JP2018090710A - Manufacturing method of star-shaped polymer, star-shaped polymer and filler dispersion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a star-shaped polymer high in polymerization yield, capable of using easily available materials, high in design freedom of a polymer structure and suitable for industrial manufacturing process.SOLUTION: Provided is a manufacturing method of a star-shaped polymer having a process 1 for polymerizing a first monomer component containing a monomer represented by the following general formula (1) under a condition that a compound which may produce iodide ion exists to obtain a core polymer having a branch structure having a group which may be living radical polymerized at a branch terminal, and a process 2 for polymerizing a second monomer component containing the core polymer and a (meth)acrylic acid-based monomer under a condition that a compound which may produce iodide ion exists.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing a star polymer having a star-branched structure, a star polymer produced by the production method, and a filler dispersion obtained using the star polymer.

  In recent years, polymers formed from vinyl compounds having a multi-branched structure such as graft polymers, star polymers, hyperbranched polymers, and branched polymers have been developed. Among these, star polymers and branched polymers are produced by polymerizing bifunctional monomers having two unsaturated bonds by a polymerization method such as an anionic polymerization method or a radical polymerization method. In particular, it is known that these polymers having a multi-branched structure are produced by a living polymerization method (Patent Document 1).

  Furthermore, a star polymer having a structure including a core part (core polymer) and a plurality of arm parts (polymer chains) bonded to the core part has been developed. A star polymer having such a structure can be produced, for example, by polymerizing a polymer having an unsaturated bond at its terminal and a bifunctional monomer by a radical polymerization method or the like (Patent Document 2). In addition, there is a method in which a core polymer having a plurality of polymerization initiating groups is produced in advance, and a monomer is polymerized from these polymerization initiating groups to elongate an arm part (Patent Document 3).

JP-A-11-29617 JP-A-8-81514 JP 2000-290326 A

  However, in the case of producing a star polymer by anionic polymerization, the cost tends to increase due to the need for purification of the material, and since the crosslinking reaction is caused by two or more unsaturated bonds, the material becomes a solvent. There were problems such as difficulty in melting. Moreover, when producing a star-shaped polymer by radical polymerization, insoluble matter is likely to be generated due to coupling between radicals, and the yield tends to be low. Furthermore, in the case of producing a star polymer by living radical polymerization, there are problems that the polymerization efficiency is low and the cost is high because it is necessary to use a special material.

  The present invention has been made in view of such problems of the prior art, and the problem is that the polymerization yield is high and easily available materials can be used, and An object of the present invention is to provide a method for producing a star polymer suitable for an industrial production process with a high degree of design freedom of the polymer structure. Another object of the present invention is to provide a star polymer useful as a filler dispersant produced by the above production method, and a filler dispersion using this star polymer as a filler dispersant. is there.

That is, according to this invention, the manufacturing method of the star polymer shown below is provided.
[1] A first monomer component containing a monomer represented by the following general formula (1) is polymerized under conditions in which a compound capable of generating iodide ions is present, and a group capable of living radical polymerization is used as a branch terminal. Step 1 for obtaining a core polymer having a branched structure having the above-mentioned condition, and the second monomer component containing the obtained core polymer and a (meth) acrylic acid monomer are present under the condition that a compound capable of generating iodide ions exists. Step 2 to obtain a star polymer having a plurality of arm portions containing a structural unit derived from the (meth) acrylic acid monomer, polymerized below and bonded to the branch end of the core polymer, and the core polymer; A process for producing a star polymer having

（前記一般式（１）中、Ｙは任意の有機基を示す）

(In the general formula (1), Y represents an arbitrary organic group)

[2] The method for producing a star polymer according to [1], wherein the first monomer component further includes a methacrylic acid monomer.
[3] The star polymer according to [1] or [2], wherein the content of the structural unit derived from the monomer represented by the general formula (1) in the core polymer is 5 to 50% by mass. Manufacturing method.
[4] Production of the star polymer according to any one of [1] to [3], wherein the first monomer component and the second monomer component are each polymerized under a condition in which an organic amine is further present. Method.

Moreover, according to this invention, the star polymer shown below is provided.
[5] A star polymer produced by the method for producing a star polymer according to any one of [1] to [4].
[6] The star polymer according to [5], wherein the content of the core polymer is 50% by mass or less.
[7] The number average molecular weight in terms of polystyrene of the core polymer measured by gel permeation chromatography is 1,000 to 20,000, and the number average molecular weight in terms of polystyrene measured by gel permeation chromatography is The star polymer according to [5] or [6] above, which is 10,000 to 1,000,000.
[8] The core polymer is at least one selected from the group consisting of a hydroxyl group, an acidic group, an amino group, a quaternary ammonium base, an aromatic ring group, an alkyl group having 8 to 18 carbon atoms, and an alkoxysilyl group. The star polymer according to any one of [5] to [7], comprising a structural unit derived from a methacrylic acid monomer having a group.
[9] The star polymer according to any one of [5] to [8], which is used as a filler dispersant.

Furthermore, according to the present invention, the following filler dispersion is provided.
[10] A dispersion medium, at least one filler selected from the group consisting of organic pigments, inorganic pigments, carbon nanotubes, and nanocellulose, and a filler dispersant that disperses the filler in the dispersion medium. A filler dispersion in which the filler dispersant is the star polymer described in [9].

  INDUSTRIAL APPLICABILITY According to the present invention, a method for producing a star polymer suitable for an industrial production process having a high polymerization yield, a material that can be easily obtained, and a high degree of freedom in designing a polymer structure. Can be provided. Moreover, according to this invention, the star-shaped polymer useful as a filler dispersing agent etc. which are manufactured by said manufacturing method, and the filler dispersion using this star-shaped polymer as a filler dispersing agent can be provided.

  According to the method for producing a star polymer of the present invention, the molecular weight of the arm part constituting the star polymer can be easily adjusted, and various functional groups can be introduced into the arm part. That is, according to the present invention, it is expected to provide a star-shaped polymer that has unprecedented properties and can be used for various fields.

<Method for producing star-shaped polymer>
Embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments. The manufacturing method of the star polymer of this invention has the process 1 which obtains a core polymer, and the process 2 which obtains a star polymer. In step 1, a first monomer component containing a monomer represented by the following general formula (1) is polymerized under conditions in which a compound capable of generating iodide ions is present, and a group capable of living radical polymerization is branched to a terminal group. This is a step of obtaining a core polymer having a branched structure. Then, in step 2, the obtained second polymer component containing the core polymer and the (meth) acrylic acid monomer is polymerized under a condition in which a compound capable of generating iodide ions is present. This is a step of obtaining a star polymer having a plurality of arm portions including a structural unit derived from a (meth) acrylic acid monomer, which is bonded to a branch end of the polymer.

（前記一般式（１）中、Ｙは任意の有機基を示す）

(In the general formula (1), Y represents an arbitrary organic group)

(Process 1)
The monomer represented by the general formula (1) includes an unsaturated bond capable of radical polymerization and a polymerization initiating group having a tertiary carbon atom bonded to a bromine atom, capable of radical polymerization (preferably living radical polymerization). It is a monomer contained in its molecular structure.

  The bromine atom in the polymerization initiating group is eliminated as a bromine radical by a conventionally known method. Further, with the elimination of the bromine radical, a radical of a tertiary carbon atom (carbon radical) is generated. Then, the unsaturated bond capable of radical polymerization of the monomer reacts with the generated carbon radical. As a method for desorbing bromine atoms as bromine radicals, there are an atom transfer radical polymerization method using a redox reaction of a metal ion of a metal complex, a method using a base and the like. After the bromine atom in the polymerization initiating group is eliminated as a bromine radical, the monomer may be inserted to polymerize. However, there are compounds that can produce iodide ions in the system. For this reason, after a bromine atom and an iodine atom carry out halogen exchange and an iodine atom couple | bonds with a tertiary carbon atom, an iodine atom may detach | desorb as an iodine radical by the effect | action of a redox reaction or a base.

  The monomer represented by the general formula (1) is a reaction product of the corresponding monomer (a) and acid component (b), for example, as represented by the following formula.

  The monomer (a) is a methacrylate having a hydroxyl group. Z in the general formula (a) represents an arbitrary organic group. X in the general formula (b) represents a hydroxyl group, a halogen atom, or an organic carboxylic acid anhydride residue.

  As the monomer (a), hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, poly (n = 2 or more) ethylene glycol monomethacrylate, poly (n = 2 or more) propylene glycol monomethacrylate, poly (n = 2 or more) polybutylene glycol monomethacrylate, poly (n = 2 or more) ethylene propylene glycol monomethacrylate, methacryloyloxy-2-hydroxy-1-chloropropane, methacryloyloxydihydroxypropane, and the like. Furthermore, a reaction product of a methacrylate having the above hydroxyl group with a hydroxycarboxylic acid such as lactic acid or a cyclic ester such as ε-caprolactone; a methacrylate having the above hydroxyl group and a polybasic acid (for example, succinic acid or phthalic acid) And a monomethacrylate compound obtained by reacting a hydroxyl group); an ester methacrylate having a hydroxyl group obtained by reacting a methacrylate having the above hydroxyl group and a diol. In addition, as arbitrary organic groups each represented by Z in the general formula (a) and Y in the general formula (1), methylene, ethylene, propylene, methylethylene, butylene, methylpropylene, hexylene, poly (n = 2 or more) oxyalkylene (having 2 to 4 carbon atoms).

  Examples of the acid component (b) include isobromobutyric acid, isobromobutyric acid bromide, and isobromobutyric anhydride. The monomer represented by the general formula (1) can also be obtained by reacting glycidyl methacrylate or 3,4-epoxycyclohexylmethyl methacrylate with the acid component (b) described above. Furthermore, the monomer represented by the general formula (1) can be obtained by reacting the diol with the acid component (b) and then reacting methacrylic acid, methacrylic acid chloride, methacrylic anhydride, or the like.

  In step 1, the first monomer component containing the monomer represented by the general formula (1) is polymerized by heating as necessary under conditions where a compound capable of generating iodide ions is present. Thereby, a core polymer having a branched structure having a group capable of living radical polymerization at the branch end can be obtained. As the compound capable of generating iodide ions (iodine compound), a metal iodide salt, a quaternary ammonium iodide salt, a quaternary phosphonium iodide salt, a quaternary ammonium triiodide salt, or the like can be used. . Examples of the metal iodide salt include lithium iodide, sodium iodide, potassium iodide, calcium iodide, magnesium iodide and the like. Examples of the quaternary ammonium iodide salt include tetramethylammonium iodide, tetraethylammonium iodide, and tetrabutylammonium iodide. Examples of the quaternary phosphonium iodide salt include tetrabutylphosphonium iodide, tributylmethylphosphonium iodide, and triphenylmethylphosphonium iodide. Examples of the quaternary ammonium triiodide salt include tributylmethylammonium triiodide.

  The first monomer component preferably further contains a methacrylic acid monomer. Examples of methacrylic acid monomers include methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, 2-methylpropane methacrylate, t-butyl methacrylate, pentyl methacrylate, hexyl methacrylate, octyl methacrylate, 2-ethylhexyl methacrylate, nonyl methacrylate, Decyl methacrylate, isodecyl methacrylate, lauryl methacrylate, tetradecyl methacrylate, octadecyl methacrylate, behenyl methacrylate, isostearyl methacrylate, cyclohexyl methacrylate, t-butylcyclohexyl methyl methacrylate, isobornyl methacrylate, trimethylcyclohexyl methacrylate, B decyl methacrylate, cyclo decyl methyl methacrylate, benzyl methacrylate, t- butyl benzotriazole-phenylethyl methacrylate, phenyl methacrylate, naphthyl methacrylate, aliphatic, such as allyl methacrylate, can be mentioned alicyclic, and an aromatic alkyl methacrylates.

  Further, as a methacrylic acid monomer, a monomer having a hydroxyl group, a monomer having a glycol group, a monomer having an acid group (carboxy group, phosphoric acid group, sulfonic acid group, etc.), a monomer containing an oxygen atom, and an amino group Monomers, monomers containing nitrogen atoms, polyester monomethacrylates, ester methacrylates, monomethacrylates of polyfunctional hydroxyl compounds, halogen atom-containing methacrylates, silicon atom-containing monomers, monomers having ultraviolet absorbing groups, α-position hydroxyl group methyl substitution Acrylates, monomers having two or more addition polymerizable groups, and the like can be used.

  Next, regarding the process of forming the core polymer in Step 1, together with the monomer represented by the general formula (1) (hereinafter also referred to as “initiating group monomer” for convenience), a methacrylic acid monomer (if necessary) ( Hereinafter, the case of using “constituent monomer” for convenience will be described as an example. As shown in the following formula, first, the halogen atom W (bromine atom or iodine atom) is eliminated as a halogen radical from the polymerization initiating group of the compound represented by the general formula (1). A carbon radical is generated with the elimination of the halogen radical, and reacts with the unsaturated bond of the initiating group monomer or the unsaturated bond of the constituent monomer. When the generated carbon radical reacts with the unsaturated bond of the initiating group monomer, a monomer (intermediate) having two polymerization initiating groups is formed. Further, when the generated carbon radical reacts with the unsaturated bond of the constituent monomer, an initiating group monomer (intermediate) having an extended polymer chain is formed. By repeating such a reaction, the polymer chain extends and the number of branched branch ends (polymerization initiating groups) increases. As a result, a core polymer (A) having a branched structure having a group capable of living radical polymerization at the branch end is formed.

  The content of the structural unit derived from the monomer represented by the general formula (1) in the core polymer is preferably 5 to 50% by mass, and more preferably 10 to 30% by mass. When the content of the structural unit derived from the monomer represented by the general formula (1) in the core polymer is less than 5% by mass, the number of branches may be small, and a sufficiently branched star structure is difficult to be formed. May be. On the other hand, if it is more than 50% by mass, the number of branches may be too large, and it may be easy to form particles.

  There is no particular limitation on the amount of the compound that can generate iodide ions with respect to the monomer represented by the general formula (1). Specifically, it is preferable to use 0.1 to 2 moles of a compound capable of generating iodide ions with respect to the polymerization initiating group in the monomer represented by the general formula (1).

  The polymerization reaction is preferably solution polymerization performed in the presence of an organic solvent. Organic solvents include hexane, octane, decane, isodecane, cyclohexane, methylcyclohexane, toluene, xylene, ethylbenzene and other hydrocarbon solvents; methanol, ethanol, propanol, isopropanol, butanol, isobutanol, hexanol, benzyl alcohol, cyclohexanol Alcohol solvents such as: ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol propyl ether, diglyme, triglyme, tetraglyme, dipro Pilin glycol dimethyl ether, butyl carb Glycol solvents such as ethanol, butyltriethylene glycol, methyl dipropylene glycol, methyl cellosolve acetate, propylene glycol monomethyl ether acetate, dipropylene glycol butyl ether acetate, diethylene glycol monobutyl ether acetate; diethyl ether, dipropyl ether, methylcyclopropyl ether Ether solvents such as tetrahydrofuran, dioxane and anisole; ketone solvents such as methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, cyclohexanone, isophorone and acetophenone; methyl acetate, ethyl acetate, butyl acetate, propyl acetate, methyl butyrate, ethyl butyrate, Caprolactone, methyl lactate, ethyl lactate, dimethyl oxalate, dimethyl adipate Ester solvents such as dimethyl glutarate; halogenated solvents such as chloroform and dichloroethane; amide solvents such as dimethylformamide, dimethylacetamide, pyrrolidone, N-methylpyrrolidone, caprolactam, dimethyl sulfoxide, sulfolane, tetramethylurea Dimethyl imidazolidinone, ethylene carbonate, propylene carbonate, dimethyl carbonate and the like. These organic solvents can be used individually by 1 type or in combination of 2 or more types.

  The amount of the first monomer component in the organic solvent is preferably 10 to 70% by mass, and more preferably 30 to 60% by mass. In order to dissolve iodide ions, it is preferable to use a highly polar organic solvent. Among them, it is preferable to use an alcohol organic solvent, a glycol organic solvent, an amide organic solvent, or a urea organic solvent.

  What is necessary is just to superpose | polymerize a 1st monomer component on temperature conditions more than room temperature. However, when polymerizing at a temperature around room temperature, the polymerization time may be long. For this reason, it is preferable to polymerize by heating to 40 ° C. or higher, more preferably 60 ° C. or higher, particularly preferably 70 ° C. or higher.

  It is preferred to polymerize the first monomer component in the presence of an organic amine. By polymerizing in the presence of an organic amine, the polymerization rate and the polymerization yield can be improved. Organic amines include trimethylamine, triethylamine, dimethylbutylamine, tributylamine, trioctylamine, dodecyldimethylamine, dimethylaminoethanol, triethanolamine, tripropanolamine, diazabicycloundecene, diazabicyclooctane, N-methylmorpholine. It is preferable to use a tertiary organic amine such as pyridine.

  A radical generator may be used in combination. Examples of the radical generator include oily azo initiators such as 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile) and azobisisobutyronitrile; benzoyl peroxide, lauroyl peroxide, t -Oily peroxides such as butyl lauric acid perester.

  After the polymerization reaction, the volatile matter may be removed and the solid matter may be taken out, or may be used in the next step as it is. Alternatively, the reaction solution may be poured into a poor solvent to precipitate the core polymer, and then filtered and dried to be taken out in a powder state. However, it is preferable to remove the monomer represented by the general formula (1) as much as possible. Specifically, the content of the monomer represented by the general formula (1) is preferably less than 5% by mass, and more preferably less than 1% by mass. If a large amount of the monomer of the general formula (1) is present, it may be difficult to form the arm portion in the next step (step 2).

(Process 2)
In step 2, the second monomer component containing the core polymer and (meth) acrylic acid monomer obtained in step 1 is polymerized under conditions in which a compound capable of generating iodide ions is present. (Meth) acrylic acid monomers include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, 2-methylpropane (meth) acrylate, t -Butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate , Lauryl (meth) acrylate, tetradecyl (meth) acrylate, octadecyl (meth) acrylate, behenyl (meth) acrylate, isostearyl (meth) acrylate, cyclohexyl (meth) acrylate Rate, t-butylcyclohexylmethyl (meth) acrylate, isobornyl (meth) acrylate, trimethylcyclohexyl (meth) acrylate, cyclodecyl (meth) acrylate, cyclodecylmethyl (meth) acrylate, benzyl (meth) acrylate, t-butylbenzotriazole Examples thereof include aliphatic, alicyclic, and aromatic alkyl (meth) acrylates such as phenylethyl (meth) acrylate, phenyl (meth) acrylate, naphthyl (meth) acrylate, and allyl (meth) acrylate.

  Furthermore, as a (meth) acrylic acid monomer, a monomer containing a hydroxyl group, a monomer having a glycol group, a monomer having an acid group (carboxy group, phosphoric acid group, sulfonic acid group, etc.), a monomer containing an oxygen atom, amino Group-containing monomer, nitrogen atom-containing monomer, polyester-based mono (meth) acrylate, ester-based (meth) acrylate, poly (hydroxy) compound mono (meth) acrylate, halogen atom-containing (meth) acrylate, silicon atom For example, a monomer having an ultraviolet-absorbing group, an α-position hydroxyl group methyl-substituted (meth) arylate, a monomer having two or more addition polymerizable groups can be used.

  As a compound (iodine compound) that can generate iodide ions, the same compounds as those used in Step 1 can be used. The iodine compound used in step 1 and the iodine compound used in step 2 may be the same compound or different compounds.

  Further, it is preferable to polymerize the second monomer component in the presence of an organic amine. By polymerizing in the presence of an organic amine, the polymerization rate and the polymerization yield can be improved. As the organic amine, those similar to those used in Step 1 can be used. The organic amine used in step 1 and the organic amine used in step 2 may be the same compound or different compounds.

As shown in the following formula, the second monomer component was bonded to the branch end of the core polymer (A) and the core polymer (A) by polymerizing under the same reaction conditions as the polymerization reaction conditions in Step 1. , A star polymer (X) having a plurality of arm portions including a structural unit derived from a (meth) acrylic acid monomer can be formed. At the branch end of the core polymer (A), there is a group capable of living radical polymerization blocked with a halogen atom W (bromine atom or iodine atom). A carbon radical is generated with the elimination of the halogen radical, and a (meth) acrylic acid monomer is inserted. After the desorbed halogen radical returns to the extension end of the arm portion and is stabilized, the halogen radical is desorbed again to generate a carbon radical. Furthermore, by repeating the reaction that a (meth) acrylic acid monomer is inserted, an arm part is formed, and the star polymer (X) can be obtained. In the following formula, R ₁ represents a hydrogen atom or a methyl group, and R ₂ represents an arbitrary organic group.

<Star polymer>
The star polymer of the present invention can be produced by the above-mentioned star polymer production method. That is, the star polymer of the present invention has a core polymer and a plurality of arm parts including structural units derived from a (meth) acrylic acid monomer, which are bonded to the branch ends of the core polymer.

The content of the core polymer in the star polymer is preferably 50% by mass or less, more preferably 40% by mass or less, and particularly preferably 30% by mass or less.
If the content of the core polymer is more than 50% by mass, the performance of the arm portion is difficult to be exhibited, and the properties of the core polymer may be manifested too easily to become a particle shape.

  When the content of the core polymer in the star polymer is 50% by mass or less, that is, when the content of the arm part which is a linear polymer is more than 50% by mass, the arm part can be dissolved in an organic solvent. “Dissolved in an organic solvent” means that when a star polymer is added to an organic solvent, it becomes almost transparent without turbidity or precipitation. In addition, as an organic solvent, the solubility with respect to the organic solvent of a star-shaped polymer can be designed suitably by changing the polymer composition which comprises an arm part. For this reason, it is difficult to generally specify the types of organic solvents that can dissolve the star polymer. However, the star polymer can be dissolved in the above-mentioned type of organic solvent by designing the polymer composition constituting the arm portion. That is, when a star polymer containing at least a predetermined arm portion that can be dissolved in an organic solvent is added to the organic solvent, it can be almost transparent (substantially dissolved).

  Further, since the arm part is a linear polymer capable of forming a film, a star polymer containing at least a predetermined part of the arm part can also be used as a coating film forming component. Further, by using a pigment adsorbing monomer such as a monomer having an amino group as the first monomer component constituting the core polymer, the star polymer can be used as a pigment dispersant. However, when there is too much content of the structural unit derived from a pigment adsorbing monomer, dispersibility may fall.

  The polystyrene-equivalent number average molecular weight of the core polymer measured by gel permeation chromatography is preferably 1,000 to 20,000, and more preferably 5,000 to 15,000. When the number average molecular weight of the core polymer is less than 1,000, the properties of the core polymer are hardly exhibited and the degree of branching tends to decrease. On the other hand, when the number average molecular weight of the core polymer is more than 20,000, the core polymer is too large, and thus it tends to be particleized and may be easily gelled during polymerization.

  The polystyrene-equivalent number average molecular weight of the star polymer measured by gel permeation chromatography is preferably 10,000 to 1,000,000, and more preferably 12,000 to 500,000. If the number average molecular weight of the star polymer is less than 10,000, the size as a polymer molecule may be slightly insufficient. On the other hand, if the number average molecular weight of the star polymer is more than 1,000,000, the viscosity tends to increase during the polymerization, and stirring may be difficult.

  As the use of the star polymer of the present invention, a binder as a coating film forming component, a viscosity modifier, a rheology control agent, a filler dispersant such as a pigment dispersant, a viscosity reducer, a slip agent, a water repellent, an oil repellent, Examples include high-functional surface treatment agents, mold release agents, compatibilizers, impact resistance improvers, stiffness improvers, reinforcing agents, DDS (drug delivery system) carriers, refractive index adjusters, and UV absorbers. . Regardless of water-based or oil-based, added to paints, inks, stationery, cosmetics, textiles, coating agents, electronic materials, display materials, optical device materials, optical recording materials, resin additives, automotive parts materials, etc. Can do.

  The star polymers of the present invention are particularly useful as filler dispersants. For example, a polymer structure having a core polymer including a structural unit having a group that can be adsorbed to various fillers and an arm portion that can be compatible with a dispersion medium enables dispersibility, dispersion stability, color development, and transparency. In addition, a filler dispersant capable of improving various properties of the filler such as sedimentation stability and sediment recovery properties can be obtained.

  When the star polymer of the present invention is used as a filler dispersant, the core polymer is a hydroxyl group, an acidic group, an amino group, a quaternary ammonium base, an aromatic ring group, an alkyl group having 8 to 18 carbon atoms, and It is preferable to comprise so as to include a structural unit derived from a methacrylic acid monomer having at least one group selected from the group consisting of alkoxysilyl groups. Hydroxyl groups and acidic groups are adsorbed on the filler by hydrogen bonding. Furthermore, when a basic group is present in the structure of the filler, or when the filler is treated with a derivative having a basic group, the acidic group is adsorbed on the filler by ionic bonding. The quaternary ammonium base is adsorbed to the filler by ionic bonding when a sulfonic acid group or the like is present in the filler structure. In addition, since the quaternary ammonium salt may be difficult to dissolve in a nonpolar solvent, the quaternary ammonium salt may be adsorbed on the filler by an adsorption action utilizing the non-affinity of the core polymer to the dispersion medium. The aromatic ring group is adsorbed to the filler by π-π stacking. Furthermore, an aromatic ring group or an alkyl group having 8 to 18 carbon atoms is adsorbed to the filler by hydrophobic interaction. The alkoxysilyl group is adsorbed on the filler by a covalent bond formed by dehydration condensation with a hydroxyl group on the filler surface.

  What is necessary is just to comprise an arm part so that it may become a polymer composition compatible and compatible with a dispersion medium. When monomers, oligomers, thermoplastic resins, or thermosetting resins used in various organic solvents, ultraviolet curable inks, and the like are used as the dispersion medium, a polymer composition that is compatible with these dispersion media may be selected. On the other hand, when an aqueous solvent is used as a dispersion medium, it can be dissolved in an aqueous solvent by forming a polymer composition having an acidic group or amino group, or a polymer composition having a glycol chain such as a polyethylene glycol group. .

<Filler dispersion>
The filler dispersion of the present invention contains a dispersion medium, a filler, and a filler dispersant that disperses the filler in the dispersion medium. The filler dispersant is the above-described star polymer. The filler is a filler or additive used by being dispersed in a dispersion medium in order to exhibit characteristics such as a specific function and durability. As the filler, organic pigments, inorganic pigments, carbon nanotubes, and nanocellulose, which are known to be fine and difficult to disperse, can be used. These fillers can be used singly or in combination of two or more.

  As organic pigments, azo pigments such as azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments; phthalocyanine pigments, perylene and perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, Examples thereof include polycyclic pigments such as diketopyrrolopyrrole; dye lake pigments such as basic dye type lake pigments and acid dye type lake pigments; nitro pigments, nitroso pigments, and aniline black. Examples of inorganic pigments include carbon black, extender pigments, titanium oxide pigments, iron oxide pigments, spinel pigments, composite metal oxides, natural minerals such as clay, and magnetic materials.

  As the carbon nanotube, any of a single wall nanotube, a double wall nanotube, and a multi-wall nanotube can be used. Examples of the single wall nanotube include those having an outer diameter of 0.47 nm to 100 nm, a length of 0.5 to 500 μm, and a purity of 50 to 100%. Examples of the multi-wall nanotube and double-wall nanotube include those having an outer diameter of 1 to 100 μm, an inner diameter of 0.1 to 95 μm, a length of 0.5 to 500 μm, and a purity of 50 to 100%.

  Nanocellulose is obtained by defibrating a material (wood pulp or the like) containing cellulose fibers, which are plant raw materials, to a nano-level size. Examples of nanocellulose include cellulose nanofiber (CNF) and cellulose nanocrystal (CNC).

Cellulose nanofibers are fibers having a fiber width of about 4 to 200 nm and a fiber length of about 5 μm or more obtained by subjecting an aqueous suspension or slurry of a material containing cellulose fibers to a treatment such as mechanical defibration. The specific surface area of the cellulose nanofiber is usually 70~300m ² / g, preferably from 70 to 250 ² / g, more preferably from 100 to 200 m ² / g. The fiber diameter (average value) is usually 4 to 200 nm, preferably 4 to 150 nm, and more preferably 4 to 100 nm.

The cellulose nanocrystal is a crystal having a crystal width of about 4 to 70 nm and a crystal length of about 25 to 3000 nm, which is obtained by subjecting cellulose fibers to chemical treatment such as acid hydrolysis. The specific surface area of the cellulose nanocrystals typically 90~900m ² / g, preferably from 100 to 500 m ² / g, more preferably from 100 to 300 m ² / g. The crystal width (average value) is usually 10 to 50 nm, preferably 10 to 30 nm, and more preferably 10 to 20 nm. The crystal length (average value) is usually about 500 nm, preferably 100 to 500 nm, particularly preferably 100 to 200 nm.

  The dispersion medium may be either a liquid or a solid. Examples of the liquid dispersion medium include water, an organic solvent, a monomer component, an ionic liquid, and a liquid polymer. Solid dispersion media include polystyrene resin, ABS resin, styrene butadiene resin, styrene butadiene styrene resin, polyethylene resin, polypropylene resin, polyester resin such as polyethylene terephthalate and polybutylene terephthalate, polycarbonate resin, acrylic resin, urethane resin, Examples thereof include thermoplastic resins such as polyphenylene ether resins and polyphenylene sulfide resins; thermosetting resins such as melamine resins, epoxy resins, unsaturated polyester resins, and phenol resins.

  A filler dispersion can be obtained by using a star polymer as a filler dispersant, a filler, and a dispersion medium, and mixing and dispersing according to a conventionally known method. For example, when producing a liquid filler dispersion, for example, a kneader, an ultrasonic disperser, a high-pressure homogenizer, a disperser using bead media, or the like can be used. Moreover, when manufacturing a solid filler dispersion, a mixing roll, a Banbury mixer, a kneader, a kneader ruder, a single screw extruder, a multi-screw extruder, etc. can be used.

  The amount (composition ratio) of each component to be contained in the filler dispersion is not particularly limited, and can be appropriately set depending on the application. Further, the amount of the filler dispersant can be appropriately set according to the filler shape, particle diameter, and adsorptive properties. When an example is given, it is preferable to contain 3-100 mass parts of filler dispersing agents with respect to 100 mass parts of fillers, and it is still more preferable to contain 5-50 mass parts.

  The filler dispersion may further contain a conventionally known functional material. Functional materials include durability improvers (ultraviolet absorbers, antioxidants, light stabilizers, etc.), release agents, peelability improvers, antibacterial agents, antifungal agents, plasticizers, antistatic agents, anti-drying agents , Flame retardants, infrared absorbers, far-infrared absorbers, heat ray reflectors, sparingly soluble inorganic salts, and the like.

  The liquid filler dispersion can be used, for example, as a paint, ink, coating agent, adhesive, stationery colorant or additive. Of the liquid filler dispersions, the aqueous pigment dispersion can be used as a colorant for aqueous paints, aqueous gravure inks, inkjet inks, aqueous stationery inks, aqueous coating agents, aqueous adhesives, and the like. Furthermore, among liquid filler dispersions, oily dispersions can be used as paints, gravure inks, oily stationery, coating materials, and adhesives. Solid filler dispersions can be used for molded products such as various containers, films, sheets, blisters, pipes, hoses, tubes, beads, fibers, automobile parts, electrical equipment parts, stationery, toys, furniture, and daily necessities. It can be used as a constituent material.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples. In the examples and comparative examples, “parts” and “%” are based on mass unless otherwise specified.

<Production of star polymer (1)>
Example 1
Into a 2 L separable flask (reaction vessel) equipped with a stirrer, a reverse flow condenser, a thermometer, and a nitrogen introduction tube, an organic solvent (amide solvent, trade name “EXAMID M100”, manufactured by Idemitsu Kosan Co., Ltd., hereinafter “M100”). 400 parts, 20 parts of 2- (2-bromoisobutylyloxy) ethyl methacrylate (BEMA), 180 parts of methyl methacrylate (MMA), and 29.1 parts of tributylammonium iodide (TBAI) are added and stirred. And heated to 75 ° C. After TBAI dissolved and became uniform, 1.4 parts of triethylamine (TEA) was added and polymerized at 75 ° C. for 7 hours to obtain a core polymer solution. The polymerization rate calculated based on the solid content (35.9%) measured by sampling was about 100%. Moreover, the number average molecular weight (Mn) of the core polymer measured by GPC using tetrahydrofuran (THF) as a developing solvent was 16,100, and the dispersity (PDI) was 1.59.

  5,000 parts of methanol was placed in a 10 L beaker, and the core polymer solution was added while stirring at 1,500 rpm using a disper to precipitate the core polymer to obtain a polymer slurry. The resulting polymer slurry was filtered and then washed with methanol and water. The core polymer CP-1 was obtained by drying with a dryer at 70 ° C. for 24 hours.

  In a reaction vessel similar to the reaction vessel described above, 600 parts of M100 and 40 parts of core polymer CP-1 were placed and heated to 80 ° C. to dissolve the core polymer CP-1. After 7.3 parts of TBAI were added and dissolved, 360 parts of MMA and 0.4 parts of TEA were further added and polymerized at 80 ° C. for 6 hours to obtain a solution of star polymer S-1. The solid content was 39.8% and the polymerization rate was about 100%. Further, the Mn of the star polymer S-1 measured by GPC was 35,000, and the PDI was 1.61. As the molecular weight increased and the peak of the core polymer CP-1 disappeared, the polymer extended from the branch end of the core polymer CP-1 (the arm part was bonded to the branch end of the core polymer CP-1). I understand).

(Example 2)
In a reaction vessel similar to the reaction vessel used in Example 1, 400 parts of M100, 40 parts of BEMA, 160 parts of MMA, and 58.2 parts of TBAI were placed, stirred and heated to 75 ° C. After TBAI dissolved and became uniform, 2.8 parts of TEA was added and polymerized at 75 ° C. for 7 hours to obtain a core polymer solution. The solid content was 38.6% and the polymerization rate was about 100%. Moreover, Mn of the core polymer measured by GPC was 7,500, and PDI was 1.54.

  5,000 parts of methanol was placed in a 10 L beaker, and the core polymer solution was added while stirring at 1,500 rpm using a disper to precipitate the core polymer to obtain a polymer slurry. The resulting polymer slurry was filtered and then washed with methanol and water. The core polymer CP-2 was obtained by drying with a dryer at 70 ° C. for 24 hours.

  In a reaction vessel similar to the reaction vessel described above, 600 parts of M100 and 40 parts of core polymer CP-2 were placed and heated to 80 ° C. to dissolve the core polymer CP-2. After adding 14.6 parts of TBAI and dissolving, 360 parts of MMA and 0.8 part of TEA were further added and polymerized at 80 ° C. for 6 hours to obtain a solution of star polymer S-2. The solid content was 39.9% and the polymerization rate was about 100%. Further, the Mn of the star polymer S-2 measured by GPC was 15,300, and the PDI was 1.59. As the molecular weight increased and the peak of the core polymer CP-2 disappeared, the polymer extended from the branch end of the core polymer CP-2 (the arm part was bonded to the branch end of the core polymer CP-2). I understand).

(Example 3)
In a reaction vessel similar to that used in Example 1, 600 parts of M100 and 40 parts of core polymer CP-1 obtained in Example 1 were placed, heated to 80 ° C., and dissolved in core polymer CP-1. I let you. After adding TBAI 7.3 parts and dissolving, 360 parts of benzyl methacrylate (BzMA) and 0.4 parts of TEA were further added and polymerized at 80 ° C. for 6 hours to obtain a solution of star polymer S-3. . The solid content was 39.8% and the polymerization rate was about 100%. Further, the Mn of the star polymer S-3 measured by GPC was 38,000, and the PDI was 1.63. As the molecular weight increased and the peak of the core polymer CP-1 disappeared, the polymer extended from the branch end of the core polymer CP-1 (the arm part was bonded to the branch end of the core polymer CP-1). I understand).

Example 4
In a reaction vessel similar to that used in Example 1, 600 parts of M100 and 40 parts of core polymer CP-1 obtained in Example 1 were placed, heated to 80 ° C., and dissolved in core polymer CP-1. I let you. After 21.9 parts of TBAI were added and dissolved, 280 parts of MMA and 8.4 parts of TEA were further added and polymerized at 80 ° C. for 6 hours to obtain a solution of star polymer S-4. The solid content was 41.7% and the polymerization rate was about 100%. Further, the Mn of the star polymer S-4 measured by GPC was 25,300, and the PDI was 1.58. As the molecular weight increased and the peak of the core polymer CP-1 disappeared, the polymer extended from the branch end of the core polymer CP-1 (the arm part was bonded to the branch end of the core polymer CP-1). I understand).

  Table 1 shows the composition and physical properties of the star polymers produced in Examples 1 to 4.

<Production of star polymer (2)>
(Example 5)
In a reaction vessel similar to the reaction vessel used in Example 1, 400 parts of M100, 100 parts of BzMA, 40 parts of BEMA, 40 parts of cyclohexyl methacrylate (CHMA), 20 parts of MMA, and 58.2 parts of TBAI were stirred and stirred at 75 ° C. Warmed to. After TBAI dissolved and became uniform, 2.8 parts of TEA was added and polymerized at 75 ° C. for 7 hours to obtain a core polymer solution. The solid content was 39.1% and the polymerization rate was about 100%. Moreover, Mn of the core polymer measured by GPC was 7,800, and PDI was 1.68.

  5,000 parts of methanol was placed in a 10 L beaker, and the core polymer solution was added while stirring at 1,500 rpm using a disper to precipitate the core polymer to obtain a polymer slurry. The resulting polymer slurry was filtered and then washed with methanol and water. The core polymer CP-3 was obtained by drying with a dryer at 70 ° C. for 24 hours.

  In a reaction vessel similar to the above-described reaction vessel, 600 parts of diethylene glycol monobutyl ether (BDG) and 120 parts of core polymer CP-3 were placed and heated to 80 ° C. to dissolve the core polymer CP-3. After 43.8 parts of TBAI were added and dissolved, 200 parts of BzMA, 80 parts of methacrylic acid (MAA), and 2.4 parts of TEA were further added, and polymerized at 80 ° C. for 6 hours to obtain a solution of star polymer S-5 Got. The solid content was 41.5% and the polymerization rate was about 100%. Further, the Mn of the star polymer S-5 measured by GPC was 17,700, and the PDI was 1.75. As the molecular weight increased and the peak of the core polymer CP-3 disappeared, the polymer extended from the branch end of the core polymer CP-3 (the arm part was bonded to the branch end of the core polymer CP-3). I understand). Subsequently, 15.5 parts of 28% ammonia water and 289.8 parts of ion exchange water were added to the solution of the star polymer S-5 to neutralize it, and a transparent aqueous solution of the star polymer S-5 (solid content: 30). 4%).

(Example 6)
In a reaction vessel similar to that used in Example 1, 400 parts of M100, 40 parts of BEMA, 110 parts of BzMA, 50 parts of MAA, and 58.2 parts of TBAI were stirred and heated to 75 ° C. After TBAI dissolved and became uniform, 2.8 parts of TEA was added and polymerized at 75 ° C. for 7 hours to obtain a core polymer solution. The solid content was 39.2% and the polymerization rate was about 100%. Moreover, Mn of the core polymer measured by GPC was 7,200, and PDI was 1.68.

  5,000 parts of methanol was placed in a 10 L beaker, and the core polymer solution was added while stirring at 1,500 rpm using a disper to precipitate the core polymer to obtain a polymer slurry. The resulting polymer slurry was filtered and then washed with methanol and water. It was made to dry for 24 hours with a 70 degreeC dryer, and core polymer CP-4 was obtained.

  In a reaction vessel similar to the reaction vessel described above, 600 parts of M100 and 120 parts of core polymer CP-4 were placed and heated to 80 ° C. to dissolve the core polymer CP-4. After 43.8 parts of TBAI were added and dissolved, 80 parts of MMA, 160 parts of butyl methacrylate (BMA), 40 parts of 2-ethylhexyl methacrylate (EHMA), and 2.4 parts of TEA were further added, and 6 parts at 80 ° C. Polymerization over time gave a solution of star polymer S-6. The solid content was 40.1% and the polymerization rate was about 100%. Further, the Mn of the star polymer S-6 measured by GPC was 18,400, and the PDI was 1.85. As the molecular weight increased and the peak of the core polymer CP-4 disappeared, the polymer extended from the branch end of the core polymer CP-4 (the arm part was bonded to the branch end of the core polymer CP-4). I understand). The acid value of the star polymer S-6 measured by titration with 0.1N KOH ethanol solution using ethanol / toluene as a solvent and phenolphthalein as an indicator was 46.5 mgKOH / g.

(Example 7)
In a reaction vessel similar to the reaction vessel used in Example 1, 400 parts of M100, 40 parts of BEMA, 110 parts of BzMA, 50 parts of 2-dimethylaminoethyl methacrylate (DMAEMA), and 58.2 parts of TBAI were added and stirred to 75. Warmed to ° C. After TBAI dissolved and became uniform, 2.8 parts of TEA was added and polymerized at 75 ° C. for 7 hours to obtain a core polymer solution. The solid content was 39.4% and the polymerization rate was about 100%. Moreover, Mn of the core polymer measured by GPC was 7,300, and PDI was 1.65.

  5,000 parts of methanol was placed in a 10 L beaker, and the core polymer solution was added while stirring at 1,500 rpm using a disper to precipitate the core polymer to obtain a polymer slurry. The resulting polymer slurry was filtered and then washed with methanol and water. It was made to dry for 24 hours with a 70 degreeC dryer, and core polymer CP-5 was obtained.

  In a reaction vessel similar to the above-described reaction vessel, 600 parts of BDG and 120 parts of core polymer CP-5 were placed and heated to 80 ° C. to dissolve the core polymer CP-5. After 43.8 parts of TBAI was added and dissolved, 80 parts of MMA, 160 parts of BMA, 40 parts of EHMA, and 2.4 parts of TEA were further added and polymerized at 80 ° C. for 6 hours to obtain a solution of star polymer S-7. It was. The solid content was 40.0% and the polymerization rate was about 100%. Further, the Mn of the star polymer S-7 measured by GPC was 17,900, and the PDI was 1.81. As the molecular weight increased and the peak of the core polymer CP-5 disappeared, the polymer extended from the branch end of the core polymer CP-5 (the arm part was bonded to the branch end of the core polymer CP-5). I understand). The amine value of the star-shaped polymer S-7 measured by titration with bromocresol green as an indicator using a 0.1N hydrochloric acid 2-propanol solution using 2-propanol / toluene as a solvent was 25.8 mgKOH / g. .

(Example 8)
In a reaction vessel similar to the reaction vessel used in Example 1, 400 parts of M100, 40 parts of BEMA, 160 parts of HEMA, and 58.2 parts of TBAI were placed, stirred and heated to 75 ° C. After TBAI dissolved and became uniform, 2.8 parts of TEA was added and polymerized at 75 ° C. for 7 hours to obtain a core polymer solution. The solid content was 36.0% and the polymerization rate was about 100%. Moreover, Mn of the core polymer measured by GPC was 7,000, and PDI was 1.63.

  5,000 parts of methanol was placed in a 10 L beaker, and the core polymer solution was added while stirring at 1,500 rpm using a disper to precipitate the core polymer to obtain a polymer slurry. The resulting polymer slurry was filtered and then washed with methanol and water. It was made to dry for 24 hours with a 70 degreeC dryer, and core polymer CP-6 was obtained.

  In a reaction vessel similar to the reaction vessel described above, 600 parts of BDG and 40 parts of core polymer CP-6 were placed and heated to 80 ° C. to dissolve the core polymer CP-6. After TBAI 14.6 parts was added and dissolved, 360 parts of dicyclopentenyloxyethyl methacrylate (manufactured by Hitachi Chemical Co., Ltd .: FA-512M, hereinafter abbreviated as FA512M) and 0.8 part of TEA were further added. Polymerization was carried out at 6 ° C. for 6 hours to obtain a solution of star polymer S-8. The solid content was 40.4% and the polymerization rate was about 100%. Further, the Mn of the star polymer S-8 measured by GPC was 19,500, and the PDI was 1.88. As the molecular weight increased and the peak of the core polymer CP-6 disappeared, the polymer extended from the branch end of the core polymer CP-6 (the arm part was bonded to the branch end of the core polymer CP-6). I understand).

  Table 2 shows the composition and physical properties of the star polymers prepared in Examples 5 to 8.

<Application Example 1: Application to water-based pigment ink>
(A) Preparation of Yellow Aqueous Pigment Dispersion Solution 345.4 parts of an aqueous solution of star polymer S-5 obtained in Example 5, 105 parts of BDG, and 599.6 parts of ion-exchanged water were mixed to obtain a blue-white translucent solution. Obtained. 350 parts of an azo-based yellow pigment (PY-74, trade name “Seika First Yellow 2016G”, manufactured by Dainichi Seika Kogyo Co., Ltd.) was added to the resulting solution, and stirred for 30 minutes using a disper to prepare a mill base. . Using a horizontal media disperser (trade name “Dynomill 0.6 liter ECM type”, manufactured by Shinmaru Enterprises Co., Ltd., zirconia beads: diameter 0.5 mm), the prepared mill base was dispersed at a peripheral speed of 10 m / s. After sufficiently dispersing the pigment, 544.4 parts of water was added to adjust the pigment concentration to 18%. The mill base taken out from the disperser was centrifuged (7,500 rpm, 20 minutes), filtered through a 10 μm membrane filter, and diluted with water to obtain a yellow aqueous pigment dispersion having a pigment concentration of 14%. .

  The number average particle diameter of the pigment in the obtained yellow aqueous pigment dispersion was 121 nm, and it was confirmed that the pigment was finely dispersed. The number average particle size of the pigment in the dispersion was measured using a particle size measuring device “NICOMP 380ZLS-S” (manufactured by International Business). The yellow aqueous pigment dispersion had a viscosity of 3.2 mPa · s and a pH of 8.8. The viscosity of the dispersion was measured using an E-type viscometer. The number average particle diameter of the pigment in the yellow aqueous pigment dispersion after storage at 70 ° C. for one week was 120 nm, and the yellow aqueous pigment dispersion had a viscosity of 3.1 mPa · s. This shows that the storage stability of the yellow aqueous pigment dispersion is very good.

(B) Preparation of Yellow Aqueous Pigment Ink Each component was mixed according to the formulation shown in Table 3 and sufficiently stirred, and then filtered through a membrane filter having a pore size of 10 μm to prepare a yellow aqueous pigment ink for inkjet.

(C) Evaluation of Dischargeability of Yellow Aqueous Pigment Ink The prepared yellow aqueous pigment ink was filled in a cartridge and mounted on an ink jet printer (trade name “EM930C”, manufactured by Seiko Epson Corporation). Using this inkjet printer, printing was performed on a dedicated photo glossy paper (PGPP), Xerox paper (4024, manufactured by Xerox Co., USA), and a dedicated photo matte paper in a printing mode of 720 dpi. As a result, it was confirmed that the prepared yellow aqueous pigment ink could be ejected from the inkjet nozzles without any problem.

<Application Example 2: Application to UV-curable Pigment Ink>
(A) Preparation of white pigment dispersion 24.9 parts of an aqueous solution of star polymer S-6 obtained in Example 6, 66.7 parts of isobornyl acrylate, and titanium oxide (trade name “JR-405”, Taca 100 parts) (mixed product, number average particle size 240 nm) were mixed and stirred for 2 hours using a dissolver. After confirming that the pigment (titanium oxide) lump had disappeared, it was dispersed using a horizontal media disperser to obtain a white pigment dispersion. The obtained white pigment dispersion was passed through a 10 μm filter and a 5 μm filter. At this time, there was no filter “that is”. The number average particle diameter of the pigment in the obtained white pigment dispersion was 223 nm. The viscosity of the white pigment dispersion was 10.2 mPa · s.

(B) Evaluation of sedimentation property of white pigment dispersion The obtained white pigment dispersion was put in a light-shielded glass bottle and left in a thermostatic bath set at 60 ° C. for 1 month. The number average particle diameter of the pigment in the white pigment dispersion after standing was 201 nm, and the viscosity of the white pigment dispersion was 10.1 mPa · s. Moreover, the supernatant was not produced at all. That is, no change in physical properties due to storage was observed, and it was confirmed that high dispersion stability was maintained. A slightly viscous precipitate was observed, but when shaken, it returned to the original white pigment dispersion. The number average particle size of the sediment was 204 nm, but it was confirmed that the precipitate was dispersed again and returned to a good dispersion state.

(C) Preparation of UV curable pigment ink Each component was mixed according to the formulation shown in Table 4, and after sufficient stirring, filtered sequentially with a membrane filter with a pore size of 10 μm and a membrane filter with a pore size of 5 μm, and ultraviolet rays for inkjet A curable white pigment ink was prepared. The number average particle diameter of the pigment in the obtained ink was 176 nm, and the viscosity of the ink was 5.7 mPa · s. The obtained ink was put in a brown sample bottle and left in a thermostat set at 60 ° C. for 1 month. The number average particle diameter of the pigment in the ink after standing was 177 nm, and the viscosity of the ink was 5.7 mPa · s. Moreover, the supernatant and sediment were not confirmed. From the above, it was found that the storage stability of the ultraviolet curable white pigment ink was also good.

(D) Evaluation of Dischargeability of UV Curable Pigment Ink The prepared UV curable white pigment ink was filled in a cartridge and loaded in an ink jet printer (trade name “EB100”, manufactured by Konica Minolta). Using this ink jet printer, solid images were printed on a polyethylene terephthalate (PET) film continuously for 1 hour. As a result, it was confirmed that printing can be performed smoothly without clogging of the head, and there is no streaking or twisting in the solid image, and excellent ejection stability is exhibited.

<Application Example 3: Application to Color Filter (CF) Pigment Ink>
(A) Preparation of Green Pigment Dispersion Solution 150 parts of the aqueous solution of star polymer S-7 obtained in Example 7, 416.7 parts of propylene glycol monomethyl ether acetate (PGMAc), and Pigment Green 58 (trade name “FASTOGEN GREEN A110”) “, DIC Corporation) 100 parts were mixed and stirred for 2 hours using a dissolver. After confirming the absence of the pigment (Pigment Green 58) lump, it was dispersed using a horizontal media disperser to obtain a pigment dispersion. The obtained pigment dispersion was sequentially filtered through a 10 μm filter and a 5 μm filter to obtain a green pigment dispersion. In addition, no filter “that is” occurred. The pigment concentration of the obtained green pigment dispersion was 15%. The number average particle size of the pigment in the green pigment dispersion was 30 nm, and the viscosity of the green pigment dispersion was 5.8 mPa · s.

(B) Preparation of CF Green Pigment Ink Each component was mixed according to the formulation shown in Table 5 and sufficiently stirred to prepare a CF green pigment ink. The “photosensitive acrylic resin varnish” in Table 5 is a varnish containing an acrylic resin obtained by reacting glycidyl methacrylate with a BzMA / MAA copolymer. Mn of this acrylic resin was 6,000, PDI was 2.38, and the acid value was 110 mgKOH / g.

(C) Production of green glass substrate A glass substrate treated with a silane coupling agent was set on a spin coater. The prepared green pigment ink for CF was spin-coated on a glass substrate at 300 rpm for 5 seconds, and then prebaked at 80 ° C. for 10 minutes. Subsequently, it exposed with the light quantity of 100 mJ / cm < ² > using the ultrahigh pressure mercury lamp, and produced the green glass substrate. The produced green glass substrate (color glass substrate) had excellent spectral curve characteristics and excellent fastness such as light resistance and heat resistance. The color glass substrate was also excellent in optical properties such as light transmittance and contrast ratio.

<Application Example 4: Application to Carbon Nanotube (CNT) Aqueous Dispersion>
(A) Preparation of CNT aqueous dispersion CNT (average diameter: 10 nm, average length: 1.5 μm, using MWNT), mixed solution of water and BDG (water: BDG = 75: 25), S-5 as a dispersant Preparation of CNT aqueous dispersion using was carried out. In a 200 mL polycup, 2.0 parts of CNT (average diameter: 10 nm, average length: 1.5 μm, using MWNT), 70.1 parts of ion-exchanged water, 23.4 parts of BDG, and the star shape obtained in Example 5 6.6 parts of an aqueous solution of polymer S-5 (resin solid content: 30.4%) were added. The amount of the star polymer S-5 was 100% by mass ratio with respect to CNT. At this stage, the CNTs were wet but were sinking to the bottom of the polycup and the top was transparent. A stirrer was placed in a polycup and stirred with a magnetic stirrer, and then ultrasonic waves were applied for 60 minutes using an ultrasonic disperser with an output of 1200 Hz. By irradiating with ultrasonic waves, the liquid became uniformly black, and the CNT aggregation state was released. Then, the CNT which could not be fully disperse | distributed was centrifuged and separated (removed), and the CNT aqueous dispersion liquid was obtained.

(B) Physical property evaluation of CNT aqueous dispersion The sample for measurement was prepared by diluting the CNT aqueous dispersion so that the absorbance could be measured. On the other hand, a calibration curve was prepared by measuring the absorbance of a sample having a known CNT concentration using a spectrophotometer. And while measuring the light absorbency of the prepared sample for a measurement, CNT density | concentration (actual value;%) was computed from the created calibration curve. Moreover, the state after standing CNT aqueous dispersion for one month was confirmed visually. The results are shown in Table 6.

  As shown in Table 6, by using the star-shaped polymer produced in the examples, a high concentration CNT aqueous dispersion in which CNTs are stably dispersed without agglomerates even when left standing for a long period of time is obtained. I was able to.

<Application Example 5: Application to Cellulose Nanofiber (CNF) Dispersed Resin Composition>
(A) Preparation of CNF Add 19,400 parts of water to 600 parts of softwood bleached kraft pulp (refiner treated, solid content 25%) to prepare an aqueous suspension (slurry) with a pulp slurry concentration of 0.75% did. The prepared slurry was subjected to mechanical defibrating using a bead mill. It dehydrated with a filter press to obtain 570 parts of water-containing CNF-1 (solid content: 25%).

(B) Preparation of CNF-dispersed resin composition 24.8 parts of an aqueous solution of the star polymer S-8 obtained in Example 8 were dissolved in 25 parts of DMDG. After adding 0.2 part of a cationic surfactant (oleylamine acetate), 50 parts of ion-exchanged water was added dropwise with uniform stirring to obtain 100 parts of an aqueous dispersion treating agent. The concentration of the star polymer S-8 in the obtained aqueous dispersion treatment agent was 10%.
100 parts of an aqueous dispersion treating agent was added to 40 parts of CNF-1 (solid content: 25%) and mixed well to obtain a readily dispersible cellulose composition (CNS-1).

  40 parts of the obtained CNS-1 in a state where 80 parts of fine particle polyethylene (trade name “Flow Beads HE3040”, manufactured by Sumitomo Seika Co., Ltd., hereinafter referred to as “PE”) is wetted with 50 parts of ion-exchanged water. Was added to obtain a mixture. The resulting mixture was filtered and dried to remove water and DMDG. As a result, 95 parts of a CNF-dispersed resin composition which was a mixed composition of CNF-1 treated with the star polymer S-8 and PE was obtained.

(C) Evaluation of CNF-dispersed resin composition The CNF-dispersed resin composition was biaxially extruded and kneaded under the condition of a kneading temperature of 140 ° C and discharged in a strand shape. After cooling, cutting was performed with a pelletizer to obtain PE resin pellets in which CNF-1 was dispersed. The obtained PE resin pellets were injection molded to produce dumbbell pieces (dumbbell thickness: 2 mm). Using the produced dumbbell piece as a sample for evaluation, a tensile tester (trade name “Universal Tester 5900” series, manufactured by Instron) was used to conduct a tensile test at a tensile speed of 10 mm / min, and a tensile elastic modulus. And the tensile strength was measured. As a result, it was found that the CNF-dispersed resin composition produced using the star polymer produced in the example as a filler dispersant was excellent in mechanical properties and highly dispersed in PE. .

  The star polymer of the present invention includes, for example, a binder as a coating film forming component, a viscosity modifier, a rheology control agent, a filler dispersant such as a pigment dispersant, a thickener, a slip agent, a water repellent, an oil repellent, a high It is useful as a functional surface treatment agent, a mold release agent, a compatibilizing agent, an impact resistance improving agent, a rigidity improving agent, a reinforcing agent, a DDS (drug delivery system) carrier, a refractive index adjusting agent, an ultraviolet absorber and the like.

Claims (10)

A first monomer component containing a monomer represented by the following general formula (1) is polymerized under conditions in which a compound capable of generating iodide ions is present, and a branch having a group capable of living radical polymerization at the branch end Step 1 for obtaining a core polymer having a structure;
The obtained second polymer component including the core polymer and the (meth) acrylic acid monomer is polymerized under a condition in which a compound capable of generating iodide ions is present, and the core polymer and the core polymer Step 2 of obtaining a star polymer having a plurality of arm portions including a structural unit derived from the (meth) acrylic acid monomer bonded to a branch end;
A process for producing a star polymer having

(In the general formula (1), Y represents an arbitrary organic group)   The method for producing a star polymer according to claim 1, wherein the first monomer component further contains a methacrylic acid monomer.   The method for producing a star polymer according to claim 1 or 2, wherein the content of the structural unit derived from the monomer represented by the general formula (1) in the core polymer is 5 to 50% by mass.   The method for producing a star polymer according to any one of claims 1 to 3, wherein the first monomer component and the second monomer component are each polymerized under a condition in which an organic amine is further present.   The star polymer manufactured by the manufacturing method of the star polymer as described in any one of Claims 1-4.   The star polymer according to claim 5, wherein the content of the core polymer is 50% by mass or less. The number average molecular weight in terms of polystyrene of the core polymer measured by gel permeation chromatography is 1,000 to 20,000,
The star polymer according to claim 5 or 6, wherein the number average molecular weight in terms of polystyrene measured by gel permeation chromatography is 10,000 to 1,000,000.   The core polymer has at least one group selected from the group consisting of a hydroxyl group, an acidic group, an amino group, a quaternary ammonium base, an aromatic ring group, an alkyl group having 8 to 18 carbon atoms, and an alkoxysilyl group. The star polymer according to any one of claims 5 to 7, comprising a structural unit derived from a methacrylic acid monomer.   The star polymer according to any one of claims 5 to 8, which is used as a filler dispersant. A dispersion medium;
At least one filler selected from the group consisting of organic pigments, inorganic pigments, carbon nanotubes, and nanocellulose;
A filler dispersant for dispersing the filler in the dispersion medium,
A filler dispersion in which the filler dispersant is the star polymer according to claim 9.