FR2460993A1 - PROCESS FOR THE PREPARATION OF A SOLUTION IN A MINERAL OIL OF A POLYMER THAT IMPROVES THE VISCOSITY INDEX OF MINERAL OILS, A PRODUCT PRODUCED THEREBY, AND A LUBRICATING OIL COMPOSITION COMPRISING THE PRODUCT - Google Patents

Abstract

THE PRESENT INVENTION CONCERNS THE FIELD OF ADDITIVES FOR LUBRICATING OILS. IN ACCORDANCE WITH THE INVENTION, AN ETHYLENICALLY UNSATURATED DICARBOXYL SUBSTANCE IS GRAFT, PREFERABLY IN SOLUTION, IN AN INERT ATMOSPHERE AND IN THE PRESENCE OF AN INITIATOR OF FREE RADICALS, ON ETHYLENE COPOLYMERS, SOLUBLE IN OILS, OIL SOLUBLE, ABOUT 2 TO 98 BY WEIGHT OF ETHYLENE AND ONE OR MORE ALPHA-OLEFINS IN CAC, FOR EXAMPLE PROPYLENE, AND HAVING AN AVERAGE MOLECULAR WEIGHT

Description

The present invention relates to additives

  stable polymers with dispersing properties for lubricating oils

  who can also be useful as agents

  improving the viscosity index of lubricating oils.

  More particularly, this invention relates to solutions of stable viscosity and free of substantially saturated polymers comprising ethylene and one or more C3-C28 alpha-olefins, preferably propylene, on which are grafted, in the presence of a free radical initiator, an ethylenically unsaturated dicarboxylic acid, preferably at elevated temperature and under an inert atmosphere, the obtained product having subsequently been reacted with an alkyl heterosubstituted alkyl primary amine to form multifunctional polymeric reaction products characterized by viscosity stabilization solutions to

mineral oil base.

  It is well known that ashless dispersants for lubricating oil compositions promote the

  sludge dispersion properties of said compositions.

  A typical type of dispersant generally derives from a hydrocarbon-substituted dicarboxylic acid, for example an alkenyl succinic acid or its anhydride, which has been reacted with a nitrogenous substance,

for example an alkylenepolyamine.

  It is also well known that the introduction of carboxylic acid groups onto copolymers of ethylene, for example by reaction of an oxidized and degraded copolymer with maleic anhydride, provides a means of forming a derivative with an alkylenepolyamine, which which makes it possible to impart sludge dispersing activity to those copolymers which exhibit viscosity index (IV) improving activity when dissolved in mineral oils (see United States Patent No. 3 316,177). One way of introducing the carboxylic groups is to graft maleic anhydride onto the

  polymer by a radical mechanism. The United States Patent

  No. 4,089,794 discloses the production of additives

  dispersing mud, oil soluble, hydrocarbon

  fuels and lubricating oils by grafting

  free radical-induced solution of a di-

  ethylenically unsaturated carboxylic acid, such as maleic anhydride, on a substantially saturated copolymer comprising ethylene and at least one other alpha-olefin, at elevated temperature, in order to obtain, without appreciable degradation of the polymer, a useful precursor copolymer which is can then react with a polyfunctional substance reactive with a carboxylic acid, such as a polyamine or a hydroxyamine or a mixture thereof, to form multifunctional polymeric imide derivatives which have particular utility as lubricating oil additives acting against oxidation products and

sludge produced in the engines.

  The invention proposes to provide a dispersant formed by a grafted ethylene copolymer, which is generally useful as an agent for improving the viscosity index of mineral oils, and which has useful properties. sludge dispersion and improved viscosity stabilizing activity, which agent provides a trouble-free solution when dissolved in

a mineral oil.

  U.S. Patent No. 4,137,185 discloses that the reaction of organic acid anhydrides, for example acetic anhydride, makes it possible to form amide derivatives from any primary amine groups of the ethylene copolymer of imide type, which gives these copolymers a viscosity stabilization activity. The aforesaid reaction can be considered as defining a method for improving the viscosity stabilization of an oil additive concentrate, this concentrate comprising a hydrocarbon solvent and 0.1 to 50% by weight, based on the weight total of said concentrate, a viscosity index improving agent consisting of a

  graft copolymer of the imide type, ethylene and alpha-

  C3-C28 olefin, which has a number average molecular weight (Mn) of 700-500,000, which process comprises the step of reacting said concentrate with a hydrocarbon-substituted acid anhydride, wherein the hydrocarbon component comprises about 1 to 30 carbon atoms, adding said acid anhydride in about 0.5 to 2.5 moles, per primary amine group, of this concentrate and maintaining said concentrate at a temperature of about 500C to about about 250WC, preferably and 2001C, for a period of 0.25 to 8 hours, preferably 0.5 to 3 hours. It appears that the reaction is a side free primary amine group acylation to give an amide structure, which limits the property

  of chain extension, in solution, of multi-functional copolymers

  functional and therefore inhibits the growth of

  viscosity of oily solutions containing the additives.

  It has now been found that the stabilization of the viscosity can be favored, for the grafted copolymers made multifunctional which are described in the patent

  No. 4,137,185, when reacting 0.5 to 1.5 equiva-

  a slow molar (with respect to the grafted dicarboxylic acid groups) of an aliphatic, preferably C 8 to C 20, alkyl heterosubstituted primary alkylene amine, for example an aminopropyl and tridecyl ether with the said graft copolymer, which gives the surprising result which consists of an improved dispersant activity and the property of providing solution-free solutions by dissolution in

a mineral oil.

  In particular, the invention relates to a composition comprising a lubricating oil in which is dissolved, at least in an amount that can increase

  the viscosity number, a heteroarylalkylene-amine derivative

  C8-C20 substituted, oil soluble, of a viscosity index improver consisting of an ethylene polymer on which carboxyl functional groups have been grafted and which contains 0.001 to 8% by weight of nitrogen, the carboxyl groups grafted being an average of 2 to preferably 4 to 16, per molecule of ethylene copolymer. This invention provides an additive in the form of an oily composition having improved viscosity stability without visually observable disorder. Thus, the present invention also relates to novel amido-imido, preferably succinimido type grafted amine-derived amine copolymer compositions, as well as lubricants containing these compounds.

  copolymers, prepared as described herein.

  The ethylene copolymers on which the grafting is to take place contain from about 2 to 98%, preferably from 30 to 80%, by weight of ethylene and from about 2 to 98%, preferably from 20 to 70%, by weight. one or more C3-C28, preferably C3-C18, and more preferably C3-C8, alpha-olefins, for example propylene. These copolymers preferably have a degree of crystallinity of less than 25% by weight, as determined by X-ray examination and differential scanning calorimetry, and a number average molecular weight (n) of between about 700 and 500,000, preferably between 10,000 and 250,000, as determined by vapor phase osmometry (VPO) or osmometry using a membrane. Copolymers of ethylene and propylene are the most preferred. Of the other alpha-olefins which can be used in place of propylene to form the copolymer or in combination with ethylene and propylene to form a terpolymer,

  may be 1-butene, 1-pentene, 1-hexene, 1-

  octene, as well as branched-chain alpha-olefins such as 5-methylpentene-1 and 6-methylheptene-1 and mixtures

of these substances.

  It is also possible to use the terpolymers of ethylene, of said alphaolefin and of an unconjugated diolefin or mixtures of such diolefins. The amount of unconjugated diolefin is from about 0.5 to 20 mole percent, preferably from about 1 to about 7 mole percent, based on the total amount of ethylene and alpha-olefin. Typical diolefins include cyclopentadiene, 2-methylene-5-norbornene, unconjugated hexadiene or any other non-conjugated alicyclic or aliphatic diolefin having 6 to 15 carbon atoms per molecule,

  such as 2-methyl- or ethyl-norbornadiene, 2,4-dimethyl-

  2-octadiene, 3- (2-methyl-1-propane) cyclopentene, ethylidenenorbornene, etc. These ethylene copolymers (this term also including terpolymers) can be prepared using the well known Ziegler-Natta catalyst compositions. Such a polymerization can be carried out to obtain the copolymers of ethylene by passing 0.1 to 15 parts of ethylene, for example 5 parts; 0.05 to parts of this higher alpha-olefin, for example 2.5 parts, usually propylene; and 10 to 10,000 parts of hydrogen per million parts of ethylene; in 100 parts of an inert liquid solvent containing (a) about 0.0017 to 0.017 parts, for example 0.0086 parts, of a main catalyst containing a transition metal, for example VOCl3; and (b) about 0.0084 to 0.084 parts, for example 0.042 parts, of cocatalyst, for example (C2H5) 3A12C13; at a temperature of about 25 C and a gauge pressure of 420 kPa for a time sufficient to effect optimum conversion, for example 15 minutes to half an hour; all the aforementioned parts being

expressed in weight.

  The ethylenically unsaturated carboxylic substances which are grafted onto the copolymer contain at least one ethylenic bond and at least one, preferably two, carboxylic acid groups or the corresponding anhydride group or a polar group which can be converted

  said carboxyl groups by oxidation or hydrolysis.

  Maleic anhydride or a derivative thereof is preferred since it has been found that it is not appreciably homopolymerized, but that it is grafted onto the ethylene copolymer or terpolymer for give two carboxylic acid functions. These preferred substances correspond to the general formula:

1 1

  CC I! where R1 and R2 are hydrogen or halogen and 0 is oxygen. Further suitable examples include chloromaleic anhydride, itaconic anhydride or the corresponding dicarboxylic acids, such as maleic acid or fumaric acid, or their monoesters. The free-radical-induced grafting of ethylenically unsaturated carboxylic substances (carboxylic acids and derivatives) in solvents, such as benzene, is well known in the art. The grafting is carried out at elevated temperature, from about 100 ° C. to 250 ° C., preferably 150 ° C. to 180 ° C., for example above 160 ° C., in a solvent, preferably a mineral lubricating oil solution containing, for example, For example, 1 to 50% by weight, preferably 5 to 30%, based on the total initial oil solution, of the ethylene polymer, preferably under an inert atmosphere. The grafting is usually carried out in the presence of a decomposable compound at high temperature, which can provide free radicals at this temperature.

high temperature.

  The free radical initiators which can be used are peroxides, hydroperoxides and azo compounds, the preferred initiators being those whose point

  boiling point is greater than about 100 C and decomposes

  thermally pose in the range of grafting temperatures to give said free radicals. As representative examples of these free radical initiators, one can

  mention azobutyronitrile, 2,5-dimethyl-hex-3-peroxide

  tertiary yne-2,5-bis-butyl (sold under the trade name "Lupersol lwO") or its analogue with hexane,

  tertiary dibutyl peroxide and dicumyl peroxide.

  The initiator is used at a rate of about 0.05% to about

  i%, based on the total weight of the polymer solution.

  The ethylenically unsaturated carboxylic substance, for example maleic anhydride, is used in an amount of from about 0.01% to about 10%, preferably 0.1 to 2.0%, based on the weight of the whole of the initial solution of oil. The above carboxylic substance and the free radical initiator are used in a weight ratio of from 1.0: 1 to 30: 1,

preferably 3.0: 1 and 6: 1.

  The grafting is preferably carried out under an inert atmosphere, for example under a nitrogen protective atmosphere. Although the grafting can be performed in the presence of air, the yield of the desired graft polymer then decreases compared to the case of grafting under an inert atmosphere. The inert atmosphere must be substantially free of oxygen. The grafting time is from about 0.1 to 12 hours, preferably from about 0.5 to 6 hours, and most preferably from 0.5 to 3 hours. The grafting reaction lasts at least about 4 times, preferably at least about 6 times, the half life of the free radical initiator at the reaction temperature used, for example 2 hours at 1600C and 1 hour at

  1700C with 2,5-dimethyl-hex-3-yn-2,5-bis (t-butyl)

peroxide).

  In the grafting process, the copolymer solution is first heated to the temperature

  grafting and the carboxylic substance as well as the initial

  are then added, with stirring, although they can also be added before heating. When the reaction is complete, the excess acidic substance is removed by purging with an inert gas,

for example a nitrogen sweep.

  Maleic anhydride or other carboxylic substance

  The method used in the grafting step is grafted onto both the polymer and the solvent of the reaction system. The weight percentage grafted to the polymer is normally higher than that grafted onto the oil due to the greater reactivity of the polymer in grafting. However, the exact partition coefficient between these two substances depends on the nature of the polymer and its reactivity, the reactivity and the type of oil and also the concentration of the polymer in the oil. The partition coefficient can be determined experimentally from infrared spectrum analyzes of the dialyzed product in oil and polymer fractions, measuring in each of them the absorption

infrared peak of anhydride.

  The grafting is preferably carried out in a mineral lubricating oil which does not need to be removed after the grafting step, but which can be used as a solvent in the subsequent reaction step between the graft polymer and the polyfunctional substance and like

  solvent of the final product to form the concentrate.

  The oil on which grafted carboxyl groups are attached, for example anhydride groups

  maleic, will also be transformed into the corresponding derivatives.

  during its reaction with the hetero primary amine

  substituted. If desired, the partition coefficient between the imidated grafted polymer and the imidated, grafted oil can be determined by dialysis in polymer and oil fractions and infrared analysis or nitrogen analysis of said fractions. Unfortunately, it has become apparent that the grafted oil can give rise to a cloudiness when it becomes excessively

  polar for example from the formation of derivatives.

  When the solution-grafting step is carried out in the presence of a decomposable peroxide at elevated temperature, it is carried out without degradation of the chain length (molecular weight) of the ethylene-containing polymer. Molecular weights and degradation can be evaluated by determining the thickening activity of the polymer. The thickening activity (TE) is defined as the ratio between, on the one hand, the weight percentage of a polyisobutylene (sold as an oil solution by Exxon Chemical Co. under the trade name "Paratone NU") having a molecular weight 20,000 according to the method

  Staudinger, which is required to thicken a lubricating oil.

  neutral solvent-borne mineral fiber having a 150 seconds universal Saybolt viscosity at 37.8 C, a viscosity number of 105 and a pour point, according to ASTM, of -17.8 C ("Solvent 150 Neutral "), up to a viscosity of 124 x 10-7 m2 / s at 98.9 C and, on the other hand, the weight percent of a test copolymer which is required to thicken the same oil up to at the same viscosity, at the same temperature. The thickening activity is related to (Mn) and is a suitable and useful means of measurement for the preparation of lubricating oils of

different qualities.

  Usable primary alkyl (hetero substituted alkyl) amines are characterized by an alkyl group having 8 to 20 carbon atoms, the total number of carbon atoms being from 10 to 70 and the number of nitrogen atoms from 1 to 11, these amines preferably responding to the general formula:

H

  Wherein s is an integer from 2 to 6, t is an integer from 0 to 10 and Y is a substituent group selected from the following : -NR (amino group),! R 'S-R (thiol group), HO-it-O-R (ether group), -C-C-R (keto group),

R '

  H -N- (CH2) 2-N-C-R (imidazoline group) and H C N H2CI

C

  ## STR2 ## (N, S and O have the usual meanings, R represents a C 8 to C 20 alkyl group and R 'of hydrogen or an alkyl group

lower in C1 to C9.

  The following description illustrates the amines

  usable according to the invention, which, for ease of presentation, will be classified according to the meanings given above for the group Y of the general formula:

  1. Y is an amino group, that is, -N-R-

  ! R 'which gives a product such as aminopropyloleylamine

  formula C18H35NH- (CH2) 3NH2. This type of reaction substance

  It is easily obtained by cyanoethylation and subsequent reduction of oleylamine. Thus, the use of starting materials ranging from C8H17NH2 (octylamine) to C20H41NH2 (eicosylamine) by cyanoethylation using acrylonitrile and subsequent reduction can provide

  amines such as aminopropyloctylamine, aminopropyl-

  nonylamine, etc. By repeating the cyanoethylation followed by the reduction, the previously obtained product, for example aminopropyloleylamine, gives an amine of the formula C 18 H 35 LNH- (CH 2) 3) 2 NH 2, while additional steps of cyanoethylation followed by reduction increase the parameter t , of the general formula, of a unit at each stage. The cyanoethylation followed by the reduction process is applicable to each of the following categories: 2. Y is a thiol group, i.e. -S-R. The useful primary amine compounds which comprise this group are obtained by cyanoethylation, followed by a reduction step, of an alkyl mercaptan, for example C 8 H 17 SH at C 20 H 41 SH, as

  illustrated by lauryl mercaptan which gives the amino sulfide

  propyl and lauryl or by stearyl mercaptan which gives (after two steps) the aminopropylaminopropyl sulfide and

of stearyl.

  3. Y is an ether group, i.e., -O-R. In this case, the cyanoethylation and the reduction apply to an alcohol, for example tridecyl alcohol, and extends to alcohols having 8 to 20 carbon atoms. Such amine li

  primary ingredient is, for example, the amino ether

  propyl and tridecyl C13H27-O- (CH2) 3NH2 sold by the Armak Company of Chicago, Illinois under the trade name "Armeen EA-13". All C 8 to C 20 alcohols can be cyanoethylated and reduced, in as many steps as desired, to obtain primary amines:

  (C 8 -C 20) O-O- (CH 2) 3 -NH 10 O (CH 2) 3 NH 2 useful for the invention.

  4. Y is a keto group, that is to say:

-C-C-R

  I R 'for example that o R' is a group C8H17 and R a group

  C9H19, which corresponds to 9-aminopropyl-10-nona

decanone: O H

C9H19-C-C- (CH2) 3NH2

  8H17 obtained by adding acrylonitrile, in basic medium, to the nonadecanone (Michael addition) followed by

reduction of the cyano group.

  5. Y is an imidazoline group, i.e.

-NH- (CH2) 2-N-C-R

H C N

H2C \ N

  C H2 which is in fact of the type Y = -N-R o R 'is hydrogen and R is the R R'

  reaction product of oleic acid and diethylene

  triamine which condenses to give the imidazoline nucleus. Subsequent cyanoethylation using acrylonitrile, followed by reduction, using, for illustrative purposes, the

  reaction product above, gives aminopropylamino-

  ethylolylimidazoline of formula: -H g C - N (CH 2) 2 - N - (CH 2) 3 NH 2

N CH2 H

  C H2 The diversity of primary amines is evident during condensation with imidazoline, given the diversity

  C7-C19 acids and alkylene polyamines.

  6. Y is a glycol ester group, i.e.

O- (CH2) 2-O- (CH2) 2-O-C-R

  of which the primary amino derivative is available as a glycol ester of the trademark "Kessco" from the Armak Company of Chicago, Illinois. When R is C18H37, the primary amine can be easily produced by cyanoethylation and reduction of the monostearate of

  diethylene glycol to give the aminopropyl monostearate

  diethylene glycol. Other glycol esters available

  from the Armak Company are ethylene monostearate

  glycol and propylene glycol monostearate each of which can be cyanoethylated and reduced to give useful amines in

the scope of the invention.

  The process for the formation of multifunctional derivatives (formation of imide derivatives) will now be described: The grafted polymer, preferably in solution, can be easily reacted with the above-mentioned primary alkyl (heterosubstituted alkylene) amines and their mixtures, by mixing them together. with this graft polymer and heating at a temperature of about 1000C to 250 C for minutes to 30 hours, preferably 10 minutes to 10 hours,

  usually about 15 minutes to about 3 hours.

  Removal of the water makes the imidation reaction complete.

  From 0.5 to 1.5, preferably 1, molar equivalent of said primary amine relative to the content of groups is used.

  grafted dicarboxylic acid, for example the content of anhy-

  maleic dride grafted. For example, with an ethylene-propylene copolymer of molecular weight (Mn) of about 000, corresponding to a thickening activity of about 2.1, which has on average four maleic anhydride groups, preferably about 2 to 4 moles are used. primary amine, per mole of graft copolymer. It has been found that the use of at least about 0.5 molar equivalents per mole of maleic anhydride grafted gives a solution in

  oil with improved clarity, although 1 equiva-

  slow molar represents an optimal amount for the

limpidity (absence of trouble).

  The water-soluble, nitrogen-based graft polymers prepared in accordance with the invention may be incorporated in an extended range of, for example, from 0.001 to 50% by weight, preferably from 0.005 to 0.005% by weight.

  20%, in an oily substance, such as a lubricating oil,

  a fuel or hydrocarbon fuel. When said polymers are used in lubricating oil compositions, for example diesel engine or automobile crankcase lubricating oils, the concentrations used range from about 0.01 to 20% by weight, for example 0, 1 to 15.0% by weight and preferably 0.25 to 10.0% by weight of the overall composition. The lubricating oils to which the products of the invention may be added include not only hydrocarbon oils derived from petroleum, but also synthetic lubricating oils such as esters of diacids and complex esters prepared by esterification of monoacids, polyglycols,

diacids and alcohols.

  The imide type graft polymers of the invention may be marketed and / or used in the form of a concentrate, for example in a proportion of about 10% to about 50% by weight, preferably 15% to 49%, in an oil, for example a mineral lubricating oil, for

facilitate their handling.

  The above lubricating oil concentrates and compositions may contain other customary additives, such as dyes,

  pour point, anti-wear agents, anti-

  oxidizers, other agents for improving the

  viscosity, dispersants and the like.

  The following examples are given, as a non

  limiting to better illustrate the method according to the invention.

  In these examples, as throughout this specification, all parts are by weight unless otherwise indicated and the nitrogen content is determined by the

Kjeldahl method.

EXAMPLE 1

  Preparation of an ethylene-propylene-succinic anhydride copolymer 99.9 kg of an oil concentrate containing about 15% of ethylene-propylene copolymer (TE 2,1) are introduced into a reactor of 189 l, heated to 121 Under nitrogen and purged with nitrogen for one hour. Then 1723 kg of maleic anhydride are introduced into the stirred reactor and the temperature is raised to 171 ° C. At this temperature, 0.43 kg of the product of the trade name "Lupersol 130" is added and the process is continued. stirring for 1.5 hours. Finally, the reaction medium is purged with nitrogen for 1.5 hours to remove any unreacted maleic anhydride. The product obtained is diluted with a mineral oil

  up to a polymer content of about 15%.

EXAMPLE 2

  300 g of a concentrate in oil at about 15% decopolymethylenepropylene-succinic anhydride (0.04749

  mole of maleic anhydride grafted), prepared as described above

  above, are introduced into a one-liter, four-necked flask, heated to 170 ° C under a nitrogen atmosphere and then subjected to intense purging for one hour. The solution is then reacted with 12.2 g (0.04749 mol) of the product of the name "Armeen EA 13" from the Armak Company, which is aminopropyl and tridecyl ether,

  C13H27-O- (CH2) 3NH2, and stirred for an additional period of

  2 hours. The solution is finally diluted with 128 g of oil "S 100 N" to obtain a final solution at 10.5%

by weight of active ingredient.

EXAMPLE The reaction is identical to that of Example 2, except that

replaces aminopropyl ether and

  tridecyl with 15.0 g (0.04749 mol) of N-aminopropyl-

morpholine (NAPM).

EXAMPLE 4

  The reaction of this example is identical to that of Example 2, except that the "Armeen EA-13" is replaced by 0 g (0.04749 mol) of the commercial product.

  "Duomeen EA-13" from the Armak Company which is the amino ether

  propylaminopropyl and tridecyl of formula:

C13H27- - (CH2) 3-NH- (CH2) 3 -NH2.

EXAMPLE 5

  The reaction is identical to that of Example 2, except that the reaction mass is aminated with a mixture of 1: 1 (in moles) of 3.40 g (0.023 mole) of NAPM and 6.10 g

  (0.023 moles) of amino and tridecyl ether.

EXAMPLE 6

  The reaction is identical to that of Example 2, except that the reaction mass is aminated with a 1: 1 (molar) mixture of 3.40 g (0.023 mol) of NAPM and 7.5 g

  (0.023 moles) bis (aminopropyl) ether and tridecyl ether.

EXAMPLE 7

  The reaction is identical to that of Example 5, except that the aminopropyl and tridecyl ether is first introduced, the reaction mass being stirred for 30 minutes before addition of NAPM. After addition of the NAPM, the reaction mass is stirred for 45 minutes before final dilution to obtain a product at 10.5% by weight.

weight of active ingredient.

EXAMPLE 8

  The reaction is identical to that of Example 6 except that the bis (aminopropyl) and tridecyl ether is first added, the reaction mass being stirred for 30 minutes before addition of the NAPM. After addition of the NAPM, the reaction mass is stirred for an additional period of 30 minutes before final dilution until

  5% by weight of this active ingredient.

EXAMPLE 9

  The products of Examples 2 to 8 are subjected to a determination of clarity, that is to say of absence of

  disturbance, using, for each sample, a color

  nephelometer meter ("Nephocolorimeter Model 9") sold by Coleman Instrument Corporation of Maywocd, Illinois. The results are given in Table 1, the smaller number representing lower turbidity

(greater clarity).

TABLE I

  Blister Index (Nephelometric) Example 2 33

3,230

N 4 52

230

6,205

a 7,101

N 8 156

  The results of Table I show that the products according to the invention (Examples 2 and 4) lead to multifunctional viscosity index improvers, in the form of concentrates, which are clear, clear and stable, while the product obtained from a usual polyamine such as NAPM (Example 3) leads to a multifunctional agent for improving the

  viscosity which contains a haze or veil.

  In addition, the proper addition of the reaction polyamines, i.e., the sequential addition of the haze-removing polyamine and then the non-acting polyamine, results in solutions of the multifunctional agent. improvement in the viscosity index (MFVI) in mineral oil which have improved clarity, i.e., lower turbidity (compare Example 5 to Example 7 and Example 6 to Example 8). These results indicate that the polyamine preferentially reacts first with the turbid products, i.e., the grafted oil molecules, and then with the graft polymer, which is probably due to the differences of solubility in the mineral oil between the oil which has been grafted and the

graft copolymer.

EXAMPLE 10

  Inhibition test of oxidation products.

  The product of Example 4 is evaluated at the oxidation product inhibition (VIB) bench and the results

  are compared to those obtained using a multi-agent

  Viscosity index improving functional system sold commercially under the name "LZ 3702" by Lubrizol Corp. from Cleveland, Ohio, which is believed to be a styrene-maleic anhydride copolymer esterified by

  short chain and amine alcohols by means of a polyamine.

  In an inhibition test of the oxidation products, each test sample is constituted by g of lubricating oil containing 0.07 g of additive concentrate (at 50% of active ingredient), so that the test sample contains 0.35% by weight of additive. The 9.93 g of the oil to be evaluated, to which the additive is mixed, consist of an industrial lubricating oil removed from the engine of a taxi which has run for 3219 km with said lubricating oil. Each 10 g sample is matured overnight at about 140 ° C. and is then centrifuged to remove the sludge. The supernatant fluid of each sample is subjected to a heating cycle from about 150 ° C. to room temperature for a period of 3.5 hours at a frequency of about 2 cycles per minute. During the heating phase, the gas containing a mixture of about 0.7% by volume of SO 2 and 1.4% by volume of NO, the residual percentage representing air, is bubbled through the

  test samples while during the cooling phase

  At the same time, the steam is made to pass bubble-bubble through the test samples. At the end of the duration of the test, which can be repeated as needed to determine the inhibitory effect of any additive, the wall surfaces of the test flasks in which the samples are contained are observed. visually. The vials in which the samples are contained are visually evaluated for inhibition of formation of the oxidation products. The amount of oxidation products deposited on the walls is evaluated using degrees of 1 to 7, the highest degree corresponding to the highest amount of oxidation products. It has been found that this test confirms the results obtained with regard to the formation of

  oxidation products as a result of the MS-VC engine test.

  The results of the VIB test of the product of Example 4 and "LZ 3702" are given in Table II below.

TABLE II

Degree VIB Example 4

"LZ 3702" 5

  The results of the VIB test indicate that the product of Example 4 is superior in the inhibition of

  the formation of oxidation products, to the multi-agent

  functional improvement of the industrial viscosity index

  370. The products of the invention make it possible to obtain clear and clear mineral oil solutions, in particular concentrates of multifunctional agents for improving the viscosity index. which are derivatives prepared in a single step and endowed with a product inhibition activity

  significantly higher oxidation than that of a multi-agent

  functional improvement of the viscosity index of industrial type.

EXAMPLE II

Tests on engines.

  The "Duomeen EA-13" of Example 4 is compared with the NAPM of Example 3 in a 240 hour test in a "1H2" single cylinder supercharged diesel engine.

  Caterpillar "using the conditions of the ASTM-

  STP509A in which no dispersant is used. We

gets the following results.

TABLE III

NAPM "Duomeen"

  Total weight of degradation products

  (WTD) 1204 294% throat filling (TGF) 38 52 The WTD value is the most significant of the values; the lower the value, the cleaner the motor. It is found that the "Duomeen" is much higher since it gives a degradation rate much lower than the NAPM. The TGF value corresponds to a slight

  advantage for the NAPM, but it is of little importance.

  The two substances are also compared in the L-38 engine test, which uses a single-cylinder gasoline engine in which the oil oxidation and bearing corrosion properties are evaluated using the NI 3405 method. Federal Trials (United States of America). The degrees of formation of oxidation products on the piston liner are 9.7 for the "Duomeen" and 7.7 for the NAPM, respectively. In these tests, the degree 10 corresponds to a clean engine while the degree 0 denotes a full engine of calamine. Thus, the invention may be described as relating to a composition comprising an oil-soluble imide type ethylene copolymer having a number average molecular weight (Mn) of from 700 to 500,000 (preferably from 1,000 to 1,000,000). and 250,000) and which has, on average, 2 to 20 (preferably 4 to 10) graft imido groups per molecule, 50 to 100 mol% of said imido groups being a (C 8 -C 20) alkyl (heterosubstituted alkylene) primary amine substituted on nitrogen; under these conditions, this composition is exempt

  turbidity and stabilization of its viscosity is improved.

  It goes without saying that the present invention has been described only for explanatory and non-limiting purposes and that any useful modifications can be made to it.

without leaving his frame.

Claims (9)

  1. Process for the preparation of a solution, in an oil, of a viscosity index-improving polymer having sludge dispersion properties, by grafting, in solution in a mineral oil, of maleic anhydride onto a copolymer containing about 30 to 80% by weight of ethylene and about 20 to 70% by weight of at least one C3 to C28 alpha olefin, said copolymer having a number average molecular weight of from about 10,000 to 250,000, to obtain on average two to twenty maleic anhydride groups per copolymer molecule, this solution in mineral oil containing about 1 to 50% by weight, based on the total weight of solution, of said copolymer, characterized in that a graft is fraction of said maleic anhydride on said polymer and another maleic anhydride fraction on said oil, so as to obtain a grafted product, and then the grafted product is reacted with 0.5 to 1.5 equivalents molar concentration, expressed with respect to the reacted maleic anhydride, of a C8-C20 alkyl heterosubstituted primary alkyleneamine having a total number of carbon atoms of from 11 to 70 and a number total of nitrogen atoms from 1 to 11.   2. Method according to claim 1, characterized in that the aforementioned grafting is performed by means of a free radical initiator at a temperature of about 100 at 250 C.   3. Process according to claim 1 or 2, characterized in that the C8-C20 alkyl heterosubstituted alkylene-polyamine is of the general formula: HY - ((CH2) s - N - t - (CH2) s --NH2 in which s is an integer from 2 to 6, t is an integer from 0 to 10 and Y is a substituent group selected from the following groups: HO H ! he I   -N-R, -S-R, -O-R, -C-C-R, -N- (CH 2) 2 -N T-C-R, I i R 'R' H2C N C   H2 o and -OCH2CH2OCH2CH2O-C-R '; Where N is nitrogen, S is sulfur, O is oxygen, R is C8 to C20 alkyl and R 'is   hydrogen or a C1-C9 alkyl group.   4. Method according to claim 3, characterized in that Y is a group -O-R.   5. Method according to one of claims 1 to 4,   characterized in that the heterosubstituted alkylene polyamine is aminopropyl and tridecyl ether or diisopropyl ether. bis (aminopropyl) and tridecyl.   6. Method according to one of claims 1 to 5,   characterized in that the above-mentioned C8-C20 alkyl heterosubstituted alkylene polyamine is reacted in an amount of less than one molar equivalent per grafted maleic anhydride group and that the remaining maleic anhydride groups are then reacted with an alkylenepolyamine.   7. Method according to claim 6, characterized   in that the alkylenepolyamine is N-aminopropyl- morpholine.   8. Solution in the oil of an agent for improvement   viscosity index, characterized in that it is   prepared by the process according to one of claims 1 to 7.   A lubricating oil composition, characterized in that it comprises a main amount of lubricating oil and an amount of the oil solution of claim 8 sufficient to impart to said composition   viscosity index improving properties.