Coating processes – Direct application of electrical – magnetic – wave – or... – Electrostatic charge – field – or force utilized
Reexamination Certificate
2000-06-30
2001-09-18
Parker, Fred J. (Department: 1762)
Coating processes
Direct application of electrical, magnetic, wave, or...
Electrostatic charge, field, or force utilized
C427S133000, C427S135000, C427S476000, C427S485000
Reexamination Certificate
active
06291026
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to mold-release agents for mold surfaces and, more particularly, to a method for forming a mold-release coating using a release powder electrostatically deposited on a mold surface.
2. Description of the Related Art
In the process of making molded polymeric foam parts, such as polyurethane foam parts, foam precursor material is first admitted into a mold and, subsequently, the foam precursor material is caused to foam and cure, taking on the shape of the mold's interior.
The interior surfaces of the mold are usually coated with a wax mold-release agent before every molding operation. The wax mold-release agent allows complete and easy removal of the molded part. Typically, the wax mold-release agent is spray-applied onto the mold surface.
Current wax mold-release agents include solvent-based and water-based agents. Solvent-based wax mold release agents are applied to the interior surface of molds and allowed to dry. These agents are applied before every molding operation or frequently between molding operations. However, during the drying step, volatile organic compounds are evolved, requiring precautions to avoid human exposure. With the increased awareness of environmental protection, such solvent-based wax mold-release agents are becoming obsolete.
Water-based wax mold-release agents result in substantially less evolution of volatile organic compounds than do the solvent-based wax mold-release agents. Water-based wax mold-release agents are also applied before every molding operation or frequently between molding operations. Although they contain much less volatile organic compounds than solvent-based wax mold-release agents, water-based wax mold-release agents are not without problems.
One problem with water-based wax mold-release agents is that they still contain a small amount of volatile organic compounds which are evolved during the coating process. Secondly, water-based wax mold-release agents gradually build-up on the mold surface causing undesirable changes in the mold's dimensions or contours. Thirdly, water-based wax mold-release agents are more expensive than solvent-based wax mold-release agents. Lastly, water-based wax mold-release agents require longer drying times than do solvent-based wax mold-release agents.
A problem with using as a mold release agent is that there remains wax deposit on the surface of the part after removal, along with was build-up on the mold itself.
SUMMARY OF THE INVENTION
It is, therefore, one object of the present invention to provide a method for forming a mold-release coating on a mold surface without using a wax.
It is another object of the present invention to provide a method for forming a mold-release coating on a mold surface which requires less time, labor, and materials than do prior art methods.
It is yet another object of the present invention to provide a method for forming a mold-release coating on a mold surface which reduces the amount of volatile organic compounds evolved relative to using solvent-based wax mold-release agents.
It is yet another object of the present invention to provide a method for forming a mold-release coating on a mold surface which does not deleteriously alter the mold's dimensions or contours.
It is still another object of the present invention to provide a mold release coating which significantly reduces flammability as compared to wax mold-release agents.
It is a further object of the present invention to provide a mold release coating which increases the ability to adhere a cloth material to a foam molded part.
It is still a further advantage of the present invention to provide a mold release coating that allows a foam molded part to be painted.
It is a further object of the present invention to provide a mold release coating which minimizes periodic cleaning of the molds.
To achieve the foregoing objects, the present invention is a method for forming a mold-release coating on a mold surface. The method includes two basic steps: (a) providing a base coat of material on the mold surface and (b) electrostatically depositing a release powder onto the base coat of material. The base coat of material has a surface which is capable of accepting and retaining the release powder. Upon deposition of the release powder, the release powder embeds the base coat material thereby forming a mold-release coating. The base coat may periodically be applied to the mold, as properties or a portion thereof diminishes. The release powder is electrostatically applied before each molding operation.
A more specific embodiment of the present invention includes providing a base coat of solvent base wax to the mold which substantially remains on the mold during subsequent molding operations.
One advantage of the present invention is that a method for forming mold-release coatings is provided without using a wax as a mold release agent. Another advantage of the present invention is that the method provided for forming mold-release coatings requires less time, labor, and materials than do prior art methods. Yet another advantage of the present invention is that the method provided for forming mold-release coatings uses less volatile organic compounds than do methods which use conventional solvent-based wax mold-release agents. Still another advantage of the present invention is that the method provided for forming mold-release coatings does not deleteriously alter the mold's dimensions or contours by wax build-up as do wax mold-release agents. A further advantage of the present invention is that the mold-release coatings significantly reduce flammability and increase the ability to adhere a cloth material and paint a foam molded part as compared to wax mold-release agents. Yet a further advantage of the present invention is that the mold-release coatings reduce periodic cleaning of the molds because there is no wax build-up on the surface of the part.
REFERENCES:
patent: 2795512 (1975-06-01), Sherratt et al.
patent: 3101244 (1963-08-01), Hood et al.
patent: 3127457 (1964-03-01), Di Pinto
patent: 3279936 (1966-10-01), Foresteck
patent: 3341646 (1967-09-01), Britain
patent: 3492394 (1970-01-01), Heine
patent: 3598626 (1971-08-01), Probst et al.
patent: 3624190 (1971-11-01), Cekada, Jr.
patent: 3671007 (1972-06-01), Bailey et al.
patent: 3883628 (1975-05-01), Martin
patent: 3925530 (1975-12-01), Rees
patent: 3928673 (1975-12-01), Pardee et al.
patent: 3931381 (1976-01-01), Lindberg
patent: 3995979 (1987-12-01), Fedrigo
patent: 4110119 (1978-08-01), Boehmke et al.
patent: 4118235 (1978-10-01), Horiuchi et al.
patent: 4131662 (1978-12-01), Cekoric et al.
patent: 4281032 (1981-07-01), Escott et al.
patent: 4308063 (1981-12-01), Horiuchi et al.
patent: 4312672 (1982-01-01), Blahak et al.
patent: 4427803 (1984-01-01), Fukui et al.
patent: 4681712 (1987-07-01), Sakakibara et al.
patent: 4892585 (1990-01-01), Fischer et al.
patent: 5021109 (1991-06-01), Petropoulos et al.
patent: 5028366 (1991-07-01), Harakal et al.
patent: 5035849 (1991-07-01), Uemura et al.
patent: 5039435 (1991-08-01), Hanano
patent: 5212245 (1993-05-01), Franks et al.
patent: 5628956 (1997-05-01), Theusner et al.
patent: 2621255 (1977-11-01), None
patent: 2193143 (1988-03-01), None
patent: 5648276 (1979-09-01), None
patent: 5964318 (1982-05-01), None
patent: 5910691 (1983-01-01), None
Hawley's Condersed Chemical Dictionary, 13thEdition, Revised by Richard J. Lewis Sr., pp. 897-898, 906, 1178, 1997.*
“Hawley's Condensed Chemical Dictionary” Richard J. Lewis, Sr., 13th addition, pp. 897-898.
Hanson Bror H.
Hunter Douglas L.
Bliss McGlynn P.C.
Parker Fred J.
Polymerit
LandOfFree
Method for forming a mold-release 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 Method for forming a mold-release coating, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for forming a mold-release coating will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2542192