JP4754062B2 - Method for producing resin particles - Google Patents

Description

【００５３】
【表２】

【００５４】
この結果、得られた樹脂粒子の溶媒中における平均粒子径は８０ｎｍであった。この樹脂粒子の溶媒中における平均粒子径は、動的光散乱測定装置（ＤＬＳ−７００、大塚電子製）にて測定した（以下の実施例、比較例においても同様に測定した）。なお、この最終の重合率は８０％であった。
【００５５】
実施例１
参考例１において、重合系にカーボンブラックグラフトポリマー（ＧＣＢ）を配合する以外は参考例１と同様にして、下記表４の組成にて、着色樹脂粒子を合成した。なお、ＧＣＢ液の作製は、上記のグラフトポリマーを反応ポリマーとして作製したものを用い、下記表３の組成にて９０℃で２時間アトライターを使用し作製した。
【００５６】
【表３】

【００５７】
また、重合開始剤アゾイソブチロニトリル（ＡＩＢＮ）は、重合系に用いた溶媒と同じ溶媒に溶解し、系を７０℃に昇温後、３０分後に添加した。
【００５８】
【表４】

【００５９】
この結果得られた重合系において、得られた着色樹脂粒子の溶媒中における平均粒子径は２２４ｎｍであり、元々のＧＣＢの平均粒子径は１４０ｎｍであったため、目的とする粒子が得られた。
【００６０】
なお、この最終の重合率は９２％であった。
【００６１】
比較例１
カーボンブラックグラフトポリマーの代わりにカーボンブラック２０部を界面活性剤（スパン８０（商品名）；花王株式会社製）５部を利用してアイソパーＭ（エクソン社製の商品名）７５部中に分散させた分散液１５部を用いて実施例１と同様の重合系の組成で着色樹脂の合成を行った。その結果、カーボンの凝集物と白濁したエマルションが分離した形で生成した。
【００６２】
比較例２
カーボンブラックグラフトポリマー（ＧＣＢ）１５部と参考例１で合成したポリ酢酸ビニル系エマルション８５部を混合した場合、安定な黒色分散液が作製された。
【００６３】
しかしながら、得られた分散液を遠心分離機を用いて粒子を沈降させた際、ＧＣＢの粒子と白濁したエマルションの上澄みができた。実施例１の場合、遠心分離後の上澄みは透明であり、樹脂がＧＣＢに覆われた着色微粒子が得られており、重合過程で着色微粒子が合成できたことがわかった。
【００６４】
【発明の効果】
以上述べたように、本発明によれば、非水溶媒中において凝集が起こらず、再分散性も良好な樹脂粒子を得ることができる。また、本発明の方法によれば、帯電調節剤等の添加物の添加によっても粒子分散状態は変わらず良好であり、得られる樹脂粒子の電気抵抗率・帯電性を簡単に制御できる。さらに、分散性が良好であるため、分散体の粘度も非常に低い。このため、例えば、電子写真用液体現像剤の調整において、好適に用いることのできる原料となる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to colored resin fine particles and a method for producing the same. The present invention relates to colored resin fine particles dispersed in a non-aqueous solvent, particularly for use in electrophotographic liquid developers, inks, paints, and the like, and a method for producing the same.
[0002]
[Prior art]
A liquid developer for electrophotography (liquid toner) in which colorant-containing resin particles are dispersed in a highly insulating non-aqueous solvent can be made on demand, and compared with a dry developer, Since the particle size can be reduced, it is possible to improve the image quality and reproducibility of a fixed image, and applications in fields such as industrial printers and high-speed high-performance copying machines are expected.
[0003]
Such a liquid developer includes a highly insulating non-aqueous solvent serving as a medium, various pigments represented by carbon black, colorants such as dyes, and the like. Contains a resin component that imparts fixability, a dispersant for dispersing the colorant-containing resin particles in a non-aqueous solvent, a charge control agent that adjusts the polarity and charge amount of the colorant-containing resin particles, and other components Composition.
[0004]
Examples of the dispersion in which the colorant-containing resin particles are dispersed in a non-aqueous solvent include, for example, dry pulverization of a kneaded product of a resin component and a colorant, and a ball mill or paint shaker together with the non-aqueous solvent in which the dispersant is dissolved. It is known that a concentrated dispersion is prepared by dispersing to a target particle size using a wet disperser such as a sand mill and becomes a master batch, and this concentrated dispersion is diluted as it is or with a solvent. In order to obtain the polarity of the phase, a charge adjusting agent is added as necessary.
[0005]
Alternatively, in the presence of a polymer soluble in the non-aqueous solvent in a non-aqueous solvent, a monomer that is soluble in the non-aqueous solvent but becomes insoluble by polymerization is polymerized to form resin particles. There is also known a method of adding the resin particle dispersion to a non-aqueous solvent containing a charge control agent together with a colorant adsorbed on or separately dispersed.
[0006]
However, in these methods, there is a limit to reducing the particle size, and mechanical dispersion treatment and granulation treatment are necessary, and the dispersion stability of the resin particles in the obtained composition is insufficient. It was.
[0007]
In addition, as a method for producing such a resin particle dispersion, (1) carbon black dispersed by adding a poor solvent to a polymer solution completely dissolved in a good solvent using changes in the solubility of the polymer, and others (2) a method of dispersing an aqueous colorant in a non-aqueous medium by a phase inversion method using an emulsifier (phase inversion method), and (3) a semi-liquid state. A method of kneading and dispersing a self-dispersible graft block polymer and carbon black with a three roll and dispersing them in a non-aqueous medium (Japanese Patent Laid-Open No. 3-188469), (4) a block having a hydrophobic block and a hydrophilic block A method of producing microcapsules by a surface polymerization method in a non-aqueous medium using a protective colloid made of a polymer (Japanese Patent Laid-Open No. 7-246329) It is.
[0008]
However, in coacervation, the solvent resistance of the polymer greatly depends on the temperature, and at a high temperature, the polymer swells and dissolves in the solvent, so that the fusion of the polymer proceeds and the colored particles aggregate and cannot be redispersed.
[0009]
When the colorant is dispersed from an aqueous system to a non-aqueous system by the phase inversion method, the addition of additives used to adjust electrical resistance and chargeability may destroy the dispersion system, making it difficult to control the electrical resistance value and chargeability. It becomes.
[0010]
The microencapsulation using the interfacial polymerization method has a problem in that resin fine particles are synthesized separately from the colorant in the polymerization process because the pigment as the colorant and the resin to be coated are not compatible.
[0011]
[Problems to be solved by the invention]
Therefore, an object of the present invention is to provide a novel resin particle and a method for producing the same. Another object of the present invention is to provide resin particles that are stably dispersed in a non-aqueous medium, do not cause aggregation, and have good redispersibility, and a method for producing the same. The present invention further provides particle sizes from submicron order to 10²Disclosed is a resin particle which can be freely controlled in a micron order range and a method for producing the same. Another object of the present invention is to provide resin particles capable of freely changing the ratio of a polymer component contained in the particles and a pigment such as carbon black, and a method for producing the same. Further, the present invention further includes a colorant having desired characteristics such as the particle surface being controllable, the chargeability and surface resistance being freely controllable, particularly high resistance and positive charge. Provided are resin particles capable of producing particles and a method for producing the same.
[0012]
[Means for Solving the Problems]
In the present system, the present inventors use a dispersion resin grafted to a colorant for the purpose of increasing the compatibility between the colorant and the resin to be coated by post-polymerization, and the dispersion stabilizer for the resin in which the dispersion resin is post-polymerized As a result, it has been found that colored fine particles can be synthesized by incorporating a colorant, and the present invention has been completed.
[0013]
That is, the present invention for solving the above problems is (1) In a non-aqueous solvent, a monomer that is soluble in the non-aqueous solvent and becomes insoluble by polymerization is polymerized to be dispersed in the non-aqueous medium. In the method for producing resin particles,
A resin characterized in that the monomer is polymerized in the presence of a block or graft copolymer insoluble in the non-aqueous solvent and has self-dispersibility to produce resin particles dispersed in the non-aqueous medium. A method for producing particles.
[0014]
The present invention also provides (2) producing colored resin particles dispersed in a non-aqueous medium by polymerizing the monomer in the presence of a colorant dispersed in the non-aqueous solvent. This is the method described in (1) above.
[0015]
The present invention further includes (3) a segment (A) in which the colorant particle surface has an affinity for the non-aqueous solvent and a segment (B) having a lower affinity for the non-aqueous solvent than the segment (A). The method according to (2) above, wherein a polymer-grafted colorant modified with a block or a graft copolymer chain is used as the colorant.
[0016]
This invention which solves the said subject is (4) Resin particle | grains with an average particle diameter of 50 nm-10 micrometers characterized by the method obtained by the method as described in said (1).
[0017]
This invention which solves the said subject is (5) Colored resin particle with an average particle diameter of 50 nm-10 micrometers characterized by the method of the said (2) or (3) description.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail based on specific embodiments.
[0019]
The present invention provides a method for producing resin particles dispersed in a non-aqueous medium by polymerizing a monomer that is soluble in the non-aqueous solvent and becomes insoluble by polymerization in a non-aqueous solvent. Resin particles characterized by producing resin particles dispersed in a non-aqueous medium by polymerizing the monomers in the presence of a block or graft copolymer insoluble in a solvent and having self-dispersibility It is a manufacturing method.
[0020]
The non-aqueous solvent used in the present invention is not particularly limited, and for example, hydrocarbon solvents, hexane, benzene and the like can be used, but particularly high insulating properties (10⁹Isoparaffin hydrocarbons having an electrical resistance of Ωcm or more, Isopar M, Isopar L, Isopar H (all trade names of Exxon) and the like are preferable.
[0021]
The block or graft copolymer that is insoluble in the non-aqueous solvent and has self-dispersibility used in the present invention has a simple structure such as an AB block copolymer or an AB graft copolymer. Without limitation, a B-A-B type block copolymer or a more advanced alternating block copolymer, a comb-type graft copolymer in which a plurality of B segments are grafted onto an A segment, and a star-shaped graft copolymer. Various types such as polymers are included. Similarly, the graft copolymer includes various forms.
[0022]
Insoluble in a non-aqueous solvent and having self-dispersibility means that the block or graft copolymer is left in a non-aqueous solvent in a solid state without using mechanical stirring or the like. This means that the particles are dispersed in a solvent so as to dissolve naturally, and the average particle size of the dispersed particles in the non-aqueous solvent of the block or graft copolymer is, for example, 5 to Those having a thickness of 400 nm, particularly about 5 to 150 nm are desirable. The dispersion stability of the obtained resin particles in the non-aqueous solvent depends greatly on the dispersed particle size of the block or graft copolymer.
[0023]
Specific examples of the block or graft copolymer that is insoluble in the non-aqueous solvent and has self-dispersibility greatly depend on the type of the non-aqueous solvent to be used. A combination of a polymer unit having affinity for a non-aqueous solvent and a non-affinity, for example hydrophilic polymer unit, for a non-aqueous solvent. For example, isoparaffin as described above as a non-aqueous solvent. In the case of using a hydrocarbon, the former polymer unit is, for example, a long-chain hydrocarbon having about 6 to 40 carbon atoms, such as a polymer of a monomer having a stearyl group, while the latter polymer unit. May be a polymer of a monomer having a cyclic structure such as a benzene ring, a naphthalene ring or an indene ring, for example, a styrene skeleton.
[0024]
Specific examples of the monomer that forms the former polymer unit include stearyl acrylate, stearyl methacrylate, hexadecyl acrylate, hexadecyl methacrylate, heptadecyl acrylate, heptadecyl methacrylate, nonadecyl acrylate, and nonadecyl methacrylate. Aralkyl acrylate, aralkyl methacrylate, behenyl acrylate, behenyl methacrylate, pentasil acrylate, pentasil methacrylate, heptacyl acrylate, heptacyl acrylate, nonacyl acrylate, nonacyl methacrylate, doteracyl acrylate, doteracyl methacrylate, etc. is there. Of these, stearyl acrylate, behenyl acrylate, behenyl methacrylate, pentasil acrylate, pentasil methacrylate and the like are particularly preferable. Specific examples of the monomer forming the latter polymer unit include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p- Examples thereof include styrene monomers such as tert-butylstyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, and p-chlorostyrene. However, as a matter of course, the monomers forming the former and latter polymer units are not limited to those exemplified above as long as the finally obtained block or graft copolymer can exhibit the desired characteristics. It is not limited. For example, as a comonomer in any unit, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, dodecyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, α- Amorphous acrylic ester or amorphous such as methyl chloroacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate Methacrylic acid ester monomers; acrylic acid monomers such as acrylonitrile, methacrylonitrile and acrylamide; vinyl ether monomers such as vinyl methyl ether, vinyl isobutyl ether and vinyl ethyl ether Mer; vinyl ketone monomers such as vinyl methyl ketone, vinyl ethyl ketone, vinyl hexyl ketone; N-vinyl compound monomers such as N-vinyl pyrrole, N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidone; other, ethylene It is possible to use various vinyl monomers such as propylene, butylene, vinyl chloride and vinyl acetate.
[0025]
The monomer that is soluble in the non-aqueous solvent and becomes insoluble by polymerization will naturally vary depending on the non-aqueous solvent used. For example, when an isoparaffinic hydrocarbon as described above is used as the non-aqueous solvent. Monomers such as various acrylic methacrylic esters, styrene, and vinyl acetate can be used.
[0026]
Furthermore, in the present invention, the monomer is polymerized in the coexistence of the colorant dispersed in the non-aqueous solvent to produce colored resin particles dispersed in the non-aqueous medium. It is the manufacturing method of the resin particle characterized.
[0027]
The pigment that is one of the colorants that coexists in such a polymerization system is not particularly limited, and may be an organic pigment, an inorganic pigment, or a mixture thereof.
[0028]
Examples of inorganic pigments include alumina, titanium dioxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, silica sand, clay, mica, wollastonite, diatomaceous earth, and various inorganic oxide pigments. , Chromium oxide, cerium oxide, bengara, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silica fine powder, silicon carbide, silicon nitride, boron carbide, tungsten carbide, titanium carbide, cerium oxide, Examples thereof include powder or particles such as carbon black. Further, such an inorganic pigment may be treated with a known hydrophobizing agent such as a titanium coupling agent, a silane coupling agent or a higher fatty acid metal salt.
[0029]
Examples of organic pigments include yellow pigments such as navel yellow, naphthol yellow S, hanzer yellow G, hanzer yellow 10G, benzidine yellow G, benzidine yellow GR, quinoline yellow lake, permanent yellow NCG, and tartrazine lake. Orange pigments such as Liveden Orange, Permanent Orange RK, Benzidine Orange G, Indanthrene Brilliant Orange GK, Permanent Red 4R, Risor Red, Pyrazolone Red 4R, Watching Red Calcium Salt, Lake Red D, Brilliant Carmine 6B, Eomin Lake, Rhodamine Lake Red pigments such as B, buzzalin lake, brilliant carmine B, purple pigments such as fast violet B, methyl violet lake, alkali blue , Victoria Blue Lake, Phthalocyanine Blue, Metal-free Phthalocyanine Blue, Phthalocyanine Blue Partial Chloride, Fast Sky Blue, Indanthrene Blue BC and other blue pigments, Pigment Green B, Malachite Green Lake, Final Yellow Green G and other green pigments Etc.
[0030]
These organic pigments may also be treated pigments having improved dispersibility using a dispersion aid or the like.
[0031]
However, as the colorant used in the present invention, the colorant particle surface has a segment (A) having an affinity for the non-aqueous solvent and a segment having a lower affinity for the non-aqueous solvent than the segment (A). It is desirable to use a polymer grafted colorant modified with a block or graft copolymer chain having (B).
[0032]
As a pigment which is one kind of such a colorant, it is added to a non-aqueous solvent as described above and self-dispersed, and the same polymer chain as a block or graft copolymer which functions as a kind of polymerization stabilizer is used. It is desirable to be a surface-modified polymer grafted colorant.
[0033]
In the following, the present invention will be described focusing on an embodiment in which carbon black is used as a pigment and a polymer is combined with the carbon black.
[0034]
The carbon black used in producing the carbon black graft polymer according to the present invention is not particularly limited as long as it has a functional group such as a carboxyl group or a hydroxy group on the surface thereof. For example, furnace black, channel black, Any kind of acetylene black, lamp black and the like can be used, and ordinary commercial products can be used as they are, but among them those having a carboxyl group are preferred. Further, it is preferable to use carbon black having a pH of less than 7, particularly pH 1 to 5. Carbon black having a carboxyl group can be easily obtained as acidic carbon black, but carbon black obtained by oxidizing neutral or basic carbon black can also be suitably used as a raw material in the present invention. When carbon black does not have a functional group such as a carboxyl group, or when the pH is 7 or higher, grafting may not be performed effectively. In addition, the test method of the pH of carbon black is based on JISK6211.
[0035]
The average particle size of carbon black is preferably in the range of 0.0005 to 0.4 μm, particularly 0.001 to 0.2 μm. Since carbon black having an average particle diameter of less than 0.0005 μm cannot be easily obtained, it has little industrial significance. When the average particle diameter exceeds 0.4 μm, sufficient dispersibility may not be imparted to the obtained carbon black graft polymer.
[0036]
  On the other hand, the polymer used to form a polymer portion by being grafted to such carbon black is a segment having a reactive group capable of reacting with a functional group on the surface of carbon black (B), And substantially free of the reactive group and the segment (B) Segments with higher affinity for non-aqueous solvents thanAAnd a polymer of block type or graft type.
[0037]
  In such block or graft polymers, segments (B) The reactive group contained therein is not particularly limited as long as it can contribute to grafting of the polymer to carbon black by reacting with a functional group present on the surface of carbon black. Sex groups can be used.
[0038]
Here, in order to make the grafting more reliable and stable, it is desired that the polymer portion is bonded to the carbon black through a covalent bond, in particular, an ester bond, a thioester bond, an amide bond, an amino bond, An at least one bond selected from the group consisting of an ether bond, a thioether bond, a carbonyl bond, a thiocarbonyl bond and a sulfonyl bond, and at least one bond selected from the group consisting of an ester bond, a thioester bond and an amide bond It is desirable to be. Considering such points, the reactive group is preferably at least one or more selected from the group consisting of an epoxy group, a thioepoxy group, an aziridine group, an N-hydroxyacrylamide group, and an oxazoline group. . Although the reactive group with respect to carbon black is not necessarily limited to these, when the polymer which has groups other than these reactive groups is used, the kind of carbon black which can be used may restrict | limit. The reason why it is preferable that the polymer has the reactive group is that carbon black and the polymer are added with very high grafting efficiency even under mild conditions regardless of the type and state of carbon black that can be used. It is to react. In particular, when carbon black has a carboxyl group as a surface functional group as described above, the carboxyl group is irreversible in high yield by thermal reaction with an epoxy group, a thioepoxy group, an aziridine group, an N-hydroxyacrylamide group or an oxazoline group. An addition reaction is performed, and this addition reaction is desirable because the above-described covalent bond is formed between the carbon black portion and the polymer portion.
[0039]
  In addition, a polymer (segment (B(Part)) will be described later.
[0040]
  Segments with such reactive groups (B) Must have a low affinity for the target medium due to its segment chain structure. Note that the low affinity here means that the other segment (A) And relative to the target media type or segment (A) Depending on the composition of the segment (B) Can have various configurations, and cannot be specified in general. However, from another point of view, the segment (B) Is desirable to have a high affinity for carbon black because it shows better orientation to carbon black. From this point, the segment (B) Has a main chain mainly composed of a carbon-carbon bond, more preferably an aromatic ring such as a benzene ring, naphthalene ring or indene ring in the main chain, and the reaction as described above. Having a functional group in the molecule, while the segment (A) Is the segment (BIt is desirable to include a large amount of a skeleton structure having less aromatic rings than (1), for example, a linear structure such as a long-chain hydrocarbon.
[0041]
  As mentioned above, the segment (B) Is a segment selected from the aspect of dispersibility to be imparted to carbon black (A) In accordance with the chain structure, for example, various vinyl polymers by styrene monomer, (meth) acrylic monomer, alkylene monomer alone or by copolymerization, Although it can be a polymer chain (having the above-mentioned reactive group) such as polyester and polyether, among these, a vinyl polymer, particularly a vinyl monomer component having an aromatic ring, is more preferably 50 mol% or more. Is a vinyl polymer containing 60 mol% or more and having a reactive group, and various segments selected according to the liquid medium to be used (A) Is possible because it can be combined.
[0042]
Further, in consideration of economy and the like, in particular, a styrene monomer and a (meth) acrylic monomer as a main or copolymer, especially a styrene monomer component is 50 mol% or more, and further 60 mol. A polymer chain containing at least% (having the above reactive group) is desirable.
[0043]
  Meanwhile, segment (A), For example, a polysiloxane structure, a poly (meth) acrylic structure, a polyether structure such as polyalkylene glycol, a polyester structure, or a polyalkylene structure in consideration of dispersibility in the non-aqueous medium used. An appropriate polymer chain having a polyamide structure, a polyimide structure, a polyurethane structure, etc. is selected. As described above, when an isoparaffin hydrocarbon is used as a solvent, a long chain such as a stearyl group is used as an ester group. A polymer unit of a vinyl monomer such as a (meth) acrylic monomer having a hydrocarbon group is desirable.
[0044]
  Segments with such reactive groups (B) And a segment with high affinity for the liquid medium used (A) Is not particularly limited, and it may be produced by appropriately combining known polymer polymerization techniques such as various block or graft types and reactive polymer production techniques. Can do.
[0045]
As a method for obtaining a graft-type polymer, for example, a polymerization initiator and a polymerizable monomer are mainly polymerized by solution polymerization, emulsion polymerization, bulk polymerization or suspension polymerization in the presence of a high molecular weight polymer to be a graft chain. A method of polymerizing a chain polymer is known. However, if the high molecular weight material does not have a radical polymerizable functional group, the resulting graft copolymer contains a large amount of ungrafted polymer, and has the disadvantage that the graft efficiency is low. Yes. Therefore, it is preferable to use a radical polymerizable high molecular weight as the high molecular weight. Such a radical polymerizable high molecular weight substance is generally referred to as a “macromonomer” and is a high molecular weight substance having a radical polymerizable group at one end, for example, a (meth) acryloyl group, a styryl group, etc. It is obtained by reacting a polymer having a carboxyl group at one end with a radical polymerizable monomer having a glycidyl group in an organic solvent (for example, Japanese Patent Publication No. 43-11224 discloses a method in which an organic solvent is used). A method is disclosed in which a prepolymer obtained by radical polymerization of a radically polymerizable monomer in the presence of mercaptoacetic acid and glycidyl methacrylate are reacted in the presence of a dimethyllaurylamine catalyst.
[0046]
  Thus, for example, to obtain the graft copolymer according to the present invention, the segment (A) In the presence of the radically polymerizable high molecular weight as described above as a component for forming a polymerizable monomer having a reactive group for carbon black in the molecule and other segments (if necessary) (BThe polymerizable monomer that forms the skeleton of) may be polymerized.
[0047]
In the method for producing resin particles according to the present invention, in 100 parts by mass of the non-aqueous solvent as described above, a monomer that is soluble in the non-aqueous solvent and becomes insoluble by polymerization, for example, 1 to 100 parts by mass, More preferably 5 to 50 parts by weight, 0.1 to 50 parts by weight of a block or graft copolymer insoluble in the non-aqueous solvent and having self-dispersibility, more preferably 0.1 to 20 parts by weight, further required Accordingly, 0.1 to 50 parts by weight, more preferably 1 to 20 parts by weight of the colorant as described above is blended, and the temperature is adjusted to a temperature of about 30 to 150 ° C., which is a polymerization temperature, and a polymerization initiator, for example, Polymerization can be carried out by adding a known amount of a known azo-based or peroxide-based material, for example, about 0.1 to 10 parts by mass with respect to 100 parts by mass of the monomer.
[0048]
The resin particles obtained as a result of such a polymerization reaction have a very small particle diameter of 50 nm to 10 μm, particularly 50 nm to 5 μm, and can be stably dispersed in the non-aqueous solvent. For example, it can be suitably used as a raw material in the production of an electrophotographic liquid developer.
[0049]
【Example】
Hereinafter, the present invention will be described in detail based on examples. In the following, “part” means part by mass unless otherwise specified.
[0050]
  referenceExample 1
  A ternary copolymer (stearyl macromonomer-styrene-isopropyl oxazoline copolymer) was synthesized in toluene in a separable flask equipped with a temperature sensor, a stirring blade, and a cooling tube with the composition shown in Table 2 below.
[0051]
Thereafter, using the terpolymer (1) as a stabilizer, resin particles were synthesized by polymerization of vinyl acetate in the composition shown in Table 1 below. The temperature of the polymerization system was 75 ° C., and the polymerization time was 8 hours. The polymerization initiator azoisobutyronitrile was directly added after raising the temperature of the system.
[0052]
[Table 1]

[0053]
[Table 2]

[0054]
As a result, the average particle diameter of the obtained resin particles in the solvent was 80 nm. The average particle diameter of the resin particles in the solvent was measured with a dynamic light scattering measuring device (DLS-700, manufactured by Otsuka Electronics Co., Ltd.) (also measured in the following Examples and Comparative Examples). The final polymerization rate was 80%.
[0055]
  Example1
  referenceIn Example 1, except that carbon black graft polymer (GCB) is blended in the polymerization systemreferenceIn the same manner as in Example 1, colored resin particles were synthesized with the composition shown in Table 4 below. The GCB liquid was prepared by using an attritor at 90 ° C. for 2 hours with the composition shown in Table 3 below, using the graft polymer prepared as a reaction polymer.
[0056]
[Table 3]

[0057]
The polymerization initiator azoisobutyronitrile (AIBN) was dissolved in the same solvent as that used in the polymerization system, and the system was heated to 70 ° C. and added 30 minutes later.
[0058]
[Table 4]

[0059]
In the polymerization system obtained as a result, the average particle diameter of the obtained colored resin particles in the solvent was 224 nm, and the average particle diameter of the original GCB was 140 nm. Thus, the target particles were obtained.
[0060]
The final polymerization rate was 92%.
[0061]
  Comparative Example 1
  Instead of the carbon black graft polymer, 20 parts of carbon black is dispersed in 75 parts of Isopar M (trade name, manufactured by Exxon) using 5 parts of a surfactant (Span 80 (trade name); manufactured by Kao Corporation). Example using 15 parts of the dispersion1A colored resin was synthesized with the same composition of the polymerization system. As a result, carbon agglomerates and white turbid emulsions were formed in a separated form.
[0062]
  Comparative Example 2
  15 parts of carbon black graft polymer (GCB)referenceWhen 85 parts of the polyvinyl acetate emulsion synthesized in Example 1 was mixed, a stable black dispersion was produced.
[0063]
  However, when particles were sedimented from the obtained dispersion using a centrifuge, the supernatant of GCB particles and a cloudy emulsion was formed. Example1In the case of, the supernatant after centrifugation was transparent, and colored fine particles covered with GCB were obtained. It was found that the colored fine particles could be synthesized in the polymerization process.
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【The invention's effect】
As described above, according to the present invention, resin particles that do not aggregate in a non-aqueous solvent and have good redispersibility can be obtained. In addition, according to the method of the present invention, the particle dispersion state is good even when an additive such as a charge control agent is added, and the electric resistivity and chargeability of the resulting resin particles can be easily controlled. Furthermore, since the dispersibility is good, the viscosity of the dispersion is also very low. For this reason, it becomes a raw material which can be used suitably, for example in the adjustment of the electrophotographic liquid developer.

Claims (1)

In the presence of a colorant dispersed in a non-aqueous solvent, it is soluble in the non-aqueous solvent in the presence of a block or graft copolymer that is insoluble in the non-aqueous solvent and has self-dispersibility, and A method for producing colored resin particles dispersed in a non-aqueous medium by polymerizing a monomer that becomes insoluble by polymerization,
A block or graft copolymer chain in which the colorant particle surface has a segment (A) having an affinity for the non-aqueous solvent and a segment (B) having a lower affinity for the non-aqueous solvent than the segment (A) A polymer grafted colorant modified with is used as the colorant,
The colorant particles are carbon black,
The segments (A) is Po Li (meth) polymer chains having an acrylic structure,
The segment (B) is a styrenic monomer having in the molecule at least one reactive group selected from the group consisting of an epoxy group, a thioepoxy group, an aziridine group, an N-hydroxyacrylamide group, and an oxazoline group, It is a polymer chain of a vinyl polymer, polyester or polyether obtained by homo- or copolymerization of a (meth) acrylic monomer or an alkylene monomer,
The non-aqueous solvent is an isoparaffinic hydrocarbon,
The block or graft copolymer insoluble in the non-aqueous solvent and having self-dispersibility includes a polymer unit having affinity for the non-aqueous solvent and a polymer having non-affinity for the non-aqueous solvent. The former polymer unit is a polymer of a monomer having a long chain hydrocarbon group having 6 to 40 carbon atoms, and the latter polymer unit is a polymer of a monomer having a cyclic structure. A block or graft copolymer,
The method for producing colored resin particles, wherein the monomer that is soluble in the non-aqueous solvent and becomes insoluble by polymerization is at least one of acrylic acid ester, methacrylic acid ester, styrene, and vinyl acetate.