JP2010008816A - White toner for electrostatic image development, two-component developer, image forming method, image forming apparatus, and process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a white toner having good low temperature fixability and offset resistance, free from dropping of the toner from a fixed surface even when a sheet is folded or rubbed, having not only excellent cleaning property but good chargeability, less contamination on a base, and high concealing property, and enabling a good white image to be formed. <P>SOLUTION: The toner for electrostatic image development includes a toner base material prepared by dispersing an organic solvent phase in which at least a functional group-containing polyester resin is dissolved, an active hydrogen-containing compound and a colorant into an aqueous medium phase having dispersion of resin particles, inducing an extension reaction and/or a crosslinking reaction of the functional group-containing polyester resin and the active hydrogen-containing compound, and removing the organic solvent from the obtained dispersion liquid, wherein a polyol-coated titanium oxide pigment is used as the colorant. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a white toner used for image formation using an electrophotographic process. More specifically, the present invention relates to an upper surface of an image forming surface in order to obtain a contrast image even when a transparent film or the like is used as a recording material for a full color image. The present invention relates to a white toner used on the entire surface.

  The color of an electrophotographic copy image is generally black, but recently, full-color images using four colors of yellow, magenta, cyan, and black have been widely used. In such a case, an image is formed using a four-color toner on a white substrate such as paper. However, in the case of colored paper or black paper with a colored base material, or a transparent film that is a transparent base material, satisfactory color development cannot be obtained with four color toners. For this reason, it has been proposed that white toner is newly used as the fifth color toner to form a white background (see Patent Document 1).

  The white toner is used as a white base for paper or the like which is a black or colored substrate, or is used for a white background such as a film which is a transparent substrate. In this case, the white toner is required to have a concealing characteristic. The concealment characteristic is an ability to hide the tip of the white base material on which the white toner is fixed. In the case of white, it is necessary to scatter and reflect all incident light because only a fixed white toner is used for color development. If even a small amount of incident light is transmitted, the concealability deteriorates and a blur difference is felt. Therefore, it is very difficult to design compared to black toner and color toner that absorb light.

  Various proposals have been made so far in order to improve the concealability (see, for example, Patent Document 2 and Patent Document 3). However, sufficient concealment is not obtained. In practice, it is necessary to apply a much larger amount than the toner used as the color toner, and to thicken the fixed white toner layer to provide a hiding power. At this time, since the white toner layer is thickened, cracking of the toner layer and peeling of the toner layer in the case of a film become a problem.

  In addition, toners (yellow toner, magenta toner, cyan toner, black toner) used for developing an electrostatic image generally contain a colorant, a charge control agent, and other additives in a binder resin. The colored particles are roughly classified into a pulverization method and a polymerization method, and white toner is generally manufactured by a pulverization method. In the pulverization method, a colorant, a charge control agent, an offset preventing agent and the like are melt-mixed in a thermoplastic resin and uniformly dispersed, and the resulting composition is pulverized and classified to produce a toner.

  According to the pulverization method, a toner having excellent characteristics can be produced to some extent, but there is a limit to the selection of the toner material. For example, the composition obtained by melt mixing must be capable of being pulverized and classified by economically usable equipment. From this requirement, the melt-mixed composition must be made sufficiently brittle. Therefore, when the above composition is actually pulverized into particles, a high-range particle size distribution is likely to be formed, and when attempting to obtain a copy image with good resolution and gradation, for example, a particle size of 5 μm The following fine powder and coarse powder of 20 μm or more must be removed by classification, which has the disadvantage that the yield becomes very low.

  Further, in the pulverization method, it is difficult to uniformly disperse the colorant, the charge control agent, and the like in the thermoplastic resin. The uneven dispersion of the compounding agent adversely affects the fluidity, developability, durability, image quality and the like of the toner.

  In recent years, in order to overcome these problems in the pulverization method, a toner production method by a polymerization method has been proposed. For example, Patent Document 4 discloses a method for producing white particles by a suspension polymerization method. However, the toner particles obtained by the suspension polymerization method are spherical and have a drawback of poor cleaning properties. Development / transfer with a low image area ratio results in a small amount of residual toner, and poor cleaning does not pose a problem. However, images with a high image area ratio, such as photographic images, and untransferred images formed due to poor paper feed, etc. Toner may be generated on the photoconductor as untransferred toner, and if accumulated, the image may be soiled. In addition, the charging roller that contacts and charges the photosensitive member is contaminated, and the original charging ability cannot be exhibited.

  Furthermore, as a problem peculiar to the white toner, there is a limit to fixability when aiming at low-temperature fixing by increasing the pigment concentration in order to improve concealment.

JP 2006-220694 A Japanese Patent Laid-Open No. 1-105962 JP 2000-056514 A JP 2007-41078 A

  The present invention is compatible with a low-temperature fixing system, has good offset resistance, does not peel off the toner from the fixing surface even when bent or rubbed, and has excellent cleaning properties as well as good chargeability. To provide a white toner with little background stain and high concealability and capable of forming a good white image, and to provide a developer, an image forming method, an image forming apparatus, and a process cartridge using the toner. Objective.

  In order to solve the above problems, the invention according to claim 1 is characterized in that resin fine particles are dispersed in an organic solvent phase in which at least a functional group-containing polyester resin is dissolved, an active hydrogen-containing compound, and a colorant. The toner is dispersed in a water-based aqueous medium phase to cause an elongation reaction and / or a crosslinking reaction between the functional group-containing polyester resin and the active hydrogen-containing compound, and an organic solvent is removed from the obtained dispersion. A toner for developing an electrostatic charge image as a base, and a white toner for developing an electrostatic charge image using a polyol-coated titanium oxide pigment as the colorant.

  The invention according to claim 2 is the white toner for developing electrostatic images according to claim 1, wherein the functional group-containing polyester resin and a non-reactive polyester resin are dissolved in the organic solvent phase. The weight ratio of the functional group-containing polyester resin and the non-reactive polyester resin is 5/95 to 75/25.

  The invention according to claim 3 is the white toner for developing electrostatic images according to claim 1 or 2, wherein the toner base contains 10 to 30% by weight of a polyol-coated titanium oxide pigment. .

  According to a fourth aspect of the present invention, in the white toner for developing an electrostatic charge image according to any one of the first to third aspects, the toner base has a volume average particle diameter of 3 to 9 μm.

  According to a fifth aspect of the present invention, in the white toner for developing electrostatic images according to the fourth aspect, the toner base has a volume average particle diameter (Dv) / number average particle diameter (Dn) of 1.25 or less. It is characterized by that.

  The invention according to claim 6 is the white toner for developing electrostatic images according to any one of claims 1 to 5, wherein the toner base has an average circularity of 0.900 to 0.980. To do.

  According to a seventh aspect of the present invention, in the white toner for developing an electrostatic charge image according to any one of the first to sixth aspects, a full color comprising a yellow toner, a magenta toner, a cyan toner and a black toner formed on a transparent film. In order to view the image from the side opposite to the image forming surface, the image is used to whiten the back surface of the full-color image.

  The invention described in claim 8 is a two-component developer including a carrier comprising at least the toner according to any one of claims 1 to 7 and magnetic particles.

  According to the ninth aspect of the present invention, a full color image including yellow toner, magenta toner, cyan toner, and black toner is formed on a transparent film by an electrophotographic method, and the full color image is opposite to the image forming surface. A solid image of white toner is formed on the full-color image on the image forming surface using the white toner for developing an electrostatic charge image according to any one of claims 1 to 6. It is a characteristic image forming method.

  According to a tenth aspect of the present invention, there is provided a full color image forming means for forming a full color image containing yellow toner, magenta toner, cyan toner and black toner on a transparent film by an electrophotographic method, and the full color image The solid image of the white toner for developing an electrostatic charge image according to any one of claims 1 to 6 is formed on the full-color image on the image forming surface so as to be viewed from the side opposite to the image forming surface. And a white toner image forming unit.

  According to an eleventh aspect of the present invention, the electrostatic charge image carrier and at least a developing unit that develops the electrostatic charge image formed on the electrostatic charge image carrier with toner to form a visible image are integrated. A process cartridge that is supported and detachable from a main body of the image forming apparatus, wherein the process cartridge uses the white toner for developing an electrostatic charge image according to any one of claims 1 to 6. .

  According to the present invention, the low-temperature fixability and offset resistance are good, and the toner does not peel off from the fixing surface even if it is bent or rubbed. Further, not only is the cleaning property excellent, but also the charging property is good. Further, it is possible to provide a white toner that has less background stains and has high concealability and forms a good white image.

Hereinafter, the present invention will be described in detail.
In the present invention, at least an organic solvent phase in which a functional group-containing polyester resin is dissolved, an active hydrogen-containing compound, and a colorant are dispersed in an aqueous medium phase in which resin fine particles are dispersed, or In advance, an organic solvent phase in which at least the functional group-containing polyester resin, the active hydrogen-containing compound, and a colorant are dispersed or dissolved in an organic solvent is added to the aqueous medium phase in which the resin fine particles are dispersed. For electrostatic charge image development in which an elongation reaction and / or a crosslinking reaction between the functional group-containing polyester resin and the active hydrogen-containing compound is caused to occur, and an organic solvent is removed from the resulting dispersion to form a toner base. Toner,
It is a white toner for developing electrostatic images using a polyol-coated titanium oxide pigment as the colorant.

  In the present invention, a full color image is formed on a transparent film by an electrophotographic method using yellow toner, cyan toner, magenta toner, and black toner, and a solid back image is formed on the full color image with a white toner. It is assumed that it has been formed and fixed. When this image is viewed from the direction opposite to the image side on which the white toner is formed, that is, from the film side, an image with a high gloss and high-quality feeling can be obtained. Since the surface of the transparent film is smooth, a very high gloss can be obtained uniformly regardless of the amount of toner adhered. Furthermore, since the surface of the image is smooth, external light (illumination light and natural light) is not irregularly reflected on the surface, so that a very bright image can be obtained. By these things, a high-class feeling can be obtained from human senses.

  In addition, the white toner of the present invention is a surface opposite to the image forming surface of the full color image composed of yellow toner, cyan toner, magenta toner and black toner formed on the transparent film according to claim 7. In order to view the image from the side, in addition to using it to make the back surface white, it is possible to apply a paper, film, or the like, which is a transparent, black or colored substrate, to white and use it as a base for a white background.

When the white toner of the present invention is used as a solid back image or a white background base, it is necessary to provide sufficient concealment. Therefore, the amount of white toner attached is preferably 0.5 mg / cm ² or more. Considering the cracking of the layer, it is appropriate to set it to 10 mg / cm ² or less.

  In the present invention, in addition to the white toner, a color toner and a black toner are used in combination. Conventionally used electrophotographic products can be used as the color toner and the black toner. The weight average particle diameter of these color toner and black toner is not particularly limited and can be appropriately selected according to the purpose. The thickness is preferably 2 to 15 μm, but when high image quality is to be achieved, it may be produced by a high-precision pulverization method or a polymerization method.

  The raw material constituting the white toner of the present invention may be a known material as long as the properties of the toner satisfy the relationship defined in the present invention, and a combination thereof may be used.

[Organic solvent phase]
<Organic solvent>
In the present invention, any organic solvent that can dissolve and / or disperse the toner composition (functional group-containing polyester resin, active hydrogen-containing compound, colorant, non-reactive polyester resin, etc.) is particularly limited. is not. As a preferable thing, it is preferable that the boiling point of this solvent is less than 150 degreeC from the point of being easy to remove.
Examples of the solvent include toluene, xylene, benzene, carbon tetrachloride, methylene chloride, 1,2-dichloroethane, 1,1,2-trichloroethane, trichloroethylene, chloroform, monochlorobenzene, methyl acetate, ethyl acetate, methyl ethyl ketone, acetone. , Tetrahydrofuran and the like can be used alone or in combination of two or more. Among these, methyl acetate and ethyl acetate are preferable because they are particularly volatile to toner.
The amount of the solvent used is usually 40 to 300 parts by weight, preferably 60 to 140 parts by weight, and more preferably 80 to 120 parts by weight with respect to 100 parts by weight of the toner composition.

<Functional group-containing polyester resin>
In the present invention, a polyester prepolymer having an isocyanate group can be used as the functional group-containing polyester resin.
Examples of the polyester prepolymer (A) having an isocyanate group include a polycondensate of a polyol (1) and a polycarboxylic acid (2), and a polyester having an active hydrogen group further reacted with a polyisocyanate (3). Is mentioned. Examples of the active hydrogen group possessed by the polyester include hydroxyl groups (alcoholic hydroxyl groups and phenolic hydroxyl groups), amino groups, carboxyl groups, mercapto groups, and the like. Among these, alcoholic hydroxyl groups are preferred.

  Examples of the polyol (1) include a diol (1-1) and a tri- or higher valent polyol (1-2). (1-1) alone or (1-1) and a small amount of (1-2) Mixtures are preferred.

  Diol (1-1) includes alkylene glycol (ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, etc.); alkylene ether glycol (diethylene glycol) , Triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, etc.); alicyclic diols (1,4-cyclohexanedimethanol, hydrogenated bisphenol A, etc.); bisphenols (bisphenol A, bisphenol) F, bisphenol S, etc.); alkylene oxide (ethylene oxide, propylene oxide, butylene oxide, etc.) adduct of the above alicyclic diol; Alkylene oxide phenol compound (ethylene oxide, propylene oxide, butylene oxide, etc.), etc. adducts. Among them, preferred are alkylene glycols having 2 to 12 carbon atoms and alkylene oxide adducts of bisphenols, and particularly preferred are alkylene oxide adducts of bisphenols and alkylene glycols having 2 to 12 carbon atoms. It is a combined use.

  The trihydric or higher polyol (1-2) includes 3 to 8 or higher polyhydric aliphatic alcohols (glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, sorbitol, etc.); trihydric or higher phenols (Trisphenol PA, phenol novolak, cresol novolak, etc.); and alkylene oxide adducts of the above trivalent or higher polyphenols.

  Examples of the polycarboxylic acid (2) include dicarboxylic acid (2-1) and trivalent or higher polycarboxylic acid (2-2). (2-1) alone and (2-1) with a small amount of ( The mixture of 2-2) is preferred.

  Dicarboxylic acid (2-1) includes alkylene dicarboxylic acid (succinic acid, adipic acid, sebacic acid, etc.); alkenylene dicarboxylic acid (maleic acid, fumaric acid, etc.); aromatic dicarboxylic acid (phthalic acid, isophthalic acid, terephthalic acid) And naphthalenedicarboxylic acid). Of these, preferred are alkenylene dicarboxylic acids having 4 to 20 carbon atoms and aromatic dicarboxylic acids having 8 to 20 carbon atoms.

  Examples of the trivalent or higher polycarboxylic acid (2-2) include aromatic polycarboxylic acids having 9 to 20 carbon atoms (trimellitic acid, pyromellitic acid, and the like). In addition, as polycarboxylic acid (2), you may make it react with polyol (1) using the acid anhydride or lower alkyl ester (methyl ester, ethyl ester, isopropyl ester, etc.) of the above-mentioned thing.

Since the polyester having an alcoholic hydroxyl group at the terminal is prepared by polycondensation reaction, the ratio of the polyol (1) to the polycarboxylic acid (2)
The equivalent ratio [OH] / [COOH] of [OH] and carboxyl group [COOH] is usually 2/1 to 1/1, preferably 1.5 / 1 to 1/1, more preferably 1.3 / 1. -1.02 / 1.

  Examples of the polyisocyanate (3) used for preparing the polyester prepolymer by reacting with the alcoholic hydroxyl group of the polyester include aliphatic polyisocyanates (tetramethylene diisocyanate, hexamethylene diisocyanate, 2,6-diisocyanatomethyl carbonate). Proate, etc.); alicyclic polyisocyanates (isophorone diisocyanate, cyclohexylmethane diisocyanate, etc.); aromatic diisocyanates (tolylene diisocyanate, diphenylmethane diisocyanate, etc.); Xylylene diisocyanate); isocyanurates; the polyisocyanates blocked with phenol derivatives, oximes, caprolactam, etc .; and A combination of two or more of these may be mentioned.

  The use ratio of the polyisocyanate is usually 5/1 to 1/1, preferably 4/1 to 1 as the equivalent ratio [NCO] / [OH] of the isocyanate group [NCO] and the hydroxyl group [OH] of the polyester having a hydroxyl group. 1.2 / 1, more preferably 2.5 / 1 to 1.5 / 1. When [NCO] / [OH] exceeds 5, the low-temperature fixability deteriorates. If the molar ratio of [NCO] is less than 1, the urea content in the modified polyester will be low, and the hot offset resistance will deteriorate.

  The number of isocyanate groups contained per molecule in the polyester prepolymer (A) having an isocyanate group is usually 1 or more, preferably 1.5 to 3 on average, more preferably 1.8 to 2.5 on average. It is a piece. If it is less than 1 per molecule, the molecular weight of the modified polyester after crosslinking and / or elongation becomes low, and the hot offset resistance deteriorates.

<Combination of non-reactive low molecular weight polyester>
In the present invention, it is important not only to use the modified polyester (A) alone, but also to contain an unmodified polyester (C) that is not modified as a toner binder component together with the modified polyester (A). By using (C) in combination, the low-temperature fixability and the glossiness when used in a full-color apparatus are improved.
Examples of (C) include the same polycondensates of polyol (1) and polycarboxylic acid (2) as in the polyester component (A), and preferred ones are also the same as (A). (C) is not limited to unmodified polyester, but may be modified with a chemical bond other than a urea bond, and may be modified with, for example, a urethane bond. It is preferable that (A) and (C) are at least partially compatible with each other in terms of low-temperature fixability and hot offset resistance. Accordingly, the polyester component (A) and (C) preferably have similar compositions. When (C) is contained, the weight ratio of (A) to (C) is usually 5/95 to 75/25, preferably 10/90 to 25/75, more preferably 12/88 to 25/75, Especially preferably, it is 12 / 88-22 / 78. If the weight ratio of (A) is less than 5%, the hot offset resistance deteriorates, and it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability.

  The peak molecular weight measured by GPC (gel permeation chromatography) of the non-reactive polyester (C) which is not modified is usually 1000 to 30000, preferably 1500 to 10000, more preferably 2000 to 8000. If it is less than 1000, heat-resistant storage stability will deteriorate, and if it exceeds 30000, low-temperature fixability will deteriorate. The hydroxyl value of (C) is preferably 5 or more, more preferably 10 to 120, and particularly preferably 20 to 80. If it is less than 5, it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability. The acid value of (C) is usually from 0.5 to 40, preferably from 5 to 35. If the acid value is too high, it tends to be negatively charged, which is not preferable. Those exceeding this range are susceptible to environmental influences under high temperature and high humidity and low temperature and low humidity environments, and are liable to cause image deterioration.

[Active hydrogen-containing compounds]
As will be described later, the polyester prepolymer (A) having an isocyanate group has a higher molecular weight when subjected to elongation and / or crosslinking reaction with an active hydrogen-containing compound.
In the present invention, amines can be used as the active hydrogen-containing compound as a crosslinking agent and / or an extender. As amines (B), diamine (B1), trivalent or higher polyamine (B2), aminoalcohol (B3), aminomercaptan (B4), amino acid (B5), and amino acids B1-B5 blocked (B6) etc. are mentioned.
Examples of the diamine (B1) include aromatic diamines (phenylenediamine, diethyltoluenediamine, 4,4′-diaminodiphenylmethane, etc.); alicyclic diamines (4,4′-diamino-3,3′-dimethyldicyclohexylmethane, diamines). Cyclohexane, isophoronediamine, etc.); and aliphatic diamines (ethylenediamine, tetramethylenediamine, hexamethylenediamine, etc.) and the like.
Examples of the trivalent or higher polyamine (B2) include diethylenetriamine and triethylenetetramine.
Examples of amino alcohol (B3) include ethanolamine and hydroxyethylaniline.
Examples of amino mercaptan (B4) include aminoethyl mercaptan and aminopropyl mercaptan.
Examples of the amino acid (B5) include aminopropionic acid and aminocaproic acid.
Examples of the B1 to B5 amino group blocked (B6) include ketimine compounds and oxazoline compounds obtained from the B1 to B5 amines and ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.).
Among these amines (B), preferred are B1 and a mixture of B1 and a small amount of B2.
Furthermore, if necessary, the molecular weight of the modified polyester after completion of the reaction can be adjusted by using a terminator for crosslinking and / or elongation. Examples of the terminator include monoamines (diethylamine, dibutylamine, butylamine, laurylamine, etc.), and those blocked (ketimine compounds).

<Characteristics of toner binder>
In the present invention, as described above, a urea-modified polyester resin obtained by a reaction between a polyester prepolymer (A) and an amine (B) is used as a toner binder, and a non-reactive polyester (C Other components (including the resin used for the colorant master batch) are also used in combination.
In the present invention, the glass transition point (Tg) of the toner binder is usually 40 to 70 ° C., preferably 45 to 55 ° C. If it is less than 40 ° C., the heat-resistant storage stability of the toner deteriorates, and if it exceeds 70 ° C., the low-temperature fixability becomes insufficient. Due to the presence of the crosslinked and / or elongated polyester resin, the toner for developing an electrostatic charge image of the present invention exhibits good storage stability even when the glass transition point is low as compared with known polyester-based toners.

[Aqueous medium phase]
<Aqueous medium>
In the present invention, the aqueous medium in which the resin fine particles described later are dispersed to form the aqueous medium phase may be water alone, or a solvent miscible with water may be used in combination. Examples of miscible solvents include alcohols (methanol, isopropanol, ethylene glycol, etc.), dimethylformamide, tetrahydrofuran, cellosolves, and lower ketones (acetone, methyl ethyl ketone, etc.). These can be used singly or in combination of two or more.

<Resin fine particles>
The resin fine particles in the present invention are added in the production process in order to control the toner shape (circularity, particle size distribution, etc.) described later. The fine particles are considered to be bonded to the surface portion when an organic solvent phase and an active hydrogen-containing compound (amines) are dispersed in an aqueous medium to form organic dispersed particles, as will be described later. As a result, like the external additive described later, it is considered that the toner base particles obtained are unevenly distributed mainly on the surface portion. In the present invention, it is necessary and important that the amount of resin fine particles contained in the obtained toner particles after the external additive treatment is 0.5 to 5.0 wt%.
When the content is less than 0.5 wt%, the storability of the toner deteriorates, blocking occurs during storage and in the developing machine, and when the remaining amount is 5.0 wt% or more, the resin fine particles are not present. The exudation of the wax is obstructed, the effect of releasing the wax is not obtained, and the occurrence of offset is observed. Further, it is important that the glass transition point (Tg) of the resin fine particles is 40 to 100 ° C. and the weight average molecular weight is 9000 to 200,000. If the Tg of the resin fine particles is less than 40 ° C. and / or the weight average molecular weight is less than 9,000, the storage stability of the toner deteriorates, and blocking occurs during storage and in the developing machine. Is 80 ° C. or higher and / or the weight average molecular weight is 200,000 or higher, the resin fine particles inhibit the adhesiveness to the fixing paper, and an increase in the minimum fixing temperature is observed.

The residual rate of the resin fine particles can be measured by analyzing a substance caused by the resin fine particles, not by the toner particles, using a pyrolysis gas chromatograph mass spectrometer, and calculating from the peak area.
The detector is preferably a mass spectrometer, but is not particularly limited. The dispersion / blending amount of the resin fine particles in the aqueous medium may be set so as to satisfy the above-mentioned conditions relating to the content, but is usually in the range of about 0.5 to 10% by weight.

The resin fine particles may be any resin as long as it can form an aqueous dispersion, and may be a thermoplastic resin or a thermosetting resin. For example, vinyl resins, polyurethane resins, epoxy resins, polyester resins, polyamide resins, polyimides Examples thereof include resins, silicon-based resins, phenol resins, melamine resins, urea resins, aniline resins, ionomer resins, and polycarbonate resins. As the resin fine particles, two or more of the above resins may be used in combination. Of these, vinyl resins, polyurethane resins, epoxy resins, polyester resins, and combinations thereof are preferred because an aqueous dispersion of fine spherical resin particles is easily obtained.
Examples of the vinyl resin include polymers obtained by homopolymerization or copolymerization of vinyl monomers, such as styrene- (meth) acrylic acid ester resins, styrene-butadiene copolymers, and (meth) acrylic acid-acrylic acid ester polymers. Styrene-acrylonitrile copolymer, styrene-maleic anhydride copolymer, styrene- (meth) acrylic acid copolymer, and the like.

<Colorant>
The white colorant used in the present invention is preferably titanium oxide having a particle size of 0.1 to 0.4 μm. This titanium oxide can be obtained by any manufacturing method such as a sulfuric acid method and a chlorination method. In addition, any crystal structure such as anatase type, rutile type or brookite type can be used. In particular, those surface-treated with siloxane or a silane coupling agent are preferable, and those surface-treated with a polyol organic material are particularly preferable. That is, when the toner binder according to the present invention is used in combination with titanium oxide coated with a polyol-based organic substance as a white colorant, the titanium oxide has a strong hiding power, and the amount added to the binder is relatively small and desired. Since whiteness can be obtained, it is possible to obtain a toner image that does not easily peel off even if it is bent or rubbed.

  As the polyol-coated titanium oxide pigment used in the present invention, Taipei CR-50-2 and Taipei CR-60-2 (both manufactured by Ishihara Sangyo Co., Ltd.) can be obtained as commercial products. These have the characteristics shown in the table below (from the company brochure).

  The amount to be used is preferably 10 to 30% by weight of the polyol-coated titanium oxide pigment in the toner. If it is less than 10% by weight, the whiteness is low and the hiding power is low. On the other hand, if it exceeds 30% by weight, the low-temperature fixability is hindered.

  The colorant used in the present invention can also be used as a master batch combined with a resin. As the binder resin to be kneaded with the master batch, the same resin as the binder resin can be used. Moreover, binder resin may be used individually by 1 type, and 2 or more types may be mixed and used for it.

<Release agent>
Further, a wax may be contained together with the toner binder and the colorant. Known waxes can be used as the wax of the present invention, such as polyolefin wax (polyethylene wax, polypropylene wax, etc.); long chain hydrocarbon (paraffin wax, sasol wax, etc.); carbonyl group-containing wax, etc. It is done. Of these, carbonyl group-containing waxes are preferred.
Examples of the carbonyl group-containing wax include polyalkanoic acid esters (carnauba wax, montan wax, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18. -Octadecandiol diol distearate, etc.); polyalkanol esters (tristearyl trimellitic acid, distearyl maleate, etc.); polyalkanoic acid amides (ethylene diamine dibehenyl amide, etc.); polyalkylamides (trimellitic acid tristearyl amide, etc.) And dialkyl ketones (such as distearyl ketone). Among these carbonyl group-containing waxes, polyalkanoic acid esters are preferred.
The melting point of the wax of the present invention is usually 40 to 160 ° C, preferably 50 to 120 ° C, more preferably 60 to 90 ° C. A wax having a melting point of less than 40 ° C. has an adverse effect on heat resistant storage stability, and a wax having a melting point of more than 160 ° C. tends to cause a cold offset when fixing at a low temperature.
Further, the melt viscosity of the wax is preferably 5 to 1000 cps, more preferably 10 to 100 cps as a measured value at a temperature 20 ° C. higher than the melting point. Waxes exceeding 1000 cps have poor effects for improving hot offset resistance and low-temperature fixability.
The amount of the wax (release agent) used is usually 0 to 40% by weight, preferably 3 to 30% by weight as the content in the toner base. Further, the wax (release agent) can be dissolved or dispersed in the organic solvent phase, but is not limited thereto.

<Charge control agent>
The toner of the present invention may contain a charge control agent as necessary. All known charge control agents can be used, such as nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine dyes, alkoxy amines, quaternary ammonium salts (fluorine-modified). Quaternary ammonium salts), alkylamides, phosphorus simple substances or compounds, tungsten simple substances or compounds, fluorine-based activators, salicylic acid metal salts, and metal salts of salicylic acid derivatives. Specifically, Nitronine-based dye Bontron 03, quaternary ammonium salt Bontron P-51, metal-containing azo dye Bontron S-34, oxynaphthoic acid metal complex E-82, salicylic acid metal complex E- 84, E-89 of a phenol-based condensate (manufactured by Orient Chemical Industry Co., Ltd.), TP-302 of a quaternary ammonium salt molybdenum complex, TP-415 (manufactured by Hodogaya Chemical Industry Co., Ltd.), quaternary ammonium Copy charge PSY VP2038 of salt, copy blue PR of triphenylmethane derivative, copy charge of quaternary ammonium salt NEG VP2036, copy charge NX VP434 (manufactured by Hoechst), LRA-901, LR-147 which is a boron complex (Nippon Carlit), copper phthalocyanine, perylene, quinacridone Azo pigments, sulfonate group, carboxyl group, and polymer compounds having a functional group such as a quaternary ammonium salt.

  In the present invention, the amount of charge control agent used is determined by the toner production method including the type of binder resin, the presence or absence of additives used as necessary, and the dispersion method, and is uniquely limited. However, it is used in the range of 0.1 to 10 parts by weight with respect to 100 parts by weight of the binder resin, and preferably in the range of 0.2 to 5 parts by weight. When the amount exceeds 10 parts by weight, the chargeability of the toner is too high, the effect of the main charge control agent is reduced, the electrostatic attractive force with the developing roller is increased, the flowability of the developer is reduced, and the image density is reduced. Incurs a decline. These charge control agents can be dissolved and dispersed after being melt-kneaded with the masterbatch and resin, or of course, it may be added when directly dissolving and dispersing in an organic solvent. It is preferable to make it.

[Production of toner]
The dry toner of the present invention can be produced by the following method, but is not limited thereto.

<Method for producing toner base particles in aqueous medium>
The aqueous phase used in the present invention is used by adding resin fine particles in advance. The water used for the aqueous phase may be water alone, or a solvent miscible with water may be used in combination. Examples of the miscible solvent include alcohol (methanol, isopropanol, ethylene glycol, etc.), dimethylformamide, tetrahydrofuran, cellosolves (methylcellosolve, etc.), lower ketones (acetone, methyl ethyl ketone, etc.) and the like.

<Dispersion and reaction of organic solvent phase>
As described above, the toner base particles are obtained by dispersing the organic solvent phase containing the polyester prepolymer (A) together with the amines (B) in the aqueous medium phase, and extending and / or crosslinking in the aqueous medium phase. It is formed through a step of forming a urea-modified polyester.
As a method for stably forming a dispersion comprising a polyester prepolymer (A) in an aqueous phase, a composition of a toner raw material comprising a polyester prepolymer (A) dissolved or dispersed in an organic solvent in an aqueous phase is added. And a method of dispersing by shearing force.
Polyester prepolymer (A) dissolved or dispersed in an organic solvent and other toner composition (hereinafter referred to as toner raw material), colorant masterbatch, release agent, charge control agent, unmodified The polyester resin or the like may be mixed when forming the dispersion in the aqueous phase, but after the toner raw material is mixed in advance and dissolved or dispersed in an organic solvent, the mixture is added to the aqueous phase and dispersed. Is more preferable.
In the present invention, other toner raw materials such as a colorant, a release agent, and a charge control agent do not necessarily have to be mixed when forming particles in the aqueous phase. It may be added. For example, after forming particles containing no colorant, the colorant can be added by a known dyeing method.

The dispersion method is not particularly limited, and known equipment such as a low-speed shear method, a high-speed shear method, a friction method, a high-pressure jet method, and an ultrasonic wave can be applied. In order to make the particle size of the dispersion 2 to 20 μm, a high-speed shearing type is preferable.
When a high-speed shearing disperser is used, the rotational speed is not particularly limited, but is usually 1000 to 30000 rpm, preferably 5000 to 20000 rpm. The dispersion time is not particularly limited, but in the case of a batch method, it is usually 0.1 to 5 minutes. The temperature during dispersion is usually 0 to 150 ° C. (under pressure), preferably 40 to 98 ° C. Higher temperatures are preferred in that the dispersion of the polyester prepolymer (A) has a low viscosity and is easy to disperse.

The amount of the aqueous medium used relative to 100 parts by weight of the solid component contained in the organic solvent phase of the polyester prepolymer (A) is usually 50 to 2000 parts by weight, preferably 100 to 1000 parts by weight. If the amount is less than 50 parts by weight, the dispersion state of the toner composition is poor, and toner particles having a predetermined particle diameter cannot be obtained. If it exceeds 2000 parts by weight, it is not economical.
Moreover, a dispersing agent can also be used as needed. It is preferable to use a dispersant because the particle size distribution becomes sharp and the dispersion is stable.

  As a dispersant for emulsifying and dispersing the organic solvent phase containing the polyester prepolymer (A), an anionic surfactant such as alkylbenzene sulfonate, α-olefin sulfonate, phosphate ester, alkylamine salt, Amino alcohol fatty acid derivatives, polyamine fatty acid derivatives, amine salt types such as imidazoline, and quaternary alkyltrimethylammonium salts, dialkyldimethylammonium salts, alkyldimethylbenzylammonium salts, pyridinium salts, alkylisoquinolinium salts, benzethonium chloride, etc. Nonionic surfactants such as ammonium salt type cationic surfactants, fatty acid amide derivatives, polyhydric alcohol derivatives, such as alanine, dodecyldi (aminoethyl) glycine, di (octylaminoethyl) glycine and N-alkyl -N, amphoteric surfactants such as N- dimethyl ammonium betaine.

  Further, by using a surfactant having a fluoroalkyl group, the effect can be obtained in a very small amount. Preferred anionic surfactants having a fluoroalkyl group include fluoroalkyl carboxylic acids having 2 to 10 carbon atoms and metal salts thereof, disodium perfluorooctanesulfonyl glutamate, 3- [omega-fluoroalkyl (C6 to C11). Oxy] -1-alkyl (C3-C4) sodium sulfonate, 3- [omega-fluoroalkanoyl (C6-C8) -N-ethylamino] -1-propanesulfonic acid sodium, fluoroalkyl (C11-C20) carboxylic acid And metal salts, perfluoroalkyl carboxylic acids (C7 to C13) and metal salts thereof, perfluoroalkyl (C4 to C12) sulfonic acids and metal salts thereof, perfluorooctane sulfonic acid diethanolamide, N-propyl-N- (2 Hydroxyethyl) -Fluorooctanesulfonamide, perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salt, perfluoroalkyl (C6-C10) -N-ethylsulfonylglycine salt, monoperfluoroalkyl (C6-C16) ethyl phosphate, etc. Is mentioned.

  Product names include Surflon S-111, S-112, S-113 (Asahi Glass Co., Ltd.), Florard FC-93, FC-95, FC-98, FC-129 (Sumitomo 3M Co., Ltd.), Unidyne DS-101. DS-102 (Daikin Kogyo Co., Ltd.), Mega-Fac F-l0, F-l20, F-113, F-191, F-812, F-833 (Dainippon Ink Co., Ltd.), Xtop EF-102 , 103, 104, 105, 112, 123A, 123B, 306A, 501, 201, 204 (manufactured by Tochem Products), and Fgentent F-100, F-150 (manufactured by Neos).

  Cationic surfactants include aliphatic primary, secondary or secondary amine acids having a fluoroalkyl group, aliphatic quaternary ammonium salts such as perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salts, benzalco Nitrogen salts, benzethonium chloride, pyridinium salts, imidazolinium salts, trade names include Surflon S-121 (manufactured by Asahi Glass), Florard FC-135 (manufactured by Sumitomo 3M), Unidyne DS-202 (manufactured by Daikin Industries), Megafac F-150, F-824 (manufactured by Dainippon Ink, Inc.), Xtop EF-132 (manufactured by Tochem Products), and Footgent F-300 (manufactured by Neos) are listed.

  Further, tricalcium phosphate, calcium carbonate, titanium oxide, colloidal silica, hydroxyapatite and the like can be used as an inorganic compound dispersant which is hardly soluble in water.

Further, the dispersed droplets may be stabilized by a polymer protective colloid. For example, acrylic acid, methacrylic acid, α-cyanoacrylic acid, α-cyanomethacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid or maleic anhydride or other (meth) acrylic monomer containing a hydroxyl group, For example, β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, β-hydroxypropyl acrylate, β-hydroxypropyl methacrylate, γ-hydroxypropyl acrylate, γ-hydroxypropyl methacrylate, 3-chloro-2-acrylate -Hydroxypropyl, 3-chloro-2-hydroxypropyl methacrylate, diethylene glycol monoacrylate, diethylene glycol monomethacrylate, glycerol monoacrylate, glycerol monomethacrylate, N -Methylol acrylamide, N-methylol methacrylamide, etc., vinyl alcohol or ethers with vinyl alcohol, such as vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether, etc., or esters of compounds containing vinyl alcohol and carboxyl groups, such as Vinyl acetate, vinyl propionate, vinyl butyrate, etc., acrylamide, methacrylamide, diacetone acrylamide or their methylol compounds, acid chlorides such as acrylic acid chloride, methacrylic acid chloride, vinyl pyridine, vinyl pyrrolidone, vinyl imidazole, ethyleneimine, etc. Homopolymers or copolymers such as those having a nitrogen atom or a heterocyclic ring thereof, polyoxyethylene, polyoxypropylene, Oxyethylene alkylamine, polyoxypropylene alkylamine, polyoxyethylene alkylamide, polyoxypropylene alkylamide, polyoxyethylene nonyl phenyl ether, polyoxyethylene lauryl phenyl ether, polyoxyethylene stearyl phenyl ester, polyoxyethylene nonyl phenyl ester Polyoxyethylenes such as, celluloses such as methyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose can be used.
In addition, when an acid such as calcium phosphate salt or an alkali-soluble substance is used as the dispersion stabilizer, the calcium phosphate salt is removed from the fine particles by a method such as dissolving the calcium phosphate salt with an acid such as hydrochloric acid and washing with water. To do. It can also be removed by operations such as enzymatic degradation.

  When a dispersant is used, the dispersant may remain on the surface of the toner particles, but it is preferable from the charged surface of the toner that the dispersant is washed and removed after the elongation and / or crosslinking reaction.

  The elongation and / or cross-linking reaction time is selected depending on the reactivity of the isocyanate group structure of the prepolymer (A) and the amines (B), but is usually 10 minutes to 40 hours, preferably 2 to 24 hours. is there. The reaction temperature is generally 0 to 150 ° C, preferably 40 to 98 ° C. Moreover, a well-known catalyst can be used as needed. Specific examples include dibutyltin laurate and dioctyltin laurate.

  In order to remove the organic solvent from the obtained emulsified dispersion, a method in which the temperature of the entire system is gradually raised to completely evaporate and remove the organic solvent in the droplets can be employed. Alternatively, the emulsified dispersion can be sprayed into a dry atmosphere to completely remove the water-insoluble organic solvent in the droplets to form toner fine particles, and the aqueous dispersant can be removed by evaporation. . As a dry atmosphere in which the emulsified dispersion is sprayed, a gas obtained by heating air, nitrogen, carbon dioxide gas, combustion gas, or the like, in particular, various air currents heated to a temperature equal to or higher than the boiling point of the highest boiling solvent used is generally used. Sufficient quality can be obtained with a short treatment such as spray dryer, belt dryer or rotary kiln.

  When the particle size distribution at the time of emulsification dispersion is wide and washing and drying processes are performed while maintaining the particle size distribution, the particle size distribution can be adjusted by classifying into a desired particle size distribution.

In the classification operation, the fine particle portion can be removed in the liquid by a cyclone, a decanter, centrifugation, or the like. Of course, the classification operation may be performed after obtaining the powder as a powder after drying. The unnecessary fine particles or coarse particles obtained can be returned to the kneading step and used for the formation of particles. At that time, fine particles or coarse particles may be wet.
The dispersant used is preferably removed from the obtained dispersion as much as possible, but it is preferable to carry out it simultaneously with the classification operation described above.

  Mixing or giving mechanical impact force to the powder mixture after drying with different types of particles such as release agent fine particles, charge control fine particles, fluidizing agent fine particles, and colorant fine particles By immobilizing and fusing on the surface, it is possible to prevent detachment of foreign particles from the surface of the resulting composite particle.

  Specific means include a method of applying an impact force to the mixture by blades rotating at high speed, a method of injecting and accelerating the mixture in a high-speed air stream, and causing particles or composite particles to collide with an appropriate collision plate, etc. is there. As equipment, Ong mill (manufactured by Hosokawa Micron Co., Ltd.), I-type mill (manufactured by Nippon Pneumatic Co., Ltd.) has been modified to reduce the pulverization air pressure, hybridization system (manufactured by Nara Machinery Co., Ltd.), kryptron System (manufactured by Kawasaki Heavy Industries, Ltd.), automatic mortar, etc.

[Application of external additives]
The white particles (toner base material) obtained in the present invention can be used as a toner per se, but preferably, an external additive is applied. As the external additive for assisting the fluidity, developability and chargeability of the toner, inorganic fine particles can be preferably used. The primary particle diameter of the inorganic fine particles is preferably 5 nm to 2 m, and particularly preferably 5 nm to 500 nm. Moreover, it is preferable that the specific surface area by BET method is 20-500 m < ² > / g. The proportion of the inorganic fine particles used is preferably 0.01 to 5% by weight of the toner, and particularly preferably 0.01 to 2.0% by weight.

  Specific examples of the inorganic fine particles include, for example, silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, tin oxide, quartz sand, clay, mica, wollastonite, diatomaceous earth. Examples include soil, chromium oxide, cerium oxide, bengara, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, and silicon nitride.

  Other polymer fine particles, for example, polystyrene obtained by soap-free emulsion polymerization, suspension polymerization, dispersion polymerization, methacrylic acid ester, acrylic acid ester copolymer, polycondensation system such as silicone, benzoguanamine, nylon, thermosetting resin And polymer particles.

  Such a fluidizing agent can be surface-treated to increase hydrophobicity and prevent deterioration of flow characteristics and charging characteristics even under high humidity. For example, silane coupling agents, silylating agents, silane coupling agents having an alkyl fluoride group, organic titanate coupling agents, aluminum coupling agents, silicone oils, modified silicone oils and the like are preferable surface treatment agents. .

  On the other hand, examples of the cleaning property improver for removing the developer after transfer remaining on the photoreceptor and the primary transfer medium include fatty acid metal salts such as zinc stearate, calcium stearate and stearic acid, such as polymethyl methacrylate fine particles, polystyrene. Examples thereof include fine polymer particles produced by soap-free emulsion polymerization of fine particles and the like. The polymer fine particles preferably have a relatively narrow particle size distribution and a volume average particle size of 0.01 to 1 μm.

[Toner shape, etc.]
<Circularity and circularity distribution>
It is important that the toner in the present invention has a specific shape and shape distribution. An toner having an average circularity of less than 0.90 and an irregular shape that is too far from a spherical shape exhibits satisfactory transferability and dust. A high-quality image with no image cannot be obtained. As a method for measuring the shape, an optical detection band method is suitable in which a suspension containing particles is passed through an imaging unit detection band on a flat plate, and a particle image is optically detected and analyzed by a CCD camera. Toner having an average circularity of 0.975 to 0.900, which is a value obtained by dividing the perimeter of an equivalent circle having the same projected area obtained by this method by the perimeter of the actual particle, has a high density with a reproducibility of an appropriate density. It was found to be effective for forming a clear image. More preferably, particles having an average circularity of 0.970 to 0.950 and a circularity of less than 0.94 are 15% or less. Further, when the average circularity is 0.975 or more, in a system that employs blade cleaning or the like, a cleaning failure occurs on the photosensitive member or the transfer belt, causing stain on the image. For example, development / transfer with a low image area ratio results in a small amount of residual toner and poor cleaning does not become a problem. The image-formed toner may be generated as a transfer residual toner on the photosensitive member, and if accumulated, the image may be soiled. In addition, the charging roller that contacts and charges the photosensitive member is contaminated, and the original charging ability cannot be exhibited. This value was measured as an average circularity by a flow type particle image analyzer FPIA-2100 (manufactured by Toa Medical Electronics Co., Ltd.). A specific measurement method will be described later.

<Volume average particle diameter, number average particle diameter>
The toner of the present invention preferably has a volume average particle diameter (Dv) of 3 to 9 μm, and more preferably 5 to 8 μm. The ratio (Dv / Dn) of the volume average particle diameter (Dv) to the number average particle diameter (Dn) is 1.25 or less, preferably 1.10 to 1.20. Here, the volume average particle diameter (Dv) is defined as Dv = [Σ (nD ³ ) / Σn] ^1/3 (where n is the number of particles and D is the particle diameter).
In the present invention, by setting the value of (Dv / Dn) within the above range, it is excellent in heat resistant storage stability, low-temperature fixability, and hot offset resistance, and particularly when used in a full-color copying machine or the like. In the two-component developer, even if the toner balance for a long time is performed, the fluctuation of the toner particle diameter in the developer is reduced, and the development is stable and stable even with long-term stirring in the developing device. Sex is obtained. Even when used as a one-component developer, even if the balance of the toner is performed, the fluctuation of the toner particle diameter is reduced, and the toner is filmed on the developing roller and the toner is made thin. The toner is not fused to a member such as a blade, and good and stable developability and an image can be obtained even in the long-term use (stirring) of the developing device.

In general, it is said that the smaller the particle size of the toner, the more advantageous it is to obtain a high-resolution and high-quality image, but it is disadvantageous for transferability and cleaning properties. is there. Further, when the volume average particle diameter is smaller than the range of the present invention, in the case of the two-component developer, the toner is fused to the surface of the carrier during a long period of stirring in the developing device, and the charging ability of the carrier is reduced, or the one-component development When used as an agent, toner filming on the developing roller and toner fusion to a member such as a blade for thinning the toner are likely to occur. Further, these phenomena are the same for the toner having a fine powder content larger than the range of the present invention.
On the contrary, when the particle diameter of the toner is larger than the range of the present invention, it becomes difficult to obtain a high resolution and high quality image, and when the balance of the toner in the developer is performed, In many cases, the variation of the particle size becomes large. It was also clarified that the same applies when the volume average particle diameter / number average particle diameter (Dv / Dn) is too large. Further, if the volume average particle diameter / number average particle diameter (Dv / Dn) is too small, there are preferable aspects from the viewpoint of stabilizing the behavior of the toner and uniformizing the charge amount, but the toner becomes insufficiently charged. In some cases, it was also found that the cleaning property may be deteriorated.
The volume average particle size / number average particle size (Dv / Dn) was measured using a particle size measuring device “Coulter Counter TAII” manufactured by Coulter Electronics Co., Ltd., with a volume average particle size (Dv ) And the number average particle diameter (Dn).

  As the storage elastic modulus of the toner, the temperature (TG ′) at which the measurement frequency is 20 Hz becomes 1000 Pa is usually 100 ° C. or higher, preferably 110 to 200 ° C. If it is less than 100 ° C., the resistance to hot offset deteriorates. As the viscosity of the toner, the temperature (Tη) at 100 Pa · s at a measurement frequency of 20 Hz is usually 180 ° C. or lower, preferably 90 to 160 ° C. If it exceeds 180 ° C., the low-temperature fixability deteriorates. That is, TG ′ is preferably higher than Tη from the viewpoint of achieving both low temperature fixability and hot offset resistance. In other words, the difference between TG ′ and Tη (TG′−Tη) is preferably 0 ° C. or more. More preferably, it is 10 degreeC or more, Most preferably, it is 20 degreeC or more. The upper limit of the difference is not particularly limited. Further, from the viewpoint of achieving both heat-resistant storage stability and low-temperature fixability, the difference between Tη and Tg is preferably 0 to 100 ° C. More preferably, it is 10-90 degreeC, Most preferably, it is 20-80 degreeC.

[Carrier for two-component developer]
When the toner of the present invention is used for a two-component developer, it may be used by mixing with a magnetic carrier. The carrier to toner content ratio in the developer is 1 to 10 weights of toner with respect to 100 parts by weight of carrier. Part is preferable, and the range of 3 to 9 parts by weight is more preferable.
As the magnetic carrier, conventionally known ones such as iron powder, ferrite powder, magnetite powder, magnetic resin carrier having a particle diameter of about 20 to 200 μm can be used.
Examples of the coating material include amino resins such as urea-formaldehyde resin, melamine resin, benzoguanamine resin, urea resin, polyamide resin, and epoxy resin. Polyvinyl and polyvinylidene resins such as acrylic resins, polymethyl methacrylate resins, polyacrylonitrile resins, polyvinyl acetate resins, polyvinyl alcohol resins, polyvinyl butyral resins, polystyrene resins and styrene acrylic copolymer resins, Halogenated olefin resins such as vinyl, polyester resins such as polyethylene terephthalate resin and polybutylene terephthalate resin, polycarbonate resins, polyethylene resins, polyvinyl fluoride resins, polyvinylidene fluoride resins, polytrifluoroethylene resins, polyhexafluoropropylene resins , Copolymers of vinylidene fluoride and acrylic monomers, copolymers of vinylidene fluoride and vinyl fluoride, tetrafluoroethylene and vinyl Fluoro terpolymers, and silicone resins terpolymers etc. of vinylidene fluoride and non-fluorinated monomer.
Moreover, you may contain electrically conductive powder etc. in coating resin as needed. As the conductive powder, metal powder, carbon black, titanium oxide, tin oxide, zinc oxide or the like can be used. These conductive powders preferably have an average particle diameter of 1 μm or less. When the average particle diameter is larger than 1 μm, it becomes difficult to control electric resistance. The toner of the present invention can also be used as a one-component magnetic toner that does not use a carrier or a non-magnetic toner.

(Image forming method)
Next, an image forming method using the white toner of the present invention will be described.
The image forming method of the present invention forms a full color image containing yellow toner, magenta toner, cyan toner, and black toner on a transparent film by an electrophotographic method, and is a surface opposite to the image forming surface of the full color image. Image formation in which a solid image of white toner is formed using the white toner for developing an electrostatic charge image of the present invention on the uppermost surface of the image forming surface (that is, on the formed full color image) in order to view the image from the side In the above image formation, a full-color image may be formed first on a transparent film, and then a solid image of white toner may be formed on the full-color image. The solid image may be formed, and then a full color image may be formed on the solid image.
The formation of a full-color image has at least an electrostatic charge image formation process, a development process, a transfer process, a fixing process, and a cleaning process using yellow, magenta, cyan, and black toners on a transparent film. Accordingly, the image is formed using a full-color image forming apparatus having other processes such as a static elimination process, a recycling process, and a control process.
Next, a solid image of white toner is formed using the white toner of the present invention on the entire image forming surface of the transparent film on which the obtained full-color image is formed, using another image forming apparatus.
On the other hand, when transferring the image on the transfer belt onto the transparent film, for example, an image forming apparatus having a five-color developing unit is used as described later, and the white color is first formed on the transfer belt. In this method, a solid image of toner is formed, a full-color image is sequentially formed on the solid image using black, cyan, magenta, and yellow toner, and then transferred from the full-color image forming surface onto a transparent film.
By forming in this way, it is possible to see a full color image with good contrast by viewing the image from the side opposite to the image forming surface of the full color image.

  Hereinafter, as a mode for carrying out image formation according to the present invention, a case where image formation is performed will be described with reference to the image forming apparatus of FIG. An image forming apparatus 100 shown in FIG. 1 includes a photosensitive drum 10 as an electrostatic latent image carrier, a charging roller 20 as a charging unit, exposure 30 by an exposure unit as an exposure unit, and a developing unit as a developing unit. 40, an intermediate transfer member 50, a cleaning blade 60 as a cleaning means, and a static elimination lamp 70 as a static elimination means.

  The intermediate transfer member 50 is an endless belt, and is designed so as to be movable in the direction of the arrow in the figure by three rollers 51 that are arranged on the inner side and stretch the belt. Part of the three rollers 51 also functions as a transfer bias roller that can apply a predetermined transfer bias (primary transfer bias) to the intermediate transfer member 50. The intermediate transfer member 50 is provided with a cleaning blade 90 in the vicinity thereof, and the transfer capable of applying a transfer bias for transferring (secondary transfer) a visible image (toner image) to the recording medium 95. A transfer roller 80 serving as a means is arranged to face. Around the intermediate transfer member 50, a corona charger 58 for applying a charge to the toner image on the intermediate transfer member 50 is connected to the electrostatic latent image carrier 10 and the intermediate transfer member in the rotation direction of the intermediate transfer member 50. It is disposed between the contact portion with the body 50 and the contact portion between the intermediate transfer member 50 and the recording medium 95.

  The developing device 40 includes a developing belt 41 as a developer carrying member, and a black developing unit 45K, a yellow developing unit 45Y, a magenta developing unit 45M, and a cyan developing unit 45C provided around the developing belt 41. The black developing unit 45K includes a developer accommodating portion 42K, a developer supplying roller 43K, and a developing roller 44K. The yellow developing unit 45Y includes a developer accommodating portion 42Y, a developer supplying roller 43Y, and a developing roller 44Y. The magenta developing unit 45M includes a developer accommodating portion 42M, a developer supplying roller 43M, and a developing roller 44M, and the cyan developing unit 45C includes a developer accommodating portion 42C and a developer supplying roller 43C. And a developing roller 44C. Further, the developing belt 41 is an endless belt, is rotatably stretched by a plurality of belt rollers, and a part thereof is in contact with the electrostatic latent image carrier 10.

  In the image forming apparatus 100 shown in FIG. 1, for example, the charging roller 20 charges the photosensitive drum 10 uniformly. The exposure device performs imagewise exposure 30 on the photosensitive drum 10 to form an electrostatic latent image. The electrostatic latent image formed on the photosensitive drum 10 is developed by supplying toner from the developing device 40 to form a toner image. The toner image is transferred (primary transfer) onto the intermediate transfer member 50 by the voltage applied from the roller 51 and further transferred (secondary transfer) onto the recording medium 95. As a result, a transfer image is formed on the recording medium 95. The residual toner on the electrostatic latent image carrier 10 is removed by the cleaning blade 60, and the charge on the electrostatic latent image carrier 10 is once removed by the static elimination lamp 70.

  Another mode for carrying out the image forming method of the present invention will be described with reference to the image forming apparatus of FIG. The image forming apparatus 100 shown in FIG. 2 does not include the developing belt 41 as the developer carrying member in the image forming apparatus 100 shown in FIG. 1, and the black developing unit 45 </ b> K is disposed around the electrostatic latent image carrying member 10. 1 except that the yellow developing unit 45Y, the magenta developing unit 45M, and the cyan developing unit 45C are directly opposed to each other, and have the same functions and effects as the image forming apparatus 100 shown in FIG. Show. In FIG. 2, the same components as those in FIG. 1 are denoted by the same reference numerals.

  Another embodiment for carrying out the image forming method of the present invention will be described with reference to FIG. A tandem image forming apparatus 100 shown in FIG. 3 is a tandem color image forming apparatus. The tandem image forming apparatus 120 includes a copying apparatus main body 150, a paper feed table 200, a scanner 300, and an automatic document feeder (ADF) 400.

The copying apparatus main body 150 is provided with an endless belt-like intermediate transfer member 50 at the center. The intermediate transfer member 50 is stretched around the support rollers 14, 15 and 16, and can be rotated clockwise in FIG. 3. In the vicinity of the support roller 15, an intermediate transfer member cleaning unit 17 for removing residual toner on the intermediate transfer member 50 is disposed. A tandem in which four image forming units 18 of yellow, cyan, magenta, and black are arranged to face each other on the intermediate transfer member 50 stretched between the support roller 14 and the support roller 15 along the conveyance direction. A mold developing device 120 is disposed. An exposure unit 21 is disposed in the vicinity of the tandem developing device 120. On the opposite side of the intermediate transfer member 50 from the side where the tandem developing device 120 is arranged, the secondary transfer unit 22 is arranged. In the secondary transfer unit 22, a secondary transfer belt 24, which is an endless belt, is stretched around a pair of rollers 23, and the recording medium conveyed on the secondary transfer belt 24 and the intermediate transfer member 50 are in contact with each other. Is possible. A fixing unit 25 is disposed in the vicinity of the secondary transfer unit 22.
In the tandem image forming apparatus 100, a reversing device 28 for reversing the recording medium in order to form an image on both sides of the recording medium is disposed in the vicinity of the secondary transfer unit 22 and the fixing unit 25. .

  Next, formation of a full-color image (color copy) using the tandem developing device 120 will be described. That is, first, a document is set on the document table 130 of the automatic document feeder (ADF) 400, or the automatic document feeder 400 is opened and the document is set on the contact glass 32 of the scanner 300. 400 is closed.

  When a start switch (not shown) is pressed, when the document is set on the automatic document feeder 400, the document is transported and moved onto the contact glass 32, and then the document is set on the contact glass 32. Immediately after that, the scanner 300 is driven, and the first traveling body 33 and the second traveling body 34 travel. At this time, light from the light source is emitted from the first traveling body 33 and reflected light from the document surface is reflected by the mirror in the second traveling body 34 and is received by the reading sensor 36 through the imaging lens 35 to be color. An original (color image) is read and used as black, yellow, magenta, and cyan image information.

  Each image information of black, yellow, magenta and cyan is stored in each image forming unit 18 (black image forming unit, yellow image forming unit, magenta image forming unit, and cyan image forming unit) in the tandem type developing device 120. Each image forming unit forms black, yellow, magenta, and cyan toner images. That is, each image forming means 18 (black image forming means, yellow image forming means, magenta image forming means, and cyan image forming means) in the tandem type developing device 120 is a static image as shown in FIG. An electrostatic latent image carrier 10 (black electrostatic latent image carrier 10K, yellow electrostatic latent image carrier 10Y, magenta electrostatic latent image carrier 10M, and cyan electrostatic latent image carrier 10C); A charger 60 that uniformly charges the electrostatic latent image carrier, and the electrostatic latent image carrier is exposed like an image corresponding to each color image based on each color image information (L in FIG. 4). An exposure device for forming an electrostatic latent image corresponding to each color image on the electrostatic latent image carrier, and each color toner (black toner, yellow toner, magenta toner, and cyan toner) for the electrostatic latent image. Use and develop each color A developer 61 for forming a toner image by the toner, a transfer charger 62 for transferring the toner image onto the intermediate transfer member 50, a cleaning means 63, and a charge eliminator 64. Each monochrome image (black image, yellow image, magenta image, and cyan image) can be formed based on the image information. The black image, the yellow image, the magenta image, and the cyan image formed in this manner are respectively transferred to the black electrostatic latent image carrier 10K on the intermediate transfer member 50 that is rotationally moved by the support rollers 14, 15 and 16. Black image formed on top, yellow image formed on electrostatic latent image carrier 10Y for yellow, magenta image formed on electrostatic latent image carrier 10M for magenta, and electrostatic latent image carrier for cyan The cyan image formed on 10C is sequentially transferred (primary transfer). Then, the black image, the yellow image, the magenta image, and the cyan image are superimposed on the intermediate transfer member 50 to form a composite color image (color transfer image).

  On the other hand, in the paper feed table 200, one of the paper feed rollers 142 is selectively rotated to feed the recording medium from one of the paper feed cassettes 144 provided in multiple stages in the paper bank 143, and one sheet at a time by the separation roller 145. The paper is separated and sent to the paper feed path 146, transported by the transport roller 147, guided to the paper feed path 148 in the copying machine main body 150, and abutted against the registration roller 49 to stop. Alternatively, the recording roller 142 is rotated to feed out the recording medium on the manual feed tray 54, separated one by one by the separation roller 52, put into the manual feed path 53, and abutted against the registration roller 49 and stopped. The registration roller 49 is generally used while being grounded, but may be used in a state where a bias is applied to remove paper dust from the recording medium. Then, the registration roller 49 is rotated in synchronization with the synthesized color image (color transfer image) synthesized on the intermediate transfer member 50, and the recording medium is sent between the intermediate transfer member 50 and the secondary transfer unit 22. Then, by transferring (secondary transfer) the composite color image (color transfer image) onto the recording medium by the secondary transfer means 22, a color image is transferred and formed on the recording medium. The residual toner on the intermediate transfer member 50 after image transfer is cleaned by the intermediate transfer member cleaning means 17.

  The recording medium on which the color image has been transferred is conveyed by the secondary transfer means 22 and sent to the fixing means 25, where the combined color image (color transfer image) is generated by heat and pressure. Is fixed on the recording medium. After that, the recording medium is switched by the switching claw 55 and discharged by the discharge roller 56 and stacked on the paper discharge tray 57. Alternatively, the recording medium is switched by the switching claw 55 and reversed by the reversing device 28 and led again to the transfer position. After the image is also recorded on the back surface, the image is discharged by the discharge roller 56 and stacked on the discharge tray 57.

  Next, the case of forming an image with white toner on the back surface of a full color image will be described. For example, the image forming apparatus including a developing unit of five colors can be used. FIG. 5 shows an outline of an image forming apparatus having a five-color developing unit. The developing unit 35 is formed with white toner, the developing unit 36 is black toner, the developing unit 37 is cyan toner, the developing unit 38 is magenta toner, and the developing unit 39 is yellow toner, and is transferred to the intermediate transfer belt 40. Create an image. The image formed on the intermediate transfer belt 40 is transferred to a transparent film or the like by the transfer device 41 and fixed by the fixing device 43. In the case of FIG. 5, since a white toner layer is formed on the uppermost surface of the image forming surface, a full color image can be viewed from the film surface where no image is formed. On the other hand, in the case of black paper or colored paper, since it is desired to provide a white toner layer on the base, it is necessary to change the position of the developing unit. The white developing unit 35 is installed at the place of the yellow developing unit 39, and the other developing units move in the direction of the place where the white developing unit 35 was located.

  The image forming of the present invention can be performed by the image forming apparatus having the five color developing units as described above, but the full color image and the white image may be formed by separate machines. Absent. For example, a color image may be formed by a full-color MFP currently on the market, and the white toner of the present invention may be formed by a monochrome MFP currently on the market. In this case, the existing model is remodeled, which is advantageous in terms of development costs. Further, since the white toner image is formed by another machine, when the image is formed on the color image, the white toner is transferred to the fixed image, so that the toner is not mixed. On the other hand, when the image is formed on the white image in the opposite case, the color toner is transferred onto the fixed white toner, so that the toner is not mixed in this case. On the other hand, in the case of FIG. 5, since unfixed toner is transferred in a superimposed manner, care must be taken in transferring and fixing so that the toner is not mixed. In particular, white toner has high concealability, and therefore, when toner is mixed, it has a great influence on color development. Note that the MFP is a multifunction machine in which a FAX and a printer function are added to a copying machine.

(Process cartridge)
The process cartridge of the present invention integrally supports an electrostatic charge image carrier and at least developing means for developing the electrostatic image formed on the carrier using toner to form a visible image. A process cartridge which is detachable from the apparatus main body, and uses the white toner for developing an electrostatic charge image of the present invention as the toner. The process cartridge of the present invention may further integrally support other means appropriately selected as necessary.

  FIG. 6 shows an example of the process cartridge of the present invention. The process cartridge includes a photosensitive member 101 and includes a charging device 102, an exposure device 103, a developing device 104, a transfer device 106, and a cleaning device 107. Each of these members can be the same as the above-described image forming apparatus.

  EXAMPLES The present invention will be further described below with reference to examples, but the present invention is not limited thereto. In the following, “parts” means parts by weight, and “%” means percent by weight.

(Measuring method)
-Isocyanate group content The isocyanate group content was measured using the method defined in JIS K1603.

-Acid value The acid value (mgKOH / g) was measured using the method prescribed | regulated to JISK0070. However, when the sample does not dissolve, a solvent such as dioxane or THF can be used as the solvent.

-Hydroxyl value The measuring method of a hydroxyl value (mgKOH / g) is based on the method prescribed | regulated to JISK0070. However, when the sample does not dissolve, a solvent such as dioxane or THF is used as the solvent.

-Molecular weight It measured using GPC.
In addition, when measuring the molecular weight of the prepolymer having an isocyanate group, a sample in which the isocyanate group was sealed was prepared by adding 3-fold equivalent of dibutylamine to the isocyanate group, and used for GPC measurement. .

・ Glass transition temperature Tg
It measured using TG-DSC system TAS-100 (made by Rigaku Corporation).

[Example 1]
~ Synthesis of organic fine particle emulsion ~
In a reaction vessel equipped with a stir bar and a thermometer, 683 parts of water, 11 parts of sodium salt of ethylene oxide methacrylate adduct sulfate (Eleminol RS-30, manufactured by Sanyo Chemical Industries), 80 parts of styrene, 83 parts of methacrylic acid Then, 110 parts of butyl acrylate, 12 parts of butyl thioglycolate, and 1 part of ammonium persulfate were charged and stirred at 400 rpm for 15 minutes to obtain a white emulsion. The system was heated to raise the temperature in the system to 75 ° C. and reacted for 5 hours. Further, 30 parts of a 1% ammonium persulfate aqueous solution was added, and the mixture was aged at 75 ° C. for 5 hours, and an aqueous vinyl resin (a copolymer of styrene-methacrylic acid-butyl acrylate-methacrylic acid ethylene oxide adduct sulfate sodium salt). A dispersion was obtained. This is designated as [fine particle dispersion 1]. The volume average particle size of the [fine particle dispersion 1] measured with a laser diffraction particle size distribution analyzer (LA-920, manufactured by Shimadzu Corporation) was 120 nm. A portion of [Fine Particle Dispersion 1] was dried to isolate the resin component. The Tg of the resin was 42 ° C., and the weight average molecular weight was 30,000.

~ Preparation of aqueous phase ~
990 parts of water, 65 parts of [fine particle dispersion 1], 37 parts of 48.5% aqueous solution of sodium dodecyl diphenyl ether disulfonate (Eleminol MON-7, Sanyo Kasei Kogyo Co., Ltd.) and 90 parts of ethyl acetate are mixed and stirred to give a milky white liquid. Got. This is designated as [Aqueous Phase 1].

~ Synthesis of low molecular weight polyester ~
In a reaction vessel equipped with a condenser, a stirrer and a nitrogen inlet tube, 229 parts of bisphenol A ethylene oxide 2-mole adduct, 529 parts of bisphenol A propylene oxide 3-mole adduct, 208 parts terephthalic acid, 46 parts adipic acid and dibutyl Add 2 parts of tin oxide, react at normal pressure and 230 ° C for 8 hours, and further react for 5 hours at 10-15 mmHg reduced pressure. Then, add 44 parts of trimellitic anhydride to the reaction vessel at 180 ° C and normal pressure. The mixture was reacted for 2 hours to obtain [Low molecular weight polyester 1]. [Low molecular polyester 1] had a number average molecular weight of 2500, a weight average molecular weight of 6700, a Tg of 43 ° C., and an acid value of 25.

~ Synthesis of intermediate polyester ~
In a reaction vessel equipped with a cooling pipe, a stirrer and a nitrogen introduction pipe, 682 parts of bisphenol A ethylene oxide 2-mole adduct, 81 parts of bisphenol A propylene oxide 2-mole adduct, 283 parts of terephthalic acid, trimellitic anhydride 22 And 2 parts of dibutyltin oxide were added, reacted at 230 ° C. for 8 hours at normal pressure, and further reacted for 5 hours at a reduced pressure of 10 to 15 mmHg to obtain [Intermediate Polyester 1]. [Intermediate Polyester 1] had a number average molecular weight of 2,100, a weight average molecular weight of 9,500, Tg of 55 ° C., an acid value of 0.5, and a hydroxyl value of 51.

-Synthesis of a modified polyester resin (referred to as prepolymer 1) capable of reacting with a compound having at least an active hydrogen group-
In a reaction vessel equipped with a cooling tube, a stirrer and a nitrogen introduction tube, 410 parts of the above [intermediate polyester 1], 89 parts of isophorone diisocyanate, and 500 parts of ethyl acetate were added and reacted at 100 ° C. for 5 hours. ] Was obtained. [Prepolymer 1] had a free isocyanate weight% of 1.53%.

~ Synthesis of ketimine ~
In a reaction vessel equipped with a stir bar and a thermometer, 170 parts of isophoronediamine and 75 parts of methyl ethyl ketone were charged and reacted at 50 ° C. for 5 hours to obtain [ketimine compound 1]. The amine value of [ketimine compound 1] was 418.

~ Preparation of oil phase, i.e. toner composition ~
In a container equipped with a stir bar and a thermometer, 400 parts of [Low molecular weight polyester 1], 110 parts of carnauba wax and 947 parts of ethyl acetate were charged, heated to 80 ° C. with stirring, and maintained at 80 ° C. for 5 hours. Thereafter, it was cooled to 30 ° C. in 1 hour. Next, 1500 parts of titanium oxide (Taipeku CR-50-2, manufactured by Ishihara Sangyo Co., Ltd.) and 500 parts of ethyl acetate were charged into the container and mixed for 1 hour to obtain [Material Solution 1].
[Raw material solution 1] 1324 parts are transferred to a container, and using a bead mill (Ultra Visco Mill, manufactured by Imex Co., Ltd.), a liquid feeding speed is 1 kg / hr, a disk peripheral speed is 6 m / sec, and 0.5 mm zirconia beads are 80% by volume. The wax was dispersed under the conditions of filling and 3 passes. Next, 1324 parts of a 65% ethyl acetate solution of [low molecular weight polyester 1] and 34 parts of the above [inorganic fine particles 1] were added, followed by one pass with a bead mill under the above conditions to obtain [Pigment / Wax Dispersion 1]. The solid content concentration of [Pigment / Wax Dispersion 1] (130 ° C., 30 minutes) was 50%.

~ Emulsification ~
[Pigment / Wax Dispersion 1] 648 parts, [Prepolymer 1] 154 parts, [Ketimine Compound 1] 8.5 parts in a container, and TK homomixer (manufactured by Tokushu Kika) at 5,000 rpm for 1 minute After mixing, 1200 parts of [Aqueous Phase 1] was added to the container and mixed with a TK homomixer at a rotation speed of 10,000 rpm for 20 minutes to obtain [Emulsion Slurry 1]. That is, it is dispersed in an aqueous medium containing resin fine particles and an elongation reaction is performed.

~ Solvent removal ~
[Emulsion slurry 1] was put into a container equipped with a stirrer and a thermometer, and after removing the solvent at 30 ° C. for 8 hours, aging was carried out at 45 ° C. for 4 hours to obtain [Dispersion slurry 1].

~ Washing and drying ~
[Dispersion Slurry 1] After filtering 100 parts under reduced pressure,
(1): 100 parts of ion-exchanged water was added to the filter cake, mixed with a TK homomixer (10 minutes at 12,000 rpm), and then filtered.
(2): 100 parts of a 10% aqueous sodium hydroxide solution was added to the filter cake of (1), mixed with a TK homomixer (30 minutes at 12,000 rpm), and then filtered under reduced pressure.
(3): 100 parts of 10% hydrochloric acid was added to the filter cake of (2), mixed with a TK homomixer (rotation speed: 12,000 rpm for 10 minutes), and then filtered.
(4): 300 parts of ion-exchanged water was added to the filter cake of (3), mixed with a TK homomixer (rotation speed: 12,000 rpm for 10 minutes), and then filtered twice to obtain a cake. . This is designated as [filter cake 1].
[Filter cake 1] was dried with a circulating dryer at 45 ° C. for 48 hours. Thereafter, the mixture was sieved with a mesh having an opening of 75 μm to obtain toner base particles. This is designated as [toner base particle 1].

[Example 2]
In the preparation and emulsification of the oil phase of Example 1, that is, the toner composition, 1500 parts of titanium oxide (Taipeku CR-50-2 manufactured by Ishihara Sangyo Co., Ltd.) and 400 parts of titanium oxide (Taipeke CR-60-2 manufactured by Ishihara Sangyo Co., Ltd.) [Toner base particles 2] were obtained in the same manner as in Example 1 except that

[Comparative Example 1]
In the preparation and emulsification of the oil phase of Example 1, that is, the toner composition, 1500 parts of titanium oxide (Taipec CR-50-2 manufactured by Ishihara Sangyo Co., Ltd.) was changed to 1500 parts of titanium oxide (Taipeke R-780 manufactured by Ishihara Sangyo Co., Ltd.). Except for this, [Toner Base Particles 3] were obtained in the same manner as in Example 1.

[Comparative Example 2]
-Example of production of white toner for electrostatic image development by pulverization-
(Synthesis example of polyester resin A)
443 parts of PO adduct of bisphenol A (hydroxyl value 320), 135 parts of diethylene glycol, 422 parts of terephthalic acid, and 2.5 parts of dibutyltin oxide are placed in a reaction vessel equipped with a thermometer, stirrer, cooler and nitrogen introduction tube. Then, the reaction was carried out at 200 ° C. until the acid value reached 10, to obtain [Polyester Resin A]. The resin had a Tg of 63 ° C. and a peak number average molecular weight of 6000.

(Synthesis example of polyester resin B)
443 parts of PO adduct of bisphenol A (hydroxyl value 320), 135 parts of diethylene glycol, 422 parts of terephthalic acid, and 2.5 parts of dibutyltin oxide are placed in a reaction vessel equipped with a thermometer, stirrer, cooler and nitrogen introduction tube. Then, the reaction was carried out at 230 ° C. until the acid value reached 7 to obtain [Polyester Resin B]. The resin had a Tg of 65 ° C. and a peak number average molecular weight of 16000.

(Production of toner base)
Polyester resin A 40 parts Polyester resin B 60 parts Titanium oxide (Taipaque CR-50-2, manufactured by Ishihara Sangyo Co., Ltd.) 30 parts Carnauba wax 5 parts The above toner constituent materials were mixed with a Henschel mixer (Henschel 20B, Mitsui Mining Co., Ltd.) at 1500 rpm 3 minutes) and mixed in a single-screw kneader (Buss small bus co-kneader) under the following conditions (setting temperature: inlet portion 100 ° C., outlet portion 50 ° C., feed amount: 2 kg / Hr). Kneading was performed to obtain [Toner Base 4].
[Toner base 4] is kneaded, cooled by rolling, pulverized by a pulverizer, and further an I-type mill (IDS-2 manufactured by Nippon Pneumatic Co., Ltd., using a flat impingement plate, air pressure: 6.8 atm / cm ² and finely pulverized at a feed rate of 0.5 kg / hr, and further classified (132MP manufactured by Alpine Corporation) to obtain [Mother toner particles 4].

[Comparative Example 3]
Comparative Example 2 except that 30 parts of titanium oxide (Taipeku CR-50-2 manufactured by Ishihara Sangyo Co., Ltd.) was changed to 15 parts of titanium oxide (Taipeke CR-60-2 manufactured by Ishihara Sangyo Co., Ltd.). [Toner base particles 5] were obtained in the same manner as in Example 2.

[Comparative Example 4]
90 parts of styrene, 10 parts of divinylbenzene, and 30 parts of titanium oxide (Taipeku CR-50-2 manufactured by Ishihara Sangyo Co., Ltd.) are dispersed with a TK homomixer (manufactured by Special Machine), and [Polymerizable monomer composition 1] is dispersed. Obtained.
While stirring an aqueous magnesium chloride solution in which 9.8 parts of magnesium chloride is dissolved in 250 parts of ion-exchanged water, an aqueous solution of sodium hydroxide in which 6.9 parts of sodium hydroxide is dissolved in 50 parts of ion-exchanged water is gradually added. A colloidal dispersion 1] of magnesium oxide was prepared.
Into the colloidal dispersion 1 of magnesium hydroxide, the [polymerizable monomer composition 1] is added and stirred, and the polymerization initiator t-butylperoxy-2-ethylhexanoate (Perbutyl O manufactured by Nippon Oil & Fats Co., Ltd.) ) Was added, and then [Emulsion 1 of the polymerizable monomer composition] was formed using an Ebara milder (MDN303V manufactured by Ebara Seisakusho).
Put [Polymerizable monomer composition droplet 1] into a container equipped with a stirrer and thermometer, and control the temperature so that the polymerization addition rate becomes 80% at 80 ° C. After the polymerization addition rate reached 80%, the temperature was further raised, heated at 90 ° C. for 4 hours, and cooled to obtain [Dispersion Slurry 3].
(1): [Dispersion slurry 3] 10% hydrochloric acid was added to 100 parts until the pH reached 6, and the mixture was mixed with a TK homomixer (rotation speed: 12,000 rpm for 10 minutes) and then filtered.
(2): 500 parts of ion-exchanged water was added to the filter cake of (1), mixed with a TK homomixer (10 minutes at 12,000 rpm), and then filtered twice to obtain a cake-like product. . This is designated as [filter cake 3].
[Filter cake 3] was dried at 45 ° C. for 48 hours in a circulating drier. Thereafter, the mixture was sieved with a 75 μm mesh to obtain toner base particles. This is designated as [toner base particle 6].

[Comparative Example 5]
In the polymerizable monomer composition of Comparative Example 4, 30 parts of titanium oxide (Taipeke CR-50-2 manufactured by Ishihara Sangyo Co., Ltd.) was changed to 15 parts of titanium oxide (Taipeke CR-60-2 manufactured by Ishihara Sangyo Co., Ltd.). Except for this, [Toner Base Particles 7] were obtained in the same manner as in Comparative Example 4.

<External additive treatment>
To 100 parts of [toner base particles 1 to 7] obtained above, 1.0 part of hydrophobic silica (HDK2000H: manufactured by Clariant Japan) as an external additive and titanium oxide (JMT-150IB: manufactured by Teica) ) 0.8 part was mixed with a Henschel mixer to obtain a toner. This is referred to as [Toners 1 to 7].

<Example of carrier production>
The raw materials shown below were dispersed with a homomixer for 10 minutes to obtain a blend coating film forming solution of an acrylic resin and a silicone resin containing alumina particles. A fired ferrite powder [(MgO) 1.8 (MnO) 49.5 (Fe ₂ O ₃ ) 48.0: average particle size; 50 μm] was used as the core material, and the coating film forming solution was formed on the surface of the core material. It was applied with a Spira coater (manufactured by Okada Seiko Co., Ltd.) to a thickness of 0.15 μm and dried. The obtained carrier was baked by standing in an electric furnace at 150 ° C. for 1 hour. After cooling, the ferrite powder bulk was crushed using a sieve having an opening of 106 μm to obtain a carrier.
Acrylic resin solution (solid content 50 wt%) ... 21.0 parts guanamine solution (solid content 70 wt%) ... 6.4 parts alumina particles [0.3 μm, specific resistance 10 ¹⁴ (Ω · cm)] ... 7.6 parts silicone resin solution [solid content 23 wt%
(SR2410: manufactured by Toray Dow Corning Silicone Co., Ltd.)], 65.0 parts aminosilane [solid content: 100 wt%
(SH6020: manufactured by Toray Dow Corning Silicone Co., Ltd.)] ... 0.3 parts toluene ... 60 parts butyl cellosolve ... 60 parts

<Developer>
7 parts of the toner and 93 parts of the carrier were stirred for 5 minutes with a tumbler mixer (Willy A. Bachofen AG Machinenfabrik T2F) to prepare a developer.

[Particle characteristics of toner]
As the particle characteristics of the toner, volume average particle diameter (Dv), number average particle diameter (Dn), Dv / Dn, and circularity were measured by the following measurement methods.
(1) Volume average particle diameter (Dv) and (Dv / Dn)
Coulter Electronics' particle size measuring instrument "Coulter Counter TA
II ". Further, (Dv / Dn) was automatically calculated from the above value.
(2) Average circularity The average circularity is measured by a flow type particle image analyzer FPIA-2100 (manufactured by Toa Medical Electronics Co., Ltd.). As a specific measuring method, 0.1 to 0.5 ml of a surfactant, preferably alkylbenzene sulfonate is added as a dispersant to 100 to 150 ml of water from which impure solids have been removed in advance, and further measurement is performed. Add about 0.1-0.5g of sample. The suspension in which the sample is dispersed is obtained by performing dispersion treatment for about 1 to 3 minutes with an ultrasonic disperser and measuring the shape and distribution of the toner with the above apparatus at a dispersion concentration of 3000 to 10,000 / μl. .

The image formation test was performed as follows.
<Imaging device>
In evaluating the white toners of Examples and Comparative Examples, a prototype machine in which a digital full-color copying machine and a digital monochrome copying were connected was manufactured. The digital full-color copier is imgio MP manufactured by Ricoh.
C4500 (evaluation machine A) was used, and the digital nomochrome copying machine was modified from imgio Neo 453 (evaluation machine B) manufactured by Ricoh. The digital full-color copier uses standard full-color toner as it is, and the paper and OHP coming out of the fixing unit are fed to the digital monochrome copier. In addition, Imagio MP made by Ricoh
C4500 full-color toner is a color toner produced by a polymerization method. In the digital monochrome copying machine, the white toners of Examples and Comparative Examples were put and evaluated. The image formation of the white toner was adjusted so that the adhesion amount was about 1.0 mg / cm ^2, and the digital nomograph was set so as to produce a solid image.

<Image creation sample>
As the image forming sample, a full color image was formed on an OHP film, and a white toner was formed on the entire surface. That is, a sample for viewing a full color image from the opposite direction (film side) to the image side on which the white toner was formed was prepared. As the OHP film, 3M CG3700 was used. The full color image was printed with high-definition color digital standard image data (ISO / JIS-SCID sample N5 bicycle).

<Evaluation items and evaluation methods>
(Bending test)
The evaluation machine A prints high-definition color digital standard image data (ISO / JIS-SCID sample N5 bicycle) on an OHP film (CG3700 manufactured by 3M) to form a full-color image, and then the evaluation machine B The strength of an image printed with white toner on one side was evaluated. As a bending test, the OHP was bent so that the toner fixing surface was on the outside, and the curvature Rmm of the OHP when the toner was peeled was measured.

(Rubbing test)
The printed image formed in the same manner as in the bending test was rubbed on the toner fixing surface with a JIS smear cloth (JIS L 0849) using a clock meter (Model 1 manufactured by Atlas Electric Devices) to determine whether the toner was peeled off.

(Charge amount (Q / M))
With the evaluation machine B, the charge amount (Q / M) of the white toner developer after outputting 1,000 image charts with a 5% image area was measured with a blow-off device.

(Whiteness)
An image printed with white toner on one side by the evaluation machine B was placed on black paper, and the whiteness of the image was confirmed.

(Cleanability)
Using the evaluation machine A, the transfer residual toner on the photosensitive member that passed the cleaning process after outputting 100 sheets was transferred to black paper with Scotch tape (manufactured by Sumitomo 3M Co., Ltd.) and measured with a Macbeth reflection densitometer RD514 type. The difference between the blank and the blank is less than 0.005, the evaluation is 0.005 to 0.010, the evaluation is 0.01 to 0.02, the evaluation is Δ, and the evaluation is 0.0. did.

(Dirt)
Evaluator B outputs 1,000 image charts with 5% image area, stops blank image during development, transfers developer on photoconductor after development to black paper, and transfers untransferred tape The difference from the image density was measured by a spectrodensitometer (manufactured by X-Rite) and quantitatively evaluated. The difference was less than 0.30, and the difference was 0.30 or more.

(Fixability)
Using Evaluation Machine A, a solid image and a thick paper transfer paper (made by Ricoh, Type 6200 and NBS Ricoh Copied Printing Paper <135>) with a solid image and a toner adhesion amount of 0.85 ± 0.1 mg / cm ² The fixing was evaluated. A fixing test was performed by changing the temperature of the fixing belt, and an upper limit temperature at which hot offset did not occur on plain paper was defined as an upper limit fixing temperature. Further, the minimum fixing temperature was measured with a thick paper. The lower limit fixing temperature was determined as the fixing lower limit temperature at the fixing roll temperature at which the residual ratio of the image density after rubbing the obtained fixed image with a pad was 70% or more. The upper limit fixing temperature was ◎ for 190 ° C or higher, ○ for 190-180 ° C, △ for 180-170 ° C, and x for 170 ° C or lower. The lower limit fixing temperature was ◎ for 135 ° C. or less, ◯ for 135 to 145 ° C., Δ for 145 to 155 ° C., and × for 155 ° C. or more.

  Table 2 shows the production methods of the toners of Examples and Comparative Examples, the types of titanium dioxide, and the contents in the toner.

  Table 3 shows the particle diameters, circularity, etc. of the toners of Examples and Comparative Examples.

  Table 4 shows the evaluation results by image formation of the toners of Examples and Comparative Examples.

  From the above table, the toner of the example does not peel off even when bent to a small curvature and the strength of the fixed toner layer is higher than that of the toner of the comparative example. Also, from the results of the rubbing test, the toner of the example has a high toner layer strength, the Q / M after image formation of 1000 sheets is also large compared to the toner of the comparative example, and exhibits good chargeability. The white toner has high concealability and has no problem. It can also be seen that both the low-temperature fixability and the offset resistance are good.

1 is a schematic configuration diagram illustrating an example of an image forming apparatus used in the present invention. It is a schematic block diagram which shows the other example of the image forming apparatus used by this invention. It is a schematic block diagram which shows the other example of the image forming apparatus used by this invention. FIG. 4 is a partially enlarged view of FIG. 3. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus capable of forming a white toner image and a full-color image by one machine according to the present invention. It is a schematic block diagram which shows an example of the process cartridge used by this invention.

Explanation of symbols

(About FIGS. 1-4)
10 Photoconductor (Photoconductor drum)
10K black photoconductor 10Y yellow photoconductor 10M magenta photoconductor 10C cyan photoconductor 14 support roller 15 support roller 16 support roller 17 intermediate transfer cleaning device 18 image forming means 20 charging roller 21 exposure device 22 secondary transfer device 23 Roller 24 Secondary transfer belt 25 Fixing device 26 Fixing belt 27 Pressure roller 28 Sheet reversing device 30 Exposure device 32 Contact glass 33 First traveling member 34 Second traveling member 35 Imaging lens 36 Reading sensor 40 Developing device 41 Developing belt 42K Developer container 42Y Developer container 42M Developer container 42C Developer container 43K Developer supply roller 43Y Developer supply roller 43M Developer supply roller 43C Developer supply roller 44K Developer roller 44Y Developer roller 44M Developer Roller 44C Developing roller 45K Black developing unit 45Y Yellow developing unit 45M Magenta developing unit 45C Cyan developing unit 49 Registration roller 50 Intermediate transfer member 51 Roller 52 Separating roller 53 Manual feed path 54 Manual feed tray 55 Switching claw 56 Discharge roller 57 discharge tray 58 corona charger 60 cleaning device 61 developing device 62 transfer charger 63 photoconductor cleaning device 64 static eliminator 70 static eliminator lamp 80 transfer roller 90 cleaning device 95 transfer paper 100 image forming device 120 tandem type developer 130 document table 142 Paper feed roller 143 Paper bank 144 Paper feed cassette 145 Separation roller 146 Paper feed path 147 Transport roller 148 Paper feed path 150 Copier main body 200 Paper feed table 300 Scanner 400 Automatic document transport Feeder (ADF)
(About Figure 5)
DESCRIPTION OF SYMBOLS 1 Paper feeding part 5, 11, 17, 23, 29 Photoconductor 8, 14, 20, 26, 32 Developing device 9, 15, 21, 27, 33 Cleaning device 35 White toner developing unit 36 Black toner developing unit 37 Cyan toner Development unit 38 Magenta toner development unit 39 Yellow toner development unit
40 Intermediate transfer belt 41 Transfer device 43 Fixing device (FIG. 6)
101 photoconductor 102 charging means (charging device)
103 Exposure (exposure equipment)
104 Developing means (developing device)
105 Recording medium 106 Transfer means (transfer device)
107 Cleaning means

Claims (11)

An organic solvent phase in which at least a functional group-containing polyester resin is dissolved, an active hydrogen-containing compound, and a colorant are dispersed in an aqueous medium phase in which resin fine particles are dispersed, and the functional group-containing polyester system is dispersed. An electrostatic charge image developing toner which causes an elongation reaction and / or a crosslinking reaction between a resin and the active hydrogen-containing compound and removes an organic solvent from the obtained dispersion to form a toner base,
A white toner for developing electrostatic images, wherein a polyol-coated titanium oxide pigment is used as the colorant.   In the organic solvent phase, a non-reactive polyester resin is dissolved together with the functional group-containing polyester resin, and the weight ratio of the functional group-containing polyester resin to the non-reactive polyester is 5/95 to 75/25. The white toner for developing an electrostatic charge image according to claim 1, wherein:   3. The white toner for developing electrostatic images according to claim 1, wherein the toner base contains 10 to 30% by weight of a polyol-coated titanium oxide pigment.   The white toner for developing an electrostatic charge image according to any one of claims 1 to 3, wherein the toner base has a volume average particle diameter (Dv) of 3 to 9 µm.   5. The electrostatic charge image developing device according to claim 4, wherein a ratio (Dv / Dn) of a volume average particle diameter (Dv) to a number average particle diameter (Dn) of the toner base is 1.25 or less. White toner.   The white toner for developing an electrostatic charge image according to claim 1, wherein the toner base has an average circularity of 0.900 to 0.980.   Used to whiten the back of a full-color image formed on a transparent film so that a full-color image composed of yellow toner, magenta toner, cyan toner and black toner can be viewed from the side opposite to the image-forming surface. The white toner for developing electrostatic images according to claim 1, wherein   A two-component developer comprising at least a carrier comprising the toner according to claim 1 and magnetic particles.   In order to form a full-color image including yellow toner, magenta toner, cyan toner, and black toner on a transparent film by electrophotography, and to view the full-color image from the side opposite to the image-forming surface, A solid image of white toner is formed on the full-color image on the image forming surface using the white toner for developing an electrostatic charge image according to any one of claims 1 to 6.   Full color image forming means for forming a full color image containing yellow toner, magenta toner, cyan toner, and black toner on a transparent film by electrophotography, and a surface opposite to the image forming surface of the full color image A white toner image forming means for forming a solid image of the white toner for developing an electrostatic charge image according to any one of claims 1 to 6 on the full-color image on the image forming surface for viewing from the side. An image forming apparatus comprising the image forming apparatus.   An electrostatic charge image carrier and a developing unit that develops at least an electrostatic charge image formed on the electrostatic charge image carrier with toner to form a visible image are integrally supported and detachable from the main body of the image forming apparatus. A process cartridge according to claim 1, wherein the toner for developing an electrostatic charge image according to any one of claims 1 to 6 is used as the toner.

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