JP2005202299A - Toner for electrostatic latent image development - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a capsule toner that has excellent low-temperature fixability, offset resistance, and blocking resistance, can suppress filming on a developing roller and a photoreceptor, and can stably form a clear image many times. provide.
In a capsule toner mainly composed of a colorant and a binder resin, the capsule wall has M (volume%) of a powder substance having a thermal conductivity of Y (W / mK) at 300 K with respect to the capsule wall. A toner for developing an electrostatic latent image, which contains and satisfies the following formula when the thickness of the capsule wall is r (nm).
(R / 100) ² <M * logY <60 (1)
[Selection] Figure 1

Description

  The present invention relates to a toner for developing an electrostatic latent image formed on an image carrier by an electrophotographic process or an ion flow method.

  An image forming apparatus using an electrophotographic method such as a laser printer, an LED (Light Emitting Diode) printer, or a digital copying machine uniformly charges the surface of a photosensitive member, and irradiates the image information with a laser beam, an LED, or the like. Then, a desired electrostatic latent image is formed, and the developing unit visualizes the electrostatic latent image with toner (developer) to form a visible image, which is fixed to a recording material to obtain an image. .

  In recent years, there has been a strict demand for downsizing and speeding up of image forming apparatuses using these electrophotographic systems.

  As for the downsizing of the image forming apparatus, since a space cannot be provided between the apparatus and the members, a toner hopper and a cleaner have to be arranged around the heat source of the fixing apparatus and the exposure system. However, when a toner hopper or a cleaner is provided around the heat source, the toner is always exposed to a high temperature atmosphere, and the toner may be fused to cause blocking.

  In addition, there has been a strong demand for speeding up the number of copies and speeding up the number of printed sheets as the image forming apparatus becomes more complex and personal computers are networked. Such high-speed copying machines and high-speed printers need to be fixed for a short time. In order to meet the demands from the image forming apparatus in designing the toner, it is sufficient to lower the glass transition temperature of the toner. However, if the glass transition temperature is lowered, blocking occurs during storage of the toner, resulting in agglomeration. Aggregates and becomes a toner with poor storage stability.

  However, it is difficult to provide a toner having both characteristics because the anti-blocking property and the low-temperature fixing property are contradictory properties such that the low-temperature fixing property deteriorates when the blocking resistance is improved.

  In view of the above background, there has been proposed a technique for achieving low-temperature fixability by using a capsule toner composed of a core substance and a capsule wall provided so as to cover the surface of the core substance as the toner.

  This type of capsule toner uses a low melting point compound or a material having a low Tg as a core material in order to improve the meltability at low temperature. For example, a technology for forming a core material with wax (patent) Document 1), a technique in which the core material is composed of polyester crosslinked with a polyvalent metal compound (see Patent Document 2), a technique in which the core material is composed of low-melting polyester (see Patent Document 3), and the like are disclosed. .

  However, in the above technique, charging stability and storage stability are considerably poor and practicality is extremely low.

  Further, in order to improve fluidity, blocking resistance is achieved by using a capsule toner composed of a core substance as a toner and an outer shell provided so as to cover the surface of the core substance with inorganic fine particles. A technique has been proposed (Patent Document 4). Furthermore, a technique for encapsulating metal fine particles with an insulating resin has been proposed (Patent Document 5).

  However, in the above technique, the correlation between the thickness of the capsule wall, the thermal conductivity of the inorganic fine particles or metal fine particles contained in the capsule wall, and the volume% with respect to the capsule wall is not shown. Since it is inferior and it is difficult to suppress filming on the developing roller and the photoreceptor, the practicality is extremely low.

  As described above, it is the actual situation that no sufficiently satisfactory capsule toner has been obtained.

Japanese Patent Publication No.49-1588 JP 58-174957 A JP 58-176642 A Japanese Patent Laid-Open No. 1-9467 JP 2002-231053 A JP-A-10-133417

  The present invention has been made based on the circumstances as described above, and its purpose is excellent in low-temperature fixability, offset resistance, and blocking resistance, and suppresses filming on the developing roller and the photoreceptor. Another object of the present invention is to provide a capsule toner that can stably form a clear image many times.

  The present inventor has found that the above problems can be solved by incorporating powder particles having an optimum relationship between the thermal conductivity and the volume% with respect to the capsule wall with respect to an arbitrary capsule wall, and have reached the present invention.

That is, the present invention is an invention of a toner for developing an electrostatic latent image. In a core material that is a capsule toner mainly composed of a colorant and a binder resin, the capsule wall has a thermal conductivity of 300 K (Y / W / mK). ) Is contained (M% by volume) with respect to the capsule wall, and when the thickness of the capsule wall is r (nm), the following equation is satisfied.
(R / 100) ² <M * logY <60 (1)

  By containing powder particles that have an optimal relationship between the thermal conductivity and volume% of the capsule wall for any capsule wall, the stress applied to the toner by the toner regulating member can be moderately moderated, preventing filming. it can. In other words, when using fine particles with high thermal conductivity, the total amount of toner is within the range satisfying the above formula even if the volume% with respect to the capsule wall is reduced as compared with using fine particles with low thermal conductivity. As a result, the thermal conductivity is about the same.

When the diameter of the core substance is R (nm), the relationship with the capsule wall thickness r (nm) preferably satisfies the following formula.
(R / R) <0.10 (2)

  According to the present invention, it is possible to provide a capsule toner having excellent offset resistance, speeding up fixing with a low heat quantity, speeding up, adapting to energy saving, and excellent blocking resistance.

  The core material component preferably contains 30% by weight or more of a polyester resin. A polyester resin generally can be fixed at low temperature while maintaining heat-resistant storage as compared with other resins, and therefore it is possible to provide a toner that can be fixed at low temperature while maintaining heat-resistant storage.

  The capsule wall is preferably a polyester resin. By using a polyester resin for the capsule wall, it is possible to provide a toner for developing an electrostatic image that maintains transparency.

  The toner for an electrostatic latent image developer of the present invention is preferably obtained by an emulsification dispersion method in a non-aqueous medium. By adopting the emulsification dispersion method in non-aqueous media, there is no hydrophilic functional group or hydrophilic substance on the surface, and it is possible to have stable charging characteristics against changes in humidity, so high quality An image is obtained.

  By containing powder particles that have an optimal relationship between the thermal conductivity and volume% of the capsule wall for any capsule wall, the stress applied to the toner by the toner regulating member can be moderately moderated, preventing filming. it can. In other words, when using fine particles with high thermal conductivity, the total amount of toner is within the range satisfying the above formula even if the volume% with respect to the capsule wall is reduced as compared with using fine particles with low thermal conductivity. As a result, the thermal conductivity is about the same.

  Capsule toners that are excellent in offset resistance, can be quickly and quickly fixed with a low heat quantity, can be adapted to energy saving, and have excellent blocking resistance can be provided.

  A polyester resin generally can be fixed at low temperature while maintaining heat-resistant storage as compared with other resins, and therefore it is possible to provide a toner that can be fixed at low temperature while maintaining heat-resistant storage.

  By using a polyester resin for the capsule wall, it is possible to provide a toner for developing an electrostatic image that maintains transparency.

  Since there is no hydrophilic functional group or hydrophilic substance on the surface and it is possible to have stable charging characteristics against changes in humidity, a high-quality image can be obtained.

  In the toner production method according to the first embodiment of the present invention, the binder resin component and the colorant component as main components are emulsified and dispersed in a supercritical fluid or a subcritical fluid using an emulsifier. In this method, the pressure is rapidly reduced after a period of time so that the colorant component is dispersed in the inside of the binder resin component and is precipitated in the form of particles.

  If the temperature and pressure of a substance are set to a certain condition (critical point) or higher, the fluid in the density of the gas phase and the liquid phase becomes equal, and the fluid under temperature and pressure near the critical point is supercritical. It is called fluid. Moreover, even if it is less than a supercritical point, it will be in the state close | similar to a supercritical fluid also on the conditions near a critical point, and such a fluid is called a subcritical fluid.

  In supercritical fluids or subcritical fluids (in the following description of supercritical fluids, subcritical fluids are also included unless otherwise specified), both gas properties and liquid properties appear. For example, density is close to liquid (several hundred times that of gas), viscosity is close to gas (1/10 to 1/100 of liquid), diffusion coefficient is 1/10 to 1/100 of liquid, heat conduction The degree can be close to liquid (about 100 times that of gas).

  A supercritical fluid generally has a very large power for dissolving a substance, and has a property that can greatly change the dissolving power of a substance by changing temperature and pressure. This is very excellent as a reaction solvent or an extraction solvent, and has been actively studied in the field of separation, extraction and purification of substances in recent years. Examples include caffeine extraction from coffee and separation / extraction of waste.

  In addition, a desired substance is dissolved in the supercritical fluid and rapidly expanded (RESS method (Rapid Expansion of Supercritical Solution)), or a poor solvent or a surfactant is added to the supercritical fluid. The production of fine particles using the fact that the solubility of the solute is significantly reduced and the dissolved substance is precipitated by this action is also performed.

  As a method for producing fine particles using a supercritical fluid, there is a technique described in Patent Document 6, for example. This method only relates to a method for producing fine particles to be externally added to the toner, and does not describe any method for producing the toner itself.

  The present inventors paid attention to the above-mentioned properties relating to the supercritical fluid, and tried variously applying it to toner production.

  When the supercritical fluid in the reaction vessel is depressurized, for example, the emulsified and dispersed components are precipitated as fine particles. At this time, since the pigment is in a well dispersed state in the supercritical fluid, the toner in the form of fine particles can be obtained in a state where the colorant component is uniformly dispersed in the fine particles of the binder resin component.

Examples of substances that can be used as the supercritical fluid include CO ₂ , N ₂ , CH ₄ , C ₂ H ₆ , CF ₃ H, NH ₃ , CF ₃ Cl, CH ₃ OH, C ₂ H ₅ OH, and H. ₂ O etc. are mentioned.

  Examples of the colorant component include organic pigments and inorganic pigments, such as carbon black, aniline blue, calco oil blue, chrome yellow, methylene blue, dupont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, and rose. Bengal, disazo yellow, carmine 6B, quinacridone pigments and the like. The particle diameter (primary particles) of the pigment is 40 nm to 400 nm, preferably 100 nm to 200 nm.

  In addition to the binder resin components, colorant components, and emulsifiers that are mixed in the supercritical fluid, an additive aid (entrainer) is used to increase the affinity between the supercritical fluid or subcritical fluid and the solute. ) May be added.

  Depending on the combination of the substance of the supercritical fluid used and the solute to be mixed as the above-mentioned auxiliary additive, alcohols (methanol, ethanol, isopropanol, butanol, etc.) and ketones (methyl ethyl ketone, acetone, cyclohexanone, etc.) ), Ethers (diethyl ether, tetrahydrofuran, etc.), hydrocarbons (toluene, benzene, cyclohexane, etc.), esters (ethyl acetate, butyl acetate, methyl acetate, alkyl carboxylic acid esters, etc.), halogenated hydrocarbons (Chlorobenzene, dichloromethane, etc.), water, ammonia and the like. However, when water or ammonia is used as an auxiliary additive, water or ammonia is not used as a supercritical fluid or subcritical fluid.

  Hereinafter, the production of the toner of the present invention will be described with reference to the drawings. As a manufacturing apparatus for producing the toner of the present invention, for example, a configuration as shown in FIG. First, gas is supplied to the reaction vessel 7 from the gas cylinder 1 filled with a substance to be a supercritical fluid. This gas is raised to a desired pressure by the pressurizing pump 2. Similarly, the entrainer (addition aid) 3 is also raised to a desired pressure by the pressure pump 4. These high-pressure gas and entrainer 3 are sent to reaction vessel 7 through valves 5 and 6. At this time, although not shown, the temperature of the high-pressure gas may be adjusted to a desired temperature with a preheating coil or the like. Moreover, before introducing into the reaction vessel 7, the supercritical gas and the entrainer 3 are not shown, but may be mixed in a separate vessel in advance.

  In the reaction vessel 7, an emulsifier containing a binder resin component as a toner material, a colorant component, and a resin component constituting the capsule wall is sealed, and the reaction vessel 7 is, for example, a heater 9 or FIG. Although not shown, it is configured to have a desired temperature in a constant temperature water bath or the like. Further, the inside of the reaction vessel 7 is adjusted to a desired pressure by the valves 5 and 6. These temperature and pressure are monitored by a thermometer 8 and a pressure gauge 10.

  Thus, the supercritical fluid, the entrainer, the main component binder resin component, the colorant component, and the emulsifier containing the resin component constituting the capsule wall are mixed in the reaction vessel 7 in the supercritical state. It becomes. At this time, although not shown in the figure, the inside of the reaction vessel 7 may be stirred with a stirring device (for example, a propeller-like stirring device) as necessary.

  The connection mechanism from the reaction vessel 7 to the nozzle 14 and the nozzle 14 itself can adjust the temperature of the high-pressure gas to a desired temperature by a preheating coil or the like. Further, a thermometer can be installed in the vicinity of the outlet of the nozzle 14 to monitor it.

  By maintaining such a state and opening the pressure reducing valve 11 shown in FIG. 1, the supercritical fluid in the reaction vessel 7 rapidly expands and is depressurized. At this time, the respective solutes emulsified and dispersed in the supercritical fluid are precipitated in the form of fine particles in a mixed state.

  In this step, by appropriately setting the affinity between the colorant component and the binder resin component of the main component, the emulsifier, the entrainer and the supercritical fluid, and the pressure adjustment conditions of the reaction vessel 7, After the pressure reduction, toner fine particles can be obtained in which the colorant component is embedded in the binder resin component deposited in the form of fine particles in the reaction container 7 in a state of being dispersed almost uniformly. These toner fine particles have a volume average particle diameter of 3 μm to 7 μm.

  Hereinafter, although the present invention is explained based on each concrete example, the present invention is not limited to each following example.

(Production Example 1)
A toner production apparatus as shown in FIG. 1 is used for the production of the toner according to Production Example 1 of the present invention. The volume of the reaction vessel 7 is, for example, 1000 cm ³ . In this Production Example 1, carbon dioxide is used as the gas used as the supercritical fluid. As the entrainer, ethanol (which is a commercial product for general reagents) is used.

  When the binder resin component is 50 g and this is 100 parts by weight, 10 to 30 parts by weight of carbon black (manufactured by Mitsubishi Chemical Corporation, trade name: MA100) as a pigment, 3 parts by weight of a resin component as an emulsifier and fine particles 6 parts by weight are put in the reaction vessel 7 in advance. Note that the entrainer is incompatible with the binder resin component under normal temperature and normal pressure conditions.

  Carbon dioxide gas supplied from the gas cylinder 1 is pressurized by the pressurizing pump 2 and introduced into the reaction vessel 7 through the valve 6. 200 ml of ethanol as the entrainer 3 is also introduced into the reaction vessel 7 via the pressure pump 4.

  Here, the pressure reducing valve 11 for discharge remains closed, and the pressure in the reaction vessel 7 increases due to the introduction of high-pressure carbon dioxide. Further, the heaters 9, 12, and 13 adjust the reaction vessel 7, the ejection mechanism temperature, the connection mechanism temperature, and the temperature near the ejection mechanism outlet.

  When the pressure in the reaction vessel 7 is 7.3 MPa or more, the inside of the reaction vessel 7 is in a supercritical state. Moreover, the critical temperature of carbon dioxide is 304.6K, and if it sets temperature more than this, it will be in a supercritical state.

  For example, after maintaining this state for 20 minutes, the decompression valve 11 is opened and the mixed solution in the reaction vessel 7 is discharged from the nozzle 14 into the particle collection box 15. Toner fine particles containing the pigment dispersed almost uniformly are deposited in the reaction vessel 7.

  At this time, carbon dioxide as a supercritical fluid and ethanol as an entrainer contained in the mixed solution are separated into carbon dioxide and ethanol by a recovery mechanism (not shown) and reused.

  In Production Example 1, since an entrainer that is incompatible with the binder resin component is used under normal temperature and normal pressure conditions, a small amount of entrainer is attached to the surface of the obtained toner fine particles. However, coalescence between the toner fine particles (that is, bonding between each other) does not occur, and the toner fine particles can be obtained in a fine state.

  In addition, the toner fine particles were subjected to composition analysis in the depth direction using a TOF-SIMS (time-of-flight secondary ion mass spectrometer) “TRIFT-2000” manufactured by ULVAC-PHI Co., Ltd. The layer thickness r and the core material diameter R were measured.

(Example 1)
The binder resin component is a polyester resin (Dainippon Ink Co., Ltd., trade name: FZ-100): Acrylic resin (Sekisui Chemical Co., Ltd.) = 2: 8, and the resin component contained in the emulsifier is an acrylic resin. This was carried out in the same manner as in Production Example 1 except that 10 parts by weight (manufactured by Sekisui Chemical Co., Ltd.) and 20 parts by weight of silica (thermal conductivity at 300 k = 4.7 W / mK) were used. However, r = 750 (nm), R = 6030 (nm), (r / R) = 0.12, and M = 80.

(Comparative Example 1)
The binder resin component is a polyester resin (Dainippon Ink Co., Ltd., trade name: FZ-100): Acrylic resin (Sekisui Chemical Co., Ltd.) = 2: 8, and the resin component contained in the emulsifier is an acrylic resin. This was carried out in the same manner as in Production Example 1 except that 20 parts by weight (manufactured by Sekisui Chemical Co., Ltd.) and 10 parts by weight of silica (thermal conductivity at 300 K = 4.7 W / mK) were used. However, r = 740 (nm), R = 6100 (nm), (r / R) = 0.12, and M = 42.

(Comparative Example 2)
The binder resin component is a polyester resin (Dainippon Ink Co., Ltd., trade name: FZ-100): Acrylic resin (Sekisui Chemical Co., Ltd.) = 2: 8, and the resin component contained in the emulsifier is an acrylic resin. This was carried out in the same manner as in Production Example 1 except that 3 parts by weight (manufactured by Sekisui Chemical Co., Ltd.) and 27 parts by weight of silica (thermal conductivity at 300 K = 4.7 W / mK) were used. However, r = 755 (nm), R = 6100 (nm), (r / R) = 0.12, and M = 89.

(Comparative Example 3)
The binder resin component is a polyester resin (Dainippon Ink Co., Ltd., trade name: FZ-100): Acrylic resin (Sekisui Chemical Co., Ltd.) = 2: 8, and the resin component contained in the emulsifier is an acrylic resin. It was carried out in the same manner as in Production Example 1 except that 1 part by weight (manufactured by Sekisui Chemical Co., Ltd.) and 29 parts by weight of silica (thermal conductivity at 300 K = 5.3 W / mK) were used. However, r = 752 (nm), R = 6090 (nm), (r / R) = 0.12, and M = 97.

(Example 2)
The binder resin component is a polyester resin (Dainippon Ink Co., Ltd., trade name: FZ-100): Acrylic resin (Sekisui Chemical Co., Ltd.) = 2: 8, and the resin component contained in the emulsifier is an acrylic resin. It was carried out in the same manner as in Production Example 1 except that 25 parts by weight (manufactured by Sekisui Chemical Co., Ltd.) and 5 parts by weight of aluminum fine powder (thermal conductivity at 300 K = 237 W / mK) were used. However, r = 760 (nm), R = 6100 (nm), (r / R) = 0.12, and M = 24.

(Comparative Example 4)
The binder resin component is a polyester resin (Dainippon Ink Co., Ltd., trade name: FZ-100): Acrylic resin (Sekisui Chemical Co., Ltd.) = 2: 8, and the resin component contained in the emulsifier is an acrylic resin. This was carried out in the same manner as in Production Example 1 except that 3 parts by weight (manufactured by Sekisui Chemical Co., Ltd.) and 27 parts by weight of aluminum fine powder (thermal conductivity at 300 K = 237 W / mK) were used. However, r = 750 (nm), R = 6050 (nm), (r / R) = 0.12, and M = 90.

(Comparative Example 5)
The binder resin component is a polyester resin (Dainippon Ink Co., Ltd., trade name: FZ-100): Acrylic resin (Sekisui Chemical Co., Ltd.) = 2: 8, and the resin component contained in the emulsifier is an acrylic resin. This was carried out in the same manner as in Production Example 1 except that 29 parts by weight (manufactured by Sekisui Chemical Co., Ltd.) and 1 part by weight of aluminum fine powder (thermal conductivity at 300 K = 237 W / mK) were used. However, r = 760 (nm), R = 6070 (nm), (r / R) = 0.13, and M = 10.

(Example 3)
The binder resin component is a polyester resin (Dainippon Ink Co., Ltd., trade name: FZ-100): Acrylic resin (Sekisui Chemical Co., Ltd.) = 2: 8, and the resin component contained in the emulsifier is an acrylic resin. This was carried out in the same manner as in Production Example 1 except that 5 parts by weight (manufactured by Sekisui Chemical Co., Ltd.) and 10 parts by weight of silica (thermal conductivity at 300 K = 4.7 W / mK) were used. However, r = 310 (nm), R = 6100 (nm), (r / R) = 0.05, and M = 80.

(Comparative Example 6)
The binder resin component is a polyester resin (Dainippon Ink Co., Ltd., trade name: FZ-100): Acrylic resin (Sekisui Chemical Co., Ltd.) = 2: 8, and the resin component contained in the emulsifier is an acrylic resin. This was carried out in the same manner as in Production Example 1 except that 8 parts by weight (manufactured by Sekisui Chemical Co., Ltd.) and 22 parts by weight of silica (thermal conductivity at 300 K = 4.7 W / mK) were used. However, r = 610 (nm), R = 6100 (nm), (r / R) = 0.10, and M = 85.

Example 4
Example 3 except that the binder resin component in Example 3 is polyester resin (manufactured by Dainippon Ink Co., Ltd., trade name: FZ-100): acrylic resin (manufactured by Sekisui Chemical Co., Ltd.) = 4: 6. And performed in the same manner. However, r = 310 (nm), R = 6100 (nm), (r / R) = 0.05, and M = 80.

(Comparative Example 7)
Example 3 except that the binder resin component in Example 3 is polyester resin (manufactured by Dainippon Ink Co., Ltd., trade name: FZ-100): acrylic resin (manufactured by Sekisui Chemical Co., Ltd.) = 3: 7. And performed in the same manner. However, r = 310 (nm), R = 6100 (nm), (r / R) = 0.05, and M = 80.

(Example 5)
In Example 3, it carried out like Example 3 except having made only the polyester resin (Dainippon Ink Co., Ltd. make, brand name: ME-100) into the resin component contained in the said emulsifier. However, r = 310 (nm), R = 6100 (nm), (r / R) = 0.05, and M = 80.

(Example 6)
The entrainer was carried out in the same manner as in Example 3 except that a mixed solution of ethanol: water = 50: 50 was used. However, r = 310 (nm), R = 6100 (nm), (r / R) = 0.05, and M = 80.

[Performance evaluation]
A ferrite carrier having an average particle size of 80 μm was blended with 100 parts by mass of each of the toners prepared in Examples 1 to 6 and Comparative Examples 1 to 7 to prepare a two-component developer having a toner concentration of 4%.

For filming, the obtained developer was continuously copied 10,000 sheets by an electrophotographic copying machine (model number AR-450M Sharp), and then a halftone image was formed and the surface of the photoreceptor was observed. Evaluation was performed as follows.
○: Disturbed image, no toner component adhering to the photosensitive break Δ: Slightly cloudy is observed on a part of the photoreceptor surface, but no problem on the image ×: The photoreceptor surface is clouded, and the image is disturbed

For low-temperature fixability, the temperature of the fixing roller is controlled between 100 and 240 ° C., and the image fixed through the fixing machine is placed on a Gakushin type fastness tester (loading 1 kg on sand eraser), The optical reflection density was measured with a Macbeth reflection densitometer before and after rubbing three times, and the fixing property was evaluated at the fixing roller temperature when the fixing rate according to the following definition exceeded 70%.
Fixing rate (%) = [(Image density after rubbing) / (Image density before rubbing)] × 100
○: 90% or more Δ: 70-90%
×: 70% or less

With respect to storage stability, toner cartridge replenishment property: the toner cartridge A is filled with a toner weight of 9.9 g / cm ² per unit area, and the toner cartridge B has a toner weight per unit area of 4.8 g / cm ^2. Each toner was charged in a filled state of cm ² and left for 2 days in a high-temperature and high-humidity environment (35 ° C., 85%), and then the replenishability to the toner hopper of the Sharp digital copying machine AR450M was evaluated.
○: Full amount of toner can be replenished smoothly Δ: About half of the toner remains in the toner cartridge ×: Almost toner remains and overflows

About transparency (haze degree), the haze value defined below was measured using the haze meter (TC-HIII type; Tokyo Denshoku Co., Ltd. product) based on Japanese Industrial Standard K7105.
Haze degree (%) = (diffuse transmitted light amount / total transmitted light amount) × 100
○: Less than 25% △: 25% to 30%
×: 30% or more

Regarding the hot offset occurrence temperature, in accordance with the measurement of the minimum fixing temperature, the toner image is transferred and fixed by the fixing roller described above, and then the white transfer paper is sent to the fixing roller under the same conditions. The operation of visually observing whether or not toner contamination occurs is repeated while the set temperature of the fixing roller is sequentially increased, and the lowest set temperature at which toner contamination occurs is determined as the hot offset occurrence temperature.
○: 210 ° C. or higher Δ: 190 ° C. or higher and lower than 210 ° C. ×: less than 190 ° C.

For blocking resistance, 10 g of toner was placed in a 100 ml glass bottle, left in a thermostatic bath at a temperature of 50 ° C. for 2 days, and evaluated according to the following criteria.
○: No blocking Δ: Soft caking state ×: Hard caking

Regarding the charging stability, the obtained developer was continuously copied by using an electrophotographic copying machine (model number AR-450M Sharp Corporation) and 10,000 originals having an original density of 6% were continuously copied, and then 50 mm × 50 mm. The solid image was printed out, and the developer after the initial and 10,000 continuous copies were sampled from the developing device of the electrophotographic copying machine, and the charge amount was measured by the blow-off method. Further, the charging stability is the rate of change of the charge amount at the initial stage and after continuous copying of 10,000 sheets.
○ The charge amount of the 10,000th sheet is 100 to 80% of the initial charge amount
Δ: The charge amount of the 10,000th sheet is 80 to 60% of the initial charge amount.
×: The charge amount of the 10,000th sheet is 60% or less of the initial charge amount

  Table 1 shows the relationship between each example and comparative example and image quality.

  As shown in Table 1, Example 6 was particularly good in all items.

FIG. 1 is a schematic diagram of a toner production apparatus used for producing the toner of the present invention.

Explanation of symbols

1: gas cylinder, 2: pressurization pump, 3: entrainer, 4: pressurization pump, 5, 6: valve, 7: reaction vessel, 8: thermometer, 9, 12, 13: heater, 10: pressure gauge, 11: Pressure reducing valve, 14: Nozzle, 15: Particle collection box.

Claims (5)

In the core material which is a capsule toner mainly composed of a colorant and a binder resin, the capsule wall is composed of a powder material having a thermal conductivity at 300 K of Y (W / mK) with respect to the capsule wall M (volume%). A toner for developing an electrostatic latent image, wherein the toner satisfies the following formula when the thickness of the capsule wall is r (nm):
(R / 100) ² <M * logY <60 (1) 2. The electrostatic latent image developing according to claim 1, wherein when the diameter of the core material is R (nm), the relationship with the thickness r (nm) of the capsule wall satisfies the following formula. toner.
(R / R) <0.10 (2)   The toner for an electrostatic latent image developer according to claim 1, comprising 30% by weight or more of a polyester resin as the core substance component.   4. The electrostatic latent image developer toner according to claim 1, wherein the capsule wall is made of a polyester resin.   The toner for an electrostatic latent image developer according to claim 1, which is obtained by an emulsification dispersion method in a non-aqueous medium.

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