Combustion – Candle – e.g. – taper – etc.
Reexamination Certificate
2000-02-11
2002-08-27
Clarke, Sara (Department: 3743)
Combustion
Candle, e.g., taper, etc.
C044S275000
Reexamination Certificate
active
06439880
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to constructions and formulations for candles, particularly candles in which the body of the candle is substantially transparent or translucent.
2. The Prior Art
Candles that are used for informal occasions (i.e., candles that are not used for religious ceremonies or similar formal occasions) are often provided in other than the simple waxy “off white” color. Such candles may often be brightly colored and decorated with the various “add on” forms (e.g., wax forms like grape clusters, etc.). Another format, in which candles may be made in a decorative manner beyond their mere utilitarian function, is to make the candle clear.
It is well known that candles can be made in numerous designs and may come in many forms. Although every candle may vary widely in utility, scent, color, texture and even clarity, they most widely fall into two general categories. These categories are listed and defined below (definitions courtesy of NCA, National Candle Association—www.nca.org).
1. Filled Candles—Those candles produced (filled) and used within the same vessel; and
2. Free Standing Candles—Those candles which are rigid and generally free standing which are to be used on a heat resistant, non-flammable surface or on a candle accessory such as a votive holder or candle stick.
When making either kind of the two general candle types above; manufacturers must consider the formulation characteristics of the fuels to be used. Because a certain candle fuel composition will have certain chemical and physical properties associated with it, the fuel may or may not be well suited for one or both of the above-stated categories.
For example, traditional fuels that are too soft, perhaps whether by having a low melt point or low hardness value, cannot be used in a free standing application because typically they lack sufficient rigidity at certain temperatures or there is the presence of obvious oiliness about the fuel. These too “soft” fuel characteristics are common for very highly fragranced waxes, waxes containing oil and the newer gelled oils. Although it is possible to add ingredients or “additives” to these fuels to help reduce softness or oiliness, this typically increases cost. Therefore softer or oilier fuels, often being cost effective, are most well suited for the “filled candle”, i.e., container applications.
Recent developments in gelled oil technology have resulted in candle fuels that are transparent. One form of candle fuel is exemplified by light oil, solidified by rubber-type compounds. One such candle fuel is manufactured and sold by Penreco under the name “Versagel” (formerly known as “Geahlene”). For the purposes of this application, this form of fuel shall be termed “rubberized gel” fuel. Another form of candle fuel is exemplified by an ester-terminated polyamide, blended with a solvent to form a gel. Such a fuel is exemplified in U.S. Pat. Nos. 3,615,289; 3,645,705; 3,819,342; 4,332,548; 4,449,987 and may be referred to generally as “polyamide gel” fuel.
While these fuels have achieved the desirable transparent/translucent characteristic, they have already exhibited limitations in their application to free standing candle types. These limitations are again associated with their inherent physical and/or chemical properties that include lack of rigidity, oiliness, tackiness, or brittleness. These transparent gelled oil candle materials are recognized as being best presented within solid, heat resistant glass or plastic final-use-containers. These same gelled oil candle fuels use polymer type gellants, commonly with caulk, adhesive or rubber formulations which are often very sticky when molten or mixed with oils, rendering themselves as materials not suited for removal from candle molds that are often used to make free standing candles, both due to the removal difficulties, and due to the further propensity of the candles to be easily marred, once the candle has been removed from the mold.
The candle gel known as Versagel (Geahlene) from Penreco is an amorphous blend of block polymer and fuel (hydrocarbon oil) that exhibits a resultant thickened viscosity rendering a nearly solid or semi solid and tacky rigid fuel form at room temperature. Ultimately as the gel is heated by a candle flame, it reaches a temperature range best described as its melting temperature, where dramatic loss in viscosity occurs, allowing the now molten fuel to be wicked up and “fuel” combustion. This viscosity and resultant rigidity of the fuel is also subject to diminish, less dramatically, with increasing exposure to even room temperature conditions over time. This behavior is termed “cold flow” and is exacerbated with the presence of fragrance materials in the formula. Manufacturers address this cold flow problem by using less fragrance additive or by placing a temporary clear plastic lid over the top opening of the candle container, often with an aperture for the wick, to protect the filled candle unit from cold flow should the candle be placed on its side during shipping. This also protects the gel from unsightly fingerprints by restricting consumers curious fingers access to the gel surface. In summary, this gelled oil is subject to having a non-fully self-supporting property and is best suited for insertion into some sort of filled container application. It should be noted that the presence of increasing polymer concentrations can slow the process of cold flow, but such increased polymer concentrations are known to hinder the wicking process of molten fuel, thus producing a smaller, dimmer flame.
Clear polyamide gelled oil fuels are available and also possess high oil concentrations. Being at least partially crystalline in structure, this technology is said to be able to attain rigid gelled oil sufficient for a free standing candle application. However, the literature also suggests that this technology has a history of being prone to fracture, marring, “bleed” or exhibit chemical phase separation in the pool of molten fuel surrounding the wick during burning.
The “bleed” characteristic is more technically known as syneresis, the phenomenon that oil is physically being squeezed out of the candle fuel material because of shrinkage and excessive chemical crosslinking of the polymer in the gelled fuel body. This results in a tactile sensation of being excessively oily with a tendency to accept fingerprints or mar, and subsequently the internal gel matrix becomes increasingly brittle. Polyamide gels in common with candle gel described above are notoriously sticky; containing polymers suited for adhesives and caulking formulations, and is difficult to remove from a candle mold. Because of these properties polyamide gel candle compositions are also widely recognized as being truly suitable for use in a filled candle or solid final use container applications such as glass. Polyamide gels contain comparatively high percentages of gellant to achieve functionality, rendering a cost limitation as well.
The understood behavior of “burning a candle” is easily visualized and most non-technically described as the process upon lighting the wick the candle fuel core becomes molten, fuels the wick and the candle as a whole is “burned down” with time, where the fuel core surface, wick and flame all remain spacially constant to each other, they burn down leaving a deeper vertical distance relative to top edge the original candle and container. This proceeds until the candle is exhausted or extinguished.
In so being most notably suited for use in solid containers such as glass or heat resistant plastic, the production of a freestanding transparent or translucent candle present several challenges. Manufactures can only approximate this desired design by using a clear glass or solid plastic tube that serves to provide the support or protection for the candle fuel. However, glass tubes being expensive, may crack or shatter in the presence of even slight temperature changes relative to the internal and external boundaries of the candle. Heat resi
Clarke Sara
Dick & Harris
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