EP1873230A1

EP1873230A1 - Candle and candle production process.

Info

Publication number: EP1873230A1
Application number: EP06116335A
Authority: EP
Inventors: Bert Wagenaar; Johan Pauwels; Francis Emmers
Original assignee: SPAAS KAARSEN
Current assignee: SPAAS KAARSEN
Priority date: 2006-06-29
Filing date: 2006-06-29
Publication date: 2008-01-02

Abstract

The candle comprises a candle fuel which contains at least a mixture of free organic acids, in particular a mixture of free fatty acids. This that said free organic acid mixture contains at least 5, preferably at least 10 and more preferably at least 20 weight percent unsaturated organic acids or has a iodine number of at least 5, preferably of at least 10 and more preferably of at least 20. In this way the melting point of the candle fuel can be lowered sufficiently without having to use more expensive fuel materials like paraffin or partially hardened oils. The presence of the unsaturated free fatty acids also enabled to obviate processing problems, observed for completely hardened free fatty acids, when producing a candle fuel granulate by spraying the candle fuel, in partially crystallized state, onto a cooling drum.

Description

The present invention relates to a candle containing a candle fuel which contains at least a mixture of free organic acids, in particular a mixture of free fatty acids.
The candle industry frequently converts liquid fuels into granulates by means of powder production technologies. This granulate can subsequently be pressed or used in an extruder to obtain the final candle shape with an inserted wick. Paraffin was the fuel of choice in the past together with a small amount of additives like completely hardened fatty acid (stearine) and vybar. Due to a price increase of the petroleum products like paraffin, candles which are produced from paraffin blends are becoming expensive and the demand for a cheaper versatile candle raw material is urgent.
Candle fuels consisting of saturated (i.e. hardened) organic acids like stearic acid, palmitic acids or mixtures thereof provide a cost effective alternative. However these saturated acids have a high melting point and are brittle, stiff and hard. The state of the art candle extruders or candle powder presses cannot process these saturated organic acids.
A further drawback is that, due to the high melting point of the saturated fatty acid mixture, a large wick or flame is needed so that the candle has a reduced burning time. When a 9-day burner container contains a mixture of crystallized palmitic and stearic acid, the resulting melting point of 55 - 60 degrees Celsius is too high. A large flame is necessary to obtain the liquid melting pool in this case combined with a large fuel consumption. As a result the fuel is consumed rapidly and the 9-day burner burning period is too short.
A state of the art solution is to use partially hardened soybean oil (containing triglycerides) with a melting point of 37 degrees Celsius and a fuel consumption of 2.3 gram per hour. Such a partially hardened oil has however the same drawback as paraffin, namely its relatively high cost price.
An object of the present invention is to provide a new candle which comprises an alternative candle fuel which is cheaper to produce than the partially hardened soybean oil and which is easier to granulate and to process than the completely hardened fatty acid mixtures which are now used for producing candles.
To this end, the candle according to the present invention is characterised in that the free organic acid mixture contains at least 5, preferably at least 10 and more preferably at least 20 weight percent unsaturated organic acids or has a iodine number of at least 5, preferably of at least 10 and more preferably of at least 20.
In contrast to the prior art candles, the free organic acids used in the candles according to the present invention contain more unsaturated free organic acids, more particularly free fatty acids, or have in other words a higher iodine number. It has been found that these unsaturated free fatty acids enable, in a same way as the usual paraffins, to adjust the hardness and melting point of the candle fuel by controlling the weight fraction of unsaturated organic acids in the blend. These unsaturated organic acids are capable to provide an acceptable hardness of a mixture of saturated and unsaturated organic acids. When a candle fuel granulate is first produced, the presence of the unsaturated fatty acids in the candle fuel enables to obviate processing problems, especially the problems observed when granulating completely hardened fatty acid by spraying them in a liquid or partially crystallized state on a rotating cooling drum. Compared to the known partially hardened soybean oil, the unsaturated fatty acids can be produced more easily, and thus more cost effectively, by partially hardening free fatty acids which were first produced by hydrolysing natural oils or fats (glycerides). Notwithstanding these important advantages of the free fatty acids, they have hitherto not been used in the production of candles.

The melting points of some representative unsaturated compounds are presented in Table 1. For comparison, the fully saturated (hardened) stearic acid has a iodine number of less than 1 and a melting point of 69 degrees Celsius. The entries of elaidic and oleic acid in table 1 show that the iodine number is not uniquely correlated with the melting point of an organic acid but that also the structure (especially the cis or trans form of the double bond) has an effect on the melting point.

Table 1. melting points of pure compounds. The position of the double bond is indicated between brackets.

Compound	Iodine number	Melting point (°C)
Stearic acid, C18:0	0	69
Elaidic adic, C18:1 (trans 9)	90	46
Oleic acid, C18:1 (9)	90	13.4
Linoleic acid, C18:2 (9,12)	181	-5
α-Linolenic acid, C18:3 (9.12,15)	273	-11

The melting point is a very important parameter when producing candles. In accordance with the present invention the melting point of the candle fuel is adjusted by controlling the fraction of one or more unsaturated organic acids in the blend. Table 2 presents the melting point of blends of Oleon products 0436 and 0403. Oleon product 0436 is obtained by fully hardening a blend which consists mainly of palmitic and stearic acid. The iodine number of product 0436 is less than 1. The soft product Oleon 0403 has a iodine number of 60. It contains 48 wt% of fully saturated organic acids and 52 wt% of unsaturated organic acids. The unsaturated acids fraction consists of 3% C16:1, 41 wt% C18:1, 7 wt% C18:2 and 1 wt% C20:1.

Table 2. Control of the melting point by controlling the fraction of unsaturated acids.

Blend composition	Melting point, degrees C	Weight fraction, unsaturated acids in blend	Approximate iodine value gr I₂ per 100 g.
100 wt% 0436	55	0	1
90 wt% 0436 + 10 wt% 0403	53	5	6
75 wt% 0436 + 25 wt% 0403	51	13	15
50 wt% 0436 + 50 wt% 0403	47	26	30
25 wt% 0436 + 75 wt% 0403	42	39	45
100 wt% 0403	39	52	60

Melting point according to ASTM 938.

The controlled balance between the fraction unsaturated organic acids and the fraction saturated organic acids can be obtained by any means. Examples are adding a blend with a higher fraction of unsaturates to a blend with a smaller fraction of unsaturates. Another example of balance control is to stop the hydrogenation of a blend which is too high in unsaturated organic acids until the correct melting point or softness has been achieved.
Unsaturated organic acids can auto-oxidize and the oxidative rancidity of the product yields objectionable flavours and odours. Heavy metals can promote this auto-oxidation reaction. The said auto-oxidation reaction can be inhibited by adding anti-oxidants like citric acid which chelate with the heavy metals and render them inactive.

EXAMPLE 1.

A commercial molten (liquid) mixture consisting mainly of saturated palmitic and stearic acid, for example Oleon 0436 with a iodine value less than 1.0, cannot be cooled on a rotating cooling drum when a fine granulate powder is requested. This is a result of poor binding between the saturated Oleon 0436 product spray and the metal surface of the cooling drum. Adding 10 weight percent of unsaturated Oleon product 0403 was found to be sufficient to obtain a proper bonding between the partially crystallized liquid spray and the cooling drum. As a consequence, the presence of unsaturated organic acids enables the processing of organic acid mixtures on the cooling drum.

EXAMPLE 2.

A commercial molten (liquid) mixture consisting mainly of saturated palmitic and stearic acid, for example Oleon 0436 with a iodine value less than 1.0, can be sprayed and air cooled to form solid granules. However the powder granulate is very hard. Pressing of the powder yields a fragile tablet which easily breaks apart when exposed to mechanical handling. When unsaturated organic acids were added to the saturated stearic acid, the resulting powder was more ductile and could be pressed into tablets which were not fragile and were of sufficient mechanical strength. It was found that when adding for example 30 parts of Oleon product 0403 to 70 parts of the saturated Oleon product 0436 a good pressing product was obtained. The resulting tablets like tea lights could be handled mechanically with ease and were of sufficient quality for acceptation by the consumer.

EXAMPLE 3.

When a 9-day burner container contains a mixture of crystallized palmitic and stearic acid, the resulting melting point of 55 - 60 degrees Celsius is too high. A large flame is necessary to obtain the liquid melting pool in this case combined with a large fuel consumption. As a result the fuel is consumed rapidly and the 9-day burner burning period is too short. A state of the art solution is to use partially hardened soybean oil with a melting point of 37 degrees Celsius and a fuel consumption of 2.3 gram per hour. When the Oleon product 0403 is used combined with a suitable wick, a similar fuel consumption of 2.3 gram can also be achieved however at a considerable lower fuel cost. The new fuel Oleon 0403 with a low melting point of approx. 40 degrees Celsius offers significant commercial benefits when applied in a 9-day burner.

EXAMPLE 4.

Glass containers were filled with a liquid mixture of Oleon product 0403 and 0436, together with some proper compatibilizers to obtain a smooth candle appearance. The resulting candle had a lower melting point compared to a fully hardened stearin candle. This is advantageous because a fully hardened stearin candle would require a very large flame to melt the full circumference, with an associated large fuel consumption and hence a short burning period.

Claims

A candle containing a candle fuel which contains at least a mixture of free organic acids, in particular a mixture of free fatty acids, characterised in that said free organic acid mixture contains at least 5, preferably at least 10 and more preferably at least 20 weight percent unsaturated organic acids or has a iodine number of at least 5, preferably of at least 10 and more preferably of at least 20.
A candle according to claim 1, characterised in that said candle fuel has a melting point, measured in accordance with ASTM 938, lower than 52 degrees Celsius, in particular lower than 45 degrees Celsius.
A candle according to claim 1 or 2, characterised in that, at 20 degrees Celsius, the candle fuel is contained in a solid state a container, the candle being in particular able to burn for at least 7 days, preferably for at least 9 days.
A candle according to claim 1 or 2, characterised in that said candle is pressed or extruded from a granulate containing at least said candle fuel.
A candle according to any one of the claims 1 to 4, characterised in that it comprises additives, in particular anti-oxidants, to inhibit auto-oxidation reactions of the unsaturated carbon double bond.
A candle according to any one of the claims 1 to 5, characterised in that said organic acid mixture consists for at least 50 % by weight, preferably for at least 70% by weight, of C12 or higher fatty acids, preferably of C14 or higher C20 fatty acids and more preferably of C16 or higher fatty acids, the organic acid mixture consisting preferably for at least 50% by weight of C16 and C18 fatty acids.
A candle according to any one of the claims 1 to 6, characterised in that said candle fuel consists for at least 10% by weight, preferably for at least 30% by weight, more preferably for at least 50% by weight and most preferably for at least 70% by weight of said mixture of free organic acids.
A candle according to any one of the claims 1 to 7, characterised in that said candle fuel consists for at least 10% by weight, preferably for at least 30% by weight, more preferably for at least 50% by weight and most preferably for at least 70% by weight of a mixture of free fatty acids.
A candle according to any one of the claims 1 to 8, characterised in that it further contains at least one wick and additives like colorants, flagrances and emission control agents.
A process for producing a candle according to any one of the claims 1 to 9, characterised in that said candle fuel is applied in a molten state in a container and allowed to set therein to produce the candle or said candle fuel is granulated, in particular by spraying the candle fuel in liquid form on a rotating cooling drum or by spraying the candly fuel and cooling it in the air, and the granulated candle fuel is pressed or extruded into the shape of the candle.