Synthetic fire logs

Details Synthetic fire logs Synthetic fire logs

1999-11-04

2002-10-01

Medley, Margaret (Department: 1714)

Fuel and related compositions

Fuel product of defined shape or structure

Cylindrical

C044S544000, C044S541000, C044S543000, C044S559000, C044S562000, C044S563000, C044S576000, C044S580000, C044S593000

Reexamination Certificate

active

06458177

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to synthetic fire logs, that is, logs manufactured as substitutes for natural wood logs.
BACKGROUND OF THE INVENTION
Synthetic fire logs are usually composed of a mixture which includes wax and wood waste, a typical mixture ratio being 60% wax to 40% wood waste. This mixture is greasy to the touch, and inclined to crumble when being handled. After the mixture has been extruded in a cylindrical shape and cut into convenient lengths to form the log, it is usually wrapped in a polyethylene lined paper sleeve which is sealed at both ends.
This wrapping stops fragments of the log from dropping off, and makes the log less messy to handle, as the polyethylene does not permit oily elements in the log to soak into the paper. The polyethylene also provides additional fuel value to the log. This paper is also useful as a means of carrying instructions and other information about the log, and as a means of lighting the log. A typical log might weigh 1.25 kg and burn for 2½ hours.
A known type of firelighter is also composed of such a mixture of wood waste and paraffin wax.
Though effective, easy to light and very popular, the paper wrapped logs are not very attractive, whereas a real log fire retains a romantic appeal. Wrapping the logs in the paper requires dedicated equipment, and the paper is also in danger of being torn.
OBJECT OF THE INVENTION
The object of the present invention is to efficiently provide a synthetic log which resembles more closely a natural wooden leg, while retaining the convenience to the user of the paper wrapped logs of the prior art.
SUMMARY OF THE INVENTION
According to the present invention there is provided a mixture including paraffin wax and a thickening agent, the thickening agent being such that above the melting point of the paraffin wax the mixture is pseudoplastic as herein defined. Preferably, paraffin wax makes up 50 to 99% by weight of the mixture. Preferably, the thickening agent makes up 40% by weight of the mixture, and preferably, the thickening agent includes diatomaceous earth.
According to another aspect of the invention, there is provided a synthetic log comprising an inner portion of combustible material including wood waste and a hydrocarbon, surrounded by a coating of a different material, said coating being applied in a state of low viscosity so as to substantially cover the surface of the log, and thereafter setting. Preferably, the material of the coating comprises a pseudoplastic mixture such as described above.
According to a development of the invention, there is provided a synthetic log whose cross section is a quadrant. Preferably, two coatings are applied, one coating resembling bark applied to the curved surface
24
, and the other coating resembling freshly cleaved wood being applied to the rectangular surfaces
22
.
According to another embodiment of the invention, there is provided a synthetic log or firelighter made entirely out of a mixture of paraffin wax and filler material.
The wood waste and wax mixture of prior art logs is a dark brown color. It cannot though conveniently be sold without being wrapped for the reasons outlined above. A material is needed that retains the convenience of the paper wrapped product, that is, is clean, durable, and easy to light, but has a theology which allows it to be easily formed so as to have a texture resembling wood. Ideally then, it should be applicable in the manner of a paint, but quickly set so as to be hard to the touch, and should not drip while burning. It must also have a brown color.
Paraffin wax is readily inflammable, and has a convenient melting point, being molten about 50° C. When molten paraffin wax is mixed with a thickening agent or filler such a diatomaceous earth, the resulting mixture forms a thick, strongly pseudoplastic paste, that is, the mixture has a high viscosity when a low shear force is applied, and a low viscosity when a high shear force is applied.
Such a mixture may be applied in the manner of a paint, but will retain a texture imparted upon it. While the mixture is burning, it retains its pseudoplasticity, and does not drip. The proportion of thickening agent determines the pseudoplasticity of the mixture. The mixture also hardens as the wax solidifies on the cool log.
Such a mixture may be easily applied around a conventional log so as to fulfill the functions of the paper wrapping, that is, to hold the log together and help light it, and also mimic the look and texture of a natural log, which the paper is not able to do.
To substitute for the paper, the mixture must form a coat that is strong and tough enough to protect the log material beneath the coating, and be inflammable enough to be easily set alight. In order to accurately resemble natural wood, the mixture should be easily moldable, but should not drip while burning.


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