CA1081681A

CA1081681A - Polymeric additives for fuels and lubricants

Info

Publication number: CA1081681A
Application number: CA255,156A
Authority: CA
Inventors: Lawrence J. Engel; John B. Gardiner
Original assignee: Exxon Research and Engineering Co
Current assignee: ExxonMobil Technology and Engineering Co
Priority date: 1975-06-25
Filing date: 1976-06-17
Publication date: 1980-07-15
Also published as: AU498559B2; NL7606896A; AU1460576A; AR226408A1; GB1554947A; BE843360A; FR2315519B1; JPS524507A; US4089794A; JPS6018712B2; NL191023C; FR2315519A1; BR7603998A; DE2627785A1; IT1061434B; DE2627785C2; NL191023B

Abstract

ABSTRACT OF DISCLOSURE
Ethylene copolymers derived from about 2 to 98 wt. % ethylene, and one or more C3 to C28 alpha olefins, e.g. conylene-propylene, are solution grafted under an inert atmosphere and at elevated temperatures with an ethylenically-unsaturated carboxylic acid material in the presence of a high-temperature decomposable free-radical initiator and thereafter reacted with a polyfunctional material reactive with carboxyl groups; such as (a) a polyamine or (b) a polyol, or (c) a hydroxy-amine, or mixtures thereof to form carboxyl-grafted polymeric derivatives, which have good engine sludge and varnish control behavior in fuels and lubricating oils. If the molecular weight is above 10,000, then these polymers are also useful as multifunctional viscosity index improvers.

Description

1 This invention relates to polymeric dispersant

2 additives for lubricating oils and hydrocarbon fuels which

3 may also be useful as viscosity-index improvers for lubri-

4 cating oils. More particularly, this invention relates to substantially saturated polymers compris~ng ethylene and 6 one or more C3 to c2g alpha-olefins, preferably propyleneJ
7 which have been solution-grafted in the presence of a free-radical initiator with an ethylenically-unsaturated carboxy-9 lic acid material at an elevated temperature, preferably in lo an inert atmosphere, and thereafter reacted with a poly-11 functional material reactive with carboxy groups, such as 12 (a) a polyamine, (b) a polyol or (c) a hydroxy amine, or 3 mixtures thereof, to form multifunctional polymeric reaction products.
A variety of polymeric materials which incorporate 16 nitrogen and/or oxygen have been described in U.S. and for-17 eign patents as dispersants for fuels and lubricants and as 18 viscosity index improvers for lubricants. For example:
19 U.S. Patent 3,326,804 improves the sludge disper-sant properties of oleaginous compositions by adding thereto 21 the reaction product of a polyalkylene polyamine with the 22 product obtained by grafting maleic anhydride onto hydroper-23 oxidized ethylene copolymer.
24 U.S. Patent 3,404,091 grafts polar monomers, such as acrylonitrile or methylacrylamide, onto hydroperoxidized 26 copolymers of ethylene and propylene to produce multifunc-27 tional additives.
28 U.S. Patent 3,404,092 reacts hydroxylated ethylene-29 propylene copolymers with isocyanates to produce viscosity index improvers exhibiting improved thickening potencies and , 10 8 1 ~ ~1 shear stabilities in petroleum oils.
U.S. Patent 3,687,849 grafts various unsaturated monomers including unsaturated polybasic acids, including maleic anhydride, onto a degraded, hydroperoxidized, inter-polymers of ethylene and propylene (see also U.S. Patents 3,388,067, 3,687,9Q5 and 3,785,980).
U.S. 3,769,216 shows an atactic (i.e., non-crystal-line) copolymer of ethylene and propylene containing from 45 to 65 mole percent of ethylene, mechanically degraded in the lo presence of oxygen followed by reaction with a polyamine.
British Patent 1,031,130 discloses an additive pre-pared by reacting a polyolefin carrying a succinic acid group with a hydroxy aliphatic amine, said succinic acid group having been incorporated onto a polyolefin having several double bonds or several halogen atoms to provide for the formation of said double bonds. British Pat~nt 1,172,818 describes the preparation of lube oil additives by the con-densation of an amine with an oxidized, e.g., ozonized, polymer.
It is also known to graft ethylenically unsaturated carboxylic acid material, e.g. maleic anhydride, onto satur-ated ethylene copolymers and terpolymers in the presence of a free-radical initiator, such as an organic peroxide. The grafting can be done in the presence of a solvent, such as benzene and low-molecular weight paraffins (see Belgian Patent 607,269) and halobenzenes (see U.S. Patent 3,255,130).
This grafting has also been done at temperatures of from :, ~ 81 1 150C. to 200C. without a solvent (see U.S. Patent 2 3,427,183). Such maleic anhydride, free-radical initiated 3 grafted ethylene polymeric materials have also been subse-4 quently reacted with polyfunctional compounds capable of pro-moting cross linkages between the various polymeric chains, 6 e.g., metallic oxides and hydroxides, glycols and diamine~
7 (see U.K. Patent 885,969 and U.S. Patent 3,236,917).
8 In contrast to the above-noted prior art, it has 9 been discovered that it i8 possible to produce an oil-soluble, sludge-dispersing additive for hydrocarbon fuels 11 and lubricating oils, wh~ch additive may also improve the 12 viscosity index of said lubricating oils9 by the free-radical 13 induced grafting in solution of an ethylenically-unsaturated 14 dicarboxylic acid material onto a substantially saturated copolymer comprising ethylene and at least one other alpha-16 olefin at an elevated temperature to provide9 without sub-17 stantial polymer degradation~ a useful precursor polymer 18 which can be subsequently reacted with a carboxylic acid-19 reacting polyfunctional material9 such as a polyamine, a polyol or a hydroxyamine,or mixtures of these,to form ~lti-21 functional polymeric derivatives having particular utility 22 a8 engine sludge and varnish control additives for lubricat-23 ing oils.
24 I me EthYlene CoPol~mer 2s The ethylene copolymers to be grafted in accord-26 ance with this invention contain from about 2 to about 98, 27 preferably 30 to 80 wt. % of ethylene, and about 2 to 98, 28 preferably 20 to 70, wt. 70 of one or More C3 to C2g, prefer-29 ably C3 to Clgg more preferably C3 to Cg, alpha-olefins.
Such copolymers preferably have a degree of crystallinity of less than 25 wt. %, as determined by X-ray and differential 2 scanning calorimetry, and a number average molecular weight 3 (~In) in the range of abou~ 700 to about 500,000, preferably 4 700 to 250,000, as determined by vapor phase osmometry (VPO) or membrane osmometry. Copolymers of ethylene and propylene 6 are most preferred. Other alpha-olefins suitable in place 7 of propylene to form the copolymer or to be used in combil a-8 tion with ethylene and propylene to form a terpolymer in-g clude l-butene, l-pentene, l-hexene, l-octene; also branched 10 chain alpha-olefins, such as 5-methylpentene-1 and 6-methyl-11 heptene-l and mixtures thereof.
12 Terpolymers o ethylene, said alpha-olefin and a 13 non-con~ugated diolefin or mixtures of such diolefins may 14 also be used. The amount of the non-con~ugated diolefin 15 ranges from about 0.5 to 20 mole percent, preferably about 1 16 to about 7 mole percent, based on the total amount of ethyl-17 ene and alpha-olefin present. Representative diolefins in-18 clude cyclopentadiene, 2-methylene-5-norbornene, non-con~u-19 gated hexadiene, or any other alicyclic or aliphatic noncon-20 ~ugated diolefin having from 6 to 15 carbon atoms per mole-21 cule, such as 2-methyl or ethyl norbornadiene, 2,4-dimethyl-22 2-octadiene, 3-(2-methyl-1-propene) cyclopentene, ethylidene 23 norbornene, etc.
24 These ethylene copolymers, this term including 25 terpolymers, may be prepared using the well-l~nown Ziegler-26 Natta catalyst compositions as described in U.K. Patent 27 1,397,994.
28 Such polymerization may be effected to produce the 29 ethylene copolymers by passing 0.1 to 15, for example, 5 30 parts of ethylene; 0.05 to 10, for example, Z.5 parts of :, - .. . .

said higher alpha-olefin, typically propylene; and from lO
2 to lO,000 parts of hydrogen per million part~ of ethylene;
3 into lO0 parts of an inert liquid solvent containing (a) 4 from about 0.0017 to 0.017, for example, 0.0086 parts of a transition metal principal catalyst, for example, VOCl3; and 6 (b) from about 0.0084 to 0.084, for example, 0.042 parts of 7 cocatalyst, e.g. (C2Hs)3Al~Cl3; at a temperature of about 8 25C. and a pressure of 60 psig for a period of time suffi-9 cient to effect optimum conversion, for example, 15 minutes to one-half hour; all parts being parts by weight.
11 II. EthYlenically Unsaturated Carbox~rlic l~cid Materials 12 l~ese materials which are grafted (attached) onto 13 the copolymer are organic compounds which contain at least 14 one ethylenic bond and at least two carboxylic acid or its anhydride groups or a polar group which is convertible into 16 said carboxyl groups by oxidation or hydrolysis. Maleic an-17 hydride or a derivative thereof is preferred as it does not 18 appear to homopolymerize appreciably but grafts onto the 19 ethylene copolymer or terpolymer to give two carboxylic acid 20 functionalities. Such preferred materials have the generic 21 formula 22 ll 12 X
26 wherein Rl ~nd R2 are hydrogen or a halogen and X is oxygen, 27 NH or ~R3 wherein R3 is a hydrocarbyl amine or alkyl group9 28 e.g. a Cl to C40 alkyl, preferably Cl to Cl8 alkyl. Suit-29 able examples include chloromaleic anhydride, itaconic an-30 hydride, N-hexyl maleimide or the corresponding diearboxylic ~8 i ~

1 acids, such as maleic acid or fumaric acid.
2 III. Graftin~ of the Polymer 3 me free-rsdical induced grafting of ethylenical-4 ly unsaturated carboxylic acid materials in solvents, such as benzene is known in the art (U.S. Patent 3,236,917).
6 m e grafting according to the process of this invention is 7 carried out at an elevated temperature in the range of 8 about 100C. to 250C., preferably 120 to 190C., and more 9 preferably 150 to 180C., e.g. above 160C., in a solvent, 0 preferably a mineral lubricating oil solution containing, e.g. l to 50, preferably 5 to 30 wt. %, based on the initial 2 total oil solution,of the ethylene polymer and preferably 13 under an inert environment. The grafting is carried out in 14 the presence of a high-temperature decomposable compound capable of supplying free radicals at said elevated tempera-16 ture.
17 The free-radical initiators which may be used are 8 peroxides, hydroperoxides, and azo compounds which have a 19 boiling point greater than about 100C. and decompose ther-mally within the grafting temperature range to provide said 21 free radicals. Representative of these free-radical initia-22 tors are azobutyronitrile and 2,5-dimethyl-hex-3-yne-2,5 23 bis-tertiary-butyl peroxide, sold as Lupersol 130 by Wallace 24 and Tiernan, Inc., or its hexene analogue. The initiator is 2s used at a level of between about 0.005% and about 1%, based 26 on the total weight of the polymer solution.
27 The ethylenically unsaturated dicarboxylic acid 28 material, e.g. maleic anhydride, is used in an amount rang-29 ing from about 0.01% to about 10%, preferably O.l to 0.8%, ~ based on the weight of the initial total oil solution. The 1 aforesaid dicarboxylic acid material and free radical ini-2 tiator are used in a weight percent ratio range of l.O:l to 3 30:1; preferably 2.0:1 to 5:0, more pre~erably 2.0:1 to 4 2.6:1. m ese ratios are the optimum ranges when using Lupersol 130. If other ~nitiators are used, then the ratio 6 should preferably be altered to give the same approximate 7 number of moles of free radicals as with Lupersol 130 8 (which forms 4 moles free radicals per mole initiator).
9 The grafting is preferably carried out in an inert 0 atmosphere, such as by nitrogen blanketing. While the grafting can be carried out in the presence of air, the 2 yield of the desired graft polymer is decrea~ed as compared 13 to grafting under an inert atmosphere. The inert environ-4 ment, which is preferred, should be free of oxygen, that is, preferably no substantial polymer oxidation should ocour 16 during the free-radical induced grafting of the polymer. No 7 substantial oxidation is defined for the purposes of this 8 invention as the introduction of le89 than about 0.05 wt. %, 19 preferably le~s than about O.Ol wt. %, of oxygen into the grafted polymer excluding that introduced by the graft of 21 said carboxylic acid material. The grafting time ranges 22 from about O.l to 12 hours, preferably from about 0.5 to 6 23 hours, more preferably 0.5 to 3 hours. The graft reaction ; 24 i8 carried out to at least approximately 4 times, preferably at least about 6 times the half-life of the free-radical ini-26 tiator at the reaction ~emperature employed. Thus, for 27 example, with Lupersol 130 about 2 hours is required at 28 160C. and one hour at 170C. Lupersol 130 has a boiling 29 point of about 243C. (extrapolated from ~he vapor pressure);
its half-life at 160C. is 20 minutes, at 170C. it is 8 .

~)tBl~

1 minutes and at 180C. it is 3 minutes. The time and tempera-2 ture combination should be such that substantially all the 3 peroxide (i.e. above 90~h) i8 decomposed.
4 In the grafting process, the copolymer solution is

5 first heated to grafting temperature and thereafter said di-

6 carboxylic acid material and initiator are added with agita-

7 tion although they could have been added prior to heat~ng.

8 When the reaction is complete, the excess maleic anhydride

9 is eliminated by an inert gas purge, e.g. nitrogen sparging.
In the grafting step, the maleic anhydride or 11 other dicarboxylic acid material used is grafted onto both 12 the polymer and oil reaction solvent~ the wt. % grafted onto 13 the polymer is normally greater than the amount grafted onto 14 the oil due to greater reactivity of the polymer to grafting.
However, the exact split between the two materials depends 6 upon the polymer and its reactivity, the reactivity and type 17 of oil, and also the concentration of the polymer in the oil.
18 me split can be measured empirically from the infra red 19 analyses of product dialyzed into oil and polymer fractions and measuring the anhydride peak absorbance in each.
21 The grafting is preferably carried out in a mineral 22 lubricating oil which need not be removed after the grafting 23 step but can be used as the solvent in the subsequent reac-24 tion of the graft polymer with the polyfunctional material and as a solvent for the end product to form the concentrate.
26 IV. Polyamines 27 ~seful polyamines for reaction with the grafted 28 ethylene-containing polymers include polyamines of about 2 to 29 60, e.g., 3 to 20, total carbon atoms and about 2 eo 12, e.g.
2 ~o 6 nitrogen atoms in ~he molecule, which amines may be 81~81 hydrocarbyl polyamines or may be hydrocarbyl polyamines in-2 cluding other groups, e.g., hydroxy groups, alkoxy groups, 3 amide groups, imidazoline groups, and the like. Preferred 4 amines are aliphatic saturated polyamines, including those of the general formula:
6 R-N-(cH2)s ~-- N-(CH2)S--1 N R
7 R' L H Jt R
8 wherein R and R' are independently selected from the group 9 consisting of hydrogen, Cl to C25 straight or branched chain 0 alkyl radicals, Cl to C12 alkoxy C2 to C6 alkylene radicals, C2 to C12 hydroxy or amino alkylene radicals, and Cl to C12 12 alkylamino C2 to C6 alkylene radicals, s is a number of from 13 2 to 6, preferably 2 to 4, and t is a number of from O to 10, ~
14 prefera~ly 2 to 6. ~ ~ -Examples of suitable amine compounds include di-16 tallow amine, 1,2-diaminoethane, 1,3-diaminopropane, 1,4-17 diaminobutane, 1,6-diaminohexane, diethylene triamine, tri-18 ethylene tetraamine, tetraethylene pentamine, 1,2-propylene 19 diamine, di-(1,2-propylene) triamine, di-(1,3-propylene) 20 triamine, N,N-dimethyl-1,3-diaminopropane, N,N-di-(2-amino~
21 ethyl)ethylene diamine3 N,N-di-(2-hydroxyethyl)-1,3-propyl-22 ene diamine, and N-dodecyl~1,3-propane diamine.
23 Other useful amine compounds include alicyclic di-24 amines such as 1,4-di-(aminomethyl) cyclohexane, and hetero-25 cyclic nitrogen compounds such as imidazolines and N-amino-26 alkyl piperazines of the general formula:

. /
28 NH2-(cH2)p - N\ N-G

30 wherein G is hydrogen or an omega-aminoalkylene radical of

- 10 -1 0 ~ 1 ~8 1 1 from l to 3 carbon atoms and p is an integer o~ from l to 4.
2 Examples of such amines include 2-pentadecyl imidazoline, 3 N-(2-aminoethyl) piperazine, N-(3-aminopropyl) piperazine, 4 and N,N'-di-(2-aminoethyl) piperazine. Amino morpholines, such as N-(3-aminopropyl) morpholine can also be used.
6 Commercial mixtures of amine compounds may advan-7 tageously be used. For example, one process for preparing 8 alkylene amines involves the reaction of an alkylene di-9 halide (such as ethylene dichloride or propylene dichloride) with ammonia, which results in a complex mixture of alkyl-

11 ene groups, forming such compounds as diethylene triamine,

12 triethylenetetramine, tetraethylene pentamine and isomeric piperazines. Low cost poly (ethylene amines) compounds hav-ing a composition approximating ~etraethylene pentamine are available commercially under the trade name Polyamine 400.
16 Still other polyamines separated by hetero atom chains such 17 as polyethers or sulfides can be used.
18 V. ~ ls 19 UseEul polyols for reaction with the grafted ethyl-ene-containing polymers are polyhydric, preferably hydro-21 carbyl, alcohols containing from about 2 to about 30, pre-22 ferably 2 to 6, carbon atoms and from about 2 to about lO, 23 preferably 2 to 5, hydroxyl radicals; for example, glycerol, 24 alkylene glycols such as dipropylene glycol, trimethylol etha~e, trimethylol propane, and pentaerythritol which is 26 preferred.
27 VI. Hydroxy Amines 28 Useful hydroxy amines for reaction with the grafxd 29 ethylene-containing polymer are pr~mary and secondary amines having 2 to 30 carbon atoms~ preferably 2 to 6 carbon atoms, ~ 81 ~ ~1 1 l to 6 hydroxy groups, preferably 2 to 3 hydroxy groups, and 2 1 to l0 nitrogen atoms, such as tris-hydroxymethyl amino-3 methane, diethanolamine and diisoprop~nolamine, etc. The 4 products obtained from a 2,2-disubstituted-2-amino-l-alkanol having 2 to 3 hydroxy groups and containing a total of 4 to 6 8 carbon atoms as represented by 2-amino-2-(hydroxymethyl)-7 1,3-propanediol (also known as tris-hydroxy methylamino-8 methane) are preferred. Other examples o said hydroxy 9 amines include 2-amino-2-methyl-l,3-propanediol; 2-amino-2-ethyl-l,3-propanediol, etc.
11 VII. Process 12 The grafted polymeric solution can be readily re-

13 acted with said polyamines, polyols, hydroxy amines and mix-

14 tures thereof by admixture together and heating at a temp-erature of from about 100C. to 250C. for from l0 minutes 16 to 30 hours, preferably l0 minutes to l0 hours, usually 17 about 15 minutes to about 3 hours. It is preferred to use 18 0.0l to 2.5 mole, more preferably 0.5 to l.0 mole,of the 19 polyfunctional material, e.g. polyamine, polyol or hydroxy-amine, per mole of grafted maleic anhydride. The reaction 21 of diethylene triamine with the grafted ethylene-containing 22 polymer occurs in 15 minutes or less at 170C. with a nitro-23 gen blanket.
24 The grafting step according to this invention can be accomplished without degradation of the chain length 26 (molecular weight) of the ethylene-containing polymer. Mea-27 gurement of molecular weights and degradation can be eval~a~d 28 by determination of the thickening efficiency of the polymer.
29 m ickening efficiency (T.E.) is defined as the ratio of the weight percent of a polyisobutylene (sold as an .. . .

E3 1 oil solution b~ Exxon Chemical Co. as Paratone N), having a 2 Staudinger Molecular Weight of 20,000, required to thicken 3 a solvent-extracted neutral mineral lubricating oil, having 4 a viscosity of 150 SUS at 37.8C., a viscosity index of 105 and an ASl~I pour point of 0F., (Solvent 150 Neutral) to a 6 viscosity of 12.4 centistokes at 98.9C., to the weight per-7 cent of a test copolymer required to thicken the same oil 8 to the same viscosity at the same temperature. T.E. is re-9 lated to ~ and is a much more convenient, practical mea-surement. As a rough guide, a T.E. of 1,4 is about a ~ of 11 17,000 while a T.E. of 2.86 is about a ~n of 60,000; polymer 12 type influences this relationship.
13 The oil having attached, grafted maleic anhydride 14 groups w~en reacted with the polyfunctional derivatives, e.g. polyamine, is also converted to the corresponding deri-16 vatives. If desired, the split between the derivatized 17 graft polymer and the derivatized graft oil can be deter-18 mined by dialysis into polymer and oil fractions and infra-19 red or nitrogen analysis of the fractions.
The final reaction product contains in the range 21 of O.OOl to 25, preferably O.Ol to lO, wt. % nitrogen and/
22 or oxygen and has a l~n in the range of 700 to 500,000, pre-23 ferably 700 to 250,000. For the polymeric additives of ~4 higher molecular weight, i.e. a ~n of from about lO,000 to about 500,000, e.g. lO,000 to 250,000, (useful for pour de-26 pressant and/or V.I.-improving applications), the ni~rogen 27 and/or oxygen content ranges from about O.OOl to 5 wt. per-28 cent, preferably O.Ol to 0~5 wt. %. For polymeric addi-29 tives of lower molecular weights, i.e. l~n of less than about lO,000 (useful as pour depressant and/or dispersant), the ~3 81 6~1 1 nitrogen and/or oxyg~ content ranges broadly from about 2 0.001 to 25 wt. %, preferably from 0.01 to 8 wt. %. The 3 unique advantages of the present invention include the fea-4 tures that there is no significant degradation of polymer chain le~gth during the grafting of the polymer and subse-6 quent imidation and that the amount of nitrogen-containing 7 polymer material appears to be highly soluble in the hydro-8 carbon solvent used during the grafting step.
9 Minor amounts, e.g. 0.001 to 49 wt. %, preferably 0.001 to 20%, of the oil-soluble nitrogen and/or oxygen 11 containing graft polymers of the invention can be in-12 corporated into a major amount of an oleaginous material, 13 such as a lubricating oil or hydrocarbon fuel. When used 14 in lubricating oil compositions, e.g., automotive or die-sel crankcase lubricating oil, the polymer concentrations 16 are within the range of about 0.01 to 20 wt. %, e.g., 0.1 17 to 15.0 wt. %~ preferably 0.25 to 10.0 wt. %, of the total 18 composition. The lubricating oils to which the products 19 of this invention can be added include not only hydrocarbon oil derived from petroleum, but also include sy~thetic 21 lubricating oils such as esters of dibasic acids and complex 22 esters made by esterification of monobasic acids, poly-23 glycols, dibasic acids and alcohols.
24 These polymeric additives can be incorporated in fuels, such as middle distillate fuels, at concentrations of 26 from about 0.001 to about 0.5 wt. % and higher, preferably 27 from about 0.005 to 0.2 wt. ~/O,of the total composition.
28 mese polymeric additives can contribute dispersant activity , .

:' .

.

1 to the fuel as well as varnish control behavior.
2 The nitrogen and/or oxygen containing graft poly-3 mers of the invention may be prepared in a concentrate 4 form, e.g., from about 5 wt. % to about 49 wt. %, prefer-ably 15 to 49 wt. %,in oil, e.g., mineral lubricating oil, 6 for ease of handling.
7 The above concentrates may contain other conven-8 tional additives, such as dyes, pour point depressants, 9 antiwear agents, antioxidants, other viscosity-index ~m-o provers, dispersants and the like.
11 ~XAMPLE 1 2 One gallon (3000 gms.) of a 9 wt. % solution of an ethylene-propylene copolymer made by the Ziegler-Natta pro-4 cess using H2-moderated VOC13/aluminum sesqulchloride cata-lyst, the copolymer having a crystallinity of less than 25%
16 containing about 54 wt~ % ethylene and 46 wt. % propylene, 17 having a T.E. of 2.86 (~n - 60,000),(which is equivalent ~o 8 about 0.005 mole copolymer) in SlOON (Solvent 100 Neutral~
19 neutral oil wa8 heated to 180C. under a nitrogen blanket.
To this was added with stirring 11.25 gms. (0.375 wt. %9 21 0.115 mole) of maleic anhydride and 2.7 gms. (0.09 wt. %) of 22 2,5-dimethyl hex-3-yne2,5-bis-tertiary butyl peroxide.
23 After about 5 hours the system maintained at 180C. was 24 sparged with nitrogen for 2 hours to remove all of the un-reacted maleic anhydride. To this æystem cooled to 150C.
26 10 gm8. (0.33 wt. %, 0.096 mole)of diethylene triami~e was 27 added. me wt. % are all based on the weight of the initial 28 oil solution. The reaction was conducted for 3 hours at 29 150C. followed by sparging with nitrogen for 3 hours at 180C. This resulted in a nitrogen-containing grafted

- 15 -~0 8 1 6~ 1 l copolymer having a T.E. of 2.99 thus showing that there was 2 no breakdown in molecular weight but instead a slight in-3 crease. The product was subjected to infrared analysis 4 which showed the 1790 micron absorption peak indicative of the acid anhydride group essentially eliminated and replaced 6 by an amide peak at 1710 micron after reaction with the 7 polyamine.

9 The following Table I describes a number of experi-ments carried out according to this invention~ The reactions ll were carried out essentially as that of Example 1 except for 2 variations in reactants and their concentrations and reaction l3 conditions as noted in said table; the same peroxide was 14 used as in Example 1 and the copolymer was made by t~e same :
process.

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~ l l l 1 EXAMPLE 12 ~ 8 ~
2 Two fully formulate~ lubricating oil blends were 3 prepared by blending 6.5 wt. % of the additive of Example 1 4 or 9.8 wt. % of the additive of Example 2 respec~ively with 4.0 wt. % of a borated ashless dispersant (40% active in-6 gredient), 0.9 wt. % of a commercial zinc dialkyl dithio-7 phosphate antiwear additive ~70% active ingredient), 1.0%
8 of an overbased magnesium hydrocarbon sulfonate concentrate 9 (400 total base number),O.3 wt. % of a rust inhibitor lo (ethoxylated alkyl phenol) and 0.5% of an ashless antioxi-11 da~t, the balance of the formulation being a refined lubri-12 cating oil base stock. The fully formulated lubricant had 13 a viscosity in the SAE lOW-30 range.
14 For comparison, two similar blends were prepared substituting for the additive of this invention 9.1 wt. %

16 of an ethylene-propylene copolymer containing about 54 wt. %

17 ethylene and having a T.E. of 1.4 with the same oil/addi-

18 tive package as above to make test Blend C and 6.0 wt. % of

19 a commerciall~y available methacrylate multifunctional vis-cosity index improver-dispersant (about 45% active ingredi-: B 21 ent) sold as Acryloid 956 by Rohm and Haas of Philadelphia, 22 Pennsylvania, with the same oil/additive package as above 23 to make Test Blend D.
24 Each of the blends prepared as described was sub-2s jected to the MS Sequence VC Engine Test which is a test 26 well known in the automotive industry. me test is run in a 27 Ford engine of 302 cubic inch displacement following the 28 procedure described in the publication enti~led "Multi-29 cylinder Test Sequences for Evaluating Auto tive Engine Oils" (ASTM Special Publication 315-E). At the end of each ~ f~

~ ~ 8~
1 test various parts of the engine are rated on a merit basis 2 wherein 10 represents a perfectly clean part, and lesæer - 3 numbers represent increasing degree of deposit formation.
4 The various ratings are then totaled and averaged on the basis of 10 as a perfect rating. The results obtained with 6 the blends described above are given in Table II.

9MERIT RATrNGS (BASIS 10) 10Additive of Test Blend 11Example l Example 2 C D
12 Wt% (100%
13 active basis) 0.585 1.33 1.24 2.7 14 Sludge Merit 8.5 9.4 6.4 8.8 Varnish Merit 8.4 8.3 7.3 8.2 16 Piston Skirt 17 Varnish Merit 8.0 8.4 7.0 8.2 18 The above tests show that on a weight basis, the 19 additives which ca~ be prepared by this inventionJ are bet-ter than a connnercial multifunctional viscosity index im-21 prover (Blend D). A comparison of Examples 1 and 2 with 22 Test Blend C indicates that the present invention signifi-23 cantly~mproves the dispersancy of ethylene-propylene co-24 polymers generally used as viscosity index improvers.

.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for preparing a lubricating oil concentrate of a viscosity index improver having sludge dispersing properties and a number average molecular weight in the range of about 10,000 to 250,000; comprising dissolving from 5 to 30 weight percent of ethylene copolymer comprising 30 to 80 wt. % ethylene and 20 to 70 wt. % C3 to C18 alpha-olefin in a mineral lubricating oil as solvent, maintaining said resulting copolymer-oil solution at a temperature of from about 100°C to about 250°C and under an inert atmosphere while admixing an ethylenically-unsaturated dicarboxylic acid material selected from the group consisting of maleic anhydride maleic anhydride derivatives, maleic acid and fumaric acid, and a free-radical initiator having a boiling point in excess of about 100°C into said solution, wherein the weight ratio of said dicarboxylic acid material to said initiator is about 1:1 to 30:1, and maintaining said temperature and inert atmosphere for about 0.1 to 12 hours to graft said acid material onto said ethylene copolymer and said solvent, without substantial molecular weight breakdown of said ethylene copolymer, and thereafter reacting carboxy groups of said grafted polymer with a polyfunctional material selected from the group consisting of polyamines having 3 to 20 carbon atoms and 2 to 12 nitrogen atoms, C2to C30 polyols having 2 to 10 hydroxyl radicals, and C2 to C30 hydroxy amines having 1 to 6 hydroxy groups and 1 to 10 nitrogen atoms, to thereby form said lubricating oil concentrate.

2. A process according to Claim 1, wherein said C3 to C18 alpha-olefin is propylene and said dicarboxylic acid material is maleic anhydride.

3. A process according to Claim 2, wherein said polyfunctional material is said polyamine.

4. A process according to Claim 2, wherein said polyfunctional material is a polyol.

5. A process according to Claim 2, wherein said polyfunctional material is a hydroxy amine.

6. A process according to Claim 1, wherein said initiator is a peroxide.

7. A process according to Claim 6, wherein said initiator is 2,5-dimethyl-hex-3-yne-2,5-bis-tertiary-butyl peroxide and is used in a concentration of from about 0.005 to 1 wt. %, based upon the total weight of said copolymer-oil solution.

8. A process according to Claim 7, wherein said grafting temperature is in the range of 120° to 190°C.

9. A process according to Claim 8, wherein the weight ratio of said dicarboxylic acid material to said initiator is within, the range of 2.0:1 to 5.0:1.

10. The lubricating oil concentrate produced by the process of Claim 1.

11. The lubricating oil concentrate produced by the process of Claim 3.

12. The lubricating oil concentrate produced by the process of Claim 4.

13. The lubricating oil concentrate produced by the process of Claim 5.

14. A lubricating oil composition comprising a major proportion of lubricating oil and a minor V.I. improving amount of the concentrate of Claim 10.

15. A lubricating oil composition comprising a major proportion of lubricating oil and a minor V.I. improving amount of the concentrate of Claim 11.

16. A lubricating oil composition comprising a major proportion of lubricating oil and a minor V.I. improving amount of the concentrate of Claim 12.

17. A lubricating oil composition comprising a major proportion of lubricating oil and a minor V.I. improving amount of the concentrate of Claim 13.