JPH026052B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for manufacturing a capsule toner used for electrostatic photography or magnetic recording. [Prior art] Conventionally, electrophotographic development methods include powder cloud method, fur brush method, cascade development method,
Magnetic brush development methods are known, and the toners used in these methods are colored fine powders in which dyes and pigments are dispersed in natural or synthetic resins. For example, the magnetic brush development method that is currently in widespread use uses a two-component developer called carrier, which is a mixture of iron powder and toner. In the case of such a two-component developer, in order to maintain good development, maintenance and adjustment to prevent carrier contamination, toner concentration fluctuations, etc. are required, which is complicated. A developing method using a one-component developer containing powder is beginning to be developed and put into practical use. If you want to keep the developed toner image,
An operation called "fixing" is performed. Such fixing methods include methods of melting and adhering the toner with a heat chamber, methods of melting the toner with a heat roller and pressing the toner onto the support surface at the same time, and methods of melting and adhering the toner using a solvent and then fixing the toner. Methods of removing the solvent and methods of applying and fixing a resin solution called a fixer onto the image are known, but energy-saving fixing methods such as pressure fixing using rigid rollers are recommended from the viewpoint of energy saving and non-pollution. It is changing to. The pressure fixing method has the following advantages: there is no risk of burning the copy sheet, the copying can be done without any waiting time when the copier is turned on, high-speed fixing is possible, and the fixing device has a simple structure. There are many advantages. However, while current pressure fusing methods have the above-mentioned major advantages, they also have several significant drawbacks. One of them is that a linear pressure of 30 to 40 kg/cm is generally required for fixing, and in order to apply this much pressure, the fuser needs to be quite strong, which means that the fuser needs to be large.・It is undesirable because it becomes heavy. Furthermore, it is extremely difficult to uniformly apply such pressure to the paper, and the transfer paper may wrinkle or curl. Another disadvantage is that when applying pressure as described above with a roller on the image,
The surface of the image becomes smooth and the image becomes glossy, degrading the quality of the image. In order to overcome these drawbacks, for example, fixing can be performed with low energy such as low fixing pressure, and toners that can be fixed with low pressure are being actively developed. However, it has excellent fixing performance with low energy, does not cause offset phenomenon to the pressure roller, and has stable developing performance and fixing performance even after repeated use.
A practical low-energy fixing toner with excellent storage stability that does not cause adhesion to the carrier, metal sleeve, or photoreceptor surface, and does not cause aggregation or caking during storage has not been obtained. [Problems to be Solved by the Invention] The present invention has been made in view of the above points. An object of the present invention is to provide a method for producing a microcapsule toner that has high-performance fixing properties even with low energy. Still another object of the present invention is to provide a method for producing a pressure-fixable microcapsule toner in which the fixability changes little with respect to pressure. Still another object of the present invention is to provide a method for producing a microcapsule toner that is speed independent and suitable for high speed fixing. Still another object of the present invention is to provide a method for producing a microcapsule toner that does not cause offset to a pressure roller or adhesion to a metal sleeve or photoreceptor surface. Still another object of the present invention is to provide a method for producing a microcapsule toner that has stable developing performance and fixing performance for repeated use and does not cause aggregation or caking during storage. [Means and effects for solving the problems] Specifically, the present invention provides a method for producing a capsule toner comprising a core material and an outer shell covering the core material, which has a melt viscosity of 1 to 1 at 100°C. A mixture containing at least a compound having a hydrocarbon chain of 30 cps and a coloring material is heated and melted, and the molten mixture is kneaded with a solid medium to disperse the coloring material into particles of 2μ or less. After preparing the product, the solid media is removed, core material particles are prepared from the prepared kneaded material, and the prepared core material particles are coated with a shell material, so that at least 50% of the capsule toner particles have an average particle size of ±4μ. The present invention relates to a method for manufacturing a capsule toner, which is characterized in that the capsule toner is produced within the following range. Compounds having a hydrocarbon chain with a melt viscosity of ₁ to 30 cps at 100°C are C12 to _C50 hydrocarbons, fatty acids and their esters, metal soaps, fatty alcohols, polyhydric alcohols, and their metal salts or their chlorides. compounds, fluoride amides, bisamides, etc. Specifically, the long-chain compounds having a carbon chain of _C12 to _C50 mentioned above include the following. (1) Normal and isoparaffins represented by CnH ₂ n+2 (n = 12 to 50) and compounds having some unsaturated bonds in them. Examples include C ₂₈ n-Octacosane C ₃₂ n-Dotriacontane C ₃₆ n-Hexatriacontane It also includes squalene C ₃₀ H ₅₀ and squalane [2, 6, 10, 15, 19, 23 hexamethyltetracosane (C ₃₀ H ₆₂ )]. (2) Fatty acids having hydrocarbon chains as described above, such as those shown in the table below.

【table】

[Table] (3) Alcohols and esters thereof can also be used, for example as shown in the following table.

[Table] (4) Chlorides of the above substances, such as chlorinated paraffin, can also be used. (5) Amides and bisamides having a C ₁₂ to _{C 50} hydrocarbon chain can also be used, for example as shown in the following table.

[Table] These products are commercially available singly or as a mixture. Generally, they are known as paraffin wax, microcrystalline wax, montan wax, ceremin wax, ozokerite, carnauba wax, rice wax, Sierra wax, Zasol wax, metal wax, amide wax, and lubricant. Manufacturers and product names include paraffin wax (Japan Oil), paraffin wax (Japan Oil), microwax (Japan Oil), microcrystalline wax (Japanese wax), Hoechst wax (hoechst AG), and diamond. These include Watkusu (Shin Nippon Rika), Suntite (Seiko Chemical), and Panacet (Nippon Oil & Fats). Typical grades of paraffin waxes include those shown in the table below.

【table】

[Table] Other examples include Hoechst Wax OP (Partially saponified ester wax of montanic acid, Hoechst AG) E (Ester wax of montanic acid, Hoechst AG)
AG) GL3 (partially saponified synthetic wax, Hoechst AG), etc. Of course, several types of polymeric substances and some long-chain compounds may be used in combination, if necessary. These materials are mixed with a coloring material, atomized by an appropriate method, and then microencapsulated using a shell material. The present inventors investigated pressure-fixable microcapsule toner for fixing with low fixing pressure, and found that the conventional pressure-fixable microcapsule toner for fixing with low fixing pressure has its components and low melt viscosity. Particles in which there is no coloring material inside the toner particles due to insufficient dispersion due to the use of a substance;
Alternatively, it has been found that a large number of particles in which the coloring material in the toner particles is unevenly distributed is generated, which deteriorates the performance as a toner and has an adverse effect on image quality, durability, stability, etc. Furthermore, in order to obtain sufficient performance for practical use with pressure-fixing microcapsule toners that fix at such low fixing pressures, uniform particle size distribution is required, which has a significant impact on fixing performance especially at low pressures. I discovered that. The present inventors have discovered that the particles of the coloring material are dispersed in the toner particles so that they are 5μ or less, more preferably 2μ or less, and that the toner has a particle size distribution and that 50% or more of the particles are on average Particle±
It has been found that a practical microcapsule toner can be obtained by adjusting the thickness to within 4μ. One method for obtaining the capsule toner of the present invention is to use a dispersing device that uses solid media as a dispersing device to reduce the size of particles of the coloring material to 5 μm or less. Dispersion devices using solid media include ball mills, sand mills, and attritors, and various types such as glass beads, steel balls, alumina, and ceramics are used, and various shapes and sizes are also used. Various methods have been known for melting and dispersing toner components, such as triple-roll and twin-screw extruder kneaders. In a toner containing a compound having a hydrocarbon chain and a coloring material, the toner fine particles targeted by the present invention cannot be obtained, but the coloring material contained therein exists in the toner fine particles as particles of 5 μm or more, and is not melt-dispersed. When a product is made into fine particles by a known method such as pulverization, the coloring material in the particles becomes unevenly distributed or the component ratio becomes uneven. As a result, the electrostatic properties, magnetic properties, color properties of each toner particle,
causing unevenness or imbalance in physical properties such as smoothness,
For example, there may be a difference in the color of the toner itself due to insufficient dispersion of the coloring material, or a difference in hue or density between the initial image reproduction and the repeated use by a copying machine. In addition, for example, the uneven distribution of the coloring material in the resin and the coloring material ratio in the toner particles are extremely different for each toner particle, resulting in different strengths for each particle. A smearing phenomenon may occur, or image fixation may become uneven, resulting in non-fixing, offset, etc. In addition, for example, the uneven distribution and ratio of the coloring material may vary from particle to particle, resulting in nonuniform electrostatic and magnetic properties of each toner particle (i.e., nonuniform or unstable developability, transferability, etc.). ),
Adverse effects on image quality and durability, such as changes in image density, are likely to occur. In the present invention, these problems are prevented by improving the dispersion of the coloring material,
We were able to improve toner performance. To obtain the core particles of the capsule toner of the present invention,
It is preferable to adopt a method in which particles are obtained by heating a raw material kneaded dispersion (pulverized into fine particles in a molten state), and the particles are stabilized by cooling. As this method, a spray drying method, a suspension method, an emulsification method, etc. can be used. By forming core particles using these methods, toner particles in which the coloring material is uniformly distributed from the center of the core particle toward the surface can be easily obtained.
The present inventors have found that the core particles produced by this method have a reduced possibility that colored material particles will appear on the surface of the core particles. This provides many useful properties for toners, such as uniform physical properties such as electrical properties, smooth surfaces, and chemical uniformity that makes them easier to encapsulate. There is. In the present invention, in order to obtain the required particle size distribution (50% or more of the toner particles have an average particle size within ±4 μm), the particles must be obtained by a controlled granulation method, or the desired particles can be obtained by a classification operation. ,
After further encapsulation, it is classified and used as necessary. In order to check the degree of dispersion of the colored substance, the toner can be dispersed in an embedding resin such as epoxy resin, cured, cut into ultrathin sections using a microtome, etc., and observed using a transmission electron microscope. . Although various particle size distribution measuring devices can be used to determine the particle size distribution, a device that can measure the number of particles as large as possible is preferred. One example of a preferred measuring device is a device that disperses particles in an electrically conductive liquid and measures the particle size based on changes in transmitted conductivity, which is commercially available as a so-called Coulter counter, and the aperture can be appropriately selected. By this, toners with various particle sizes can be manufactured. Known resins can be used as the shell material of the microcapsule toner of the present invention, such as polystyrene, polyp-chlorostyrene, monopolymers of styrene and substituted products thereof such as polyvinyltoluene, and styrene-p-chlorostyrene. Copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate Copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α chloromethacrylate Methyl copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer Polymers, styrenic copolymers such as styrene-acrylonitrile-indene copolymers, styrene-maleic acid copolymers, styrene-maleic acid ester copolymers, polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyacetic acid Vinyl, polyethylene, polypropylene, polyester, polyurethane, polyamide, epoxy resin, polyvinyl butyral, rosin, modified rosin, terpene resin, phenolic resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, urea resin, melamine Resins can be used alone or in combination. Moreover, a known method is applied as the microencapsulation method. For example, a spray drying method, a liquid drying method, a phase separation method, an in-situ polymerization method, etc. can be used, and in order to give the toner of the present invention insulating properties and appropriate triboelectric charging properties, a multilayer shell structure is provided. It's okay. Furthermore, the toner of the present invention is used as a one-component magnetic toner, mixed with carrier particles such as iron powder, glass beads, nickel powder, ferrite powder, etc., as needed, as a developer for electrical latent images. It can also be used in combination with hydrophobic colloidal silica fine powder for the purpose of improving the free-flowing properties of the powder, and abrasive fine particles such as cerium oxide for preventing toner adhesion. [Example] Next, the present invention will be explained with reference to Examples. Example 1 Paraffin with a melting point of 70°C (viscosity at 100°C
10cps) 70 parts polyethylene wax (viscosity at 100℃
100 cps) 30 parts Phthalocyanine blue 10 parts The above mixture was heated and melted, mixed for 10 minutes in a mixer at a rotation speed of 100 rpm, and then kneaded for 1 hour in a sand mill containing a ball made of glass beads with a diameter of 2 mm as a solid medium. The pot during kneading was heated to 110°C with oil. After removing the kneaded material from the sand mill while removing the glass bead balls, it was supplied to a two-fluid nozzle equipped with a 4 kg/cm ² compressed air supply device heated to 200°C, atomized, and then in air. After cooling, it was collected in a cyclone. The obtained particles were spherical particles with an average size of about 12 μm, and when they were embedded in epoxy resin, ultrathin sections were made with a microtome, and observed with a transmission electron microscope, it was found that even the largest particle of the colored material was 1.5 μm in size. Ta. This is encapsulated using the spray method, with an average of 0.2μ
The capsule has a wall thickness of . Styrene acrylic resin was used as the wall material. In addition, the obtained particles were placed in a Coulter counter TA-
When the particle size distribution was measured using a mold, the average particle size was
11.66μ, and from the volume distribution data it was found that the average particle ±4μ had 55.2%. When the obtained capsule toner was mixed with an iron powder carrier having an average particle size of 200 μm and a positive electrostatic latent image was developed, a clear image was obtained. When the developed image was transferred to transfer paper and passed through a pressure roller with a linear pressure of 25 kg/cm, a completely fixed image was obtained. Comparative Example 1 An experiment was conducted in the same manner as in Example 1 except that polyethylene wax was used instead of paraffin having a melting point of 70°C. The particles obtained were spherical with an average size of about 25 μm, and the maximum shape of the colored particles was 2.5 μm. A capsule toner was manufactured using these particles.
The average particle size measured by Coulter counter is
25.3μ, and from the volume distribution data it was found that 43.2% of the particles were present within the average particle ±4μ. When an image evaluation experiment was conducted, an extremely unclear image was obtained, and the image was removed even when lightly rubbed with the hand. Also, after a few shots, almost no images came out. Example 2 Paraffin with a melting point of 70°C (viscosity at 100°C
10 cps) 40 parts Carnauba wax 60 parts Magnetic material (magnetite) 60 parts The above mixture was heated and melted, mixed for 10 minutes in a mixer at 100 rpm, and then mixed in a sand mill containing a ball made of glass beads with a diameter of 1.5 mm. Kneaded for hours. The pot in the mix was heated to 120°C with oil. After the kneaded material was taken out, it was fed into hot water heated to 95° C. and dispersed using a high-speed stirrer.The dispersion was then rapidly cooled, centrifuged, and further dried to obtain particles. Using the phase separation method, this is encapsulated and the average
The capsules had a wall thickness of 0.18μ. Styrene/acrylic resin was used for the wall material. When the particle size distribution of the toner was measured using a Coulter counter, the average particle size was found to be 10.58μ, and from the volume distribution data, it was found that 65% of the toner particles were within the average particle size ±4μ. When the obtained capsule toner was applied to a developing device having a magnetic sleeve, clear images were obtained. When the developed image was transferred to transfer paper and passed through a pressure roller with a linear pressure of 17 kg/cm, a completely fixed image was obtained. Furthermore, the maximum size of the coloring material in the toner was 2.0μ. Comparative Example 2 The same procedure as in Example 2 was carried out except that the kneading using a sand mill was performed. The resulting toner was found to have an average particle size of 20.5μ and an average particle size of ±4μ of 23%. The maximum size of the coloring material in the toner was 7.8μ. When this toner was used for development in the same manner as in Example 2, only unclear images with a lot of fog were obtained, and the images stopped appearing after several sheets. Also, the transferred image came off just by lightly touching it with my finger. Comparative Example 3 The same procedure as in Example 2 was carried out, except that paraffin with a melting point of 70°C and paraffin with a viscosity of 0.8 cps at 100°C were used instead of carnauba wax. It was found that the average particle size of the resulting toner was 8.2μ, with 35% of the particles existing within the average particle size ±4μ. Images obtained with this toner were unclear and had a low temperature. Also, after a few 10 shots, almost no images came out. [Effects of the Invention] The microcapsule toner of the present invention can be fixed with lower energy than conventional toners, and can provide clear images with high image density and no fog. Further, such toner can be fixed with low energy, and even when a large number of copies are made in succession, a homogeneous image can be obtained without any change in characteristics. Furthermore, it has excellent stability during storage and stability in various environments.

Claims (1)

[Claims] 1. A method for producing a capsule toner consisting of a core material and an outer shell covering the core material, in which a mixture containing at least a coloring material and a compound having a hydrocarbon chain with a melt viscosity of 1 to 30 cps at 100°C is heated. After melting and kneading the molten mixture with solid media to prepare a kneaded product in which the coloring material is dispersed in particles of 2μ or less, the solid media is removed, and core material particles are extracted from the prepared kneaded product. and coating the prepared core material particles with a shell material to produce a capsule toner in which 50% or more of the capsule toner particles have an average particle size within ±4μ.