JP2006154244A - Toner for image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner for an image forming apparatus to obtain an image with high picture quality and high definition without inducing so-called scattering or fix trailing. <P>SOLUTION: The toner comprises a polymerization toner having a two-layer structure of a core portion using a first thermoplastic resin in the center and a shell portion using a second thermoplastic resin covering the outside of the core portion. The second thermoplastic resin constituting the shell portion comprises a material which is at least softened by a preheating means disposed in an upstream side of a thermal fixing means along a recording medium carrying belt which carries a recording medium with a toner image transferred thereon to a fixing device having the thermal fixing means. The first thermoplastic resin constituting the core portion comprises a material which is fused with the second thermoplastic resin in the thermal fixing means and fixed to the recording medium. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a toner for an image forming apparatus such as a copying machine, a printer, a facsimile, or a composite machine using an electrophotographic method, and in particular, due to thermal fixing, the toner is scattered and the image becomes jagged. The present invention relates to a toner for an image forming apparatus that prevents a phenomenon of roughening and a phenomenon that is caused by unfixed toner, which is called fixing tailing.

  In an image forming apparatus such as a copying machine, a printer, a facsimile, or a composite machine using an electrophotographic system, a latent image formed on a photosensitive member is developed into a toner image, and the toner image is recorded on paper or the like. An image is formed by transferring and fixing on a medium.

  Such image forming apparatuses are also required to have high-quality images and high-definition images as the technology advances, and polymerized toners having excellent image characteristics due to their shapes have been used. This polymerized toner has come to be used in black-and-white copiers, printers, and full-color image forming apparatuses due to advantages such as transferability, but on the other hand, if the image becomes high-quality or high-definition, it has been less noticeable in the past. The problems that did not exist are getting closer.

  One of these is called “scattering”, and the outline of the image or text is frayed by the scattered toner when it is fixed, and the other is called “fixing tailing”. This is a phenomenon in which the toner on the unfixed image fluctuates and the image is traced.

  Among these, “scattering” means that when toner is transferred more than necessary to an image or character portion by electrostatic attraction, and that portion is thermocompression-bonded on the recording material, the toner is scattered to the edge portion and fixed as it is. This phenomenon sometimes occurs, and the edge portion and the boundary portion of the image become jagged, and the image quality is deteriorated. “Fixing tailing” is a phenomenon in which the toner particles forming the toner image transferred onto the recording material by the water vapor generated from the recording material when the moisture-absorbing recording material passes through the trailing edge of the recording material. It is thought to be caused by scattering to the side.

  As a technique for preventing such “scattering” and “fixing tailing”, for example, Patent Document 1 discloses an average primary image in an image forming apparatus that heat-fixes a visible image on a recording material via a heat-resistant fixing thin film. At least one kind of inorganic fine particles 1 selected from oxides of titanium, aluminum, zinc and zirconium having a particle size of 80 nm to 800 nm, inorganic fine particles 2 having an average primary particle size other than silica of less than 80 nm, and an average primary particle size of 30 nm By using toner with at least externally added silica fine particles, the toner's electric resistance control effect is enhanced, the toner in the transfer area becomes evenly thin, and the generated water vapor is easily removed, and the formed visible image is heated. There is shown an image forming apparatus capable of preventing “scattering” and “fixing tailing” when fixing.

Similarly, Patent Document 2 includes melt additives MI having a melt viscosity MI of 3 to 40, and external additives A and B each containing different inorganic elements. There is shown a one-component toner for full color and an image forming method in which “scattering” and “fixing tailing” can be prevented by being 5 to 60%.
(Count number of synchronized three elements of toner-derived carbon, external additive A, and external additive B / total synchronous particle count) × 100 (%)

JP 2002-23416 A JP 2003-207930 A

  However, the methods disclosed in Patent Document 1 and Patent Document 2 relate to an image forming apparatus that heat-fixes a visible image on a recording material via a heat-resistant fixing thin film, and a fixing apparatus using a normal heater. Even if it is used as it is in an image forming apparatus, the effect is low, and the structure is complicated using a plurality of external additives.

  Therefore, in the present invention, a toner for an image forming apparatus capable of obtaining a high-quality and high-definition image that does not cause such “scattering” and “fixing tailing” even in a fixing device using a normal heater. It is a problem to provide.

In order to solve the above problems, the toner for an image forming apparatus according to the present invention comprises:
A toner for developing a latent image formed on a photoreceptor by electrophotography,
The toner is a polymerized toner having a two-layer structure including a core portion using a first thermoplastic resin in the center and a shell portion covering the outside of the core portion and using a second thermoplastic resin.
The second thermoplastic resin constituting the shell portion is a backup medium provided on the upstream side of the thermal fixing unit in the recording medium conveying belt for conveying the recording medium on which the toner image is transferred to a fixing device having a thermal fixing unit. Consists of a material that is at least softened by heating means,
The first thermoplastic resin constituting the core portion is made of a material that is melted together with the second thermoplastic resin by the thermal fixing unit and fixed to the recording medium.

  When the toner is configured in this way, the toner image transferred to the recording medium is softened by the preheating means before reaching the heat fixing means, and the phenomenon such as “scattering” and “fixing tailing” does not occur, and the image quality is high. Thus, it is possible to provide a toner for an image forming apparatus capable of obtaining a high-definition image.

When the glass transition temperature of the second thermoplastic resin constituting the shell portion is Tg1, and the glass transition temperature of the first thermoplastic resin constituting the core portion is Tg2,
50 ° C <Tg1 <80 ° C
50 ° C <Tg2 <80 ° C
In the preferred embodiment of the present invention, the toner is softened by the preheating means at approximately 80 ° C., and the fixing to the recording medium is performed in the range of 160 to 180 ° C. .

  As described above, the toner for an image forming apparatus according to the present invention is a polymer toner having a two-layer structure of a core part and a shell part covering the core part, and the image forming apparatus side uses a recording medium conveying belt to attach the recording medium. The preheating unit is provided on the upstream side of the fixing heater of the recording medium conveyance belt, and the toner shell is at least softened by the preheating unit. The toner particles do not adhere to each other when heated, and the toner does not scatter or flutter, and the above-mentioned phenomena such as “scattering” and “fixing tailing” do not occur, and a high-quality and high-definition image can be obtained. The toner for an image forming apparatus can be provided.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.

  FIG. 1 is a schematic configuration diagram of a fixing device in an image forming apparatus using the toner for an image forming apparatus according to the present invention, and FIG. 2 is a result of an experiment performed by changing the manufacturing method of the toner for the image forming apparatus according to the present invention. It is the table | surface which showed. In the figure, 1 is a fixing roller including a heat source in the fixing device, 2 is a pressure roller for pressing the recording medium to which the toner image is transferred, against the fixing roller, 3 is a conveyance belt for the recording medium, 4 is a driving roller, 5 Is a preheating unit that preheats the toner for the image forming apparatus of the present invention described below before fixing, and prevents "scattering", "fixing tailing", etc., and 6 is a recording on which the toner image is transferred It is a medium. Although FIG. 1 shows only the fixing device portion of the image forming apparatus, the image forming apparatus using the toner for the image forming apparatus of the present invention forms a toner image such as a photoconductor, a developing device, or a transfer device. Needless to say, a well-known electrophotographic apparatus for transferring to a recording medium is used.

  First, the toner for an image forming apparatus according to the present invention will be briefly described. The toner according to the present invention uses a polymerization method, and covers a core portion using a first thermoplastic resin at the center and the outside of the core portion. A two-layer structure including a shell portion using the second thermoplastic resin was formed. Then, a toner image is formed on the photosensitive member by using a known electrophotographic method and transferred to the recording medium 6. Then, the recording medium 6 is connected to the fixing roller 1 by the conveying belt 3 shown in FIG. It is conveyed to a fixing device comprising a pressure roller 2.

  The conveying belt 3 that conveys the recording medium 6 is provided with a preheating unit 5 in the middle of reaching the fixing device including the fixing roller 1 and the pressure roller 2 (that is, upstream of the fixing device). The toner is heated by the preliminary heating unit 5 before being fixed by being heated by the fixing roller 1 and the pressure roller 2, and the toner shell portion is at least softened so as not to be easily scattered, thereby preventing scattering. Thereafter, fixing by the fixing roller 1 and the pressure roller 2 is performed.

  Usually, the fixing process of the toner image on the recording medium 6 includes the following three processes. First, a process in which the toner is semi-fused and combined, a process in which the toner single particles or the combined toner are fluidized and spread, and a process in which the finally melted toner penetrates into the recording medium 3. Normally, these three processes are performed at a constant temperature for only several tens of milliseconds, but in the present invention, after the toner image is transferred onto the recording medium 6, preliminary heating is performed by the preliminary heating unit 5. At this point, a process in which the toner at the stage is half melted and coalesced is created. At this time, the temperature of the preheating unit 5 or the average molecular weight of the shell part and the amount of added wax are adjusted so that only the shell part is softened, and only the surface shell part of the toner is softened and combined. At this time, the water in the toner particles evaporates, but it does not occur suddenly and the air flow is not disturbed, so that neither tailing nor scattering occurs. If the two-layer structure of the core part and the shell part is not used, the resin or wax in the core part melts to some extent at this point, and high temperature offset tends to occur in the fixing between the fixing roller 1 and the pressure roller 2.

  In this way, the toner has a two-layer structure of a core portion and a shell portion covering the core portion, and the image forming apparatus side conveys the recording medium to the fixing device by the recording medium conveying belt, and the recording medium conveying belt By providing a preheating portion upstream of the fixing heater and making the toner shell portion soften at least in the preheating portion, toner particles adhere to each other due to heating of the preheating portion, and the toner scatters. It is possible to provide a toner for an image forming apparatus in which a phenomenon such as “scattering” and “fixing tailing” as described above does not occur and a high-quality and high-definition image can be obtained. .

The glass transition temperature of this toner is Tg1 when the glass transition temperature of the thermoplastic resin constituting the shell portion is Tg2 and the glass transition temperature of the thermoplastic resin constituting the core portion is Tg2.
50 ° C <Tg1 <80 ° C
50 ° C <Tg2 <80 ° C
The temperature of the fixing roller 1 and the preheating unit 5 in the fixing apparatus shown in FIG. 1 is 160 to 180 ° C. for the fixing roller 1 and about 80 ° C. for the preheating unit 5. preferable.

  This is because when Tg1 is 50 ° C. or lower, the storage stability of the toner is deteriorated and aggregation occurs in the toner cartridge, and when Tg1 is 80 ° C. or higher, softening does not occur during heating by the preheating unit 5. When fixing is performed by the fixing roller 1 and the pressure roller 2, tailing or scattering occurs, and the toner does not sufficiently melt in the end, so that a low temperature offset occurs or the toner penetrates into the paper. This causes a phenomenon that the toner is peeled off from the paper due to insufficient. When Tg2 is 50 ° C. or lower, the toner in the core melts when heated by the preheating unit 5 and expands and melts by passing through the shell, so that the toner particles are excessively fused and added to the fixing roller 1. This is because high-temperature offset is likely to occur during fixing with the pressure roller 2, and when Tg2 is 80 ° C. or higher, fixing by the fixing roller 1 and the pressure roller 2 is insufficient and low-temperature offset occurs. is there.

  In addition, this glass transition temperature Tg can be calculated | required from the change point of a specific heat using a differential scanning calorimeter (DSC). Specifically, a differential scanning calorimeter DSC-6200 manufactured by Seiko Instruments Inc. is used as a measuring device, 10 mg of a measurement sample is placed in an aluminum pan, an empty aluminum pan is used as a reference, and a measurement temperature range of 25 to 200 ° C. The glass transition point was determined from the endothermic curve obtained by measuring at a temperature elevation rate of 10 ° C./minute and at normal temperature and humidity.

  The toner for an image forming apparatus according to the present invention is a polymer toner having a two-layer structure of a core portion and a shell portion covering the core portion as described above. There are two types of suspension polymerization and emulsion polymerization. In general, suspension polymerization is a method in which a pigment wax charge control agent or the like is dispersed in a monomer and then dispersed and polymerized in a dispersion medium. After forming primary particles, the outer shell monomer is dispersed again to form a core-shell structure. Let it form. On the other hand, emulsion polymerization forms monomers, waxes, pigments, charge control agents, etc. as dispersions, creates aggregates by associative aggregation, and then forms outer particles and heat-fuses to form toner particles. .

  Hereinafter, the method for producing the toner for an image forming apparatus of the present invention will be described in detail. In the following description, all “parts” represent parts by weight.

  10 parts of n-butyl acrylate, 90 parts by weight of styrene, C.I. I. 5 parts of Pigment Blue 15-1, 1 part of a charge control agent (trade name FCA-201PS, manufactured by Fujikura Kasei Co., Ltd.), 0.3 part of divinylbenzene, and 2 parts of 2,2-azobisisobutyronitrile Prepare a uniformly dispersed monomer composition for internal components (A) by stirring and mixing for 15 minutes at a rotational speed of 10,000 rpm with a TK homomixer (manufactured by Tokki Kako Co., Ltd.), which is a mixer having a shearing force. did.

  On the other hand, 6.9 parts of sodium hydroxide (alkali hydroxide metal salt) were dissolved in 50 parts of ion-exchanged water in an aqueous solution obtained by dissolving 9.8 parts of calcium phosphate (water-soluble polyvalent metal salt) in 250 parts of ion-exchanged water. The aqueous solution was gradually added with stirring to prepare a calcium hydroxide colloid (slightly water-soluble metal hydroxide colloid) dispersion (B).

  Further, 75 parts of styrene, 25 parts of n-butyl acrylate, and 100 parts of water were finely dispersed with an ultrasonic emulsifier (manufactured by Ultrasonic Industries), and a dispersion of the monomer for the outermost surface component (C ) Was prepared.

  Into the calcium hydroxide colloid dispersion liquid (B) thus obtained, the above-mentioned internal component polymerizable monomer composition (A) is added, and high shear stirring is carried out at a rotational speed of 8000 rpm using a TK homomixer. Then, droplets (monomer composition particles) of the monomer composition for internal components were granulated. (A + B)

  The granulated aqueous dispersion (A + B) of the monomer composition for internal components is put into a reactor equipped with a stirring blade, a polymerization reaction is started at 65 ° C., and the reaction is performed for 4 hours. The monomer dispersion (C) was added to the reactor, then 1 part of 1% aqueous potassium persulfate solution was added as a water-soluble radical initiator, and then the reaction was continued for 5 hours to complete the reaction. An aqueous dispersion of polymer particles (toner particles) was obtained.

  The obtained toner particles were embedded with an epoxy resin, then cut to 1 mm thickness with an ultramicrotome, and the cut surface was observed with a transmission electron microscope. As a result, a 0.2 μm thick resin layer was present on the outermost surface of the toner particles. It was confirmed that it was generated.

  While stirring the aqueous dispersion of polymer particles obtained above, the pH of the system is reduced to 4 or less with sulfuric acid and acid washing (25 ° C., 10 minutes) is performed. Water is separated by filtration, and then ion-exchanged water is newly added. 500 parts were added to reslurry and washed with water.

  Thereafter, dehydration and water washing were repeated several times, and the solid content was filtered and separated, followed by drying at 50 ° C. for a whole day and night to obtain toner particles having a volume average particle diameter of 7.2 μm.

  To 100 parts of the toner particles obtained above, 0.3 parts of hydrophobized colloidal silica (trade name: REA200, manufactured by Nippon Aerosil Co., Ltd.) was added and mixed using a Henschel mixer to prepare a toner.

  When the Tg of the obtained toner was measured by DSC, two endothermic peaks, which are glass transition points, were measured. From the monomer composition and polymerization time, the outer Tg1 was 64 ° C. and the core Tg2 was 70 ° C. It could be confirmed.

  As an evaluation of storage stability, 3 g was weighed into a container that can seal the obtained toner, stored at 60 ° C. for 3 hours, and after taking out, it was confirmed whether or not the toner passed through a 330 mesh sieve. Passed and the storage stability was good. In addition, if the storage stability was 90.0% or more, it was determined as OK.

  In addition, using the toner obtained, the pre-heating unit 5 is set so that 80 ° C. heat is applied from the back side of the paper after normal transfer onto the paper with a printer (FS-C8008N manufactured by Kyocera Mita Corporation). After passing, the toner was fixed with the same fixing device (fixing temperature 170 ° C.) as before. The obtained image was a very good image without scattering or tailing, and neither high temperature offset nor low temperature offset occurred. In addition, the fixing portion was folded in half, and it was confirmed that the toner had permeated the paper. The toner was sufficiently permeated and the toner did not peel off from the paper.

  Further, when a solid image was printed and projected on the OHP sheet, it was confirmed that cyan was sufficiently transmitted and the toner was sufficiently melted.

  20 parts of n-butyl acrylate, 80 parts of styrene, C.I. I. 5 parts of Pigment Blue 15-1, 1 part of a charge control agent (trade name FCA-201PS, manufactured by Fujikura Kasei Co., Ltd.), 0.3 part of divinylbenzene, and 2 parts of 2,2-azobisisobutyronitrile Prepare a uniformly dispersed monomer composition for internal components (A) by stirring and mixing for 15 minutes at a rotational speed of 10,000 rpm with a TK homomixer (manufactured by Tokki Kako Co., Ltd.), which is a mixer having a shearing force. did.

  On the other hand, 6.9 parts of sodium hydroxide (alkali hydroxide metal salt) were dissolved in 50 parts of ion-exchanged water in an aqueous solution obtained by dissolving 9.8 parts of calcium phosphate (water-soluble polyvalent metal salt) in 250 parts of ion-exchanged water. The aqueous solution was gradually added with stirring to prepare a calcium hydroxide colloid (slightly water-soluble metal hydroxide colloid) dispersion (B).

  On the other hand, 75 parts of styrene, 25 parts of n-butyl acrylate, and 100 parts of water were finely dispersed with an ultrasonic emulsifier (manufactured by Ultrasonic Industries) to prepare a dispersion (C) of the monomer for the outermost surface component. Prepared.

  Into the calcium hydroxide colloid dispersion liquid (B) thus obtained, the above-mentioned internal component polymerizable monomer composition (A) is added, and high shear stirring is carried out at a rotational speed of 8000 rpm using a TK homomixer. Then, droplets (monomer composition particles) of the monomer composition for internal components were granulated. (A + B)

  The granulated aqueous dispersion (A + B) of the monomer composition for internal components was put into a reactor equipped with a stirring blade, and the polymerization reaction was started at 65 ° C. and reacted for 3.5 hours. Add the monomer dispersion for surface component (C) to the reactor, then add 1 part of 1% aqueous potassium persulfate as a water-soluble radical initiator, and then continue the reaction for 4 hours to react. Upon completion, an aqueous dispersion of polymer particles (toner particles) was obtained.

  The obtained toner particles were embedded with an epoxy resin, then cut to 1 mm thickness with an ultramicrotome, and the cut surface was observed with a transmission electron microscope. As a result, a 0.2 μm thick resin layer was present on the outermost surface of the toner particles. It was confirmed that it was generated.

  While stirring the aqueous dispersion of polymer particles obtained above, the pH of the system is reduced to 4 or less with sulfuric acid and acid washing (25 ° C., 10 minutes) is performed. Water is separated by filtration, and then ion-exchanged water is newly added. 500 parts were added to reslurry and washed with water.

  Thereafter, again, dehydration and water washing were repeated several times, and the solid content was filtered and separated, followed by drying at 50 ° C. for a whole day and night to obtain toner particles having a volume average particle diameter of 7.4 μm.

  To 100 parts of the toner particles obtained above, 0.3 part of hydrophobized colloidal silica (trade name: REA200, manufactured by Nippon Aerosil Co., Ltd.) was added and mixed using a Henschel mixer to prepare a toner.

  When the Tg of the obtained toner was measured by DSC, two endothermic peaks, which are glass transition points, were measured. From the monomer composition and polymerization time, the outer Tg1 was 53 ° C. and the core Tg2 was 60 ° C. all right.

  As an evaluation of storage stability, 3 g was weighed into a container capable of sealing the obtained toner, stored at 60 ° C. for 3 hours, taken out, and then checked whether the toner passed through a 330 mesh sieve. 4% passed and the storage stability was good.

  Also, using the obtained toner, transfer to the paper as usual with a printer (FS-C8008N manufactured by Kyocera Mita Corporation), and then pass through the preheating unit 5 so that 80 ° C. heat is applied from the back side of the paper. Then, the toner was fixed with the same fixing device (fixing temperature 170 ° C.) as before. The obtained image was a very good image without scattering or tailing, and neither high temperature offset nor low temperature offset occurred. In addition, the fixing portion was folded in half, and it was confirmed that the toner had permeated the paper. The toner was sufficiently permeated and the toner did not peel off from the paper.

  Further, when a solid image was printed and projected on the OHP sheet, it was confirmed that cyan was sufficiently transmitted and the toner was sufficiently melted.

  20 parts of n-butyl acrylate, 80 parts of styrene, C.I. I. 5 parts of Pigment Blue 15-1, 1 part of a charge control agent (trade name FCA-201PS, manufactured by Fujikura Kasei Co., Ltd.), 0.3 part of divinylbenzene, and 2 parts of 2,2-azobisisobutyronitrile Prepare a uniformly dispersed monomer composition for internal components (A) by stirring and mixing for 15 minutes at a rotational speed of 10,000 rpm with a TK homomixer (manufactured by Tokki Kako Co., Ltd.), which is a mixer having a shearing force. did.

  On the other hand, 6.9 parts of sodium hydroxide (alkali hydroxide metal salt) were dissolved in 50 parts of ion-exchanged water in an aqueous solution obtained by dissolving 9.8 parts of calcium phosphate (water-soluble polyvalent metal salt) in 250 parts of ion-exchanged water. The aqueous solution was gradually added with stirring to prepare a calcium hydroxide colloid (slightly water-soluble metal hydroxide colloid) dispersion (B).

  On the other hand, 80 parts of styrene, 20 parts of n-butyl acrylate, and 100 parts of water were subjected to a fine dispersion treatment with an ultrasonic emulsifier (manufactured by Ultrasonic Industries Co., Ltd.). Prepared.

  Into the obtained calcium hydroxide colloid dispersion (B), the polymerizable monomer composition for internal components (A) is charged, and is stirred with high shear at a rotational speed of 8000 rpm using a TK homomixer. Droplets (monomer composition particles) of the monomer composition for internal components were granulated. (A + B)

  The granulated aqueous dispersion (A + B) of the monomer composition for internal components was put into a reactor equipped with a stirring blade, and the polymerization reaction was started at 65 ° C. and reacted for 4.0 hours. Add the monomer dispersion for surface component (C) to the reactor, then add 1 part of 1% aqueous potassium persulfate as a water-soluble radical initiator, and then continue the reaction for 6 hours. Upon completion, an aqueous dispersion of polymer particles (toner particles) was obtained.

  The obtained toner particles were embedded with an epoxy resin, then cut to 1 mm thickness with an ultramicrotome, and the cut surface was observed with a transmission electron microscope. As a result, a 0.2 μm thick resin layer was present on the outermost surface of the toner particles. It was confirmed that it was generated.

  While stirring the aqueous dispersion of polymer particles obtained above, the pH of the system is reduced to 4 or less with sulfuric acid and acid washing (25 ° C., 10 minutes) is performed. Water is separated by filtration, and then ion-exchanged water is newly added. 500 parts were added to reslurry and washed with water.

  Thereafter, dehydration and water washing were repeated several times, and the solid content was filtered and separated, followed by drying at 50 ° C. for a whole day and night to obtain toner particles having a volume average particle diameter of 7.6 μm.

  To 100 parts of the toner particles obtained above, 0.3 part of hydrophobized colloidal silica (trade name: REA200, manufactured by Nippon Aerosil Co., Ltd.) was added and mixed using a Henschel mixer to prepare a toner.

  When the Tg of the obtained toner was measured by DSC, two endothermic peaks, which are glass transition points, were measured. From the monomer composition and polymerization time, the outer Tg1 was 75 ° C and the Tg2 of the core portion was 65 ° C. all right.

  As an evaluation of storage stability, 3 g was weighed into a container capable of sealing the obtained toner, stored at 60 ° C. for 3 hours, and after taking out, it was confirmed whether or not the toner passed through a 330 mesh sieve. % Passed and the storage stability was good.

  Also, using the obtained toner, transfer to the paper as usual with a printer (FS-C8008N manufactured by Kyocera Mita Corporation), and then pass through the preheating unit 5 so that 80 ° C. heat is applied from the back side of the paper. Then, the toner was fixed with the same fixing device (fixing temperature 170 ° C.) as before. The obtained image was a very good image without scattering or tailing, and neither high temperature offset nor low temperature offset occurred. Further, when the fixing portion was folded in half and the penetration of the toner into the paper was confirmed, the toner was sufficiently penetrated and the toner did not peel off from the paper.

  Further, when a solid image was printed and projected on the OHP sheet, it was confirmed that cyan was sufficiently transmitted and the toner was sufficiently melted.

  90 parts of styrene, 10 parts of n-butyl acrylate, C.I. I. 5 parts of Pigment Blue 15-1, 1 part of a charge control agent (trade name FCA-201PS, manufactured by Fujikura Kasei Co., Ltd.), 0.3 part of divinylbenzene, and 2 parts of 2,2-azobisisobutyronitrile Prepare a uniformly dispersed monomer composition for internal components (A) by stirring and mixing for 15 minutes at a rotational speed of 10,000 rpm with a TK homomixer (manufactured by Tokki Kako Co., Ltd.), which is a mixer having a shearing force. did.

  On the other hand, 6.9 parts of sodium hydroxide (alkali hydroxide metal salt) were dissolved in 50 parts of ion-exchanged water in an aqueous solution obtained by dissolving 9.8 parts of calcium phosphate (water-soluble polyvalent metal salt) in 250 parts of ion-exchanged water. The aqueous solution was gradually added with stirring to prepare a calcium hydroxide colloid (slightly water-soluble metal hydroxide colloid) dispersion (B).

  On the other hand, 75 parts of styrene, 25 parts of n-butyl acrylate, and 100 parts of water were finely dispersed with an ultrasonic emulsifier (manufactured by Ultrasonic Industries) to prepare a dispersion (C) of the monomer for the outermost surface component. Prepared.

  Into the calcium hydroxide colloid dispersion (B) obtained as described above, the polymerizable monomer composition (A) for internal components is added and stirred with high shear using a TK homomixer at a rotational speed of 8000 rpm. Then, droplets (monomer composition particles) of the monomer composition for internal components were granulated. (A + B)

  The granulated aqueous dispersion (A + B) of the monomer composition for internal components was put into a reactor equipped with a stirring blade, and the polymerization reaction was started at 65 ° C. and reacted for 3.5 hours. Add the monomer dispersion for surface component (C) to the reactor, then add 1 part of 1% aqueous potassium persulfate as a water-soluble radical initiator, and then continue the reaction for 5.0 hours. The reaction was completed to obtain an aqueous dispersion of polymer particles (toner particles).

  When the Tg of the obtained toner was measured by DSC, two endothermic peaks, which are glass transition points, were measured. From the monomer composition and polymerization time, the outer Tg1 was 64 ° C. and the core Tg2 was 75 ° C. I understood.

  While stirring the aqueous dispersion of polymer particles obtained as described above, the pH of the system is reduced to 4 or less with sulfuric acid, acid washing (25 ° C., 10 minutes) is performed, water is separated by filtration, and a new ion exchange is performed. 500 parts of water was added to reslurry and washed with water.

  Thereafter, dehydration and water washing were repeated several times, and the solid content was filtered and separated, followed by drying at 50 ° C. for a whole day and night to obtain toner particles having a volume average particle diameter of 7.2 μm.

  As an evaluation of storability, 3 g was weighed into a container capable of sealing the obtained toner, stored at 60 ° C. for 3 hours, and after taking out, it was confirmed whether or not the toner passed through a 330 mesh sieve. % Passed and the storage stability was good.

  In addition, after the normal toner image was transferred to the paper with a printer (FS-C8008N manufactured by Kyocera Mita Co., Ltd.) using the obtained toner, the preheating unit 5 was set so that 80 ° C. heat was applied from the back side of the paper. After passing, the toner was fixed with the same fixing device (fixing temperature 170 ° C.) as before. The obtained image was a very good image without scattering or tailing, and neither high temperature offset nor low temperature offset occurred. In addition, the fixing portion was folded in half, and it was confirmed that the toner had permeated the paper. The toner was sufficiently permeated and the toner did not peel off from the paper.

  Further, when a solid image was printed on an OHP sheet and projected, it was confirmed that cyan was sufficiently transmitted and the toner was sufficiently melted.

Comparative Example 1

  20 parts of n-butyl acrylate, 80 parts of styrene, C.I. I. 5 parts of Pigment Blue 15-1, 1 part of a charge control agent (trade name FCA-201PS, manufactured by Fujikura Kasei Co., Ltd.), 0.3 part of divinylbenzene, and 2 parts of 2,2-azobisisobutyronitrile Prepare a uniformly dispersed monomer composition for internal components (A) by stirring and mixing for 15 minutes at a rotational speed of 10,000 rpm with a TK homomixer (manufactured by Tokki Kako Co., Ltd.), which is a mixer having a shearing force. did.

  On the other hand, 6.9 parts of sodium hydroxide (alkali hydroxide metal salt) were dissolved in 50 parts of ion-exchanged water in an aqueous solution obtained by dissolving 9.8 parts of calcium phosphate (water-soluble polyvalent metal salt) in 250 parts of ion-exchanged water. The aqueous solution was gradually added with stirring to prepare a calcium hydroxide colloid (slightly water-soluble metal hydroxide colloid) dispersion (B).

  On the other hand, 70 parts of styrene, 30 parts of n-butyl acrylate, and 100 parts of water were finely dispersed with an ultrasonic emulsifier (manufactured by Ultrasonic Industrial Co., Ltd.). Prepared.

  Into the calcium hydroxide colloid dispersion (B) obtained as described above, the polymerizable monomer composition (A) for internal components is added and stirred with high shear using a TK homomixer at a rotational speed of 8000 rpm. Then, droplets (monomer composition particles) of the monomer composition for internal components were granulated. (A + B)

  The granulated aqueous dispersion (A + B) of the monomer composition for internal components was put into a reactor equipped with a stirring blade, and the polymerization reaction was started at 65 ° C. and reacted for 4.0 hours. Add the monomer dispersion for surface component (C) to the reactor, then add 1 part of 1% aqueous potassium persulfate as a water-soluble radical initiator, and then continue the reaction for 4.0 hours. The reaction was completed to obtain an aqueous dispersion of polymer particles (toner particles).

  When the Tg of the obtained toner was measured by DSC, two endothermic peaks, which are glass transition points, were measured. From the monomer composition and polymerization time, it was found that the outer Tg1 was 43 ° C and the core Tg2 was 62 ° C. It was.

  While stirring the aqueous dispersion of polymer particles obtained as described above, the pH of the system is reduced to 4 or less with sulfuric acid, acid washing (25 ° C., 10 minutes) is performed, water is separated by filtration, and a new ion exchange is performed. 500 parts of water was added to reslurry and washed with water.

  Thereafter, again, dehydration and water washing were repeated several times, and the solid content was separated by filtration, followed by drying at 50 ° C. for a whole day and night with a dryer, to obtain toner particles having a volume average particle diameter of 7.9 μm.

  As an evaluation of storability, 3 g was weighed into a container that can seal the obtained toner, stored at 60 ° C. for 3 hours, and after taking out, it was confirmed whether the toner passed through a 330 mesh sieve. It was poor in storage stability, passing only 45.0%.

  In addition, after the normal toner image was transferred to the paper with a printer (FS-C8008N manufactured by Kyocera Mita Co., Ltd.) using the obtained toner, the preheating unit 5 was set so that 80 ° C. heat was applied from the back side of the paper. After passing, the toner was fixed with the same fixing device (fixing temperature 170 ° C.) as before. The obtained image was a very good image without scattering or tailing, and neither high temperature offset nor low temperature offset occurred. In addition, the fixing portion was folded in half, and it was confirmed that the toner had permeated the paper. The toner was sufficiently permeated and the toner did not peel off from the paper.

  Further, when a solid image was printed and projected on the OHP sheet, it was confirmed that although the color was slightly black, cyan was sufficiently transmitted and the toner was sufficiently melted.

Comparative Example 2

  20 parts of n-butyl acrylate, 80 parts of styrene, C.I. I. 5 parts of Pigment Blue 15-1, 1 part of a charge control agent (trade name FCA-201PS, manufactured by Fujikura Kasei Co., Ltd.), 0.3 part of divinylbenzene, and 2 parts of 2,2-azobisisobutyronitrile Prepare a uniformly dispersed monomer composition for internal components by stirring and mixing for 15 minutes at a rotational speed of 10,000 rpm with a TK homomixer (manufactured by Koki Kako Co., Ltd.), which is a mixer having shearing force (A) did.

  On the other hand, 6.9 parts of sodium hydroxide (alkali hydroxide metal salt) were dissolved in 50 parts of ion-exchanged water in an aqueous solution obtained by dissolving 9.8 parts of calcium phosphate (water-soluble polyvalent metal salt) in 250 parts of ion-exchanged water. The aqueous solution was gradually added with stirring to prepare a calcium hydroxide colloid (slightly water-soluble metal hydroxide colloid) dispersion (B).

  On the other hand, 90 parts of styrene, 10 parts of n-butyl acrylate, and 100 parts of water were subjected to a fine dispersion treatment with an ultrasonic emulsifier (manufactured by Ultrasonic Industries) to obtain a dispersion (C) of the monomer for the outermost surface component. Prepared.

  Into the calcium hydroxide colloid dispersion (B) obtained as described above, the polymerizable monomer composition (A) for internal components is added and stirred with high shear using a TK homomixer at a rotational speed of 8000 rpm. Then, droplets (monomer composition particles) of the monomer composition for internal components were granulated. (A + B)

  The granulated aqueous dispersion (A + B) of the monomer composition for internal components was put into a reactor equipped with a stirring blade, and the polymerization reaction was started at 65 ° C. and reacted for 4.0 hours. Add the monomer dispersion for surface component (C) to the reactor, then add 1 part of 1% aqueous potassium persulfate as a water-soluble radical initiator, and then continue the reaction for 6.0 hours. The reaction was completed to obtain an aqueous dispersion of polymer particles (toner particles).

  When the Tg of the obtained toner was measured by DSC, two endothermic peaks, which are glass transition points, were measured. From the monomer composition and polymerization time, it was found that the outer Tg1 was 86 ° C and the Tg2 of the core portion was 62 ° C. It was.

  While stirring the aqueous dispersion of polymer particles obtained as described above, the pH of the system is reduced to 4 or less with sulfuric acid, acid washing (25 ° C., 10 minutes) is performed, water is separated by filtration, and a new ion exchange is performed. 500 parts of water was added to reslurry and washed with water.

  Thereafter, again, dehydration and water washing were repeated several times, and the solid content was filtered and separated, followed by drying at 50 ° C. for a whole day and night with a dryer to obtain toner particles having a volume average particle diameter of 7.0 μm.

  As an evaluation of storability, 3 g was weighed into a container that can seal the obtained toner, stored at 60 ° C. for 3 hours, and after taking out, it was confirmed whether or not the toner passed through a 330 mesh sieve. Passed and the storage stability was good.

  In addition, after the normal toner image was transferred to the paper with a printer (FS-C8008N manufactured by Kyocera Mita Co., Ltd.) using the obtained toner, the preheating unit 5 was set so that 80 ° C. heat was applied from the back side of the paper. After passing, the toner was fixed with the same fixing device (fixing temperature 170 ° C.) as before. Scattering and tailing occurred in the obtained image. Neither high-temperature offset nor low-temperature offset occurred. In addition, the fixing portion was folded in half, and it was confirmed that the toner had permeated the paper. The toner was sufficiently permeated and the toner did not peel off from the paper.

  Further, when a solid image was printed and projected on the OHP sheet, it was confirmed that cyan was sufficiently transmitted and the toner was sufficiently melted.

Comparative Example 3

  30 parts of n-butyl acrylate with respect to 70 parts of styrene, C.I. I. 5 parts of Pigment Blue 15-1, 1 part of a charge control agent (trade name FCA-201PS, manufactured by Fujikura Kasei Co., Ltd.), 0.3 part of divinylbenzene, and 2 parts of 2,2-azobisisobutyronitrile Prepare a uniformly dispersed monomer composition for internal components (A) by stirring and mixing for 15 minutes at a rotational speed of 10,000 rpm with a TK homomixer (manufactured by Tokki Kako Co., Ltd.), which is a mixer having a shearing force. did.

  On the other hand, 6.9 parts of sodium hydroxide (alkali hydroxide metal salt) were dissolved in 50 parts of ion-exchanged water in an aqueous solution obtained by dissolving 9.8 parts of calcium phosphate (water-soluble polyvalent metal salt) in 250 parts of ion-exchanged water. The aqueous solution was gradually added with stirring to prepare a calcium hydroxide colloid (slightly water-soluble metal hydroxide colloid) dispersion (B).

  On the other hand, 75 parts of styrene, 25 parts of n-butyl acrylate, and 100 parts of water were finely dispersed with an ultrasonic emulsifier (manufactured by Ultrasonic Industries) to prepare a dispersion (C) of the monomer for the outermost surface component. Prepared.

  Into the calcium hydroxide colloid dispersion (B) obtained as described above, the polymerizable monomer composition (A) for internal components is added and stirred with high shear using a TK homomixer at a rotational speed of 8000 rpm. Then, droplets (monomer composition particles) of the monomer composition for internal components were granulated. (A + B)

  The granulated aqueous dispersion (A + B) of the monomer composition for internal components was placed in a reactor equipped with a stirring blade, and the polymerization reaction was started at 65 ° C. and reacted for 3.0 hours. Add the monomer dispersion for surface component (C) to the reactor, then add 1 part of 1% aqueous potassium persulfate as a water-soluble radical initiator, and then continue the reaction for 5.0 hours. The reaction was completed to obtain an aqueous dispersion of polymer particles (toner particles).

  When the Tg of the obtained toner was measured by DSC, two endothermic peaks, which are glass transition points, were measured, and it was found from the monomer composition and polymerization time that the outer Tg1 was 60 ° C. and the core Tg 2 was 42 ° C. It was.

  While stirring the aqueous dispersion of polymer particles obtained as described above, the pH of the system is reduced to 4 or less with sulfuric acid, acid washing (25 ° C., 10 minutes) is performed, water is separated by filtration, and a new ion exchange is performed. 500 parts of water was added to reslurry and washed with water.

  Thereafter, again, dehydration and water washing were repeated several times, and the solid content was filtered and separated, followed by drying at 50 ° C. for a whole day and night to obtain toner particles having a volume average particle diameter of 7.4 μm.

  As an evaluation of storability, 3 g was weighed into a container that can seal the obtained toner, stored at 60 ° C. for 3 hours, and after taking out, it was confirmed whether or not the toner passed through a 330 mesh sieve. It did not pass and was poorly stored.

  In addition, using the toner obtained, the pre-heating unit 5 is set so that 80 ° C. heat is applied from the back side of the paper after normal transfer onto the paper with a printer (FS-C8008N manufactured by Kyocera Mita Corporation). After passing, the toner was fixed with the same fixing device (fixing temperature 170 ° C.) as before. Although the obtained image did not scatter or tail, a high temperature offset occurred and toner adhered to the image.

  Further, when a solid image on the OHP sheet was printed and projected, it was confirmed that cyan was sufficiently transmitted and the toner was sufficiently melted.

Comparative Example 4

  90 parts of styrene, 10 parts of n-butyl acrylate, C.I. I. 5 parts of Pigment Blue 15-1, 1 part of a charge control agent (trade name FCA-201PS, manufactured by Fujikura Kasei Co., Ltd.), 0.3 part of divinylbenzene, and 2 parts of 2,2-azobisisobutyronitrile Prepare a uniformly dispersed monomer composition for internal components (A) by stirring and mixing for 15 minutes at a rotational speed of 10,000 rpm with a TK homomixer (manufactured by Tokki Kako Co., Ltd.), which is a mixer having a shearing force. did.

  On the other hand, 6.9 parts of sodium hydroxide (alkali hydroxide metal salt) were dissolved in 50 parts of ion-exchanged water in an aqueous solution obtained by dissolving 9.8 parts of calcium phosphate (water-soluble polyvalent metal salt) in 250 parts of ion-exchanged water. The aqueous solution was gradually added with stirring to prepare a calcium hydroxide colloid (slightly water-soluble metal hydroxide colloid) dispersion (B).

  On the other hand, 75 parts of styrene, 25 parts of n-butyl acrylate, and 100 parts of water were finely dispersed with an ultrasonic emulsifier (manufactured by Ultrasonic Industries) to prepare a dispersion (C) of the monomer for the outermost surface component. Prepared.

  Into the calcium hydroxide colloid dispersion (B) obtained as described above, the polymerizable monomer composition (A) for internal components is added and stirred with high shear using a TK homomixer at a rotational speed of 8000 rpm. Then, droplets (monomer composition particles) of the monomer composition for internal components were granulated. (A + B)

  The granulated aqueous dispersion (A + B) of the monomer composition for internal components was put into a reactor equipped with a stirring blade, and the polymerization reaction was started at 65 ° C. and reacted for 6.0 hours. Add the monomer dispersion for surface component (C) to the reactor, then add 1 part of 1% aqueous potassium persulfate as a water-soluble radical initiator, and then continue the reaction for 5.0 hours. The reaction was completed to obtain an aqueous dispersion of polymer particles (toner particles).

  When the Tg of the obtained toner was measured by DSC, two endothermic peaks, which are glass transition points, were measured. From the monomer composition and polymerization time, the outer Tg1 was 60 ° C. and the core Tg2 was 87 ° C. all right.

  While stirring the aqueous dispersion of polymer particles obtained as described above, the pH of the system is reduced to 4 or less with sulfuric acid, acid washing (25 ° C., 10 minutes) is performed, water is separated by filtration, and a new ion exchange is performed. 500 parts of water was added to reslurry and washed with water.

  Thereafter, again, dehydration and water washing were repeated several times, and the solid content was filtered and separated, followed by drying at 50 ° C. for a whole day and night to obtain toner particles having a volume average particle diameter of 7.4 μm.

  As an evaluation of storage stability, 3 g of the obtained toner was placed in a container that can be sealed, stored at 60 ° C. for 3 hours, and after removal, it was confirmed whether or not the toner passed through a 330 mesh sieve. Passed and the storage stability was good.

  However, after the normal toner image is transferred to the paper with a printer (FS-C8008N manufactured by Kyocera Mita Corporation) using the obtained toner, the preheating unit 5 is set so that 80 ° C. heat is applied from the back side of the paper. After passing, the toner was fixed with the same fixing device (fixing temperature 170 ° C.) as before. Although the obtained image did not scatter or tail, a low temperature offset occurred in the second fixing portion.

  Further, when a solid image was printed and projected on the OHP sheet, light was not sufficiently transmitted and the color became dull cyan, and it was confirmed that the toner was not sufficiently melted.

  The table of FIG. 2 summarizes the above results. In this table, “Tg1 shell part” is the composition of the shell part and the polymerization reaction time, and “Tg2 core part” is the composition of the core part and the polymerization reaction time. Also, “Tg1” and “Tg2” on the right are the glass transition points, “Preservation” is the percentage of the toner that passed through the 330 mesh screen, “Fixability” is the presence or absence of offset, and “Obiki” is Presence / absence of the fixing tail and “transparency” indicate whether the toner is sufficiently melted, “◯” indicates that the toner is satisfactory, and “X” indicates that there is an image defect.

As is apparent from this table, Tg1 and Tg2 are 50 ° C <Tg1 <80 ° C as described above.
50 ° C <Tg2 <80 ° C
In Examples 1 to 4 contained in the sample, “preservability”, “fixability”, “snoring”, and “transparency” are all good, but this range is out of comparison with Tg1. In Example 1, there is a problem in “preservability” and “transparency”, and in Comparative Example 2, “preservation” is good but there is a problem in “snoring”. Further, in Comparative Example 3 in which Tg2 is out of this range, there is a problem in “fixability”, and in Comparative Example 4, there is a problem in “fixability” and “transparency”.

Therefore, also from this result, it is understood that it is preferable to keep Tg1 and Tg2 within the following ranges.
50 ° C <Tg1 <80 ° C
50 ° C <Tg2 <80 ° C

  As described above, according to the present invention, the toner for an image forming apparatus is a polymer toner having a two-layer structure of a core part and a shell part covering the core part, and the image forming apparatus side is provided with a recording medium conveying belt. The recording medium is conveyed to the fixing device, and a preheating unit is provided on the upstream side of the fixing heater of the recording medium conveyance belt, and the toner shell is at least softened by the preheating unit. The toner particles adhere to each other by heating in the heating section, and the toner does not scatter or flutter, and the above-mentioned phenomena such as “scattering” and “fixing tailing” do not occur, and the image quality is high and the definition is high. It is possible to provide a toner for an image forming apparatus capable of obtaining a stable image.

  According to the present invention, it is possible to provide a toner for an image forming apparatus capable of obtaining a high-quality and high-definition image without causing phenomena such as “scattering” and “fixing tailing”.

FIG. 3 is a schematic configuration diagram of a fixing device in an image forming apparatus using the toner for an image forming apparatus of the present invention. 6 is a table showing the results of experiments conducted by changing the method for producing a toner for an image forming apparatus according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fixing roller 2 Pressure roller 3 Conveying belt 4 of recording medium Drive roller 5 Preheating part 6 Recording medium

Claims (3)

A toner for developing a latent image formed on a photoreceptor by electrophotography,
The toner is a polymerized toner having a two-layer structure including a core portion using a first thermoplastic resin in the center and a shell portion covering the outside of the core portion and using a second thermoplastic resin.
The second thermoplastic resin constituting the shell portion is a backup medium provided on the upstream side of the thermal fixing unit in the recording medium conveying belt for conveying the recording medium on which the toner image is transferred to a fixing device having a thermal fixing unit. Consists of a material that is at least softened by heating means,
The first thermoplastic resin constituting the core portion is made of a material that is melted together with the second thermoplastic resin by the thermal fixing means and fixed to the recording medium. Toner for equipment. When the glass transition temperature of the second thermoplastic resin constituting the shell portion is Tg1, and the glass transition temperature of the first thermoplastic resin constituting the core portion is Tg2,
50 ° C <Tg1 <80 ° C
50 ° C <Tg2 <80 ° C
The toner for an image forming apparatus according to claim 1, wherein the toner is an image forming apparatus.   3. The toner for an image forming apparatus according to claim 1, wherein the toner is softened by the preheating unit at approximately 80 ° C., and the fixing to the recording medium is performed in a range of 160 to 180 ° C. 3. .

Images