Stock material or miscellaneous articles – Composite – Of polyimide
Reexamination Certificate
2001-05-04
2002-11-19
Niland, Patrick D. (Department: 1714)
Stock material or miscellaneous articles
Composite
Of polyimide
C427S058000, C427S096400, C427S372200, C427S385500, C427S388100, C427S393500, C428S458000, C428S474400
Reexamination Certificate
active
06482529
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates broadly to polymeric coating compositions suitable for providing a coating which is solderable and/or has high corrosion resistance and to substrates coated with the same. The coated substrates have improved properties, most importantly, resistance to hostile environments such as corrosive liquids and gases. Furthermore, the coated substrates the ability to be soldered without breaching the polymeric coating and/or electroplated. The invention further relates to methods for producing the polymeric coating compositions and polymer coated substrates.
2. Description of the Related Art
Several publications are referenced in this application. These references describe the state of the art to which this invention pertains, and are incorporated herein by reference.
Polymers have been grafted onto metallic substrates to form coatings that protect the substrates from a variety of environmental conditions. Typically organic coatings and paints are applied onto metallic substrates via a physical bond and act to protect the substrate from corrosive gases, solutions of high or low pH, varying relative humidity and varying temperature conditions. Such physically bonded coatings typically do not provide adequate protection against corrosion or other environmental impacts and have a tendency to become dislodged from the surface of the substrate after relatively short periods of time, particularly under stresses imposed by severe environmental conditions, e.g. the presence of acids or bases, corrosive gases such as hydrogen sulphide, sulphur dioxide and carbon dioxide.
Metal substrates have been coated with polymers by graft polymerization processes with results that are superior to those obtained where the metal substrate is coated with organic paints or coatings. Such grafted coatings are both conductive and provide a durable protective layer which is resistent to severe environmental conditions. U.S. Pat. No. 5,043,226 to Wiedeman, et al. describes methods for applying graft polymers to a variety of metal substrates such as steel, aluminum, iron and other metals.
It is important in many applications that the metal coated substrate have not only excellent corrosion and abrasion resistance as well as resistance to adverse environmental conditions, but that the coated metal also have satisfactory conductivity and solderability, so that it can be used in a variety of industrial applications. Heretofore, the art has not provided polymer coated metal substrates having both a tenaciously bound polymer layer which is corrosion resistant and the necessary properties of conductivity and solderability.
OBJECTS OF THE INVENTION
It is an object of the invention to overcome the above-identified deficiencies.
It is a primary object of this invention to provide a polymer coating composition for a substrate wherein the polymer is grafted to the substrate and tenaciously bound thereto.
It is a further object of the invention to provide a polymer-coated substrate which is highly resistant to abrasion and corrosion as well as to a variety of hostile environmental conditions, including humidity, temperature, pH, chemical attack, etc.
It is still a further related object of this invention to provide a polymer-coated substrate in which the polymer-coating is tenaciously bound to the metal substrate and does not admit of bubbling, cracking or other failure which exposes the substrate to environmental conditions, and, which further has satisfactory conductivity and solderability characteristics such that a metallic or non-metallic substrate, for example, can be used in a variety of industrial applications.
It is still a further and related object of this invention to provide a method for producing such polymer-coated substrates.
It is still a further and related object of this invention to provide such a process wherein the polymer-coating can be relatively inexpensively applied to a variety of substrates.
The foregoing and other objects and advantages of the invention will be set forth in or apparent from the following description.
SUMMARY OF THE INVENTION
The invention relates to novel polymeric coating compositions suitable for coating substrate materials. The polymeric composition according to the invention comprises:
(i) from 25 to 99 parts by wt of a poly(amide-imide) prepolymer;
(ii) from 1 to 25 parts by wt of trifunctional ester, preferably a methacrylate ester of the formula:
(iii) from 0.5 to 15 parts by wt of a organo-reactive silane monomer, preferably an organo-reactive silane of the formula:
H
2
N(CH
2
)
n
Si(OC
2
H
5
)
3
wherein n is an integer from 2 to 20.
According to one preferred embodiment, the coating is a conductive coating comprising conductive additives.
Surprisingly, it has been found that the polymer composition can be applied to a variety of substrates including steel, stainless steel, iron, brass, copper, aluminum, platinum, titanium, silver, gold, Telfon, plastics, glass and others, and that the coated substrate has both excellent resistance to abrasion and corrosion as well as highly desirable properties of conductivity and solderability. Thus, the coated substrates can be used in a variety of products which are exposed to hostile environmental conditions (including high humidity, temperatures, pressures and corrosive gases) while being fabricated into various sub-components and packaging.
For example, it has now been found that polymer-coated components produced according to the invention can be soldered directly through the polymer coating without breaching that coating and exposing the underlying substrate to environmental conditions. This is a vast improvement over prior art practices which required that the polymer coating be scraped away to expose the substrate to the soldering or welding operation.
The coated substrates in the invention can be efficiently and economically prepared by a graft polymerization procedure which includes the steps of:
(a) forming a prepolymer mixture comprising:
(i) from 25 to 99 parts by wt of a poly(amide-imide) prepolymer;
(ii) from 1 to 25 parts by wt of a trifunctional ester; and
(iii) from 0.5 to 15 parts by wt of an organo-reactive silane;
(iv) a solvent for said components (i)-(iii); and
(v) an effective amount of nickel powder;
(b) applying said prepolymer mixture to the surface of said substrate; and
(c) curing said prepolymer mixture.
Accordingly, the invention also relates to a coated substrate comprising a substrate and a polymeric coating thereupon.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The polymeric coating composition of the present invention is comprised of three different monomeric units, at least one poly(amide-imide) prepolymer, at least one trifunctional ester and at least one organo-reactive silane.
The composition is formed by forming a mixture of monomers containing all three of the aforedescribed components. Broadly, the mixture contains from 25 to 99 parts by wt of the poly (amide-imide) prepolymer, from 1 to 25 parts by wt of the trifunctional ester, and from 0.5 to 15 parts by wt of the organo-reactive silane. Desirably the mixture contains from 70 to 99 parts by wt of the poly (amide-imide) prepolymer, from 5 to 20 parts by wt of trifunctional ester and from 0.5 to 5 parts by wt of the organo-reactive silane monomer. Best results are obtained where the polymeric composition comprises from 85 to 95 parts by wt of the poly (amide-imide) prepolymer, from 5 to 15 parts by wt of the ester and from 1 to 5 parts by wt. of the silane.
The major component of the polymeric composition is a reactive poly (amide-imide). The monomer is fairly low in molecular weight and is readily soluble in organic solvents. The poly (amide-imide) may be, for example, composed of trimellitic, aromatic amide and aromatic imide moieties. AMOCO Al-10 Polymer, available from AMOCO Oil Company, is a suitable component. As supplied, Al-10 Polymer is approximately 50% in the un-imidized or amic acid form. These two-forms of polymer are shown below:
Other suitable polyamides-im
Greenwood Edward
Horowitz Carl
Sanduja Mohan L.
Thottathil Paul
Zilberman Lina
Alchemetal Corp.
Evans, Esq. Barry
Kramer Levin Naftalis & Frankel LLP
Niland Patrick D.
LandOfFree
Polymeric coating compositions, polymer coated substrates,... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Polymeric coating compositions, polymer coated substrates,..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Polymeric coating compositions, polymer coated substrates,... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2942418