Plastic and nonmetallic article shaping or treating: processes – Mechanical shaping or molding to form or reform shaped article – Shaping against forming surface
Reexamination Certificate
2000-05-10
2002-12-17
Heitbrink, Jill L. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Mechanical shaping or molding to form or reform shaped article
Shaping against forming surface
C264S328100, C264S338000, C106S038240, C106S038350
Reexamination Certificate
active
06495084
ABSTRACT:
BACKGROUND OF THE INVENTION
When a solid macroscopic article of manufacture is made by molding an initially solid sheet or powder, a liquid, or a mixture of liquids or of both liquid and solid raw material(s) into a shape and size defined by a mold cavity, at least part of the surface of the solid macroscopic article of manufacture thus made may adhere to the surface of the mold cavity that shapes its final form so strongly that the molded article can not be removed from the mold cavity without damaging the molded object, the mold cavity surface, or both. To minimize the likelihood of this undesired result, a thin layer of a substance called a “mold release agent” or a similar name, this mold release agent being a substance chemically distinct from both the surface of the mold cavity and from the raw material(s) used to form the molded article, is often coated over the surface of the molding cavity before the raw material(s) to be molded are introduced into the molding cavity.
A first mixture of chemically distinct individual chemical substances is to be understood for purposes of this definition to be chemically distinct from a second mixture of chemically distinct individual chemical substances if any one of the following conditions is true: The second mixture contains at least one chemical substance that is not in the first mixture; the first mixture contains at least one chemical substance that is not in the second mixture; or there is a ratio of the amount of a first chemical substance in the first mixture to the amount of a second chemical substance in the first mixture, the amounts of said first and second chemical substances in said first mixture being expressed in the same units, that is different, by an amount of at least five percent of its own value, from the ratio of the amount of said first chemical substance in the second mixture to the amount of said second chemical substance in the second mixture, said amounts of said first and second chemical substances in said second mixture being expressed in the same units.
In some molding operations, part of the raw materials to be molded may constitute at least one solid body that covers part of the molding surface of the molding cavity and may need to be positioned rather precisely over a particular part of the molding surface, so that other constituents of the raw materials for the molding operation can be kept from contact with the parts of the mold cavity not in contact with this/these solid body or bodies. Any such solid body may be designated hereinafter as a “positioned molding insert”. In order to facilitate the precise positioning of any such positioned molding insert, a substance usually called a “molding aid” may be applied to the surface of the positioned molding insert, the mold cavity surface, or both, in order to reduce the energy input that would be required, in the absence of any molding aid, to move the positioned molding insert laterally over the surface of the molding cavity into the precise position where it is desired.
A particular practical instance where such a molding aid is needed is the manufacture of some instrument panels for automobiles. A thin sheet of a vinyl plastic, which will form a “skin” for the final instrument panel, is placed over part of the molding surface for the final molding operation. This plastic sheet is held in place by vacuum applied to small holes in the molding surface and often needs to be repositioned from its first placement on the surface, to have wrinkles in the initial placement smoothed out, or the like. Once the vinyl plastic sheet has been positioned over precisely the desired part of the molding surface for this final molding operation, a reinforcing structure is also put into the molding cavity, which is then closed except for an injection port through which are injected fluid materials that will react to form a solid urethane foam that fills, when the gas filled cells of the foam are considered to be as space filling as the solid parts of the foam, all parts of the molding cavity not already occupied.
This invention relates to compositions that are suitable for use as at least one of molding aids, mold release agents, and any other facilitators of desired motion between a solid molding surface and at least one of (i) a volume of raw material that is to be converted into a solid, molded, macroscopic article of manufacture that has a shape and/or size that is least partially different from that of any individual solid part of the raw material but that conforms to the molding surface and (ii) a solid macroscopic article of manufacture that conforms to the molding surface and has been formed from a volume of raw material that is entirely liquid or contains one or more solid parts, any such solid part being different in shape, size, or both from the last previously aforesaid solid macroscopic article of manufacture. Any such composition may be denoted hereinafter as a “molding facilitator”.
Difference or sameness between shapes and/or sizes of two distinct solid objects is to be evaluated by comparison to normal prior art standards of precision of shape and size for the solid macroscopic articles of manufacture produced by the molding operation being performed.
One currently commercially used molding aid for the manufacture of automobile instrument panels as described above is a material known in the art as “banana wax”. No details of its chemical composition are known with certainty to the applicants, but it is believed to be an emulsion in water of some waxy solid. When freshly applied, the liquid “banana wax” is effective for its intended use in facilitating the lateral motion of a piece of thin vinyl plastic sheet over a portion of the surface of the molding cavity that includes small holes in which a partial vacuum is maintained during use, to prevent undesired motion of the properly positioned piece of vinyl sheet during the molding process. Also, when freshly applied the liquid “banana wax” can readily be rinsed away by water from any surface when the presence of “banana wax” on the surface is no longer desired. However, the mold surface against which the piece of vinyl plastic sheet is held, with residual “banana wax” between the sheet and the molding surface, is heated during use to 38±6° C., thereby speeding evaporation of water from the liquid “banana wax” composition.
It has often been observed in practice that solid, liquid, or both solid and liquid residues from part of the initially applied liquid “banana wax” remain on at least a portion of the surface of the final molded instrument panel produced in the process and adhere strongly enough that the residues can not be removed even by power washing. Adhesion of subsequently applied paint to any part of the molded article surface that was contaminated with residues before the surface was painted is generally inadequate. Furthermore, liquid and/or solid residues from the initially applied liquid “banana wax” composition may remain on the molding surfaces also and be impossible to remove by rinsing with water only. If left in place on the molding surface, such residues may transfer to the surface(s) of other article(s) later molded by the same molding surface. It is also believed that some of the “banana wax” may migrate into the interior of the molded article produced in a molding process that utilizes it and that any such migration could damage the functioning and/or durability of the molded article.
All of these shortcomings of “banana wax” apply with at least equal detriment to any other commercial preparation for the same purpose that has been tested.
Accordingly, the major object of this invention is to provide a composition for use as a molding facilitator that will remain readily rinseable with water even after completely drying and will otherwise function at least as satisfactorily as the prior art material known as “banana wax”. Other alternative and/or concurrent objects are to minimize migration of any constituent of the molding facilitator into the interior of any object molded in
Held, III Theodore D
Lasky Douglas J
Harper Stephen D.
Heitbrink Jill L.
Henkel Corporation
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