Process to make aminated polyolefins

Details Process to make aminated polyolefins Process to make aminated polyolefins

2001-01-23

2003-06-24

Zitomer, Fred (Department: 1713)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Mixing of two or more solid polymers; mixing of solid...

C525S378000, C525S379000

Reexamination Certificate

active

06583231

ABSTRACT:

This application claims priority from European Patent Application No. 00200252.5, filed Jan. 25, 2000.
The present invention relates to a new process to make aminated polyolefins, particularly aminated polyisobutylenes.
Aminated polyisobutylenes have long been used as an additive in lubricating oils and/or fuels, such as gasoline, especially unleaded gasoline. Early on, these products were made by halogenation and subsequent amination of low-molecular weight polyolefins, as described in for instance GB 1,083,610. Because of the desire not to use a halogenation process, other routes to the aminated polyolefins were sought.
GB 1,172,818 discloses a process wherein a long-chain ketone or aldehyde, which may be formed through ozonolysis of an olefin polymer and subsequent decomposition of the products formed, is reacted with one or more specific diamines. Specific types of aminated polyolefins are obtained. This process was found to be cumbersome, especially because first the ketone or aldehyde has to be formed and purified. Although conventional techniques are used, this decomposition step is elaborate and costly.
EP-A-0 123 424 discloses employing a specific oxidation process which involves the use of at least one hydroperoxide and at least one peroxide, to oxidize an olefinic polymer which is separated from the reaction mixture. Preferably, the so-oxidized polymers are further reacted with ammonia or organic amines other than tertiary compounds. The use of ammonia in this process resulted in aminated polyolefins with favourable properties. However, the process to make them is not very economical, since it requires the use and handling of at least two types of peroxides.
U.S. Pat. No. 4,832,702 deals with the difficulties observed in the various oxidative processes by introducing a hydroformylation step. The products differ from the previous aminated polyolefins in that an additional carbon atom is introduced into the molecule. This process has gained commercial significance even though it is not very economical. The process is particularly uneconomical if aminated polyisobutylenes are made, because polyisobutylene with an isobutylene end group, which is present for about 25% in commercial polyisobutylenes, shows poor conversion in the hydroformylation process. U.S. Pat. No. 5,103,061 discloses a process wherein a low-molecular weight polyolefin is first treated with ozone and the resulting product is reacted directly with a primary hydrocarbyl amine. After further treatment aminated polyolefins are obtained. This process is considered to be hazardous even if the ratio of ozone to olefin is selected properly, especially because the primary products of the ozonation are described to be refluxed without taking any precautions. U.S. Pat. No. 5,274,182 introduces another alternative process in which a high-molecular weight isobutylene-diene copolymer is degraded by means of ozone, the degradation products having two lateral functional groups. These groups can be modified, inter alia, with the aid of ammonia in order to obtain specific aminated polyisobutylenes. However, the handling of the very high-molecular weight product can be difficult and use is to be made of the specific copolymer. It is noted that the degradation products of the ozonolysis are stabilized to prevent further oxidation because of the peroxides that are present. The introduction of such additives is time consuming, expensive and for those reasons regarded to be undesired.
Since the aminated polyolefins are of increasing interest for use in modern-day oils and fuels, a new process was sought that: i) does not suffer from the hazards of the above-mentioned processes, ii) can be derived from off-the-shelf low-molecular weight polyolefins, iii) gives good yield, also if polyisobutylenes with an isobutylene end group are used as a raw material, iv) can be practised without the necessity of purifying intermediates and/or adding additional chemicals, and v) preferably can be run in a continuous fashion.
Surprisingly, we have found that a new process fulfills most, if not all, of these requirements. This new process, the first embodiment of the present invention, includes an ozonolysis, a reduction, and a reductive amination step. More particularly, the process involves the steps of:
1. ozonolysis of one or more low-molecular weight polyolefins with at least one end group that is unsaturated, in the presence of an alkanol-hydrocarbon solvent mixture, to form a solution/dispersion of polyolefin-alkoxyhydroperoxides,
2. subsequent catalytic reduction of the crude solution/dispersion of polyolefin-alkoxyhydroperoxides with hydrogen and a suitable catalyst, to form a solution/dispersion of hemi-acetals and or -ketals,
3. removal of the catalyst and optional washing of the mixture resulting from step 2, to remove undesired side products,
4. reductive amination of the hemiacetals and or -ketals to form the aminated polyolefin end product, preferably at a temperature of 50-200° C., optionally in the presence of a solvent, and
5. removal of the catalyst and optional removal of the solvent.
The ozonolysis is conducted in a conventional way, using conventional equipment. Suitably, ozone gas and an optional diluent gas, such as oxygen or air, are bubbled through a solution/dispersion of the unsaturated low-molecular weight polyolefin in the hydrocarbon/alkanol solvent mixture. Part of the acetone and formaldehyde formed will remain in the mixture, while the rest may be carried off, together with some solvent, with the optional diluent gas. Traces of formic acid may form. Preferably, conditions are chosen such that throughout the reaction the mixture is in the form of a solution. In that case, the ozonolysis time can be kept short. Furthermore, it is preferred to conduct the ozonolysis in a continuous fashion. In an non-optimized experimental set-up where the ozonolysis was conducted in a continuous fashion at 0-20° C., average residence times of 30 seconds were shown to be sufficient to get a conversion of the unsaturated groups of >95%. Preferably, the ozonolysis is conducted in such a fashion that essentially no formaldehyde is formed by either selecting the appropriate low-molecular weight polyolefin or the proper reaction conditions, e.g. by lowering the ozone concentration, which measures are either known to the skilled person or found by routine experimentation.
The low-molecular weight polyolefin with at least one unsaturated end group that is used as raw material is preferably selected from the group consisting of polypropene, polyisobutene, poly-1-butene, ethene-propene copolymer, ethene-isobutene copolymer, ethene-1-butene copolymer, propene-isobutene copolymer, propene-1-butene copolymer, and terpolymers of ethene, propene and/or butene with one or more other ethylenically unsaturated monomers, such as styrene, &agr;-methylstyrene, vinyl naphthalene, butadiene, and isoprene, with at least one unsaturated ethenyl (—CH═CH
2
), 1-propenyl (—CH═CH—CH
3
), 2-propenyl (—CH
2
—CH═CH
2
), 1-isobutenyl (—CH═C(CH
3
)
2
), 2-isobutenyl (—CH
2
—C(CH
3
)═CH
2
), 2-butenyl (—CH
2
—CH═CH—CH
2
), or 3-butenyl (—CH
2
—CH
2
—CH═CH
2
) end group. Preferably, it is a polyisobutene, poly-1-butene, or a co- or ter-polymer with 30% or more, preferably 50% or more, monomeric units derived from 1-butene or isobutene, with one of the indicated end groups. More preferably, it is a polyisobutene with 1-isobutenyl (—CH═C(CH
3
)
2
) and/or 2-isobutenyl (—CH
2
—C(CH
3
)═CH
2
) end groups. Most preferred are commercial mixtures of said polyisobutenes with said 1-isobutenyl and/or 2-isobutenyl end groups. For ease of production and for increased purity of the product it is preferred to use a low-molecular weight unsaturated polyolefin with just one unsaturated end group. The number averaged molecular weight (Mn) of these low-molecular weight unsaturated polyolefin materials preferably is from 300 to 5000 Dalton. More preferably, they have a Mn of 400-3000, most preferably from 500-2000 Dalton. An example

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