Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
2000-03-08
2003-04-29
Silbaugh, Jan H. (Department: 1732)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S250000, C156S297000, C264S154000, C264S162000, C264S322000, C264S325000
Reexamination Certificate
active
06554944
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to bowl shaped products, and processes, equipment and materials for manufacturing bowl shaped products comprising plastics, preferably mainly acrylic plastics and including alumina trihydrate therein as a filler making up the bulk of the material by weight.
2. Description of the Related Prior Art
Kitchen, bathroom and office countertops fabricated from flat sheet stock of solid surfacing material comprising acrylics filled with alumina trihydrate such as that sold under the trademark of “Corian”, manufactured by E.I. duPont de Nemours & Co., Inc. of Wilmington, Del. 19898 U.S.A., have been in use now for many years. “Corian” is a trademark of E.I. duPont de Nemours & Co., Inc. which refers to their solid surfacing material comprising acrylics filled with alumina trihydrate, alternatively referred to as aluminum trihydrate, the alumina trihydrate comprising 20 to 85 percent by weight of the solid surface material or article. Other companies are now also manufacturing and selling rigid sheet stock solid surfacing material comprising acrylics filled with alumina trihydrate for use as building materials. Solid surfacing material comprising acrylic filled with alumina trihydrate is believed to be manufactured generally in accordance with the processes and mix formulas disclosed in U.S. Pat. No. 3,847,865 issued Nov. 12, 1974 to inventor Ray Duggins and assigned to E.I. duPont de Nemours & Co., Inc. Formulas (mixes), processes and principles thereof provided in U.S. Pat. No. 3,847,865 describe that acrylic resins (polymers) filled with 20 to 85% by weight alumina trihydrate, preferably 55 to 85 percent by weight alumina trihydrate, can be the basis for producing a quality building material having many desirable attributes, and desirable attributes beyond those provided by other similar mixes of substantially other plastics families and fillers other than alumina trihydrate, as described in U.S. Pat. No. 3,847,865. Duggins states that below an approximate 20 percent fill of alumina trihydrate in the plastics provides little benefit from the filler, and above an approximate 85 percent fill of alumina trihydrate and the mix generally cannot be formed into a hardened useful material. Duggins details in the U.S. Pat. No. 3,847,865 that the acrylic plastics are the primary binder and include desirable attributes including translucent qualities, and the alumina trihydrate is preferably applied in the range of 55 to 85% by weight of the article as a important filler for achieving certain qualities, and colorants such as pigments, pigmented particles and the like can be added to the mix to achieve various visual appearances including those including visually distinguishable particles which in many cases simulate stone such as marble or those having a variegated pattern. It is also stated in the Duggins patent that various small quantities from other numerous plastics families can also be added to the acrylic and alumina trihydrate mix and for numerous reasons. Duggins also details how to form such a mix of acrylic binder with alumina trihydrate filler and colorants into material shapes by casting or extrusion to define building material shapes such as flat rigid sheet stock or to cast the fluid mixture into non-flat structures prior to solidification. The solid surfacing material today sold under the name of “Corian” is an acrylic based binder heavily filled with alumina trihydrate, possibly containing some small quantities other plastics, and in most varieties of the mix including various colorants (color providing materials) as described in the Duggins patent. It is believed that “Corian” trademark brand solid surfacing material in rigid sheet form sold today for countertop material is manufactured with an about or approximate 70% by weight fill of alumina trihydrate, i.e. approximately 70% of the product or sheet total weight, in a binder of primarily acrylic plastics and including pigments, organic and/or inorganic, (and possibly dyes in some cases for some colors) dependant upon desired visual affect. Concentrations of the alumina trihydrate between 55 and 85 percent in the plastics provides greater hardness and resistance to flame, as opposed to lower concentrations. 65% to 85% alumina trihydrate by weight is believed most suitable by us for hardness and resistance to flame. Variations of the formula, mainly in the colorants used, provide such solid surfacing material in a wide variety of different appearances in flat sheet stock for use as building materials. Solid surfacing materials of acrylic filled with alumina trihydrate are most often manufactured and sold in flat rigid sheet form, typically in 30 inch wide×12 foot lengths in thicknesses between ¼ through ¾ inches and also in metric sizes, and in many different solid colors, color design patterns, i.e., having veining of different colors or shades of colors therein, and matrix colors or appearances, i.e., clearly distinguishable granular or particle-like color variations, and in some cases appearing as various types of natural stone. Flat sheet stock of such acrylic filled with alumina trihydrate and colorants is believed to be initially cast as a thick fluid or mix, then solidified, and then for most color mixes, sanded and polished (faced) on at least the side of the sheet intended to be exposed in use, although the Duggins U.S. Pat. No. 3,847,865 also describes the material mix as extrudable as a mix prior to solidification. The facing, i.e., sanding or any like process of the cast solidified flat sheet is to mechanically remove a thin outermost surface layer or skin-layer which, generally due to settling of colorants and some upward migration of translucent materials of the mix, does not appear the same as the balance of the sheet acrylic filled with alumina trihydrate and colorants, which as will be discussed, is a problem in economically casting such material in certain colors in three-dimensional or bowl shapes since it is clearly much easier to sand a rigid flat surface compared to the rigid multiple curved surfaces of three-dimensional products. It is believed that certain colors of the acrylic filled with alumina trihydrate material, particularly the solid colors defined with very small and evenly distributed particles and colorants can be cast or extruded without the requirement of any or any significant amount of later sanding to achieve a basically finished surface and appearance, while other color mixes of the material require substantial amounts of sanding after solidification to eliminate the skin surface layer not appearing like the balance of the material. As previously stated, in the prior art, acrylic filled with alumina trihydrate has been cast, initially as a thick fluid into bowl forms for use as sinks and lavatories, some bowls cast with integrally cast countertops to define one-piece sinks/countertop units. However, three-dimensional cast bowls such as lavatories comprising acrylic filled with alumina trihydrate for mounting within a countertop are not economically obtainable in as a wide of a variety of colors and color design patterns and matrix colors as the same material in sheet form. This is believed to be due to increased difficulties in 3-D casting and finishing (sanding and polishing) compared to flat sheet formation, particularly with controlling colorant, pigment and color particle dispersement and final position thereof within the mix when the mix is fluid and pushed into and then held in a three-dimensional shaped casting mold prior to the mix solidifying, such as by catalytic action. There has been limited success, generally restricted to only certain colors, using matched mold casting of acrylic binding a filler of alumina trihydrate by forcing the mix into a bowl shaped casting cavity, then allowing or causing the material to solidify (polymerize or thermoset, such as with injection of a catalyst) prior to removing the bowl from the casting tool. It is believed significant amounts of sanding
Peters Chris R.
Young James E.
Lee Edmund H.
Silbaugh Jan H.
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