POLYMERES D'ACIDE ACRYLIQUE, D'ACIDE 2-ACRYLAMIDO- 2-METHYLPROPYL-SULFONIQUE ET D'ACIDE 2-ACRYLAMIDO-2- METHYLPROPYL-PHOSPHONIQUE

ACRYLIC ACID/2-ACRYLAMIDO-2-METHYLPROPYL-SULFONIC ACID/2-ACRYLAMIDO-2-METHYLPROPYL PHOSPHONIC POLYMERS

Abrégé anglais

TITLE OF THE INVENTION
ACRYLIC ACID/2-ACRYLAMIDO-2-METHYLPROPYL-
SULFONIC ACID/2-ACRYLAMIDO-2-METHYLPROPYL PHOSPHONIC
POLYMERS

ABSTRACT OF THE DISCLOSURE
The present invention is directed to a
polymer, having an intrinsic viscosity of 0.05 to 4.5
dl/g, in 1.0 M NaCl, prepared from:
(A) 35 to 65%, by weight, of acrylic acid or
methacrylic acid;
(B) 15 to 45%, by weight, of 2-acrylamido-2-methyl-
propylsulfonic acid or 2-methacrylamido-2-methyl-
propylsulfonic acid; and
(C) 15 to 25%, by weight, of 2-acrylamido-2-methyl-
propyl phosphonic acid or 2-methacrylamido-2-
methylpropylphosphonic acid.

Revendications

- 7 -

WHAT IS CLAIMED IS:

1. A polymer, having an intrinsic viscosity
of 0.05 to 4.5 dl/g, in 1.0 M NaCl, prepared from:
(A) 35 to 65%, by weight, of acrylic acid or
methacrylic acid;
(B) 15 to 45%, by weight, of 2-acrylamido-2-methyl-
propylsulfonic acid or 2-methacrylamido-2-methyl-
propylsulfonic acid; and
(C) 15 to 25%, by weight, of 2-acrylamido-2-methyl-
propyl phosphonic acid or 2-methacrylamido-2-
methylpropylphosphonic acid.

2. The polymer of Claim 1, prepared from
acrylic acid, 2-acrylamido 2-methylpropylsulfonic
acid, and 2-acrylamido-2-methylpropyl phosphonic acid.

3. The polymer of Claim 1, prepared from
40 to 60%, by weight, acrylic acid; 20 to 40%, by
weight, 2-acrylamido-2-methylpropylsulfonic acid, and
15 to 25%, by weight, 2-acrylamido-2-methylpropyl
phosphonic acid.

4. The polymer of Claim 1, having an
intrinsic viscosity of 0.05 to 2.5 dl/g, in 1.0 M
NaCl.

Description

2 0 5 0 S/l O O ~A ~ 2,e~




- 1 - C-1405

TITLE OF THE INVENTION
ACRYLIC ACID/2-ACRYLAMIDO-2-METHYLPROPYL-
SULFONIC ACID/2-ACRYLAMIDO-2-METHYLPROPYL PHOSPHONIC
POLYMERS




BACKGROUND OF THE INVENTION
U.S. Patent 3,928,196 discloses the use of a
copolymer of 2-acrylamido-2-methylpropylsulfonic acid
and acrylic acid as scale inhibitors.
Published European Patent Application 89,654
discloses copolymers of 2-acrylamido-2-methylpropyl
phosphonic acid and acrylamide or acrylic acid as
scale inhibitors.

DESCRIPTION OF THE INVENTION
The present invention is directed to a
polymer, having an intrinsic viscosity of 0.05 to 4~5
dl/g, in 1.0 M NaCl, prepared from:
(A) 35 to 65%, by weight, of acrylic acid or
methacrylic acid;


2050S/1003A - 2 - C-1405

(B) 15 to 45%, by weight, of 2-acrylamido-2-methyl-
propylsulfonic acid or 2-methacrylamido-2-methyl-
propylsulfonic acid; and
(C3 15 to 25%, by weight, of 2-acrylamido-2-methyl-
propyl phosphonic acid or 2-methacrylamido-2-
methylpropylphosphonic acid.
The polymers are prepared fro]m 35 to 65%,
preferably 40 to 60%, by weight, acrylic acid or
methacrylic acid, preferahly acrylic acid; 15 to 45~,
10 preferably 20 to 40%, by weight, 2-acrylamido-2-
methylpropylsulfonic acid (hereinafter "AMPS") or
2-methacrylamido-2-methylpropyl~ulfonic acid,
preferably AMPS; and 15 to 25~, preferably 20%, by
weight, 2-acrylamido-2-methylpropyl phosphonic acid
(hereinafter "AMPPA") or 2-methacrylamido-2-methyl-
propylphosphonic acid. Terpolymers are preferred.
AMPPA may be prepared as described ln U.S. Pat~nt
~,526,728.
The polymers may be prepared by mixing the
monomers preferably in the presence of a free radical
initiator. Any free radical initiator may be used.
Examples include peroxides, azo initiators and redox
systems. The polymerization may also be initiated
photochemically. The preferred catalysts are sodium
persulfate or a mixture of ammonium persulfate and
any azo type initiator, such as 2,2'-azobis~(2,4-
dimethyl-4-methoxyvaleronitrile).
The polymerization may be conducted by any
of a variety of procedures, for example, in solution,
suspension, bulk and emulsions.
The reaction temperature is not critical.
The reaction will generally occur between 10 and
100C9 preferably 40 to 60C. It is generally
impractical to run the reaction below room
temperature because the reaction is too slow. Above


2050S/1003A - 3 - C-1405

a temperature of 60C, the molecular weight of the
polymer tends to decrease. The reaction, depending
on the temperature, generally takes from 1 to 12
hours. Measuring for residual monomer will verify
when the reaction is complete.
The pH of the reaction mixture is not
critical. The pH is generally in the range of 3.5 to
9Ø
The percent solids in the reaction mixture
is not critical. The preferred range is 1 to 50%, by
weight, solids.
The molecular weight of polymers is
difficult to accurately measure. The polymers are,
instead, usually identified by intrinsic viscosity.
The intrinsic viscosity of the polymer is critical in
the instant invention. The intrinsic viscosity
should be .05 to 4.5, preferably 0.05 to 2.5 dl/g, in
1.0 M sodium chloride (measured in a 75 Cannon
Ubbelohde capillary viscometer).
The polymers of the instant invention have
been found to be effective as scale inhibitors,
particularly in inhibiting calcium phosphate scale.

EXAMPLES 1 AND 2
The polymers of the examples were produced
by mixing the monomers indicated in Table 1, in the
amounts, solids concentration, initial temperatures
and pH indicated. The monomer mix was purged with
nitrogen for one hour. The solvent was deionized
water. The initiator was added and the components
allowed to react for about 3 hours.




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2050S/1003A - 5 - C-1405

EXAMPLES 3 AND 4
-
Various polymers were screenecl for threshold
inhibition of calcium carbonate and ca]cium phosphateO
Stagnant flask tests were used with so]utions stored
for 24 hours at constant temperature. The standard
test conditions used were as follows:

Calcium Calcium
Carbonate Phosphate
lO Calcium, mg/l 200 200
Bicarbonate, mg/l600 ---
Phosphate, mg/l --- 9
pH 8.0 8.5
Temperature, C 60 60
Two flasks were used for each test; one for
a control (no inhibitor) and one with the polymer.
The percent inhibition was determined by the
following equation:

S - S
Percent Inhibition = x lO0 where:
-
S - S

SI = level of test specie initially;
Sc = level of test specie at end of
control test; and
ST = level of test specie at end of
inhibitor test,
Calcium was used as the test specie in the
calcium carbonate test, and phosphate was the test
specie in the calcium phospha~e test. The results
are summarized in Table II.



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