JP2011090135A - Toner for laser fixation, and image forming apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner for laser fixation with little reflection of a laser beam from the surface of a toner particle and having high utilization efficiency of the laser beam; and to provide an image forming apparatus using the same. <P>SOLUTION: In the toner used for the image forming apparatus employing a laser fixation method, a reflection preventing film 22 for the laser beam to be used for fixation is formed on the surface of a core particle 21 including at least a binder resin and a coloring material. When a laser beam source having 780 nm wavelength is used and a polyester having a refractive index of about 1.57 is used as the material of the binder resin of the core particle 21, the reflection preventing film 22 can be formed by using one layer of a film formed by a material having a refractive index of 1.3 to 1.4. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a printer, or a facsimile, and more specifically, includes a fixing device that fixes an unfixed toner image formed on a recording paper by a laser beam irradiation means. The present invention relates to an image forming apparatus and a toner used therefor.

  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 recording member 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.

However, the conventional roller pair system requires warm-up time because it is necessary to raise the fixing roller and the pressure roller to a predetermined temperature after the power is turned on. Further, since it is necessary to keep the roller surface at a predetermined temperature during the standby state when the copying operation is not performed, the roller surface must be constantly heated even when the copying operation is not performed, and wasteful energy is consumed. .
Therefore, as a method of fixing only the toner efficiently without consuming unnecessary energy, a method of fixing the toner by irradiating it with laser light or light from a xenon flash lamp and fixing it (light fixing method) has been proposed. (For example, see Patent Documents 2 and 3).

Japanese Patent Laid-Open No. 11-38802 JP-A-7-191560 JP 2003-280247 A

  However, when using the photofixing method, it is important to absorb the light efficiently in the toner. However, in the current toner, the ratio of the light entering the inside of the particle is reduced due to reflection on the toner particle surface. There is a problem that the utilization efficiency of light is low.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a laser fixing toner with low laser beam reflection on the surface of toner particles and high use efficiency of the laser beam, and an image using the same. It is to provide a forming apparatus.

  In order to solve the above-described problem, a first technical means of the present invention is a toner used in an image forming apparatus employing a laser fixing method, on the surface of core particles containing at least a binder resin and a coloring material. An antireflection film for laser light used for fixing is formed.

  A second technical means of the present invention is characterized in that, in the first technical means, the antireflection film comprises a single layer film formed of a material having a refractive index of 1.3 to 1.4. is there.

  According to a third technical means of the present invention, in the first technical means, the antireflection film is composed of a two-layer film.

  According to a fourth technical means of the present invention, in any one of the first to third technical means, the antireflection film is formed by fusing resin particles.

  A fifth technical means of the present invention is an image forming apparatus using the toner of any one of the first to fourth technical means.

  According to a sixth technical means of the present invention, in the fifth technical means, the image forming apparatus forms a color image, and at least the last color to be superimposed to form the color image It is characterized by using toner.

  According to the present invention, since the reflection of the laser beam on the toner particle surface is small and the ratio of the light penetrating into the inside of the particle is large, the utilization efficiency of the fixing light can be increased.

1 is a diagram illustrating an example of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a diagram illustrating an example of a fixing device used in the image forming apparatus in FIG. 1. 3 is a cross-sectional view schematically illustrating an example of the toner of the present invention. FIG. It is a figure which shows the relationship between the reflectance of the toner which a coating layer consists of one layer, and the thickness and refractive index of a coating layer. It is a figure which shows the relationship between the reflectance of the toner which a coating layer consists of two layers, and the film thickness of an inner layer.

  First, an image forming apparatus using the toner of the present invention will be described with reference to FIGS. The image forming apparatus 1 in FIG. 1 includes image forming units 2B, 2C, 2M, and 2Y that form toner images of black, cyan, magenta, and yellow, respectively, by electrophotography.

  Since the image forming units 2B, 2C, 2M, and 2Y have the same configuration except for the color of the toner used, the image forming units 2B, 2C, 2M, and 2Y will be collectively described below as the image forming unit 2. The image forming unit 2 forms an electrostatic latent image by irradiating the charged photosensitive drum 3 with laser light, a photosensitive drum 3 having a photosensitive layer, a charging device 4 for charging the photosensitive layer to a predetermined potential. An exposure device 5 that stores toner of a corresponding color and develops an electrostatic latent image on the photosensitive drum 3 with the toner, and a toner image on the photosensitive drum 3 is transferred to an intermediate transfer belt 9 described later. A primary transfer device 7 that performs primary transfer and a drum cleaner 8 that removes toner and the like on the photosensitive drum 3 after the primary transfer are included.

  In addition, the image forming apparatus 1 includes an intermediate transfer belt 9 to which the toner images of the respective colors formed by the image forming units 2B, 2C, 2M, and 2Y are sequentially transferred, and an image transferred on the intermediate transfer belt 9 in an overlapping manner. A secondary transfer device 12 for transferring to the paper P (an example of a recording member) conveyed by the roller pair 11 from the paper storage unit 10, a fixing device 13 for fixing the secondary transferred image on the paper P, Is provided. The paper P discharged from the fixing device 13 is sent out of the device by the discharge roller 14.

  The image forming apparatus 1 uses a laser fixing method. Therefore, the fixing device 13 has a configuration as shown in FIG. 2, for example. That is, the fixing device 13 includes a laser light source 13a that generates laser light, and a rotary polygon mirror 13c that reflects the laser light emitted from the laser light source 13a and scans and exposes the endless belt 13b. A collimator lens or the like can be provided in the optical path between the laser light source 13a and the rotating polygon mirror 13c, and an fθ lens, a folding mirror, or the like is provided between the rotating polygon mirror 13c and the endless belt 13b. Can do.

While the paper P passes, the laser light from the laser light source 13a is scanned by the rotary polygon mirror 13c and applied to the toner held on the paper P. Then, the toner that generates heat due to the absorption of light is melted and fixed on the paper.
In this example, a configuration in which the light of one semiconductor laser is scanned by a rotating polygon mirror is used, but a configuration in which a plurality of semiconductor lasers are arranged and irradiated without scanning can also be used.

  Subsequently, an example of the toner of the present invention will be described with reference to FIGS. FIG. 3 is a cross-sectional view schematically showing an example of the toner of the present invention. The toner particles of the toner of the present invention are comprised of core particles 21 that are resin particles and a coating layer (antireflection film) 22 that coats the surface of the core particles, as exemplified by reference numeral 20 in the figure. Since the coating layer 22 uses light interference, it is necessary to change the film thickness in proportion to the wavelength when the laser wavelength to be used is different. In the example described below, a semiconductor laser having a wavelength of 780 nm is used as the fixing laser.

  The core particle 21 is composed of a binder resin, a colorant, a charge control agent, a release agent, and the like, and an infrared absorber may be added depending on the light source used. When the reflection on the surface of the toner particles is considered, the refractive index of the binder resin is most important, and polyester, acrylic resin, styrene-acrylic resin, or the like is used as the binder resin. In this example, polyester (refractive index = about 1.57) is used as the binder resin.

  The covering layer 22 may be composed of one layer or two layers.

(When the coating layer 22 is composed of one layer)
FIG. 4 shows the result of calculating the reflectance in the vertical direction when a material having a refractive index of 1.57 is used as the binder resin for the core particles 21 and the coating layer 22 having a different refractive index is provided. When there is no coating layer (that is, when the film thickness is 0 nm in FIG. 4), the surface reflectance is slightly less than 5%. On the other hand, when the coating layer 22 having a refractive index of 1.3, 1.35, or 1.4 is provided with a thickness of 100 to 200 nm, the surface reflectance is 2 as shown in FIGS. %, And the amount of laser light entering the core particles 21 of the toner particles 20 can be increased, so that the utilization efficiency of the laser light can be increased. When the refractive index of the coating layer 22 is 1.45 or more, as shown in FIG. 4D, the surface reflectance cannot be reduced to 2% or less, so that the antireflection effect of the coating layer 22 is reduced.

  Thus, when the coating layer 22 is composed of one layer, it is desirable to use a material having a refractive index of about 1.3 to 1.4. As a specific material, silicon resin, amorphous fluorine-based resin, magnesium fluoride, or the like can be used.

(When the coating layer 22 is composed of two layers)
In general, a two-layer film has a reflectivity of 0 when the following conditions (1) and (2) are satisfied.
(1) ns · n1 ² = n0 · n2 ²
(2) 4 · n1 · d1 = 4n2 · d2 = λ
n0: refractive index of air ns: refractive index of core particle 21 of toner particle 20 λ: wavelength of laser beam n1: refractive index of outer layer, d1: film thickness of outer layer n2: refractive index of inner layer, d2: Film thickness of the inner layer

If conditions close to the above two formulas can be adopted, the reflectance can be lowered.
For example, when the outer layer has a refractive index of 1.4 and a film thickness of 140 nm and the inner layer has a refractive index of 1.75, the relationship between the film thickness of the inner layer and the reflectance is shown in FIG. As shown in the drawing, when the film thickness of the inner layer is about 100 nm, the reflectance can be suppressed while forming the coating layer 22 only with a material having a refractive index of 1.4 or more. A material having a refractive index of 1.4 or more has a wider range of selection than a material having a refractive index of less than 1.4. That is, when the coating layer 22 is formed as an antireflection film, the coating layer is formed of one layer. Rather, the two layers are more flexible in forming material. The coating layer 22 composed of two layers can be realized by using a high refractive index resin such as a polyester resin or a thiaurethane resin in which a silicon resin is added to the outer layer and titanium oxide is added to the inner layer.

  Although it is possible to form the coating layer 22 as an antireflection film with three or more layers, it is desirable to form the coating layer 22 with one or two layers because the manufacturing process becomes longer.

  Various methods are conceivable as a method of forming the coating layer 22. For example, there is a method in which inorganic magnesium fluoride fine particles are attached to the surface of the core particle 21 and then formed into a polymer layer by a capsule technique such as a spray drying method. Hereinafter, other methods, that is, a method of forming the coating layer 22 using shell particles that are resin particles, and conditions of the shell particles will be described.

The toner (toner particles) produced by this method is a capsule toner in which the surface layer portion of the core particles is coated with shell particles, and the shell particles are fused with at least one of the core particles and the adjacent shell particles. To form a coating layer.
When the shell particles are fused and integrated, the strength of the coating layer is increased, and the coating is optically integrated to reduce scattering on the surface, thereby serving as an antireflection film. .

  Moreover, the adhesion strength between the coating layer and the core particles is increased by fusing and integrating the shell particles and the core particles. As a result, for example, the coating layer can be prevented from being detached from the core particles by stirring in the developing container, and the coating layer is less likely to be peeled off, so that the toner surface is made uniform, fluidity and anti-blocking property. Further, it is possible to prevent the toner properties such as charging stability from being changed by long-term use. It also prevents toner spent on the carrier.

The volume average particle diameter of the shell particles used in the toner is related to the film thickness of the coating layer (antireflection film). Since the film thickness of the antireflection film is about 50 nm to 400 nm, the volume average particle diameter of the shell particles is preferably 50 nm to 400 nm.
In addition, when the volume average particle diameter of the shell particles is less than 50 nm, the shell particles are difficult to be immobilized on the surface of the core particles, the thickness of the coating layer formed is thin, and it is difficult to cover the core particle surfaces uniformly. Therefore, a coating layer having a uniform thickness cannot be obtained. Accordingly, toner properties such as fluidity, blocking resistance, and charging stability may be deteriorated, so that 50 nm or more is desirable from the viewpoint of toner properties.

  Further, in the coating process, when a method of spraying the shell particle dispersion containing the shell particles and the adhesion aid from the same spray nozzle is selected, when the volume average particle diameter of the shell particles is less than 50 nm, the shell particle dispersion The dispersibility of the shell particles in the liquid may be reduced.

  A coating layer made of shell particles is formed on the surface of the core particles. Since the coating layer is used as an antireflection film, it is preferably formed on most of the surfaces of the core particles. The major part of the surface of the core particle is a part that occupies 90% or more of the surface area of the core particle.

  The toner is produced by, for example, attaching and fusing the shell particles to the core particles using an adhesion aid that increases the adhesion between the core particles and the shell particles. It includes a manufacturing process, a shell particle and adhesion aid adjusting process, and a coating process. The temporal order of the core particle preparation step and the shell particle and adhesion aid adjusting step may be reversed.

<Core particle production process>
In the core particle production step, core particles containing at least a binder resin and a colorant are produced. As described above, the core particles further contain a charge control agent (charge control agent), a release agent and the like.
The binder resin is not particularly limited as long as it is commonly used as a binder resin for toner, and examples thereof include polyester, polyurethane, epoxy resin, acrylic resin, and styrene-acrylic resin. Among these, polyester, acrylic resin, and styrene-acrylic resin are preferable. One of these resins may be used alone, or two or more thereof may be used in combination. Moreover, even if it is the same kind of resin, it is possible to use a plurality of kinds of resins different in any one or more in terms of molecular weight, monomer composition, and the like.

  Polyester is excellent in transparency, and can impart good powder fluidity, low-temperature fixability, secondary color reproducibility, and the like to the aggregated particles, and is therefore suitable as a binder resin for color toners. Known polyesters can be used, and examples thereof include polycondensates of polybasic acids and polyhydric alcohols. As the polybasic acid, those known as polyester monomers can be used, for example, terephthalic acid, isophthalic acid, phthalic anhydride, trimellitic anhydride, pyromellitic acid, naphthalenedicarboxylic acid and other aromatic carboxylic acids, maleic anhydride Examples thereof include aliphatic carboxylic acids such as acid, fumaric acid, succinic acid, alkenyl succinic anhydride, and adipic acid, and methyl esterified products of these polybasic acids. A polybasic acid can be used individually by 1 type, or can use 2 or more types together. As the polyhydric alcohol, those known as monomers for polyesters can be used. For example, aliphatic polyhydric alcohols such as ethylene glycol, propylene glycol, butanediol, hexanediol, neopentylglycol, glycerin, cyclohexanediol, cyclohexanediene, etc. Examples thereof include aromatic diols such as alicyclic polyhydric alcohols such as methanol and hydrogenated bisphenol A, ethylene oxide adducts of bisphenol A, and propylene oxide adducts of bisphenol A. A polyhydric alcohol can be used individually by 1 type, or can use 2 or more types together. The polycondensation reaction between the polybasic acid and the polyhydric alcohol can be carried out according to a conventional method. For example, the polybasic acid and the polyhydric alcohol are contacted in the presence or absence of an organic solvent and in the presence of a polycondensation catalyst. The process is terminated when the acid value, softening point, etc. of the polyester to be produced reach a predetermined value. Thereby, polyester is obtained. When a methyl esterified product of a polybasic acid is used as a part of the polybasic acid, a demethanol polycondensation reaction is performed. In this polycondensation reaction, for example, the carboxyl group content at the end of the polyester can be adjusted by appropriately changing the mixing ratio of polybasic acid and polyhydric alcohol, the reaction rate, etc., and thus the properties of the resulting polyester are modified. it can. When trimellitic anhydride is used as the polybasic acid, a modified polyester can also be obtained by easily introducing a carboxyl group into the main chain of the polyester. A self-dispersible polyester in water in which a hydrophilic group such as a carboxyl group or a sulfonic acid group is bonded to the main chain and / or side chain of the polyester can also be used. Further, polyester and acrylic resin may be grafted.

  Examples of the styrene-acrylic resin include styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate. Examples thereof include a copolymer, a styrene-butyl methacrylate copolymer, and a styrene-acrylonitrile copolymer.

  As the colorant, organic dyes, organic pigments, inorganic dyes, inorganic pigments and the like commonly used in the electrophotographic field can be used.

Examples of the black colorant include carbon black, copper oxide, manganese dioxide, aniline black, activated carbon, nonmagnetic ferrite, magnetic ferrite, and magnetite.
Examples of yellow colorants include chrome lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, navel yellow, naphthol yellow S, Hansa yellow G, Hansa yellow 10G, benzidine yellow G, and benzidine. Yellow GR, Quinoline Yellow Lake, Permanent Yellow NCG, Tartrazine Lake, CI Pigment Yellow 12, CI Pigment Yellow 13, CI Pigment Yellow 14, CI Pigment Yellow 15, CI Pigment Yellow 17, CI Pigment Yellow 93, CI Pigment Yellow 94, CI Pigment Yellow 138, and the like.

Examples of the orange colorant include red chrome yellow, molybdenum orange, permanent orange GTR, pyrazolone orange, vulcan orange, indanthrene brilliant orange RK, benzidine orange G, indanthrene brilliant orange GK, C.I. pigment orange 31, CI Pigment Orange 43 and the like.
Examples of red colorants include bengara, cadmium red, red lead, mercury sulfide, cadmium, permanent red 4R, risol red, pyrazolone red, watching red, calcium salt, lake red C, lake red D, and brilliant carmine 6B. , Eosin Lake, Rhodamine Lake B, Alizarin Lake, Brilliant Carmine 3B, CI Pigment Red 2, CI Pigment Red 3, CI Pigment Red 5, CI Pigment Red 6, CI Pigment Red 7, C.I. Pigment Red 15, C.I. Pigment Red 16, C.I. Pigment Red 48: 1, C.I. Pigment Red 53: 1, C.I. Pigment Red 57: 1 C.I. Pigment Red 122, C.I. Pigment Red 123, C.I. Pigment C.I. Pigment Red 144, C.I. Pigment Red 149, C.I. Pigment Red 166, C.I. Pigment Red 177, C.I. Pigment Red 178, C.I. Pigment Red 222 Etc.

Examples of purple colorants include manganese purple, fast violet B, and methyl violet lake.
Examples of the blue colorant include bitumen, cobalt blue, alkali blue lake, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partially chlorinated, first sky blue, indanthrene blue BC, and CI pigment. Blue 15, CI pigment blue 15: 2, CI pigment blue 15: 3, CI pigment blue 16, CI pigment blue 60, and the like.

Examples of the green colorant include chromium green, chromium oxide, pigment green B, micalite green lake, final yellow green G, CI pigment green 7, and the like.
Examples of the white colorant include compounds such as zinc white, titanium oxide, antimony white, and zinc sulfide.
One colorant can be used alone, or two or more different colorants can be used in combination. Moreover, even if it is the same color, 2 or more types can be used together. Although the amount of the colorant used is not particularly limited, it is preferably 0.1 to 20 parts by weight, more preferably 0.2 to 10 parts by weight with respect to 100 parts by weight of the binder resin.

  As the release agent, those commonly used in this field can be used, for example, petroleum wax such as paraffin wax and derivatives thereof, microcrystalline wax and derivatives thereof, Fischer-Tropsch wax and derivatives thereof, polyolefin wax (polyethylene wax, polypropylene Wax etc.) and derivatives thereof, low molecular weight polypropylin wax and derivatives thereof, hydrocarbon polymer waxes such as polyolefin polymer wax (low molecular weight polyethylene wax etc.) and derivatives thereof, carnauba wax and derivatives thereof, rice wax and derivatives thereof , Candelilla wax and its derivatives, plant wax such as wood wax, animal wax such as beeswax and whale wax, fatty acid amide, phenol fatty acid ester, etc. Oil-based synthetic waxes, long-chain carboxylic acids and their derivatives, long-chain alcohols and derivatives thereof, silicon-based polymers, such as higher fatty acids. Derivatives include oxides, block copolymers of vinyl monomers and waxes, graft modified products of vinyl monomers and waxes, and the like. The amount of the wax used is not particularly limited and can be appropriately selected from a wide range, but is preferably 0.2 to 20 parts by weight, more preferably 0.5 to 10 parts by weight, particularly preferably 100 parts by weight of the binder resin. 1.0 to 8.0 parts by weight.

  As the charge control agent, those for positive charge control and negative charge control commonly used in this field can be used. Examples of the charge control agent for controlling positive charge include nigrosine dyes, basic dyes, quaternary ammonium salts, quaternary phosphonium salts, aminopyrines, pyrimidine compounds, polynuclear polyamino compounds, aminosilanes, nigrosine dyes and derivatives thereof, and triphenylmethane. Derivatives, guanidine salts, amidine salts and the like can be mentioned. Charge control agents for controlling negative charges include oil-soluble dyes such as oil black and spiron black, metal-containing azo compounds, azo complex dyes, metal salts of naphthenic acid, salicylic acid and derivatives thereof, and metal salts (metal is Chromium, zinc, zirconium, etc.), fatty acid soaps, long-chain alkyl carboxylates, resin acid soaps, and the like. The charge control agent can be used alone or in combination of two or more as required. The amount of the charge control agent used is not particularly limited and can be appropriately selected from a wide range. The charge control agent may be contained in the core particles, or may be used by being mixed in a coating layer that becomes an antireflection film in the coating step described later. When the charge control agent is contained in the core particles, the charge control agent is preferably 0.5 to 3 parts by weight with respect to 100 parts by weight of the binder resin.

  When the absorption rate by the toner at the laser wavelength used for laser fixing is low, an infrared absorber may be added to the toner particles. As the infrared absorber, substituted benzenedithiolnickel complexes, phthalocyanines, anthraquinones, bisdithiobenzylnickel complexes and the like can be used.

The core particles can be manufactured according to a general toner manufacturing method. As a general toner production method, for example, a dry method such as a pulverization method, a suspension polymerization method, an emulsion aggregation method, a dispersion polymerization method, a dissolution suspension method, and a wet emulsion method such as a melt emulsification method are used. A method for producing core particles by the pulverization method will be described below.
In the pulverization method, a toner composition containing a binder resin, a colorant, and other toner additive components is dry-mixed with a mixer and then melt-kneaded with a kneader. The kneaded material obtained by melt kneading is cooled and solidified, and the solidified material is pulverized by a pulverizer. Thereafter, particle size adjustment such as classification is performed as necessary to obtain core particles.

  Known mixers can be used, such as 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.), etc. Henschel type mixing device, Ong mill (trade name, manufactured by Hosokawa Micron Corporation), hybridization system (trade name, manufactured by Nara Machinery Co., Ltd.), Cosmo system (trade name, manufactured by Kawasaki Heavy Industries, Ltd.), and the like.

  A well-known thing can be used also as a kneading machine, for example, common kneading machines, such as a twin-screw extruder, a 3 roll, a laboratory blast mill, can be used. More specifically, for example, uniaxial or biaxial extruders such as TEM100B (trade name, manufactured by Toshiba Machine Co., Ltd.), PCM-65 / 87, and PCM-30 (all of which are trade names, manufactured by Ikegai Co., Ltd.). And an open roll type kneader such as Needex (trade name, manufactured by Mitsui Mining Co., Ltd.).

  Synthetic resin additives such as colorants may be used as a master batch to uniformly disperse the synthetic resin additive in the kneaded product. Two or more additives for synthetic resin may be used as composite particles. The composite particles can be produced, for example, by adding an appropriate amount of water, lower alcohol or the like to two or more additives for synthetic resin, granulating with a general granulator such as a high speed mill, and drying. Masterbatch and composite particles are mixed into the powder mixture during dry mixing.

<Shell particle and adhesion aid preparation process>
In the shell particle and adhesion aid preparation step, shell particles containing at least a resin are produced. Also, an adhesion aid that increases the adhesion between the core particles and the shell particles is prepared.
The resin that can be used for the shell particles is not particularly limited.

Such shell particles can be obtained, for example, by emulsifying and dispersing the shell particle raw material with a homogenizer or the like. It can also be obtained by monomer polymerization.
The adhesion aid prepared in this step is a liquid that can improve the wettability of the shell particles to the core particles. The adhesion aid is preferably a liquid that does not dissolve the core particles. Further, since the adhesion aid needs to be removed after coating of the shell particles, it is preferably a liquid that easily evaporates.

As an adhesion assistant satisfying these conditions, for example, it is preferable to contain at least one kind of water and lower alcohol. Examples of the lower alcohol include methanol, ethanol, propanol and the like. By using a material containing these as an adhesion aid, the wettability of the shell particles to the core particles can be increased, and it is easier to form a coating layer containing the shell particles on the entire surface or most of the core particles. Become. Moreover, the drying time for removing the adhesion aid can be further shortened.
Further, the adhesion aid is not limited to those exemplified above, for example, alcohols such as butanol, diethylene glycol and glycerin, ketones such as acetone and methyl ethyl ketone, esters such as methyl acetate and ethyl acetate, and the like are used. May be.

<Coating process>
In the coating process, shell particles are adhered to the core particles and fused using the adjusted adhesion aid. As a result, the core particles are coated with the shell particles to form a coating layer.
The adhesion aid increases the adhesion between the core particles and the shell particles by improving the wettability of the shell particles to the core particles. By using an adhesion aid, it becomes easy to form a coating layer containing shell particles over the entire surface or most of the core particles. Such a coating layer is difficult to be detached from the core particles due to the presence of shell particles fused to the core particles. Accordingly, it is possible to prevent the coating layer from being detached and the properties of the toner from being changed by long-term use.

  The coating process is performed using, for example, a surface modifying apparatus. The surface modification apparatus is an apparatus that includes a container that accommodates core particles and shell particles therein, and a spraying means that sprays an adhesion aid inside the container. Further, in the present embodiment, the surface modification apparatus includes a stirring unit that stirs the core particles in the container.

  A closed container can be used as a container for containing the core particles and the shell particles. The spraying means mixes the adhesion auxiliary agent storage part for storing the adhesion auxiliary agent and / or the carrier gas storage part for storing the carrier gas and the adhesion auxiliary agent and / or carrier gas, and stores the resulting mixture in the container A liquid spraying unit that sprays toward the core particles and sprays droplets of the deposition aid onto the core particles. Compressed air or the like can be used as the carrier gas. Commercially available products can be used as the liquid spray unit. For example, a two-fluid nozzle (trade name: HM-6 type, a sticking auxiliary agent is passed through a tube pump (trade name: MP-1000A, manufactured by Tokyo Rika Kikai Co., Ltd.) A product connected so as to be quantitatively fed to Fuso Seiki Co., Ltd. can be used. As the stirring means, a stirring rotor or the like capable of imparting mechanical and thermal energy mainly composed of impact force to the core particles is used.

  Commercially available products can be used as the container equipped with the stirring means. 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, Okada Seiko) Henschel type mixing equipment such as Co., Ltd., Ongmill (trade name, manufactured by Hosokawa Micron Corporation), Hybridization system (trade name, manufactured by Nara Machinery Co., Ltd.), Cosmo System (trade name, manufactured by Kawasaki Heavy Industries, Ltd.) Etc. By installing the liquid spray unit in the container of such a mixer, this mixer can be used as the surface modification device of the present embodiment.

  The core particles are coated with shell particles as follows. First, core particles and shell particles are put into a container, and an adhesion assistant is sprayed inside the container in a state where the core particles and the shell particles are stirred by the stirring means. The core particles and the shell particles are sprayed with an adhesion aid and applied with thermal energy by stirring, so that their surfaces swell and soften, and wettability is improved. A mechanical impact force by the stirring means is added to the shell particles so that the shell particles adhere to the surface of the core particles, and a part of the shell particles is fused with at least one of the core particles and the adjacent shell particles. As a result, the shell particles can be adhered to the entire surface of the core particles, and the shell particles can be fused to the entire surface of the core particles.

  The adhesion aid is preferably sprayed with the core particles floating in the container. When the mixture of the shell particles and the adhesion assistant is sprayed in a state where the core particles are suspended in the container, the time for the core particles sprayed with the adhesion assistant to be brought into contact with each other can be shortened. As a result, toner aggregation during toner production can be prevented and generation of coarse particles can be prevented, so that a toner having a uniform particle diameter can be obtained. The state in which the core particles float in the container can be realized by, for example, stirring by a stirring means or supply of compressed air having a sufficient strength to spray the adhesion aid.

  The amount of the adhesion aid is not particularly limited, but it is preferably an amount that wets the entire surface of the core particles. The amount of adhesion aid used is determined by the amount of core particles used. Moreover, the amount of the adhesion assistant can be adjusted by the spraying time by the spraying means, the number of spraying, and the like. Therefore, the spraying amount per unit time by the spraying means is set according to the core average particle diameter, the use ratio of the core particle and the shell particle, the material of the core particle and the material of the shell particle, etc., for example, among the shell particles in the container When most of the particles adhere to the core particles, the spraying of the deposition aid by the spraying means may be terminated.

  The coating of the shell particles onto the core particles by such a surface modification apparatus is performed as follows. First, core particles are put into a container, and a mixture of an adhesion aid and shell particles is sprayed inside the container in a state where the core particles are stirred by the stirring means. The surface of the core particles is sprayed with an adhesion assistant and applied with thermal energy by stirring, whereby the surface thereof swells and softens, and the wettability is improved. Further, the shell particles are mixed together with the adhesion aid, and after being sprayed inside the container, the shell particles are agitated and applied with thermal energy, and the surface thereof is swollen and softened like the core particles. A mechanical impact force by the stirring means is added to the shell particles so that the shell particles adhere to the surface of the core particles, and a part of the shell particles is fused with at least one of the core particles and the adjacent shell particles. As a result, the shell particles can be adhered to the entire surface of the core particles, and the shell particles can be fused to the entire surface of the core particles.

  When spraying the mixture of the adhesion aid and the shell particles, the adhesion aid is preferably used in a ratio of 1 part by weight or more and 99 parts by weight or less with respect to 1 part by weight of the shell particles. The coating liquid which is a mixture of the adhesion aid and the shell particles is prepared in the shell particle and adhesion aid preparation step. When the mixture of the shell particles and the adhesion aid is sprayed from the same spraying means, the mixture of the shell particles and the adhesion aid at the above ratio is used, thereby improving the wettability of the shell particles to the core particles. It can be sufficiently increased and the time for removing the adhesion aid can be shortened. Further, the viscosity of the mixture is suitable, and the spraying of the mixture by the spraying means is easy. If the adhesion aid is less than 1 part by weight, the viscosity of the mixture becomes too high and the nozzle holes of the spray unit may be clogged. If the adhesion aid exceeds 99 parts by weight, the content of the adhesion aid will be too high, and the time for removing the adhesion aid will be too long.

  The amount of the mixture of the shell particles and the adhesion aid is not particularly limited, but it is necessary to include an amount of the shell particles that can cover the entire surface of the core particles. The preferred amount of shell particles that can cover the entire surface of the core particles is 1 to 30 parts by weight with respect to 100 parts by weight of the core particles as described above. It is determined according to the content rate of the shell particles therein.

When the coating of the shell particles on the entire surface of the core particles is completed, the adhesion aid is removed. The removal of the adhesion aid is performed by vaporizing the adhesion aid with a dryer, for example. For removal of the adhesion aid, for example, a commonly used dryer such as a hot air receiving dryer, a conductive heat transfer dryer, a freeze dryer, or the like is used, but it can also be performed by natural drying.
In the case of a coating layer having a two-layer structure, two types of shell particles can be prepared and the coating process can be performed twice.

  The toner of the present invention may contain external additives that perform functions such as powder flowability improvement, triboelectric chargeability improvement, heat resistance, long-term storage stability improvement, cleaning property improvement, and photoreceptor surface wear property control. . Known external additives can be used, and examples thereof include silica fine powder, titanium oxide fine powder, and alumina fine powder. These are preferably surface-treated with a silicon resin, a silane coupling agent or the like. One type of external additive can be used alone, or two or more types can be used in combination. The external additive is added in an amount of 0.1 with respect to 100 parts by weight of the toner in consideration of the charge amount necessary for the toner, the influence of the external additive on the abrasion of the photoreceptor and the environmental characteristics of the toner. It is preferable that it is -10 weight part.

  The toner of the present invention can be used as a one-component developer or a two-component developer. When used as a one-component developer, the toner is used only without using a carrier. When used as a one-component developer, a blade and a fur brush are used, and the toner is conveyed by friction charging with a developing sleeve to adhere the toner onto the sleeve, thereby forming an image. When used as a two-component developer, the toner of the present invention is used with a carrier.

  Further, in the case of the image forming apparatus in which the color toners are superposed and fixed as shown in FIG. 1, only the toner of the color to be formed last may be the toner with an antireflection film. Since the lower toner layer is not directly irradiated with laser light, normal toner may be used. When energy is most needed for fixing, the toner of the color that will be formed last is always on, so the antireflection film is attached to the toner of the color that is formed last, and the laser It is effective to increase the light use efficiency.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2 ... Image forming unit, 3 ... Photosensitive drum, 4 ... Charging apparatus, 5 ... Exposure apparatus, 6 ... Developing apparatus, 7 ... Primary transfer apparatus, 8 ... Drum cleaner, 9 ... Intermediate transfer belt 10 DESCRIPTION OF SYMBOLS ... Paper accommodating part, 11 ... Roller pair, 12 ... Secondary transfer device, 13 ... Fixing device, 13a ... Laser light source, 13b ... Endless belt, 13c ... Rotating polygon mirror, 14 ... Discharge roller.

Claims (6)

A toner used in an image forming apparatus employing a laser fixing method,
A toner comprising an antireflection film for laser light used for fixing formed on the surface of core particles containing at least a binder resin and a coloring material.   The toner according to claim 1, wherein the antireflection film comprises a single layer film formed of a material having a refractive index of 1.3 to 1.4.   The toner according to claim 1, wherein the antireflection film comprises a two-layer film.   The toner according to claim 1, wherein the antireflection film is formed by fusing resin particles.   An image forming apparatus using the toner according to claim 1. To form color images,
The image forming apparatus according to claim 5, wherein the toner is used for at least a color to be superimposed last to form the color image.

Images