JP2592803B2 - Stabilization of aqueous systems - Google Patents

Description

Description: BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to an improved method of stabilizing aqueous systems by adding small amounts of low molecular weight and water soluble polymers. More specifically, the present invention provides a method of polymerizing, when polymerized together, an aqueous system, such as phosphate, iron, zinc, in a cooling tower,
At least three monomers that produce terpolymers and interpolymers that exhibit unexpectedly improved settling inhibition and dispersing performance with respect to and other inorganic particulates About doing.

Polymers that have been found to exhibit such improved performance in aqueous systems include certain selected weight percents.
Has units derived from (meth) acrylic acid and salts thereof, acrylamidoalkyl or arylsulfonates, and one or more units derived from vinyl esters, vinyl acetate, and alkyl-substituted acrylamides .

2. Description of the Prior Art In many industrial application and residential areas, water containing relatively high concentrations of inorganic salts is used. These salts are formed by the reaction of a metal cation, such as calcium, magnesium, or barium, with an inorganic anion, such as phosphates, carbonates, and sulfates. These salts are poorly soluble in water and when the concentration of these salts in solution increases,
Alternatively, when the pH or temperature of the water containing these salts increases, these salts tend to precipitate out of solution and crystallize, producing hard deposits or scales on various surfaces. Such scale formation is problematic for heat conducting equipment, boilers, secondary oil recovery wells, and fabrics that have been washed with hard water as described above.

Many cooling water systems made from carbon steel, including industrial cooling towers and heat exchangers, have experienced corrosion problems due to the presence of dissolved oxygen. This corrosion has been attempted to be prevented by adding various inhibitors, for example orthophosphate compounds and / or zinc compounds. However, when phosphate is added, extremely insoluble phosphate,
For example, the formation of calcium phosphate will further occur. Also, the addition of the zinc compound will cause precipitation of insoluble salts, such as zinc hydroxide and zinc phosphate. Other inorganic particulates such as mud, silt, and clay are commonly found in cooling water.
These fine particles tend to adhere to the surface of the device or the like, and unless these fine particles are effectively dispersed, the flow of water and the conduction of heat are limited.

Stabilization of aqueous systems containing scale-forming salts and inorganic particulates involves one or a set of mechanisms. For anti-precipitation, the size of the salt is reduced to a size smaller than the colloidal size by adsorbing an inhibitor on the salt crystals immediately after the nucleation of the salt crystals and interfering with the further growth of the crystals. As late as possible to delay the onset of sedimentation. There is another stabilization mechanism for the dispersion of precipitated salt crystals. It is believed that by adsorbing the inhibitor onto the precipitated crystals, an electrical negative charge is imparted and its repulsion prevents aggregation, sticking, and deposition on the surface. Also, the adsorption of the inhibitor may be due to other dispersed particulates such as mud, silt, and clay, and
Metals such as iron and zinc, and their insoluble salts,
Can be used to stabilize aqueous systems by facilitating their dispersion and subsequent removal from the aqueous system. Another stabilizing mechanism is the ability of the inhibitor to interfere with and distort the crystal structure of the scale, making the scale more easily breakable and dispersible.

Polymers derived from (meth) acrylic acid, and salts thereof, and mixtures of such polymers with other compounds and polymers, such as phosphonic acid, have long been used as suspending agents in aqueous systems. Have been. Also, a copolymer of (meth) acrylic acid and a vinyl ester such as hydroxyethyl methacrylate and hydroxypropyl acrylate, and (meth) acrylic acid and a salt thereof, and acrylamide alkyl or aryl sulfonate or unsubstituted acrylamide And their copolymers have been used for water treatment. Also, acrylic acid, 2
-Acrylamide-2-methylpropanesulfonic acid (AM
PS), and terpolymers made from unsubstituted acrylamide have been proposed to remove rust and nodules from surfaces.

For example, US Pat. No. 3,578,589 describes the use of poly (meth) acrylic acid and copolymers to treat scale in aqueous systems. U.S. Pat.Nos. 3,332,904, 3,692,673, 3,709,815
No. 3,709,816, No. 3,928,196, No. 3,807,36
No. 7 and 3,898,037 describe the use of AMPS-containing polymers. U.S. Patent 3,699,04
No. 8, and 3,890,228 describe the use of phosphonic acids mixed with poly (meth) acrylate for water treatment. U.S. Pat. No. 3,085,916 describes the use of polyacrylamide as a dispersant. GB 2082600 describes acrylic acid, AMPS, acrylamide polymers as scale inhibitors, while W083 / 02607 and W3 / 02608 disclose (meth) acrylic as scale inhibitors. Acid / AMPS copolymers are described. U.S. Pat. Nos. 4,404,111 and 4,342,653 describe AMPS copolymerized with acrylamide and, optionally, acrylic acid. Other interesting publications include U.S. Patent Nos. 3,110,666,
No. 4,457,847, No. 4,029,577, No. 4,209,398, EPC
0,108,842, 4,029,577, 4,209,398, 4,432,884,
4,309,523 and 4,432,879.

In addition, U.S. Pat.Nos. 4,517,098 and 4,530,766, and the references cited therein by the present inventor, disclose a scale inhibitor and a low molecular weight for use in dispersing inorganic particulates in water. The use of (meth) acrylic copolymers is described.

A number of technical areas in the art describing scale prevention, dispersion, and / or stabilization of aqueous systems utilizing polymers derived from (meth) acrylic acid, AMPS, and ethylenically unsaturated monomers. Despite the presence of the literature, conventional materials and their combinations are known for scale-forming salts commonly found in water for cooling towers, and for dispersed inorganic particulates, regardless of the pH and temperature of the aqueous system. It has not been found to be safe and effective at low usage to stabilize aqueous systems, including all of the various types. Certain known substances used for the various applications described above are:
Those who have found that the best stable performance properties of each component can be achieved if they are polymerized at certain selected weight ratios to form a low molecular weight and water soluble terpolymer or intermolymer. No one has been up to now. As used herein, the term "terpolymer (te
"rpolymer" means a polymer formed from three monomers and the term "interpolymer"
"r)" means a polymer formed from at least four monomers. Also, as used herein, the term "copolymer" refers to a polymer formed from only two monomers.

Scale and sediment accumulate in various parts of the boiler circuit due to the presence of impurities in the feed water. These impurities come from a variety of sources, such as, for example, operational malfunctions, leaks, operational errors, and inaccurate impurity analysis. Common types of foreign matter in boiler feedwater are:
These include dissolved solids, gases, alkaline substances, organic matter, and corrosion products from returned condensate. Salts of hardness present in the feed water form their baked sediments and scale when concentrated in the boiler and transferred to the heated surfaces of the equipment. These deposits or scales cause excessive temperature increase and potential rupture of the boiler tube. Typical deposits found in boilers are calcium phosphate, magnesium hydroxide, magnesium silicate and miscellaneous corrosion products such as magnetite (Fe ₃ O ₄ ), hematite (FeOO
H), and iron phosphate, and the like.

To prevent scale and sediment from forming in the boiler, there are two basic internal water treatment methods. These are either the precipitation of impurities as insoluble sludge or the complete prevention of precipitation using chelating agents.

The polymer can act as a chelating agent or sequestering agent, and in some instances, the chelating agent commonly used for that purpose, such as ethylenediaminetetraacetic acid (EDTA) or nitrilotriacetic acid (NTA) ) Are preferred. This is because they have a low tendency to corrode metal parts. The lower propensity of the polymer to corrode is due to less active binding to cations, such as iron, which is due to the stoichiometry of the chelating agent present in the recirculated boiler water. When an amount higher than the amount (theoretical) is present, it means that there will be very little tendency to attack metal parts. The difficulty with this method, even with the polymer, is that the purity of the feedwater must be closely monitored and excessive residual polymer must be prevented from attacking the metal surface.

Another major method of preventing sedimentation growth is to use feedwater hardness
Precipitation as insoluble sludge that can be easily removed by discharging from the boiler. In this method, the polymer is used to disperse insoluble particulates to prevent the particulates from adhering to the hot surfaces of the equipment and to remove sludge in mud drums that are difficult to remove. To prevent hard and dense sediment. The most common precipitant used is phosphate, which removes most of the calcium from the recirculated water as calcium phosphate. Thus, the main difference between the treatment of cooling water and the treatment of boiler water using phosphates is to prevent calcium phosphate from precipitating in the cooling water and to precipitate calcium phosphate in the treatment of boiler water. However, the dispersion is maintained by the polymer.

Common polymers currently used to disperse sludge or chelate hard cations include polyacrylic acid, polymethacrylic acid, copolymers of sulfonate styrene and maleic acid, and acrylic acid and acrylamide. And copolymers thereof.

Accordingly, it is an object of the present invention to provide terpolymers and interpolymers that exhibit improved phosphate stability in aqueous systems over conventional polymer additives.

It is also an object of the present invention to provide terpolymers selected for stabilizing iron and zinc and their salts in aqueous systems.

It is a further object of the present invention to provide certain selected terpolymers and interpolymers in which the inorganic particulates and the thick aqueous slurry are dispersed.

It is a further object of the present invention to provide terpolymers and interpolymers that maintain water solubility and hydrolytic stability at high pH conditions and have improved stabilizing and dispersing performance.

SUMMARY OF THE INVENTION The present inventors have found that in aqueous systems, about 10 to about 84% by weight of units derived from (meth) acrylic acid and salts thereof, 11% by weight or more of units derived from acrylamidoalkyl or aryl sulfonates. Low molecular weight and water soluble terpolymer containing up to 40% by weight and at least about 5 to about 50% by weight of one or more units selected from certain vinyl esters, vinyl acetate, and substituted acrylamides And by the addition of the interpolymer,
It has been unexpectedly found that aqueous systems can be effectively stabilized. These terpolymers and interpolymers, when added to aqueous systems, have improved phosphate stabilization and iron and zinc dispersibility while maintaining water solubility as compared to conventional additives. Show unexpectedly. Also, preferred terpolymers and interpolymers exhibit a high degree of hydrolytic stability under high pH conditions. In addition, (meth) acrylic acid and its salt about 60 ~
Copolymers made from about 90% by weight, and about 40 to about 10% by weight of the substituted acrylamide, and having a weight average molecular weight of about 2500 to about 8000, unexpectedly produce zinc and its salts in aqueous systems Have also been found to be useful as suspending agents.

DETAILED DESCRIPTION OF THE INVENTION The present inventors have determined that at selected weight ratios, selected low molecular weight terpolymers and interpolymers made from at least three selected monomers can be combined with their corresponding conventional homopolymers. Compared to polymers, copolymers, and mixtures thereof, it is planned to incorporate the beneficial anti-scaling and dispersing properties of each of the known monomers and to provide unexpected improvements as stabilizers for aqueous systems It has been found that results can be produced.

Terpolymers and interpolymers that have been found to be useful in the present invention include (a) (meth) acrylic acid and its salts, (b) acrylamidoalkyl or aryl sulfonates, and (c) certain vinyls. At least one unit derived from an ester, vinyl acetate, and substituted acrylamide, and contains units derived from at least three types of monomers.

The weight percent of terpolymer or interpolymer units derived from (meth) acrylic acid and salts thereof is about
10 to about 84%, preferably at least about 30%.

These (meth) acrylic acids and salts thereof have the formula (A): Wherein R ₁ is hydrogen or CH ₃ , X is hydrogen, a metal cation, or N- (R ₂ ) ₄ (where R ₂ is hydrogen, a C ₁ -CC ₄ alkyl group, C ₁ -C ₄ hydroxyalkyl group or a mixture thereof)].

Preferred (meth) acrylic acids and salts thereof include acrylic acid, methacrylic acid, and their sodium salts. Other vinyl dicarboxylic acids and their anhydrides, such as maleic acid, fumaric acid, itaconic acid and their anhydrides, can also be used in place of all or part of (meth) acrylic acid, Terpolymer and interpolymer salt components for use in stabilizing aqueous systems can also be used.

The units of the terpolymer or interpolymer derived from acrylamidoalkyl or arylsulfonate should be no less than 11% by weight and no more than about 40% by weight. In a terpolymer or interpolymer,
If the concentration of the acrylamidoalkyl or arylsulfonate unit is 11% by weight or less, a significant decrease in stabilization performance will occur, and if the unit in the selected terpolymer or interpolymer is about 40% by weight. More will affect the economic viability of the selected terpolymer or interpolymer. Acrylamide alkyl or aryl sulfonates useful in the terpolymers or interpolymers of the present invention have the formula (B): Wherein R ₃ is hydrogen or methyl, R ₄ is hydrogen or a C ₁ -C ₄ alkyl group, and R ₅ is a C ₁ -C ₈ alkyl group or C ₈ -C ₁₀ An aralkyl group, and X is the same as defined in the formula (A).

Other units of the terpolymer or interpolymer are:
Derived from one or more of the following vinyl esters as defined by formula (C), vinyl acetate as defined by formula (D), or substituted acrylamide as defined by formula (E): Is done. One or more of these units can be incorporated into a terpolymer or interpolymer, respectively. The total concentration of units of this third component in the terpolymer or interpolymer is
It ranges from at least about 5 to about 50% by weight, preferably from about 5 to about 30% by weight.

The vinyl ester selected has the formula (C): Wherein R ₆ is halogen or CH ₃ , R ₇ is a C ₁ -C ₆ alkyl group, a C ₆ -C ₁₀ aryl group, a C ₆ -C ₁₀ aralkyl group, or (Wherein, R ₈ is hydrogen or CH ₃ , R ₉ is a C ₁ -C ₆ alkyl group or hydrogen, and n is an integer of 1 to 3)].

The vinyl esters represented by formula (C) are different from the (meth) acrylates represented by formula (A).

The vinyl acetate unit has the formula (D): Can be indicated by

The substituted acrylamide unit has the formula (E): Wherein R ₁₀ is hydrogen or CH ₃ , R ₁₁ and R ₁₂ are hydrogen, C ₁ -C ₈ alkyl, C ₆ -C ₈ cycloalkyl, benzyl, or a compound represented by the formula (C Expression, as defined in R ₁₁ and R ₁₂ are not both hydrogen.]

The units of (meth) acrylic acid and its salts, when used by themselves, are cost effective suspending or dispersing agents that enable low levels of performance. The acrylamidoalkyl or aryl sulfonate units provide (meth) acrylic acid and its salt components with improved calcium tolerance and phosphate stabilization, and improved stabilization when iron is present I will provide a. Third
When the unit of the component is a selected vinyl ester, substituted acrylamide, or vinyl acetate, the present inventors have determined that the stabilization efficiency of the acrylamide alkyl or aryl sulfonate component against phosphates, zinc, and inorganic particulates. And found that it increased unexpectedly.

It has also been found that the water solubility of the selected terpolymer or interpolymer can be improved by incorporating vinyl ester or vinyl acetate units into the acrylamide or arylsulfonate component at selected weight ratios. . It has been found that when the unit of the third component is a substituted acrylamide, not a vinyl ester or vinyl acetate, the hydrolytic stability of the resulting terpolymer is unexpectedly improved.

The inventor has noted that when one or more types of the same third component monomer units (ie, two types of selected vinyl esters) were used to make an interpolymer, the stabilization of the same was achieved. The performance characteristics indicate that one such monomer unit
It was found that there was no significant improvement compared to selected terpolymers containing the same concentration of species only.

The inventor has also found that 2-acrylamido-2-methylpropanesulfonic acid (AMPS) is a preferred substituted acrylamidosulfonate, and hindered amides such as t-butylacrylamide, t-octylacrylamide, and dimethylacrylamide, Preferred (alkyl) substituted acrylamides have been found.

Terpolymers and interpolymers useful in the methods of the invention containing the selected units in the selected weight ratios have a weight average molecular weight in the range of about 3000 to about 25,000, preferably about 4000 to about 8000. Having.

The most preferred terpolymer of the present invention has about 57% by weight of units of (meth) acrylic acid or salt thereof, 23% by weight of AMPS, and 20% by weight of vinyl ester, vinyl acetate, or acryl-substituted acrylamide, And a terpolymer having a molecular weight in the range of about 4500 to about 5500 weight average molecular weight.

The following methods can be used to synthesize terpolymers and interpolymers useful in practicing the present invention.

Synthesis of Terpolymers and Interpolymers In general, the prior art describes some suitable synthetic methods for producing low molecular weight copolymers of (meth) acrylic acid. These methods can be used to produce terpolymers and interpolymers useful in the present invention.

U.S. Pat. No. 4,314,004 describes a method for synthesizing one such suitable copolymer, the description of which is incorporated herein by reference. This method requires a specified concentration range of the polymerization initiator and a specified molar ratio range of the initiator concentration and the concentration of certain metal salts to obtain the desired low molecular weight polymer useful in the present invention. I have. Preferred polymerization initiators are peroxide compounds such as ammonium persulfate, potassium persulfate, hydrogen peroxide, and t-butyl hydroperoxide. A preferred concentration range for the initiator is from about 1 to about 20% by weight, based on the weight of the monomer. The metal salts used to control the molecular weight preferably include cuprous chloride, cupric chloride, cuprous bromide, cupric bromide, cupric sulfate, cupric acetate, Ferrous, ferric chloride, ferrous sulfate, ferric phosphate, and ferrous phosphate are included. Polymerization initiator:
The molar ratio of the metal salt is preferably between about 40: 1 to about 80: 1. Terpolymers and interpolymers of (meth) acrylic acid useful in the present invention are preferably prepared in water at a polymer concentration of about 40 to about 50%, based on the total weight of the solution.

Another useful method for producing the aforementioned low molecular weight terpolymers and interpolymers is described in U.S. Pat.
No. 1,266. This description is incorporated herein by reference. In this method, isopropanol is used as a molecular weight regulator and as a reaction solvent. Further, as the reaction solvent, a mixture of isopropanol and water containing at least 45% by weight of isopropanol can be used. The polymerization initiator is
Free radical initiators such as hydrogen peroxide, sodium persulfate,
Potassium persulfate or benzoyl peroxide. The polymerization is carried out under pressure at a temperature of from 120 to 200 ° C. The concentration of the copolymer in the solvent is preferably between 25 and 45%, based on the weight of the total solution. When the polymerization is complete, isopropanol is distilled from the reactor and the polymer is neutralized with a base.

Another method for producing low molecular weight terpolymers and interpolymers useful in the present invention is disclosed in U.S. Pat.
No. 6,099, which is incorporated herein by reference. This method is directed to the production of cyano-containing oligomers, but can be used to produce low molecular weight polymers useful in the present invention. This method uses bisulfite as a polymerization molecular weight regulator and the resulting polymer has sulfonate end groups. A preferred bisulfite is sodium bisulfite, the concentration of which is 3-20% by weight, based on the weight of monomer. The free radical polymerization initiator is ammonium persulfate, sodium persulfate, potassium persulfate, hydrogen peroxide, or t-butyl hydroperoxide.
The concentration of the initiator is from about 0.2 to about 10% by weight based on the monomer. The polymerization temperature is preferably 20-65 ° C., and the concentration of the polymer in the aqueous solvent is 25% based on the total solution weight.
~ 55% by weight.

Test Method Next, a test method performed using the terpolymer and the interpolymer of the present invention for stabilizing precipitation of calcium phosphate in an aqueous system will be described.

Two types of cooling water were used. One is water containing iron contaminants and small amounts of phosphate, and the other is water containing no iron contaminants and high concentrations of phosphate ions. The percent settling generated by the addition of the terpolymer, interpolymer, or comparative conventional polymer is calculated by the following formula:

T: part of phosphate ion remaining in the solution / million (ppm) at the end of the test analyzed using the ascorbic acid method. (APHA standard, 13th edition,
page532, (1971)] I: ppm of phosphate in aqueous solution at the beginning of the test. The following general procedure was used for the two water tests.

A stock solution containing calcium ions (Ca ⁺² ) and optionally ferric ions (Fe ⁺³ ) was made from the chloride salt at twice the concentration required for the final test solution.

A second stock solution containing phosphate ions (PO ₄ ^-3 ) was made from disodium phosphate at twice the concentration required for the final test solution.

A stock solution was made containing 0.1% by weight of the active polymer (expressed in acid form).

In a 4 oz jar, the stock solution was added in the following order.

1. 50ml of phosphate stock solution.

2. 1 ml, 1.5 ml, or 2.0 ml of the polymer stock solution. This produces 10 ppm, 15 ppm, or 20 ppm of the active polymer, respectively.

3. 50 ml of calcium ion stock solution. The pH of each of the resulting mixtures was adjusted to 8.5. The jar was then capped and placed in a water bath at 70 ° C. for 17 or 24 hours according to the phosphate stock solution, as shown in Table 1. At the end of this time, the jar was removed from the water bath and the solution was filtered using 0.22 micron filter paper. Next, the filtered solution was analyzed using the ascorbic acid method to calculate parts / million (ppm). Table 1 shows the reagent concentrations, polymer compositions, molecular weights, and test results.

Example 1-10 is a comparative example. Examples 11-49 show that terpolymers and interpolymers with selected units and concentrations are copolymers of acrylic acid and AMPS, copolymers of acrylic acid and similar vinyl esters, and acrylic acid and alkyl-substituted acrylamide. And shows improved phosphate stabilization over the copolymers of US Pat. For example, Samples 2 and 3 show the conventional low molecular weight acrylic acid / AMPS copolymer phosphate stabilizing effect. However, these copolymers show poor phosphate stabilization (Test Condition 2) compared to selected terpolymers containing acrylic acid and AMPS units (eg, Sample 18). You will notice
Furthermore, Example 4 (copolymer of acrylic acid and hydroxyethyl methacrylate) shows a poor stabilizing effect on water containing iron and phosphate. On the other hand, Samples 17 and 18 show a significant improvement using the selected terpolymer. Also, a conventional copolymer of acrylic acid and hydroxypropyl acrylate (sample 5)
Is poor in its effect compared to samples 27-32 using the selected acrylic acid / AMPS / HPA terpolymer. The acrylic acid / alkyl substituted acrylamide copolymer of Sample 7 is a selected terpolymer of the invention containing substituted acrylamide, such as Samples 38 and 39,
Shows poor phosphate and iron stabilizing effects as compared to. In addition, comparative terpolymers made from acrylic acid, AMPS, and unsubstituted acrylamide also show poor performance as compared to the acrylic acid / AMPS / substituted acrylamide or vinyl ester terpolymers of the present invention. Samples 16 and 17 show that the AMPS units in the selected terpolymer need to be greater than 11%.

Sample 11-13 (ethyl acrylate), Sample 15 (vinyl acetate), Sample 14 (t-butyl acrylate), Sample 16-26
(Hydroxyethyl methacrylate), Samples 27-32 (Hydroxypropyl acrylate) and Samples 45-46 (Cellosolve acrylate) contained at least 5% by weight of vinyl ester units compared to acrylic acid / AMPS copolymer (Sample 3). Figure 4 shows the effective performance of the selected terpolymer incorporated.

In addition, a comparison of Samples 3 and 10 with Samples 33-44 demonstrates the unexpected and unexpected performance of terpolymers incorporating substituted acrylamide over terpolymers made from acrylic acid / AMPS and unsubstituted acrylamide. Is shown.

Samples 11-13, 18-21, 28-30, 33-35, 38 and 39 show the effect on increasing the amount of the third component unit in the terpolymer and decreasing the amount of acrylic acid. In many cases, the phosphate stabilizing effect is shown to improve when the amount of units of the third component in the terpolymer increases to 5% by weight or more.

Samples 48 and 49 show that a further improvement would be made over the terpolymer if a selected interpolymer containing both a vinyl ester monomer and an alkyl-substituted alkylacrylamide at a concentration of at least 5% by weight was used. Is shown. In comparison, sample 47 shows that when the two vinyl esters were used to make an interpolymer with acrylic acid and AMPS, they were substantially more effective than the selected terpolymer containing equal amounts of any one of these vinyl esters. No significant improvement has occurred.

Also, the selected terpolymers and interpolymers are effective in stabilizing aqueous systems containing carbonates and sulfates. Table 2 shows the effect of preventing precipitation on calcium carbonate and calcium sulfate. The measured value of calcium sulfate is determined by the standard test method (NACE standard TM-03-
74), and the calcium carbonate measurements were obtained using the same method as described in U.S. Pat. No. 4,326,980, which are incorporated herein by reference. Used in the book.

In addition to the stabilizing effect on phosphates, carbonates and sulfates in aqueous systems, the inventors have determined that useful dispersants for inorganic microorganisms in which selected terpolymers and interpolymers are suspended in water. Was found.
To exemplify this, the inventor has used an aqueous system containing kaolin clay or iron oxide to produce an aqueous system containing suspended, mud, silt, or other hydrophilic particulates, such as calcium carbonate. Was imitated. Kaolin clay is mud,
Simulated product of inorganic fine particles such as silt or calcium carbonate. Iron oxide was chosen because it is commonly found as a hydrophobic particulate in recirculating cooling water. Iron oxide dispersibility tests indicate the ability of selected terpolymers to disperse hydrophobic particulates, such as iron phosphate, and various forms of calcium phosphate, iron hydroxide, and iron oxide.

The test methods used for the kaolin dispersibility and iron oxide dispersibility tests are as follows.

Kaolin dispersibility test As calcium carbonate in multimix cups
430 ml of water containing 200 ppm CaCl ₂ and Hydrite UF
0.43 g of kaolin (1000 ppm kaolin) was added. The mixture was mixed for 10 minutes, then the pH of the mixture was adjusted to pH 7.5 using sodium hydroxide. 100 ml of the conditioned mixture is placed in a 4 oz. Jar, into which 5 pp of polymer
m (0.5 ml of a 0.1% solution adjusted to pH 8.0) was added. The jar was capped and left for 2 hours without stirring. Next, the upper 20 ml of each jar was placed in a 1 oz glass bottle, and the turbidity of the solution in the vial was measured using an HF type DRT 100D turbidimeter, and the turbidity unit (NTU ). The results are shown in Table 3.

The iron oxide dispersibility test was performed in a multi-mix cup.
430 ml of water containing 200 ppm CaCl ₂ as calcium carbonate,
And Fe ₂ O ₃ (Fisher reagent)
(700 ppm Fe 203). The mixture was mixed for 15 minutes and then the pH was adjusted to pH 7.5 using sodium hydroxide. A 100 ml aliquot was then placed in a 4 oz. Jar, into which 3 ppm of polymer (pH 8.
0.3 ml of a 0.1% solution adjusted to 0) was added. The jar was capped and placed on a low speed shaker for 15 minutes. Following shaking, the jar was left unstirred for 4 hours. The upper 20 ml of each jar was then taken and placed in a 1 oz glass bottle and measured using an HF type 100D turbidimeter and indicated as NTU.
Higher NTU values indicate better dispersibility. The results are shown in Table 3.

In general, the selected terpolymers showed improved particulate dispersibility over conventional copolymer dispersants for kaolin and iron oxide.

The following table shows that selected terpolymers of the present invention have improved performance as stabilizers for phosphates and dispersants for inorganic particulates in aqueous systems compared to known copolymers and homopolymers. Present the comparative data shown.

Comparative sample 50 has an M (weight average) of 5070, 19% (active polymer solids) of acrylic acid / AMPS (6.7 / 93.7% by weight) copolymer, acrylic acid and HEMA (80/20% by weight,
M5460) with 81% (active) of the copolymer. For a fair comparison, 24.8 ppm of the active polymer mixture was compared to 20 ppm of the terpolymer. The coefficient of 1.24 times is 66% by weight of acrylic acid / AMPS 18
% By weight and 16% by weight of HEMA can be compared to terpolymer samples (20 and 25) by 82% by weight of AA, 22% by weight of AMPS and HEMA
20% by weight of all compositions resulted.

Comparative sample 51 contains 66% by weight (active) of AA / EA (70/30% by weight) copolymer (M5340) and AA / AMPS (6.3 / 93.7%).
% By weight) 25% by weight of copolymer (M5070) (active) and 9% by weight of poly AA (M4570) (active),
Was made by mixing

Comparative sample 52 was composed of 60% by weight (activity) of AA / HPA (62/38% by weight) copolymer (M3000) and AA / AMPS (6.3 / 96.7%).
% By weight) 25% by weight of copolymer (M5070) (active) and 15% by weight of poly AA (M4570) (active),
Was made by mixing

Comparative sample 53 was composed of 66.7% by weight (activity) of AA / t-BAM (70/30% by weight) copolymer (M2770) and AA / AMPS (6.3 / 9%).
3.7% by weight) 24.5% by weight of copolymer (M5070)
(Active), and 8.8% by weight of poly AA (M4570).

Table 4 shows the results of comparative tests performed by the same general procedure as described above.

Table 4 shows the terpolymer for phosphate stabilizing action and inorganic fines dispersibility in all compositions as compared to a mixture of copolymers formulated to be substantially equivalent to the terpolymer composition. It shows the unexpected excellence of the polymer.

In addition to dispersing the particulates at low concentrations in aqueous systems, the present inventors have determined that selected terpolymers as dispersants to reduce the viscosity of concentrated dispersions or slurries of kaolin clay or calcium carbonate. The ability was checked. The test procedure used for the kaolin clay slurry is as follows.

PH 7 in a stainless steel mixing cup.
6.13 g of a 10% solution of the selected polymer of 0, 4.66 g of a 20% solution of sodium carbonate, and enough water to bring the aqueous solution weight to 210 g. To this, 490 g of ASP kaolin clay was added, and the resulting mixture was mixed with a multimixer (multimixe).
r) for about 5 minutes at low speed, followed by 15 minutes at high speed.
Stir for a minute to make a slurry. Then, with 0.125% by weight of the resulting (polymer on clay) dispersant, 7
500 g of a 0 wt% clay slurry was taken, placed in a pint jar, capped and shaken gently until the slurry had cooled to room temperature. The viscosity of the slurry was then measured using a Brookfield RV uiscometer and the pH of the slurry was measured. 0.88 g of a 10% polymer solution and 2.05 g of kaolin clay were added to the pint jia (adding 0.025% by weight of the total dispersant and keeping the kaolin clay solids at 70%). The pint jer was then stirred at high speed for 2 minutes using a multi-mixer. The viscosity was measured and then additional polymer and clay were added and mixed, and the measurements were repeated as described above. Table 5 shows the results.

The test procedure used to determine the dispersibility of the terpolymer in the concentrated calcium carbonate slurry is as follows.

PH 1 in a 1 volume stainless steel mixing cup
17.5 g of a 10% polymer solution of about 7.0, and the weight of the aqueous solution
Pour enough water to make 300g. To this, 700 g of M60 precipitated calcium carbonate (manufactured by Mississippi Lime Company) was added, followed by stirring at low speed for about 5 minutes using a multi-mixer to form a slurry. The slurry was then stirred at high speed for 15 minutes. Then poured the resulting 0.25 wt% to 500g of 70 wt% CaCO ₃ slurry with a (polymer on CaCO ₃₎ in Paintojiya, capped, slurry was shaken make boiled to cool to room temperature. Next, the viscosity of the slurry was measured using a B-type RV viscometer. To this slurry, 1.76 g of a 10% polymer solution and 4.10 g of calcium carbonate were added to increase the total dispersant amount by 0.05% by weight, while
The slurry solids were maintained at 70%. Next, the slurry was stirred at a high speed for 2 minutes using a multi-mixer, and the viscosity was measured. These steps are repeated as described above,
The table shows the decrease in viscosity.

Tables 5 and 6 show the effectiveness of terpolymers and interpolymers as dispersants on aqueous kaolin clay slurries and calcium carbonate slurries. As the polymer concentration increases, the slurry viscosity decreases until the viscosity reaches a minimum. The viscosity begins to increase as the polymer concentration increases above that required to reach a minimum viscosity. The viscosity of the slurry when no dispersant is added is extremely high and cannot be measured at 20 RPM.

The hydrolytic stability of the polymer used for water treatment is important. Many water treatment formulations, especially those containing polyphosphate, must maintain a high pH (pH 11 or higher) to prevent the return of polyphosphate to orthophosphate. Polymers that are not stable to high pH must be packaged separately from the polyphosphate. Table 7 shows a comparison of the hydrolytic stability of some terpolymers of the present invention. This test creates a 10% (active) polymer solution using deionized water, adjusts the solution to pH 13.5, and then
The conditioned sample was heated at 70 ° C at the intervals shown in Table 7.
The polymer was placed in an oven and then tested for its ability to prevent phosphate precipitation in high phosphate water (as shown in Test Condition 2) at 20 ppm polymer concentration. A significant decrease with the percent settling inhibition indicates that the polymer is not hydrolytically stable.

This table shows that the AA / AMPS / vinyl ester terpolymers (samples 13, 20, and 31) are not hydrolytically stable, while having high initial protection, and therefore high pH formulations Indicates that it must be separated and packaged.

Samples 35 and 39, terpolymers of AA / AMPS / alkyl-substituted acrylamide, are hydrolytically stable and maintain high initial phosphate settling performance, and are therefore highly packaged in a single package. It can be combined with a pH formulation.

In order for the polymer to function properly for water treatment,
The polymer must be water-soluble when the polymer is added to water. For a given composition, the solubility of the polymer in water increases as the molecular weight of the polymer decreases. Therefore, the polymers must be compared at the same molecular weight in order to make a valid comparison of the effect of the composition comprising the terpolymer on solubility. Table 8 shows a comparison of the solubility of selected terpolymers with copolymers and homopolymers having the same molecular weight. Each of the aqueous solutions contains 100 ppm (active) polymer and 6000 ppm CaCl ₂ as calcium carbonate. The sample is placed in a 4 oz. Jar and then placed in a 61 ° C. water bath. The samples were then brought to equilibrium temperature and the percent transmission was measured using a Brinkman PC / 600 colorimeter using a 520 nm filter. The high solubility of the polymer is indicated by a high% transmission.

Table 8 shows that AA / AMS of the present invention at almost the same M
Terpolymer of vinyl ester monomer or alkyl-substituted acrylamide (Samples 30 and 39)
Indicates that it has more solubility than the AA / AMPS copolymer (Sample 3) or the copolymer of AA and vinyl ester (Sample 6). The solubility of the AA / substituted acrylamide copolymer is equivalent to that of the AA / EA copolymer, i.e., the AA / A of the present invention.
It would easily be expected to have less solubility than the MPS / substituted acrylamide terpolymer.

In addition, polymers made from about 60 to about 90% by weight of (meth) acrylic acid and its salts, and about 40 to about 10% by weight of substituted acrylamide, and having a weight average molecular weight of about 2500 to about 8000, are present in aqueous systems. Has been found to be unexpectedly useful as a suspending agent for zinc and salts thereof. The result was converted to the ninth
It is shown in the table.

Comparison of industrially used boiler treating polymers with the terpolymers of the present invention provides a useful measure of their performance. Typically, the polymer is placed in boiler feed water at a dose of about 0.5 to about 5 mg / L. In recirculated boiler water, the polymer concentration will typically be from about 5 to about 50 mg / L due to concentration of dissolved solids due to the formation of water vapor.

The screening method used to test the efficacy of these polymers was 19
It is based on the method proposed at the 46th Annual Meeting of the International Water Conference, Pittsburgh PA, November 4-7, 1985. "Treatment and temperature effects on turbidity and morphology in boilers (Treatmen
t and Temperature Effects on Turbidity and Morphol
ogy in Boilers) ”includes Fe ₃ O ₄ and Fe
A method is described that uses synthetic boiler water containing an excess of calcium and magnesium with iron added as (OH) ₃ .

This synthetic boiler water can be compared to actual boiler water, or feed water, which is leaking material having hardness in such a composition. In this method, the ability of the polymer to prevent settling of the dispersed boiler sludge was determined by measuring the turbidity of the dispersion after settling for one hour.

The synthetic boiler water used in these tests was made as follows.

_{a.5.68g / L 14.78g c.4.24% Na 3} PO 4 · 12H 2 O solution 14.78gd of 14.78g b.6.63g / L magnesium sulfate solution calcium hydroxide _{solution, 1.81% Na 2 SiO 3 ·} 9H 14.78 g of a ₂ O solution e. 5.78 g / L Fe ⁺³ made from 14.78 g f.FeCl _{3 of a} 5.41% Na ₂ CO ₃ solution and adjusted to pH 11
137.72 g of the above dispersion was placed in a 2 l volumetric flask. 50 mg of Fe ₃ O ₄ was added to the flask, and deionized water was added to fill the marked line.

100 ml of the aqueous synthetic boiler dispersion was placed in a 4 oz. Jar and placed on a laboratory shaker at high speed for 10 minutes.

The jar was then removed from the shaker and 0.5 or 1.0 ml of a 0.1% active polymer deionized aqueous solution adjusted to pH 9.5.
Was added (corresponding to 5 or 10 mg / L of active polymer).
The jar was then placed on a shaker at high speed for 5 minutes. The upper 20 ml of the dispersion was pipetted and the turbidity was measured and indicated as turbidity units (NTU) by nephelometer. In this test, high turbidity indicates good dispersibility of the sludge in the boiler water.

The solid obtained from the mixture of the above components has the following composition:

Dissolved solid phosphate 46mg / L Silica 12mg / L Sulfate 39mg / L Carbonate 226mg / L Sodium 214mg / L Dispersed solid hydroxyapatite 57mg / L Serpentin 38mg / L Magnetite 25mg / L Hematite 25mg / L The results are shown in Table 10 below.

As is apparent from Table 10, the terpolymer of the present invention (Sample GJ) has a better ability to disperse boiler sludge than the conventionally used polymer. This is due to the high N in the 5 mg / L and 10 mg / L spiked polymer solids.
Proven by TU values.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Jillon Natri, 504 Welshille Road, Ambler, PA, United States of America 504 (56) References JP-A-61-42400 (JP, A) JP-B-59-44119 (JP, B2) US Patent 4,432,884 (US, A)

Claims (12)

(57) [Claims] (1) 10-84 of (meth) acrylic acid and a salt thereof
% By weight, 11% by weight or more and 40% by weight or less of acrylamidoalkylsulfonate or acrylamidoarylsulfonate, and at least 5 to 50% by weight of one or more units selected from the group consisting of vinyl esters, vinyl acetate, and substituted acrylamides. % Of an aqueous system comprising adding an effective amount of a water-soluble polymer to the aqueous system. 2. The method of claim 1 which is effective in preventing precipitation of inorganic phosphate, carbonate, or sulfate in an aqueous system. 3. An aqueous system comprising iron, zinc, their salts, mud,
2. The method of claim 1 which is effective for dispersing inorganic particulates selected from the group consisting of silt and clay. 4. The method of claim 1 wherein said water-soluble polymer has a weight average molecular weight in the range of 3000-25000. 5. The water-soluble polymer comprises 10 to 84% by weight of (meth) acrylic acid and a salt thereof, 11% to 40% by weight of 2-acrylamido-2-methylpropanesulfonic acid, and vinyl. The method of claim 1, wherein the method comprises at least 5 to 50% by weight of one or more units selected from the group consisting of esters, vinyl acetate, and substituted acrylamides. 6. A vinyl ester having the formula Wherein R ₆ is halogen or CH ₃ , R ₇ is a C ₁ -C ₆ alkyl group, a C ₆ -C ₁₀ aryl group, a C ₆ -C ₁₀ aralkyl group, or (In the formula, R ₈ is hydrogen or CH ₃ , R ₉ is a C ₁ -C ₆ alkyl group or hydrogen, and n is an integer of 1 to 3)]. A method according to claim 1 or 5, characterized by the features. 7. The substituted acrylamide has the formula Wherein R ₁₀ is hydrogen or CH ₃ , R ₁₁ and R ₁₂ are hydrogen, C ₁ -C ₈ alkyl group, C ₆ -C ₈ cycloalkyl group, benzyl group, or (Wherein R ₈ is hydrogen or CH ₃ , R ₉ is a C ₁ -C ₆ alkyl group or hydrogen, and n is an integer of 1 to 3) And wherein both R ₁₁ and R ₁₂ are not hydrogen.]. The method according to claim 1 or 5, wherein 8. The method of claim 1, wherein said water-soluble polymer is a terpolymer having a weight average molecular weight of 4000 to 8000. 9. 10-84 of (meth) acrylic acid and a salt thereof
% By weight, 11% by weight or more and 40% by weight or less of 2-acrylamido-2-methylpropanesulfonic acid, and formula Wherein R ₁₀ is hydrogen or CH ₃ , R ₁₁ and R ₁₂ are hydrogen, C ₁ -C ₈ alkyl group, C ₆ -C ₈ cycloalkyl group, benzyl group, or (Wherein, R ₈ is hydrogen or CH ₃ , R ₉ is a C ₁ -C ₆ alkyl group or hydrogen, and n is an integer of 1 to 3) 9. A process according to claim 8 wherein the terpolymer comprises from 5 to 50% by weight of a substituted acrylamide having the formula: wherein both R ₁₁ and R ₁₂ are not hydrogen. 10. The water-soluble polymer is (meth) acrylic acid or 57% by weight of a salt thereof, 2-acrylamide-2-
23% by weight of methylpropanesulfonic acid and 20% by weight of units of a third component selected from the group consisting of vinyl esters, vinyl acetate and substituted acrylamides;
The method according to claim 1, which is a terpolymer having a weight average molecular weight of 4500 to 5500. 11. A water-soluble polymer comprising 10 to 84% by weight of acrylic acid, 11% to 40% by weight of 2-acrylamido-2-methylpropanesulfonic acid, and at least 5 to 50% by weight of substituted acrylamide. 2. The method according to claim 1, wherein the method comprises hydrolyzing under high pH conditions. 12. The boiler, wherein the aqueous system is a boiler containing a dissolved and dispersed solid selected from the group consisting of calcium carbonate, calcium phosphate, magnesium hydroxide, serpentine, magnetite, and hematite. 2. The method according to claim 1, wherein the concentration of the polymer added to the mixture is 0.1 to 500 ppm.