JP2006085198A - Electrophotographic method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic method using an electrostatic latent image toner which has a high charging level and fast rising of charges and is imparted with positive charging characteristics excellent in durability and stability. <P>SOLUTION: In the electrophotographic method using an electrostatic latent image toner containing a binder resin and a charge controlling agent, the electrostatic latent image toner specified as follows is used. A charge controlling agent (CCA) having a function of controlling charges to a specified range (excluding a quaternary ammonium salt) and a charge enhancing resin (CCR) having a function of enhancing charges are used together as the charge controlling agent: the total amount of the charge controlling agent and the charge enhancing resin (CCA+CCR) is controlled to the range of 3 to 7 wt.% with respect to 100 wt.% of the entire amount of the electrostatic latent image toner. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrophotographic method using a specific electrostatic latent image toner (hereinafter sometimes simply referred to as toner) in a development process employed in a copying machine, a laser printer, or the like. More specifically, the present invention relates to an electrophotographic method using an electrostatic latent image toner that has a high charge level, a rapid rise in charge amount, and can impart positive charge characteristics excellent in durability and stability.

  In dry electrophotography, a magnetic toner (particularly a magnetic one-component toner) used to make an electrostatic latent image a visible image is generally a thermoplastic binder resin (binder resin), a charge control agent, a magnetic powder, In addition, the toner is manufactured as a toner having a desired particle diameter through premixing and other steps of melt-kneading, pulverization, and classification. In the toner particles, a certain amount of positive or negative charge is accumulated by frictional charging on the particle surface, and the charged particles are used for developing an electrostatic latent image.

  Here, the charge accumulated on the surface of the toner particles due to frictional charging needs to be either positive or negative depending on the type of the photoconductive photoreceptor used for forming the electrostatic latent image. In this case, the amount of charge needs to be sufficient to make the electrostatic latent image visible more accurately. For this reason, a charge control agent or a conductive substance is generally mixed and dispersed in a binder resin to control the charge and charge amount on the toner particle surface.

  Further, in recent years, as a photoconductive photoconductor for forming an electrostatic latent image, in place of a selenium photoconductor or an organic photoconductive photoconductor, it is pollution-free and has high sensitivity, and further has a Vickers strength of 1500 to 1500. Amorphous silicon photoconductors (hereinafter referred to as a-Si photoconductors) are used from the viewpoint of having characteristics such as 2000 being very hard. Therefore, in order to develop an electrostatic latent image formed on an a-Si photoreceptor, it is desired to use a positively chargeable toner having excellent chargeability and durability.

  Therefore, magnetic one-component toner particles are known as positively chargeable toners. In this toner, a charge control agent (CCA) having a function of adjusting a charge amount typified by nigrosine or the like within a certain range is used alone as a charge control agent.

  However, such a positively chargeable charge control agent (CCA) has poor compatibility with the binder resin. In particular, when the toner contains magnetic powder, the dispersibility of the charge control agent is significantly reduced, and the toner The charging characteristics became unstable, causing problems such as image defects and poor fixability. In addition, such a positively chargeable charge control agent is used to control the charge present in the particle surface layer during the pulverization process when the toner particles are produced and the fluid friction process in the copying machine when the charge is accumulated on the toner particle surfaces. There is a tendency for the agent to easily leave. For this reason, there have been problems such as a change in the charge amount of the toner particles and a variation in the chargeability of the individual toner particles. In particular, since the number of times of copying increases and the time of fluid friction increases, it has been difficult to maintain a stable charged state over a long period of time.

Therefore, instead of the positively chargeable charge adjusting agent (CCA), a charge enhancing resin (CCR) in which a functional group of a quaternary ammonium salt is introduced into a polymer has been proposed (see Patent Documents 1 to 3). However, even when such a charge-enhancing resin (CCR) is used alone, there has been a problem that the rising property of the charge amount is poor. In particular, in a high-temperature and high-humidity environment, the stand-up property is further reduced, and it is difficult to control the chargeability.
JP-A-62-210472 (Claims) JP 63-60458 (Claims) Japanese Patent Laid-Open No. 3-80259 (Claims)

The inventors of the present invention have intensively studied the conventional problems, and as a result, a specific charge adjusting agent (CCA) having a function of adjusting the charge amount within a certain range and a charge enhancement having a function of increasing the charge amount. By using the resin (CCR) together, it is possible to quickly increase the charge amount even in an environment such as high temperature and high humidity, and to prevent the deterioration of the durability of the toner due to the difficulty in charging the toner. The title and the present invention have been completed.
In other words, an object of the present invention is to provide an electrophotographic method using an electrostatic latent image toner that has a quick rise in charge amount, can be easily controlled, and has excellent durability and the like.

In an electrophotographic method using an electrostatic latent image toner containing a binder resin and a charge control agent, the present invention relates to a charge control agent having a function of adjusting a charge amount within a certain range as a charge control agent ( However, the quaternary ammonium salt is excluded.) (CCA) and a charge enhancing resin (CCR) having a function of increasing the charge amount are used in combination, and the total amount of the electrostatic latent image toner is 100% by weight. An electrostatic latent image toner using a total amount of the charge adjusting agent and the charge enhancing resin in the range of 3 to 7% by weight.
With this configuration, the toner can be charged quickly, so that the so-called charge amount can be quickly started up, and positive charging characteristics excellent in durability and stability can be imparted. That is, even when only one of the charge adjusting agent (CCA) and the charge enhancing resin (CCR) is used, a quick start-up property cannot be obtained, and the toner tends to deteriorate due to a long-time charging operation. However, by combining the charge control agent (CCA) and the charge-enhancing resin (CCR) in this way, the rise of the charge amount can be made synergistically faster, and the charge amount can be easily controlled, resulting in a high charge. The quantity can be obtained.

  In carrying out the electrophotographic method using the electrostatic latent image toner of the present invention, the charge-enhancing resin (CCR) is a polymer or oligomer having a quaternary ammonium salt, or a polymer or oligomer having a carboxylate. The polymer or oligomer having a carboxyl group is preferred.

  In carrying out the electrophotographic method using the electrostatic latent image toner of the present invention, the charge adjusting agent (CCA) is an azine compound (including a nigrosine compound), and the charge enhancing resin (CCR) is quaternary. A styrene-acrylic copolymer having an ammonium salt is preferred.

  Further, in carrying out the electrophotographic method using the electrostatic latent image toner of the present invention, when the total amount of the electrostatic latent image toner is 100% by weight, the charge adjusting agent is added in an amount of 0.1%. A value in the range of 5 to 5% by weight is preferred.

  In carrying out the electrophotographic method using the electrostatic latent image toner of the present invention, when the total amount of the electrostatic latent image toner is 100% by weight, A value within the range of 5% by weight is preferred.

  In carrying out the electrophotographic method using the electrostatic latent image toner of the present invention, the binder resin is preferably a styrene-acrylic copolymer.

  An embodiment of a magnetic toner for electrostatic latent images (hereinafter sometimes simply referred to as toner) and an electrophotographic method using the same in the present invention will be described in detail.

[Binder resin]
(1) Type The type of binder resin used in the toner of the present invention is not particularly limited. For example, styrene resin, acrylic resin, styrene-acrylic copolymer, polyethylene resin, polypropylene resin It is preferable to use thermoplastic resins such as vinyl chloride resin, polyester resin, polyamide resin, polyurethane resin, polyvinyl alcohol resin, vinyl ether resin, N-vinyl resin, styrene-butadiene resin.

  More specifically, the polystyrene resin may be a homopolymer of styrene or a copolymer with another copolymerizable monomer copolymerizable with styrene. As copolymerizable monomers, p-chlorostyrene; vinyl naphthalene; ethylene unsaturated monoolefins such as ethylene, propylene, butylene, and isobutylene; vinyl halides such as vinyl chloride, vinyl bromide, and vinyl fluoride; vinyl acetate, propion Vinyl esters such as vinyl acrylate, vinyl benzoate, vinyl butyrate; methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, dodecyl acrylate, n-octyl acrylate, 2-chloroethyl acrylate, acrylic (Meth) acrylic acid esters such as phenyl acid, methyl α-chloroacrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate; other acrylic acid derivatives such as acrylonitrile, methacrylonitrile, acrylamide; Vinyl ethers such as nylmethyl ether and vinyl isobutyl ether; Vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and methyl isopropenyl ketone; N-vinyl pyrrole, N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidene, etc. N-vinyl compounds of These may be used alone or in combination of two or more with a styrene monomer.

  Moreover, as the polyester resin, any resin obtained by condensation polymerization or co-condensation polymerization of an alcohol component and a carboxylic acid component can be used. The following are mentioned as a component used when synthesize | combining a polyester-type resin.

  First, dihydric or trihydric or higher alcohol components include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1, Diols such as 4-butenediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol; bisphenol A, hydrogen Bisphenols such as added bisphenol A, polyoxyethylenated bisphenol A, polyoxypropylenated bisphenol A; sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, Entaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, diglycerol, 2-methylpropanetriol, 2-methyl-1,2,4- Examples include trivalent or higher alcohols such as butanetriol, trimethylolethane, trimethylolpropane, 1,3,5, -trihydroxymethylbenzene.

  As the divalent or trivalent or higher carboxylic acid component, a divalent or trivalent carboxylic acid, an acid anhydride or a lower alkyl ester thereof is used. Maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid Phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, malonic acid, or n-butyl succinic acid, n-butenyl succinic acid, isobutyl succinic acid, isobutenyl succinic acid, Divalent carboxylic acids such as alkyl or alkenyl succinic acid such as n-octyl succinic acid, n-octenyl succinic acid, n-dodecyl succinic acid, n-dodecenyl succinic acid, isododecyl succinic acid and isododecenyl succinic acid; , 4-Benzenetricarboxylic acid (trimellitic acid), 1,2,5 Benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl -2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, empole trimer acid Examples thereof include trivalent or higher carboxylic acids and the like.

  The binder resin is preferably a thermoplastic resin from the viewpoint of good fixability, but the amount of cross-linked portion (gel amount) measured using a Soxhlet extractor is 10% by weight or less, more preferably 0.1. A thermosetting resin may be used as long as the value is within a range of 10 wt% to 10 wt%. By introducing a partially crosslinked structure in this way, it is possible to further improve the storage stability, form retention, and durability of the toner without deteriorating the fixability. Therefore, it is not necessary to use 100% by weight of the thermoplastic resin as the binder resin for the toner, and it is also preferable to add a cross-linking agent or partially use a thermosetting resin.

  Therefore, an epoxy resin, a cyanate resin, or the like can be used as the thermosetting resin. More specifically, one or more of bisphenol A type epoxy resin, hydrogenated bisphenol A type epoxy resin, novolac type epoxy resin, polyalkylene ether type epoxy resin, cycloaliphatic type epoxy resin, cyanate resin, etc. Combinations are listed.

(2) Functional group in binder resin Also, in such a binder resin, in order to improve the dispersibility of the magnetic powder, it is selected from hydroxyl group, hydroxyl group, amino group and glycidoxy (epoxy) group. It is preferable to use a resin having at least one functional group in the molecule.
In addition, it can be confirmed using an FT-IR apparatus whether it has these functional groups, and also can be quantified using a titration method.

(3) Molecular Weight of Binder Resin The binder resin preferably has two weight molecular weight peaks (referred to as a low molecular weight peak and a high molecular weight peak). Specifically, it is preferable that the low molecular weight peak is in the range of 3,000 to 20,000, and the other high molecular weight peak is in the range of 300,000 to 1500,000. If the weight molecular weight peak is within such a range, the toner can be easily fixed, and offset resistance can be improved. The weight molecular weight of the binder resin is determined by measuring the elution time from the column using a molecular weight measuring device (GPC) and comparing it with a calibration curve prepared in advance using a standard polystyrene resin. Can do.

(4) Glass transition point of binder resin Moreover, in a binder resin, it is preferable to make a glass transition point (Tg) into the value within the range of 55-70 degreeC. When the glass transition point of the binder resin is less than 55 ° C., the obtained toners are fused with each other, and the storage stability tends to be lowered. On the other hand, when the glass transition point of the binder resin exceeds 70 ° C., the fixability of the toner tends to be poor. In addition, the glass transition point of binder resin can be calculated | required from the change point of specific heat using a differential scanning calorimeter (DSC).

[Charge control agent]
In the toner of the present invention, the charge level and the charge rising property (indicator of whether to charge to a constant charge level in a short time) are remarkably improved, and the durability and stability are excellent, and excellent fluidity is obtained. Therefore, it is necessary to add a charge control agent.
Here, the charge control agent includes a specific charge adjusting agent (CCA) having a function of adjusting the charge (charge amount) within a certain range, and a charge enhancing resin having a function of increasing the charge (charge amount) ( CCR). In the toner of the present invention, it is necessary to add a specific charge adjusting agent and a charge enhancing resin in combination.

(1) Charge control agent (CCA)
Specific examples of the charge control agent (CCA) used in the present invention include pyridazine, pyrimidine, pyrazine, orthooxazine, metaoxazine, paraoxazine, orthothiazine, metathiazine, parathiazine, 1, 2, 3 as azine compounds. Triazine, 1,2,4-triazine, 1,3,5-triazine, 1,2,4-oxadiazine, 1,3,4-oxadiazine, 1,2,6-oxadiazine, 1,3,4-thiadiazine 1,3,5-thiadiazine, 1,2,3,4-tetrazine, 1,2,4,5-tetrazine, 1,2,3,5-tetrazine, 1,2,4,6-oxatriazine, Azin Fast Red as a direct dye consisting of 1,3,4,5-oxatriazine, phthalazine, quinazoline, quinoxaline and azine compounds C, azine fast red 12BK, azine violet BO, azine brown 3G, azine light brown GR, azine dark green BH / C, azine deep black EW and azine deep black 3RL, nigrosine as a nigrosine compound, nigrosine salt, nigrosine derivative, nigrosine Nigrosine BK, Nigrosine NB, Nigrosine Z, metal salts of naphthenic acid or higher fatty acids, alkoxylated amines, alkylamides, benzylmethylhexyldecylammonium as quaternary ammonium salts, decyltrimethylammonium chloride, etc. as acidic dyes composed of compounds 1 type, or 2 or more types.
In particular, the nigrosine compound contained in the azine compound is optimal for use in the present invention from the viewpoint of obtaining a quicker start-up property.

(2) Charge-enhancing resin (CCR)
Examples of the charge enhancing resin (CCR) used in the present invention include a resin or oligomer having a quaternary ammonium salt, a resin or oligomer having a carboxylate, a resin or oligomer having a carboxyl group, and the like. Polystyrene resin having quaternary ammonium salt, acrylic resin having quaternary ammonium salt, styrene-acrylic resin having quaternary ammonium salt, polyester resin having quaternary ammonium salt, polystyrene resin having carboxylate Resin, acrylic resin with carboxylate, styrene-acrylic resin with carboxylate, polyester resin with carboxylate, polystyrene resin with carboxyl group, acrylic resin with carboxyl group, carboxyl group Styrene- Acrylic-based resin, and one or more of such polyester resin having a carboxyl group.

  In particular, a styrene-acrylic resin (styrene-acrylic copolymer) having a quaternary ammonium salt, carboxylate or carboxyl group as a functional group can easily adjust the charge amount to a value within a desired range. From the point of view, it is optimal for use in the present invention. Moreover, as a preferable acrylic resin in the above-mentioned styrene-acrylic resin or acrylic resin itself, (meth) acrylic acid alkyl ester includes methyl acrylate, ethyl acrylate, n-propyl acrylate, iso-propyl acrylate. N-butyl acrylate, iso-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate, and the like.

  As the quaternary ammonium salt, a unit derived from a dialkylaminoalkyl (meth) acrylate through a quaternization step is used. Examples of the derived dialkylaminoalkyl (meth) acrylate include di (amino) ethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dipropylaminoethyl (meth) acrylate, dibutylaminoethyl (meth) acrylate and the like ( Lower alkyl) aminoethyl (meth) acrylate; dimethylmethacrylamide, dimethylaminopropylmethacrylamide are preferred. Further, hydroxy group-containing polymerizable monomers such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and N-methylol (meth) acrylamide can be used in combination during polymerization.

(3) Addition amount Next, the addition amount of the charge control agent will be described. That is, the addition amount of the charge control agent is preferably determined from the desired charge amount. Specifically, the addition amount of the charge control agent (CCA) is set to a value within the range of 0.5 to 5% by weight, In addition, the amount of charge-enhancing resin (CCR) added is preferably set to a value in the range of 1 to 5% by weight. By setting each value within such a range, the dispersibility is good and the effect of addition can be exhibited effectively.
Therefore, the addition amount of the charge adjusting agent (CCA) is set to a value within the range of 0.5 to 3% by weight, and the addition amount of the charge enhancing resin (CCR) is set to the value within the range of 2 to 5% by weight. Is preferred.

Further, when the total amount of the toner is 100% by weight, the addition amount of the charge control agent (CCA + CCR), which is the sum of the charge adjusting agent (CCA) and the charge enhancing resin (CCR), is 3.0 to 7.0% by weight. It is preferable to set the value within the range of%.
When the addition amount of the charge control agent (CCA + CCR) is less than 3% by weight, it becomes difficult to stably impart charging characteristics to the toner, and there is a tendency that the image density is lowered or the durability is lowered. is there. In addition, poor dispersion tends to occur, so-called fogging tends to occur, and photoconductor contamination tends to increase.
On the other hand, if the amount of the charge control agent (CCA + CCR) added exceeds 7% by weight, the environment resistance, particularly charging failure and image failure under high temperature and high humidity, tends to cause defects such as photoconductor contamination. .
Therefore, from the viewpoint of a better balance between the charge control function and the durability of the toner, the addition amount of the charge control agent (CCA + CCR) is set to a value within the range of 3.0 to 8.0% by weight. Is more preferable.

[Additive]
(1) Waxes In the toner of the present invention, it is preferable to add waxes from the viewpoint of increasing the image density and effectively preventing offset to the reading head and image smearing.

  Here, the type of wax to be added is not particularly limited, but for example, polyethylene wax, polypropylene wax, fluorine-based wax, Fischer-Tropsch wax and the like are preferably used. By adding such wax, offset to the read head and image smearing can be prevented more efficiently. Fischer-Tropsch wax is a straight-chain hydrocarbon compound that is produced using the Fischer-Tropsch reaction, which is a catalytic hydrogenation reaction of carbon monoxide, and has few iso (iso) structure molecules and side chains.

  Further, among Fischer-Tropsch waxes, those having a weight average molecular weight of 1000 or more and an endothermic bottom peak due to DSC in the range of 100 to 120 ° C. are more preferable. As such Fischer-Tropsch wax, Sazol wax C1 (high molecular weight grade by crystallization of H1, endothermic bottom peak: 106.5 ° C.) available from Sazol, Sazol wax C105 (by fractional distillation of C1) Refined product, endothermic bottom peak: 102.1 ° C.), Sazol wax SPRAY (C105 fine particles, endothermic bottom peak: 102.1 ° C.), and the like.

  Also, the amount of added wax is not particularly limited. For example, when the total amount of toner is 100% by weight, the added amount of wax is set to a value in the range of 1 to 5% by weight. Is preferred. If the amount of added wax is less than 1% by weight, there is a tendency that offset to the read head, image smearing, etc. cannot be effectively prevented, while if the added amount of wax exceeds 5% by weight. Further, the toners are fused with each other, and the storage stability tends to be lowered.

(2) Others The toner of the present invention includes a colorant, a dye, a pigment, a coupling agent, silica particles, etc. for the purpose of improving the fluidity of the toner, maintaining the storage stability, or making it multifunctional. It is also possible to add and blend. In particular, for the purpose of maintaining fluidity and storage stability, it is preferable to use colloidal silica, hydrophobic silica or the like in the toner having an average particle diameter in the range of 5 to 12 μm. Silica particles are preferably externally added to the toner from the viewpoint of more control of the fluidity of the toner. In that case, it is preferable to use, as silica particles, dry silica fine powder in which a positively charged polar group (amino group or the like) is introduced using a silane coupling agent and subjected to a hydrophobic treatment with silicone oil.

  Hereinafter, the present invention will be described in more detail based on examples. Needless to say, the following description exemplifies the present invention, and the scope of the present invention is not limited to the following description without any particular reason.

[Example 1]
(Preparation of toner for electrostatic latent image)
An electrostatic latent image toner was prepared with the following blending ratio.
(1) Styrene-acrylic resin 87.5 parts by weight (2) Azine compound system (charge control agent, CCA) 0.5 part by weight (3) 4.0 parts by weight styrene resin having quaternary ammonium salt as functional group Copolymer (charge enhancing resin, CCR)
(4) 3.0 parts by weight of polypropylene wax (5) 5.0 parts by weight of carbon black

However, the total addition amount is 100 parts by weight, the polypropylene wax is fixed at 3 parts by weight, the carbon black is fixed at 5 parts by weight, and the addition amount of styrene-acrylic resin (copolymer) is the remaining part by weight 87 .5 parts by weight shall be added.
Next, each component was melt-kneaded with a twin-screw extruder, then cooled, pulverized and classified to obtain a powder having an average particle size of 7 μm.

In addition, the compounding ratio of the charge adjusting agent (CCA) and the charge enhancing resin (CCR) is as shown in Table 1, the azine compound system (CCA) is 0.5 parts by weight, and the quaternary ammonium salt is a functional group. The styrene-based resin copolymer (CCR) is 4.0 parts by weight. Then, silica (SiO ₂ ) fine powder was externally added and mixed to the obtained powder so as to have a ratio of 0.5% by weight, and adhered to the surface to be used for the following evaluation as the toner of the present invention. .

(Evaluation of toner for electrostatic latent image)
The obtained toner was used as a magnetic one-component developer, accommodated in a Kyocera page printer (FS-3700) equipped with an a-Si drum, and an image evaluation pattern (solid pattern) was output to evaluate the fixability. In addition, charging characteristics, image characteristics, and developing sleeve contamination were evaluated by the following methods. The obtained results are shown in Table 2.

(1) Charging characteristics 5 parts by weight of the obtained toner and 100 parts by weight of a ferrite carrier are mixed and vibrated in a container under normal environmental conditions (20 ° C., 65% RH) for friction charging for 60 minutes. The initial charge amount was defined as the charge amount (μC / g). The results are shown in Table 2.

  Further, the toner was used as a magnetic one-component developer and contained in the above-mentioned Kyocera page printer, and 100,000 sheets were continuously printed (paper passing). The toner charge amount at that time was defined as the charge amount after durability. The results are shown in Table 2. The charge amount of the toner was measured using a blow-off powder charge amount measuring device manufactured by Toshiba Chemical Corporation.

Further, in this example, the charge amount of the toner was measured before stirring (0 minutes), 3 minutes, 10 minutes, 20 minutes, 30 minutes, and 40 minutes after stirring, and the charge rising property of the toner was also examined. . The result is shown in FIG.
In FIG. 1, the horizontal axis represents the stirring time (minutes), and the vertical axis represents the charge amount (μC / g). The curve indicated by the symbol A represents this example. For comparison, similar data for Comparative Example 1 is represented by a curve indicated by symbol B, similar data for Comparative Example 2 is represented by a curve denoted by symbol C, and further denoted by symbol D. The curve shown shows an example in which neither the charge control agent (CCA) nor the charge enhancement resin (CCR) is added in Example 1. As can be seen from the results, this example with the addition of a charge control agent and a charge enhancing resin shows a charge amount of 15 μC / g or more in about 3 minutes after stirring, and 30 μC / g in about 10 minutes after stirring. Saturates at high levels. On the other hand, the system (curves B and C) to which either one of the charge adjusting agent and the charge enhancing resin is added has a clearly slow rise in charge amount, and the saturated charge level is 20 to 24 μC / It can be seen that it is quite low as g.

(2) Image characteristics The obtained toner was used as a magnetic one-component developer and stored in the above-mentioned Kyocera page printer, and the image characteristics were evaluated. That is, an image evaluation pattern (solid pattern) obtained in a normal environment (20 ° C., 65% RH) is used as an initial image, and then 100,000 sheets are continuously printed (paper passing) to print the image pattern. A durable image was obtained. Then, using an Macbeth reflection densitometer, the image density (print density) in the initial image and the durable image was measured. The results are shown in Table 2.

Further, the fogging property of the initial image and the durable image obtained at the same time was visually observed according to the following criteria.
○: Fog is not observed at all and is in a good state.
Δ: Slight fogging is observed.
X: Remarkable fog is observed.

(3) Fixability Fixing temperature is set to 190 ° C, and after cooling for 10 minutes with the power off, the power is turned on (ON), and five image evaluation patterns (solid patterns) are printed continuously for measurement. I got an image. Next, a brass weight (1 kg load) wrapped with a cotton cloth was reciprocated 10 times on the obtained image. The image density before and after this operation was measured with a Macbeth reflection densitometer, the fixing rate (density before operation / density after operation) of the density was determined, and the fixability was evaluated from the following criteria. The results are shown in Table 2. Note that classic crest paper was used as the evaluation paper.
A: The fixing rate is a value of 95 or more.
Δ: The fixing ratio is a value of 90% or more and less than 95%.
X: The fixing rate is a value of less than 90%.

(4) Adherence to developing sleeve The obtained toner was used as a magnetic one-component developer and stored in the above-mentioned Kyocera page printer, and image characteristics were evaluated. That is, 100,000 sheets were continuously printed in a normal environment (20 ° C., 65% RH), and the obtained image evaluation pattern (solid pattern) was visually observed to evaluate the developing sleeve adhesion from the following criteria. The results are shown in Table 2.
○: Dirt is not recognized, and it is clean and good.
Δ: Slight dirt is observed.
X: Considerable dirt is recognized.

[Examples 2 to 4, Reference Example 1 and Example 6]
(Preparation of toner for electrostatic latent image)
In Examples 2 to 4, Reference Example 1 and Example 6, as shown in Table 1, except that the addition amounts of the charge adjusting agent (CCA) and the charge enhancing resin (CCR) were changed, respectively, Similarly, an electrostatic latent image toner was prepared.

(Evaluation of toner for electrostatic latent image)
In Examples 2 to 4, Reference Example 1 and Example 6, the obtained electrostatic latent image toners were evaluated for fixing properties and image characteristics in the same manner as in Example 1. The results are shown in Table 2.

[Comparative Examples 1-2]
(Preparation of toner for electrostatic latent image)
In Comparative Examples 1 and 2, the electrostatic latent image toner is the same as in Example 1 except that either one of a charge control agent (CCA) and a charge enhancement resin (CCR) is added as shown in Table 1. Was made.

(Evaluation of toner for electrostatic latent image)
In Comparative Examples 1 and 2, the electrostatic latent image toners obtained were evaluated in terms of fixability and image characteristics in the same manner as in Example 1. The results are shown in Table 2.

  According to the present invention, in an electrophotographic method using an electrostatic latent image toner containing a binder resin and a predetermined amount of a charge control agent, the charge control agent has a function of adjusting the charge amount within a certain range. The charge level can be increased by using the charge control agent (excluding quaternary ammonium salt) (CCA) and the charge enhancing resin (CCR) having the function of increasing the charge amount in combination. It is now possible to provide an electrophotographic method using an electrostatic latent image toner (electrostatic latent image toner) capable of imparting a positive charging characteristic having a fast rise and excellent durability and stability.

FIG. 5 is a diagram illustrating a relationship between agitation time and a charge amount in an electrostatic latent image toner.

Claims (6)

In an electrophotographic method using an electrostatic latent image toner containing a binder resin and a charge control agent,
As the charge control agent,
A charge control agent (excluding a quaternary ammonium salt) having a function of adjusting the charge amount within a certain range (CCA);
A charge-enhancing resin (CCR) having a function of increasing the charge amount;
Together with
The electrostatic latent image toner in which the total amount of the charge adjusting agent and the charge enhancing resin is in the range of 3 to 7% by weight when the total amount of the electrostatic latent image toner is 100% by weight. An electrophotographic method using the method.   The charge-enhancing resin (CCR) is a polymer or oligomer having a quaternary ammonium salt, a polymer or oligomer having a carboxylate, or a polymer or oligomer having a carboxyl group. Electrophotographic method.   The electron according to claim 1 or 2, wherein the charge control agent (CCA) is an azine compound, and the charge-enhancing resin (CCR) is a styrene-acrylic copolymer having a quaternary ammonium salt. Photo method.   2. The addition amount of the charge adjusting agent is set to a value within a range of 0.5 to 5% by weight when the total amount of the electrostatic latent image toner is 100% by weight. The electrophotographic method according to claim 1.   5. The additive amount of the charge enhancing resin is set to a value in the range of 1 to 5% by weight when the total amount of the electrostatic latent image toner is 100% by weight. The electrophotographic method according to any one of the above.   The electrophotographic method according to any one of claims 1 to 5, wherein the binder resin is a styrene-acrylic copolymer.

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