Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
1999-03-25
2001-02-13
Sanders, Kriellion (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S096000, C524S244000, C524S245000, C524S251000, C524S487000, C524S062000
Reexamination Certificate
active
06187849
ABSTRACT:
FIELD OF INVENTION
The present invention relates to temporary protective coating compositions which are useful in the passivation of untreated metallic substrates. More specifically, the invention relates to formable, weldable aqueous temporary protective coatings which are compatible with the variety of adhesives and sealants used in the assembly of automobiles.
BACKGROUND OF THE INVENTION
Metallic substrates such as steel sheet which are produced in steel mills are treated shortly after manufacture to prevent rusting and corrosion of the sheet prior to being formed into the desired parts. Typically mill oils, such as FERROCITE 61 AUS available from Quaker Chemical Corp., DRAWCO FB 27 MC-1 available from Novamax Technologies, Inc., and MONTGOMERY DB 4265 available from Fuchs Lubricants Co. have been used for this purpose.
The mill oils are typically removed after the metallic substrates are formed into parts. Mill oils and film-forming materials, however, are often difficult to remove completely and can be incompatible with subsequently applied organic materials, for example, primer coatings, adhesives and sealants.
In place of mill oils, organic polymers have also been employed as passivating agents for steel sheet. These materials generally provide better corrosion resistance than do mill oils and are easier to remove. However, depending on the organic polymer used, small residual amounts can remain on the surface of the metallic substrate. Although compatible with most subsequently applied primer coatings, these organic polymer residues are often incompatible with subsequently applied adhesives and sealants which are used in the assembly of automobiles.
Temporary protective coating compositions are known in the art. U.S. Pat. No. 4,942,193 discloses a formable, weldable temporary protective coating for metallic substrates which comprises a neutralized acid or base-functional polymer prepared in the presence of a lubricating composition consisting essentially of a relatively high level of a wax. The coating is particularly useful to provide in-transit corrosion resistance.
U.S. Pat. No. 5,081,174 discloses a formable, weldable, removable coating for use on untreated metals comprised of a base-neutralized, acid fuctional copolymer, a wax lubricant and a removability enhancing material such as phosphoric acid present at additive levels to improve the removability of the coating from metallic substrates by aqueous alkaline cleaners. The coatings provide corrosion resistance, are formable and/or drawable, weldable by conventional means, and can be removed with alkaline cleaners.
U.S. Pat. No. 5,229,450 discloses formable, weldable temporary protective aqueous coating compositions useful in passivating untreated metallic substrates. The coatings are comprised of a neutralized acid or base-functional polymer and a lubricating composition in an amount sufficient to impart drawability and formability to the metallic substrates to which they are applied. The coatings provide corrosion resistance, are formable and/or drawable, and weldable by conventional means, and can be removed with alkaline cleaners.
Although the above-described temporary protective coatings provide excellent in-transit corrosion resistance, weldability and formability, the coatings are often incompatible with subsequently applied adhesives and sealants.
It has been found that by using a polymer having a relatively high level of acid functional monomer present, compatibility of the temporary protective coating with a wide variety of adhesives and sealants can be improved.
SUMMARY OF THE INVENTION
In accordance with the present invention, provided is a temporary protective coating composition which when deposited and dried on a metallic substrate, is removable by contacting with an aqueous alkaline cleaning solution, the coating comprising (a) a wax present in an amount up to 20 weight percent; (b) a base-neutralized, acid functional polymer which is the polymerization reaction product of (i) a polymerizable, ethylenically unsaturated monomer having acid functionality and (ii) at least one polymerizable ethylenically unsaturated monomer different from (i); and (c) an amine containing an acrylic moiety of from 8 to 30 carbon atoms, the amine being different from the base used to neutralize the acid functional polymer (b).
Other than in the operating examples, or where otherwise indicated, all numbers expressing quantities of ingredients or reaction conditions used in the specification or claims are to be understood as being modified in all instances by the term “about”. Also, as used herein, the term “polymer” is meant to include oligomers.
DETAILED DESCRIPTION OF THE INVENTION
Examples of waxes suitable for use in the present invention include natural waxes such as petroleum waxes, e.g., paraffin waxes and hydrocarbon waxes; mineral waxes, e.g., montan wax; vegetable waxes, e.g., carnauba wax; and synthetic waxes such as Fischer-Tropsch waxes and polyethylene waxes. Preferably the wax component (a) is a hydrocarbon wax, more preferably a branched hydrocarbon wax having a melting point ranging from 40° C. to 90° C., preferably from 50° C. to 80° C., and more preferably 55° C. to 75° C.
Typically, the wax component (a) is present in the temporary protective coating of the invention in an amount up to 20 weight percent, preferably from 1 to 15 weight percent, and more preferably from 2 to 12 weight percent based on total solids content of the coating.
The temporary protective coating of the invention also comprises (b) a base-neutralized, acid functional polymer, the polymer comprising (i) a polymerizable, ethylenically unsaturated monomer having acid functionality and (ii) at least one other polymerizable, ethylenically unsaturated monomer different from (i).
Examples of suitable polymerizable, ethylenically unsaturated monomers having acid functionality include, but are not limited to, acrylic acid and or methacrylic acid (cumulatively referred to herein as “(meth)acrylic acid”), crotonic acid, itaconic acid, maleic and combinations thereof.
Examples of polymerizable, ethylenically unsaturated monomers different from (i) above suitable for use as component (ii) include alkyl esters of (meth)acrylic acid, for example methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethyl hexyl (meth)acrylate and the like. Other suitable polymerizable, ethylenically unsaturated monomers include vinyl aromatic compounds, for example, styrene and vinyl toluene; nitriles such as acrylonitrile and methacrylonitrile; vinyl and vinylidine halides such as vinyl chloride and vinylidene fluoride; and vinyl esters such as vinyl acetate. Hydroxy alkyl esters of (meth)acrylic acid, for example hydroxyethyl (meth)acrylate and hydroxypropyl (meth)acrylate, may also be used.
In a preferred embodiment of the invention functional monomer (i) is acrylic acid and the polymerizable, ethylenically unsaturated (ii) is comprised of styrene and butylacrylate.
Typically, the polymerizable, ethylenically unsaturated monomer having acid functionality (i) is present in the base-neutralized acid functional polymer in an amount ranging from 10 to 50 weight percent, preferably from 20 to 40 weight percent, and more preferably from 25 to 35 weight percent based on total weight of monomers in the polymer.
Also, the polymerizable, ethylenically unsaturated monomer (ii) which is different than (i) is typically present in the base-neutralized acid functional polymer in an amount ranging from 90 to 50 weight percent, preferably from 80 to 60 weight percent, and more preferably from 75 to 65 weight percent based on total weight of monomers in the polymer.
The base-neutralized acid functional polymer (b) may be prepared by conventional free-radical solution polymerization techniques in the presence of suitable catalysts such as benzoyl peroxide, t-amyl peroxy-2-ethyl hexanoate or N, N-azobis (isobutyronitrile).
The polymerization is preferably carried out in the presence of the wax component (a) in an organic solvent in which the monomers and the wax
Gray Ralph C.
Jones Dennis W.
Nugent, Jr. Richard M.
Pawlik Michael J.
PPG Industries Ohio Inc.
Sanders Kriellion
Uhl William J.
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