Method for making hard mold

A hard mold and method of preparing the mold is disclosed. The hard mold is designed for manufacturing articles having various shapes and patterns. The shaping mold includes a layer of hardened material provided over the entire surface of the selected master. The inventor has found that a polyurea coating or other polyurethane hybrid is preferred. Once the layer of hardened material has dried, the surface of the hardened material is sanded with a 20-40 grit sandpaper and a layer of polyester resin is then applied to the layer of hardened material. Once the polyester resin is applied, multiple layers of vinyl ester are applied to the polyester resin to prevent the polyester resin from shrinking. In the preferred embodiment, the application includes at least three (3) layers of vinyl ester.

Not Applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a hard mold and a method of preparing the mold, which mold is used for manufacturing articles having various patterns defined by unevenness of its surface such as a wood-grain pattern, a marbled pattern and the like. More particularly, the invention relates to a hard mold and a method of preparing the mold, which mold defines various shaping surfaces for forming various surface patterns.

2. Brief Description of Prior Art

It has been conventional practice to incorporate metal molds, polyurethane molds, or silicone molds when manufacturing articles having various shaped patterns defined by unevenness. With these type of molds, it is common practice to etch the uneven shaping surface on the mold. According to such a method, projections on the shaping surface are all of a relatively equal height since the unevenness of the metal mold surface is formed by etching. As a result, recesses of the pattern formed on the manufactured articles are all of the same depth, which fails to provide the articles with a sufficient touch of rich quality and fails to produce articles having a surface finish substantially similar if not identical to the surface of the material imitated.

As will be seen from the subsequent description, improvements are needed in hard mold technology. There is a need for a hard mold that overcomes the deficiencies of the prior art, that can be used for manufacturing articles having various patterns defined, and that produce articles having a realistic surface finish to that of the material imitated.

As will be described, the preferred embodiments of the present invention overcome disadvantages of the prior art.

SUMMARY OF THE INVENTION

In accordance with the present invention, a hard mold used for manufacturing articles having various shapes and patterns defined is provided. The shaping mold generally comprises a master substrate fixably superposed by a coating of hardened material. The inventor has found that a polyurea coating or other polyurethane hybrid is preferred. The layer or coating of hardened material is provided over the entire surface of the master. Once the layer of hardened material has dried, a layer of polyester resin is applied to the layer of hardened material. Prior to applying the layer of polyester resin, the surface of the hardened material is sanded with a 20-40 grit sandpaper. Roughing up the surface area prior to applying the layer of polyester resin causes the layer of hardened material to better adhere to the polyester resin. Once the polyester resin is applied, multiple layers of vinyl ester are applied to the polyester resin to prevent the polyester resin from shrinking. In the preferred embodiment, the application includes at least three (3) layers of vinyl ester.

The resulting hard mold performs with increased precision without breaks or cracks occurring to the shaping surface and provides excellent heat and pressure resistance with no loss of shrink control.

The present invention will be illustrated on the basis of the figures and following description of a preferred embodiment thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In accordance with the present invention, a hard mold10for manufacturing articles having various shapes and patterns defined is disclosed. The hard mold10of the present invention is directed to a shaping mold and method of preparing the mold for manufacturing articles, primarily plastic articles, having various shapes and patterns defined by unevenness of its surface such as a wood-grain pattern, a marbled pattern, and the like. In the broadest context, the hard mold10and method of the present invention consists of components configured and correlated with respect to each other so as to attain the desired objective.

The shaping mold10according to the invention is intended for production of various articles (“article”) having a pattern defined by its shape and/or unevenness of its surface. The shaping mold10generally includes a master substrate fixably superposed by a coating of hardened material104. Characteristics of as suitable hardened material104should include toughness, impact, abrasion, corrosion and thermal shrink resistance. The Inventor has found that a polyurea coating (commercially available by Futura/Devcon Coatings, Inc.) or other polyurethane hybrid is preferred. The hardened material is required to have surface-hardness and an ornamental effect if desired. Thus the layer104of hardened material should withstand mechanical shock and thermal shock due to hot temperatures. And, the layer104should not adhere to the surface102of the master100in order to avoid defects, such as surfaces blemishes. Said another way, it should break away clean.

The layer104or coating of hardened material is provided over the entire surface102of the master100. In the preferred embodiment, the layer of hardened material104should have a thickness of approximately ⅛ to 3/16 inches, although its thickness can be selected according to the pattern to be impressed upon the article. It should be noted however, the present invention and method is suitable for flat and/or smooth surfaces as well.

Once the layer of hardened material104has dried, a layer of polyester resin106is applied to the layer of hardened material104. In the preferred embodiment, the polyester resin106has a thickness of approximately 3/32 inches. Preferably, prior to applying the layer of polyester resin106as described above, the surface of the hardened material is sanded with a 20-40 grit sandpaper. Roughing up the surface area prior to applying the layer of polyester resin106causes the layer of hardened material104to better adhere to the polyester resin.

As is known in the art, characteristics of the polyester resin includes shrinking. As such, multiple layers of vinyl ester (commercially available under the name “Opti PLUS” made by Cook Composites and Polymers Co.) are applied to the polyester resin to prevent the polyester resin from shrinking.

In the preferred embodiment, the application includes at least three (3) layers of vinyl ester. Further, the thickness of each layer of vinyl ester is approximately ⅛ to 3/16 inches per layer.

The method200of preparing the hard mold10of the present invention is described as follows:

As known in the art, the surface102of the master100having the desired form and surface on which the hardened material104is to be placed is thoroughly cleaned201and prepared depending on the master's100material type. Then, the hardened material (such as polyurea) in a fluid state is applied202in film form to the master surface102, thereby to form the layer of hardened material104. Once applied, the uneven surface102of the master100for example, forms the layer of hardened material104having an uneven surface being inverse to the uneven shaping surface to be formed.

Once the layer of hardened material104becomes hard (approximately 20 minutes), the surface of the layer of hardened material104is roughed up 206 using a 20-40 grit sandpaper.

A polyester resin106in a fluid state is then applied208in film form to the layer of hardened material104. Before the polyester resin106begins to shrink, multiple layers108,112,114of vinyl ester is applied to the polyester resin in order to keep the polyester resin from shrinking. In the preferred embodiment, at least three (3) layers of the vinyl ester is applied to the polyester resin106.

The master100is then released from the mold10as known in the art.

The present method permits the shaping surface to be performed with increased precision without breaks or cracks occurring to the shaping surface due to unnecessary external forces applied to the shaping surface when the master is removed from the shaping surface. In addition, the resulting mold provides excellent heat and pressure resistance with no loss of shrink control.

Although the description above contains many specificities, these should not be construed as limiting the scope of the invention, but as merely providing illustrations of some of the presently preferred embodiments of this invention. It would be obvious to those skilled in the art that modifications made may be made to the embodiments described above without departing from the scope of the present invention. Thus, the scope of the invention should be determined by the appended claims and the formal application and their legal equivalents, rather than by the examples given.