Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
1999-05-26
2001-08-28
Yoon, Tae H. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S240000, C524S523000, C524S524000, C524S536000
Reexamination Certificate
active
06281292
ABSTRACT:
The present invention relates to mixtures of oil-soluble copolymers of ethylene and further comonomers which contain one or more hydroxyl groups and copolymers of ethylene and ethylenically unsaturated compounds, and their use for improving the lubricity of fuel oils.
DESCRIPTION OF THE RELATED ART
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).
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-0 743 974 discloses additives which improve the lubricating action of fuel oils and which comprise mixtures of esters and copolymers of ethylene and vinyl acetate.
WO-95/33805 discloses the use of cold-flow improvers as lubricity enhancers.
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.
However, the lubricating action of the known additives is in many oils still unsatisfactory or very high amounts must be added in order to achieve satisfactory results. The object of the present invention was therefore to find additives which improve the lubricating action in middle distillates which have been substantially freed from sulfur and aromatic compounds and do so when used in extremely small amounts.
SUMMARY OF THE INVENTION
Surprisingly, it has been found that mixtures of copolymers which, besides ethylene, also contain hydroxyl-containing comonomers and copolymers consisting of ethylene and olefinically unsaturated esters or ethers exhibit the requisite properties.
The invention thus relates to mixtures comprising
A) from 10 to 90% by weight of at least one copolymer comprising structural units derived from ethylene and structural units derived from olefinically unsaturated, hydroxyl-containing compounds, and
B) from 90 to 10% by weight of at least one copolymer comprising structural units derived from ethylene and structural units derived from vinyl esters, olefinically unsaturated ethers and/or (meth)acrylates.
The invention furthermore relates to fuel oils comprising the copolymer mixtures described.
The invention furthermore relates to a process for improving the lubricating action of fuel oils while simultaneously improving their cold-flow properties, which comprises adding the copolymer combinations described to the fuel oils.
The olefinically unsaturated compounds whose non-ethylenic structural units are derived from the further comonomers in component A) 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).
DESCRIPTION OF THE PREFERRED EMBODIMENTS
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
16
-hydroxyalkyl, especially C
2
-C
12
-hydroxyalkyl, or C
6
-C
30
-hydroxyaryl. Suitable vinyl esters include 2-hydroxyethyl vinyl ester, &agr;-hydroxypropyl vinyl ester, 3-hydroxypropyl vinyl ester and 4-hydroxybutyl vinyl ester.
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
16
-hydroxyalkyl, especially C
2
-C
12
-hydroxyalkyl. Suitable acrylates include hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate, hydroxyisopropyl acrylate, 4-hydroxybutyl acrylate, diethylene glycol monoacrylate and glycerol monoacrylate, and the corresponding esters of methacrylic acid.
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
16
-hydroxyalkyl, especially C
2
-C
12
-hydroxyalkyl. 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.
The molar proportion of hydroxy-functionalized comonomers in the copolymer A) is preferably from 0.5 to 15%, in particular from 1 to 12%, especially from 1 to 8%. The OH number of the copolymer is preferably between 1 and 500 mg of KOH/g of polymer, in particular between 5 and 300 mg of KOH/g of polymer, especially between 10 and 200 mg of KOH/g of polymer.
Besides ethylene, the copolymers A) 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 (Versatic 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 ester of a neocarboxylic acid having 8 to 12 carbon atoms. If the copolymers contain a further comonomer, the molar proportion thereof is preferably up to 15%, in particular up to 12%.
The olefinically unsaturated compounds whose non-ethylenic structural units are derived from the further comonomers in component B) are preferably vinyl esters, acrylic esters, methacrylic esters and/or alkyl vinyl ethers.
The vinyl esters are preferably those of the formula 4
CH
2
=CH—OCOR
1
(4)
in which R
1
is C
1
-C
30
-alkyl, preferably C
1
-C
1
Krull Matthias
Kupetz Markus
Reimann Werner
Clariant GmbH
Hanf Scott E.
Jackson Susan S.
Yoon Tae H.
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