GB2389858A

GB2389858A - Porous firelighter with laminate packaging

Info

Publication number: GB2389858A
Application number: GB0313186A
Authority: GB
Inventors: Michael Cox
Original assignee: Swedish Match UK Ltd
Current assignee: Republic Technologies UK Ltd
Priority date: 2002-06-11
Filing date: 2003-06-09
Publication date: 2003-12-24
Anticipated expiration: 2023-06-09
Also published as: GB0313186D0; GB0213293D0; AU2003244778A1; WO2003104362A1; GB2389858B

Abstract

A firelighter comprises a porous core 10 and a combustible wrapper 11 enclosing the core said core is impregnated with a volatile liquid fuel, eg kerosene,biodiesel. The wrapper is laminate, comprising at least two layers, a first polymeric layer 13 and a second non-polymeric layer 12. said polymer layer being on the fuel side of the wrapper. The polymeric layer is preferably comprises a laminate of a first polyethylene layer and a second non-polyolefinic material eg polyamide. The non-polymeric layer may be paper. The porous material is fibreboard or compressed wood chips. The wrapper is sealed to prevent leakage of the fuel. Also disclosed is a firelighter comprising a bio-diesel impregnated porous material, enclosed in a wrapper.

Description

l Firefighters The present invention relates to firflighters, that is

devices that can be ignited easily and are used to light fires, such as barbeques, wood or coal fires.

Firefighters are ideally composed of a material that is easy to ignite and burns for a reasonable length of time so that the burning firflighter ignites the firewood or coal etc of the main fire. Dry kindling such as paper or twigs is often used to light fires, but such material often burns too quickly and at too low 10 a temperature to ignite the fuel, such as logs or coal. Commercially available firflighters usually comprise gelled kerosene or less commonly, paraffin wax blocks. The object of the present invention is to provide a firflighter which is 15 easy to light and burns efficiently so it can be used to effectively light a fire, whilst also being environmentally friendly, by reusing recycled materials. Other advantages shall become apparent as the invention is described.

According to the present invention there is provided a firflighter 20 comprising a porous material and a wrapper enclosing the porous material, said porous material having been impregnated with a volatile liquid fuel, wherein the wrapper is laminate, comprising at least two layers, the layers comprising a first polymeric layer and a second non-polymeric layer.

25 Preferably the polymer layer is on the fuel side (the inside layer) of the wrapper. Preferably the polymeric layer is polyethylene or is laminate, comprising at least two layers. Preferably the polymeric layer comprises a first polyethylene layer and a second layer of nonpolyolefinic material. Preferably the non-polyolefinic material is polyamide. Preferably the polymeric layer 30 comprises a polyethylene layer of thickness greater than 50 microns and less

f than 80 microns and a polyamide layer of thickness greater than 10 microns and less than 20 microns.

Preferably the non-polymeric layer is paper. Preferably the porous S material has a porosity of more than 50 % and less than 80 %. Preferably the thickness of the firflighter (t) is less than half the width (w) and the depth (d) of the firefighter. Preferably the volatile liquid fuel is biodiesel or kerosene.

Preferably the porous material is fibreboard. Preferably the wrapper is sealed to prevent leakage of the fuel.

According to another aspect of the present invention there is provided a firflighter comprising a porous material and a wrapper enclosing the porous material, said porous material having been impregnated with a volatile liquid feel and characterized in that the volatile liquid Mel is biodiesel.

Advantages of the present invention are that the frelighter's paper wrapper is very easy to light and the volatile liquid fuel impregnated within the porous medium burns steadily and for a reasonable length of time. The wrapper ensures that the firflighter is clean to handle. The flat shape of the firflighter 20 allows fast absorption of the volatile liquid fuel into the porous medium.

The firflighter is preferably made from environmentally friendly materials, as the fibreboard or compressed wood chips, biodiesel, paper wrapper and polymer coating may all be derived from waste materials.

A firflighter embodying the invention will now be described by way of example, with reference to the drawings, of which: Figure I is a crosssectional view of the firflighter, showing a cross-section 30 between the two points marked A of figure 3

Figure 2 is a perspective view of the firflighter without the wrapper Figure 3 is perspective view of the firflighter s Figure 4 is a crosssectional view of an alternative embodiment of the firflighter.

Referring to figure 1, the firflighter comprises a core of porous material 10, impregnated with a volatile liquid fuel, and enclosed in a 10 combustible wrapper 11. The core should be made of any combustible, porous, low density material. For example fibreboard (made by compressing fibrous material) or compressed wood chips could be used, the advantages of these materials being that they can be made from waste materials and are therefore inexpensive. In the embodiment shown in figure 1, the core is composed of 15 fibreboard, having a density of around 0.3 g/cm3 and a porosity of 80 %, allowing the fibreboard to absorb 80 % fuel by volume. Fibreboard of density 0.8 g/cm3 or greater and porosity SO % or less would be insufficiently porous. If there is insufficient fuel absorbed, the firflighter will be difficult to ignite and will provide insufficient energy to light the main fire. Increasing the porosity 20 above 80 % does not significantly increase the volume of fuel absorbed by the fibreboard. The fibreboard is impregnated with a volatile liquid fuel by immersing it in the fuel. The fibreboard is left soaking in the fuel until the board has absorbed 25 sufficient fuel or until it is saturated. Referring to figure 2, the fibreboard 10 should have a thickness (t) that is less than half the width (w) and also less than half the depth (d). Due to its flat shape, the fibreboard has a high surface area to volume ratio, which allows it to absorb the volatile fuel faster than if it were cuboid with the thickness, width and depth of the fibreboard roughly equal. The

l firflighter burns fast with large flame height, due to the flat shape of the fibreboard block.

Long strips of 70 mm wide and 7 mm thick fibreboard are immersed in 5 the fuel. After immersion the strips are cut into 70 mm squares, having surface area 11,760 mm2. Alternatively large sheets of fibreboard could be soaked then cut or the fibreboard could be cut into pieces of the desired size before fuel impregnation. The pieces can of course be cut to any size, depending on the desired burning time of the freighter. Before impregnation with fuel, a 70 mm lO square, 7 mm thick piece of fibreboard has a mass of about lO g. After soaking in fuel it has a mass of about 30g. A 70 mm square, 7 mm thick piece of fibreboard, having a porosity of 80 % can absorb roughly up to 27 cm3 of biodiesel. 15 The fuel used to impregnate the core should be of low viscosity, so as to have a fast absorption time. The volatility should not be too high that the firflighter burns too vigorously, causing a hazard. The vapours of very volatile fuels are also difficult to contain. If the fuel has too low a volatility, the firflighter will be difficult to ignite.

In a preferred embodiment, biodiesel is used as the fuel as it has a suitable volatility (it has a flash point of around lOO C). It also has a low viscosity of 4.7 centistokes (at 40 C) therefore it takes only a short time for fibreboard to absorb sufficient fuel. Typically it takes around 30 seconds to saturate 7 mm 25 thick strips of fibreboard with biodiesel.

Biodiesel is a renewable liquid fuel produced from the transesterification of the fatty acids in vegetable oils. It is composed of methyl esters produced from the transesterification of triglycerides with methanol, or it may be 30 composed of ethyl esters from the transesterificatoin of triglycerides with

/ ethanol. Fuel resulting from the transesterification of vegetable oils with lower alcohols other than methanol and ethanol would also be suitable, however such fuels are not currently commercially available. The firflighter fuel can be made from any vegetable oil, for example rape oil or the used cooking oil from fast 5 food restaurants. As it is derived from vegetable sources it is environmentally sustainable and does not contribute to the release of carbon into the atmosphere.

In the case of waste cooking oil, the production of biodiesel recycles an otherwise waste material. Biodiesel has a calorific value just less than that of normal mineral fuels. It is odourless and it produces less smoke during burning 10 than mineral oil. Unlike mineral fuels biodiesel is nontainting therefore can be used in firflighters for cooking fires or barbeques. Biodiesel has been commercially available for a number of years, primarily as methyl esters.

Raw vegetable oils could also be used to impregnate the fibreboard, 15 however they are much more viscous than biodiesel, therefore vegetable oils would take a longer time to absorb into the fireboard. Raw vegetable oils also have a much a higher flash point than biodiesel, so would be more difficult to set alight. 20 The wrapper is a paper-polymer laminate comprising paper 12 coated with a thin polymer layer 13, the polymer layer being on the inside of the wrapper, adjacent to the fibreboard 10. The inner polymer layer is combustible, and impermeable to the biodiesel, therefore it retains the liquid fuel and its vapours. The polymer layer ensures that the firflighter is clean to the touch and 25 does not have a strong odour. A wrapper of paper alone is unsuitable for containing liquid fuels as paper is permeable and would allow liquid fuels to leak through the wrapper and evaporate.

The outer layer is made of paper so that the firflighter is quick and easy to 30 light. The paper also adds an extra layer of protection to prevent the inner s

! polythene layer from being punctured or torn. Kraft paper (a coarse paper made from wood pulp) is used as it has high strength. The Kraft paper is typically 40 - 80 gem, and preferably 60 gem Kraft paper is used. Other combustible material such as cardboard can be used for the outer layer.

The polymer layer of the paper-polymer laminate wrapper must be sufficiently impervious to the liquid fuel in order to prevent leakage and also impervious to the fuel vapour to prevent evaporation of the fuel. The polymer layer of the wrapper comprises a polyethylene layer of thickness 50 - 80 10 microns and a polyamide layer of thickness 10 microns. The paper-

polymer laminate wrapper is around 100 - 150 gem in total. Polyethylene is used in the wrapper as it is flexible and tough and has a low softening point, so the wrapper can be heat sealed to form a leak tight package. However, polyolefin films are not completely impervious to hydrocarbons and 15 hydrocarbon derivatives. Polyamide films have better barrier properties to hydrocarbons than polyolefins, therefore the polymer layer also includes a thin layer of polyamide film to enhance the barrier properties. Alternatively a polyester film could be used in place of the polyamide film as polyesters also have superior barrier properties than polyolefins. Of course, other materials 20 which are tough, combustible and have good barrier properties can be used in the inside layer of the wrapper.

The ratio of the thicknesses of the paper and polymer layers should be chosen to ensure that the wrapper is strong and tear resistant, that it is easy to 25 light and that once set alight, the firefighter burns well. Preferably the wrapper comprises a layer of 60 gem Kraft paper, a polyethylene layer of 60 micron thickness and a polyamide layer of 12 micron thickness.

Thermoplastic polymer films such as polyethylene films are difficult to 30 ignite because the plastic melts away from the source of the heat when ignition is

! attempted. Once the polymer is alight it burns with a small flame since most of the hot material drips away from the flame front. Small flames are more likely to be extinguished by wind or a small draught. The outer paper layer 12 in the paper-polymer laminate wrapper can easily be ignited and the paper provides a 5 wick for the molten polymer to absorb into, preventing the polymer from dripping away from the flame. The polymer is retained at the flame front and therefore gives bigger flames which are less sensitive to draughts.

The polymer-paper laminate can be made by several different processes.

10 In a first process, the polymer is extruded through a slot die as a film and then immediately pressed onto a paper substrate whilst the polymer is still hot and molten, so that the polymer adheres to the paper. The polyethylene layer can be adhered onto the paper first followed by the polyamide film on top of the polyethylene film, or vice versa. In a second process, a preformed cold polymer 15 film is brought into contact with the paper and then heated to bond the polymer and paper together. The polyethylene layer can be bonded to the paper first, followed by the polyamide film or vice versa. Structured laminates comprising two or more polymer films can be formed in this way. Rather than using polymer-coated paper, separate layers of paper and polymer film may be used.

20 The paper and polymer film may be glued together by use of adhesive and additional layers of polymer or paper may be added.

The paper-polymer laminate wrapper has many advantages over a wrapper comprising merely paper or plastic. The wrapper is tougher and less 25 easy to puncture or tear than a single layer wrapper. It can be ignited easily, it burns well and it is impervious to the volatile liquid fuel contained in the firflighter. The impregnated core is wrapped in a rectangular piece of the polymer 30 coated paper, the polymer layer forming the inner layer' adjacent to the

( fibreboard. Referring to figure 3, the wrapper is folded around the impregnated fibreboard, and sealed to forth an envelope around the core, preventing leakage of the fuel. The impregnated fibreboard is placed in the center of a rectangular sheet of the wrapper (polyethylene side next to the fibreboard), having an area of 5 around 110 mm by 170 mm, with the fibreboard edges parallel to the wrapper edges. The opposite, shorter sides of the rectangular sheet are folded over the fibreboard and brought together over the board, leaving around a 10 mm overlap of the polyethylene coated paper. A seal 32 is formed at the overlap either by means of a strip of pressure sensitive adhesive or by heating the area of overlap, 10 thus melting the polyethylene and adhering the paper. Polyethylene has a low softening point and therefore the paper-polymer laminate wrapper can easily be heat sealed. There is an overlap 3 l of around 10 mm at each of the two edges of the firefighter that run perpendicular to the seal 32. The two opposite ends 31 of the firefighter are then sealed in the same way.

Sheets of polymer coated paper of different sizes or shapes can be used to package the impregnated fibreboard, provided there is sufficient overlap of the wrapper to form strong seals, to prevent leakage of the fuel.

20 During use, the firflighter is placed amongst the fuel of the fire to be lit (eg the briquettes of a barbeque). It should be placed reasonably centrally within the pile of fuel so as to ignite as much of the fuel as possible. The firefighter should be left accessible so that it can be lit, for example with a match or lighter, and it should also not be completely enclosed by the fuel so that there a good 25 supply of air to allow it to burn for as long as possible. The wrapper is ignited, which then causes the core to catch alight. The firflighter of this embodiment will burn for around 12 minutes.

Referring to figure 4, in another embodiment, the firflighter comprises a 30 large core made of compressed wood chips 41, saturated in kerosene. The wood

chips are compressed, using a mould, into a cylindrically shaped block of length 150 mm, diameter 50 mm and mass 300 g. The compressed wood chips have a density of around 1.0 g/cm3 and a porosity of around 33 %. Kerosene is more volatile than biodiesel, having a flash point between SO and 150 C, therefore it 5 is very easy to ignite. The block is immersed in kerosene for three minutes, in which time it absorbs around 12-14 % kerosene by volume. A minimum absorption of 10 % kerosene is necessary for the block to ignite and burn efficiently. The firflighter burns for around 40 minutes and can therefore be used to start large fires, which require a longer burning firestarter. The lo impregnated block is wrapped in a paper-polymer laminate wrapper comprising paper 43 coated by a layer of polymer 42, the polymer being adjacent to the wood chip block 41.

Claims

1. A firflighter comprising a porous material and a wrapper enclosing the porous material, said porous material having been impregnated with a 5 volatile liquid fuel, wherein the wrapper is laminate, comprising at least two layers, the layers comprising a first polymeric layer and a second non-polymeric layer.

2. A firflighter according to claim I wherein the polymeric layer is on the 10 fuel side (the inside layer) of the wrapper.

3. A firflighter according to claims 1 or 2 wherein the polymeric layer is polyethylene. 15

4. A firflighter according to claims 1 or 2 wherein the polymeric layer is laminate, comprising at least two layers.

5. A firflighter according to claim 4 wherein the polymeric layer comprises a first polyethylene layer and a second layer of a nonpolyolefinic 20 material.

6. A firflighter according to claim 5 wherein the polymeric layer comprises a first polyethylene layer and a second polyamide layer.

25

7. A firflighter according to claim 6 wherein the polymeric layer comprises a polyethylene layer of thickness greater than 50 microns and less than 80 microns and a polyamide layer of thickness greater than 10 microns and less than 20 microns.

8. A firflighter according to any previous claim wherein the nonpolymeric layer is paper.

9. A firflighter according to any preceding claim wherein the porous 5 material has a porosity of more than 50 % and less than 80 %.

10. A firflighter according to any preceding claim wherein the thickness of the firflighter (t) is less than half the width (w) and the depth (d) of the firflighter.

l l. A firflighter according to any preceding claim wherein the volatile liquid fuel is biodiesel.

12. A firflighter according to claim any of claims l to 10 wherein the volatile 15 liquid fuel is kerosene.

13. A firflighter according to any preceding claim wherein the porous material is fibreboard.

20

14. A firflighter according to any preceding claim wherein the wrapper is sealed to prevent leakage of the fuel.

15. A firflighter comprising a porous material and a wrapper enclosing the porous material, said porous material having been impregnated with a 25 volatile liquid fuel and characterized in that the volatile liquid fuel is biodiesel.