CA1175411A - Haze-free polymer additives for fuels and lubricants - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
Solutions of ethylene-propylene copolymers graf-ted with vinyl-containing monomers, maleic anhydride- or ethyienlcally-unsaturated acids, including functionalized derivatives thereof, and then reacted with polyols, poly-amines or hydroxyamines, as well as hydrogenated buta-diene or isoprene copolymers, which solutions have haze-forming tendencies in mineral oil And are generally useful as multifunctional lubricating oil additives, are reduced in haze-forming tendencies by treatment with 0.5 to 25 wt.
? of an alkyl hydroxy benzene compound, such as nonyl or docecyl phenol.

Description

` 1175~11 l This invention relates to haze-free multifunc-

2 tional polymeric additives for lubricating oils which are

3 useful both as dispersants and viscosity index improvers.

4 ~ore particularly, the invention relates to haze-free hydrocarbon mineral oil solution concentrates of ethylene/
6 alpha-olefin copolymers and terpolymers which have been 7 solution grafted with polymerizable monomers and, in some 8 cases, further derivatized by reaction with polyfunc-9 tional compounds containing amino or hydroxy functional groups.
ll Graft copolymers based on ethylene/alpha-olefin 12 which are either copolymerized or further functionalized 13 with polyamines or polyols are known in the art and are 14 disclosed in U.S. Patents 4,089,794 issued May 16, 1918 to Engel et al; No. 4,146,489 issued March 27, 1979 to 16 Stambaugh et al and~U.S. Patent ~o. 4,160,739 issued 17 July 10, 1979 to Stambaugh et al. The tendency of such 18 polymers to form haze in hydrocarbon or mineral oil 19 solutions is also recognized in the art as described in U.S. Patent No. 4,144,181, issued March 13, 1979 to 21 Elliott et al, which discloses haze-free hydrocarbon 22 solutions of such multifunctional polymeric additives by 23 reacting same with an oil-soluble strong acid, preferably 24 a long-chain alkyl aryl sulfonic acid.
The present invention is directed to a resolu-26 tion of the same problem and provides an alternate 27 technique for providing haze-free solutions through the 28 use of certain aromatic hydroxy compounds.
29 In accordance with the present invention, there are provided substantially haze-free mineral hydrocarbon 31 oil solution concentrate compositions comprising a hydro-32 carbon mineral oil of lubricating viscosity and from 33 about 1 to 50 wt. %, based upon the total weight of said 34 composition, of an ethyIene/alpha-olefincopolymeric dispersant-viscosity index improver material which, in 36 solution, has haze-forming tendencies, which material has 37 been formed by grafting ethylene/alpha-olefin copolymers 175~1 1 1 or terpolymers with (a) a vinyl-containing nitrogen 2 monomer; or (b) a monomer system comprising maleic an-3 hydride and monomers copolymerizable therewith and post-4 reacting the graft with a polyamine, or ~c~ an ethyleni-cally unsaturated carboxylic acid material, which graft 6 is subsequently reacted with polyamine, polyol or hydroxy 7 amine, the elimination or inhibition of haze-forming 8 tendencies being provided by treating said composition at 9 temperatures of about 50C to 150C with about O.S~ to 25% by weight, based on the weight of said solution, of an 11 oil-soluble alkyl hydroxy benzene compound, said compound 12 containing 1-3 alkyl groups each containing about 2-20 13 carbon atoms and said compound having 1-3 hydroxy groups.
14 A further embodiment of the present invention is lubri-cating oil compositions which contain the haze-free con-16 centrates in amount of from about 1-30 wt.~, preferably S
17 to 15 wt. %, based upon the total weight of said lubri-18 cating oil composition.
19 The treatment in accordance with the present invention to provide clear and haze-free oil solution 21 concentrates is preferably conducted with about 2-8~ by 22 weight, based on the weight of the solution, of a mono-23 alkylated phenol having 8-12 carbon atoms, such as nonyl-24 phenol and dodecylphenol, which are particularly preferred materials. The treatment of the graft copoly-26 mers in accordance with the present invention is pre-27 ferably conducted at a temperature of about S0-90C for a 28 period of about 10 minutes to 10 hours, preferably in the 29 area of about 0.5 to about 3 hours.
While it is feasible to carry out the process of 31 the present invention on a fully formulated oil as op-32 posed to a solution concentrate, this is not a desirable 33 approach since it could lead to unwanted interference 34 with other additives present in such formulations.
The invention is particularly applicable to 36 ethylene-propylene copolymers and ethylene-propylene-37 diene terpolymers which are grafted with polar nitrogen-~ 17541 1 1 containing monomers such as C-vinyl pyridines and N-2 vinylpyrrolidone as described in said U.S. Patent 3 4,146,489. The ethylene propylene polymers contain about 4 40-70 mole % ethylene, and have a viscosity average molecular weight of about 10,000 to 200,000. The ter-6 polymers contain about 10% by weight of a non-conjugated 7 diene such as 1,4 hexadiene, dicyclopentadiene or ethyli-8 dene norbornene. Examples of suitable polar, nitrogen-9 containing monomers which are grafted to these polymers or terpolymers are 2-vinylpyridine, N-vinylpyrrolidone, 11 4-vinylpyridine and other lower alkyl (Cl-Cg) substituted 12 C-vinylpyridines,such as 2-methyl-5-vinylpyridine, 2-13 methyl-4-vinylpyridine and 2-vinyl-6-methylpyridine.
14 Such materials are preferably solution grafted in the presence of a free radical initiator such as alkyl peroxy 16 esters, alkyl peroxides, alkyl hydroperoxides and the 17 like with t-butyl perbenzoate as the preferred initiator.
18 The temperature range is about ~0-150C and suitable 19 solvent media include aliphatic or aromatic hydrocarbons including minerai oils, the latter being preferred since 21 it provides a convenient vehicle for blending the finish-22 ed product into a lubricàting oil composition.
23 Another category of copolymers suitable for 24 treatment in accordance with the present invention are those described in U.S. Patent 4,144,181 which are the 26 oil-soluble derivatized ethylene copolymers based upon 2-27 98 weight ~ ethylene with one or more C3-C2g alpha ole-28 fins, such as propylene, which are grafted, preferably 29 solution grafted, at elevated temperatures in the presence of a free radical initiator with an ethyleni-31 cally-unsaturated carboxylic acid material thereafter 32 reacted with a polyfunctional material reactive with 33 carboxy groups such as a polyamine, a polyol or a hydroxy 34 amine or mixture thereof to form carboxyl-grafted polymeric derivatives which are suitable as dispersant 36 viscosity index improvers for lubricating oil. Ethylene 37 copolymers preferably contain 30-80 weight % ethylene and ~ 1754 1 ~

1 20-70 weight ~ of 1 or more alpha olefins, preferably r3_ 2 Clg, particularly propylene, which will have a Mn in the 3 range of about 700-500,000, preferably 10,000-50,000 as 4 determined by vapor phase osmometry. Ethylene-propylene copolymers are particularly preferred. Also suitable are 6 ethylene/alpha-olefin terpolymers which additionally 7 contain 0.5-20 preferably 1-7 mole % of a nonconjugated 8 polyolefin such as cyclopentadiene, 2-methylene-5-9 norbornene, nonconjugated hexadiene or other noncon-jugated diolefins having 6-15 carbon atoms,such as ethyl 11 norbornadiene, ethylidiene norbornene and the like, as 12 well as mixtures of such nonconjugated diolefins.
13 The materials which are grafted onto the copoly-14 mers or terpolymers are those compounds which contain at least one ethylenic bond and at least one, preferably 16 two, carboxylic acid or anhydride groups such as maleic 17 anhydride, chloromaleic anhydride, itaconic anhydride, N-18 hexylmaleimide or the corresponding dicarboxylic acids 19 such as maleic acid or fumaric acid. Also suitable are the monocarboxylic acrylics and methacrylics such as 21 acrylic and methacrylic acids,methyl acrylate and methyl 22 methacrylate.
23 The grafting of the polymers conducted as 24 described in U.S. Patent g,l44,181 in the presence of a free radical initiator such as peroxide or hydroperoxide 26 at elevated temperatures of about 100 to 250C and pre-27 ferably in a mineral lubricating oil solution. Subse-28 quent to the grafting, a derivatization reaction is 29 carried out with a polyamine, polyGl or hydroxyamine.
Useful polyamines include those having 2-16 carbon atoms 31 and about 2-6 nitrogen atoms in the molecule including 32 the hydrocarbyl- polyamines which may contain other 33 groups such as hydroxy, alkoxy, amide, imidazoline groups 34 and the like. Preferred are the aliphatic saturated polyamines. Examples of suitable amine compounds include 36 ethylene diamine, 1,2-diaminomethane, 1,3-diamino propane, 37 triethylene tetramine, tetraethylene pentamine, 1,2-~ 1754 1 1 1 propylene diamine and the like. Other suitable amines 2 include N-amino alkyl morpholines and N-amino alkyl 3 piperazines.
4 A useful polyol for reaction with the grafted ethylene-containing polymers are the C2-C30 polyols 6 having 2-10 hydroxyl groups such as glycerol, alkylene 7 glycols, such as dipropylene glycol, as well as pentaery-8 thritol which is the preferred polyol. The hydroxy amines 9 include those having 2-30 carbon atoms, 1-6 hydroxy groups, and 1-10 nitrogen atoms,such as diethanolamine, 11 diisopropanolamine, tris-hydroxymethyl aminomethane, 2-12 amino-2-ethyl-1,3-propanediol and the like. The reaction 13 with the grafted polymer preferably is conducted in 14 solu`tion at a temperature of 100-250C utilizing 0.5-1.0 mole of the polyfunctional polyamine, polyol or hydroxy 16 amine per mole of the grafted carboxylic material. The 17 final product can then be subjected to the haze elimina-18 tion treatment step in accordance with the present in-19 vention. Other graft copolymers which can have haze forming tendencies which can be treated in accordance 21 with the present invention are the same ethylene~alpha 22 olefin, preferably propylene, copolymers or terpolymers 23 which may be grafted with maleic acid or anhydride plus 24 monomers copolymerizable with maleic acid or anhydride as described in detail in U.S. Patent 4,160,739. Generally 26 the monomers copolymerizable with maleic acid or an-27 hydride are the alpha, beta-monoethylenically unsaturated 28 monomers which are soluble in a reaction medium and 29 suitably reactive, these include the esters, amides, and nitriles of acrylic and methacrylic acid and other 31 monomers containing no free acid group. Other useful 32 monomers include styrene, alpha-methyl styrene, Cl-C4 33 alkyl and alkoxy ring substituted styrenes, C4-C12 alpha 34 olefins such as isobutylene, vinyl esters such as vinyl acetate, vinyl ketone, vinyl chloride, and vinylidene 36 chloride. Preferred are monomers containing up to about 37 10 carbon atoms as with the preparation-of other ~ 1754~ 1 1 copolymer-based additives. As discussed above, the 2 grafting is preferably conducted in solution at elevated 3 temperatures of from about 80-150C in the presenceof a free 4 radical initiator. After preparation of the graft copoly-mer, a post-reaction with a polyamine is conducted in the 6 same solvent reaction medium at a temperature of at least 7 about 80C and typically in the range of about 150-250C.
8 A variety of polyamines are suitable including aliphatic, 9 cycloaliphatic, aromatic or heterocyclic polyamines, preferably containing a single primary or secondary amino 11 group and at least one tertiary amino such as a hetero-12 cyclicamino group. The polyamines may contain up to 13 about 6 nitrogen-atoms, preferably 2-4 nitrogen atoms 14 and, generally C4-C30, preferably C4-C12, polyamines are used.
16 Thickening efficiency (T.E.) is defined as the 17 ratio of the weight percent of a polyisobutylene (sold as 18 an oil solution by Exxon Chemical Company as Paratoné N~, 19 having a Staudinger molecular weight of 20,000, required to thicken a solvent-extracted neutral mineral lubri-21 cating oil, having a viscosity of 150 SUS at 37.8C., a 22 viscosity index of 105 and an ASTM pour point of 0F., 23 (Solvent 150 Neutral) to a viscosity of 12.4 centistokes 24 at 98.9C., to the weight percent of a test copolymer required to thicken the same oil to the same viscosity at 26 the same temperature. T.E. is related to Mn and is a 27 much more convenient, practical measurement. As a rough 28 guide, a T.E. of 1.4 is about a Mn of 17,000 while a T.E.
29 of 2.86 is about a Mn of 60,000; polymer type influences this relationship. Thickening efficiency is used in the 31 examples below.
32 A wide range, e.g. 0.001 to 50 wt. %, of active 33 ingredient polymeric additive of the oil-soluble graft 34 polymer treated in accordance with this invention can be incorporated into about a major amount of an o;eaginous 36 material such as a lubricating oil or hydrocarbon fuel.
37 When used in lubricating oil compositions, e.g.

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1 175~ 1 1 1 automotive or diesel crankcase lubricating oil, t~e 2 treated polymer solution concentrates are used preferably 3 within the range of about l to 30 weight percent, pre-4 ferably 5 to 15 wt. ~, of polymer solution concentrate based on the ~eight of the total lubricating oil composi-6 tion. The lubricating oils to which the products of this 7 invention can be added include not only hydrocarbon oil 8 derived from petroleum, but also include synthetic 9 lubricating oils such as esters of dibasic acids and complex esters made by esterification of monobasic acids, 11 polyglycols, dibasic acids and alcohols. Since these 12 type of additives are normally sold and used as oil 13 concentrates, the practical definition of use levels in 14 terms of concentrates is used here.
These treated polymeric additives can be in-16 corporated in fuels, such as middle distillate fuels, at 17 active ingredient concentrations cf from about 0.001% to 18 about 0.5 wt. % and higher, preferably from about 0.005 19 to 0.2 wt. ~, of the total composition. These treated polymeric additives can contribute dispersant activity to 21 the fuel as well as varnish control behavior.
22 The nitrogen-and/or oxygen-containing graft 23 polymers treated in accordance with the invention may be 24 prepared in a concentrate form, e.g. from about 1 wt. %
to about 50 wt. ~, preferably S to 25 wt. %, in oil, e.g.
26 mineral lubricating oil, for ease of handling.
27 In addition to treating the graft copolymers 28 noted above, a further embodiment of the present inven-29 tion resides in carrying out the treatment process of the present invention to clarify hazy solutions of hydro-31 genated copolymers of butadiene or isoprene with styrene.
32 Solutions of these polymers, which are used as viscosity 33 index improvers, do have a tendency to form hazy solu-34 tions at high concentrations, i.e. about 10% to 40% by volume and this haze can over a period of time give rise 36 to deposition of sediment. Treatment of these hazy poly-37 mer solution concentrates with 0.75 to 25 wt. %~ prefer-1 ably 2-8 wt. ~, of the alkyl hydroxy benzene compound, 2 especially at elevated temperatures,such as about 50C., 3 will provide clear stable solutions. The hydrogenated 4 copolymers suitable for this embodiment are those copoly-mers of butadiene or isoprene with styrene, either random, 6 tapered or block copolymers having a molecular weight of 7 about 20,000 to 200,000 containing about 20 to 70 wt. ~
8 of copolymerized styrene and having viscosity index im-9 proving properties when used in lubricating oils. Such polymers are described for example in U.S. Patent 1~ 3,965,019 and U.S. Patent 4,081,390. Typically greater 12 than 95% of the olefin bonds are hydrogenated. An ex-13 ample of such a polymer is a hydrogenated 25 wt. % styrene 14 - 75 wt. % isoprene copolymer having a Mn of 50,000 ~
100,000 where the isoprene is greater than 95% of the 1,4 16 - form. Dodecyl and nonyl phenol are the preferred 17 treating agents and provide substan~ially haze-free lubricating 18 oil compositions comprising a lubricating oil containing 19 0.1% to 50 wt. ~ of the copolymer treated in accordance with the invention.
21 The above solutions may contain other conventional 22 additives, such as dyes, pour point depressants, antiwear 23 agents, antioxidants, other viscosity-index improvers, 24 dispersants and the like.
For purposes of this disclosure an oil-soluble 26 compound should dissolve in mineral oil, e.g. Solvent 100 27 Neutral at 20C in a concentration of at least 5 weight 28 percent based on the weight of said mineral oil.
29 The invention is further illustrated by the following Examples which are not to be considered limita-31 tive of its scope.
32 The Examples below will set forth both "con-33 centrates" and "solutions". The term concentrates refers 34 to the actual commercial form of the polymeric additives which are sold as mineral oil concentrated solutions 36 containing a stated amount of polymeric additive. When 37 actual finished lubricating oil formulations are prepared ~ ~ 7 5 ~

1 from these commercial additives, the "concentrate" is 2 diluted to form a "solution". To fully evaluate the 3 effect of treatment in accordance with the present in-4 vention, the treated concentrates are diluted to form solutions which reflect actual usage levels of additives 6 in finished formulations. This is especially important 7 in evaluating sediment formation since, while haze is 8 usually observable in concentrates, sediment is not 9 because of the high viscosity of the concentrate when compared with a diluted solution.
11 Example 1 12 (~) A solution having a viscosity of 11 cSt at 13 100C was prepared which contained 14~ by weight of a 14 graft copolymer of ethylene-propylene (43 wt. % ethylene) copolymer with 2-vinyl pyridine available as "Acryloid 16 1155"~from Rohm and Haas, Philadelphia, Pennsylvania,in 17 the form of a mineral oil solution concentrate containing 18 about 7-8% by weight of the vinyl pyridine grafted EP
19 copolymer (~ N=0.32; a T.E. = 2.66) dissolved in Sol-vent 150 Neutral mineral lubricating oil. The solution 21 of this concentrate was observed to be hazy and upon 22 standing for 3 days, sediment deposits began to appear.
23 Viscosity of the 7-8 wt. % concentrate was 1562 cSt. at 24 100C.
(B) A fresh sample of the above 7-8 wt. % con-26 centrate was treated with 2 ~ by wt. of nonyl phenol, 27 based on the total weight of the concentrate,at a tem-28 perature of 65C~ and provided a clear, easily flowing 29 concentrate having a viscosity of 1164 cst. at 100C. A
14~ by wt. oil solution of the thusly treated concentrate 31 remained clear upon standing for two months with no 32 observable sediment. The viscosity of this solution was 33 11 cSt at 100C.
34 Example 2 Example 1 was repeated using dodecyl phenol as 36 the treating agent and equivalent results were obtained.

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1~75~11 1 Example 3 2 Example 1 was repeated using a solution of a 3 concentrate of an ethylene-prcpylene copolymer (43% wt. %
4 ethylene) having a T.E. of 2.7 grafted with maleic anhydride and post-reacted with tetraethylene pentamine 6 following the method of U.S. Patent 4,089,794. The 7 solution was visibly hazy but treatment of the concen-8 trate with 4% by wt. nonyl phenol at 65C. yielded a 9 clear solution with no haze or sediment formation upon standing. Viscosity for both the treated and untreated 11 solutions was essentially the same.
12 Example 4 13 A 20% mineral oil solution by volume of a 14 concentrate containing about 3 wt. % of a 95% hydro-genated 25 wt. % styrene-75 wt. % isoprene copolymer 16 having a Mn of 50,000-100,000 in lubricating oil was 17 measured for haze level using a nephelometer (Model 9, 18 Coleman Industries, Maywood, Illinois) and the haze 19 reading was 48 nephelos.
After treatment of the concentrate with 2% by 21 wt. of nonyl phenol at 121C. for 1 hour the haze level 22 of a subsequently prepared 20% by volume solution of the 23 concentrate was reduced to 14 nephelos. Thickening 24 efficiency was not affected by the treatment with nonyl phenol.

Claims (14)

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

1. A substantially haze-free mineral hydrocarbon oil solution concentrate composition comprising a mineral oil of lubricating viscosity and from about 0.1 to 50 wt.
%, based upon the total weight of said composition, of ethylene-alpha-olefin dispersant-viscosity index improver material which material has been formed by grafting an ethylene alpha-olefin copolymer or terpolymer with (a) a vinyl-containing nitrogen monomer or; (b) a monomer system comprising maleic anhydride and monomers copolymerizable therewith and post reacting the graft with a polyamine or, (c) an ethylenically unsaturated carboxylic acid material which graft is subsequently reacted with a polyamine, polyol or hydroxy amine, wherein the inhibition of haze in said composition is provided by treating said composition at a temperature of about 50°C to 150°C with about 0.5 to 25%
by wt., based upon the weight of said composition, of an oil-soluble alkyl hydroxy benzene compound, said compound containing 1-3 alkyl groups, each containing about 2 - 20 carbon atoms and said compound having 1 - 3 hydroxy groups.

2. The composition of claim 1 wherein the ethyl-ene/alpha-olefin dispersant viscosity index improver has been formed by grafting with a vinyl-containing nitrogen monomer.

3. The composition of claim 2 wherein the graft is that of an ethylene/propylene copolymer or terpolymer with a lower C1-C8 alkyl-substituted vinyl pyridine or N-vinyl pyrrolidone.

4. The composition of claim 3 wherein the graft is that of an ethylene/propylene copolymer containing 50 -70 mole % of ethylene and the vinyl monomer is 2-vinyl-pyridine.

5. The compositon of claim 1 wherein the alkyl hydroxy benzene compound is a mono-alkylated C8-C12 alkyl phenol.

6. The composition of claim 1 wherein the alkyl hydroxy benzene compound is nonyl phenol.

7. The composition of claim 1 wherein the haze inhibiting treatment is conducted with 2 to 8 % by wt. of said alkyl hydroxy benzene compound.

8. The composition of claim 1 wherein said grafting is solution grafting conducted in a hydrocarbon mineral lubricating oil.

9. The composition of claim 1 wherein the dis-persant-viscosity index improver material is an ethylene propylene copolymer having 38 to 70 wt. % ethylene which is solution grafted with maleic anhydride in a mineral lubricating oil solvent and the polyfunctional reactant is a polyamine.

10. The composition of claim 9 wherein the poly-amine is an alkylene polyamine.

11. The composition of claim 9 wherein the poly-amine is a C3 - C30 imidazoline, N-amino alkyl morpholine or N-amino alkyl piperazine.

12. A substantially haze-free oil solution con-centrate composition comprising a mineral hydrocarbon oil of lubricating viscosity and from about 0.1 to 50 wt. %
based on the total weight of said composition of a viscos-ity index-improving hydrogenated copolymer of butadiene or isoprene with 20 to 70 wt. % of copolymerized styrene, the copolymer having an Mn of 20,000 to 200,000 wherein said composition has been treated at a temperature of about 50°C to 150°C with from about 0.75 to 25% by weight based on the weight or said concentrate with an oil-soluble alkyl hydroxy benzene compound, said compound having 1 to 3 C2 - C20 alkyl groups and 1 - 3 hydroxy groups.

13. The composition of claim 12 wherein said composition is treated with 2 - 8 wt. % of nonyl phenol or dodecyl phenol.

14. A lubricating oil composition containing about 5 to 15 wt. % of the haze-free solution concentrate of claims l or 12