Additive compositions

Details Additive compositions Additive compositions

2002-10-07

2004-09-14

Seidleck, James J. (Department: 1711)

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

Synthetic resins

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

C525S098000, C525S338000, C508S475000, C508S591000, C044S393000, C044S395000

Reexamination Certificate

active

06790913

ABSTRACT:

This invention relates to additive compositions, use of the additive compositions to improve cold flow characteristics of fuel oils, fuel oil compositions comprising the additive compositions and additive concentrates of the additive compositions.
Fuel oils, whether derived from petroleum or from vegetable sources, contain components, e.g., alkanes, that at low temperature tend to precipitate as large crystals or spherulites of wax in such a way as to form a gel structure which causes the fuel to lose its ability to flow. The lowest temperature at which the fuel will still flow is known as the pour point.
As the temperature of the fuel falls and approaches the pour point, difficulties arise in transporting the fuel through lines and pumps. Further, the wax crystals tend to plug fuel lines, screens, and filters at temperatures above the pour point. These problems are well recognized in the art, and various additives have been proposed, many of which are in commercial use, for depressing the pour point of fuel oils. Similarly, other additives have been proposed and are in commercial use for reducing the size and changing the shape of the wax crystals that do form. Smaller size crystals are desirable since they are less likely to clog a filter. The wax from a diesel fuel, which is primarily an alkane wax, crystallizes as platelets; certain additives inhibit this and cause the wax to adopt an acicular habit, the resulting needles being more likely to pass through a filter than are platelets. The additives may also have the effect of retaining in suspension in the fuel the crystals that have formed, the resulting reduced settling also assisting in prevention of blockages.
EP 0 815 184A discloses the use of an oil-soluble hydrogenated block diene polymer in combination with a cold flow improver selected from: ethylene-unsaturated ester compounds; comb polymers; polar nitrogen compounds; compounds comprising a ring system having at least two substituents comprising a linear or branched aliphatic hydrocarbylene group optionally interrupted by one or more hetero atoms and carrying a secondary amino group, the substituents on the amino groups each being a hydrocarbyl group containing 9 to 40 carbons; hydrocarbon polymers; and polyoxyalkylene compounds.
The present invention is concerned with the problem of providing an improved additive composition for improving cold flow characteristics of fuel oils.
More particularly, the present invention is concerned with the problem of improving cold flow characteristics of fuel oils having a 90%-20% boiling temperature range, as measured in accordance with ASTM D-86, of more than 115° C., preferably more than 120° C., more preferably more than 130° C., and most preferably more than 140° C., and a final boiling point of more than 370° C., preferably more than 380° C., and most preferably more than 390° C.
In accordance with the present invention there is provided an additive composition comprising:
(i) at least one oil-soluble hydrogenated block diene polymer, comprising at least one crystallizable block, obtainable by end-to-end polymerization of a linear diene, and at least one non-crystallizable block, the non-crystallizable block being obtainable by 1,2-configuration polymerization of a linear diene, by polymerization of a branched diene, or by a mixture of such polymerizations;
(ii) at least one ethylene-unsaturated ester compound; and
(iii) at least one comb polymer.
As used in this specification the term “hydrocarbon” and related terms refer to a group having a hydrocarbon or predominantly hydrocarbon character. Among these, there may be mentioned hydrocarbon groups, including aliphatic, (e.g., alkyl), alicyclic (e.g., cycloalkyl), aromatic, aliphatic and alicyclic-substituted aromatic, and aromatic-substituted aliphatic and alicyclic groups. Aliphatic groups are advantageously saturated. These groups may contain non-hydrocarbon substituents provided their presence does not alter the predominantly hydrocarbon character of the group. Examples include keto, halo, hydroxy, nitro, cyano, alkoxy and acyl. The groups may also or alternatively contain atoms other than carbon in a chain or ring otherwise composed of carbon atoms.
The invention also provides use of the additive composition defined above to improve cold flow characteristics of a fuel oil. The additive composition has been found to be particularly effective in fuel oils having a 90%-20% boiling temperature range, as measured in accordance with ASTM D-86, of more than 115° C., preferably more than 120° C., more preferably more than 130° C., and most preferably more than 140° C., and a final boiling point of more than 370° C., preferably more than 380° C., and most preferably more than 390° C.
The invention further provides a fuel oil composition comprising a major proportion of a fuel oil and a minor proportion of the additive composition defined above.
The invention still further provides an additive concentrate comprising a solvent miscible with fuel oil and a minor proportion of the additive composition defined above.
Advantageously, the hydrogenated block copolymer used in the present invention comprises at least one substantially linear crystallizable segment or block and at least one segment or block that is essentially not crystallizable. Without wishing to be bound by any theory, it is believed that when butadiene is homopolymerized with a sufficient proportion of 1,4 (or end-to-end) enchainments to provide a substantially linear polymeric structure then on hydrogenation it resembles polyethylene and crystallizes rather readily; when a branched diene is polymerized on its own or with butadiene a branched structure will result (e.g., a hydrogenated polyisoprene structure will resemble an ethylene-propylene copolymer) that will not readily form crystalline domains but will confer fuel oil solubility on the block copolymer.
Advantageously, the block copolymer before hydrogenation comprises units derived from butadiene only, or from butadiene and at least one comonomer of the formula
CH
2
═CR
1
—CR
2
═CH
2
wherein R
1
represents a C
1
to C
8
alkyl group and R
2
represents hydrogen or a C
1
to C
8
alkyl group. Advantageously the total number of carbon atoms in the comonomer is 5 to 8, and the comonomer is advantageously isoprene.
Advantageously, the copolymer contains at least 10% by weight of units derived from butadiene.
After hydrogenation, the copolymer advantageously contains at least 10%, preferably at least 15% by weight, and preferably at most 40% by weight, most preferably at most 35% by weight, of at least one crystalline or crystallizable segment composed primarily of methylene units; to this end the crystallizable segment before hydrogenation advantageously has an average 1,4 or end-to-end enchainment of at least 70 mole, preferably at least 85 mole, per cent. The hydrogenated block copolymer comprises at least one low crystallinity segment composed of methylene and substituted methylene units, derived from one or more alkyl-substituted monomers described above, e.g., isoprene and 2-3-dimethylbutadiene.
Alternatively, the low crystallinity segment may be derived from butadiene by 1,2 enchainment, in which the segment has before hydrogenation an average 1,4 enchainment of butadiene of at most 30, preferably at most 10, percent. As a result, the polymer comprises 1,4-polybutadiene as one block and 1,2-polybutadiene as another. Such polymers are obtainable by e.g., adding a catalyst modifier, as described in WO92/16568.
A further advantageous block copolymer is a star copolymer having from 3 to 25, preferably 5 to 15, arms.
Advantageous embodiments of block copolymers are those comprising a single crystallizable block and a single non-crystallizable block and those comprising a single non-crystallizable block having at each end a single crystallizable block. Other tri- and tetra-block copolymers are also available. In certain preferred embodiments, in which the copolymer is derived from butadiene and isoprene, these are referred to below as PE-PEP and PE-PEP

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