JPS6380265A - Preparation of pressure-fixable magnetic encapsulated toner - Google Patents

Abstract

PURPOSE:To prepare an encapsulated toner superior in function separation performance at low cost with good productivity by using a combination of a process for dispersing solid core particles containing magnetic particles into an aqueous medium solution of a shell material set to an acidic pH region, and a process for changing the pH of the obtained dispersion to the pH region preprecipitating the shell material from the dispersion and coating the surfaces of the core particles with the shell material. CONSTITUTION:The encapsulated toner is prepared by using the combination of the process for dispersing the solid core particles containing magnetic particles into an aqueous medium solution of the shell material set to an acidic pH region, and the process for changing the pH of the obtained dispersion to the pH region for precipitating the shell material from the dispersion and coating the surfaces of the core particles with the shell material. As the core material for preparing a pressure-fixable polyethylene wax, alone or a mixture of 2 or more kinds of them, the precursors producing it by reaction, or the like can be used, thus permitting the shell material in a state dissolved in the aqueous medium to be favorably insolubilized, and allowed to coat the surfaces of the core particles dispersed in said medium.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing microcapsule toner used in electrophotography, electrostatic printing, magnetic recording, and the like.

11. Conventionally, toner for electrostatic photography, electrostatic printing, or magnetic recording is mainly produced by dispersing and kneading dyes and pigments (and/or magnetic materials as necessary) in resin to obtain particles with a particle size of 5. ~30gm
It is used after being ground into fine particles.

The performance required of such toners is wide-ranging, including developability, fixability, durability, stability, and environmental resistance.
It is difficult to satisfy all of these various performances with one material. For this reason, a material with good fixing properties is used as a core material.
The periphery thereof is coated with a material having excellent developability. A so-called microcapsule toner has been proposed.

On the other hand, in recent years, in place of the heat fixing method, many machines have been released that utilize a pressure fixing method in which toner is pressed onto a fixing substrate (often transfer paper) using pressure and fixed. In this pressure fixing method, since the toner is fixed by pressure, a heat source is not required, there is no risk of fire, the equipment can be simplified, and there is no waiting time until the fixing device is heated. It is also characterized by high adaptability to high speeds.

However, with this pressure fixing method, problems such as the need to increase the strength of the fixing device makes the machine heavy, and the fixing surface of the obtained fixing material become glossy or wrinkled. It tends to be easy. For this reason, efforts are being made to make the toner softer and lower the fixing pressure. The durability performance of the product is significantly lowered, and the storage stability is also deteriorated.

For this reason, many microcapsule toners have been published in which a soft material is used as a core material and the periphery thereof is covered with a hard resin, as seen in Japanese Patent Publication No. 8104/1983.

However, to date, no microcapsule toner with sufficiently high practicality has been announced, and a further improved capsule toner has been eagerly awaited. One reason for this is that materials suitable as toner materials are not necessarily suitable as microcapsule materials. The problem is that it is difficult to provide uniform development suitability, particularly charge controllability.

In addition, there are problems such as the wall material of the microcapsules peeling off due to the impact force received during the development process, and there are many issues that need to be resolved in order to put microcapsule toner into practical use, such as the completeness of the coating and the durability of the coating. The current situation is that there are still some things that need to be done.

Many encapsulation production methods have been proposed to solve these problems (Tasushi Kondo, °° Microcapsules, Sankyo Publishing, 1977), such as the spray dryer method, electrostatic coalescence method, and submerged drying method. , an interfacial polymerization method, a phase separation method, an 1n-situ polymerization method, and a method combining these methods.

In the encapsulation process, the core particles are dispersed in a solution in which the shell material is dissolved or dispersed, and the dispersion is discharged using a two-fluid nozzle or a disc atomizer, and the shell material is deposited on the surface of the core particles. When a coating spray method is adopted, a capsule toner having a coarse particle size in which the particles coalesce may be obtained, and particles called free shells consisting only of shell material may also be produced as a by-product.

Furthermore, when an interfacial polymerization method is used in the encapsulation process, the polymerization reaction generally takes a long time and the toners coalesce, resulting in an unavoidable drop in productivity. Moreover, in this interfacial polymerization method, the selection range of materials that can be used is very narrow, so it is necessary to appropriately control the characteristics 1 of the capsule toner obtained using the interfacial polymerization method, such as triboelectric charging characteristics. This becomes extremely difficult.

Furthermore, even when a phase separation method is used in the encapsulation process, there are various problems. By adding a non-solvent that cannot substantially dissolve the shell material to a solution in which the shell material has been solubilized using " This is a method in which the surface of the core particle is coated.

In this phase separation method, it is essential that the binder constituting the core particles does not dissolve in the good solvent during the process of dispersing the core particles in the good solvent. If part of the core material is dissolved in a good solvent, the core material will be mixed into the resulting shell film, leading to destabilization of the triboelectric charging characteristics of the toner and contamination of the sleeve, which is a toner carrier. Furthermore, when the shell material is precipitated by the action of a non-solvent, the free shell with high triboelectrification properties is produced as a by-product and tends to cause fogging in the developing process and unevenness of the toner layer on the sleeve. In the encapsulation method using the phase separation method, selection of a good solvent and a non-solvent for the shell material is extremely important. In other words, if these selections are incorrect, the precipitation point of the shell material will be too early, resulting in poor product stability and reproducibility.
On the other hand, if the precipitation point is too slow, the manufacturing equipment will be large and the amount of solvent relative to the core particles will be large, resulting in a decrease in productivity and making it difficult to recover and utilize the solvent.

Furthermore, temperature control in this phase separation method must also be extremely delicate and complicated.

1 to 11 An object of the present invention is to provide a method for producing a microcapsule toner that solves the above-mentioned drawbacks.

Another object of the present invention is to provide a method for producing a microcapsule toner that does not aggregate or coalesce, has high coating integrity, does not generate free shells, and has excellent functional separation properties.

Another object of the present invention is to provide a manufacturing method for producing microcapsule toner at low cost and with good reproducibility.

As a result of intensive research, the present inventors found that using an aqueous medium solution of the shell material in a certain equilibrium state of protonated and aprotonated forms of the shell material, and further utilizing the above equilibrium to form a core. It has been found that precipitating a shell material on the particle surface is not only extremely effective in achieving the above object, but also provides a capsule toner with excellent environmental stability.

The pressure-fixed magnetic capsule toner manufacturing method of the present invention is based on the above knowledge, and more specifically, the method for producing a pressure-fixed magnetic capsule toner of the present invention is
A dispersion step in which solid core particles containing magnetic particles are dispersed in a solution in an aqueous medium set in the acidic p)I region, and the pH of the dispersion obtained in the above dispersion step is adjusted from the dispersion to the shell material. The method is characterized by comprising the step of coating the surface of the core particle with a shell material by changing the pH to a pH range in which is precipitated.

The present invention will be explained in more detail below. In the following description, unless otherwise specified, "%" and "r part" expressing a quantitative ratio are defined as heavy fi1'& quasi.

When obtaining a pressure fixable toner, the core material used in the present invention includes waxes such as polyethylene wax, oxidized polyethylene, paraffin, fatty acids, fatty acid esters, fatty acid amides, fatty acid metal salts, and higher alcohols; Vinyl acetate resin, cyclized rubber, and the like can be used alone or in combination of two or more, or as a core material raw material that provides these core materials by reaction.

In the present invention, more preferably used core materials include: (a) A resin having a hardening effect that has a Vickers hardness of 2 to 8 Kg/am'' when the mold is held for 15 seconds at an applied load of Log.

(b) Critical surface tension at 20°C is 15-4°dyr
A mixture containing at least two of the following resins: (c) a resin having an ll1l type property-imparting action of +e/c+s, and (c) a resin having a fixing property-imparting action having a compressive elastic modulus of 0.1 to 50 kg/intestinal 2. Examples include a binder resin containing a heat-treated product that has been heat-treated in advance in the presence of a radical generator.

As the resin having the hardening effect (a) used here, a substance exhibiting a Vickers hardness of 2 to 8 kg/wm2 when the mold is held for 15 seconds at an applied load of log is preferably used.

The hardening effect here means: ■- suppressing the shape change and crushing of the core particles in response to external force applied when the obtained core particles are encapsulated; (1) impart resistance to external forces applied to the toner during the toner filling process or during storage; and (1)
Provides resistance forces between the sleeve and toner, between the sleeve and blade (toner layer thickness regulating means), and between toner and toner as the sleeve, which is a toner carrier, rotates under a desired magnetic field in the developing process. (2) To provide appropriate strength against the friction between the cleaning member and the drum when cleaning the toner remaining on the drum, which is the latent image carrier, after the transfer process.

In the present invention, Vickers hardness can be measured using a microhardness meter (MVK-F) manufactured by Akashi Seisakusho. The hardness measurement method is based on JIS Z2244, and in this method, the loading rate is set so that the applied load is log and the required time is 15 seconds, and the measurement is performed at a test temperature of 23±5°C.

Specific examples of substances having such a hardening effect (a) include substances with a Vickers hardness of 2 to 8 kg/■2, such as carnauba wax (Vickers hardness Hv=3
, 6 kg/am2), Candelilla wax (
There are natural waxes such as Hv=4.8kg/2) and synthetic waxes such as polyethylene wax.

If a substance having a hardening effect (a) with a Vickers hardness of less than 2 kg/am' is used, the toner will be destroyed by external force that causes the sleeve and toner to move relative to each other in the developing process. Toner adhesion occurs on the sleeve. As a result, the original functions that function between the toner and the sleeve, such as the generation of sufficient frictional electrification and the function of preventing toner particles from coagulating with each other, are reduced, causing uneven coating of the toner layer on the sleeve. On the other hand, Vickers hardness is 8
When a substance having a hardness imparting action exceeding kg/am2 is used, there is an increased tendency for the pressure fixing properties of the toner to be insufficient.

As the substance having particularly preferable hardening effect (a), carnauba wax (or modified carnauba wax) having an acid value in the range of 0 to 2 (more preferably 0 to 1) is preferably used.

If carnauba wax with an acid value exceeding 2 is used, the carnauba wax will self-emulsify when the core material is atomized in an aqueous dispersion medium in the presence of a dispersant, resulting in core particles having an extremely wide particle size distribution. I can only get it.

Furthermore, carnauba wax has extremely high hardness.

Since the melt viscosity is relatively low, the stirring power required for atomization is small, and the desired atomization can be achieved satisfactorily even when a commonly used stirring device is used.

A further preferable feature of carnauba wax is that it has an extremely good ability to encapsulate the magnetic material used during the formation of core particles.

On the other hand, the material having the release property imparting effect (b) used in the present invention has a critical surface tension of 15 to 15 at 20°C.
A substance exhibiting 40 dyne/c is preferably used. Specific examples include polyvinyl fluoride (critical surface tension γc = 28 dyne/am), Teflon (γc = 18.5), polyethylene (yc = 31), polyisobutyne (yc = 27), and ethylene-propylene. Polymer (γc = 28), ethylene-tetrafluoroethylene copolymer (γG = 26-27), ethylene-vinyl acetate copolymer (γG = 37), isobutyne-isoprene copolymer (γc = 27), polypropylene (γ.

;29-34), polymethyl methacrylate (γ.~3
9), polyvinyl chloride (γc=39), etc. Especially γ
Those having C of 15 to 40 d2ne/am, such as polyvinyl fluoride, Teflon, polyethylene, etc., are preferable.

If a material having a release property imparting effect (b) with a critical surface tension of less than 15 d7ne/am is used, the hardness imparting effect (a) and the fixing property imparting effect (c) contained in the core material would be used. ) and the shell material, resulting in poor uniform dispersion of the core material and a tendency for delamination between the core particles and the shell film to occur when external forces are applied. It increases. On the other hand.

1llll with critical surface tension exceeding 40 dine/cm
When a substance that has a moldability imparting effect is used, it has high water absorption, so that image density decreases and toner film formation on the drum is likely to occur under high humidity. Furthermore, when core particles are formed by a wet method, self-emulsification of the core particles occurs, and only core particles with a significantly wide particle size distribution can be obtained.

Further, in the present invention, as the substance having the fixing property imparting function (c), a substance exhibiting a compressive elastic modulus of 0.1 to 50 kg/am'' is preferably used.

In the present invention, this compressive elastic modulus is JIS-720
It can be measured in accordance with 8. The measurement conditions are as follows. That is, using a Shimadzu Autograph DO3-2000 manufactured by Shimadzu Corporation, a sample piece molded to a diameter of 12 mm and a height of 30 mm was placed on the pressurizing surface and pressurized at a test speed of 9 m/min. Calculate the compressive modulus from the slope of the straight section at the beginning of the line.

Specific examples of the substance having a fixing property-imparting effect (C) that is preferably used in the present invention include paraffin wax, polyamide resin, microcrystalline wax, and ethylene-
Examples include vinegar-vinyl copolymers. Particularly preferably, one having a compressive elastic modulus of 0.1 to 50 Kg/am', for example, paraffin 155 (manufactured by Nippon Seiro Co., Ltd.; compressive elastic modulus E=
lOKg/ms'), 5PO145 (manufactured by Hiki Seirosha; E
= 15 g/as'), Polymide S-40E (
Manufactured by Sanyo Chemical Co., Ltd.; E = 12 Kg/m2), Microcrystalline wax (manufactured by Nippon Chemical Co., Ltd.; E =
= 26 Kg/am2).

This fixing property imparting component is required to have the effect of making the toner sufficiently sensitive to stress from the fixing device when an unfixed image of the toner is fixed on an object to be fixed by the fixing device.

However, if the toner deforms excessively in response to external force, the deformation extends to the inside of the object to be fused, and the strength of the interface between the toner and the object to be fused increases, but it is resistant to rubbing by cloth, eraser, etc. On the contrary, the durability of the fixed image becomes weaker.

If a substance having a fixing property imparting effect (c) with a compressive elastic modulus of less than 0.1 Kg/*m2 is used,
Images may become "smeared" or "smeared". On the other hand, the compression modulus is 50Kg/! If a substance having a fixability-imparting effect (c) exceeding 1112 is used, the fixing performance will be significantly lowered, such as the fixing object "peeling off" from the fixing object.

The content in the binder resin of the resin having the hardness imparting effect (a), the mold releasability imparting effect (b), and the fixing property imparting effect (c) used in the present invention is the total binder resin in the core material. 100
5 to 60 parts, preferably 10 to 60 parts of resin (a)
50 parts, resin (b) is 5 to 60 parts, preferably 10 to 5 parts
0 parts, resin (C) is 20 to 90 parts, preferably 20 to 8 parts
Preferably, the ratio is 0 parts.

In the present invention, the above-mentioned (&) hardening effect.

(b) A mixture containing at least 2N resin among the three components having an a-type property-imparting action and (c) a fixing property-imparting action is heat-treated in the presence of a radical generator to bind the core substance. It is preferable to use resin.

Reactions caused by this heat treatment include radical reactions such as hydrogen abstraction reactions by radical generators or radicals generated by heating, and intramolecular or intermolecular crosslinking reactions. When the radical generator is applied, it is preferable to carry out the heat treatment in the absence of a solvent such as an organic solvent that dissolves the resin.

A method using a polymerization initiator is preferred because radicals can be generated easily and reliably at a relatively low temperature.

Examples of the polymerization initiator include peroxide compounds (specific examples of which are shown in Table 1 below), hydroperoxides such as cumene hydroperoxide; furkyl peroxides such as di-tert-butyl peroxide; potassium peroxosulfate, ammonium peroxosulfate, and peroxides. hydrogen oxide,
So-called radical polymerization initiators such as 2.3-azobisisobutyronitrile are preferably used.

From the viewpoint of safety and availability 1, hydrogen peroxide and n-butyl-4,4-bis-tart-butyl peroxyvalerate (e.g. Barhexa■ manufactured by NOF ■) are particularly recommended. preferable.

Table 1 Typical Organic Peroxides In the present invention, by performing heat treatment in the presence of a radical generator, characteristics completely unanticipated in the past can be realized, namely, the hardness-imparting component contained in the core material, and the mold release agent. It is possible to prevent phase separation of the properties-imparting component and the fixability-imparting component, as well as migration of components due to changes over time, and as a result, it is possible to produce core particles with uniform mechanical and electrophotographic properties. becomes.

In the present invention, as a component of the core substance.

When producing core particles, for example, when using a method in which a poorly water-soluble dispersant is used in an aqueous solvent to granulate the core particles, the dispersant dissociates in the aqueous medium and induces a charge opposite to the charge induced. When obtaining core particles in the presence of a poorly water-soluble dispersant in an aqueous medium, it is preferable to combine a cationic property-imparting compound or an anionic property-imparting compound with a cationic property-imparting compound or an anionic property-imparting compound. It is common to use a dispersant that has In other words, when the particle size of the dispersant is very small, the surface of each dispersant particle is significantly activated energetically, so that the selective adhesion of the dispersant particle to the surface of the core particle increases.

In the present invention, when a polar solvent such as water is used as a dispersion medium for the core particles, it is advantageous to provide the dispersant with a highly polar functional group. By occupying, due to ionic ability interaction,
Furthermore, it becomes possible to make the core particles as desired. Furthermore, by making effective use of such functional groups, it is expected that, for example, the dispersant can be removed when it is not needed. In other words, if it is desired to obtain a desired particle size, it can be achieved by arbitrarily selecting the amount of the slightly water-soluble dispersant added.

However, simply using a dispersant selected in this way does not necessarily ensure that the dispersant adheres selectively and uniformly only to the surface of the core particle, and may not be sufficient to obtain uniform particles. In order to uniformly adhere the dispersant onto the surface of the core particle, it is necessary to

It is preferable to further combine a cationic property-imparting compound or an anionic property-imparting compound that induces a charge opposite to the charge induced by dissociation of the dispersant in an aqueous medium into the core substance to be atomized. .

For example, typical examples of dispersants that can be dissociated as anions in water include silica, bentonite, etc., and hydrophobic amines are generally used as compounds imparting cationic properties to these dispersants. # is preferably a cationic property-imparting compound that is sufficiently compatible with other components contained in the core material, such as a long-chain aliphatic amine or a graft compound produced from polyethylene and a hexamer containing an amine group. There is. Specifically, Duomin T (Lion-71mer),
There are amino-modified waxes and the like obtained by heating and dissolving polyethylene wax, adding an aprotic polar solvent containing an amino group-containing vinyl monomer and a radical initiator, and heating again.

On the other hand, examples of dispersants that can be dissociated as cations in water include aluminum oxide. Compounds imparting anionic properties include hydrophobic long-chain aliphatic carbonaceous compounds such as stearic acid and oleic acid. Also long chain aliphatic dicarboxylic acids.

Examples of the carboxylic anhydride include a reaction product of a CS α-olefin and anhydrous leic acid, or a half ester thereof.

The core particles used in the present invention can be manufactured by various manufacturing methods using the core material as described above. Such core particle manufacturing methods include, for example, an electrostatic exposure method using the method described in JP-A-58-216736, in which a DC voltage is applied and window material is discharged from a disk atomizer, and a two-fluid nozzle. The melt spray method described in JP-A No. 59-120263 to form core particles, and the suspension granulation method described in JP-A-59-127062, which involves granulation in an aqueous medium, are preferably used in the present invention. As mentioned above, it is preferable to use a method in which the core material is granulated in an aqueous medium to produce core particles because the particle size distribution becomes sharp. The manufacturing method is not limited to the following.

The average particle diameter of the core particles used in the present invention is preferably 0.4 to 99 JLII, more preferably 4 to 19 JLII, as a volume average particle diameter.

In the present invention, in order to produce a magnetic capsule toner, magnetic particles are contained in the core material.

As a magnetic substance contained in the core material.

These include ferromagnetic elements such as iron, cobalt, nickel, or manganese, and alloys and compounds containing these elements such as magnetite and ferrite. This magnetic substance may also be used as (all or part of) a coloring agent.Furthermore, particles of this magnetic substance may be used as various hydrophobizing agents (for example, silane coupling agents, titanium coupling agents), surfactants, etc. The content of this magnetic substance, which may be treated with, is preferably 15 to 180 parts (more preferably 50 to 150 parts) based on 100 parts of all the resin in the core material.

A coloring agent can also be used in combination with a magnetic substance in the core material of the present invention. Such colorants include, for example,
Various carbon blacks, aniline black, naphthol yellow, molybdenum orange, rhodamine lake,
Alizarin rake.

Examples include methyl violet lake, phthalocyanine blue, nigrosine methylene blue, rose bengal, and quinoline yellow.

The amount of colorant added is based on 100 parts of the binder resin of the core particles.
0.1 to 20 parts is preferred.

Furthermore, 120% of the molten mixture of the core materials consisting of the binder resin of the core materials and the magnetic material (coloring agent if necessary) is added.
The apparent viscosity measured at a rubbing speed of 10 5 ec-' at a temperature of 0.degree.

The fact that the apparent viscosity decreases as the shear rate increases is generally referred to as chicken-tropy, but this highly chicken-tropic core material prevents toner deformation due to abrasion between pressure rollers during pressure fixing. encourage,
Improves fixing properties.

In addition, as described later, in the method of melting and mixing the core material, pouring it into an aqueous medium and applying strong shearing force using a homomixer or the like in the presence of an emulsifier, etc., to granulate the core material, During said shearing.

By lowering the apparent viscosity of the core material, granulation properties are improved.On the other hand, after shearing, the apparent viscosity increases, which causes coalescence between particles and the formation of colorants, magnetic substances, etc. inside the particles. Aggregation and bias are suppressed.

Although various viscosity meters are used in the viscosity measurement method, a rotating double cylinder (rotor) type viscometer is used in the present invention.

In the case of a rotor type viscometer, the shear rate is determined by the following formula.

1- (Rh/Rc)2(5ee-')RC: Car 2
radius (c+*) Rb: rotor radius (c+w) h: rotor height cm) ω: rotor rotational angular velocity N: rotational speed (RP layer) Also, shear stress S is S=M/2πRb2 h(M; viscosity torque), and the viscosity η is η=S/I) (η: viscosity)
Therefore, by measuring the torque from the shape of the rotor of the viscometer, the slip speed and viscosity can be determined.

In addition, binder resins that generally have pressure fixing properties have a relatively low melt viscosity, so no shear (shearing force) occurs between pigments such as colorants and magnetic materials and the binder resin during melt-kneading. Therefore, the pigment tends to be insufficiently dispersed in the binder resin. As a result, a large number of particles with no coloring material inside the toner particles or particles with the coloring material unevenly distributed in the toner particles are generated, which deteriorates the performance as a toner and ultimately reduces the image quality, durability, and stability of the toner. It tends to have a negative impact on

Therefore, it is desirable to disperse the pigment particles (used to include Fii particles) in the toner particles so that the particle size is 5 pm or less, preferably 2 pm or less. Media was used rather than the two-roll, twin-screw extruder kneader, etc. that had been used to melt and disperse the components. It is desirable to disperse the melted cross-wire for a sufficiently long time using attritors, ball mills, or sand mills.

In order to check the degree of dispersion of pigment substances, it is possible to determine the degree of dispersion of the toner by dispersing the toner in an embedding resin such as an epoxy resin, curing it, cutting it into ultrathin sections using a microtome, etc., and observing it with a transmission electron microscope. can. In addition, a particle size gauge (
For example, the dispersibility of the pigment substance can also be determined by using a grind gauge (type 2, manufactured by Yoshimitsu Seiki Co., Ltd.).

Above, the core material used in the microcapsule toner manufacturing method of the present invention has been mainly explained.

On the other hand, the best material used in the present invention mainly has good mechanical properties and thermal properties, and has a film-forming property imparting function (A) that provides sufficient film-forming property, and a film-forming property imparting function (A) that mainly provides acidification in an aqueous medium. Preferably used is a resin that has both the proton addition function (B), which is capable of forming a proton addition mass with an agent, and the solubilization function (C), which is mainly able to solubilize the proton adduct in an aqueous medium.

As for the resin properties, the number average molecular weight is 5.000 to 4.0.
00, and more preferably 10.000 to 30.000, and the ratio of the number average molecular fit (Mn) to the weight average molecular weight (M w ) showing monodispersity of molecular weight distribution (M w / M n) is in the range of 1.5 to 4.5, the glass transition temperature (Tg) is 40°C or higher, preferably 60-120°C, and the crosslinking (cros
Thermoplastic resins that have no bonding (s-1 inking) and exhibit stable properties against humidity can be preferably used.

However, it is difficult for a resin synthesized from a single type of monomer to satisfy all of the above functions (A), (B), and (C:), and in general, a copolymer that is a combination of multiple seven monomers is used. Combination is preferably used. Specifically, a resin composed of one type of monomer having the following various functions is used.

As the monomer having function (A), styrene (St
), α-chlorostyrene, α-methylstyrene, allylbenzene, phenylacetylene, vinylnaphthalene, 4-methylstyrene, 2,4-dimethylstyrene, 3
-Ethylstyrene, 2.4-diethylstyrene, 2-methoxystyrene, 4-chlorostyrene, 4-fluorostyrene, 3-iodostyrene, 4-cyanostyrene, 3
-Aromatic hexamers such as nitrostyrene are preferably used.

As the monomer having function (B), methacryl%N
, N-dimethylaminoethyl ester (DM), acrylic acid N,N-dimethylaminoethyl ester, methacrylic acid N,N'-diethylaminoethyl ester (DE)
, acrylic acid N.

N-diethylaminoethyl ester, acrylic ugly N, N
-dibutylaminoethyl ester, methacrylic acid N, N
Nitrogen-containing aliphatic monomers such as -dibutylaminoethyl ester (DB), 2-piperidinoethyl methacrylate, and 2-piperidinoethyl acrylate are preferably used.

Seven polymers that have both functions (A) and CB) include vinylpyridine, vinylcarbazole, and 5-ethyl-2-
Vinylpyridine, 2-methyl-5-vinylpyridine, N
, N-divinylaniline, trans-1,2-bis(2-
pyridyl)ethylene, 2-vinylquinoline, 2-(N,
N-dimethylamino)-4-vinylpyrimidine, 4-vinylpyrimidine, 3-cinnamoylpyridine, 4-methacryloxybenzylideneaniline, diallylmelamine, 2,4-dimethyl-6-vinyl-triazine, 4,6
Nitrogen-containing aromatic monomers such as -diami2-2-vinyltriazine and N-vinylimidazole are preferably used.

Seven polymers having function (C) include ethylene, propylene, isoprene (IP), butadiene (BD),
Ethylenically unsaturated monoolefins such as butylene and imbutylene; vinyl chloride, vinylidene chloride, vinyl bromide,
Vinyl halides such as vinyl fluoride; vinyl esters such as vinyl acetate, vinyl propionate, and vinyl benzoate; methyl methacrylate (MMA), ethyl methacrylate, propyl methacrylate, n-butyl methacrylate (BMA), Isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate (2EHA), stearyl methacrylate, phenyl methacrylate, methyl acrylate, methyl acrylate, afrylmi 1! n-butyl (BA),
Isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-acrylate
Ethylhexyl, stearyl acrylate, acrylic acid 2
- Acrylic acid or methacrylic acid esters such as chloroethyl and phenyl acrylate; vinyl methyl ether,
Vinyl ethers such as vinyl ethyl ether and vinyl isobutyl ether; Vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, and methyl isopropenyl ketone; Acrylonitrile (AN), acrolein,
Aliphatic vinyl septamers such as acrylamide, maleic anhydride (MA), and dimer acid are preferably used.

The shell material used in the present invention is not limited to only a resin composed of heptamer having the functions (A), (B) or (C) as described above, but also polyester, polycarbonate, polyester, etc. Polyether resins such as sulfonates, polyamides, polyurethanes, polyureas, epoxy resins, rosins, modified rosins, terpene resins, phenolic resins, aliphatic or alicyclic hydrocarbon resins, aromatic petroleum resins, melamine resins, polyphenylene oxides, Alternatively, a homopolymer or copolymer such as a thioether resin may be used in combination.

More preferred specific examples of the shell material used in the present invention include St-MMA-DM copolymer, S L-MMA
-DE copolymer, S L-2E1 (terpolymer such as A-DM copolymer; St-MMA-2EHA-DM copolymer, St-MMA-BMA-DM copolymer, S
t-MMA-BD-DM copolymer, S t -MMA-
Examples include quaternary copolymers in which one function (C) is composed of two heptads, such as IP-DM copolymer and St-AN-MMA-DM copolymer.

The composition ratio of the heptamers having function (A) CB) (C) is the molar ratio (assuming the entire monomers constituting the copolymer as lOO): (A) : (B) : (C)
= (30~90): (5~65): (5~
30) (mol%).

If the ratio of the seven toner particles having the function (A) is less than 30 mol%, it will be formed on the surface of the sleeve (which is the toner carrier in the developing device) that rotates facing the photosensitive drum which is the latent image carrier. The toner layer collapsed due to the force applied to the toner between the sleeve and the regulating blade, which is a toner layer thickness regulating means, and the force applied to the toner between the sleeve surface layer that rotates against the external magnetic force. In addition, some of the toner developed on the photoreceptor surface may be removed during the cleaning process. The external force between the cleaner member and the surface layer of the photoreceptor tends to cause toner fusion on the surface of the photoreceptor drum, resulting in harmful effects.

On the other hand, the ratio of heptomers having two functions (A) is 90 mol%
If it exceeds 20%, the blending ratio of the 7mers having functions (B) and (C) becomes relatively small, and it becomes difficult to solubilize the shell material in the aqueous medium by adding an acidifying agent.

When the proportion of the monomer having function (B) is less than 5 mol%, solubilization in the shell aqueous medium is prevented, while when the proportion exceeds 65 mol%, the stability of the toner at high temperatures is reduced. As a result, it becomes difficult to satisfy the Tg value required for the toner.

If the ratio of the monomer having function (C) is less than 5 mol%, it will be difficult for the proton adduct of the shell material generated by the action of the acidifying agent to be solubilized in the aqueous medium; If it exceeds 30 mol%, the solubility of the proton adduct in the aqueous medium will be sufficiently high, but on the contrary, the ability to form a film with the amount of shell material on the surface of the core particle will be insufficient.

The amount of the shell material added to cover the surface of the core particle cannot be determined uniquely depending on the surface shape of the core particle, the density of the core material and the amount of the shell material, the particle diameter of the core particle, etc.

In the present invention, the amount of added shell material is determined by calculating the amount of shell material corresponding to the set film thickness from the following formula based on the set film thickness of the amount of shell material from the viewpoint of toner characteristics. It is preferable.

That is, the amount of shell material added is preferably calculated using the following formula.

Here, δ: Set film thickness (ILm), W: Amount of shell material, ρ: Density of shell material, G: Density of core particles, S: Amount of core particles, D = Volume of core particles. Average particle size (pm).

The volume average particle size of the core particles was determined as follows. That is, by putting approximately 1% saline in a beaker, adding a small amount of core particles, and dispersing the core particles in an ultrasonic cleaner for about 60 seconds, then adding 1% saline, The core particle concentration was adjusted to 5 to 10%, and a sample was prepared by ultrasonic dispersion for about 60 seconds again. This sample was added to the Coulter Counter TA-II (Coulter Counter TA-II).
(manufactured by Electronics Co., Ltd.) to determine the volume average particle size.

The set film thickness δ in the present invention is 0.01 to 2°.
(more preferably 0.05 to 1.0 lm). If this set film thickness is less than 4ts, the shell material cannot completely cover the surface of the core particle, resulting in a so-called defective film. Therefore, during development under high humidity, stable frictional charging is not performed, and furthermore, the toner tends to adhere to the drum.On the other hand, if the set film thickness exceeds 2.0 pm, the toner will have too high resistance. ,
During development under low humidity, uneven toner coating tends to occur on the sleeve.

Further, in the present invention, the average particle size (volume average particle size) of the encapsulated toner is usually 0.5 to 20 gm, preferably 5 to 20 gm.

In the present invention, the above-described amount of shell material is subjected to the core particle coating step in the form of a solution dissolved in an aqueous medium set in an acidic pH range.

The method for obtaining such a shell material solution is not particularly limited. For example, it is possible to obtain the solution via a solution polymerization method, but from the viewpoint of improving the environmental stability of the capsule toner, It is preferable to prepare a shell material solution by solubilizing the above shell material in an aqueous medium with the aid of an acidifying agent.

If such a shell material amount solution is used and core particles are dispersed in an aqueous medium in advance, the amount of shell material becomes insoluble at a predetermined p.
By changing the pH of the dispersion liquid to the H range, the amount of shell material can be coagulated and precipitated on the surface of the dispersed core particles to sufficiently cover the dispersed particles.

The aqueous medium in the present invention is under the following conditions (
A solvent having one or more of 1) to (4) is preferably used.

1) The amount of shell material is preferably a solvent that can stably form a proton adduct in the presence of an acidifying agent, that is,
Preferably, the amount of shell material is a highly polar solvent that can be completely solubilized in the aqueous medium by the addition of an acidifying agent.

In the present invention, a highly polar solvent is defined as one that is sufficiently miscible with water and has a solubility parameter (according to "Polymer Handbook").
(described in 2nd Edition ■337-359) means a solvent with a value of 11.0 or more.

2) It is preferable that the solvent is a solvent that does not substantially increase the viscosity of the solution when the amount of shell material is insolubilized.In a system using a solvent that increases the viscosity when the shell material is precipitated, stirring of this system is preferable. As a result, the precipitated shell material particles do not selectively coagulate and precipitate on the surface of the core particle, and many free shells consisting only of shell material particles are produced as by-products, and the capsule toner is aggregated and coalesced. The proportion of

3) From the viewpoint of recovering and reusing the solvent, a low boiling point solvent is preferable.

4) It is preferable that the solvent is a solvent that does not substantially dissolve the core material.

In other words, when the core material is solubilized when the core particles are dispersed in an aqueous medium, when the shell material is precipitated in the next step, it is encapsulated using the core material that does not contain magnetic particles (or colorants, etc.) as a core. Free shells that do not contain core particles are likely to be produced as a by-product because the toner that has been dissolved in the toner is produced as a by-product, and the solubilized core material destabilizes minute oil droplets that are generated at the initial stage of precipitation of the shell material.

Specific examples of solvents preferably used in the present invention are shown in Table 2 below.In the present invention, it is most preferable to encapsulate using a single solvent consisting only of water, but in order to satisfy the above conditions, Usually, a mixed solvent system consisting of water and a lower alcohol is particularly preferably used. In this case, the mixing ratio of water and lower alcohol largely depends on the characteristics of the shell material used, but in general, the weight ratio of lower alcohol to water (weight of lower alcohol/weight of water) is (E), The number average molecular weight of material a is 10.00
If the value divided by 0 is (N), these blending ratios CD
) is preferably mixed so that D=E/N=0.05 to 6, and more preferably, D=0.1 to 4. .

Table 2 Specific examples of polar solvents When the above blending ratio (D) is smaller than 0.05, the shell material that can be solubilized in an aqueous medium is restricted, and high molecular weight resins cannot be used particularly from the viewpoint of solubility. Furthermore, the viscosity of the shell material solution becomes extremely high when the shell material, which has been solubilized with the aid of the acidifying agent, is precipitated (preferably by the action of the basifying agent), and sufficient stirring is not performed. Free shells and coalesced toner are more likely to occur.

On the other hand, when the blending ratio (D) is greater than 6, the viscosity of the solution when the shell material precipitates becomes low and the load on stirring is reduced, but on the contrary, the shell material swells and some solubilizes. This causes the shell material to be difficult to solidify even after encapsulation, making the post-processing process extremely complicated. Furthermore, the stability of the precipitated shell material emulsion particles is poor, making it difficult to selectively adsorb onto the surface of the core particles, making it easy for the shell material to mechanically adhere to containers and the like.

The smaller the amount of solvent used for the core particles containing the magnetic substance, the better from the viewpoint of productivity, but encapsulation is usually carried out in a range of 10 to 50 parts of the core particles per 100 parts of the solvent. It is preferable.

In the present invention, it is also possible to further add another polar solvent to the aqueous medium in order to smooth the shell film. Such other polar solvents include, for example, ethylene glycol diacetate, ethylene glycol dimethyl ether, ethylene glycol monoacetate, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether, ethylene glycol monoethyl ether acetate, ethylene glycol monomethyl ether, ethylene Cellosolves such as glycol monomethyl ether acetate; polar aproton-donating solvents such as acetonitrile, dioxane, dimethylformamide, dimethyl sulfoxide, dimethylacetamide, dimethylurea, etc. can be used.

In the present invention, the concentration of the shell resin solubilized in the aqueous medium with the aid of an acidifying agent is usually 0.5 to 20 parts (particularly preferably 1.0 to 10 parts) per 100 parts of the aqueous medium. It is preferable to use it at a concentration of .

When the concentration of the shell material is less than 0.5 parts, the manufacturing equipment becomes large and furthermore, a large burden is placed on solvent recovery. On the other hand, if the shell material concentration exceeds 20 parts.

When the shell material precipitates, the viscosity of the solution increases and it cannot be stirred sufficiently, which not only increases the number of free shells, but also increases the viscosity of the solution.
A large amount of coalesced toner is also generated.

In the present invention, it is preferable to add an acidifying agent to the aqueous medium and set the pH to be in an acidic PH range to solubilize the shell material to form a shell material solution. In this case,
The pH value at which the shell material can be solubilized depends on the type of aqueous medium, blending ratio, film-forming properties (A), and solubilizing monomer (C).
Although it depends somewhat on the type, molecular weight, ionic strength, etc. of the proton-adding monomer (B), in general,
Since Kb has a value of 7±2, it is preferable to set the pH value so that the ionization rate of monomer (B) defined by the following formula is 90% or more, and usually P
It is preferable to adjust the H value to 5±1.5 using an acidifying agent.

Ionization rate (%) of Natsuma (B) 1 + anti lag (pH-pKa) In order to precipitate the shell material, use a normal basizing agent (if the region where the shell material is deposited is alkaline).

It is preferable to change the pH to the alkaline side, which is the precipitation region. As the basifying agent used in this case, in addition to ordinary organic/inorganic bases, it is also possible to use a pH buffer.

In the encapsulation in the present invention, under the above pH conditions,
Encapsulation can be carried out by heating or at room temperature, but in order to completely cover the surface of the core particle with the shell material, to suppress mechanical adhesion of the shell material, and furthermore to prevent elution of the core material, the encapsulation is carried out using -lO Preferably, the encapsulation is carried out at a temperature of ~+30° C. If the encapsulation temperature is lower than 110° C., the equipment becomes complicated and running costs increase.

On the other hand, if the encapsulation temperature exceeds +30°C, mechanical adhesion of the shell material and elution of the core material tend to increase, which is not preferable.

In the present invention, the basifying agent includes sa bases such as sodium hydroxide, potassium hydroxide, calcium hydroxide, ammonia gas, and aqueous ammonia; and ethylenediamine and diethylenetriamine.

Organic bases such as triethylenediamine are preferably used, and aqueous ammonia is particularly preferably used.

On the other hand, in the present invention, the acidifying agent includes hydrochloric acid, sulfuric acid,
Inorganic acids such as phosphoric acid; and organic acids such as formic acid, acetic acid, and succinic acid are preferably used, and acetic acid is particularly preferably used.

In the present invention, the rate of addition of the basic agent used is determined by the following formula: F: Concentration of shell material in aqueous medium (g/text) G: Amount of aqueous medium (I H: Addition rate of base and other agents (+sl /min), and it is more preferable to perform the above-mentioned sotrol.

It takes time to convert, and production efficiency decreases significantly.

In addition, the shell material resin precipitated by the production method of the present invention is first precipitated in the form of viscous oil droplets and undergoes a step of solidification, so if the dropping speed of the basicizing agent is slow, the precipitated core resin When the coalescence of the material particles exceeds the accelerated level, the precipitated shell material emul 9.7 particles cannot be completely adsorbed onto the surface of the core particle, leading to the generation of free shells and the tendency to cause coalescence of single particles. There is.

11. As described above, according to the present invention, the balance between the protonated product and the aprotonated product of the shell material is controlled by pH control.
A method for producing a capsule toner is provided in which a shell material dissolved in an aqueous medium is suitably insolubilized and the shell material is well coated on the surface of a core particle dispersed in an aqueous medium.

According to the production method of the present invention, aggregation of the produced capsules,
A microcapsule toner that suppresses coalescence, does not generate free shells, and has excellent functional separation can be produced at low cost and with good reproducibility.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples.

Reprint carnauba wax (manufactured by Noda Wax Co., Ltd.) 1kg 2
The mixture was placed in a four-bottle flask, and the pressure inside the container was reduced to 1 to 2 mmHg in a nitrogen atmosphere. While maintaining this reduced pressure state, the inside of the container was heated to 250°C and reacted for 8 hours. The acid value of the carnauba wax obtained at this time was 0.5.

This carnauba wax (Beercurse hardness Hv=3.6)
400 g, and 200 g of polywax 655 (manufactured by Petrolite, bicritical surface tension γC = 31 dyne/am)
And further, 5PO145 (manufactured by Nippon Seirosha, compressive elastic modulus E=
After putting 15 kg/■2) 400 g into a four-bottle flask, n-butyl-4,4-bisute
rt-Butyl peroxyvalerate (Perhexa V, manufactured by NOF Corporation, temperature 105°C to obtain a half-life of 10 hours) I
g was added thereto, and the inside of the container was heated to 150°C for 2 hours of heat treatment.

Using a lighter, the mixture was kneaded at 200 rP for 3 hours to obtain a core material.

At 120° C. of the contaminant (core material). shear rate 10
5ec-' apparent viscosity is 600 cpg, shear rate 0
, 5 5 ec-' had an apparent viscosity of 6500 cps.

In addition, the particle size of magnetite particles in the kneaded material is at most 1.5
It was a 1L layer.

On the other hand, in a 201 Ajihomo mixer (manufactured by Tokushu Kika Kogyo Co., Ltd.), water 2001 and wood-philic silica (7Erogil #200, manufactured by Nippon Aerosil Co., Ltd.) 2, which is negatively charged in water, were placed in advance.
0g was sampled and heated to 90°C to use as a dispersion medium. child,
In the dispersion medium obtained as above, the above-mentioned contaminant (core substance) I
kg, and the circumferential speed of the above Ajihomo mixer was 20 ta.
Granulation was carried out for 1 hour under the following conditions: /sec and the number of passes was 6.9 times/1n. After finishing the granulation, using a heat exchanger,
After cooling the dispersion to 0.degree. C., 50 g of sodium hydroxide was added to the dispersion, and stirring was continued for 5 hours to obtain core particles.

When the obtained spherical core particles were analyzed by fluorescent X-ray analysis, no residual silica was observed.

Furthermore, the core particles were filtered using a centrifuge and washed with water to determine the particle size distribution (measured using a Coulter counter).
Number average particle size 9.1 lm1 Volume average particle size 10.5 lm,
9 core particles with a volume average particle diameter variation coefficient of 18.7%
Obtained with a yield of 5%.

On the other hand, in a one-liter flask equipped with an autohomo mixer (manufactured by Tokushu Kika Kogyo Co., Ltd.), a thermometer, and a PH meter,
320 g of isopropyl alcohol and 80 g of water were collected, and St-MMA-DM copolymer (copolymerization molar ratio 60:30:10) (Mn = 26,000, Mw) as a shell material was collected.
=67,000, Mw/Mn=2.5, Tg=85.5℃]
8 g (set film thickness δ = 0.20 JL■) was added, and further 8 g of acetic acid was accurately weighed and added to solubilize the copolymer resin. The pH at this time was 5.0.

While maintaining the temperature of the system at 0°C, 100 g of the core particles were added to the solubilized shell material solution obtained above, and the rotation speed was 400 Or
The mixture was stirred at pm for 5 minutes to sufficiently disperse the core particles.

A 28% ammonia aqueous solution was gradually added dropwise to this dispersion,
The addition was continued until the pH of the system reached 10, and encapsulation was performed. At this time, 1 dispersion was centrifuged using a small centrifuge, and further washed thoroughly with 2 fL of water, yielding 95.
% capsule toner was obtained.

At this time, the filtrate obtained from the centrifuge was concentrated using a rotary evaporator.

When xylene was added, the xylene layer was separated using a separating funnel, and the solvent (xylene) was removed again, it was found that the prepared shell material was effectively used for encapsulation at a rate of 97.8%. .

The particle size distribution of the obtained capsule toner had a convergence average particle size of 9.93L11 and a volume average particle size of 11.2JL1.
The variation coefficient of volume average particle diameter was 18.0%. This particle size distribution suggests encapsulation with less free shell and less coalescence. Further, when the triboelectric charge amount of this capsule toner was measured by the method described in U.S. Pat. No. 4,302,201, it was found to be +17,
There was Oa couJl/gte. This also indicates that the shell material sufficiently covers the core particles.

When the obtained capsule toner was applied to PC30 (Canon Co., Ltd. copying machine, pressure fixing) and image printing was performed,
Sufficient image density and fixability were obtained.

A solution (set film thickness: 0.2 wells) in which the shell material was solubilized was obtained.

After adding 100 g of core particles produced by the method described in Example 1 into the shell material solution obtained in this way, the rotation speed of the autohomogen mixer was increased to 500 while maintaining the system temperature at 5°C. Orpm for 5 minutes to sufficiently disperse the core particles in the same manner as in Example 1.

Encapsulation was carried out by gradually adding a 28% ammonia aqueous solution to this dispersion at a dropping rate of 1 cc/min until the pH change rate of the system reached saturation.

After centrifuging this dispersion using a small centrifuge,
A capsule toner was obtained by thoroughly washing with water 21.

The particle size distribution of the obtained capsule toner was as follows (as measured using a coal tar counter): (fil number average particle size was 10.1 gm and volume average particle size was 11.6 pm).
Met. In addition, the amount of triboelectric charge of the capsule toner was determined in Example 1.
When measured in the same manner as above, +18, 5 final coujL
/g, and when the image was printed using PC-30 in the same manner as in Example 1, sufficient image density and fixing properties were obtained as in Example 1.

(manufactured by Titan Kogyo Co., Ltd.) 180 parts by weight Each component of the above recipe was melted and mixed at 150°C, and the air temperature was adjusted to 12%.
After spraying, cooling, and solidifying using a two-fluid nozzle set at 0°C, the mixture was classified to obtain core particles.

When the particle size distribution of the obtained core particles was measured using a Coulter counter, the number average particle size was 8.71 Lm, and the volume average particle size was 10.5 Lm.

Using the above core particle long, St-MMA was used as the a material.
-BA-DE copolymer (copolymerization molar ratio 65:10:5:
20) (Mn=12000.Mw=,40000,Mw
/M n = 3, 3) to 12.1 g (set film thickness 0.
Encapsulation was carried out in the same manner as in Example 1, except that 30#L■) was used.

The particle size distribution of the obtained capsule toner had a number average particle size of 9.6 p+s and a volume average particle size of 11.7 gg+. Also, the amount of triboelectric charge of this capsule toner is l
6, 5 ILcoujL/g. 343 g of ethanol was used as a solvent to solubilize the shell material.
Encapsulation was carried out in the same manner as in Example 1, except that a mixed solvent system consisting of 57 g of water and 10 g of glycerin was used.

The particle size distribution of the obtained capsule toner has a number average particle size of io, IBm, and a volume average particle size of 11.57z+s.
Met. The amount of triboelectric charge of the toner is +17.5 cou
When the image was printed using PC-30 in the same manner as in Example 1, sufficient image density and fixing properties were obtained as in Example 1.

Immediate representative Saruwatari dose line 1 1, -1 Procedural amendment October 2nd, 1986

Claims (1)

[Claims] A dispersion step of dispersing solid core particles containing magnetic particles in a solution of the shell material in an aqueous medium set in an acidic pH range, and a pH of the dispersion obtained in the dispersion step. A method for producing a pressure-fixed magnetic capsule toner, comprising the steps of: coating the surface of a core particle with a shell material by changing the pH of the dispersion to a pH range in which the shell material precipitates.