Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1988-06-24
1991-07-02
Lipman, Bernard
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
5253338, 525379, C08F 806
Patent
active
050286668
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to an improved process for the production of oxidised polyisobutenes, to the production of lubricating oil and fuel additives therefrom and to the uses thereof.
Oxidised polyisobutenes, that is polyisobutenes having oxygen chemically bound thereto principally in the form of keto-carbonyl groups, are potentially valuable industrial products because they are readily convertible by reaction with amines into materials useful as lubricating oil additives, for example as dispersants and detergents.
The oxidation and subsequent ammination of polyisobutylenes has been described in the patent literature in, for example, U.S. Pat. No. 3,931,024.
U.S. Pat. No. 3,931,024 discloses that a highly effective dispersant for a lubricating oil or a fuel can be prepared by the noncatalysed air-oxidation of a polyolefin or of a halogenated polyolefin to form an oxygen-containing material. This material is then reacted with an aliphatic polyamine under conditions that cause the formation of an addition product which differs chemically from the Schiff bases of the prior art. The oxidation of the polymer is conducted by contacting the polymer with air at a temperature in the range of from about 120.degree. to about 250.degree. C., more usually at a temperature in the range from about 150.degree. C. to about 220.degree. C. The lower temperatures tend to favour more unsaturation in the product. Excessively high temperatures are generally to be avoided so as to minimise degradation. Atmospheric pressure or somewhat elevated pressures can be used, the latter favouring the mass transfer rate. Efficient agitation is also helpful in increasing the rate. In Example 1 of U.S. Pat. No. 3,931,024 a quantity of polyisobutene of about 980 average molecular weight was oxidised by blowing air through the polymer at 170.degree. C. for 25 hours, no catalyst being used. More specifically, 1640 g of the polymer was thus oxidised using a stream of air at the rate of 1 liter of air per minute measured at standard conditions. The oxidised polymer was found to contain 4.3 weight percent of oxygen. No further details of the oxidation process are given.
In our experience, it is possible to successfully produce oxidised polyisobutenes in stirred pots on a laboratory scale, but scale-up has proved impossible. This failure to scale-up we now believe is due to the difficulty involved in developing sufficient shear in a large stirred pot reactor. For example it has been calculated from our results that an 80 cm diameter reactor with an 80 cm fill height and a 6 blade flat agitator would require a minimum of a 60 kilowatt stirrer.
In GB-A-959362 there is described the oxidation of polyethylene waxes in vessels of 10 liter and 100 liter capacity. In order to achieve an acceptable shear rate a very high agitator power input is employed.
It is clear from the foregoing that for commercial scale operation a different approach is required. We have now found that polyisobutenes can be successfully oxidised in a manner capable of use on a commercial scale by passing through a column of polyisobutene a molecular oxygen-containing gaseous oxidant at high gas flow rates per unit cross-sectional area. In this manner high shear of the polyisobutene can be achieved.
Accordingly, the present invention provides a process for the production of an oxidised polyisobutene which process comprises passing through a column of the polyisobutene maintained at a temperature in the range from 140.degree. to 200.degree. C. and at atmospheric or elevated total pressure a molecular oxygen-containing gaseous oxidant at a gas flow rate greater than 10 liters cm.sup.-2 h.sup.-1 measured at the operating pressure.
As the molecular weight of polyisobutenes increases, their physical form changes from mobile liquids, through viscous liquids to rubbery solids. Suitably the polyisobutene may be one having a number average molecular weight in the range from about 900 to about 10,000, though higher molecular weight polyisobutenes may be used if desired. Low molecular wei
REFERENCES:
patent: 3931024 (1976-01-01), Hu
BP Chemicals (Additives) Limited
Lipman Bernard
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