JP3991037B2 - Toner production method - Google Patents

Description

  The present invention relates to a method for producing a toner used for developing a latent image formed in an electrophotographic method, an electrostatic recording method, an electrostatic printing method or the like.

  As factors relating to the performance of the color toner, there are fog and white stripes. The fog and white stripes are influenced by the amount of the charge control agent, but also greatly depend on the dispersion state of the charge control agent of the color toner particles. The dispersion state of various raw materials of the color toner particles is substantially determined by the step of mixing the raw materials and the step of kneading in the method for producing the color toner by the pulverization method.

  In order to solve this problem, a technique for controlling the dispersibility of a colorant or the like using an open roll type continuous kneader or a kneading extruder provided with supply ports at a plurality of positions is known (Patent Document 1). 2).

JP 2000-75543 A (Claim 1) JP-A-3-149567 (Claim 1)

  However, in the technique of Patent Document 1, it is not easy to sufficiently disperse the charge control agent due to the importance of producing a toner excellent in dispersion of the colorant. This method has a drawback that it cannot sufficiently disperse the colorant, charge control agent, wax and the like required for the color toner as the temperature of the composition rises due to heat of kneading. Until now, sufficient investigation has not been made on the dispersibility of the charge control agent.

  An object of the present invention is to provide a toner manufacturing method in which the dispersibility of a charge control agent is controlled and fog and white stripes do not occur when printing is performed.

  The present invention is a method for producing a toner comprising a step of melt kneading a raw material containing a binder resin, a charge control agent, a colorant and a wax using an open roll type continuous kneader having heating and cooling functions. In the melt-kneading, 70 to 100% by weight of the binder resin to be blended and 60 to 90% by weight of the charge control agent are 0.3 L from the end of the roll on the inlet side of the kneader (where L is the roll length) The present invention relates to a toner production method in which melt kneading is performed at a position between

  In the present invention, since the dispersibility of the charge control agent in the toner can be controlled, it is possible to produce a toner that does not cause fogging or white streaks when printed.

  In the present invention, at least a binder resin, a charge control agent, a colorant and a wax are used as raw materials. By using an open roll type continuous kneader having heating and cooling functions when melt kneading the raw material, it is possible to produce a toner with excellent dispersibility of additives such as charge control agents, colorants, waxes, In addition, when supplying raw materials from multiple supply ports, by controlling the blending ratio of the binder resin and charge control agent, it is possible to control the dispersibility of the charge control agent and prevent white streaks and fog from occurring It is possible to produce an excellent toner.

  As the open roll type continuous kneader used in the present invention, the raw material is supplied to a plurality of positions along the axial direction of the roll to the open roll type continuous kneader in which two rolls are arranged close to each other in parallel. What provided the mouth is preferable.

Each roll can be heated or cooled by passing a heat medium. That is, one can be a heating roll and adjusted to a temperature near the melting temperature of the binder resin, and the other roll can be a cooling roll and adjusted to a temperature equal to or lower than the melting temperature of the binder resin. The melting temperature (Tm) is a Koka-type flow tester (CFT-500, manufactured by Shimadzu Corporation), with a die diameter of 1 mm, a length of 1 mm, a load of 20 kg / cm ² G A temperature corresponding to ½ of the height of the outflow end point from the outflow start point when a 1 cm ³ sample is melted out under the condition of a temperature rate of 6 ° C./min.

  The gap between the two rolls is preferably 0.1 to 10 mm, more preferably 0.1 to 3 mm. Moreover, there is no limitation in particular about the structure of each roll, a magnitude | size, material, etc., The roll surface may be smooth and may be a wave type, an uneven | corrugated type, etc.

  The peripheral speed of the roll is preferably 2 to 100 m / min, and the rotation speed ratio of the two rolls (the rotation speed of the cooling roll / the rotation speed of the heating roll) is 1/10 to 9/10. Is preferred.

  Feeding the raw material between the upper surface of the roll or between the two rolls from the supply ports provided at a plurality of positions along the axial direction of the roll while rotating the two rolls inward and in opposite directions, respectively. It is preferable to perform kneading. The kneading force can be appropriately adjusted depending on the kneading temperature and the number of roll rotations.

  In addition, supply of the raw material to an open roll type continuous kneader can be performed using, for example, a table feeder. Moreover, you may premix each raw material using a mixing apparatus, before supplying a raw material. The mixing device is not particularly limited, and high-speed stirring type mixing such as Henschel mixer (Mitsui Mine), super mixer (Kawata), high-speed mixer (Fukae Kogyo), Ladige mixer (Matsubo), etc. Apparatus.

  Examples of the binder resin used in the present invention include polyester, styrene-acrylic resin, a mixed resin of polyester and styrene-acrylic resin, and a hybrid resin in which two or more resin components are partially chemically bonded. From the viewpoint of the dispersibility of the control agent, it is preferable to use polyester as a main component. The content of the polyester in the binder resin is preferably 50 to 100% by weight, and more preferably 70 to 100% by weight. The hybrid resin is preferably a resin in which a condensation polymerization resin such as polyester, polyester / polyamide, polyamide or the like and an addition polymerization resin such as vinyl polymerization resin are chemically bonded, and two or more kinds of resins are used as raw materials. In order to obtain a hybrid resin efficiently, two or more types of resins may be used. Those obtained from a mixture of raw material monomers are preferred.

  The raw material monomer of the polyester is not particularly limited, and a known alcohol component and a known carboxylic acid component such as carboxylic acid, carboxylic acid anhydride, or carboxylic acid ester are used.

  Examples of the alcohol component include polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane and polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane. Bisphenol A alkylene (2 to 3 carbon atoms) oxide (average number of added moles 1 to 16) adduct, ethylene glycol, propylene glycol, glycerin, pentaerythritol, trimethylolpropane, hydrogenated bisphenol A, sorbitol, or alkylene thereof (C2-C4) oxide (average addition mole number 1-16) adduct etc. are mentioned.

  The carboxylic acid component includes dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, fumaric acid, maleic acid, adipic acid and succinic acid, alkyl groups having 1 to 20 carbon atoms such as dodecenyl succinic acid and octenyl succinic acid, or carbon. Trivalent or higher polyvalent carboxylic acids such as succinic acid, trimellitic acid and pyromellitic acid substituted with alkenyl groups of 2 to 20, anhydrides of these acids and alkyls of these acids (1 to 3 carbon atoms) ) Esters and the like.

  The polyester can be produced, for example, by subjecting an alcohol component and a carboxylic acid component to condensation polymerization at a temperature of 180 to 250 ° C. in an inert gas atmosphere, if necessary, using an esterification catalyst.

  When the toner obtained by the present invention is used as a positively chargeable toner, the acid value of the polyester is preferably 0.5 to 15 mgKOH / g, more preferably 1 to 12 mgKOH / g, and particularly preferably 1.5 to 10 mgKOH / g. preferable.

  When the toner is used as a negatively chargeable toner, the acid value of the polyester is preferably 5 to 40 mgKOH / g, more preferably 10 to 35 mgKOH / g, and particularly preferably 15 to 30 mgKOH / g.

  Moreover, the softening point of polyester is preferably 80 to 165 ° C, and the glass transition point is preferably 50 to 85 ° C.

  From the viewpoint of obtaining a sufficient residence time and controlling the degree of dispersion of the charge control agent or the like, the binder resin accounts for 70 to 100% by weight, preferably 80 to 90% by weight, of the open roll type continuous kneader. The sheet is supplied to a position between 0.3 L (L indicates the roll length) from the end of the roll on the side. When a plurality of binder resins are used, the supply position can be changed in accordance with the desired degree of dispersion. In addition, the binder resin may be supplied from one supply port at a time, or may be divided and supplied from one or a plurality of supply ports. More preferably, the remaining binder resin supplied between 0.3 L and preferably 0.2 L from the end of the roll is supplied at a position exceeding 0.3 L and up to 0.6 L. By adjusting the amount of the binder resin at the site, the dispersibility of the charge control agent can be controlled by adjusting the concentration of the charge control agent in the kneaded product.

  Specific examples of the charge control agent used in the present invention include a positive chargeability such as a nigrosine dye, a triphenylmethane dye containing a tertiary amine as a side chain, a quaternary ammonium salt compound, a polyamine resin, and an imidazole derivative. Examples include charge control agents, metal-containing azo dyes, aromatic hydroxycarboxylic acid metal complexes, copper phthalocyanine dyes, metal complexes of alkyl derivatives of salicylic acid, and negatively chargeable charge control agents such as organoboron compounds. Depending on the properties, they may be used alone or in combination, but in the present invention, since the charge rising property is particularly good, the formula (I):

(Wherein, X ^{n +} represents a cation, and n represents an integer of 1 or 2)
The organic boron compound represented by these is preferable.

In the formula (I), examples of the cation represented by X ^{n +} include alkali metals such as potassium and sodium, alkaline earth metals, ammonium ions and the like. Among these, from the viewpoint of charging stability, an alkali metal is used. preferable.

As a commercial item of the organic boron compound represented by the formula (I), there is “LR-147” (manufactured by Nippon Carlit Co., Ltd., benzyl acid boron compound, X ^{n +} : potassium (K ⁺ )) and the like.

  5-100 micrometers is preferable and, as for the average particle diameter of the charge control agent used for this invention, 5-50 micrometers is more preferable. In general, a charge control agent having a relatively large average particle size has a small number of particles in one toner particle, and the dispersibility of the charge control agent greatly affects the performance of the printed matter. It is difficult to control. However, in the present invention, even when a charge control agent having a large average particle size is used, the dispersibility of the charge control agent in the present invention can be appropriately controlled. In addition, the average particle diameter of the charge control agent can be obtained by a measurement method described later.

  The blending amount of the charge control agent is preferably 0.5 parts by weight or more, more preferably 1 part by weight or more from the viewpoint of charge stability with respect to 100 parts by weight of the binder resin. From the viewpoint of charge rising property, it is preferably adjusted to be less than 2 parts by weight, more preferably 1.8 parts by weight or less.

  The charge control agent is added in an amount of 60 to 90% by weight, preferably 75 to 90% by weight, in accordance with the desired degree of dispersion, from the roll end of the kneader at the entrance side of the kneader to 0.3 L, preferably 0.8. Supply to a position between 2L. When a plurality of charge control agents are used, the supply position can be changed according to the desired degree of dispersion. In addition, the charge control agent may be supplied from one supply port at a time, or may be supplied separately from one or a plurality of supply ports. The effect of the charge control agent increases as the degree of dispersion increases, but the effect decreases as the degree of dispersion increases further. Therefore, it is preferable to control the dispersion degree so as to obtain an optimum dispersion degree of the charge control agent to be used. More preferably, the remaining binder resin supplied between 0.3 L from the roll end is supplied at a position exceeding 0.3 L and up to 0.6 L.

  The blending weight ratio (charge control agent / binder resin) when supplying the binder resin and the charge control agent to a position between 0.3 L from the roll end of the kneader is 0.5 / 100 to 5/100. Is preferable, 0.7 / 100 to 3/100 is more preferable, and 0.9 / 100 to 2/100 is more preferable.

  0.5-3 weight part is preferable with respect to 100 weight part of binder resin, and, as for the total compounding quantity of a charge control agent, 1-2 weight part is more preferable.

  The colorant used in the present invention is not particularly limited to dyes, pigments and the like used as toner colorants. Black colorants, yellow pigments, red or red pigments, blue pigments, green pigments These colorants may be used alone or in combination of two or more. The toner obtained by the present invention may be any of color toners such as black toner, monocolor toner, and full color toner. However, in the case of producing a color toner, the effect of the present invention is more remarkably exhibited, which is preferable. .

  From the viewpoint of improving the degree of dispersion, the colorant is preferably 70 to 100% by weight, more preferably 80 to 100% by weight, 0.3L from the roll end on the inlet side of the kneader of the kneader, preferably It is preferable to supply to a position between 0.2L. When a plurality of colorants are used, the supply position can be changed according to the desired degree of dispersion. In addition, the colorant may be supplied from one supply port at a time, or may be supplied separately from one or a plurality of supply ports.

  The colorant supplied to the position between 0.3 L from the roll end of the kneader is preferably 3 to 20% by weight in the total amount of raw material supplied to the position between 0.3 L from the roll end. Weight percent is more preferred.

  The total blending amount of the colorant is preferably 1 to 10 parts by weight and more preferably 2 to 5 parts by weight with respect to 100 parts by weight of the binder resin.

  Examples of the wax include natural wax and synthetic wax, silicone type, higher fatty acid, polyolefin type, low molecular weight polymer and the like. Among these, natural wax is preferably used, and specific examples include carnauba wax, rice wax, candelilla wax, beeswax and the like.

  The wax is preferably supplied from one or more supply ports at a position between 0.9 L from the end of the roll on the inlet side of the kneader according to the desired degree of dispersion. When a plurality of waxes are used, the supply position can be changed according to the desired degree of dispersion. In addition, the wax may be supplied from one supply port at a time, or may be supplied separately from one or a plurality of supply ports.

  The total amount of the wax is preferably 2 to 15 parts by weight and more preferably 4 to 8 parts by weight with respect to 100 parts by weight of the binder resin.

  Furthermore, in the present invention, additives such as fluidity improvers, conductivity modifiers, extender pigments, reinforcing fillers such as fibrous substances, antioxidants, anti-aging agents, and cleaning improvers are appropriately used as toner raw materials. You may mix | blend.

  The kneaded material obtained by the above melt-kneading process can be continuously taken out from the open roll type continuous kneader, cooled to an extent capable of being pulverized, and then subjected to the pulverization process.

  A cooling belt etc. are mentioned as a cooling device used for cooling. Examples of the pulverizer used for pulverization include a jet mill, a collision plate mill, and a rotary mechanical mill.

  Further, a toner is obtained through a classification process and a surface treatment process in which an external additive such as hydrophobic silica is added to the toner surface as necessary.

  Examples of the classifier used for classification include an air classifier, an inertia classifier, and a sieve classifier. In addition, the fine powder smaller than the target particle diameter removed by classification can be used for the raw material mixing step or the melt-kneading step, and the particles larger than the target particle size can be used again for the pulverization step.

  The volume average particle size of the toner obtained by the present invention is preferably 4 to 12 μm from the viewpoint of productivity and high image quality.

  The toner obtained according to the present invention has an appropriately adjusted dispersibility of the charge control agent, and has an excellent dispersibility of the colorant and the wax as the dispersibility of the charge control agent is improved. Therefore, by using the toner obtained according to the present invention in a printing method such as electrophotography, electrostatic printing method, magnetic recording method, etc., it is excellent in coloration of the toner, and the filming of the toner on the photoconductor in the printer is also possible. In addition, since white streaks and fogging can be prevented, high quality images can be stably obtained even in continuous printing.

[Acid value and hydroxyl value]
It is measured by the method of JIS K0070.

[Glass transition point and melting point]
A differential scanning calorimeter “DSC210” (manufactured by Seiko Denshi Kogyo Co., Ltd.) is used to measure at a heating rate of 10 ° C./min.

[Average particle size of charge control agent]
Twenty particles of the charge control agent are randomly extracted from the mapping by a scanning electron microscope (SEM). The major axis of the extracted particles is measured, and the average value thereof is taken as the average particle diameter of the charge control agent.

Resin production example 1
10800 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 4300 g of polyoxypropylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, 4500 g of terephthalic acid and 630 g of n-dodecenyl succinic anhydride was stirred at 230 ° C. under a nitrogen atmosphere, and when water produced by the reaction stopped flowing out, 1880 g of trimellitic anhydride was added and measured according to ASTM D36-86. The resin A was obtained by reacting until the softening point reached 130 ° C. Resin A had a glass transition point of 74 ° C., an acid value of 25 mgKOH / g, and a hydroxyl value of 26 mgKOH / g.

Resin production example 2
12250 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 21125 g of polyoxypropylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, 14940 g of terephthalic acid and Resin B was obtained by stirring 15 g of dibutyltin oxide at 230 ° C. in a nitrogen atmosphere and reacting until the softening point measured in accordance with ASTM D36-86 reached 121 ° C. Resin B had a glass transition point of 66 ° C., an acid value of 3.4 mgKOH / g, and a hydroxyl value of 23.4 mgKOH / g.

Examples 1-5 and Comparative Examples 1-5
100 parts by weight of binder resin prepared by mixing 34.5 parts by weight of resin A and 65.5 parts by weight of resin B with a Henschel mixer, charge control agent “LR-147” (manufactured by Nippon Carlit Co., Ltd., average particle size 50 μm) 1.4 3. Part by weight, Pigment Blue 15: 3 (manufactured by Dainichi Seika Kogyo Co., Ltd.) 4.3 parts by weight and Pigment Green 7 (manufactured by Dainichi Seika Kogyo Co., Ltd.) 0.3 parts by weight are mixed by a Henschel mixer 6 parts by weight and 7.6 parts by weight of wax “Carnauba Wax C1” (manufactured by Kato Yoko Co., Ltd., melting point: about 83 ° C.) are used as raw materials, and each raw material is continuously kneaded from the position shown in Table 1 by a table feeder. Machine (Mitsui Mining Co., Ltd., trade name: Nidex). In addition, when the supply position of each raw material is the same, each raw material is put into a Henschel mixer (effective capacity 10 L) which is a mixing device, and is mixed for 10 minutes at a blade rotation speed of 2500 rotations / minute. The mixture was fed to a kneader.

  The open roll type continuous kneader used has a roll outer diameter of 0.14 [m] and an effective roll length of 0.8 [m], and the operating conditions are heating roll (previous roll) rotation speed of 75 revolutions / minute. The cooling roll (rear roll) has a rotation speed of 15 rotations / minute, and the roll gap is 0.1 mm. The heating and cooling medium temperature in the roll is 150 ° C. on the raw material input side of the heating roll and 115 ° C. on the kneaded product discharge side, The raw material input side of the cooling roll was 35 ° C., the kneaded product discharge side was 30 ° C., and the discharge rate of the raw material mixture was 10 kg / hour.

  Next, the kneaded material obtained by melt-kneading is roughly crushed with a funnel plex. Further, 8 kg of the obtained coarsely crushed material and 56 g of hydrophobic silica “R-972” (manufactured by Nippon Aerosil Co., Ltd.) are mixed with a Henschel mixer. Stir and mix for a minute.

  The obtained stirred mixture was pulverized and classified using a collision plate pulverizer and a dispersion separator to obtain a powder having a volume average particle diameter of about 8.0 μm.

  1.5 kg of the obtained powder, 5.3 g of silica “Si-N” (manufactured by Nippon Aerosil Co., Ltd.) hydrophobized with silicone oil, silica “R-972” hydrophobized with dichlorodimethylsilane ( Nippon Aerosil Co., Ltd.) (7.5 g) and hexamethyldisilazane hydrophobized silica “WACKER H13TM” (Clariant Japan Co., Ltd.) 7.5 g were mixed with a Henschel mixer for 10 minutes at 3000 r / min. The obtained mixture was passed through a vibrating sieve having an aperture of 105 μm to obtain a cyan toner.

Test example 1
(1) The toner was put in the developing cassette, and 1,000 sheets were printed with “BEAMSTAR 4120” (manufactured by Hitachi, Ltd.) at a printing rate of 5%, and the number of white streaks on the developing roll was counted.
(2) After leaving the apparatus for a whole day and night, the number of white streaks on the developing roll was counted after 1000 sheets were printed again at a printing rate of 5% as in the first day.
(3) Thereafter, the operation of (2) was repeated. Every 1000 prints, the number of white streaks on the developing roll was counted and printed up to 6000. The white streaks were evaluated according to the following evaluation criteria. The results are shown in Table 1.

[Evaluation criteria for white stripes]
A: White streaks do not occur until 6000 sheets are printed.
A: No white streak is generated until the end of printing 4000 sheets, and the number of white streaks when printing 6000 sheets is 5 or less.
Δ: No white streak is generated until 4000 sheets are printed, and there are 6 or more white lines when printing 6000 sheets.
X: White streaks occur before the end of printing 4000 sheets.

Test example 2
Toner was put in the developing cassette, and 100 sheets of white paper with a printing rate of 0% were printed with “BEAMSTAR 4120” (manufactured by Hitachi, Ltd.). The paper weight A before printing and the paper weight B after printing were respectively measured to calculate an increase rate (%) [(B−A) / A × 100], and fog was evaluated according to the following evaluation criteria. The results are shown in Table 1.

[Evaluation criteria for fogging]
A: Increase rate is less than 0.05%.
○: Increase rate is 0.05% or more and less than 0.10%.
Δ: Increase rate is 0.10% or more and less than 0.15%.
X: The increase rate is 0.15% or more.

  From the above results, it can be seen that the high-quality images with less white streaks and fog are continuously obtained with the toner of the example as compared with the toner of the comparative example. In particular, from the results of Comparative Example 1, when the charge control agent is excessively dispersed, the charge of the toner tends to be reduced, and fogging occurs. From the results of Comparative Examples 2 to 5, the dispersibility is reversed. If it is too low, it will be understood that charging is deviated, causing problems such as fogging and white streaks.

  The toner obtained by the present invention is used for development of a latent image formed in electrophotography, electrostatic recording method, electrostatic printing method or the like.

Claims (4)

A toner production method comprising a step of melting and kneading a raw material containing a binder resin, a charge control agent, a colorant and a wax using an open roll type continuous kneader having heating and cooling functions, In the kneading, 70 to 100% by weight of the binder resin to be blended and 60 to 90% by weight of the charge control agent are 0.3 L from the end of the roll on the inlet side of the kneader (where L represents the roll length). A method for producing a toner, wherein the toner is supplied to a position between the two and melt kneaded.   The method according to claim 1, wherein the charge control agent has an average particle diameter of 5 to 100 μm. The charge control agent is of formula (I):

(Wherein, X ^{n +} represents a cation, and n represents an integer of 1 or 2)
The manufacturing method of Claim 1 or 2 which is an organic boron compound represented by these. The manufacturing method in any one of Claims 1-3 which supply 70-100 weight% of a coloring agent to the position between 0.3L from the roll edge part by the side of the entrance of a kneading machine.