Patent Grant
6923639
The present invention relates generally to the field of candle making and in particular to a new and useful holder for a wick which extinguishes the candle flame at the end of the candle useful life.
Candle wicks function by capillary action drawing a fuel from a pool up through the wick to the flame. The fuel used in known candles may be paraffin wax, vegetable-based wax or synthetic polymers, like ester-terminated polyamides (ETPA), such as one sold under the name UNICLEAR, or PENRECO gel sold by Pennzoil. Paraffin waxes typically form a melt pool at between 150-200° F., while UNICLEAR polyamide forms a melt pool at between about 200-250° F. The capillary action can be through a fabric or thread wick or through a capillary tube. When the candle fuel pool becomes very shallow, it can become hot enough to vaporize and it no longer needs a wick to burn. This phenomenon is called “flash” or “flashover” and is a problem especially with candles formed or supported in containers.
Once the upper surface of the wax descends nearly to the floor of the container, the shallow pool of wax can be elevated above its flashpoint temperature, typically between 350-450° F. for conventional paraffin waxes and about 440° F. for UNICLEAR, for example. During flashover, the temperature within the candle can be elevated to at least 1200° F. This excessive heat can cause glass containers to break, and it can cause metal tins to scorch the paint off the tin sides and char surfaces on which they are resting. With freestanding candles the molten wax pool must not extend through the candle floor, because wax can flow out onto the candle supporting surface. If the wax flows out or the container of a contained candle breaks, supporting or surrounding objects can be ignited.
An additional problem is that carbon balls may form during burning and fall into the wax pool at the bottom of the candle, or the user may allow matches or wick trimmings to fall to the bottom. These foreign objects may aggravate the flashover problem by becoming secondary wicks if they are ignited by the candle flame.
In conventional candles formed in containers, a wick support like the sustainer 2 shown in
Sustainers of this type are popular for use in candles because they are easily assembled using machines. The wick is simply inserted through the bore and held in place by crimping the bore. The cylindrical plate of the sustainer 2 is easily affixed to a container for holding a candle.
During burning, molten wax 4 is drawn upwardly through the wick sides initially, and is carried to the flame. As the upper surface of the molten wax 4 descends to near the top end of the sustainer 2, the heat from the flame liquifies the wax all around the sustainer 2. Once this wax is liquified, molten wax 4 can be drawn from beneath the sustainer 2 through the bore and upwardly to the flame. This permits the majority of the wax 4 to be consumed before the flame goes out from lack of fuel. When the depth of the molten wax 4 is sufficiently small, the flashover problem can occur.
Flashover is a problem which causes significant damage and harm. Flashover can result in house fires and burns to people who use candles decoratively. This is a problem which is being given more attention by consumer groups and needs to be solved in an economical way. The need exists for an inexpensive and simple safety device for preventing or significantly decreasing the likelihood of flashover.
Several different approaches to solving the problem of flashover have been provided. U.S. Pat. No. 5,842,850, for example, discloses several embodiments of a wick sustainer of the type shown in
U.S. Pat. No. 4,332,548 teaches a transparent safety disc at the bottom of a candle. The safety disc is formed by a thermoplastic polyamide resin, combined with a flammable solvent for the resin that is compatible with the candle material. The candle is also transparent. A wick holder and wick are placed on a layer of the resin mixture followed by pouring the candle material around the wick and wick holder and over the resin layer. The safety disc layer helps prevent flameups due to its higher melting point and other characteristics which render it substantially non-flammable in the presence of a candle flame.
U.S. Pat. No. 3,797,990 discloses a safety layer for a candle formed from a higher melting point wax. The higher melting point wax in the safety layer is not combustible by a candle flame. The safety layer may be positioned around or below the wick clip and wick bottom. When the candle flame nears the safety layer and causes it to melt, the wax in the safety layer begins to block the wick, subsequently resulting in the candle flame being extinguished due to lack of fuel.
U.S. Pat. No. 2,831,330 teaches adding polybutene polymers to a candle wax in different proportions to first extend the burn time of the candle and then in an amount sufficient to extinguish the candle due to lack of fuel. Polybutene polymer provided in concentrations of about 15% in a portion of a candle is disclosed as being capable of extinguishing a candle when the candle flame reaches the area of higher polybutene concentration.
U.S. Pat. No. 5,127,922 describes a candle having an outer shell which includes 10-30% of a fire retardant material. The fire retardant material is mixed with a thermoplastic compound, so that the shell will slowly melt and mix with the candle fuel as the candle burns. The fire retardant can be a silicone elastomer, a non-halogenated, inorganic flame retardant or an alumina trihydrate, among other compounds.
Other mechanical devices for extinguishing a candle prior to the point where a flashover or flame-up would occur are known, such as taught by U.S. Pat. No. 4,818,214 for a candle having a heat-shrinkable sleeve around the candle near the base. When the candle burns down sufficiently that the candle flame is near the sleeve, the heat activates the sleeve, causing it to shrink inwardly, constricting the wick and extinguishing the flame.
Several of the prior art devices and compounds use flame retardants or flame-resistant materials to extinguish the flame. But, the prior compounds and apparatus for preventing flashover or extinguishing a candle flame can be complex and require particular mixtures of components. Further, some prior art flame-retardant coatings and mixtures for use on wicks or in candle fuels can also make the candle difficult to use by extinguishing the candle prematurely and requiring relighting well before the end of the useable life.
Polyethylene discs with central bores for holding wicks have been suggested for use as the wick holder in a candle to prevent flashover. However, testing has revealed that polyethylene discs soften at 200° F. and can combust rather easily when exposed to a burning candle flame. Thus, polyethylene, while easy to mold, is not suitable for providing a non-combustible wick holder for extinguishing a candle flame at the end of the candle useful life.
Clearly, few simple solutions for preventing flashover which are easy to manufacture and incorporate into a candle are available.
A flame-resistant and retardant wick holder which can be easily incorporated into candles in place of existing wick sustainers is needed. Plastics are a material which can be easily molded and formed, but which can also combust and produce very toxic by-products.
A widely accepted test to determine flammability of plastics used in products is found in Underwriter Laboratories UL-94 standard. ASTM standard 3801-96 and ISO standard 1210-1991 are similar standards having similar tests and equivalent ratings.
The UL-94 standard includes horizontal and vertical burn tests which can be used to rate the flammability of plastics. The vertical burn test is considered more stringent and a plastic can receive one of several ratings, depending on its flammability.
A rating of V-0 from the UL-94 vertical burn test indicates that combustion of the product stops within ten seconds after two applications of ten seconds each of a flame to a test bar of the plastic material, and the material must not produce any flaming drips. The V-0 rating is considered the best rating of non-flammability for a plastic.
The UL-94 vertical burn test is performed by suspending a ½ inch wide by 5 inch long test rod of the plastic material over a cotton pad. A burner flame is applied to the lower end of the test rod for ten seconds, following which combustion of the rod, if any is observed until it stops. The burner flame is applied to the test rod for a second period of ten seconds. Observations of the test rod following application of the flame determine the rating the material will receive. In addition to the requirements noted above, the specimen must not begin glowing or flaming combustion after application of the burner flame. The rating for the material is based on the thickness of the test rod used. That is, a ¼ inch thick test rod which achieves a V-0 rating qualifies the material of the test rod used in products in ¼ or greater thicknesses. The thinner the test rod, the less combustible the material.
Polyethersulfone (PES) is one such material which has a V-0 rating for the UL-94 vertical burn test at a thickness of 0.8 mm, or about 1/32 inches. Polyethersulfone is a thermoplastic material which is commonly used for electrical applications such as wire insulation, connectors, molded interconnects and housings for starters. Polyethersulfone is also known for use in other applications as well where heat resistance is desired. However, while the combustion characteristics of polyethersulfone are known, PES is not known for use in applications involving open flames.
It is an object of the present invention to provide a non-combustible wick holder for a candle to eliminate flashover.
It is a further object of the invention to provide a wick holder which will extinguish a candle flame on a wick when the flame reaches the wick holder.
Yet another object of the invention is to provide a non-flammable wick holder that is easily incorporated into a candle for preventing flashover of the candle when the wick burns down to the wick holder.
Accordingly, a flame-retardant wick holder for a candle wick is provided which effectively extinguishes the candle flame on the wick when the flame and fuel level reach the wick holder. The flame-retardant wick holder is a disc or sleeve made of a polyethersulfone with a bore through the center for holding a candle wick.
In one embodiment, the top surface of the disc may be sloped away from the bore in the center, so that the top surface has a conical shape, or it may be flat. Further, a vertical barrier or ridge may be provided extending upwardly from all around the outer edge of the disc. The barrier has grooves or through-holes for permitting molten wax to drain off the sloped top surface of the disc.
The wick holder may have a diameter or width the same as the container it is used in, or it may be as small as about one inch across. The wick holder may be shaped to accommodate the shape of the container, or it is circular.
In an alternate embodiment, the wick holder is formed as a cylindrical sleeve fitted over a wick clip securing a wick. The upper end of the wick holder sleeve extends past the upper end of the wick clip tube. This embodiment is particularly useful in pillar type candles which are free-standing and do not have a surrounding container.
In each case, the wick holder is sufficiently thick, or shaped to have a maximum height, so that the upper end of the bore is raised above the floor of the container or support where the disc or sleeve is used to prevent candle fuel from melting and rising through the wick in the bore.
The polyethersulfone (PES) used to make the wick holder is selected from those having a UL-94 vertical burn test rating of at least V-0 or which is non-combustible and intumescent when heated. The intumescent property of PES helps restrict the flow of candle fuel through the wick, as the PES swells from the greater heat of the candle flame burning closer to its upper surface. The swelling polymer constricts the wick within the holder bore, thereby cutting off the capillary flow of candle fuel. And, since the wick holder is substantially non-combustible, it will not support combustion once the flame reaches its surfaces. Other polymers which are also non-combustible and intumescent like polyethersulfone can be used to make the wick holder with similar effect.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which a preferred embodiment of the invention is illustrated.
In the drawings:
Referring now to the drawings, in which like reference numerals are used to refer to the same or similar elements,
As seen in
The wick holder 10 preferably rests with the holder bottom 19 supported on container floor 22. In such cases, the candle 50 may be formed by inserting wick 30 through bore 18 and placing wick holder 10 on the floor 22 of the container 20. The wick holder 10 can be secured in place on the container floor 22, such as with a small amount of adhesive or a tacky candle fuel material. Then, liquid candle fuel 100 is poured into the container 20 around the wick holder 10 and wick 30 until the top surface 105 of the candle is at a desired level, and the wick 30 still protrudes from the top surface 105. The candle fuel 100 is allowed to solidify around the wick 30 in the container 20 before it is used by lighting the wick 30.
The wick holder is preferably made of a polyethersulfone, such as RADEL polyethersulfone sold by BP AMOCO. The polyethersulfone selected must have a UL-94 flammability test rating of at least V-0 or better. It has been found that polyethersulfone used for the wick holder 10 material causes a flame on a candle wick 30 to extinguish when the wick 30 and candle fuel 100 reach the horizontal top surface 16 of the wick holder 10. The polyethersulfone does not support sustained combustion, so the candle flame cannot be sustained when the wick 30 is deprived of candle fuel 100 by the presence of the wick holder 10.
The sloped upper surface 12, when present, may be formed at any angle between 0° and 90°. When the upper surface 12 is at 0° or 90° it is either merged into the horizontal top surface 16 or the vertical side of base 14, respectively. Similarly, the horizontal top surface 16 around bore 18 may be eliminated (see FIG. 8A), so that the sloped upper surface 12 provides a conical shape to the top of the wick holder 10. The sloped surface 12 helps drain molten candle fuel 100 away from the wick 30 so that it cannot fuel the candle flame. Preferably, the sloped surface 12 is present and ranges between a 5° and 30° angle with a horizontal plane.
The polyethersulfone wick holder 10 acts as a heat sink as well, to disperse heat from the burning candle flame away from the area immediately around the candle flame to reduce the size of the molten fuel puddle produced when the flame is at or near the level of the wick holder.
The wick holder 10 in
The cylindrical wick holder 10 of
Wick holder 10 preferably has an inner diameter of bore 18 sized to fit snugly around the tube 62 with a frictional fit or slightly looser. Preferably, the inner diameter of the bore 18 and the outer diameter of the tube are the same so as to provide a snug frictional fit. Non-flammable adhesives are preferably used to secure the wick holder 10 and tube 62 together, or less desirably they may be left separable from each other. The outer diameter of the wick holder 10 is preferably about 0.25 inches or greater, and most preferably is sized from 0.25 inches up to the diameter of the wick clip disc portion 160.
Typically, the wick clip tube 62 will be about the same diameter as the wick used. The wick 30 (not shown in
The cylindrical shape of the wick holder 10 in
Although the cylindrical wick holder 10 generally will not protect against secondary wicking, this has been found to be less of a problem with pillar candles. The cylindrical wick holder 10 functions to extinguish the candle flame and cut off the flow of candle fuel 100 on the wick 30 when the flame nears the upper end of wick holder 10. This capability is improved when the wick holder 10 extends above the tube 62.
The cone-shaped holder of
The wick holder 10 should have the same dimensions as discussed above, except that the holder 10 includes the circumferential barrier 80 extending above cylindrical base portion 14. The barrier preferably extends above the base portion 14 by between ⅛ inch to ½ inch. The remaining dimensions of the wick holder 10 may be the same as in other embodiments.
The barrier 80 prevents a wick 30 from falling over into fuel surrounding the holder 10 and creating a secondary wicking effect. The barrier is preferably located at the perimeter edge of the wick holder 10, although it may be positioned closer to the bore 18 when the wick holder 10 diameter is large. It should be understood that the wick holder 10 can be shaped as in any of the prior embodiments and the barrier 80 will be positioned at the same perimeter edge as shown with the circular wick holder 10 of
When a candle has burned down sufficiently that the wick holder 10 is needed to help prevent flashover from occurring, the barrier 80 will support a leaning wick above the surrounding fuel. As shown in
The grooves 85 and drain holes 88 are provided so that as the candle burns down toward the sloped surface 12 of the wick holder 10, the fuel covering the holder 10 can drain off the sloped surface 12. When grooves 85 are used, each groove 85 should have a width less than the width of the wick (and bore 18). The narrower grooves 85 will prevent the wick from being able to fall into one of the grooves 85 and onto fuel surrounding the wick holder 10. The drain holes 88 may be any size, but are preferably narrower or shorter than the diameter of a wick used with the holder 10 to prevent the wick from passing through one of the drain holes 88. The grooves 85 or drain holes 88 should not be smaller than 1/32 inch wide, so that fuel will drain effectively off the sloped surface 12.
The sloped surface 12 can be arranged at any angle from 0-90°, relative to horizontal. When the wick holder 10 includes barrier 80, the sloped surface 12 is preferably angled at between 1-10°, and most preferably about 4° relative to horizontal.
The drain holes 88 or grooves 85 are spaced around the circumference of the barrier 80. Preferably, they are spaced equidistant from each other. They may be used in combination as well, so that a groove 85 is provided at one point of the barrier 80, while a drain hole 88 is provided 180° opposite.
At least one groove 85 or drain hole 88 is needed to ensure that fuel will have a path for flowing off the sloped surface 12. Preferably, there are three grooves 85 or drain holes 88, and most preferably, the three openings are arranged spaced 120° apart around the barrier 80.
In yet another embodiment of the wick holder 10 illustrated by
The wick holder 10 may have cavities 90 in the embodiments of
The embodiment of the wick holder 10 of
The embodiments of the wick holder 10 having a barrier 80 are particularly useful for preventing secondary wicking. Secondary wicking occurs when fuel is drawn up from the wax pool through the free upper end of the wick. If all of the wax pool is drawn up this way then it is possible to increase the wax pool temperature above its flash point and/or in a filled candle to break/shatter the candle holder. To help prevent secondary wicking it is preferable to make the wick holder 10 about 1.5 inches diameter so that it is wide enough to prevent the free end of the wick from touching the wax pool. The barrier 80 provides an elevated support if the upper end of the wick does fall over, and can prevent it from touching the pool.
Polyethersulfone (PES) is a preferred material for making the wick holder 10 for several reasons. PES is a thermoplastic capable of withstanding elevated temperatures. This characteristic allows PES to be easily molded using injection molding techniques. PES is resistant to acids, bases, aliphatic hydrocarbons, oils and fat, among other things, so that it is unlikely to absorb fragrance oils or candle fuels which might make the wick holder 10 somewhat combustible.
Polyethersulfone melts at about 230° C. (about 446° F.). It has a Vicat softening point of about 215° C. (419° F.). A very favorable feature of polyethersulfone is that it is intumescent. That is, when PES is heated, such as by a candle flame, it begins to swell, which in the region of the bore 18, acts to cut off the capillary action in the wick.
Further, PES can appear transparent to yellowish, so that it is usable in transparent candles.
PES is substantially non-combustible, having a UL-94 standard vertical burn test rating of V-0 for thicknesses as small as 1/32 inch. The resistance to combustion of PES combined with heat dissipation properties of a sufficiently large wick holder 10 results in a wick holder according to the invention being capable of extinguishing a candle flame when the flame reaches the level of the wick holder upper surface.
Several tests were conducted with different size wick holders made from PES in accordance with the invention to verify the ability of the wick holders to extinguish a candle flame. The test samples and results were as follows.
Three cylindrical paraffin wax candles and three cylindrical candles made from UNICLEAR each having a PES wick holder ⅜ inches in total height, with a 10° slope to the sloped upper surface 12, 3/32 inch diameter bore 18 and one inch diameter across were provided. The candles were burned 12 hours per day until the candle was at the end of its useful life. The candles were each monitored to determine if they extinguished on their own at the end of the candle useful life. In particular, the candles were monitored to determine if they self-extinguished once the top surface of the PES wick holder 10 was exposed, or alternatively, if secondary wicking occurred, such as from carbon ball buildup or wick pieces in the residual candle fuel. It was observed that all six candles extinguished upon reaching the PES wick holder, despite the presence of carbon balls adjacent the wick. The width of the PES wick holder prevented wick pieces from causing any secondary wicking.
Three cylindrical paraffin wax candles and three cylindrical candles made from UNICLEAR each having a PES wick holder ⅜ inches in total height, with a 10° slope to the sloped upper surface 12, 5/32 inch diameter bore 18 and one inch diameter across were provided. The candles were burned and observed as in Test 1, above. Again, all six candles self-extinguished despite the presence of carbon balls and some small wick pieces which were trapped on the sloped upper surface of the wick holder and prevented from igniting any candle fuel. The PES holder did not experience any combustion.
Three cylindrical paraffin wax candles and three cylindrical candles made from UNICLEAR each having a PES wick holder ⅜ inches in total height, with a 20° slope to the sloped upper surface 12, 3/32 inch diameter bore 18 and one inch diameter across were provided. The candles were burned and observed as in Test 1, above. All six candles self-extinguished.
Three cylindrical paraffin wax candles and three cylindrical candles made from UNICLEAR each having a PES wick holder ⅜ inches in total height, with a 20° slope to the sloped upper surface 12, 5/32 inch diameter bore 18 and one inch diameter across were provided. The candles were burned and observed as in Test 1, above. All six candles self-extinguished.
Three cylindrical paraffin wax candles and nine cylindrical candles made from UNICLEAR each having a PES wick holder ¼ inches in total height, with a 10° slope to the sloped upper surface 12, 5/32 inch diameter bore 18 and one inch diameter across were provided. The candles were burned and observed as in Test 1, above. All but one of the candles self-extinguished despite the presence of carbon balls and wick pieces.
Three cylindrical paraffin wax candles and three cylindrical candles made from UNICLEAR each having a PES wick holder ¼ inches in total height, with a 20° slope to the sloped upper surface 12, 3/32 inch diameter bore 18 and one inch diameter across were provided. The candles were burned and observed as in Test 1, above. All six candles self-extinguished.
Three cylindrical paraffin wax candles and two cylindrical candles made from UNICLEAR each having a PES wick holder ¼ inches in total height, with a 20° slope to the sloped upper surface 12, 5/32 inch diameter bore 18 and one inch diameter across were provided. The candles were burned and observed as in Test 1, above. All five candles self-extinguished.
In each of the tests above, a 44-32-18c wick from Atkins and Pierce was used.
As shown by the tests, a relatively small wick holder 10 incorporated into a candle can provide a self-extinguishing feature. Preferably, the wick holders 10 will be at least 1 inch in diameter, up to the diameter of the container or candle the wick holder is used with. The wick holders can be between 1/32 inch thick to 1 inch or more, but are preferably about 3/32 to ½ inch thick between the bottom surface 19 and horizontal top surface 16 or top opening of the bore 18 when there is no top surface 16. The wick holders 10 should position the top opening of the bore 18 at about ⅛ inch above the bottom of the candle or container bottom 22, and preferably between about ¼ inch and 1 inch above the container bottom 22 or candle bottom.
Other polymers having similar properties to PES can be used for the wick holder 10. In particular, the polymer must not support combustion by a candle flame. Polymers which have at least a V-0 rating for sample thicknesses of 1/32 to ⅛ inch from the UL-94 test are good candidates. Other materials having a UL-94 test rating of V-0 for the same thicknesses may be used as well, including ceramics. Preferably the V-0 rating can be obtained for material thicknesses as low as 1/32 inch, but materials rated V-0 at thicknesses up to ¼ inch are acceptable.
Preferably, the material selected for the wick holder 10 will also be intumescent when heated, so that the same constriction effect in the bore 18 is provided when the candle flame reaches the top surface 16 of the wick holder 10.
Acceptable polymers include polyphenylsulfones (PPS) and polyvinylchloride (PVC) which meet the non-combustion and intumescent requirements, will not melt at temperatures less than about 350° F. and can also be easily injection molded. Specific polymers include RADEL A-300, polysulfone P-1720 (pigmented) and polysulfone P-1700, available from Amoco.
As a further alternative, ceramics which are heat resistant and do not support combustion could be used for the wick holder 10. Although ceramics will not usually have the same intumescent properties as the preferred polymers, the heat resistant and non-combustible nature of ceramics at the temperatures involved with burning candles make them suitable for use.
A further alternative composition for making the wick holder 10 of the invention is one known commercially as FX-100 sold by Flame Seal. The composition is formable into any of the wick holder shapes of
While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.
This application is a continuation-in-part application of U.S. patent application Ser. No. 10/257,201 filed on Oct. 9, 2002, now abandoned, which is the National Phase of International Application PCT/US02/26313 filed Aug. 16, 2002, which claims priority of U.S. patent application Ser. No. 10/131,943 filed Apr. 25, 2002, now U.S. Pat No. 6,773,484, which is a continuation-in-part application of U.S. patent application Ser. No. 09/931,826 filed Aug. 17, 2001, now U.S. Pat. No. 6,508,644, the entirety of each of which is hereby incorporated by reference.
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| Number | Date | Country | |
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| Number | Date | Country | |
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| Parent | 10257201 | US | |
| Child | 10388038 | US |
