US2443082A

US2443082A - Synthetic lubricant

Info

Publication number: US2443082A
Application number: US540144A
Authority: US
Inventors: Orland M Reiff; Howard D Hartough; Jr Harry J Andress
Original assignee: Socony Vacuum Oil Co Inc
Current assignee: ExxonMobil Oil Corp
Priority date: 1944-06-13
Filing date: 1944-06-13
Publication date: 1948-06-08
Anticipated expiration: 1965-06-08

Description

Patented June 8, i948 SYNTHETIC LUBRICANT Orland M. Reifl, Woodbury, Howard D. Hal-tough, Pitman, and Harry J. Andress, Jr., Woodbury, N. J., assignors to Socony-Vacuum Oil 30mpany, Incorporated, a corporation of New York No Drawing. Application June 13, 1944, Serial No. 540,144

14 Claims. (oi. 252 47) This invention has to do with the art of lubrication and, more particularly, has to do with the preparation of synthetic lubricants.

In the lubricant art considerable progress has been realized in recent years in the production of lubricants characterized by one or more specific properties and adapted for particular uses. In the main, this progress can be attributed to two developments: the first, new refining procedures and, the second, addition agents capable of imparting particular properties to available lubricants. Although these lubricants are somewhat superior to those formerly available in the art, in general, they too suffer in one or more respects. For example, while such oils have superior viscosity characteristics, etc., they may have undesirable oxidation characteristics, etc. Recently, however, in an efi'ort to obtain superior lubricants endowed with specific and superior characteristics, a new field has been explored, namely, the synthesis of lubricants from various materials. The products so obtained have been aptly described in the art as synthetic lubricants.

While many of the synthetic lubricants recently prepared have been found to be desirable for various uses in view of a superior characteristic such as improved oiliness, viscosity, resistance to oxidation, etc., they invariably have extremely high pour points which naturally militate against their wide use in the art. Generally they suffer too from the disadvantage of a failure to respond to pour point depressants when the latter are incorporated therewith in relatively small amounts.

The present invention is predicated upon the discovery of a new and novel clas of synthetic lubricantsparafiin wax-toluenes-Which are characterized by relatively low pour points and which are responsive to substantial pour point depression upon the addition thereto of small amounts of a novel class of pour point depressants, the esters of alkyl-substituted phenols. The synthetic lubricants of this invention, in combination with the said pour point depressants, are all characterized by pour points of F. (A. S. T. M.) or lower and are further characterized by outstanding viscosity index values and resistance to oxidation.

Also contemplated herein, is a method for the preparation of the said new and novel synthetic lubricants, the method involving reacting certain partially halogenated paraflin waxes with toluene in the presence of a Friedel-Crafts catalyst at a condensation temperature and thereafter separating the catalyst and any unchanged reactants from the reaction mixture so obtained. While the present method may be briefly summarized by the foregoing statement, it is much more complex than as so stated, inasmuch as several of the factors recited therein are critical in nature and must be followed religiously lest products of a somewhat inferior character be formed. Specifically, the several critical factors, all of which are interrelated, include the following:

1. Type of paraflin wax,

2i Degree of halogenation of the parafiin wax an 3. Proportions of halogenated parafiin wax and of toluene.

0f importance in the present method is the type of parafiln wax used. We have'found that when a crystalline paraffin wax having a melting point not greater than about 140 F. is used, synthetic lubricant of relatively low pour point and susceptible to pour point depression are obtained.

Particularly preferred waxes of this type, however, are those having melting points from about F. to about F. These waxes have a crystalline structure, as opposed to other paraflin waxes which do not have a well-defined c ystal structure and are amorphous in character. The latter are commonly referred to as amorphous waxes, and are considered to be undesirable for the purposes of this invention, for such waxes would result in products having relatively high melting points and have comparatively little susceptibility to pour point depression. Of the waxes used herein we have found that particularly outstanding results are obtained with a crystalline paramn wax containing on the average of 24 carbon atoms and having a melting point of about 126 F. It is to be understood, however, that all rystalline paraiiin waxes characterized by melting points not greater than about F. and obtained from all sources, such as petroleum wax fractions, the Fischer-Tropsch synthesis, etc., are contemplated herein.

Accordingly, When used hereinafter the expression wax, unless otherwise qualified, denotes the desired reactant: crystalline paraiiin wax.

With regard to the degree of halogenation of wax which must .be followed, it may first :be said that all halogens may be used. In view of the relative cost, availability. etc., however, chlorine is preferred and, for these reasons, the following description will be confined to the chlorinated Waxes. It is essential that the chlorinated waxes reacted with toluene contain from about 18 per cent to 25 per cent chlorine. When chlorine concentrations in excess of the maxima, 25 per cent, are used, the products obtained therefrom are characterized by relatively high viscosities and do not have sufliciently low pour points- I-.when small amounts of the aforesaid pour point depressants are incorporated therewith. Similarly, when chlorine concentrations lower than about 18 per cent are used, the products so obtained contain excessive amounts of wax and have undesirably high pour points, above 0 F. I

It should be understood that a 20 per cent chlorinated wax is one prepared by introducing chlorine into a crystalline paraffin wax, as defined above, until the weight of the wax has increased about 20 per cent. Such a product is predominantly comprised of dichlorinated wax with substantial quantities of unchlorinated wax, monochloro wax and more highly chlorinated wax. It should also be understood that when other halogens are used in place of chlorine in the wax reactant, the foregoing percentage range from about 18 per cent to 25 per cent, will be subject to change in proportion to the relative atomic weights of the individual halogens.

Of primary importance are the relative amounts or proportions of the reactants, namely, chlorinated wax-and toluene. In order to obtain the desired product, at least one mole of toluene is reacted with an amount of chlorinated wax which contains one atomic weight of chlorine. In short, at least one mole of toluene is used for each atomic weight of chlorine in the chlorinated wax reactant. Accordingly, it will be clear that the reaction products obtained with such proportions are predominantly monowax toluenes. If less than one mole of toluene is used for each atomic weight of chlorine in a chlorowax, products of less desirable character are obtained. The latter products, unlike those contemplated herein, suffer from their failure to give pour points of 0 F. or lower when small amounts of the aforesaid pour point deressants are used herewith.

The reaction temperatures useful in the present method are those normally referred to in the art as Friedel-Crafts condensation temperatures. While temperatures from about 25 C. to about 110 C. may be used satisfactorily, the preferred reaction temperature is about 108 C., the boiling point of toluene.

The amount of catalyst used in the condensation should be relatively small, that is, a catalytic amount. Generally, amounts from about 1 per cent to about per cent by weight of the chlorowax reactant are satisfactory, and amounts of the order of 3 per cent are preferred. Catalysts such as aluminum chloride, zinc chloride, ferric chloride, boron trifiuoride, hydrogen fluoride, etc., serve the purpose of this invention; and for this reason, the catalysts are defined broadly herein as those capable of efiecting a Friedel-Crafts type condensation. Particularly preferred, however, is aluminum chloride.

In order to more fully illustrate the method by which our synthetic lubricants are obtained the following typical procedure is detailed hereinbelow.

EXAMPLE PREPARATION or Wax-Townes (1-18) Two moles of toluene (180 grams) and 198 grams of an 18 per cent chlorowax (126 F. A. S. T. M. melting point) are placed in a flask equipped with a thermometer, reflux condenser I and an electrically driven stirrer. The chlorowax used contains 1 atomic weight of chlorine. Aluminum chloride (6 grams) is slowly added to the chlorowax and toluene at a temperature of about 4 25 C. while agitating the same. The temperature is then raised to the reflux temperature of toluene, about 108 0., and maintained for about 1 hour to complete the condensation of chlorowax and toluene. The reaction mixture is then. purified by filtering through a contact clay to remove aluminum chloride. The filtrate is then heated to remove excess toluene and the residue obtained thereby is a wax-substituted toluene containing some unreacted wax, about 5 to 15 per cent unreacted wax. The unreacted wax is removed by vacuum distillation (it may also be removed by convention dewaxing procedures). The product is wax-toluene (1-18).

Parenthetical expressions (1-18) indicating that toluene is substituted with 1 wax group and that the chlorowax used in the preparation thereof contained 18 per cent chlorine are used hereinafter to so identify each product illustrative of the present invention, as well as related products which do not possess the superior characteristics of the lubricants prepared as outlined above.

It will be understood, of course, that any unreacted toluene can be used again in the preparation of additional product, and that unreacted wax can be further chlorinated for future use.

Although we have illustrated our synthetic lubricants by a product free of unreacted wax (removed by vacuum distillation, solvent dewaxing, etc), it is to be understood that it is not essential that all of the unreacted wax be removed. Accordingly, both wax-free synthetic lubricants and synthetic lubricants containing relatively small amounts of unreacted wax are contemplated herein.

In order to illustrate the superior characteristics of the synthetic lubricants of the present invention, several typical examples are presented hereinbelow in Table I. There, the S. U. V. at 210 F., viscosity index and A. S. T. M. pour test of the above synthetic lubricants are shown; all of these characteristics and methods for determining the same are well known in the art and need not be further described at this point. In addition the response of these synthetic lubricants with and without a pour point depressant is also demonstrated. Also present in Table I .for comparison with the synthetic lubricants contemplated herein are several typical products which are much less desirable for use as lubricants for one reason or another. For convenience in identifying the latter products, they are preceded by an X" in Table I.

1 A-pour depressant: tetra-wax phenol phthalate.

It will be clear on inspection of the pour test results set forth in Table I that wax-toluenes prepared from a chlorowax containing 12, 26 and 28 per cent chlorine do not give pour points of 0 F. and lower when a small amount of pour depressant A is incorporated therewith. Surprisingly, however, when the chlorowax reactant contains from about 18 per cent to 25 per cent chlorine, the

wax-toluenes obtained therefrom are susceptible of a pour point lowering to at least F. when small amounts of pour depressant A are added thereto.

It will be further noted from inspection of the results provided in Table I that the wax-toluenes (1-18) to (1-25) have viscosities (S. U. V. 210 F.) and viscosity indexes which make them extremely valuable lubricants, suitable for automotive and aviation use.

To illustrate the critical nature ofthe proportions of toluene and of the halogen wax reactants in obtaining the synthetic lubricants of this invention, and those related materials of somewhat inferior character, several typical examples of wax-toluenes are shown in Table II below. The data'in this table are similar to those shown in Table I above and the products not contemplated herein are again identified by the letter X" which precedes them, as X wax-toluene (3-21) Table II Product [V. I.

Wax-toluene (148; Wax-toluene (l-24 X wax-toluene 53-18) Xwax-toluene 3-24) X wax-toluene (5-18). X wax-toluene (5-24) l A=pour depressant: tetra-wax phenol phthalate.

plated herein. It is to be understood, however,-

that all esters of alkyl-substituted phenols, particularly those in which the alkyl substituent is parafiin wax, are broadly contemplated. Such depressants are described at length in Patent Nos. 2,048,465 and 2,048,466 issued to O. M. Reifi et al. Although varying amounts of these materials may be used, satisfactory results are obtained with concentrations of from about 0.125 per cent to about 1.0 per cent.

We claim:

1. A lubricant of low pour point comprising a synthetic lubricant having incorporated therewith a small amount, suflicient to characterize the said lubricant with a pour point at least as low as 0 R, of an ester of an alkyl-substituted phenol, said synthetic lubricant being prepared from a crystalline paraffin wax having a melting point not greater than about 140 F. and toluene by: partially halogenating the paraflin wax to form a mixture of halogenated wax and substantially unhalogenated wax containing an amount of halogen corresponding to from about 18 to 25 per cent chlorine; mixing the halogenated wax and unhalogenated wax with toluene in the proportion of at least one mole of toluene to each atom of halogen in the halogenated wax mixture; adding thereto a catalyst capable of effecting a Friedel-Crafts type condensation; heating the mixture thus obtained at a Friedel-Crafts colidensation temperature until substantially all .of the halogenated wax has reacted with said toluene; and separating the FriedebCrafts catalyst;

unreacted toluene and unhalogenated wax from the reaction mixture so obtained, to obtain said synthetic lubricant.

'2. A lubricant of low pour point comprising a synthetic lubricant having incorporated therewith a small amount, sumcient to characterize the said lubricant with a pour point at least aslow as 0 F., of an ester of an alkyl subs'tituted phenol, said synthetic lubricant being prepared from a crystalline paraflln wax having a melting point not greater than about 140? F. and toluene by: partially chlorinating the paramn wax to form a mixture of chlorinated wax and unchlorinated wax containing from about 18 to 25 per cent chlorine; mixing the chlorinated wax and unchlorinated wax with toluene in the proportion of at least one mole of toluene to each atom of chlorine in the chlorinated wax mixture; adding a Friedel-Crafts catalyst thereto; heating the mixture thus obtained under refluxing conditions to the refluxing temperature of toluene until substantially all of the chlorinated wax has reacted with said toluene; and separating the Friedel- Crafts catalyst, unreacted toluene and unchlorinated wax from the reaction mixture so obtained, to obtain said synthetic lubricant.

3. A lubricant of low pour point comprising a synthetic lubricant having incorporated therewith a small amount, sumcient to characterize the said lubricant with a pour point at least as low as 0 F., of an ester of an alkyl-substituted phenol, said synthetic lubricant being prepared from a crystalline paraflin wax having a melting point between about F. and about F. and toluene by: partially chlorinating the parafiin wax to form a mixture of chlorinated wax and unchlorinated wax containing from about 18 to 25 per cent chlorine; mixing the chlorinated wax and unchlorinated wax with toluene in the proportion of at least one mole of toluene to each atom of chlorine in the chlorinated wax mixture; adding a Friedel-Crafts catalyst thereto; heating the mixture thus obtained under refluxing conditions to the refluxing temperature of toluene until substantially all of the chlorinated wax has reacted with said toluene; and separating the Friedel-Crafts catalyst, unreacted toluene and unchlorinated wax from the reaction mixture so obtained, to obtain said synthetic lubricant,

4. A lubricant of low pour point comprising a synthetic lubricant having incorporated therewith a small amount, suflicient to characterize the said lubricant with a pour point at least as low as 0 R, of an ester of an alkyl-substituted phenol, said synthetic lubricant being prepared from a crystalline parafiin wax having an average of about 24 carbon atoms and a melting point of about 126 F. and toluene by: partially chlorinating the paraflin wax to form a mixture of chlorinted wax and unchlorinated wax containing from about 18 to 25 per cent chlorine; mixing the chlorinated wax and unchlorinated wax with toluene in the proportion of at least one mole of toluene to each atom of chlorine in the chlorinated wax mixture; adding a Friedel-Crafts catalyst thereto; heating the mixture thus obtained under refluxing conditions to the refluxing temperature of toluene until substantially all of the chlorinated wax has reacted with said toluene; and separating the Friedel-Crafts catalyst, unreacted toluene and unchlorinated wax from the reaction mixture of chlorinated wax and unchlorinated wax containing irom about 18 to 25 per cent chlorine; mixing the chlorinated wax and unchlorinated wax with toluene in the proportion of at least one mole of toluene toeach atom of chlorine in the chlorinated wax mixture; adding a catalytic amount of aluminum chloride thereto; heating the mixture thus obtained under refluxing conditions to the refluxing temperature of toluene until substantially all of the chlorinated wax has reacted with said toluene; and separating the aluminum chloride, unreacted toluene and unchlorinated wax from the reaction mixture so obtained, to obtain said synthetic lubricant.

6. A lubricant of low pour point comprising a synthetic lubricant having incorporated therewith a small amount, suilicient to characterize the said lubricant with a pour point at least as low as 0 F., of an ester of an alkyl-suhstituted phenol, said synthetic lubricant being prepared from a crystalline parailln wax having a melting point not greater than about 140 F. and toluene by: partially chlorinating the paraflin wax to form a mixture of chlorinated wax and unchlorinated wax containing from about 18 to 25 per cent chlorine; mixing the chlorinated wax and unchlorinated wax with toluene in the proportion of at least one mole of toluene to each atom oi! chlorine in the chlorinated wax mixture; adding a Friedel- Crafts catalyst thereto; heating the mixture at about 110 C. until substantially all of the chlorinated wax has reacted with said toluene; and separating the Friedel-Crafts catalyst, unreacted tolueneand unchlorinated wax from the reaction mixture so obtained, to obtain said synthetic lubricant.

7. A lubricant of low pour point comprising a synthetic lubricant being prepared from a cry!- talline paraiiln wax having a melting point from about F. to about F. and toluene by: partially chlorinating the paramn wax to form a mixture or chlorinated wax and unchlorinated wax containing from about 18 to 25 percent chlorine; mixing the chlorinated wax and unchlorinated wax with toluene in the proportion of at least one mole or toluene to each atom of chlorine in the chlorinated wax mixture; adding a Friedel- Crafts catalyst thereto; heating the mixture thus obtained under refluxing conditions to the refluxing temperature of toluene until substantially all 0! the chlorinated wax has reacted with said toluene; and separating the Friedel-Crai'ts catalyst, unreacted toluene and unchlorinated wax from the reaction mixture so obtained, to obtain said synthetic lubricant.

9. The method of preparing a lubricant having a pour point at least as low as 0 F. which comprises: partially halogenating a crystalline paraffin wax having a melting point not greater than about F. to form a mixture oi! halogenated wax and substantially unhalogenated wax containing an amount of halogen corresponding to from about 18 to 25 per cent chlorine; mixing the halogenated wax and unhalogenated wax with toluene in the proportion of at least one mole of toluene to each atom of halogen in the halogenated wax mixture; adding thereto a catalyst capable ot'efiecting a Friedel-Craits type condensation; heating the mixture thus obtained at a Friedel-Crafts condensation temperature until substantially all of the halogenated wax has reacted with said toluene; separating the Friedel- Crafts catalyst, unreacted toluene and unhalosynthetic lubricant having incorporated there-' with a small amount, suillcient to characterize the said lubricant with a pour point at least as low as 0 F., of an ester of a wax-substituted phenol, said synthetic lubricant being prepared from a crystalline paraflin wax having a melting point not greater than about 140 F. and toluene by: partially chlorinating the parafliln wax to form a mixture of chlorinated wax and unchlorinated wax-containing from about 18 to 25 per cent chlorine; -mixing the chlorinated wax and unchlorinated wax with toluene in the proportion of at least one mole of toluene to each atom of chlorine in the chlorinated wax mixture, adding a, Friedel-Crafts catalyst thereto; heating the mixture thus obtained under refluxing conditions to the refluxing temperature of toluene until substantially all of the chlorinated wax has reacted with said toluene; and separating the Frledel- Crafts catalyst, unreacted toluene and unablerinated wax from the reaction mixture so obtained, to obtain said synthetic lubricant.

8. A lubricant of low pour point comprising a synthetic lubricant having incorporated therewith a small amount, suiiicient to characterize the said lubricant with a pour point at least as low as' 0 F., of tetra-wax phenol phthalate, said genated wax from the reaction mixture so obtained; and adding thereto a small amount suincient to characterize the said lubricant with a pour point at least as low as 0 F. of an ester oi an alkyl-substituted phenol.

10. The method of preparing a lubricant having a pour point at least as low as 0 F. which comprises: partially chlorinating a crystalline paraflln wax having a melting point not greater than about 140 F. to form a mixture of chlorinated wax and substantially unchlorinated wax containing from about 18 to 25 per cent chlorine; mixing the chlorinated wax and unchlorinated wax with toluene in the proportion of at least one mole of toluene to each atom of chlorine in the chlorinated wax mixture; adding thereto a Friedel-Crafts catalyst; heating the mixture thus obtained under refluxing conditions to the refluxing temperature of toluene until substantially all of the chlorinated wax has reacted with said toluene; separating the Friedel-Crafts catalyst, unreacted toluene and unchlorinated wax from the reaction mixture so obtained; and adding thereto a small amount suflicient to characterize the said lubricant with a pour point at least as low as 0 F. of an ester of an alkyl-substituted phenol.

11. The method of preparing a lubricant having a pour point at least as low as 0 E, which comprises: partially halogenating a crystalline paraflin wax having a melting point not greater than about 140 F. to form a mixture of unhalogenated wax and substantially unhalogenated wax containing an amount of halogen corresponding to from about 18 to 25 percent chlorine; mixing the halogenated wax and unhalogenated wax with toluene in the proportion of at least one mole of toluene to each atom of halogen in the halogenated wax mixture; adding thereto a catalyst capable of efiecting a Friedel-Craits type cient to characterize the said lubricant with a pour point at least as low as F. of an ester of an alkyl-substituted phenol;

12. The method of preparing a lubricant having a pour point at least as low as 0 FE, which comprises: partially chlorinating a crystalline parafiin wax having a melting point not greater than about 140 F. to form a mixture of chlorinated wax and substantially unchlorinated wax containing from about 18 to 25 per cent chlorine; mixing the chlorinated wax and unchlorinated wax with toluene in the proportion of at least one mole of toluene to each atom of chlorine in the chlorinated wax mixture; adding thereto a Friedel-Crafts catalyst; heating the mixture thus obtained under refluxing conditions to the refluxing temperature of toluene until substantially all of the chlorinated wax has reacted with said toluene; separating the Friedel-Crafts catalyst, unreacted toluene and unchlorinated wax from the reaction mixture so obtained; and adding thereto a small amount sufiicient to characterize the said lubricant with a pour point at least as low as 0 F. of an ester of an alkyl-substituted phenol.

13. The method of preparing a lubricant-having a pour point at least as low as 0 F. which comprises: partially halogenating a crystalline paramn wax having a melting point not greater than about 140 F, to form a mixture of halogenated wax and substantially unhalogenated wax containing an amount of halogen corresponding to from about 18 to 25 per cent chlorine; mixing the halogenated wax and unhalogenated wax with toluene in the proportion of at least one mole of toluene to each atom of halogen in the halogenated wax mixture; adding thereto a catalyst capable of effecting a Friedel-Crafts type condensation; heating the mixture thus obtained at a Friedel-Crafts condensation temperature until substantially all of the halogenated wax h'as reacted with said toluene; separating the Friedel- Crafts catalyst, unreacted toluene and unhalogenated wax from the reaction mixture so ob- 10 tained; and adding thereto a small amount sumcient tocharacterize the said lubricant with a pour point at least as low as 0 F. of tetra-wax phenol phthalate.

14. The method of preparing a lubricant having a pour 'point at least as low as 0 F. which comprises: partially chlorinating a crystalline paramn wax having a melting point not greater than about F. to form a mixture of chlorinated wax and substantially unchlorinated wax containing from about 18 to 25 per cent chlorine; mixing the chlorinated wax and unreacted wax with toluene in the proportion of at least one mole of toluene .to each atom of chlorine in the chlorinated wax mixture; adding thereto a Friedel-Crafts catalyst; heating the mixture thus obtained under refluxing conditions to the refluxing temperature of toluene until substantially all of the chlorinated wax has reacted with said toluene; separating the Friedel-Crafts catalyst, unreacted toluene and unchlorinated wax from the reaction mixture so obtained; and adding thereto a small amount suflicient to characterize the said lubricant with a pour point at least as low as 0 F. of an ester of tetra-wax phenol phthalate.

ORLAND M. REIFF. HOWARD D. HARTOUGH. HARRY J. ANDRESS, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,339,493 Lieber et al Jan. 18, 1944 2,350,571 Schilling June 8, 1944 2,297,292 Davis et al "Sept. 29, 1942 2,189,924 Pier et a1. Feb. 13, 1940 2,048,466 Reiif et al. July 21, 1938 FOREIGN PATENTS Number Country Date 491,522 Great Britain Sept. 5, 1938 478,972 Great Britain Jan, 27, 1938 OTHER REFERENCES The Condensed Chemical Dictionary, "mum Edition, 1942. Reinhold Publishing Corporation,

0 New York, page 487.