Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2000-06-19
2002-11-26
Cain, Edward J. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S133000, C524S165000, C524S167000, C524S173000, C524S284000, C524S300000
Reexamination Certificate
active
06486245
ABSTRACT:
DESCRIPTION
The invention relates to a coating composition, to a formulation comprising said coating composition, to methods of coating surfaces with the coating composition, and to articles coated with the coating composition. The coating composition is based on a complex of polyelectrolytes and oppositely charged surfactants. The surfactants contain fluorine bonded covalently to carbon atoms. The coating material imparts oleophobic and/or hydrophobic properties to various surfaces. The degree of hydrophobicity and other properties such as, for instance, gas or moisture permeation can be adjusted over a wide range. Through the use of additives, the coating can be executed an a permanent or temporary coating. The readily variable profile of properties, the uncomplicated application, and the low coat thickness result in a wide scope for application as, for example, an antisoiling, antigraffiti or antiadhesion coating.
In the field of coating techniques, there exists a virtually innumerable number of different coating materials, each for very specific applications. In some cases a combination of polyelectrolytes and surfactants has been described.
DE 42 20 975 A1 describes oleophobic and/or permanent hydrophobic finishing for polymeric surfaces with a thin film. The film is formed from at least one layer of a water-soluble polycation and/or of a cationic synthetic resain. To further improve the oleophobic and/or permanently hydrophobic properties, the film may further comprise a long-chain surfactant or an alkyl-substituted polyanion. In the process described, the surface is first treated with a polycation solution and then treated, if desired, with an alkyl-substituted polyanion as second component or with a long-chain surfactant. Therefore, at least two different operations are required for coating. Furthermore, a prerequisite for application of the process is that the surface to be coated possesses a negative zeta potential.
This layer-by-layer construction by adsorption from aqueous solution has already been used for many years for scientific purposes and is described in a review by Decher (Science 277 (1997), 1232-1237).
International Patent Application Wo 96/11981 describes a fluorocarbon-containing additive which is applied subsequently to painted substrates and protects them against soiling or makes them easier to clean. These additives are based on discrete oligomers comprising a polyfunctional oligomeric core to which fluorinated alkyl chains are bonded covalently. The dirt repellency feature is achieved through the fluorinated alkyl chains, while adhesion to the paint is induced by the functionalized core. This type of protection by means of additives is strongly limited to well-defined, i.e. dust-free, painted surfaces. Furthermore, reaction times of from 6 hours to two weeks are necessary for preparing the fluorinated additives.
U.S. Pat. No. 5,330,788 describes a temporary coating for surfaces, developed in particular for protecting automobiles in transit. The coating is based on a film-forming acrylic acid polymer, a nonionic acetylenically unsaturated surfactant, if desired, a phosphate ester surfactant, and a base for neutralization. The coating material can be removed rapidly in contact with a special alkaline aqueous medium, which is likewise described in the patent. Extremely disadvantageous are, apparently, the long drying times for the coating, which are stated as being “overnight” or 24 hours. Since the principal component, the polyacrylic acid, is a polyelectrolyte which finds application as a super-absorbent (used, for example, in diapers and to improve the water retention capacity of arid soils), it cannot be assumed that these drying times, which are unreasonably long from an economic standpoint, might be substantially reduced.
U.S. Pat. No. 5,387,434 describes an antigraffiti composition whose protective action derives from sodium silicate. Since this is soluble in water, the interface between substrate and environment must be made hydrophobic. This is achieved by means of latex, silicones, or waxes. Particularly suitable are microcrystalline wax emulsions which are stabilized by sodium lignin-sulfonate. Graffiti removal requires high-pressure steam jets with a pressure of 100 psi, and temperatures of up to 90° C. Consequently, this process is suitable only for very specific substrates which permit these conditions without damage. No statement concerning the drying time of the coating can be found in the patent. However, it must be assumed that the crosslinking of the silicate requires several hours to days. Furthermore, it is likely that drying, which is retarded as a result of the added wax, will likewise take at least one day under dry conditions.
DE 36 30 520 C1 describes a process for protecting applications of color to surfaces of natural and synthetic stone. The process consists of two steps: first, an inorganic impregnation is applied, which is not specified in any great detail. This is followed by the application of a color-accepting, detachable, wax-like coating which can be removed by means of high-pressure hot water. Owing to the fact that it necessitates at least two different operations, this process is very time-consuming. In the case of typical inorganic impregnations, from at least one to three days are necessary given dry weather. Furthermore, this process is applicable only to a very limited number of specific substrates.
European Patent Application EP 0 695 772 A1 describes a class of fluorine-containing polyethers which are applied to masonry where they crosslink and form an impermeable antigraffiti film. The synthesis of the crosslinkable substances, however, is time-consuming and costly, and the raw material applied requires a drying time of 48 hours on the masonry in order to crosslink sufficiently. Furthermore, the field of use is limited to the coating of masonry.
Available on the market there is a surface protection is system from the company PSS (Protective Surface System) which is based or a polysaccharide mixture. According to an examination certificate from the German Federal Institute of Materials Research (Report No. 3.14.3441-91), effective protection against graffiti with the system PSS 20 requires three coats with drying times of from 24 to 72 hours in each case. Thus from 3 to 9 days are necessary for the application of the protective coat.
All of the abovementioned coating processes are characterized by a closely limited field of use and, in some cases, by drying times of several days for the protective coats.
DE-A-44 28 641 describes mesomorphic complexes comprising anionic polyelectrolytes, cationic polyelectrolytes and/or polyampholytes, and cationic, anionic, nonionic and/or amphoteric surfactants. As a consequence of the mesomorphic structure, generally improved material properties, such as increased mechanical strength, for example, are expected. The materials constructed of these amorphous or mesomorphic polyelectrolytes, such as films or membranes, include as an essential component surfactants having a hydrocarbon framework. Coatings with low-energy surfaces, however, cannot be produced using the fluorine-free complexes described therein.
Antonietti et al. (Adv. Mater. 8 (1996), 41-45) and Lochhaas et al. (Polyelectrolyte-surfactant complexes with fluorinated surfactants: A new type of material for coatings (3
rd
conference in the series: High Performance Coating Materials, Fluorine in Coatings II, Feb. 24-26, 1997, Munich, Germany) describe complexes comprising cationic polyelectrolytes and anionic fluorinated surfactants. Cationic polyelectrolyte components disclosed include polyacrylic acid, polymethacrylic acid, and poly(diallyldimethylammonium chloride). On contact with moisture these complexes have a very high propensity to absorb water; they swell rapidly and in doing so become soft to gelatinous. This leads to a considerable deterioration in the mechanical properties, so rendering them unsuitable for practical applications as coating material.
It is an object of the present invention to develop a
Lochhaas Helmut
Thunemann Andreas
Cain Edward J.
Fulbright & Jaworski L.L.P.
Nanogate Technologies GmbH
LandOfFree
Self-arranging coating does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Self-arranging coating, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Self-arranging coating will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2949443