Fuel and related compositions – Solidified liquid
Reexamination Certificate
2001-01-05
2002-07-16
Medley, Margaret (Department: 1714)
Fuel and related compositions
Solidified liquid
C044S275000, C044S317000, C431S126000, C431S188000
Reexamination Certificate
active
06419713
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an article and method of producing a colored flame, wherein the article comprises a fuel material and a chromogenic agent.
DESCRIPTION
According to a first aspect, the invention relates to a solid or liquid fuel composition capable, while burning, of producing a selected and varied colored flame other than a standard or usual flame color. The present invention also concerns a candle or a lighting device with a colored flame prepared from the fuel composition. According to a third aspect, the present invention relates to a process for the manufacture of a colored flame candle.
The word “candle” is used to designate a functional or decorative lighting device comprising a wick, generally braided, embedded in a meltable fuel material capable, while burning, of producing a flame with a height generally between 2 and 4 cm. Usually, the meltable fuel material is comprised of waxes of various origins. A mixture of paraffin, stearin and, in minor amount, beeswax and mineral wax is typically used as meltable fuel material.
Commercial compositions often comprise major amounts of paraffin and stearin at 80-90 wt. % and 10-20 wt. % respectively. This composition improves the melting properties of the composition, improves compatibility between the various constituents, and avoids smoking during combustion.
During the melting of the meltable fuel material, occurring generally at a temperature between 60-80° C., the liquid mixture rises into the wick by capillary action and catches fire at the wick end. The flame temperature of a conventional candle is about 1000-1,200° C.
Various additives may be added to the meltable fuel material, for example, fluidity control agents to control the molten fuel material fluidity, and aromas or fragrance, such as incense.
For a long time, numerous efforts have been made to obtain a candle capable, while burning, of producing a colored flame other than a standard flame color. For example, it is known that ions of certain elements, including some metalloids having a sufficiently low excitation potential and most metals, radiate in the visible spectrum when they are in a gaseous phase and are in a sufficiently excited state. The combustion of such an element, or chromogenic agent, in a flame produces a characteristic color.
Chromogenic agents conventionally used for the preparation of a candle with a selected colored flame are, for example, derivatives of boric acid, copper or thallium compounds, etc. for a green colored flame, lithium or strontium compounds, etc. for a red colored flame, copper halides for a blue colored flame, sodium compounds for a yellow colored flame, lanthane compounds for an orange colored flame, etc.
U.S. Pat. No. 4,386,904, JP-Kokai-53-30,176, and JP-Kokoku-50-22,828 use a candle with a wick, which has been previously impregnated with a solution of an alkaline or alkaline-earth metal salt, oxide or hydroxide. Attempts have also been made to use a conventional meltable fuel material, such as wax, paraffin, fatty acid, etc., into which is added a chromogenic agent as a dust or powder of a metal, mineral salt, oxide or hydroxide (JP-Kokai-47-14,973), borate or perchlorate compounds dissolved in an ethanolamine derivative (U.S. Pat. No. 1,816,140, U.S. Pat. No. 2,551,574, U.S. Pat. No. 3,150,510 or DE-C-530,147) or, more recently, as a fatty acid salt.
Candles having a coating containing these various chromogenic agents were also disclosed. When the candle bums, the coating melts and releases theses chromogenic agents into the molten mixture in which the wick is imbedded.
None of these solutions is actually satisfactory because inhomogeneous distributions of these compositions do not allow a candle to produce a flame having a stable color. As indicated above, the temperature of a conventional candle flame is of about 1000-1200° C.; however, the inventors have observed that this temperature range is largely insufficient to excite conventional chromogenic agents. On the other hand, with a “hot” flame having a temperature higher than or of about 1,700° C., it was observed that these chromogenic agents could provide a colored flame fully satisfactory as to the obtained color.
Stemming from this principle, prior art discloses introducing a fuel component into the fuel composition that is able to increase the flame temperature. For example, French utility model application 2,675,813 teaches the use of hexamethylenetetramine to this end. It is also possible to find in the literature mention of the use of methaldehyde or hydrazine for the same purpose. Practically, these solutions are not satisfactory.
An acceptable candle must comprise a mixture that melts in a controlled way under the effect of heat. In other words, a crater of molten material must form at the candle surface at the level of the wick and its diameter must remain constant when the candle bums. If the crater diameter shrinks, the candle will eventually go out. If the crater diameter increases, the whole candle softens in a totally non-aesthetic manner. The crater diameter and consequently the quantity of molten material is controlled by the flame temperature, which itself depends on the composition of the mixture constituting the candle. Further, the molten mixture must rise into the wick by capillary action and catch fire at the wick end. For the flame of a burning candle to be stable, the speed of the molten material rising into the wick must balance the combustion rate of the same material in the flame. When the speed of the molten material rising into the wick is lower than the combustion rate, the flame rapidly runs out of fuel and eventually the wick itself burns. Consequently, the wick length shortens and the candle goes out. In the opposite situation, the fuel material arrives at the flame level in an amount such that the flame grows and comes down to the molten material crater level. The molten material eventually catches fire and the entire candle ignites.
Further, the molten material crater must contain a homogeneous mixture of the fuel composition, comprising, beside the conventional candle constituents, the chromogenic agent and the compound which, when burning, increases the flame temperature. The temperature of the molten material in the crater should ideally remain stable and be sufficient to ensure the fluidity of the molten material mixture so that it can rise into the wick by capillary action. On the other hand, at this temperature, the mixture must not be able to catch fire spontaneously; otherwise, the molten material crater could catch fire directly and ignite the entire candle.
According to the present invention, it is proposed to prepare a fuel composition capable, while burning, of producing a selected colored flame, by using a fuel composition comprising a chromogenic agent and triethanolamine. Conventional fuel constituents may comprise up to 50 wt. % of the fuel composition. Within the scope of the present invention, the chromogenic agent can be a mixture of several chromogenic agents.
The inventors note that triethanolamine can be used advantageously as a fuel component and is capable of increasing the flame temperature well above 1,700° C., which is a temperature sufficient to excite conventional chromogenic agents.
Further, and extremely advantageously, triethanolamine can entirely replace conventional waxes used as meltable fuel material, that is, unlike other above-mentioned fuel components capable of increasing the flame temperature, triethanolamine and a chromogenic agent can by themselves provide the fuel for the candle. Other conventional constituents, such as waxes, paraffin, etc., of the candle, if any, are present in a minor amount not greater than 50 wt. % and preferably below 20 wt. % of the composition. The very low cost of triethanolamine in comparison with conventional candle constituents, is not a negligible advantage.
Additionally, the inventors note that boric acid and its derivatives, the majority of the copper, thallium, tellurium, strontium, calcium, lanthane, sodium, etc. c
Durand Gerard
Legrand Bruno
Mokili Bandombélé
Rives Jean-Pierre
Medley Margaret
Regal Universal Ltd.
Williams James R.
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