NO821107L - POLYALKENYL BIS (SUCCINANHYDRIDES OR ACIDS) AND THEIR PREPARATION AND USE - Google Patents

Description

The invention generally relates to polyalkenyl succinic anhydrides or acids, and in particular polyalkenyl bis (succinic anhydrides or acids), hereinafter referred to as PABSA, compositions containing PABSA, progress

method for the production of PABSA, transfer of PABSA to derivatives thereof, and use of the derivatives in lubricating oil compositions.

The reaction of maleic anhydride or maleic acid with a monoolefin polymer to form a polyalkenyl succinic anhydride or acid is known. Thus, polyisobutene succinic anhydride, hereinafter referred to as PIBSA, which is widely used in the form of its ester or imide, as a dispersant in lubricating oil applications, is prepared by reacting polyisobutene with maleic anhydride. The reaction can be represented by the following equation:

From US patent 4.0124-38 it is also known that

alkyl or cycloalkyltetracarboxylic acid compounds of formula can be prepared

in which A and C are monovalent succinic acid groups connected to B at one of the two carbon atoms A and C which have unsaturated valences and a hydrogen atom connected to the other unsaturated carbon atom, in which B is the connecting alkane-

or cycloalkane group 4- to 30 carbon atoms which have 2 of the above-mentioned groups A and C, which are equally or differently connected at carbon atom 1 and 2, or at carbon atom 1 and 3, and optionally have carbon atom 1 and carbon atom 4- connected by a 1- 8 carbonmethylene bridge, the remainder of the unsaturated carbon valences of the bivalent hydrocarbon group are connected to hydrogen atoms, and wherein R 1 means

2 3

H and R and R mean H or the same or different hydrocarbyl groups, X and Y mean together.-0- or X and Y are the same or different groups of the structure: -OR, in which R

means H or the same or different alkyl or cycloalkyl groups with from 1 to 8 carbon atoms each. The alkyl or cycloalkyltetracarboxylic acid compound with the above formula is prepared by hydrogenation of the corresponding compound in which B is an alkenyl group with 4 to 30 carbon atoms.

Theoretically, it is possible to prepare a polyalkenyl bis (succinic acid or anhydride) by reacting mono (succinic acid or anhydrides), which is produced by reacting maleic anhydride and PIBSA with additional maleic anhydride as shown by the following equation:

However, as polyalkenyl bis-(succinic acid or anhydride) has been discussed and in practice it has not been found possible to produce mono-(succinic acid or anhydride) by 100% transfer of the ■olefin polymer. For example, the composition of 1 mol of polyisobutene should have an average molecular weight of 1000, i.e. the average molecular weight of a mol of olefin determined by measuring the bromine number with a mol. maleic anhydride theoretically give polyisobutene mono (succiric anhydride) with a PIBSA number of approx. 102, (the PIBSA number is the number of mg of potassium hydroxide required to neutralize 1 gram of the sample). In practice, it must have been found possible to achieve a PIBSA figure of approx. 90 in uncatalyzed maleination met a figure corresponding to approx. 85% molar transfer of polyisobutene. One of the groups for this is believed to be that polyisobutene contains approx. 15% unreactive impurities.

It has now surprisingly been found that polyalkenyl-

bis (succinic acid or anhydride) in which the polyalkenyl groups derived from a polyolefin with an average molecular weight (Mn) in the range from 500 to 2100 can be produced by modifying the process conditions and in particular by using a nickel salt as catalyst.

Accordingly, according to: the invention is provided

a polyalkenyl bis-(succinic acid) or a polyalkenyl bis-(succinic anhydride) in which the polyalkenyl group is derived from a polyolefin, having an average molecular weight in the range from 500 to 2100.

Furthermore, the invention relates to a composition comprising a polyalkenyl mono-(succinic acid or anhydride) and a polyalkenyl bis-(succinic acid or anhydride) in which the polyalkenyl groups are derived from a polyolefin with an average molecular weight in the range from 500 to 2100.

The polyalkenyl groups can suitably be derived from a polyolefin such as polyethylene, polypropylene and polybutylene or an olefin copolymer. Preferably, the polyalkenyl group is derived from polyisobutene.

Furthermore, according to the invention, it is provided

a method for producing a composition as mentioned above, the method being characterized by reacting a polyolefin with an average molecular weight in the range from 500 to 2100 in more than an equimolar amount of malein-

acid or maleic anhydride at elevated temperature,

and either at sub-atmospheric, atmospheric or hard-atmospheric pressure while passing a gas stream through the reaction participants or a sub-atmospheric pressure in the absence of a gas stream, either for the entire duration or for part of the ■ reaction.

Maleic acid or maleic anhydride is preferably reacted with the polyalkylene in a molar ratio in the range of 1:1 to 3:1. Although all of the maleic acid or maleic anhydride may be added in one portion at the beginning of the reaction, it is preferred to add it either portionwise or continuously for the duration of the reaction.

Appropriately, this elevated temperature can be higher than 150°C and preferably in the range of 200 to 260°C. More preferably, the reaction is carried out with a programmed temperature increase over a temperature range from 230 to 250°C.

The pressure at which the method is carried out depends on the extent to which a gas stream is passed through the reaction participants or not. Thus, the pressure can be atmospheric, sub-atmospheric or super-atmospheric, when a gas stream is passed through the reaction participants. The gas can be an inert gas, such as nitrogen or carbon dioxide or a lower carbon. In the absence of gas flow, the pressure must be below atmospheric, either during all or part of the reaction. Although the reaction can be carried out completely at subatmospheric pressure, it is preferred to carry out the beginning of the reaction at superatmospheric pressure, to reduce the pressure to subatmospheric during the reaction, preferably during the last phase of the reaction.

It is assumed that the gas flow or use of sub-atmospheric pressure enables the removal of volatile contaminants. Use of an inert gas stream is preferred in industrial scale operation of the process due to the long operating times required to achieve further pressure change.

The reaction time can appropriately be at least

4 hours and preferably from 6 to 12 hours.

The process can be carried out in the presence or absence of catalyst, preferably in the presence of a catalyst

With regard to the catalyst, it has been found that nickel salts and especially nickel iodide are active catalysts

tor for the preparation of polyalkenyl bis-(succinic acid or anhydride), regardless of the alkenyl substituent. •The connection also relates to the process for the production of a polyalkenyl-bis-(succinic acid or anhydride), which is characterized by reacting a polyolefin with a greater than equimolar amount of maleic acid or maleic anhydride at elevated temperature, and in the presence of a catalyst comprising a nickel salt.

The nature of the polyalkylene, molar ratio of the reaction participants, the reaction temperature and reaction time,

may conveniently be the same as stated above. It is also preferred to operate the process at atmospheric sub-atmospheric or super-atmospheric pressure while passing a gas flow through the reaction participants, or by working at sub-atmospheric pressure in the absence of a gas flow, either for all or part of the reaction duration.

In addition to PABSA, both methods form polyalkenyl mono- (succinic acid or anhydride) and are therefore

a suitable method for producing the composition according to the invention. In the absence of a catalyst, it is possible to transfer polyisobutene of average molecular weight 1000 to PABSA containing compositions having

a PIBSA number in the range of 90 to 150. In the presence of nickel iodide as a catalyst, it is possible to increase the PIBSA number to at least 120, corresponding to approx. 4.0% transfer to PIBSA.

PABSA or the composition according to the invention can conveniently be transferred to an ester or an ester composition by reacting an alcohol - under known esterification conditions, or can be transferred to an imide or imide composition conveniently by reacting with an amine of formula

h2n(ch2chnh)xh

R<1>

in which x is an integer and R is a C to C alkyl radical or hydrogen by, for example, the method described in British Patent No. 9 22831. Both the ester and the imide can be used in lubricating oil compositions. It has been found that less succinimide derived from PABSA-containing compositions according to the invention is required to form the same functional group concentration than when the succinimide derived from the corresponding mono- (succinic acid or anhydride) is used, without any apparent loss in scattering properties. Especially after resulting in an increase in the viscosity of the lubricating oil formulations which incorporate the succinimide produced from PABSA-containing mixtures according to the invention.

Accordingly, there is provided a lubricating oil composition comprising a lubricating base oil and an imide or ester dispersant derived from either PABSA or PABSA-containing compositions as indicated above.

In addition to the succinimide or the ester dispersant, the lubricating oil composition may also contain one or more common lubricating oil additives.

The invention will be explained in more detail with the help of some examples.

Preparation of polyisobutene bis-(succinic anhydride).

Example 1

Polyisobutene (4-00 g of average molecular weight 1000) of maleic anhydride (64 g) and nickel iodide (0.64 g) was added to a stainless steel Magnedrive autoclave (1 1 capacity) and the mixture was heated with stirring at 230° C and an applied pressure of 30 psig nitrogen. The reaction mixture was also continuously bubbled through with nitrogen/at a flow rate of approx. 3 liters per hour. The reaction temperature was gradually increased from 230 to 24-0°C over the course of 2 hours. A further addition of maleic anhydride (33 g) was made over a 2 hour period at 24-0°C to 250°C / 10 psig and then the reaction mixture was heated for an additional 4 hours at 250

to 260°C/30 psig. The reaction product (4-84 g) was cooled to 150°C and then discharged from the autoclave. The reaction product comprises 1.1% v/v of unreacted maleic anhydride, 30%. v/v of unreacted polyisobutene and remaining was polyisobutene succinic anhydride. This product gave a total PIBSA number of 120 mg KOH equivalent g _ -i, after correction for its maleic anhydride content. This high PIBSA number indicates that a significant amount of bis-(succinic anhydride) substitution of the polyisobutene had occurred.

Example - 2

Polyisobutene (4-00 g of average molecular weight 100.0) was added to a stainless steel Magnedrive autoclave (1 liter capacity) and was heated to 230°C with stirring and nitrogen gas flow (gas flow approx. 3 liters) per hour) under an applied pressure of 4-0-4-4-psig nitrogen. Maleic anhydride (63 g) was then pumped into the reaction over 2 hours while the temperature of the reaction mixture was increased from 130 to 24-0°C Additional maleic anhydride (32 g) was pumped into the reaction mixture over 2 hours at 24-0°C/4-0-4.4 psig, and then the reaction temperature was raised from 24-0° to 250 °C over an outer 4-hour period. The reaction mixture was then cooled to 150°C and discharged from the reactor. The product was distilled up to 215°C/100 mbar to remove unreacted maleic anhydride as an overhead product. The distillate residue was then filtered to remove resin derived from maleic anhydride and the filtrate product gave a total PIBSA number of 115 KOH equivalent per gram.

Preparation of succinimide dispersant from polyisobutene bis-(succinic anhydride).

Example 3'

PIBSA turnover product with a PIBSA figure of

120 from example 1 (220g) was mixed with a corresponding weight of lubricating oil and heated to 190°C/1bar. Triethylene tetraamine (15.78 g) was then added with stirring over 15 minutes and the mixture was then heated for 3 hours at 190°C. The PIBSA imide product contained 1.37 v/v nitrogen, 0.52% v/v basic nitrogen and gave a viscosity of approx. 70.3 cSt at 100°C.

PIBSA-imide derived from regular PIBSA with a total PIBSA number of 95 KOH equivalent per gram, contains in particular 1.4-% v/v nitrogen, 0.58.$ v/v' basic'nitrogen and gives a viscosity of 4-95 cSt at 100°C.

The imide derived from the polyisobutenyl bis-(succinic anhydride) compound has a lower viscosity (76.3 cSt) than the imide derived from polyisobutenyl mono-(succinic anhydride)

(4-95 cSt).

Machine test.

Example 4-

A Petter AV-1 machine test was performed on a standard formulation in which a minor amount of usual imide-95

the product from example 3 (i.e. Y20x vaG^S addition) was used to give the same concentration of imide functional groups in the test mixture, and this gave the same good machine test grade (as determined by measuring the degree of carbonization of the piston surfaces), as the obtainable from common formulations.hydrolysable imide derived from polyisobutenyl mono-(succinic anhydride).

Effect of pressure.

Example' 5

Polyisobutene (1 mole of average molecular weight 1000) and maleic anhydride (1.6 moles) were added to a stainless steel Magnedrive autoclave (1 liter capacity) and the mixture was heated with stirring to 238°C under an applied pressure of 10 psig nitrogen . After 2 hours under these conditions, PIBSA numbers were measured. The pressure was reduced to atmospheric pressure for a further 2 hours, and PIBSA numbers again determined. Finally the pressure was reduced

to -10 psig for U hours, and the PIBSA number was determined at the end of this period. The results are listed in the following table.

Comparison test 1.

The procedure according to example 5 was repeated with the exception that the pressure was maintained, at 10

psig at time, and the measurement of PIBSA number was made after A and 8 hours.

Comparison test 2.

Comparative Test 1 was repeated with the exception that the pressure was maintained at 20 psig throughout, and the PIBSA number was measured only U hours.

Comparison samples 1 and 2 are not covered by the invention, and are only included for comparison purposes.

Example 6.

Example 5 was repeated with the difference that the pressure was maintained at 20 psig throughout the

the search and reaction participants were flushed with nitrogen in an amount of 4 volumes of nitrogen per volume of reaction mixture per hour..The total PIBSA figure was measured after.6 hours.

The results in the table show that in comparison sample 1, a PIBSA number of 85 was obtained during the course of A hour at 238°C/10 psig, and that this did not increase after a further 4-hour reaction. In Example 5, equilibrium was reached... during 2 hours at 238°C/25 psig and a further reaction occurred as a result of a reduction in pressure from 25 to 15 psig absolute to give PIBSA-

figure of 87, which was further increased to 95 by reducing the pressure to 5 psig absolute. In Example 6, the corresponding PIBSA numbers obtained by isobaric pressure operation, simply by flushing the reaction mixture with a stream of nitrogen.

Claims (10)

1. A polyalkenyl bis-(succinic acid) or a polyalkenyl bis-(succinic anhydride) in which the polyalkenyl group is derived from a polyolefin having an average molecular weight in the range of 500 to 2100. 2. A composition comprising polyalkenyl bis-(succinic acid) or polyalkenyl bis-(succinic anhydride) according to claim 1, and a polyalkenyl mono- (succinic acid or anhydride) in which the polyalkenyl groups are also derived from a polyolefin with an average molecular weight in the range from 500 to 2100 . 3. A composition according to claim 2, characterized in that the polyalkenyl group is derived from polyisobutene. 4-. A composition according to claim 2, characterized in that the polyalkenyl group is derived from polyisobutene with an average molecular weight of 1000 and the composition has a PIBSA number in the range from 90 to 115. 5. A composition according to claim 2, characterized in that the polyalkenyl group is derived from polyisobutene with an average molecular weight of 1000, and the composition has a PIBSA number greater than 120. 6. Process for producing a composition according to one of claims 2 to 4-, v characterized in that reaction of a polyolefin with an average molecular weight in the range from - 500 to 2100, in more than an equimolar amount of maleic acid or maleic anhydride at elevated temperature , and subatmospheric or atmospheric or superatmospheric pressure during passage of gas flow through the reaction mixture. 7. 'Procedure for producing a composition according to one of claims 2 to 4-, characterized by the reaction of a fine polyol with an average molecular weight in the range from 500 to 2100, with more than an equimolar amount of maleic acid or maleic anhydride at elevated temperature and at subatmospheric pressure, in the absence of a gas stream, for at least part of the reaction time . 8. Process for the production of a polyalkenyl-bis-(succinic acid) or polyalkenyl-bis(succinic anhydride) characterized by reacting a polyolefin with more than an equimolar amount of maleic acid or maleic anhydride in the presence of a catalyst comprising a nickel salt. 9. Method according to claim 8, characterized in that the nickel salt is nickel iodide. 10. Lubricating oil composition reacting one lubricating base oil, and an imide or ester dispersant derived from either a polyalkenyl-bis(succinic acid), or polyalkenyl-bis-(succinic anhydride), according to claim 1, or the composition according to, claims, 2 to 5..