Flow enhancer for petroleum middle distillates

Details Flow enhancer for petroleum middle distillates Flow enhancer for petroleum middle distillates

1999-11-02

2002-05-28

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...

C526S316000, C526S318200, C526S321000, C526S348000

Reexamination Certificate

active

06395852

ABSTRACT:

The present invention relates to copolymers, processes for their preparation, mixtures and concentrates containing them and mineral oil middle distillate compositions and their use as flow improvers and paraffin dispersants.
Middle distillates, such as gas oils, diesel oils and heating oils, which are obtained from mineral oil by distillation, have different contents of paraffins, depending on the origin of the crude oil. Precipitation of solid paraffins occurs at low temperatures. The term cloud point (CP) of the raffinate is used. On further cooling, the lamellar n-paraffin crystals form a house-of-cards structure which leads to setting of the middle distillate although the predominant part of the middle distillate is still liquid. The flowability of the mineral oil distillate fuels is considerably impaired by the precipitated n-paraffins in the temperature range between cloud point (CP) and pour point. The paraffins block filters and result in nonuniform or no fuel feed to the combustion units. Similar faults occur in the case of heating oils.
It has long been known that the crystal growth of the paraffins in the mineral oil middle distillates, combustion fuels and power fuels can be modified by suitable additives. Effective additives prevent the paraffins from forming such house-of-cards structures in the middle distillates and from becoming solid at temperatures only a few degrees Celsius below the temperature at which the first paraffin crystals crystallize out. Instead, fine, well crystallized, separate paraffin crystals are formed, said crystals passing through filters in motor vehicles and heating installations or at least forming a filter cake which is permeable for the liquid part of the middle distillates, so that trouble-free operation is ensured.
Depending on the origin of the crude oil and on the refinery cut, there are however middle distillates in which conventional flow improvers exhibit insufficient response if any at all.
A further disadvantage of conventional flow improvers is based on the fact that, owing to their density being higher than the liquid part, the precipitated paraffin crystals tend increasingly to settle out on the bottom of the container during storage. This results in the formation of a homogeneous low-paraffin phase in the upper part of the container and of a two-phase paraffin-rich layer at the bottom. Since, both in vehicle tanks and in storage or delivery tanks of the mineral oil dealers, 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 falls below the cloud point of the middle distillate, since the amount of precipitated paraffin increases with decreasing temperature.
The mode of action of the conventional flow improvers and paraffin dispersants is based on the modification of the paraffin crystals. These are generally polymers which change the crystal growth of the n-paraffins by cocrystallization (interaction) and thus improve the flow properties of the middle distillate at low temperatures. According to DIN EN 116, the efficiency of the flow improvers is expressed indirectly by measurement of the Cold Filter Plugging Point (CFPP).
Ethylene/vinyl carboxylate copolymers, as disclosed, for example, in U.S. Pat. Nos. 3,048,479 and 3,627,838, have long been used as flow improvers.
WO 95/25755 describes flow improvers based on a copolymer of diketene, unsaturated dicarboxylic acids and olefins.
It is an object of the present invention to provide flow improvers and paraffin dispersants which are effective also in critical mineral oil middle distillates in which conventional flow improvers exhibit insufficient response if any at all.
We have found that this object is achieved, according to the invention, by providing a copolymer of the monomers of the following components A to C and, if required, D, the total amount by weight of which is 100 mol %:
a: from 20 to 80 mol % of at least one ethylenically unsaturated dicarboxylic acid or of an anhydride, ester and/or amide thereof as component A,
b: from 1 to 79 mol % of at least one diketene of the general formula (I)
 where R
1
and R
2
independently are each hydrogen or C
1
-C
30
-alkyl, as component B,
c: from 1 to 79 mol % of at least one vinyl ester, alkyl (meth)acrylate, (meth)acrylonitrile or mixtures thereof as component C and
d: from 0 to less than 0.5 mol % or, if at least 20 mol % of component C are present, from 0 to 20 mol % of at least one further olefinically unsaturated monomer as component D.
Certain copolymers which resemble the novel copolymers are known. Copolymers of maleic anhydride, diketene and a vinyl ether are disclosed in DE-A-25 31 194. They are used as surface-active compounds, glass cleaners or builders for solid and liquid synthetic detergents.
DE-A-25 31 195 discloses similar copolymers which are based on maleic anhydride and diketene and, if desired, vinyl ethers. They are used for the antistatic treatment of organic fiber materials or as care agents for color fabrics.
DE-A-39 13 127 discloses copolymers of maleic anhydride, diketene and (meth)acrylic acid. They are used as additives in pulverulent or liquid detergents and cleaning agents.
The components of the novel copolymers are described below.
COMPONENT A
Component A is used in the novel copolymers in an amount of from 20 to 80, preferably from 20 to 70, in particular from 25 to 68, mol %.
Preferably used components A are compounds of the general formula (II)
R
4
—OC—R
3
C═CR
5
—CO—R
6
  (II)
where R
3
and R
5
independently are each hydrogen or C
1
-C
22
-alkyl, preferably C
1
-C
10
-alkyl, in particular C
1
-C
6
-alkyl, and
R
4
and R
6
independently are each hydrogen or a radical of an NH-, SH- and/or OH-functional compound, in particular hydrogen, —SR
7
, —OR
8
or —NR
9
R
10
,
or, in the case of cis-dicarboxylic acid compounds, R
4
and R
6
together are —O— or —NR
11
— and R
7
to R
11
independently are each C
1
-C
22
-, preferably C
1
-C
10
-, in particular C
1
-C
6
-alkyl or -hydroxyalkyl or C
2
-C
22
-alkenyl, preferably C
2
-C
10
-alkenyl, in particular C
2
-C
6
-alkenyl, each of which may be interrupted by up to 3 oxygen atoms and/or aminoalkylated, or a polyether radical or polyamine radical.
If R
4
and R
6
together form a radical —O—, resulting compounds are acid anhydrides.
Examples of suitable components A are monoethylenically unsaturated dicarboxylic anhydrides of 4 to 8 carbon atoms, such as maleic anhydride, itaconic anhydride, mesaconic anhydride, citraconic anhydride and methylenemalonic anhydride. Among the stated anhydrides, maleic anhydride and itaconic anhydride are preferably used, in particular maleic anhydride.
Dicarboxylic acids, such as fumaric acid, maleic acid, itaconic acid, mesaconic acid, citraconic acid, methylenemalonic acid and their corresponding mono- and dialkyl esters with, preferably, C
1
-C
12
-alcohols, in particular aliphatic linear C
1
-C
6
-alcohols, are furthermore preferred.
The NH- and/or OH-functional compounds may be of the general formula (IV)
A—[CHR
14
—CHR
15
—O]
m
[CHR
16
—(CH
2
—)
x
NH—]
n
H  (IV)
where m is from 0 to 100, preferably from 0 to 50, in particular from 0 to 20,
n and x are each from 0 to 5,
R
14
, R
15
and R
16
independently are each hydrogen or C
1
-C
6
-alkyl and
A is C
2
-C
30
-alkoxy, preferably C
2
-C
20
-alkoxy, in particular C
2
-C
10
-alkoxy, especially C
2
-C
6
-alkoxy, or NR
17
R
18
, where one of the radicals R
17
and R
18
may be hydrogen and at least one of the radicals R
17
and R
18
differs from hydrogen and is C
1
-C
30
-alkyl, preferably C
1
-C
20
-alkyl in particular C
1
-C
6
-alkyl or C
2
-C
30
-alkenyl, preferably C
2
-C
20
-alkenyl, in particular C
2
-C
6
-alkenyl, or —[CHR
19
—CHR
20
—O—]
p
H, R
19
and R
20
independently each being hydrogen or C
1
-C
6
-alkyl and p being from 1 to 100, preferably from 1 to 50, in partic

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