US20030124474A1

US20030124474A1 - Self extinguishing candles and method of making same

Info

Publication number: US20030124474A1
Application number: US10/295,056
Authority: US
Inventors: David Elliott; David Morrison; Julie Thompson
Original assignee: Individual
Current assignee: Penreco Partnership
Priority date: 2000-06-07
Filing date: 2002-11-13
Publication date: 2003-07-03
Also published as: BR0205170A; AU2003291468A1; TW200417603A; WO2004044112A1

Abstract

A self-extinguishing candle and method of making the candle are described. The self-extinguishing candle comprises a candle body formed of a candle base material and a flame retardant. The flame retardant is capable of extinguishing the candle flame or, alternatively, of controlling the candle flame.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent application Ser. No. 09/874,669 filed on Jun. 5, 2001 which claims priority to U.S. Provisional patent application, Serial No. 60/210,057, filed Jun. 7, 2000, the disclosures of which are incorporated by reference herein in their entirety.[0001]

FEDERALLY SPONSORED RESEARCH

Not applicable.

REFERENCE TO MICROFICHE APPENDIX

Not applicable.

FIELD OF THE INVENTION

The invention relates to self-extinguishing candles and methods of making candles.

BACKGROUND OF THE INVENTION

Since their earliest use, candles have provided a convenient and generally reliable source of light for mankind. While candles have varied substantially through the years, all generally comprise a solid fuel source (usually wax) within which a fiber wick is embedded. In their basic function, candles provide light once the fiber wick is lit by producing sufficient heat to melt the wax fuel to a liquid form which may be carried within the wick and burned. As the candle flame burns, the heat produced creates a pool of melted wax in the region of the wick. This liquified or melted wax is then carried up to the flame by capillary action within the wick. As the candle burns, and the wax fuel is consumed, the position of the flame moves downwardly upon the wick permitting the candle to produce a substantially continuous light.

As long as the fuel is supplied through the wick via a capillary action to the flame, the flame continually bums down the wick. In many situations, the candle is lit and left alone to bum until the candle is manually extinguished or extinguishes itself. A typical candle will normally extinguish itself upon the disintegration of the wick or the elimination of the fuel supply to the wick.

Many commercially sold wax candles, however, are often placed or formed in a glass or other fragile non-flammable container. Therefore, as the flame disintegrates the wick, the flame approaches the bottom of the glass candle holder, thereby causing the glass holder to experience excessive heating. In certain conditions, the excessive heating results in thermally induced cracking or breakage failures. Specifically, when the heat inside the glass container exceeds the heat stress limits of the glass container, the glass may crack or completely break. If a glass candle holder breaks, flying glass pieces, fire hazards, and bums from picking up hot pieces of glass and wax may result in various levels of injury and/or property damage.

Typical candles will often self-extinguish when approximately 0.25 inches of wax residue is left in the bottom of the glass holder. However, allowing a candle to bum with only 0.25 inches of wax residue between the flame and bottom of the glass is often dangerous in that, as discussed above, the flame still provides excessive heat to the glass surface. To further separate the flame from the glass surface and to provide stability to the wick, the bottom end of the wick is typically inserted into a wick clip. An exemplary wick clip is often constructed of a thin metal or aluminum material which includes a wide base for supporting a hollow cylindrical ferrule, whereby the cylindrical ferrule is typically located in the center of the base. The center of the base often includes an opening allowing fuel access from underneath the base into the hollow ferrule.

Other candles, such as pillar candles, are free-standing, neither poured nor placed into a holder. As the candle bums down, the flame approaches the surface on which the candle is placed and may mar, char or bum the surface. If a free-standing candle is left unattended and is allowed to bum very low, the melted wax could flow out of candle and over the surface. Furthermore, as the flame approaches the bottom of the wick, a free-standing candle poses a safety hazard as the flame could ignite the surface on which the candle sits.

Alternatively, some candles, both free-standing and jar candles, are manufactured to include a wick holder formed from a round base with a cylindrical ferrule emanating from the center of the round base. The cylindrical ferrule is hollow as to allow one end of the wick to be reciprocally received therein. The upper portion of the ferrule is “S” crimped, without piercing the ferrule, to reduce the flow of fuel upward through the ferrule. The base of the wick holder includes a small opening in the center of the base which is concentric with, and the same diameter as, the opening in the cylindrical ferrule. The bottom of the base, on the opposite side of the cylindrical ferrule, is completely sealed off by a hot-melt adhesive, thereby preventing fuel from traveling up the hollow ferrule.

By reducing the flow of fuel within the wick holder, the wick holder restricts the supply of fuel to the candle wick when the flame burns the candle wick down to the top of the wick holder ferrule. By restricting the supply of fuel to the wick, the candle flame, upon burning down to the top of the wick holder, self-extinguishes before allowing the flame to approach the surface of the glass candle holder.

The aforementioned candles are based on restricting the flow of liquid wax to the wick by a mechanical device. Therefore, the ability of the candles to self-extinguish depends upon the performance of the restricting device. If the restricting device fails to function, the candle would not self-extinguish at the desired point. Therefore, there is need for a candle that self-extinguishes at the desired point with improved consistency.

It has also been observed that candles frequently burn with too large a flame and expend the candle too quickly. Although the wick can be manually trimmed to decrease the flame size, this necessitates extinguishing the candle and allowing the wick to cool. Furthermore, trimming the wick does not prevent the rapid consumption of the candle. There is a need, therefore, for a candle in which the rate of fuel consumption, and therefore flame size, is controlled.

SUMMARY OF THE INVENTION

Embodiments of the invention meet the aforementioned need by one or more of the following aspects. In one aspect, a self-extinguishing candle is provided. The self-extinguishing candle includes a candle body formed of a candle base material, and a wick. All or part of the candle body includes at least one flame retardant as an additive.

The flame retardant in accordance with the embodiments of the invention may be a solid insoluble or partially soluble in the candle base material. In some embodiments, the flame retardant may function by flowing into and partially or totally clogging the wick thereby restricting or preventing the flow of the candle base material into and through the wick. As a consequence, the flame may be limited and/or controlled or extinguished.

Alternatively, the flame retardant in accordance with the embodiments of the invention may be a flame-extinguishing or flame-controlling, non-combustible, material which flows into and through the wick. In such embodiments, the flame retardant either limits and/or extinguishes the flame. Such material may be a solid or a liquid. The clogging-form, flame-controlling, and the flame-extinguishing form of flame retardants are collectively referred to herein as a flame retardant.

In one embodiment, the self-extinguishing candle includes a candle body formed from a candle base material and having a bottom portion which further includes at least one flame retardant.

In another aspect, the self-extinguishing candle includes a candle body formed from a candle base material and at least one flame retardant wherein the flame retardant concentration increases from a low concentration at the top of the candle body, where the candle is lit, to a high concentration at the bottom of the candle body.

In another aspect, a method of making a self-extinguishing candle is provided. The method includes: (a) forming a candle body from a candle base material and at least one flame retardant wherein the flame retardant is evenly distributed throughout the candle body.

Additional aspects of the invention as well as objects and advantages provided by embodiments of the invention are apparent with the following description.

DESCRIPTION OF THE DRAWINGS

Not applicable.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Embodiments of the invention provide a self-extinguishing candle which includes a candle body formed of a candle base material. In a first embodiment, the candle body further includes a substantially uniformly distributed flame retardant additive. The flame retardant may be present in amounts from about 0.01% to about 50% by weight; more preferably, from about 0.05% to about 20% by weight; and most preferably, from about 0. 1% to about 10% by weight.

The terms “flame retardant additive” and “flame retardant” as used herein mean any compound, composition or material which extinguishes and/or controls a flame. These terms include solid-clogging, flame extinguishing and flame limiting forms.

In a second embodiment, the distribution of flame retardant is non-uniform, with a greater concentration of the flame retardant in a lower portion of the candle body. Most preferably, there exists a gradient of increasing flame retardant weight percentage over the height of the candle, having from about 0% to about 10% flame retardant at the top of a candle nearest the lightable end of the candle to from about 90% to about 0.01% flame retardant at the bottom of the candle.

In yet another embodiment, the flame retardant concentration is discontinuous, with no flame retardant present toward a lightable end of the candle body and a flame-extinguishing concentration of a flame retardant present toward the bottom of the candle body. The flame retardant may range from about 0.01% to about 90% by weight toward the bottom portion of the candle body.

In some embodiments, the flame retardant is of the type or in sufficient concentration to completely extinguish the flame. In other embodiments, the flame retardant is of the type or in a concentration so as to control the flame such that the flame does not burn excessively or stronger than desired. Particularly useful for controlling the flame are the solid, insoluble clogging forms of flame retardants. Such clogging flame retardants, including but not limited to hydrophobic silica, restrict the flow of the candle base material to and/or through the wick.

Typically, the self-extinguishing candle includes one or more wicks inside or on the outside of the candle, although it is not always necessary to have a wick inside the candle. The wick may extend completely or partially through the candle body. Wickless candles which are self-extinguishing may also be made in accordance with embodiments of the invention.

The candle body of the self-extinguishing candle in accordance with embodiments of the invention includes a candle base material. The term “candle base material” refers to any material that can be used to form a candle. A suitable candle base material preferably is a solid which upon melting, provides a fuel source to a burning wick. A suitable candle base material can be solid, semi-solid, or liquid. Although most candle base material is opaque or substantially opaque, a transparent, substantially transparent or translucent material can also be used to form the candle body. Consequently, the self-extinguishing candles in accordance with embodiments of the invention can be transparent, opaque, or translucent.

A common form of candle base material is wax, which usually refers to a substance that is a plastic to brittle solid at ambient temperature and becomes a low viscosity liquid upon being subjected to elevated temperatures. Suitable waxes for forming the candle body include any known waxes, including but not limited to, paraffin wax, microcrystalline wax, beeswax, insect wax, animal wax, vegetable wax, mineral wax, synthetic wax, polyethylene wax, and mixtures thereof. In addition to wax, semi-solids (such as petrolatum), liquids, synthetic materials, synthetic polymers, mixtures of synthetic materials, mixtures of synthetic polymers and synthetic materials, and mixtures of synthetic polymers with one or more organic compounds may be used as a candle base material or part of a candle base material. Other typically used candle fuel source components, such as hydrocarbon oil, stearic acid, Vybar®, etc., also may be included in the candle base material. The following U.S. patents disclose a suitable candle base material that can be used in embodiments of the invention: U.S. Pat. Nos. 6,063,144; 6,036,925; 4,855,098; 4,449,987; 4,332,548; and U.S. Pat. No. 4,005,978. The disclosures of all of the above U.S. patents are incorporated by reference herein in their entirety. It is noted that a wax can be used alone or with one or more additives or gelling agents to form the candle base material, depending on the type of candles desired.

The self-extinguishing candle can also have a translucent, transparent or substantially transparent candle body. Any translucent, or transparent candle base material may be used in embodiments of the invention. For example, the following U.S. patents disclose a suitable transparent candle composition which may be used in embodiments of the invention: U.S. Pat. No. 5,879,694; 5,843,194; 5,578,089; 5,508,334; 5,132,355; 3,819,342; and U.S. Pat. No. 3,645,705. In addition, U.S. Pat. No. 6,111,055 discloses a transparent polyamide-based gel that can be used to form a transparent candle. As the terms are used herein, polyamides may be considered either a synthetic material or a synthetic polymer. The disclosures of all of the above U.S. patents are incorporated by reference herein in their entirety. In addition, U.S. Pat. No. 5,961,967 discloses a multiphase candle containing locally enriched regions of deliverable active ingredients. Such a candle may also be used in embodiments of the invention. Therefore, the disclosure of this patent is incorporated by reference herein in its entirety.

In some embodiments, the candle body may be formed from a candle base material which is capable of undergoing a phase transition from opaque to transparent or vice versa. PCT Application WO 99/27042 discloses such a candle base material which is suitable for use in embodiments of the invention. The disclosure of this PCT application is incorporated by reference herein in its entirety. Moreover, U.S. Pat. No. 6,471,731, entitled “Polymeric Candle Compositions and Candles Made Therefrom,” filed on Oct. 29, 2002 and U.S. patent application Ser. No. 09/590,863, filed on Jun. 9, 2000 in the name of David Elliott, III, Richard L. Johnson, Wei Song as the inventors, disclose another candle base material which is capable of under going a phase transition from opaque to transparent. The disclosures of these provisional and utility applications are incorporated by reference herein in its entirety.

The flame retardants disclosed in The Chemistry and Uses of Fire Retardants by J. W. Lyons, Wiley-Interscience (1970), can be used in this invention. Thus, the disclosure of this book is incorporated by reference herein in its entirety. It is noted that a suitable flame retardant can be an inorganic compound, an organometallic compound, an organic compound, or a mixture thereof. The flame retardant can be liquid, solid, or semi-solid. Hydrophobic silica, titanium dioxide (TiO₂), talc,, clay, diatomaceous earth, and liquid silicone may be used as a flame retardant. Additional suitable flame retardants include, but are not limited to, lead-containing compounds, arsenic-containing compounds, phosphorus-containing compounds, sulfur-containing compounds, alumina trihydrate, aluminum oxide (Al₂O₃), magnesium hydroxide, magnesium carbonate, calcium carbonate, boric acid, antimony trioxide, tris-1,3-dibromopropyl phosphate, ammonium phosphate, bis(bromochloropropyl) bromochloropropyl phosphate, chlorinated paraffin, polybrominated diphenyloxide, decarbromophenoxybenzene, tetrabromobisphenol A, hexabromocyclododecane, tetrabromophthalic anhydride, or mixtures thereof. Additional suitable flame retardants are disclosed in the following U.S. Pat. Nos. 6,005,033; 5,886,072; 5,766,568; 5,710,202; 5,583,172; 5,578,666; 5,532,302; 5,521,003; 5,418,272; 5,344,855; 5,296,534; 5,027,416; 5,185,103; 5,151,225; 5,130,349; 5,030,674; 5,025,042; 5,011,736; 4,945,018; 4,921,897; 4,900,768; 4,885,318; 4,869,948; 4,808,647; 4,740,537; 4,671,896; 4,520,152; 4,456,654; 4,362,658; 4,350,793; 4,343,854; 4,320,038; 4,235,978; 4,194,068; 4,184,969; 4,154,775; 4,115,351; 4,094,850; 4,078,016; 4,067,930; 3,956,567; 3,953,650; 3,950,456; and U.S. Pat. No. 3,941,908. The disclosures of all of the above U.S. patents are incorporated by reference herein in their entirety. Moreover, suitable flame retardants include a phosphorus/nitrogen-containing oligomer or polymer as disclosed in U.S. Pat. No. 5,409,976, a phosphorus/nitrogen-containing compound as disclosed in U.S. Pat. No. 5,158,999, a halogenated aliphatic bisimide as disclosed in U.S. Pat. No. 4,430,467, and thermally stable cyclic phosphonate esters as disclosed in U.S. Pat. No. 4,842,609, and halogenated imide-containing polyols as disclosed in U.S. Pat. No. 4,401,778. The disclosures of all of the preceding U.S. patents are incorporated by reference herein in their entirety.

In some embodiments of phase-changing candles, paraffin wax with at least 20 carbon atoms per molecule (hereinafter “C ₂₀₊ paraffin wax”) is used. C₂₀₊ paraffin wax refers to a wax composed of mainly paraffins with 20 or more carbon atoms per molecule. In other words, the preferred C₂₀₊ paraffin wax is substantially free of paraffins with less than 20 carbon atoms per molecule. Nevertheless, a small amount of paraffins with less than 20 carbon atoms per molecule may be present in the C₂₀₊ paraffin wax. Preferably, the melting point of the C₂₀₊ paraffin wax should fall in the range of about 100° F. to about 200° F. (i.e., about 37° C. to about 93° C.), more preferably in the range of about 100° F. to about 170° F., and most preferably in the range of about 110° F. to about 165° F.

Paraffin wax is considered as a petroleum wax. It typically is macrocrystalline and brittle. Paraffin wax usually is composed of about 40 to about 90 weight percent of normal alkanes, with the remainder isoalkanes and cycloalkanes. Preferably, the paraffin wax does not include a substantial amount of hydrocarbons with less than 20 carbon atoms per molecule. Typical properties of paraffin wax are listed in Table I as follows. Examples of suitable paraffin waxes can be obtained from Bareco under the trade names of Bareco Paraffin 120/125, Bareco FR 5914, and Bareco FR 5315.

TABLE I


Typical Properties of Paraffin Wax

FLASH POINT, CLOSED CUP. ° C.	204*
VISCOSITY AT 98.9° C., MM²/S	4.2-7.4
MELTING RANGE, ° C.	46-68
REFRACTIVE INDEX AT 98.9° C.	1.430-1.433
NUMBER AVERAGE MOLECULAR WEIGHT	350-420
CARBON ATOMS PER MOLECULE	20-36
DUCTILITY/CRYSTALLINITY OF SOLID WAX	friable to crystalline

In some embodiments, wax alone or a mixture of waxes is used to form the candle body. In other embodiments, a polymer or a polymeric material is used alone or with a wax to form the candle base material. In still other embodiments, a wax is mixed with one or more additives to the form the candle base material. The term “polymer” used herein includes both homopolymer and copolymer. A homopolymer is a polymer obtained by polymerizing one type of monomer, whereas a copolymer is a polymer obtained by polymerizing two or more types of monomers. “Block copolymer” refers to a copolymer in which like monomer units occur in relatively long, alternate sequences on a chain.

Some polymers used in the candle base material often function as gelling agents. Any polymer which is capable of forming a three dimensional network or a gel through physical or chemical crosslinking may be used in embodiments of the invention. Suitable polymers include, but are not limited to, a copolymer with at least two blocks, i.e., a diblock copolymer, a triblock copolymer, a radial block copolymer, a star polymer, a multi-block copolymer, and mixtures thereof. Other embodiments, the polymer includes at least one triblock copolymer, radial block copolymer, star polymer, or multi-block copolymer. The copolymer includes at least one rigid block and one elastomeric (or rubber-like) block. The rigid blocks of the copolymer form rigid domains through which physical crosslinking may occur. The physical crosslinking via these rigid domains yields a continuous three dimensional network. In the presence of heat and shear or solvent, the rigid domains soften and permit flow. After cooling or solvent evaporation, the rigid domains reform and harden, locking the elastomeric network in place. U.S. Pat. No. 5,221,534, U.S. Pat. No. 5,879,694 and U.S. Pat. No. 5,578,089 disclose examples of such block copolymers, and the disclosures of the patents are incorporated by reference in their entirety herein.

A diblock copolymer includes two blocks within its chains: a rigid block and an elastomeric block. The rigid block typically may be composed of polystyrene, polyethylene, polyvinylchloride, phenolics, and the like; the elastomeric block may be composed of ethylene/butadiene copolymers, polyisoprene, polybutadiene, ethylene/propylene copolymers, ethylene-propylene/diene copolymers, and the like. As such, suitable diblock copolymers include, but are not limited to, styrene-ethylene/propylene copolymers, styrene-ethylene/butadiene copolymers, styrene-isoprene copolymers, styrene-butadiene copolymers. In some embodiments, a diblock copolymer is used along with one or more triblock copolymers, star polymers, radial copolymers, and multi-block copolymers.

A triblock copolymer includes two rigid blocks at either end and a middle block which is elastomeric within its chains. This is a preferred triblock copolymer structure, although a triblock copolymer with two elastomeric end blocks and a rigid middle block also can be used. Suitable triblock copolymers include, but are not limited to, styrene-ethylene/propylene-styrene copolymers, styrene-ethylene/butadiene-styrene copolymers, styrene-isoprene-styrene copolymers, and styrene-butadiene-styrene copolymers. Multi-block copolymers are similar to diblock copolymers or triblock copolymers, except that the multiple block copolymers include additional elastomeric blocks and/or rigid blocks.

In addition to the linear chain structure, branched homopolymers or copolymers, such as a radial polymer and a star polymer, also may be used. It should be noted that one or more functional groups may be grafted onto the chain of any of the aforementioned polymers. In other words, any of the above polymers may be modified by grafting. Suitable functional groups for grafting depend on the desired properties. For example, one or more ester groups, silane groups, silicon-containing groups, maleic anhydride groups, acrylamide groups, and acid groups may be grafted. In addition to grafting, the above polymers may be hydrogenated to reduce unsaturation before they are used.

It is noted that additional suitable block copolymers may include, but are not limited to, polystyrene/polyester, polyether/polyamide, polyether/polyester, polyester/polyamide, polyether/polyurethane, polyester/polyurethane, poly(ethylene oxide)/poly(propylene oxide), nylon/rubber, and polysiloxane/polycarbonate.

Generally, the weight average molecular weight of a suitable polymer is in the range from about 10,000 to about 1,000,000, preferably from about 70,000 to about 400,000. The rigid block content may range from about 5% to about 80%, preferably from about 20% to about 40% by weight.

Numerous commercially available block copolymers may be used in embodiments of the invention. For example, various grades of copolymers sold under the trade name of Kraton® from Shell Chemical Company can be used. In addition, copolymers sold under the trade name of Vector® available from Dexco and Septon® from Kuraray also may be used. Calprene and Solprene products listed in Table II are available from Momentum Technologies, Inc. Table II lists some commercially available block copolymers which may be used in embodiments of the invention.

TABLE II


	Block	Polystyrene
Copolymer	Type	Content(%)	Comment

Kraton ® G 1702	SEP	28	Hydrogenated diblock
Kraton ® G 1701	SEP	37	Hydrogenated diblock
Kraton ® G 1780	SEP	7	Star polymer
Kraton ® G 1650	SEBS	30	Hydrogenated triblock
Kraton ® G 1652	SEBS	30	Hydrogenated triblock
Kraton ® D 1101	SBS + SB	31	Triblock and diblock
			mixture (85:15)
Kraton ® D 1102	SBS + SB	28	Triblock + diblock
			(85:15)
Kraton ® D 1133	SBS + SB	35	Triblock + diblock
			(66:34)
Kraton ® FG 1901	SEBS	30	Triblock (hydrogenated
			and functionally grafted
			with 1.7% of maleic
			anhydride.
Septon ® 1001	SEP	35	Hydrogenated diblock
Vector ® 6030	SB	30	Unsaturated diblock
Vector ® 8550	SBS	29	Unsaturated triblock
Vector ® 2518P	SBS	31	Unsaturated triblock
Calprene ® H6120P	SEBS	30	Hydrogenated triblock
Solprene ® 1430	SB	40	Unsaturated diblock

It should be recognized that block copolymers are not the only polymers that can be used in embodiments of the invention. Other types of polymers also may be used. Homopolymers which are capable of effecting strong molecular interaction between polymeric chains can be used. One such example is butyl rubber, which can thicken oil due to its compatibility with oil and high molecular weight. Specifically, a polybutadiene polymer sold under the trademark of Solprene® S200, which is available from Momentum Technologies, Inc., can be used. Other homopolymers capable of forming hydrogen bonding may include polyamide, polyester, etc. Other suitable polymers include ester terminated polyamide (ETPA), amide terminated polyamide (ATPA), other polyamides and polyamide derivatives.

In those embodiments in which a polymer is present in a candle base material, the polymer content may range from about 0.01 wt. % to about 80 wt. %, although other composition ranges are acceptable. In such embodiments, a polymer is present in the candle base material from about 1 wt. % to about 65 wt. %. In embodiments where both a diblock copolymer and a triblock copolymer are used, the triblock copolymer may range from about 0.01 wt. % to about 30 wt. %, and the diblock copolymer from about 0.01 wt. % to about 20 wt. %.

In some embodiments of formulating a candle base material, a wax and a polymer may be present in any amount. In some embodiments, a candle base material may be made from the following components: a paraffin wax or a mixture of waxes with at least 20 carbon atoms per molecule in an amount of about 2 to about 96% by weight, a block copolymer in an amount of about 0.01 to about 35% by weight, and a hydrocarbon oil in an amount of 0 to about 96% by weight. Additional additives and objects may be included during the manufacturing of candles.

Candle base materials and candle bodies in accordance with some embodiments of the invention may be prepared by blending a hydrocarbon oil and a wax with one or more triblock, radial block, and/or multi-block copolymers, star polymers, or mixtures thereof, in desired amounts. A diblock copolymer may also be optionally included. In general, the higher the polymer content, the stiffer the gel. Acceptable compositions including a hydrocarbon oil, a wax and polymers are disclosed in U.S. Pat. No. 6,340,467, and the disclosure of such patent is incorporated by reference in its entirety herein.

In some embodiments, a hydrocarbon oil and a suitable wax are first heated to a temperature in the range of about 50° C. to about 150° C., at which point a polymer is added under agitation to the desired weight percent as set forth herein. After sufficient time for the copolymer to dissolve in the mixture, the composition is poured into a mold or a jar containing a wick. Alternatively, a wick may be added thereafter, and the composition is allowed to cool to a stiff gel.

In some embodiments of the invention, the candle is formed by cooling the candle base material with flame retardant additive in a mold or jar. A mold is used to impart external features, for example, a pillar candle, if desired. Conventional jars, clear, colored or otherwise decorative, such as sculpted, etched, cut glass, etc., may be employed for holding the candle. More preferably, clear glass jars are used for a jar candle.

Candle base materials and candle bodies also may be formed by blending a suitable polymer (or a polymer blend) and a hydrocarbon oil and heating the mixture to a temperature in the range of from about 50° C. to about 150° C. to dissolve the polymer (or the polymer blend) in the oil. A wax is then added under agitation. The wax is mixed with the hydrocarbon oil and the copolymer. Mixing may be carried out in any conventional manner. Upon cooling, a stiff (and sometimes opaque) gel forms.

In addition to a wax and a polymeric material, a hydrocarbon oil may be used in forming a candle base material. It is noted that a hydrocarbon oil may used with or without a polymeric material in formulating a candle base material. Hydrocarbon oil refers to any oil that is primarily composed of one or more compounds with hydrocarbon moieties. Suitable hydrocarbon oils include, but are not limited to, vegetable oil, animal oil, insect oil, mineral oil, esters, or other oil-soluble liquids. It also includes refined, aromatic-free paraffinic and naphthenic oils, solvents, synthetic liquids, hydrogenated or unhydrogenated oligomers of polybutene, polypropylene, polydecene, and polyterpene. Other polyolefins also are suitable.

A preferred mineral oil is white oil which is colorless and transparent and generally is recognized as safe for contact with human skin. Another preferred hydrocarbon oil is poly-α-olefins (“PAOs”). The term “poly-α-olefin” refers to a class of saturated olefin oligomers. A typical poly-α-olefin includes various amounts of dimers, trimers, tetramers, pentamers, hexamers of an α-olefin. A preferred PAO is oligomers of 1-decene, although it may be oligomers of any other α-olefins. Another preferred oil is hydrogenated polyisobutene.

In some embodiments of the invention, the self-extinguishing candle is formed by pressing a particulate candle base material with a flame retardant in a mold. Such pressure molding may occur at ambient or elevated temperatures, with the pressure causing the candle base material particulates to meld into a solid unit.

The self-extinguishing candles in some embodiments employ one or more wicks, typically of porous material which may be either waxed or unwaxed and of the thickness and type appropriate for the particular candle design. Any wick may be used. The wick or wicks may include a decorative feature, for example, striping, coloring, impregnation or coated with material for special effects, such as to provide a colored flame, sparkles, etc., if so desired.

The self-extinguishing candles in accordance with embodiments of the invention also may contain one or more additives such as stabilizers, U.V. inhibitors, antioxidants, colorants, fragrances, flame retardants, and the like to an extent not adversely affecting or decreasing the desired properties of the candle. Stabilizers and other suitable additives include, but are not limited to, performance enhancing additives, materials which improve the candle's burn properties, materials which improve the candle's appearance, and the like to an extent not adversely affecting or decreasing the desired properties of the candle. With respect to antioxidants, specific reference is made to 2,6-di-tert-butyl-4-methylphenol known as “BHT,” which is generally employed at about 0.0 to about 1 weight percent. Other antioxidants also may be used. These additives can be placed in the candle body, the flame resistant block, or both.

Colorants may be added to the candles. The candles may be multicolored or have colored layers. The latter is achieved by forming one colored layer, allowing the layer to cool, and overlaying with a second colored layer, and so on. Other designs can be employed, such as single or multi-color swirls. Such swirls can be achieved by adding the color to the candle base material at a time during cooling of the composition but prior to complete solidification, and gently stirring the composition. Still other design variations are apparent to those skilled in the art.

In addition to colorants, ornamental features may be embedded within the candle body, the flame resistant block, or both. Such features may be either insoluble or soluble in the respective composition of the candle, as desired. Use of such ornamental features allows a possibility not heretofore available in decorative features, as virtually any decorative object can be incorporated within the candle body, provided generally that such decorative feature does not adversely affect the burning capacity of the candle in an undesired way.

Notwithstanding the above, decorative and other functional features that interfere with the burning of the candle may be incorporated, if so desired. For example, in suitable candle designs, decorative features located near the periphery of the candle and not in communication with the wick or flame will not adversely affect the operation of the candle and may thus be of any sort desired. Such a decorative feature may be placed in the candle, for example, by addition to the candle base material after sufficient cooling of the melt but before complete solidification.

Exemplary decorative features include glitter, sparkles, ribbons, air bubbles of various size, and other soluble, partially soluble and insoluble embeds. A pearlizing agent may be used in the candle. Other decorative additives, such as those that cause special effects, e.g., sparkling, flame coloring, etc., or mixtures thereof, also may be added to the candle base material of the candle in effective amounts and as desired. In addition, fluorescent and phosphorescent pigments or dyes may be added to enhance the appearance of the candle. U.S. Pat. No. 6,433,068, entitled “Hydrocarbon Gels as Suspending and Dispersing Agents and Products,” discloses a suspension system which can be used in embodiments of the invention. The disclosure of this patent is incorporated by reference in its entirety herein.

Fragrances, for example, cinnamon, spice, bayberry, pine, essence oils, etc., also may be used in a manner similar to the way wax candles employ pleasing aromatic additives. Any fragrances soluble in or otherwise compatible with the candle composition may be used in making the candles. These fragrances can be employed by inclusion into the heated candle base material. Alternatively, if the fragrance is particularly volatile, it is preferably added to the cooling composition prior to complete solidification. Fragrances are generally employed at up to about 20% by weight of the total candle base material. However, it is recognized by those skilled in the art that fragrant additives can be used up to their characteristic solubility level in the composition of the candle.

The self-extinguishing candles in accordance with embodiments of the invention may further contain a functional additive, such as an insect repellant, for use in the same capacity as conventional candles containing such an additive. The flame retardant may be present in amounts from about 0.01% to about 50% by weight; more preferably from about 0.1% to about 35% by weight; and most preferably from about 0.5% to about 10% by weight. For example, U.S. Pat. No. 5,387,418 discloses one such insect repellant compound that may be employed in the candles. The disclosure of the patent is incorporated by reference herein in its entirety. Citronella oil is another example of an insect repellant that may be used in embodiments of the invention. These additives are used in the conventional amounts as known in the art.

The following examples are presented to illustrate the invention but are not to be considered as limiting the invention. The following include examples of each of the three types of self-extinguishing candles: (1) those in which the flame retardant is evenly distributed throughout the candle; (2) those in which the flame retardant is distributed as a gradient with a higher distribution at the bottom of the candle; and (3) those in which the flame retardant is present only in a lower portion of the candle. The Kraton® polymers used in these examples were obtained from Shell Chemical Company. FR 5914 and FR 5315, referred to in the examples below, are paraffin waxes sold under the Bareco trade name. Micro 195, a microcrystalline wax, was obtained from Bareco, Vybar 103, Vybar 260, and Vybar 343 were obtained from Baker Petrolite. Calprene H 6120P was obtained from Momentum Technologies, Inc.

EXAMPLE 1

A candle base material of 69.9 grams FR 5914, 10 grams FR 5315, 10 grams white petrolatum, and 0.10 grams Kraton G1650. 0.1 grams of Aerosil R 972, a fumed silica composition, was added to the candle base material and mixed. A candle was prepared with an appropriately sized wick. The resulting candle was lit and the flame self-extinguished after 6 minutes and 30 seconds. [0062]

EXAMPLE 2

A candle base material containing 70.5 grams Bareco FR 5315, 4 grams Micro 195, 3 grams Vybar 260, 10 grams Yellow Beeswax, 10 grams Soy Wax, and 1 grams Calprene H 6120P was prepared. 1.5 grams talc was added to the candle base material and permitted to partially settle such that there was a larger concentration of talc at the bottom of the resulting candle than at the top of the candle. The candle was lit and self-extinguished after 30 minutes of burning. [0063]

EXAMPLE 3

A candle base material containing 66.9 grams Bareco FR 5914, 5 grams Bareco FR 5315, 15 grams white petrolatum, 3 grams Micro 195, 3 grams Stearic Acid, 4 grams Yellow Beeswax and 0.1 grams Ajinomoto GP-1, was prepared. 3 grams bentonite clay was added to a candle before hardening of the base material so as to obtain a greater concentration of the clay at the bottom of the candle than at the top of the candle. Ajinomoto GP-1 is a dibutyl lauroyl glutamide compound. The candle was lit and self-extinguished after 8 minutes and 20 seconds. [0064]

EXAMPLE 4

A candle base material containing 56.2 grams Bareco FR 5914, 36.7 grams Bareco FR 5315 1.5 grams white petrolatum, 0.7 grams Stearic Acid, 3.8 grams yellow beeswax, and 0.1 grams Kraton G1701 was prepared. 1 grams of fumed silica was added to the base material. A candle was then prepared using an appropriate wick and the resulting candle had substantially constant concentration of the fumed silica throughout. The candle was lit and it burned with a small flame. The candle self-extinguished after about 2 hours. [0065]

EXAMPLE 5

A candle base material containing 85.0 g Bareco FR 5914, 5.0 g Bareco FR 5315, 3.0 g Bareco Micro 195, 1.0 g Stearic Acid, and 1.0 g Yellow Beeswax was heated to 90° C. with stirring. To this mixture was added 2.0 g Kraton G1650 and 2.0 g Kraton G1702. The blend was stirred until the polymers were dissolved and the mixture was uniform and homogeneous. Aerosil R972 (1.0 g) was added to the candle base material. A candle was prepared from this material, with the Aerosil being uniformly distributed throughout the candle. When the candle was lit, it self-extinguished after 1 minute and 30 seconds. [0066]

EXAMPLE 6

A candle base material containing 87.90 g Bareco FR 5914, 0.10 g Vybar 103, 3.00 g Stearic Acid, 1.00 g Kraton G1654, 1.00 g Kraton GRP 6917, 2.00 g Kraton D1102, and 5.00 g Dow Corning 200 Silicone Fluid (350 cSt) was prepared and made into a candle. The silicone fluid was evenly dispersed throughout the candle. When lit, the candle burned steadily, with a small, controlled flame. [0067]

EXAMPLE 7

A candle base material containing 76.0 g Bareco FR 5315, 5.0 g White Petrolatum, 10.0 g Bareco Micro 195, 8.0 g Kraton G1652, and 1.0 g Stearyl Methicone was prepared. This was made into a candle with the Stearyl Methicone being distributed evenly throughout the candle. When lit, the candle had a steady burn, with a very small flame. [0068]

EXAMPLE 8

A candle base material was prepared from 87.0 g Bareco FR 5914, 10.0 g White Petrolatum, and 2.0 g Bareco Micro 195. To the bottom portion of this candle base material was added enough Aerosil R972 to give a concentration of 1 wt %, while the top portion of the candle contained no Aerosil R972. When this candle was lit, it burned as a normal candle until the flame reached the region of the candle which contained the Aerosil. At this point, the candle self-extinguished and could not be re-lit. [0069]

EXAMPLE 9

A candle base material containing 85.0 g Bareco FR 5914, 3.0 g Bareco Micro 195, 1.0 g Stearic Acid, and 10.0 g Yellow Beeswax was heated until melted. To this was added 1.0 g Aerosil R972. A candle was prepared from this base, which self-extinguished after burning for 2 minutes. [0070]

EXAMPLE 10

A candle base material containing 68.50 g Bareco FR 5914, 19.00 g Bareco FR 5315, 2.00 g White Petrolatum, 3.00 g Stearic Acid, and 5.00 g Yellow Beeswax was heated until melted. To this was added 2.50 g Aerosil R972. A candle was prepared from this base, which self-extinguished after burning for 3 minutes. [0071]

EXAMPLE 11

A candle base material containing 81.20 g Bareco FR 5315, 5.00 g White Petrolatum, 10.00 g Bareco Micro 195, and 3.00 g Kraton G1652 was mixed with heating until homogeneous. To this was added 0.80 g Aluminum Oxide with stirring. This was made into a candle, with uniform dispersion of the aluminum oxide throughout the candle. When lit, the candle burned very slowly to completion, with a very small flame. [0072]

EXAMPLE 12

A candle base material containing 86.70 g Bareco FR 5914, 0.30 g Vybar 103, 3.00 g Stearic Acid, and 5.00 g Kraton G1702 was heated until all the solids had melted or dissolved. To this was added 5.00 g Titanium Dioxide. A candle, with even dispersion of the titanium dioxide, was prepared from this base. The candle was lit, and it self-extinguished after 5 minutes. [0073]

EXAMPLE 13

A candle base material containing 90.0 g Soy Wax, 6.0 g Bareco FR 5315, and 3.0 g Vybar 260, was prepared. To this was added 1.0 g Aerosil R972 with mixing. This base, with evenly-dispersed Aerosil, was made into a candle, which self-extinguished 20 seconds after being lighted. [0074]

EXAMPLE 14

A candle base material containing 85.40 g Bareco FR 5315, 2.50 g Bareco Micro 195, 0.10 g Vybar 260, 6.00 g Yellow Beeswax, and 4.00 g Kraton G1652 was heated with stirring until the mixture was uniform and homogeneous. To this was added 2.00 g Bentonite Clay. A candle, with uniform dispersion of the bentonite clay throughout, was prepared from this base. The candle self-extinguished after burning for 15 minutes. [0075]

EXAMPLE 15

A candle base material containing 51.00 g Bareco FR 5914, 4.00 g Bareco FR 5315, 15.00 g White Petrolatum, 3.00 g Bareco Micro 195, 3.00 g Stearic Acid, 4.00 g Yellow Beeswax, 5.00 g Soy Wax, and 5.00 g Kraton G1650 was heated with stirring until the mixture was smooth and homogeneous. To this was added 10.00 g Talc, with stirring. A candle, with even dispersion of the talc, was prepared from this base. The candle was lit, and it self-extinguished after 1 minute and 10 seconds. [0076]
A demonstrated above, embodiments of the invention provide a self-extinguishing candle which may have one or more of the following advantages. First, because the candle extinguishes automatically after the candle base material is consumed by the candle flame, there is little or no need for a candle extinguishing device, such as a candle snuffer. The self-extinguishing feature of the candle should provide some peace of mind to consumers. Also due to its self-extinguishing feature, fire safety should improve. Finally, due to its design simplicity, it is relatively cost effective to manufacture the self-extinguishing candle. Other advantages are apparent to a person of ordinary skill in the art. [0077]
While the invention has been described with respect to a number of embodiments, modifications and variations exist. For example, instead of creating a single flame resistant portion in a candle, multiple flame resistant regions may be used. The flame resistant region need not be opaque; it can also be transparent or translucent. Colorants may also be added to the flame resistant region to enhance aesthetic appeal. The appended claims intend to cover all such variations and modifications as fall within the scope of the invention.[0078]

Claims

What is claimed is:

1. A candle comprising:

a candle body comprising:

a candle base material;

a flame retardant; and

a wick,

wherein the flame retardant is substantially uniformly distributed throughout the candle body.

2. The candle of claim 1 wherein the flame retardant is selected from the group consisting of hydrophobic silica, liquid silicone, titanium dioxide, clay, diatomaceous earth, and mixtures thereof.

3. The candle of claim 1 wherein the flame retardant is selected from the group consisting of aluminum oxide, alumina trihydrate, magnesium hydroxide, magnesium carbonate, calcium carbonate, boric acid, antimony trioxide, and mixtures thereof.

4. The candle of claim 1 wherein the flame retardant is selected from the group consisting of tris-(1,3-dibromopropyl) phosphate, ammonium phosphate, bis(bromochloropropyl) bromochloropropyl phosphate, chlorinated paraffin, polybrominated diphenyloxide, decarbromophenoxybenzene, tetrabromobisphenol A, hexabromocyclododecane, tetrabromophthalic anhydride, and mixtures thereof.

5. The candle of claim 1 wherein the candle body contains from about 0.01% to 50% by weight flame retardant.

6. The candle of claim 1 wherein the candle body contains from about 0.05% to about 20% by weight flame retardant.

7. The candle of claim 1 wherein the candle body contains from about 0.1% to about 10% by weight flame retardant

8. The candle of claim 1 wherein the candle base material includes a wax.

9. The candle of claim 8 wherein the wax is selected from the group consisting of paraffin wax, microcrystalline wax, beeswax, animal wax, insect wax, vegetable wax, mineral wax, synthetic wax, polyethylene wax, and mixtures thereof.

10. The candle of claim 1 wherein the candle base material includes a wax and a gelling agent.

11. The candle of claim 8 wherein the gelling agent is a di-block copolymer, tri-block copolymer, radial copolymer, star polymer, multi-block copolymer, a polyamide, an ester terminated polyamide, an amide terminated polyamide, polyamide derivatives, polybutadiene, or a mixture thereof.

12. The candle of claim 1 wherein the candle base material includes a hydrocarbon oil.

13. The candle of claim 1 wherein the candle body further comprises one or more soluble, partially soluble or insoluble embeds, or a mixture thereof.

14. The candle of claim 1 wherein the flame retardant is present in at least a flame-extinguishing concentration.

15. The candle of claim 1 wherein the flame retardant is present in a flame-controlling amount.

16. The candle of claim 2 wherein the flame retardant restricts the flow of candle base material through the wick.

17. A candle comprising:

a candle body having a lightable end and bottom end and comprising:

a candle base material;

a flame retardant; and

a wick,

wherein the flame retardant is distributed in the candle body in a gradient with a flame-extinguishing concentration of flame retardant at the bottom end and a lower concentration of flame retardant at the lightable end.

18. The candle of claim 17 wherein the flame retardant is selected from the group consisting of hydrophobic silica, liquid silicone, titanium dioxide, clay, diatomaceous earth, and mixtures thereof.

19. The candle of claim 17 wherein the flame retardant is selected from the group consisting of aluminum oxide, alumina trihydrate, magnesium hydroxide, magnesium carbonate, calcium carbonate, boric acid, antimony trioxide, and mixtures thereof.

20. The candle of claim 17 wherein the flame retardant is selected from the group consisting of tris-(1,3-dibromopropyl) phosphate, ammonium phosphate, bis(bromochloropropyl) bromochloropropyl phosphate, chlorinated paraffin, polybrominated diphenyloxide, decarbromophenoxybenzene, tetrabromobisphenol A, hexabromocyclododecane, tetrabromophthalic anhydride, and mixtures thereof.

21. The candle of claim 17 wherein the candle base material includes a wax.

22. The candle of claim 21 wherein the wax is selected from the group consisting of paraffin wax, microcrystalline wax, beeswax, animal wax, insect wax, vegetable wax, mineral wax, synthetic wax, polyethylene wax, and mixtures thereof.

23. The candle of claim 17 wherein the candle base material includes a wax and a gelling agent.

24. The candle of claim 23 wherein the gelling agent is a di-block copolymer, tri-block copolymer, radial copolymer, star polymer, multi-block copolymer, a polyamide, an ester terminated polyamide, an amide terminated polyamide, polyamide derivatives, polybutadiene, or a mixture thereof.

25. The candle of claim 17 wherein the candle base material includes a hydrocarbon oil.

26. The candle of claim 17 wherein the candle body further comprises one or more soluble, partially soluble or insoluble embeds, or a mixture thereof.

27. A candle comprising:

a candle body having a top lightable portion and a bottom portion wherein the top portion comprises a candle base material and the bottom portion comprises a candle base material and a flame retardant, and

a wick extending from the top lightable portion through at least part of the candle body.

28. The candle of claim 27 wherein the flame retardant is selected from the group consisting of hydrophobic silica, liquid silicone, titanium dioxide, clay, diatomaceous earth, and mixtures thereof.

29. The candle of claim 27 wherein the flame retardant is selected from the group consisting of aluminum oxide, alumina trihydrate, magnesium hydroxide, magnesium carbonate, calcium carbonate, boric acid, antimony trioxide, and mixtures thereof.

30. The candle of claim 27 wherein the flame retardant is selected from the group consisting of tris-(1,3-dibromopropyl) phosphate, ammonium phosphate, bis(bromochloropropyl) bromochloropropyl phosphate, chlorinated paraffin, polybrominated diphenyloxide, decarbromophenoxybenzene, tetrabromobisphenol A, hexabromocyclododecane, tetrabromophthalic anhydride, and mixtures thereof.

31. The candle of claim 27 wherein the bottom portion of the candle body contains from about 0.01% to 50% by weight flame retardant.

32. The candle of claim 27 wherein the bottom portion of the candle body contains from about 0.05% to about 20% by weight flame retardant.

33. The candle of claim 27 wherein the bottom portion of the candle body contains from about 0.1% to about 10% by weight flame retardant

34. The candle of claim 27 wherein the candle base material includes a wax.

35. The candle of claim 34 wherein the wax is selected from the group consisting of paraffin wax, microcrystalline wax, beeswax, animal wax, insect wax, vegetable wax, mineral wax, synthetic wax, polyethylene wax, and mixtures thereof.

36. The candle of claim 27 wherein the candle base material includes a wax and a gelling agent.

37. The candle of claim 36 wherein the gelling agent is a di-block copolymer, tri-block copolymer, radial copolymer, star polymer, multi-block copolymer, a polyamide, an ester terminated polyamide, an amide terminated polyamide, polyamide derivatives, polybutadiene, or a mixture thereof.

38. The candle of claim 27 wherein the candle base material includes a hydrocarbon oil.

39. The candle of claim 27 wherein the candle body further comprises one or more soluble, partially soluble or insoluble embeds, or a mixture thereof.

40. The candle of claim 28 wherein the flame retardant restricts the flow of candle base material through the wick.