US2700653A - Antifreeze - Google Patents

Description

United States Patent No Drawing. Application December 26, 1951, Serial No. 263,487

6 Claims. (Cl. 252-75) The present invention relates to an electrolyte or salt base anti-treeze liquid for cooling systems and, more particularly, it relates to a calcium chloride liquid antifreeze for use in the cooling systems of internal combustion engines that does not corrode or impair the walls of the cooling system.

Calcium chloride has always been recognized as an excellent freezing point depressant. However, the high corrosive enect, and particularly the electrolytic corrosive effect, or calcium chloride solutions upon the metal walls of cooling systems has precluded its use in this capacity. Attempts have been made in the past to add corrosion inhibitors to the calcium chloride solution but such corrosion inhibitors have always proved unsuccessful. This is mainly due to the fact that the modern internal combustion engine has at least four, and sometimes six, dilferent metals therein which are exposed to the action of the calcium chloride solution. In such cases, although one inhibitor was successful in protecting a particular metal, it would be found to have an extremely deleterious effect on another metal. Thus, it became necessary to add inhibitors for the inhibitors. The addition of each added inhibitor, however, only brought along new problems peculiar to that-inhibitor to that to date no completely efiicient inhibiting system has been devised for calcium chloride anti-freezes to be used in internal combustion engines. I

Accordingly, anti-freezes other than the salt base type have come into use. These anti-freezes are of the organic liquid type and as such do not cause electrolytic corrosion. Unfortunately, these organic anti-freezes are relatively expensive and in times of raw material shortages have placed a heavy drain on critical raw materials. At the same time, they do not attain as low a freezing point as do the calcium chloride anti-freezes.

In any attempt to produce an efficient corrosion inhibiting system for electrolyte base anti-freezes there are several factors to be considered. One of these factors is hydrolysis of the electrolyte base For example, in the case of calcium chloride, hydrolysis will produce free hydrochloric acid which attacks the metal walls of the cooling system.

Another factor to be considered is aeration. Although the cooling systems of internal combustion engines are closed systems for all practical purposes, they still admit air from the atmosphere and thus permit free oxygen to enter the coolant. Oxygen, of course, will tend to oxidize the metal surfaces of the cooling system. With increased circulatory motion of the coolant, oxygen unsaturated liquid is brought to the surface where it is exposed to the atmosphere of the air and takes on oxygen. Since a high velocity of the coolant in the system is desirable, it becomes necessary to device an anti-freeze wherein aeration can have no elfect.

A still further consideration is the temperature of the coolant. Although a higher temperature will dispel some of the dissolved oxygen, the increased temperature Will augment the rate of hydrolysis of calcium chloride thus producing more free acid to attack the metal wa ls.

However, the most troublesome factor in the production of a good electrolyte base anti-freeze is the constant electrolytic action that takes place between the electrolyte base solution and the metal walls of the cooling system. This phenomenon must be eliminated or at least reduced to a satisfactory minimum if a successful salt base non-corrosive anti-freeze is to be produced. In an attempt to overcome this electrolytic effect, mechanically produced barrier coatings between the solution and the metals as well as chemically produced barrier films or passivators, have been employed. Such coatings and films do achieve their protective purpose when the coolant is in a quiescent state, but once the coolant has begun to circulate then the protective coatings are eroded away, particularly at places where the circulatory motion of the liquid is violent, so that the surfaces of the metal are exposed to the electrolytic action of the salt base solution. Due to the higher temperature during the circulatory phase, the electrolytic rate between the salt and the metal walls will increase. This electrolytic increase is in addition to the increase of both the hydrolysis and erosion elfects taking place during the circulatory stage. Thus, in any suitable electrolyte antifreeze, it becomes necessary to deal with both the quiesfent phase and the circulatory phase of the cooling i uid.

l have invented an electrolyte base anti-freeze for internal combustion engines which employs a salt, such a It is an object of this invention to provide a salt base anti-freeze which has an extremely low freezing point temperature and which will not attack the walls of cooling system at both high and low temperatures.

It is a further object of this invention to provide a salt base anti-freeze solution that is suitable throughout its circulatory and quiescent phases.

Moreover, it is an object of the present invention to provide a colloidal solution or dispersion for use with a salt base anti-freeze which will overcome the corrosive qualities of a salt base due to hydrolysis, aeration and electrolytic action.

An advantage of the present invention is that due to its high boiling point and low freezing point it can be employed as a permanent type coolant suitable to both summer and winter weather.

A further advantage resides in the fact that my salt base anti-freeze has a higher specific heat than the present types so that its capacity to take up heat is superior to that of the present alcohol and glycol type anti-freezes.

In addition, since my salt base anti-freeze has a higher specific gravity than the present type anti-freezes, a greater volume of coolant will be circulated by the Water pumps at any given speed thus enhancing the cooling effect.

A still further advantage flowing from my invention is that it displaces the use of the more expensive organic chemicals as anti-freezes.

Moreover, it has the advantage that the beneficial freezing depressant effect of a salt base solution can be aitftained without the accompanying deleterious corrosive e ects.

Other objects and advantages of the present invention will become more apparent as it is described in detail below.

In accordance with the present invention, I have provided a salt base anti-freeze comprising a calcium chloride-sugar solution, a colloidal solution or dispersion of water and starch, and other corrosion inhibiting and lubricating agents.

The basic formula for compounding my novel antifreeze is shown below:

TABLE A Ingredients: Percentage by weight Calcium chloride 22-36 Water 72-58 Sugar A 4 Sodium nitrate 0.2 Triethanolamine 0.6 Soluble starch 0.3 Butyl Cellosolve 0.5 n-Butylalcohol 0.2 Barium hydroxide 0.05 Dibutyl phthalate 0.05 Urea 0.05 Octyl alcohol 0.05

It is to be expressly understood that my anti-freeze does not have to be made with strict adherence to the above percentages, but that these percentages may be reasonably departed from without effecting the invention. However, it is pointed out that the total percentage of water and calcium chloride present in the anti-freeze should approximate 94%.

In compounding my non-corrosive anti-freeze, hard or soft water may be used. If hard water is employed, several of the ingredients added to the water are capable of softening the water. The main water softening compound added to the water is barium hydroxide, which will remove magnesium sulphate, calcium sulphate, sulphuric acid, carbonic acid and carbon dioxide. Moreover, without such a compound as barium hydroxide or one similar to it to keep the solution on the alkaline side, the hydrochloric acid formed by hydrolysis of the calcium chloride solution would attack the walls of the cooling system. This, of course, is in addition to the attack on the walls due to the electrolytic action of the calcium chloride.

The calcium chloride employed may either be in the anhydrous or hydrated form. However, in the above formula, the percentages are based on the use of anhydrous calcium chloride. Sugar is employed in the antifreeze to prevent the calcium chloride from crystallizing out of solution due to vaporization when the anti-freeze is at a high temperature such as when the engine has been running for a long period of time.

The aqueous solution of calcium chloride and sugar form what may be thought of as the basic solution since they constitute the major portions of the anti-freeze.

Without limiting myself thereto in any manner, shape or form, I would like to suggest at this point the probable theories that explain the action of the following added ingredients which permit my salt base anti-freeze to be non-corrosive. However, it is to be expressly understood that I am not suggesting that this theory is the only explanation of the action of the added ingredients.

Sodium nitrate has long been known to have the function of a passivator. In such capacity the sodium nitrate will protect the aluminum walls of the cooling system by reacting therewith to form a film of aluminum oxide. This film of aluminum oxide is one of the barriers or films devised to prevent corrosion of the metals of the cooling system.

In addition to this aluminum oxide film, urea is added to the solution to produce a protective coating on the walls of the cooling system. The urea forms a complex compound, the constituency of which is unknown, but which serves as an excellent protective for the walls of the system, particularly during the quiescent stage.

Although the solution now has ingredients which form protective coatings, namely aluminum oxide film and the coating of urea complex, these are still insufficient to protect the cooling system adequately. This is because in the circulatory phases, the coolant will wash and erode away, at least partly, these two above barriers thereby exposing bare metal surfaces of the cooling system to the electrolytic action of the calcium chloride solution. This electrolytic factor is the most difficult one to control in the achievement of the non-corrosive salt base anti-freeze.

Accordingly, my anti-freeze includes a colloidal solution or dispersion which is designed to overcome this effect. This colloidal dispersion comprises Water, soluble starch and triethanolamine. The soluble starch is to be considered as the dispersoid and the water as the dispersing medium. In choosing a disperoid for my invention, a compound must be sought which has the following properties. First, the dispersoid must be an organic compound since an inorganic dispersoid presents too great an electrolytic effect to be employed with calcium chloride. Second, the dispersoid must be stable so that it does not lose its colloidal properties and permanently coagulate. Third, the dispersoid must be chemically inert so as not to react with the other ingredients of the anti-freeze solution. Fourth, the dispersoid must be reversible, i. e., if the dispersoid particles should temporarily coagulate, they must possess the ability to return m colloidal state.

I have foundthat boththe saccharo and proteinwate-r colloids have the above-four required properties.

However, of these groups I prefer the use of soluble starch. The soluble starch molecules due to their large surface area, exhibit a strong tendency to absorb ions in. solution and thus become electrically charged themselves. However, if the particles are deprived of their electrical charge they will surrender the colloidal state and coagulate. This occurs when there is an electrolytic action between the exposed walls of the cooling system and the electrolytic salt base. When this electrolytic action commences, the dispersoid particles will coagulate and form an augmentative protective coating on the bare metal Walls Once a barrier has been set up between the calcium chloride and the metal walls, electrolytic action stops. However, there are still left the coagulated starch particles. If the dispersoid is irreversible, all of the colloid will in short time coagulate and be subjected to erosive action during the circulatory phase. Thus the anti-freeze is eventually rendered use less. However, by choosing a reversible dispersoid, the starch particles will return to the colloidal statethus creating a fresh supply of colloid to prevent electrolytic action between the calcium chloride and the bare metal wa ls.

In addition, the dispersoid should have a specific gravity which is the same as or greater than the specific gravity of the entire solution, if it is to serve as an effective coating agent. If its specific gravity were less than as a whole, the coagulated particles would tend to rise to the top of the solution and thus not form a uniform coating over the bare metal surfaces of the cooling system.

Triethanolamine serves a double function in my antifreeze. Not only does it act in its well knowncapacity as a stabilizer for the water and soluble starch, but it also is a neutralizer for acid formed by the disassociation of calcium chloride. It thus augments the alkaline effect of the barium hydroxide.

I have also found that triethanolamine itself is insufficient as a stabilizer since large quantities are required to form a suitable starch-water colloid. It is well known that triethanolamine may be used in quantities of 5% and more to form stable colloids. However, when such large quantities are employed in my anti-freeze, the entire solution will become too viscous and therefore unsatisfactory. Thus, it becomes necessary to seek the aid of an agent which enhances the stabilizing effect of triethanolamine. Such an agent is butyl Cellosolve (ethylene glycol monobutyl ether). The combined efiect of the triethanolamine and butyl Cellosolve provide for a very stable colloid.

Dibutyl phthalate is primarily added as a lubricant during the circulatory stage of the coolant. As a lubricant it oils the surface Walls of the cooling system by providing a fine coating upon the walls. Furthermore, the dibutyl phthalate acts as an agglutinant for any of the coagulated starch coating that remains on the surface walls of the system. Although most of the starch will go back into colloidal state, there is a certain minor portion which will remain coagulated. It is this minor amount that the lubricant will agglutinate, thus forming a firmer starch coating. One reason that l have chosen dibutyl phthalate is because its specific gravity that of the solution is slightly higher than that of water thus insuring its complete dispersion in the anti-freeze solution during the circulatory stage.

I have, moreover, found that if n-butylalcohol is added to the anti-freeze, it serves as an excellent solvent for the organic materials employed in the anti-freeze. However, the addition of such compound is not necessary to the success of my invention.

Octyl alcohol is incorporated into the anti-freeze because of its anti-foaming qualities and of its evaporation depressant effect, i. e., it prevents loss of water. Although I prefer to use secondary normal octyl alcohol (2-oc-' tanol), other octyl alcohols, such as primary normal octyl alcohol (l-octanol) will also suffice for my purposes.

Thus, in operation, anti-freeze works as follows in order to prevent corrosion of the cooling system. The sodium nitrate and the urea each respectively form a film of aluminum oxide and a coating of urea complex ade'-' quate to protect thecooling system during the quiescent stage, However, when the engine is running andpthe coolant is circulating, as e awarl y cooling system.

At this point, electrolytic action will these protective barriers-"will be exposing; the metalwalls of the initiate between the calcium chloride solution and the metal walls. Once this electrolytic action commences, the electrically charged starch particles in the colloidal state will lose their charges and coagulate out on the exposed metal walls forming a suitable coating and barrier between the calcium chloride and the cooling system. It is true that in time the starch coating for the most part will return to colloidal state, but in that time a new film of aluminum oxide and a new film of urea complex will have formed to cover the eroded area. Thus, in the circulatory phase, there is always provided some means of protecting the metal walls against the electrolytic action and other corrosive effects of the calcium chloride-water coolant. Moreover, the dibutyl Example 4 Weight P t Ingredients by Green 5 Grams Weight Water 3, 785 5a. calcium chloride (dihydrate). 2, 854 39. 9 sucrose 350 4. 0 10 barium hydroxide 3 04 potassium nitrate. 12 2 morpholine 40 6 soluble starch 30 4 butyl Cellosolve.-- 4O 6 n-b utylaleohol 17 2 dibutyl phthalate. 2 .03 15 octyl alcoh 2 .03 urea 2 03 phthalate lubricant will add to the protective coating.

Below is an example of a typical formula for my novel anti-freeze. I

Example 1 Weight P t Ingredients by Grams Weight Water 4, 340 67. 9 calcium chloride 1, 710 26. 7 sucrose 260 4. 1 barium hydroxide- 2 03 sodium nitrate 6 09 triethanolamine. 25 4 10 .2 20 3 l0 2 dibutyl phthalate. 2 03 octyl alcohol (sec-normal) 2 03 urea 2 03 Although preferably I employ sucrose, other water soluble carbohydrates, such as'the mono-, .di-, and trisaccharides may be equally employed in place thereof.

Potassium nitrate and lithium nitrate may be employed as passivators in place of sodium nitrate.

Furthermore, hydroxy alkylamines, such as diethanolamine and monoethanolamine, and also morpholine may be employed in place of triethanolamine. Moreover, Carbitol (monoethyl ether of diethylene glycol) and butyl Carbitol (monobutyl ether of diethylene glycol) may be substituted in the basic formula for butyl Cellosolve.

Likewise, diethyl phthalate and isoamyl phthalate have also been found satisfactory as lubricants in place of dibutyl phthalate. Below are some examples which employ the various different equivalent compounds described above:

Example 2 Weight P t In edients by P gr Grams Weight Water 4, 394 65. 7 calcium chloride 1, 881 28. 2 sucrose 300 4. barium hydroxide 2. 33 04 potassium nitrate 8 1 dinthmmlnmlne 3O .4 soluble starch 20 3 Carbitol 25 4 n-buty 12 2 ethyl nhthalata 2 03 octyl alcohol 2 03 urea 2 03 Furthermore, the calcium chloride may be added in hydrate form as shown in Examples 3 and 4 below.

Example 3 Weight Percent In edients by Grams Weight Water 3, 785 54. 5 calcium chloride (dihydrate) 2, 718 39. 0 sucrose. 325 4. 7 barium hydroxide 2. 67 .04 sodium nitrate .1 monoethanolam 35 5 soluble starch 25 4 butyl Car-bitch.-- 30 .4 n-butylalcohol 15 2 amyl phthalate 2 .03 octyl alcohol 2 03 urea..-. 2 .03

In Table A, of course, the percentage ranges for the calcium chloride and water have already been given. It should be noted that in Examples 3 and 4, the percentage of calcium chloride is based on the dihydrate. In solution, the water of the dihydrate will add to the water used to dissolve the calcium chloride thereby bringing tlliese examples into conformity with Table A and the c aims.

Examples 1 through 4 show the sugar ranging from 4.1% to 4.9% by weight or approximately 4 to 5%.

Table A and the above examples show the barium hydroxide ranging from .03% to .05 by weight.

The above examples and Table A also disclose that the nitrate compounds range from 0.1 to 0.2% by weight; the organic nitrogen compounds range from 0.4 to 0.6% by weight; the soluble starch ranges from 0.2 to 0.4% by weight; and the ethylene glycol ethers range from 0.3 to 0.6% by weight.

It is to be expressly understood that the above examples are only representative of my invention and I am not in any way limiting myself thereto, particularly since any combination of the equivalent ingredients will result in a suitable and satisfactory anti-freeze.

However, regardless of the particular anti-freeze employed within the scope of my invention, the pH should range between a pH of 7 and 9.

In carrying out the manufacture of my anti-freeze, a tank is filled with water at room temperature. About 5% of the total amount of water employed is kept apart from p reparation of the soluble starch solution. To the remaming amount of water the calcium chloride is gradually added and evenly dissolved. Next, the sugar is added to the calcium chloride solution until it is comthese three ingredients comprise what may be considered the basic solution, barium soluble undesirable constituents that should be removed from the solution as soon as possible. The entire solutron lS stirred for approximately five minutes to insure complete solution and then filtered to remove undesirable msoluble impurities present in the calcium chloride, sugar and barium hydroxide.

Due to the heat of solution, the solution will now have a temperature of approximately 140 F. It is necessary that the solution be permitted to cool to approximately F. before the other ingredients are added. When the solutionjs at the proper temperature, sodium nitrate, urea, triethanolamine and butyl Cellosolve are added in that respective order.

Meanwhile, the soluble starch solution should be prepared in the following manner. The starch is added to about /3 of the water which has not yet been placed in the solution. This water should be at room temperature. The starch is stirred until the mixture has an homogeneous consistency. The remaining of the homogeneous mixture of soluble starch and cool water so as to provide a thorough and even dissolution of the soluble starch in the major solution. This total soluble starch preparation is then mixed into the major solution containing calcium chloride and sugar.

The n-butylalcohol, the dibutyl phthalate and octyl alcohol are respectively added to the entire solution, which is then agitated to attain a uniform distribution of ingredients and finally permitted to cool down to approximately 86 F. before it is placed in suitable coutainers.

Having thus described my invention, I claim:

1 .,A non-corrosive anti-freeze solution for internal combustion engines comprising from 22 to 36% by weight of calcium chloride, from 58 to 72% by weight of water, said calcium chloride and said water approximating 94% by weight of the solution, approximately from 43o 5% of a sugar of the class consisting of mono-, di-, and tri-saccharide and sucrose, approximately from 0.1 to 0.2% by weight of a nitrate of the class consisting of sodium, potassium and lithium nitrate, approximately 005% by weight of barium hydroxide, approximately from 0.4 to 0.6% by weight of a nitrogen compound of the class consisting of mono-, di-, and triethanolamine and morpholine, from 0.2 to 0.4% by weight of soluble starch, s'aid starch and said water forming a reversible colloid in the solution, and approximately 0.05% by y7veigh1t (91f urea, said solution having a pH range between an.,. l I I 2. A non corrosiye anti-freeze solution for internal combustion engines con'lpri sirig from 22. to 36% by weightlof calciumchloride, from 5 8 to 72% by weight qij water, said {calcium chloride and said water approxim t n 94% by, wei to es i iom app o e y from4 to 5%. by, Weight of sucrose, approximately from 0.1 to 0.2% by weight of sodium nitrate, approximately 0.05% by weight of barium hydroxide, approximately from 0.4 to 0.6% by weight of a nitrogen compound of the class consis'tingof mono-, di-, and tri-etha'nolamine and morpholine, from 0.2 to 0.14% by weight of soluble starch, said starch and said water forming a reversible colloid in the solution,

and approximately 0.05% by weight of urea, said solution having a pH range between 7a11 .9-.

3. A r on-corrosive anti-freezesolution for internal combustion engines in accord with claim 1 wherein said soluble starch has a specific gravity not less than the p i r V YPHa u iQ V t. .7 4. A non-corrosive anti-freeze solution; in accord with claim l wherein said solution furthercornprises approximately from 0.4 to 0.6% by weight of a' compound of the class consisting of monoethyl monobutyl ether of di'e'thylene glycol, and ethylene glycol monobutyl ether, and approximately 0.05%

by weight of combustion engines comprising from 22 to weight of calcium chloride, ,from 58 to 72% t of water, said calcium 36% by by weight chloride and said water approximating 94% by weight of the solution, approximately from 0.1 to 0.2% by weight of a nitrate ofrthe class consisting of s'odium,,potassium and lithium nitrate, approximately 0.05% mately from by weight of barium hydroxide, approxl- 0.4 to 0.6%

by weight of a nitrogen com pound of the class consisting of mono-, di, and triethanolamine and weight of soluble starch, said starch ing a reversible colloid in the solution, 0.005% by weight of urea,

morpholine, from 0.2 to 0.4% by and said water formand approximately said solution having a pH range between 7 and 9.

6..A non-corrosive anti-freeze solution for internal combustion engines weight of calcium chloride, from 58 to 72% comprising from 22 to 36% by by weight of water, said calcium chloride and said water approxmating 94% byweight of the solution,

approximately from 0.1 to 0.2% by w eight of sodium nitrate, approximately 0.05% by weight of barium hydroxide, approximately 0.4 to 0.6% by weight of tri-ethanolamine, from 0.2 to 0.4% by weight of soluble starch, said starch and said water forming a reversible colloid in the solution,

and approximately having a pH range 0.05% by weight of urea, said solution between 7 and 9.

References Cited in the file of this patent when STATES PATENTS ether oidiethylene glycol,

Claims (1)

1. A NON-CORROSIVE ANTI-FREEZE SOLUTION FOR INTERNAL COMBUSTION ENGINES COMPRISING FROM 22 TO 36% BY WEIGHT OF CALCIUM CHLORIDE, FROM 58 TO 72% BY WEIGHT OF WATER OF CALCUIM CHLORIDE AND SAID WATER APPROXIMATING 94% BY WEIGHT OF THE SOLUTION, APPROXIMATELY FROM 4 TO 5% OF A SUGAR OF THE CLASS CONSISTING OF MONO-, DIAND TRI-SACCHARIDE AND SUCROSE, APPROXIMATELY FROM 0.1 TO 0.2% BY WEIGHT OF A NITRATE OF THE CLASS CONSISTING OF SODIUM, POTASSIUM AND LITHIUM NITRATE, APPROXIMATELY 0.05% BY WEIGHT OF BARIUM HYDROXIDE, APPROXIMATELY FROM 0.4 TO 0.6% BY WEIGHT OF A NITROGEN, COMPOUND OF THE CLASS CONSISTING OF MONO-, DI-, AND TRI-ETHANOLAMINE AND MORPHOLINE, FROM 0.2 TO 0.4% BY WEIGHT OF SOLUBLE STARCH, SAID STARCH AND SAID WATER FORMING A REVERSIBLE COLLOID IN THE SOLUTION, AND APPROXIMATELY 0.05% BY WEIGHT OF UREA, SAID SOLUTION HAVING A PH RANGE BETWEEN 7 AND 9.