Wick composition for air freshener candle product

This invention provides a wick composition which is comprised of a polymeric strand such as polyethylene, which has a content of particulate cellulosic filler ingredient. The cellulosic ingredient contains chemically-bound air-freshener constituent. The wick is adapted for incorporation in a candle body. When the wick is ignited, it combusts with a controlled release of the air freshener constituent into the atmosphere.

BACKGROUND OF THE INVENTION 
This invention generally relates to the dispensing of an air freshener from 
a candle product. More specifically this invention relates to a wick 
composition having a content of air freshener constituent which is 
released under wick combustion conditions. 
Candles have been known and used since early civilization. A typical candle 
is formed of a solid or semi-solid body of wax such as paraffin wax or 
beeswax, and it contains an axially embedded combustible fibrous wick. 
When the wick of a candle is lit, the generated heat melts the solid wax, 
and the resulting liquid flows up the wick by capillary action and is 
combusted. 
More recently candles have been developed that appeal to the olfactory as 
well as the visual sense. This type of candle usually incorporates a 
fragrance oil in the wax body. As the wax is melted in a lighted candle, 
there is a release of the fragrance oil from the liquified wax pool. 
Conventional fragrance candles have drawbacks because of cost and other 
considerations. The incorporation of fragrance oil in candle wax is 
difficult to achieve in a quantity which ensures the release of a suitable 
level of fragrance into the atmosphere during candle burning. Further, the 
incorporated fragrance tends to migrate and volatilize from the wax body 
prematurely. The fragrance also softens the wax body, and there is an 
undesirable loss of rigidity in the candle structure. 
There is continuing interest in the development of improved fragrance and 
other types of air freshener candle products. 
Accordingly, it is an object of this invention to provide an air freshener 
candle product which releases air freshener into the atmosphere only under 
the pyrolysis conditions of the burning candle. 
It is another object of this invention to provide a wick composition which 
has a content of air freshener constituent, and which is adapted for 
incorporation in a candle body. 
It is a further object of this invention to provide a wick composition 
which can be produced by a continuous molding process. 
Other objects and advantages of the present invention shall become apparent 
from the accompanying description and examples. 
Publications of background interest relative to the present invention 
include U.S. Pat. Nos. 2,379,250; 2,829,511; 3,332,428; 3,499,452; 
3,560,122; 3,705,890; 3,898,039; 4,092,988; 4,568,270; 5,538,018; and 
5,569,779; incorporated by reference. 
U.S. Pat. No. 2,829,511 describes a candle wick structure composed of a 
core strand of cellulose acetate in combination with an outer web of 
cotton fibers. 
U.S. Pat. No. 5,538,018 describes a flavorant-release additive which is a 
cellulose derivative that is incorporated into a cigarette paper wrapper. 
DESCRIPTION OF THE INVENTION 
One or more objects of the present invention are accomplished by the 
provision of a wick composition comprising a polymeric strand which 
contains between about 0.5-40 weight percent of particulate air 
freshener-release cellulosic filler ingredient, wherein the air freshener 
is a chemically-bound constituent which is released into the atmosphere 
when the wick is combusted. 
The wick composition typically is an elongated strand having a diameter 
between about 0.2-0.8 centimeters. 
The polymeric matrix of an invention wick composition preferably is 
selected from the class of thermoplastic resins which in general are 
adapted for fiber-formation by processes such as extrusion or compression 
molding. It is preferred that the polymer is composed of elements which do 
not convert into noxious vapors under wick combustion conditions, such as 
carbon, hydrogen and oxygen. 
Equipment and processes for polymer fiber-formation by extrusion are 
described in publications such as U.S. Pat. Nos. 3,065,502; 3,351,695; 
3,577,588; 4,134,714; 4,302,409; and 5,320,798; incorporated by reference. 
A wick polymeric strand can be composed of multiple filaments. 
Suitable fiber-forming polymers include hydrocarbyl polyolefinic 
derivatives such as low and high density polyethylene, low and high 
density polypropylene, polybutene, polystyrene, and the like. 
Other types of suitable polymers include polyvinyl acetate, and acrylate 
resins such as polymethyl acrylate, polymethyl methacrylate, polybutyl 
methacrylate, poly(ethyl acrylate/ethylene), and the like. 
Other preferred types of polymers include cellulosic derivatives such as 
cellulose acetate, methylcellulose, ethylcellulose, and the like. 
Other types of polymers such as thermoset resins can be utilized by 
pressure molding a powder blend of resin and air freshener-release 
cellulosic filler. Other components can be included in a wick composition 
such as stearic acid or particulate polysaccharidic filler which does not 
contain chemically-bound air freshener, such as starch or guar gum. 
The air freshener-release cellulosic filler ingredient of an invention wick 
composition typically is in the form of a powder, or in the form of fine 
fibers which have an average length between about 0.3-3 centimeters. 
The cellulosic substrate of the filler ingredient can be obtained from 
vegetable sources such as cotton, linen, flax, hemp, jute, wood pulp, and 
the like. The cellulosic substrate can be in the form of substituted 
derivatives such as cellulose acetate or methylcellulose, which 
additionally have a content of chemically-bound air freshener constituent. 
The term "cellulosic" as employed herein refers to a .beta.-glucosidic 
polysaccharide corresponding to the formula: 
EQU [C.sub.6 H.sub.7 O.sub.2 (OH).sub.3 ]n 
where n is an integer which provides an average molecular weight between 
about 100,000-2,000,000. 
A present invention candle product can be produced by employing 
conventional candle making methods such as molding, dipping, and the like. 
The combustible body of a candle product typically is a thermoplastic 
blend of organic materials such as beeswax, paraffin wax, montan wax, 
carnauba wax, microcrystalline wax, fatty alcohols, fatty acids, fatty 
esters, natural and synthetic resins, and the like. Candle manufacture is 
described in publications such as "Modern Candle Making", A. Watt 
(Technical Press, London, 1935). 
A wick normally extends longitudinally through a candle body. More than a 
single wick may be utilized in a spaced relationship, but usually a single 
wick component is centrally disposed in a shaped candle body. When a 
candle wick is ignited, the wick is adapted to combust gradually, so that 
both the wick and candle body are consumed. 
When in a candle body, a present invention wick structure after ignition 
has sufficient porosity to absorb melted candlewax into the wick by 
capillary action for combustion during candle usage. The transport of 
melted wax can be enhanced by one or more capillary grooves extending 
axially along the surface of the wick filament. 
A unique aspect of the present invention is the provision of a wick 
composition with an incorporated cellulosic filler ingredient which has a 
content of chemically-bound air freshener constituent. 
The term "chemically-bound" as employed herein refers to a covalent bond 
between a cellulose polymer chain and an air freshener molecule, such as 
an ether or ester linkage. The Degree of Substitution (D.S.) can be 
between about 0.05-3. 
The term "air-freshener" as employed herein is meant to include fragrances 
such as geraniol, insect repellents such as citronellal, and therapeutic 
agents such as menthol. 
An air freshener constituent of a present invention wick composition can be 
any inherently volatile organic compound which is capable of being 
covalently linked to a cellulosic substrate by chemical reaction. 
Suitable volatile air freshener compounds include alcohols such as 
undecanol, 4-isopropylcyclohexanol, geraniol, linalool, citronellol, 
farnesol, menthol, 3-trans-isocamphylcyclohexanol, benzyl alcohol, 
2-phenylethyl alcohol, 3-phenylpropanol, 3-methyl-5-phenylpentanol, 
cinnamic alcohol, isoborneol, thymol, eugenol, isoeugenol, anise alcohol, 
methyl salicylate, and the like. 
Other suitable air freshener compounds include aldehydes and ketones such 
as hexanal, decanal, 2-methyldecanal, trans-2-hexenal, acetoin, diacetyl, 
geranial, citronellal, methoxydihydrocitronellal, menthone, carvone, 
camphor, fenchone, ionone, irone, damascone, cedryl methyl ketone, 
muscone, civetone, 2,4-dimethyl-3-cyclohexene carboxaldehyde, 
2-heptylcyclopentanone, cis-jasmone, dihydrojasmone, cyclopentadecanone, 
benzaldehyde, phenylacetaldehyde, dihydrocinnamaldehyde, cinnamaldehyde, 
.alpha.-amylcinnamaldehyde, acetophenone, benzylacetone, benzophenone, 
piperonal, and the like. 
Other suitable air freshener compounds include esters such as 
trans-2-hexenyl acetate, allyl 3-cyclohexylpropionate, methyl cinnamate, 
benzyl cinnamate, phenylethyl cinnamate, and the like. 
The chemical-bonding of an alcohol air freshener such as geraniol or 
menthol to a cellulose polymer can be accomplished by the formation of a 
carbonate ester linkage: 
##STR1## 
The reaction proceeds readily in the presence of a basic reagent such as 
sodium hydroxide or an organic amine. The production of cellulose 
carbonates are described in publications such as U.S. Pat. No. 3,705,890 
and U.S. Pat. No. 5,068,321; incorporated by reference. 
Another chemical means for forming a linkage between an alcohol air 
freshener and a cellulose polymer is by the use of an alcohol 
epichlorohydrin derivative under alkaline reaction conditions. 
##STR2## 
The chemical-bonding of an aldehyde such as citronellal or a ketone such as 
fenchone to a cellulose polymer can be accomplished by the formation of a 
hemiacetal (ketal) and/or acetal (ketal) linkage under acidic conditions: 
##STR3## 
The chemical bonding of an ester such as phenylethyl cinnamate air 
freshener to a cellulose polymer can be accomplished by a Michael addition 
reaction under alkaline conditions: 
##STR4## 
The Michael addition reaction is described in publications such as U.S. 
Pat. No. 2,415,040 and U.S. Pat. No. 5,569,779; incorporated by reference. 
The chemical-bonding of an air freshener constituent in a present invention 
wick composition provides significant advantages not previously 
contemplated by the prior art. 
The air freshener constituent is released only when the wick composition is 
being combusted. The air freshener is released by pyrolysis at a sustained 
constant rate. 
The amount of air freshener constituent which is chemically-bound in the 
cellulosic substrate can be predetermined within a D.S. range between 
about 0.05-3 by selected synthesis conditions. 
Because the air freshener constituent is chemically bound, there is no 
premature loss of air freshener by migration and evaporation. Also, since 
there is no air freshener such as a fragrance oil dispersed within a 
present invention candle product, the candle body does not soften and lose 
rigidity. 
The present invention also contemplates a further embodiment in which a 
wick composition comprises a polymeric filament which contains between 
about 0.5-40 weight percent of particulate cellulosic filler, and which 
has one or more capillary grooves extending axially along the surface of 
the filament. 
The following examples are further illustrative of the present invention. 
The components and specific ingredients are presented as being typical, 
and various modifications can be derived in view of the foregoing 
disclosure within the scope of the invention.

EXAMPLE I 
This Example illustrates the preparation of geraniol glycidyl ether. 
##STR5## 
Geraniol (100 g) is added dropwise to a stirred mixture of 50% aqueous 
sodium hydroxide (300 mL), epichlorohydrin (300 g), and tetrabutylammonium 
hydrogen sulfate (60 g) with cooling to maintain a temperature of 
20.degree. C. 
After a reaction period of 18 hours, the mixture is poured into water (one 
liter), and the aqueous medium is extracted with chloroform. The extract 
layer is washed with water, dried over sodium sulfate and filtered, and an 
oil product is recovered after solvent evaporation. NMR and IR confirm the 
structure. 
EXAMPLE II 
This Example illustrates the preparation of a polymeric wick composition 
which has a content of air freshener-release cellulosic filler in 
accordance with the present invention. 
A reactor equipped with a reflux condenser and stirrer is charged with 
hexane (one liter), caustic solution (20 g of 50% aqueous sodium 
hydroxide), and cellulose fibers (30 g; 0.5 cm average length). The 
mixture is stirred for 30 minutes at 25.degree. C. under a nitrogen 
atmosphere. 
Geraniol glycidyl ether (50 g) is added to the slurry, and the resulting 
reaction mixture is heated at 75.degree. C. for 10 hours. The mixture then 
is cooled to room temperature, neutralized with glacial acetic acid, and 
filtered. 
The recovered cellulose fibers are washed with acetone and then with water. 
After drying, solid state NMR indicates that the cellulosic matrix has a 
D.S. of 0.35. 
Polyethylene powder (MP 120.degree. C.) is blended with 10 weight percent 
of the above described geraniol-substituted cellulose fibers, and the 
blend is passed through an extruder under heat and pressure to form a 
continuous strand of wick composition having a 0.35 cm diameter. 
A cut section of the strand is ignited, and a flame persists until the wick 
section is completely consumed. The wick combustion releases a flowery 
rose aroma which is characteristic of geraniol. 
A shaped paraffin candle (MP 63.degree. C.) is drilled down the center, and 
a wick section is inserted. When the wick is ignited, a flame persists 
until the entire candle is consumed. A flowery rose aroma is released 
during the candle burning. 
EXAMPLE III 
This Example illustrates the preparation of a polymeric wick composition 
which has a content of fragrance-release cellulosic filler in accordance 
with the present invention. 
Following the general procedure of Example I, glycidyl ethers are formed 
with the ingredients of a perfume oil: 
______________________________________ 
Parts 
______________________________________ 
hydroxycitronellal 
18.0 
cinnamyl alcohol 
1.7 
terpineol 8.0 
benzylalcohol 
18.0 
phenethyl alcohol 
20.0 
linalool 2.0 
______________________________________ 
In a manner similar to that described in Example II, a slurry of cellulose 
powder is treated with the glycidyl ether mixture to chemically-bind the 
fragrance ingredients to the cellulosic matrix (a D.S. of 0.6). 
Polystyrene powder (MP 150.degree. C.) is blended with 20 weight percent of 
the above described fragrance-release cellulosic filler ingredient, and 
the blend is passed through an extruder under heat and pressure to form a 
continuous strand of wick composition having a 0.45 cm diameter. 
A cut section of the strand is ignited, and a flame persists until the wick 
section is completely consumed. The wick releases a flowery lilac note. A 
similar fragrance release is obtained when the wick is burned within a 
candle wax body. 
A similar result is obtained when the polymer ingredient is cellulose 
acetate or polyvinyl acetate. 
EXAMPLE IV 
This Example illustrates the preparation of menthyl chloroformate. 
A reactor in a dry-ice/acetone bath (-75.degree. C.) is charged with liquid 
phosgene (117 g). Menthol (130 g), dissolved in 500 mL of cyclopentane, is 
added dropwise to the phosgene with stirring. The reaction medium is 
refluxed for six hours at room temperature. 
The excess phosgene and cyclopentane are removed under reduced pressure. 
The recovered menthyl chloroformate is dissolved in diethyl ether (300 
mL), and the solution is washed with aqueous sodium bicarbonate, and then 
with distilled water. The liquid medium is dried over sodium sulfate, and 
the solvent is removed under reduced pressure to yield a purified menthyl 
chloroformate. 
EXAMPLE V 
This Example illustrates the preparation of a polymeric wick composition 
which has a content of menthol-release cellulosic filler in accordance 
with the present invention. 
Cellulosic powder (400 g) is suspended in a blend of pyridine (1800 g) and 
benzene (3 liters), and the admixture is stirred for 20 hours at room 
temperature. 
A 1200 g quantity of menthyl chloroformate is added dropwise to the stirred 
reaction medium at room temperature. The stirring is continued for 12 
hours at a reaction medium temperature of 85.degree. C. After cooling and 
filtering, the recovered cellulose powder is washed with benzene, then 
with isopropanol and with water. The wick product has a menthyl carbonate 
D.S. of 0.9. 
Polypropylene powder (MP 110.degree. C.) is blended with 4 weight percent 
of the above described menthol-release cellulosic filler ingredient, and 
the blend is passed through an extruder under heat and pressure to form a 
continuous strand of wick composition having a 0.3 cm diameter. 
A cut section of the strand is consumed completely when ignited. A distinct 
aroma of menthol is detectable in the atmosphere during the wick burning. 
A similar menthol release is obtained when the wick is burned within a 
candle wax body. 
EXAMPLE VI 
This Example illustrates the preparation of a polymeric wick composition 
which has a content of citronellal-release celluosic filler in accordance 
with the present invention. 
A reactor is equipped with a stirrer and a reflux condenser having a 
water-removal unit. The reactor is charged with benzene (500 mL), 
p-toluenesulfonic acid (50 mg), citronellal (50 g) and cellulose powder 
(30 g). 
The admixture is heated at reflux with stirring, and continued until no 
more water is entrained as an azeotrope. After cooling, the acid catalyst 
is neutralized with ammonium hydroxide. The mixture is filtered, and the 
recovered cellulose powder is washed with water. After drying, solid state 
NMR indicates that the cellulosic matrix has a D.S. of about 0.2. 
Polyethylene powder (MP 128.degree. C.) is blended with 28 weight percent 
of the above described citronellal-release cellulosic filler ingredient, 
and the blend is passed through an extruder under heat and pressure to 
form a continuous strand of wick composition having a 0.6 cm diameter. 
A cut section of the strand is consumed completely when ignited. A 
citronellal aroma is released during the wick burning. A similar 
citronellal release is obtained when the wick is burned within a candle 
body.