JP2014035462A - Toner and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner capable of sufficient plastic deformation even at low pressure in a non-heating or low-temperature condition, and an image forming apparatus using the toner.SOLUTION: A toner contains a binder resin 4, and a soft material 5 comprising at least one of wax and an elastic material; the soft material 5 is dispersed in the binder resin 4 in a particulate shape, and has the average inter-particle distance of 330 nm or less that is defined as the average value of the closest inter-particle distances D between particles of the soft material 5.

Description

  The present invention relates to a toner and an image forming apparatus used in an electrophotographic image forming apparatus such as a copying machine, a printer, and a facsimile machine.

  An electrophotographic image forming apparatus (for example, a printer) includes a fixing device that fixes a toner image formed on a recording member (recording paper or paper) onto the paper by heat melting. As an example of this fixing device, as disclosed in Patent Document 1, a roller-pair type fixing device including a fixing roller and a pressure roller is known.

  The fixing roller is a roller member in which an elastic layer is formed on the surface of a hollow metal core made of metal such as aluminum, and a halogen lamp is arranged as a heat source inside the core metal. Then, the temperature control device controls the temperature of the fixing roller surface by controlling the halogen lamp on / off based on a signal output from a temperature sensor provided on the surface of the fixing roller.

  The pressure roller is a roller member in which a heat-resistant elastic layer such as silicon rubber is provided as a coating layer on a cored bar. The pressure roller is pressed against the peripheral surface of the fixing roller, and a nip region is formed between the fixing roller and the pressure roller by elastic deformation of the elastic layer of the pressure roller.

  In the above configuration, the fixing device sandwiches the paper on which the unfixed toner image is formed in the nip region between the fixing roller and the pressure roller, and conveys the paper by rotating both the rollers, The toner image on the sheet is melted and fixed on the sheet by the heat of the peripheral surface of the fixing roller.

  However, in the conventional roller pair system, immediately after the power is turned on in the morning, the fixing roller and the pressure roller are at room temperature. Further, in the atmospheric state where the copying operation is not performed, the roller surface needs to be maintained at a predetermined temperature. Therefore, the heating must always be performed even when the copying operation is not performed. In addition to these copying operations, useless energy is consumed.

  In order to solve such a problem, Patent Document 2 discloses a toner having a high-density oxidized polyethylene as a core material and an outer shell made of an electrically insulating resin.

Japanese Patent Laid-Open No. 11-38802 Japanese Patent Publication No. 60-27977

  However, in the toner described in Patent Document 2, polyethylene wax has a relatively high strain softening property among polymer materials and is suitable for pressure fixing, but there is a limit to simply encapsulating it. For this reason, it is impossible to achieve the goal of obtaining sufficient fixability even at a low load while maintaining storability.

  Therefore, in order to solve the above problems, the present invention provides a toner that is sufficiently plastically deformable even at a low pressure and has excellent storage stability when performing fixing mainly under pressure under non-heating or low-temperature conditions. An object of the present invention is to provide an image forming apparatus using this toner.

  In order to solve the above problems, the toner according to the present invention contains a binder resin and a soft material composed of at least one of wax and elastic material, and the soft material is contained in the binder resin. The average interparticle distance, which is dispersed in the form of particles and defined as the average value of the closest interparticle distances between the soft material particles (hereinafter abbreviated as interparticle distance), is 330 nm or less.

  According to the above configuration, by setting the average interparticle distance to 330 nm or less, the toner can be plastically deformed entirely even at a low pressure, and good storage stability can be obtained. That is, when stress is applied to a single toner particle, the stress is transmitted through the particle without resistance, and the toner particle is destroyed. However, if a soft material such as wax is present in a state of being dispersed in the binder resin in a particulate state, the soft material is deformed by receiving stress, so that the stress is dispersed around the soft material. In particular, when the average interparticle distance of the soft material is 330 nm or less, the dispersion of the stress becomes continuous, and the entire particle is uniformly plastically deformed with respect to a predetermined stress. Thereby, a toner excellent in fixing property can be provided.

  As the soft material, a wax or an elastic material can be used alone. It is also possible to use a wax and an elastic material in combination. In this case, the wax particles and the elastic material particles are dispersed in the binder resin in a mixed state. Therefore, the interparticle distance is the closest interparticle distance regardless of the types of wax particles and elastic material particles.

  The average interparticle distance is preferably 80 nm or more. If the average interparticle distance is less than 80 nm, the effect of dispersing the stress may be reduced when the average particle radius of the soft material particles dispersed in the binder resin becomes too small and stress is applied.

  The soft material preferably has a small degree of variation in the interparticle distance. Specifically, it is preferable that the degree of variation in the interparticle distance defined as a value obtained by dividing the standard deviation of the interparticle distance of the soft material by the average interparticle distance is 31 or less. When the degree of variation in the interparticle distance increases, the stress distribution intended by the present invention may not be continuous, and a portion that does not undergo plastic deformation may occur.

  The blending amount of the soft material is preferably 12% by weight to 30% by weight with respect to the whole toner. When the amount is less than 12% by weight, the whole toner is hardly plastically deformed. This may adversely affect the storability and pigments.

  When at least a wax is used as the soft material, the wax preferably has a weight average molecular weight of 2000 or less, more preferably 1000 or less, as measured by gel permeation chromatography (GPC). When the molecular weight is reduced, the hardness of the toner can be lowered, and the toner can be fluidized entirely at a low pressure, so that excellent fixability can be exhibited. The wax is desirably solid in the toner use temperature range from the viewpoint of storage stability. For this purpose, the wax weight average molecular weight is preferably 500 or more.

  Furthermore, the shape of the wax is preferably substantially spherical when dispersed in the toner. Usually, when a large amount of a release agent is blended, the dispersion shape receives a force in the rotation direction of the kneader, so that it tends to be an elongated rod shape. In that case, when the toner is stressed, the function of stress dispersion by the release agent becomes insufficient. However, when the shape is substantially spherical, the stress concentration can be sufficiently diffused, and good fixability can be obtained. In order to make the dispersed particles substantially spherical, for example, the toner is gradually cooled (annealed) after discharging from the kneader, or heated and cooled after normal cooling.

  The toner having the above structure can be used as it is in a powdered state, and has a capsule structure in which the toner having the above structure is used as a core, and a resin having a higher hardness or crow transition point (Tg) than the core. Can also be used. As a result, it is possible to maintain storability and fixability satisfactorily.

  In the image forming apparatus using the toner described above, after the toner is placed on the recording member, the toner is fixed under a low linear pressure of 5 kgf / cm to 30 kgf / cm and under non-heating or low temperature conditions. It becomes possible. Further, the image forming apparatus using the toner described above can be controlled so that the fixing temperature becomes 80 ° C. or less after the toner is placed on the recording member. That is, fixing at a low temperature is possible. Therefore, power consumption can be suppressed, and further, the time from the start to the time when image formation becomes possible can be shortened.

  As described above, according to the present invention, the soft material is dispersed in the binder resin in the form of particles, and the average interparticle distance between the soft material particles is set to 330 nm or less. When fixing is performed, a toner that can be sufficiently plastically deformed even at a low pressure and has excellent storage stability can be obtained.

Schematic showing the main part of the image forming apparatus of the present invention Schematic diagram showing a state in which stress is applied to the toner of the present invention

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view showing a main part of the image forming apparatus of the present invention. The image forming apparatus includes a fixing device having a fixing roller 1 and a pressure roller 2. In the image forming apparatus of the present embodiment, the toner 3 is transferred between the fixing roller 1 and the pressure roller after the image of the toner 3 is transferred to the recording member P by an intermediate transfer belt (not shown). Three images are fixed on the recording member P.

  An unfixed toner image is, for example, a toner contained in a developer such as a non-magnetic one-component developer containing a non-magnetic toner, a non-magnetic two-component developer containing a non-magnetic toner and a carrier, and a magnetic developer containing a magnetic toner. Formed with.

  Next, the toner material will be described. The toner binder resin 4 is not particularly limited, and for example, a cyclic olefin resin can be used. This resin is preferable because it is nonpolar and can contain a large amount of a dispersant such as wax. The olefin resin used is described in detail in JP-A-2000-066438.

  The cyclic olefin resin as the binder resin will be described in detail. The resin is a lower alkene having 2 to 12 carbon atoms, preferably 2 to 6 carbon atoms, for example, α-olefins such as ethylene, propylene and butylene (in a broad sense, acyclic). Olefins) and cyclic and / or polycyclic compounds having 3 to 17, preferably 5 to 12 carbon atoms having at least one double bond such as norbornene, tetracyclododecene, dicyclopentadiene, cyclohexene, etc. A cyclic (cyclo) olefin), particularly preferably a copolymer with norbornene or tetracyclododecene, which is colorless and transparent and has a high light transmittance.

  Olefin-based polymers having this cyclic structure include, for example, metallocene-based catalysts, Ziegler-based catalysts, and metathese polymerizations, that is, heavy polymers using catalysts for double bond opening and ring-opening polymerization reactions. It is a polymer obtained by a legal method. Examples of the synthesis of the olefin polymer having this structure include JP-A-5-339327, JP-A-5-9223, JP-A-6-271628, European Patent Application Publication (A) No. 203799, No. 407870, No. 283164, No. 156464, JP-A-7-253315, and the like.

  According to these, one or more monomers of the above cyclic olefin are optionally combined with one of the above acyclic olefin-monomers and -78 to 150 ° C., preferably 20 to 80 ° C. and a pressure of 0.01 to 64 bar and an aluminoxane. It is obtained by polymerizing in the presence of a catalyst comprising at least one metallocene comprising, for example, zirconium or hafnium. Other useful polymers are described in European Patent Application (A) 317262, and hydrogenated polymers and copolymers of styrene and dicyclopentadiene can also be used.

  Since the metallocene catalyst is activated in a state where the metallocene catalyst is dissolved in the inert hydrocarbon of the aliphatic or aromatic hydrocarbon, for example, the metallocene catalyst is dissolved in toluene, and the preliminary activity and reaction are performed in a solvent. The important properties of an olefin polymer having a cyclic structure are softening point, melting point, viscosity, dielectric properties, non-offset temperature range and transparency. These can be advantageously adjusted by the choice of monomer / comonomer, ie intermonomer ratio in the copolymer, molecular weight, molecular weight distribution, hybrid polymer, blends and additives.

  In addition, the reaction charge molar ratio of the acyclic olefin and the cyclic olefin can be varied in a wide range depending on the olefin polymer having a target cyclic structure, preferably 50: 1 to 1:50, particularly preferably. Is adjusted from 20: 1 to 1:20.

  For example, when the copolymer component is charged with a total of two compounds, ethylene as an acyclic olefin and norbornene as a cyclic olefin, the glass transition point (Tg) of an olefin polymer having a cyclic structure as a reaction product. Is greatly affected by these charging ratios, and when the norbornene content is increased, Tg tends to increase. For example, when the content of norbornene is about 60% by weight, Tg is about 60 to 70 ° C. Physical properties such as number average molecular weight are adjusted as known from the literature.

  As the binder resin, in addition to the cyclic olefin resin, a polyester resin, a styrene acrylic resin, a polyamide resin, or the like may be used alone, or two or more kinds of resins may be mixed and used.

  The polyester resin is produced by condensation polymerization of a divalent or higher acid monomer and a divalent or higher alcohol monomer. Specifically, examples of the acid monomer include bifunctional acid monomers such as terephthalic acid, phthalic acid, fumaric acid, maleic acid, and succinic acid, or derivatives thereof. Examples of alcohol monomers include bifunctional alcohol monomers such as bisphenol A derivatives, ethylene glycol, and neopentyl glycol. Polyester resins having different glass transition points can be produced by combining these monomers.

  The styrene acrylic resin is produced by copolymerizing a styrene component and an acrylic component. Specifically, as the acrylic component, acrylic acid esters such as n-butyl acrylate and 2-ethylhexyl acrylate and methacrylic acid esters such as n-butyl methacrylate are used, and these acrylic components and styrene are combined. Thus, styrene acrylic resins having various glass transition points can be produced. The styrene acrylic resin used for the toner preferably has a glass transition point of 55 ° C to 70 ° C.

  Any colorant can be used, for example, carbon black, aniline black, acetylene black, naphthol yellow, hansa yellow, rhodamine lake, alizarin lake, bengara, phthalocyanine blue and indanthrene blue. One type of colorant may be used alone, or two or more types may be used in combination. The colorant is appropriately selected according to the color required for the toner.

  By containing a charge control agent, the charging characteristics of the toner can be controlled. Examples of the charge control agent include quaternary ammonium compounds, metal complexes of monoazo dyes, nitrohumic acid and its salts, metal complexes with metals such as salicylic acid, chromium or iron, and amino compounds. A material known as an organic dye can also be used as a charge control agent. One charge control agent may be used alone, or two or more charge control agents may be used in combination.

  As the soft material, at least one of a wax and an elastic material can be used, and a wax and an elastic material can be used in combination. Examples of the wax (release agent) include ester waxes containing fatty acid ester compounds as main components; aliphatic hydrocarbon waxes such as paraffin wax, polyolefin wax, Fischer-Tropsch wax, and microcrystalline wax; and low molecular weight polyurethanes. Various types such as polyurethane wax can be used.

  Ester waxes include natural waxes such as carnauba wax, candelilla wax, rice wax, and montan wax, as well as synthetic waxes such as methyl laurate, methyl myristate, methyl palmitate, methyl stearate, and butyl stearate. can do. One type of wax may be used alone, or two or more types may be used in combination.

  In addition to rubber materials such as natural rubber and synthetic rubber, an elastomer can be used as the elastic material. Specific examples of the rubber material include cyclic isoprene, styrene butadiene rubber (SBR), nitrile rubber (NR), butadiene rubber (BR), and isoprene rubber (IR). Particularly preferred is cyclic isoprene, which can be obtained by copolymerizing styrene and butadiene. The copolymerization ratio of styrene and butadiene is preferably 20:80 to 50:50, and the copolymerization ratio of styrene and butadiene is more preferably 30:70 to 50:50.

  Hard particles such as titanium oxide, calcium carbonate, silica, alumina, and clay may be blended in the toner. Of these, calcium carbonate is particularly suitable because of its excellent particle size, shape and dispersibility. The blending amount of the hard particles with respect to the whole toner is preferably 15% by weight to 30% by weight. If the blending amount of the hard particles is less than 15% by weight, the entire toner may not be affected. If the blending amount is more than 30% by weight, the elastic properties are lost and the fixability may be deteriorated. .

  By distributing hard particles in the toner, when a load is applied to the toner, the cyclic olefin resin slips at the interface between the cyclic olefin resin and the hard particles, and the cyclic olefin resin easily flows, so-called strain softening phenomenon occurs. . Therefore, it is preferable that the interface between the cyclic olefin resin and the hard particles is weak.

  The toner described above can be used after being granulated as it is, and a toner having a capsule structure in which the above-described toner particles are used as a core and a resin whose hardness or crow transition point (Tg) is higher than that of the core is used. It is also possible. Examples of the resin used for the shell include melamine-formaldehyde resin, polyester resin, and styrene acrylic resin in the shell portion.

  The resin for the shell is not limited to this, and a known resin used as a binder resin for the toner can be used as the resin. One of these resins may be used alone, or two or more thereof may be used in combination. Further, the method for producing the capsule is not particularly limited, and for example, a method of causing the shell resin particles to collide with the core particles with a high-speed air current, such as a hybridization system manufactured by Nara Machinery Co., Ltd., can be used.

  FIG. 2 is a schematic diagram showing a state in which stress is applied to the toner of the present invention. As illustrated, in the toner 3 according to the present invention, the soft material particles 5 are uniformly dispersed in the binder resin 4. When the external force F acts on the toner particles having such a configuration, the soft material particles 5 dispersed in the toner 3 particles are deformed to disperse / relax the external force F, and the toner 3 particles are plastically deformed without being destroyed. To do. At this time, since the soft material particles 5 are deformed, mechanical energy is converted into heat energy, and thus plastic deformation of the toner 3 particles is promoted. As a result, the toner of the present invention exhibits excellent fixability.

  Next, a method for manufacturing the toner 3 will be described. To prepare the toner by the pulverization method, a toner composition containing a binder resin, a colorant, a soft material and other additives is dry-mixed with a mixer and then melt-kneaded with a kneader. The kneaded product obtained by melt kneading is cooled and solidified, and the solidified product is pulverized by a pulverizer. Thereafter, particle size adjustment such as classification is performed as necessary to obtain a powdered toner.

  Known mixers can be used. For example, Henschel mixer (trade name, manufactured by Mitsui Mining Co., Ltd.), Super mixer (trade name, manufactured by Kawata Co., Ltd.), Mechano Mill (trade name, manufactured by Okada Seiko Co., Ltd.), An airflow mixer such as a hybridization system (trade name, manufactured by Nara Machinery Co., Ltd.) can be used.

  Next, it is necessary to knead a soft material such as wax in the binder resin by applying heat and pressure to the mixture by the above mixer, but in the present invention, the average interparticle distance of the soft material is 80 nm. Since it is ˜330 nm, it is necessary to further improve the dispersibility of the soft material. The method for this is not particularly specified if the average inter-particle distance of the soft material is 80 nm to 330 nm. For example, when a kneader is used, the rotational speed of the screw is preferably 500 rpm or more, preferably 2000 rpm or more.

  In general, when a dispersant is kneaded into a binder resin, it is known that the dispersed particle diameter of one dispersed particle becomes smaller as the number of rotations of the screw is larger. In this case, since a compatibilizer is unnecessary, there is an advantage that the storage stability of the toner is improved. Moreover, even in general kneaders such as conventional twin screw extruders, three rolls, and lab blast mills, the average interparticle distance is 80 nm by using a compatibilizing agent that is optimal for the binder resin and soft material particles. It is possible to achieve a dispersion state in the range of ˜330 nm.

  More specifically, for example, TEM-100B (trade name, manufactured by Toshiba Machine Co., Ltd.), PCM-65 / 87, PCM-30 (all of which are trade names, manufactured by Ikegai Co., Ltd.), etc. Extruder, Needex (trade name, manufactured by Mitsui Mining Co., Ltd.) and other open roll type kneaders. Among these, a twin screw extruder is preferable.

  In the present invention, the soft material is dispersed in the binder resin. However, when wax is used as the soft material, since the wax is easily plastically deformed, the toner composition is extruded as usual after kneading with a kneader. It solidifies by cooling in the stretched state. As a result, the shape of the wax particles in the toner becomes an elongated rod. On the other hand, when it is gradually cooled after being extruded from the kneader, the shape of the wax particles in the toner becomes substantially spherical.

  As the pulverizer, for example, a jet-type pulverizer that pulverizes using a supersonic jet stream or a solidified material is introduced into a space formed between a rotor (rotor) and a stator (liner) that rotate at high speed. And an impact type pulverizer for pulverization. For the classification, a known classifier capable of removing the excessively pulverized toner base particles by classification using centrifugal force and wind force can be used, and examples thereof include a swirl type wind classifier (rotary wind classifier).

  As described above, the toner to which an external additive is added as required can be used as a one-component developer without adding a carrier, or can be mixed with a carrier and used as a two-component developer. When used as a one-component developer, toner that has been frictionally charged with a developing sleeve using a blade and a fur brush is attached onto the sleeve, thereby conveying the toner and forming an image. When used as a two-component developer, the toner of the present invention is used with a carrier. Since the one-component developer and the two-component developer contain the toner capable of maintaining a stable charging performance in a high humidity environment, the two-component developer has high charging stability even in a high humidity environment.

  As the carrier, a known carrier can be used, for example, a resin-coated carrier in which iron or copper, zinc, nickel, cobalt, manganese, chromium or the like alone or a composite ferrite and carrier toner base particles are surface-coated with a coating substance, or Examples thereof include a resin-dispersed carrier in which magnetic particles are dispersed in a resin.

  Known coating materials can also be used, such as polytetrafluoroethylene, monochlorotrifluoroethylene polymer, polyvinylidene fluoride, silicon resin, polyester resin, metal compound of ditertiary butylsalicylic acid, styrene resin, acrylic resin, Examples include polyacid, polyvinyllar, nigrosine, aminoacrylate resin, basic dye, basic dye lake, silica fine powder, and alumina fine powder.

  By using the toner of the present invention described above in the image forming apparatus according to the present invention, the linear pressure between the fixing roller 1 and the pressure roller 2 is a low pressure of 5 kgf / cm to 30 kgf / cm and 25 without heating. It becomes possible to perform pressure fixing at a temperature as low as below. As a result, power consumption required for heating can be suppressed, and the time required to start up the main body switch from the image forming apparatus can be shortened. On the other hand, when the pressure between the fixing roller 1 and the pressure roller 2 is lower than the above range, the fixability may be insufficient. When the pressure is higher than the above range, the gloss becomes strong, and the fixing device also has a problem. Become a big deal.

  In this example, various toners were prepared, and the formed toner was used to actually form an image with an image forming apparatus, and the toner fixability and storage stability were evaluated.

[Production of toner]
A binder resin, a soft material, a pigment (carbon black) and a charge control agent (manufactured by Nippon Carlit Co., Ltd .: LR-147) are blended, and hard particles (calcium carbonate manufactured by Shiraishi Kogyo Co., Ltd., Brilliant-1500) are further added as necessary. The blended toner composition was mixed and then melt-kneaded by a kneader. In this example, the average interparticle distance and the degree of variation in the interparticle distance were variously changed by changing the rotational speed of the kneader around 3000 rpm. The kneaded product was cooled and solidified, and then the solidified product was pulverized by a pulverizer and the particle size was adjusted to obtain a toner.

  When manufacturing the toner having a capsule structure, the toner particles obtained by the above process were used as a core, and a polyester resin having a glass transition point of 60 ° C. was used as a shell material. The periphery of the core was covered with a shell material by a hybridization system manufactured by Nara Machinery Co., Ltd., and a capsule structure toner was obtained.

  As the binder resin, a cyclic olefin resin, a polyester resin, and a styrene acrylic resin were used. The cyclic olefin resin was obtained by using ethylene as the acyclic olefin and norbornene as the cyclic olefin, and reacting both as described above so that the norbornene content was 60% by weight. The polyester resin having a glass transition point of 60 ° C. was used. Further, a styrene acrylic resin having a glass transition point of 60 ° C. was used.

  As the soft material, wax and synthetic rubber were used. As the wax, WEP-2 manufactured by Nippon Oil & Fats Co., Ltd., which is an ester wax and a synthetic wax having a weight average molecular weight of 600, and carnauba wax, which is an ester wax and a natural wax, were used. In addition, Fischer-Tropsch wax (Sazol C80 manufactured by Sazol Wax) was used as the aliphatic hydrocarbon wax. As the synthetic rubber, cyclic polyisoprene and styrene butadiene were used.

  In addition, as the “fatty acid ester WEP-2”, two types of dispersed particles in the toner having a substantially spherical shape and an elongated rod shape were used. That is, after the toner composition containing WEP-2 is kneaded with a kneader, it is cooled as usual to form wax particles in the form of elongated rods, and by gradually slowly cooling after kneading, the wax particles are substantially spherical. Two types of toners were used. The influence of the shape of the wax was evaluated by using the wax particles of the same type and different in shape.

  Various combinations of the above raw materials were used for No. 1 to 27 toners were prepared and evaluated. Specific blending and evaluation results are shown in Table 1. In the table, the unit in the blending amount column means “% by weight”. The indication of “molecular weight” means “weight average molecular weight”.

[Evaluation test]
(1) Fixability test As shown in Table 1, image formation was performed with an image forming apparatus using each produced toner, and the fixability was evaluated. As the image forming apparatus, a fixing roller and a pressure roller are both made of an iron material having a diameter of 40 mm and having a hard chrome plating on the surface. Although no halogen lamp is arranged in the fixing roller, a heating means such as a halogen lamp may be provided in order to improve the fixing property.

  In that case, the fixing temperature is preferably 80 ° C. or less, and particularly preferably 65 ° C. or less. The lower the heating temperature, the less energy consumption. In particular, when a low molecular weight wax is used as the soft material, it is not good to control the fixing temperature at a temperature higher than 80 ° C. in order to prevent the occurrence of offset or the like, and it is preferable to control the fixing temperature to about 60 ° C. In this embodiment, a linear pressure of 10 kgf / cm is applied between the fixing roller and the pressure roller, the fixing temperature is 25 ° C., the maximum fixing speed is 225 mm / sec, and the maximum copying speed is 50 sheets / minute (A4 horizontal feed). .

  The toner is fixed to A4 test paper with black solid, lightly folded so that the black solid part of the fixed test paper is bent, and a fold line is rolled by rolling a cylindrical roller of 100 g in diameter 10 cm and height (width) 2 cm. After making, the crease of the recording paper was widened, and the toner that had fallen off the crease was wiped off with a clean waste cloth. Evaluation was made into five steps. Specific criteria are as shown below.

Evaluation Content 5 ... The width of the white part of the crease (the toner dropout part) is 0.1 mm or less 4 ... The width of the white part of the crease is 0.2 mm or less 3 ... The width of the white part of the crease is 0.3 mm or less 2 ... The crease The width of the white part is 0.4 mm or less 1... The width of the white part of the crease is 0.5 mm or less. As described above, the fixability has the highest evaluation in evaluation 5 and the evaluation in evaluation 1 has the lowest evaluation. -3 means that there is no practical problem, that is, an example level, and evaluations 2-1 mean that there is a practical problem, that is, a comparative example level.

(2) Preservability 20 g of toner is placed in a cylindrical aluminum container having a diameter of 3 cm and a height of 10 cm, left in a constant temperature bath at 60 ° C. for 5 hours, and then subjected to 400 mesh ultrasonic sieving to see if toner aggregates are generated. I investigated. Evaluation was made into five steps. Specific criteria are as shown below.

Evaluation Content 5 ... Mesh remaining rate is less than 2% 4 ... Mesh remaining rate is 2% or more and less than 5% 3 ... Mesh remaining rate is 5% or more and less than 10% 2 ... Mesh remaining rate is 10% or more and less than 20% 1 ... Mesh remaining ratio is 20% or more As described above, the fixability is rated 5 most highly, evaluation 1 is the least evaluated, and evaluations 5 to 3 are levels with no practical problems, that is, implementation. It means that it is an example level, and evaluations 2-1 mean that it is a practically problematic level, that is, a comparative example level.

(3) Observation of dispersed state of soft material particles Pellets with a particle size of several millimeters that can be collected during toner production were sliced to a thickness of 100 nm with an ultramicrotome (JEOL) and observed with TEM (manufactured by Hitachi, Ltd.). To do. If necessary, the dispersion state of the soft material can be easily observed by staining with osmium or the like. This makes it possible to calculate the average interparticle distance. As shown in FIG. 2, the interparticle distance D refers to a distance between a certain soft material 5 particle and another soft material 5 particle closest to the particle.

[Evaluation results]
From Table 1, although it is the same as a composition, it is No. from which the variation degree of the average interparticle distance and the interparticle distance of a soft material differs. 1-No. No. 9 having an average interparticle distance of 80 nm to 330 nm and a variation degree of interparticle distance of 31 or less. For 1, 2, 5, 8, 9, and 26, both the fixability and the storage stability were at a level with no problem in use.

  On the other hand, No. whose average interparticle distance is outside the range of 80 nm to 330 nm. 3, 4 and 6, and the variation degree of the interparticle distance is larger than 31. 7 indicates that the fixing property is at an insufficient level.

  On the other hand, if the average inter-particle distance of the soft material is 80 nm to 330 nm and the variation degree of the inter-particle distance is 31 or less, the blending amount of the soft material with respect to the whole toner is within a range of 12 wt% to 30 wt%. In addition, the storage stability was at a level with no problem in use (No. 10 to No. 12).

  As the soft material, a total of five types of waxes, WEP-2 having a weight average molecular weight of 600 and fatty acid esters having weight average molecular weights of 800, 980, 2000, and 5000, were used as synthetic waxes of ester wax. Furthermore, carnauba wax (No. 19), which is an ester-based natural wax, and Fischer-Tropsch wax (No. 20), which is an aliphatic hydrocarbon wax, were used. As a result, No. 1 using a wax having a weight average molecular weight of 1000 or less. Nos. 1, 19, 20 and 25 are No. 1 having a weight average molecular weight of more than 1000. It can be seen that the fixing property is excellent as compared with 14 and 15.

  In addition to wax, cyclic polyisoprene (No. 21) and styrene butadiene (No. 22), which are synthetic rubbers, were used as the soft material. Furthermore, no. In No. 27, fatty acid ester WEP-2 and styrene butadiene were used in combination. Both of these fixability and storability evaluations were good.

  Regarding the shape of the wax, No. 1 in which the shape of the wax particles in the toner is substantially spherical is superior to the No. 16 in which the shape of the wax particles is rod-like in terms of fixability. Further, No. 1 in which hard particles are blended in the toner. No. 22 is No. which does not contain hard particles. It has better fixability than 1. Furthermore, no. No. 1 having a capsule structure in which a composition having the same composition as that of No. 1 is used as a core and the periphery of the core is covered with a shell. 24, no. It is superior in storage stability to 1.

DESCRIPTION OF SYMBOLS 1 Fixing roller 2 Pressure roller 3 Toner 4 Binder resin 5 Soft material

Claims (9)

A binder resin and a soft material composed of at least one of wax and elastic material, wherein the soft material is dispersed in the binder resin in the form of particles, and between the soft particles close to each other A toner having an average interparticle distance defined as an average value of distances (hereinafter abbreviated as interparticle distance) of 330 nm or less. The toner according to claim 1, wherein the average interparticle distance is 80 nm or more. 3. The toner according to claim 1, wherein a degree of variation of the interparticle distance defined as a value obtained by dividing the standard deviation of the interparticle distance by the average interparticle distance is 31 or less. 4. The toner according to claim 1, wherein the amount of the soft material is 12% by weight to 30% by weight with respect to the whole toner. The toner according to claim 1, wherein at least a wax is used as the soft material, and a weight average molecular weight of the wax is 1000 or less. The toner according to claim 5, wherein the wax has a substantially spherical shape when dispersed in the toner. 6. A toner having a capsule structure in which the toner according to claim 1 is used as a core and a resin having a hardness or glass transition point higher than that of the core is used as a shell. An image forming apparatus, wherein the toner according to claim 1 is placed on a recording member and fixed at a pressure of 5 kgf / cm to 30 kgf / cm. An image forming apparatus, wherein the toner according to claim 1 is placed on a recording member, and the fixing temperature is controlled to be 80 ° C. or lower.

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