CANDLE COMPOSITION

Abstract: The invention relates to gelled hydrocarbon compositions comprising a low molecular weight and a medium molecular weight triblock polymer. These gels can be used to make clear candles.

Description: Candle Composition The invention relates to a clear candle containing a gelled or solidified hydrocarbon oil. Candles of gelled hydrocarbon oils are well known, for example, as described in WO 96/34077 and WO 97/08282. However, these gelled clear candles have the potential to catch fire since the difference between the pool temperature and flashpoint is smaller than in conventional wax candles. If the candle then ignites flames as high as 30 cms can occur with black smoke emanating. This is a potential health hazard and indeed is a reason why there have been a number of product recalls. In addition it is important that the gelled candles do not flow when the candle holder is tipped on its side (e.g. as may occur during transportation or accidental spillage) . Once the wick is buried in the gelled candle material, the product is spoiled. In other words, such a candle material must be firm (i.e. not flow) and have large difference between the pool temperature and the flash point . In the past it has been found that if for example the difference between the pool temperature and flash point is an acceptable amount, then there is too much flow, or vice versa. It has proved to be very difficult if not impossible to obtain an acceptable difference between pool temperature and flash point and at the same time produce a candle having desirable flow. It is also well known in the art to use such gelled hydrocarbon oils for uses other than candles. For example, European Patent No.0224389 discloses styrene- dyene block copolymer compositions. However, none of these compositions would have suitable characteristics for forming candles. International Patent Application No. W097/31623 discloses gelled compositions suitable for a wide range of uses, but not suitable for use in candles. This is particularly because the hydrocarbon used in the compositions disclosed in this international application are volatile and thus would be likely to present a severe fire hazard if used in candles. In addition, the material forming the candle would simply disappear with time, due to evaporation of the hydrocarbon. To alleviate these problems, there is provided a gelled hydrocarbon composition, suitable for use as a candle body, comprising a hydrocarbon oil gelled with a low molecular weight and a medium molecular weight triblock polymer. By low molecular weight triblock polymer is preferably meant a triblock polymer of molecular weight (either Mw or Mn) from 20,000 to 82,000, more preferably 50,000 to 82,000 most preferably Mw is about 78,000 and Mn is about 73,000 expressed as "polystyrene equivalent" molecular weights . An example of such a low molecular weight polymer is Kraton G1652 (RTM) . By medium molecular weight triblock polymer is preferably meant a triblock polymer of molecular weight (either Mw or Mn) of from 82,000 to 150,000, more preferably 85,000 to 120,000, most preferably Mw is about 95,000 and Mn is about 89,600 expressed as "polystyrene equivalent" molecular weights . An example of such a medium molecular weight polymer is Kraton G1650 (RTM) . Preferably the molecular weight is measured by a technique known as "Comparison of the molecular weight distributions of ethylene-butylene-styrene copolymers using "Gel Permeation Chromatography" , the process of which is as follows: The determination of triblock polymers having low and medium molecular weight is expressed as the polystyrene equivalents. The samples are analysed using gel permeation techniques with tetrahydrofuran as the solvents and columns appropriate to low/medium molecular weight polymers . It has been found that through careful selection of the low molecular weight and medium molecular weight triblock polymer, a candle having improved safety results. In other words, through this careful selection, a candle may be formed in which the flash point and the pool temperature have acceptable values, and the difference between the pool temperature and the flash point is also large enough. Further, the resultant candle does not flow when the candle holder is tipped on its side. A single solution of the sample is prepared by adding 10 mis of solvent to 20 mg of the sample and leaving for a minimum of four hours to dissolve. A small amount of l, 2-dichlorobenzene in the solvent is added as an internal marker and the solutions are mixed thoroughly. The solutions are filtered through a 0.2 micron polyamide membrane into sample vials, which are placed in an autosampler. Chromatographic conditions are as follows : Columns PI gel 2X mixed bed D 30 cms, 5 microns Flow rate 1.0 ml/min Temperature 30C Data acquisition and handling is carried out using Viscotek "Trisec 3.0" software. The GPC system was calibrated with polystyrene and the results are expressed as "polystyrene equivalent" molecular weight. The term "triblock polymer" is one well known in the art and suitable triblock polymers are styrene- ethylene/butylene-styrene block copolymers such as are sold under the trade name KRATON G (RTM) by Shell. These copolymers are hydrogenated and are thus thermally stable, that is to say decomposition is not likely to occur during the blending of the copolymer with the hydrocarbon oil. The KRATON G (RTM) copolymers are indicated as being compatible with paraffinic and napthenic oils and are reported as taking up more than 20 times their weight in oil to make a gelled product . Such co-polymers are described in WO 96/34077 and WO 97/08282, the contents of which are incorporated herein by reference. The triblock is often substantially pure triblock and may also include up to 5% diblock copolymer. Alternatively the triblock copolymers may contain blends with radial block copolymer or multiblock copolymer. Such copolymers and blends are described in WO 97/08282 and WO 97131623. Desirable blends of low molecular weight and high molecular weight are in the ratios of 1 to 20 up to 20 to 1. Preferably the blends are in the ratio of 1 to 10 up to 10 to 1, more preferably 1 to 5 up to 5 to 1 Both the low and medium molecular weight are triblock co-polymers of the form a-b-a where b is an oil soluble residue (e.g ethylene or butylene) and a an insoluble styrene residue. An example of this type of polymer is from the Kraton G (RTM) series of thermoplastic rubber polymers. These polymers are a linear block styrene-ethylene- butylene-styrene which have been hydrogenated to impart thermal stability during processing. These tri-block polymers are supplied as >99% pure systems with either low, medium or high molecular weights . These products can then be blended in the laboratory to change the rheological properties of the final hydrocarbon-oil gel as desired. The hydrocarbon oil used is desirably a natural or synthetic hydrocarbon oil of C16 to C50, desirably as disclosed in WO 96/34077 or WO 97/08282. The oil may for example be a paraffinic oil, a naphthenic oil or a natural mineral oil . The hydrocarbon oil can for example be a natural or synthetic cosmetic grade hydrocarbon oil. The hydrocarbon oil desirably is in liquid form at temperatures from 0° to 200° C. Preferred hydrocarbon oils are selected from paraffinic oils naphthenic oils or natural mineral oils, more preferably a white oil. Advantageously, the vapour pressure of the hydrocarbon oil is very low, typically negligible at 20°C. Preferably hydrocarbon oil comprises a carbon chain of 18 to 30 carbons. The resistance to flow of the gelled compositions can be improved further by the addition of a small amount (e.g. 0.01 - 1%) of a fatty acid monomer e.g. a compound of formula I or formula II HO - (CH 2 ) U _ COOH (I) CH 3 -(CH 2 ) P - CH(OH)- (CH 2 ) q - COOH (II) in which u is 8 to 24 p is 0 to 16, preferably 1 to 8, more preferably 3 to 5 and q is 8 to 24, preferably 8 to 16, more preferably 8 to 10. Desirably p and q is from 8 to 24, preferably 12 to 20, more preferably 14 to 18. A preferred fatty acid monomer is a stearic acid containing one or more hydroxy groups . A particularly preferred stearic acid is 12 - hydroxystearic acid. A gelled composition according to the invention will generally have an attractive clear appearance. Further according to the invention, there is provided a candle comprising i) a candle body and ii) a wick located in the body, said body comprising a gelled hydrocarbon composition comprising a hydrocarbon oil, gelled by polymerisation with a low molecular weight and medium molecular weight triblock polymer. Still further according to the invention there is provided a process for preparing a gelled hydrocarbon composition comprising i) mixing (e.g. homogenising) the said hydrocarbon oil with the powdered triblock copolymers at elevated temperature (e.g. 100 - 120° C) and ii) optionally reducing the temperature of the above mixture (e.g. to about 70 - 90° C) adding, whilst mixing (e.g. at 400 - 500 rpm) fragrance to the above mixture . The resulting mixture may then be homogenised at for example 400 - 500 rpm. The candle body desirably comprises the hydrocarbon oil in an amount of 70 to 99 wt%, preferably 85 to 95 wt%, more preferably about 90 wt% . Preferably the triblock polymers are present in an amount of 1-30 wt%, more preferably 5-15 wt%. Preferably the fatty acid monomer if present is present in an amount of 0.1 to 3 wt%, more preferably 0.2 to 2 wt%, most preferably 0.5 to 1 wt%. The candle body may comprise further components preferably 1 to 20% wt, such as one or more compounds selected from fragrances, malodour counteractants, insecticides, pesticides, insect repellants, colourants, anti-oxidants, preservatives, anti-ingestion agents, stabilisers, insect repellents, deodorizers and masking agents . Suitable fragrances preferably 1- l0%wt are generally known in the art, for example one comprising fragrant materials selected from one or more of the following cedarwood oil, sandalwood oil, bergamot, Bulgarian rose oil, patchouli, myrrh, clove leaf oil, linalol, ethyl alcohol, tepineol, menthol, citronellal and phenyl ethyl alcohol . The fragrance normally comprises a carrier solvent such as diethylphthalate, carbitol, dipropyleneglycol , or dipropylglycol . Suitable malodour counteractants are well known, for example is one or more aroma and/or non-aroma chemicals which are known to have an action in reducing the perception of the intensity of malodours for example unsaturated esters, ketoneε, aldehydes, and/or fragrant materials such as citronellal or cedarwood oil (which is known to counteract the perception of tobacco malodour) . Preferably 0.1-10%wt are present. Suitable insecticides, pesticides and insect repellants are well known for use in the invention for example a pyrethroid, niotinoid, rotenoid, tetramethrin, bioallerthrin, allethrin, phenthrin, dinitrophenol, organothiocyamate, benzene hexachloride, citronellal, a polychlorinated cyclic hydrocarbon (for example heptachlor (RTM) , aldrin (RTM) or telodrin) or an organophosphorus compound for example tetraethyl pyrophosphate) . Preferably l-10%wt is present. Any colourant used should be oil soluble. Examples of suitable colourants are Iragon Green (RTM) , Iragon Violet (RTM) , Sandoplast Blue 2B and Fat Red 5B02. Preferably up to 2% wt is present. A suitable anti-oxidant is, for example, tocopherol, ascorbyl palmitate, butylated toluene, ascorbic acid, tert-butyl hydroquinone, beta carotene, butylated hydroxy toluene or a gallate. Preferably 0.1 to 2% of an antioxidant may be present in the composition. Suitable preservatives are quaternary alkyl ammonium compounds or imidazolinium derivatives. Preferably 0.1 to 2% of a preservative may be present in the composition. An example of a suitable anti-ingestion agent is Bitrex (trade mark) which is made by McFarlane Smith Ltd and comprises denatonium benzoate. Preferably up to 2% wt of an anti-ingestion agents may be present in the composition. A gelled composition according to the invention preferably comprises in addition to the hydrocarbon and the triblock copolymer, i) fragrance in an amount of up to 7wt%, preferably up to 5 wt %, ii) colouring agent in an amount of up to 1 wt% and iii) antioxidant in an amount of up to 1 wt % . All of the above percentages are in relation to the total weight of the candle body composition i.e. excluding the wick and container. A candle body may be prepared by mixing the hydrocarbon oil and the medium molecular weight triblock copolymers and low molecular weight triblock copolymers at an elevated temperature e.g. 120 - 100C, a temperature of from 70 to 90° C, more preferably 80°C to 85°C. On cooling further the composition may then be added while the oil/polymer mix is still in liquid form. Preferably the components are mixed together and then poured into a container containing the wick to form the candle body. Alternatively polymerisation of the gelled composition can be conducted in moulds or carried out to form a continuous or semi-continuous body which is then cut into the desired shapes . Preferably the polymerisation takes place when the wick is already present . The invention will be illustrated by the following Examples . Examples 1 to 6. Method of Manufacture of the Candles from Gel The candle consists of a liquid mineral oil that is gelled using a polymeric thickening agent e.g. a Kraton (RTM) co-polymer The candle may also contain fragrance and, if desired, a dye. a) Method of manufacture of the gel The appropriate amount of oil is weighed into a beaker and heated up to 120°C, whilst stirring with Heidolph mixer at 350-450 rpm. When the oil reaches 120°C co-polymeric thickening agent e.g. the Kraton (s) (RTM) is/are gradually added whilst stirring. When all the Kraton (RTM) has dissolved and the mix is reduced to about 85°C and fragrance and 12-hydroxystearic acid - if present is added slowly and left to stir for 10 minutes. Care is needed in adding the fragrance to the mix. b) Method of manufacture of the candle The heater is turned off and a dab of gel mix is used to fix the wick to the base of the glass . The gel is then poured into candle glasses (lOOg fill weight) . The mix compositions are as set out below: Example 1 Results pool temp 75°C some creep Example 2 Results pool temp 80°C some creep Example 3 Results pool temp 70-75°C High creep All amounts are in percentages by weight Example 4 Results pool temp 75°C creep OK All amounts are in percentages by weight Comparative Examples A to C Comparative Example A Results pool temp too high Comparative Example B Results the candle flows out of container quickly Comparative Example C Results High Mol weight co-polymer Too high Melt point to add fragrance

Claims: CL-AIMS : 1. A gelled hydrocarbon composition suitable for use as a candle body, comprising a hydrocarbon oil gelled with a low molecular weight triblock polymer having a Mw or Mn from 20,000 to 82,000 and a medium molecular weight triblock polymer having an Mw or Mn of 82,000 to 150,000. 2. A gelled hydrocarbon composition according to Claim 1 in which the triblock may include up to 5% diblock copolymer or may contain blends with radial block copolymer or multiblock copolymer. 3. A gelled hydrocarbon composition according to any one of the preceding claims in which the triblock polymers are a linear block styrene-ethylene-butylene-styrene which may have been hydrogenated to impart thermal stability during processing. 4. A gelled hydrocarbon composition according to any one of the preceding claims in which the hydrocarbon oil used is a natural or synthetic hydrocarbon oil of C16 to C50, preferably a paraffinic oil, a naphthenic oil or a natural mineral oil . 5. A gelled hydrocarbon composition according to any one of the preceding claims in which there is the addition of a small amount (e.g. 0.01 - 1%) of a fatty acid monomer e.g. a compound of formula I or formula II HO - (CH 2 ) U _ COOH (I) CH 3 -(CH 2 ) P - CH(OH)- (CH 2 ) q - COOH (II) in which u is 8 to 24 p is 0 to 16, preferably 1 to 8, more preferably 3 to 5 and q is 8 to 24, preferably 8 to 16, more preferably 8 to 10. 6. A gelled hydrocarbon composition according to any one of the preceding claims in which the hydrocarbon oil is present in an amount of 70 to 99 wt%, preferably 85 to 95 wt%, more preferably about 90 wt% and the triblock polymers are present in an amount of 1-30 wt%, more preferably 5-15 wt%. 7. A gelled composition according to any one of the preceding claims which comprises in addition to the hydrocarbon and the triblock copolymer, i) fragrance in an amount of up to 7wt%, preferably up to 5 wt %, ii) colouring agent in an amount of up to 1 wt% and iii) antioxidant in an amount of up to 1 wt % . 8. A candle comprising i) a candle body and ii) a wick located in the body, said body comprising a gelled hydrocarbon composition according to any one of the preceding claims . 9. A candle according to Claim 8 in which the candle body comprises the hydrocarbon oil in an amount of 70 to 99 wt%, preferably 85 to 95 wt%, more preferably about 90 wt% and Preferably the triblock polymers are present in an amount of 1-30 wt%, more preferably 5-15 wt%. 10. A candle according to Claim 8 or Claim 9, further including one or more components (preferably in an amount of 1 to 20% wt) , selected from fragrances, malodour counteractants, insecticides, pesticides, insect repellants, colourants, anti-oxidants, preservatives, anti- ingestion agents, stabilisers, insect repellents, deodorizers and masking agents . 11. A process for preparing a gelled hydrocarbon composition according to any one of Claims 1 to 7 comprising iv) mixing (e.g. homogenising) the said hydrocarbon oil with the powdered triblock copolymers at elevated temperature (e.g. 100 - 120° C) and ii) optionally reducing the temperature of the above mixture (e.g. to 70 - 90° C) adding, whilst mixing (e.g. at 400 - 500 rpm) fragrance (and any further additives) to the above mixture . 12. A gelled composition substantially as herein described with reference to any one of Examples 1 to 4. 13. A candle substantially as herein described with reference to any one of Examples 1 to 4.

Inventors: WILSON SONIA KATHERINE, WILSON, SONIA, KATHERINE
Applicants: RECKITT & COLMANN PROD LTD, WILSON SONIA KATHERINE, RECKITT & COLMAN PRODUCTS LIMITED, WILSON, SONIA, KATHERINE
Application year: 2000
Main classification: C11C5
IPC codes: C08L53, C11C5