CA2006420A1

CA2006420A1 - Copolymers, mixtures thereof with poly(meth)acrylate esters and the use thereof for improving the cold fluidity of crude oils

Info

Publication number: CA2006420A1
Application number: CA002006420A
Authority: CA
Inventors: Herbert Wirtz; Sigmar-Peter Von Halasz; Michael Feustel; Juliane Balzer
Original assignee: Herbert Wirtz; Sigmar-Peter Von Halasz; Michael Feustel; Juliane Balzer; Hoechst Aktiengesellschaft
Current assignee: Hoechst AG
Priority date: 1988-12-24
Filing date: 1989-12-21
Publication date: 1990-06-24
Also published as: EP0376138B1; EP0376138A3; DE58906771D1; EP0376138A2; NO895218D0; DE3843922A1; NO895218L

Abstract

- ? -ABSTRACT OF THE DISCLOSURE
New copolymers, mixtures thereof with poly(meth)acrylate esters and the use thereof for improving the cold flu-idity of crude oils Copolymers and the use thereof for improving the fluidity of crude oils.

Copolymers of 50 to 99.9% by weight of a C14-C22-alkyl (meth)acrylate and 50 to 0.1% by weight of a comonomer of the formula 1 (1) in which R1 is hydrogen or methyl, R2 is a group of the formulae , , , , , -CH2-O-C2HF3 , or , R3 is C1-C80-alkyl, C2-C80-alkenyl, C5- or C6-cycloalkyl or -cycloalkenyl which can each be substituted by alkyl groups, or is aralkyl, alkaryl or the radical of a dimeric fatty acid, of maleic acid, of succinic acid or of a C6-C22-alkenylsuccinic acid, R4 is C1-C80-alkyl, C1-C80-alkenyl, C5- or C6-cycloalkyl or -cycloalkenyl which can each be substituted by alkyl groups, or is aralkyl or alkaryl, R5 is C6-C20 -alkyl, - ? -m is 2 or 3, n is a number from 1 to 30 and is a number from 2 to 20, and mixtures of such a copolymer with C14-C22-alkyl poly(meth)acrylates.

These copolymers or their mixtures with C14-C22-alkyl poly(meth)acrylates are outstandingly suitable for improving the fluidity of crude oils. Those copolymers are also included here which contain a comonomer of the formula 1 in which R2 additionally can also be a group of the formula , or

Description

;~ )&~0 . . '' HOECHST AKTIENGESELLSCHAFT HOE 88/378 Dr. OT/AP

Description New copolymersl mixtures thereof with poly(meth)acrylate esters and the use thereof for Lmproving the cold flu-idîty of crude oils Depending on the provenance, crude oils contain greater or lesser fractions of dissolved n-paraffins which represent a special group of problems, because they crystallize out on lowering of the temperature and thus can lead to a deterioration in the flow properties of these oils. In pipeline transport, this crystallization can cause depositions on the wall, and in an extreme case, complete blockage of the pipeline. In addition, paraffin precipitations can also lead to complications in production, storage and further processing.
.
The deposition of paraffin starts with the formation of microcrystals in the form of fine platelets and needles, and the viscosity of the crude oil rises significantly.
When these microcrystals grow together into a three-dimensional networX, the crude oil loses its fluidity andfinally solidifies. The solidification point is also called setting point (pour point) and depends on the quantity and distribution of the paraffins dissolved in the oil.

For restoring or maintaining the fluidity, there are a number of measures of a thermal or mechanical nature -for example scraping the paraffin off the inner wall of the pipe, or heating of entire pipelines. It is certainly more elegant to combat the cause of the phenomenon by the addition of so-called setting point depressants ~paraffin inhibitors, pour point depressants), in most cases in quantities of a few hundred ppm. ~ ~

' ~ ,',' -- 2~&~2~:) The effect of a paraffin inhibitor is based on the fact that it co-crystallizes with the paraffins, i.e. inter-feres with the build-up of the regular crystal structure.
At the same time, the high-molecular inhibitor molecules represent crystallization nuclei, so that the number of primarily formed microcrystals is increased. Finally, polar groups within the inhibiLtor molecule prevent the crystals from growing together into a network. The paraffin inhibitor thus does not change the quantity of the paraffin crystallizing out, but the size and polarity of the crystals. The consequence is that the pour point is depressed and the fluidity of the oil is maintained across a wider temperature range.

The paraffin inhibitors are in general homopolymers and copolymers based on olefins, (meth)acrylate esters, maleic acid derivatives and certain vinyl monomers. Thus, ~or example, homopolymers of acrylates having 18 to 24 carbon atoms in the alcohol radical are claimed in German Ofi~enlegungsschrift 2,264,328 for the use as pour point depressants.

In European Patent 0,120,512, copolymers of long-chain acrylate esters and comonomers such as styrene, t-butyl-styrene, acrylonitrile, acrylamide or vinylpyridine are described for the same intended use.

Finally, US Patent 4,547,207 claims copolymers of long-chain acrylate esters and certain vinylidene components for crude oils and residual oils.

A disadvantage of all the substances mentioned is that their activity is not yet sufficient, so that high use concentrations result.

For this reason, novel copolymers are sought whic:h have improved properties as pour point depressants and still show sufficient activity even at low rates of addition.

Z~1~64~

Surprisingly, it has now been found that a marked depres-sion of the pour point of crud~e oils can be achieved by means of the copolymers dQscribed below, and particularly by mixturQs thereof with poly(meth)acrylates.

The present invention relates to copolymers composed of 50 to 99.9% by weight of a C14-C22-alkyl (meth)acrylate and 50 to 0.1% by weight of a comonomer of the formula 1 ~Rl (1) H2C = C

in which R1 is hydrogen or methyl, R2 is a group of the formulae O O O
Il 11 11 . .
.~ -O-C-CH2-0-CH3, -C-O- ~CH2)m-0-C-R3' ~C~ (O-CH2-CH~)n-N~ ~ -C~O~ (CH2)2-C~F2x~
N

CH2-O-C2HF4 , -C-O-CH ~ or ;~

-CH -N-CH -CH=C~ , . .

2 1 2 2 :

R3 is Cl-C80-alkyl, C2-C80-alkenyl, C5- or ~6-cycloalkyl or : ~ :
-cycloalkenyl which can each be substituted by alkyl i::~
groups, or is aralkyl, alkaryl or the radical of a ~:
dimeric fatty acid, of maleic acid, of succinic acid or ~;:
of a C6-C22-alkenylsuccinic acid, .
R4 is Cl-C80-alkyl, C1-C80-alkenyl, C5- or C6-cycloalkyl or i~
-cycloalkenyl which can each be substituted by alkyl groups, or is aryl, aralkyl or alkaryl, R5 is C6-C20-alkyl, ~ :;
m is 2 or 3, -- _ 4 n is a number from 1 to 30 and x is a number from 2 to 20, and mixtures of these copolymers with Cl~-C22-alkyl poly(meth)acrylate~.

Those comonomers are preferred in which R3 snd R4 are C6-C3~-alkyl, C6-C36-alkenyl, cyclohexyl, cyclohexenyl, naphthenyl, phenyl, benzyl or C1-C4-mono-, -di- or -tri-alkylphenyl or R3 can also be the radical of a dLmeric fatty acid, of maleic acid, of succinic acid or of a C6-C1e-alkenylsuccinic acid, and x is a number from 4 to 16.

The invention also relates to polymer mixtures of 10 to 90% by weight of a Cl4-C22-alkyl poly(meth)acrylate (B) and 90 to 10% by weight of an abovementioned copolymer (A).
A:B mixing ratios of 20 to 40% by weight of polymer A and 80 to 60% by weight of polymer B are preferred.

The abovementioned copolymers (A) and mixtures thereof wi~h the C~4-C22-alkyl poly(meth)acrylates (B) are out-standingly suitable for improving the fluidity of crude oils. Fu~thermore, it has been found that those copoly-mers ~A) and mixture~ thereof with the poly(meth)acrylatee~ers (B) are also suitable for improving the fluidity of crude oils in which the copolymer (A) contains those monomer6 of the above formula (1) in which R2 additionally i8 a group of the formulae -N o , -N ~ or -COO O

The preparation of the polymers described is carried out by conventional proces~es in ~olution in an aromatic hydrocarbon, hydrocarbon mixture or an n-paraffin at SO-100C and with the ~tarters conventional for free-radical po}ymerization~. The proportion by weight of the monomers is here between 50 and 90%.

2~ 4;~
_ 5 --In some cases, the polymers can be prepared by two routes, namely in the case of the acylated hydroxyalkyl acrylates. On the one hand, the hydroxyalkyl acrylates can be copolymerized directly with the (meth)~crylate esters and then esterified by the usual method or, on the other hand, the monomeric die~;ter can also be ~repared first and then copolymerized. Because of the different reactivities, the two pxeparation methods result in different molecular weight distributions. Which of the copolymers shows the greater effect is then dependent on the composition of the crude oil~

The polymers and polymer mixtures described are distin-guished by a broad activity and allow an improvement in the flow properties of many crude oils at used quantities of 10 - 1,000 ppm.

~he examples which follow are intended to explain the invention without limiting it.

I. Preparation of the monomers 1~ The pxeparation of a few monomers will be described ¦~ 20 below, if these are not common commercial products.

ample 1 `~

Preparation of 2-naphthenoyloxyethyl acrylate 148 g (0.5 mol) of naphthenic acid in 200 g of toluene ` are first introduced into a 1 1 four-necked flask with a stirrer, contact thermometer and reflux condenser as well as a gas inlet tube, and heated to 50C. 59.5 g (0.5 mol) of thionyl chloride are added thereto dropwise in the course of 30 minutes, and reflux is maintained for one further hour after the end of the addition. The mixture -is allowed to cool again to 50C and, while pa~sing through nitrogen, a solution of 58 g (0.5 mol) of hy~
droxyeth~l acrylate in 58 g of toluene is added in the course of 30 minutes. After the end of the addition, the mixture is held at 60C for 4 hours and a vigorous stream of nitrogen is passed through the solution during this period. Toluene is removed at 75C and 20 mm ~g. This gives 98 g (quantitative yield) of a brown oil.

The other claimed esters can be prepared from hydroxy-propyl (meth)acrylate in an analogous manner.

If the subsequent polymeriza~ion is to be carried out in high-boilin~ aromatics or in n-paraffins, the esterifi-cation can also take place directly in these solvents. Ofcourse, there is then no distillation of the solvent.

~xample 2 Préparation of benzyl acrylate .. .
144 g (2 mols) of acrylic acid, which have been inhibited lS with 1.4 g of hydroquinone monomethyl ether, are dis-solved in 139 g of a high-boiling aromatics mixture in a 1 1 four-necked ~lask with stirrer, contact thermometer, water separator and gas inlet tube. 3.2 g of p-toluene-sulfonic acid are added thereto, the mixture i8 heated to 70C and, at this temperature, 216 g (2 mols) of benzyl alcohol are allowed to run in over a period of 10 minutes. After the end of the addition, the mixture is hsated to reflux. To accelerate the removal of water, air is passed through the solution. The reaction is complete after about 5 hours. The progress of the reaction is monitored via the acid number. After 5 hours, the latter gives a conversion of about 97~.

The n-alkyl (meth)acrylates and cyclohexyl acrylates are prepared in the same way in accordance with these in-structions.

~xEmple 3 Preparation of l-acryloylosyethyl~3-tallow-fatty alkyl-hexahydropyrLmidine 1,000 g (2.90 mols) of tallow-fatty alkyl-propylenedi-amine are dissolved in 1,500 ml of toluene in a 6 1 four-necked flask with a stirrer, contact th~rmometer and water separator. 86~95 g (2.90 mols) of paraformaldehyde are added thereto in portions at room temperature. During the addition, attention must be paid to foaming. After the end of the addition, the mixture is boiled for 6 hours under a water separator. Sl ml of water in total are ~eparated out. After the end of the reaction, the solvent is removed in vacuo. This gives 1~030 g of a light yellow paste, which is then ethoxylated at 130C by the usual methods. For the esterification with acrylic acid, the ethoxylate thus obtained, of molecular weight 410 corresponding to 1.2 mols of ethylene oxide/mol, i8 dissol~ed together with 181 g ~25 mols) of acrylic acid in 500 g of toluene, 1 g of p-toluenesulfonic acid is added, and the whole is haated for 5 hours at 110-130C
under a water separator. 34 g of water in total separate out (about 75~ of theory). The solvent is then removed in vacuo. The crude material thus obtained was not further purified for the copolymerizations.

II. Preparation of the poly~ers Example 1 16~ g (0.30 mol) of a stearyl acrylate, prepared analo-gously to Example I.2, 58~ in toluene, and 3.3 g (0.028 mol) of hydroxyethyl acrylate were first introduced, together with 1.0 g of dodecylmercaptan, into a 1 1 four-necked flask fitted with a ~tirrer extending to near the wall, reflux condenser, contact thermometer, gas inlet tube and dropping funnel. At an internal temperature of 60C, a solution of 0.5 g of azo-bis-(isobutyronitrile) z~

in 27 g of toluene is added tllereto over a period of 30 minutes, while passing through nitrogen. After the exothermic reaction has subsided, the mixture is kept for a further 2 hours at 80C. For the esterification of the free hydroxyl group, 7.5 g (0.028 mol) of stearic acid chloride are added dropwise at 50 and stirring is continued at this temperature until hydrogen chloride is no longer ~volved. This gives a light-brown copolymer which is ad~usted with toluene to 50% solids content.
K value (5% in toluene/25C) according to Ubbelohde:
19.8.

~a~ple 2 As in ~xample II.l, 135 g ~0.29 mol) of 58~ stearyl-acrylate are first introduced at 50C together with - 15 9.5 g (0.026 mol) of a 2-stearoyloxyethyl acrylate prepared analogously to Example I.1. After the addition of 0.5 g of azo-bis-(isobutyronitrile) in 16 g of tolu-en~, the mixture i8 heated at 50, 60, 70, 80 and 90C
~bath temperature) for 1 hour at each of these tempera-tures. This gives a light-brown copolymer which is ad~usted with toluene to a solids content of 50~.
K value (S~ in toluene/25C) according to Ubbelohde:
48.9.

The polymerizations with the acetyl and naphthenoyl deri~atives also proceed correspondingly.

~ample 3 , As in Example II.1, 75 g (0.178 mol) of 60% Cl2-C,4-alkyl acrylate in toluene are copolymerized with 45 g (0.38 mol) of vinyl methoxyacetate. The starter used is a solution of 0.5 g of azo-bis-(isobutyronitrile) in 10 g of toluene. The mixture iB kept at 50, 60, 70, 80 and 90C for 1 hour at each of these temperatures, giving a yellow polymer of K value 31.5.

- ~æo~-20 ~a~ple 4 As in Example II.l, 11.7 g ~0.35 mol) of stearyl acrylate in Cl2-Cl6-n-paraffin are copolymerized together with 11.7 g (0.925 mol3 of 1-acryloyloxyethyl-3-tallow-fatty alkyl-hexahydropyrimidine. 1 g of tert.~butyl perpiva-late, di~olved in 20 g of C12-Cl6-n-paraffin, is used as the starter. The solution should not fall below 50~ of monomers in total. ~hen the temperature profile described in Examples II.2 and II.3 is maintained, ~ highly viscous light-brown product of K value 45.40 is obtained.

Analo~ously to the methods described in Examples II.2, II.3 and II.4, long-chain ac~ylates can be copolymerized with the following monomer~ listed in the table. The molar ratios and the K values are listed for some typical ; 15 polymers.

.

`:

2~)&~2~

Monomer IMonomer II Molar R value Example CH2=CHCOR ~atio O
.... . _ 5R-C18H37~ - C6F13 9? : 3 40,3 5 R C18H37 ~ o~ C8F17/ 95 5 44,8 6 R=C18H37 ~ C8F17/ 95 : 5 48~1 7 R C18H37 O`C2HF4 99,5 : 0,5 44~3 8 15R=C18H37 o ~ 90 : 10 37,8 9 R=C18H37 ~ ~ 90 : 10 39~2 10 R C18H37 ~ `N ~ 99 : 1 34,1 11 R=C18H37/ ~ 99 : 1 34,5 12 C22H43 ~
o - o R=C18H37 ~ o~ QH 99 : 1 24,5 13 O

N~
30R-C18H37/ ~ ~ 90 : 10 36,3 14 ... . . _ . _ . . .

,,~:.. -: . .- . .: . . : -The effectiveness of the copolymers inve~tigated is described by reference to the determination of the pour points. This i8 carried out according to DIN ISO 3016.
Accordingly, after prior heating, the sample is cooled under fixed conditions and tested for fluidity at tem-perature intervals of 3C each.

Using the compounds and mixtures according to the inven-tion, pour point measurements were carried out on an Indian oil which has a pour point of 29C in untreated 0 8ample8. The results are ~ummarized in the following ~ ~ ~
table: ~:

'"'"''' .'7'' '.' ~ ' ~' ' . ' " ' ' ' ' . , ' , ' ' , ' ', . ''" ' . ''.. ,.'' . ,' ., ,, ", ' ' . ' .. " '. ' ' ' Z1~4~

Product Quantity Pour used point (ppm) (~C) Polymer according to Example 1 300 21 Polymer according to Example 1 500 17 Mixture of 20% of polymer ac-cording to Exhmple 1 and 80~ 300 12.5 of Cl~-C~2-alkyl polyacrylate " 500 10 . . . _ _ Polymer according to Example 2 300 20.5 Polymer according to Example 2 500 18 Mixture of 20% of polymer ac-cording to Example 2 and 80% 300 12 of Cl8-Cz2-alkyl polyacrylate " 500 11 Polymer according to Example 3 300 29 PoIymer according to Example 3 500 25 Mixture of 20% of polymer ac-cording to Example 3 and 80~ 300 20 of C1B-C22-alkyl polyacrylate " 500 15.5 -Polymer according to Example 4 300 21 Polymer according to Example 4 500 19.5 Mixture o~ 20~ of polymer ac-cording to Example 4 and 80% 300 15 of Cl8-C22-alkyl polyacrylate " 500 17 : . . . .
,: j , , i . . . ~ . . . . . .
, .. .. . .... . . . .
, .:. ,. ,.. , . . . . : -:: ~ . : . . ~
.. -., ., . , . . ~ .

4~

Product Quantity Pour -used point (ppm) ~C) Polymer according to Example 5 300 19 Polymer according to Example 5 500 17 Mixture of 20% of polymer ac-cording to Example 5 and 80~ 300 11 of Cl8-C22-alkyl polyacrylate " 500 10 Polymer according to Example 6 300 20 Polymer according to Example 6 500 18 Mixture of 20% of polymer ac-cording to ExamplP 6 and 80~ 300 13 of C~8-Czz-alkyl polyacrylate " 500 12.5 Polymer according to Example 7 300 19 Po~ymer according to Example 7 500 17.5 Mixture of 20~ of polymer ac-cording to Example 7 and 80~ 300 13.5 of C~8-Cz2-alkyl polyacrylate " 500 12 . ~
Polymer according to Example 8 300 16.5 Polymer according to Example 8 500 11 Nixture of 20% of pol~mer ac- ;`:
cording to Example 8 and 80% 300 10 of C18-Cz2-alkyl polyacrylate " 500 7 :~`
-~
'' ', ' ;~ 4~

Product Quantity Pour used point (ppm) (C) . . .
5Polymer according to Example 9 300 19.5 Polymer according to ~xample 9 500 18 Mixture of 20% of pol~mer ac-cording to Example 9 and 80% 300 11.5 of C1~-C22-alkyl polyacrylate " 500 8 Polymer according to Example 10 300 20.5 Polymer according to Example 10 500 18 Mixture of 20~ of polymer ac-15cording to Example 10 and 80% 300 10.5 of Cl~-C22-alkyl polyacrylate ~I 500 ~.5 -Polymer according to Example 11 300 22.5 Poly.mer according to Example 11 5Q0 lB
Mixture of 20~ of polymer ac~
cordin~ to Example 11 and 80% 300 16.5 o Cl8-C22-alkyl polyacrylate Il S00 13 Polymer according to Example 12 300 19 Polymer according to Example 12 500 16 Nixture of 20~ of polymer ac-cording to Example 12 and 80% 300 18 of Cl~-C~-alkyl polyacrylate " 500 14 Polymer according to Example 13 300 22 Polymer according to Example 13 500 18 Mixture of 20~ of polymer ac-cording to Exlmple 13 and 80% 300 18 of Cl8-C~-alkyl polyacrylate .... :. . ~ , - . . ...

.. , , .. . - . ~ . ., 26~

Product Quantity Pour used point (ppm) (C) Polymer according to Example 14 300 18 Polymer according to Example 14 500 16 Mixture of 20~ of polymer ac- :
cording to Example 14 and 80~ 300 13 ~
of Cl~-C22-alkyl polyacrylate ~' 500 ll 0Paradyne 70 300 25.5 500 23.0 _~
~Paradyne 85 500 30.5 ; . .

0Shellswim 5 T 500 14.0 0Shellswim 11 T 300 20.5 - 500 14.0 ~ :
"'':' ,`', `
The four la~t-mentioned product6 represent commercially :: .
available flow improvers. `.. :`

.:, , .i,.,,.. , :. , ~, : .-- , . ~ .. . , ,. ~.. . . .

Claims

1. A copolymer composed of 50 to 99.9% by weight of a C14-C22 alkyl (meth)acrylate and 50 to 0.1% by weight of a comonomer of the formula 1 (1) in which R1 is hydrogen or methyl, R2 is a group of the formulae , , , , , , or , R3 is C1-C80-alkyl, C2-C80-alkenyl, C5- or C8-cycloalkyl or -cycloalkenyl which can each be substituted by alkyl groups, or is aralkyl, alkaryl or the radical of a dimeric fatty acid, of maleic acid, of succinic acid or of a C6-C22-alkenylsuccinic acid, R4 is C1-C80-alkyl, C1-C80-alkenyl, C5- or C6-cycloalkyl or -cycloalkenyl which can each be substituted by alkyl groups, or is aryl, aralkyl or alkaryl, R5 is C6-C20-alkyl, m is 2 or 3, n is a number from 1 to 30 and X is a number from 2 to 20, and mixtures of such a copolymer with C14-C22-alkyl poly(meth)acrylates.

2. A copolymer as claimed in claim 1, containing a comonomer of the formula (1), in which R4 is C6-C36-alkyl, C8-C36-alkenyl, cyclohexyl, cyclohexenyl, naphthenyl, phenyl, benzyl, C1-C4-mono-, -di- or -tri-alkylphenyl or R3 can also be the radical of a dimeric fatty acid, of maleic acid, of succinic acid or of a C8-C18-alkenylsuccinic acid, and x is a number from 4 to 16.

3. A mixture of 10 to 90% by weight of a copolymer as claimed in claim 1 and 90 to 10% by weight of a C14-C22-alkyl poly(meth)acrylate.

4. A mixture of 20 to 40% by weight of a copolymer as claimed in claim 1 and 80 to 60% by weight of a C14-C22-alkyl poly(meth)acrylate.

5. The use of a copolymer composed of 50 to 99.9% by weight of a C14-C22-alkyl (meth)acrylate and 50 to 0.1% by weight of a comonomer of the formula 2 (2) in which R1 is hydrogen or methyl, R2 is a group of the formulae , , , , , , , , , or R3 is C1-C80-alkyl, C2-C80-alkenyl, C5- or C6-cycloalkyl or -cycloalkenyl which can each be substituted by alkyl groups, or is aralkyl, alkaryl or the radical of a dimeric fatty acid, of maleic acid, of succinic acid or of a C8-C22-alkenylsuccinic acid, R4 is C1-C80-alkyl, C1-C80-alkenyl, C5- or C6-cycloalkyl or -cycloalkenyl which can each be substituted by alkyl groups, aralkyl or alkaryl, R5 is C6-C20-alkyl, m is 2 or 3, n is a number from 1 to 30 and X is a number from 2 to 20, and of mixtures of such a copolymer with C14-C22-alkyl poly(meth)acrylates for improving the fluidity of crude oils.

6. Use of a copolymer, as claimed in claim 5, containing a comonomer of the formula (1), in which R3 and R4 are C5-C36-alkyl, C6-C36-alkenyl, cyclohexyl, cyclohexenyl, naphthenyl, phenyl, benzyl or C1-C4-mono-, -di- or -tri-alkylphenyl, or R3 can additionally be the radical of a dimeric fatty acid, of maleic acid, of succinic acid or of a C9-C18-alkenylsuccinic acid, and x is a number from 4 to 16, for improving the fluidity of crude oils.

7. The use of a mixture of 10 to 90% by weight of a copoly-mer as claimed in claim 4 and 90 to 10% by weight of a C14-C22-alkyl poly(meth)acrylate for improving the fluidity of crude oils.

8. The use of a mixture of 20 to 40% by weight of a copolymer as claimed in claim 4 and 80 to 60% by weight of a C14-C22-alkyl poly(meth)acrylate for improving the fluidity of crude oils.