of the metal article that has been cold drawn.
Such removal/cleaning has been conventionally accomplished with strongly alkaline cleaners, preferably also containing sequestering agents for the metal cations in any underlying conversion coating, when such a coating is present, and surfactants to aid in wetting of the surface and dispersion and removal of soils. However, when substantial amounts of metal intermediate length carboxylate salt(s) have been dissolved in such a cleaner, it becomes strongly prone to foaming, which causes practical difficulties in processing. Up to now, surfactant anti-foam agents have been primarily used to control such foaming, but their success leaves much to be desired in many practical operations: Even if foaming is effectively prevented, as is by no means always accomplished, solid residues on various parts of the process equipment tend to accumulate with continued use of a fixed volume of cleaner. Accordingly, a major object of this invention is to provide a method of avoiding impractical amounts of foaming during cleaning of metal intermediate length carboxylate salt(s) from underlying metal substrates, thereby achieving cleaning results that are more economical, more consistent in cleaning quality, or both. Other 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, throughout the description, unless expressly stated to the contrary: percent, “parts of”, and ratio values are by weight or mass; 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 within the composition by chemical reaction(s) noted in the specification between one or more newly added constituents and one or more constituents already present in the composition when the other constituents are added, and does not necessarily preclude unspecified chemical interactions among the constituents of a mixture once mixed; specification of constituents in ionic form additionally implies the presence of sufficient counterions to produce electrical neutrality for the composition as a whole and for any substance added to the composition; any counterions thus implicitly specified preferably are 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 an object of the invention; the word “mole” means “gram mole”, and the word itself and all of its grammatical variations may by used for any chemical species defined by all of the types and numbers of atoms present in it, irrespective of whether the species is ionic, neutral, unstable, hypothetical, or in fact a stable neutral substance with well defined molecules; and the terms “solution”, “soluble”, “homogeneous”, and the like are to be understood as including not only true equilibrium solutions or homogeneity but also dispersions that show no visually detectable tendency toward phase separation over a period of observation of at least 100, or preferably at least 1000, hours during which the material is mechanically undisturbed and the temperature of the material is maintained within the range of 18-25° C.
BRIEF SUMMARY OF THE INVENTION
It has been found that at least the major object of the invention as stated above can be achieved by an essentially different means from the use of antifoam agents as the only aid to foam control: The intermediate length carboxylate anion(s), which have been found to be the major cause of the foaming tendency exhibited by an aqueous liquid alkaline cleaning composition containing them, are precipitated by addition of appropriate cations (for example, Ca, Mg, or Ba) that will form, together with the already present intermediate length carboxylate anions, salts that are substantially insoluble in the alkaline cleaning composition. The precipitated salts can be removed from the used aqueous liquid alkaline cleaning composition by filtration, by allowing the precipitated salts to settle as a sludge and then draining the sludge from the bottom of a holding tank, by skimming any floating precipitate off a holding tank for the circulating cleaning composition, and/or by any other suitable method for separating solids from liquids, many of which are known to those skilled in the art. After the intermediate length carboxylate anions have been thus removed from the cleaning composition, the composition can be re-used indefinitely, without any foaming problems, as long as any ingredients consumed during use are replenished and any subsequent accumulations of intermediate length carboxylate anions in the composition are removed when needed by repetition of the removal steps described above. In most instances, no specific anti-foam agent at all needs to be used in the aqueous liquid alkaline cleaning composition when intermediate length carboxylate anions are removed from the composition whenever the concentration of these anions exceeds a selected value, although a small amount of anti-foam agent may be useful in some instances. Thus the cost of anti-foam agents is avoided or at least very much reduced.
A clean surface suitable for immediate further processing of the cold-drawn metal substrate can normally be achieved, after the cleaning as described above, by rinsing any residue of cleaning solution from the cleaned substrates in sufficiently hot water to cause the substrate to flash dry by evaporation after rinsing.
DETAILED DESCRIPTION OF THE INVENTION
At a minimum, a process according to the invention for cleaning an article having a solid surface that includes metal intermediate length carboxylate salt(s) and an underlying metal substrate preferably comprises, more preferably consists essentially of, or still more preferably consists of, the following steps:
(I
Church Richard J.
Hacias Kenneth J.
Carrillo Sharidan
Harper Stephen D.
Henkel Corporation
Ortiz Daniel S.
LandOfFree
Process for avoiding foaming during cleaning of metal salts... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for avoiding foaming during cleaning of metal salts..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for avoiding foaming during cleaning of metal salts... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2874220