JP2003131419A - Toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner which causes no retransfer under various transfer current conditions and gives high image density. SOLUTION: The toner is obtained by adding acicular fine particles of iron oxide hydrate to toner particles comprising a bonding resin and a colorant and has one or more endothermic peaks at <=120 deg.C in differential thermal analysis.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner used in recording methods using electrophotography, electrostatic recording, magnetic recording and the like.

[0002]

2. Description of the Related Art Conventionally, a large number of electrophotographic methods are known, but generally, a photoconductive substance is used to form an electric latent image on a photoconductor by various means, and then,
The latent image is developed with toner to make it a visible image, and if necessary, the toner image is transferred to a transfer material such as paper, and then the toner image is fixed on the transfer material by heat / pressure to obtain a final image. It is a thing.

In recent years, there has been a great demand for colorization of copying machines, printers and fax machines using electrophotography.

Further, in order to suppress image shift, there is a process in which a multicolor image is formed on a photosensitive member or an intermediate transfer member and then transferred to a transfer material such as a paper / OHT film at once. is necessary.

In general, it is difficult to use a magnetic toner containing a magnetic material for a color toner because of its tint.
Non-magnetic toner is used. When magnetic toner that is more advantageous in downsizing / simplification of the developing device is used as black toner and non-magnetic toner is used as color toner, the optimum transfer current value of non-magnetic toner is the optimum transfer current value of magnetic toner. Tends to be higher. Therefore, when the transfer condition of the main body of the device is adjusted to the non-magnetic toner, a phenomenon called "retransfer" occurs in which the magnetic toner is once transferred onto the transfer material and then returns to the latent image carrier, resulting in a black image. Causes a decrease in image density.

Further, as paper materials have been further diversified in recent years, copying machines, printers, and fax machines using electrophotography are required to be compatible with these various paper materials. However, the optimum transfer conditions differ depending on the paper material that is the transfer material. For example, for thick paper or OHT film, the optimum transfer current value is high. On the other hand, for thin paper, the optimum transfer current value is low, and if the transfer conditions of the device body are optimized for thick paper or OHT film, the “retransfer” phenomenon still occurs.

Japanese Unexamined Patent Publication No. 2-66559 and Japanese Unexamined Patent Publication No.
No. 87159, JP-A-2-146557, JP-A-2-167566, JP-A-5-61251 and the like have been proposed that the transfer rate can be improved by subjecting the toner to mechanical shock treatment. There is.

In the methods proposed by these methods, the transfer rate is certainly improved when the transfer conditions are optimized for the toner, but the transfer efficiency when the transfer current value is set higher than that. Is hardly improved and has no effect on the improvement of "retransfer".

Further, in JP-A-10-48870 and JP-A-10-48872, the transfer current value is set to a high value by adding certain specific inorganic fine particles or organic fine particles to the toner particles. It has been proposed that "retransfer" can be suppressed even in the case.

However, in the case of using a high-humidity environment in which "retransfer" is more likely to occur and a transfer paper having a small thickness is used, further improvement in "retransfer" property is required.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to provide a toner which solves the above problems of the prior art.

That is, an object of the present invention is to provide a toner which can obtain high image density without causing "retransfer" under a wide range of transfer current conditions (especially under high transfer current conditions).

A further object of the present invention is to provide a toner having a high image density and capable of obtaining an image of good quality.

[0014]

The present invention provides a toner having toner particles containing at least a binder resin and a colorant and needle-shaped iron oxide hydroxide fine particles externally added to the toner particles. The average major axis of the fine particles is 0.2 to
2.0 μm, the average of the ratio of the major axis to the minor axis is 5 to 60,
The toner has an endothermic peak in differential thermal analysis of 120 ° C.
The present invention relates to a toner having one or more of the following.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The inventors of the present invention have conducted a study for the purpose of solving "retransfer", and have found that "retransfer" can be solved by increasing the charge amount of toner before transfer. Was achieved.

That is, the specific iron oxide hydroxide fine particles are externally added to the toner particles, and the endothermic peak in the differential thermal analysis is 1
By using the toner having one or more at 20 ° C. or less, the charge amount of the toner on the electrostatic latent image carrier before transfer or the intermediate transfer member can be made higher than before.
It was possible to prevent "retransfer".

The reason is that in the toner of the present invention, the fine particles are separated from the toner base during development and transfer, and the fine particles give an electric charge to the toner base itself, thereby increasing the charge amount of the toner before transfer. It is considered that "retransfer" can be prevented.

In the present invention, when the average particle diameter of the iron oxide hydroxide fine particles externally added to the toner particles is less than 0.2 μm, the adhesion of the fine particles to the toner surface is too large, and the toner base particles during development / transfer are too large. Separation does not occur sufficiently and the charge amount of the toner before transfer cannot be increased, so that there is no effect in preventing “retransfer”. When the average particle diameter of the fine particles exceeds 2.0 μm, the surface area of the fine particles is small and the effect of increasing the tribo of the toner before transfer is small and the effect of preventing “retransfer” is not obtained. In addition, the toner particles may agglomerate with the fine particles as nuclei, resulting in an increase in fog.

The iron oxide hydroxide fine particles used in the present invention have a needle-like shape. Since the iron oxide hydroxide fine particles have a needle-like shape, the tribo of the toner is increased and the effect of preventing "retransfer" is high as compared with the case where an isotropic shape is used. The needle-like shape is represented by the ratio of major axis to minor axis (major axis / minor axis), and the average of major axis and minor axis of the hydrous iron oxide hydroxide fine particles used in the present invention is 5 to 60. When the average of the ratio is less than 5, the effect of increasing toner tribo and preventing “retransfer” is low, and when it exceeds 60, aggregation of the toner particles occurs with the iron oxide hydroxide fine particles as nuclei. This causes an increase in fog.

The iron oxide hydroxide fine particles according to the present invention are used in a form externally added to the toner particles. When the fine particles are internally added to the toner particles and strongly fixed to the toner surface, the charge amount of the toner before the transfer cannot be increased, and the "retransfer" cannot be prevented.

In the present invention, the iron oxide hydroxide fine particles are
It is preferable that the iron powder carrier has the same charging polarity as the toner particles. When the charging polarity of the fine particles is the same as the charging polarity of the toner particles, the image density is higher and the fog can be further suppressed.

Further, in the present invention, the above-mentioned iron oxide hydroxide fine particles have an absolute charge amount of | 2 with respect to the iron powder carrier.
It is preferably 0 | μC / g or less, more preferably | 10 | μC / g or less. When the charge amount of the fine particles is in the above range, the image density is higher and the fog can be further suppressed.

The amount of the iron oxide hydroxide fine particles added to the toner particles is 0.01 to 100 parts by weight of the toner particles.
It is preferably 2.0 parts by mass (more preferably 0.05 to 1.0 parts by mass).

When the amount of the iron oxide hydroxide fine particles added to the toner particles is less than the above lower limit, the effect of increasing the charge amount of the toner before transfer is insufficient, and the effect of preventing "retransfer" is sufficiently obtained. Absent. If the amount of fine particles added to the toner particles exceeds the upper limit, fog is likely to occur.

Next, the material of the iron oxide hydroxide fine particles according to the present invention will be described in detail.

The iron oxide hydroxide used in the present invention is generally a compound represented by the chemical formula of FeOOH. There are some crystal forms in this, but among them, α-type iron oxide hydroxide is more preferable. When the α-type iron oxide hydroxide fine particles are used in the present invention, the “retransfer” preventing effect is further enhanced.

Further, the surface of the hydrous iron oxide hydroxide fine particles may be a form in which another metal oxide, hydrous oxide or hydroxide is adhered and coated. Further, the surface of the iron oxide hydroxide fine particles may be subjected to a hydrophobic treatment.

The toner of the present invention has one or more endothermic peaks in differential thermal analysis at 120 ° C. or lower (preferably 110 ° C. or lower).

Endothermic peak in differential thermal analysis is 120 ° C.
If it is not below, the effect of preventing "retransfer" by externally adding the iron oxide hydroxide fine particles of the present invention cannot be sufficiently obtained.

Endothermic peak in differential thermal analysis is 120 ° C.
The toner described below has a specific state in which the state of dispersion of the magnetic material / charge control agent in the binder resin in the melt-kneading step in the production of toner particles is different from that of the toner having no endothermic peak at 120 ° C. or less. It is supposed to be.
It is considered that the certain specific state makes it easy to exert the effect of preventing the "retransfer" of the specific iron oxide hydroxide fine particles of the present invention.

The toner of the present invention is effective if the endothermic peak in differential thermal analysis is at least 120 ° C. or lower, and the endothermic peak may be above 120 ° C. However, it is preferable that the endothermic peak in the differential thermal analysis does not exist below 60 ° C (preferably below 70 ° C). Endothermic peak in differential thermal analysis is 60 ℃
If it is below the range, the image density tends to be low. In addition, storage stability tends to be unstable.

The endothermic peak in the differential thermal analysis is 120 ° C.
As a means to have the form described below, a method of internally adding a compound having an endothermic peak in differential thermal analysis at 120 ° C. or lower to the toner particles is preferable.

The endothermic peak in the differential thermal analysis is 120 ° C.
Examples of compounds having one or more of the following include resins and waxes.

Examples of the resin include crystalline polyester resin and silicone resin.

As the wax, paraffin wax,
Petroleum wax and its derivatives such as microcrystalline wax and petrolactam, montan wax and its derivatives, hydrocarbon wax and its derivatives by the Fischer-Tropsch method, polyolefin wax represented by polyethylene and its derivatives, carnauba wax,
Natural waxes such as candelilla wax and their derivatives, and the like include oxides, block copolymers with vinyl monomers, and graft modified products. Alcohols such as higher aliphatic alcohols; fatty acids such as stearic acid and palmitic acid or compounds thereof; acid amides, esters, ketones, hydrogenated castor oil and its derivatives, vegetable waxes, animal waxes, etc.
Any material having a temperature of not higher than 0 ° C can be used.

It is considered that these compounds have relatively low polarities and stabilize the charging of the toner base. It is considered that this facilitates the effect of preventing "retransfer" of the iron oxide hydroxide fine particles according to the present invention.

Among the above waxes, polyolefin,
Hydrocarbon waxes, petroleum waxes and higher alcohols obtained by the Fischer-Tropsch method are particularly preferable in the toner of the present invention.

The above-mentioned polyolefin, hydrocarbon wax by the Fischer-Tropsch method, petroleum wax, and higher alcohols have a weight-average molecular weight (M) measured by gel permeation chromatography (GPC).
If the ratio (Mw / Mn) of w) to the number average molecular weight (Mn) is 1.0 to 2.0, the effect of preventing "retransfer" is further enhanced. The reason is that (Mw / Mn) is 1.0 to
By incorporating the above wax having a sharp re-sharp molecular weight distribution of 2.0 into the toner particles, the state of dispersion of the magnetic material, the charge control agent, etc. in the binder resin can be improved in the melt-kneading step in the production of the toner particles. It is considered that this is because it becomes a more preferable state for the present invention.

Further, in order to enhance the effect of preventing "retransfer", the toner of the present invention has a shape factor SF-1 measured by an image analyzer of the toner of 110 to 180 (more preferably 120 to 120). 160), and the value of the shape factor SF-2 is 110 to 140 (more preferably 115 to 14).
0) and the value B obtained by subtracting 100 from the value of SF-2
And the ratio B / A of the value A obtained by subtracting 100 from the value of SF-1 must be 1.0 or less. The shape in the above range is a shape in which the toner surface is relatively smooth and has no unevenness. In the case of such a shape, it is considered that the iron oxide hydroxide fine particles externally added to the toner work more effectively and enhance the "retransfer" prevention effect.

When SF-1 is less than 110, S
When F-2 is less than 110 and B / A is less than 1.0, it becomes difficult to clean the transfer residual toner remaining on the latent image carrier, and cleaning failure is likely to occur. Further, when SF-1 exceeds 180, and S
If F-2 exceeds 140, further improvement of the "retransfer" preventing effect cannot be obtained sufficiently.

The toner of the present invention is sufficiently effective in preventing "retransfer" of the toner regardless of the shape of the toner, but the toner shape (SF-1, SF-2, B /
When A) satisfies the above range, the effect of preventing "retransfer" can be further enhanced by combining with the effect of preventing "retransfer" depending on the shape of the toner.

The following method can be used to bring the shape of the toner of the present invention into the above range.

Examples include a method in which toner particles are finely pulverized using a mechanical impact type fine pulverizing apparatus, and a method in jet type pulverization, in which the pulverizing pressure is lowered than usual to increase the number of circulations and finely pulverize. Also, a hot water bath method in which finely pulverized or further classified toner particles are dispersed in water and heated,
Examples thereof include a heat treatment method of passing a hot air stream and a mechanical impact method of applying mechanical energy.

Among these, the method of applying treatment by mechanical impact force is preferable. Examples of the process for applying a mechanical impact force include, for example, a method of applying a mechanical impact force to toner particles by a mechanical impact type crusher such as Kawasaki Heavy Industries, Ltd.'s Kryptron system or Turbo Industrial's turbo mill, and Hosokawa Micron. Like devices such as Mechanofusion System manufactured by Nara Machinery Co., Ltd. and hybridization system manufactured by Nara Machinery Co., Ltd., toner particles are pressed against the inside of the casing by centrifugal force with blades that rotate at high speed, and toner is compressed by a force such as a frictional force. A method of applying a mechanical impact force to the particles can be mentioned.

The treatment for applying mechanical impact force is particularly preferable when it is carried out after the step of pulverizing the toner particles or after the further classification step, because the effect of preventing "retransfer" is further enhanced. Further, it is considered that the mechanical impact treatment causes the surface of the toner particles to be in a “certain peculiar surface state” in which the action of the iron oxide hydroxide fine particles according to the present invention is more likely to work.

In the present invention, examples of the binder resin constituting the toner particles include the following. In the case of heat fixing toner, for example, polystyrene, poly-p
-Homopolymers of styrene such as chlorostyrene and polyvinyltoluene and substitution products thereof; styrene-vinylnaphthalene copolymers, styrene-acrylic acid ester copolymers, styrene-methacrylic acid ester copolymers, styrene-maleic acid ester copolymers Polymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-maleic acid copolymer, styrene-α-chloromethylmethacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinylmethyl Styrene-based copolymers such as ether copolymers, styrene-vinyl ethyl ether copolymers, styrene-vinyl methyl ketone copolymers, styrene-butadiene copolymers, styrene-isoprene copolymers, styrene-acrylonitrile indene copolymers Coalescing;
Polyvinyl chloride, phenol resin, natural modified phenol resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy resin, xylene resin, polyvinyl Butyral, tempen resin, coumarone indene resin, petroleum resin, etc. can be used.

Among these, the styrene copolymer is
The effect of preventing "retransfer" is further enhanced, which is particularly preferable.

It is considered that the styrene-based copolymer has a relatively low main-chain polarity and stabilizes the charging of the toner base. It is considered that this facilitates the effect of preventing "retransfer" of the iron oxide hydroxide fine particles of the present invention.

Examples of the comonomer for the styrene monomer of the styrene-based copolymer include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate,
Didecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide, etc. A monocarboxylic acid having a heavy bond or a substituted product thereof; acrylic acid such as acrylic acid, methacrylic acid, α-ethylacrylic acid and crotonic acid, and α- or β-alkyl derivatives thereof, fumaric acid, maleic acid, citraconic acid Unsaturated dicarboxylic acids and their monoester derivatives, maleic anhydride, etc. are available. Such monomers can be used alone or in admixture and copolymerized with other monomers to produce a desired polymer.

Among these, it is particularly preferable to use a monoester derivative of unsaturated dicarboxylic acid. More specifically, for example, monomethyl maleate, monoethyl maleate, monobutyl maleate, monooctyl maleate, monoallyl maleate, monophenyl maleate,
Α-, β such as monomethyl fumarate, monoethyl fumarate, monobutyl fumarate, monophenyl fumarate etc.
-Unsaturated dicarboxylic acid monoesters; alkenyldicarboxylic acids such as n-butenyl monosuccinate, n-octenyl monosuccinate, n-butenyl malonate monoethyl, n-dodecenyl glutarate monomethyl, n-butenyl adipate monobutyl and the like. Monoesters of aromatic dicarboxylic acids such as phthalic acid monomethyl ester, phthalic acid monoethyl ester, phthalic acid monobutyl ester, etc .; Vinyl such as vinyl chloride, vinyl acetate, vinyl benzoate, etc. Esters, for example, ethylene-based olefins such as ethylene, propylene, butylene, etc .; vinyl ketones, such as vinyl methyl ketone, vinyl hexyl ketone, etc .; for example, vinyl methyl ether, vinyl ethyl ether, vinyl iso Vinyl ethers such as Chirueteru; vinyl monomers are used alone or in combination.

As the crosslinking agent, a compound having two or more polymerizable double bonds is mainly used. For example, an aromatic divinyl compound such as divinylbenzene, divinylnaphthalene, etc .; for example, ethylene glycol diacrylate. , Ethylene glycol dimethacrylate,
Carboxylic acid esters having two double bonds such as 1,3-butanediol dimethacrylate; divinyl compounds such as divinylaniline, divinyl ether, divinyl sulfide, and divinyl sulfone; and compounds having three or more vinyl groups. It can be used alone or as a mixture.

The toner of the present invention is particularly effective in the case of a magnetic toner in which a magnetic material is contained in the toner particles.

In the present invention, the magnetic substance contained in the toner particles is preferably an alloy or compound powder containing a ferromagnetic element. For example, magnetite, maghemite,
Examples thereof include ferrites, alloys and compounds of iron, cobalt, nickel, manganese, zinc and the like, other ferromagnetic alloys, etc., which are conventionally known as magnetic materials.

The BET specific surface area of the magnetic substance by the nitrogen gas adsorption method is 1 to 40 m ² / g, further ^{2 to} 30 m ²
/ G is preferable.

The average particle size of the magnetic material is 0.05 to 1
μm, preferably 0.1 to 0.6 μm.

Further, the magnetic substance is the binder resin 1 in the toner particles.
It is preferable to contain 60 parts by mass to 200 parts by mass, more preferably 80 parts by mass to 150 parts by mass with respect to 00 parts by mass.

The toner particles of the present invention are particularly preferable when they contain magnetic iron oxide having a substantially spherical shape. Unlike the case where the state of dispersion of the magnetic substance in the binder resin in the melt-kneading step in the production is different from the case where the shape of the magnetic substance is other than substantially spherical, a specific surface state becomes a more preferable form, It is considered that the effect of preventing "retransfer" of the iron oxide hydroxide fine particles of the present invention becomes easier to work. The shape of the magnetic body is "almost spherical"
Using an electron micrograph of the magnetic substance, each particle (1
The average ratio of the major axis to the minor axis (major axis / minor axis) of 1.0 or more is 1.0 to 1.2.

In the toner of the present invention, a charge control agent can be used by blending with toner particles (internal addition) or by mixing with toner particles (external addition). The charge control agent makes it possible to control the optimum charge amount according to the developing system, and particularly in the present invention, the balance between the particle size distribution and the charge amount can be further stabilized. Examples of substances that control the toner to be negatively charged include the following substances.

Organic metal complexes and chelate compounds are effective, for example, monoazo metal complexes, acetylacetone metal complexes, aromatic hydroxycarboxylic acids, and aromatic dicarboxylic acid metal complexes. Other examples include aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids and their metal salts, anhydrides, esters, and phenol derivatives such as bisphenol.

In addition, in the toner of the present invention, it is preferable that the second inorganic fine powder is externally added to the toner particles for the purpose of adding fluidity to the toner.

The second inorganic fine powder is preferably contained in the developer by stirring and mixing the developer with a mixer such as a Henschel mixer.

As the second inorganic fine powder used in the present invention, inorganic fine powder such as silicic acid fine powder, titanium oxide, aluminum oxide and the like are preferable, and silicic acid fine powder is particularly preferable.
For example, as the silica fine powder, it is possible to use both a so-called dry method produced by vapor phase oxidation of a silicon halide or a dry silica called fumed silica, and a so-called wet silica produced from water glass or the like. However, dry silica having less silanol groups on the surface and inside the silica fine powder and having less production residue of Na ₂ O, SO ₃ ^2-, etc. is preferable. In dry silica,
By using other metal halogen compounds such as aluminum chloride and titanium chloride together with silicon halogen compounds in the manufacturing process, it is possible to obtain composite fine powders of silica and other metal oxides, and these are also included.

It is also possible to use one whose surface has been made hydrophobic beforehand with an organic compound. Examples of such an organic treatment method include a method of treating with an organic metal compound such as a silane coupling agent or a titanium coupling agent which reacts or physically adsorbs with the inorganic fine powder; or after treatment with a silane coupling agent, or silane A method of treating with a coupling agent and at the same time treating with an organosilicon compound such as silicone oil can be mentioned.

The second inorganic fine powder used in the present invention has a specific surface area of 30 m as measured by the BET method by nitrogen adsorption.
It is preferably ² / g or more, and particularly preferably in the range of 50 to 400 m ² / g.

The weight average particle diameter of the toner of the present invention is 10.0.
It is preferably not more than μm (preferably 8.0 μm). When the weight average particle diameter of the toner is 10.0 μm or less, the effect of preventing “retransfer” is further enhanced. It is considered that the reason is that the electrostatic charge latent image carrier before transfer or the toner on the intermediate transfer member is further charged.

In the production of the toner particles according to the present invention, the above-mentioned constituent materials are mixed in a mixing step using a mixer such as a Henschel mixer, a ball mill, a V-type mixer, a heat roll kneader and an extruder. A kneading process using a machine, a kneaded product after cooling and solidification, a crushing process using a crusher such as a jet mill, and a manufacturing process including at least the above processes are preferably performed.
Further, if necessary, it is also preferable to go through a classification step of the pulverized material.

Among these, a production method having at least a step of melt-kneading the binder resin and the other composition and a pulverization step of finely pulverizing the binder resin is particularly preferable in the production step.

In the melt-kneading step, when the endothermic peak in the differential thermal analysis is 120 ° C. or less, the dispersion state of the magnetic substance and the charge control agent in the binder resin becomes a preferable state for the present invention, and it should be crushed. This is because that particular peculiar state is exposed as it is on the surface of the toner particles, and the effect of preventing "retransfer" of the toner of the present invention is exhibited.

In the present invention, S indicating the shape factor of particles is used.
F-1 and SF-2 are, for example, FE-SE manufactured by Hitachi Ltd.
2 μm magnified 1000 times using M (S-800)
The above 100 toner images are randomly sampled, and the image information is introduced into an image analysis device (LuzexIII) manufactured by Nicolet Co., for example, through an interface and analyzed. Coefficient SF-1,
It is defined as SF-2.

[0070]

[Equation 1]

In the above formula, MXLNG is the absolute maximum length of the grain, PERIME is the perimeter of the grain, and AREA is the projected area of the grain.

The shape factor SF-1 indicates the degree of roundness of particles, and the shape factor SF-2 indicates the degree of unevenness of particles.

The endothermic peak in the differential thermal analysis according to the present invention is measured with a highly accurate internal heat input compensation type differential scanning calorimeter. For example, DSC-7 manufactured by Perkin Elmer
Can be used. The measuring method is ASTM D3418-8.
Perform according to 2. The DSC curve used in the present invention is 1
After the temperature was raised once and the previous history was taken, the temperature rate was 10 ° C / mi.
n, a DSC curve measured when the temperature is lowered and raised in the temperature range of 0 to 200 ° C is used. What is the endothermic peak temperature?
In the SC curve, it means the peak temperature in the positive direction, that is, the point at which the differential value of the peak curve becomes 0 when the value changes from positive to negative.

The weight average particle diameter of the toner of the present invention is measured by using Coulter Counter TA-II type or Coulter Multisizer (manufactured by Coulter Co.). As the electrolytic solution, a 1% NaCl aqueous solution is prepared using first grade sodium chloride. For example, ISOTONR-II (manufactured by Coulter Scientific Japan) can be used. As the measuring method, 0.1 to 5 ml of a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant to 100 to 150 ml of the electrolytic aqueous solution, and 2 to 5 measurement samples are further added.
Add 20 mg. The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and a 100 μm aperture is used as an aperture by the above-mentioned measuring device,
The volume distribution and the number distribution of the toner having a size of 2 μm or more were measured to calculate the volume distribution and the number distribution. Then, a weight-based weight average particle diameter D4 (the median value of each channel is set as a representative value for each channel) determined from the volume distribution according to the present invention was determined.

As a method for measuring the charge amount of fine particles according to the present invention, EFV200 / 300 (manufactured by Powder Deck Co., Ltd.) was used as a carrier in an environment of temperature: 23 ° C. and humidity: 60%, and a carrier of 10.0 g was used. Place 0.2 g of fine particles in a polyethylene container with a volume of 50 ml
Shake. Next, about 1 g of the mixture is put into a metal measuring container 2 having a 500 mesh screen 3 on the bottom as shown in FIG. At this time, the weight of the entire measuring container 2 is measured and designated as W ₁ [g]. Next, it is placed on a suction device (the portion in contact with the measurement container 2 is an insulator), suction is performed from the suction port 7 at a pressure of 2450 Pa (250 mmAq), and in this state, suction is performed for 2 minutes to remove fine particles by suction. The potential of the electrometer 9 at this time is V [volt].
Here, 8 is a capacitor, and the capacity is C [μF]. Weigh the entire measuring container 2 after suction and measure it with W ₂
[G]. The charge amount T [μC / g] of the fine particles is T [μ
Determined by C / g] = C × V / calculation formula (W ₁ -W _2).

In the present invention, the molecular weight distribution of wax is G
It is measured by the PC under the following conditions.

(GPC measurement conditions) Apparatus: GPC-150C (manufactured by Waters) Column: GMH-HT, 30 cm × 2 stations (manufactured by Tosoh Corporation) Temperature: 135 ° C. Solvent: o-dichlorobenzene (addition of 0.1% ionol) ) Flow rate: 1.0 ml / min Sample: 0.4 ml of 0.15% sample injected

The molecular weight calibration curve prepared by the monodisperse polystyrene standard sample is used to calculate the molecular weight of the sample measured under the above conditions. In addition, Mark-Hou
It is calculated by converting to polyethylene using a conversion formula derived from the wink viscosity formula.

In the present invention, the major axis and minor axis of the iron oxide hydroxide fine particles are measured as follows.

The iron oxide hydroxide fine particles were observed with an electron microscope or the like.
A photograph is taken at a magnification of 20,000 times or more, and the maximum longest diameter is measured as the major axis for 100 or more particles on the photograph, and the diameter in the direction perpendicular to the major axis of the particle is measured as the minor diameter. . The number average of the major axis and the ratio of the major axis and the minor axis of each particle is taken as the respective average value.

[0081]

EXAMPLES The present invention will now be described in more detail by way of examples, which should not be construed as limiting the invention.

[0082]   (Example 1)   Styrene-butyl acrylate-butyl maleate-half ester copolymer                                                             100 parts by mass   Magnetite (shape: spherical, average particle size: 0.2 μm) 100 parts by mass   Iron complex of monoazo dye (negative charge control agent) 2 parts by mass   Low molecular weight polyethylene (differential thermal analysis endothermic peak: 102 ° C,   Mw / Mn: 1.3) 4 parts by mass

After the above materials were premixed, they were melt-kneaded by a twin-screw kneading extruder set at 130 ° C. After cooling the kneaded product, it was roughly pulverized, finely pulverized by a pulverizer using a jet stream, and further classified by an air classifier. Further, the surface was treated with a mechanical impact force to obtain a black powder (toner particle) A.

Toner particles A: 100 parts by weight of fine particles 1 (hydrogenated iron oxide, crystal form: α type, average major axis:
0.8 μm, average of major axis / minor axis: 35, charge amount: −5
μC / g): 0.5 parts by mass, hexamethyldisilazane /
Dimethyl silicone oil treated dry silica: 1.2 parts by mass was stirred and mixed with Henschel mixer 10B at 3200 rpm for 2 minutes to obtain a toner.

The weight average particle diameter of the obtained toner is 6.8 μm.
m, SF-1 was 142, SF-2 was 123, and B / A was 0.55. The endothermic peak in the differential thermal analysis was 102 ° C.

Observation of the toner surface with an electron microscope showed that the iron oxide hydroxide fine particles were adhered to the surface of the toner particles in the original shape and were not embedded in the surface.

(Examples 2 to 6 and Comparative Examples 1 to 5) The fine particles 1 added in Example 1 are the same as the fine particles 2 to 2 shown in Table 1.
6 and fine particles 7 to 11 were obtained in the same manner as in Example 1 to obtain toners shown in Table 3.

(Examples 7 and 8) Toners shown in Table 3 were obtained in the same manner as in Example 1 except that the amount of the fine particles 1 added in Example 1 was changed to the amount shown in Table 3.

(Examples 9 to 15) Toner particles B to H were obtained in the same manner as in Example 1 except that the waxes shown in Table 2 were added instead of the low molecular weight polyethylene added in Example 1, and other than that. In the same manner as in Example 1, the toner shown in Table 3 was obtained.

(Examples 16 to 18) Example 16 was the same as Example 1 except that the mechanical shock treatment (toner particles I) performed in Example 1 was not performed, and the shape was adjusted by adjusting the conditions of the mechanical shock treatment. Similarly, toner particles I to K are obtained,
The toners shown in Table 3 were obtained in the same manner as in Example 1 except for the above.

[0091]   (Examples 19 and 20, Comparative Example 6)   Styrene-butyl acrylate copolymer 100 parts by mass   Magnetite (shape: spherical, average particle size: 0.2 μm) 80 parts by mass   2 parts by weight of triphenylmethane dye (positive charge control agent)   Low molecular weight polyethylene (differential thermal analysis endothermic peak: 102 ° C,   Mw / Mn: 1.3) 4 parts by mass

After the above materials were premixed, they were melt-kneaded by a twin-screw kneading extruder set at 130 ° C. After cooling the kneaded product, it was roughly pulverized, finely pulverized by a pulverizer using a jet stream, and further classified by an air classifier.

Further, the surface was treated with a mechanical impact force to obtain a black powder (toner particle) L.

To 100 parts by weight of the toner particles L, 0.5 parts by weight of each of the fine particles 1, 5, and 10 in Table 1, and dry silica treated with amino-modified silicone oil: 0.
3200r with 8 parts by mass with Henschel mixer 10B
The mixture was stirred and mixed at pm for 2 minutes to obtain a toner.

The weight average particle diameter of the obtained toner is 7.2 μm.
m, SF-1 was 144, SF-2 was 122, and the ratio B / A was 0.50. The endothermic peak in the differential thermal analysis was 102 ° C.

[0096]   (Comparative Example 7)   Polyester resin (condensation polymer of propoxylated bisphenol and fumaric acid)                                                           100 parts by mass   Magnetite (shape: octahedron, average particle size: 0.2 μm) 60 parts by mass   Iron complex of monoazo dye (negative charge control agent) 2 parts by mass   Low molecular weight polypropylene (differential thermal analysis endothermic peak: 145 ° C,   Mw / Mn: 8.8) 4 parts by mass

After the above materials were premixed, they were melt-kneaded by a twin-screw kneading extruder set at 130 ° C. The kneaded product was cooled, coarsely pulverized, finely pulverized by a pulverizer using a jet stream, and further classified by an air classifier to obtain a black powder (toner particles) M.

To 100 parts by mass of the toner particles M, 0.4 parts by mass of dry silica treated with hexamethyldisilazane / dimethylsilicone oil was stirred and mixed with a Henschel mixer 10B at 3200 rpm for 2 minutes to obtain a toner. .

The weight average particle diameter of the obtained toner is 11.3.
μm, SF-1 was 165, SF-2 was 155, and B / A was 0.85. The endothermic peak in the differential thermal analysis was 145 ° C.

<Evaluation> The toners of the above Examples and Comparative Examples were evaluated by the following methods. The results are shown in Table 4.

1) Evaluation of transferability Laser beam printer LBP-1260 manufactured by Canon Inc.
Was modified and a device equipped with a variable transfer bias power source was used to develop a solid black image in an environment of 30 ° C / 80% RH,
Transfer the image onto a transfer paper of 65 g / m ² and peel off the transfer residual image left on the photoconductor with a transparent polyester adhesive tape and paste it on a white paper, and measure the reflection density with a Macbeth reflection densitometer Was evaluated by the value obtained by subtracting the density of the portion where only the tape was applied on a white paper. The transfer voltage was evaluated in steps of 0.5 kV from 1.0 to 3.0 kV.

2) Evaluation of Image Density / Fog Laser Beam Printer LBP-1260 manufactured by Canon Inc.
And Canon Canon copier PC330 at 32 ℃ / 80
After 1,000 sheets were printed in an environment of 100% and left for 2 days, a solid black image was printed, and the image density was measured by a Macbeth reflection densitometer and evaluated.

In addition, the difference in whiteness on the unused transfer paper measured by a reflectometer (manufactured by Tokyo Denshoku Co., Ltd.) simultaneously with printing a solid white image and the whiteness of the transfer paper after printing the solid white. Fog was evaluated from.

[0104]

[Table 1]

[0105]

[Table 2]

[0106]

[Table 3]

[0107]

[Table 4]

[0108]

According to the present invention, "retransfer" does not occur even under a high transfer current condition, and an image having a high image density and good image quality can be obtained.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an apparatus for measuring a charge amount of toner according to the present invention.

[Explanation of symbols]

1 suction machine 2 measuring vessels 3 Conductive screen (500 mesh) 4 lid 5 vacuum gauge 6 Air flow control valve 7 Suction port 8 capacitors 9 electrometer

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03G 9/08 384 F term (reference) 2H005 AA01 AA02 AA06 AA08 AB04 AB09 CA03 CA13 CA14 CB03 EA01 EA03 EA05 EA06 EA10 FA06

Claims (20)

[Claims] 1. A toner having toner particles containing at least a binder resin and a colorant and needle-shaped iron oxide hydroxide fine particles externally added to the toner particles, wherein the iron hydroxide oxide fine particles have an average major axis of 0.2. To 2.0 μm, the average of the ratio of major axis to minor axis is 5 to 60, and the toner has one or more endothermic peaks in differential thermal analysis at 120 ° C. or less. 2. The toner according to claim 1, wherein the charged polarity of the iron oxide hydroxide fine particles with respect to the iron powder carrier is the same as the charged polarity of the toner particles with respect to the iron powder carrier. 3. The toner according to claim 1, wherein a charge amount of the iron oxide hydroxide fine particles with respect to an iron powder carrier is | 20 | μC / g or less. 4. The toner according to claim 1, wherein the charge amount of the iron oxide hydroxide fine particles with respect to the iron powder carrier is | 10 | μC / g or less. 5. The toner according to claim 1, wherein the iron oxide hydroxide fine particles are α-type iron oxide hydroxide. 6. The toner according to claim 1, wherein the toner has one or more endothermic peaks in a differential thermal analysis in a region of 60 ° C. to 120 ° C. 7. The toner according to claim 6, wherein the toner has one or more endothermic peaks in a differential thermal analysis in a region of 70 ° C. or higher. 8. The toner according to claim 6, wherein the toner has one or more endothermic peaks in a differential thermal analysis in a region of 110 ° C. or lower. 9. The toner particles contain at least one wax component selected from the group consisting of polyolefin wax, Fischer-Tropsch hydrocarbon wax, petroleum wax and higher alcohols. 9. The toner according to any one of 1 to 8. 10. The wax component has a Mw / Mn in a range of 1.0 to 2.0 in a molecular weight distribution measured by gel permeation chromatography (GPC). Toner. 11. The toner has a shape factor SF-1 of 110 to 180 and a shape factor SF-2 of 110 to 140 measured by an image analyzer, and SF Value B minus SF minus 100 and SF-
The toner according to any one of claims 1 to 10, wherein the ratio B / A with the value A obtained by subtracting 100 from the value of 1 is 1.0 or less. 12. The toner has a shape factor SF-1 of 120 to 160 and a shape factor SF-2 of 115 to 140 as measured by an image analyzer, and SF Value B minus SF minus 100 and SF-
The toner according to any one of claims 1 to 10, wherein the ratio B / A with the value A obtained by subtracting 100 from the value of 1 is 1.0 or less. 13. The toner according to claim 1, wherein a styrene-based copolymer is used as the binder resin. 14. A magnetic material is contained in the toner particles as the colorant.
The toner according to any one of 1. 15. The toner according to claim 14, wherein the magnetic substance is magnetic iron oxide having a substantially spherical shape. 16. The toner has a weight average particle diameter of 10.0.
The toner according to any one of claims 1 to 15, wherein the toner has a thickness of not more than μm. 17. The toner has a weight average particle diameter of 8.0 μm.
The toner for developing an electrostatic charge image according to any one of claims 1 to 15, wherein the toner has a particle size of m or less. 18. The toner particles are obtained through a manufacturing process including at least a step of melt-kneading a binder resin and a colorant and a step of crushing the same. 17. The toner according to any one of 17. 19. The toner according to claim 1, wherein the toner particles are subjected to a spheroidizing treatment that applies at least a mechanical impact force. 20. The toner according to claim 19, wherein the toner particles have been subjected to a spheroidizing treatment for applying a mechanical impact force after the pulverizing step.