JPS5946388B2 - Heat-sublimable microcapsule toner and method for fixing images of this toner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-sublimable dry microcapsule toner used in electrophotography, electrostatic recording, electrostatic printing, etc., and a method for fixing images formed using this toner.

Conventionally, developers used in electrophotography, etc., are generally wet-type developers in which toner is fine resin powder coated with a colorant and dispersed in an insulating liquid (solvent), and wet-type developers. They are broadly classified into two-component dry developers, in which large toner is mixed with a suitable powder called a carrier, and one-component dry developers, in which toner and carrier are integrated.

Among these, in wet-type developers, the toner is dispersed and swollen in the liquid, so even if it is separated from the liquid after development, the toner retains its self-fixing properties and therefore does not require special fixing. However, since it contains a solvent, , flammable or toxic hazards. Dry developers, on the other hand, do not contain any solvent, so there is no such danger, but since the toner is simply dispersed in the carrier as a powder, the toner does not have self-fixing properties. Therefore, in the case of a dry developer, whether the toner image is transferred to plain paper as in the Xerox method, or the toner image is left on the photosensitive paper without any transfer as in the electrofax method, After development, some kind of energy is applied from the outside to fix the toner on these substrates.
It must be a permanent image. For this reason, conventionally, a heat fixing method, a solvent fixing method, or a pressure fixing method is generally employed as a method for fixing a dry toner image. Among these methods, the heat fixing method is a method in which the toner resin is heated to a temperature above its softening point using a heater to soften it and basically fix the toner, and is currently the most widely used method because it provides strong fixing power. However, in order to soften the toner, a large amount of electric power is required even if various heating parts are devised, and it is also necessary to preheat the fixing part of the copying machine. In order to eliminate these drawbacks, it is conceivable to use a toner with a low softening point, but lowering the softening point of the toner causes disadvantages such as the toner coagulating and solidifying during storage. On the other hand, the solvent fixing method utilizes the ability of the solvent to dissolve the toner, so it does not require electricity and is more advantageous than the spot heat fixing method. This is not desirable as a toner fixing method. On the other hand, the pressure fixing method is a method that has been adopted in recent years to improve the shortcomings of these fixing methods. It pressurizes dry toner (using electricity) and takes advantage of the plastic deformation of the toner resin and a certain degree of penetration into the substrate. Although it does not require much electric power during pressurization, it takes 1000 kg/kg to fix the toner.
It requires a high pressure comparable to that of a B4 plate, and has disadvantages such as making the device heavier and larger. Therefore, various pressure fixing toners have been proposed in order to reduce the pressure during fixing. Among these, microcapsule toners are known, which have a core of a self-fixing ink composition such as a printing ink, and are surrounded by an outer wall of a polymeric substance such as gelatin. Although the intended purpose can be achieved by using such toner, a decrease in fixing power is unavoidable because the toner has wall substances that do not originally contribute to fixing. SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a heat-sublimable dry microcapsule toner and a method for fixing images formed with this toner, which improve the above-mentioned drawbacks.
This purpose is to create a heat-sublimable microcapsule toner that has a core of a self-fixing ink composition containing a resin and/or a colorant as its main component, and a heat-sublimable microcapsule toner that is surrounded by an outer wall containing a heat-sublimable polymer as a main component, and a toner made from this toner. Thermal sublimation is characterized by heating the image above the sublimation temperature of the thermosublimable polymer to sublimate the polymer on the outer wall of the toner and release the self-fixing ink composition of the toner core, thereby obtaining a permanent image. This is accomplished by a method of fixing a transparent microcapsule toner image. The heat-sublimable polymer used for the wall material of the toner of the present invention is obtained by direct polymerization of carbon dioxide gas and an epoxy compound, and is a type of polycarbonate.

Epoxy compounds that polymerize with carbon dioxide gas include ethylene oxide, propylene 6 oxide, cyclohexene oxide, styrene oxide, epichlorohydrin, etc. Typical heat-sublimable polymers made by polymerizing these compounds include polyethylene carbonate, polypropylene carbonate, and polystyrene carbonate. etc. These heat-sublimable polymers are commercially available, and their manufacturing method is described, for example, in a research report by Mr. Inoue (Faculty of Engineering, University of Tokyo) at the 23rd Annual Conference of the Society of Polymer Science and Technology (1971) (collection of lecture abstracts). reference). In order to form the wall material of the microcapsule toner of the present invention, the above-mentioned heat sublimable polymer may be used alone, or the polymer may be used as a main component, and polystyrene, polyacrylic acid ester, polyvinyl acetate may be used. It is also possible to mix resins conventionally used as binder resins for electrophotographic toners, such as polyvinyl chloride and polyvinyl chloride, to form the wall material. Self-fixing ink compositions used as the core material of toners are those in which resins and/or colorants are dispersed or dissolved in water or organic solvents, such as printing inks commonly used in offset printing, Water-based inks, electrophotographic wet developers, etc. can be used as is.

That is, water-soluble resins include gelatin, gum arabic, hydroxymethyl cellulose, ethyl cellulose, sodium alginate, pectin, etc. Polystyrene or lipophilic resins include polyacrylic acid ester, polystyrene acrylonitrile, polystyrene butadiene, polybutadiene, and polyvinyl chloride. , polyethylene, polypropylene, etc. In addition, colorants include inorganic pigments such as carbon black, red iron, molybdenum red, lead circle, iron oxide powder, barium yellow, manganese green, zinc green, ultramarine, cobalt blue, zinc oxide, lithopone, pallite, etc., and Permanetlet 4R1. Organic pigments such as azo pigments such as Hansaero 1 G, Benzene Ero 1 G, phthalocyanine pigments such as Phthalocyanine Blue B1 Phthalocyanine Green, and Fast Sky Blue 1 are used.

Note that the concentration of the resin and/or colorant in the composition is not particularly limited. In addition to the above-mentioned constituent materials, it is possible to mix magnetic powder for a toner for one-component mag development into the microcapsule toner of the present invention and use it as a toner for one-component mag development; is easily understood.

The method for producing the heat-sublimable microcapsule toner of the present invention includes the coacervation method, submerged drying method, orifice method, which are conventionally known methods for producing ordinary microcapsules.
Any method such as the spray drying method may be used.

When carrying out the method of the present invention, a toner image is formed on a substrate (photosensitive paper, plain paper, etc.) by a conventional electrophotographic method, electrostatic recording method, or the like.

The fixing method of the present invention is far more effective than general heat fixing methods that involve melting a resin because fixing is carried out by dissolving the self-fixing ink composition in the capsule onto the support by sublimation of a heat-sublimable polymer. It requires less electricity.

That is, in the conventional melting type fixing method, in order to fix a toner having a softening point of 100° C., it is necessary to leave the toner in an atmosphere at 250° C. for at least 2 seconds. This is because this fixing method melts the toner and softens it sufficiently.
This is because the adhesive force with the molten toner cannot be increased unless the support is also heated. On the other hand, when using the toner of the present invention, fixing occurs when the contents of the capsule are dissolved onto the support. Sufficient fixing can be achieved by leaving the toner in the interior for about 0.5 seconds, so when fixing at the same speed, the power consumption is significantly reduced compared to conventional heat fixing methods. The present invention will be explained in more detail with reference to Examples below. Note that parts and % represent parts by weight and % by weight, respectively. Example 1 20 parts of polyethylene carbonate (manufactured by Nihon Oinoreshinore Co., Ltd., sublimation temperature 10°C) was dissolved in 380 parts of a fusion solvent of benzene:carbon tetrachloride = 1:1 (weight ratio).
% polymer solution was prepared.

Apart from this, 5 parts of carbon black, 2 parts of gum arabic
0 parts, 10 parts of ethylene glycol, and 65 parts of water were placed in a ball mill and dispersed for 24 hours to prepare a water-based ink.To 100 parts of this water-based ink, 1 part of sorbitan monooleate (SO-10 manufactured by Nitsuko Chemical Co., Ltd.) was added as an emulsifier. mix,
This was added to the polymer solution and emulsified and dispersed using a homomixer. The particle size of the resulting self-fixing ink composition droplets was about 10 microns. This dispersion was diluted by adding 400 parts of benzene, and while stirring, petroleum ether (boiling point 6
C) was gradually added to 5-110 to phase-separate the polyethylene carbonate in the polymer solution. In this way, a concentrated solution of polyethylene carbonate was precipitated around the droplets of the ink composition to prepare microcapsules. Next, the system is cooled to below 15°C and separated into a precipitate and a supernatant liquid,
After the supernatant liquid is removed by decanting, petroleum ether is added to the precipitate, i.e., capsules, for washing. After washing the capsules, they were filtered and dried to take out the capsules as a powder, thus obtaining a black microcapsule toner. Particle size is 1
It was 0 to 20μ. Next, 5 parts of this toner was mixed with 100 parts of iron powder (carrier) to prepare a dry developer, and when the electrostatic latent image formed on the Se photosensitive plate was developed, a good positive image was obtained. Furthermore, this toner image was transferred onto plain paper and heated at scale 7 using an offset user made by Rikoichi (equivalent to being left in an atmosphere of 250°C for 0.5 seconds).
When fixing was carried out, the polyethylene carbonate on the outer wall of the toner sublimated and the ink included therein oozed out, forming a permanent image firmly fixed on the plain paper. For comparison, a developer for PPC-900 (plain paper copying machine) manufactured by Rikoichi (a heat-fixable toner containing carbon black as a main component and a resin with a softening point of about 100°C - a mixture of iron powder) was used as a developer. Developing, transferring and fixing were carried out in the same manner, but the toner image was not fixed at all.

Example 2 0.2 parts of the same emulsifier as in Example 1 was added to a solution of 20 parts of polypropylene carbonate (manufactured by Nihon Oinole Seal Kogyo Co., Ltd., sublimation temperature 120°C) dissolved in 100 parts of methylene chloride.
20% plus 5% amino black
50 parts of a gum arabic aqueous solution was added and emulsified and dispersed using a homomixer to prepare a W/O type first dispersion.

Next, the first dispersion was added to 800 parts of a 1% gelatin aqueous solution at pH 6 and at a temperature of 30° C. with stirring, followed by vigorous stirring to prepare a [W/0]/W type second dispersion. This second dispersion was gradually heated until the temperature reached 40°C, and then
When stirring was continued for a period of time, methylene chloride evaporated, and polypropylene carbonate capsules encapsulating the ink were formed in the gelatin aqueous solution. The capsules were washed in the same manner as in Example 1, filtered, dried, and taken out as a powder. The particle size of the obtained black microcapsule toner was 10 to 20 μm. Next, 5 parts of this toner was mixed with 100 parts of iron powder carrier to make a dry developer, and development, transfer and fixing were carried out in the same manner as in Example 1. A fixed permanent image was obtained.

For comparison, the same method was used except that Rikoichi's developer for PPC-900 (thermal fixing toner containing iron powder as main components and resin with a softening point of about 120°C) was used as the developer. Although development, transfer, and fixing were performed, no fixing was achieved.

Claims (1)

[Scope of Claims] 1. A thermosublimable micro ink composition comprising a core of a self-fixing ink composition containing a resin and/or a colorant as a main component, and surrounding the core with an outer wall containing a thermosublimable polymer as a main component. capsule toner. 2. An image made of a heat-sublimable microcapsule toner in which the core of a self-fixing ink composition containing a resin and/or a colorant as a main component is covered with an outer wall containing a heat-sublimable polymer as a main component is formed using a heat-sublimable polymer. A thermosublimable microcapsule toner image characterized by heating above the sublimation temperature of the toner to sublimate the thermosublimable polymer on the outer wall of the toner and release the self-fixing ink composition of the toner core, thereby obtaining a permanent image. Fixation method.