JP5332581B2 - Image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming method for obtaining high image quality in a printed matter formed while saving energy, and an image obtained thereby. <P>SOLUTION: The image forming method is a method through a toner holding treating process for holding a toner image formed of a toner particle containing at least a resin, onto a toner holding material layer formed on an image support base material, and a relational expression (1):1&ge;B/A&ge;0.9, and a relational expression (2):1.4&ge;C/D&ge;0.7 are satisfied when A is taken as a particle shape degree expressed by (the minimum diameter of a projection image/the maximum diameter of the projection image), as to the toner particle subjected to the holding treating process, B is taken as a particle shape degree expressed by (the minimum diameter of a projection image/the maximum diameter of the projection image), as to the toner particle after holding-treated, C is taken as a refractive index of the resin constituting the toner particle, and D as a refractive index of a material constituting the toner holding material layer. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

The present invention relates to an electrophotographic image forming method , for example.

  Conventionally, as a method for fixing toner to an image support in an electrophotographic image forming method in which toner is electrostatically developed to form an image, a method using a heat pressure roller, flash light, or the like has been used. (For example, see Patent Document 1 and Patent Document 2.)

  However, since these methods are to fix the toner by fixing it to the image support by deforming the toner, a large amount of energy is required, which is not preferable from the viewpoint of energy saving.

  As an energy-saving fixing method, there has been proposed a method of fixing only by applying pressure without using heat (see, for example, Patent Document 3). There has also been proposed a method in which a concave portion is provided on the surface of an image support, and toner particles are electrostatically adhered and fixed therein (see, for example, Patent Document 4).

  However, depending on the method using only the applied pressure, there is a problem that an image formed without being sufficiently fixed to the image support becomes low quality. In addition, depending on the method of providing the concave portion, there is a problem that the toner particles are inevitably detached from the concave portion and are contaminated by the detached toner.

  Furthermore, depending on the image forming methods disclosed in Patent Documents 1 to 4, an image in which toner is present in the image portion and toner is not present in the non-image portion is formed. There is a problem that a high level of image quality cannot be obtained due to the formation of a minute step between the portion and the non-image portion.

  In order to solve such a problem of the level difference between the image portion and the non-image portion, a method in which toner is also present in the non-image portion has been proposed (see, for example, Patent Document 5). In addition, the image support is configured to have a resin layer on the surface, and the toner and the resin layer of the image support are melted by heating and pressure during fixing to fix the toner to the surface of the image support. There has also been proposed a method of making it (see, for example, Patent Document 6).

However, even with the method disclosed in Patent Document 5, a gap is generated between the toners, and the formed printed matter has a high white turbidity, and a sufficient color depth cannot be obtained. Also, it cannot be said that sufficient image quality is obtained even by the method of melting the resin layer and the toner disclosed in Patent Document 6.
As described above, conventionally, there has been no image forming method capable of obtaining high image quality in an image formed while achieving energy saving.

JP 2004-101648 A JP-A-5-297626 JP-A-6-242627 Japanese Patent No. 4085505 JP-A-9-197858 JP-A-11-160905

The present invention has been made based on the above circumstances, and an object of the present invention is to provide an image forming method capable of obtaining high image quality in a printed material formed while achieving energy saving. .

The image forming method of the present invention is a toner image holding method in which a toner image formed by toner particles containing at least a resin is held by applying an external force to a toner holding material layer formed on an image supporting substrate. An image forming method through a processing step,
The particle shape degree represented by (minimum diameter of projection image / maximum diameter of projection image) of the toner particles subjected to the holding treatment step is A, and (minimum diameter of projection image / The following relational expression (1) is satisfied when the particle shape degree of the toner particles represented by the maximum diameter of the projected image is B,
The refractive index of the resin constituting the toner particles C, and the refractive index of the material constituting the toner holding layer meets the following equation (2) is D, the external force is applied to the toner holding layer It is only pressure, and the material constituting the toner holding material layer has thixotropy .
Relational expression (1): 1 ≧ B / A ≧ 0.9
Relational expression (2): 1.4 ≧ C / D ≧ 0.7

  In the image forming method of the present invention, the toner image holding treatment step includes a state in which the toner image is held after the toner particles are embedded in the toner holding material layer laminated on the intermediate transfer member by an external force. The toner holding material layer can be superposed on the image supporting substrate.

  According to the image forming method of the present invention, basically, a toner image can be fixed to an image support without applying heat, so that energy saving is achieved, and the image support is a toner holding material. A toner that forms a toner image in which the surface of a printed matter obtained by having a layer is in a highly uniform state, a difference in height level between an image portion and a non-image portion is suppressed to a small level Because the difference between the refractive index of the resin of the particles and the refractive index of the material constituting the toner holding material layer is within a specific small range, an image portion having a low white turbidity and a sufficient color depth is formed, and thus high. A printed matter having image quality can be obtained.

  Hereinafter, the image forming method and the image of the present invention will be described in detail.

<First Embodiment>
In the image forming method of the present invention, a toner image holding treatment step of holding a toner image formed electrostatically by toner particles containing at least a resin on a toner holding material layer formed on an image supporting substrate. It is a method that goes through.
Specifically, in the toner image holding processing step of the image forming method of this example, as shown in FIGS. 1A and 1B, the toner holding material layer 15 formed on the image supporting substrate 11 is used. In addition, a process of directly burying the toner image T with toner particles by an external force is performed. The toner image T is fixed by this toner image holding process.
The external force applied for burying the toner particles of the toner image T can be a pressing force having a magnitude of 1.00 × 10 ^{3 to} 1.00 × 10 ⁸ Pa.
In the toner image T fixed on the toner holding material layer 15, at least all of the toner particles constituting the toner image T are buried by 50% by volume or more as shown in FIG. As shown in FIG. 4, it is preferable that all the toner particles are respectively embedded by 100% by volume.

In the image forming method of the present invention, when the particle shape degree of the toner particles used in the toner image holding treatment step is A and the particle shape degree of the toner particles after the toner image holding treatment is B, the following relationship is established. When satisfying the formula (1), the refractive index of the resin constituting the toner particles (hereinafter also referred to as “toner resin”) is C, and the refractive index of the material constituting the toner holding material layer 15 is D, The relational expression (2) is satisfied.
Relational expression (1): 1 ≧ B / A ≧ 0.9
Relational expression (2): 1.4 ≧ C / D ≧ 0.7
Here, the particle shape degree of the toner particles is expressed by the minimum diameter of the projected image / the maximum diameter of the projected image.

  When (B / A) indicating the degree of change in the particle shape before and after the toner image holding process is in the range of the above relational expression (1), it is possible to form a print with high image quality with a small amount of energy. . On the other hand, when (B / A) indicating the degree of change in particle shape is less than 0.9, a large amount of energy is required to obtain a printed product, which is not preferable because of a large environmental load.

Specifically, the particle shape degree A used in the toner image holding treatment step is determined by peeling off the toner image T electrostatically formed on the photosensitive member K (see FIG. 1) and scanning electron microscope ( SEM) “JSM-7401F” (manufactured by JEOL Ltd.), and an image with a magnification of 2,000 times is taken into a “Luzex image analyzer” (manufactured by Nireco). by measuring the maximum diameter and the minimum diameter of the projected image, the minimum diameter determined particle shape index was divided by the maximum diameter, and calculates the average value of the particle shape of about 100 toner particles, determined It is what

  Specifically, the particle shape degree A subjected to this toner image holding treatment step is preferably 0.40 to 1.00, more preferably 0.60 to 1.00.

Further, the particle shape degree B of the toner particles after the toner image holding treatment is specifically determined by using a transmission electron microscope (TEM) “JEM-1400” of a cross section of the printed matter P obtained by this image forming method. (Manufactured by JEOL Ltd.), an image with a magnification of 2,000 times is taken into a “Luzex image analyzer” (manufactured by Nireco), and for each toner particle, the maximum diameter and measuring the diameter, the minimum diameter determined particle shape index was divided by the maximum diameter, by calculating the average value of the particle shape of about 100 toner particles are those obtained.

  Further, when the ratio of the refractive index C of the toner resin and the refractive index D of the material constituting the toner holding material layer 15 (hereinafter also referred to as “refractive index ratio”) is in the range of the above relational expression (2), As a result of the light scattering being suppressed, the white turbidity of the obtained image portion Q is low, and a sufficient color depth is obtained. Therefore, the image quality of the obtained printed matter P is high. On the other hand, if the refractive index ratio deviates from the range of the above relational expression (2), and the refractive index ratio is excessive, light scattering occurs greatly. As a result, the obtained image portion Q becomes white turbid and sufficient color is obtained. Depth cannot be obtained, and therefore the image quality of the obtained printed matter P is low.

(Image support)
The image support 10 used in the image forming method of the present invention is obtained by forming a toner holding material layer 15 on an image support base 11.
As the image supporting substrate 11, an appropriate one can be used. For example, plain paper from thin paper to thick paper, high-quality paper, coated printing paper such as art paper or coated paper, commercially available Japanese paper, Examples include postcard paper, polypropylene synthetic paper, polyethylene terephthalate (PET) film, polyethylene naphthalate (PEN) film, polyimide film, and cloth.

In the present invention, it is preferable that the toner holding material layer 15 does not have fluidity in a state where an external force is not applied, and develops a fluid state when the external force is applied. Specifically, it can be made of a material having a thixotropic property that is, for example, a gel in a normal state and changes into a sol when an external force is applied.
As a material constituting the toner holding material layer 15, the refractive index satisfies the above relational expression (2) in relation to the refractive index of the toner resin, is incompatible with the toner resin, and has toner particles by an external force. The degree of change (B / A) in the degree of particle shape when the material is buried is also a level of fluidity (hereinafter also referred to as “specific fluidity”) that can be within the range of the relational expression (1). ) Can be selected as appropriate.
The specific fluidity specifically refers to a material having a penetration of 30 or more measured according to JIS K2207 in a state where an external force for embedding toner particles is applied. As a material constituting the holding material layer 15, a material having a higher penetration is preferable.
By using a material having such a specific fluidity, the toner image T formed by electrostatically adhering each toner particle on the photoconductor K is maintained in the electrostatic charge in each toner particle. The toner holding material layer 15 can be buried in the state.

  The external force for burying the toner particles in the toner holding material layer 15 is applied by a method capable of setting the degree of change (B / A) in the particle shape degree of the toner particles within the range of the relational expression (1). For example, an electrostatic force applied by an appropriate transfer device, a pressing force with which the image support 10 is pressed against the toner image T on the photosensitive member K, and a combination thereof may be mentioned.

  Further, the material constituting the toner holding material layer 15 is preferably a material having high affinity with the toner particles.

Examples of the material constituting the toner holding material layer 15 include silicone-based, acrylic-based, vinyl-based, urethane-based resins, elastomers, rubbers, gels and sols thereof with organic solvents and oils, water-based emulsions and water-soluble materials thereof. And high molecular weight polymers and gels or sols of these and aqueous solvents can be used.
Specifically, the silicone resins include dimethylsiloxane, diphenylsiloxane, methylvinylsiloxane, methylphenylsiloxane, fluorosiloxane, trifluorosiloxane, trifluoropropylsiloxane, chloromethylsiloxane, cyanoethylsiloxane, polyether siloxane, fluoro Examples thereof include polyether siloxane and aminosiloxane.
Examples of acrylic resins include 2-ethylhexyl acrylate and n-butyl acrylate, methyl acrylate, ethyl acrylate, methyl methacrylate, acrylic acid, methacrylic acid, itaconic acid, acrylamide derivatives, hydroxyethyl acrylate, and glycidyl acrylate. Examples include polymers.
Examples of vinyl resins include polyvinyl acetate, ethylene-vinyl acetate copolymer, acrylic-vinyl acetate copolymer, polyvinyl acetal, polyvinyl butyral, phenol-vinyl butyral copolymer, polyvinyl pyrrolidone, and polyvinyl chloride. Is mentioned.
Examples of urethane resins include polyurethane prepolymers obtained by reacting polyols and polyisocyanates. Examples of polyols include 1,2-polybutadiene polyol, 1,4-polybutadiene polyol, and poly (pentadiene / butadiene) polyol. , Poly (butadiene / styrene) polyol, poly (butadiene / acrylonitrile) polyol, etc., and polyisocyanates include diphenylmethane diisocyanate, tolylene diisocyanate, naphthalene diisocyanate, polymethylene polyphenyl isocyanate, xylylene diisocyanate, lysine diisocyanate, hexamethylene. Diisocyanate, isophorone diisocyanate, methylene bis (cyclohexyl isocyanate), etc.
Further, as water-soluble polymers, natural polymer polysaccharides such as xanthan gum, carrageenan, pullulan, furseleran, curdlan, gelatin, collagen, etc .; sodium alginate, calcium alginate natural low molecular polysaccharide; polyacrylic acid; sodium polyacrylate A mixture of polyvinyl alcohol and the like with a solvent such as water, methyl alcohol, ethyl alcohol, ethylene glycol, propylene glycol, polyethylene glycol, and glycerin;

The refractive index of the material constituting the toner holding material layer 15 can be measured by various known methods, and the refractive index of the material constituting the toner holding material layer 15 in the present invention is separately determined. A thin film made only of the material constituting the material 15 is prepared, and this thin film is measured with an Abbe refractometer.
Specific examples of the refractive index of the material constituting the toner holding material layer 15 include 1.53 for gelatin, 1.51 for polyvinyl alcohol, 1.51 for sodium polyacrylate, and 1.1 for fluorine-modified acrylic resin. 34, the silicone gel is 1.41, and the fluorine-modified silicone gel is 1.34.
The thickness of the toner holding material layer 15 is set in relation to the thickness of the toner image T to be held, for example, 1 to 500 μm.

In the image forming method of the present invention, when the toner holding material layer 15 has adhesiveness even when no external force is applied, the surface of the toner holding material layer 15 is provided with a viewpoint of storability and writeability. In addition, a surface protective layer may be provided.
The surface protective layer may be formed by applying a material having the same composition as the material constituting the surface of the toner holding material layer 15 and curing only the coated layer with light, heat, steam, or the like. 15 may be provided by a method of applying a material having a composition different from that of the material constituting the surface. Examples of other compositions include organic solvent-soluble resins such as polystyrene resins, acrylic resins, and polyester resins, photocuring agents, thermosetting agents, and moisture curing agents.
Moreover, as a surface protective layer, it can also provide by coat | covering sheets, such as a polyethylene terephthalate (PET), a polyethylene naphthalate (PEN), a polypropylene (PP), a polystyrene (PS).

[Toner particles]
The toner particles used in the image forming method of the present invention contain at least a resin, and may further contain a colorant, a charge control agent, a magnetic powder, a release agent and the like as desired. Such an aggregate of toner particles is hereinafter referred to as toner.
The toner particles before use will be described below.

[Method for producing toner particles]
A method for producing such toner particles is not particularly limited, and a pulverization method, an emulsion dispersion method, a suspension polymerization method, a dispersion polymerization method, an emulsion polymerization method, an emulsion polymerization aggregation method, and other known methods. And so on.

[Toner resin]
The toner resin needs to be selected so as to satisfy the above relational expression (2) in the relationship of the refractive index ratio with the material constituting the toner holding material layer 15. For example, the refractive index C is 1.30-1. It is preferable to select one that is 70, and more preferably 1.40 to 1.60.

  The refractive index of the toner resin can be measured by various known methods. For the refractive index of the toner resin in the present invention, a thin film made only of the toner resin is prepared separately, and this thin film is used as an Abbe refractometer. Measured value.

  When the toner particles are produced by a pulverization method, an emulsification dispersion method, etc., the resin constituting the toner is a styrene resin, a (meth) acrylic resin, a styrene- (meth) acrylic copolymer resin, an olefinic resin. Various known resins such as vinyl resins such as resins, polyester resins, polyamide resins, polycarbonate resins, polyethers, polyvinyl acetate resins, polysulfones, epoxy resins, polyurethane resins and urea resins can be used. . These can be used alone or in combination of two or more.

  On the other hand, when the toner particles are produced by a suspension polymerization method, a dispersion polymerization method, an emulsion polymerization method, an emulsion polymerization aggregation method or the like, as a polymerizable monomer for obtaining a resin constituting the toner, for example, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p Styrene or styrene derivatives such as tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene; methyl methacrylate , Ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate Methacrylic acid ester derivatives such as t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate; methyl acrylate , Ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, phenyl acrylate, etc. Acrylic ester derivatives; Olefins such as ethylene, propylene, isobutylene; Vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide, vinyl fluoride, vinylidene fluoride Vinyl esters such as vinyl propionate, vinyl acetate and vinyl benzoate; vinyl ethers such as vinyl methyl ether and vinyl ethyl ether; vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and vinyl hexyl ketone; N-vinyl N-vinyl compounds such as carbazole, N-vinylindole and N-vinylpyrrolidone; vinyl compounds such as vinylnaphthalene and vinylpyridine; vinyl-based compounds such as acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, A polymer can be mentioned. These vinyl monomers can be used alone or in combination of two or more.

Moreover, it is preferable to use combining what has an ionic dissociation group as a polymerizable monomer. The polymerizable monomer having an ionic dissociation group has, for example, a substituent such as a carboxyl group, a sulfonic acid group, and a phosphoric acid group as a constituent group, and specifically includes acrylic acid, methacrylic acid, maleic acid. Acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl ester, itaconic acid monoalkyl ester, styrene sulfonic acid, allyl sulfosuccinic acid, 2-acrylamido-2-methylpropane sulfonic acid, acid phosphooxyethyl methacrylate And 3-chloro-2-acid phosphooxypropyl methacrylate.
Furthermore, as a polymerizable monomer, divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, neopentyl A binder resin having a crosslinked structure can also be obtained using a polyfunctional vinyl such as glycol diacrylate.

[Colorant]
When the toner particles are configured to contain a colorant, organic or inorganic pigments of various colors as exemplified below can be used as the colorant.
That is, examples of black pigments include carbon black, copper oxide, manganese dioxide, aniline black, activated carbon, nonmagnetic ferrite, magnetic ferrite, and magnetite.
Yellow pigments include yellow 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, Benzidine Yellow GR, Examples include quinoline yellow lake, permanent yellow NCG, and tartrazine lake.
Examples of the orange pigment include red chrome yellow, molybdenum orange, permanent orange GTR, pyrazolone orange, vulcan orange, indanthrene brilliant orange RK, benzidine orange G, and indanthrene brilliant orange GK.
Red pigments include quinacridone, 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, brilliant carmine 6B, eosin lake, b over Daminreki B, alizarin lake, etc. Brilliant Carmine 3B.
Examples of purple pigments include manganese purple, fast violet B, and methyl violet lake.
The blue pigment, iron blue, cobalt blue, alkali blue lake, Victor Li Aburureki, metal phthalocyanine blue, metal-free phthalocyanine blue, partially chlorinated phthalocyanine blue, fast sky blue, and the like indanthrene blue BC.
Examples of the green pigment include chrome green, chromium oxide, pigment green B, micalite green lake, final yellow green G, and the like.
Examples of white pigments include zinc white, titanium oxide, antimony white, and zinc sulfide.
Examples of extender pigments include barite powder, barium carbonate, clay, silica, white carbon, talc, and alumina white.
These pigments can be used alone or in combination of two or more.

  The addition amount of the colorant is preferably 0.5 to 20 parts by mass, more preferably 2 to 10 parts by mass with respect to 100 parts by mass of the toner.

[Magnetic powder]
When the toner particles are configured to contain magnetic powder, for example, magnetite, γ-hematite, or various ferrites can be used as the magnetic powder.
The addition amount of the magnetic powder is preferably 10 to 500 parts by mass, more preferably 20 to 200 parts by mass with respect to 100 parts by mass of the toner.

[Charge control agent]
Further, in the case where the toner particles are configured to contain a charge control agent, the charge control agent is not particularly limited as long as it is a substance that can give positive or negative charge by frictional charging, and there are various known ones. Can be used. Specifically, as the positive charge control agent, for example, a nigrosine dye such as “Nigrosine Base EX” (manufactured by Orient Chemical Industries), “quaternary ammonium salt P-51” (manufactured by Orient Chemical Industries), “ Quaternary ammonium salts such as “Copy Charge PX VP435” (manufactured by Hoechst Japan), alkoxylated amines, alkylamides, molybdate chelate pigments, and imidazole compounds such as “PLZ1001” (manufactured by Shikoku Kasei Kogyo Co., Ltd.) Examples of the negative charge control agent include “Bontron S-22” (manufactured by Orient Chemical Industries), “Bontron S-34” (manufactured by Orient Chemical Industries), and “Bontron E-81” (Orient Chemical Industries). Manufactured by Co., Ltd.), "Bontron E-84" (manufactured by Orient Chemical Industry Co., Ltd.), "Spiron Black TRH" Metal complexes such as (Hodogaya Chemical Industries, Ltd.), thioindigo pigments, quaternary ammonium salts such as “Copy Charge NX VP434” (Hoechst Japan), “Bontron E-89” (Orient Chemical Industries) And boron compounds such as “LR147” (manufactured by Nippon Carlit), fluorine compounds such as magnesium fluoride and carbon fluoride, and the like. In addition to the metal complexes used as negative charge control agents, oxycarboxylic acid metal complexes, dicarboxylic acid metal complexes, amino acid metal complexes, diketone metal complexes, diamine metal complexes, azo group-containing benzene-benzene derivatives Those having various structures such as a skeletal metal body and an azo group-containing benzene-naphthalene derivative skeleton metal complex can be used.
As described above, the toner particles are configured to contain the charge control agent, whereby the chargeability of the toner is improved.

  The addition amount of the charge control agent is preferably 0.01 to 30 parts by mass, more preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the toner.

〔Release agent〕
Further, when the toner particles are configured to contain a release agent, various known waxes can be used as the release agent. As the wax, it is particularly preferable to use a polyolefin-based wax such as low molecular weight polypropylene, polyethylene, or oxidized polypropylene or polyethylene.
As described above, the toner particles are configured to contain a release agent, whereby the toner fixing property is improved.

  The addition amount of the release agent is preferably 0.1 to 30 parts by mass, more preferably 1 to 10 parts by mass with respect to 100 parts by mass of the toner.

[Particle size of toner particles]
The toner particles preferably have a volume-based median diameter of 3 to 8 μm. When the volume-based median diameter is 3 to 8 μm, the reproducibility of fine lines and high image quality of photographic images can be achieved, and the amount of toner consumption can be reduced compared to the case of using a large particle size toner. be able to.

  The volume-based median diameter of the toner is measured and calculated using a measuring device in which a computer system equipped with data processing software “Software V3.51” is connected to “Coulter Multisizer 3” (manufactured by Beckman Coulter). Is. Specifically, 0.02 g of toner is added to 20 mL of a surfactant solution (for example, a surfactant solution in which a neutral detergent containing a surfactant component is diluted 10-fold with pure water for the purpose of dispersing the toner). Then, ultrasonic dispersion was performed for 1 minute to prepare a toner dispersion, and this toner dispersion was placed in a beaker containing “ISOTON II” (manufactured by Beckman Coulter) in a sample stand. Pipette until the indicated concentration is 8%. Here, a reproducible measurement value can be obtained by setting the concentration range. In the measurement apparatus, the measurement particle count is 25000, the aperture diameter is 50 μm, the frequency value is calculated by dividing the measurement range of 1 to 30 μm into 256, and the volume integrated fraction is 50 % Particle diameter is defined as the volume-based median diameter.

[Average circularity of toner particles]
The above toner particles preferably have an average circularity represented by the following formula (S) of 0.700 to 1.000, more preferably 0.850 to 1.000.
Formula (S): Average circularity = circumference of circle obtained from equivalent circle diameter / perimeter of particle projection image

(External additive)
The above toner particles can constitute the toner as it is, but in order to improve fluidity, chargeability, cleaning properties, etc., the toner particles are provided with a so-called post-treatment agent, a fluidizing agent and a cleaning aid. The toner may be constituted by adding external additives such as the above.

As the post-treatment agent, for example, inorganic oxide fine particles composed of silica fine particles, alumina fine particles, titanium oxide fine particles, etc., inorganic stearate compound fine particles such as aluminum stearate fine particles, zinc stearate fine particles, or strontium titanate, titanium Inorganic titanic acid compound fine particles such as zinc acid are listed. These can be used individually by 1 type or in combination of 2 or more types.
These inorganic fine particles are preferably subjected to surface treatment with a silane coupling agent, a titanium coupling agent, a higher fatty acid, silicone oil or the like in order to improve heat-resistant storage stability and environmental stability.

  The total amount of these various external additives added is 0.05 to 5 parts by mass, preferably 0.1 to 3 parts by mass with respect to 100 parts by mass of the toner. In addition, various external additives may be used in combination.

(Developer)
The toner as described above can be used as a magnetic or non-magnetic one-component developer, but may be mixed with a carrier and used as a two-component developer. When the toner is used as a one-component developer, a non-magnetic one-component developer or a magnetic one-component developer containing about 0.1 to 0.5 μm of magnetic particles in the toner can be used. Can also be used. Further, when the toner is used as a two-component developer, the carrier may be a magnetic material made of a conventionally known material such as a metal such as iron, ferrite, or magnetite, or an alloy of such a metal with a metal such as aluminum or lead. Particles can be used, and ferrite particles are particularly preferable. As the carrier, a coated carrier in which the surface of magnetic particles is coated with a coating agent such as a resin, a resin dispersion type carrier in which magnetic fine powder is dispersed in a binder resin, or the like may be used.

  According to the above image forming method, basically, the toner image T can be fixed to the image support 10 without applying heat, so that energy saving is achieved. Since the surface of the printed matter P obtained by having the holding material layer 15 is in a highly uniform state, there is no difference in the height level between the image portion Q and the non-image portion, and the toner image T Since the difference between the refractive index of the toner resin forming the toner and the refractive index of the material constituting the toner holding material layer 15 is within a specific small range, the image portion Q having a low white turbidity and a sufficient color depth is formed. Therefore, it is possible to obtain a print P having high image quality.

<Second Embodiment>
In the second embodiment according to the image forming method of the present invention, the toner held in a laminated state on the intermediate transfer member C as shown in FIGS. 3A to 3C in the toner holding process. After the toner particles are buried in the holding material layer 25 by an external force, the toner holding material layer 25 in a state where the toner image T is held is superposed on the image supporting substrate 21 to fix the toner image T. Other than the above, the method has the same requirements as those of the first embodiment.

  According to the image forming method described above, it is possible to obtain the same effect as that of the image forming method of the first embodiment.

Although the embodiments of the present invention have been specifically described above, the embodiments of the present invention are not limited to the above examples, and various modifications can be made.
For example, as shown in FIGS. 4A and 4B, first, a toner image T electrostatically formed on the photoconductor K with toner particles is formed on the image support base 11 in the toner holding process. Then, a filler that becomes the toner holding material layer 35 is introduced by solidifying on the image supporting substrate 11 on which the toner image T is carried, and this is solidified to hold the toner image T It may be.
According to such an image forming method, since the toner particles held in the formed printed matter P are hardly deformed from the particle shape of unused toner particles, the toner particles are separated from the printed matter P. Can be used for playback.

  Hereinafter, specific examples of the present invention will be described, but the present invention is not limited thereto.

[Synthesis Example 1 of Toner Particles]
(1) Preparation of Colorant Fine Particle Dispersion While stirring a surfactant solution in which 2.5 parts by mass of sodium dodecyl sulfonate was dissolved in 1600 parts by mass of ion-exchanged water, 400 parts by mass of quinacridone pigment was gradually added. Next, a colorant fine particle dispersion [1] in which colorant fine particles having a volume average particle diameter of 215 nm are dispersed was prepared by a dispersion treatment using a sand grinder manufactured by IMEX. The volume average particle size of the fine particles in the dispersion was measured by “UPA-150” (manufactured by Nikkiso Co., Ltd.).

(2) Preparation of toner Interface in which 4 parts by mass of sodium dodecylsulfonate was dissolved in 2800 parts by mass of ion-exchanged water in a reaction vessel equipped with a stirrer, a heating / cooling unit, a nitrogen introducing unit, and a raw material / auxiliary charging unit The activator solution was charged, and the internal temperature was raised to 80 ° C. while stirring at a stirring speed of 200 rpm under a nitrogen stream. To this solution, a polymerization initiator solution in which 10 parts by mass of potassium persulfate was dissolved in 400 parts by mass of ion-exchanged water was added, 530 parts by mass of styrene, 200 parts by mass of n-butyl acrylate, 70 parts by mass of methacrylic acid, n- A monomer mixture composed of 16 parts by mass of octyl mercaptan was added dropwise over 90 minutes, and then the polymerization treatment was carried out while maintaining heating for 120 minutes to obtain latex [Lx1].
On the other hand, 70 parts by mass of polyethylene wax was added to a monomer mixture consisting of 116 parts by mass of styrene, 47 parts by mass of n-butyl acrylate, 12 parts by mass of methacrylic acid, and 2 parts by mass of n-octyl mercaptan, and the mixture was heated to 80 ° C. A monomer solution was prepared by warming and dissolving. On the other hand, a surfactant solution in which 3 parts by mass of sodium dodecyl sulfonate is dissolved in 700 parts by mass of ion-exchanged water is heated to 80 ° C., and the monomer mixture and the surfactant solution are mixed. An emulsified dispersion [1] was prepared by performing a dispersion treatment for 30 minutes using “CLEARMIX” (manufactured by M Technique).
Then, 1700 parts by mass of ion-exchanged water and 160 parts by mass of the above latex [Lx1] were charged into a reaction vessel equipped with a stirrer, a heating / cooling device, a nitrogen introduction device, and a raw material auxiliary charging device, The internal temperature was raised to 80 ° C. while stirring at a stirring speed. A solution prepared by dissolving the above emulsified dispersion [1] and 6 parts by mass of potassium persulfate in 240 parts by mass of ion-exchanged water was added to this solution and polymerized for 2 hours to obtain a latex [Lx2].
Thereafter, a solution prepared by dissolving 5 parts by mass of potassium persulfate in 220 parts by mass of ion-exchanged water was added to the latex [Lx2], and 338 parts by mass of styrene, 110 parts by mass of n-butyl acrylate, 7 parts by mass of n-octyl mercaptan. A monomer mixture liquid consisting of parts was added dropwise over 90 minutes, and then heated for 120 minutes to carry out the polymerization process to obtain latex [Lx3] in which fine particles having a volume average particle size of 156 nm were dispersed. .
Furthermore, in a reaction vessel equipped with a stirrer, a heating / cooling device, and a raw material / auxiliary charging device, 1300 parts by mass of ion-exchanged water, 790 parts by mass of the latex [Lx3], and the colorant dispersion [1] 163 A mass part was charged, and 5M sodium hydroxide aqueous solution was added to adjust the pH to 10 while stirring at a stirring speed of 200 rpm. Next, a solution in which 27 parts by mass of magnesium chloride hexahydrate was dissolved in 27 parts by mass of ion-exchanged water was added, the temperature was raised to 86 ° C., and the particle growth reaction was continued at this temperature. When the particle size of the associated particles becomes 6.6 μm in volume average particle size, a solution in which 67 parts by mass of sodium chloride is dissolved in 270 parts by mass of ion-exchanged water is added to stop particle growth, and further heating The toner base particles having a volume average particle diameter of 6.4 μm are obtained by spheroidizing until the average circularity reaches 0.94, and then cooling, filtering, washing with water repeatedly, and drying. 1] was obtained.
0.5% by mass of silica fine particles “H-2000” (manufactured by Hoechst Japan) and 1% by mass of titanium dioxide fine particles “T-805” (manufactured by Nippon Aerosil Co., Ltd.) with respect to 100 parts by mass of the toner base particles [1] The toner [1] is obtained from the toner particles [1].
In the above, the volume average particle size of the fine particles in the latex [Lx3] and the volume average particle size of the toner base particles [1] are measured by “Coulter Multisizer” (manufactured by Beckman Coulter, Inc.). The average circularity is a value measured using a flow type particle image measuring device “FPIA-2000” (manufactured by Sysmex Corporation). Further, the shape and particle size of the toner base particles [1] did not change depending on the addition of silica and titanium dioxide. The same applies to the following.

[Synthesis Example 2 of Toner Particles]
Copper phthalocyanine pigment 6.0g, polycaprolactone polyester 1.64g, methyl methacrylate 100g, 1mmφ glass beads 260g are placed in a polymer bottle and dispersed for 4 hours with a bend shaker. Dispersion liquid [1] was prepared.
Next, a solution obtained by dissolving 6.3 g of polyvinylpyrrolidone in 242 g of ethanol was charged into a reaction vessel equipped with a stirrer, a heating / cooling device, a nitrogen introducing device, and a raw material / auxiliary charging device, and a stirring speed of 100 rpm under a nitrogen stream The internal temperature was raised to 70 ° C. while stirring. To this solution, 72.25 g of the above-mentioned colorant dispersion [1] and 1.60 g of azobisisobutyronitrile are added, and polymerization is performed for 24 hours to obtain a dispersion of pearl-like particles having high monodispersity. It was. Particles are separated from this pearl fine particle dispersion with a centrifuge, washed twice with ethanol, and then washed five times with water, so that the volume average particle diameter is 5.0 μm and the average circularity is 1.00. Toner base particles [2] were obtained.
0.5% by mass of silica fine particles “H-2000” (manufactured by Hoechst Japan) and 1% by mass of titanium dioxide fine particles “T-805” (manufactured by Nippon Aerosil Co., Ltd.) with respect to 100 parts by mass of the toner base particles [2] The toner [2] by toner particles [2] was obtained by processing with a Henschel mixer.

[Toner Particle Synthesis Example 3]
100 parts by mass of polyester resin (Tg 61 ° C., Mn = 4,200, Mw / Mn = 5.5), 6 parts by mass of copper phthalocyanine pigment, 5 parts by mass of polyethylene wax, charge control agent “Bontron E-84” (Orient (Made by Chemical Co., Ltd.) 2 parts by mass of a melt kneader is used to obtain a mixture, which is then applied to a pulverizer and further applied to a classifier, whereby a toner base having a volume average particle size of 7.5 μm and an average circularity of 0.78 Particles [3] were obtained.
0.5% by mass of silica fine particles “H-2000” (manufactured by Hoechst Japan) and 1% by mass of titanium dioxide fine particles “T-805” (manufactured by Nippon Aerosil Co., Ltd.) with respect to 100 parts by mass of the toner base particles [3] The toner [3] is obtained from the toner particles [3].

[Synthesis Example 4 of Toner Particles]
100 parts by mass of polyester resin (Tg 61 ° C., Mn = 4,200, Mw / Mn = 5.5), 5 parts by mass of polyethylene wax, 2 parts by mass of charge control agent “Bontron E-84” (manufactured by Orient Chemical Co., Ltd.) The mixture was applied to a kneader, and the mixture was applied to a pulverizer and further applied to a classifier to obtain toner base particles [4] having a volume average particle size of 7.5 μm and an average circularity of 0.78.
0.5% by mass of silica fine particles “H-2000” (manufactured by Hoechst Japan) and 1% by mass of titanium dioxide fine particles “T-805” (manufactured by Nippon Aerosil Co., Ltd.) with respect to 100 parts by mass of the toner base particles [4] The toner [4] is obtained from the toner particles [4].

[Developer Preparation Examples 1 to 4]
For toners [1] to [4], each of these and a silicon acrylic coat carrier are mixed so that the mass ratio is 6:94, whereby developers [1] to [4] which are two-component developers are mixed. Was prepared.

[Example 1]
Silicone gel “SE1891H” (manufactured by Dow Corning Toray) is applied on coated paper with a bar coater, and then left to stand in a sunny place and cured by sunlight, resulting in a thickness of 50 μm and a penetration of 45 An image support [1] having a flexible toner holding material layer was prepared.
On this image support [1], a toner image was formed by “bizhub C 253” (manufactured by Konica Minolta Business Technologies) from which the fixing device was removed using developer [1]. By passing it in a state where it was not heated, a printed product [1] was obtained.
Table 1 shows the degree of change in particle shape (B / A) and the refractive index ratio (C / D) in this print [1].

With respect to this printed matter [1], the fixing strength was calculated by measuring the fixing strength by the following mending tape peeling method. As a result, the fixing rate was 80% or more. It was.
-Mending tape peeling method-
1) Measure absolute reflection density D ₀ in the image area.
2) Lightly affix the mending tape “No.810-3-12” (manufactured by Sumitomo 3M) to the image area.
3) Reciprocating and rubbing on the mending tape 3.5 times with a pressure of 1 kPa.
4) Peel off the mending tape at an angle of 180 degrees and a force of 200 g.
5) measuring the absolute reflection density D ₁ of the post-peeling.
6) The fixing rate is calculated based on the following formula (M).
Formula (M): Fixing rate (%) = D ₁ / D ₀ × 100
For the measurement of absolute reflection density, a reflection densitometer “RD-918” (manufactured by Macbeth Co.) was used.

[Example 2]
After applying a gelatin solution adjusted to pH 3.0 (containing 20% by mass of titanium dioxide) to white polyethylene terephthalate (PET) that has been hydrophilized, it is dried until it becomes a soft gel, so that the thickness is 20 μm. An image support [2] having a flexible toner holding material layer having a penetration of 45 was produced.
On this image support [2], a toner image was formed by “bizhub C 253” (manufactured by Konica Minolta Business Technologies) from which the fixing device was removed using developer [2]. After passing through without heating, the printed material [2] was obtained by immersing in a formalin solution and curing the toner holding material layer of gelatin. With respect to this printed matter [2], the fixing rate was calculated in the same manner as in Example 1. As a result, fixing of the toner image was confirmed.
Table 1 shows the degree of change in particle shape (B / A) and the refractive index ratio (C / D) in this print [2].

[ Reference example ]
An image was formed on white polyethylene terephthalate (PET) by “bizhub C 253” (manufactured by Konica Minolta Business Technologies) using developer [3]. Fluorine-modified silicone gel “SIFEL 8370” (manufactured by Shin-Etsu Chemical Co., Ltd.) is dropped on this image, and after covering with a 5 μm transparent PET film, it is left to stand in a sunny place and exposed to sunlight to be cured. As a result, a print [3] was obtained. With respect to this printed matter [3], the fixing rate was calculated in the same manner as in Example 1. As a result, fixing of the toner image was confirmed.
Table 1 shows the degree of change in the particle shape degree (B / A) and the refractive index ratio (C / D) in this print [3].

[Example 3 ]
By applying silicone gel “SE1885” (manufactured by Dow Corning Toray) on PET treated with a fluorine coating solution, a transfer body having a flexible toner holding material layer having a thickness of 50 μm and a penetration of 90 is obtained. Produced.
A toner image formed by “bizhub C 253” (manufactured by Konica Minolta Business Technologies, Inc.) with the fixing device removed using developer [1] is transferred onto the transfer body, and then the transfer body is applied to the coated paper. Then, the above-mentioned removed fixing device is allowed to pass through without heating, and after the PET is peeled off, an ultraviolet curable resin “A-1753” (manufactured by Tesque) is applied and placed in a sunny place. The printed product [4] was obtained by placing and curing with sunlight. With respect to this printed matter [4], the fixing rate was calculated in the same manner as in Example 1. As a result, toner image fixing was confirmed.
Table 1 shows the degree of change in particle shape (B / A) and the refractive index ratio (C / D) in this print [4].

[Comparative Example 1]
A toner image is formed on a paper “J paper” (manufactured by Konica Minolta Business Solutions) using “bizhub C 253” (manufactured by Konica Minolta Business Technologies) from which the fixing device is removed using the developer [1]. The fixing device removed was passed through in a state where the fixing temperature was set to 180 ° C., so that a comparative print [5] was obtained. With respect to this comparative printed material [5], the fixing rate was calculated in the same manner as in Example 1. As a result, fixing of the toner image was confirmed.
Table 1 shows the degree of change in particle shape (B / A) in this comparative print [5].

[Comparative Example 2]
A toner image as an image portion is formed on paper “CF paper” (manufactured by Konica Minolta Business Solutions) by “bizhub C 253” (manufactured by Konica Minolta Business Technologies) with the fixing device removed using developer [3]. And forming a toner image corresponding to the non-image area other than the image area using the developer [4], and passing the fixed fixing device at a fixing temperature of 180 ° C. A comparative print [6] was obtained. For this comparative printed product [6], the fixing rate was calculated in the same manner as in Example 1. As a result, fixing of the toner image was confirmed.
Table 1 shows the degree of change in particle shape (B / A) and the refractive index ratio (C / D) of this comparative print [6].

[Comparative Example 3]
An image support [3] was prepared by cutting a toner receiving portion having a width of 100 μm and a depth of 50 μm on an A4 size PET sheet having a thickness of 500 μm based on the desired image. By supplying developer [1] to the toner receiving portion of this image support [3], a comparative print [7] was obtained. With respect to this comparative printed product [7], the fixing rate was calculated in the same manner as in Example 1. As a result, fixing of the toner image was confirmed.
Table 1 shows the degree of change in particle shape (B / A) and the refractive index ratio (C / D) in this comparative print [7].

[Comparative Example 4]
In Example 1, a toner image was formed on the coated paper in the same manner except that the coated paper was used instead of the image support [1]. By passing this through the fixing device without heating, a comparative print [8] was obtained. As a result of observation, toner particles were partially attached to the fixing roller of the fixing device. With respect to this comparative printed product [8], the fixing rate by the mending tape peeling method was calculated in the same manner as in Example 1, and it was confirmed that the toner image was not fixed.
Table 1 shows the degree of change in particle shape (B / A) in this comparative print [8].

[Comparative Example 5]
A toner image was obtained by “bizhub C 253” (manufactured by Konica Minolta Business Technologies, Inc.) in which a fixing device was removed using developer [1] on “super gloss coated paper” (manufactured by Oji Paper Co., Ltd.) having a resin layer on the surface. And the above-mentioned fixing device removed was passed with the fixing temperature set at 180 ° C. to obtain a comparative print [9]. For this comparative printed product [9], the fixing rate was calculated in the same manner as in Example 1. As a result, the fixing of the toner image was confirmed.
Table 1 shows the degree of change in particle shape (B / A) in this comparative print [9].

[Evaluation]
The amount of electric power required to obtain the printed materials of Examples 1 to 4 and Comparative Examples 1 to 5, and the turbidity and color depth of the image portion of the obtained printed materials were evaluated as follows. The results are shown in Table 1.

[White turbidity]
The printed matter was evaluated according to the following sensory evaluation criteria by visual observation of 20 monitors.
-Sensory evaluation criteria-
A: All 20 people evaluated that they were not cloudy.
○: 15 or more and less than 20 people evaluated as not cloudy.
(Triangle | delta): The thing evaluated that 10 or more and less than 15 people are not cloudy.
X: It was evaluated that less than 10 people were not clouded.

[Color depth]
The printed matter was evaluated according to the following sensory evaluation criteria by visual observation of 20 monitors.
-Sensory evaluation criteria-
A: All 20 people evaluated that the color was deep.
○: 15 or more and less than 20 people evaluated that the color is deep.
Δ: 10 or more and less than 15 people evaluated that the color is deep.
X: Less than 10 people evaluated the color as deep.

1A and 1B are schematic diagrams for explaining an image forming method according to a first embodiment of the present invention, in which FIG. 1A is a diagram illustrating a state where a toner image is formed on a photoreceptor, and FIG. FIG. 3 is a diagram illustrating a state where a toner image is held on a body. It is a schematic diagram which shows an example of the form of the image of this invention. FIG. 6 is a schematic diagram for explaining a modification of the image forming method of the present invention, in which (a) shows a state in which a toner image is formed on the photosensitive member, and (b) shows toner holding on the intermediate transfer member. FIG. 4C is a diagram illustrating a state where a material layer is supported, and FIG. FIGS. 4A and 4B are schematic diagrams for explaining an image forming method according to a second embodiment of the present invention, in which FIG. 4A shows a state where a toner image is formed on an image supporting substrate, and FIG. FIG. 6 is a diagram illustrating a state where a toner image is held on an image support.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image support body 11 Image support base | substrate 15, 25, 35 Toner holding material layer C Intermediate transfer material K Photoconductor P Printed matter Q Image part T Toner image

Claims (2)

An image forming method that undergoes a toner image holding process for holding a toner image formed of toner particles containing at least a resin by applying an external force to a toner holding material layer formed on an image supporting substrate. There,
The particle shape degree represented by (minimum diameter of projection image / maximum diameter of projection image) of the toner particles subjected to the holding treatment step is A, and (minimum diameter of projection image / The following relational expression (1) is satisfied when the particle shape degree of the toner particles represented by the maximum diameter of the projected image is B,
The refractive index of the resin constituting the toner particles C, and the refractive index of the material constituting the toner holding layer meets the following equation (2) is D, the external force is applied to the toner holding layer An image forming method , wherein only the pressure is applied, and the material constituting the toner holding material layer has thixotropic properties .
Relational expression (1): 1 ≧ B / A ≧ 0.9
Relational expression (2): 1.4 ≧ C / D ≧ 0.7 In the toner image holding treatment step, after the toner particles are buried in the toner holding material layer laminated on the intermediate transfer member by an external force, the toner holding material layer in a state where the toner image is held is changed to an image supporting substrate. The image forming method according to claim 1, wherein the image forming method is performed by superimposing the image on the image.

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