WO1992017437A1

WO1992017437A1 - Poly(1,6-hexanediamine)s and related compounds and their use as lubricating oil additives

Info

Publication number: WO1992017437A1
Application number: PCT/GB1992/000465
Authority: WO
Inventors: Stephen James Cook; Christopher Payne
Original assignee: Bp Chemicals Limited
Priority date: 1991-03-28
Filing date: 1992-03-16
Publication date: 1992-10-15
Also published as: GB9106762D0; MX9201359A; AU1365592A

Abstract

A compound of the formula (I): X[D-NH]x[D-N(DNH2)]yDY wherein (x+y) has a value in the range from 1 to 19, y is zero or an integer, D is (CH2)6, X and Y are independently either -NH2 or -OH, and when y is greater than 1, the [D-N(DNH2)] groups are randomly distributed throughout the polymer chain, or a mixture of at least two compounds of formula (I) have been prepared. The compounds are prepared by deaminative polymerisation in the presence of a transition metal catalyst. These compounds can be used to prepare lubricating oil additives, in particular polyisobutenyl succinimides.

Description

POLYd.6 HEXANEDIAMINE)S AND RELATED COMPOUNDS AND THEIR USE AS LUBRICATING OIL ADDITIVES

The present invention relates to novel poly(1,6-hexanediamine) and related compounds, to dispersant additives derived therefrom and to lubricating oil compositions incorporating the dispersant additives. A well known class of dispersant for use in lubricating oil compositions is that formed by the reaction of a hydrocarbyl-substituted succinic acylating agent, for example a polyisobutene succinic anhydride, and an amine, particularly a polyamine and more particularly a polyalkylene polyamine, for example triethylene tetramine (TETA) or tetraethylene pentamine (TEPA). For a review of the prior art on the production of such dispersants reference may be made to GB-A-1565627 which itself covers a lubricating composition comprising a major amount of oil of lubricating viscosity and a minor amount of one or more carboxylic derivatives produced by reacting at least one substituted succinic acylating agent with a reactant selected from (a) an amine having within its structure at least one H-N« group, (b) an alcohol, (c) a reactive metal or reactive metal compound, and (d) a combination of two or more of any of (a) to (c), the components (d) being reacted with said one or more substituted succinic acylating agents simultaneously or sequentially in any order, wherein said substituted succinic acylating agent(s) consist of substituent groups and succinic groups wherein the substituent groups are derived from polyalkene, said polyalkene having an M_n value of 1300 to 5000 and a M_w/M_n value of 1.5 to 4, said acylating agent(s) having within their structure an average of at least 1.3 succinic groups for each equivalent weight (as hereinbefore defined) of substituent groups.

Although polyaraines, such as TETA and TEPA, impart good dispersancy properties to, for example, polyisobutenesuccinimide dispersants formed from them, the search continues for improved dispersancy and better economics. Moreover, the use of polyamines, such as TETA and TEPA, in the production of succinimide dispersants contributes to oil seal swelling problems in engines using lubricating oils containing them. We have found that dispersancy can be improved without any deterioration in oil seal swelling by the use, in the preparation of dispersants from a hydrocarbyl substituted succinic acylating agent, of a poly(l,6-hexanediamine) and related compounds in place of, for example TETA and TEPA.

Accordingly, the present invention provides either a compound of the formula:-

X[D-NH]_χ[D-N(DNH₂)]_yDY (I) wherein

(x+y) has a value in the range from 1 to 19, y is zero or an integer, D is (CH₂)₆,

X and Y are independently either -NH₂ ^or -OH, and when y is greater than 1, the [D-N(DNH₂)] groups are randomly distributed throughout the polymer chain, or a mixture of at least two compounds of the formula (I). In the formula (I), X and Y are preferably exclusively -NH . Preferably x+y<10, more preferably x+y<5; for example x+y=2. y is preferably zero; where =Y=NH2, the compound is a poly(l,6-hexane diamine).

An example of a poly(l,6-hexanediamine) has the formula: (A) H₂N(CH2)6NH(CH₂)6NH(CH2)6NH2

An example of a poly(l,6-hexanediamine) mixture comprises the compounds:-

(B) H₂N(CH2)6NH(CH₂)6NH2, and (A) H₂N(CH₂)₆NH(CH₂)₆NH(CH₂)₆NH₂ In another aspect the present invention provides a process for the production of polyv.1,6-hexanediamine) of the formula (I), or a mixture thereof, which process comprises contacting 1 ,6-hexanediamine with a transition metal catalyst under deaminative polymerisation conditions. 1,6-Hexanediamine is a large tonnage commercial material, being a precursor for Nylon 66, and is widely available. It is manufactured by hydrogenation of adiponitrile, which, in turn, is produced from either adipic acid, butadiene or acrylonitrile. It may be used in the deaminative polymerisation process without further purification. In the process for the production of a polyd,6-hexanediamine) or related compound or a mixture thereof there is used a transition metal catalyst. A suitable transition metal is nickel, which may be employed for example in the form of Raney nickel. Alternatively, the nickel may be supported on a suitable support, for example alumina. In order to minimise the potential for hydrolysis of the product, it is preferred to employ catalysts in a substantially anhydrous form. This may suitably be achieved by washing the catalyst prior to use with, for example, 1,6 hexanediamine.

Deaminative polymerisation conditions include the use of an elevated temperature, suitably in the range from 100 to 230*C, typically in the range from 130 to 210*C. The temperature and the reaction time are factors which can affect both the molecular weight and the structure of the product.

It is very much preferred to operate the process in an open system, that is a system in which evolved gas is allowed to vent. The process being a deaminative polymerisation, it is highly desirable that the ammonia evolved does not remain in contact with the reactants.

In another aspect the present invention provides a dispersant additive suitable for use in lubricating oil compositions which additive is obtainable by reacting at elevated temperature either a poly(1 ,6-hexanediamine) having the formula (I) or a mixture thereof, with a hydrocarbyl-substituted succinic acylating agent.

Suitable hydrocarbyl-substituted succinic acylating agents are described in the aforesaid GB-A-1565627. A preferred acylating agent has the formula:-

wherein R^ is an alkyl or alkenyl group derived from a polyolefin, preferably a polyisobutene.

The substituent R^z may suitably have a number average molecular weight in the range from about 500 to about 5000, preferably from about 700 to about 2500. R^ may also be a succinic anhydride moiety, in which case the compound of formula (V) would be a dianhydride.

A mixture of hydrocarbyl-substituted succinic acylating agents may be employed if desired. The above mentioned acylating agent would in practice have a molecular weight distribution and the average number of succinic groups per molecule would be greater than 1 but not necessarily an integer. The average number of succinic groups per molecule is preferably in the range 1 to 2, more preferably between 1.2 and 1.7 for example 1.3.

The ρoly(l,6-hexanediamine) and the acylating agent are suitably reacted in proportions such as to produce either the mono- bis- or tris- succinimide derivative. The charge mole ratio of polyamine to acylating agent can be varied to give the desired product. The charge mole ratio is preferably in the range 0.1 to 1.1 preferably 0.2 to

1.0; in the case of the tris succinimide, the ratio is preferably about 0.3, in the case of the bis succinimide it is preferably about

0.5 and in the case of the mono succinimide it is preferably about

1.0. However, it will be understood that each of the "mono-", "bis-" and "tris" succinimides will in reality be a mixture of products with the mono-, bis- and trisuccinimides being the predominant product respectively.

Using mixtures containing poly(l,6-hexanediamines) of different molecular weights, such as may be obtained by the deaminative polymerisation process of hereinbefore described, it is preferred to remove unreacted monomer from the mixture before reacting the mixture with the hydrocarbyl-substituted succinic acylating agent.

Generally, the reaction will be effected in the presence of a solvent for the reactants. In view of the intended use of the product, a preferred solvent is a lubricating oil. The lubricating oil may be an animal, vegetable or mineral oil. Suitably the lubricating oil may be a petroleum-derived lubricating oil, such as a naphthenic base, paraffin base or mixed base oil. Solvent neutral oils are particularly suitable. Alternatively, the lubricating oil may be a synthetic lubricating oil. Suitable synthetic lubricating oils include synthetic ester lubricating oils, which oils include diesters such as di-octyl adipate, di-octyl sebacate and tri-decyladipate, or polymeric hydrocarbon lubricating oils, for example liquid polyisobutenes and poly-alpha olefins. Alternatively, the solvent may be an inert hydrocarbon, suitably a liquid paraffin. The elevated temperature may suitably be in the range from 80 to 230, preferably from 120 to 210*C.

A suitable poly(l,6-hexanediamine) for use in the formation of dispersant additives according to the invention is that hereinbefore denoted as (A) or a mixture of (A) and (B) as hereinbefore denoted. In another aspect the present invention provides an additive concentrate comprising a lubricating oil and a dispersant additive as hereinbefore described.

The lubricating oil may be any natural or synthetic oil. It may suitably be any of the lubricating oils as hereinbefore described with reference to the dispersant additive.

Suitably the additive concentrate may contain up to 80% by weight based on the total weight of the composition of the dispersant additive. In a final aspect the present invention provides a finished lubricating oil composition which composition comprises a major proportion of a lubricating oil and a minor proportion of the additive concentrate as hereinbefore described.

The same, or a different, lubricating oil to that in the concentrate composition may be used in the final lubricating oil composition.

Into the lubricating oil composition there may also be incorporated any of the conventional additives normally employed, which additives include antioxidants, detergents, extreme pressure/anti-wear agents and viscosity index improvers. It is an advantage of the present invention that, because the dispersant composition of the invention has viscosity index properties, less of the conventional viscosity index improver may be required.

Alternatively, some at least of the aforesaid additives may be incorporated into the additive concentrate.

The lubricating oil composition may be used for any lubricating application, including automotive and marine use.

For use as an automobile engine lubricant, sufficient of the additive concentrate as to provide up to 10Z by weight of the dispersant additive in the lubricating composition may be employed.

For use as a marine engine lubricant, sufficient of the additive concentrate as to provide up to 10Z by weight of the dispersant additive in the lubricating composition may be employed.

The invention will now be further illustrated by reference to the following Examples.

(a) Preparation and characterisation of poly(l,6-hexanediamine) (i) Preparation

Examples 1-4 A five-necked one litre flanged flask was fitted with an efficient double coil condenser, an overhead stirrer, a thermocouple well, and a nitrogen purge, leaving one neck free for the addition of reactants. The purged gas passed out of the top of the condenser, to sparge into an indicator solution contained in a magnetically stirred three litre flask fitted with a burette for addition of acid. The diamine (generally 400-500g) and Raney nickel catalyst (5%w/w) were placed in the reaction flask, and c_a one litre of a dilute solution of boric acid buffered methyl red/bromocresol green placed in the indicator flask. The reaction mixture was stirred under a gentle flow of nitrogen and heated to the desired temperature, selected from the range 130-150*C. The indicator changed from red to green when the solution went from acidic to alkaline. Thus the amount of ammonia evolved in the reaction could be determined by titration with an acid. Also, the rate of ammonia evolution could be determined by adding an aliquot of acid to the indicator solution and observing the neutralisation time. The acid used was generally 3-5M H Sθ .

The reaction was heated for the required time, with sampling and then allowed to cool. The product was dissolved in methanol (ca 300ml) and filtered twice; once through a sinter funnel to remove the bulk of the Raney nickel, and again through a pad of silica gel to remove any finely dispersed particles. Volatiles were removed in vacuo and the products were analysed by ^H and ^C NMR.

The reactants, conditions and yields for the deaminative polymerisations are summarised in Table 1 below.

Table 1

1 Based on final weight and ammonia loss indicated by titration.

² Some unreacted 1,6-hexanediamine was lost as volatiles during the drying stage, accounting for the slightly lower yields.

(ii) Product Structure

The analyses indicated that the products were mixtures of linear poly(l ,6-hexanediamine)s, with very small amounts of a similar species wherein a primary amine group has been replaced by a hydroxyl group. The average number of units of 1,6-hexanediamine (n) in the products as determined by the various analytical techniques are summarised in Table 2 below.

Table 2

There is relatively good agreement between the measurements of ammonia evolved and the *H NMR data. The ¹³C N R data gives a value of n somewhat lower in each case. This is probably due to the long relaxation times of *- C atoms, which lead to inaccuracies in their integration.

The products of Examples 1, 3 and 4 have similar compositions, being synthesised under similar conditions to demonstrate the reproducibility of the Examples. They are mixtures of the following species:-

(1) H N(CH₂)6NH minor component

(2) H₂N(CH₂)6NH(CH₂)6NH₂ major component

(3) H2N(CH₂)6NH(CH₂)₆NH(CH₂)₆NH₂ major component

(4) H₂N[(CH2)6NH]_m(CH₂)₆NH(CH₂)6NH₂ minor component

(5) H₂N[(CH₂)₆NH]_m(CH₂)6NH(CH₂)₆OH minor component The product of Example 2 contains polymer (4) as its major component, where m = 3, 4 and 5. Its minor components are probably the higher and lower chain length polyamines, with small amounts of polyraer(5) wherein m = 3, 4 and 5.

(b) Preparation of dispersant additives Example 5

A 3-neck, 5 litre flask was charged with polyisobutene-succinic anhydride (PIBSA) (M_n of polyisobutene substituent - 1000) (2400g) and poly(l,6-hexanediamine) from Example 1 (120g), i.e. a theoretical charge mole ratio (CMR) of 0.3, as measured by the weights of the starting materials. The flask was fitted with an overhead stirrer, a thermocouple well and a condenser. The reaction was stirred at 180^*C for 3 hours, and then the water generated by the reaction was stripped off under vacuum (29 inches Hg) at 180*C for 1 hour. The product was fully compatible with mineral oil. A nitrogen determination on the product showed the total nitrogen to be 0.77Z and the basic nitrogen to be 0.102.

(c) Testing of dispersant additives (i) Petter AVB engine test

The product of Example 5 was tested in a Petter AVB engine test at 3Z and 5Z dispersant concentration. The results of the test are given in Table 3. A Petter AVB Pass - 60.

Also given in Table 3 are the results obtained for 3Z, 5Z and 7% solutions of a variety of prior art polyisobutene succinimides identified as follows: (A¹) - the polyisobutene succinimide resulting from the reaction of a polyisobutene succinic anhydride (PIBSA) (wherein the polyisobutene substituent has M_n = 1000) and tetraethylene pentamine (TEPA) at a CMR of 0.9.

(B¹) - the polyisobutene succinimide resulting from the reaction of PIBSA (M_n polyisobutene = 1000) and triethylene tetramine

(TETA) at a CMR of 0.9. (C^) - the polyisobutene succinimide resulting from reaction identical to A¹ except the CMR Was 0.5, not 0.9. (D^) - the polyisobutene succinimide resulting from reaction identical to C* except that in the starting PIBSA the polyisobutene substituent is derived from a mixture of polyisobutenes having M_ns of 1000 and 2400 to provide an average M_n of about 1840 and the CMR was 0.35, not 0.5.

Table 3

It can be seen from the results presented in Table 3 that the dispersancy, as measured by the Petter AVB test, of the dispersant additive of the invention is significantly better than the prior art sucicnimides at 3Z concentration.

(ii) VW Seals Swell Test

At 5Z concentration the performance of the dispersant of Example 5 was no worse than that of A¹, B¹ and C¹, but inferior to that of D*.

Claims

Claims :

1. A compound of the formula:-

X[D-NH]_x[D-N(DNH₂)]_yDY (I) wherein (x+y) has a value in the range from 1 to 19, y is zero or an integer, D is (CH₂)₆,

X and Y are independently either -NH₂ or -OH, and when y is greater than 1, the [D-N(D H )] groups are randomly distributed throughout the polymer chain, or a mixture of at least two compounds of the formula (I).

2. A compound as claimed in claim 1 wherein y is zero.

3. A compound as claimed in either claim 1 or claim 2 wherein x + y is less than 5.

4. A compound as claimed in any one of the preceding claims wherein x + y is less than or equal to 2.

5. A compound claimed in any one of the preceding claims wherein X = Y = NH₂.

6. A process for preparing the compounds as claimed in any one of the preceding claims which comprises a deaminative polymerisation in the presence of a transition metal catalyst.

7. A process as claimed in claim 6 wherein the transition metal catalyst is Raney Nickel.

8. A lubricating oil additive which comprises the reaction product of a compound as claimed in any one of claims 1 to 5 and an acylating agent of the formula

0 II H₂C — C^

0

- / R² CH— C

II 0 wherein R² is an alkyl or alkenyl group derived from a polyolefin.

9. A lubricating oil additive as claimed in claim 8 wherein R² is derived from polyisobutene.

10. A lubricating oil additive as claimed in either claim 8 or claim

9 wherein R² has a number average molecular weight in the range

500-5,000.

11. A lubricating oil additive as claimed in claim 10, wherein R- has a number average molecular weight in the range 700-2,500.