Branched ether esters as viscosity index modifiers

Abstract

The present invention deals with novel internal branched ether esters based upon novel ether alcohols. These materials are useful as viscosity index modifiers where outstanding liquidity, resistance to oxidation, and minimal variation in viscosity as a function of temperature is required.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention deals with novel branched ether ester compounds useful as viscosity index modifiers. These esters are derived from novel branched ether alcohols. It is because of the internal location of the branched ether group in these ether esters that these materials are very efficient viscosity index modifying materials. They have low viscosity, are stable to oxidation and exhibit minimal variation in viscosity as a function of temperature. All of these properties are required for a viscosity index modifier.

2. Description of the Art and Practices

Viscosity index modifiers are known in the art. Typical teachings are as follows:

U.S. Pat. No. 4,207,196, to Sudekum issued June 10, 1980 teaches that ethylene/alpha olefin polymers are useful in viscosity index modification.

U.S. Pat. No. 4,212,816 to Hentschel issued July 15, 1980, teaches that pentaerythritol esters of carboxylic acids are useful as viscosity index modifiers.

U.S. Pat. No. 4,181,618 to Durand issued Jan. 1, 1980, teaches that graft copolymers of vinyl compounds are useful as viscosity index modifiers.

U.S. Pat. No. 4,63,159 issued April 1981 to Berens et al teaches that certain aliphatic polyol compounds reacted with branched monocarboxylic acid form esters useful in automatic transmission fluids.

None of these materials shown to be useful as viscosity index modifiers are as effective as the highly branched ether esters taught by the current invention.

There are several factors known about liquidity in esters. When made to a given molecular weight, the highest viscosity esters are those derived from saturated linear alcohols. This class of compounds also exhibit a wide change in viscosity as a function of temperature. It is for these reasons that esters derived from saturated linear alcohols are least desirable as viscosity index modifiers.

Pentaerythritol, a highly branched four hydroxyl group containing alcohol is sometimes used to obtain an improvement in viscosity over saturated alcohols. The improvement is only partial and there are difficulties in controlling the reaction if less than four equivalents of acid is added.

The next improvement is to base the ester upon oxo alcohols. Oxo alcohols are well known to those skilled in the art. They contain about 20-30% branching at the alpha position. The branching is methyl. Esters derived from this type of raw material are the more liquid than esters derived from saturated linear alcohols if the esters have the same molecular weight.

Finally, esters based upon guerbet alcohols are the most liquid of the groups discussed. There are many references to the use of gurebet alcohols to make esters for use in a variety of lubricating applications. The useful property of guerbet alcohols in lubricating applications is the beta branch and the liquidity it renders.

Guerbet Alcohols are known materials which have a high degree of regiospecific beta branching. They have been known since the 1890's when Marcel Guerbet first synthesized them. (M. Guerbet, C. R. Acad. Sci. Paris, 128, 511; 1002 (1899)). These materials are high in molecular weight and are liquid to very low temperatures. The guerbet reaction gives very specific branching in the alcohol as shown; ##STR1##

As can be seen by the above reaction the molecules have substitution on the second carbon from the hydroxyl group. This branching has been found to be critical to the preparation of a product having the desired lubrication and oxidative stability properties. If the branching were on the same carbon as the hydroxyl group, the hydroxyl group would be a secondary one and would be very hindered and has low reactivity. As one moves the branch position away from the beta carbon, the liquidity, lubricity and metal substantivity decreases. If the branch is lower alkyl like methyl in some oxo alcohols, there is little increase in the liquidity, lubricity and metal substantivity over normal alcohols having the same number of carbons. Additionally, the oxo process gives only some beta branching (between 1 and 28%) the guerbet process gives essentially 100% product.

U.S. Pat. No. 4,425,458 issued January 1984 to Lindner et al teaches that certain diesters of guerbet alcohols are useful as lubricants in polycarbonate applications. Additionally, U.S. Pat. No. 4,767,815 issued August 1988, to O'Lenick teaches that certain guerbet ether esters are likewise useful as polycarbonate lubricants.

U.S. Pat. No. 4,800,077 issued January 1989, to O'Lenick et al teaches that guerbet alcohols can be used to prepare certain conditioning quaternary compounds.

U.S. Pat. No. 4,868,236 issued September 1989, to O'Lenick teaches that certain guerbet alcohol citrate esters are useful in plastic lubrication.

U.S. Pat. Nos. 4,731,190 and 4,830,769 both to O'Lenick teaches that certain alkoxylate esters are useful as lubricants useful in facilitating the working of metal. Guerbet alcohol derived esters have not enjoyed widespread acceptance in viscosity index modification applications.

Surprisingly, the compounds of the present invention are superior to esters of guerbet alcohols of the same molecular weight. Hence they are very useful as viscosity index modifiers.

OBJECT OF THE INVENTION

It is the object of the present invention to provide a series of novel branched ether esters, which have very low viscosities over a range of temperatures. These materials are very effective viscosity index modifiers.

THE INVENTION

The present invention relates to a particular group of high molecular weight beta branched internal ether esters which are derived from high molecular weight internal branched ether alcohols. These compounds have one alkyl group and one ether alkyl group branch which differentiates our esters from esters derived from guerbet alcohols. Guerbet alcohols have two alkyl branches derivatives in the beta position. The presence of the ether function has a profound effect upon viscosity of the ester and consistency of viscosity as a function of temperature. The unique ether beta branch also differentiates our esters from esters derived from oxo alcohols. Oxo alcohols have no ether group. The position of the branched ether group also distinguishes these materials from alkoxylated fatty alcohol esters. The latter has the ether linkage on the terminal portion of the molecule and has a lower alkyl group between the oxygen groups.

R--(--O--CH.sub.2 --CH(CH.sub.3))x--OH R--(--O--CH.sub.2 --CH.sub.2 --)x--OH An additional aspect of the invention is the surprising efficiency of these branched ether esters as viscosity index modifiers. ##STR2## It will be understood by those skilled in the art that the above definition or R' and R" will also include several other positional isomers.

The compounds of the current invention are the esterification product of a new series of branched ether alcohols and their alkoxylates recently developed by Nova Molecular Technologies Lake Geneva Wi.

The alcohols, marketed under the trade name "Aldol Alcohol" and conform to the following structure; ##STR3##

R' is ##STR4##

R" is ##STR5##

R.sup.3 is hydrogen or lower alkyl;

EO is --(CH.sub.2 CH.sub.2 --O)--

PO is --(CH.sub.2 CH(CH.sub.3)--O)--

x, y and z are independently integers from 0 to 20;

m is an integer from 0 to 5;

n is an integer from 0 to 5.

______________________________________Name n m x y z______________________________________ALDOL ALCOHOL 21 1 1 0 0 0ALDOL ALCOHOL 27 2 2 0 0 0ALDOL ALCOHOL 21-E3 1 1 3 0 0ALDOL ALCOHOL 21-E5 1 1 5 0 0ALDOL ALCOHOL 21-E15 1 1 15 0 0ALDOL ALCOHOL 21-E20 1 1 20 0 0ALDOL ALCOHOL 2 2 0 20 2027-P20-E20ALDOL ALCOHOL 2 2 10 10 027-E10-P10ALDOL ALCOHOL 2 2 5 4 027-E5-P4ALDOL ALCOHOL 2 2 20 0 027-E20______________________________________

We have learned that esters derived from these alcohols make outstanding viscosity index modifiers. In one embodiment the compounds of the current invention, are monoesters and conform to the following structure;

R--C(O)--R wherein R.sup.1 is; ##STR6##

R' is ##STR7##

R" is ##STR8##

R.sup.3 is hydrogen or lower alkyl;

EO is --(CH.sub.2 CH.sub.2 --O)--

PO is --(CH.sub.2 CH(CH.sub.3)--O)--

x, y and z are independently integers from 0 to 20;

m is an integer from 0 to 5;

n is an integer from 0 to 5.

R is alkyl having between 6 and 20 carbon atoms.

In another embodiment the compounds of the current invention are diesters of these internal branched ether alcohols and conform to the following structure;

R.sup.1 --R.sup.2 --R.sup.1 wherein R.sup.1 is;

R.sup.2 is selected from; ##STR9##

p has a value from 1 to 15;

m and o independently range from 0 to 5;

n is 1 or 3.

In a final embodiment the compounds of the current invention are triesters and conform to the following structure; ##STR10## wherein R.sup.1 is; ##STR11##

R' is ##STR12##

R" is ##STR13##

R.sup.3 is hydrogen or lower alkyl;

EO is --(CH.sub.2 CH.sub.2 --O)--

PO is --(CH.sub.2 CH(CH.sub.3)--O--

x, y and z are independently integers from 0 to 20;

m is an integer from 0 to 5;

n is an integer from 0 to 5.

The high molecular weight and the presence an internal branched ether linkage on the alcohol backbone of the compounds of the present invention, make these materials unique in their structure and in their performance properties as viscosity index modifiers.

These alcohols are esterified with fatty acids, citric acid or diacids, using known methods, to give the esters of the present invention.

______________________________________ Nova Name______________________________________Raw Material AlcoholsExample #1 ALDOL ALCOHOL 21Example #2 ALDOL ALCOHOL 27Example #3 ALDOL ALCOHOL 21-E3Example #4 ALDOL ALCOHOL 21-E5Example #5 ALDOL ALCOHOL 21-E15Example #6 ALDOL ALCOHOL 21-E20Example #7 ALDOL ALCOHOL 27-P20-E20Example #8 ALDOL ALCOHOL 27-E10-P10Example #9 ALDOL ALCOHOL 27-E5-P4Example #10 ALDOL ALCOHOL 27-E20Suitable Acid Raw MaterialsTallow Acid Mixture of C18 and C16Lauric Acid C.sub.12 H.sub.26 O.sub.2Myristic Acid C.sub.14 H.sub.30 O.sub.2Palmitic Acid C.sub.16 H.sub.34 O.sub.2Stearic Acid C.sub.18 H.sub.38 O.sub.2Caprylic Acid C.sub.8 H.sub.18 O.sub.2Suitable Diacid Raw MaterialsAdipic Acid HO(O)C(CH.sub.2).sub.4 C(O)OHSuccinic Acid HO(O)C(CH.sub.2).sub.2 C(O)OHDodecanedioic Acid HO(O)C(CH.sub.2).sub.10 C(O)OHMalic Acid HO(O)CCHCHC(O)OHMalonic Acid HO(O)C(CH.sub.2).sub.3 C(O)OHAzelaic Acid HO(O)C(CH.sub.2).sub.5 C(O)OHSuitable Triacid Raw MaterialsCitric Acid ##STR14##______________________________________

EXAMPLES

General Procedure

In a suitable reaction vessel is added the specified Nova ALDOL ALCOHOL (example 1-10). The specified amount of the acid, is then added under good agitation. Next, between 0.1 and 0.5% of an esterification catalyst is added. Begin to heat. The reaction starts as the temperature reaches 140 degrees C. Continue to heat to 200 degrees C. and apply vacuum as the rate of distillation slows. A minimum of 97% of the theoretical water is removed before proceeding. Apply vacuum as the rate of distillation slows. A minimum of 97% of the theoretical water is removed, giving the desired product.

EXAMPLE #11

In a suitable reaction vessel is added 329.0 grams of Nova ALDOL ALCOHOL 21 (example 1), 275.0 grams of tallow fatty acid, under good agitation and nitrogen sparge. Next, add 1.0 gram of stannous oxylate, an esterification catalyst. Begin to heat. The reaction begins as the temperature reaches 140 degrees C. Continue to heat to 200 degrees C. and apply vacuum as the rate of distillation slows. A minimum of 97% of the theoretical water is removed before proceeding. Apply vacuum as the rate of distillation slows. The product is used without additional purification.

EXAMPLES 12-13

Example 11 is repeated, however this time the specified amount of the specified type of acid replaces the tallow acid and the specified amount and type of ALDOL ALCOHOL is used.

______________________________________Example ALDOL ALCOHOL Fatty AcidNumber Type Grams Type Grams______________________________________12 Example 1 329.0 Tallow Acid 286.013 Example 1 329.0 Lauric Acid 202.014 Example 1 329.0 Myristic Acid 230.015 Example 1 329.0 Palmitic Acid 258.016 Example 1 329.0 Stearic Acid 286.017 Example 1 329.0 Caprylic Acid 146.018 Example 1 329.0 Adipic Acid 73.019 Example 1 329.0 Succinic Acid 59.020 Example 1 329.0 Dodecanedioic 115.0 Acid21 Example 1 329.0 Malic Acid 58.022 Example 1 329.0 Malonic Acid 66.023 Example 1 329.0 Azelaic Acid 80.024 Example 1 329.0 Citric Acid 64.325 Example 2 411.0 Tallow Acid 275.026 Example 2 411.0 Lauric Acid 202.027 Example 2 411.0 Myristic Acid 230.028 Example 2 411.0 Palmitic Acid 258.029 Example 2 411.0 Stearic Acid 286.030 Example 2 411.0 Caprylic Acid 146.031 Example 2 411.0 Adipic Acid 73.032 Example 2 411.0 Succinic Acid 59.033 Example 2 411.0 Dodecanedioic 115.0 Acid34 Example 2 411.0 Malic Acid 58.035 Example 2 411.0 Citric Acid 64.336 Example 3 461.0 Tallow Acid 275.037 Example 3 461.0 Lauric Acid 202.038 Example 3 461.0 Palmitic Acid 258.039 Example 3 461.0 Stearic Acid 286.040 Example 3 461.0 Succinic Acid 59.041 Example 3 461.0 Dodecanedioic 115.0 Acid42 Example 3 461.0 Malonic Acid 66.043 Example 3 461.0 Citric Acid 63.444 Example 4 668.2 Lauric Acid 202.045 Example 4 668.2 Myristic Acid 230.046 Example 4 668.2 Palmitic Acid 258.047 Example 4 668.2 Stearic Acid 286.048 Example 4 668.2 Caprylic Acid 146.049 Example 4 668.2 Adipic Acid 73.050 Example 4 668.2 Succinic Acid 59.051 Example 4 668.2 Dodecanedioic 115.0 Acid52 Example 4 668.2 Malic Acid 58.053 Example 4 668.2 Malonic Acid 66.054 Example 4 668.2 Azelaic Acid 80.055 Example 4 668.2 Citric Acid 63.456 Example 5 989.1 Tallow Acid 275.057 Example 5 989.1 Lauric Acid 202.058 Example 5 989.1 Myristic Acid 230.059 Example 5 989.1 Palmitic Acid 258.060 Example 5 989.1 Stearic Acid 286.061 Example 5 989.1 Caprylic Acid 146.062 Example 5 989.1 Adipic Acid 73.063 Example 5 989.1 Succinic Acid 59.064 Example 5 989.1 Dodecanedioic 115.0 Acid65 Example 5 989.1 Malic Acid 58.066 Example 5 989.1 Malonic Acid 66.067 Example 5 989.1 Azelaic Acid 80.068 Example 5 989.1 Citric Acid 63.469 Example 6 1209.0 Tallow Acid 275.070 Example 6 1209.0 Lauric Acid 202.071 Example 6 1209.0 Myristic Acid 230.072 Example 6 1209.0 Palmitic Acid 258.073 Example 6 1209.0 Stearic Acid 286.074 Example 6 1209.0 Caprylic Acid 146.075 Example 6 1209.0 Adipic Acid 73.076 Example 6 1209.0 Succinic Acid 59.077 Example 6 1209.0 Dodecanedioic 115.0 Acid78 Example 6 1209.0 Malic Acid 58.079 Example 6 1209.0 Malonic Acid 66.080 Example 6 1209.0 Azelaic Acid 80.081 Example 6 1209.0 Citric Acid 63.482 Example 7 2471.2 Tallow Acid 275.083 Example 7 2471.2 Lauric Acid 202.084 Example 7 2471.2 Myristic Acid 230.085 Example 7 2471.2 Palmitic Acid 258.086 Example 7 2471.2 Stearic Acid 286.087 Example 7 2471.2 Caprylic Acid 146.088 Example 7 2471.2 Adipic Acid 73.089 Example 7 2471.2 Succinic Acid 59.090 Example 7 2471.2 Dodecanedioic 115.0 Acid91 Example 7 2471.2 Malic Acid 58.092 Example 7 2471.2 Malonic Acid 66.093 Example 7 2471.2 Azelaic Acid 80.094 Example 7 2471.2 Citric Acid 63.495 Example 8 1441.0 Tallow Acid 275.096 Example 8 1441.0 Lauric Acid 202.097 Example 8 1441.0 Myristic Acid 230.098 Example 8 1441.0 Palmitic Acid 258.099 Example 8 1441.0 Stearic Acid 286.0100 Example 8 1441.0 Caprylic Acid 146.0101 Example 8 1441.0 Adipic Acid 73.0102 Example 8 1441.0 Succinic Acid 59.0103 Example 8 1441.0 Dodecanedioic 115.0 Acid104 Example 8 1441.0 Malic Acid 58.0105 Example 8 1441.0 Malonic Acid 66.0106 Example 8 1441.0 Azelaic Acid 80.0107 Example 8 1441.0 Citric Acid 63.4108 Example 9 867.0 Tallow Acid 275.0109 Example 9 867.0 Lauric Acid 202.0110 Example 9 867.0 Myristic Acid 230.0111 Example 9 867.0 Palmitic Acid 258.0112 Example 9 867.0 Stearic Acid 286.0113 Example 9 867.0 Caprylic Acid 146.0114 Example 9 867.0 Adipic Acid 73.0115 Example 9 867.0 Succinic Acid 59.0116 Example 9 867.0 Dodecanedioic 115.0 Acid117 Example 9 867.0 Malic Acid 58.0118 Example 9 867.0 Malonic Acid 66.0119 Example 9 867.0 Azelaic Acid 80.0120 Example 9 867.0 Citric Acid 63.4121 Example 10 1291.0 Tallow Acid 275.0122 Example 10 1291.0 Lauric Acid 202.0123 Example 10 1291.0 Myristic Acid 230.0124 Example 10 1291.0 Palmitic Acid 258.0125 Example 10 1291.0 Stearic Acid 286.0126 Example 10 1291.0 Caprylic Acid 146.0127 Example 10 1291.0 Adipic Acid 73.0128 Example 10 1291.0 Succinic Acid 59.0129 Example 10 1291.0 Dodecanedioic 115.0 Acid130 Example 10 1291.0 Malic Acid 58.0131 Example 10 1291.0 Malonic Acid 66.0132 Example 10 1291.0 Azelaic Acid 80.0133 Example 10 1291.0 Citric Acid 63.4______________________________________

APPLICATION EXAMPLES

We have evaluated the initial viscosity as well as viscosity variation as a function of temperature of several of the esters of the present invention and several other esters for comparison to the compounds of the present invention.

The following data shows the viscosity effect as a function of temperature. We have chosen products based upon the guerbet alcohol, and the same ester type based upon the branched aldol ether alcohols disclosed. Compounds based upon linear alcohols of compared molecular weight (i.e. stearic) would have been solid. This shows the critical nature of the internal location of the branched ether linkage to liquidity.

This data below shows viscosity of various esters (in centistokes) as a function of temperature (in degrees C.).

______________________________________Material 5 C 10 C 20 C 30 C______________________________________TriestersGuerbet (20 Citrate) 4,392 2,600 1134 673Tridecyl Citrate 1,300 500 350 220Example #24 350 108 74 25Example #35 425 160 91 40Example #43 300 80 60 20Stearyl (4EO) Citrate Solid Solid Solid SolidStearyl (4PO) Citrate Solid Solid Solid SolidStearyl Citrate Solid Solid Solid SolidDiestersGuerbet (20) Dodeacanedioic 300 170 70Example #20 150 80 30Example #33 200 110 50Example #41 100 50 26Stearyl (4EO) Dodecanedioic Solid Solid SolidStearyl (4PO) Dodecanedioic Solid Solid SolidStearyl Dodecanedioic Solid Solid SolidMonoestersGuerbet (20) Tallowate 320 190 57.5Example #12 150 100 25.6Example #25 175 125 46.0Example #36 130 90 20.0Stearyl (4EO) Tallowate Solid Solid SolidStearyl (4PO) Tallowate Solid Solid SolidStearyl Tallowate Solid Solid Solid______________________________________

The low viscosity over a wide range of temperatures is one of the most important reasons why the compounds of the present invention are outstanding viscosity index modifiers.

Claims

1. A branched ether ester conforming to the following formula;

R--C(O)--R.sup.1

wherein R.sup.1 is; ##STR15## R' is ##STR16## R" is ##STR17## R.sup.3 is selected from hydrogen or methyl; EO is --(CH.sub.2 CH.sub.2 --O)--

PO is --(CH.sub.2 CH(CH.sub.3)--O)--

x, y and z are independently integers from 0 to 20;

m is an integer from 0 to 5;

n is an integer from 0 to 5;

R is alkyl having between 6 and 20 carbon atoms.

2. A compound of claim 1, wherein R is alkyl having between 12 and 18 carbon atoms.

3. A compound of claim 1, wherein R is alkyl having 18 carbon atoms.

4. A compound of claim 1, wherein x, y and z are all zero.

5. A branched ether ester conforming to the following formula;

R.sup.1 --R.sup.2 --R.sup.1

wherein R.sup.1 is; ##STR18## R' is ##STR19## R" is ##STR20## R.sup.3 is selected from hydrogen or methyl; EO is --(CH.sub.2 CH.sub.2 --O)--

PO is --(CH.sub.2 CH(CH.sub.3)--O)--

x, y, and z, are independently integers from 0 to 20;

R.sup.2 is selected from; ##STR21## p has a value from 1 to 15; m and o independently range from 0 to 5;

n is 1 or 3.

6. A compound of claim 5, wherein R is alkyl having between 12 and 18 carbon atoms.

7. A compound of claim 6, wherein R is alkyl having 18 carbon atoms.

8. A compound of claim 6, wherein

R.sup.2 is; ##STR22## p has a value from 1 to 15.

9. A compound of claim 6, wherein

R.sup.2 is; ##STR23## m and o independently range from 0 to 5.

10. An branched ether ester conforming to the following formula; ##STR24## wherein R.sup.1 is; ##STR25## R' is ##STR26## R" is ##STR27## R.sup.3 is selected from hydrogen or methyl; EO is --(CH.sub.2 CH.sub.2 --O)--

PO is --(CH.sub.2 CH(CH.sub.3)--O)--

x, y and z are independently integers from 0 to 20;

m is an integer from 0 to 5;

n is and integer from 0 to 5.

11. A compound of claim 10 wherein x, y and z are all zero.

12. A compound of claim 10 wherein x, y and z independently range from 1 to 5.

13. A compound of claim 10 wherein m and n are independently integers ranging from 1 to 3.

14. A compound of claim 10 wherein m and n are each 1.

15. A compound of claim 10 wherein m and n are each 0.