JPH0576494B2 - - Google Patents

Description

[Detailed description of the invention]

SUMMARY OF THE INVENTION The present invention provides a viscosification agent.
relates to thickening agents for aqueous and salt solutions that are mixtures of water-soluble polymer backbones containing anionic comonomers and copolymers of water-soluble polymer backbones containing cationic comonomers. Aqueous solutions of the invention containing polymer complexes can exhibit dilatant properties. The present invention provides that the inventive interpolymer complexes comprising an anionic copolymer and a cationic copolymer can be used as an alternative to the use of very high molecular weight polymers.
It is also disclosed that they may be useful as drag reducers for aqueous systems. The present invention provides that these interpolymer complexes can be used as drag reducers for multicomponent aqueous solutions, such as well control and workover fluids.
It is disclosed that it may be useful as a workover fluid, marine applications such as ships, blood, etc. In the latter fluids, the addition of the interpolymer complexes of the invention enhances the flow rate of blood in the circulatory system of biological species (animals and humans). In most cases, this has a beneficial effect on the organism, such as increasing the rate at which the blood transports oxygen, medicines, nutrients, etc. to the organs. A similar enhancement effect would be seen with regard to fluid circulation in plants. General Description of the Invention The aqueous thickening agent for water and high ionic strength solutions of the present invention is produced by the interaction of a mixture of two different polymers. There are a number of copolymers suitable for making the complexes of the present invention. One preferred system has (A) a sulfonate content of 1 to
(B) a copolymer of acrylamide and neutralized styrene sulfonate having an ionic monomer content ranging from 1 to 50% by weight; Amide

It consists of a mixture of a copolymer with a quaternary ammonium salt such as Various other polymer systems can be used in the present invention, subject to the limitations described below. The copolymer (A) must be based on a largely water-soluble polymer backbone containing an anionic comonomer. The water-soluble polymer backbone of copolymer (A) is polyacrylamide. The anionic comonomer of copolymer (A) is selected from the group consisting of α,β ethylenically unsaturated monomers having sulfonic or carboxylic or phosphoric acid groups neutralized with metal or amine cations. Particularly preferred and representative polymer species are styrene sulfonate, vinyl sulfonate, allyl sulfonate, acrylamide propyl sulfonate, where the sulfonic acid group is an ammonium cation or A, A, A of the periodic table of elements,
It is neutralized with a metal cation selected from the group consisting of B and B genus. Copolymer (A) contains 1-50% by weight, more preferably 2-30%, most preferably 3-20% by weight of anionic comonomer.
The number average molecular weight of copolymer (A) is 10000−
5,000,000, more preferably 20,000-3,000,000, most preferably 50,000-1,000,000. Copolymer (A)
are generally prepared by techniques known in the art of polymer chemistry. Preferably, free radical initiation is used. For example, copolymerization of acrylamide and sodium styrene sulfonate is carried out in water using a conventional initiator such as potassium persulfate, as described in the Examples below. Typically, these polymers are made in this manner, but there are many variations that can be carried out without departing from the spirit of the invention. The copolymer (B) must be based on a highly water-soluble polymer backbone containing cationic species.
The water-soluble polymer main chain of copolymer (B) is polyacrylamide. The cationic comonomers of the copolymer (B) are selected from α,β ethylenically unsaturated monomers having quaternary bases or pyridinium groups present as functional groups. Particularly preferred are N,N,N-trimethylammoniumpropylmethacrylamide and vinylpyridine. Copolymer (B)
contains 1-50% by weight, more preferably 2-30%, most preferably 3-20% by weight of cationic comonomer. The number average molecular weight of the copolymer (B) measured by gel permeation chromatography is 10000-5000000, more preferably 20000-
3,000,000, most preferably 50,000-1,000,000.
Copolymer (B) is prepared in the same manner as is commonly used for the preparation of copolymer (A), as described in the examples below. One important property of the materials used in this invention is the stoichiometry of the ionic species when polymers (A) and (B) are blended together. We have investigated a wide range of such stoichiometry, including the anionic species/
The ratio of cationic species ranges from 30/1 to 1/30. Even wider ranges of such stoichiometry are believed to be within the scope of this invention. However, it has been found that when this ratio is around 1/1, the solution behavior of such complexes is less pronounced. However, when substantially departing from this ratio in aqueous systems, the resulting solutions exhibit unusual viscous behavior as a function of temperature or concentration. Therefore, the ratio of anion functionality/cation functionality is:
45/1-1.1/1, most preferably 30/1-1.2/
1. Or anionic group/
The ratio of cationic groups can be 1/45-1/1.1, more preferably 1/30-1/1.2. A complex mixture of copolymer (A) and copolymer (B) ideally comprises copolymer (A) and copolymer
Produced by mixing together separate aqueous solutions of (B). The aqueous solution of copolymer (A) is 100ml of water.
0.02-10g, more preferably 0.04-8g,
Most preferably it contains 0.05-5g of copolymer (A). The aqueous solution of copolymer (B) is
0.02-10g, more preferably 0.04-8g, most preferably 0.05-5g of copolymer (B). For high ionic strength solutions, the complex mixture of copolymer (A) and copolymer (B) is ideally formed by mixing separate high ionic strength solutions of copolymer (A) and copolymer (B) together. It is manufactured by
The high ionic strength solution of copolymer (A) contains 0.1-5 g, preferably 0.2-5 g, most preferably 0.5-2 g of copolymer (A) per 100 ml of water, and the solution contains 0.0005-0.5 mol per 100 ml of water. More preferably 0.001-0.5 mol, most preferably 0.01-0.5
Contains moles of acids or bases or salts such as sodium chloride. The aqueous solution of copolymer (B) is 100ml of water.
0.1-5g, more preferably 0.2-5g, most preferably 0.5-2g of copolymer (B) per copolymer (B). In the case of polymer solutions exhibiting dilatant properties, interpolymer complexes of anionic and cationic copolymers are typically prepared by preparing a first solution of the anionic copolymer in an aqueous solution. . A second solution of cationic copolymer is prepared by dissolving the cationic copolymer in an aqueous solution. The concentration of anionic copolymer in the solution is 0.001-10.0 g/dl, more preferably 0.01-5.0 g/dl, most preferably 0.1
-4.0g/dl. The concentration of the cationic copolymer in the second solution is 0.001-10.0 g/dl, more preferably 0.01-5.0 g/dl, most preferably 0.1-4.0
g/dl. A first solution of anionic copolymer and a second solution of cationic copolymer can be mixed together, thereby allowing the anionic and cationic copolymers to interact to produce an aqueous interpolymer complex. Alternatively,
Both polymers can be dissolved together at the same time. The molar ratio of anionic monomer units in the copolymer to cationic monomer units in the copolymer in the interpolymer complex is 0.05-20, more preferably 0.1-10, most preferably 0.25. The concentration of interpolymer complex in aqueous solution is 0.01−
10 g/dl, preferably 0.1-7 g/dl, most preferably 0.2-5 g/dl. In the case of interpolymer complexes of anionic and cationic copolymers that function as drag reducers, the polymer solution is typically prepared by preparing a first solution of the anionic copolymer in an aqueous solution. be done. A second solution of cationic copolymer is prepared by dissolving the cationic copolymer in an aqueous solution. The concentration of anionic copolymer in solution is 0.001-10.0 g/dl, more preferably 0.01-5.0 g/dl, most preferably
It is 0.1-4.0g/dl. The concentration of the cationic copolymer in the second solution is 0.001-10 g/dl, more preferably 0.01-5.0 g/dl, most preferably 0.1-4.0
g/dl. A first solution of anionic copolymer and a second solution of cationic copolymer can be mixed together, thereby allowing the anionic and cationic copolymers to interact to produce a water-soluble interpolymer complex. Alternatively,
Both polymers can be dissolved in water at the same time. The molar ratio of anionic monomer units in the copolymer to cationic monomer units in the copolymer in the interpolymer complex is 0.05-20, more preferably 0.1-10, most preferably 0.2-5. The concentration of the interpolymer complex drag reducer in the aqueous solution is 0.0004-10 g/dl, more preferably 0.001-10 g/dl.
Further reductions can be made to 7 g/dl, most preferably in the range of 0.005-5 g/dl. DESCRIPTION OF THE PREFERRED EMBODIMENTS The following examples are intended to illustrate the invention and are not intended to limit it. Example 1 A representative example for the synthesis of acrylamide (AM)-sodium styrene sulfonate (SSS) copolymer is shown below. Add 25 g of acrylamide, 12.75 g of sodium styrene sulfonate, and 500 ml of distilled water to the four-necked flask from Step 1. The solution is purged with nitrogen gas for 1 hour to remove dissolved oxygen. The solution was heated to 55°C when the nitrogen gas purge was started. At this point, 0.05g
of potassium persulfate was added to the solution. 24 hours later,
The polymer was precipitated from solution with acetone. The obtained polymer was then washed several times with large amounts of acetone and dried in a vacuum dryer at 60° C. for 24 hours. As a result of elemental analysis, the sulfur content was 4.16% by weight, which corresponds to 11.2 mol% of sodium styrene sulfonate. Example 2 A representative example for the synthesis of acrylamide, methacrylamide propyltrimethylammonium chloride (MAPTAC) copolymer is essentially the same as the polymerization of the previous example. However, as shown below, use an appropriate amount of MAPTAC instead of SSS. Acrylamide 25.0g MAPTAC (50% solution) 27.4g This reaction is carried out using the instructions in the above specification. As a result of elemental analysis, the chlorine content was 4.75% by weight, which corresponds to 11.9 mol% MAPTAC. As known to those skilled in the art, the concentration of ionic monomer attached to the growing polymer chain is directly related to the initial concentration of the reactive species. Therefore, adjustment of the ionic charge within the polymer structure was achieved by varying the initial anionic or cationic vinyl monomer concentration. Examples 1 and 2 produced a series of copolymers with different compositions as shown in Table 1.

Example 3 For each mixture forming the complex, an aqueous solution of acrylamide-N,N,N-trimethylammonium propylene methacrylamide copolymer (abbreviated as MAPTAC) and an aqueous solution of acrylamide-sodium styrene sulfonate copolymer (abbreviated as SSS) were used. ) are prepared separately. The concentration of each solution is calculated such that when equal volumes of MAPTAC or SSS solutions are blended, the required molar ratio of MAPTAC/SSS is obtained while maintaining a constant polymer concentration in the blend of 2%. The blend was made by injecting the acrylamide-sodium styrene sulfonate solution into the stirring acrylamide-N,N,N-trimethylammoniumpropylmethacrylamide solution and stirring for several hours to ensure optimal mixing and blending. Manufactured by Various concentrations of each blend were obtained by diluting this 2% strength blend with water. Thus, using samples -C and -E, approximately
Series of SSS/1.2/1, 6.01/1, 24/1
A ration of MAPTA was prepared. According to the above method,
Samples were prepared as follows (AM indicates acrylamide). -A-0.286g of -C in 50ml of water (70AM/
30SSS) -B-1.714g of -E (95AM/
5MAPTAC) -C-0.909 g of -C in 50 ml of water -D-1.091 g of -E in 50 ml of water -E-1.540 g of -C in 50 ml of water -F-0.462 g of -E in 50 ml of water After stirring and dissolving the sample at ambient temperature,
The viscosity of each solution was obtained at 25°C. -A and-
B, preparing a blend of the above solutions by blending -C and -D, -E and -F;
The resulting blends were −AB and −, respectively.
They were called CD and -EF. At 25℃, with a Burckfield viscometer,
The viscosities of the individual components measured at various spindle speeds are shown in Table 2. The viscosity of each blend at various temperatures and spindle speeds is shown in Table 3.

【table】

【table】

[Table] The above blended solution with a concentration of 2% was diluted by adding water in the following manner to create a series of solutions with concentrations of 1.5, 1.0, and 0.5%, which were named as follows. Next, the respective viscosities at 0, 25, 50 and 75°C were measured and shown in Table 4. The solution was diluted as follows.

【table】

【table】

【table】

[Table] Example 4 Follow the above procedure, but this time MAPTAC/
A series of blends with SSS ratios of 1.24/1, 6.2/1, and 24/1 were prepared. These blends were obtained by first mixing -A and -G based polymer solutions to a total polymer concentration of 2%. These solutions were then diluted to 1.5, 1, and 0.5% concentrations. The dilution was carried out as described below and the observed viscosities are shown in Table 5. Samples used based on -A and -G at 2%: -AB (1.24/1 22.8MAPTAC/
3.06SSS, 2% concentration in water) -CD (6.2/1 22.8MAPTAC/3.06SSS,
2% concentration in water) -EF (24/1 22.8MAPTAC/3.06SSS,
2% concentration in water) These samples were then diluted as follows. −AB− 34.5ml−AB

[Table] Table 5 shows the solution viscosities at these various dilutions.

【table】

【table】

TABLES Tables 3, 4 and 5 show the viscosity-temperature relationship for certain polymer concentration ranges. Apparently, as the ratio of cationic to anionic species approaches 24/1, the resulting polymer solution behaves very erratically, with the solution viscosity actually increasing with temperature. The most striking phenomenon seen in Tables 4 and 5 is the dependence of viscosity on polymer concentration. Unlike normal polymer solutions, the viscosity values shown here do not decrease monotonically as the polymer concentration decreases. In fact, in the 2%-1% concentration range, the solution viscosity changes in certain cases, especially for one ionic species (i.e.
MAPTAC) is 20 more than the other (i.e. SSS)
When it's larger by a factor of two or so, it's actually increasing. This behavior appears to be a unique and perhaps the first example of such a polymer solution whose viscosity increases with dilution. Similarly, observations have shown that when one ionic component is in higher proportion than the other, the solution viscosity can remain constant or actually increase substantially with temperature. Although this behavior is sometimes observed in hydrocarbon solutions, this appears to be the first time such behavior has been observed in a homogeneous aqueous solution. The above solutions based on water-soluble polymer complexes exhibit unusual and potentially useful properties. In particular, the field of water-based lubricants is one where solutions that maintain a constant viscosity over a wide temperature range are particularly useful. It is clear that the viscosity of the individual polymer components in their respective uncomplexed states decreases monotonically with increasing temperature. Typically, the viscosity value at 75°C is only 1/5 of the viscosity value at 0°C. Clearly, the present invention provides a new method for adjusting the viscosity of aqueous solutions. It is clear that this method is applicable to a variety of water-based fluid conditioning including cutting fluids, hydraulic fluids, drilling muds. Moreover, the unusual behavior in which the solution viscosity actually increases when diluting a polymer complex solution is a very useful feature when viscosity control by dilution is desired, such as in oil recovery processes. Example 5 The following table shows AM-co-MAPTAC:AM-co-
Typical viscous behavior (0-75°C) of 0.1M sodium chloride solution containing SSS interpolymer complex is shown. This complex has an ionic monomer molar ratio SSS/
Manufactured to have a residual charge of MAPTAC. This special complex contains 32.9 mol%
MAPTAC with SSS-co-AM copolymer and 3.6%
-co-AM copolymer with a molar ratio of 2.3/1.0 formed from appropriate concentrations. The above mole % refers to the ionic content within the respective copolymer structure. The concentration of the complex in the solution was 2 g/dl. Viscosity (cps) Viscosity (cps) Temperature (°C) 0.1M NaCl unsalted 0 76 65000 25 87 39000 50 74 15000 75 56 550 For comparison, individual copolymer components, AM-co
- MAPTAC and AM-co-SSS have viscosities of 220 cps and 210 cps at 2 g/dl in fresh water, respectively. Addition of 0.1M NaCl causes AM−co
-The viscosities of MAPTAC and AM-co-SSS are approximately 34 cps and 19 cps at 2 g/dl, respectively.
Examining these data, the water-soluble interpolymer complex is dramatically more effective as a high ionic strength aqueous phase thickener than either of the individual components at low polymer concentrations. Moreover, the viscosity values are significantly higher than the average values of the respective copolymers. Furthermore, it can be seen that the viscosity of the complex in salt-free solution gradually decreases with increasing temperature, whereas an isoviscosity effect occurs in high ionic strength media. This is a new and unexpected result. Although the underlying mechanism is not completely understood, this phenomenon has a variety of potential technological applications. Example 6 In this example, the ionic strength of the NaCl solution of Example 5 is reduced (0.01 M) and the isoviscosity effect is again observed. Appropriate data is shown in the table below. Temperature (°C) Viscosity (cps) 0 110 25 165 50 75 75 105 Example 7 The following table shows that at high ionic strength (0.2M NaCl),
High ionic monomer molar ratio (4.6 SSS/MAPTAC)
A typical example of the viscosity-temperature behavior of an aqueous solution (2 g/dl) with Temperature (°C) Viscosity (cps) 0 190 25 275 50 245 75 175 These data show that increasing the SSS/MAPTAC ratio results in a significant increase in viscosity. Moreover, isoviscosity effects are also observed. again,
In comparison, the individual copolymer components of the complex have significantly lower viscosities (or their average viscosity values) under the same experimental conditions. Example 8 The table below is a typical example of the viscosity-shear rate behavior of an aqueous solution containing an interpolymer complex at 250<0>C. The complex was prepared such that the solution had a residual charge as indicated by the ionic monomer molar ratio, SSS/MAPTAC, of 1.15/1.0. Polymer concentration was 1 g/dl. Shear rate (sec ^-1 ) Viscosity (cps) 3.0 360 6.0 310 9.0 280 12.0 270 22.0 230 30.0 265 50.0 290 75.0 310 105. 260 110. 240 225. 180 250. 160 30 0. 150 data indicates that the shear rate is relatively When low, it shows that the viscosity decreases as expected. But about
At shear rates greater than 22 sec ^-1 the viscosity begins to increase (dilatant behavior). Shear rate is 100sec ^-1
A further increase in viscosity is observed even when approaching . The individual copolymer components of the complex exhibit a monotonic decrease in viscosity under the same experimental conditions. Therefore, it is easy to see that water-soluble low charge density interpolymer complexes are effective as dilatant fluids in aqueous solutions and, moreover, are effective viscosifiers over a wide range of shear rates. The mechanism of viscosity enhancement in these solutions is believed to be primarily due to an increase in the apparent molecular weight of the complex due to the formation of intermolecular ionic bonds. The number of bonds is increased by the segmental orientation of the complex backbone in the shear field. Furthermore, the extent of viscosity enhancement is a direct function of the amount of charge density, the molecular weight of the individual copolymer, and the complex concentration. An increase in any of these factors will significantly enhance the viscosity-shear rate profile. These types of polymeric materials can be useful as dilatant agents in various well control and workover fluids. Other application areas include digestion, drag reduction, hydraulic fluids, enhanced oil recovery, anti-misting applications and a host of systems involving aqueous solutions. Example 9 Drag reduction was evaluated by flowing an aqueous solution through a stainless steel tube with an inner diameter of 2.13 mm and measuring the resulting pressure drop due to friction. The solvent was distilled water. Flow was generated by loading a pair of stainless steel tanks (one each) with a pre-dissolved aqueous polymer solution, pressurizing the tanks with nitrogen gas (300 kPa), and discharging the solution from the tube test section. . The pressure drop was measured across a 48 cm straight segment of tubing having a pair of wall pressure taps and a differential pressure transmitter. The flow rate was determined by weighing a sample of the effluent collected during the measurement period. The flow rate in the drag reduction experiment was in the range of 10-24 g/s, which corresponds to a solvent Reynolds number of 6500-15000 (solvent Reynolds number = average flow rate x tube diameter x kinematic viscosity of the solvent). Drag reduction is due to polymer/
The pressure drop of the xylene solution was measured compared to the pressure drop of the xylene solvent at equal flow rates. Results were expressed as % drag reduction defined as below. % Drag Reduction = Pressure Drop (Solvent) - Pressure Drop (Solution) Pressure Drop (Solvent) x 100 Typical drag reductions from experiments with interpolymer complexes and their individual anionic and cationic components are given in Table 6. show.

【table】

TABLE The data show that while drag reduction is seen with all solutions, the effectiveness of drag reduction is improved by forming the interpolymer complex. The high molecular weight copolymer materials used in this study appear to be useful as a special example of a general phenomenon.
That is, the presence in the polymer chain of a single monomer consisting of a wide group of water-soluble anionic and cationic moieties is a necessary condition for drag reduction in water solubility. Stoichiometry of these opposing charge units is not a prerequisite for effective drag reduction of these solutions. Furthermore, the acrylamide monomer units present within the copolymer structure are
This is just one example of the many water-soluble or water-dispersible monomer structures that can be used.

Claims (1)

[Scope of Claims] 1 (a) A copolymer of an acrylamide monomer and an anionic comonomer, the copolymer comprising from 1 to 50% by weight of repeating units corresponding to the anionic comonomer, based on the total weight of the copolymer; (b) a copolymer of an acrylamide monomer and a cationic comonomer comprising from 1 to 50% by weight, based on the total weight of the copolymer, of repeating units corresponding to the cationic comonomer, and The ratio of anionic functional group/cationic functional group is 45/1 ~
An aqueous polymer complex solution characterized in that the ratio is 1.1/1 or in the range of 1/45 to 1/1.1. 2 (a) the cationic comonomer is selected from the group of α,β ethylenically unsaturated monomers having a quaternary base or vinylpyridine as a functional group, and (b) the anionic comonomer is selected from the group of α,β ethylenically unsaturated monomers having a quaternary base or vinylpyridine as a functional group, and (b) the anionic comonomer is Claim 1, characterized in that the monomer is selected from α, β ethylenically unsaturated monomers having a sulfonic acid functional group, a carboxylic acid functional group, or a sulfonic acid functional group attached as a salt in the side chain of the monomer. Polymer complex aqueous solution as described. 3. The aqueous polymer complex solution according to claim 1, characterized in that it has a salt concentration of at least 0.01 molar.