US2726526A - Candles having reduced dripping properties - Google Patents

Description

'CANDLES HAVING REDUCED DRIPPING PROPERTIES Donald C. Walker, Lansing, 111., assignor to Standard Oil,

Company, Chicago, IlL, a corporation of Indiana (Ilaims. (Cl. 67-22) This invention relates to candles and it pertains more particularly to candles which have a minimum tendency to drip when burned.

Although the body portion of candles *hasbeen made in whole or in part from paraffin waxes of petroleum'origin for some time, their quality frequently varies. One serious defect which often occurs is that upon burning the candle, a portion of the melted wax drips down the side of the candle. This wax which drips down the candle is not available for-burning and the eficctive burning time of the candle is reduced in direct relationship to the amount of melted wax which drips down the candle, which may be as much as 50%. In addition, dripping candles constitute a hazard to the users thereof since hot melted wax may escape from the candle holder and do serious damage. The wax which 'drips down the side of the candle also gives it a less pleasing and often unsightly appearance. An object of this invention is to provide a method and means for reducing the tendency of candles to drip when burned. Another object "of this invention is to improve the'appearance of candles when burned and also substantially eliminate'thehazard involved in burning candles. A further object is to provide a candle having the describedimproved properties and a method of manufacture therefor. Other objects will become apparent in the course of the detailed description of the invention.

If two candles, of identical size, shape-and wick are made under identical conditions from two diflferentparaffin waxes of the same melting point and then burned, a diference will often be noted in :the dripping rate of the two candles. In view of the identity 'of conditions, particularly in that the paraffin waxes have the same melting point, this is somewhat surprising. .Ithas been discovered that if the paraflin wax is subjected to oxidizing conditions, particularly while in its melted state so that it contains about 10 .milliequivalents of peroxide .or more per kilogram of wax, the candle made therefrom will have a greater tendency to drip when it is burned. The reason why oxidation'of the wax increases its dripping tendency is not known, although it is possible that acids, aldehydes, peroxides, and the like'which might be formed, may cause this 'tmdesirable phenomenon. This discovery suggested :the :addition of "antioxidants to the wax prior to allowing the'wax to be exposed to the type of oxidation'which'usually occurs dur-' ing the manufacture of candles. It was then discovered that only certain antioxidants are effective in reducing the dripping tendencyof the candle, while others have no effect or even increase the dripping rate of the candle upon burning. It has been discovered that if from about 0.001 to about 0.1%, preferably 0.01 to 0.03% by weight, of a substituted phenolic compound such as di-tertiary butyl para-cresol, tertiary butyl para-methoxy phenol, .or methylene bis para-cresol is added to a melted, substantially non-oxidized parafiiniwax, i. e. containing Jess than about 10 milliequivalents ;of peroxide per kilogram of wax, prior to further exposure 'of the'wax to oxidiz- 2,726,526 Patented Dec. 13, 1955 ing conditions such as usually occurs in the manufacture of candles and the body of a candle is made from this wax, the finished candle will display substantially no tendency to drip when burned. This is true 'even though the mixture of melted wax and substituted phenolic compound is subjected to severe oxidizing conditions prior to manufacturing the candle body therefrom. The candle body may consist essentially of paraflin wax, as is used in manufacturing votive lights or the like, or it may consist essentially of a mixture of l to 50% by weight stearic acid with the remainder parafiin wax, this latter type mixture being employed in making molded or hand dipped candles. The paraflin wax may have an ASTM melting point between about to F., preferably between about 122 to 137 'F. If'stearic'aci'd is employed in the wax body of the candle, it is "preferably used in amounts of 10 to 40% by'weigh't. In manufacturing the candle, the stearic acid, wax, and substituted phenolic compound are thoroughly mixed while in the liquid, i. e. melted, state and the mixtureis then used to make the candle body. The stearic acid need not be of high purity and surprisingly, it may contain as high as 15 to 20 milliequivalents of peroxide per kilogram of stearic acid and the finished candle containing such stearic acid will be substantially free from dripping upon burning. It will be free of dripping even though the mixture of melted wax, impure stearic acid, and substituted phenolic compound is subjected to severe oxidizing conditions which would cause 'a candle prepared under identical conditions but containing no substituted phenolic compound to drip very much.

My invention has applicability in general to candles which have a body comprised in whole or in part of parafiin wax. The body of the candle, which surrounds the wick, may be composed of any suitable para'fiin wax, i. e., usually having a melting point between about '115 to 170 F., preferably about 122 to 137 F.,"provided that the wax has not been-substantially oxidized or subjected to substantial exposure to oxidizing conditions such that the wax contains more than about 10 milliequivalents of peroxide .per kilogram of wax. The paraffin waxes which are of petroleum origin are usually "obtained by the sweating of crude scale wax followed by refining the wax by acid treating and finishing by percolating through a diatomaceous earth.

The invention has applicability to candles such as votive lights and molded or hand dipped-candles. Votive lights ordinarily are composed of parafiin wax preferentially having a melting point between about 115 to 137 F., such as 122 to 127 F. Although dripping is ordinarily not a problem with votive lights since the candle is usually encased within a glass or metal container, votive lights often are defective in their rate of burning. Frequently the votive light will burn with a lower flame and more slowly than is desirable. The amount of light given off is then insufficient for the illuminationdesired. In addition, the flame being smaller, it is much more easily snuffed out by drafts. I have discovered that the reduced burning rate or size of the flame of a votive light is directly related to the dripping tendency of the candle and consequently that my technique for reducing the dripping tendency of a candle upon burning will also increase the burning rate or size of flame when burning a votive light.

The body of molded, hand dipped, or decorative candles usually consist of l to 50% by weight stearic acid with the remainder consisting of parafiin wax having a melting point between about 115 to 170 F., preferably between about 122 to 137 F. The stearic acid may be single, double, or triple-pressed stearic acid. It need not 'be'free of peroxides, as is contrasted with the necessity that the parafiin wax contain less'than about 10 milliequivalents of peroxide per kilogram of wax. The stearic acid may be of impure form and may contain up to 50 milliequivalents of peroxide per kilogram of stearic acid. For example, tests have shown that a candle having a body prepared from paraffin wax, stearic acid containing 20 milliequivalents of peroxide per kilogram of stearic acid, and the substituted phenolic compound which had been subjected to oxidation for 48 hours at 200 F., did not drip to any substantial extent, i. e. less than about 1 to 2% by weight. This is particularly surprising because if the added parafiin wax in such a mixture were characterized by the same peroxide number, the candle mad from the mixture would drip extensively.

The substituted phenolic compound may be di-tertiary butyl para-cresol (2,6-di-tertiary butyl-4-methyl phenol), tertiary butyl para-methoxy phenol (2-tertiary butyl 4- methoxy phenol), or methylene bis para-cresol often termed bis(2 hydroxy 5 methyl phenyl) methane. Related compounds such as para-tertiary butyl catechol (1,2-dihydroxy 4-tertiary butyl benzene), bis (2-hydroxy S-methylphenyl) sulfide which is hereinafter called sulfur bis para-cresol, bis(2-hydroxy S-methylphenyl) sulfoxide which is hereinafter called thionyl bis para-cresol, and bis(2-hydroxy S-chlorophenyl) sulfide which is hereinafter called sulfur bis para-chlorophenol were surprisingly found to be ineffective. The substituted phenolic compound is incorporated in an amount between about 0.001 to 0.1% by weight based upon the paraffin wax and stearic acid, if the latter is present at all. This amount is normally sufiicient to inhibit dripping of the candle, but if the paraffin wax containing this same amount of substituted phenolic compound is subjected to extreme oxidizing conditions, it may be necessary to employ somewhat more of the substituted phenolic compound. In usual commercial installations for manufacturing candles, it is preferred to employ about 0.01 to 0.03% by weight of the substituted phenolic compound. As little as 0.001% by weight of the substituted phenolic compound may be employed and a significant improvement may be noted in the quality of the candle. However, if less than this amount is employed it is generally insuificient to prevent the subsequent exposure of the melted paraffin Wax to oxidizing conditions from increasing the dripping properties of the candle. This is especially true if the body of the candle is to be manufactured from a mixture of paraffin wax and impure stearic acid having a peroxide content of or more milliequivalents of peroxide per kilogram of stearic acid. With such impure stearic acid it is preferred to employ approximately 0.01 to 0.03% by weight of the substituted phenolic compound based on paraifin wax plus stearic acid.

In commercial practice the substituted phenolic compound may be employed in the candle manufacturing process by adding the necessary small amount of substituted phenolic compound to a refined and substantially non-oxidized parafiin wax (preferably containing less than about 5 milliequivalents of peroxide per kilogram of wax) while the wax is in the melted state. The temperature of the melted wax will vary, dependent to some extent on the melting point of the wax. It is preferably just slightly higher than is necessary to prevent any solidification of the wax. The substituted phenolic compound is mixed and/ or dispersed within the melted wax and the stearic acid, if any is to be added, is then added to the wax containing substituted phenolic compound followed by further mixing. The liquid mixture of paraifin wax, substituted phenolic compound and stearic acid if any, is then used to make the body of the candle either by conventional hand dipping or molding processes. It is during the same that the vat of melted parafiin wax is exposed to the atmosphere that peroxides form in the wax and an increase in its dripping tendency occurs, and therefore, it is important that the substituted phenolic compound be added to the paraffin wax prior to any substantial exposure of the melted wax to oxidizing conditions, i. e. atmospheric oxygen.

A number of experiments were performed to demonstrate the effectiveness of various substituted phenolic compounds for reducing the tendency of candles to drip when made from wax containing phenolic compounds which had been subjected to oxidizing conditions. Eight samples were prepared by adding parts by weight of melted paraflin wax, 40 parts by weight of stearic acid and 0.02 part by weight of the substituted phenolic compound, in samples where the latter was used, to a glass beaker contained on a steam bath. The parafiin wax was a refined petroleum wax having an ASTM melting point of F. and a peroxide number of 0 milliequivalents per kilogram of wax. The stearic acid was Darling double-pressed stearic acid containing 15 milliequivalents of peroxide per kilogram. The peroxide number, which is a measure of that active oxygen which will cause oxidation of a reducing agent, is determined by a standard test such as for example, dissolving the sample in a solvent and adding thereto potassium iodide in a solution of acetic acid and isopropyl alcohol, and then titrating the released iodine with a standard solution of sodium thiosulfate. The sample of melted paraffin wax, stearic acid, and substituted phenolic compound was stirred at F. until thoroughly mixed. To each sample was added a one-inch square of aluminum foil to catalyze oxidation of the sample and to simulate plant operation wherein aluminum kettles are employed. The temperature of the sample was raised to 200 F. and air was bubbled through the sample at the rate of 2 to 3 bubbles per second (approximately 20 to 40 milliliters of air per minute) through a glass tube having its outlet near the bottom of the beaker. The sample was exposed to daylight and artificial light while continuing the oxidizing treatment. Air was bubbled through each sample for about 48 hours.

Molded candles were then prepared from each sample and the candles were burned and their dripping rates measured. The candles prepared were 1% inches in diameter, about 12 inches long, and had 42-thread wicks. The candles prepared from the samples were positioned on a fiat supporting surface and were burned in a draftproof room until only a stub about 2 inches high remained, at which time they were extinguished. The waxy drippings were scraped off the candle stub and the adjacent supporting surface and the drippings collected and weighed. Comparisons of the rate of dripping of each sample candle is given below in Table I as the percentage drip, which is measured by dividing the weight of the candle drippings by the original weight of the candle and multiplying by 100.

Table I Substituted Phenolic Compound g g The above Table I clearly shows that the substituted phenolic compounds contained in samples 2, 3, and 4 where highly effective in preventing the candle from dripping whereas the phenolic compound antioxidant contained in samples 5, 6, 7, and 8 were ineffective for this purpose and frequently increased the percentage dripping over that exhibited by the candle made from sample 1 which contained no substituted phenolic compound.

The effectiveness of the substituted phenolic compounds in increasing the burning rate of votive lights was deter mined in an additional set of experiments. In these experiments the votive light candle was made from a refined petroleum paraflin wax having an ASTM melting point of 122 to 127 F. without any added stearic acid. The melted parafiin wax was added to a glass beaker on a steam bath and mixed with 0.02% by weight of ditertiary butyl para-cresol (2,6-ditertiary butyl 4-methyl phenol) at 165 F. A one-inch square piece of aluminum foil was added to the mixture and air was bubbled through the mixture at a rate of about 2 to 3 bubbles per second (20 to 40 milliliters of air per minute) while maintaining the contents of the beaker at about 200 F. The beaker containing this mixture was exposed to natural and artificial light. Air was continuously bubbled into the bottom of the beaker and samples of the wax sutficient to manufacture a votive light candle therefrom were withdrawn each day. The oxidation was continued for 15 days. The votive light candles which were made from the samples Withdrawn each day were then tested to determine their burning rates. Burning rates were measured by completely burning, in a draft-proof room, the votive light candle while it was encased within the usual cylindrical glass enclosure. The total weight of the candle in grams divided by the time in hours is the measure of the burning rate. Table II which follows shows the burning rate of the votive light candles made from the parafiin wax which had been subjected to oxidation for 15 days according to the above described procedure.

The data in Table II show that oxidation of the wax for 15 days reduces the burning rate from 3.5 grams per hour to 2.9 grams per hour. Although the burning rate is decreased by only some 20%, the flame of the votive light candle made from the wax which had been subjected to oxidation was only about one-half the size of the flame of the votive light candle made from wax which had not been subjected to oxidizing conditions. The flame was so reduced in size that it was very easily extinguished by small drafts and it was commercially unacceptable. The votive light made from the parafiin Wax containing the di-tertiary butyl para-cresol which had been subjected to the same oxidizing conditions showed no difference in burning rate from a candle prepared from a wax which had not been subjected to oxidation. The direct relationship between burning rate of a candle and dripping rate of a candle may thus be noted in view of the data presented in Tables I and II.

Thus having described the invention what is claimed 1s:

1. The method of manufacturing a paraflin wax base candle which has a reduced tendency to drip when burned which comprises incorporating from about 0.001 to 0.1% by weight of at least one substituted phenolic compound selected from the class consisting of di-tertiary butyl paracresol, tertiary butyl para-methoxy phenol, and methylene bis para-cresol within a substantially non-oxidized melted paraffin wax prior to further exposure of said melted parafiin wax to oxidizing conditions and forming a candle having a body comprised of said paraflin wax containing said substituted phenolic compound.

2. The method of claim 1 wherein said substantially non-oxidized melted paraflin wax is characterized by a peroxide number of less than about 10 milliquivalents of peroxide per kilogram of wax.

3. The method of claim 1 wherein said substituted phenolic compound is incorporated in an amount between about 0.01 to 0.03% by weight based on said wax and wherein said parafiin wax has a melting point between about to F.

4. The method of claim 1 wherein the body of said parafiin wax base candle comprises essentially from about 1 to 50% by weight of stearic acid, from about 0.01 to 0.03% by weight of said substituted phenolic compound, and the remainder paraffin wax having a melting point between about l15 to 170 F.

5. The method of claim 4 wherein said stearic acid is characterized by a peroxide content of between about 1 to 50 milliequivalents of peroxide per kilogram of stearic acid.

6. As an article of manufacture a candle having a reduced tendency to drip when burned which comprises a wick and a substantially non-oxidized paraffin wax base body having a peroxide content of less than 10 milliequivalents of peroxide per kilogram of wax and containing from about 0.001 to 0.1% by weight of at least one substituted phenolic compound selected from the class consisting of di-tertiary butyl para-cresol, tertiary butyl para-methoxy phenol, and methylene bis para-cresol.

7. The candle of claim 6 wherein said paraffin wax has a melting point between about 115 to 170 F. and wherein said substituted phenolic compound is contained in an amount from about 0.01 to 0.03% by weight.

8. As an article of manufacture a candle having a reduced tendency to drip when burned which comprises a wick and a waxy body portion, said body portion comprising essentially 1 to 50% by weight stearic acid, 0.001 to 0.1% by weight of at least one substituted phenolic compound selected from the class consisting of di-tertiary butyl para-cresol, tertiary butyl para-methoxy phenol, and methylene bis para-cresol, and the remainder substantially non-oxidized paraflin wax having a peroxide content of less than 10 milliequivalents of peroxide per kilogram of wax.

9. The candle of claim 8 wherein said substituted phenolic compound is contained in an amount between about 0.01 to 0.03% by weight and wherein said substantially non-oxidized paraflin wax has a melting point between about 115 to 170 F.

10. As an article of manufacture a candle having a reduced tendency to drip when burned which comprises a wick and a waxy body portion, said body portion comprising essentially between about 10 to 40% by weight of stearic acid having a peroxide content between about 2 to 50 milliequivalents of peroxide per kilogram of stearic acid, about 0.01 to 0.03% by weight of at least one substituted phenolic compound selected from the class consisting of di-tertiary butyl para-cresol, tertiary butyl para-methoxy phenol, and methylene bis para-cresol, and the remainder substantially non-oxidized paraifin wax having a melting point between about 122 to 137 F.

References Cited in the file of this patent Modern Packaging, volume 26, Number 4, pp. 153, 154, December 1952.