JP5334157B2 - Block copolymer, viscosity modifier and coagulant aid - Google Patents

Description

The present invention relates to a block copolymer having a novel structure. In addition, the present invention improves the function of the coagulation aid of the polymer coagulant, that is, the polymer coagulant in the water treatment or paper industry, etc., comprising the viscosity control agent comprising the block copolymer, and also the viscosity control agent. The present invention relates to an agglomeration aid that is a drug having a function of causing the aggregation.

Ionic water-soluble copolymers are used in various industrial fields including viscosity modifiers, flocculants, and papermaking additives. In such a field, from the viewpoint of industrial production, the copolymer usually has a random structure. In recent years, living radical polymerization techniques have been developed, and it has become possible to synthesize block-shaped water-soluble copolymers. There are various reports on diblock polymers and triblock polymers. Among these, as for the triblock polymer, N, N-dimethylacrylamide-block-N-isopropylacrylamide-block-N, N-dimethylacrylamide is reported in Non-Patent Document 1, for example. Non-Patent Document 2 reports triblock polymers such as styrene-block-2-dimethylaminoethyl methacrylate-block-styrene and n-butyl methacrylate-block-2-dimethylaminoethyl methacrylate-block-n-butyl methacrylate. Has been. Non-Patent Document 3 reports styrene-block-N-isopropylacrylamide-block-styrene. However, the block copolymer of the present invention is not known for those having the same ionic block portion near both ends and the nonionic hydrophilic block portion near the center, and Its viscosity control function, coagulation function, and other general functions have not been clarified.

Viscosity modifiers are used in various industries to achieve thickening, flow control, and other properties in aqueous systems. A number of viscosity modifiers are commercially available for this purpose, such as sodium carboxymethylcellulose, guar gum, sodium alginate, hydroxyethylcellulose and the like. However, the viscosity of the aqueous system after adding these viscosity modifiers is usually a value expected from the viscosity of the viscosity modifier itself, and no dramatic increase in viscosity is manifested. Further, when increasing the viscosity of an aqueous solution system containing an ionic polymer, a polymer having an opposite charge usually does not exhibit a sufficient effect because it forms an insoluble complex and precipitates. Patent Document 1 discloses a method for increasing the viscosity of an aqueous anionic polymer system, but the types of anionic polymers are limited to special ones derived from natural products. Thus, a sufficient method for dramatically increasing the viscosity of a general ionic polymer solution is not known.

JP-T-2002-514673 Macromolecules, 2006, 39, 1724 Macromolecules, 2007, 40, 5575. Macromolecules, 2007, 40, 5827

The first object of the present invention is to provide a block copolymer which is industrially useful and has a novel structure. The second object of the present invention is to provide a viscosity modifier that dramatically increases the viscosity of an aqueous ionic polymer solution, and a coagulation aid that improves the coagulation function of the polymer coagulant.

An ionic group obtained by reversible addition-fragmentation chain transfer polymerization (hereinafter abbreviated as RAFT polymerization) has substantially ionic groups only at both end regions, and the central portion is substantially nonionic. It has been found that a specific block copolymer is useful for modifying the properties of an aqueous ionic polymer system. More specifically, with respect to the aqueous ionic polymer solution system, a block copolymer having a charge opposite to that of the ionic polymer in both end regions and having substantially no charge in the central portion is precipitated. It has been found that it has an excellent viscosity increasing effect without producing a product. Further, the present inventors have found that a block copolymer having such a structure dramatically improves the aggregating function and the like of the ionic polymer, leading to the present invention.

When the number of moles of monomer A with an ionic a, the number of moles of non-ionic hydrophilic monomer C c, the number of moles of monomer D with ionic was d,
c ≧ (a + d),
0.01 ≦ a / (a + c + d),
0.01 ≦ d / (a + c + d)
In the copolymer of monomers A , C and D satisfying
(1) The first polymerization is carried out in water in the presence of the ionic monomer A, the RAFT polymerization chain transfer agent and the polymerization initiator.
(2) The second polymerization is carried out by adding the nonionic hydrophilic monomer C and the polymerization initiator to the reaction product of (1), and after completion of the reaction,
(3) a third polymerization, (2) a first polymerization monomer D及 beauty polymerization initiator blocky copolymer was obtained conducted by adding with the same ionic to the reaction product of However, it has been found that it has an excellent viscosity-increasing effect on an ionic polymer aqueous solution system having an ionicity opposite to that of the block copolymer and significantly improves the aggregation effect. . Here, the RAFT polymerization chain transfer agent means a chain transfer agent used when RAFT polymerization is performed.

The block copolymer of the present invention forms a complex with the ionic polymer in the aqueous ionic polymer solution by adding a small amount, and the properties of the aqueous ionic polymer solution can be changed. Specifically, the viscosity of the aqueous ionic polymer solution can be dramatically increased. As a result, it can be used as a viscosity modifier in aqueous systems in various industries, and it can be expected to improve the cohesiveness of the polymer coagulant and improve the effect of the ionic polymer additive in the papermaking field.

The synthesis of the block copolymer of the present invention can be carried out by RAFT polymerization. Hereinafter, the method for obtaining the block copolymer of the present invention will be described in detail.

RAFT polymerization is carried out by adding a RAFT polymerization chain transfer agent to a normal radical polymerization reaction system. Usually, a RAFT polymerization chain transfer agent containing a dithioester group, a trithiocarbonate group or the like is used. Of these, water-soluble ones are preferred, and examples thereof include 4-cyanopentanoic acid dithiobenzoate, S-Ethyl-S ′-(α, α′-dimethyl-α “-acetic acid) -trithiocarbonate. In addition to these, it is also possible to use bisdithioesters and bistrithiocarbonates.

For the initiation of polymerization, a radical polymerization initiator is used. These initiators are preferably water-soluble and can be polymerized in any of azo, redox and peroxide systems. Examples of water-soluble azo initiators include 2,2′-azobis (2-methylpropionamidine) dichloride, 2,2′-azobis [2- (2-imidazolin-2-yl) propane] And hydrogen chloride, 4,4′-azobis (4-cyanovaleric acid), and the like. Examples of redox systems include a combination of ammonium persulfate and sodium sulfite, sodium hydrogen sulfite, trimethylamine, tetramethylethylenediamine and the like. Further, examples of peroxides include ammonium or potassium persulfate, hydrogen peroxide, and the like. Of these, water-soluble azo initiators are preferred.

  The polymerization conditions are usually appropriately determined according to the monomer used, the polymerization initiator, and the like. As temperature, it carries out in the range of 0-100 degreeC. The polymerization is usually carried out in three stages. During the first stage polymerization, the ionic monomer (mixture) is polymerized. The ionic monomer (mixture) may be a single type, a mixture of a plurality of ionic monomers having the same ionicity, or a plurality of ions having the same ionicity. It may be a mixture of an ionic monomer and a plurality of types of nonionic hydrophilic monomers. A chain transfer agent and a polymerization initiator are added to the aqueous ionic monomer (mixture) solution, and the system is sufficiently purged with nitrogen to start the first polymerization. The polymerization time is about 1 to 30 hours. If necessary, it is preferable to adjust the pH by adding hydrochloric acid or the like. The amount of the chain transfer agent is about 20 to 20000 ppm based on the polymerizable monomer used throughout the entire polymerization. If it is less than this, the progress of the polymerization is slow, and if it is more than this range, the molecular weight of the resulting polymer becomes too small. The amount of the polymerization initiator is about 5 to 100% with respect to the chain transfer agent. After the first polymerization is sufficiently completed, a second nonionic hydrophilic monomer is added, a polymerization initiator is further added, and after the system is sufficiently purged with nitrogen, the second polymerization is started. The polymerization time is about 1 to 30 hours. The amount of the polymerization initiator is about 5 to 100% with respect to the amount of the chain transfer agent added during the first polymerization. After the second polymerization is sufficiently completed, a third monomer (mixture) is added, a polymerization initiator is further added, and after the system is sufficiently purged with nitrogen, the third polymerization is started. The polymerization time is about 1 to 30 hours. The amount of the polymerization initiator is about 5 to 100% with respect to the amount of the chain transfer agent added during the first polymerization. Although there is no restriction | limiting in particular in the whole quantity of a polymerizable monomer, About 5 to 30% of the whole is preferable if the viscosity and economical efficiency of the finally produced aqueous solution are considered. After the first and second polymerizations, it is possible to remove unreacted monomers by a dialysis method, a precipitation method, an extraction method or the like.

Kicking the present invention blocky copolymer, the monomer A having ion-resistant, the first polymerization was carried out in the presence of sewage RAFT chain transfer agent and a polymerization initiator, followed by non-ionic hydrophilic The second polymerization is carried out by adding the polymerizable monomer C and the polymerization initiator, and further the third polymerization is carried out by adding the monomer D having the same ionicity as the first polymerization and the polymerization initiator. can get. Here, A and D are both cationic monomers (mixtures) or both anionic monomers (mixtures) and may be a mixture of different types of monomers as long as they are ionic. A and D may be the same type of polymerizable monomer, or may be composed of different types of polymerizable monomers as long as they are of the same ionicity. C consists of a nonionic hydrophilic monomer (mixture), and may be a mixture of different kinds of nonionic hydrophilic monomers. A small amount of ionic monomer may be included so that the formation of the complex is not suppressed.

In the copolymer of the present invention, the amount of monomers constituting A and D needs to be 1 mol% or more based on the total amount of monomers. If the amount is less than this, the ability to form a polymer electrolyte complex is lowered. In the monomers in the first polymerization and the third polymerization, 0 ≦ (number of moles of monomer constituting B / number of moles of monomer constituting A) ≦ 2, 0 ≦ (E The number of moles of monomer constituting / the number of moles of monomer constituting D) ≦ 2. When these numbers are larger than 2, the ability to form a polymer electrolyte complex is lowered. Further, the central nonionic part of the block copolymer of the present invention satisfies the number of moles of monomers constituting C ≧ (sum of the number of moles of monomers constituting A, B, D, E). There is a need. When this is not satisfied, the behavior becomes close to that of a random copolymer, an insoluble precipitate is easily generated, and an effective polyelectrolyte complex is not formed.

Examples of the anionic monomer include (meth) acrylic acid, itaconic acid, maleic acid, styrene sulfonic acid, acrylamide 2-methylpropane sulfonic acid, and salts thereof. Of these, acrylic acid and its salts are more preferred.

Among the cationic monomers, examples of tertiary amino group-containing cationic monomers include dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide, and diethylaminopropyl. (Meth) acrylamide and salts thereof may be mentioned. Examples of quaternary ammonium base-containing cationic monomers include (meth) acryloyloxyethyltrimethylammonium chloride, (meth) acryloyloxyethyldimethylbenzylammonium chloride, (meth) acryloylaminopropyltrimethylammonium chloride, (meth) acryloyl. Examples thereof include aminopropyldimethylbenzylammonium chloride, (meth) acryloyloxy 2-hydroxypropyltrimethylammonium chloride, diallyldimethylammonium chloride and the like. Examples of the primary amine include allylamine, and examples of the secondary amine include diallylmethylamine.

Examples of nonionic hydrophilic monomers are (meth) acrylamide, dimethylacrylamide, diethylacrylamide, isopropylacrylamide, hydroxyethylacrylamide, vinylpyrrolidone, vinylformamide, vinylacetamide, glycerol (meth) acrylate, hydroxyethyl (meth) An acrylate etc. are mentioned. Acrylamide is more preferable because of ease of polymerization.

The amount of the ionic monomer used during the first polymerization and the third polymerization needs to be 1 mol% or more based on the total amount of monomers. If it is less than this, the formation of the complex with the ionic polymer becomes insufficient. The amount of the monomer (mixture) used in the second polymerization is the number of moles of the monomer (mixture) used in the first polymerization and the monomer used in the third polymerization. It is made to become more than the sum of the number of moles of (mixture). If it is less than this, the formation of the complex will be insufficient. The types of ionic monomers in the first and third polymerizations may be different as long as they are the same ionic. The molecular weight of the finally obtained copolymer is about 5,000 to 3,000,000, more preferably about 10,000 to 3,000,000. If it is smaller than this, the formation of the composite is insufficient and the effect of increasing the viscosity becomes small. In order to obtain a molecular weight larger than this, it is necessary to reduce the addition amount of the RAFT polymerization chain transfer agent and the polymerization initiator. In this case, however, problems such as a long time for polymerization occur. In addition, the viscosity of the copolymer itself becomes large and handling becomes difficult. The molecular weight can be controlled by the amount of RAFT polymerization chain transfer agent.

When the viscosity of the ionic polymer aqueous solution is improved, the addition amount of the block copolymer of the present invention is preferably 1 to 70% by mass with respect to the ionic polymer in the ionic polymer aqueous solution. More preferably, it is -50 mass%. When it is smaller or larger than this range, the bridging effect is lowered and the viscosity increasing effect is insufficient.

Taking as an example the case where a block copolymer having an anionic moiety at both ends is added to the cationic polymer aqueous solution, the mechanism of viscosity increase can be considered as follows. That is, the anionic portion present at both ends interacts ionicly with the cationic polymer to form a polymer electrolyte complex. Since the central part does not form a complex with the cationic polymer, it exists freely in the aqueous solution, so the anionic part at the other end interacts with other cationic polymers, and the polymer electrolyte is crosslinked between the molecules. Complexes are easily formed. Thus, it is considered that the viscosity of the entire system is drastically increased because a complex having an apparently large molecular weight is formed.

When the aqueous ionic polymer solution is used as a flocculant in the water treatment industry, a chemical in the paper industry, etc., by adding the block copolymer of the present invention in advance and increasing the viscosity, The effect can be greatly improved.

(Example)
EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not restrict | limited to a following example, unless the summary is exceeded.

  To a four-necked 300 ml separable flask equipped with a stirrer, reflux condenser, and nitrogen inlet tube was added 1.67 g of 60% aqueous acrylic acid solution, 12.0 g of 1N-NaOH, and 0.005 g of 4-cyanopentanoic acid dithiobenzoate. A mixed solution. While maintaining the temperature at 20 ° C., nitrogen was introduced from the nitrogen introduction tube while stirring, and the system was purged with nitrogen. Next, 0.1 g of 1% 2,2′-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride aqueous solution was added, and the flask was heated to a temperature of 50 ° C. The first polymerization was started. The first polymerization reaction was completed after 8 hours. After cooling to room temperature, 16 g of 50% aqueous acrylamide solution, 18.4 g of deionized water, 1% 2,2′-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride aqueous solution 0.1 g And heated to a temperature of 50 ° C. to initiate the second polymerization. After 16 hours, the second polymerization reaction was completed. After cooling to room temperature, 1.67 g of 60% aqueous acrylic acid solution, 50 g of deionized water, 1 g of 2,2′-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride aqueous solution 0.1 g The third polymerization was started by adding and heating to a temperature of 50 ° C. The third polymerization was terminated after 22 hours. When the molecular weight of the polymer obtained by GPC-MALS was measured, it showed a weight average molecular weight of 1,400,000. This is referred to as block copolymer 1.

A methacryloyloxyethyltrimethylammonium chloride homopolymer (p-MMCQ, weight average molecular weight of 900,000 by MALS) was dissolved in deionized water to 1%. As a result of measurement using a Brookfield viscometer with a rotation speed of 60 rpm and a No. 2 rotor, the viscosity was 12 mPa · s (25 ° C., the same applies hereinafter). The block copolymer 1 of Example 1 was dissolved in deionized water to 1%. The viscosity was 90 mPa · s. The viscosity of the 0.2% block copolymer 1 aqueous solution was 5.0 mPa · s. Table 1 shows the results of mixing 1% p-MMCQ aqueous solution with 1% block copolymer 1 aqueous solution and measuring the viscosity. The viscosity was measured using a Brookfield viscometer with a No. 2 rotor at 60 rpm. It was confirmed that the addition of the block copolymer 1 significantly increases the viscosity.

(Table 1)

Acryloyloxyethyldimethylbenzylammonium chloride (p-ABCQ, weight average molecular weight of 1,400,000 by MALS) was dissolved in deionized water to 1%. The viscosity was 30 mPa · s as a result of measurement with a No. 2 rotor at a rotation speed of 60 rpm using a Brookfield viscometer. The block copolymer 1 of Example 1 was dissolved in deionized water to 1%. The viscosity was 90 mPa · s. The viscosity of the 0.2% block copolymer 1 aqueous solution was 5.0 mPa · s. Table 2 shows the results of mixing 1% p-ABCQ aqueous solution and 1% block copolymer 1 aqueous solution and measuring the viscosity. The viscosity was measured using a Brookfield viscometer with a No. 2 rotor at 60 rpm. It was confirmed that the addition of the block copolymer 1 significantly increases the viscosity.

(Table 2)

Polyamidine (weight average molecular weight of 500,000 by MALS) was dissolved in deionized water to 5%. The viscosity was 15.5 mPa · s as a result of measuring with a Brookfield viscometer using a No. 2 rotor at 60 rpm. The block copolymer 1 of Example 1 was dissolved in deionized water to 1%. The viscosity was 90 mPa · s. The viscosity of the 0.2% block copolymer 1 aqueous solution was 5.0 mPa · s. Table 3 shows the results of mixing the 5% polyamidine aqueous solution and the 1% block copolymer 1 aqueous solution and measuring the viscosity. The viscosity was measured using a Brookfield viscometer with a No. 2 rotor at 60 rpm. It was confirmed that the addition of the block copolymer 1 significantly increases the viscosity.

(Table 3)

An aqueous silica solution having a concentration of 4% was prepared, and 250 ml was used as a test solution, and an agglomeration test was performed using a Flocky tester (ODA-10-W95 manufactured by Koei Kogyo Co., Ltd.). In the Flocky tester, the cohesive strength is obtained as a voltage output value. FIG. 1 shows the result of measuring the floc strength by adding 5 ml each of the cationic polymer pMMCQ (1%) aqueous solution and pMMCQ (0.9%) + block copolymer 1 (0.1%) aqueous solution. . The voltage output value of the 4% silica aqueous solution was 1000. When the cationic polymer and the block copolymer 1 were mixed and the viscosity-adjusted one was added, the strength increased about twice as much as when only the cationic polymer was added.

(Fig. 1) Analysis of cohesive strength by Flocky tester

(Comparative Example 1)
In a four-neck 300 ml separable flask equipped with a stirrer, reflux condenser, and nitrogen inlet tube, 3.4% 60% acrylic acid aqueous solution, 12.0 g 1N-NaOH, 16.0 g 50% aqueous acrylamide solution, 67.7 g deionized water Was added to obtain a uniform mixed solution. While maintaining the temperature at 20 ° C., nitrogen was introduced from the nitrogen introduction tube while stirring, and the system was purged with nitrogen. Next, 1.0 g of 1% 2,2′-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride aqueous solution was added, and the flask was heated to a temperature of 50 ° C. to polymerize. Was started. The polymerization was terminated after 10 hours.
When the molecular weight of the polymer obtained by GPC-MALS was measured, it showed a weight average molecular weight of 800,000. This is random copolymer 1

(Comparative Example 2)
A methacryloyloxyethyltrimethylammonium chloride homopolymer (p-MMCQ, weight average molecular weight of 900,000 by MALS) was dissolved in deionized water to 1%. As a result of measuring with a Brookfield viscometer using a No. 2 rotor at 60 rpm, the viscosity was 12 mPa · s. Random copolymer 1 of Comparative Example 1 was dissolved in deionized water to 1%. The viscosity was 51 mPa · s. Table 4 shows the results of mixing 1% p-MMCQ aqueous solution and 1% random copolymer 1 aqueous solution and measuring the viscosity. The viscosity was measured using a Brookfield viscometer with a No. 2 rotor at 60 rpm. In the case of the random copolymer 1, a precipitate was generated and the effect of increasing the viscosity was insufficient.

(Table 4)

Claims (6)

When the number of moles of monomer A with an ionic a, the number of moles of non-ionic hydrophilic monomer C c, the number of moles of monomer D with ionic was d,
c ≧ (a + d),
0.01 ≦ a / (a + c + d),
0.01 ≦ d / (a + c + d)
In the copolymer of monomers A , C and D satisfying
(1) The first polymerization is carried out in water in the presence of the ionic monomer A, the RAFT polymerization chain transfer agent and the polymerization initiator.
(2) The second polymerization is carried out by adding the nonionic hydrophilic monomer C and the polymerization initiator to the reaction product of (1), and after completion of the reaction,
(3) a third polymerization, (2) a first polymerization monomer D及 beauty polymerization initiator blocky copolymer was obtained conducted by adding with the same ionic to the reaction product of The ionic monomers are dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide, diethylaminopropyl (meth) acrylamide, and their Salt, (meth) acryloyloxyethyltrimethylammonium chloride, (meth) acryloyloxyethyldimethylbenzylammonium chloride, (meth) acryloylaminopropyltrimethylammonium chloride, (meth) acryloylaminopropyldimethylbenzylammonium chloride, (meth) acryloyloxy -Selected from hydroxypropyltrimethylammonium chloride, diallyldimethylammonium chloride, allylamine, diallylmethylamine, (meth) acrylic acid, itaconic acid, maleic acid, styrenesulfonic acid, acrylamide 2-methylpropanesulfonic acid, and salts thereof The nonionic hydrophilic monomer is (meth) acrylamide, dimethylacrylamide, diethylacrylamide, isopropylacrylamide, hydroxyethylacrylamide, vinylpyrrolidone, vinylformamide, vinylacetamide, glycerol (meth) acrylate, hydroxyethyl A block copolymer, which is a kind selected from (meth) acrylates . The block copolymer according to claim 1, having a weight average molecular weight of 5,000 to 3,000,000. The block copolymer according to claim 1, wherein the monomer is a vinyl monomer. The block copolymer according to any one of claims 1 to 3 , wherein A and D are acrylic acid (salt) and C is acrylamide. The viscosity regulator which consists of a block-shaped copolymer of any one of Claims 1-4 . An aggregation aid comprising the block copolymer according to any one of claims 1 to 4 .