JP2007041246A - Toner kneading machine, toner manufacturing method, and electrophotograph toner manufactured by using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner kneading machine and a toner manufacturing method that can improve the grindability by reducing the density of the kneaded object to be discharged, and provide thus manufactured toner. <P>SOLUTION: A continuous two-roll kneading machine 100 has an outer cooler 12 obliquely above the front roll 2 at the opposite side of the back roll 1 with respect to the front roll 2 to partially cool the surface of the melted material sticking to the front roll 2 by blowing cold air. In this configuration, fine air gaps can be made in the material when contact kneading by cooling it from the outside before it is in contact with the back roll 1 within the heat medium area of the front roll 2. Thus, the apparent density of the kneaded object is lowered to be discharged, and the grindability can be improved. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a toner kneading apparatus and a toner manufacturing method used for electrophotography, electrostatic printing, and the like, and a toner manufactured thereby, and particularly relates to a dry type.

  In electrophotography, generally, a photoconductive substance is used, and an electric latent image is formed on a photoconductor by various methods, and then the latent image is developed using toner. There are known methods for forming an image by transferring a toner image onto a transfer material such as paper and then fixing it by various methods.

  A dry toner is a powder that forms an image. However, in order to form an image accurately, it is necessary to impart a number of functions to the toner particles. For example, chargeability, transportability, fixability, coloring power, storage stability, and the like. Therefore, the toner is prepared as a mixture of various raw materials. Examples of the dry toner production method include a pulverization method, a polymerization method, and an encapsulation method. In general, the pulverization method occupies the mainstream.

  As a method for producing toner by a general pulverization method, a raw material comprising additives such as a binder resin for fixing to a transfer material, various colorants for producing a color, and a charge control agent is dry-mixed, After that, the mixed powder is melt-kneaded with a compressive force and shear force while applying temperature in a general-purpose kneading device such as a twin-screw extruder, a kneader, or a continuous two-roll kneading device, and cooled. After solidification, coarse pulverization is performed as necessary to produce a kneaded coarse pulverized powder, and then fine pulverization is performed to a suitable particle size as a toner using a fine pulverization apparatus such as a jet mill. Then, if necessary, the particles are classified by various classifiers, and the particle size is made uniform in a particle size distribution capable of exhibiting sufficient performance as a toner. Further, if necessary, a fluidity improver, a lubricant and the like are dry-mixed to complete a usable toner.

  Here, as one of the factors related to the toner performance, there is a charge amount distribution. The charge amount distribution depends on the amount of the colorant and charge control agent, but also greatly depends on the dispersion of the colorant and charge control agent.

  The dispersion state of the toner particles of the various raw materials in the toner is substantially determined by the raw material mixing step and the kneading step in the toner production step by the pulverization method. As a device used for mixing raw materials, a container rotating type mixer such as a V blender or a W corn blender or a high speed stirring type mixing device such as a Henschel mixer is usually used and adjusted by these devices. The mixed powder as a mixture is melt kneaded by a kneader or a twin screw extruder.

  However, the kneaded product obtained by the above-described production method has an insufficient dispersion state of the colorant and the charge control agent in the binder resin, so that the charge amount distribution is large and has a reverse polarity different from the desired charge. There are many charged toners, and printed images using these toners have problems such as fogging. Further, in the color toner, since the dispersion of the colorant is insufficient, the transmittance of the OHP film is deteriorated and the image is blurred.

  Therefore, recently, in order to improve the dispersibility of the colorant and charge control agent in the binder resin, a continuous two-roll kneading device (continuous) having a shearing force stronger than that of the aforementioned kneader or twin screw extruder. (Also called a two-roll mill). Such a continuous two-roll kneading apparatus is described in (Patent Document 1).

  5A and 5B are diagrams showing an outline of a conventional continuous two-roll kneading apparatus, in which FIG. 5A is a side view of the entire apparatus, and FIG. 5B is a conceptual view of the roll portion as viewed from above.

  In FIG. 5, 100 is a conventional continuous two-roll kneading apparatus. The continuous two-roll kneading apparatus 100 is provided with two rolls, 1 being a back roll and 2 being a front roll. 3 is a toner material supply unit, and 4 is a kneaded material discharge unit. Reference numerals 5 and 6 denote roll drive motors, and reference numerals 8, 9, 10, and 11 denote heating medium supply and discharge portions of the back roll 1 and the front roll 2, respectively.

The kneaded material kneaded by such a continuous two-roll kneader 100 has a good dispersion state of the colorant and the charge control agent in the binder resin, and the kneaded material is pulverized and classified. The printing characteristics of the toner are also good.
JP 2001-154408 A

  However, when a conventional continuous two-roll kneading apparatus is used, when a mixed powder that is a mixture of a binder resin, a colorant, and the like is supplied to the conventional continuous two-roll kneading apparatus 100, The kneaded material is discharged in a high density state by melt solidification. When this is finely pulverized by a pulverizer, the degree of kneaded material to be crushed with respect to a constant impact energy is less likely to be crushed as the density of the non-ground material is higher.

  On the other hand, a method of lowering the kneading temperature and reducing the density of the kneaded product by making it in an incompletely melted state and improving the pulverization property can be considered, but this method increases the melt viscosity of the mixture and increases the mobility of the material. As a result, the dispersibility of the colorant and charge control agent in the binder resin deteriorates.

  The present invention solves the above-mentioned conventional problems, and provides a toner kneading apparatus and a toner production method capable of improving the pulverization property by reducing the density of the discharged kneaded material, and It is an object of the present invention to provide a toner manufactured using the above toner manufacturing method.

  In order to solve the above-described problems, the present invention is a continuous two-roll type toner kneading apparatus in which a mixture containing at least a binder resin and a colorant is heated and melt-kneaded by rotation of a front roll and a back roll. A toner kneading device comprising a cooling device for cooling the front roll surface other than the contact portion with the back roll from the outside in the heat medium region of the front roll.

  According to the toner kneading device of the present invention, the cooling device cools the surface of the front roll other than the contact portion with the back roll in the heat medium region of the front roll. Since fine voids can be woven into this, the density of the discharged kneaded material is lowered, so that the pulverizability can be improved.

  The invention according to claim 1 of the present invention is a continuous two-roll type toner kneading apparatus in which a mixture containing at least a binder resin and a colorant is heated and melt-kneaded by rotation of a front roll and a back roll. A toner kneading device comprising a cooling device for cooling the front roll surface other than the contact portion with the back roll from the outside in the heat medium region of the front roll.

  The cooling device cools the exposed material portion on the surface of the front roll other than the contact portion with the back roll in the heat medium area of the front roll, so that the material can be added to the material during re-contact kneading between the front roll and the back roll after cooling. Fine voids can be woven. By weaving fine voids in the material, the density of the discharged kneaded material is lowered, so that the grindability is improved. The temperature of the cooling device can be adjusted freely, and the supplied mixture can be melt-kneaded without lowering the mobility of the material to be kneaded, so that it can be bound with sufficient shearing force. Dispersibility of a colorant or the like in the resin can be improved. Accordingly, the dispersion state of the colorant and the like in the binder resin of the kneaded product becomes good.

  According to a second aspect of the present invention, in the first aspect of the present invention, the cooling device is an air cooling device.

  According to the third aspect of the present invention, a mixture containing at least a binder resin and a colorant is melt-kneaded by the toner kneading apparatus according to the first aspect of the present invention, and the melt-kneaded kneaded product is pulverized and classified. The toner manufacturing method is characterized by the fact that the density of the kneaded material discharged by cooling and weaving fine voids in the material is lowered, and the pulverizability can be improved. Therefore, since the dispersibility of the colorant or the like in the binder resin can be improved with a sufficient shearing force, the dispersion state of the colorant or the like in the binder resin of the kneaded product should be good. Can do. In addition, the yield in the toner manufacturing process can be improved, and a high-quality toner with a stable charge amount can be manufactured.

  According to a fourth aspect of the present invention, there is provided a toner manufacturing method comprising melting and kneading a mixture by the toner kneading apparatus according to the second aspect of the present invention, and pulverizing and classifying the kneaded mixture. .

  The invention according to claim 5 of the present invention is a toner manufactured using the toner manufacturing method according to claim 3 of the present invention, and the manufactured toner is a dispersion of a colorant or the like in the binder resin. Since the state is good, the charge amount is stable, and it is possible to eliminate defects in the printed image such as fogging, and in the case of color toner, the deterioration of the transmittance of the OHP film and the blurring of the image are prevented. be able to.

(Embodiment)
Embodiments of the present invention will be described below.

  FIG. 1 is a diagram showing an outline of a continuous two-roll kneading apparatus according to an embodiment of the present invention, where (a) is a side view of the entire apparatus, and (b) is a concept of the roll part as viewed from above. FIG. FIG. 2 is a roll sectional view of the continuous two-roll kneading apparatus in the embodiment of the present invention.

  In FIG. 1, 100 is a continuous two-roll kneading apparatus. The continuous two-roll kneading apparatus 100 is provided with two rolls, 1 being a back roll and 2 being a front roll. 3 is a toner material supply unit, and 4 is a kneaded material discharge unit. Reference numerals 8, 9, 10, and 11 denote heat medium supply / discharge sections of each roll, and reference numerals 5 and 6 denote roll drive motors. Reference numeral 12 denotes a cooling device.

  As shown in FIG. 2, the back roll 1 and the front roll 2 of the continuous two-roll kneading apparatus 100 are hollow inside, along the inner peripheral surface on the inner peripheral side of the roll surface. A pipe 7 formed in a spiral shape is provided.

  As shown in FIG. 1, the spiral pipe 7 includes a heat medium supply / discharge section which is a temperature control heat medium machine capable of controlling the temperature at both ends of both the front roll 2 and the back roll 1. 8, 9, 10 and 11, respectively. Therefore, the surface temperature in each roll of the back roll 1 and the front roll 2 is arbitrarily controlled by supplying a heat medium such as steam, hot water, oil, or a cooling medium such as cooling water to these temperature control heat medium machines. It is a possible structure. Moreover, as shown in FIG.1 (b), both the back roll 1 and the front roll 2 are formed in the cylindrical shape which has the helical groove | channel on the surface.

  The cooling device 12 is an air cooling device that partially cools the surface layer of the material melted and adhered to the front roll 2 by blowing cool air, and is opposite to the back roll 1 side with respect to the front roll 2. And provided at a position obliquely above the front roll 2.

  Next, a toner kneading method and a toner manufacturing method using the continuous two-roll kneading apparatus 100 in the present embodiment will be described.

  First, raw materials containing at least a binder resin and a colorant are mixed in a container rotating type mixer such as a V blender or a high-speed agitation type mixer such as a Henschel mixer, and the resulting mixed powder is a mixed powder. The body is quantitatively continuously supplied to the toner material supply unit 3 of the continuous two-roll kneading apparatus 100 shown in FIG. 1 using a screw feeder or the like.

  Next, as shown in FIG. 2, the mixture supplied to the toner raw material supply unit 3 of the front roll 2 is supplied with heat supplied to a spiral pipe 7 on the inner peripheral side of the roll surface of the hollow part of the front roll 2. Heated by the heat transfer action of the medium, the binder resin melts and adheres to the surface of the front roll 2. Similarly, the toner is easily melted and adheres to the surface of the front roll 2 by the heat transfer action from the back roll 1 heated by the spiral pipe 7 in the hollow portion.

  Thus, the mixture adhering to the surface of the front roll 2 without dropping is melt-kneaded by rotating the front roll 2 and the back roll 1 inward as shown by the arrows in FIG. Is done. And in the state which adhered to the front roll 2 and the back roll 1 by the screw effect of the helical groove | channel provided in the surface of the back roll 1 and the front roll 2 shown by FIG. 1 (a), (b), It is transferred in the direction (from left to right in FIG. 1B).

  When the melted deposit is transferred in this way, the melted deposit on the surface of the front roll other than the contact portion with the back roll is opposite to the back roll 1 side with respect to the front roll 2, Cooling is performed by a cooling device 12 provided at a position obliquely above the front roll 2. The melted adhering material is kneaded while being subjected to a rapid compressive force and a shearing force of the roll rotation in the gap between the back roll 1 and the front roll 2 again while weaving fine voids in the material by being cooled. Is done. And it transfers to the kneaded material discharge part 4 as a kneaded material. Thus, by kneading the material while weaving fine voids, the density of the discharged kneaded material decreases.

  Here, the operating conditions of the continuous two-roll kneading apparatus 100 will be described. The rotation speed of the roll is preferably 50 rpm or more in order to have a strong shearing force, and 150 rpm or less in order not to generate extreme heat generation or the molecular chain of the binder resin. Further, in order to continuously discharge the kneaded material, the kneaded material needs to be attached to the front roll 2 in the vicinity of the kneaded material discharge portion 4, so that the rotation speed of the front roll 2 is the rotation of the back roll 1. It must be equal to or greater than the number.

  After cooling the kneaded material obtained in this way, coarsely pulverized with a cutter mill or the like, then finely pulverized with a jet mill pulverizer, appropriately removed coarse powder and fine powder with a classifier such as an airflow classifier, desired The finished toner is obtained through an external addition step in which an additive is externally added as necessary. In the present embodiment, as described above, since the density of the discharged kneaded material is lowered, the grindability of the kneaded material is improved. Therefore, if the toner kneading apparatus in the present embodiment is used, the toner can be pulverized to a smaller size with the same equipment and low energy, the productivity is improved, and a high-quality toner can be manufactured.

  Next, the toner material used in the toner kneading apparatus and the toner manufacturing method in the present embodiment will be described. The toner produced by the toner kneading apparatus and the toner production method in the present embodiment is composed of at least a binder resin and a colorant, and can contain a charge control agent, various additives, and the like in addition to that.

  First, the following resins can be used as the binder resin.

  Polyester resin, epoxy resin, polyol resin, styrene-acrylic resin, polyvinyl chloride, phenolic resin, natural resin modified phenolic resin, maleic acid resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, acrylic phthalate Resin, polyvinyl acetate, silicone resin, polyurethane, polyamide resin, polyvinyl butyral, terpene resin, coumarone indene resin, polycarbonate, fluororesin, aliphatic or aliphatic hydrocarbon resin, aromatic petroleum resin, modified rosin, paraffin Natural waxes, synthetic waxes and the like, and these resins can be used alone or in combination of two or more.

  For example, styrenes such as styrene, chlorostyrene, α-methylstyrene, vinyl styrene, monoolefins such as ethylene, propylene, butylene, isobutylene, vinyl acetate, vinyl propionate, vinyl benzoate, vinyl butyrate, etc. Acrylic acid alkyl esters such as vinyl esters, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate And vinyl ethers such as alkyl methacrylates, vinyl methyl ether, vinyl ethyl ether and vinyl butyl ether, vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropenyl ketone. Homopolymers or copolymers of emission and the like can be mentioned.

  Typical examples thereof include styrene such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene, and homopolymers thereof, styrene-p-chlorostyrene copolymers, styrene-vinyltoluene copolymers, styrene-vinylnaphthalene. Copolymer, styrene-alkyl acrylate ester copolymer, styrene-alkyl methacrylate ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer Styrene copolymers such as styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic anhydride copolymer Coalescence, polyethylene, Len - vinyl acetate copolymer, ethylene copolymers such as ethylene vinyl alcohol copolymer, and polypropylene. These homopolymers or copolymers can be used alone or in combination of two or more.

  Among the binder resins described above, the polyester resin has a sharp melting suitability and good fixability. Further, it is possible to improve the color developability and durability as a toner, which is particularly preferable.

  The weight average molecular weight of the polyester resin is preferably 10,000 or more and 20,000 or less. That is, if it is less than 10000, there is a problem that a so-called offset phenomenon in which the toner is transferred to the fixing roller occurs in the toner fixing step, and if it is more than 20000, there is a problem that the melting suitability is deteriorated and fixing failure occurs. It is not preferable.

  Furthermore, as the colorant used in the toner kneading apparatus and the toner manufacturing method of the present embodiment, any organic or inorganic pigment or dye is used.

  As pigments, disazo pigments, insoluble azo pigments, azo lake pigments, copper phthalocyanine pigments and the like can be used. As dyes, azo dyes, anthraquinone dyes, xanthene dyes, methine dyes basic Dyes such as dyes and oil-soluble dyes can be used. These pigments and dyes can be used alone or in admixture of two or more.

  The pigments include phthalocyanine blue, indanthrene blue, peacock blue, first sky blue, indanthrene blue, aniline blue, calcoil blue, ultramarine blue, permanent red, watching red calcium salt, brilliant carmine, lake red. , Rose Bengal, Naphthol Yellow, Hansa Yellow, Rhodamine Yellow, Hansa Yellow, Permanent Yellow, Benzidine Yellow, Naphthol Yellow, Chrome Yellow, Quinoline Yellow, Carbon Black, Aniline Black, Acetylene Black, Lamp Black, Alizarin Lake, Bengala, Rhodamine Lake , Permanent orange, pyrazolone orange, benzine orange, malachite green oxalate, key Kuridon, fast violet, methyl violet lake, as a blue dye or pigment of copper phthalocyanine and derivatives thereof, C. I. Pigment blue 15: 3, C.I. I. Pigment blue 15, C.I. I. Pigment Blue 16, red or red pigments include C.I. I. Pigment Red 5, C.I. I. Pigment Red 3, C.I. I. Pigment Red 2, C.I. I. Pigment Red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 57, C.I. I. Pigment red 122, C.I. I. Pigment red 9, C.I. I. Pigment red 48, C.I. I. Pigment red 48: 3, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 112, C.I. I. Pigment red 149, C.I. I. Pigment red 170, C.I. I. Pigment red 168, C.I. I. Pigment red 188, C.I. I. Pigment red 194, C.I. I. Pigment red 175, C.I. I. Pigment red 208, C.I. I. Pigment red 187, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 81, C.I. I. Pigment red 122, C.I. I. Pigment Red 49: 1, benzimidazolone monoazo pigment, C.I. I. Pigment yellow 151, C.I. I. Pigment yellow 154, C.I. I. Pigment yellow 156, C.I. I. Pigment yellow 120, C.I. I. Pigment Yellow 175, an acetoacetic acid arylamide-based disazo yellow pigment, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 17, C.I. I. Pigment Yellow 83, an isoindolinone pigment, C.I. I. Pigment yellow 110, C.I. I. Pigment yellow 109, C.I. I. Pigment yellow 137, C.I. I. Pigment Yellow 173, an acetoacetic acid arylamide monoazo yellow pigment, C.I. I. Pigment yellow 1, C.I. I. Pigment yellow 3, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 97, C.I. I. Pigment Yellow 98 can be used.

  Examples of the dye include C.I. I. Direct Blue 1, C.I. I. Direct Blue 2, C.I. I. Acid Blue 9, C.I. I. Acid Blue 15, C.I. I. Basic Blue 3, C.I. I. Basic Blue 5, C.I. I. Modern Blue 7, C.I. I. Direct Red 1, C.I. I. Direct Red 4, C.I. I. Acid Red 1, C.I. I. Basic Red 1, C.I. I. Basic Red 12, C.I. I. Modern Tread 30, C.I. I. Solvent Red 49, C.I. I. Solvent Red 52, C.I. I. Solvent Red 109, C.I. I. Solvent Red 58, C.I. I. Solvent Red 8, C.I. I. Solvent Yellow 19, C.I. I. Solvent Yellow 77, C.I. I. Solvent Yellow 79, C.I. I. Disperse Yellow 164 can be used.

  Next, as the charge control agent, the following charge control agents can be used.

  The charge control agent as the negatively chargeable toner includes, for example, salicylic acid or its derivative chromium / zinc / aluminum / boron complex or salt compound, benzylic acid or its derivative chromium / zinc / aluminum / boron complex or salt compound, tetraphenyl Borates, chromium / azo complex dyes, iron azo complex dyes, cobalt / azo complex dyes, chromium / zinc / aluminum / boron complexes or salt compounds of naphtholic acid or its derivatives, long chain alkyl carboxylates, long chain alkyl sulfones And surfactants such as acid salts.

  Further, charge control agents as positively chargeable toners include cetyltrimethylammonium bromide, quaternary ammonium salts, N, N-dialkylaminoalkyl (meth) acrylates, and N, N-dialkylaminoalkyl (meth) acrylamides. Examples include radically polymerizable copolymers obtained by copolymerizing monomers having nitrogen-containing functional groups, nigrosine dyes and derivatives thereof, derivatives such as triphenylmethane derivatives, quaternary phosphonium salts, quaternary pyridinium salts, guanidine salts, and amidine salts. It is done.

  Further, the toner of the present invention can contain various additives as required.

  Additives include flow improvers, mold release agents, lubricants, fixing aids, cleaning improvers, conductive fillers, extenders, reinforcing fillers such as fibrous substances, antioxidants, anti-aging agents, offsets Examples include inhibitors. Additives are added to satisfy various properties required for the toner or to improve the properties.

  Examples of these additives include oxides, double oxides, inorganic oxides, metal oxides, metals, silicon compounds, carbon, carbon compounds, fullerenes, boron compounds, carbides, nitrides, and ceramics. Examples of the inorganic oxide include silica, titania, alumina, zirconia, zinc oxide, magnesium oxide, cerium oxide, strontium titanate, iron oxide, copper oxide, tin oxide and the like. Further, various waxes such as fluororesin fine particles, silicone resin fine particles, higher fatty acids such as stearic acid, and metal salts thereof such as zinc stearate and aluminum stearate may be added.

  The fluidity improver is an inorganic oxide such as silica, alumina, titania, zirconia, etc., and the surface of these inorganic oxides is a silane compound having a nitrogen element-containing substituent such as aminosilane, or an amino-modified silicone oil, etc. It is preferable that it is hydrophobized with a silicone oil having a nitrogen element-containing substituent. For example, hydrophobic silica can be mentioned. This fluidity improver is preferably added externally to the toner surface.

  Examples of the release agent include low molecular polypropylene, low molecular polyethylene, or waxes such as microstalline wax, carnauba wax, sazol wax, and paraffin wax.

  In addition, waxes such as polyolefin, polyethylene, and polypropylene also function as offset preventing agents.

  Examples of the lubricant include Teflon (registered trademark), zinc stearate, polyvinylidene fluoride and the like, and low molecular weight polyethylene, low molecular weight polypropylene and the like can be added as a fixing aid.

  These additives can be added singly or in combination of two or more as required, and are added internally or externally depending on the purpose.

  Next, the kneaded material discharged by the toner kneading apparatus and the toner manufacturing method in the present embodiment will be described in detail using a comparative example. In addition, this invention is not limited at all by the following examples and comparative examples.

  The toner formulation used in this embodiment is shown below.

Binder resin Polyester resin 91.0 parts by weight (glass transition point: 58 ° C.)
Colorant C.I. I. Pigment Blue 15: 34.5 parts by weight Charge control agent Quaternary ammonium salt 4.5 parts by weight External additive (fluidity imparting agent)
1.0 part by weight of hydrophobic silica (Example 1)
Except for the external additive, 5 kg of the raw material weighed in the proportion of the above formulation was mixed with a Henschel mixer under the conditions of a blade rotation speed of 1400 rpm and a treatment time of 10 minutes to obtain a mixed powder. This mixed powder was supplied to the continuous two-roll kneader 100 in the present embodiment shown in FIG. 1 to obtain a kneaded product discharged after melt kneading. The continuous two-roll kneading apparatus 100 has a roll outer diameter of 140 mm and a roll length of 800 mm, and the two division positions of the heat medium pipe inside the roll are 400 mm from the supply side on the front roll and 200 mm from the supply side on the back roll. It is. The operating conditions of the continuous two-roll kneader 100 are as follows.

Cold air temperature of roll external cooling device 12: 16 ° C.
Roll rotation speed Front roll rotation speed: 70 rpm
Back roll speed: 60 rpm
Heat medium temperature in roll Front roll: Toner raw material supply side: 100 ° C., kneaded product discharge side: 40 ° C.
Back roll: Toner raw material supply side: 90 ° C., kneaded product discharge side: 30 ° C.
Toner raw material supply rate: 10 kg / hour The kneaded product obtained while cooling is coarsely pulverized by a bantam mill having a 2 mm screen, finely pulverized by a turbo mill, and further finely and coarsely powdered by an elbow jet classifier. The toner was removed to obtain a toner having an average particle diameter (D50) of about 9.0 μm.

  The average particle size was measured using a Coulter Counter TA-II type (manufactured by Coulter).

  Further, 1 part by weight of hydrophobic silica was added to 100 parts by weight of the toner particles and mixed and adhered using a Henschel mixer to obtain the cyan toner of Example 1.

(Comparative Example 1)
Except for the continuous two-roll kneading apparatus 100 used and its operating conditions, the toner was produced by the same formulation and method as in Example 1. In Comparative Example 1, the continuous two-roll kneading apparatus 100 has a roll outer diameter of 140 mm and a roll length of 800 mm, and the two division positions of the heat medium pipe inside the roll are from the supply side for both the front roll and the back roll. The operating conditions of the continuous two-roll kneader 100 are 400 mm.

Roll external cooling device: Not used Roll rotation speed Front roll rotation speed: 70 rpm
Back roll speed: 60rpm
Heat medium temperature in roll Front roll: Toner raw material supply side: 100 ° C., kneaded product discharge side: 40 ° C.
Back roll: Toner raw material supply side: 90 ° C., kneaded product discharge side: 30 ° C.
Toner raw material supply rate: 10 kg / hour Further, the discharged material after melt kneading was subjected to the same steps as in Example 1 to obtain a cyan toner of Comparative Example 1.

  The result of having measured the density of the discharge | emission after the melt-kneading of Example 1 and Comparative Example 1 is shown in FIG. In the measurement, the kneaded effluent was immersed in an arbitrary amount of an aqueous surfactant solution, and the apparent density was calculated from the change in the overall weight and volume.

  As shown in FIG. 3, the kneaded discharge of Example 1 had a density drop of about 4% compared to Comparative Example 1. In order to compare the pulverization property, the particle size distribution after pulverization at the same mill rotation speed (7000 rpm) was measured with the turbo mill used for fine pulverization, and the result of the average particle size (D50% diameter of the volume distribution) was obtained. This is also shown in FIG. In Example 1, compared with Comparative Example 1, the average particle size after pulverization was pulverized by about 1.2 μm.

  Next, the toners of Example 1 and Comparative Example 1 were put into a non-magnetic one-component developer and a printing device, and a continuous printing life test for 10,000 sheets was performed. The test results are shown in FIG.

  Here, an evaluation method and evaluation criteria for the evaluation items shown in FIG. 4 will be described.

  The image density stability is for confirming a change with time of the printed image density, and the image density of the first to 10000th printed sheets is measured with a Macbeth densitometer (manufactured by Macbeth Co.). And it evaluated by the difference of the density | concentration change. Fog is a phenomenon of toner flying to the non-image area, and the degree of contamination of the non-image area was visually determined. The solid followability was evaluated visually by checking whether or not blurring of the image occurred in the printing direction when a full solid image was printed. The evaluation in all evaluation items is a three-step evaluation of ◯, Δ, and ×, and the evaluation criteria are ◯: good, Δ: acceptable, ×: poor.

  From the results of the life test, the toners obtained in Example 1 and Comparative Example 1 both have a stable image density, and in addition to the reduction of fog, the followability of the solid image is also good. Furthermore, the stability of the toner charge amount on the developing roller (toner transport roller) of the non-magnetic one-component developer was also good.

  From these apparent density, kneadability comparison and toner life test results of these kneaded discharged products, Example 1 has a lower apparent density and a higher void ratio than Comparative Example 1, so that it is more finely pulverized with the same energy. be able to. The obtained toner was found to be a high quality toner.

  As described above, when the conventional continuous two-roll kneading apparatus is used, the material is placed in a high-temperature molten state so as to adhere to the front roll. The continuous two-roll kneading apparatus 100 according to the embodiment has a surface of the front roll 2 other than the contact part with the back roll 1 in the heating medium region of the front roll 2 in the middle of the process. By locally cooling from the outside and weaving fine voids in the material during contact kneading, the density of the discharged kneaded material can be reduced and the pulverization can be improved, so the same equipment and low energy, The toner can be pulverized smaller, the productivity is improved, and a high-quality toner can be manufactured. In addition, since the toner produced by this toner production method has a good dispersion state of the colorant or the like in the binder resin, the charge amount is stable, and defects in the printed image such as fogging can be eliminated. In addition, the color toner can be a high-quality electrophotographic toner that can prevent deterioration of the transmittance of the OHP film and blurring of the image.

  The present invention is a toner kneading device comprising a cooling device for cooling the front roll surface other than the contact portion with the back roll in the heat medium region of the front roll from the outside. In addition, fine voids can be woven into the material, which is suitable for the field of toner manufacturing apparatus and toner kneading apparatus for the purpose of improving pulverizability.

(A) Side view of the entire device, (b) Conceptual view of the roll part from above Roll sectional view of a continuous two-roll kneading apparatus in an embodiment of the present invention The figure which shows the result of the density and average particle diameter (D50% diameter of volume distribution) of the discharged material after melt-kneading The figure which shows the result of the continuous printing life test of 10,000 sheets (A) Side view of the entire device, (b) Conceptual view of the roll part from above

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Back roll 2 Front roll 3 Toner raw material supply part 4 Kneaded material discharge part 5 Roll drive motor 6 Roll drive motor 7 Spiral pipe 8 Heat medium supply / discharge part 9 Heat medium supply / discharge part 10 Heat medium supply / discharge part 11 Heat medium Supply / discharge unit 12 External cooling device 100 Continuous 2-roll kneading device

Claims (5)

A continuous two-roll type toner kneading apparatus that heats a mixture containing at least a binder resin and a colorant and melts and kneads the mixture by rotating a front roll and a back roll,
A toner kneading apparatus comprising a cooling device for cooling the front roll surface other than the contact portion with the back roll in the heat medium region of the front roll from the outside. 2. The toner kneading apparatus according to claim 1, wherein the cooling device is an air cooling device. A continuous two-roll type toner kneading device that heats a mixture containing at least a binder resin and a colorant, and melts and kneads by rotation of a front roll and a back roll, and includes a heating medium region of the front roll, A toner characterized in that the mixture is melt-kneaded by a toner kneader provided with a cooling device for cooling the front roll surface other than the contact portion with the back roll from the outside, and the melt-kneaded kneaded product is pulverized and classified Production method. The toner manufacturing method according to claim 3, wherein the cooling device is an air cooling device. A continuous two-roll type toner kneading device that heats a mixture containing at least a binder resin and a colorant, and melts and kneads by rotation of a front roll and a back roll, and includes a heating medium region of the front roll, The mixture was manufactured by melt-kneading the mixture by a toner kneading device equipped with a cooling device that cools the front roll surface other than the contact portion with the back roll from the outside, and pulverizing and classifying the melt-kneaded mixture. Features toner.

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