JPS6057859A - Magnetic microcapsule toner - Google Patents

Abstract

PURPOSE:To improve transfer efficiency and to obtain an image having high image density and high blackness without unevenness by incorporating ultrafine particles of a magnetic material having a grain size and coercive force of specific values as a component into a core material. CONSTITUTION:Single or/and plural ultrafine particles of magnetic materials such as triiron tetraoxide of which the primary particle size is <=0.1mum when observed by an electron microscope are combined to adjust the coercive force thereof to 50-400Oe. Such particles are addd at 15-70pts.wt. to 100pts.wt. the entire resin in a core materialsuch as polyethylene wax. Carbon black, various dyes and pigments, hydrophobic colloidal silica, etc. for controlling electric charge, providing dluidity, coloring, etc., are added or mixed to or with the above-mentioned mixture. A resin consisting of a monomer such as styrene or the like is used as a shell material for coating the core material. A capsule toner having 5-10mum average grain size is thus obtd. The coloring power is improved and the transfer image having good transfer efficiency and through blackness without uneven transfer is thus obtd. by the above-mentioned constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic capsule toner for use in developing electrostatic latent images formed in electrophotography.

Conventionally, the method for manufacturing toner used in electrophotography involves mixing colorants such as carbon black and dyes in various natural or synthetic resins using a blending method, and then
Grinding and pulverizing method; dispersing these materials in a solvent,
A method of pulverization by spray drying; A method of polymerizing an aqueous suspension of a polymerizable monomer while stirring to obtain a fine polymer powder; After dispersing the material in a solvent, the dispersion is A method of obtaining a fine powder by suspending it in a solvent that is incompatible or difficult to miscible with the above-mentioned solvent; a method of suspending a dispersion liquid in the same manner as described above and spray-drying it to obtain a fine powder; or A method is known in which the material is dispersed in a solvent and then stirred and mixed with a solvent that is compatible with the solvent and does not dissolve the resin to form a fine powder.

The above method is suitable for pulverizing a non-adhesive resin to obtain a heat-fixable toner, but is not suitable for pulverizing a sticky resin and obtaining a pressure-fixable toner. It is. That is, it is difficult to form into a toner due to the tackiness of the resin, and even if it can be formed into a toner, the toners tend to aggregate with each other, resulting in a significant decrease in fluidity. In addition, in the case of a two-component toner consisting of toner and a carrier, the toner adheres to the carrier and causes contamination of the carrier, and in the case of a one-component toner consisting only of toner, it adheres to the sleeve via a magnet during development. It causes sleep fusion. Against this background, many methods using microencapsulation methods have been proposed in recent years as a method for turning sticky resin into toner. For example, JP-A-48-90977
In the method described in the publication, a single phase solution consisting of two or more polymeric substances with different solubility is prepared, and by spray drying this, the one with higher solubility is used as a core substance and the surrounding area with lower solubility is formed. However, since it uses a flammable solvent, there is a risk of fire, and in order to prevent fires, the equipment becomes complicated and operational difficulties arise. accompany. Also, JP-A-48-8
No. 0478 forms a mixture of wall materials in a solvent,
The core material is dispersed or dissolved therein to form a dispersion in which the mixture is the dispersed phase, and the solubility characteristics of the solvent with respect to the mixture are varied so that the core and wall materials are sequentially dispersed in a phase fraction of 1 ul. , thus a method of forming a capsule consisting of a core material surrounded by a wall material is disclosed. However, with this method, if a coloring agent or magnetic material is mixed into the core material, the viscosity of this core material is extremely high, and it is difficult to emulsify it into fine particles by stirring (which easily destroys the dispersed phase). Become.

Furthermore, the surface of the magnetic material is usually highly hydrophilic, and therefore the magnetic material contained in the toner material is selectively localized at the particle interface during atomization, and observation with a scanning electron microscope reveals a highly uneven surface state. It shows. As a result, even if a hard shell layer is formed on the surface of the basket core particles in the next step, the resistance is not sufficiently high, and when the toner image obtained by development is electrostatically transferred to a transfer device such as paper, the transfer is extremely difficult. Inefficient,
Another drawback was that the transferred image was uneven. On the other hand, by subjecting the surface of the magnetic material to a hydrophobizing agent, it is possible to encapsulate the magnetic material in the core particles to some extent, but this is not yet fully satisfactory as a toner. In order to make the toner sufficiently high in resistance, attempts have been made to provide a new intermediate insulating layer or to set the thickness of the thin film to the core particle sufficiently large. However, all of these methods involve various problems, such as the process being complicated and the fact that capsule toner particles coalesce with each other during the encapsulation process, which inevitably limits the ability to thicken the film.

The present invention solves these drawbacks by providing a magnetic microcapsule toner in which a core material composed of a soft material containing as an essential component an ultrafine magnetic material that also serves as a coloring agent is colored with a hard shell material. This is what we provide.

Still another object of the present invention is to provide a magnetic microcapsule toner that is characterized by improved transfer efficiency resulting in high image density and uniform images.

Still another object of the present invention is to provide a magnetic microcapsule toner that provides images with high blackness.

That is, the present invention provides an insulating microcapsule toner in which a core material containing a magnetic substance is coated with a hard shell material, in which the primary particle diameter of the magnetic substance is 90.15 m or less as observed with an electron microscope, and Coercive force is 50
This is a magnetic microcapsule toner characterized by having a particle diameter of 4000e.

That is, the present invention uses a magnetic material whose primary particle diameter is 0.1 μm or less as observed by electron microscopy, and even if the magnetic particles are localized at the particle interface. Since the particle diameter of the protruding magnetic substance is extremely small, it is easy to completely cover the core particle containing the magnetic substance with the shell material, and the coloring power is also improved, resulting in good transfer efficiency and even sufficient blackness without uneven transfer. A transferred image having the following characteristics can be obtained.

On the other hand, the ultrafine magnetic particles used in the present invention generally tend to exhibit a very high coercive force, but the magnetic properties of such magnetic substances mean a strong restraining force in the developing device, which is very inconvenient. Therefore, in the present invention, the coercive force can be increased from 50 to 50 by combining a single and/or a plurality of ultrafine magnetic particles whose primary particle diameter is 90.15 m or less as observed by an electron microscope.
The purpose was achieved by adjusting the temperature to 4000e.

As the ultrafine magnetic particles used in the present invention, any magnetic substance having a primary particle diameter of 0.1 μm or less as observed by electron microscopy and a coercive force of 50 to 4000 e can be used in the present invention.

Examples of magnetic substances include triiron tetroxide (Fe304)
rIron sesquioxide (γ-Fe2O3), iron zinc oxide (ZnF
e204) rYttrium iron oxide (Y3Fe5O1
2) #Cadmium iron oxide (CdFe2O4) y Gadolinium iron oxide (Gd5FesO+2) p Copper iron oxide (
CuFe2O4) r Lead iron oxide (PdFe, 2o1.)
, iron nickel oxide (NiFe2O4) + iron neozoum oxide (NdFeO3), iron oxide barium (BaFe
1201q) r Magnesium iron oxide (MgFe
204) *Iron manganese oxide (MnFe04) Lanthanum iron oxide (LaFeO3) rIron powder (Fe), cobalt 1 (Co), nickel powder (Ni), etc. are known, and they can be used alone to satisfy the above conditions. It is used selectively or in combination of two or more types. A particularly suitable magnetic material for the purposes of the present invention is fine particles of triiron tetroxide. The content of this magnetic substance is preferably 15 to 70 parts by weight based on 100 parts by weight of all the resins in the core material.

As the core substance used in combination with the above magnetic material, any substance that exhibits fixability under heat or pressure can be used as appropriate. For example, pressure fixable toners include polyethylene wax, polyethylene oxide, paraffin, fatty acids, and fatty acid esters. , fatty acid amide.

Waxes such as fatty acid metal salts and higher alcohols; ethylene-vinyl acetate resin, cyclized rubber, etc. can be used.

Heat-fixable toners include those exhibiting rubber elasticity such as styrene-butadiene resin, polyester resins having trifunctional or higher functional groups, resins containing carboxylic acid groups crosslinked with metal, or Products with a three-dimensional network structure, such as those created by mixing crosslinking monomers and providing crosslinks between the main chains, are resistant to thermal offset when a heat roll fixing device is used.
By mixing an appropriate amount of a low molecular weight component with these to broaden the molecular distribution, it is possible to keep the fixing temperature relatively low while also improving thermal offset properties.

As the material for the outer shell covering the core material, known resins can be used, such as resins made of the following monomers. Styrene and its substituted products such as styrene, P-chlorostyrene, and P-dimethylaminostyrene; methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, N methacrylate, Esters of acrylic acid or methacrylic acid such as N-dimethylaminoethyl ester; halfesters, halfamides or diesterimides of maleic anhydride or maleic anhydride;
vinylbilysin, noethylaminoethyl methacrylate,
Nitrogen-containing vinyls such as dimethylaminoethyl methacrylate, trimethylaminoethyl methyl methacrylate, trimethylaminoethyl methylmethacrylate, and N-vinylimidazole; vinyl acetals such as vinyl formal and vinyl butyral; vinyl chloride, acrylonitrile.

Vinyl monomers such as vinyl acetate; vinylidene monomers such as vinylitine chloride and hnylidene fluoride; ethylene,
Olefin monomers such as propylene. Also, polyester, 7J? Liquor rnate.

de risulfo, i,), polyamide, polyurethane.

Polyurea, epoxy resin, rosin, modified rosin.

Such as terpene resins, phenolic resins, aliphatic or obscene hydrocarbon resins, aromatic petroleum resins, melamine resins, polyphenylene oxides, ]? Homopolymers, copolymers, or mixtures of riether resins or thioether resins can be used.

As the coloring agent contained in the core material of the capsule toner of the present invention, known dyes and pigments can be used. For example, various carbon blacks, annealing blacks.

Naphthol yellow, molybdenum orange, rhodamine lake, alizarin lake, methyl violet lake, 7 thalocyanine blue, nigrosine methylene blue,
Examples include rose pencil and quinoline yellow.

Carpin black, various dyes and pigments, hydrophobic colloidal silica, etc. can be added to the capsule toner of the present invention for the purpose of charge control, imparting fluidity, coloring, etc., in an amount of /III'=1. The average particle size of the capsule toner is preferably 3 to 20 microns (preferably 5 to 10 microns). - In general, the thickness of a thin film for coating the periphery of a soft solid core with a hard material depends on the state of distribution of the magnetic material present in the core particles. If the magnetic material protrudes onto the surface of the core particle and the coating thickness is sufficiently small compared to the diameter of the magnetic material particles used, the toner will not have sufficient high resistance, resulting in low triboelectric properties. On the other hand, if the film thickness is sufficiently large, the stability of the resulting microcapsule toner is insufficient and coalescence occurs, resulting in only images of extremely poor quality.

Normally, the JNJ circumference of a soft solid core is 0.01 to 2μ by soft material.
The coating is preferably coated to a thickness of 0.1 to 0.5 μm, particularly preferably 0.1 to 0.5 μm.

Various known encapsulation techniques can be used to produce the capsule toner. For example, spray drying method, interfacial polymerization method, coacervation method, phase separation method, in-aitu polymerization method, U.S. Patent No. 3,338,9
The methods described in Specification No. 91, No. 3,326,848 Ming #l Lu, No. M3,502,582 Yu, etc. can be used.

Example 1 "Carnauba wax" (manufactured by Noda Wax Co., Ltd.) 15 parts by weight Microcrystalline wax M-160J (manufactured by Sanoko Co., Ltd.) 15 parts by weight "Hoechst KSL wax" (manufactured by Sanoko Co., Ltd.)
(manufactured by Hoechst) 30 parts by weight "stearic acid" 5 parts by weight "styrene-diethylaminoethyl methacrylate copolymer" 2 parts by weight "triiron tetroxide" 40 parts by weight or more of the substance was heated to 120°C with an attritor. There was crosstalk for an hour. Meanwhile, 2 parts by weight of colloidal silica rAerosil 300J and 21 parts of ion-exchanged water were added to a 3-no-nanano or rubble flask equipped with a homomixer manufactured by Tokushu Kika Kogyo Co., Ltd. and stirred at 1200 rpm until the internal temperature reached 90°C. Warmed.

100 g of the above-mentioned contaminant was added to the mixture, and atomization using a Coulter counter was continued until the volume average particle diameter reached L3 μm. After finishing, cool the dispersion liquid until the final concentration of the solution is 1.
Caustic soda was added so that the concentration was 2. After continuing stirring for 4 hours, using a rotary centrifuge, the filtration and washing operations were repeated until the dispersion was neutralized. After drying, 100 parts by weight of core particles J, 10 parts by weight of a polymer obtained by quaternizing a styrene-dimethyl methacrylate-methyl methacrylate terpolymer with benzyl chloride, and 100 parts by weight of acetone J, was added to a disk atomizer. - A desired microcapsule toner can be obtained by ejecting and atomizing it from a spray drying device equipped with.

Example 2 "Rice wax" (manufactured by Noda Wax Co., Ltd.) 15 parts by weight "Microcrystalline wax M-160J (manufactured by f' Noko Co., Ltd.) 15 parts by weight "Heggist ζ SL wax" (manufactured by Hoechst M) 30 parts by weight "Stearic acid ” 5 parts 1 part “Styrene-dimethylaminoethyl methacrylate copolymer” 2 parts by weight [triiron tetroxide J 40 parts by weight Average particle diameter 0.07 μm Oil absorption (Vloo#) 4
A substance having a coercive force of 1200e or more was heated to 120° C. with an attritor and mixed for 1 hour. Separately, a portion of colloidal silica r Aerosil 300 J 2 M and two volumes of ion-exchanged water were added to a 31-separaglu flask equipped with a homomixer manufactured by Tokushu Kika Kogyo Co., Ltd., and the rotation speed was 1'2000 rpm.
While stirring, the mixture was heated until the internal temperature reached 90°C.

The above kneaded material 10011 was put into this, and the particle size of the dispersed particles was (volume average particle size using a Coulter counter) 1.
Atomization was continued until the particle size reached 3 μm. After completion of the dispersion, the dispersion was cooled and caustic soda was added so that the - of the solution became 12. After stirring for 4 hours, using a rotary centrifuge,
Passage and washing were repeated until neutralized. After drying, encapsulation was continued.

"Core Particle J 100i Denbu "Styrene dimethyl methacrylate copolymer quaternized with benolchloride"l OM characteristics r'iV
A dispersion having a composition of Acetone J 100n or more was placed in a seven-parasol flask, and methanol was gradually added dropwise while stirring thoroughly to obtain a microcapsule toner.

Example 3 r AC405J (manufactured by Allied Chemical Company) 15 parts by weight “C-1702” (manufactured by Allied Chemical Company) 1
5-layer placement section “Hoechst E Wax” (manufactured by Hoechst) 3
0 parts by weight 1 part "polydimethylaminoethyl methacrylate" 2 parts by weight "triiron tetroxide" 40 parts by weight Average particle size 0.05 μm Coercive force 2000e Oil absorption (F/100.!?) 52 The materials shown above were used. A magnetic microcapsule toner was obtained in accordance with Example 1 except for this.

Comparative Example The procedure of Example 1 was followed except that the following core materials were used.

"Carnauba wax" (Noda Wax O) 15 parts by weight "Microcrystalline wax M-160J (Sanoko Co., Ltd. ji (IQ) 15 parts by weight [HEX] KSL wax" (manufactured by Hoechst) 30 parts by weight "Stearic acid"
51 Keibu "Styrene-diethylaminoethyl methacrylate copolymer" 2 parts by weight "Triiron tetroxide" 40 parts by weight Average particle size 0.3 μm Coercive force 2500e Oil absorption (#/1ool 28.5) The obtained microcapsule toner Images were printed using an improved PC-10 machine (manufactured by Yayanon Co., Ltd.).Fixing was performed using a metal roller with a heel pressure of 10 kg/cm as a fixing device.

Claims (1)

[Claims] In an insulating microcapsule toner in which a core substance containing a magnetic substance is covered with a hard shell material, the primary particle diameter of the magnetic substance is 90.1 when observed with an electron microscope.
A magnetic microcapsule toner characterized in that the magnetic substance has a coercive force of 50 to 4000 e and has a coercive force of 50 to 4000 e.