Organic compounds -- part of the class 532-570 series – Organic compounds – Carbohydrates or derivatives
Reexamination Certificate
1999-09-23
2001-03-06
Wilson, James O. (Department: 1623)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carbohydrates or derivatives
C536S020000, C536S021000, C536S030000, C536S045000, C536S046000, C536S047000, C536S124000, C536S126000, C536S128000, C051S298000, C051S302000, C134S017000, C134S038000, C527S300000, C527S313000, C428S532000
Reexamination Certificate
active
06197951
ABSTRACT:
TECHNICAL FIELD
The invention described herein pertains generally to chemically modified starch blast media for use in coating removal applications. In general, the invention relates to polysaccharide polymers with grafted polymeric side chains, said grafted polymeric side chains being of essentially uniform molecular weight in that the graft copolymer is at least an oligomer, and sometimes, a polymer. More specifically, the invention relates to polysaccharide polymers unto which are grafted polymethyl methacrylate oligomers. The invention relates to a novel method of preparation of the polymethyl methacrylate graft copolymer polysaccharides in which the grafting component is at least oligomeric in nature and often, polymeric.
BACKGROUND OF THE INVENTION
Various methodologies and compositions have been taught in the prior art regarding the stripping of coatings from an underlying surface. A non-exhaustive list of such technologies would include:
U.S. Pat. No. 4,731,125 which discloses a process whereby paint is removed from composite by blasting with urea-formaldehyde plastic particles having a Mohs scale hardness of 2.5-3.5 with a flow at a pressure of 40 lb/in
2
;
U.S. Pat. No. 4,947,591 which discloses a process whereby paint is removed by impact with particles of an acrylic-containing unsaturated polyester where the particles are ground from a cured mass so as to have at least 40 facets per particle;
U.S. Pat. No. 5,112,406 which discloses a process for removing coatings from sensitive hard surface metal composite surfaces, masonry, stucco, plaster or wood by blasting the surfaces with a high velocity fluid stream containing water soluble crystalline sodium sulfate particles admixed with a hydrophobic silica or hydrophobic polysiloxane flow/anti-caking agent;
U.S. Pat. No. 5,160,547 which discloses a process where the surfaces are blasted with a water saturated compressed air stream under pressures of 10-150 psi using sodium bicarbonate particles having particle sizes of 250-300 microns in admixture with a hydrophobic silica flow/anti-caking agent;
U.S. Pat. No. 5,147,466 which discloses fine particles or oil films which are cleaned from the surface by bombarding it with fine frozen particles of water or other liquids such as glycerin carried in a stream of nitrogen cooled air under relatively low pressure;
U.S. Pat. No. 5,221,296 which discloses abrasives based on finely divided abrasive particles bonded to one another and/or to a support by means of a binder, where the binder is the solid component of an aqueous polymer dispersion which is obtainable by polymerizing unsaturated monomers which can be polymerized by means of free radicals, in the aqueous phase of a monosaccharide, oligosaccharide, polysaccharide, oxidatively, hydrolytically and/or enzymatically degraded polysaccharide, chemically modified monosaccharide, oligosaccharide or polysaccharide or a mixture of the above;
U.S. Pat. No. 5,308,404 which discloses a process by which contaminants are removed from substrates by blast clearing with a media containing abrasive particles obtained by compacting fine particles of the abrasive into larger particles having a hardness of 2-5 Mohs, and wherein the abrasive can be water (soluble or insoluble) and is preferably sodium bicarbonate or calcium carbonate;
U.S. Pat. No. 5,316,587 which discloses blast cleaning a solid surface which includes the steps of propelling an abrasive blast medium against a solid surface using a water-containing pressurized fluid stream to strip contaminants from the surface wherein the blast medium comprises water soluble abrasive particles and a surfactant;
U.S. Pat. No. 5,322,532 which discloses a process for removing contaminants from a substrate comprises blast cleaning the substrate with composite abrasive particles formed by agglomerating particles of sodium bicarbonate with an aqueous binder solution of sodium carbonate;
U.S. Pat. No. 5,360,903 and U.S. Pat. No. 5,367,068 which disclose a process whereby a surface is treated with particles of a glassy polysaccharide wherein the apparent hardness of the granules is between that of the coating and of the substrate and the granules are of starch, preferably wheat starch, with dextrose equivalent less than 10, preferably unhydrolyzed;
U.S. Pat. No. 5,367,838 which discloses a method wherein ice particles are supplied to the apparatus from an ice supply and a fluidizing device provides a fluidizing flow of the ice particles entrained in cold dry air;
U.S. Pat. No. 5,380,347 which discloses the preparation of blast media useful in stripping contaminants from solid surfaces which comprises forming a surfactant-clathrate compound comprising a surfactant and a water soluble compound having clathration properties and incorporating the compound with abrasive particles; and
U.S. Pat. No. 5,427,710 which discloses a composition useful for removing polymeric coatings from flexible and inflexible surfaces which consists essentially of a conjugated terpene, an alcohol, a non-conjugated terpene, a surfactant, and an organo-clay rheological additive.
While all of the above references have contributed to the science of blast media development, there still exists a need for a product which quickly removed paint from a surface, yet which does not harm the surface through the removal process.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided a chemically modified polysaccharide blast media for use in coating removal applications.
It is an object of this invention to provide a polysaccharide polymer onto which is grafted a poly(meth)acrylate oligomer useful in coating removal applications.
It is another object of this invention to provide a blast media with coating removal rates similar to Type V media (thermoset methyl methacrylate polymer in abrasive form) for commercial aircraft fuselage paint removal.
It is still another object of this invention to provide a blast media suitable for use on thin skin clad aluminum and delicate composite panels.
These and other objects of this invention will be evident when viewed in light of the drawings, detailed description, and appended claims.
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patent: 5427710 (1995-06-01), Stevens
patent: 5780619 (1998-07-01), Lenz
Archer Daniels Midland Company
Laff Whitesel & Saret
Wilson James O.
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