JPH04358160A - Electrostatically chargeable resin particles, toner using same and production thereof - Google Patents

Abstract

PURPOSE:To efficiently and surely stick and bond fine resin particles core particles and to obtain a toner ensuring an excellent combination of electric charge controlling action with environmental resistance and particle characteristics, especially a high kick-off rate of electrified charges, capable of shortening start time from the supply of electric power to the beginning of development, maintaining a relatively low proper level of satd. electric charges and having a narrow electric charge distribution. CONSTITUTION:Resin core particles 2 which are charged to one of polarities in an aq. medium 1 are swollen with an org. solvent, fine resin particles 3 which are charged to the other in the medium 1 are mixed with the swollen particles in the medium 1 and this mixture is heat-treated to tightly bond the fine resin particles 3 to the surfaces of the resin core particles 2.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to chargeable resin particles, toners using the same, and methods for producing the same. The present invention relates to a chargeable resin having a combination of particle properties such as fluidity and a method for producing the same.

0002

[Prior Art] Image formation in electrophotography, electrostatic printing, etc. involves bringing an electrostatic image formed on a substrate into contact with charged toner, and transferring the formed toner image onto paper, etc., if necessary. After the image is transferred, it is fixed by heat or pressure.

The toner used for development is obtained by dispersing a colorant and a charge control agent for controlling the charge in a fixing resin medium and granulating the resulting toner to a predetermined particle size. Various types of charge control agents are known, such as low-molecular organic charge control agents such as various dyes, and high-molecular organic charge control agents made by copolymerizing monomers having charge control functional groups. .

In this type of toner, the toner is charged to a constant polarity due to friction between the toners, between the toners and each member of the developing device, or between the toner and the carrier.
Due to non-uniformity in the dispersion of the charge control agent, the charge distribution tends to be broad, and those with a low charge tend to cause toner scattering and fog, while those with a high charge tend to cause a decrease in image density, etc. There is.

[0005] JP-A-62-226162 discloses colored thermoplastic resin particles of 2 to 30μ particles having an outflow start temperature t1 (°C) in a Koka type flow tester and the above-mentioned t
Micro resin particles with a particle size of 1 μ or less and having an outflow start temperature t2 (°C) higher than 1 (°C) are heat-treated at a temperature of t1 or more and less than t2 to form micro resin particles on the surface of the colored thermoplastic resin particles. Deposited electrostatographic dry toners have been proposed.

[0006] This publication also states that the adhesion of minute resins to the surface of colored thermoplastic resin particles can be achieved by (1) adding a polymerization initiator and part of a polymerizable monomer to a dispersion of colored particles; The remainder of the monomer is gradually added dropwise to form fine particles, and then dried by spray drying or the like within a temperature range of at least the outflow start temperature of colored particles (t1) and below the outflow start temperature of microparticles (t2). (2) After uniformly dispersing pre-synthesized microparticles in a dispersion of colored particles,
A method of drying and adhering by spray drying or the like within a temperature range of less than 2; (3) Pre-dried colored particles and microparticles are uniformly mixed at t1 or less, preferably 50°C or less, and then the temperature is t1 or more and less than t2. It has been shown that a method of adhesion by further mixing and stirring within the temperature range of

[0007]

[Problems to be Solved by the Invention] In the above proposal, efficiency can be improved without adding a charge control agent or by adding only a small amount of charge control agent, due to an increase in the coefficient of friction during rubbing and an increase in surface area due to the presence of fine particles on the surface. Although it is recognized that this proposal makes it possible to obtain the required amount of charge, it is difficult to control the temperature in order to uniformly and reliably attach the microparticles to the colored particles, and the toner's charging characteristics There are also practical problems in terms of control.

That is, the outflow start temperature (t1) of the colored particles (core particles) is a relatively high temperature such as 148° C., but if the heat treatment temperature is lower than the above temperature t1, the microparticles are Effective adhesion becomes difficult. For this reason, in the above-mentioned prior art, the fine particles are finally attached to the core particles in a dry state, but
Controlling the temperature of powder in a dry state is troublesome, and if the heat treatment temperature exceeds the temperature of microparticles t2, a problem will occur in which all the particles will fuse together and form a large agglomerate. Become.

Furthermore, if no charge control agent is used, or if only a small amount is used, the charge build-up speed of the toner is slow, and the charge of each toner particle tends to be quite broad. There are problems in that it takes a long time from turning on the power of the copying machine to starting development, or that image density and image quality tend to fluctuate depending on the time from the start of operation.

[0010] Therefore, the object of the present invention is to provide a charging method in which the adhesion and bonding of fine resin to core particles is carried out efficiently and reliably, and which also has an excellent combination of charge control effect, environmental resistance, and particle properties. The present invention provides a synthetic resin particle or toner and a method for producing the same.

Another object of the present invention is that the rising speed of the charged charge is high, so that the start time from turning on the power to starting development can be shortened, and the saturated charge is also maintained at a relatively low and appropriate level. The object of the present invention is to provide an electrophotographic toner in which the distribution of electric charges is suppressed to a narrow range and can form images of high density and high quality, and a method for producing the same.

Still another object of the present invention is to be able to form toner images of constant density and constant image quality regardless of environmental changes such as humidity, and to have excellent fluidity under developing conditions. To provide an electrophotographic toner capable of forming images free from defects such as fogging, brush marks, trailing, white spots, insufficient density, uneven density, etc. when toner is replenished, and a method for producing the same.

[0013]

[Means for Solving the Problem] According to the present invention, resin core particles charged to one polarity are swollen in advance with an organic solvent in an aqueous medium, and the resin core particles charged to the opposite polarity are swollen in an aqueous medium. A charging property characterized by mixing polarly charged micro resin particles and the above-mentioned swollen resin particles in an aqueous medium, and heat-treating the mixture to firmly bond the micro resin particles to the surface of the resin core particles. A method of making resin particles is provided.

In the present invention, the resin core particles include a polymer charge control agent that controls charge polarity in an aqueous medium and an organic low molecular charge control agent that has a charge control action of opposite polarity to the polymer charge control agent. Preferably, the resin core particles are produced by a suspension polymerization method.
It is preferable to consist of spherical particles with a particle size of 1 to 25 μm.

On the other hand, the fine resin particles are preferably made of a resin containing an initiator fragment or a monomer component having a charge control group that is charged to the opposite polarity to that of the resin core particles in an aqueous medium. The particles preferably consist of spherical particles with a particle size of 0.01 to 2 μm produced by an emulsion polymerization method, particularly a non-emulsion polymerization method.

[0016] The resin core particles and the fine resin particles are mixed in a ratio of 100:
A weight ratio of 0.1 to 100:20, especially 100:0.5
It is preferable to mix at a weight ratio of 100:5 to 100:5.

In another aspect of the present invention, there is provided a resin medium containing a polymeric charge control agent having a charge control effect of a constant polarity, and a resin medium containing a polymeric charge control agent having a polarity opposite to that of the polymeric charge control agent, which is dispersed in the resin medium. A spherical core particle consisting of an organic low-molecular charge control agent having a controlling effect, and a resin containing a monomer or an initiator fragment having a charge control group that is charged to the opposite polarity to the polymer charge control agent of the spherical core particle. There is provided a chargeable resin particle or toner comprising a fine resin particle coating layer, wherein at least the innermost layer portion of the fine resin particle coating layer is embedded in the surface of the core particle.

[0018]

[Function] In the method of the present invention, the first step is to use a combination of resin core particles that are charged to one polarity in an aqueous medium and minute resin particles that are charged to an opposite polarity to the resin core particles in an aqueous medium. This is the first characteristic. That is, by mixing a combination of these resin particles in an aqueous medium, for example, as shown in FIG.
The microscopic resin particles dispersed in an aqueous medium and negatively (or positively) charged are electrically attracted to the surface of the resin core particles 2 which are negatively (or negatively) charged. The coating of the negatively (or positively) charged microparticles 3 is completely and reliably formed on the surface.

Generally, if there are free minute resin particles that are not attached to the resin core particles, only these free minute resin particles will adhere to the electrostatic image, resulting in a problem that a non-colored toner image, so-called white spots, will occur. However, in the present invention, the resin core is removed from the resin core. Since the particles and the fine resin particles are electrostatically bonded in advance, there is no generation of unattached free particles, and this inconvenience is eliminated.

Next, the second feature of the present invention is that the resin core particles to be dispersed in the aqueous medium are swollen in advance with an organic solvent. When bonding microparticles to resin core particles, conventional methods require heat treatment at a temperature within a range that softens the resin in the core particles but does not soften the resin in the microparticles. There are significant restrictions on the selection and combination of various resins, and it is extremely difficult to reliably bond core particles and fine particles while maintaining the toner particle size within a certain narrow range.However, in the present invention, By pre-swollen the resin of the core particles with an organic solvent, it is possible to bond the microparticles to the core particles at a much lower temperature than in the non-swollen state, which eliminates the various limitations mentioned above. At the same time, it is possible to reliably embed and bond fine particles to the surface of the core particle while preventing mutual aggregation of toner particles and maintaining the toner particle size within a certain narrow range.

Furthermore, in connection with the use of the above-mentioned combination of core particles and fine particles and the swelling of the resin core particles with an organic solvent in advance, core particles suspended or dispersed in an aqueous medium can be used. The third feature is that the mixture of microparticles is heat treated in the presence of an aqueous medium. Since the aqueous medium has a large heat capacity and a uniform temperature distribution,
The heat treatment temperature of the entire system can be controlled uniformly and with high precision, and since the heat treatment is performed while the toner is suspended in an aqueous medium, it is possible to perform the heat treatment while preventing the toner particles from coagulating and becoming coarse. becomes.

In the chargeable resin particles or toner according to the present invention, the fine resin particles are controlled to have a constant polarity charge in an aqueous medium, and the coating layer of the fine resin particles controls the electric charge of the final particles such as toner. It has the effect of controlling the polarity to be the same as the electric charge in an aqueous medium. Since this fine resin exists concentratedly on the surface of final particles such as toner, the charge rises rapidly, and therefore has the remarkable advantage of shortening the start time from turning on the power to starting development.

In FIG. 2, which schematically shows the particle structure of a preferable chargeable resin particle or toner (hereinafter simply referred to as toner) of the present invention, this toner 10 consists of a resin core particle 2 and fine resin particles covering the surface of the resin core particle 2. 3 and a covering layer 4. The resin core particles 2 include, for example, a resin medium 5 containing a polymeric charge control agent having a positive (or negative) control effect.
and an organic low molecular weight control agent 6 which is dispersed in this resin medium and has a charge control effect opposite to that of the resin medium, for example, a negative (or positive) control effect. When the core particles 2 are dispersed alone in an aqueous medium, the charge is controlled to be positive (or negative) by the action of the resin medium 5. On the other hand, the fine resin particles 3 forming the coating layer 4 contain a monomer or an initiator fragment having a charge control group having a polarity opposite to that of the polymeric charge control agent, in this case a negative (or positive) control effect. The above components provide a negative (or positive) control effect during dispersion in an aqueous medium and as a final toner.

In this type of toner particle of the present invention, the surface distribution structure of the microparticles and the dispersion structure of the bipolar control agent in the core particles increase the rate of rise of the charge and also maintain the saturation charge at a relatively low appropriate level. It has the extremely desirable effect of maintaining the

FIG. 3 shows toner particles of this type of the present invention (curve A), a conventional suspension polymerized toner containing a single charge control agent (curve B), and a toner corresponding to the core particles of the present invention alone. (Curve C) is plotted with the horizontal axis representing the stirring time in the developing device and the vertical axis representing the amount of charge on the toner particles. These results show that the toner of the present invention exhibits a surprising effect in that the rate of charge rise is faster than that of any other toner, and the saturation charge amount is suppressed to a relatively low range. is understood. In the present invention, the reason why the saturation charge amount is suppressed to a relatively low level is thought to be due to the coexistence of a positive charge control agent and a negative charge control agent in the core particles, which cancel out the charge. .

[0026]

[Preferred embodiment of the invention]

Core particles The core particles used in the present invention are those in which the fixing resin itself has a charge control function, that is, it is made of a polymeric charge control agent, or it is made of a blend of a polymeric charge control agent and another resin. A coloring agent, preferably a low-molecular organic charge control agent, is further blended therein. These core particles may be manufactured by any granulation method known per se, such as a pulverization classification method, a spray granulation method, a hot air granulation method, a suspension polymerization method, etc., but depending on the fluidity of the toner particles and the particle size In terms of uniformity, suspension polymerization is preferred.

In the suspension polymerization method, the polymeric charge control agent may be synthesized during the polymerization process, or the polymeric charge control agent may be synthesized separately, and the polymeric charge control agent may be added to the oil phase in the system. The monomers may be polymerized in the presence of the monomers.

i) Polymeric charge control agent and monomer: The polymeric charge control agent has a charge polarity opposite to that of the final toner, and includes a positively chargeable functional group-containing monomer,
Alternatively, it can be obtained by copolymerizing a monomer containing a negatively chargeable functional group with a monomer constituting a fixing resin for toner.

As positively charged monomers, monomers containing a cationic group such as a basic nitrogen atom, for example,
Dimethylaminoacrylate, dimethylaminoethyl acrylate, diethylaminoethyl acrylate, diethylaminopropyl acrylate, N-aminoethylaminopropyl acrylate, dimethylaminomethacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, diethylaminopropyl methacrylate, N-aminoethylaminopropyl methacrylate, Primary such as vinylpyridine, 2-vinylimidazole, 2-hydroxy-3-acryloxypropylmethylammonium chloride, acrylonitrile,
Monomers containing secondary or tertiary amino groups or quaternary ammonium groups are used.

[0030] As the negatively charged monomer, sulfonic acid,
Anionic monomers such as carboxylic acid, phosphonic acid or salts thereof, preferably monomers having a sulfonic acid or salt group, such as styrene sulfonic acid,
Vinylsulfonic acid, acrylamide methylpropanesulfonic acid, acrylsulfonic acid, methacrylsulfonic acid,
Examples include acrylic-2-ethylsulfonic acid, methacryl-2-ethylsulfonic acid, and their salts such as sodium, potassium, and calcium. Styrenesulfonic acid is particularly preferred from the viewpoint of charge control properties, reactivity, etc. .

Monomers to be copolymerized with these positively chargeable monomers or negatively chargeable monomers include monomers that are generally lipophilic and are used in the production of fixing resins for toners, and various radically polymerizable monomers. Examples include vinyl aromatic monomers, acrylic monomers, vinyl ester monomers, vinyl ether monomers, diolefin monomers, monoolefin monomers, and the like.

Examples of vinyl aromatic monomers include styrene, α-methylstyrene, vinyltoluene, α-chlorostyrene, o, m, p-chlorostyrene, p-ethylstyrene, and divinylbenzene.

Examples of acrylic monomers include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, and 2-hydroxy. Ethyl acrylate, 3-
Examples include hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, ethylene glycol dimethacrylate, and tetraethylene glycol diacrylate.

Examples of vinyl ester monomers include vinyl formate, vinyl acetate, and vinyl propionate. Examples of vinyl ether monomers include vinyl-n-butyl ether, vinyl phenyl ether, vinyl cyclohexyl ether, and the like.

Examples of diolefin monomers include butadiene, isoprene, chloroprene, and the like.

Examples of monoolefin monomers include ethylene, propylene, isobutylene, butene-1,
Examples include pentene-1 and 4-methylpentene-1.

Among these monomers, styrene-based and acrylic-based monomers are preferably used in terms of control of molecular weight distribution, copolymerizability with charge control monomers, and compatibility.

The ratio of positively chargeable or negatively chargeable monomer to lipophilic monomer can be varied over a wide range, but in terms of chargeability, at least 0.5% of positively chargeable or negatively chargeable monomer per polymer. % by weight, especially 2% by weight or more, while from the viewpoint of moisture resistance and fixing properties, the positively chargeable or negatively chargeable monomer should be present in the amount of 20% by weight or less,
In particular it should be present in an amount of up to 15% by weight.

The polymeric charge control agent can be produced using a polymerization initiator by means known per se such as suspension polymerization, emulsion polymerization, solution polymerization, and bulk polymerization. Of course, when producing a polymeric charge control agent in the process of producing core particles, suspension polymerization is naturally carried out.

Examples of the polymerization initiator include azo such as azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), and 2,2'-azobis(2,4-dimethylvaleronitrile). Oil-soluble initiators such as peroxides such as compounds, cumene hydroperoxide, t-butyl hydroperoxide, dicumyl peroxide, di-t-butyl peroxide, benzoyl peroxide, lauroyl peroxide, etc. are used. In addition, combinations of ionizing radiation such as γ-rays, accelerated electron beams, ultraviolet rays, and various sensitizers can also be used. The polymerization initiator is preferably used in an amount of 0.5 to 10 parts by weight per 100 parts by weight of monomer.

[0041] As the coloring agent, the following various pigments and dyes can be used.

Black carbon black, acetylene black, lamp black, aniline black, etc.

Yellow yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, nabels yellow, naphthol yellow S, Hansa yellow G, Hansa yellow 10G, benzidine yellow G,
Benzidine Yellow GR, Quinoline Yellow Lake, Permanent Yellow NGG, Tartrazine Lake, C.I.
I. Solvent Yellow 2, C. I. Solvent Yellow 14, C. I. Solvent Yellow 60 etc.

Orange red yellow lead, molybdenum orange, permanent orange GTR, pyrazolone orange, vulcan orange, indanthrene brilliant orange RK, benzidine orange G, indanthrene brilliant orange GK, C
．． I. Solvent Orange 7th grade.

Red Red Red Red, Cadmium Red, Red Lead, Mercury Cadmium Sulfide, Permanent Red 4R, Lysol Red, Pyrazolone Red, Watching Red Calcium Salt, Lake Red D, Brilliant Carmine 6B, Eosin Lake, Rhodamine Lake B, Alizarin Lake, Brilliant Carmine 3B, C. I. Solvent Red 3, C.
I. Solvent Red 24, C. I. Solvent Red 27 etc.

Purple Manganese Purple, Fast Violet B, Methyl Violet Lake, C. I. Solvent Violet 13 grade.

Blue ultramarine, cobalt blue, alkali blue lake, Victoria blue lake, phthalocyanine blue, metal-free phthaloyanine blue, phthalocyanine blue - partially chlorinated product, fast sky blue, indanthrene blue BC,
C. I. Solvent Blue 7, C. I. Solvent Blue 35 mag.

Green chrome green, chromium oxide, pigment green B,
Malachite Green Lake, Final Yellow Green G, C. I. Solvent Green 15th grade.

[0049] Brown C. I. Solvent Brown 5th class.

0050 White Zinc white, titanium oxide, antimony white, zinc sulfide, etc.

Extender pigments include barite powder, barium carbonate, clay, silica, white carbon, talc, alumina white, etc.

Conductive pigments Conductive carbon black, various metal powders such as aluminum powder, etc.

Magnetic material pigment Triiron tetroxide (Fe3O4), iron sesquioxide (γ-Fe2O
3), iron zinc oxide (ZnFe2O4), iron yttrium oxide (Y3Fe5
O12) Cadmium iron oxide (CdFe2O4), cadmium iron oxide (Gd3Fe
5O12), iron copper oxide (CuFe2O4), iron lead oxide (PbFe12O19)
, iron nickel oxide (NiFe2O4), iron neodymium oxide (NdFeO3)
), barium iron oxide (BaFe12O19), magnesium iron oxide (MgF
e2O4), iron manganese oxide (MnFe2O4), lanthanum iron oxide (LaFeO3)
, iron powder, cobalt powder, nickel powder, etc.

Photoconductive pigments such as zinc oxide, selenium, cadmium sulfide, cadmium selenide, etc.

These colorants may be used alone or in a mixture of two or more, in an amount that provides a sufficient toner image density, for example 0.5 to 30 parts by weight, particularly 1 to 30 parts by weight, per 100 parts by weight of the resin medium. It is used in an amount of 20 parts by weight.

iii) Low-molecular organic charge control agent As the low-molecular organic charge control agent, known dye-based positive charge control agents and negative charge control agents are used. Suitable examples of positive charge control agents are oil-soluble dyes, examples of which are as follows.

[0057] Oleosol Blue G (C.I.Solv
ent Blue 11) Oriental Oil Blue K (C.I.Solvent
Blue 12) Orient Oil Blue BO (C.I. Solvent
Blue 25) Sudan Blue II (C.I.Solvent Bl
ue 35) Sumipurato Blue OA (C.I. Solvent
Blue 36) Pomelo First Blue FLE (C.I.Solven
t Blue 55) Eisenspiron Blue (C.I.Solvent
Blue 73) Sumiplast Green G (C.I. Solvent
Green 3) Orient Oil Black HBB (C.I.Solve
nt Black 3) Nigrosine base (C.I.Solvent Bla
ck 7) Eisenspiron Black BH (C.I.Solven
t Black 22) Eisenspiron Black GSH (C.I.Solve
nt Black 23) Victoria Blue (C.I.Solvent Blue
e 2) Orient Oil Yellow GG (C.I.Solven
t Yellow 2) Pomelo First Yellow CGG (C.I.Solve
nt Yellow15) Eisenspiron Yellow GRH (C.I.Solve
nt Yellow61) Iketon Yellow GR extra (C.I.Solv
ent Orange 1) Eisenspiron Orange GRH (C.I.Solve
nt Orange 37) Eisen Spiron Ferry Red BH (C.I.Sol
vent Red 81) Eisenspiron Pink BH (C.I.Solvent
Red 82) Eisenspiron Red BBH (C.I.Solven
t Red 83) Orient Oil Violet +730 (C.I.So
lvent Violet13) Eisenspiron Violet RH (C.I.Solv
ent Violet 21) etc.

As the negative charge control agent, a carboxyl group-containing compound such as an alkyl salicylic acid metal chelate or a metal-containing complex dye, particularly a complex azo dye containing chromium, iron or cobalt, are used.

Suitable complex salt dyes have the following formula:

[Formula 1] In the formula, A represents a residue of a diazo component having a phenolic hydroxyl group at the ortho position, B represents a residue of a coupling component, M represents chromium, iron or cobalt metal, and [Y
] + is an inorganic or organic cation, represented by 2
: Type 1 metal complex dye. Other sulfonylamine derivatives of copper phthalocyanine may also be used for the purposes of the present invention. Typical examples of these metal-containing complex dyes include Spiron, Opuras Color, Bontron, Kayaset, and the like.

The low molecular weight organic charge control agent is preferably used in an amount of 0 to 5 parts by weight, particularly 0.2 to 1 part by weight, per 100 parts by weight of the resin medium.

iv) Production of core particles Core particles are produced by suspending each of the above components as an oil phase in water and carrying out suspension polymerization. The aqueous medium is preferably used in an amount of 1 to 9 times the total weight of each of the above components.

[0062] In suspension polymerization, it is advisable to use a conventional suspension stabilizer. Examples of suspension stabilizers include conventionally known ones such as water-soluble polymers, poorly water-soluble powdered inorganic compounds, and surfactants. Examples of water-soluble polymers include gelatin, gum tragacanth, starch, methylcellulose, carboxymethylcellulose, polyvinyl alcohol, and polyacrylates. In addition, examples of inorganic compounds include barium sulfate, calcium sulfate,
Barium carbonate, calcium carbonate, magnesium carbonate, calcium phosphate, talc, bentonite, limestone earth,
Examples include clay.

The appropriate amount of suspension stabilizer to be used is usually 3 to 20 parts by weight per 100 parts by weight of suspended particles.

[0064] Suspension of the oil phase in the above suspension polymerization method is carried out using a high-speed shear stage stirrer such as a homomixer or homogenizer, and the core particles can be adjusted to a particle size according to the purpose. When using core particles as toner,
It is preferable to adjust the center particle size to about 1 to 15 μm. Polymerization is usually carried out at a temperature of 50 to 100°C for 2 to 1
It lasts about 2 hours.

Other toner compounding agents can be added to the core particles used in the present invention, if desired. Such toner compounding agents include release agents (offset inhibitors) made of known aliphatic compounds such as aliphatic resins, aliphatic metal salts, higher fatty acids, fatty acid esters, and partially saponified products thereof. ), and aliphatic resins with a low molecular weight (weight average molecular weight of 1,000 to 10,000) are particularly suitable.Specifically, low molecular weight polypropylene, low molecular weight polyethylene, paraffin wax, and resins with a carbon number of 4 or more are suitable. One type or a combination of two or more types of low molecular weight olefin polymers consisting of olefin units is suitable, and silicone oil and various waxes can also be used. These waxes generally have a resin component of 10
It is preferably used in an amount of 1 to 5 parts by weight, particularly 1.5 to 3 parts by weight relative to 0 parts by weight.

Microparticles The microparticles are produced by emulsion polymerization of the monomer components described above in an aqueous medium so that the particle diameter is in the range of 0.01 to 2 μm. The constituent monomers are similar to those of the core particle except that the charge in the aqueous medium is of opposite polarity to that of the core particle. In this case, the desired charge control effect can be obtained by copolymerizing a positively chargeable monomer or a negatively chargeable monomer, but in addition to this, a polymerization initiator that has a charge control effect is selected,
The desired charge control effect can also be obtained by attaching the initiator fragment to the end of the polymer chain.

For example, a persulfate-based polymerization initiator has an anionic sulfonate group bonded to the terminal of the polymer chain, so that a negative charge control effect can be obtained. Similarly, azobis(2-
The use of a basic nitrogen-containing initiator, such as (amidinopropane) hydrochloride, provides positive charge control by the initiator fragment.

The concentration of charge control groups in the microparticles is as follows: resin 1
It is preferably in the range of 1 to 50 mmol, particularly 3 to 30 mmol, per 00 g.

[0069] From the viewpoint of minimizing the influence of humidity on the microparticles and preventing an adverse effect on the electrical properties, it is preferable to manufacture the microparticles by an emulsifier-free emulsion polymerization method. A self-emulsifying effect is obtained due to the polar groups contained in the polymerization initiator and monomer.

As for the polymerization conditions, it is preferable to use 0.1 to 3 parts by weight of a polymerization initiator per 100 parts by weight of monomer, and carry out the polymerization at a temperature of 50 to 100° C. for about 3 to 24 hours.

Production of Toner According to the present invention, resin core particles are suspended in an aqueous medium and swollen with an organic solvent. As an organic solvent,
Depending on the type of resin, for example, aromatic solvents: toluene, xylene, benzene, etc. Ester: alkanes such as ethyl acetate, propyl acetate, etc.
: Ketones such as hexanone and cyclohexane
: Cyclohexane, methyl isobutyl ketone, etc. Alcohol : Select an appropriate one from amyl alcohol, cyclohexanol, etc. Aromatic solvents are generally preferred.

These organic solvents are preferably used in an amount of 0.1 to 10 parts by weight, particularly 1 to 5 parts by weight, per 100 parts by weight of the core particles. When an organic solvent is added to the core particle suspension and stirred, the organic solvent is absorbed into the core particles, causing swelling of the resin. This process proceeds well at room temperature, but
Swelling can also be made more rapid by heating to about 0°C.

Next, the swollen core particles and fine resin particles are mixed in an aqueous medium. In this case, the ratio between the core particle and the fine particle is 100:0.1 to 100:20, especially 100:
It is desirable to mix at a weight ratio of 1 to 100:4. If an inorganic suspension stabilizer is present in the core particle,
It is preferable to add hydrochloric acid to the mixture of the two to solubilize the inorganic salt as a hydrochloride salt and remove it from the core particles in order to promote electrical bonding between the core particles and the microparticles. Also,
By adding hydrochloric acid, the positively charged groups (basic nitrogen atoms) contained in the core particles or microparticles are cationized, and electrical bonding between the core particles and the microparticles proceeds smoothly.

[0074] Next, the aqueous liquid containing the core particles and fine particles is heat treated. This causes the microparticles to become embedded in the surface of the core particle, creating a strong bond. The temperature of the heat treatment depends on the type of resin, but is generally in the range of 20 to 80°C, particularly 30 to 60°C.

The heat-treated toner particles are dehydrated by filtration, centrifugation, etc., washed with water if necessary, and then dried by vacuum drying or the like to form a product.

The obtained toner particles can be used as is as a toner for a two-component developer or a one-component toner, or they can be used as a toner for a two-component developer or a one-component toner.
It can be added in an amount of about 5 to 0.5% by weight and used as the above-mentioned toner. The chargeable resin particles according to the present invention are particularly useful as electrophotographic toners, but can also be used in other applications such as electrostatic powder coating.

[0077]

EXAMPLES The present invention will be explained in more detail with the following examples.

(Synthesis of negatively chargeable charge control copolymer 1)
styrene

60 parts by weight α-phenylvinylphosphonic acid
40
Parts by weight 2,2'-azobis(2,4-dimethylvaleronitrile) 10 parts by weight Methyl alcohol

400 parts by weight

[0079] The mixture was subjected to a polymerization reaction at 80°C for 12 hours under a nitrogen atmosphere with gentle stirring. The obtained polymer was pulverized by evaporation to obtain a negatively chargeable charge control copolymer 1.

(Synthesis of negatively chargeable charge control copolymer 2)
styrene

90 parts by weight Sodium styrene sulfonate
10 parts by weight azobisisobutyronitrile
10 parts by weight polyacrylic acid

10 parts by weight isopropyl alcohol
6
00 parts by weight water

200 parts by weight

[0081] These mixtures were subjected to a polymerization reaction at 60°C for 12 hours under a nitrogen atmosphere and with gentle stirring. The resulting polymer was centrifuged to replace the medium with methanol, and then evaporated to powder to obtain a negatively chargeable charge control copolymer 2.

(Core particle synthesis example 1) Styrene

90 parts by weight dimethylaminoethyl methacrylate
10 parts by weight divinylbenzene

0.7 parts by weight 2-ethylene glycol dimethacrylate
1.5 parts by weight metal-containing dye, Bontron
S-34 (Orient Chemical, trade name)

3 parts by weight Carbon black, MA-100 (manufactured by Mitsubishi Chemical Corporation, trade name)
5 parts by weight Polymerization initiator, 2,2'-azobis(2,4-dimethylvaleronitrile)

3 parts by weight Polymerization initiator, 2,2'-azobis(2-methylbutyronitrile)

1 part by weight

0083
] A mixture of these was added to 800 parts by weight of water, 100 parts by weight of tricalcium phosphate TCP-10 (manufactured by Taihei Kagaku Sangyo, trade name, solid content concentration 10%) and 0.0 parts by weight of sodium laurate.
012 parts by weight was added to the continuous phase, granulated using a homo mixer, and a polymerization reaction was carried out at 80° C. for 8 hours with gentle stirring. The obtained polymer was washed with water, filtered, and redispersed three times to obtain a positively charged core particle suspension 1.

(Core Particle Synthesis Example 2) In place of 10 parts by weight of dimethylaminoethyl methacrylate in Core Particle Synthesis Example 1, 1 part by weight of diethylaminopropyl methacrylate was added.
Positively charged core particle suspension 2 was obtained in the same manner as in core particle synthesis example 1 except that 0 part by weight was used.

(Core particle synthesis example 3) Styrene

90 parts by weight of negatively chargeable charge control copolymer 1

10 parts by weight divinylbenzene

0.7 parts by weight 2-ethylene glycol dimethacrylate
1.5 parts by weight metal-containing dye, Bontron, N-11 (manufactured by Orient Chemical, trade name)

2 parts by weight carbon black, MA-100 (manufactured by Mitsubishi Kasei Corporation, trade name)
5 parts by weight polymerization initiator, 2,2'-azobis(2,4-dimethylvaleronitrile)

3 parts by weight polymerization initiator, 2,2'-azobis(2-methylbutyronitrile)

1 part by weight

[0086]
These mixtures were mixed with 800 parts by weight of water, 100 parts by weight of tricalcium phosphate TCP-10 (manufactured by Taihei Kagaku Sangyo, trade name, solid content concentration 10%) and 0 parts by weight of sodium lauryl sulfate.
．． 012 parts by weight was added to the continuous phase, granulated using a homomixer, and a polymerization reaction was carried out at 80° C. for 8 hours with gentle stirring. The obtained polymer was washed with water, filtered, and redispersed three times to obtain a negatively charged core particle suspension 3.

(Core particle synthesis example 4) Using 3 parts by weight of negatively chargeable charge control copolymer 2 instead of 10 parts by weight of negatively chargeable charge control copolymer 1 in core particle synthesis example 3, A negatively charged core particle suspension 4 was obtained in the same manner as in core particle synthesis example 3 except that 97 parts by weight of the styrene monomer was used instead of 90 parts by weight.

(Synthesis example 1 of microparticles) Styrene

72 parts by weight 2-ethylhexyl methacrylate
25 parts by weight Sodium styrene sulfonate

3 parts by weight water

900 parts by weight Polymerization initiator, potassium persulfate
1 part by weight

Negatively charged fine particle suspension 1 was obtained by carrying out a polymerization reaction of these mixtures at 80° C. for 6 hours with gentle stirring.

(Synthesis example 2 of microparticles) Styrene

72 parts by weight 2-ethylhexyl methacrylate
25 parts by weight dimethylaminoethyl methacrylate
3
Part by weight water

900 parts by weight Polymerization initiator, Azobis (
2-amidinopropane) hydrochloride

1
Weight part

[0091] These mixtures were heated to 80°C with gentle stirring.
A positively charged microsuspension 2 was obtained by carrying out a polymerization reaction for 6 hours.

Example 1 To 100 parts by weight of positively charged core particle suspension 1, 5 parts by weight of toluene was added.
A swollen positively charged core particle suspension 1 was obtained by adding parts by weight and stirring for 24 hours. 3 parts by weight of this swollen positively charged core particle suspension 1 and negatively charged fine particle suspension 1 were mixed, and 12 parts by weight were mixed.
Add 20 parts by weight of specified hydrochloric acid, and stir at 60°C for 3 hours with gentle stirring.
By performing heat treatment for 0 minutes, the microparticles were fixed to the surface of the core particles. After removing toluene by reducing the pressure at 60° C., the toner particles of the present invention were obtained by washing, filtering, drying, and crushing.

When the particle size distribution of this toner was measured using a Coulter counter, the volume-based median diameter D
No. 50 had a sharp particle size distribution of 11.2 μm.

0.0% per 100 parts by weight of the obtained toner.
A developer having a toner concentration of 3.8% was prepared by mixing 1 part by weight of hydrophobic silica fine powder and mixing with a silicone resin-coated ferrite carrier. Electrophotocopy machine, D
Using C-2585 (manufactured by Sanda Kogyo Co., Ltd., trade name), the obtained developer was subjected to a 2000-sheet printing durability test to evaluate the image quality and the durability of the developer. The evaluation results of this toner are shown in Table 1.

Example 2 A toner was synthesized in the same manner as in Example 1, except that 100 parts by weight of positively charged core particle suspension 2 was used instead of positively charged core particle suspension 1 in Example 1. evaluated. The obtained toner had a D50 of 10.7 μm and a sharp particle size distribution. The evaluation results of this toner are shown in Example 1.
It is also shown in Table 1.

Example 3 100 parts by weight of negatively charged core particle suspension 3 was used instead of positively charged core particle suspension 1 of Example 1, and positively charged fine particle suspension was used instead of negatively charged fine particle suspension 1. A toner was synthesized in the same manner as in Example 1, except that 3 parts by weight of Suspension Liquid 2 was used.

The obtained toner had a D50 of 10.2 μm and a sharp particle size distribution. A developer having a toner concentration of 3.8% was prepared by mixing 0.1 part by weight of hydrophobic silica fine powder with 100 parts by weight of the obtained toner and mixing it with a ferrite carrier coated with a silicone resin. . Evaluation was performed using an electrophotographic printer, LPX-1 (manufactured by Sanda Kogyo Co., Ltd., trade name). The evaluation results of this toner are shown in Table 1 as in Example 1.

Example 4 100 parts by weight of negatively charged core particle suspension 4 was used in place of the negatively charged core particle suspension 3 of Example 3, and 3 parts by weight of negatively charged fine particle suspension 1 of Example 1 was used. A toner was synthesized in the same manner as in Example 3, except that 3 parts by weight of negatively charged fine particle suspension 2 was used instead of 3 parts by weight, and the D of the obtained toner was evaluated.
No. 50 had a sharp particle size distribution of 10.5 μm. The evaluation results of this toner are shown in Table 1 as in Example 1.

Comparative Example Toners of Comparative Examples were obtained in the same manner as in the Examples except that the swelling aid (toluene) of Examples 1 to 4 was not used. However, as the printing durability test progresses, the fine particles on the surface of the core particles detach and accumulate in the developer, leaving a layer on the drum covered with the detached particles and a layer covered with toner all over the surface. It gets stuck and cannot be cleaned.
Fogging occurred on the entire surface.

[0100]

[Table 1] *In each of the comparative examples, the fine particles on the surface of the core particle detach as the printing durability test progresses and accumulate in the developer, leaving a layer covered with the detached fine particles on the drum. Toner adhered to the entire surface, and it was no longer cleaned, resulting in fogging over the entire surface. Image quality evaluation ○: Good image without fogging △: Slight fogging ▲: Too much fogging ×: Toner scatters from the developing sleeve

[0101]

[Effects of the Invention] According to the present invention, when attaching and bonding fine resin to resin core particles, the charges of these particles in an aqueous medium are made to have opposite polarities, and the core particles are swollen in advance with an organic solvent. This makes it possible to reliably embed microparticles on the surface of the core particles and bond them together while preventing toners from agglomerating and maintaining the toner particle size within a certain narrow range, without any particular restrictions on the combination of resins used. became.

Furthermore, in this toner, since the charge control layer is limited to the vicinity of the surface, the charge build-up speed is high, the start time from turning on the power to starting development can be significantly shortened, and the charge distribution is also relatively small. It also has the advantage of being kept at a narrow level.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the dispersion and charging state of core particles and fine resin particles in an aqueous medium.

FIG. 2 shows suitable chargeable resin particles or toner of the present invention (
FIG. 2 is an explanatory diagram schematically showing the particle structure of a toner (hereinafter simply referred to as toner).

FIG. 3: Toner particles of this type according to the invention (curve A),
Conventional suspension polymerization toner containing a single charge control agent (curve B
), and the toner (curve C) corresponding to the core particles of the present invention alone, is a graph plotted with the horizontal axis representing the stirring time in the developing device and the vertical axis representing the amount of charge on the toner particles.

[Explanation of symbols]

Reference Signs List 1 aqueous medium, 2 resin core particles, 3 fine resin particles, 4 coating layer, 5 resin medium containing polymeric charge control agent, 6 organic low molecular weight control agent, 10 toner.

Claims (8)

[Claims] Claim 1: Resin core particles that are charged to one polarity in an aqueous medium are swollen in advance with an organic solvent, and minute resin particles that are charged to the opposite polarity to the resin core particles in an aqueous medium and the swollen resin particles are prepared. 1. A method for producing chargeable resin particles, which comprises mixing the above in an aqueous medium, and heat-treating the mixture to firmly bond the fine resin particles to the surface of the resin core particles. 2. The resin core particles contain a polymeric charge control agent that controls charge polarity in an aqueous medium and an organic low-molecular charge control agent that has a charge control action with a polarity opposite to that of the polymeric charge control agent. The method according to claim 1, comprising particles containing. 3. The method according to claim 1, wherein the resin core particles consist of spherical particles having a particle size of 1 to 25 μm produced by a suspension polymerization method. 4. Any one of claims 1 to 3, wherein the minute resin particles are made of a resin containing an initiator fragment or a monomer component having a charge control group that is charged to the opposite polarity to that of the resin core particle in an aqueous medium. The manufacturing method described in. 5. The method according to claim 1, wherein the fine resin particles are spherical particles having a particle size of 0.01 to 2 μm produced by an emulsifier-free emulsion polymerization method. [Claim 6] The number of resin core particles and fine resin particles is 10.
6. The method according to claim 1, wherein the ingredients are mixed at a weight ratio of 0:0.1 to 100:20. 7. A resin medium containing a polymeric charge control agent having a charge control function of a constant polarity, and an organic compound dispersed in the resin medium and having a charge production function of a polarity opposite to that of the polymeric charge control agent. Coating of spherical core particles consisting of a molecular charge control agent and fine resin particles of a resin containing a monomer component or an initiator fragment having a charge control group that is charged with a polarity opposite to that of the polymeric charge control agent of the spherical core particles. A chargeable resin particle comprising a layer, at least the innermost layer of the fine resin particle coating layer being embedded in the surface of the core particle. 8. An electrophotographic toner comprising the chargeable resin particles according to claim 7.