Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1998-12-16
2002-05-07
Pezzuto, Helen L. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C044S271000, C526S318440, C526S318450, C526S320000, C526S324000, C526S331000, C526S332000
Reexamination Certificate
active
06384170
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to oil-soluble copolymers of ethylene and further comonomers which contain one or more hydroxyl groups, and their use for improving the lubricity of fuel oils.
BACKGROUND OF THE INVENTION
Mineral oils and mineral oil distillates used as fuel oils generally contain 0.5% by weight or more of sulfur, which, on burning, causes the formation of sulfur dioxide. In order to reduce the resultant environmental pollution, the sulfur content of fuel oils is continually being reduced further. The EN 590 standard relating to diesel fuels currently prescribes a maximum sulfur content of 500 ppm in Germany. In Scandinavia, fuel oils containing less than 200 ppm and in exceptional cases less than 50 ppm of sulfur are already in use. These fuel oils are generally produced by hydrotreating the fractions obtained from the crude oil by distillation. However, the desulfurization also removes other substances which provide the fuel oils with a natural lubricating action. These substances include, inter alia, polyaromatic and polar compounds.
However, it has now been found that the friction- and wear-reducing properties of fuel oils worsen with increasing degree of desulfurization. These properties are frequently so poor that the fuel-lubricated materials, such as, for example, the distributor injection pumps of diesel engines, can be expected to exhibit signs of wear after only a short time. The further lowering of the 95% distillation point to below 370° C., in some cases to below 350° C. or 330° C., which has in the meantime been carried out in Scandinavia, further exacerbates this problem.
The prior art therefore describes attempts to solve this problem (so-called lubricity additives).
EP-A-0 680 506 discloses esters of carboxylic acids having 2 to 50 carbon atoms as additives for improving the lubricating action of low-sulfur middle distillates containing less than 0.5% by weight of S.
DD-126 090 discloses lubricity additives comprising copolymers of ethylene and unsaturated carboxylic esters, preferably vinyl acetate, which are added to the fuels in amounts of from 0.01 to 0.5% by weight.
EP-A-0 764 198 discloses additives which improve the lubricating action of fuel oils and comprise polar nitrogen compounds based on alkylamines or alkyl ammonium salts containing alkyl radicals having 8 to 40 carbon atoms.
DE-A-15 94 417 discloses additives for improving the lubricating action of oleophilic liquids which comprise esters made from glycols and dicarboxylic acids having at least 11 carbon atoms.
EP-A-0 635 558 discloses diesel oils having sulfur contents of less than 0.2% by weight and aromatic contents of less than 30% by weight. These diesel oils contain, as additives, from 100 to 10,000 ppm of C
1
-C
5
-alkyl esters of unsaturated, straight-chain C
12
-C
22
-fatty acids originating from oil seed.
EP-A-0 074 208 discloses middle and heavy distillates containing, as additives, copolymers of ethylene and alkoxylated acrylates or ethylene and vinyl esters of saturated and unsaturated carboxylic acids.
The object of the present invention was to find additives which improve the lubricating action in middle distillates which have been substantially freed from sulfur and aromatic compounds. At the same time, these additives should also have a positive effect on the cold-flow properties of these middle distillates.
SUMMARY OF THE INVENTION
Surprisingly, it has been found that copolymers of ethylene and ethylenically unsaturated compounds carrying one or more hydroxyl groups provide the fuel oils to which they are added with the requisite properties.
The invention relates to copolymers of ethylene and at least one further olefinically unsaturated comonomer containing one or more hydroxyl groups.
The invention furthermore relates to fuel oils comprising middle distillates containing a maximum of 0.5% by weight of sulfur and at least one copolymer of ethylene and at least one further olefinically unsaturated comonomer containing one or more hydroxyl groups.
The olefinically unsaturated compounds which make up the further comonomer(s) are preferably vinyl esters, acrylates, methacrylates, alkyl vinyl ethers and/or alkenes carrying hydroxyalkyl, hydroxyalkenyl, hydroxycycloalkyl or hydroxyaryl radicals. These radicals contain at least one hydroxyl group, which can be in any desired position of the radical, but is preferably at the chain end (&ohgr;-position).
The vinyl esters are preferably those of the formula 1
CH
2
═CH—OCOR
1
(1)
in which R
1
is C
1
-C
30
-hydroxyalkyl, preferably C
1
-C
2
-hydroxyalkyl, especially C
2
-C
6
-hydroxyalkyl or the corresponding hydroxy oxalkyl. Suitable vinyl esters include 2-hydroxyethylvinyl esters, &agr;-hydroxypropylvinyl esters, 3-hydroxypropylvinyl esters and 4-hydroxybutylvinyl esters.
The acrylates are preferably those of the formula 2
CH
2
═CR
2
—COOR
3
(2)
in which R
2
is hydrogen or methyl, and R
3
is C
1
-C
30
-hydroxyalkyl, preferably C
1
-C
12
-hydroxyalkyl, especially C
2
-C
6
-hydroxyalkyl or the corresponding hydroxy oxalkyl. Suitable acrylates include hydroxyethyl acrylate, hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate, 3-hydroxypropyl methacrylate, hydroxyisopropyl acrylate, 4-hydroxybutyl acrylate and glycerol monoacrylate.
The alkyl vinyl ethers are preferably compounds of the formula 3
CH
2
═CH—OR
4
(3)
in which R
4
is C
1
-C
30
-hydroxyalkyl, preferably C
1
-C
12
-hydroxyalkyl, especially C
2
-C
6
-hydroxyalkyl or the corresponding hydroxy oxalkyl. Suitable alkyl vinyl ethers include 2-hydroxyethyl vinyl ether, hydroxypropyl vinyl ether, hexanediol monovinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether and cyclohexanedimethanol monovinyl ether.
The alkenes are preferably monounsaturated hydroxyhydrocarbons having 3 to 30 carbon atoms, in particular 4 to 16 carbon atoms, especially 5 to 12 carbon atoms. Suitable alkenes include dimethylvinylcarbinol (=2-methyl-3-buten-2-ol), allyloxypropanediol, 2-butene-1,4-diol, 1-buten-3-ol, 3-buten-1-ol, 2-buten-1-ol, 1-penten-3-ol, 1-penten-4-ol, 2-methyl-3-buten-1-ol, 1-hexen-3-ol, 5-hexen-1-ol and 7-octene-1,2-diol. In a further preferred embodiment the carbon chains of the alkenes contain oxygen atoms.
The invention furthermore relates to a process for improving the lubricating action of mineral oils and mineral oil distillates by adding the hydroxyl-containing copolymers designated in greater detail herein to the oils.
The molar proportion of hydroxy-functionalized comonomers in the copolymer is preferably from 0.5 to 15%, in particular from 1 to 12%. The OH number of the copolymers is preferably between 1 and 800 mg of KOH/g of polymer, in particular between 5 and 500 mg of KOH/g of polymer, especially between 10 and 300 mg of KOH/g of polymer.
The melt viscosities of the copolymers according to the invention at 140° C. are preferably less than 10,000 mpas, in particular between 10 and 1000 mpas, especially between 15 and 500 mPas.
Besides ethylene, the copolymers according to the invention contain at least one comonomer containing hydroxyl groups. They may also contain further, for example one, two or three further, olefinically unsaturated comonomers. Examples of such olefinically unsaturated comonomers are vinyl esters, acrylic acid, methacrylic acid, acrylic esters, methacrylic esters, vinyl ethers and olefins. Particularly preferred vinyl esters are vinyl acetate, vinyl propionate and vinyl esters of neocarboxylic acids having 8, 9, 10, 11 or 12 carbon atoms. Particularly preferred acrylic and methacrylic esters are those with alcohols having 1 to 20 carbon atoms, in particular of methanol, ethanol, propanol, n-butanol, isobutanol and tert-butanol. Particularly preferred olefins are those having 3 to 10 carbon atoms, especially propene, isobutylene, diisobutylene, norbornene, 4-methyl-1-pentene and hexene. Particular preference is given to terpolymers of ethylene, a hydroxy-functionalized comonomer and either vinyl acetate or a vinyl
Krull Matthias
Kupetz Markus
Wildfang Raimund
Hanf Scott E.
Jackson Susan S.
Pezzuto Helen L.
LandOfFree
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