Ethylene-based copolymers and their use as flow improvers in min

Details Ethylene-based copolymers and their use as flow improvers in min Ethylene-based copolymers and their use as flow improvers in min

1996-04-02

1997-11-04

Schofer, Joseph L.

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

Synthetic resins

Polymers from only ethylenic monomers or processes of...

44408, 526330, 5263488, 524555, C08F22602, C08F21804, C10L 118, C10L 122

Patent

active

056841086

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to novel ethylene-based copolymers, the use of these and of copolymers known per se as flow improvers in mineral oil middle distillates, and furthermore mineral oil middle distillates which contain these copolymers.
2. Description of the Related Art
Middle distillates, such as gas oils, diesel oils or fuel oils, which are obtained from mineral oils by distillation, have different contents of paraffins, depending on the origin of the crude oil. At relatively low temperatures, solid paraffins separate out (cloud point, CP). On further cooling, the lamellar n-paraffin crystals form a house-of-cards structure, and the middle distillate sets although the predominant part of the middle distillate is still liquid. The flow of the fuels obtained from the mineral oil distillate is considerably impaired by the precipitated n-paraffins in the temperature range between cloud point and pour point. The paraffins block filters and cause nonuniform fuel feed to the combustion units or completely stop the feed. Similar problems occur in the case of fuel oils.
It has long been known that the crystal growth of the paraffins in the combustion and power fuels obtained from the mineral oil middle distillates can be modified by means of suitable additives. Effective additives on the one hand prevent middle distillates from forming such house-of-cards structures and becoming solid at temperatures as low as a few degrees Celsius below the temperature at which the first paraffin crystals crystallize out and, on the other hand, form fine, well-crystallized, separate paraffin crystals which pass through filters in motor vehicles and heating systems or at least form a filter cake which is permeable to the liquid part of the middle distillates, thus ensuring trouble-free operation.
Ethylene/vinyl carboxylate copolymers as disclosed, for example, in U.S. patent application No. 3,048,479 and U.S. patent application No. 3,627,838 have long been used as flow improvers.
A disadvantage of these additives is that, because they have a higher density than the liquid part, the precipitated paraffin crystals tend increasingly to settle out on the bottom of the container during storage. Consequently, a homogeneous phase having a low paraffin content forms in the upper part of the container and a two-phase paraffin-rich layer at the bottom. Since, both in vehicle tanks and in the mineral oil dealers' storage or delivery tanks, the middle distillate is generally withdrawn slightly above the bottom of the container, there is a danger that the high concentration of solid paraffins will lead to blockages of filters and metering means. This danger is all the greater the further the storage temperature is below the precipitation temperature of the paraffins, since the amount of paraffin precipitated is a function of the temperature and increases with decreasing temperature.
JP-A 83/80386 describes flow improvers comprising ethylene, vinyl acetate and N-vinyl-2-pyrrolidone, which however do not give satisfactory results in all cases in practice since the mineral oil fractions to be treated differ greatly in composition, depending on their origin. According to EP-A 405 270, the action of the terpolymers disclosed in the Japanese patent application can be improved by mixing with an ethylene/vinyl acetate co-polymer; on the other hand, the addition of a plurality of polymers to the mineral oil middle distillates is technically very complicated.
U.S. patent application No. 2,787,459 discloses copolymers made from monomers which carry a basic nitrogen atom, such as aminoalkyl acrylates, and those monomers which carry no amino group but a hydrocarbon radical of 8 to 18 carbon atoms. They are used for dispersing sludge, as may be obtained from fuel oils.
EP-A 340 975 describes copolymers of ethylene and aminoalkyl acrylates, which may contain up to 20% by weight of vinyl acetate and have a number average molecular weight of from 5000 to 50,000. The copolymers are used for reduci

REFERENCES:
patent: 2787459 (1957-04-01), Du Bus De Warnaffe
patent: 3048479 (1962-08-01), Ilnyckyj et al.
patent: 5115036 (1992-05-01), Shiga et al.
Chemical Abstract 99, 215,519f, 1983 -Abstract of AL.

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