Ampholytic polymers and polymeric microemulsions

Quaternary dialkylaminomethyl polymers derived from (alk)acrylamide and about 1 to about 15 mole percent ethylenically unsaturated anionic comonomer wherein the resulting ampholytic polymer has a standard viscosity of at least about 2.1 cps are disclosed. Processes for the preparation of these polymers and their use in flocculating suspended material in a variety of aqueous dispersions are also disclosed.

This invention relates to ampholytic polymers, more specifically to 
polymers of quaternized, aminomethyl (alk)acrylamide and about 1 to about 
15 mole percent anionic comonomer. Microemulsions comprising such polymers 
are also disclosed. Methods of using these polymers and microemulsions for 
flocculating suspended material in a variety of aqueous dispersions and 
processes for the preparation of the ampholytic polymers and 
microemulsions containing such polymers are also encompassed within this 
invention. 
BACKGROUND OF THE INVENTION 
Amino methylated or Mannich (alk)acrylamide polymers in inverse 
(water-in-oil) microemulsion form are used as flocculants for separating 
suspended material from aqueous dispersions. As such, they are preferred 
over other types of flocculants because of their high solids content, low 
bulk viscosity, their tendency to reduce interpolymer crosslinking 
problems, and superior performance. These inverse microemulsion Mannich 
acrylamide polymers (microemulsion Mannich PAMS) are described in U.S. 
Pat. Nos. 4,956,399; 4,956,400; 5,037,863; 5,132,023 and 5,037,881, which 
are incorporated herein by reference. Oftentimes, these Mannich acrylamide 
polymers are quaternized and used in their highly charged cationic state. 
It has been found, however, that for certain flocculant applications, the 
cationic charge on the microemulsion Mannich PAMS may be too high and may 
inhibit the performance of the polymeric flocculant. For example, many 
aqueous dispersions containing paper deinking sludge or other suspended 
material resulting from the processing of recycled paper have relatively 
low cationic demand. Consequently, highly cationized quaternary 
microemulsion Mannich PAMS have not performed as efficiently as desired in 
these flocculation applications. Ampholytic polymers have been found to be 
a viable alternative. 
Ampholytic polymers in emulsion form are known to be useful for treating 
sewage and industrial wastes as disclosed in U.S. Pat. Nos. 4,330,450 and 
4,363,886. But these polymeric emulsions do not provide the benefits of 
microemulsions, (e.g. higher solids and reduced crosslinking). 
Furthermore, the amount of anionic comonomer sufficient to provide a 
polymer with a standard viscosity of at least 2.1 cps for effective 
treatment of sludge having a relatively low cationic demand is also not 
provided. 
Japanese patent application No. 63-218246 discloses a polymeric 
water-in-oil emulsion having anionic and cationic properties which is made 
by mixing an anionic polymeric inverse emulsion having 5 to 100 mole 
percent anionicity with a cationic polymeric inverse emulsion having 5 to 
100 mole percent cationization. This system does not, however, provide 
ampholytic properties, due to charge neutralization, since the charges 
result from a mixture of two differently charged polymers as opposed to a 
single ampholytic polymer. 
Compositions comprising crosslinked anionic or amphoteric polymeric 
microparticles, as taught in U.S. Pat. No. 5,171,808, may be used for 
facilitating the solid-liquid seperation of various biologically treated 
suspensions but such polymeric microparticles only have solution 
viscosities of at least 1.1 mPa.s and may not flocculate as well as 
desired. 
While ethylenically unsaturated anionic comonomers have been incorporated 
into microemulsion Mannich PAMs, see e.g., U.S. Pat. No. 4,956,400 and 
U.S. patent application Ser. No. 07/860,542 filed on Mar. 30, 1992, now 
abandoned and incorporated into Mannich PAMs, see e.g., U.S. Pat. No. 
4,137,164, the effective amount of anionic comonomer cannot be ascertained 
from these patents and not all of the resulting anionic copolymers 
disclosed in the patents are particularly effective in treating aqueous 
dispersions having a low cationic demand or high total solids. Even if one 
were to quaternize the resulting anionic copolymers to provide ampholytic 
copolymers, the resulting ampholytic copolymers would also be ineffective 
for treating aqueous dispersions, particularly those having low cationic 
demand and/or high total solids. There exists a need for polymeric 
flocculant that can be prepared at high polymer solids levels and can 
perform effectively in treating aqueous dispersions especially those 
having a low cationic demand or high total solids. It has now been found 
that copolymers of quaternary aminomethyl (alk)acrylamide and about 1 to 
about 15 mole percent of at least one ethylenically unsaturated anionic 
comonomer wherein such copolymers have a standard viscosity of at least 
2.1 cps provide superior flocculating performance relative to 
microemulsion Mannich PAMS and other flocculant agents in the art with 
respect to certain aqueous dispersions containing suspended materials. 
While these polymers provide the benefits of microemulsion Mannich PAMS, 
such as low bulk viscosity and high solids content, and may be used like 
the known Mannich PAM microemulsions in various flocculation applications, 
the ampholytic polymers of the present invention also tend to be more 
effective in flocculating aqueous dispersions which don't flocculate well 
using highly cationically charged polymers, i.e., aqueous dispersions such 
as sludges which have a somewhat lower cationic demand. 
Therefore the present invention provides ampholytic polymers or copolymers 
of quaternized dialkylaminomethylated (alk)acrylamide and anionic 
comonomer which provide all of the benefits of microemulsion Mannich PAMS 
yet also tend to be more effective than current cationic flocculants in 
treating suspended solids in aqueous dispersions having somewhat lower 
cationic demands and sludges having total solids levels of at least about 
4 weight percent. 
The present invention also provides a process for preparing an ampholytic 
copolymer and an inverse microemulsion ("microemulsion" herein) comprising 
an ampholytic copolymer of quaternary dialkylaminomethyl (alk)acrylamide 
and ethylenically unsaturated anionic comonomer having a standard 
viscosity of at least 2.1 cps. Methods of using these ampholytic polymers 
to flocculate suspended material in various aqueous dispersions such as 
deinking process waters resulting from the processing of recycled paper 
and various sludge-containing dispersions are also encompassed within the 
present invention. 
SUMMARY OF THE INVENTION 
According to the present invention, there is provided copolymers of 
quaternary dialkylaminomethyl (alk)acrylamide and about 1 to about 15 mole 
percent ethylenically unsaturated anionic comonomer which have a standard 
viscosity of at least about 2.1 cps when measured at 0.1 percent 
concentration in a 1 molar sodium chloride solution. It is preferred that 
the anionic comonomer content range from about 2 to about 12 mole percent, 
more preferably from about 5 to about 10 mole percent, which results in a 
copolymer (also called polymer herein) having a standard viscosity of at 
least about 2.8 cps. Most preferably about 10 mole percent ethylenically 
unsaturated anionic comonomer is incorporated into the polymer to provide 
a polymer having a standard viscosity of approximately 2.8 cps. Preferred 
anionic comonomers include acrylic acid, methacrylic acid and 2-acrylamido 
2-alkyl sulfonic acid. Acrylamide is a preferred (alk)acrylamide. The 
presence of the anionic comonomer and quaternary dialkylaminomethyl 
(alk)acrylamide units in the polymer render it ampholytic. 
The ampholytic polymers of the present invention are prepared by 
polymerization in an inverse (water-in-oil) microemulsion, also referred 
to herein as microemulsion polymerization. A preferred process for 
preparing ampholytic polymeric microemulsions of the present invention 
comprises: 
(a) admixing in any order: 
(i) an aqueous solution comprising (alk)acrylamide monomer and about 1 to 
about 15 mole percent ethylenically unsaturated anionic comonomer; 
(ii) at least one hydrocarbon liquid; and 
(iii) an effective amount of surfactant or surfactant mixture so as to form 
an inverse microemulsion; 
(b) subjecting the inverse microemulsion obtained in step (a) to 
polymerization conditions; 
(c) reacting the polymer resulting from step (b) with an effective amount 
of formaldehyde and a secondary amine, or a complex formed by said 
formaldehyde and secondary amine; 
(d) quaternizing the polymer resulting from step (c); and 
(e) heat treating the quaternized polymer resulting from step (d) to 
provide a polymer with a standard viscosity of at least about 2.1 cps when 
measured at 0.1 percent concentration in a 1 molar sodium chloride 
solution, by: 
(i) treating the polymer by adding, in any order, effective amounts of 
acid, a formaldehyde scavenger compound and water; and 
(ii) heating the treated polymer to a temperature of from about 40.degree. 
to about 80.degree. C. for about 3 to about 20 hours. 
In a second embodiment, the ampholytic polymeric microemulsion is prepared 
by: 
(a) reacting 
(i) at least one (alk)acrylamide monomer; and 
(ii) formaldehyde and a secondary amine or a complex thereof in an aqueous 
solution to produce a tertiary aminomethyl substituted (alk)acrylamide 
monomer; 
(b) admixing 
(i) said aqueous solution of substituted (alk)acrylamide monomer and about 
1 to about 15 mole percent ethylenically unsatured anionic comonomer; and 
(ii) at least one hydrocarbon liquid; and 
(iii) an effective amount of surfactant or surfactant mixture so as to form 
an inverse microemulsion; 
(c) subjecting the inverse microemulsion obtained in step (b) to 
polymerization conditions; and 
(d) quaternizing the polymer resulting from step (c); and 
(e) heat treating the quaternized polymer resulting from step (d) to 
provide a polymer with a standard viscosity of at least about 2.1 cps when 
measured at 0.1 percent concentration in a 1 molar sodium chloride 
solution, by: 
(i) treating the polymer by adding, in any order, effective amounts of 
acid, a formaldehyde scavenger compound and water; and 
(ii) heating the treated polymer to a temperature of from about 40.degree. 
to about 80.degree. C. for about 3 to about 20 hours, and 
A third embodiment sets forth a process for preparing the ampholytic 
polymeric microemulsion comprising: 
(a) admixing 
(i) an aqueous solution comprising an (alk)acrylamide monomer and about 1 
to about 15 mole percent ethylenically unsaturated anionic comonomer, a 
formaldehyde and a secondary amine or a complex thereof; 
(ii) at least one hydrocarbon liquid; and 
(iii) an effective amount of surfactant or surfactant mixture, so as to 
form an inverse microemulsion; 
(b) subjecting the inverse microemulsion obtained in step (a) to 
polymerization conditions and simultaneously allowing the formaldehyde and 
secondary amine to react with the (alk)acrylamide amide groups; and 
(c) quaternizing the polymer resulting (d) from step (b); and 
(d) heat treating the quaternized polymer resulting from step (d) to 
provide a polymer with a standard viscosity of at least about 2.1 cps when 
measured at 0.1 percent concentration in a 1 molar sodium chloride 
solution, by: 
(i) treating the polymer by adding, in any order, effective amounts of 
acid, a formaldehyde scavenger compound and water; and 
(ii) heating the treated polymer to a temperature of from about 40.degree. 
to about 80.degree. C. for about 3 to about 20 hours, and 
A process for preparing an ampholytic polymer which comprises preparing an 
ampholytic polymeric microemulsion according to any of the three 
procedures described above, though preferably the first procedure, and 
recovering the ampholytic polymer from the ampholytic polymeric 
microemulsion is also provided by the present invention. 
Further in accordance with the present invention are provided methods of 
flocculating suspended material in aqueous dispersions, particularly 
aqueous dispersions having a relatively low cationic demand, by treating 
the dispersion with an effective amount of a dilute aqueous solution 
comprising the ampholytic polymers of the present invention. 
DETAILED DESCRIPTION OF THE INVENTION 
The present invention, in a broad sense, is directed to ampholytic polymers 
comprising repeating units of quaternary dialkylaminomethyl 
(alk)acrylamide and at least one anionic comonomer such that the 
ampholytic polymer has a standard viscosity of at least about 2.1 cps when 
measured at 0.1 percent concentration in a 1 molar sodium chloride 
solution. More specifically, the present invention provides copolymers of 
quaternary dialkylaminomethyl (alk)acrylamide and about 1 to about 15 mole 
percent, based on the moles in the total polymer, of ethylenically 
unsaturated anionic comonomer. The resulting copolymers have a standard 
viscosity of at least about 2.1 cps when measured at 0.1 percent 
concentration in a 1 molar sodium chloride solution. Suitable 
ethylenically unsaturated anionic comonomers are those that, when 
incorporated into the ampholytic polymer in amounts ranging from about 1 
to about 15 mole percent, based on the moles in the total polymer (total 
polymer), and heat treated in accordance with the instant invention, 
provide the ampholytic polymer with a standard viscosity of at least about 
2.1 cps when measured at 0.1 percent concentration in a 1 molar sodium 
chloride solution. The ethylenically unsaturated anionic comonomers may be 
used to make the ampholytic polymers by converting them into their salt. 
Preferred anionic comonomers include acrylic acid; 2-acrylamido-2-alkyl 
sulfonic acid; methacrylic acid, fumaric acid, crotonic acid; maleic acid; 
styrene sulfonic acid; their salts and mixtures thereof and the like. 
Acrylic acid and its acrylate salts are most preferred. If desired, more 
than one type of anionic monomer may be incorporated into the backbone of 
the ampholytic polymer. The amount of anionic comonomer present in the 
ampholytic polymer is critical insomuch as it should not range above about 
15 mole percent, based on total polymer. Preferably the anionic content 
may range up to about 12 mole percent, more preferably up to about 10 mole 
percent. The lower end of the effective amount of anionic comonomer is not 
critical and, while amounts less than 1 mole percent may be used, 
generally at least about 1 mole percent, preferably at least about 2 mole 
percent and more preferably at least about 5 mole percent anionic 
comonomer, based on total polymer, should be present in the ampholytic 
polymer. It is optimally preferred to have about 5 to about 12 mole 
percent anionic comonomer in the ampholytic polymer and more preferably 
about 5 to about 10 mole percent, most preferably 10 mole percent, anionic 
comonomer, based on total polymer. 
While the ampholytic polymers of the present invention are generally made 
by copolymerizing, in a microemulsion, (alk)acrylamide with the 
ethylenically unsaturated anionic comonomer or mixture of comonomers, it 
is alternatively possible to prepare an ampholytic polymer of the present 
invention by hydrolyzing an (alk)acrylamide polymer in a microemulsion and 
then functionalizing by Mannich reaction and quaternization followed by 
heat treating according to knowledge within the art and through routine 
experimentation. 
The (alk)acrylamide units in the polymers of the present invention may be 
acrylamide, methacrylamide or ethacrylamide, though acrylamide is 
preferred. 
Optionally, the backbones of the ampholytic polymers may comprise, in 
addition to (alk)acrylamide and anionic comonomers, cationic or non-ionic, 
ethylenically unsaturated comonomers. Preferably, such cationic and 
non-ionic comonomers are water-soluble. Generally, up to about 90 mole 
percent cationic comonomer may be added or up to about 90 mole percent 
nonionic comonomer may be added, provided the minimum standard viscosity 
of 2.1 cps is obtained. 
Useful cationic comonomers include diallyl dialkylammonium chlorides, 
N,N-dialkylaminoalkyl (meth)-acrylates, quaternary 
N,N-dialkylaminoalkyl(meth)acrylates, N,N-dialkylaminoalkyl 
(meth)acrylamides, quaternary N,N-dialkylaminoalkyl (meth)acrylamides, 
their salts and mixtures thereof. Suitable nonionic comonomers generally 
comprise N-vinyl pyrrolidone, N,N-dialkyl(alk)acrylamides, 
hydroxyalkyl(meth)acrylates; formamide, and the like. Small quantities, 
i.e., up to about 10% by weight of other copolymerizable comonomers, such 
as methyl acrylate; methyl methacrylate; acrylonitrile, vinyl acetate, 
styrene, etc. may also be used, 
The molecular weight of the polymers of the present invention is not 
critical and may vary over a wide range from about 2 million to about 75 
million. Preferred polymers have a weight average molecular weight in the 
range of about 10 to 50 million. 
The ampholytic polymers of the present invention are generally prepared in 
a microemulsion by polymerization, Mannich reaction with formaldehyde and 
a secondary amine, quaternization with an alkylating agent and heat 
treating. The ampholytic polymers may be recovered from the microemulsion 
using methods known in the art. The resulting ampholytic polymers may be 
added to water to form dilute aqueous solutions and used to flocculate 
suspended solids in various aqueous dispersions. Alternatively, the 
ampholytic polymers may be employed in their microemulsion form by adding 
the microemulsion to the medium to be treated or typically by inverting 
them into water, optionally using a breaker surfactant. 
Polymerization in inverse microemulsions is known to those skilled in this 
art. Conventional microemulsion polymerization techniques as disclosed in, 
for example, U.S. Pat. Nos. 5,037,881; 5,037,863; 4,521,317; 4,681,912 and 
GB 2162492A., the disclosures of each of which are incorporated herein by 
reference, may be employed to prepare the polymers of the present 
invention. 
Generally, microemulsion polymerization is effected by (i) preparing a 
monomer containing microemulsion by mixing an aqueous solution of monomers 
with a hydrocarbon liquid containing an appropriate amount of surfactant 
or surfactant mixture to form an inverse (water-in-oil) microemulsion 
comprising small droplets dispersed in a continuous oil phase and (ii) 
subjecting the monomer-containing microemulsion to polymerization 
conditions. It is not necessary to apply energy, e.g., apply shear, to the 
emulsion to obtain the small droplets as they form spontaneously, although 
a microemulsion prepared as disclosed herein, which is also subject to 
shear is not beyond the scope of this invention. 
In the preferred process for preparing the ampholytic polymers of the 
present invention an aqueous solution of (alk)acrylamide and one or more 
anionic comonomers is admixed with a liquid hydrocarbon and a suitable 
surfactant or surfactant mixture. The resulting admixture forms an inverse 
(water-in-oil) microemulsion which is then subjected to polymerization 
conditions, reacted with an effective amount of formaldehyde and a 
secondary amine or a complex thereof to provide an amidoaminoalkyl group 
which is then quaternized. The quaternized polymer is heat treated to 
produce a polymer having a standard viscosity of at least 2.1 cps. The 
polymers may be used directly in microemulsion form or recovered from the 
microemulsion. 
Optionally, additional ethylenically unsaturated cationic or nonionic 
comonomers as described above are admixed with the above aqueous and 
hydrocarbon or oil liquids, preferably with the aqueous phase before it is 
admixed with the oil phase. Chain transfer agents such as isopropanol, may 
also be added, and are, in fact, preferred. Other conventional additives 
such as chelating agents to remove polymerization inhibitors, difunctional 
monomers such as methylene bis(acrylamide), pH adjustors, initiators and 
the like may also be added, preferably to the aqueous phase. 
Because some anionic comonomers used for the present invention are not very 
water-soluble, the anionic comonomers may be neutralized with base such as 
sodium hydroxide, ammonium hydroxide, or the like to obtain the more 
soluble salt. This neutralization is carried out by adjusting the pH of 
the aqueous phase to about 7, preferably prior to combining the oil and 
aqueous phases. Neutralization is less preferred than using the less 
soluble anionic comonomer because neutralization requires the pH of the 
(alk)acrylamide/anionic salt copolymeric microemulsion to be later 
readjusted to acid conditions, i.e., a pH in the range of about 2.5 to 
about 4.5, preferably about a pH of 3.5, prior to running the Mannich 
reaction. It is therefore preferred that the anionic comonomers be used in 
their less soluble acid form in preparing the polymers of the present 
invention. Indeed, it is surprising, given the low water-solubility of the 
anionic comonomers, that the anionic comonomers may be used to prepare the 
ampholytic polymers of the present invention without converting them to 
their more soluble salt form. 
A microemulsion, for purposes of this invention, is generally defined as a 
thermodynamically stable composition comprising two liquids or phases 
which are insoluble in each other along with a surfactant or surfactant 
mixture. Polymeric inverse microemulsions which contain a continuous oil 
phase and a polymer-containing discontinuous phase (aqueous droplets) are 
prepared from thermodynamically stable monomer microemulsions. Inverse 
microemulsions have a narrow droplet size distribution and are usually, 
but not always, optically transparent. The discontinuous 
polymer-containing phase of microemulsions form droplets or micelles, 
which are usually aqueous and usually have an average droplet diameter 
which is less than about 3000 .ANG., preferably less than about 2000 .ANG. 
and most preferably less than about 1000 .ANG.. Some microemulsions may 
have an average droplet diameter as large as about 3500 .ANG.. 
In order to obtain an inverse microemulsion, specific conditions with 
respect to surfactant hydrophilic-lipophylic balance (HLB), surfactant 
concentration or surfactant mixture, temperature, nature of the organic 
phase and composition of the aqueous phase must be used. 
The selection of the organic phase has a substantial effect on the minimum 
surfactant concentration necessary to obtain the inverse microemulsion and 
may consist of a hydrocarbon or hydrocarbon mixture. Isoparaffinic 
hydrocarbons or mixtures thereof are the most desirable in order to obtain 
inexpensive formulations. Typically, the organic phase will comprise 
mineral oil, toluene, fuel oil, kerosene, vegetale oils, odorless mineral 
spirits, mixtures of any of the foregoing and the like. 
The ratio by weight of the amounts of aqueous phase (water and polymer) and 
hydrocarbon phase is chosen as high as possible, so as to obtain, after 
polymerization, a microemulsion of high polymer content. As a practical 
matter, this ratio may range, for example, from abut 0.5 to about 3:1 
respectively, and usually approximates 1:1. 
The one or more surfactants are selected in order to obtain an HLB value 
ranging from about 7 to 13. This HLB range is an important factor in 
forming the inverse microemulsion. Preferably, the surfactant or 
surfactant mixture used has an HLB ranging from about 8 to about 10. When 
using the anionic comonomers in their acid form, the preferred HLB tends 
to be lower than when the anionic comonomer is used in its salt form. In 
addition to the appropriate HLB value, the concentration of surfactant 
should be optimized, i.e., sufficient to form an inverse microemulsion. 
Too low a concentration of surfactant leads to the formation of inverse 
macroemulsions which are not thermodynamically stable and too high a 
concentration results in increased costs and does not impart any 
significant benefit. Preferably, surfactants are used in amounts ranging 
from 10% to 20%, based on aqueous phase, although this range may be 
altered depending on the surfactant and HLB used. Typical surfactants 
useful in the practice of this invention may be anionic, cationic or 
nonionic. Preferred surfactants include polyoxyethylenesorbitol 
hexaoleate, sorbitan sesquidenate, sorbitan monooleate, polyoxyethylene 
(20) sorbitan monooleate, sodium dioctylsulfosuccinate, 
oleamidopropyldimethyl amine and sodium isosteary-1-2lactate. The most 
preferred suffactants are sorbitan sesquidenate and 
polyoxyethylenesorbitol hexaoleate. 
Polymerization of the microemulsion may be carried out in any manner known 
to those skilled in the art. Initiation may be effected with a variety of 
thermal and redox free radical initiators, including peroxides, e.g. 
t-butyl peroxide; azo compounds, e.g. azobisisobutyronitrile; inorganic 
compounds, such as potassium persulfate and redox couples, such as ferrous 
ammonium sulfate/ammonium persulfate, or sodium bromate/sulfur dioxide. 
Initiator addition may be effected any time prior to the actual 
polymerization per se. When conducting polymerization by free radical 
initiation it is important to remove oxygen by methods known in the art 
such as sparging with nitrogen. Polymerization may also be effected by 
photochemical irradiation processes, such as ultraviolet irradiation or by 
ionizing irradiation from a cobalt 60 source. 
The amino methylation or Mannich reaction is preferably performed after 
inverse microemulsion polymerization by adding formaldehyde and secondary 
amine to the polymer to form the tertiary aminomethyl substituent on the 
(alk)acrylamide portion of the polymer backbone. While any amount of 
tertiary aminomethyl groups may be substituted on the (alk)acrylamide 
portion of the polymer backbone, preferably, at least about 20 mole 
percent, more preferably at least 55 mole tertiary aminomethyl groups 
should be substituted on the polymer backbone. An amount sufficient to 
retain net positive charge on the polymer is preferably employed. 
It is also possible to perform the Mannich reaction at various other stages 
in relation to inverse microemulsion polymerization. For example, one may 
react the (alk)acrylamide monomer and anionic comonomer with the 
formaldehyde and secondary amine prior to the inverse microemulsion 
formation and before polymerization of the monomers. Also contemplated, is 
adding the formaldehyde and secondary amine to the aqueous solution prior 
to polymerizing and then simultaneously polymerizing the (alk)acrylamide 
monomer and anionic comonomer and carrying out the Mannich reaction. 
However, these alternative procedures are less preferred because 
undesirable side reactions may occur. 
Aliphatic aldehyes, preferably formaldehydes useful in the practice of this 
invention are selected from formaldehyde, paraformaldehyde, trioxane or 
aqueous formalin, and the like. 
Useful secondary amines are selected from dimethylamine, methylethylamine, 
diethylamine, amylmethylamine, dibutylamine, dibenzylamine, piperidine, 
morpholine, ethanolmethylamine, diethanolamine, dimethylethondamine or 
mixtures thereof. 
Especially preferred is a process wherein the formaldehyde comprises 
paraformaldehyde and the secondary amine comprises dimethylamine. It is 
also preferred to employ a formaldehyde-secondary amine complex such as 
N,N-dimethylaminomethyl alcohol. The ratio of formaldehyde to amine is not 
critical and can range from about 10:1 to 1:10, by mole, respectively. It 
is generally preferred, however, to use a molar ratio as close to 1:1 as 
practical. A sufficient quantity of the amine and formaldehyde, or complex 
thereof, is required to amino methylate and impart tertiary aminomethyl 
groups to the (alk)acrylamide polymer, preferably to impart at least 20 
mole percent of tertiary aminoalkyl groups, more preferably at least 55 
mole percent of tertiary aminomethyl groups, based on the total polymer. 
The ampholytic polymers produced by the procedures of the present invention 
are quaternized by methods known in the art, such as by reacting the 
Mannich polymers with such quaternizing agents as methyl chloride, methyl 
bromide, methyliodide, dimethyl sulfate, benzyl chloride and the like 
under known conditions. 
Assuming the Mannich reaction runs to completion, up to about 98 mole 
percent, more preferably as much as about 90 mole percent quaternized 
amino methyl (alk)acrylamide may be present in the ampholytic polymers. It 
has been observed that the Mannich reaction may not run to completion, 
oftentimes leaving anywhere from 0 to about 30 mole percent of unreacted 
(alk)acrylamide, based on total polymer, remaining in the polymer. The 
Mannich reaction can also intentionally be partially run to any extent, 
preferably leaving up to as much as 70 mole percent unreacted 
(alk)acrylamide based on total polymer, more preferably 35 mole percent 
unreacted (alk)acrylamide in the polymer backbone. Quaternization 
reactions tend to run to completion resulting in fully quaternizing 
substantially all tertiary aminomethyl groups on the (alk)acrylamide 
portion of the polymer backbone. By only partially running the Mannich 
reaction and then fully quaternizing, the ampholytic polymers of the 
present invention may be prepared having as low as 20 mole percent, more 
preferably as low as 55 mole percent quaternized amino methylated 
(alk)acrylamide, based on total polymer. 
After quaternizing the dialkylaminomethyl (alk)acrylamide/anionic 
copolymers or ampholytic polymers, the ampholytic polymers are then heat 
treated which raises the polymer standard viscosity to at least about 2.1 
cps. and renders the ampholytic polymers stable and effective as 
flocculants. Heat treatment is accomplished by adding to the untreated 
ampholytic polymer under agitation an effective amount of acid, aldehyde 
scavenger compound and water sufficient to provide a polymer with a 
standard viscosity of at least about 2.1 cps when measured at 0.1 percent 
concentration in an a 1 molar sodium chloride solution. Acids which may be 
employed for use herein are generally those acids, preferably organic 
carboxylic acids, which when used along with aldehyde scavenger to heat 
treat the ampholytic polymers described herein produce a polymer with a 
standard viscosity of at least about 2.1 cps when measured at 0.1 percent 
concentration in an a 1 molar sodium chloride solution. The acids used 
should be water soluble and inert with respect to the ingredients that are 
present in the microemulsion system, i.e. emulsifier, polymer oil and 
other generally added ingredients. The appropriate acid depends on the 
amount of anionic comonomer incorporated into the ampholytic polymer. For 
example, for ampholytic polymers containing about 10 mole percent anionic 
comonomer such as acrylic acid, suitable acids may generally include those 
acids having a pK.sub.a of from about 4.1 to about 5.2 and preferably from 
about 4.4 to about 4.9. For these ampholytic polymers comprising 10 mole 
percent anionic comonomer, acetic acid having a pK.sub.a of about 4.8 is 
most preferred for heat treating. While citric acid having a pK.sub.a of 
about 3.1 may not be as suitable for heat treating an ampholytic polymer 
containing 10 mole percent anionic comonomer, citric acid may be suitable 
for heat treating an ampholytic polymer containing less than 10 mole 
percent anionic comonomer. Moreover, while formic acid and lactic acid 
having pKa's of 3.8 and 3.9 respectively are less preferred for heat 
treating an ampholytic polymer comprising 10 mole percent anionic 
comonomer, these acids would be suitable for heat treating ampholytic 
polymers containing less than 10 mole percent anionic comonomer. Generally 
however, suitable acids may include those having a pK.sub.a of from about 
3 to about 6, preferably from about 4 to about 5 and most preferably those 
acids having a pKa around about 4.8. Examples of acids which may be used 
in the heat treating process described herein include citric, formic, 
lactic, and citraconic. Acetic acid is preferred. The quantity of acid 
used also depends on the amount of anionic comonomer present in the 
ampholytic polymer. The effective amounts of acid are amounts which will 
produce according to the invention polymers having a standard viscosity of 
at least 2.1 cps. As a general rule, as the anionic content in the 
ampholytic polymer increases, increasing amounts of acid are needed to 
provide a standard viscosity of at least about 2.1 cps when measured at 
0.1 percent concentration in a 1 molar sodium chloride solution. 
Generally, amounts ranging from about 15 to about 60 mole percent, based 
on the total number of moles of polymer present in the microemulsion, 
preferably about 25 to about 50 mole percent and more preferably about 33 
to about 40 mole percent may be used in the heat treating step, though 
these amounts may vary depending on the anionic content in the ampholytic 
polymer. 
The aldehyde scavengers useful herein are those water-soluble compounds 
which have the capability to react or complex with aldehyde. The quantity 
of aldehyde scavenger or effective amount used in the present invention is 
an amount which will provide, after heat treating, a polymer having a 
standard viscosity of at least 2.1 cps. This amount preferably ranges from 
about 0.01 to about 30 mole percent, preferably ranging from about 0.6 to 
about 15 mole percent, based on the moles of polymer in the microemulsion. 
Aldehyde scavengers include those known in the art such as those compounds 
having the capability of reacting with formaldehyde, urea, substituted 
ureas such as ethylene urea, guanidine salts, dicyanidiamide, sulfurous 
acid and any of its alkali metal salts such as sodium bisulfite, sodium 
metabisulfite and the like, as well as phosphorous acid and mixtures of 
any of the foregoing. 
The effective amount of water preferably used in heat treating the 
ampholytic polymers is preferably selected such that the polymer content 
in the aqueous phase of the resulting ampholytic polymeric microemulsion 
contains from about 10 to about 45 weight percent polymer, based on the 
weight of the total aqueous phase and preferably from about 15 to 40 
weight percent polymer, same basis. Although the acid, formaldehyde 
scavenger and water may be separately added to the ampholytic polymer in 
any order, it is preferred to pre-mix the acid, formaldehyde scavenger and 
water and gradually add the stabilizing pre-mix to the polymer, with 
stirring, preferably for a period of over 30 minutes, more preferably over 
1 hour. The resulting treated polymer, in microemulsion form, is then 
heated to a temperature preferably from about 40.degree. to about 
80.degree. C. for from about 3 to about 20 hours. More preferably, the 
treated polymer is heated to a temperature of from about 50.degree. to 
about 70.degree. C. for anywhere from about 5 to about 20 hours. The 
heating step can be carded out immediately after addition of the acid, 
scavenger and/or water, though it is also possible to delay the heating up 
to the desired time of use of the microemulsion or polymer as a 
flocculant. 
After the formaldehyde scavenger, water and the acid, preferably in the 
form of an aqueous pre-mix as described above, are added to the 
microemulsion and the polymeric microemulsion is heated the resulting 
ampholytic polymer has a standard viscosity of at least 2.1 cps, 
preferably at least 2.7 mPa.s, and more preferably at least 2.9 mPa.s when 
measured at 0.1 percent concentration in a 1 molar sodium chloride 
solution. 
Heat treating the ampholytic polymer is critical to obtaining the minimum 
standard viscosity necessary for effective flocculation performance as 
shown in Table 4 which lists the standard viscosity values of various 
ampholytic polymers containing 2, 5, 7.5, 10, 15, 20 and 50 mole percent 
anionic comonomer (acrylic acid), before and after heat treating. 
The ampholytic polymers of the instant invention may be recovered from the 
microemulsion, after heat treating, using methods known in the art such as 
filtration, stripping or by adding the microemulsion to an appropriate 
non-solvent such as acetone, precipitating the polymer and filtering the 
solids. 
The ampholytic polymers and polymeric microemulsions can be used for 
flocculating suspended solids in various aqueous dispersions, i.e. systems 
comprising solids and other materials suspended in aqueous medium, and are 
especially effective in sludges, aqueous dispersions which flocculate more 
effectively with cationic polymeric flocculants having a lower cationic 
charge. Such aqueous dispersions include but are not limited to many paper 
deinking process waters and deinking sludge resulting from the processing 
of recycled paper, many biologically treated suspensions including sewage 
sludge and other municipal or industrial sludges, and cellulosic 
dispersions found in paper production, e.g., paper waste. The polymers and 
polymeric microemulsions described herein are particularly effective in 
sludges, preferably paper sludges and sewage sludges having total solids 
level of at least 2% by weight, preferably of at least 4%, by weight, and 
most preferably at least 5% by weight. 
The methods of flocculating suspended material, including suspended solids, 
in aqueous dispersions are preferably employed in known applications to 
facilitate the clarification of aqueous dispersions or the dewatering of 
sludge-containing aqueous dispersions. The ampholytic polymers or 
microemulsions may be combined with the dispersion to be flocculated by 
conventional methods of blending, including those applying shear. To 
clarify deinking process waters, the floc may be allowed to settle and 
then is separated from the aqueous portion by conventional means, such as 
using dissolved air flotation clarifiers. Dewatering sludge may be 
accomplished by seperating the flocculated aqueous medium through 
centrifugation, use of screw press, belt press, a clarifier, pressure 
filtration or gravity filtration. 
The ampholytic polymers and ampholytic polymeric microemulsions of the 
present invention are preferably employed as flocculants prepared in the 
form of dilute aqueous solutions, though they may also be employed as 
microemulsions. Dilute aqueous solutions can be prepared by inverting the 
microemulsion into water, optionally in the presence of a breaker 
surfactant, or by recovering the polymer from the microemulsion, such as 
by stripping or by adding the microemulsion to a non-solvent which 
precipitates the polymer, e.g. isopropanol or acetone, filtering off the 
resultant solids, drying and redispersing the dry polymer in water. When a 
breaker surfactant is added for inversion, it should be in an amount 
sufficient to enable the inverted polymer to reach its maximum standard 
viscosity. The ampholytic polymeric microemulsions of the present 
invention may also be stripped to increase the percentage of polymer 
solids. 
The effective amount of dilute aqueous solution or microemulsion used for 
adequate floc stability can be found by routine experimentation for any 
particular flocculation process, polymer type and aqueous dispersion 
medium, since the dosage may vary depending on the flocculation process, 
polymer type, polymer charge and aqueous medium being treated. Generally, 
though, the effective amount of dilute aqueous solution or microemulsion 
used for flocculating suspended solids from aqueous dispersions, 
preferably sludges, includes amounts which deliver from about 0.2 to about 
100 pounds polymer, per ton of suspended solids in the aqueous dispersion, 
preferably about 0.5 to about 10 pounds polymer, per ton of suspended 
solids in the medium being treated. For flocculating suspended materials 
in deinking process waters resulting from the processing of recycled 
paper, generally the effective amount of dilute aqueous solution or 
microemulsion is an amount which provides anywhere from about 5 to about 
1000 ppm, based on the dispersion being treated, preferably about 8 to 
about 40 ppm polymer, based on the amount of process water being treated. 
DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The following examples illustrate the present invention. They are not to be 
construed to limit the claims in any manner whatsoever. 
Standard viscosity (SV) is measured by adding 10.8 parts of a 10.87% 
aqueous solution of sodium chloride to 10.0 parts of a 0.2% aqueous 
polymer solution adjusted to pH 7. The resultant mixture, which is 0.1% 
polymer concentration is stirred for five minutes with the viscosity 
determined at 25.degree..+-.0.1.degree. C. using a Brookfield viscometer 
Model DV II with UL adapter at 60 rpm. 
Percentage Total Suspended Solids Removal (% TSS Removal) is determined as 
follows: a 10 mL sample of raw process water is filtered through a 
pre-weighed 0.45 micron glass fiber membrane. The membrane is oven added 
overnight, stored in a desiccator until room temperature, and the captured 
solids are weighed. Total Suspended Solids (TSS) is then determined as: 
EQU Raw water TSS (ppm)={(A-B).times.1000}/10 mL 
where: 
A=weight of filter+sample solids in mg 
B=weight of filter in mg 
The same procedure is then applied to clarified process water samples. % 
TSS Removal is then calculated as: 
EQU % TSS Removal={(Raw water TSS-Clarified water TSS).times.100)}/Raw water TS 
S 
Turbidity is measured using a Hach Model 2100P turbidimeter and values are 
recorded in nephelometric turbidity units (NTU).

EXAMPLE 1 
The preparation of a polymeric (sodium acrylate-co-acrylamide) containing 
10 mole % sodium acrylate, quaternary mannich microemulsion and testing 
results demonstrating flocculant performance is described below. 
Microemulsion Preparation 
117.4 parts of an aqueous solution containing 50.9 parts acrylamide (AMD), 
5.7 parts glacial acrylic acid (AA), and 0.11 parts disodium salt of 
ethylenediaminetetraacetic acid (Na.sub.2 EDTA) is neutralized with a 50% 
solution of sodium hydroxide. The aqueous solution is then added to an 
organic solution containing 102.8 parts of an isoparaffinic solvent (IPS) 
having a b.p. of 207.degree.-254.degree. C., 17.6 parts of 
polyoxyethylenesorbitol hexaoleate (PESH), and 5.9 parts of sorbitan 
sesquioleate (SS). This is subsequently sparged with nitrogen for 30 
minutes at a flow rate of 500 ml/min. 
The nitrogen sparge is then lowered to 200 ml/min. and 0.23 parts 
isopropanol (IPA) and an aqueous solution containing 0.0085 parts sodium 
bromate (NaBrO.sub.3)which is presparged are added. Sparging is continued 
for approximately five minutes when polymerization is initiated by the 
introduction of 0.1% SO.sub.2 in nitrogen at a flow rate of 30-85 ml/min. 
The result is a clear and stable (sodium acrylate-co-acrylamide)(SA/AMD) 
polymeric microemulsion (SV=3.7 cps). 
DMAM Preparation 
N,N-dimethylaminomethanol (DMAM) is prepared by slowly adding 21.2 parts of 
92.5% paraformaldehyde to an appropriate flask containing 48.6 parts of a 
60% aqueous solution of dimethylamine and 22.1 parts of deionized water, 
keeping the exotherm below 25.degree. C. Upon dissolution of the 
paraformaldehyde, 1.51 parts of methanol, 2.75 parts of dicyandiamide, and 
3.86 parts of 97.9% sodium metabisulfite is added for stabilization. After 
stirring for one hour, any insolubles are allowed to settle and the clear 
solution containing 49 parts of DMAM solids is decanted. 
Mannich SA/AMD Polymeric Microemulsion Preparation 
100 parts of the above microemulsion are placed in a suitable reactor. 3.24 
parts of glacial acetic acid is then added over 6 hours with vigorous 
stirring. The microemulsion is then diluted to 18.8% solids with the 
isoparaffinic solvent used above. 43.8 parts of the above DMAM solution is 
added to the reactor at a rate of 0.53 ml/min with ample stirring. 
Subsequent to the addition, the reaction is heated to 35.degree. C. and 
held for 4.5 hours. The Mannich product is stored under refrigeration and 
has an SV of 1.7 cps. 
Quaternary SA/AMD Mannich Polymeric Microemulsion Preparation 
3.26 parts of alkylaryl polyethylene glycol ether (AAPEG) is added to 100 
parts of the Mannich product at the rate of 0.11 ml/min. This mixture is 
then transferred to a Parr Series 4560 mini-reactor and stirred. The 
reactor is evacuated to 100 torr and heated to 30.degree. C. 10.56 parts 
of methyl chloride gas is delivered at 30 psig. Upon completion of the 
methyl chloride charge, the reactor is heated to 35.degree. C. for 16 
hours. The reactor is then slowly evacuated to 100 torr and maintained for 
30 minutes to strip excess methyl chloride. The quaternary polyampholytic 
microemulsion product is clear and stable with an SV of 1.4 cps. 
Heat Treatment of Quaternary Mannich Polymeric SA/AMD Microemulsion 
25.0 parts of the above polyampholytic microemulsion is charged to an 
appropriate flask and stirred vigorously. 7.1 parts of an aqueous solution 
containing 0.87 parts of acetic acid (glacial, aldehyde free) and 0.30 
parts of urea is added to the flask at the rate of 0.12 ml/min. The 
microemulsion is then transferred to an oven pre-heated to 60.degree. C. 
for 16 hours. The resultant product is a polyampholytic microemulsion with 
an SV of 2.8 cps. 
Performance Testing 
Paper Recycling Sludge: 
The efficiency of dewatering a paper recycling sludge having sludge solids 
of 2.2% (by weight) is determined as follows: 200 parts of sludge is 
weighed into a square beaker. Aqueous solutions of heat treated 
polyampholytic flocculants are prepared by adding the microemulsion to 
water so that the polymer concentration is 0.2 weight percent and then 
adjusting the pH to 7 with sodium hydroxide. Various doses of the polymer 
solutions are added to the sludge samples with water being added to the 
polymer solution to yield an equivalent addition with each dose. The 
mixture is then agitated for 5 seconds and poured through a Buchner funnel 
containing a filter cloth. The free drainage is determined by measuring 
the volume of filtrate collected in 10 and 20 seconds. A sample of the 
filtrate is then collected for filtrate turbidity measurement in 
nephelometric turbidity units (NTU). The results are set forth in Table 1 
below. 
TABLE 1 
______________________________________ 
10 sec 20 sec 
Polyampholyte Free Free Turbidity 
of Example # 
Dose (ml) 
Drainage (ml) 
Drainage (ml) 
(NTU) 
______________________________________ 
1 1 25 40 836 
2 130 170 119 
4 110 150 99 
6 85 126 160 
______________________________________ 
Paper Recycling Process Water: 
The efficiency of clarifying process water from deinking recycled paper is 
determined as follows: 250 ml of process water having a total solids of 
0.28% (by weight) is poured into a 500 ml graduated cylinder. Aqueous 
solutions of heat treated polyampholytic flocculants are prepared by 
adding the microemulsion to water so that the polymer concentration is 0.2 
weight percent. Various doses of the polymer solutions are added to the 
substrate followed by inversion until optimum flocculation is seen. The 
floccules are 
then floated using pressurized water containing dissolved air. The results 
are set forth in Table 2 below. 
TABLE 2 
______________________________________ 
Polyampholyte of 
Example # Dose (ml) % TSS Removal 
Turbidity (NTU) 
______________________________________ 
1 1 97.8 225 
2 99.5 55 
3 98.6 41 
______________________________________ 
EXAMPLES 2-7 
In Examples 2-7 polymeric SA/AMD microemulsions are prepared using the 
procedure for example 1. The formulation amounts, in parts, are provided 
in Table 3. 
TABLE 3 
______________________________________ 
Example # 
2 3 4 5 6 7 
______________________________________ 
Organic 
Solution 
IPS 102.8 102.8 102.8 102.8 102.8 102.8 
PESH 16.6 17.0 17.3 18.2 18.8 21.0 
SS 6.9 6.5 6.2 5.3 4.7 2.5 
Aqueous 
Solution 
AMD 55.4 53.7 52.3 48.0 45.2 28.3 
AA 1.1 2.8 4.2 8.5 11.3 28.3 
Deionized 
67.0 67.0 67.0 66.9 66.9 66.8 
Water 
IPA 0.11 0.11 0.11 0.23 0.23 0.34 
Na.sub.2 EDTA 
0.11 0.11 0.11 0.11 0.11 0.11 
NaBrO.sub.3 
0.0085 0.0085 0.0085 
0.0085 
0.0085 
0.0085 
% Anionic* 
2 5 7.5 15 20 50 
SV (cps) 
3.3 3.5 3.8 4.2 4.4 4.9 
______________________________________ 
mole percent, based on the total polymer 
EXAMPLES 8-13 
Examples 8-13 describe the preparation of various charged polyampholytic 
microemulsions from the SA/AMD polymeric backbone microemulsions described 
in examples 2-7. Table 4 provides the SV for the polyampholytic 
microemulsions before and after heat treating. 
EXAMPLE 8 
100 parts of microemulsion from example 2 is functionalized by Mannich 
reaction and quaternization and heat treated using the procedure from 
example 1 with the following exceptions: 1.74 parts acetic acid is added 
to the backbone microemulsion followed by dilution to 18.8% solids using 
IPS and addition of 47.8 parts of DMAM solution, as perepared in example 
1. This Mannich product has an SV of 3.8 cps. The quaternization is then 
carried out by first adding 3.28 parts of AAPEG to 100 parts Mannich 
product then reacting with 11.2 parts methyl chloride (MeCl) gas. This 
quaternary product has an SV of 2.3 cps. Finally, 25 parts of the 
polyampholytic microemulsion is heat treated with 7.1 parts of an aqueous 
solution containing 0.66 parts acetic acid and 0.30 parts urea. The 
resultant polymer has an SV of 2.9 cps. 
Carbon 13 nuclear magnetic reasonance (.sup.13 C nmr) analysis of the 
quaternary product found 2 mole % AA and 74 mole % quaternary amine. 
EXAMPLE 9 
100 parts of microemulsion from example 3 is functionalized by Mannich 
reaction and quaternization and heat treated using the procedure from 
example 1 with the following exceptions: 2.30 parts acetic acid is added 
to the backbone microemulsion followed by dilution to 18.8% solids using 
IPS and addition of 46.2 parts of DMAM solution. This Mannich product has 
an SV of 3.0 cps. The quaternization is then carried out by first adding 
3.28 parts of AAPEG to 100 parts Mannich product then reacting with 11.0 
parts MeCl gas. This quaternary product has an SV of 1.6 cps. Finally, 25 
parts of the polyampholytic microemulsion is heat treated with 7.1 parts 
of an aqueous solution containing 0.66 parts acetic acid and 0.30 parts 
urea. The resultant polymer has an SV of 2.9 cps. 
.sup.13 C nmr analysis of the quaternary product found 5 mole % AA and 64 
mole % quaternary amine. 
EXAMPLE 10 
100 parts of microemulsion from example 4 is functionalized by Mannich 
reaction and quaternization and heat treated using the procedure from 
example 1 with the following exceptions: 2.77 parts acetic acid is added 
to the backbone microemulsion followed by dilution to 18.8% solids using 
IPS and addition of 45.0 parts of DMAM solution. This Mannich product has 
an SV of 2.0 cps. The quaternization is then carried out by first adding 
3.27 parts of AAPEG to 100 parts Mannich product then reacting with 10.78 
parts MeCl gas. This quaternary product has an SV of 1.4 cps. Finally, 25 
parts of the polyampholytic microemulsion is heat treated with 7.1 parts 
of an aqueous solution containing 0.87 parts acetic acid and 0.30 parts 
urea. The resultant polymer has an SV of 2.9 cps. 
.sup.13 C nmr analysis of the quaternary product found about 8 mole % AA 
and 66 mole % quaternary amine. 
EXAMPLE 11 
100 parts of microemulsion from example 5 is functionalized by Mannich 
reaction and quaternization and heat treated using the procedure from 
example 1 with the following exceptions: 4.19 parts acetic acid is added 
to the backbone microemulsion followed by dilution to 18.8% solids using 
IPS and addition of 41.4 parts of DMAM solution. This Mannich product has 
an SV of 1.25 cps. The quaternization is then carried out by first adding 
3.25 parts of AAPEG to 100 parts Mannich product then reacting with 10.1 
parts MeCl gas. This quaternary product has an SV of 1.26 cps. Finally, 25 
parts of the polyampholytic microemulsion is heat treated with 7.1 parts 
of an aqueous solution containing 1.05 parts acetic acid and 0.30 parts 
urea. The resultant polymer has an SV of 2.1 cps. 
.sup.13 C nmr analysis of the quaternary product found 14 mole % AA and 56 
mole % quaternary amine. 
EXAMPLE 12 
100 parts of microemulsion from example 6 is functionalized by Mannich 
reaction and quaternization and heat treated using the procedure from 
example 1 with the following exceptions: 5.13 parts acetic acid is added 
to the backbone microemulsion followed by dilution to 18.8% solids using 
IPS and addition of 38.9 parts of DMAM solution. This Mannich product has 
an SV of 1.3 cps. The quaternization is then carried out by first adding 
3.24 parts of AAPEG to 100 parts Mannich product then reacting with 9.7 
parts MeCl gas. This quaternary product has an SV of 1.2 cps. Finally, 25 
parts of the polyampholytic microemulsion is heat treated with 7.1 parts 
of an aqueous solution containing 1.31 parts acetic acid and 0.30 parts 
urea. The resultant polymer has an SV of 1.7 cps. 
.sup.13 C nmr analysis of the quaternary product found 22 mole % AA and 47 
mole % quaternary amine. 
EXAMPLE 13 
100 parts of microemulsion from example 7 is functionalized by Mannich 
reaction and quaternization and heat treated using the procedure from 
example 1 with the following exceptions: 10.78 parts acetic acid is added 
to the backbone microemulsion followed by dilution to 18.8% solids using 
IPS and addition of 24.3 parts of DMAM solution. This Mannich product has 
an SV of 1.42 cps. The quaternization is then carried out by first adding 
3.17 parts of AAPEG to 100 parts Mannich product then reacting with 6.6 
parts MeCl gas. This quaternary product has an SV of 1.3 cps. Finally, 25 
parts of the polyampholytic microemulsion is heat treated with 7.1 parts 
of an aqueous solution containing 1.31 parts acetic acid and 0.30 parts 
urea. The resultant polymer has an SV of 1.2 cps. 
.sup.13 C nmr analysis of the quaternary product found 47 mole % AA and 11 
mole % quaternary amine. 
TABLE 4 
______________________________________ 
Example 8 9 10 1 11 12 13 
______________________________________ 
Approximate Mole 
2 5 7.5 10 15 20 5 
Percent 
Acrylic Acid 
Monomer 
S.V. Before heat treat- 
2.32 1.64 1.44 
1.42 1.26 1.20 1.26 
ing 
S.V. After heat treat- 
2.9 2.9 2.9 2.8 2.1 1.7 1.2 
ing 
______________________________________ 
EXAMPLE 14 
The performance of the polyampholytic microemulsions of Examples 9 and 10 
as flocculants for dewatering sludge containing 2.0% (by weight) total 
solids is tested as described in Example 1. The results are shown in Table 
5. 
TABLE 5 
______________________________________ 
10 sec 20 sec 
Polyampholyte Free Free Turbidity 
of Example # 
Dose (ml) 
Drainage (ml) 
Drainage (ml) 
(NTU) 
______________________________________ 
9 10 97 124 964 
12 133 159 486 
14 142 168 246 
16 142 166 110 
10 10 102 120 857 
12 122 150 458 
14 140 163 255 
16 152 165 127 
______________________________________ 
EXAMPLES 15-22 
Examples 15-22 describe the use of different heat treatment buffers varying 
in acetic acid content on the polyampholytes from examples 1 and 11. All 
buffers contain the same amount of urea as in example 1. Table 6 below 
describes the acid content and corresponding standard viscosity of various 
ampholytic polymers. 
TABLE 6 
______________________________________ 
Polyampholyte Weight %* 
Example # 
example # Acetic Acid in Buffer 
SV (cps) 
______________________________________ 
15 1 9.2 2.7 
16 1 12.1 2.8 
17 1 4.7 2.6 
18 1 18.4 2.5 
19 11 9.2 1.7 
20 11 12.1 2.0 
21 11 14.7 2.1 
22 11 18.4 1.9 
______________________________________ 
*weight % is based on the toal weight of the buffer containing acid, urea 
and water 
EXAMPLE 23 
The performance of polyampholytic microemulsions from examples 1, 10, and 
11 is determined by sludge dewatering tests as described in example 1. The 
results are shown in Table 7. Sludge solids are 5.2%. 
TABLE 7 
______________________________________ 
10 sec 20 sec 
Free Free Turbidity 
Example # 
Dose (ml) Drainage (ml) 
Drainage (ml) 
(NTU) 
______________________________________ 
1 8 46 70 579 
10 70 92 201 
12 88 114 122 
14 94 118 79 
10 8 50 69 534 
10 67 92 209 
12 86 112 110 
14 94 122 102 
11 8 33 42 &gt;1000 
10 50 74 462 
12 83 107 161 
14 82 108 214 
______________________________________ 
EXAMPLE 24 
The performance of polyampholytic microemulsions from examples 1, 9, and 11 
is determined by sludge dewatering tests as described in example 1 and are 
shown in Table 8. Sludge solids are 2.2%. 
TABLE 8 
______________________________________ 
10 sec 20 sec 
Free Free Turbidity 
Example # 
Dose (ml) Drainage (ml) 
Drainage (ml) 
(NTU) 
______________________________________ 
1 1 25 4 836 
2 130 170 119 
4 110 150 99 
6 85 126 160 
9 1 44 65 896 
2 142 170 114 
4 112 148 82 
6 90 128 129 
11 1 24 37 689 
2 78 118 131 
4 92 142 98 
6 100 145 196 
______________________________________ 
EXAMPLE 25 
The performance of polyampholytic microemulsions from examples 1,8, 9, 10, 
and 11 is determined by sludge dewatering tests as described in example 1 
and are shown in Table 9. Sludge solids are 5.3%. 
TABLE 9 
______________________________________ 
10 sec 20 sec 
Free Free Turbidity 
Example # 
Dose (ml) Drainage (ml) 
Drainage (ml) 
(NTU) 
______________________________________ 
1 4 88 115 715 
6 106 130 438 
8 97 125 405 
8 4 92 120 585 
6 105 126 350 
8 88 117 345 
9 4 85 113 709 
6 103 126 429 
8 104 126 389 
10 4 92 118 642 
6 102 128 413 
8 95 122 362 
11 4 46 65 &gt;1000 
6 88 117 702 
8 100 125 645 
______________________________________ 
EXAMPLE 26 
The performance of polyampholytic microemulsions from examples 1, 9, is 
determined by sludge dewatering tests as described in example 1 and are 
shown in Table 10. Sludge solids are 3.7%. 
TABLE 10 
______________________________________ 
10 sec 20 sec 
Free Free Turbidity 
Example # 
Dose (ml) Drainage (ml) 
Drainage (ml) 
(NTU) 
______________________________________ 
1 18 61 86 917 
22 84 108 443 
26 107 132 223 
9 18 56 78 &gt;1000 
22 74 100 760 
26 107 130 257 
______________________________________ 
EXAMPLE 27 
The performance of polyampholytes from examples 1, and 8-11 in process 
water is shown in Table 11 below. Process water solids is 0.55%. 
TABLE 11 
______________________________________ 
Example # 
Dose (ml) % TSS Removal 
Turbidity (NTU) 
______________________________________ 
1 3 99.1 153 
4 97.8 400 
5 97.8 172 
6 98.4 219 
8 3 98.9 170 
4 99.2 114 
5 98.5 200 
6 97.0 287 
9 3 99.0 159 
4 98.6 123 
5 99.8 203 
6 97.6 298 
10 3 99.5 167 
4 99.2 97 
5 97.7 192 
6 96.9 266 
11 3 93.0 256 
4 99.1 161 
5 98.3 142 
6 98.4 174 
______________________________________ 
EXAMPLE 28 
The performance of polyampholytes from examples 1, 9, and 11 in process 
water is shown in Table 12 below. In this example, a low molecular weight 
cationic coagulant preceded introduction of the polyampholyte. Process 
water solids is 0.99%. 
TABLE 12 
______________________________________ 
Coagulant 
Example # 
Dose (ml) 
Dose (ml) 
% TSS Removal 
Turbidity (NTU) 
______________________________________ 
1 2 3 99.2 133 
2 4 99.4 195 
2 5 99.0 197 
9 2 3 99.6 120 
2 4 99.2 145 
11 2 3 99.0 108 
2 4 99.6 132 
______________________________________ 
EXAMPLE 29 
The performance of polyampholytes from examples 1, 8, 10, and 11 in process 
water is shown in Table 13 below. Process water solids is 0.48%. 
TABLE 13 
______________________________________ 
Example # 
Dose (ml) % TSS Removal 
Turbidity (NTU) 
______________________________________ 
1 1 96.9 269 
2 94.9 384 
8 1 97.1 190 
2 95.9 373 
10 1 96.1 311 
2 96.3 152 
11 1 96.2 346 
2 97.1 185 
______________________________________ 
EXAMPLE 30 
The performance of the polyampholytic microemulsions from example 1 where 
1A is not heat treated and 1B is heat treated is determined by sludge 
dewatering tests as described in example 1 and are shown in Table 14. 
Sludge solids are 6.9%. The SV of 1A which is not heat treated is 1.4 cps 
and the SV of 1B which is heat treated is 2.8 cps. The improved 
performance of 1B demonstrates that flocculation performance improves with 
increasing SV. 
TABLE 14 
______________________________________ 
10 sec 20 sec 
Free Free Turbidity 
Example # 
Dose (ml) Drainage (ml) 
Drainage (ml) 
(NTU) 
______________________________________ 
1A 1.2 10 13 &gt;1000 
1.7 11 12 &gt;1000 
2.3 12 18 &gt;1000 
2.9 13 20 &gt;1000 
1B 1.2 26 36 &gt;1000 
1.7 53 74 398 
2.3 76 96 130 
2.9 80 100 93 
______________________________________ 
EXAMPLE 31 
Example 31 describes the preparation of a polyampholytic microemulsion made 
without neutralization of the anionic acrylic acid. The resultant polymer 
is a poly (acrylic acid-co-acrylamide) AA/AMD containing 10 mole % acrylic 
acid, based on the total moles in the polymer. This microemulsion contains 
lower levels of coagulum formation. 
124.7 parts of an aqueous solution containing 50.9 parts AMD, 5.7 parts AA, 
1.0 parts acetic acid and 0.11 parts Na.sub.2 EDTA is mixed. The aqueous 
solution is added to an organic solution containing 102.8 parts of IPS, 
15.6 parts of PESH, and 7.9 parts of SS. This is then sparged with 
nitrogen and polymerized as in example 1. The result is a clear and stable 
polyampholytic microemulsion with an SV of 3.8 cps. 
100 parts of this backbone is then diluted to 18.8% with IPS. The mannich 
and quaternization reactions are run the same as in example 1. The 
quaternization product gave an SV of 1.3 cps. This product was then heat 
treated as in example 16 to yield a polyampholyte with an SV of 2.6 cps. 
.sup.13 C nmr analysis of the quaternary product found 11 mole % AA and 64 
mole % quaternary amine. 
EXAMPLE 32 
An AA/AMD copolymer microemulsion is prepared using 3.5 mole % AA. This 
microemulsion is prepared using the unneutralized acid as in example 31. 
123.7 parts of an aqueous solution containing 54.5 parts AMD, 2.0 parts AA, 
and 0.11 parts Na.sub.2 EDTA is mixed. The aqueous solution is added to an 
organic solution containing 102.8 parts IPS, 15.6 parts PESH, and 7.9 
parts SS. This is then sparged with nitrogen and polymerized as in example 
1. The dear microemulsion has an SV of 3.3 cps. 
100 parts of this microemulsion is then diluted to 18.8% with IPS and 47.0 
parts of DM/AM solution, as prepared in Example 1, are added. This Mannich 
product has an SV of 3.7 cps. The quaternization is then completed by 
adding 3.28 parts AAPEG to 100 parts Mannich product then reacting with 
11.1 parts MeCl. The quaternary product has an SV of 1.6 cps. Finally, 
this product is heat treated as in example 9 to yield a heat treated 
polyampholyte with SV of 3.0 cps. 
EXAMPLE 33 
A microemulsion with 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) as 
comonomer with AMD is prepared and subsequently functionalized to the heat 
treated polyampholyte. This microemulsion contains 10 mole % AMPS. At this 
level of anionicity, the SV of the quaternary product is significantly 
higher using the AMPS comonomer. This may allow for the use of the 
quaternary product directly in some substrates without need of heat 
treatment. 
123.72 parts of an aqueous solution containing 41.6 parts AMD, 14.9 parts 
AMPS, 1.72 parts acetic acid, and 0.11 parts Na.sub.2 EDTA is prepared. 
The aqueous solution is added to an organic solution identical to that in 
example 31. The clear microemulsion obtained had an SV of 3.1 cps. 
100 parts of this microemulsion is then diluted to 18.8% with IPS and 35.9 
parts DMAM solution are added. This Mannich has an SV of 2.9 cps. The 
quaternization is completed by adding 3.23 parts AAPEG to 100 parts 
Mannich product then reacting with 9.1 parts MeCl yielding a polyampholyte 
SV of 2.2 cps. Heat treatment as in example 1 yields a SV of 2.6 cps. 
EXAMPLE 34 
An AA/AMD copolymer microemulsion is prepared using 12.5 mole % AA. This 
microemulsion is prepared using the unneutralized anionic comonomer as in 
example 31. 
123.7 parts of an aqueous solution containing 49.3 parts AMD, 7.2 parts AA, 
and 0.11 parts Na.sub.2 EDTA is mixed. The aqueous solution is added to an 
organic solution containing 102.8 parts IPS, 15.6 parts PESH, and 7.9 
parts SS. This is then sparged with nitrogen and polymerized as in example 
1. The clear microemulsion has an SV of 2.8 cps. 
100 parts of this microemulsion is then diluted to 18.8% with IPS and 42.6 
parts of DMAM solution, as prepared in Example 1, are added. This Mannich 
polymer has an SV of 1.4 cps. The quaternization is then completed by 
adding 3.26 parts AAPEG to 100 parts Mannich product then reacting with 
10.3 parts MeCl. The quat product has an SV of 1.2 cps. Finally, this 
product is heat treated as in example 10 to yield a heat treated 
polyampholyte with SV of 2.3 cps. 
Transmission Electron Microscopy (TEM) analysis of the heat treated product 
yields a mean aqueous droplet diameter of 890 .ANG.. 
EXAMPLE 35 
A microemulsion with methacrylic acid (MAA) as comonomer with AMD is 
prepared and subsequently functionalized by Mannich reaction and 
quaternization and heat treated to produce a MANAMD polyampholytic 
microemulsion containing 10 mole % MAA, based on the total moles in the 
polymer. 
123.7 parts of an aqueous solution containing 50.3 parts AMD, 6.8 parts 
MAA, and 0.11 parts Na.sub.2 EDTA is prepared. The aqueous solution is 
added to an organic solution identical to that in example 25. The clear 
microemulsion obtained had an SV of 3.1 cps. 
100 parts of this microemulsion is then diluted to 18.8% with IPS and 42.9 
parts DMAM solution as prepared in Example 1 are added. This Mannich 
product has an SV of 1.7 cps. The quaternization is completed by adding 
3.26 parts AAPEG to 100 parts Mannich product then reacting with 10.4 
parts MeCl yielding a polyampholyte with an SV of 1.4 cps. Heat treatment 
as in example 1 yields a SV of 2.1 cps. 
EXAMPLE 36 
Example 36 describes the preparation of a polyampholyte similar to example 
9, but having a lower cationic charge. This polymer contains 5 mole % AA 
based on the total moles in the polymer and is reacted to only 55% 
cationic charge. The AA/AMD backbone polymer is prepared according to 
example 3. The SV of this polymer is 3.4 cps. 
100 parts of this microemulsion is then diluted to 18.8% with IPS and 34.1 
parts DMAM solution as prepared in example 1 are added. This product has 
an SV of 2.4 cps. The quaternization is completed by adding 3.19 parts 
AAPEG to 100 parts Mannich product then reacting with 7.4 parts MeCl. The 
low charged polyampholyte obtained has an SV of 1.4 cps. Heat treatment as 
in example 9 yields a product with SV of 2.9 cps. 
EXAMPLE 37 
Example 37 describes an alternative method for the preparation of poly 
(acrylic acid-co-acrylamide) microemulsion by hydrolyzing an acrylamide 
homopolymer. 123.7 parts of an aqueous phase containing 56.5 parts AMD, 
0.11 parts Na.sub.2 EDTA, and 3.4 parts acetic acid was prepared. This 
solution was mixed with an organic solution containing 102.8 parts IPS, 
16.4 parts PESH, and 7.1 parts SS. After sparging with nitrogen for 30 
minutes 0.1 parts IPA and an aqueous solution containing 0.0085 parts 
NaBrO.sub.3 was added. Polymerization was then initiated as in example 1. 
A few minutes after the maximum temperature of the exotherm was reached, a 
50% aqueous solution containing 6.4 parts NaOH is delivered to the 
reaction. This preparation is then stirred overnight. The product SV=3.7 
cps. .sup.13 C nmr analysis indicates the conversion to 9 mole % AA. 
A polyampholytic microemulsion may be prepared from the hydrolyzed AA/AMD 
microemulsion by Mannich reaction, quaternization and heat treating using 
the procedures described herein or appropriate variations thereof as found 
by routine experimentation. 
EXAMPLES 38-42 
Examples 38-42 describe the effect of different acids used in the heat 
treatment buffer on the SV of an ANAMD ampholytic polymer containing 10 
mole % acrylic acid in microemulsion form. 
25 parts of the quaternary product from example 31 is heat treated as in 
example 1 with 7.1 parts buffer containing 0.30 parts urea and 33 mole % 
of acid based on polymer. The results are set forth in Table 15. From the 
data in Table 15 one skilled in the art may select different acids to use 
for heat treating and preparing an ampholytic polymer. 
TABLE 15 
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Example Acid Acid pK.sub.a 
Product SV (cps) 
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31 Citric 3.1 1.4 
32 Formic 3.8 1.9 
33 Lactic 3.9 2.1 
34 Acetic 4.8 2.5 
35 Citraconic 
6.2 1.3 
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