JP6924942B2 - New polymers and their manufacturing methods - Google Patents

Description

The present invention relates to novel polymers, methods for producing them, and their use as dispersants.

Particle-dispersed compositions such as paints, printing inks, and cosmetics are highly functional and diversified in required functions and performances, and technical issues for stable dispersion of objects to be dispersed are also increasing. For example, as the particles are made finer, the performance and properties that the particles themselves originally have can be fully brought out. Since the crushed surface of the particles is highly active, the tendency to reaggregate increases. Therefore, sufficient dispersibility cannot be obtained in many cases, and a dispersant is required.

The dispersant needs to be adsorptive and stable in the process of forming the dispersion. The dispersant has a structure of a hydrophilic part and a lipophilic part, and the performance of the dispersant is determined by the balance of these two functional parts. Hydrophilic sites can be nonionic or ionic, and by giving them charge or steric hindrance, they prevent reaggregation of particles and stabilize the dispersion. Nonionic, the particles are stabilized by a polymer with a water-soluble, hydrophilic moiety that spreads into the water and provides entropy or steric stabilization. In ionicity, the particles are stabilized by a charged double layer mechanism by anionic or cationic ions, and ionic repulsion prevents particle aggregation. Examples of the anionic hydrophilic group include a carboxyl group, a sulfonic acid group and a sulfate ester group, and examples of the cationic hydrophilic group include an amine salt type and a quaternary ammonium salt type.

Most pigments can be roughly divided into inorganic pigments having polar functional groups such as acids and bases on the surface and organic pigments having a generally non-polar surface. In general, the property of the dispersant to be oriented and adsorbed on the interface depends on the balance (polarity) of hydrophobic and hydrophilic groups in the molecule, but in addition to this, acid-base interaction with the pigment surface and nonionic Interactions need to be considered.

There is a need for polymer dispersants that can produce both steric and charged double layer stabilizing forces in addition to adsorptivity.

For example, as a polymer dispersant, Patent Document 1 describes a method of using a block polymer containing a sulfonic acid group as an acidic group and a solvent-soluble chain as a pigment dispersant.

Patent Document 2 describes that a polymer containing a carboxylate having an adsorptive ability on the particle surface and a nonionic ethylene oxide moiety is stereochemically dispersed to prevent aggregation.

Further, Patent Document 3 describes a polymer dispersant composed of an acidic monomer containing a carboxyl group, a nonionic monomer, and a hydrophobic monomer.

Japanese Patent No. 5652961 Special Table No. 2013-517133 Japanese Patent No. 5557555

An object of the present invention is to provide a dispersant capable of forming a dispersion having stable dispersibility.

As a result of diligent research to solve the above problems, the present inventors have found that a specific block copolymer has excellent dispersibility, and have completed the following invention.

(1) A block copolymer obtained by polymerizing copolymer A, monomer B, and monomer C.
Copolymer A: A compound having the following structures a and b.
a: Hydrophilic block having a polyalkylene glycol chain having 2 to 3 carbon atoms b: Functional group monomer contributing to the polymerization reaction B: A compound represented by the following general formula (1).
R _1- R _2- SO ₃ ^- X ⁺ (1)
(In the formula, R ₁ is a functional group having a polymerizable unsaturated group, R ₂ is a hydrocarbon group having 1 to 8 carbon atoms, and X ⁺ is a proton, a metal cation, or an ammonium ion.)
Monomer C: A compound represented by the following general formula (2).
R _4- R ₅ (2)
(In the formula, R ₄ represents a functional group having a polymerizable unsaturated group, and R ₅ represents a hydrocarbon group having 4 to 22 carbon atoms.)
(2) Block common weight obtained by polymerizing monomer B and monomer C on a copolymer A having the following structure a: general formula (3) and structure b: general formula (4). Combined.
Monomer B: A compound represented by the following general formula (1).
R _1- R _2- SO ₃ ^- X ⁺ (1)
(In the formula, R ₁ is a functional group having a polymerizable unsaturated group, R ₂ is a hydrocarbon group having 1 to 8 carbon atoms, and X ⁺ is a proton, a metal cation, or an ammonium ion.)
Monomer C: A compound represented by the following general formula (2).
R _4- R ₅ (2)
(In the formula, R ₄ represents a functional group having a polymerizable unsaturated group, and R ₅ represents a hydrocarbon group having 4 to 22 carbon atoms.)

（＊は構造ｂとの結合部位であり、ｘは２又は３の整数であり、ｙは（重合数−１）であり、ｚは１又は２の整数である。）

(* Is the binding site with the structure b, x is an integer of 2 or 3, y is (polymerization number -1), and z is an integer of 1 or 2.)

（＊は構造ａとの結合部位であり、Ｚは置換もしくは無置換のアリール基、置換もしくは無置換のチオアリール基、置換もしくは無置換のチオアルキル基、置換もしくは無置換のアミノ基、置換もしくは無置換のオキシアリール基、または置換もしくは無置換のオキシアルキル基である。Ｒは、下記式（５）、（６）で表されるいずれかの基を示す。）

(* Is the bonding site with the structure a, Z is a substituted or unsubstituted aryl group, a substituted or unsubstituted thioaryl group, a substituted or unsubstituted thioalkyl group, a substituted or unsubstituted amino group, a substituted or unsubstituted. The oxyaryl group of the above, or a substituted or unsubstituted oxyalkyl group. R represents any of the groups represented by the following formulas (5) and (6).)

（式中、＊は他の部位との結合部であることを表す。）

(In the formula, * indicates that it is a joint with another part.)

(3) Monomer B and monomer C are polymerized on the copolymer A obtained by polymerizing the compound α represented by the general formula (7) and the compound β represented by the general formula (8). The resulting block copolymer.
Monomer B: A compound represented by the following general formula (1).
R _1- R _2- SO ₃ ^- X ⁺ (1)
(In the formula, R ₁ is a functional group having a polymerizable unsaturated group, R ₂ is a hydrocarbon group having 1 to 8 carbon atoms, and X ⁺ is a proton, a metal cation, or an ammonium ion.)
Monomer C: A compound represented by the following general formula (2).
R _4- R ₅ (2)
(In the formula, R ₄ represents a functional group having a polymerizable unsaturated group, and R ₅ represents a hydrocarbon group having 4 to 22 carbon atoms.)

（ｘは２又は３の整数であり、ｙは（重合数−１）であり、ｚは１又は２の整数である。）

(X is an integer of 2 or 3, y is (polymerization number-1), and z is an integer of 1 or 2.)

（式中、Ｚ及びＲは上記一般式（４）に同じである。）

(In the formula, Z and R are the same as the above general formula (4).)

(4) The method for producing a copolymer according to (1) or (2).
(A) A step of polymerizing the copolymer A and the monomer B to obtain a block copolymer AB,
(B) Step of polymerizing block copolymer AB and monomer C,
Manufacturing method including.
(5) The method for producing a copolymer according to (3).
(A) Step of obtaining copolymer A from the compound α and the compound β (b) Step of obtaining a block copolymer AB by polymerizing the obtained copolymer A and the monomer B (c) Obtaining A production method including a step of polymerizing the obtained copolymer AB and the monomer C.
(6) A dispersant containing the block copolymer according to any one of (1) to (5).

The block copolymer of the present invention has three components, a hydrophilic nonionic block, a block having a high ability to adsorb ions with a cationic substance, and a hydrophobic block, and can act as an excellent dispersant. can.

^{It is 1} H-NMR spectrum of the copolymer AB of Example 1-1. It is a GPC chart of the copolymer AB of Example 1-1. ¹ H-NMR spectrum of the copolymer of the present invention of Example 2-1. It is a spectrum of the particle size distribution measurement of Example 3-1. It is a drawing substitute photograph which shows the state of the dispersion of Example 3-1.

The block copolymer of the present invention is a compound obtained by polymerizing copolymer A, monomer B, and monomer C.

The copolymer A used in the present invention has a structure represented by the following a and b.
a: Hydrophilic block having a polyalkylene glycol chain having 2 to 3 carbon atoms b: Functional group contributing to the polymerization reaction

a has a structure having a polyalkylene glycol chain obtained by polymerizing a polyalkylene glycol having 2 or 3 carbon atoms represented by the following general formula (3), and may have a substituent. Examples of the polyalkylene glycol include ethylene glycol and propylene glycol, but ethylene glycol is preferable. The number of polymerizations is 1 to 11000, preferably 10 to 1000.

（＊は構造ｂとの結合部位であり、ｘは２又は３の整数であり、ｙは（重合数−１）であり、ｚは１又は２の整数である。）

(* Is the binding site with the structure b, x is an integer of 2 or 3, y is (polymerization number -1), and z is an integer of 1 or 2.)

b may be a functional group that contributes to the polymerization reaction, and is preferably a functional group that has a function as a chain transfer agent in living radical polymerization represented by the following general formula (4).

（＊は構造ａとの結合部位であり、Ｚは置換もしくは無置換のアリール基、置換もしくは無置換のチオアリール基、置換もしくは無置換のチオアルキル基、置換もしくは無置換のアミノ基、置換もしくは無置換のオキシアリール基、または置換もしくは無置換のオキシアルキル基である。Ｒは、下記式（５）、（６）で表されるいずれかの基を示す。）

(* Is the bonding site with the structure a, Z is a substituted or unsubstituted aryl group, a substituted or unsubstituted thioaryl group, a substituted or unsubstituted thioalkyl group, a substituted or unsubstituted amino group, a substituted or unsubstituted. The oxyaryl group of the above, or a substituted or unsubstituted oxyalkyl group. R represents any of the groups represented by the following formulas (5) and (6).)

（式中、＊は他の部位との結合部であることを表す。）

(In the formula, * indicates that it is a joint with another part.)

The copolymer A can be obtained by reacting the compound α represented by the following general formula (7) and the compound β represented by the following general formula (8) by a known means, and is also macro-chained by Aldrich. It can also be purchased as a transfer agent. For example, poly (ethylene glycol) methyl ether (4-cyano-4-pentanoate dodecyltrithiocarbonate (manufactured by Aldrich)), poly (ethylene glycol) methyl ether (4-cyano-4- (dodecylsulfanylthiocarbonyl) sulfanyl). ) Pentanoate (manufactured by Aldrich), Poly (ethylene glycol) Methyl ether (2-methyl2-propionic acid dodecyltrithiocarbonate (manufactured by Aldrich), Poly (ethylene glycol) 4-cyano-4-phenylcarbonoti oil Tio) pentanoate (manufactured by Aldrich) and the like, preferably poly (ethylene glycol) methyl ether (4-cyano-4-pentanoate dodecyltrithiocarbonate (manufactured by Aldrich)).

In compound β, Z is a group that controls the reactivity of the C = S bond and affects the radical reaction rate, and R is a group that can dissociate and generate free radicals. For example, thiocarbonithio compounds such as dithiobenzoate, dithiocarbamate, trithiocarbonate, and xantate can be mentioned. As the compound β, a commercially available compound may be used, and dithiobenzoate and trithiocarbonate are preferable in that they are suitable for the polymerization of monomers B and C, and 4-cyano-4- (phenylcarbonothio oilthio) penta. Neuc Acid (manufactured by Aldrich), 4-Cyano-4- (Dodecylsulfanylthiocarbonyl Sulfanylpentanoic Acid (manufactured by Aldrich), 2- (Dodecylthiocarbonotioilthio) -2-methylpropionic acid (manufactured by Aldrich) Aldrich) is more preferred, and 4-cyano-4- (dodecylsulfanylthiocarbonylsulfanylpentanoic acid) is even more preferred.

（ｘは２又は３の整数であり、ｙは（重合数−１）であり、ｚは１又は２の整数である。）

(X is an integer of 2 or 3, y is (polymerization number-1), and z is an integer of 1 or 2.)

（式中、Ｚ及びＲは上記一般式（４）に同じである。）

(In the formula, Z and R are the same as the above general formula (4).)

The monomer B used in the present invention is represented by the following general formula (1).

R _1- R _2- SO ₃ ^- X ⁺ (1)
(In the formula, R ₁ is a functional group having a polymerizable unsaturated group, R ₂ is a hydrocarbon group having 1 to 8 carbon atoms, and X ⁺ is a proton, a metal cation or an ammonium ion.)

Examples of the _{functional group having a polymerizable unsaturated group of R 1} include a (meth) acrylic group, a (meth) acrylamide group, a vinyl group, and a styryl group. _{The preferred R 1} in the present invention is a (meth) acrylamide group.

The hydrocarbon group having 1 to 8 carbon atoms of R ₂ is not limited to the saturated hydrocarbon group, the unsaturated hydrocarbon group and the aromatic hydrocarbon group, but the saturated hydrocarbon group having 1 to 6 carbon atoms and the aromatic group. Hydrocarbon groups are preferable, and saturated hydrocarbon groups having 1 to 4 carbon atoms are particularly preferable.

Specific examples of X ⁺ include protons, metal cations and ammonium ions. It is preferably a proton or an alkali metal ion, and more preferably a sodium ion or a potassium ion.

The monomer B is preferably represented by the following general formula (9).

（式中、Ｒ_３は水素原子あるいはメチル基、その他は上記一般式（１）に同じである。）

(In the formula, R ₃ is a hydrogen atom or a methyl group, and the others are the same as the above general formula (1).)

The monomer C used in the present invention is represented by the following general formula (2).

R _4- R ₅ (2)
(In the formula, R ₄ represents a functional group having a polymerizable unsaturated group, and R ₅ represents a hydrocarbon group having 4 to 22 carbon atoms.)

Examples of the _{functional group having a polymerizable unsaturated group of R 4} include a (meth) acrylic group, a (meth) acrylamide group, a vinyl group, and a styryl group. Preferred R ₄ in the present invention is a vinyl group.

The hydrocarbon group having 4 to 22 carbon atoms of R ₅ is not limited to the saturated hydrocarbon group, the unsaturated hydrocarbon group and the aromatic hydrocarbon group, but the saturated hydrocarbon group having 4 to 16 carbon atoms and the aromatic hydrocarbon group. A hydrogen group is preferable, and an aromatic hydrocarbon group having 6 to 12 carbon atoms is particularly preferable.

The monomer C is preferably represented by the following general formula (10).

（式中、Ｒ_６は水素原子あるいはメチル基、Ｒ_７〜Ｒ_１１はいずれも独立して、水素又は炭素数１〜６の炭化水素基を示す。）

(In the formula, R ₆ represents a hydrogen atom or a methyl group, and R _{7 to} R ₁₁ independently represent a hydrogen or a hydrocarbon group having 1 to 6 carbon atoms.)

_{The hydrocarbon groups having 1 to 6 carbon atoms of R 7 to} R ₁₁ in the above general formula (10) are not limited to saturated hydrocarbon groups, unsaturated hydrocarbon groups and aromatic hydrocarbon groups, but have 1 carbon number. A saturated hydrocarbon group of ~ 2 is preferable.

The production method of the present invention has the following steps.
(A) Step of obtaining block copolymer AB by polymerizing commercially available copolymer A and monomer B (b) Step of polymerizing the obtained copolymer AB and monomer C of the present invention In addition to the above, the production method may have the following steps.
(A) Step of obtaining copolymer A from the compound α and the compound β (b) Step of obtaining a block copolymer AB by polymerizing the obtained copolymer A and the monomer B (c) Obtaining Step of polymerizing the obtained copolymer AB and monomer C

The polymerization means in the method for producing a block copolymer of the present invention is not particularly limited as long as it is a known means, and examples thereof include a living radical polymerization method.

The living radical polymerization method is a polymerization method that enables precise control of the molecular structure while maintaining the convenience and versatility of radical polymerization. The living radical polymerization method includes a method using a transition metal catalyst (ATRP method), a method using an organotellurium compound (TERP method), and a reversible chain transfer agent (RAFT agent), depending on the method for stabilizing the polymerization growth end. There are methods such as a method using the compound β (RAFT method). Among these, the RAFT polymerization method is preferable because a narrow molecular weight distribution can be easily obtained and polymerization can be easily controlled.

The block copolymer of the present invention is usually obtained by reacting 1 mol of the commercially available copolymer A with 10 mol to 1000 mol of the monomer B, for example, using the living radical polymerization method to obtain the copolymer AB. After the obtained product, it is obtained by reacting 1 mol of the obtained copolymer AB with 10 mol to 1000 mol of the monomer C, for example, by using the above-mentioned living radical polymerization method. After obtaining the copolymer AB, the copolymer AB may be isolated and purified by a known means, if necessary.

Alternatively, the block copolymer of the present invention is obtained by subjecting 1 mol of the above compound α to 0.1 mol to 10 mol of the compound β by an esterification reaction to obtain a copolymer A, and then a single amount with respect to 1 mol of the copolymer A. After reacting 10 mol to 1000 mol of body B with, for example, using the above-mentioned living radical polymerization method to obtain copolymer AB, 10 mol to 10 mol of monomer C is added to 1 mol of the obtained copolymer AB. It is obtained by reacting 1000 mol with, for example, using the above-mentioned living radical polymerization method. After obtaining the copolymer A or the copolymer AB, the copolymer A or the copolymer AB may be isolated and purified by a known means, if necessary.

In the present invention, a polymerization initiator may be used. The polymerization initiator is not particularly limited as long as it is an initiator capable of initiating radical polymerization, and can be appropriately selected depending on the intended purpose. For example, an azo-based polymerization initiator, a peroxide-based polymerization initiator, and the like. Examples thereof include a persulfate-based polymerization initiator. Examples of the azo-based polymerization initiator include 2,2'-azobis (isobutyric acid) dimethyl, 4,4'-azobis (4-cyanovaleric acid), and 2,2'-azobis (isobutyronitrile). Examples thereof include 2,2'-azobis (2,4-dimethylvaleronitrile). Examples of the peroxide-based polymerization initiator include benzoyl peroxide and the like. Examples of the persulfate-based polymerization initiator include potassium persulfate and ammonium persulfate. Of these, AIBN, 2,2'-azobis (2,4-dimethylvaleronitrile) is preferable because the operation proceeds smoothly. The amount of the radical polymerization initiator used is generally 0.01 to 1 mol, preferably 0.1 to 0.8 mol, relative to 1 mol of the RAFT agent.

The synthesis step can be carried out in a solvent. The solvent is not particularly limited as long as it is inert to the reaction, and can be appropriately selected depending on the intended purpose. For example, water, alcohol solvent, hydrocarbon solvent, ketone solvent, ester solvent, chloride. Examples include physical solvents, aromatic solvents, aprotonic polar solvents and the like. Examples of the alcohol solvent include methanol, ethanol, 1-propanol, isopropanol and the like. Examples of the hydrocarbon solvent include hexane, heptane, octane, decane, and liquid paraffin. Examples of the ketone solvent include acetone, methyl ethyl ketone and the like. Examples of the ester solvent include methyl acetate, ethyl acetate, butyl acetate and the like. Examples of the chloride-based solvent include methylene chloride, chloroform, carbon tetrachloride and the like. Examples of the aromatic solvent include benzene and toluene. Examples of the aprotic polar solvent include tetrahydrofuran, N, N-dimethylformamide, dimethyl sulfoxide and the like. As the solvent, a solvent having a boiling point higher than the radical generation temperature of the polymerization initiator is preferable. These solvents can be used alone or in combination of two or more. Among these, an alcohol solvent is preferable, and methanol is particularly preferable, because the desired product can be obtained in good yield.

The polymerization temperature in the synthesis step is not particularly limited and may be appropriately selected depending on the intended purpose, and is usually in the temperature range from 10 ° C. to the boiling point of the solvent used, preferably 40 to 100 ° C.

The polymerization time in the synthesis step is not particularly limited and may be appropriately selected depending on the intended purpose, and usually includes several minutes to several tens of hours, preferably 30 minutes to 90 hours, etc., depending on the reaction scale. ..

The synthesis step is preferably carried out in an inert atmosphere. Examples of the inert atmosphere include nitrogen, argon, helium and the like.

As described above, the block copolymer of the present invention composed of block A-block B-block C can be produced.

The content of A block in the block copolymer of the present invention is not particularly limited and may be appropriately selected depending on the intended purpose, but the content of A block is 0 in 100% mass of the entire block copolymer. It is preferably 0.01 to 90% by mass, more preferably 1 to 85% by mass, and even more preferably 5 to 30% by mass.

The content of B block in the block copolymer of the present invention is not particularly limited and may be appropriately selected depending on the intended purpose, but the content of B block is 0 in 100% mass of the entire block copolymer. It is preferably 0.01 to 90% by mass, more preferably 1 to 85% by mass, and even more preferably 30 to 80% by mass.

The content of C block in the block copolymer of the present invention is not particularly limited and may be appropriately selected depending on the intended purpose.

The content of C block is preferably 0.01 to 50% by mass, more preferably 1 to 40% by mass, and 5 to 30% by mass in 100% by mass of the entire block copolymer. Is even more preferable.

The weight average molecular weight (Mw) of the block copolymer obtained in the present invention is preferably 1000 to 200,000, more preferably 3,000 to 150,000, and even more preferably 5,000 to 100,000.

The molecular weight distribution (PDI) of the block copolymer is preferably less than 2.0, more preferably less than 1.7. In the present invention, PDI is determined by (weight average molecular weight (Mw) of block copolymer) / (number average molecular weight (Mn) of block copolymer), and the smaller the PDI, the more the molecular weight distribution. It becomes a copolymer having a narrow width and a uniform molecular weight, and when the value is 1.0, the width of the molecular weight distribution is the narrowest. On the contrary, the larger the PDI, the smaller the molecular weight and the larger the molecular weight of the designed polymer are included, which may deteriorate the dispersibility. This is because if the molecular weight is too small, the solubility in the dispersion medium is too high, and if the molecular weight is too large, the solubility in the dispersion becomes poor.

The obtained block copolymer of the present invention is a copolymer having three components: a hydrophilic nonionic block, an anionic block, and a hydrophobic block. Since it has a hydrophilic non-ionic block, it dissolves or dissolves in a solvent due to steric repulsion or electrical repulsion, and because it has an anionic sulfonic acid group, it has a strong ionic adsorption ability because it ionic bonds with a cationic substance. It also has a hydrophobic block, so it has an affinity with hydrophobic substances. Due to these properties, it can be used as a dispersant, an ion exchange resin, a precipitant or a chelating agent.

When the block copolymer of the present invention is used as a dispersant, the particles in the dispersion medium are given excellent dispersion stability, so that the block copolymer of the present invention can be used for conventionally known particles. Specific examples thereof include particles such as inkjet ink, color filter ink, gravure ink, paint, stationery ink, writing tool ink, and coating agent.

As the particle dispersion method, a conventionally known method can be applied and is not particularly limited. For example, it is obtained by mixing using a mixer such as an ultrasonic disperser, a paint shaker, a bead mill, a ball mill, a solver, a kneader, and a triple roll.

The method for measuring the dispersed particle size is not particularly limited, and can be measured by a dynamic light scattering method, a laser diffraction / scattering method, an image analysis method, a centrifugal sedimentation method, or the like. The manufacturer is not particularly limited, but the Microtrack UPA-EX150 manufactured by Nikkiso Co., Ltd. is preferable.

Hereinafter, the present invention will be described in more detail with reference to Examples. In the examples, parts mean parts by weight and% means% by weight.

Example 1-1
<Synthesis of PEG-b-PAMPS>
An aqueous solution of 2-acrylamide-2-methylpropanesulfonic acid (AMPS, 8.64 g, 0.0417 mol, manufactured by Wako Pure Chemical Industries, Ltd.) _{neutralized with NaHCO 3} (3.50 g, 0.0417 mol) in pure water. Was obtained (pH = 6.4, 10.6 mL). In a flask, the aqueous solution, chain transfer agent PEG _46- CTA (Mn = 2400, degree of polymerization (DP) = 46, 1.00 g, 0.417 mmol, manufactured by Ardrich), initiator AIBN (0.0275 g, 0.167 mmol), Wako Pure Chemical Industries, Ltd.) was dissolved in methanol (10.4 mL) and degassed with argon for 30 minutes. The degassed methanol solution was polymerized at 60 ° C. for 5 hours. After the polymerization, the methanol solution was placed in a dialysis membrane and dialyzed against water for 2 days, the obtained solution was concentrated, and further freeze-dried to obtain a PEG-b-PAMPS copolymer.
The obtained polymer, heavy water _(D 2 O) subjected to ¹ H-NMR measurement as the solvent, a comparison of the integral intensities of methylene protons of PAMPS side chain methylene protons and 3.4ppm of PEG backbone 3.7ppm The average degree of polymerization was calculated by. As a result, it was confirmed that the average degree of polymerization of PAMPS in the polymer was 84-mer. Moreover, when gel permeation chromatography (GPC) was performed, the molecular weight distribution (Mw / Mn) was 1.53.
1 shows a ¹ H-NMR spectrum of di-block copolymers of polyethylene glycol obtained with poly (2-acrylamido-2-methylpropane sodium sulfonate) (PEG-b-PAMPS) (D 2 O) ..
FIG. 2 shows a GPC chart of the obtained polyethylene glycol and poly (sodium 2-acrylamide-2-methylpropanesulfonate) diblock copolymer (PEG-b-PAMPS).

Example 2-1
<Synthesis of PEG-b-PAMPS-b-PSt>
The obtained PEG-b-PAMPS (2.04 g, 9.42 × ^10-5 mol, Mn = 21700, Mw / Mn = 1.53), styrene (1.68 g, 0.0161 mol, Wako Pure Chemical Industries, Ltd.) , And 2,4-dimethylvaleronitrile (V-65, 0.0165 g, 6.44 × ^10-5 mol, manufactured by Wako Pure Chemical Industries, Ltd.), which is a polymerization initiator, in methanol (15.0 mL). It was dissolved and degassed with argon for 30 minutes. The degassed methanol solution was heated to 50 ° C. and polymerized for 71 hours. After the polymerization, the methanol solution was dialyzed against the dialysis membrane with methanol for 2 days, and then dialyzed with water for 3 days. The obtained solution was concentrated and further freeze-dried to obtain PEG-b-PAMPS-b-PSt, which is a block copolymer of the present invention.
The obtained copolymer was subjected to ¹ _{H-NMR measurement (120 ° C.) using deuterated dimethylsulfoxide (DМSO-d 6} ) as a solvent, and 3.7 ppm of PEG main chain methylene proton and 6.8 to 7.4 ppm. The average degree of polymerization was calculated by comparing the phenyl protons of the PSt side chains of. From this, it was confirmed that the polymer had an average degree of polymerization of 39-mer. In addition, gel permeation chromatography (GPC) could not be measured because there was no solvent that could dissolve the polymer.
^{FIG. 3 shows the 1} H-NMR spectrum (DМSO-d ₆ , 120 ° C.) of the obtained triblock copolymer PEG-b-PAMPS-b-PSt.

In this example, DRX500 (manufactured by Bruker) was used for ^{1 1 H-NMR measurement.}

GPC measurement was performed under the following conditions.
Equipment: DP-8020 pump (manufactured by Tosoh Corporation)
Columns: GF-1G guard column and GF-7М analytical column (Shodex)
Detector: RI-8020 Refractive Index Detector (manufactured by Tosoh Corporation)
Developing solvent: Phosphate buffer containing 10% by volume acetonitrile (50 mМ, pH = 9)
Standard sample: Sodium polystyrene sulfonate

Example 3-1
0.0125 g of the copolymer of the present invention obtained in Example 2-1 was added to 2.5 g of pure water. After adding 0.025 g of titanium oxide particles (TTO-55 (A) manufactured by Ishihara Sangyo Co., Ltd.) to this, a titanium oxide dispersion was obtained by dispersion treatment for 2 hours with an ultrasonic disperser. (Titanium oxide concentration 1% by weight, polymer / titanium oxide weight ratio = 0.5.)
The evaluation results of the dispersion are shown in Table 1. The average dispersed particle size shown in this table indicates the particle size at an integrated value of 50% in the particle size distribution obtained by the dynamic light scattering method (Nikkiso Co., Ltd., Microtrack UPA-EX150).
The particle size distribution measurement results of the obtained dispersion are shown in FIG.
The state of the obtained dispersion is shown in FIG.

Comparative Example 1-1
A titanium oxide dispersion was obtained under the same conditions as in Example 2 except that no polymer was added.
The evaluation results of the dispersion are shown in Table 1.
The particle size distribution measurement results of the obtained dispersion are shown in FIG.
The state of the obtained dispersion is shown in FIG.

○＝分散、×＝沈殿あり

○ = dispersion, × = with precipitation

Comparing Example 3-1 and Comparative Example 1-1, in Example 3-1 the average dispersed particle size was small, no precipitation was observed, and the dispersion was maintained. Therefore, it is possible to have excellent dispersibility. it is obvious.

The block copolymer of the present invention has excellent dispersibility and can be suitably used as a dispersant. In particular, it has the characteristic that the particle size distribution of the object to be dispersed is stable within a certain width.

Claims (5)

A block copolymer obtained by polymerizing monomer B and monomer C on a copolymer A having the following structure a: general formula (3) and structure b: general formula (4).
Monomer B: A compound represented by the following general formula (9).
Monomer C: A compound represented by the following general formula (10).

(* Is the binding site with the structure b, x is an integer of 2 or 3, y is (polymerization number-1), the polymerization number is 1 to 11000, and z is an integer of 1 or 2. Is.)

(* Is the bonding site with the structure a, Z is a substituted or unsubstituted aryl group, a substituted or unsubstituted thioaryl group, a substituted or unsubstituted thioalkyl group, a substituted or unsubstituted amino group, a substituted or unsubstituted. The oxyaryl group of the above, or a substituted or unsubstituted oxyalkyl group. R represents any of the groups represented by the following formulas (5) and (6).)

(In the formula, * indicates that it is a joint with another part.)

(In the formula, R ₃ is a hydrogen atom or a methyl group, R ₂ is a hydrocarbon group having 1 to 8 carbon atoms, and X ⁺ is a proton, a metal cation, or an ammonium ion.)

(In the formula, R ₆ represents a hydrogen atom or a methyl group, and R _{7 to} R ₁₁ independently represent a hydrogen or a hydrocarbon group having 1 to 6 carbon atoms.) The block copolymer according to claim 1, wherein the copolymer A is a copolymer obtained by reacting a compound α represented by the general formula (7) with a compound β represented by the general formula (8). ..

(X, y, and z in the formula are the same as the above general formula (3).)

(In the formula, Z and R are the same as the above general formula (4).) The method for producing a block copolymer according to claim 1 or 2.
(A) A step of polymerizing the copolymer A and the monomer B to obtain a block copolymer AB,
(B) Step of polymerizing block copolymer AB and monomer C,
Manufacturing method including. The method for producing a block copolymer according to claim 3.
(A) Step of obtaining copolymer A from the compound α and the compound β (b) Step of obtaining a block copolymer AB by polymerizing the obtained copolymer A and the monomer B (c) Obtaining A production method comprising a step of polymerizing the obtained block copolymer AB and the monomer C. A dispersant containing the block copolymer according to claim 1 or 2.

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